Switchable privacy display

Abstract

The switchable privacy display device comprises a spatial light modulator and a switchable diffraction field-of-view retarder configuration positioned between the display polarizer of the spatial light modulator and an additional polarizer. The display achieves high image visibility to off-axis users in shared operating mode and high image security to off-axis eavesdroppers in privacy operating mode.

Description

[Technical Field]

[0001] This disclosure relates to optical stacks for use in privacy displays and low stray light displays in general. [Background technology]

[0002] Privacy displays typically provide image visibility to the primary user, who is usually positioned on the axis, and reduce the visibility of image content to eavesdroppers, who are usually positioned off the axis.

[0003] A switchable privacy display may be provided by controlling the off-axis light output.

[0004] Off-axis privacy control can be provided by contrast reduction, for example, by adjusting the liquid crystal bias slope in an in-plane switching LCD.

[0005] Control may be further provided by off-axis luminance reduction. Luminance reduction can be achieved by a switchable backlight for a liquid crystal display (LCD) spatial light modulator. Off-axis luminance reduction may also be provided by a switchable liquid crystal retarder and compensating retarder arranged to modulate the input and / or output directional luminance profiles of the spatial light modulator.

[0006] Control may be further provided by increasing the off-axis reflectivity. This increase in reflectivity can be achieved by a switchable liquid crystal retarder and a compensating retarder positioned to control the polarization of ambient light hitting the reflective polarizer. [Overview of the Initiative]

[0007] According to a first aspect of the present disclosure, a display device comprising: a spatial light modulator (SLM) disposed to output spatially modulated light; a display polarizer disposed on one side of the SLM, which is a linear polarizer; an additional polarizer disposed on the same side of the SLM as the display polarizer, which is a linear polarizer; and a switchable diffraction field angle control retarder configuration (SDVACRA) disposed between the additional polarizer and the display polarizer, which comprises a liquid crystal material layer and a switchable diffraction liquid crystal retarder (SDLCR) comprising a transparent electrode configuration disposed to drive the liquid crystal material layer, wherein the transparent electrode configuration selectively drives the liquid crystal material layer, and the liquid crystal material layer is liquid A display device is provided, which is patterned to be able to be driven to a narrow-angle state having an orientation structure that introduces a net phase shift uniform across the region of the liquid crystal material layer into light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to light having a predetermined polarization state, and introducing different net relative phase shifts along the field axis and a tilt axis tilted with respect to the field axis into the orthogonal polarization components of light having a predetermined polarization state to SDVACRA, and a wide-angle state having an orientation structure that introduces a net phase shift that varies spatially across the region of the liquid crystal material layer into light having a predetermined polarization state, thereby causing the liquid crystal material layer to provide a diffraction effect to light having a predetermined polarization state.

[0008] In one operating mode of a display device, a narrow-angle state may be provided. Display images that are visible with high image visibility may be provided to the viewer along the field of view axis or at an angle close to the field of view axis. Viewers viewing from a direction inclined with respect to the field of view axis can see images without perceiving the image data, with high image security. A privacy operating mode may be provided to prevent voyeurs from viewing the displayed images. A passenger infotainment display in a vehicle may be provided to reduce driver distraction by displaying images to passengers. A low-stray-light operating mode may be provided to reduce ambient illumination from light emitted from the display device. In another operating mode of the display device, a wide-angle state may be provided. Display images that are visible with high image visibility from a wide range of viewing positions may be provided. A shared operating mode may be provided, allowing multiple viewers to view the displayed information simultaneously and comfortably. Switching between narrow-angle and wide-angle states may be provided. The display device may be segmented so that the operating state differs from other operating states in several areas. In one operating mode, some areas of the display device may provide a narrow-angle state, while other areas may provide a wide-angle state. In another operating mode, the entire display device may provide either a narrow-angle or wide-angle operation. Advantageously, an increase in the functionality of the display device can be achieved.

[0009] The number of layers required to achieve a desirable security factor in narrow-angle conditions and a desirable image visibility in wide-angle conditions can be reduced. Thinner, lighter, and lower-cost display devices can be provided. The gaps between segmented regions of the display device can be reduced.

[0010] The transparent electrode configuration can be patterned to selectively drive the liquid crystal material layer into an intermediate state having an orientation structure that allows the liquid crystal material layer to introduce a net phase shift uniform across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to light having a predetermined polarization state, and also allowing the SDVACRA to introduce a net relative phase shift that is the same along the field axis and tilt axis to the orthogonal polarization component of light having a predetermined polarization state.

[0011] Compared to a narrow-angle state, the display may be visible from an expanded viewing angle. Compared to a wide-angle state, the display brightness may be increased for the viewer along the viewing axis, and / or power consumption may be reduced. In one operating mode, some areas of the display device may provide one of the following: a narrow-angle state, a wide-angle state, or an intermediate state. In another operating mode, the entire display device may provide the same state of operation. Advantageously, an increase in the functionality of the display device may be achieved.

[0012] In the wide-angle state, the orientation structure of the liquid crystal material layer can introduce a net phase shift that spatially varies in one direction across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby causing a unidirectional diffraction effect on the liquid crystal material layer.

[0013] Brightness in wide-angle conditions may be increased for viewers along the field of view axis. Efficiency in wide-angle conditions may be increased, and stray light in a direction perpendicular to one direction may be reduced. This direction can be the horizontal axis, which provides desirable performance at horizontally spaced locations of the viewer.

[0014] The permeable electrode configuration may comprise at least one isolation electrode array. The isolation electrodes can be manufactured by known manufacturing processes that are low-cost and complex.

[0015] At least one isolation electrode array may be arranged in one direction, and the isolation electrodes may extend across the region of the liquid crystal material layer in a direction orthogonal to that direction. The isolation electrodes may have a common connection. The common connection may be formed by a bar located outside the region of the SLM. Electrical connections to the isolation electrodes may be conveniently provided at low cost and with minimal complexity.

[0016] At least one isolation electrode array may comprise two mutually mated isolation electrode sets. At least one isolation electrode array may comprise two isolation electrode arrays on either side of the SDLCR, each comprising two mutually mated isolation electrode sets. Each isolation electrode set may have a common connection. The common connection of each isolation electrode set may be formed by a bar, which is located outside the region of the SLM on both sides of the liquid crystal material layer. Further control of the orientation structure of the liquid crystal material layer may be provided to achieve alternative profiles of diffracted light. Asymmetric diffraction patterns may be provided to achieve improved control of light output in the non-viewpoint direction, primarily on one side of the optical axis of the display device. Increased display functionality may be provided.

[0017] The isolation electrodes can be spaced close enough to generate an electric field that can uniformly drive the liquid crystal material layer into a narrow-angle state by applying a common voltage to the liquid crystal material layer. This can reduce the cost and complexity of the electrode configuration and lower power consumption.

[0018] The transparent electrode configuration may further include control electrodes extending throughout the SLM, which are located outside the separation electrode array and on the same side of the liquid crystal material layer as the separation electrode array. The electric field profile within the liquid crystal material layer can be modified, and the diffraction angle can be increased with respect to the desired pitch of the separation electrodes.

[0019] The transparent electrode configuration may further include a reference electrode extending throughout the SLM, the reference electrode being positioned on the opposite side of the liquid crystal material layer from the isolation electrode array. The liquid crystal material layer may be switched between structures with different orientations to achieve desired wide-angle and narrow-angle operating states.

[0020] The display device may further include a control system arranged to supply voltage to a transparent electrode configuration in order to drive a liquid crystal material layer. The control system may be arranged to supply a voltage to the transparent electrode configuration selected to drive the liquid crystal material layer to a narrow angle state in the narrow-angle state, and to supply a voltage to the transparent electrode configuration selected to drive the liquid crystal material layer to a wide-angle state in the wide-angle state. The liquid crystal layer may be controlled to provide an output light cone for wide-angle, narrow-angle, or intermediate operating states. The size of the output light cone of the display device in each mode may be adjusted to achieve desired viewing characteristics.

[0021] A switchable liquid crystal retarder comprises two surface alignment layers adjacent to and positioned on both sides of a liquid crystal material layer, each surface alignment layer being arranged to provide alignment to the adjacent liquid crystal material. The surface alignment layer on one side of the liquid crystal material layer adjacent to the isolation electrode array may have an alignment component in the plane of the liquid crystal material layer in a direction that can be orthogonal to one direction. The direction of brightness reduction in narrow-angle privacy mode may be provided in one direction. For display devices where one direction is horizontal, the vertical viewing freedom may be increased. The surface alignment layers may be selected to provide desirable low transmittance in the tilt direction in the narrow-angle state and desirable high transmittance in the wide-angle state.

[0022] At least one of the surface alignment layers may be arranged to provide homogeneous alignment in adjacent liquid crystal materials. This can reduce the visibility of artifacts arising from the flow of liquid crystal materials during compression.

[0023] Each surface alignment layer may be arranged to provide homogeneous alignment of adjacent liquid crystal materials, the liquid crystal material layer of the SDLCR may have a retardation in the range of 500 nm to 900 nm for light with a wavelength of 550 nm, and the SDLCR may further comprise either a passive single-axis retarder having an optical axis perpendicular to the plane of the retarder and a retardation in the range of -300 nm to -700 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders having optical axes in the plane of intersecting retarders and each having a retardation in the range of 300 nm to 800 nm for light with a wavelength of 550 nm. The angle in the tilt direction may be reduced so that the minimum transmission and a desired security factor can be achieved.

[0024] One of the surface alignment layers may be arranged to provide homogeneous alignment of adjacent liquid crystal materials, and the other of the surface alignment layers may be arranged to provide homeotropic alignment of adjacent liquid crystal materials. The liquid crystal material layer of the SDLCR may have a retardation range of 700 nm to 2000 nm for light with a wavelength of 550 nm. The SDLCR may further comprise either a passive single-axis retarder having an optical axis perpendicular to the plane of the retarder and a retardation range of -300 nm to -1800 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders having optical axes in the plane of intersecting retarders, each having a retardation range of 300 nm to 1800 nm for light with a wavelength of 550 nm. The size of the polar region for which a desirable security factor is achieved can be increased. Increased optical dispersion can be achieved, and advantageously, image visibility can be increased in the wide-angle state.

[0025] Each surface alignment layer may be arranged to provide homeotropic alignment of adjacent liquid crystal materials, the liquid crystal material layer of the SDLCR may have a retardation in the range of 500 nm to 1000 nm for light with a wavelength of 550 nm, and the SDLCR may further comprise either a passive single-axis retarder having an optical axis perpendicular to the plane of the retarder and a retardation in the range of -300 nm to -900 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders having optical axes in the plane of intersecting retarders and each having a retardation in the range of 300 nm to 800 nm for light with a wavelength of 550 nm. The angle in the tilt direction may be reduced so that the minimum transmission and a desired security factor can be achieved.

[0026] SDVACRA may further include at least one passive compensation retarder. In wide-angle conditions, the size of the polar region where the desired image visibility is provided may be increased.

[0027] The liquid crystal material area extends throughout the entire SLM. The cost and complexity of the electrode configuration and control system can be reduced.

[0028] The viewing axis may be perpendicular to the plane of the SLM. A symmetrical display device may be provided. The normal viewing direction of the main viewer may be facing the front of the display device.

[0029] The display device may further comprise a backlight arranged to output light, and the SLM may be a transmissive SLM arranged to receive output light from the backlight. The backlight may provide brightness at extreme angles with respect to the SLM normal greater than 45 degrees, which may be up to 30% of the brightness along the SLM normal, preferably up to 20% of the brightness along the SLM normal, and most preferably up to 10% of the brightness along the SLM normal. A highly efficient display device may be provided. Low power consumption may be achieved for desired image brightness. Desired image brightness at angles greater than 45 degrees may be achieved in wide-angle conditions.

[0030] The display polarizer may be an input display polarizer positioned on the input side of the SLM, and additional polarizers and SDVACRAs may be positioned between the backlight and the SLM. Frontal reflection visibility may be reduced, and image contrast may be increased. Direct sunlight reflection visibility may be reduced, improving the safety of the display for the vehicle driver.

[0031] The display polarizer may be an output display polarizer located on the output side of the SLM. Additional polarizers and switchable liquid crystal retarders may be added to the SLM as needed during or after manufacturing. An increased security factor can be achieved for a given ambient light.

[0032] The display device may further include a reflective polarizer disposed between the output display polarizer and the SDVACRA, wherein the reflective polarizer is a linear polarizer. In privacy operating mode, low reflectivity along the on-axis direction may be achieved, and high reflectivity along the non-viewpoint direction tilted in the on-axis direction may be achieved. The size of the polar region in which the desired security coefficient is achieved may be increased.

[0033] SDVACRA may further comprise a further switchable liquid crystal retarder having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder, the further transparent electrode configuration may selectively drive the liquid crystal material layer of the further switchable liquid crystal retarder into a narrow-angle state in which the liquid crystal material layer may have an orientation structure that causes the further switchable liquid crystal retarder to introduce a net relative phase shift that varies along the viewing axis and tilt axis into the orthogonal polarization component of light having a predetermined polarization state, and into a wide-angle state in which the liquid crystal material layer may have an orientation structure that causes the further switchable liquid crystal retarder to introduce the same net relative phase shift along the viewing axis and tilt axis into the orthogonal polarization component of light having a predetermined polarization state. Light dispersion in the wide-angle state may be increased. Image visibility for tilted viewers may be increased.

[0034] The display device may further comprise a further additional polarizer, which is a linear polarizer, located on the same side as the first additional polarizer mentioned in the SLM and disposed either a) between the display polarizer and the first SDVACRA, or b) outside the first additional polarizer, and a further switchable liquid crystal retarder configuration, which may be disposed either a) between the further additional polarizer and the display polarizer if the further additional polarizer can be disposed between the display polarizer and the first SDVACRA, or b) between the first additional polarizer and the further additional polarizer if the further additional polarizer can be disposed outside the first additional polarizer, and further switchable liquid crystal retarder configuration The retarder configuration may comprise a further switchable liquid crystal retarder having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder configuration, the further transparent electrode configuration may selectively drive the liquid crystal material layer of the further switchable liquid crystal retarder into a narrow-angle state in which the liquid crystal material layer may cause the further switchable liquid crystal retarder configuration to have a net relative phase shift that varies along the field axis and tilt axis to the orthogonal polarization component of light having a predetermined polarization state, and a wide-angle state in which the liquid crystal material layer may have an orientation structure in which the further switchable liquid crystal retarder to have a net relative phase shift that is the same along the field axis and tilt axis to the orthogonal polarization component of light having a predetermined polarization state. In the narrow-angle state, transmission may be reduced along the tilt axis. Increased image security may be achieved.

[0035] The display device may further comprise a backlight disposed to output light, the SLM may be a transmissive SLM disposed to receive output light from the backlight, the first-mentioned display polarizer may be either a) an input polarizer or b) an output polarizer, the display device may further comprise a further display polarizer which may be either a) an output polarizer if the first display polarizer is an input polarizer, or b) an input polarizer if the first display polarizer is an output polarizer, the display device may further comprise a further additional polarizer disposed either a) on the output side of the output polarizer if the first display polarizer is an input polarizer, or b) between the input polarizer and the backlight if the first display polarizer is an output polarizer, the display device may further comprise a further additional polarizer and further display The system may further include a further switchable liquid crystal retarder configuration which can be disposed between the ray polarizer and the system, the further switchable liquid crystal retarder configuration which includes a further switchable liquid crystal retarder comprising a liquid crystal material layer and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder, the further transparent electrode configuration which can selectively drive the liquid crystal material layer of the further switchable liquid crystal retarder into a narrow-angle state in which the liquid crystal material layer may have an orientation structure that causes the further switchable liquid crystal retarder configuration to introduce a net relative phase shift that varies along the field axis and the tilt axis into the orthogonal polarization component of light having a predetermined polarization state, and into a wide-angle state in which the liquid crystal material layer may have an orientation structure that causes the further switchable liquid crystal retarder configuration to introduce a net relative phase shift that is the same along the field axis and the tilt axis into the orthogonal polarization component of light having a predetermined polarization state. In the narrow-angle state, transmission may be reduced along the tilt axis. Increased image security may be achieved. Display efficiency may be increased.

[0036] Further switchable liquid crystal retarders may be SDLCRs, and in the narrow-angle state, the liquid crystal material layer may have an orientation structure that causes the liquid crystal material layer to introduce a net phase shift uniform across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to light having a predetermined polarization state. In the wide-angle state, the liquid crystal material layer may have an orientation structure that causes the liquid crystal material layer to introduce a net phase shift that varies spatially across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby allowing the liquid crystal material layer to provide a diffraction effect to light having a predetermined polarization state. Increased image visibility to tilted viewers in the wide-angle state and improved security coefficient in the narrow-angle state can be achieved.

[0037] Further switchable liquid crystal retarders may be switchable non-diffractive liquid crystal retarders (SNDLCRs), in which, in both the narrow-angle and wide-angle states, the liquid crystal material layer may have an orientation structure that causes the liquid crystal material layer to introduce a net phase shift to light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to light having a predetermined polarization state. Cost and complexity may be reduced, and an improved security factor in the narrow-angle state may be achieved.

[0038] SDVACRA may further comprise a switchable diffractive liquid crystal element (SDLCE) having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the SDLCE, the further transparent electrode configuration may be patterned to selectively drive the liquid crystal material layer of the further SDLCR into a non-diffractive state in which the liquid crystal material layer may have an orientation structure that causes the liquid crystal material layer to introduce a net phase shift uniform across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to light having a predetermined polarization state, and a wide-angle state in which the liquid crystal material layer may have an orientation structure that causes the liquid crystal material layer to introduce a net phase shift that varies spatially across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to light having a predetermined polarization state. In the wide-angle state, light dispersion may be increased, and image visibility may be improved for viewers along the tilt axis.

[0039] According to a second aspect of this disclosure, a display device comprising: an SLM disposed to output spatially modulated light; a display polarizer disposed on one side of the SLM, which is a linear polarizer; an additional polarizer disposed on the same side of the SLM as the display polarizer, which is a linear polarizer; an SNDLCR configuration (SNDLCRA) disposed between the additional polarizer and the display polarizer, which comprises a liquid crystal material layer; and a transparent electrode configuration in which the liquid crystal material layer is selectively varied in the SDNLCRA along the field axis and a tilt axis tilted to the field axis. A display device is provided, comprising an SNDLCRA having a transmissive electrode configuration arranged to drive the SNDLCRA to a narrow-angle state which introduces a net relative phase shift into the orthogonal polarization component of light having a predetermined polarization state, and a wide-angle state which introduces a net relative phase shift, which is the same along the viewing axis and the tilt axis, into the orthogonal polarization component of light having a predetermined polarization state, and an SNDLCRA having a transmissive electrode configuration arranged to drive the SNDLCRA to a narrow-angle state which introduces a net relative phase shift, which is the same along the viewing axis and the tilt axis, into the orthogonal polarization component of light having a predetermined polarization state, and an SLM, a display polarizer, an additional polarizer, and a switchable optical dispersion configuration (SLDA) arranged in series with the SNDLCRA which is switchable between a non-dispersive state which does not provide light dispersion and a dispersed state which provides light dispersion.

[0040] In one operating mode of a display device, a narrow-angle state may be provided. Display images that are visible with high image visibility may be provided to the viewer along the field of view axis or at an angle close to the field of view axis. Viewers viewing from a direction inclined with respect to the field of view axis can see images without perceiving the image data, with high image security. A privacy operating mode may be provided to prevent voyeurs from viewing the displayed images. A passenger infotainment display in a vehicle may be provided to reduce driver distraction by displaying images to passengers. A low-stray-light operating mode may be provided to reduce ambient illumination from light emitted from the display device. In another operating mode of the display device, a wide-angle state may be provided. Display images that are visible with high image visibility from a wide range of viewing positions may be provided. A shared operating mode may be provided, allowing multiple viewers to view the displayed information simultaneously and comfortably. Switching between narrow-angle and wide-angle states may be provided. The display device may be segmented so that the operating state differs from other operating states in several areas. In one operating mode, some areas of the display device may provide a narrow-angle state, while other areas may provide a wide-angle state. In another operating mode, the entire display device may provide either a narrow-angle or wide-angle operation. Advantageously, an increase in the functionality of the display device can be achieved. Thinner, lighter, and lower-cost display devices can be provided.

[0041] SLDA can provide unidirectional dispersion of light across the liquid crystal material layer. Brightness in wide-angle conditions may be increased for viewers along the viewing axis. Efficiency in wide-angle conditions may be increased, and stray light in directions perpendicular to the unidirectional direction may be reduced. The unidirectional direction can be the horizontal axis or the lateral direction to provide desirable performance at horizontally spaced locations of the viewer.

[0042] The display device may further comprise a control system configured to supply voltage to a transparent electrode configuration to drive a liquid crystal material layer and to control the SLDA. The control system may be configured to, in the narrow-angle state of the display device, supply a voltage to the transparent electrode configuration selected to drive the liquid crystal material layer of SNDLCR to its narrow-angle state and switch the SLDA to a non-dispersive state, and in the wide-angle state of the display device, supply a voltage to the transparent electrode configuration selected to drive the liquid crystal material layer of SNDLCR to its wide-angle state and switch the SLDA to a dispersed state. The SLDA and SNDLCRA may be controlled to provide an output optical cone for wide-angle, narrow-angle, or intermediate operating states, respectively. The size of the output optical cone of the display device in each mode may be adjusted to achieve desired viewing characteristics.

[0043] SLDA can be a diffractive element that provides light dispersion by diffraction in a dispersed state. SLDA can be an SDLCE comprising a liquid crystal material layer and a transparent electrode configuration arranged to drive the liquid crystal material layer, wherein the transparent electrode configuration can be patterned to selectively drive the liquid crystal material layer into a non-diffractive state corresponding to the non-dispersive state of SLDA, having an orientation structure that causes the liquid crystal material layer to introduce a net phase shift uniform across the region of the liquid crystal material layer into light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing dispersion of light having a predetermined polarization state; and a diffractive state corresponding to the dispersed state of SLDA, having an orientation structure that causes the liquid crystal material layer to introduce a net phase shift spatially varying across the region of the liquid crystal material layer into light having a predetermined polarization state, thereby causing the liquid crystal material layer to provide light dispersion by diffraction effect. Thin, low-cost SLDAs can be provided. The cost and complexity of the electrode configuration, as well as power consumption, can be reduced.

[0044] SLDA can be a refractive element that provides dispersion of light by refraction in a dispersed state. SLDA may comprise a birefringent layer of a birefringent material having an ordinary refractive index and an extraordinary refractive index, an isotropic layer of an isotropic material having an interface with the birefringent layer, wherein the isotropic material may have a refractive index equal to the ordinary or extraordinary refractive index of the birefringent material, and the interface surface may have a dispersive surface relief, and a polarization control element disposed to selectively control the polarization of light passing through the SLDA between a first polarization state experiencing the ordinary refractive index of the birefringent layer and a second polarization state experiencing the extraordinary refractive index of the birefringent layer.

[0045] Surface relief can be due to diffraction dispersion. Surface relief can be a lens profile, prism profile, random profile, or designed profile. Thin, low-cost passive optical elements can be provided with a desired interface surface relief structure. Birefringent and isotropic materials can be hardened to achieve a stable structure that does not change its optical structure under pressure and to achieve improved robustness. Visibility of diffraction color artifacts can be reduced. A desirable profile of optical dispersion with low color variation can be achieved. Surface relief can be due to diffraction dispersion. Increased dispersion can be provided, and improved visibility to tilted viewers can be achieved.

[0046] The SLDA can be positioned between the display polarizer and an additional polarizer. The SLDA may have dispersion characteristics independent of the liquid crystal material layer of the SNDLCR, achieving improved image visibility performance in the wide-angle state and an increase in the size of the polar region for a desirable security factor in the privacy mode in the narrow-angle state.

[0047] The display device may further include a backlight arranged to output light, the SLM may be a transmissive SLM arranged to receive the output light from the backlight, and the display polarizer may be an input display polarizer arranged on the input side of the SLM. A highly efficient display device can be provided. Low power consumption can be achieved for desired image brightness.

[0048] The SLDA may be positioned outside the additional polarizer, on the same side as the display polarizer in the SLM. The display device may further include a backlight positioned to output light, the SLM may be a transmissive SLM positioned to receive output light from the backlight, the display polarizer may be an input display polarizer positioned on the input side of the SLM, and the SLDA, additional polarizer, and SNDLCRA may be positioned between the backlight and the SLM. Stray light may be reduced so that transmission in narrow-angle conditions in the tilt direction can be reduced, achieving an increased security factor.

[0049] The display polarizer may be an output display polarizer located on the output side of the SLM, and the SLDA may be located between the backlight and the SLM. The image fidelity of the information perceived on the SLM can be maintained.

[0050] The display device may further include a reflective polarizer disposed between the output display polarizer and the SNDLCRA, wherein the reflective polarizer is a linear polarizer. In the narrow-angle state of the privacy mode, low reflectivity along the on-axis direction may be achieved, and high reflectivity along the non-viewpoint direction tilted in the on-axis direction may be achieved. The size of the polar region in which the desired security coefficient is achieved may be increased.

[0051] SNDLCRA may further include at least one passive compensation retarder. In wide-angle conditions, the size of the polar region where the desired image visibility is provided may be increased.

[0052] Embodiments of the present disclosure can be used in a variety of optical systems. These embodiments may include, or operate with, various projectors, projection systems, optical components, displays, microdisplays, computer systems, processors, self-contained projector systems, visual and / or audiovisual systems, and electrical and / or optical devices. Embodiments of the present disclosure may be used in substantially any device relating to optical and electrical devices, optical systems, presentation systems, or any device that may include any type of optical system. Thus, embodiments of the present disclosure can be used in optical systems, devices used in visual and / or optical presentations, visual peripherals, and a number of computing environments.

[0053] Before proceeding to details of the disclosed embodiments, it should be understood that the disclosure is not limited to the specific arrangement details shown in its application or creation, as other embodiments are possible. Furthermore, aspects of this disclosure may be described in different combinations and arrangements to define their own unique embodiments. Also, the terms used herein are for illustrative purposes only and not for limitation.

[0054] Directional backlights control illumination emanating from substantially the entire output surface, typically controlled through modulation of independent LED light sources positioned on the input aperture side of an optical waveguide. By controlling the directional distribution of emitted light, it is possible to achieve single-viewer viewing for security purposes, where only one viewer can view the display from a limited angular range; high electrical efficiency, where illumination is provided primarily with a small angular directional distribution; alternating left and right eye viewing for time-series stereoscopic and auto-stereoscopic displays; and low cost.

[0055] These and other advantages and features of this disclosure will become apparent to those skilled in the art by reading the entire disclosure.

[0056] Embodiments are shown as examples in the attached figures, and similar reference numerals indicate similar parts. [Brief explanation of the drawing]

[0057] [Figure 1A] This schematic diagram illustrates a switchable display device in an oblique side view, comprising a backlight with a light source array, waveguide, back reflector, and light redirection components; a switchable diffractive field-of-view control retarder configuration (SDVACRA) with a switchable diffractive liquid crystal retarder (SDLCR) and passive compensation retarder; and a transmissive spatial light modulator (SLM). [Figure 1B] This is a schematic diagram illustrating the SDLCR components in an oblique side view. [Figure 1C] This is a schematic diagram illustrating the alignment orientation of an optical stack for use in the display device shown in Figure 1A, illustrated in a perspective front view. [Figure 1D] This schematic diagram illustrates the electrode and liquid crystal material structure of SDLCR in non-driving mode, as shown in a perspective front view. [Figure 1E] Figure 1A is a schematic diagram illustrating the permeable electrode configuration for the SDLCR in a perspective side view. [Figure 1F] This is a schematic diagram illustrating an alternative configuration for a permeable separation electrode, shown in a front view. [Figure 2A] This is a schematic diagram illustrating the structure and operation of an optical stack equipped with an SDVACRA having an SDLCR with the electrode configuration shown in Figure 1E, in the wide-angle state, as shown in a top view. [Figure 2B] This schematic diagram illustrates the structure of the transparent electrode configuration and liquid crystal material orientation for SDLCR under wide-angle conditions, as shown in a perspective front view. [Figure 2C] Tables 2-3 illustrate schematic diagrams illustrating the transparent electrode configuration and simulated structure of liquid crystal material orientation for SDLCR in the wide-angle state in illustrative embodiments, shown in top view. [Figure 2D] This is a schematic graph illustrating the diffraction brightness profile with respect to diffraction order for the embodiment shown in Figure 2C under wide-angle conditions. [Figure 2E] This is a schematic graph illustrating the variation in the diffraction profile due to the driving voltage in the embodiment shown in Figure 2C. [Figure 2F] This is a schematic graph illustrating the variation in total diffraction intensity due to the driving voltage in the embodiment shown in Figure 2E. [Figure 2G] This is a schematic graph illustrating the diffraction brightness profile against diffraction order for the embodiments shown in Figure 2C and Table 2 under wide-angle conditions for different drive voltages. [Figure 3A] This schematic diagram illustrates the structure and operation of a display device equipped with SDVACRA in the wide-angle state, as shown in a top view. [Figure 3B] This schematic diagram illustrates the propagation of the first linearly polarized state through an SDLCR arranged in a wide-angle state, as shown in the top view. [Figure 3C] This schematic diagram illustrates the propagation of the first polarization state through an SDLCR arranged in a wide-angle state, as shown in an oblique front view. [Figure 3D] This schematic diagram illustrates, in a top view, the propagation of a second linearly polarized state orthogonal to a first polarization state through a layer equipped with an SDLCR arranged in a wide-angle state. [Figure 3E] This schematic diagram illustrates, in a perspective front view, the propagation of a second polarization state through a layer equipped with an SDLCR arranged in a wide-angle state. [Figure 3F] This schematic diagram illustrates, in a top view, the propagation of a ray containing orthogonal polarization states at two different positions x0 and x1 across the layer through a layer of SDLCR arranged in a wide-angle state. [Figure 3G] This is a schematic diagram illustrating the configuration of Figure 3F, including an additional polarizer, the input polarizer, in a top view. [Figure 3H] This is a schematic diagram illustrating the configuration of Figure 3F, with the input polarizer (display polarizer) and output polarizer (output polarizer) shown in a top view. [Figure 4A] This schematic diagram illustrates the structure and operation of an optical stack equipped with SDVACRA in a narrow-angle state, shown in a top view. [Figure 4B]This schematic diagram illustrates the electrode arrangement and liquid crystal material orientation structure for SDLCR in a narrow-angle state, using a perspective front view. [Figure 4C] This schematic diagram illustrates the electrode arrangement and liquid crystal material orientation structure for SDLCR in a narrow-angle state, as shown in a top view. [Figure 5A] This schematic diagram illustrates the structure and operation of a display device equipped with SDVACRA in the wide-angle state, as shown in a top view. [Figure 5B] This schematic diagram illustrates, in a top view, the propagation of a first linearly polarized state through a layer equipped with an SDLCR arranged in a narrow-angle state. [Figure 5C] This schematic diagram illustrates, in an oblique front view, the propagation of a first linearly polarized state through a layer equipped with an SDLCR arranged in a narrow-angle state. [Figure 5D] This schematic diagram illustrates, in an oblique side view, the propagation of a first linearly polarized state through a layer comprising liquid crystal molecules tilted for first and second different polarization directions. [Figure 5E] This schematic diagram illustrates, in a top view, the propagation of light rays through a layer of SDLCR arranged in a narrow-angle state along the viewing axis and tilt axis for two different positions x0 and x1 across the region of the liquid crystal material layer. [Figure 5F] This is a schematic diagram illustrating the structure and operation of an optical stack equipped with SDVACRA in a narrow-angle state, using an alternative driver configuration to that illustrated in Figure 4A, as shown in a top view. [Figure 6A] This schematic diagram illustrates the structure and operation of an optical stack equipped with SDVACRA in an intermediate state, as shown in a top view. [Figure 6B] This schematic diagram illustrates the electrode configuration and liquid crystal material orientation structure of SDLCR in an intermediate state, using a perspective front view. [Figure 6C] This schematic diagram illustrates the electrode configuration and liquid crystal material orientation structure for SDLCR in an intermediate state, shown in a top view. [Figure 6D]This schematic diagram illustrates, in a top view, the propagation of light rays along the viewing axis and tilt axis in an intermediate state for light rays at two different positions x0 and x1 across the region of the liquid crystal material layer, through a layer of SDLCR arranged therein. [Figure 6E] This schematic diagram illustrates, in an oblique side view, the propagation of a first linearly polarized state through a layer comprising vertically aligned liquid crystal molecules and a passive compensating retarder. [Figure 6F] This schematic diagram illustrates the structure and operation of an alternative optical stack with SDVACRA in an intermediate state, shown in a top view. [Figure 7A] This is a schematic graph illustrating the SDLCR drive waveform of the optical stack shown in Figure 2A in the wide-angle state. [Figure 7B] This is a schematic graph illustrating an alternative driving waveform for the SDLCR of the optical stack shown in Figure 4A under narrow-angle conditions. [Figure 7C] This is a schematic graph illustrating the SDLCR drive waveform of the optical stack shown in Figure 6A in an intermediate state. [Figure 8A] Figure 1A is a schematic graph illustrating the extreme fluctuations in luminance output for an example backlight. [Figure 8B] These are schematic graphs illustrating the polar variations in transmittance for an example SDVACRA operating in a narrow-angle state, as shown in Figure 1A and Table 2. [Figure 8C] Figure 8A shows the polar variation of luminance output for the display in Figure 1A equipped with an illustrative backlight, and Figure 8B is a schematic graph illustrating the SDVACRA polar variation in the narrow-angle state. [Figure 8D] These are schematic graphs illustrating the polar variation in reflectance for an example SDVACRA operating in a narrow-angle state, as shown in Figure 1A and Table 2. [Figure 8E] Figure 8A is an illustrative example of a backlight, operating in a narrow-angle state, and this schematic graph illustrates the extreme variation of the security coefficient S for SDVACRA shown in Table 2, Figures 8B and 8D. [Figure 8F]This is a schematic graph illustrating the polar variation in transmittance for an example SDVACRA operating in the wide-angle state, as shown in Figure 1A and Table 2. [Figure 8G] This is a schematic graph illustrating the extreme variation in brightness output for the display device shown in Figure 1A, which includes the example backlight in Figure 8A and the SDVACRA in the wide-angle state shown in Figure 8F. [Figure 9A] This schematic diagram illustrates the electrode and liquid crystal material structure of an SDLCR (Single-Layer Depositionable Crystal) with two parallel homogeneous surface alignment layers in non-driving mode, as shown in a perspective front view. [Figure 9B] This is a schematic diagram illustrating an alternative homogeneous liquid crystal alignment for SDLCR in the wide-angle state, as shown in the top view of Figure 9F. [Figure 9C] This is a schematic graph illustrating the diffraction brightness profile with respect to diffraction order for the embodiment shown in Figure 9B. [Figure 9D] This is a schematic graph illustrating the normalized intensity variation with respect to angle for each of the seven different drive voltages in the configuration shown in Figure 9B. [Figure 9E] This is a schematic graph illustrating the variation in total transmission intensity for each of the seven different drive voltages in the configuration shown in Figure 9B. [Figure 9F] This schematic diagram illustrates, in a top view, an alternative homogeneous liquid crystal alignment for use in the embodiment of Figure 1A, having the electrode configuration of Figure 1E and arranged in a narrow-angle state. [Figure 9G] Figure 9A and Tables 5-6 are schematic graphs illustrating the polar variation in transmittance for example SDLCR under narrow-angle conditions. [Figure 9H] This is a schematic diagram illustrating an alternative homogeneous liquid crystal alignment for the SDLCR shown in Figure 9F, installed in an intermediate state, as shown in a top view. [Figure 10A] This schematic diagram illustrates an SDLCR in a perspective front view, comprising an electrode configuration, a pair of orthogonally aligned homogeneous surface alignment layers, and a liquid crystal material alignment structure for the SDLCR in non-driving mode. [Figure 10B] This is a schematic graph illustrating the polar variation in transmittance for an example SDVACRA operating in a narrow-angle state, as shown in Figure 10A and Table 8. [Figure 10C] This schematic diagram illustrates, in a top view, an alternative homogeneous liquid crystal alignment structure to SDLCR, having the configuration shown in Figure 10A and arranged in a narrow-angle state. [Figure 10D] This schematic diagram illustrates, in a top view, an alternative homogeneous liquid crystal alignment structure for SDLCR, having the configuration shown in Figure 10A in the wide-angle state. [Figure 10E] This is a schematic graph illustrating the normalized intensity variation with respect to angle for each of the seven different drive voltages in the configuration shown in Figure 10D. [Figure 10F] This is a schematic graph illustrating the variation in total transmission intensity for each of the seven different drive voltages in the configuration shown in Figure 10D. [Figure 11A] This schematic diagram illustrates an alternative permeable electrode configuration for the SDLCR shown in Figure 1A, where the control electrode is omitted, in a perspective side view. [Figure 11B] Figure 11A is a schematic diagram illustrating, in a perspective front view, the electrode configuration and the liquid crystal material alignment structure for an SDLCR that includes a surface alignment layer providing homogeneous alignment of the liquid crystal material and a surface alignment layer providing homeotropic alignment of the liquid crystal material when driven in a narrow-angle state. [Figure 11C] Figure 11A is a schematic diagram illustrating, in a perspective front view, the electrode configuration and the liquid crystal material alignment structure for an SDLCR that includes a surface alignment layer providing homogeneous alignment of the liquid crystal material and a surface alignment layer providing homeotropic alignment of the liquid crystal material when driven in a wide-angle state. [Figure 11D] This is a schematic diagram illustrating the structure of the SDLCR shown in Figures 11A-C, which operates in a wide-angle state, as shown in a top view. [Figure 11E]Figure 11A is a schematic diagram illustrating, in a perspective front view, the electrode configuration and the liquid crystal material alignment structure of SDLCR, which provides homogeneous alignment of the liquid crystal material and is driven in a wide-angle state, comprising two surface alignment layers. [Figure 11F] This schematic diagram illustrates an alternative liquid crystal alignment structure for SDLCR, having the configuration shown in Figure 11B, in a narrow-angle state, as shown in a top view. [Figure 11G] This schematic diagram illustrates, in a top view, an alternative homogeneous liquid crystal alignment structure to SDLCR, having the configuration shown in Figures 11B-C and arranged in a wide-angle state. [Figure 11H] This is a schematic graph illustrating the normalized intensity variation with respect to angle for each of the seven different drive voltages in the configuration of Figure 11G. [Figure 11I] This is a schematic graph illustrating the variation in total transmission intensity for each of the seven different drive voltages in the configuration shown in Figure 11G. [Figure 11J] This schematic diagram illustrates, in a top view, an alternative homogeneous liquid crystal alignment structure to SDLCR, having the configuration shown in Figure 11E and arranged in a narrow-angle state. [Figure 11K] This schematic diagram illustrates, in a top view, an alternative homogeneous liquid crystal alignment structure for SDLCR having the configuration shown in Figure 11E in the wide-angle state. [Figure 11L] Figure 11 is a schematic graph illustrating the normalized intensity variation with respect to angle for each of the seven different drive voltages in the K configuration. [Figure 11M] Figure 11 is a schematic graph illustrating the variation in total transmission intensity for each of the seven different drive voltages for the K configuration. [Figure 12] This schematic diagram illustrates an alternative permeable electrode configuration with mutually mated electrodes in a perspective side view. [Figure 13] This schematic diagram illustrates an alternative electrode configuration, illustrated in a perspective side view, which includes spaced-out transparent electrodes positioned on both sides of a liquid crystal material layer. [Figure 14A]This schematic diagram illustrates an alternative electrode configuration in a perspective side view, comprising spaced-apart, mutually mated transparent electrodes arranged on both sides of a liquid crystal material layer, and further mutually mated transparent electrodes. [Figure 14B] Figure 14A is a schematic diagram illustrating the drive configuration of an SDLCR with the electrode configuration shown in Figure 14A, as shown in a top view. [Figure 15A] Figure 14A is a schematic diagram illustrating the structure and operation of an SDLCR with an alternative electrode configuration, shown in a top view. The isolation electrodes on both sides of the liquid crystal material layer are offset by a distance δ in the lateral direction. [Figure 15B] This is a schematic diagram illustrating the liquid crystal alignment of an SDLCR with the electrode configuration shown in Figure 15A under narrow-angle conditions, shown in a top view. [Figure 15C] This schematic diagram illustrates the liquid crystal alignment of an SDLCR with the electrode configurations shown in Figure 15A and Tables 9-10 in the wide-angle state, as shown in a top view. [Figure 15D] This is a schematic graph illustrating the diffraction brightness profile with respect to diffraction order in the embodiment shown in Figure 15C. [Figure 16A] This schematic diagram illustrates a switchable display device, illustrated in an oblique side view, comprising a collimated backlight, an SLM, a reflective polarizer, an SDVACRA, and an additional polarizer. [Figure 16B] This schematic diagram illustrates a switchable display device comprising an emissive SLM, an aperture array, a display polarizer, a reflective polarizer, an SDVACRA, and an additional polarizer, in an oblique side view. [Figure 16C] This is a schematic graph illustrating the polar variation of reflectance for an example SDVACRA operating in a narrow-angle state, as shown in Figure 16A and Table 2. [Figure 16D] Figure 8A is an illustrative backlight profile for the SDVACRA shown in Table 2, illustrating the security coefficient S profile, as well as schematic graphs illustrating the profiles in Figures 8B and 16C, which operate in a narrow-angle state. [Figure 17A]This schematic diagram illustrates a side view of an alternative optical stack configuration for a switchable display device equipped with SDVACRA as shown in Figure 1A. [Figure 17B] This schematic diagram illustrates a side view of an alternative optical stack configuration for a switchable display device equipped with SDVACRA as shown in Figure 1A. [Figure 17C] This schematic diagram illustrates a side view of an alternative optical stack configuration for a switchable display device equipped with SDVACRA as shown in Figure 1A. [Figure 17D] This schematic diagram illustrates a side view of an alternative optical stack configuration for a switchable display device equipped with SDVACRA as shown in Figure 1A. [Figure 17E] This schematic diagram illustrates a side view of an alternative optical stack configuration for a switchable display device equipped with SDVACRA as shown in Figure 1A. [Figure 18A] This schematic diagram illustrates a switchable display device, illustrated in an oblique side view, that includes an SDVACRA with an SDLCR and a further retarder with an additional SDLCR. [Figure 18B] This schematic diagram illustrates a switchable display device in an oblique side view, comprising an SDVACRA with an SDLCR and a further retarder with a switchable non-diffraction liquid crystal retarder (SNDLCR). [Figure 18C] This schematic diagram illustrates a switchable display device in an oblique side view, comprising a backlight, an additional polarizer, and a switchable diffractive field of view control configuration (SDVACA) disposed between the additional polarizer and the display polarizer, wherein the SDVACA comprises switchable diffractive liquid crystal elements (SDLCE) and SDLCR. [Figure 18D] This schematic diagram illustrates a switchable display device, comprising a display polarizer, an SDVACRA, an additional polarizer, another SDVACRA, and yet another additional polarizer, in an oblique side view. [Figure 18E]This schematic diagram illustrates a switchable display device in an oblique side view, comprising a display polarizer, an SNDLCRA, additional polarizers, an SDVACRA with an SDLCR, and additional polarizers. [Figure 18F] This schematic diagram illustrates a switchable display device in an oblique side view, comprising a backlight, an additional polarizer, an SDVACRA, a transmissive SLM, a reflective polarizer, an SNDLCRA, and further additional polarizers. [Figure 18G] This schematic diagram illustrates a switchable display device in an oblique side view, comprising a backlight, an SDLCE, an additional polarizer, and an SDVACA disposed between the additional polarizer and the display polarizer, wherein the SDVACA comprises an SDLCR and a passive compensation retarder. [Figure 19A] This schematic diagram illustrates a side view of an alternative stacking configuration for a switchable display device having at least one SDVACRA and further switchable viewing angle control configurations, as well as a transmissive SLM and backlight. [Figure 19B] This schematic diagram illustrates a side view of an alternative stacking configuration for a switchable display device having at least one SDVACRA and further switchable viewing angle control configurations, as well as a transmissive SLM and backlight. [Figure 19C] This schematic diagram illustrates a side view of an alternative stacking configuration for a switchable display device having at least one SDVACRA and further switchable viewing angle control configurations, as well as a transmissive SLM and backlight. [Figure 19D] This schematic diagram illustrates a side view of an alternative stacking configuration for a switchable display device having at least one SDVACRA and further switchable viewing angle control configurations, as well as a transmissive SLM and backlight. [Figure 19E]This schematic diagram illustrates a side view of an alternative stacking configuration for a switchable display device having at least one SDVACRA and further switchable viewing angle control configurations, as well as a transmissive SLM and backlight. [Figure 20A] This schematic diagram illustrates a switchable display device comprising a backlight, an additional polarizer, an SDVACA, and an SLM, in an oblique side view, wherein the SDVACA is positioned between the additional polarizer and the display polarizer, which is the input polarizer for the SLM. [Figure 20B] This is a schematic diagram illustrating the alignment orientation of an optical stack for use in the embodiment shown in Figure 20A, in a perspective front view. [Figure 20C] Figures 20A and 20B are schematic diagrams illustrating the electrode configurations of SNDLCR and SDLCE in perspective side views. [Figure 20D] This is a schematic diagram illustrating an SDVACA with SDLCE and a switchable non-diffraction field of view control configuration, shown in an oblique side view. [Figure 21A] This schematic diagram illustrates, in a top view, the structure and operation of an alternative optical stack driven in the wide-angle state, for use in the configurations shown in Figures 20A-B and the illustrative embodiments in Tables 11-12. [Figure 21B] This schematic diagram illustrates the structure and operation of the optical stack shown in Figures 21A and 21B, which is driven in the narrow-angle condition, from a top view. [Figure 21C] This is a schematic diagram illustrating the optical stack shown in Figures 21A and 21B, which is driven in an intermediate state, from a top view. [Figure 22A] This is a schematic graph illustrating the SDVACA drive waveform of the optical stack shown in Figures 20A and 20B in the wide-angle state. [Figure 22B] These are schematic graphs illustrating alternative drive waveforms for SDVACA in the narrow-angle condition shown in Figures 20A and 20B. [Figure 22C] These are schematic graphs illustrating the drive waveforms of SDVACA in the intermediate state shown in Figures 20A and 20B. [Figure 23A]This schematic diagram illustrates, in a perspective front view, the transparent electrode configuration of Figure 21A, the liquid crystal material orientation structure of SDLCE, and the liquid crystal material orientation structure of SNDLCR in Figure 21A, under wide-angle conditions. [Figure 23B] Figure 21A and Tables 11-12 illustrate the liquid crystal material orientation structure of SDLCE in a schematic diagram showing a top view. [Figure 23C] This is a schematic graph illustrating the diffractive brightness profile with respect to diffraction order for the embodiment shown in Figure 23B. [Figure 23D] This schematic diagram illustrates the liquid crystal material orientation structure of SDLCE and SNDLCR in Figure 21B, operating under narrow-angle conditions, in a perspective front view. [Figure 23E] This schematic diagram illustrates the liquid crystal material orientation structure of SDLCE operating in an intermediate state, and the liquid crystal material orientation structure of SNDLCR in Figure 21C, as illustrated in a perspective front view. [Figure 23F] Figures 21B-C are schematic diagrams illustrating the liquid crystal material orientation structure of SDLCE in a top view. [Figure 23G] This schematic diagram illustrates, in a top view, the liquid crystal material orientation structure of SDLCR equipped with a homogeneous surface alignment layer, where the in-plane alignment direction is parallel and antiparallel to the transverse direction and arranged in a narrow-angle state, according to the embodiments shown in Tables 13-14. [Figure 23H] This is a schematic diagram illustrating the top view of the configuration shown in Figure 23G, which is driven in the wide-angle state. [Figure 23I] Figure 23H and Tables 13-14 show schematic graphs illustrating the diffraction brightness profile against diffraction order for each embodiment. [Figure 23J] This schematic diagram illustrates, in a top view, the liquid crystal material orientation structure of SDLCE equipped with a homogeneous surface alignment layer, where the in-plane alignment direction is perpendicular to the transverse direction and arranged in a narrow-angle state, according to the embodiments shown in Tables 15-16. [Figure 23K] This is a schematic diagram illustrating the top view of the configuration shown in Figure 23J, which is driven in the wide-angle state. [Figure 23L]Figure 23K and Tables 15-16 show schematic graphs illustrating the diffraction brightness profile with respect to diffraction order for each embodiment. [Figure 24] This schematic diagram illustrates an alternative electrode configuration, comprising mutually mated electrodes arranged on a single substrate, as well as additional control and reference electrodes, in a perspective side view. [Figure 25A] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25B] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25C] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25D] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25E] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25F]This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25G] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25H] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25I] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25J] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25K] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25L] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25M] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 25N] This schematic diagram illustrates a non-exclusive side view of an alternative optical stack for a switchable display device, in which a switchable non-diffraction viewing angle control configuration of an SDLCE and a switchable luminance liquid crystal is arranged between the display polarizer and an additional polarizer. [Figure 26A] This schematic diagram illustrates a switchable display device 120 in an oblique side view, comprising a backlight, a switchable light dispersion configuration with SDLCE, a transmissive SLM having an input display polarizer and an output display polarizer, a reflective polarizer, a switchable non-diffraction field of view angle control configuration, and an additional polarizer. [Figure 26B] This is a schematic diagram illustrating the alignment orientation of an optical stack for use in the embodiment shown in Figure 26A, in a perspective front view. [Figure 27A] This schematic diagram illustrates the structure and operation of the optical stack shown in Figures 26A-B and the electrode configuration shown in Figure 21C in the wide-angle state, with a top view (however, the electrode configuration is omitted). [Figure 27B] This is a schematic diagram illustrating the structure and operation of the optical stack shown in Figures 26A and 26B in the narrow-angle condition, illustrated from a top view. [Figure 27C] This is a schematic diagram illustrating the structure and operation of the optical stack shown in Figures 26A and 26B in an intermediate state, presented as a top view. [Figure 28A] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28B] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28C] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28D]This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28E] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28F] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28G] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 28H] This is a schematic diagram illustrating a non-exclusive side view of alternative, switchable display devices. [Figure 29A] This schematic diagram illustrates a switchable display device in an oblique side view, comprising a backlight, a switchable optical dispersion configuration with a switchable surface relief birefringent configuration having a surface relief birefringent optical dispersion element and a polarization control element, a transmissive SLM with an input polarizer and an output polarizer, a reflective polarizer, an SNDLCRA, and an additional polarizer. [Figure 29B] This is a schematic diagram illustrating the alignment orientation of the optical stack used in the embodiment shown in Figure 29A, in a perspective front view. [Figure 29C] This is a schematic diagram illustrating the operation of the switchable surface relief birefringence configuration shown in Figures 29A and 29B in the wide-angle state, illustrated in a top view. [Figure 29D] This is a schematic diagram illustrating the operation of the switchable surface relief birefringence configuration shown in Figures 29A and 29B in a narrow-angle state, illustrated in a top view. [Figure 29E] This is a schematic diagram illustrating a surface relief birefringent optical dispersion element in an oblique front view. [Figure 30A] This is a schematic diagram illustrating a diffraction profile surface relief birefringent optical dispersion element in a perspective front view. [Figure 30B] This is a schematic graph illustrating the diffraction brightness profile with respect to diffraction order for the embodiment shown in Figure 30A under wide-angle conditions. [Figure 31A]This is a schematic diagram illustrating a passenger infotainment display device for use in a vehicle, shown in a top view. [Figure 31B] Figure 31A is a schematic diagram illustrating the operation of the passenger infotainment display device in a top view. [Figure 32A] This schematic diagram illustrates an alternative transparent electrode configuration in a top view, where the electrode pitch p varies across the display device. [Figure 32B] This is a schematic diagram illustrating the operation of a display device with the alternative transparent electrode configuration shown in Figure 32A, from a top view. [Figure 32C] This schematic diagram illustrates the operation of a display device in a top view, further comprising the alternative transmissive electrode configuration shown in Figure 32A, and a pupillated backlight and / or a pupillated switchable luminance liquid crystal switchable non-diffraction viewing angle control configuration. [Figure 32D] This is a schematic diagram illustrating the operation of a curved, switchable display device from a top view. [Figure 32E] This schematic diagram illustrates the electrode configuration for a segmented, switchable display device in a perspective front view. [Figure 32F] This is a schematic diagram illustrating a segmented, switchable display device in a front view. [Figure 32G] This schematic diagram illustrates the view to an observer along the tilt axis of a segmented, switchable display arranged to provide a uniform wide-angle view. [Figure 32H] This schematic diagram illustrates, in an oblique front view, the view to the observer along the tilt axis of a segmented, switchable display arranged to provide areas in both narrow-angle and wide-angle states. [Figure 32I] This schematic diagram illustrates, in an oblique front view, the view to an observer along the tilt axis of a segmented switchable display device, arranged to provide visibility of a mark provided on at least one of the electrodes of the switchable display device. [Figure 33A] This schematic diagram illustrates an alternative backlight with addressable first and second light source arrays in an oblique side view and an oblique front view. [Figure 33B] This schematic diagram illustrates an alternative backlight, illustrated in a perspective side view, comprising first and second waveguides and first and second light source arrays aligned accordingly. [Figure 33C] Figure 33B is a schematic diagram illustrating the operation of the backlight in a top view. [Figure 33D] This is a schematic diagram illustrating the light redirection components in an oblique rear view. [Figure 33E] This is a schematic diagram illustrating the light conversion components in a top view. [Figure 34A] This schematic diagram illustrates an alternative backlight, possibly a mini-LED, with a light source array and a light deflection well array, in an oblique side view. [Figure 34B] This schematic diagram illustrates an alternative backlight in a perspective side view, comprising a light source array provided at the edge of a waveguide, intersecting brightness-enhancing films, a light control component, and an out-of-plane polarizer arranged to output light to an additional polarizer. [Figure 35A] This schematic diagram illustrates a switchable display device in an oblique side view, comprising a backlight, an optical control element with additional polarizers (out-of-plane and in-plane polarizers), an SDVACRA, and a transmissive SLM. [Figure 35B] This is a schematic diagram illustrating the alignment orientation of the optical stack used in the embodiment shown in Figure 35A, in a perspective front view. [Figure 35C] This schematic diagram illustrates the operation of an out-of-plane polarizer and additional polarizers for light from a backlight, in an oblique side view. [Figure 36A] This is a schematic graph illustrating the pole variation for transmission of example out-of-plane and in-plane polarizers. [Figure 36B] Figure 8A is an illustrative schematic graph illustrating the polar variation in luminance for an example configuration backlight profile and Figure 36A is an out-of-plane polarizer transmission profile. [Figure 36C] Table 19 is a schematic graph illustrating the extreme variation in transmittance for an example of SDVACRA. [Figure 36D] This is a schematic graph illustrating the extreme variation of the security coefficient for an exemplary switchable display device shown in Figure 35A, which includes the backlight profile in Figure 8A, the out-of-plane polarizer profile in Figure 36A, and the SDVACRA profile in Figure 36C. [Figure 37A] This schematic diagram illustrates the operation of a backlight equipped with light redirection components and microlouver components in an oblique side view. [Figure 37B] This schematic diagram illustrates the operation of a backlight comprising a light redirection component, a light control component, an out-of-plane polarizer, and an in-plane polarizer, using an oblique side view. [Figure 38A] This schematic diagram illustrates an alternative backlight in a perspective side view, comprising a light scattering waveguide, a back reflector, intersecting prism films, and an optical control element disposed between light-transmitting regions of width sl and mounted on a substrate, the element having louvers of thickness tl with pitch pl and louver width al. [Figure 38B] Figure 38A is a schematic diagram illustrating the operation of the backlight in a top view. [Figure 39A] This schematic diagram illustrates, in a top view, the propagation of output light along the axis from an SLM through a switchable non-diffraction field of view control configuration in a narrow-angle state. [Figure 39B] This schematic diagram illustrates the propagation of ambient illumination light through a switchable non-diffraction field of view control configuration in a narrow-angle state, as shown in a top view. [Figure 40A] This schematic diagram illustrates the propagation of output light from an SLM through a switchable non-diffraction field of view control configuration in a wide-angle state, as shown in a top view. [Figure 40B] This schematic diagram illustrates the propagation of ambient illumination light through a switchable non-diffraction field of view control configuration in a wide-angle state, as shown in a top view. [Modes for carrying out the invention]

[0058] Herein, we will explain the terminology related to optical retarders for the purposes of this disclosure.

[0059] A layer containing a uniaxial birefringent material has a direction that governs optical anisotropy, but all directions perpendicular to it (or at a given angle thereto) exhibit equivalent birefringence.

[0060] The optical axis of an optical retarder refers to the direction of light ray propagation within a uniaxial birefringent material where birefringence does not occur. This is different from the optical axis of an optical system, which may be, for example, parallel to the line of symmetry or perpendicular to the display surface on which the principal ray propagates.

[0061] For light propagating perpendicular to the optical axis, the optical axis becomes the lagging axis when linearly polarized light traveling in the direction of the electric vector parallel to the lagging axis travels at the slowest speed. The lagging axis direction is the direction in which the refractive index is highest at the design wavelength. Similarly, the fast axis direction is the direction in which the refractive index is lowest at the design wavelength.

[0062] In the case of a uniaxial birefringent material with positive dielectric anisotropy, the retard axis is the anomalous axis of the birefringent material. In the case of a uniaxial birefringent material with negative dielectric anisotropy, the fast axis is the anomalous axis of the birefringent material.

[0063] The terms half-wavelength and quarter-wavelength refer to the retarder's behavior for a design wavelength λ0, which is typically between 500 nm and 570 nm. In this embodiment, unless otherwise specified, exemplary retardation values ​​are provided for a wavelength of 550 nm.

[0064] A retarder provides a phase shift between the two perpendicular polarization components of a light wave incident upon it, and is characterized by the amount of net relative phase η it imparts to the two polarization components, which is related to the birefringence Δn and the thickness d of the retarder as follows: η = 2.π.Δn.d / λ0 Equation 1

[0065] In Equation 1, Δn is defined as the difference between the abnormal refractive index and the normal refractive index. Δn = n e -n o formula 2

[0066] For a half-wavelength retarder, the relationship between d, Δn, and λ0 is chosen such that the phase shift between the polarization components is η = π. For a quarter-wavelength retarder, the relationship between d, Δn, and λ0 is chosen such that the phase shift between the polarization components is η = π / 2. The term half-wavelength retarder as used herein typically refers to light propagating perpendicular to the retarder and perpendicular to the spatial light modulator (SLM).

[0067] An absorbing polarizer transmits light waves in a specific polarization state and absorbs light in different polarization states (within the spectral waveband) that may be in polarization states orthogonal to that specific polarization state. For a given wavefront, an absorbing linear polarizer absorbs light waves in a specific linear polarization state and transmits light waves in polarization states orthogonal to the wavefront. An absorbing linear polarizer has a unit vector direction k which can be alternatively referred to as the optical axis or the director of the absorbing material. e It has an absorption axis having a direction k perpendicular to the absorption axis direction. o This can be called the transmission axis.

[0068] Dichroic materials have different absorption coefficients α for light polarized in different directions. e , α ο It has the following properties, and its complex anomalous refractive index is as follows:

number

number

[0069] Absorptive linear polarizers can comprise a dichroic material such as a dye or iodine. During manufacture, a polyvinyl alcohol (PVA) layer is stretched so that the PVA chains are aligned in one particular direction. The PVA layer is doped with iodine molecules, from which valence electrons can move linearly along the polymer chains but not laterally. An incident polarization state parallel to the chains is at least partially absorbed, and a perpendicular polarization state is substantially transmitted. Such a polarizer can conveniently provide an in-plane polarizer.

[0070] Another type of absorptive linear polarizer is the liquid crystal dye type of dichroic linear polarizer. A thermotropic liquid crystal material is doped with a dye, and the liquid crystal material is aligned during manufacture or by an electric field. The liquid crystal layer may not be twisted or may incorporate a twist from one side of the device to the other. Alternatively, provision of an amphiphilic compound (having a hydrophilic molecular group and a hydrophobic molecular group) during manufacture can provide alignment by lyotropic liquid crystal molecules that self-align on the surface. Such alignment can be assisted, for example, by the mechanical movement of a liquid by a Meyer rod in a coating machine. The liquid crystal material can be a curable liquid crystal material. The dye can comprise an organic material aligned by the liquid crystal material, or can be provided within the liquid crystal molecules, or can comprise silver nanoparticles. Such a polarizer can provide an in-plane polarizer or an out-of-plane polarizer, with the optical axis direction k e or the absorption axis being out of the plane of the polarizer. The direction k of the transmission axis o can be in the plane of the out-of-plane polarizer. Alternatively, the direction k e can be referred to as the extraordinary axis direction, and the direction k o can be referred to as the ordinary axis direction of the dichroic molecules.

[0071] When the absorbing dye molecules are rod-shaped, the polarizer absorbs along one axis and transmits on the orthogonal axis. When the absorbing dye molecules are not rod-shaped but disk-shaped, the polarizer can absorb two orthogonal axes and transmit on the third orthogonal axis.

[0072] Here, we describe several modes of light ray propagation through a transparent retarder between polarizer pairs.

[0073] The polarization state (SOP) of a ray is represented by the relative amplitude and phase shift between any two orthogonal polarization components. A transparent retarder does not change the relative amplitude of these orthogonal polarization components, but acts only on their net relative phase. Providing a net phase shift between the orthogonal polarization components changes the SOP, while maintaining the net relative phase preserves the SOP. In this disclosure, the SOP may be referred to as the polarization state.

[0074] A linear SOP has a polarization component with non-zero amplitude and an orthogonal polarization component with zero amplitude.

[0075] A linear polarizer has a linear polarization component parallel to the electrical vector transmission direction of the linear polarizer and transmits its own linear SOP, which attenuates light at different SOPs. The term "electrical vector transmission direction" refers to the non-directional axis of the polarizer through which the electrical vector of incident light is transmitted, even though the transmitted "electrical vector" always has an instantaneous direction. The term "direction" is commonly used to describe this axis.

[0076] An absorbing polarizer is a polarizer that absorbs one polarization component of incident light and transmits a second orthogonal polarization component. An example of an absorbing linear polarizer is a dichroic polarizer.

[0077] A reflective polarizer is a polarizer that reflects one polarization component of incident light and transmits a second orthogonal polarization component. Examples of linear reflective polarizers include multilayer polymer film stacks such as 3M's DBEF® or APF®, or wire grid polarizers such as Moxtek's ProFlux®. A reflective linear polarizer may further comprise a cholesteric reflective material and quarter-wave plates arranged in series.

[0078] A retarder positioned between a linear polarizer and a parallel-linear analysis polarizer, which does not introduce a relative net phase shift, provides complete transmission of light other than residual absorption within the linear polarizer.

[0079] A retarder that provides a relative net phase shift between orthogonal polarization components alters the SOP and provides attenuation in the analytical polarizer.

[0080] In this disclosure, "A plate" refers to an optical retarder that utilizes a birefringent material layer whose optical axis is parallel to the plane of the layer.

[0081] A "positive A plate" refers to a positively birefringent A plate, that is, an A plate with a positive Δn.

[0082] In this disclosure, "C-plate" refers to an optical retarder that utilizes a birefringent material layer whose optical axis is perpendicular to the plane of the layer. "Positive C-plate" refers to a positive birefringent C-plate, i.e., a C-plate with a positive Δn. "Negative C-plate" refers to a negative birefringent C-plate, i.e., a C-plate with a negative Δn.

[0083] An "O-plate" refers to an optical retarder that utilizes a birefringent material layer whose optical axis has components parallel to the plane of the layer and components perpendicular to the plane of the layer. A "positive O-plate" refers to a positive birefringent O-plate, that is, an O-plate with a positive Δn.

[0084] An achromatic retarder may be provided in which the retardance Δn.d of the retarder material changes with wavelength λ as follows. Δn.d / λ=σ Equation 5

[0085] In the equation, σ is essentially a constant.

[0086] Examples of suitable materials include modified polycarbonate manufactured by Teijin Films. In this embodiment, an achromatic retarder may be provided to advantageously minimize the color change between polar angle viewing directions with little luminance reduction and polar angle viewing directions with increased luminance reduction, as described below.

[0087] Herein, we will explain various other terms used in this disclosure in relation to retarders and liquid crystals.

[0088] The liquid crystal cell has a retardation given by Δn.d, where Δn is the birefringence of the liquid crystal material within the liquid crystal cell, and d is the thickness of the liquid crystal cell, independent of the alignment of the liquid crystal material within the liquid crystal cell.

[0089] Homogeneous alignment refers to the alignment of liquid crystals in a liquid crystal display, where the molecules are aligned substantially parallel to the substrate. Homogeneous alignment is sometimes also called planar alignment. Homogeneous alignment can typically be provided with a small pre-tilt, such as 2 degrees, resulting in a slight tilt of the molecules on the surface of the liquid crystal cell's surface alignment layer, as described below. The pre-tilt is configured to minimize degeneracy in cell switching or in the alignment of the curable liquid crystal layer before the curing step.

[0090] In this disclosure, homeotropic alignment is a state in which rod-shaped liquid crystal molecules are aligned substantially perpendicular to the substrate. In discotic liquid crystals, homeotropic alignment is defined as a state in which the axes of the columnar structure formed by disk-shaped liquid crystal molecules are aligned perpendicular to the surface. In homeotropic alignment, pretilt is the tilt angle of the molecules near the surface alignment layer, which is typically close to 90 degrees and can be, for example, 88 degrees.

[0091] In the twisted liquid crystal layer, a twisted configuration of nematic liquid crystal molecules (also known as a helical structure or helix) is provided. The twist can be achieved by the non-parallel alignment of the surface alignment layer. Further, a cholesteric dopant can be added to the liquid crystal material to eliminate the degeneracy of the twist direction (clockwise or counterclockwise) and further control the pitch of the twist in the relaxed (usually non-driven) state. The super twisted liquid crystal layer has a twist exceeding 180 degrees. The twisted nematic layer used in the SLM typically has a 90-degree twist.

[0092] Liquid crystal molecules with positive dielectric anisotropy can be switched from a homogeneous alignment (such as A-plate retarder alignment) to a homeotropic alignment (such as C-plate or O-plate retarder alignment) by the applied electric field.

[0093] Liquid crystal molecules with negative dielectric anisotropy can be switched from a homeotropic alignment (such as C-plate or O-plate retarder alignment) to a homogeneous alignment (such as A-plate retarder alignment) by the applied electric field.

[0094] Since rod-shaped molecules have positive birefringence, as described in Equation 2, n e >n o For discotic molecules having negative birefringence, n e <n o is true.

[0095] Positive retarders such as A-plates, positive O-plates, and positive C-plates can typically be provided by stretched films or rod-shaped liquid crystal molecules. Negative retarders such as negative C-plates can be provided by stretched films or discotic-like liquid crystal molecules.

[0096] Parallel liquid crystal cell alignment refers to the alignment direction of homogeneous surface alignment layers that are parallel or, more typically, antiparallel. In the case of a pre-tilted homeotropic alignment, the surface alignment layer may have components that are substantially parallel or antiparallel. A hybrid-aligned liquid crystal cell may have one homogeneous surface alignment layer and one homeotropic surface alignment layer. A twisted liquid crystal cell may be provided by, for example, surface alignment layers that are not parallel and are oriented 90 degrees to each other.

[0097] The transmissive SLM may further include a retarder between the input display polarizer and the output display polarizer, as disclosed, for example, in U.S. Patent No. 8,237,876, which is incorporated herein by reference in its entirety. Such a retarder (not shown) is in a different location than the passive retarder of the present embodiment. Such a retarder compensates for a contrast reduction for off-axis viewing locations, which is a different effect than the luminance reduction for off-axis viewing locations of the present embodiment.

[0098] The private operation mode of the display is an operation mode in which the viewer experiences a low contrast sensitivity so that the image cannot be clearly viewed. Contrast sensitivity is a measure of the ability to distinguish various levels of luminance in a still image. Inverse contrast sensitivity can be used as a measure of visual security in that a high visual security level (VSL) corresponds to low image visibility.

[0099] In the case of a privacy display that provides an image to a viewer, visual security is obtained as follows. V = (Y + R) / (Y - K) Equation 6

[0100] Where V is the visual security level (VSL), Y is the luminance of the white state of the display at the viewing angle of the eavesdropper (which may be referred to as the non-viewing direction), K is the luminance of the black state of the display at the viewing angle of the eavesdropper, and R is the luminance of the reflected light from the display.

[0101] The panel's contrast ratio is obtained as follows: C=Y / K Equation 7 Therefore, the visual security level can be further defined as follows: V=(PY max +I.ρ / π) / (P.(Y max -Y max / C)) Equation 8 In the formula, Y max Y is the maximum brightness of the display, P is the off-axis relative brightness, and is typically the maximum brightness. max Y is defined as the ratio of luminance at the voyeur's angle to , where C is the contrast ratio of the image, ρ is the surface reflectance, π is the solid angle factor (in steradians), and I is the illuminance. max The unit is obtained by dividing the unit of I by the solid angle in units of steradians.

[0102] Display brightness varies depending on the viewing angle, therefore, the maximum brightness of the display Y max This occurs at specific angles depending on the display configuration.

[0103] In many displays, the maximum brightness Y max This occurs in the front, i.e., in the direction normal to the display. Any display device disclosed herein has a maximum brightness Y that occurs in the front. max It may be configured to have the maximum brightness Y of the display device. max The reference to can be replaced by a reference to brightness perpendicular to the display device.

[0104] Alternatively, any display described herein has a maximum brightness Y that occurs at an extreme angle with respect to the normal of the display device greater than 0 degrees. max It can be configured to have the following: For example, the maximum brightness Y maxThis can occur at non-zero polar angles and azimuth angles with, for example, zero lateral angles, and as a result, maximum brightness is for users on the axis looking down at the display device. The polar angle could be, for example, 10 degrees, and the azimuth angle could be north (90 degrees counterclockwise from east). Therefore, desirablely, viewers can see high brightness at typical non-vertical viewing angles.

[0105] The off-axis relative brightness P is sometimes referred to as the privacy level. However, such a privacy level P describes the relative brightness of the display at a given extreme angle compared to the brightness in front, and is not a measure of the perceived privacy.

[0106] Illuminance I is the luminous flux per unit area that enters the display and is reflected from the display toward the viewer's location. For Lambertian illuminance and displays with Lambertian front diffusers, illuminance I is constant with respect to polar and azimuth angles. In configurations with displays with non-Lambertian front diffusers placed in environments with directional (non-Lambertian) ambient light, illuminance I varies with the polar and azimuth angles of observation.

[0107] Therefore, in a completely dark environment, a high-contrast display has a VSL of approximately 1.0. As ambient light increases, the contrast of the perceived image deteriorates, the VSL increases, and the private image becomes more apparent.

[0108] In the case of a typical LCD display, the panel's contrast ratio C exceeds 100:1 at almost all viewing angles, so the visual security level can be roughly estimated as follows: V=1+I.ρ / (π.PY max ) Equation 9

[0109] In this embodiment, in addition to the exemplary definition of Equation 6, other measures of the visual security level V may be provided, such as the influence of the eavesdropper's location, image contrast, image color and white point, and the size of image features corresponding to the viewing angle on the image visibility to the eavesdropper. Thus, the visual security level may be, but is not limited to, the parameter V, a measure of the degree of privacy of the display.

[0110] The security of a perceptual image can be determined from the logarithmic response of the eye, and as a result, the security coefficient S is obtained by the following formula. S=overlap 10 (V) Equation 10 S=overlap 10 (1+α.ρ / (π.P)) Equation 11 In the formula, α is the maximum brightness Y max This is the ratio of illuminance I to .

[0111] The desired limit of S was determined as follows. In the first step, a privacy display device was provided. Measurements of variations in privacy level, P(θ) of the display device with extreme viewing angles, and variations in reflectance ρ(θ) of the display device with extreme viewing angles were performed using photopic spectroscopy equipment. A light source, such as a lightbox with substantially uniform luminance, was positioned to provide illumination to the viewer position at extreme angles greater than 0° with respect to the normal of the display device, from an illumination area positioned to illuminate the privacy display device along the incident direction for reflection. Variations in illuminance I(θ) of a substantially Lambertian lightbox with extreme viewing angles were determined by measuring the variations in recorded reflected luminance with extreme viewing angles, taking into account variations in reflectance ρ(θ). Using the measured values ​​of P(θ), ρ(θ), and I(θ), the variation in the security coefficient S(θ) with respect to extreme viewing angles along the zero elevation axis was determined.

[0112] In the second step, a series of high-contrast images including (i) a small text image with a maximum font height of 3 mm, (ii) a large text image with a maximum font height of 30 mm, and (iii) a video were provided to the privacy display.

[0113] In the third step, each viewer (using vision correction for viewing at 1000 mm if necessary) viewed each of the images from a distance of 1000 mm and adjusted the extreme visual field angle at zero elevation angle from a position on or near the center line of the display until the image was no longer visible with one eye. The extreme position of the viewer's eye was recorded. From the relationship S(θ), the security coefficient at that extreme position was determined. The measurements were repeated for various images, various display luminances Y max , various light box illuminances I(θ = 0), various background lighting conditions, and various viewers.

[0114] From the above measurements, S < 1.0 provides low or no visual security, and S ≥ 1 makes the image unviewable. In the range of 1.0 ≤ S < 1.5, although the image is unviewable for practical purposes, some features of the image can still be perceived depending on the contrast, spatial frequency, and temporal frequency of the image content. In the range of 1.5 ≤ S < 1.8, the image is unviewable to most images and most viewers, and in the range of S ≥ 1.8, the image is unviewable to all viewers regardless of the image content.

[0115] In an actual display device, this means that it is desirable to provide a value of S for off-axis viewers who are viewers satisfying the relationship of S ≥ S min , where S min having a value of 1.0 or more achieves the effect that the displayed image is unviewable to off-axis viewers in practical terms.

[0116] At the observed angle θ of the problem, the security coefficient S for the area of the display labeled by the index n nThis is given from equations 10 and 11 as follows: S n (θ) = log 10 [1+ρ n (θ).α(θ) / (π.P n (θ))] Equation 12 In the formula, α is the unit of knits (lumens, m). -2 .sr -1 Maximum brightness Y at ) max The angle of the problem from the display and the unit lux (lumens, m) -2 ) is the ratio of the illuminance I(θ) reflected onto the display, where α is in steradians, π is the solid angle in steradians, and ρ n (θ) is the reflectance of the display device along the observation direction in each nth region, and P n (θ) is the ratio of the brightness of the display device along the observation direction in each nth region.

[0117] In measuring human factors, the desired privacy display of this embodiment, as described below, typically has a maximum brightness of Y max When the ratio α of illuminance I to the observation angle is 4.0, the security coefficient S n It has been found to operate with a value of ≥1.0. For example, the illuminance I (θ=-45°) directed at a voyeur in the observation direction (θ=+45°) after illuminating the display and reflecting from the display could be 1000 lux, and the maximum display illuminance Y provided to the user max This could be 250 nits. This provides an image that is not visible on a wide range of real-world displays.

[0118] More preferably, the display has a security factor S at the observation angle when the ratio α is 2.0. n By operating with a value of ≥1.0, the reflectance ρ n (θ=45°) and Privacy P n It may have improved characteristics at (θ=45°). Such a configuration may have Y maxImprove the relative perceived brightness and contrast of the display for the primary user closer to the direction, while simultaneously achieving a desirable security coefficient S n It is desirable to achieve ≥1.0. Most preferably, the display has a security factor S at the observation angle when the ratio α is 1.0. n By operating with a value of ≥1.0, the reflectance ρ n (θ=45°) and Privacy P n (θ=45°) may have improved characteristics. Such a configuration may have Y compared to the brightness of the illuminated area around the display. max The display achieves a desirable high perceived brightness and contrast for the primary user closer to the viewing direction, while simultaneously achieving a desirable security factor S for off-axis viewers 47 in the viewing direction. n Achieve ≥1.0.

[0119] While the above considerations focus on reducing the visibility of the displayed image to off-axis viewers who are voyeurs, similar considerations also apply to the visibility of the displayed image to the target user of a display device, which is usually on-axis. In this case, a decrease in the Visual Security Level (VSL) V corresponds to an increase in the visibility of the image to the viewer. During observation, S < 0.2 may provide an acceptable visibility (perceived contrast ratio) of the displayed image, and more preferably, S < 0.1. In actual display devices, this corresponds to S ≤ S max It is desirable to provide a value of S for the on-axis viewer who is the target user of the display device that satisfies the relationship, where S max The value is 0.2.

[0120] In this discussion, the desired white spot (u w ', v w ') Output color (u w '+Δu', v w The color variation Δε of '+Δv' can be determined by the CIELUV color difference metric, assuming a typical display spectral light source, and is obtained by the following formula. Δε=(Δu'2 +Δv' 2 ) 1 / 2 formula 13

[0121] The diffraction effect in a liquid crystal layer is related to the interference or bending of waves around the corners of an obstacle or through an aperture into the geometric shadow region of the obstacle / aperture. The diffraction effect arises not from the propagation of light rays through the layer, but from the interaction of plane waves incident on the phase structure of the layer.

[0122] Here, the structure and operation of various directional display devices are described. In this description, common elements have common reference numbers. Note that any disclosure relating to any element applies to each device in which the same or corresponding element is provided. Therefore, for the sake of brevity, such disclosures are not repeated. For convenience, Table 1A lists the reference numbers, acronyms and corresponding features used herein, Table 1B lists the features used herein and the sub-features of each feature, and Table 1C lists the general features used herein and the specific features of those general features. [Table 1] Table 1A [Table 2] Table 1B [Table 3] Table 1C

[0123] It is sometimes desirable to provide a display device that can switch between a narrow-angle state and a wide-angle state. Here, the structure of a switchable display device is described.

[0124] Figure 1A is a schematic diagram illustrating a switchable display device 100 in a perspective side view, comprising a backlight 20 having a light source array 15, a waveguide 1, a back reflector 3, and an optical redirection component 50, a switchable diffractive field-of-view control retarder configuration (SDVACRA) 900 having a switchable diffractive liquid crystal retarder (SDLCR) 901 and a passive compensation retarder 930, and a transmissive SLM 48; Figure 1B is a schematic diagram illustrating an SDLCR 901 component 102 in a perspective side view; and Figure 1C is a schematic diagram illustrating an alignment orientation for an optical stack for use in the display device 100 of Figure 1A in a front perspective view. Features of embodiments of Figures 1B-C that are not discussed in further detail may be assumed to correspond to features of Figure 1A with equivalent reference numbers, including potential variations of the features.

[0125] The embodiment in Figure 1A illustrates a display device 100 comprising an SLM48 arranged to output spatially modulated light. The display device 100 further comprises a backlight 20 arranged to output light, and the SLM48 is a transmissive SLM48 arranged to receive the output light from the backlight 20. The SLM48 comprises a liquid crystal display device comprising transparent substrates 212, 216 and a liquid crystal layer 214 having red, green, and blue pixels 220, 222, 224. The SLM48 has an input display polarizer 210 and an output display polarizer 218 on either side thereof. The display polarizers 210, 218 are arranged to provide a high extinction ratio for light from pixels 220R, 220G, and 220B of the SLM48 and have electrical vector transmission directions 211, 219, respectively. Typical polarizers 210 and 218 can be absorptive polarizers such as dichroic polarizers, such as iodine polarizers on stretched PVA.

[0126] The backlight device 20 comprises a back reflector 3, a waveguide configuration 11 having a waveguide 1, a light source 15, a light redirection film 50, and a light control component 5 which may be arranged to receive light emitted from the waveguide 1 and directed through the SLM 48, and a diffuser. A reflective polarizer 27 may be provided between the backlight 20 and an additional polarizer 918 to improve the efficiency of the output light from the backlight 20 in order to achieve improved brightness. The reflective polarizer 27 may be omitted as an alternative. The reflective polarizer 27 operates differently from, for example, the reflective polarizer 302 shown below in Figure 16A, and achieves an increase in the security factor S. The backlight 20 in Figure 1A may be referred to as a collimated backlight. Other types of backlights 20 are described below and may be provided as alternatives to the backlight 20 in Figure 1A.

[0127] In the embodiment shown in Figure 1A, the display polarizer 910 is the input display polarizer 210 of the SLM48, which is located on the input side of the SLM48, and the display polarizer 910 is a linear polarizer. In the alternative embodiments described below, the display polarizer 910 may be the output polarizer 218.

[0128] The additional polarizer 918 is located on the same input side of the SLM48 as the outer display polarizer 910, and the additional polarizer 918 is a linear polarizer. In other words, the display polarizer 910 is the input display polarizer 210 located on the input side of the SLM48, and the additional polarizer 918 and SDVACRA900 are located between the backlight 20 and the SLM48.

[0129] In this specification, the SDVACRA900 comprises at least one switchable liquid crystal layer disposed between a polarizer pair. In the embodiments shown in Figures 1A-D, the SDVACRA900 is disposed between an additional polarizer 918 and a display polarizer 910 which is an input polarizer 210. The SDVACRA900 comprises an SDLCR901 which comprises a layer 914 of liquid crystal material 915 disposed between transparent substrates 912, 916. The SDVACRA900 further comprises a passive compensation retarder 930.

[0130] The transparent electrode configuration 904 comprises uniform electrodes 902R, 902C, and a patterned electrode 902A, and is arranged to drive a layer 914 of the liquid crystal material 915 by a voltage V applied from a voltage driver 950. The display device 100 further comprises a control system 500 arranged to supply voltage to the transparent electrode configuration 904 by the driver 950 in order to drive the layer 914 of the liquid crystal material 915.

[0131] The display device 100 may provide a field of view axis 445 and a tilt axis 447 tilted to the field of view axis 445.

[0132] In this embodiment, the narrow-angle state refers to a state of the display device 100 (or its components) in which the display device 100 (or its components) can be driven to provide, for example, a privacy operating mode. The privacy operating mode may be configured to provide the viewer 45 with an image having high image visibility along the field of view axis 445, and may be configured to provide the viewer 47 with a voyeuristic image having a high security factor along the tilt axis 447, so that the viewer 47 cannot see the image data from the display device 100 when the device is positioned under appropriate external lighting conditions. Alternatively, the viewer 47 may be the driver of a vehicle, and the privacy display may be positioned to reduce driver distraction when providing infotainment images to the passenger, who is the viewer 45.

[0133] The narrow-angle state may, alternatively or additionally, provide a low-stray-light operating mode such that the illuminance provided to the surrounding environment is reduced. Such a display device 100 can advantageously reduce driver distraction resulting from the brightly lit interior of the vehicle in which the display device is installed.

[0134] For comparison, the wide-angle state refers to the state of the display device 100, which can be used, for example, to provide a shared operating mode for the display device 100. The shared operating mode can be configured to provide image data from the display device 100 to both the viewer 45 along axis 445 and the viewer along tilt axis 447. Advantageously, both viewers (or yet another viewer) can see the image provided by the display device 100.

[0135] The intermediate state refers to a state of the display device 100 that is configured to have brightness characteristics intermediate between the narrow-angle state and the wide-angle state. The intermediate state may be configured to provide some image data to the viewer 47 while maintaining high image visibility to the viewer 45. Power consumption of the display device may be reduced compared to the wide-angle state, and the intermediate state may provide a highly efficient operating mode.

[0136] The display device has an optical axis 199 perpendicular to at least one region of the display device 100.

[0137] The field of view axis 445 may be the direction in which the viewer 45 is provided with maximum image visibility. The tilt axis 447 may be the direction of the viewer 47 normal to the viewer 47 in the narrow-angle state of the display device 100. Alternatively, the field of view axis 447 may be the minimum angle φ between the field of view axis 445 and the tilt axis 447 in which the desired security factor S is achieved. In an exemplary embodiment, the display device 100 may be installed in a laptop, where the field of view axis 445 is along the normal to the display device 100, and the tilt axis 447 is 45° laterally with respect to the field of view axis and has the same elevation angle. In an alternative exemplary embodiment, the display device 100 may be installed in a passenger infotainment display, where the field of view axis 445 is offset at an angle of +5° laterally from the optical axis 199, and the tilt axis 447 is -25° laterally with respect to the field of view axis and has the same elevation angle. A driver 47 leaning towards the display device cannot see distracting images at an angle of 25° or more from the normal 199 for an elevation angle of zero degrees.

[0138] The nominal display user 45's viewing axis 445 may be parallel to the optical axis 199 in a display such as a laptop where the user 45 is preferably centered relative to the display device 100. In other words, the viewing axis 445 is perpendicular to the plane of the SLM 48. In applications such as automotive, the viewing axis 445 may differ from the direction of the optical axis 199.

[0139] In the narrow-angle state, the non-field-of-view tilt axis 447, i.e., the direction in which the display eavesdropper is positioned, is offset by, for example, 5° laterally from the optical axis 199 and tilted at an extreme angle φ with respect to the field-of-view axis 445.

[0140] Figure 1B is an alternative embodiment showing that the SDLCR901 may be provided as a separate component 102. Component 102 may further comprise a passive compensation retarder 930 and a polarizer 918. Component 102 may be added during the manufacture of the display device 100, or alternatively, added to the SLM48 by the display user 45. Advantageously, a switchable upgrade of the display device 100 may be provided.

[0141] Here, the configuration of the optical layers of the display device 100 will be described. In this exemplary embodiment, the orientation of each layer is measured counterclockwise from the east when viewing the front of the display device 100.

[0142] Figure 1C illustrates that the backlight 20 typically provides an unpolarized or partially polarized state 21. An additional polarizer 918 having an electrical vector transmission direction 919 provides a linearly polarized state output incident on the SDVACRA 900.

[0143] The electrode 902A of the SDLCR901 is patterned and positioned to extend along a vertical axis with an orientation angle of 90°. The diffraction order directions described below are provided along the transverse axis (x-axis direction) from 0° to 180°.

[0144] SDLCR901 comprises surface alignment layers 917A and 917B, which are located adjacent to and on both sides of layer 914 of the liquid crystal material 915, and each of the two surface alignment layers 917A and 917B is arranged to provide alignment of adjacent liquid crystal material 915 on the surface of surface alignment layers 917A and 917B. The alignment directions 927A and 927B in each of the surface alignment layers 917A and 917B provide in-plane components 927Ap and 927Bp in the plane of layer 914 of the liquid crystal material 915. Furthermore, pre-tilting in alignment directions 927A and 927B reduces the degeneration of the orientation structure 965 of the liquid crystal material 915 and, advantageously, improves the uniformity across the region 103 of the layer 914 of the liquid crystal material 915, in the thickness direction through the layer 914 of the liquid crystal material 915.

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[0145] The surface alignment layer 917A on the liquid crystal layer side adjacent to the array of separation electrodes 902A has a component 927Ap of in-plane alignment of the liquid crystal material 915 layer 914 in a direction 197 perpendicular to one direction 195.

[0146] Region 103 of the liquid crystal material 915 may extend throughout the SLM 48. In a particular operating mode of the display device, the electrode configuration 904 may be further arranged so that the control system 500 and driver 950 can control the display device 100, and as a result, some regions 103A of region 103 may be arranged to provide a first operating state, and other regions 103B of region 103 may provide a second operating state different from the first state. For example, one region 103A of the display device 100 may be arranged in a narrow-angle state, and another region 103B may be arranged in a wide-angle state, as will be further described below.

[0147] The passive compensation retarder 930 may comprise, for example, a C-plate having an optical axis direction 931. Alternatively, the passive compensation retarder 930 may be provided by, for example, intersecting A-plates.

[0148] Figure 1D is a schematic diagram illustrating the electrode 902 and liquid crystal material structure for SDLCR901 in non-driven mode in a perspective front view. Features of the embodiment in Figure 1D that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0149] Figure 1D is a schematic diagram illustrating, in a perspective front view, the structure 965 of the electrodes and liquid crystal material 915 for the SDVACRA900 in a non-driving mode, i.e., when zero volts are applied across the layer 914 of the liquid crystal material 915. At least one of the surface alignment layers 917A and 917B is arranged to provide homogeneous alignment of adjacent liquid crystal material 915. As will be further described below with respect to Table 2, surface alignment layer 917A provides homogeneous alignment and surface alignment layer 917B provides homeotropic alignment, providing alignment directions 927A and 927B, respectively. The liquid crystal material 915 has a thickness direction

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[0150] Here, we will describe an example electrode configuration 904.

[0151] Figure 1E is a schematic diagram illustrating a permeable electrode configuration 904 for the SDLCR901 of Figure 1A in a perspective side view, and Figure 1F is a schematic diagram illustrating an alternative configuration for the permeable separation electrode 902A in a front view. Features of embodiments in Figures 1E-F that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0152] The transparent electrode configuration 904 in Figure 1E comprises a transparent isolation electrode 902A and a transparent homogeneous electrode 902C disposed on the first side of layer 914 of the liquid crystal material 915, and a homogeneous transparent reference electrode 902R disposed on the opposite side of layer 914 of the liquid crystal material 915. A dielectric material 905, such as SiOx or SiN, may be disposed between the transparent isolation electrode 902A and the transparent control electrode 902C. Electrodes 902A, 902C, and 902R may be provided by a transparent conductive material such as ITO.

[0153] Electrodes 902A and 902C may be embedded by dielectric materials 905 having their respective refractive indices, arranged to reduce diffraction from electrode 902A and the gap 932 in direction 195 between electrodes 902A. Advantageously, diffraction in the narrow-angle state is reduced, improving the security coefficient S for off-axis eavesdroppers 47 in the privacy operating mode.

[0154] The transparent electrode configuration 904 comprises an array of separation electrodes 902A, which are arranged in one direction 195, i.e., across the transverse direction (x-axis). The separation electrodes 902A extend across a region 103 of the liquid crystal material 915 layer 914 in a direction perpendicular to the one direction 195.

[0155] The width w of electrode 902A and the pitch p of electrode 902A may be selected to provide the desired diffraction characteristics of SDLCR901 when driven in a wide-angle state, as will be further described below.

[0156] In the embodiment of Figure 1E, the isolation electrode 902A has a common connection busbar 903. In other embodiments, such as those further described below, at least some of the isolation electrodes 902A may be connected separately. An alternative embodiment of Figure 1F illustrates common busbars 903T, 903B, 903L, and 903R. The common connection is formed by a conductor located outside the area of ​​the SLM48, i.e., the common busbar 903 is illustrated to be located outside the boundary 101 of the active area 103 of the display device 100. Figure 1E illustrates a common busbar 903 to one end of the isolation electrode 902A, but the busbar connection portion of the common busbar 903 may extend to surround the isolation electrode 902A, resulting in the busbar extending along both ends 903T, 903B, and optionally along the sides 903L, 903R. By connecting both ends, the impedance of the "finger portion" of the isolation electrode can be substantially reduced, and the isolation electrode is then electrically connected in parallel to achieve the reduced impedance. Further common electrode busbars 903 may be provided by electrodes of a transparent common busbar 903 within the active region, or by a transparent or low-impedance material such as metal, which is a light-blocking electrode outside the active region 103. Voltage drop along the transparent electrode 902 can be reduced, and advantageously, increased uniformity can be achieved.

[0157] The transparent electrode configuration 904 further comprises a control electrode 902C extending across layer 914, the control electrode 902C being located outside the array of isolation electrodes 902A and on the same side of layer 914 of the liquid crystal material 915 as the array of isolation electrodes 902A. The control electrode 902C and the reference electrode 902R may be planar electrodes.

[0158] The transparent electrode configuration 904 further comprises a reference electrode 902R extending throughout the SLM48, the reference electrode 902R being positioned opposite the layer 914 of liquid crystal material 915 from the array of isolation electrodes 902A.

[0159] Each of the voltage drivers 950A and 950B controls the voltage signal V between electrodes 902A and 902C, as will be further explained below. AC And the voltage signal V CR The electrode configuration 904 is provided to be driven by the above.

[0160] Here, the structure and operation of the display device 100 operating in wide-angle mode will be further described.

[0161] Figure 2A is a schematic diagram illustrating the structure and operation of an optical stack comprising an SDVACRA900 with an SDLCR901 having the electrode configuration 904 of Figure 1E in the wide-angle state, in a top view, and Figure 2B is a schematic diagram illustrating the transmissive electrode configuration 904 and structure 965 of the orientation of the liquid crystal material 915 for the SDLCR901 in the wide-angle state, in a perspective front view. Features of embodiments of Figures 2A-B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0162] Figure 2A illustrates a backlight 20 that provides light output in a cone 461 having high brightness in direction 460 and low brightness in direction 462. As will be further explained below in Figures 2F-G, a plane wave 470 propagates in direction 460. The SDVACRA operates by diffracting the input light, providing a phase difference Γ(x) to the output wavefront 474. The output light 464 is diffracted into a cone 465 having a maximum angular spread of half its total width laterally, which is larger than that of the cone 461. Advantageously, improved image visibility is observed in wide-angle locations under wide-angle conditions.

[0163] Figures 2A-B show the electric field E with electric field line 907 in layer 914, where adjacent electrodes 902A1 and 902A2 provide reorientation of the liquid crystal material 915 into gap 932.A1C , E A2C This provides the greatest size possible not only near the surface alignment layer 917A but also through the layer 914 of the liquid crystal material 915, across region 103 and in the thickness direction.

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[0164] Figure 2C is a schematic diagram illustrating, in a top view, the transmissive electrode configuration 904 and simulated structure 965 of the orientation of the liquid crystal material 915 for SDLCR901 in the wide-angle state for illustrative embodiments in Tables 2-3. Features of the embodiments of Figure 2C that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features. [Table 4] Table 2 [Table 5] Table 3

[0165] In this embodiment, the drive voltage

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[0166] Figure 1A and Table 2 illustrate an example where the passive compensation retarder 930 is located on the side of layer 914 of the liquid crystal material 915, which has a homeotropic alignment layer 917B. It may be desirable to provide the passive compensation retarder 930 on the input side of the SDLCR 901, in which case the alignment layer 917A is homeotropic and the alignment layer 917B is homogeneous. Similarly, the sequence of electrodes 902C, 902A, and 902R is reversed, i.e., the patterned electrode 902A is located next to the homogeneous alignment layer 917B.

[0167] Figure 2C shows that the reorientation of structure 965 can occur mainly in layer 970A, which is close to the surface alignment layer 917A, but in the thickness direction.

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[0168] Figure 2D is a schematic graph illustrating the diffraction luminance profile 430 to diffraction order for the embodiment of Figure 2C in the wide-angle state; Figure 2E is a schematic graph illustrating the variation in the diffraction profile with respect to the drive voltage for the embodiment of Figure 2C; Figure 2F is a schematic graph illustrating the variation in the total diffraction intensity with respect to the drive voltage for the embodiment of Figure 2E; and Figure 2G is a schematic graph illustrating the diffraction luminance profile 430 to diffraction order for the embodiments of Figure 2C and Table 2 in the wide-angle state for different drive voltages. Features of the embodiments of Figures 2D-G, which are not discussed in further detail, can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0169] Figure 2D illustrates the higher-order diffraction of light 460 and provides profile 430. For example, the final power distribution illustrated in Figure 8G below can be provided by the interaction between the input optical cone and SDVACRA900, as illustrated in Figure 8A below.

[0170] Table 2 shows illustrative voltages in three different operating modes applied using, for example, the waveforms in Figures 7A-C below. Applied voltage V AC and V CR This is typically an AC voltage such that the net DC voltage applied to the liquid crystal material 915 is not exceeded for more than 1 second. This reduces charge accumulation within layer 914 of the liquid crystal material 915, which is advantageous as it extends its lifespan.

[0171] Here, we will describe an alternative structure for the SDVACRA900 that is driven in various wide-angle situations.

[0172] Figure 2E shows different drive voltages V AC Various diffraction output profiles 430 for different voltages are illustrated. Profile 430 in Figure 2D is illustrated as profile 430(10V) for + / -10V in Figure 2E. Diffraction diffusion increases as the voltage increases.

[0173] Figure 2F illustrates the total power output through the display polarizer 910 in Figure 2A for different drive voltages, where Vp is the desired voltage provided when operating in a narrow-angle state. At low voltages, there is little correction of the linear polarization state 919 input to the SDVACRA 900, and most of the input light passes through the display polarizer 910.

[0174] Figure 2G shows the amount of light dispersion provided by the SDVACRA900 at the drive voltage level V in the wide-angle state. AC , V CR This illustrates how adjustments can be made. The control system 500 may be configured to provide selections of peak brightness, power efficiency, and image visibility by controlling each voltage driver 950. Depending on the desired characteristics for the operation of the display device 100, an increase in display performance can be advantageously achieved.

[0175] In the case of an intermediate drive voltage, the reorientation of structure 965 provides different retardations in layer 914 of the liquid crystal material 915. As illustrated in Figure 5D below, a phase difference η is provided for orthogonal polarization states propagating through layer 914 of the liquid crystal material in different angular directions, and some of the light is absorbed by the display polarizer 910. Additionally, a wavefront phase difference Γ is provided transversely to achieve a diffraction effect.

[0176] For higher drive voltages such as + / -10V, the total output brightness increases again as such a phase difference η in the case of orthogonal polarization decreases, and structure 965 mainly provides the diffracted wavefront phase difference Γ. The drive voltage can be adjusted to provide increased efficiency, improved visibility along the tilt axis 447, and reduced power consumption.

[0177] Here, we will further explain the operation of the display device 100 in the wide-angle state.

[0178] Figure 3A is a schematic diagram illustrating the structure and operation of a display device equipped with SDVACRA900 in the wide-angle state, shown in a top view. Features of the embodiment in Figure 3A that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0179] The backlight 20 provides light in the light cone 461. The size of the cone 461 can be determined, for example, by the angle of maximum brightness at half the total width. In the wide-angle state, diffraction in SDLCR901 provides an output cone 463 with an increased conical angle. In the angular cone 467, SDVACRA900 provides a slight reduction in the brightness of the light directed to the cone 463 resulting from the phase difference η of SDVACRA900, or provides virtually no reduction.

[0180] During operation, viewers 45 closer to the field of view axis 445, and viewers 47L and 47R further closer to the tilt axes 447L and 447R, also see the light directed from the display device at a higher brightness than that provided by the light cone 461. Advantageously, the brightness in the wide-angle state increases, and image visibility to viewers 47L and 47R increases. Hereinafter, the tilt axis 447 is tilted relative to the field of view axis 445.

[0181] Here, a further explanation is given regarding the phase shift of the light diffracted in SDLCR901.

[0182] Figure 3B is a schematic diagram illustrating the propagation of a first linear polarization state 909 through an SDLCR 901 arranged in a wide-angle state in a top view; Figure 3C is a schematic diagram illustrating the propagation of a first polarization state 909 through an SDLCR 901 arranged in a wide-angle state in a perspective front view; Figure 3D is a schematic diagram illustrating the propagation of a second linear polarization state 911 orthogonal to the first polarization state 909 through a layer 914 containing an SDLCR 901 arranged in a wide-angle state in a top view; and Figure 3E is a schematic diagram illustrating the propagation of a second polarization state 911 through a layer containing an SDLCR 901 arranged in a wide-angle state in a perspective front view. Features of embodiments in Figures 3B-E that are not discussed in further detail can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0183] Figure 3B illustrates a plane wave 470 having a linearly polarized state 909 that propagates through a layer 914 of liquid crystal material 915. The layer 914 has an orientation structure 965 of the liquid crystal material 915 that varies spatially in the lateral direction 195 in the wide-angle state.

[0184] Figures 3B-C illustrate the ray 460 provided by the plane wave 470 incident on SDLCR901. The input polarization state 909 is such that the plane wave 470 having polarization state 909 is within region 970A close to the surface alignment layer 917A, and the anomalous refractive index n of the liquid crystal material 915. e and the refractive index n o The liquid crystal material 915 is incident at different angles with respect to the optical axis 977 to observe a refractive index that can vary between 909 and 909. In other words, at some locations, the wavefront 470 with input polarization state 909 experiences the ordinary refractive index of the liquid crystal material 915, while at spatially separated locations, the wavefront 470 with input polarization state 909 experiences a refractive index close to the extraordinary refractive index of the liquid crystal material 915. Thus, such a spatially varying refractive index profile provides a net relative phase shift to the input light represented by the spatially varying wavefront 470.

[0185] In comparison with Figure 3B, Figure 3D illustrates a plane wave 470 having a linearly polarized state 911 propagating through a layer 914 of liquid crystal material 915. In the configurations of Figures 3D-E, the polarized state 911 sees nearly the same paraphotonic refractive index of the liquid crystal material 915 for all spatial positions. Therefore, the plane wave 470 having the polarized state 911 sees no or only a small modulation of phase Γ0, and the layer 914 of liquid crystal material 915 provides no or only a small diffraction effect. The plane wave 470 experiencing the uniform birefringence of the layer 914 of liquid crystal material 915 has a uniform phase Γ0 and does not diffract.

[0186] We will further consider the spatially fluctuating phase shift of the incident polarization states 909 and 911 of the light transmitted through the layer 914 of the liquid crystal material 915 of the SDLCR901 arranged in wide-angle mode.

[0187] Figure 3F is a schematic diagram illustrating in a top view the propagation of a ray 460 having orthogonal polarization states 909, 911 for two different positions x0, x1 across layer 914 through layer 914 of an SDLCR 901 arranged in a wide-angle state; Figure 3G is a schematic diagram illustrating in a top view the configuration of Figure 3F with an additional polarizer 918, which is an input polarizer; and Figure 3H is a schematic diagram illustrating in a top view the configuration of Figure 3F with an output polarizer 910, which is an input polarizer 210. Features of embodiments of Figures 3F-H that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0188] Figures 3F-H illustrate the illumination of a liquid crystal material layer 914 by light rays 460(909) and 460(911), where the light rays have polarization states 909 and 911, respectively. The input wavefront 470 is arranged so that polarization states 909 and 911 have the same nominal phases η0(909) and η0(911), and so that the net phase shift Δη after propagation through layer 914 can be determined.

[0189] The polarization states 909 and 911 can alternatively describe the orthogonal components of a single polarization state, which are eigenstates of the polarization state and can be used to determine the behavior of the polarization state as it passes through the birefringent layer.

[0190] An incident line 460(909, x0) with polarization state 909, incident on layer 914 at location x=x0 having structure 965(x0), has the ordinary refractive index n of the liquid crystal material 915. o The incident line 460(911, x0) having polarization state 911 incident on layer 914 at position x=x0 having structure 965(x0) has the ordinary refractive index n of the liquid crystal material 915. o We also experienced that the net phase shift Δη(x0) of the light transmitted through layer 914 to the orthogonal polarization states 909 and 911 is zero.

[0191] Comparing this to location x1, which is spatially separated from location x0 by a distance δx in the lateral direction of 195, the incident line 460(909,x1) having polarization state 909 incident on layer 914 at position x=x1, which has structure 965(x1), is the anomalous refractive index n of the liquid crystal material 915. e Having experienced this, an incident line 460(911,x1) having polarization state 911 incident on layer 914 at position x=x1, having structure 965(x1), has the ordinary refractive index n of the liquid crystal material 915. o This is experienced. Therefore, the net phase shift Δη(x1) to the orthogonal polarization states 909 and 911 of the light transmitted through layer 914 is not zero. Net phase shift Δη to the orthogonal polarization states 909 and 911 (which may be the orthogonal polarization components of the polarization states) of the light transmitted through layer 914 r (δx) is therefore, Δη r (δx) = Δη(x1) - Δη(x0) Equation 14 The net phase shift Δη is r It varies spatially.

[0192] In Figure 3G, the additional polarizer 918 absorbs ray 460 (911), causing a phase shift Δη of polarization state 909. rOnly (δx) is considered. In the case of the light ray 460(909, x0) having the polarization state 909, the net phase shift is, therefore, Δη r (δx)=Δη(x1) Equation 15 and in the embodiments of FIGS. 3F - H, it is the same result as in the case of Equation 14.

[0193] Compared with FIG. 3F, the display polarizer 910 absorbs the light ray 460(911) after passing through the layer 914. The net phase shift is the same as in the case of Equation 14.

[0194] Therefore, the layer 914 of the liquid crystal material 915 introduces a net phase shift Δη r (x) that varies spatially across the region 103 of the layer 914 of the liquid crystal material 915 into the light 460 having a predetermined polarization state 909, thereby providing a diffraction effect to the light 460 having a predetermined polarization state 909 in the layer 914 of the liquid crystal material 915, and a wide - angle state having an alignment structure 965 is provided.

[0195] As illustrated in FIGS. 3B - C, such a spatially varying net phase shift Δη r (δx) provides a net phase difference Γ of the wavefront that also varies spatially as Γ(x) when exiting the material to the output wavefront 474 from the entire region of the layer 914. The net phase shift Δη r (x) and this spatial variation of the subsequent net phase difference Γ(x) of the wavefront provide the diffracted wavefront 474, whereby the light output 464 can alternatively be considered as a series of plane waves propagating at different luminances and angles.

[0196] Therefore, the transparent electrode configuration 904 is patterned such that the layer 914 of the liquid crystal material 915 can be selectively driven into an orientation structure 965 that introduces a spatially varying net phase shift across the region 103 of the layer 914 of the liquid crystal material 915 to light having a predetermined polarization state 909, thereby causing the layer 914 of the liquid crystal material 915 to provide a diffraction effect to light having a predetermined polarization state 909.

[0197] The separation electrode 902A is arranged over a lateral direction of 195, and in the wide-angle state, the orientation structure 965 of the layer 914 of the liquid crystal material 915 causes a net phase shift that provides a net wavefront phase difference Γ(x) that spatially varies in one direction 195 over a region 103 of the layer 914 of the liquid crystal material 915, thereby causing the layer 914 of the liquid crystal material 915 to provide a diffraction effect in one direction 195. Referring to Figure 2A, the control system 500 is arranged to supply a voltage to the transparent electrode configuration 904 that is selected to drive the liquid crystal material 915 to the orientation structure 965 that provides a net phase shift Δη with a resulting net wavefront phase difference Γ(x) that spatially varies over a region 103 of the layer 914 of the liquid crystal material 915 in the wide-angle state, and to cause the layer 914 of the liquid crystal material 915 to provide a diffraction effect.

[0198] Another way to represent this embodiment is that at least one polarity control retarder is disposed between the additional polarizer 918 and the display polarizer 910, and at least one polarity control retarder is SDVACRA900 (or SDVACA800 in the embodiments below). In this specification, a polarity control retarder is a retarder disposed between a polarizer pair to provide a transmission variation with a viewing angle in at least one operating mode.

[0199] At least one polarity-controlled retarder includes a switchable liquid crystal retarder comprising a layer 914 of liquid crystal material 915 and a transparent electrode configuration 904 disposed to drive the layer 914 of liquid crystal material 915. The transparent electrode configuration 904 is patterned to be able to drive the layer 914 of liquid crystal material 915 into an orientation structure 965 that provides a spatially varied net phase shift Δη(x) over a region 103 of the layer 914 of liquid crystal material 915, such that the layer 914 of liquid crystal material 915 provides a diffraction effect. The transparent electrode configuration 904 can also drive the layer 914 of liquid crystal material 915 into an orientation structure 965 that provides a uniform phase shift η over a region 103 of the layer 914 of liquid crystal material 915, such that the layer 914 of liquid crystal material 915 does not provide a diffraction effect.

[0200] Here, we will describe the operation of the display 100 when it is operating in a narrow-angle state.

[0201] Figure 4A is a schematic diagram illustrating the structure and operation of the optical stack 104 with SDVACRA900 in the narrow-angle state in a top view; Figure 4B is a schematic diagram illustrating the configuration 904 of the orientation structure 965 of electrodes 902A, 902C, 902R and liquid crystal material 915 for SDLCR901 in the narrow-angle state in a perspective front view; and Figure 4C is a schematic diagram illustrating the configuration 904 of the orientation structure 965 of electrodes 902A, 902C, 902R and liquid crystal material 915 for SDLCR901 in the narrow-angle state in a top view. Features of embodiments of Figures 4A-C that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0202] The control system 500 is configured to supply a voltage to the transparent electrode configuration 904 that is selected to drive the layer 914 of the liquid crystal material 915 to a narrow angle state, as illustrated in Figure 4A, and to supply a voltage to the transparent electrode configuration 904 that is selected to drive the layer 914 of the liquid crystal material 915 to a wide angle state, as illustrated in Figure 2A of this specification.

[0203] In an alternative embodiment of Figure 4A, the control system 500 of Figure 1A is configured to supply a voltage to a transparent electrode configuration 904 that is selected to drive an orientation structure 965 that provides the liquid crystal material 915 with a net phase shift having a net wavefront phase difference Γ(x) that is uniform across a region 103 of the layer 914 of the liquid crystal material 915 in a narrow-angle state.

[0204] Referring to Table 3, a uniform orientation structure 965 of the liquid crystal material 915 is provided across region 103 by voltage V CR This is applied to the reference electrode 902R, the separation electrode 902A, and the control electrode 902C. In other words, the transparent electrode configuration 904 can selectively drive the layer 914 of the liquid crystal material 915 to a narrow-angle state (for example, for use in privacy operation mode) having an orientation structure 965 that causes the layer 914 of the liquid crystal material 915 to introduce a net phase shift uniform across the region 103 of the layer 914 of the liquid crystal material 915 into the light having a predetermined polarization state 909, thereby preventing the layer 914 of the liquid crystal material 915 from providing a diffraction effect, i.e., the SDLCR 901 from dispersing light in the narrow-angle state.

[0205] Comparing the alternative embodiments in Figures 4B-C with those in Figures 2B-C above, the liquid crystal material 915 has substantially the same alignment across the region 103 of layer 914.

[0206] This embodiment achieves a switch between (i) a wide-angle state in which the optical axis 977 of the liquid crystal material 915 is aligned with a component along direction 195, and (ii) a narrow-angle state in which the optical axis of the liquid crystal material 915 is aligned with a direction perpendicular to direction 195, provided, for example, by the direction 927Ap of the surface alignment layer 917A. In other words, the switch can be provided by in-plane rotation of the liquid crystal material 915 by applying an appropriate drive voltage.

[0207] Furthermore, the liquid crystal material 915 layer 914 introduces different net relative phase shifts along the field axis 445 and the tilt axis 447 tilted to the field axis 445 into the orthogonal polarization components of the light having a predetermined polarization state 909, as described below with respect to, for example, Figures 5D to E.

[0208] Figure 5A is a schematic diagram illustrating the structure and operation of the display device 100, which includes the SDVACRA900, in the wide-angle state, in a top view. Features of the embodiment in Figure 5A that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0209] Compared to Figure 3A, the cone 461 is not diffused by diffraction of SDLCR 901. Furthermore, the layer 914 of the liquid crystal material 915 provides brightness reduction of the light cone 467 such that the output cone 469 is reduced in size compared to the input light cone 461. A viewer 47 along the tilt axis 447 sees the reduced image brightness.

[0210] Such a configuration is advantageous in that it achieves high image security S on the desired non-field-of-view tilt axis 447 in privacy mode, while providing a switch to a wide-angle state with high image visibility on the field-of-view axis 445, as illustrated in Figure 3A.

[0211] Here, we will describe the operation of the SDLCR901 when it is driven uniformly across region 103.

[0212] Figure 5B is a schematic diagram illustrating the propagation of a first linearly polarized state 909 through a layer 914 containing an SDLCR 901 arranged in a narrow-angle state, in a top view, and Figure 5C is a schematic diagram illustrating the propagation of a first linearly polarized state 909 through a layer 914 containing an SDLCR 901 arranged in a narrow-angle state, in a perspective front view. Features of embodiments in Figures 5B-C that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0213] Compared with Figures 3B-C, the alternative embodiments in Figures 5B-C illustrate that the input plane wave 470 is not substantially modified by the phase structure of the SDLCR901, resulting in a uniform output phase shift Γ0. Ray 462 is output with reduced intensity as ray 463 along the tilt axis 447, while ray 460 is output with substantially full brightness. Advantageously, a small cone 461 is provided for narrow-angle operation.

[0214] Here, we will explain the correction of transmission with polar angles by the SDLCR901 when driven in a narrow-angle state.

[0215] Figure 5D is a schematic diagram illustrating, in a perspective side view, the propagation of a first linearly polarized state 909 through a layer 914 comprising liquid crystal molecules 925 tilted for first and second different polarization directions 447, 446. Features of the embodiment of Figure 5D that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0216] Figure 5D shows an exemplary single liquid crystal molecule 925 aligned with non-zero inclinations φ(446), φ(447), away from the normal direction 199, as provided by the narrow-angle voltage driving conditions in Figure 4A. In practice, the orientation φ of the molecular optical axis 977 is in the thickness direction, as described elsewhere in this specification.

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[0217] The polarization state 909(445) along the field axis 445 (propagating downwards and parallel to the normal direction 199 in Figure 5D) is observed as the ordinary refractive index of molecule 915, and therefore remains uncorrected through layer 914.

[0218] The polarization state 909(446) along the axis 446 tilted at a certain angle in direction 197 also observes the ordinary refractive index of molecule 915 and is therefore not modified through layer 914.

[0219] In comparison, when ray 447 is incident on molecule 925, the polarization state 909(447) is decomposed into eigenstates 997(447) and 999(447) that see both birefringent components ne and no of molecule 925. The angle φ between the polarization eigenstates 997(447) and 999(447) is... 447 Phase shift η(φ 447 This provides a resulting elliptic polarization state 995(447) that is different from the input state 909(447). The component 999(447) is absorbed by the display polarizer 910, and the off-axis brightness decreases along axis 447. Therefore, the transmission of the layer 914 placed between the parallel polarizers varies with angle φ. Such a configuration provides a transmission profile illustrated, for example, in Figure 8B below.

[0220] Therefore, in this disclosure, the spatially varying phase shift with the net phase difference Γ(x) of the wavefront of the diffraction structure 965 in Figure 3B above is different from the phase shift η that provides the angular polarization correction in the non-diffraction structure 965 in Figure 5B.

[0221] Returning to the explanation of Figures 3B-C, the orientation structure 965 of the liquid crystal material 915 provides a net phase difference Γ(x) of the wavefront that fluctuates across the region 103 of layer 914 of the liquid crystal material 915, and SDVACRA900 provides a net relative phase shift η(φ 445 It is even more preferable that the additional polarizer 918 is positioned along the field axis 445 so as not to introduce the orthogonal polarization components 997(445) and 999(445) of the light passing through it, and that the SDVACRA900 has a net relative phase shift η(φ 447 It is desirable that the additional polarizer 918 is positioned so as not to introduce the orthogonal polarization components 997(447), 999(447) of light passing through it along the tilt axis 447 tilted to the field axis 445. A wide-angle state may be provided.

[0222] Returning to the description of FIGS. 5B - C, the alignment structure 965 of the liquid crystal material 915 that provides a net phase difference Γ0 of the wavefront that is uniform across the region 103 of the layer 914 of the liquid crystal material 915 causes the SDVACRA900 not to introduce a net relative phase shift η(φ 445 ) into the orthogonal polarization components 997(445), 999(445) of the light passing through the additional polarizer 918 along the viewing axis 445. It is further desirable to arrange the SDVACRA900 so as to introduce a net relative phase shift η(φ 447 ) into the orthogonal polarization components 997(447), 999(447) of the light passing through the additional polarizer 918 along the tilt axis 447 tilted with respect to the viewing axis 445. A narrow - angle state can be provided.

[0223] Returning to the graph of FIG. 2F, in fact, in embodiments where the optical axis of the birefringent material varies spatially, both the net phase difference Γ(x) of the diffracted wavefront that provides polarization mixing between the orthogonal polarization states 995, 997 and the net relative phase shift η(φ 447 ) can exist. It may be desirable to minimize the net relative phase shift η(φ 447 ) of the polarization and provide a drive voltage to provide an increase in efficiency at wide angles. To reduce polarization mixing, the alignment structure 965 of the liquid crystal material 915 in the diffractive state is provided with an optical axis direction 977 oriented in the lateral direction 195 (x - axis), and their projected optical axes are made parallel or perpendicular to the horizontally or vertically polarized 909, 911, plane waves 470 that travel through the layer 914 of the liquid crystal material 915 in the horizontal plane. Advantageously, the optical loss is reduced. The alignment condition when driven provides a small luminance correction with a transmission efficiency of more than 60%, and preferably more than 80%, compared to the condition where the optical axis direction 977 is uniformly aligned parallel or orthogonal to the incident polarization state 909.

[0224] Figure 5E is a schematic diagram illustrating, in a top view, the propagation of SDLCR 901 through layer 914 arranged in a narrow-angle state for light rays along the viewing axis 445 and tilt axis 447 for two different positions x0, x1 across a region 103 of layer 914 of liquid crystal material 915. Features of embodiments of Figure 5E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0225] In comparison with Figures 3F to 3H, Figure 5E illustrates the narrow-angle state of layer 914 of the liquid crystal material 915.

[0226] The layer 914 of the liquid crystal material 915 has an orientation structure 965 that introduces a net phase shift η(445), η(447) uniform across the region 103 of the layer 914 of the liquid crystal material 915 to light having a predetermined polarization state 909, thereby preventing the layer 914 of the liquid crystal material 915 from providing a diffraction effect to light rays along axes 445, 447 having a predetermined polarization state 909. Therefore, the operation of the layer 914 is uniform across the region 103 in the plane of the layer 914, and the behavior at location x0 is the same as the behavior at location x1.

[0227] Furthermore, the liquid crystal material layer 915 has an orientation structure 965 that introduces different net relative phase shifts η(φ445) and η(φ447) along the field axis 445 and the tilt axis 447 tilted to the field axis 445 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909. Along the field axis 445, the net relative phase shift η(φ445) can be zero, and the polarization state 909 is maintained. Compared along the tilt axis, the net relative phase shift η(φ447) is non-zero, and the polarization state 909 is converted to an elliptic polarization state 995(447) due to the net relative phase shift η(φ447) of the polarization components 997(447) and 999(447).

[0228] Reduced transmission of SDVACRA900 can be provided along the gradient direction 447, and scattering resulting from diffraction in layer 914 is minimized so that an improved security coefficient S is achieved in privacy operating mode.

[0229] Here, we will describe alternative drive configurations.

[0230] Figure 5F is a schematic diagram illustrating the structure and operation of the optical stack 104 with the SDVACRA900 in a narrow-angle state with an alternative driver configuration to that illustrated in Figure 4A, as illustrated in a top view. Features of the embodiment in Figure 5F that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0231] Compared with Figure 4A, the embodiment in Figure 5F illustrates an alternative drive configuration comprising ground reference drivers 950R, 950A, and 950C for electrodes 902R, 902A, and 902C, respectively. When in a narrow-angle state (e.g., when operating in privacy mode), it is desirable to have a uniform retardation in the lateral direction 195 across the liquid crystal 914, minimizing any angular diffusion of the on-axial rays 460 and minimizing diffraction from the liquid crystal 914. This is achieved by the voltage V on electrodes 902A1 and 902C. A and V C This can be achieved by setting the reference electrode 902R to the same potential. Electrode 902A2 is set to the same potential as 902A1 in this state. Voltage V A and V C This is generally an AC voltage, for example, a square wave. The voltage V across the reference electrode 902R. R It can be set to ground potential.

[0232] Alternatively, the voltage can be level-shifted with respect to the ground potential. Alternatively, the voltage V R This can be an AC voltage, and the voltage V A and V CThis can be adjusted accordingly. Advantageously, the voltage at electrodes 902C or 902R may have smaller deviations, resulting in less interference to adjacent touch panel functions.

[0233] It may be desirable to improve the operation of the display device 100 when it is operating in a narrow-angle state. As mentioned above, when it is operating in a narrow-angle state, V A ga V C If equal to , the region of liquid crystal 914 above electrode 902A1 and above the gap between electrodes 902A1 and 902A2 will experience a slightly different electric field due to the capacitance splitting effect of the dielectric layer 905 in series with the capacitance of the liquid crystal layer 914 in the gap between electrodes 902A1 and 902A2. Typically, the capacitance of the dielectric layer 905 is much larger than that of the liquid crystal layer 914, and therefore the potential V on electrode 902C is much larger. C Most of the voltage supplied into the gap by drops across the liquid crystal layer 914. However, the electric field E observed by the liquid crystal layer 914 above electrode 902A1 CAR And the electric field E above the gap between electrodes 902A1 and 902A2 CR To achieve an improvement in the agreement between and, potential V C This can be slightly increased (for example, by 100 mV in the narrow-angle state in the exemplary embodiment of Table 4A) to compensate for the capacitance splitting effect. This can be adjusted for the specific material relative dielectric constant and thickness of the dielectric layer 905, as well as the thickness and dielectric constant of layer 914 of the liquid crystal material 915.

[0234] The voltage may be configured as illustrated in Figure 5F, as an alternative to those illustrated in Figures 2A, 4A, and 6A.

[0235] When installed in a wide-angle configuration, the voltage V C The size is V to compensate for the volume division effect. A It can be adjusted similarly in comparison to the size, voltage V A , V CThis is in opposite phase. The change in voltage offset is adjusted according to the material parameters as described above.

[0236] Table 4A shows illustrative potentials for the operating modes. Alternative voltages are given for electrodes 902R, 902C, 902A1, and 902A2, for example, V A As illustrated in Table 4B when it is grounded, it can be selected when it is at a different potential. C The potential on electrode 902C is V A By adjusting the potential to be slightly greater than that of electrodes 902A1 and 902A2, the electric field E across the liquid crystal material 915 of layer 914 is achieved. 914 The uniformity in the lateral direction at 195° is improved. Residual diffraction is reduced, and advantageously, performance in narrow-angle conditions is further improved. [Table 6] Table 4A [Table 7] Table 4B

[0237] It may be desirable to provide the operation of the display device 100 when it is operating in an intermediate state.

[0238] Figure 6A is a schematic diagram illustrating the structure and operation of the optical stack 104 with SDVACRA900 in the intermediate state in a top view; Figure 6B is a schematic diagram illustrating the configuration 904 of the orientation structure 965 of electrodes 902A, 902C, 902R and liquid crystal material 915 for SDLCR901 in an intermediate state in a perspective front view; Figure 6C is a schematic diagram illustrating the configuration 904 of the orientation structure 965 of electrodes 902A, 902C, 902R and liquid crystal material 915 for SDLCR901 in an intermediate state in a top view; and Figure 6D is a schematic diagram illustrating the propagation through the layer 914 of SDVACRA900 arranged in the intermediate state for light rays along the field axis 445 and tilt axis 447 for two different positions x0, x1 across the region 103 of the layer 914 of liquid crystal material 915 in a top view. Features of the embodiments shown in Figures 6A-D, which are not discussed in further detail, can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0239] In the alternative embodiment shown in Figure 6A, compared to Figure 2A, the layer 914 of the liquid crystal material 915 is driven to provide a substantially uniform, vertically oriented structure 965 of the liquid crystal material 915.

[0240] The alternative embodiments shown in Figures 6A-D illustrate that the transparent electrode configuration 904 is patterned to be driven to an intermediate state having an orientation structure 965 that selectively causes the layer 914 of the liquid crystal material 915 to introduce a net phase shift η, which is uniform across the region 103 of the layer 914 of the liquid crystal material 915, into the light having a predetermined polarization state 909, thereby preventing the layer 914 of the liquid crystal material 915 from providing a diffraction effect to the light having a predetermined polarization state 909, and also causing the SDVACRA 900 to introduce the same net relative phase shifts η(φ445) and η(φ447) along the field axis 445 and the tilt axis 447 into the orthogonal polarization components of the light having a predetermined polarization state.

[0241] Compared to Figures 2A-C, a lower level of diffraction is provided, and therefore the brightness of the on-axis ray 460 is increased. Compared to Figures 4A-C, material 915 has a vertically oriented structure 965. Such an increase provides a reduction in depolarization, as illustrated by ray 447 in Figure 5D, and provides higher brightness in the off-axis direction, as illustrated in Figure 6D. Advantageously, light loss is reduced and higher efficiency is achieved.

[0242] Here, we will further explain the operation of the passive compensation retarder 930.

[0243] Figure 6E is a schematic diagram illustrating, in an oblique side view, the propagation of a first linearly polarized state through a layer comprising vertically aligned liquid crystal molecules and a passive compensating retarder. Features of the embodiment of Figure 6E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0244] In comparison with Figure 5D, the alternative embodiment in Figure 6E illustrates that the molecule 925 is oriented vertically, providing a non-zero phase difference η(447). A passive compensating retarder 930 may be provided by a negative C-plate between an additional polarizer 918 and the display polarizer 910. Such a negative C-plate provides a negative phase difference η'(447) to components 997(447), 999(447) that compensate for a positive phase difference η(447), such that the resulting net relative phase shift is minimized and the output polarization state from SDVACRA900 (equipped with SDLCR901 and passive compensating retarder 930) is substantially aligned with the electrical vector transmission direction 911 of the display polarizer 910. Advantageously, high transmission is provided.

[0245] Figure 6F is a schematic diagram illustrating the structure and operation of an alternative optical stack 104 with SDVACRA900 in an intermediate state, shown in a top view. Features of the embodiment in Figure 6F that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0246] In the alternative embodiment shown in Figure 6F, compared to Figure 5A, the output of the light cone angle 461 is maintained to be the same as that provided by the backlight 20. Advantageously, the viewing degrees of freedom of the display are increased. Off-axis viewers 447 see the light from the display device 100 with improved image visibility compared to the narrow-angle state.

[0247] The intermediate state achieves increased brightness along the field of view axis 445 compared to the wide-angle state because light is not diffracted at higher viewing angles. The intermediate state also achieves increased image visibility to the user along the tilt axis 447. Power consumption can be reduced to provide the intermediate state. The operational efficiency of the display device 100 for the image supplied to the user 45 along the field of view axis 445 is determined by the transmission of layers such as electrode layers, polarizers, and other light-absorbing layers.

[0248] Now, let's explain the electric drive scheme.

[0249] Figure 7A is a schematic graph illustrating the drive waveform of the SDLCR901 of the optical stack 104 in Figure 2A in the wide-angle state; Figure 7B is a schematic graph illustrating an alternative drive waveform of the SDLCR901 of the optical stack 104 in Figure 4A in the narrow-angle state; and Figure 7C is a schematic graph illustrating the drive waveform of the SDLCR901 of the optical stack 104 in Figure 6A in the intermediate state. Features of the embodiments in Figures 7A-C that are not discussed in further detail can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0250] The control system 500 is configured to control which of the waveforms shown in Figures 7A-C is provided to the voltage driver 950 to provide wide-angle, privacy mode, or intermediate state operation. The alternating profiles provide DC balancing and achieve increased device lifespan. Non-square voltage profiles may be provided to achieve the desired addressing level for layer 914 of the liquid crystal material 915.

[0251] Here, we will explain the polarity variations of luminance and transmission in an illustrative manner.

[0252] Figure 8A is a schematic graph illustrating the extreme variation in luminance output for the illustrative backlight 20 in Figure 1A. Features of the embodiment in Figure 8A that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0253] In this disclosure, polar angles are described using coordinate rules that have coordinate elevation angles and coordinate lateral angles. In alternative coordinate rules, polar angles may have coordinate polar angles (different from the polar angles referred to herein), which are the angle of inclination from the normal direction to a plane, and coordinate azimuth angles, which are the angle of rotation in the plane from a reference direction in the plane. In this embodiment, the normal polar angle for an on-axis viewer 45 is marked by the polar angle location of axis 445, and the normal polar angle for an exemplary off-axis viewer 47 with zero elevation is marked by the polar angle location of axis 447.

[0254] The backlight 20 provides brightness at polar angles with respect to the normal 199 of SLM48 greater than 45 degrees, where the brightness along the normal 199 of SLM48 is up to 30%, preferably up to 20%, and most preferably up to 10%. In the illustrative example of Figure 8A, less than 2.5% of the peak brightness is provided to the tilt axis 447.

[0255] Here, we will explain an example of operation in a narrow-angle state.

[0256] Figure 8B is a schematic graph illustrating the extreme variation in transmittance of the exemplary SDVACRA900 in Figure 1A and Table 2 operating in a narrow-angle state; Figure 8C is a schematic graph illustrating the extreme variation in brightness output of the display in Figure 1A with the exemplary backlight 20 in Figure 8A, and the extreme variation in SDVACRA900 in Figure 8B in a narrow-angle state; Figure 8D is a schematic graph illustrating the extreme variation in reflectance of the exemplary SDVACRA900 in Figure 1A and Table 2 operating in a narrow-angle state; and Figure 8E is a schematic graph illustrating the extreme variation in security coefficient S for the exemplary backlight 20 in Figure 8A, and SDVACRA900 in Table 2, Figure 8B and Figure 8D operating in a narrow-angle state. Features of embodiments in Figures 8B-E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0257] Figure 8D illustrates, for example, the absence of a reflective polarizer 302, as described in Figure 16A below, and therefore the reflectance represents the frontal reflection of the display device 100.

[0258] Here, we will explain the operation in an example setting at wide angle.

[0259] Figure 8F is a schematic graph illustrating the extreme variation in transmittance for the illustrative SDVACRA900 in Figure 1A and Table 2 operating in the wide-angle state, and Figure 8G is a schematic graph illustrating the extreme variation in luminance output of the display device 100 in Figure 1A, which includes the illustrative backlight 20 in Figure 8A and the SDVACRA900 in Figure 8F, in the wide-angle state. Advantageously, the luminance with respect to the viewing tilt axis 447 increases to approximately 10%, providing substantially increased image visibility to the off-axis display user 47 when the display device 100 is positioned in the wide-angle state.

[0260] In some cases, it is desirable to reduce the transmission of SDVACRA900 at a viewing angle φ (447) close to axis 445.

[0261] Figure 9A is a schematic diagram illustrating the electrode and liquid crystal material structure of SDLCR901, which has two parallel homogeneous surface alignment layers in non-driving mode, in a perspective front view; Figure 9B is a schematic diagram illustrating an alternative homogeneous liquid crystal alignment 965 of SDLCR901 in Figure 9F, arranged in a wide-angle state, in a top view; Figure 9C is a schematic graph illustrating the diffraction brightness profile 430 to diffraction order for the embodiment of Figure 9B; Figure 9D is a schematic graph illustrating the variation of normalized intensity with respect to angle for each of seven different driving voltages for the configuration of Figure 9B; and Figure 9E illustrates the configuration of Figure 9B Figure 9F is a schematic diagram illustrating the variation in the total transmittance for each of the seven different drive voltages; Figure 9E is a schematic diagram illustrating in a top view an alternative homogeneous liquid crystal alignment 965 for use in the embodiment of Figure 1A, having the electrode configuration of Figure 1E and arranged in a narrow-angle state; Figure 9G is a schematic diagram illustrating the polar variation in transmittance for the illustrative SDLCR901 of Figure 9A and Tables 5-6 operating in a narrow-angle state; and Figure 9H is a schematic diagram illustrating in a top view an alternative homogeneous liquid crystal alignment 965 for the SDLCR901 of Figure 9F arranged in an intermediate state. Features of embodiments of Figures 9A-H that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features. [Table 8] Table 5 [Table 9] Table 6

[0262] Compared to Figures 2C-D, 4C, and 6C, the alternative embodiments in Figures 9B-C, 9F, and 9H each illustrate a configuration in which both sides of the SDLCR 901 have homogeneous surface alignment layers and one side of the layer 914 of the liquid crystal material 915 has a patterned electrode 902. The passive compensating retarder 930 is further provided by a pair of A-plate retarders 930A, 930B having their respective intersecting optical axes, as illustrated in Table 5. Some asymmetry of the luminance profile can be achieved over the lateral direction. A display, such as a passenger infotainment display, can be advantageously provided to the driver 47 on one side of the passenger 45 with an improved security factor in the narrow-angle state, for example, as illustrated in Figures 31A-B below. In the alternative embodiment, the pair of A-plate passive compensating retarders 930A, 930B can be provided by a C-plate. Advantageously, thickness and cost can be reduced.

[0263] Furthermore, compared to the embodiment in Figure 8B, as illustrated in Figure 9G, the minimum brightness can be achieved at an angle φ(447) close to the field of view axis 445. Advantageously, an increased security factor S can be provided at this smaller angle φ(447). A display device 100 suitable for use in a vehicle may be provided with an increased security factor at the driver's tilt axis 447.

[0264] Here, Table 7 describes alternative configurations for the liquid crystal layer 914 of the SDLCR901 and the liquid crystal layer 314 of the switchable non-diffractive liquid crystal retarder (SNDLCR)301.

[0265] In this specification, retardance refers to the retardance of layers 914, 314 of the liquid crystal material 915, 315 to light with a wavelength of 550 nm. The retardance ranges in Table 7 illustrate appropriate parameters for achieving the desired angle φ of minimum transmission in a narrow-angle state with respect to the tilt axis 447. Higher retardance may achieve smaller angles φ but may provide higher transmission at angles greater than φ, while providing further reduction in transmission. Alternatively, lower retardance may reduce transmission at higher tilt angles φ but may provide insufficient suppression at smaller tilt angles φ. [Table 10] Table 7

[0266] In the SDLCR901 of this embodiment, each of the surface alignment layers 917A and 917B may be arranged to provide homogeneous alignment of adjacent liquid crystal materials 915, and the layer 914 of the liquid crystal material 915 of the SDLCR901 may have a retardation in the range of 500 nm to 900 nm for light with a wavelength of 550 nm. The SDLCR901 further comprises either a passive single-axis retarder which is a compensating retarder 930 having an optical axis 931 perpendicular to the plane of the retarder 930 and a retardation in the range of -300 nm to -700 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders 930A and 930B having optical axes 931A and 931B in the plane of intersecting retarders 930A and 930B, each having a retardation in the range of 300 nm to 800 nm for light with a wavelength of 550 nm. Alternatively, one of the surface alignment layers 917A and 917B may be arranged to provide homogeneous alignment of adjacent liquid crystal material 915, and the other of the surface alignment layers 917A and 917B may be arranged to provide homogeneous alignment of adjacent liquid crystal material 915, and layer 914 of the liquid crystal material 915 of SDLCR901 has retardance in the range of 700nm to 2000nm for light with a wavelength of 550nm, and SDLCR901 is retarder The system further comprises either a passive single-axis retarder, which is a compensating retarder 930 having an optical axis 931 perpendicular to the plane and having a retardation in the range of -300 nm to -1800 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders 930A and 930B, each having optical axes 931A and 931B in the plane of intersecting retarders 930A and 930B, and each having a retardation in the range of 300 nm to 1800 nm for light with a wavelength of 550 nm.Alternatively, each of the surface alignment layers 917A and 917B may be arranged to provide homeotropic alignment of the adjacent liquid crystal material 915, and the layer 914 of the liquid crystal material 915 of SDLCR901 has a retardance in the range of 500 nm to 1000 nm for light with a wavelength of 550 nm, and SDLCR901 further comprises either a passive single-axis retarder which is a compensating retarder 930 having an optical axis 931 perpendicular to the plane of the retarder and a retardance in the range of -300 nm to -900 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders 930A and 930B having optical axes 931A and 931B in the plane of intersecting retarders and each having a retardance in the range of 300 nm to 800 nm for light with a wavelength of 550 nm.

[0267] SNDLCR301 includes, but is not limited to, Figures 18B, 18E, 18F, and 20A-B, which are further described below. In the SNDLCR301 of this embodiment, each of the surface alignment layers 317A and 317B may be arranged to provide homogeneous alignment of adjacent liquid crystal materials 315, and the layer 314 of the liquid crystal material 315 of the SNDLCR301 has a retardance in the range of 500 nm to 900 nm for light with a wavelength of 550 nm. The SNDLCR301 further comprises either a passive single-axis retarder which is a compensating retarder 330 having an optical axis 331 perpendicular to the plane of the retarder 330 and a retardance in the range of -300 nm to -700 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders 330A and 330B having optical axes 331A and 331B in the plane of intersecting retarders 330A and 330B, each having a retardance in the range of 300 nm to 800 nm for light with a wavelength of 550 nm. Alternatively, one of the surface alignment layers 317A and 317B may be arranged to provide homogeneous alignment of adjacent liquid crystal materials 315, the other of the surface alignment layers 317A and 317B may be arranged to provide homogeneous alignment of adjacent liquid crystal materials 315, the layer 314 of the liquid crystal material 315 of SNDLCR301 has a retardation in the range of 700 nm to 2000 nm for light with a wavelength of 550 nm, and SNDLCR301 is The system further comprises either a passive single-axis retarder, which is a compensating retarder 330 having an optical axis 331 perpendicular to the plane of the retarder and having a retardation in the range of -300 nm to -1800 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders 330A and 330B, each having optical axes 331A and 331B in the plane of intersecting retarders 330A and 330B, and each having a retardation in the range of 300 nm to 1800 nm for light with a wavelength of 550 nm.Alternatively, each of the surface alignment layers 317A and 317B may be arranged to provide homeotropic alignment of adjacent liquid crystal material 315, and the layer 314 of the liquid crystal material 315 of SNDLCR301 has a retardance in the range of 500 nm to 1000 nm for light with a wavelength of 550 nm, and SNDLCR301 further comprises either a passive single-axis retarder which is a compensating retarder 330 having an optical axis 331 perpendicular to the plane of the retarder and having a retardance in the range of -300 nm to -900 nm for light with a wavelength of 550 nm, or a pair of passive single-axis retarders 330A and 330B having optical axes 331A and 331B in the plane of intersecting retarders and each having a retardance in the range of 300 nm to 800 nm for light with a wavelength of 550 nm.

[0268] Further configurations of the layer 914 of the liquid crystal material 915 for SDLCR901 and optionally a passive compensating retarder 930, as well as SNDLCRA300 comprising SNDLCRA301 and optionally a passive compensating retarder 330, are described in U.S. Patent No. 11,092,851, U.S. Patent No. 10,976,578, and U.S. Patent Application Publication No. 2023-0254457, all of which are incorporated herein by reference in their entirety. Such configurations are suitable for providing a switch between desired narrow-angle operation and wide-angle operation, as described herein.

[0269] In some cases, it is desirable to provide a narrow-angle view for the field axis 445, which is not close to the optical axis 199.

[0270] Figure 10A is a schematic diagram illustrating an SDLCR901 in a non-driven mode, in a perspective front view, comprising an electrode configuration 904, a pair of orthogonally aligned homogeneous surface alignment layers 917A and 917B, and an alignment structure 965 of the liquid crystal material 915; Figure 10B is a schematic graph illustrating the transmission polarity variation of the illustrative SDVACRA900 in Figure 10A and Table 8 operating in a narrow-angle state; and Figure 10C is an alternative homogeneous configuration of SDLCR901, having the configuration of Figure 10A and arranged in a narrow-angle state. Figure 10D is a schematic diagram illustrating a near-liquid crystal alignment structure 965 in a top view, a schematic diagram illustrating an alternative homogeneous liquid crystal alignment structure 965 for SDLCR901 in a top view, having the configuration of Figure 10A and arranged in a wide-angle state, Figure 10E is a schematic graph illustrating the normalized intensity variation with respect to angle for each of seven different drive voltages for the configuration of Figure 10D, and Figure 10F is a schematic graph illustrating the total transmission intensity variation for each of seven different drive voltages for the configuration of Figure 10D. Features of embodiments of Figures 10A-F that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0271] Compared to Figure 9A, the alternative embodiment in Figure 10A shows the thickness direction through layer 914 of the liquid crystal material 915.

number

[0272] Compared to the embodiments in Figures 8B and 9G, the location of the field of view axis 445 may be conveniently provided in a direction different from the normal of the display device 100. Also, the location of the tilt axis 447 may be a reduced angle φ(447) to achieve improved driver distraction in the operation of the passenger infotainment display in a narrow-angle state.

[0273] An SDLCR901 comprising a twisted layer of liquid crystal material 915, as illustrated in Table 8 and Figures 10A-B, may be further driven by a voltage across layer 914 of liquid crystal material 915 that varies across region 103 of layer 914. Such variation may be provided across region 103 of the corresponding electrode configuration 904. For example, at least one electrode 902A, 902C, 902R may be provided with a voltage that varies in the lateral direction 195. Such a varying voltage can achieve improved uniformity of brightness to the observer 45 along a given field of view axis 445 from the entire region 103 of the display device 100, and improved uniformity of the security coefficient along the tilt axis 447. Such a varying voltage is described in U.S. Patent Application Publication No. 2023-0254457, which is incorporated herein by reference in its entirety.

[0274] The SDLCR901, comprising a twisted layer of liquid crystal material 915 as illustrated in Table 8 and Figures 10A-B, may be further driven by a voltage across the layer 914 of the liquid crystal material 915 that varies depending on the measured location of a moving observer 45 and / or observer 47. For example, at least one electrode 902A, 902C, 902R may be provided with a voltage that varies depending on the observer's location. Such a varying voltage can achieve improved uniformity of brightness for a moving observer 45 of the display device 100, and improved uniformity of the security factor for a moving observer 47 who is a peeping tom or driver. Such a voltage that varies depending on the observer's location is described in U.S. Patent Application Publication 2023-0375863, which is incorporated herein by reference in its entirety.

[0275] In some cases, it is desirable to reduce the complexity of the electrode configuration 904.

[0276] Figure 11A is a schematic diagram illustrating an alternative transparent electrode configuration 904 for the SDLCR901 of Figure 1A, in which the control electrode 902C is omitted, in a perspective side view, and Figure 11B is a schematic diagram illustrating the electrode configuration 904 of Figure 11A and the alignment structure 965 of the liquid crystal material 915 in a perspective front view for the SDLCR901, which includes a surface alignment layer 917A that provides homogeneous alignment of the liquid crystal material 915 and a surface alignment layer 917B that provides homeotropic alignment of the liquid crystal material 915 in a narrow-angle state. Figure 11C is a schematic diagram illustrating the electrode configuration 904 and alignment structure 965 of the liquid crystal material 915 in Figure 11A, for SDLCR901, which includes a surface alignment layer 917A that provides homogeneous alignment of the liquid crystal material 915 and a surface alignment layer 917B that provides homeotropic alignment of the liquid crystal material 915 in a wide-angle state, in a perspective front view; Figure 11D is a schematic diagram illustrating the structure of SDLCR901 in Figures 11A-C in a top view, in a wide-angle state; and Figure 11E shows the liquid crystal material 915 Figure 11A is a schematic diagram illustrating the alignment structure 965 of the electrode configuration 904 and liquid crystal material 915 of SDLCR901, which has two surface alignment layers 917A and 917B that provide homogeneous alignment, in a perspective front view; Figure 11F is a schematic diagram illustrating an alternative liquid crystal alignment structure 965 of SDLCR901 having the configuration of Figure 11B in a narrow-angle state, in a top view; and Figure 11G is an alternative homogeneous liquid crystal alignment structure 965 of SDLCR901 having the configuration of Figures 11B-C in a wide-angle state. Figure 11H is a schematic diagram illustrating the top view of 5, a schematic graph illustrating the normalized intensity variation with respect to angle for each of the seven different drive voltages for the configuration of Figure 11G, a schematic graph illustrating the total transmission intensity variation for each of the seven different drive voltages for the configuration of Figure 11G, a schematic diagram illustrating the top view of an alternative homogeneous liquid crystal alignment structure 965 for SDLCR901 having the configuration of Figure 11E in the narrow-angle state, and Figure 11K is in the wide-angle state.Figure 11E is a schematic diagram illustrating an alternative homogeneous liquid crystal alignment structure 965 for SDLCR901 in a top view; Figure 11L is a schematic graph illustrating the normalized intensity variation with respect to angle for each of seven different drive voltages for the configuration of Figure 11K; and Figure 11M is a schematic graph illustrating the summation transmission intensity variation for each of seven different drive voltages for the configuration of Figure 11K. Features of embodiments of Figures 11A-M, which are not discussed in further detail, can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0277] Compared to the embodiment of the transparent electrode configuration 904 comprising the control electrode 902C described herein, in the alternative embodiment shown in Figures 11A-M, the separation electrodes 902A and 902B are close enough to allow the layer 914 of the liquid crystal material 915 to be driven to a narrow angle state by applying a common voltage.

[0278] In the alternative embodiment of Figure 11A compared to Figure 1E, the patterned electrode 902 comprises interlocked electrodes 902A, 902B separated by a gap 932 across region 103, each having busbars 903A, 903B outside region 103.

[0279] In the narrow-angle state and the intermediate state, V A and V B V RSet to the same potential with respect to the potential of the reference electrode 902R, control of the layer 914 of the liquid crystal material 915 is provided by the relative voltage with respect to the potential of the reference electrode 902R. The electrode spacing of 902A and 902B is small or similar to the spacing between electrodes 902A and 902R so that the electric field across the layer 914 arising from the separating electrodes 902A and 902B can substantially control the liquid crystal material 915 in the spacing between the respective separating electrodes 902A and 902B. As illustrated in Figure 11F, the gap 932 of width γ is small enough to provide a sufficient electric field for electrodes 902A and 902B of width ω to switch the layer 914 of the liquid crystal material 915 in a substantially uniform manner across the region 103. In other words, the gap 932 has a width γ small enough to achieve substantially uniform switching of the layer 914 of the liquid crystal material 915 such that substantially no diffraction is provided by the layer 914 of the liquid crystal material 915.

[0280] In comparison, in the wide-angle state, as illustrated in Figures 11C and 11E, V A and V B They are typically set to opposite potentials or opposite phases, and to different potentials relative to each other, and the electric field E AB , E BA Provides a diffraction structure 965, as illustrated elsewhere in this specification. R It can be set to a potential that can be grounded.

[0281] The transparent electrode configuration 904 in Figure 1E includes a capacitive dielectric layer 905 between electrodes 902C and 902R. In comparison, Figure 11A does not include the dielectric layer 905, and advantageously achieves reduced power consumption due to the reduction of the capacitive load of the SDLCR 901. Further complexity and cost of manufacturing the electrode configuration 904 are reduced.

[0282] The ends of electrodes 902A and 902B of the "finger portion" can be joined together to reduce the voltage drop along the length of electrodes 902B and 902A, as described elsewhere in this specification.

[0283] Here, we will describe an alternative electrode configuration 904 for use in SDLCR901.

[0284] Figure 12 is a schematic diagram illustrating an alternative permeable electrode configuration 904, comprising mutually mated electrodes 902A and 902B, in a perspective side view. Features of the embodiment in Figure 12 that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0285] In the alternative embodiment shown in Figure 12, compared to Figure 1E, the array of isolation electrodes 902 comprises two inter-mating sets of isolation electrodes 902A and 902B. Each set of isolation electrodes 902A and 902B comprises their respective common busbars 903A and 903B, disposed outside the region 103 which may be the active region of the SLM48. Electrodes 902A and 902B may be formed by etching a single layer of transparent conductor. Alternatively, the electrodes may be formed by etching two transparent conductors separated by an insulator (not shown). In this case, as described in Figure 1F, each of electrodes 902A and 902B may be formed with a busbar 903A at each end to reduce electrode impedance.

[0286] An alternative embodiment in Figure 12 includes a permeable reference electrode 902R, which can be embodied, for example, by ITO or silver nanowires. Figure 12 shows voltage V, which is the voltage applied to the common busbars 903A and 903B, respectively, with respect to the potential of the control electrode 902C. AC and V BC Let's illustrate this with an example. Potential V AC and V BC The potentials can be equal to each other to provide a symmetric diffraction effect. Alternatively, the potential V AC and V BC These can differ in order to provide an asymmetric diffraction effect. 。

[0287] The reference electrode 902R, when driven, may provide an electric field perpendicular to the cell plane that can increase or substantially neutralize the effects of the surface alignment layers 917A, 917B (not shown). When the homogeneous surface alignment layer is used on either side of layer 914 as illustrated in Figure 9B, the electric field can at least partially neutralize the alignment of the liquid crystal material 915 on both sides of layer 914.

[0288] In wide-angle conditions, it may be desirable to modify the structure 965 of the liquid crystal material 915.

[0289] Figure 13 is a schematic diagram illustrating an alternative electrode configuration 904 in a perspective side view, comprising spaced-out transparent electrodes 902AA, 902AB arranged on both sides of a layer 914 of liquid crystal material 915. Features of the embodiment in Figure 13 that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0290] Compared with the SDLCR901 in Figure 1A, the alternative embodiment in Figure 13 includes an electrode configuration 904 comprising a separation electrode 902AA between the control electrode 902C and the layer 914 of the liquid crystal material 915, and a separation electrode 902AB between the reference electrode 902R and the layer 914 of the liquid crystal material 915.

[0291] During operation, the embodiment in Figure 13, compared to the embodiment in Figure 2C, for example, shows the thickness direction of the structure 965 of the liquid crystal material 915.

number

[0292] In wide-angle conditions, it may be desirable to modify the structure 965 of the liquid crystal material 915.

[0293] Figure 14A is a schematic diagram illustrating an alternative electrode configuration 904 in a perspective side view, comprising spaced-apart, inter-mating transparent electrodes 902AA, 902BA and inter-mating transparent electrodes 902AB, 902BB arranged on both sides of a layer 914 of liquid crystal material 915, and Figure 14B is a schematic diagram illustrating a drive configuration of SDLCR901 comprising the electrode configuration 904 of Figure 14A in a top view. Features of embodiments of Figures 14A-B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0294] In an alternative embodiment of Figure 14A, at least one array of separation electrodes 902 comprises two arrays of separation electrodes 902AA, 902BA and 902AB, 902BB on either side of the SDLCR901, each comprising two inter-mated separation electrode sets.

[0295] Compared with the SDLCR901 in Figure 1A, the alternative embodiment in Figure 14A comprises an electrode configuration 904 having mutually mated separation electrodes 902AA, 902BA between a control electrode 902CA and a layer 914 of liquid crystal material 915, and separation electrodes 902AB, 902BB between a further control electrode 902CB (which may alternatively be referred to as a reference electrode 902R) and a layer 914 of liquid crystal material 915.

[0296] During operation, the embodiment in Figure 14A, compared to the embodiment in Figure 2C, for example, shows the thickness direction of the structure 965 of the liquid crystal material 915.

number

[0297] The additional control electrode 902C provides a mode in which a uniform electric field perpendicular to the plane of the liquid crystal material 915 layer 914 can be provided. In this case, the potential V AA , V BA and V CA It can be set to zero volts. In further modes, V CB It can also be set to zero. In these modes, the structure may behave like a polarity-controlled retarder, i.e., a retarder that provides transmission that varies with the pole angle, as described elsewhere in this specification, for example in Figure 6E. In another mode, V AA and V BA When the potentials are set to the same level, V CA Different potentials, typically V AA When set to the opposite or opposite phase, an electric field pattern is generated in the liquid crystal layer 914 that produces a periodic phase pattern. This can be implemented by using three ground reference voltages applied to electrodes 902BA, 902AA, and 902C. The same effect can be achieved with V AB , V BB , and V CB By using three ground reference voltages applied to the liquid crystal layer 914, a periodic phase pattern can be generated on the upper or lower part of the liquid crystal layer 914, or on both sides. Increased control of the orientation structure 965 of the liquid crystal material 915 can be provided. Increased diffusion into the light cone 465 can be achieved, and advantageously, increased visibility along the tilt axis 447 can be achieved.

[0298] This structure also V BA ga V CA V is set to a different voltage, such as a negative (anti-phase) waveform. CA and V BA It can be operated in this manner. Different distributions of diffraction orders can be generated. Advantageously, the visibility of the wide-angle state at the tilt axis 447 can be adjusted by the control system 500.

[0299] In the alternative embodiment shown in Figure 14B, the voltage V AA , V BA and V CAThey can be set to be equal to each other. Similarly, V AB , V BB and V CB These can be set to be equal to each other. The effective voltage between the separation electrodes 902CA and 902CB, i.e., V CB -V CA However, it provides a transmission profile as described elsewhere in this specification.

[0300] In a further embodiment, AC potential V BA and V AA These can be configured to generate potentials opposite to each other, thereby generating a periodic phase pattern in the liquid crystal layer 914. Such a phase structure can diffract and therefore diffuse incident light. The isolation electrodes 902AA, 902BA and isolation electrodes 902AB, 902BB can be aligned with respect to the plane of the cell perpendicular to each other, V BB and V AB V BA and V AA It may have a voltage corresponding to the voltage applied to it, in which case the diffraction diffusion effect may increase.

[0301] In a further embodiment, the voltage V AA and V BA , and voltage V AB and V BB These can be set to be equal to each other in order to provide the same operation as illustrated in Figure 11A.

[0302] The separation electrodes 902AA, 902BA and 902AB, 902BB can be offset from each other, as shown in detail in Figures 16C to D below.

[0303] In some cases, it is desirable to provide asymmetric diffraction in the wide-angle state.

[0304] Figure 15A is a schematic diagram illustrating the structure and operation of an SDLCR with an alternative electrode configuration to that of Figure 14A in a top view, where the isolation electrodes 902AA, 902BA and 902AB, 902BB on both sides of the liquid crystal material 915 layer 914 are offset by a distance δ in the lateral direction 195. Figure 15B is a schematic diagram illustrating the liquid crystal alignment 965 of an SDLCR901 with the electrode configuration 904 of Figure 15A in a top view in a narrow-angle state. Figure 15C is a schematic diagram illustrating the liquid crystal alignment 965 of an SDLCR901 with the electrode configuration 904 of Figure 15A and Tables 9-10 in a wide-angle state in a top view. Figure 15D is a schematic diagram illustrating the diffraction brightness profile 430 to the diffraction order for the embodiment of Figure 15C. Features of the embodiments shown in Figures 15A-D, which are not discussed in further detail, can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features. [Table 12] Table 9 [Table 13] Table 10

[0305] In comparison with Figure 14B, the alternative embodiment in Figure 15A illustrates the provision of an electric field line 907 in which the offset δ is tilted through the thickness of the layer 914 of the liquid crystal material 915 and can provide an asymmetric structure 965 of the orientation of the liquid crystal material 915.

[0306] Such a configuration may provide an asymmetric diffraction pattern, which can be controlled by appropriate driving of the respective mated electrodes 902AA, 902BA, 902AB, and 902BB. Such an asymmetric diffraction pattern may provide a wide-angle mode with increased brightness biased to one side of the display device 100. Such a configuration may be used in a passenger infotainment display device 100, as illustrated in Figures 31A-B below, to provide increased brightness to the driver 47.

[0307] Figure 15B illustrates how uniform alignment can be achieved across a region 103 of layer 914 of the liquid crystal material 915, providing an intermediate state without applied voltage due to homeotropic alignment. In the narrow-angle state, voltage V CA-CB A voltage is applied to provide some out-of-plane alignment of the structure 965. Alternatively, the control electrodes 902CA, 902CB may be omitted, and the isolation electrodes 902AA, 902BA may be close enough to drive the layer 914 of the liquid crystal material 915 into a narrow-angle state by applying a common voltage. Advantageously, power consumption, cost, and complexity may be reduced.

[0308] Figure 15C illustrates an asymmetric wide-angle state of the orientation structure 965 of the liquid crystal material 915, which achieves the asymmetric diffraction profile 430 of Figure 15D and can be adjusted by adjusting the driving voltage.

[0309] Here, we will describe a further configuration of the display device 100 equipped with SDVACRA900. In narrow-angle conditions, it may be desirable to increase the security factor of the display device 100.

[0310] Figure 16A is a schematic diagram illustrating a switchable display device 100 in a perspective side view, comprising a backlight 20, an SLM 48, a reflective polarizer 302, an SDVACRA 900, and an additional polarizer 918. Features of the embodiment of Figure 16A that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0311] In the alternative embodiment of Figure 16A, compared to Figure 1A, the display polarizer 910 is an output display polarizer 218 located on the output side of the SLM48. The SDVACRA900 and the additional polarizer 918 in Figure 16A are arranged to receive light from the SLM48. The embodiment of Figure 16A further comprises a reflective polarizer 302 located between the output polarizer 218 and the SDVACRA900, the reflective polarizer 302 being a linear polarizer having an electrical vector transmission direction 303 arranged to allow the same linearly polarized polarization state as the output polarizer 218 to pass through. The reflective polarizer 302 may be omitted as an alternative.

[0312] The operation of the configuration in Figure 16A in the narrow-angle state is further illustrated in Figures 39A and 39B below. Advantageously, an increase in the security factor can be achieved along the tilt axis 447.

[0313] In the wide-angle state, light from the backlight 20 and SLM 48 is diffused by the SDVACRA 900 to improve visibility to the tilt axis 447, achieving high transmittance, for example, as illustrated in Figure 40A. The thicknesses of the substrates 216, 912 and polarizers 218, 302 can be minimized to achieve reduced visibility of the blur of the pixels 220. In the wide-angle state, off-axis reflectance can be reduced, as illustrated in Figure 40B.

[0314] It may be desirable to provide a display device 100 equipped with a light-emitting SLM48.

[0315] Figure 16B is a schematic diagram illustrating a switchable display device 100 in a perspective side view, comprising a light-emitting SLM 48, an aperture array 750, a display polarizer 910, a reflective polarizer 302, an SDVACRA 900, and an additional polarizer 918. Features of the embodiment of Figure 16B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0316] In an alternative embodiment of Figure 16B, the SLM48 comprises a light-emitting SLM48. The light-emitting SLM48 comprises an array of red, green, and blue pixels 220R, 220G, and 220B arranged within a pixel layer 14 on a backplane substrate 12. The pixels are arranged to emit light 400 along the output direction. Pixels 220R, 220G, and 220B comprise light-emitting diodes, which are organic light-emitting diodes comprising an organic light-emitting material 32. The region 26 between pixels 220R, 220G, and 220B comprises control electronics and is typically reflective to the organic light-emitting diode (OLED) pixel layer 214. Alternatively, pixels 220R, 220G, and 220B may comprise inorganic micro-LEDs, or a combination of OLEDs and inorganic micro-LEDs.

[0317] The parallax barrier 21 comprises an array of apertures 22 having light-absorbing regions 24 between them. The parallax barrier 21 is a two-dimensional array of apertures 22, with each pixel 220R, 220G, 220B being aligned with its respective aperture. The parallax barrier 21 is disposed on a spacer layer 26 that provides separation from the pixel layer 14 with a parallax distance d along an axis 199 along the plane normal to the pixel layer 14. The operation of the SLM 48 in Figure 16B is further described in U.S. Patent No. 11,573,437, which is incorporated herein by reference in its entirety.

[0318] Output display polarizers 218, 910 are positioned on the output of the SLM 48, and output polarizer 218 is a linear polarizer having an electrical vector transmission direction 219. A reflection-controlled quarter-wavelength retarder 228 having an optical axis direction 29 is positioned between the output polarizer 218 and the SLM 48. The retarder 28 may be provided by a stretched birefringent film such as polycarbonate. Advantageously, a low-cost retarder 28 may be provided, and the visibility of reflections from region 26 may be reduced.

[0319] The parallax barrier 21 is disposed between the pixel layer 214 and the reflection-controlled quarter-wavelength retarder 28. In other embodiments (not shown), the quarter-wavelength retarder 228 may be provided by a layer formed between the pixel layer 214 and the parallax barrier 21. Such a retarder 28 may comprise, for example, a cured reactive mesogenic liquid crystal layer. Advantageously, the retarder may be provided with a thickness equal to or less than the desired thickness d, as will be further described below.

[0320] In light-emitting displays, high brightness is typically provided at high extreme angles. Typical light-emitting displays, such as OLED displays, can provide brightness exceeding 25% of the frontal brightness at an extreme angle of, for example, 60 degrees. MicroLED displays with inorganic LEDs can have virtually Lambertian brightness output, so the brightness at 60 degrees can approach 100% of the frontal brightness.

[0321] The switchable display device 100 is desirable to have high visual safety in the narrow-angle state at extreme angles exceeding 45 degrees and high image visibility in the wide-angle state at extreme angles exceeding 45 degrees. Preferably, the luminance along the tilt axis 447 may be at least 2.5%, preferably at least 5%, of the luminance along the field axis 445 for high image visibility under typical ambient lighting conditions. The luminance along the tilt axis 447 may be less than 1%, preferably less than 0.5%, of the luminance along the field axis 445 for high image security under typical ambient lighting conditions.

[0322] The parallax barrier 21 may be configured to provide an output luminance profile having a peak luminance along the field axis 445 and a reduction in luminance with respect to the off-axis direction 447. In the narrow-angle state, the security factor 447 in the off-axis direction may be increased. In the wide-angle state, the visibility of the image on pixels 220R, 220G, and 220B of the SLM 48 is increased from viewing along the tilt axis 447. Advantageously, an improvement in the wide-angle state may be achieved.

[0323] In the embodiments shown in Figures 16A-B, one or both of the transparent substrates 216 (if present) and 912 may be thin substrates such as thin glass. Further polarizers 218, 302 and their respective adhesive layers may be arranged with small thicknesses. Separation between layer 914 and layer 214 can be reduced. Advantageously, blurring of pixels 220 from light dispersion in the lateral direction 195 in the wide-angle state can be reduced.

[0324] Figure 16C is a schematic graph illustrating the polar variation of reflectivity for the exemplary SDVACRA900 in Figure 16A and Table 2 operating in a narrow-angle state, and Figure 16D is a schematic graph illustrating the profile of the security coefficient S for the exemplary backlight in Figure 8A, the SDVACRA900 in Table 2 operating in a narrow-angle state, and the profiles in Figures 8B and 16C. Features of embodiments in Figures 16C-D that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0325] In comparison with Figure 8E, Figure 16D illustrates how the size of the region where the desirable security factor (S>1) is achieved is favorably increased.

[0326] Here, we illustrate various alternative stacks 104 of the optical components equipped with the SDVACRA900 shown in Figure 1A.

[0327] Figures 17A–E are schematic diagrams illustrating alternative optical stack 104 configurations with side views for the switchable display device 100 equipped with the SDVACRA900 of Figure 1A. Features of embodiments of Figures 17A–E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0328] In the alternative embodiments shown in Figures 17A-E, various stacks provide different levels with respect to security coefficients, frontal reflection from electrodes, and transmission or emission displays. The SDVACRA900 can be arranged to achieve desired characteristics for the performance of the display device 100.

[0329] Herein, we describe an alternative configuration of the switchable display device 100, which includes an additional switchable liquid crystal retarder.

[0330] In some cases, it is desirable to provide increased diffusion in wide-angle settings.

[0331] Figure 18A is a schematic diagram illustrating a switchable display device in a perspective side view, comprising an SDVACRA900 with an SDLCR901A and a further retarder with an additional SDLCR901B. Features of the embodiment of Figure 18A that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0332] In an alternative embodiment of Figure 18A, the SDVACRA900 comprises an SDLCR901A and a further SDLCR901B, the further SDLCR901B comprising a layer 914B of liquid crystal material 915B and a further transparent electrode configuration 904B disposed to drive the layer 914B of liquid crystal material 915B of the further SDLCR901B.

[0333] In an alternative embodiment of Figure 18A, the display device 100 may be provided, and the SDVACRA900 may further comprise a further switchable liquid crystal retarder, which is an SDLCR901B comprising a layer 914B of liquid crystal material 915B, and a further transparent electrode configuration 904B disposed to drive the layer 914B of liquid crystal material 915B of the further switchable liquid crystal retarder (SDLCR901B), the further transparent electrode configuration 904B selectively drives the layer 914B of liquid crystal material 915B of the further switchable liquid crystal retarder, the liquid crystal material 91 The 5B layer 914B has an orientation structure 965B that causes a further switchable liquid crystal retarder to introduce a net relative phase shift that varies along the viewing axis 445 and the tilt axis 447 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909, and the liquid crystal material 915B layer 914B has an orientation structure 965B that causes the same net relative phase shift along the viewing axis 445 and the tilt axis 447 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909, and can be driven to a wide-angle state.

[0334] Therefore, the additional switchable liquid crystal retarder, SDLCR901B in Figure 18A, can be switched between a narrow-angle state in which transmission along the tilt axis is reduced and a wide-angle state in which transmission along the tilt axis is the same as or equal to transmission along the field axis.

[0335] Furthermore, a further switchable liquid crystal retarder is SDLCR901B, which has an orientation structure 965B that, in the narrow-angle state, introduces a net phase shift uniform across the region 103 of the liquid crystal material 915B to light having a predetermined polarization state 909, thereby preventing the liquid crystal material 915 layer 914B from causing diffraction effects on light having a predetermined polarization state 909. In the wide-angle state, the liquid crystal material 915 layer 914B has an orientation structure 965B that introduces a net phase shift that spatially varies across the region 103 of the liquid crystal material 915B layer 914 to light having a predetermined polarization state 909, thereby providing diffraction effects on light having a predetermined polarization state to the liquid crystal material layer. Further switchable liquid crystal retarders may provide a switch between no light dispersion in narrow-angle conditions and light diffraction in wide-angle conditions.

[0336] Drivers 950A and 950B are controlled by the control system 500 to switch the display device 100 between a narrow-angle state and a wide-angle state.

[0337] Compared to the embodiment in Figure 1A, light dispersion in wide-angle operation mode may be increased. Visibility of image data along the tilt axis 447 may be advantageously improved. The total retardation of layers 914 and 314 may be increased. For a higher security factor, the angle φ between the field axis 445 and the tilt axis 447 may be reduced.

[0338] Here, an embodiment involving SNDLCR301 will be described.

[0339] Figure 18B is a schematic diagram illustrating a switchable display device in an oblique side view, comprising an SDVACRA900 with an SDLCR901 and an additional retarder with an SNDLCR301. Features of the embodiment in Figure 18A, which are not discussed in further detail, can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0340] In an alternative embodiment of Figure 18B, SDVACRA900 may further comprise an SDLCR901, an SNDLCR301 comprising a layer 314 of liquid crystal material 315, a further retarder, and a further permeable electrode configuration 324 disposed to drive the layer 314 of liquid crystal material 315 of the further SNDLCR301, the further permeable electrode configuration 324 selectively drives the layer 314 of liquid crystal material 315 of the further SNDLCR301, the further switchable liquid crystal material 315B layer 314B The crystal retarder can be driven to a narrow-angle state, having an orientation structure 365B that introduces a net relative phase shift that varies along the field axis 445 and the tilt axis 447 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909, and a wide-angle state, having an orientation structure 365B in which the layer 314B of the liquid crystal material 315B introduces the same net relative phase shift along the field axis 445 and the tilt axis 447 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909.

[0341] A further switchable liquid crystal retarder is SNDLCR301, which, in both the narrow-angle and wide-angle states, has an orientation structure 365 that causes the layer 314 of the liquid crystal material 315 to introduce a net phase shift to light having a predetermined polarization state 909, thereby preventing the layer 314 of the liquid crystal material 315 from providing a diffraction effect to light having a predetermined polarization state. Compared to the embodiment in Figure 18A, residual diffraction in the narrow-angle state can be reduced. An improvement in the security factor can be achieved along the tilt axis 447.

[0342] As will be further described below, the SNDLCR301 comprises a layer 314 of liquid crystal material 315, surface alignment layers 317A, 317B on both sides of the layer 314 of liquid crystal material 315, and a transparent electrode configuration 324 disposed to drive the layer 314 of liquid crystal material 315, with uniform (unpatterned) electrodes 322A, 322B on both sides of the layer 314 of liquid crystal material 315. Drivers 350 and 950 are controlled by the control system 500 to switch the display device 100 between a narrow-angle state and a wide-angle state.

[0343] Compared to the embodiment in Figure 18A, the total retardation of layers 914 and 314 may be increased. For a higher security factor, the angle φ between the field axis 445 and the tilt axis 447 may be reduced.

[0344] Figure 18C is a schematic diagram illustrating a switchable display device 110 in a perspective side view, comprising a backlight 20, an additional polarizer 818, and an SDVACA800 disposed between the additional polarizer 818 and the display polarizers 210, 810, wherein the SDVACA800 comprises SDLCE801 and SDVACRA900. Features of the embodiment of Figure 18C not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0345] Compared to Figure 1A, SDVACRA900 further comprises a switchable diffractive liquid crystal element (SDLCE) 801 further comprising a layer 814 of liquid crystal material 815 and a further transparent electrode configuration 804 disposed to drive the layer 814 of liquid crystal material 815 of SDLCE801, wherein the further transparent electrode configuration 804 selectively drives the layer 814 of liquid crystal material 815 of the further SDLCR so that the layer 814 of liquid crystal material 815 has a net phase shift that is uniform across the region of the layer 814 of liquid crystal material 815, having a predetermined polarization state. The pattern is designed to allow the liquid crystal material 815 to be driven into two states: a non-diffraction state having an orientation structure 865 that introduces a net phase shift that varies spatially across the region 103 of the liquid crystal material 815 to light having a predetermined polarization state 909, thereby allowing the liquid crystal material 815 to provide a diffraction effect to light having a predetermined polarization state 909; and a wide-angle state having an orientation structure 865 that introduces a net phase shift that varies spatially across the region 103 of the liquid crystal material 815 to light having a predetermined polarization state 909, thereby allowing the liquid crystal material 815 to provide a diffraction effect to light having a predetermined polarization state.

[0346] In comparison with Figure 18A, the alternative embodiment in Figure 18C illustrates that a further switchable liquid crystal retarder may comprise an SDLCE801 instead of a further SDLCR901B. In operation in the wide-angle state, the SDVACRA900 is arranged to provide further diffraction, increasing diffusion in wide-angle mode, but preferably without significantly altering the performance in the narrow-angle state provided by the SDLCR900. The SDLCE801 may have reduced cost, complexity, and power consumption compared to the further SDLCR901B in Figure 18A.

[0347] In some cases, it is desirable to increase the security factor in a narrow-angle state. Here, an embodiment involving additional polarizers is described.

[0348] Figure 18D is a schematic diagram illustrating a switchable display device 100 in a perspective side view, comprising a display polarizer 210, an SDVACRA900A, an additional polarizer 918A, a further SDVACRA900B, and a further additional polarizer 918B. Features of the embodiment in Figure 18D that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0349] Most commonly, the display device 100 may further comprise a further additional polarizer 918B, which is a linear polarizer, located on the same side as the first-mentioned additional polarizer 918A in the SLM48 and disposed either a) between the display polarizer 910 and the first-mentioned SDVACRA900A, or b) outside the first-mentioned additional polarizer 918A; and a further switchable liquid crystal retarder configuration disposed either a) between the further additional polarizer 918B and the display polarizer 910 when the further additional polarizer 918A is disposed between the display polarizer 910 and the first-mentioned SDVACRA900A, or b) between the first additional polarizer 918A and the further additional polarizer 918B when the further additional polarizer 918B is disposed outside the first-mentioned additional polarizer 918A.

[0350] The further switchable liquid crystal retarder configuration comprises a further switchable liquid crystal retarder having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder configuration.

[0351] Further transparent electrode configurations can selectively drive the liquid crystal material layer of a further switchable liquid crystal retarder to a narrow-angle state having an orientation structure that causes the liquid crystal material layer to introduce a net relative phase shift that varies along the field axis 445 and the tilt axis 447 into the orthogonal polarization components 997, 999 of light having a predetermined polarization state, and to a wide-angle state having an orientation structure that causes the liquid crystal material layer to introduce the same net relative phase shift along the field axis 445 and the tilt axis 447 into the orthogonal polarization components 997, 999 of light having a predetermined polarization state 909, into the further switchable liquid crystal retarder.

[0352] In an alternative embodiment of Figure 18D, the display device 100 comprises an additional polarizer 918A, and further an additional polarizer 918B which is a linear polarizer located on the same side as the additional polarizer 918A first mentioned in SLM48. A further SDVACRA900B is disposed between the additional polarizer 918A and the further additional polarizer 918B. The further SDVACRA900B comprises a layer 914B of liquid crystal material 915B and a further transparent electrode configuration 904B disposed to drive the layer 914B of liquid crystal material 915B of SDVACRA900B, the further transparent electrode configuration 904B being able to selectively drive the liquid crystal material layer 914B of SDVACRA900B into a narrow-angle state and a wide-angle state.

[0353] Compared to Figure 18A, in operation in the narrow-angle state, a reduction in brightness along the tilt axis 447 can be achieved, and the illustrative transmission profiles in Figures 8B, 9G, or 10B, for example, advantageously achieve an increase in the security factor S for the viewer 47 along the tilt axis 447.

[0354] Compared to Figure 1A, in the wide-angle state, the SCVACRA900B can achieve an increase in the diffusion of light from the backlight 20. The increased brightness can be provided along the tilt axis 447, and advantageously, image visibility can be achieved.

[0355] In narrow-angle conditions, it may be desirable to increase the security factor S by providing increased reflectivity of the display device.

[0356] Figure 18E is a schematic diagram illustrating a switchable display device 100 in a perspective side view, comprising a display polarizer 210, an SNDLCRA 300, a further additional polarizer 318, an SDVACRA 900 with an SDLCR 901, and an additional polarizer 918. Features of the embodiment of Figure 18E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0357] In the alternative embodiment shown in Figure 18E, the display device 100 includes an SDVACRA 900 and an additional polarizer 918. The display device 100 further comprises a further additional polarizer 318, which is a linear polarizer, located on the same side as the additional polarizer 918 first mentioned in SLM48 and disposed between the display polarizer 210 and the SNDLCRA300 first mentioned, and a further switchable liquid crystal retarder configuration which is the SNDLCRA300 disposed between the first additional polarizer 918A and the further additional polarizer 318A, wherein the further SNDLCRA300 comprises a further switchable liquid crystal retarder which is the SNDLCRA301, comprising a layer 314 of liquid crystal material 315 and a further transparent electrode configuration 304 disposed to drive the layer 314 of liquid crystal material 315 of the further SNDLCRA300, wherein the further transparent electrode configuration 304 selectively drives the layer 314 of liquid crystal material 315 of the further SNDLCRA300, so that the layer 314 of liquid crystal material 315 is SNDLCRA A further switchable liquid crystal retarder configuration, 900, can be driven to a narrow-angle state, having an orientation structure 365 that introduces a net relative phase shift, which varies along the field axis 445 and the tilt axis 447, into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909, and a wide-angle state, having an orientation structure 365 that introduces the same net relative phase shift, which is the same along the field axis 445 and the tilt axis 447, into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909, into the further switchable liquid crystal retarder.

[0358] In alternative embodiments not shown, the sequences of SDVACRA900 and SNDLCRA300 may be reversed. More generally, the display device 100 includes an additional polarizer 918, which is on the same side as the first-mentioned additional polarizer 918 in SLM48 and further additional polarizers 318 disposed either a) between the display polarizer 210 and the first-mentioned SDVACRA900, or b) outside the first-mentioned additional polarizer 918, and a) between the further additional polarizer and the display polarizer if the further additional polarizer is disposed between the display polarizer and the first-mentioned SDVACRA900, or b) further When an additional polarizer is disposed outside the first-mentioned additional polarizer 918, the present invention further comprises a further switchable liquid crystal retarder configuration disposed either between the first additional polarizer 918 and the further additional polarizer, the further switchable liquid crystal retarder configuration comprising a liquid crystal material layer and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder, the further transparent electrode configuration being able to selectively drive the liquid crystal material layer of the further switchable liquid crystal retarder configuration to a narrow-angle state or a wide-angle state.

[0359] The SNDLCRA300 comprises the SNDLCR301 and further comprises a passive compensation retarder 330. In alternative embodiments, such as the SNDLCR301 with twist, the passive compensation retarder 330 may be omitted. The SNDLCRA is positioned between the display polarizer 310 and an additional polarizer 318. Drivers 350 and 950 are controlled by the control system 500 to switch the display device 100 between a narrow-angle state and a wide-angle state.

[0360] The SDVACRA900 is positioned between an additional polarizer 918 and a further additional polarizer 318. The SNDLCRA300 is positioned between an additional polarizer 318 and the display polarizer 210. The isolation of the SDLCRA from the pixel plane 214 is increased, and advantageously, moiré patterns are reduced. In an alternative embodiment, as illustrated in Figures 19A-E below, the SDLCRA may be positioned between an additional polarizer 918 and the input display polarizer 210, and the SNDLCRA may be positioned between a further additional polarizer 318 and the additional polarizer 918.

[0361] In operation under narrow-angle conditions, the polarizers 210 and 318 of the SNDLCRA300 and Figure 18E, respectively, can achieve a reduction in brightness along the tilt axis 447. For example, the illustrative transmission profiles in Figures 8B, 9G, or 10B favorably achieve an increase in the security factor S for the viewer 47 along the tilt axis 447.

[0362] It may be desirable to provide an increased security factor in narrow-angle conditions.

[0363] Figure 18F is a schematic diagram illustrating a switchable display device 100 in a perspective side view, comprising a backlight 20, an additional polarizer 918, an SDVACRA 900, a transmissive SLM 48, a reflective polarizer 302, an SNDLCRA 300, and a further additional polarizer 318. Features of the embodiments of Figure 18F that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0364] The display device 100 may further comprise a backlight 20 arranged to output light, the SLM 48 being a transmissive SLM 48 arranged to receive output light from the backlight 20, the first-mentioned display polarizer 910 being either a) an input polarizer 210 or b) an output polarizer 218, the display device 100 may a) output polarizer 218 when the first display polarizer 910 is an input polarizer 210, or b) output polarizer 190 when the first display polarizer 190 is an output polarizer The display device 100 further comprises an additional display polarizer 318 which is either the input polarizer 210 or the polarizer 218, and the display device 100 further comprises an additional polarizer 318 which is either a) on the output side of the output polarizer 218 when the first display polarizer 910 is the input polarizer 210, or b) between the input polarizer 210 and the backlight 20 when the first display polarizer 910 is the output polarizer 218, and the display device 100 is shown in Figure 18F. The further configuration includes a further switchable liquid crystal retarder configuration, which is an SNDLCRA300 disposed between an additional polarizer 318 and an additional display polarizer 310, the further SNDLCRA300 comprising a further SNDLCR301 comprising a layer 314 of liquid crystal material 315 and a further transparent electrode configuration disposed to drive the layer 314 of liquid crystal material 315 of the further switchable liquid crystal retarder, the further transparent electrode configuration selects the layer 314 of liquid crystal material 315 of the further SNDLCR301 The liquid crystal material 315 can be selectively driven to a narrow-angle state, in which the layer 314 of the liquid crystal material 315 has an orientation structure 365 that introduces a net relative phase shift that varies along the viewing axis 445 and the tilt axis 447 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909, and to a wide-angle state, in which the layer 314 of the liquid crystal material 315 has an orientation structure 865 that introduces the same net relative phase shift along the viewing axis 445 and the tilt axis 447 into the orthogonal polarization components 997 and 999 of light having a predetermined polarization state 909.

[0365] In other words, the display device further comprises a backlight arranged to output light, the SLM is a transmissive SLM arranged to receive output light from the backlight, the first mentioned display polarizer is either a) an input polarizer or b) an output polarizer, the display device further comprises a further display polarizer which is either a) an output polarizer if the first display polarizer is an input polarizer, or b) an input polarizer if the first display polarizer is an output polarizer, the display device further comprises a further additional polarizer arranged either a) on the output side of the output polarizer if the first display polarizer is an input polarizer, or b) between the input polarizer and the backlight if the first display polarizer is an output polarizer, the display device further comprises a further additional polarizer and further display The further switchable liquid crystal retarder comprises a further switchable liquid crystal retarder configuration disposed between it and a ray polarizer, the further switchable liquid crystal retarder configuration comprising a liquid crystal material layer and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder, the further transparent electrode configuration can selectively drive the liquid crystal material layer of the further switchable liquid crystal retarder into a narrow-angle state having an orientation structure that causes the liquid crystal material layer to introduce a net relative phase shift that varies along the field axis and tilt axis into the orthogonal polarization component of light having a predetermined polarization state into the further switchable liquid crystal retarder configuration, and into a wide-angle state having an orientation structure that causes the liquid crystal material layer to introduce a net relative phase shift that is the same along the field axis and tilt axis into the orthogonal polarization component of light having a predetermined polarization state into the further switchable liquid crystal retarder configuration.

[0366] Compared to Figure 18E, the alternative embodiment in Figure 18F achieves an increase in the security factor S in the narrow-angle state resulting from the reflective polarizer 302, the operation of which is shown in Figure 39B below. An illustrative reflectance profile is given in Figure 16C. Compared to Figure 16B, the embodiment in Figure 18F achieves a reduction in blur of pixel 220. The security factor S is also increased.

[0367] Figure 18G is a schematic diagram illustrating a switchable display device 100 in an oblique side view, comprising a backlight 20, an SDLCE801, an additional polarizer 918, and an SDLCRA900 between the additional polarizer 918 and the display polarizers 210, 910, wherein the SDLCRA900 comprises an SDLCR901 and a passive compensation retarder 930. Features of embodiments of Figure 18G that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0368] In the alternative embodiment shown in Figure 18G, the SDLCE801 is positioned outside the additional polarizer 918. As described below, the SDLCE801 is positioned to switch between the narrow-angle and wide-angle diffraction states. Compared to the embodiment shown in Figure 18C, stray light may be reduced in the narrow-angle mode, and the security coefficient S may be increased along the tilt axis 447.

[0369] This section describes additional display devices equipped with SDVACRA900 and further, non-exclusive, alternative configurations.

[0370] Figures 19A–E illustrate schematic side views of alternative stacking configurations for a switchable display device 100 comprising at least one SDVACRA900, a further switchable viewing angle control configuration, a transmissive SLM48, and a backlight20. Features of embodiments of Figures 19A–E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0371] At least the various alternative embodiments shown in Figures 19A-E can be selected to achieve the desired characteristics of a switchable display, such as increased security factor, reduced image blur, increased wide-angle visibility, thickness, and complexity.

[0372] Herein, we will describe an alternative, switchable display device 110.

[0373] Figure 20A is a schematic diagram illustrating a switchable display device 110 in a perspective side view, comprising a backlight 20, an additional polarizer 818, a switchable diffraction field of view control configuration (SDVACA) 800, and an SLM 48, wherein the SDVACA 800 is positioned between the additional polarizer 818 and the display polarizer 810, which is the input polarizer 210 of the SLM 48. Figure 20B is a schematic diagram illustrating an alignment orientation for an optical stack 104 used in the embodiment of Figure 20A in a perspective front view. Features of embodiments of Figures 20A-B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0374] In comparison with the embodiments described herein, the display device 100 is alternatively an SLM48 disposed to output spatially modulated light, a display polarizer 810 disposed on the side of the SLM48 which is a linear polarizer, an additional polarizer 818 disposed on the same side of the SLM48 outside of the display polarizer 810 which is a linear polarizer, and an SNDLCRA300 disposed between the additional polarizer 818 and the display polarizer 810 which comprises a layer 314 of liquid crystal material 315 and a transparent electrode configuration 324, wherein the transparent electrode configuration 324 selectively transmits the layer 314 of liquid crystal material 315 to the SNDLCRA300, along the field of view axis 445 and the field of view axis The SNDLCRA300 includes an SNDLCRA301, which is configured to drive the SNDLCRA300 into a narrow-angle state in which a net relative phase shift that varies along a tilt axis 447 tilted to 445 is introduced into the orthogonal polarization components 997, 999 of light having a predetermined polarization state 909, and a wide-angle state in which a layer 314 of liquid crystal material 315 is configured to drive the SNDLCRA300 into a wide-angle state in which a net relative phase shift that is the same along the field axis 445 and the tilt axis 447 is introduced into the orthogonal polarization components 997, 999 of light having a predetermined polarization state 909, and the SNDLCRA300 also includes an SLM48, a display polarizer 810, an additional polarizer 818, and a switchable optical dispersion configuration (SLDA)200 arranged in series with the SNDLCRA300, which is switchable between a non-dispersive state that does not provide light dispersion and a dispersed state that provides light dispersion.

[0375] The display device 110 comprises an SLM 48 arranged to output spatially modulated light, a display polarizer 810 disposed on the side of the SLM 48 which is a linear polarizer, and an additional polarizer 818 disposed on the same side of the SLM 48 as the display polarizer 810 outside of it, which is a linear polarizer having an electric vector transmission direction 819.

[0376] In the embodiments shown in Figures 20A and 20B, the display device 110 further comprises a backlight 20 arranged to output light 400, the SLM 48 is a transmissive SLM 48 arranged to receive the output light from the backlight 20, and the display polarizer 810 is an input display polarizer 210 arranged on the input side of the SLM 48.

[0377] The SDVACA800 comprises the SNDLCRA300 and SLDA200 as described herein, and is positioned between an additional polarizer 818 and a display polarizer 810, which is the input polarizer 210 of the SLM48.

[0378] The SLDA200 is switchable between a non-dispersive state that does not provide light dispersion and a dispersed state that provides light dispersion, and the SLDA200 is positioned between the display polarizer 810 and an additional polarizer 818.

[0379] In this specification, optical dispersion refers to the amount of dispersion, scattering, diffraction, or refraction of an incident plane wave to multiple gradient plane waves. Switchable optical dispersion refers to switching the amount of dispersion between a wide-angle state (high dispersion) and a narrow-angle state (low dispersion). In comparison, a switchable retarder such as the SNDLCR301 reduces transmission along the gradient axis 447 compared to transmission along the field axis 445 in the narrow-angle state, and maintains transmission along the gradient axis 447 compared to transmission along the field axis 445 in the narrow-angle state.

[0380] In the embodiments shown in Figures 20A and 20B, the SLDA200 includes the SDLCE801.

[0381] SDLCE801 comprises a layer 814 of liquid crystal material 815 and a transparent electrode configuration 804 disposed to drive the layer 814 of liquid crystal material 815, wherein the transparent electrode configuration 804 selectively causes the layer 814 of liquid crystal material 815 to introduce a net phase shift uniform across the region of the layer 814 of liquid crystal material 815 to light having a predetermined polarization state 909, thereby preventing the layer 814 of liquid crystal material 815 from providing dispersion of light having a predetermined polarization state 909, thus providing an orientation structure. The pattern is designed to be driven to a non-diffraction state corresponding to the non-dispersion state of SLDA200, and a diffraction state corresponding to the dispersion state of SLDA200, having an orientation structure in which layer 814 of the liquid crystal material 815 introduces a net phase shift that varies spatially across the region of layer 814 of the liquid crystal material 815 to light having a predetermined polarization state 909, thereby causing layer 814 of the liquid crystal material 815 to provide dispersion of light due to the diffraction effect.

[0382] SDLCE801 comprises transparent substrates 812, 816, with a layer 814 of liquid crystal material 815 disposed between them; surface alignment layers 817A, 817B on both sides of the layer 814 of liquid crystal material 815; an electrode configuration 804 comprising mutually mated spatial isolation electrodes 802A, 802B having a gap 832; and a driver 850. The surface alignment layers 817A, 817B are arranged to provide homeotropic alignment directions 827A, 827B on the respective surfaces of the liquid crystal material 815. SDLCE801 comprises a transparent electrode configuration 804 disposed to drive a layer 814 of liquid crystal material 815, the transparent electrode configuration 804 being patterned to drive the layer 814 of liquid crystal material 815 into an orientation structure 865 that provides a net relative phase shift, a net phase difference Γ(x) of spatially varying wavefronts over a region 103 of the layer 814 of liquid crystal material 815, and causes a diffraction effect in the layer 814 of liquid crystal material 815.

[0383] SDLCE801 provides light dispersion by diffraction in the wide-angle dispersion state, as described by the following illustrative embodiment. In the narrow-angle state, SLDA200 may provide some residual luminance correction between axes 445 and 447, but its primary functions are light dispersion in the wide-angle state and reduced light dispersion in the narrow-angle state. A passive correction retarder 830 having an optical axis direction 831 may be provided between SLDCE801 and SNDLCRA300, as described below.

[0384] SNDLCRA300 comprises a transparent substrate 312, 316, a transparent electrode configuration 324 comprising a layer 314 of liquid crystal material 315, surface alignment layers 317A, 317B on both sides of the layer 314 of liquid crystal material 315, and electrodes 322A, 322B on both sides of the layer 314 of liquid crystal material 315.

[0385] The SNDLRCA300 may further comprise a passive compensation retarder 330. When positioned between the display polarizer 810 and the additional polarizer 818, the primary purpose of the SNDLRCA300 is, for example, to reduce the transmitted brightness on the tilt axis 447 compared to the field axis 445 when operating in a narrow-angle state, as illustrated in Figure 39A, and to maintain the transmitted brightness on the tilt axis 447 compared to the field axis 445 when operating in a wide-angle state, as illustrated in Figure 40A.

[0386] The display device 110 uses a voltage driver 350 to drive a layer 314 of the liquid crystal material 315 to a transparent electrode configuration 324, applying a voltage V 314 The system further comprises a control system 500 arranged to control the SNDLCR301 by supplying a voltage V 814 It is further configured to control the SDLCE801 by supplying the necessary components.

[0387] Figure 20C is a schematic diagram illustrating the electrode configuration 804 of SDLCE801 and the electrode configuration 324 of SNDLCR301 in perspective side views, as shown in Figures 20A-B. Features of the embodiments in Figure 20C that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0388] Figure 20C illustrates that the electrode configuration 804 may comprise interlocked patterned electrodes 802A, 802B, each having busbars 803A, 803B located outside region 103. The substrate 816 does not have electrodes. Advantageously, the SDLCE 801 can be offered at a lower cost and complexity. Furthermore, light transmission is increased.

[0389] Figure 20C further illustrates that the electrode configuration 324 of SNDLCR301 comprises uniform electrodes 322A and 322B arranged on the opposite side of the layer 314 of the liquid crystal material 315. Advantageously, this reduces cost and complexity.

[0390] Figure 20D is a schematic diagram illustrating an alternative field of view control element 112 in an oblique side view, comprising an SDVACA800 with SDLCE801 and SNDLCRA300. Features of the embodiment in Figure 20D that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0391] Component 102 may be added during the manufacturing of the display device 110, or alternatively, may be added to the display device 110 by the display user. Advantageously, upgrades of the switchable display device 110 can be achieved.

[0392] Figure 20D further illustrates that SNDLCR301 may be provided between passive compensating retarders 330A and 330B such that the polarization state output from SDLCE801 may differ from the polarization state input to SNDLCR301. Using such a configuration, the transmission profile of SDVACA800 in the narrow-angle state can be adjusted. The passive compensating retarder 330 may further comprise a quarter-wave plate arranged to improve the rotational symmetry of the transmission profile, for example, as described in U.S. Patent No. 11,092,852, which is incorporated herein by reference in its entirety.

[0393] The passive compensation retarder 330A may be further equipped with a passive compensation retarder 830. Advantageously, this can reduce cost and complexity.

[0394] Here, we will further explain the operation of the configuration shown in Figures 20A and 20B.

[0395] Figure 21A is a schematic diagram illustrating, in a top view, the structure and operation of an alternative optical stack 104 driven in the wide-angle state, used in the exemplary embodiments of Figures 20A-B and Tables 11-12; Figure 21B is a schematic diagram illustrating, in a top view, the structure and operation of the optical stack 104 of Figures 21A-B driven in the narrow-angle state; and Figure 21C is a schematic diagram illustrating, in a top view, the optical stack 104 of Figures 21A-B driven in the intermediate state. Features of embodiments of Figures 21A-C that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features. [Table 14] Table 11 [Table 15] Table 12

[0396] Here, we will describe the drive waveforms for the embodiments shown in Tables 11 to 16.

[0397] Figure 22A is a schematic graph illustrating the drive waveform of the SDVACA800 of the optical stack 104 in Figures 20A-B in the wide-angle state; Figure 22B is a schematic graph illustrating an alternative drive waveform of the SDVACA800 in Figures 20A-B in the narrow-angle state; and Figure 22C is a schematic graph illustrating the drive waveform of the SDVACA800 in Figures 20A-B in the intermediate state. Features of the embodiments in Figures 22A-C that are not discussed in further detail can be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0398] The control system 500 is configured to control which of the waveforms shown in Figures 22A-C is supplied to the voltage drivers 350, 850, providing wide-angle, narrow-angle, or intermediate operation, respectively. The alternating profiles provide DC balancing and achieve increased device lifespan. Non-square voltage profiles may be provided to achieve the desired addressing levels for layers 814, 314 of the liquid crystal materials 815, 315 for SDLCE801 and SNDLCRA300, respectively.

[0399] Here, we will further explain the operation of the illustrative display device 110, which has the electrode configuration 804 shown in Figure 20C, as shown in Figures 21A-C and Tables 11-12.

[0400] Figure 23A is a schematic diagram illustrating the transmissive electrode configuration 804 of Figure 21A, and the orientation structure 865 of the liquid crystal material 815 for SDLCE801 and the orientation structure 365 of the liquid crystal material 315 for SNDLCR301 in a perspective front view, operating in a wide-angle state. Figure 23B is a schematic diagram illustrating the orientation structure 865 of the liquid crystal material 815 for SDLCE801 in Figure 21A and Tables 11-12 in a top view. Figure 23C is a schematic graph illustrating the diffraction brightness profile 430 to the diffraction order for the embodiment of Figure 23B. Figure 23D is a schematic diagram illustrating in a perspective front view the orientation structure 865 of the liquid crystal material 815 for SDLCE801 and SNDLCR301 of Figure 21B operating in a narrow-angle state; Figure 23E is a schematic diagram illustrating in a perspective front view the orientation structure 865 of the liquid crystal material 815 for SDLCE801 and the orientation structure 365 of the liquid crystal material 315 for SNDLCR301 of Figure 21C operating in an intermediate state; and Figure 23F is a schematic diagram illustrating in a top view the orientation structure 865 of the liquid crystal material 815 for SDLCE801 of Figures 21B-C. Features of embodiments of Figures 23A-F that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0401] The control system 500 is configured to, when the display device 110 is in a narrow-angle state, supply a voltage to the transparent electrode configuration 324 that is selected to drive the layer 314 of the liquid crystal material 315 of SNDLCR301 to that narrow-angle state, thereby switching the SLDA200 to a non-dispersive state, and when the display device 110 is in a wide-angle state, supply a voltage to the transparent electrode configuration 324 that is selected to drive the layer 314 of the liquid crystal material 315 of SNDLCR301 to that wide-angle state, thereby switching the SLDA200 to a dispersed state.

[0402] In the embodiments shown in Figures 21A and 23A, the control system 500, in the wide-angle state, supplies a voltage selected by the voltage driver 350 to a transmissive electrode configuration 324 comprising electrodes 322A and 322B to drive a layer 314 of the liquid crystal material 315, thereby providing the SDVACA 800 with a net relative phase shift η 800 ( φ 445 ) is not introduced into the orthogonal polarization components 997(445), 999(445) of light passing through the additional polarizer 818 along the field axis 445, and the net relative phase shift η is not introduced into SDVACA800. 800 ( φ 447 The additional polarizer 818 is positioned so as not to introduce the orthogonal polarization component of the light passing through it along the tilt axis 447, which is tilted to the field axis 445. The operation of the SDVACA800 in the wide-angle state is similar to that shown in Figure 6E above in this specification. During operation, some residual polarization mixing as described herein may be present in the SLDCE801, but such polarization mixing will generally be small. High transmission along the tilt axis 447 is achieved.

[0403] The control system 500 is further configured to supply voltage to the voltage driver 850 to switch the SLDA200, which is SDLCE801, into a dispersed state. As illustrated in Figure 21A, in the dispersed state, SDLCE801 provides light dispersion in direction 195 across a region 103 of the layer 814 of the liquid crystal material 815. SNDLCRA300 is arranged so as not to provide a reduction in brightness with respect to the viewing angle φ. Brightness is increased along the tilt axis 447, and advantageously, image visibility along the tilt axis 447 is increased in the wide-angle state.

[0404] In contrast to Figure 21A, in the illustrative embodiments of Figures 21B and 23D, the control system 500 is configured to supply a voltage to the transparent electrode configuration 324, selected by the driver 350 to drive the layer 314 of the liquid crystal material 315 into a narrow-angle state. That is, the layer 314 of the liquid crystal material 315 is configured such that SDVACA 800 controls the net relative phase shift η 800 ( φ 445) is not introduced into the orthogonal polarization components 997(445), 999(445) of light passing through the additional polarizer 818 along the field axis 445, and the net relative phase shift η is not introduced into SDVACA800. 800 ( φ 447 The polarizer is positioned to introduce orthogonal polarization components 997(447), 999(447) of light passing through an additional polarizer 818 along a tilt axis 447 tilted to the field axis 445. The control system 500 is further positioned to switch the SDLCE801 to a non-dispersive state in the narrow-angle state shown in Figure 21A. Low brightness can be achieved along the tilt axis 447, which is advantageous in achieving an increase in the security factor S in the case of privacy mode operation.

[0405] Here, we will examine the operation of the SDLCE801 under narrow-angle conditions.

[0406] The SDLCR901 in Figure 1A, as illustrated in Figure 40A, primarily aims to reduce the transmitted brightness at the tilt axis 447 compared to the field axis 445, to prevent light diffraction when operating in a narrow-angle state, and to diffract light from the field axis 445 toward the tilt axis 447 when operating in a wide-angle state. In the narrow-angle state, the liquid crystal structure 965 of the SDLCR901 behaves as an O-plate to provide such behavior.

[0407] In comparison, the SDLCE801 in Figure 20A is primarily intended to maintain transmittance along the tilt axis 447 compared to the field axis 445 when operating in a narrow-angle state, and to diffract light when operating in a wide-angle state. The electrode configuration 804 and layer 814 of the liquid crystal material 815 differ from the electrode configuration 904 and layer 914 of the liquid crystal material 915 described herein. In a narrow-angle state, the liquid crystal structure 865 of the SDLCE801 has a vertical orientation resulting from the homeotropic surface alignment layers 827A, 827B that provide the structure 865 of the positive C plate. When the SDLCE801 is positioned between the additional polarizer 818 and the display polarizer 810, the behavior of the positive C plate provides an undesirable transmittance profile. A passive correction retarder 830 may be positioned to correct the configuration of the positive C plate in a narrow-angle state to provide a uniform linear polarization state for input to the SNDLCRA300, which preferably has a wide field of view. Both the SDLCE801 and the passive correction retarder 830 reduce the net relative phase shift η to the orthogonal polarization components 997(447) and 999(447) of light passing through the SNDLCRA300. 300 ( φ 447 ) compared to the net relative phase shift η 801 ( φ 447 This substantially does not provide the orthogonal polarization components 997(447) and 999(447) of light passing through the SNDLCRA300 along the inclination axis 447. The narrow-angle performance of the SNDLCRA300 may be improved, and transmission along the inclination axis 447 may be reduced.

[0408] Alternative embodiments in Figures 21A-B include a layer 814 of liquid crystal material 815 having sufficient retardance to provide SDLCE801 for high diffraction efficiency in the wide-angle state. Such a diffracting structure 865 of SDLCE801 may preferably have a retardance close to half-wavelength retardance. The diffracting structure 865 extends through layer 870A in Figure 23B, which is typically half the thickness separation of layer 814. The retardance of layer 814 of liquid crystal material 815 is preferably 200 nm to 600 nm, more preferably 450 nm to 550 nm. The passive correction retarder 830 may be a negative C plate or an intersecting positive A plate, and each passive correction retarder has substantially the same retardance as layer 814.

[0409] Furthermore, compared to the SDLCR901 described herein, the SDLCE801 in Figure 23B lacks a reference electrode 902R. Such a configuration does not provide in-plane tilt of the material 815 through the thickness direction of the layer 814 of the liquid crystal material 815, and therefore, compared to the structure 965 described herein, structure 865 does not provide a uniform O-plate structure in the case of narrow-angle operating mode. Consequently, a desirable transmission profile such as that shown in Figure 8B is not provided by the SDLCE801. For example, the luminance profile in the narrow-angle state can be improved to correct the size of the polar region in the narrow-angle state where the security factor S is 1.0 or greater.

[0410] Furthermore, the light dispersion characteristics of the SDLCE can be improved, for example, to increase the lateral cone angle by 195 degrees for a wide-angle luminance profile similar to that of Figure 8G. This can increase the wide-angle visibility of the display device 100.

[0411] Compared to Figure 21B, in the alternative embodiments of Figures 21C and 23E, the SNDLCRA300 is switched by the control system to provide increased transmitted luminance with respect to angle φ compared to the narrow-angle state. With respect to Figure 21B, the SLDA200, which is SDLCE801, is switched by the control system to a non-dispersive state. The intermediate state can, advantageously, achieve intermediate state operation.

[0412] Here, we will describe an alternative, illustrative embodiment of the SDLCE801 for use in the SDVACA800.

[0413] Figure 23G is a schematic diagram illustrating the orientation structure 865 of the liquid crystal material 815 of SDLCE801, which has homogeneous surface alignment layers 817A and 817B, in a top view, where the in-plane alignment directions 827Ap and 827Bp are parallel and antiparallel to the transverse direction 195, and are arranged in the narrow-angle state for the embodiments in Tables 13-14. Figure 23H is a schematic diagram illustrating the top view of the configuration of Figure 23G when driven in the wide-angle state, and Figure 23I is a schematic graph illustrating the diffractive brightness profile 430 to diffraction order for the embodiments in Figure 23H and Tables 13-14. Features of the embodiments in Figures 23G-I that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features. [Table 16] Table 13 [Table 17] Table 14

[0414] Compared to the embodiments in Figures 23B and 23F, the embodiments in Figures 23H and 23G provide alternative structures 865 comprising homogeneous alignment layers 817A and 817B having alignment directions 827A and 827B that are parallel or antiparallel to the transverse direction 195, respectively.

[0415] The homogeneous alignment layers 817A and 817B can reduce the visibility of misalignment of the liquid crystal layer 315 resulting from pressurization, and advantageously, can reduce it compared to the configuration providing at least one homeotropic alignment layer 817A or 817B as shown in Figures 23B and 23F.

[0416] The upper electrode 802T is provided on the opposite side of layer 814 of the liquid crystal material 815 to the mutually mated patterned electrodes 802A, 802B. The upper electrode 802T is distinct from the reference electrode 902R in Figure 4C, for example. The upper electrode 802T provides the drive structure 865 in Figure 23H to provide the diffraction output in Figure 23H. In the narrow-angle state, the in-plane alignment structure 865 provides an A-plate structure of layer 814 of the liquid crystal material 815. Such an A-plate is aligned with the electrical vector transmission direction 819 of an additional polarizer 818 and therefore does not change the polarization state on SNDLCRA300. The passive correction retarder 830 can be omitted, advantageously reducing thickness, complexity, and cost.

[0417] Figure 23J is a schematic diagram illustrating the orientation structure 865 of the liquid crystal material 815 of SDLCE801, which has a homogeneous surface alignment layer, in a top view, where the in-plane alignment directions 827Ap and 827Bp are perpendicular to the transverse direction 195 and are arranged in the narrow-angle state for the embodiments in Tables 15-16. Figure 23K is a schematic diagram illustrating the top view of the configuration of Figure 23J when driven in the wide-angle state, and Figure 23L is a schematic graph illustrating the diffractive brightness profile 430 to diffraction order for the embodiments in Figure 23K and Tables 15-16. Features of the embodiments in Figures 23J-L that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features. [Table 18] Table 15 [Table 19] Table 16

[0418] The embodiment in Figure 23L can achieve a different diffraction profile compared to the embodiment in Figure 23I. Desired wide-angle optical dispersion characteristics can be achieved.

[0419] Here, we will describe an alternative electrode configuration 804.

[0420] Figure 24 is a schematic diagram illustrating an alternative electrode configuration 804 in a perspective side view, comprising inter-mated electrodes arranged on a single substrate, as well as additional control and reference electrodes. Features of the embodiment in Figure 24 that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0421] In comparison with Figure 20C, the alternative electrode configuration in Figure 24 features a uniform control electrode 802C instead of the entangled electrode 802B. A dielectric layer 905 is disposed between the isolation electrode 802A layer and the control electrode 802C. The voltage V814 is supplied across the dielectric layer 805. Advantageously, the manufacturing complexity of the electrode configuration 804 in Figure 20C can be reduced.

[0422] Here, we will describe an alternative optical stack featuring the SDVACA800.

[0423] Increased light dispersion can be achieved, and advantageously, image visibility at wide angles can be increased.

[0424] Figures 25A–N illustrate schematic diagrams illustrating non-exclusive side views of alternative optical stacks 104 for a switchable display device 110, where the SDLCE801 and a switchable luminance liquid crystal SNDLCRA300 are positioned between the display polarizer 810 and an additional polarizer 818. Features of embodiments of Figures 25A–N that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0425] In the alternative embodiment shown in Figure 25A, the SDLCE is positioned between the SNDLCRA300 and the display polarizer 810. In the alternative embodiment shown in Figure 25B, the SDVACA800 is positioned between the output polarizer 218, which is the display polarizer 810, and an additional polarizer 818.

[0426] The alternative embodiments shown in Figures 25C-D include SDVACA800A and a further SDVACA800B, an additional polarizer 818A and a further additional polarizer 818B.

[0427] The alternative embodiments shown in Figures 25E-F include a reflective polarizer 302. Advantageously, an increase in the security coefficient S was achieved at a tilt angle of 447 in the narrow-angle state.

[0428] An alternative embodiment in Figure 25G comprises a reflective polarizer 302 and SDVACA800A, 800B. Advantageously, increased diffusion can be achieved in the wide-angle state, and increased security coefficient S can be achieved at a tilt angle of 447 in the narrow-angle state.

[0429] An alternative embodiment in Figure 25H comprises a reflective polarizer 302, SDVACA800 and SNDLCRA300, and an alternative additional polarizer 318. Advantageously, increased diffusion can be achieved in the wide-angle state, and an increase in the security coefficient S can be achieved at a tilt angle of 447 in the narrow-angle state. Further blurring of pixel 220 in the wide-angle state is reduced.

[0430] The SDVACA800, comprising the SDLCE801 and SNDLCRA300, may be positioned on the input side of the SLM48, and the display polarizer 310 may be the input polarizer 210. Advantageously, the image contrast for light from the SLM48 may be increased.

[0431] The SDVACA800, comprising the SDLCE801 and SNDLCRA300, may be positioned on the output side of the SLM48, and the display polarizer 310 may be the output polarizer 218. Advantageously, the complexity of assembling the display device 110 can be reduced.

[0432] Alternative embodiments shown in Figures 25I-N illustrate an emissive SLM48 comprising at least one SDVACA800. Advantageously, the thickness of the display can be reduced.

[0433] Alternative embodiments (not illustrated) may offer further improvements in wide-angle visibility, image blur, thickness, cost, and complexity to achieve the desired characteristics of the display device 110.

[0434] The embodiments of Figures 25A-N, which include the SNDLCRA300, may alternatively be provided by the SDVACRA900, for example, as illustrated in Figure 18C.

[0435] Herein, we will describe a further alternative switchable display device 120.

[0436] Figure 26A is a schematic diagram illustrating in a perspective side view a switchable display device 120 comprising a backlight 20, an SLDA 200 with an SDLCE 801, a transmissive SLM 48 with input and output display polarizers 210, 218, a reflective polarizer 302, an SNDLCRA 300 and an additional polarizer 318, and Figure 26B is a schematic diagram illustrating in a perspective front view an alignment orientation for an optical stack 104 for use in the embodiment of Figure 26A. Features of the embodiments of Figures 26A-B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0437] In the alternative switchable display device 120 shown in Figures 26A-B, the display polarizer 310 is the output display polarizer 218 located on the output side of the SLM48. The display device 120 further comprises a reflective polarizer 302, which is a linear polarizer located between the output display polarizers 218, 310 and at least one initial SNDLCRA 300. Alternatively, the reflective polarizer 302 may be omitted. The SNDLCRA 300 is located between the display polarizers 218, 310 and an additional polarizer 318.

[0438] The SLDA200 is not positioned between the display polarizer 910 and the additional polarizer 918, but is positioned between the backlight 20 and the input polarizer 210 of the SLM48. In the embodiments shown in Figures 26A-B, the SLDA200 includes the SDLCE801. The SNDLCR301 includes two surface alignment layers 317A and 317B positioned adjacent to and on either side of a layer 314 of the liquid crystal material 315, with each surface alignment layer 317A and 317B positioned to provide alignment of the adjacent liquid crystal material 315. At least one SNDLCRA300 further includes at least one passive compensation retarder 330.

[0439] In the alternative embodiments shown in Figures 27A-C, the SLDA200 is positioned on the same side as the input display polarizer 210 in the SLM48 and further positioned outside the additional polarizer 318. The SLDA200 comprises an SDLCE801 comprising transparent substrates 812, 816, a liquid crystal layer 814 comprising liquid crystal material 815 having a structure 865, an electrode configuration 804 comprising inter-mating spatial isolation electrodes 806A, 806B having a gap 832, and a driver 850. Surface alignment layers 817A, 817B are positioned to provide homeotropic alignment directions 827A, 827B on the respective surfaces of the liquid crystal material 815. The SLDA200 operates in an unpolarized state. Polarization mixing due to residual retardance in the SDLCE801 does not provide optical loss in the input polarizer 210 and improves off-axis efficiency. Advantageously, the thickness can be reduced.

[0440] Here, we will further explain the operation of the display device 120 shown in Figures 26A and 26B.

[0441] Figure 27A is a schematic diagram illustrating the structure and operation of the optical stack 104 in Figures 26A-B and the electrode configuration 804 in Figure 21C (with electrode configuration 324 omitted) in the wide-angle state, in a top view; Figure 27B is a schematic diagram illustrating the structure and operation of the optical stack 104 in Figures 26A-B in the narrow-angle state, in a top view; and Figure 27C is a schematic diagram illustrating the structure and operation of the optical stack 104 in Figures 26A-B in the intermediate state, in a top view. Features of the embodiments in Figures 27A-C that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0442] Tables 17-18 provide illustrative embodiments of the configurations shown in Figures 27A-B. The retardation of the SDLCE801 can be increased to achieve increased light dispersion from the SDLCE without losses associated with undesirable polarization mixing. Advantageously, display efficiency is improved. [Table 20] Table 17 [Table 21] Table 18

[0443] In contrast to the embodiments shown in Figures 21A-C, the alternative embodiments shown in Figures 27A-C have at least one polarizer positioned between the SLDA200 and the SNDLCRA300. In the embodiments shown in Figures 27A-C, the at least one polarizer comprises an input polarizer 210 and an output polarizer 218. In the alternative embodiments, the at least one polarizer may comprise an additional polarizer 318.

[0444] The SLDA200 operates on a polarization component 909 provided by the backlight 20. Additionally, some of the light in the polarization state 911 can be transmitted by the SDLCE through the input polarizer 210 for polarization mixing in the SDLCE801, as described above herein. Losses resulting from polarization mixing in the SDLCE801 can be reduced, and efficiency can be increased.

[0445] The operation of the SNDLCRA 300, positioned between the display polarizer 310 and the additional polarizer 318, and the reflective polarizer 302 is the same as described herein. Compared with the embodiments in Figures 21A-C, the embodiments in Figures 27A-C illustrate that the transmission characteristics of the SNDLCRA 300 are not modified by the orientation structure 865 of the liquid crystal material 815 of the SDLCE 801. The polarization state 219 incident on the SNDLCRA 300 may have improved ellipticity and increased uniformity compared to the embodiments in Figures 27A-C. Advantageously, in the narrow-angle state, transmittance can be reduced along the tilt axis 447, and the size of the polar region for a desired security factor S>1 is increased. Improved image visibility can be achieved in the wide-angle state, and an improvement in the security factor S can be achieved in the narrow-angle state with respect to the tilt axis 447.

[0446] In narrow-angle conditions, it may be desirable to further increase the security factor S.

[0447] Figures 28A–H are schematic diagrams illustrating non-exclusive side views of alternative switchable display devices 120. Features of embodiments shown in Figures 28A–H that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0448] Embodiments in Figures 28A-H illustrate how configurations of the SDLCE801 and SNDLCRA300 may be provided to achieve improved security coefficients in narrow-angle conditions and / or improved luminance along the tilt axis 447 in wide-angle conditions.

[0449] In the alternative embodiments shown in Figures 28A, 28C, 28E, and 28G, the reflective polarizer 302 is omitted. Advantageously, this reduces cost and thickness.

[0450] In the alternative embodiments shown in Figures 28C-F, an SNDLCRA300A, an additional polarizer 318A, a further SNDLCRA300B, and a further additional polarizer 318B are provided. Advantageously, image security can be achieved in a narrow-angle state. The angle φ at which the desired image security coefficient S is achieved can be reduced.

[0451] In the alternative embodiments shown in Figures 28G-H, an SNDLCRA300, an additional polarizer 318, an SDVACRA900, and a further additional polarizer 918 are provided. Advantageously, image security can be achieved in the narrow-angle state. The angle φ at which the desired image security coefficient S is achieved can be reduced. Also, image visibility can be improved in the wide-angle state.

[0452] Here, we will discuss the alternative SLDA200.

[0453] Figure 29A illustrates a switchable display device 130 in a perspective side view, which includes a backlight 20, a switchable surface relief birefringence configuration (SSRBA) 600 comprising a surface relief birefringence element (SRBLDE) 601 and a polarization control element (PCE) 610, a transmissive SLM 48 having input and output polarizers 210 and 218, a reflective polarizer 302, an SNDLCRA 300, and an additional polarizer 318. These are schematic diagrams, where Figure 29B is a schematic diagram illustrating the alignment orientation of the optical stack 104 for use in the embodiment of Figure 29A in a perspective front view, Figure 29C is a schematic diagram illustrating the operation of the SSRBA600 of Figures 29A-B in a top view in a wide-angle state, Figure 29D is a schematic diagram illustrating the operation of the SSRBA600 of Figures 29A-B in a narrow-angle state in a top view, and Figure 29E is a schematic diagram illustrating the SRBLDE601 in a perspective front view. Features of the embodiments of Figures 29A-E that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0454] Similar to Figures 26A-B, the SNDLCRA300 in Figures 29A-B is configured to receive light from the display polarizer 218 and switch between wide-angle and narrow-angle states, as described above in this specification. Furthermore, embodiments in Figures 28A-H may be provided with an alternative SDLA200 to that of this embodiment.

[0455] In the alternative embodiments shown in Figures 29A and 29B, the SLDA200 comprises an SSRBA600 which includes an SRBLDE601 and a PCE610.

[0456] SRBLDE601 comprises a birefringent layer 602 of a birefringent material 603 having an ordinary refractive index no and an extraordinary refractive index ne, and an isotropic layer 604 of an isotropic material 605 having an interface 608 with the birefringent layer 614, wherein the isotropic material 603 has a refractive index ni equal to the ordinary refractive index no or extraordinary refractive index ne of the birefringent material, and the interface surface 608 has a dispersive surface relief. In practice, some small refractive index difference may exist between refractive index ni and no or between refractive index ni and ne, for example, the difference between ni and no or between ni and ne may be less than 30%, preferably less than 15%, of the difference between no and ne.

[0457] In other words, SRBLDE601 comprises a structured interface 608 between an isotropic material 605 and a birefringent material 603. The birefringent material 603 can be aligned with an alignment layer 607 provided on the interface 608 such that the material 603 has each component of alignment in the plane of layer 607p, which can be provided by at least a surface alignment layer 607. The isotropic material 605 may include, for example, a solid transparent polymer material such as a UV-curable material, and the birefringent material 603 may include, for example, a curable liquid crystal material such as a reactive mesogen.

[0458] The PCE610 comprises transparent substrates 612, 616, a layer 614 of liquid crystal material 615, surface alignment layers 617A, 617B on both sides of the layer 614 of liquid crystal material 615, and a transparent electrode configuration 624 disposed to drive the layer 614 of liquid crystal material 615, with uniform electrodes 622A, 622B on both sides of the layer 614 of liquid crystal material 615. The control system 500 is disposed to control a voltage driver 650 that provides a first voltage in the wide-angle state shown in Figure 29C and a second different voltage in the narrow-angle state shown in Figure 29D.

[0459] In the illustrative embodiment shown in Figure 29B, the PCE610 may comprise surface alignment layers 617A and 617B, which are homogeneous surface alignment layers. Advantageously, the visibility of the liquid crystal material 615 flow under pressure can be reduced. Alternatively, the PCE610 may comprise surface alignment layers 617A and 617B, which are homeotropic surface alignment layers. Advantageously, power consumption in the wide-angle state can be reduced, and an applied voltage of 0V can be provided.

[0460] The alignment layers 617A and 617B have orthogonal alignment directions 617Ap and 617Bp such that the layer 614 of the liquid crystal material 615 is a twisted nematic structure arranged to rotate the input polarization state 609 to output a polarization state 611 in a first operating mode and to pass through the polarization state 611 in a second operating mode. Advantageously, the chromaticity of the output polarization state 611 can be reduced. Preferably, the PCE 610 provides a rotational polarization state for a wide field of view. Figures 29A-B illustrate that an additional optional passive compensation retarder 630 may be provided to increase the field of view of the PCE 610. Advantageously, light dispersion along the tilt axis 447 can be increased in the wide-angle state.

[0461] Here, we will explain the operation of the SSRBA600 shown in Figures 29A and 29B.

[0462] As illustrated in Figures 29C-D, the PCE610 is arranged to selectively control the polarization of light passing through the SLDA200 (i.e., SSRBA600) between a first polarization state 611 experiencing an ordinary refractive index no in the birefringent layer and a second polarization state 609 experiencing an extraordinary refractive index ne in the birefringent layer 614. The surface relief is refraction-induced dispersion, and in the embodiments of Figures 29A-D, the surface relief is a random profile. Alternatively, the surface relief may include at least one of a lens profile, a prism profile, a random profile, or a designed profile.

[0463] In the wide-angle state, as illustrated in Figure 29C, input light 460, 462 having a polarization state 609 incident on the interface 608 is dispersed due to the refractive index step between the isotropic material 603 and the birefringent material 603. Such light is then incident on the PCE 610. A layer 614 of the liquid crystal material 615 is arranged to provide a rotation of the polarization state of the incident polarization component 609, resulting in an output polarization state 611 which is transmitted by the input display polarizer 210 in the wide-angle state.

[0464] As illustrated in Figure 29D for the narrow-angle state, light having polarization state 611 is substantially undispersed at the interface 608 due to the matching refractive indices for the isotropic material 603 and the birefringent material 605. Such light is then incident on the PCE 610. The layer 614 of the liquid crystal material 615 is arranged so as not to provide rotation of the polarization state of the incident polarization component 611, so that the same polarization state 611 is output and transmitted by the display polarizer 910 in the wide-angle state.

[0465] The interface 608 profile may have a profile that is dispersion by refraction and may include at least one of a lens profile, a prism profile, a random profile, or other designed profile, and may further include discontinuous gradients and other designed profiles to achieve a desired scattered light distribution. Generally, the interface 608 may be provided with small pitch features (e.g., less than 20 micrometers, and preferably less than 10 micrometers) with sharp (high gradient) changes compared to the refraction features. Discrination of the liquid crystal material 615 with such features provides improved scattering and, advantageously, can achieve higher image visibility at the tilt axis 447 in the wide-angle state. In the narrow-angle state, the incident polarization state 611 may be substantially refractive index matched at the interface, and the discrination may not substantially modify the incident wavefront 470.

[0466] Figure 29E illustrates the SRBLDE601, a refractive element that provides light dispersion by refraction in a dispersed state.

[0467] Here, we will explain the diffraction SRBLDE601.

[0468] Figure 30A is a schematic diagram illustrating the diffraction profile SRBLDE601 in a perspective front view, and Figure 30B is a schematic graph illustrating the diffraction luminance profile 430 to the diffraction order for the embodiment of Figure 30A in the wide-angle state. Features of the embodiments of Figures 30A and 30B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0469] In the alternative embodiment shown in Figure 30B, compared to Figure 29E, the surface relief 608 is diffractive dispersion with an interface 608 having a periodic feature with period q. Figure 30B shows the diffraction profile for light in polarization state 609 of Figure 29C, with a grating phase depth of π and a pitch of 10 microns for a wavelength of 550 nm and a period q of 10 μm.

number

[0470] Now, let's discuss the passenger infotainment display.

[0471] Figure 31A is a schematic diagram illustrating a passenger infotainment display device 100 for use in a vehicle 650 in a top view, and Figure 31B is a schematic diagram illustrating the operation of the passenger infotainment display device 100 of Figure 31A in a top view. Features of embodiments of Figures 31A and 31B that are not discussed in further detail may be assumed to correspond to features with equivalent reference numbers discussed above, including potential variations of the features.

[0472] Vehicles may include, for example, the automobile 650 in Figure 31A, or trains, boats, and airplanes. In an alternative embodiment of Figure 31A, the display device 100 is located at the location of the passenger information display (PID) (on the right side of the vehicle in the case of left-hand drive), and rays 445 and 447 are output to users 45 and 47, respectively. In a right-hand drive vehicle, the direction of light deflection referred to below is typically reflected around the vertical axis, i.e., the lateral direction is reversed.

[0473] This embodiment refers to the display device 100 described herein. Alternatively, the display devices 110, 120, and 130 described herein may be provided.

[0474] In the narrow-angle state, the display device 100 is positioned so as to be viewed by the front-seat passenger 45 near the on-axis 199 and obstructed by the driver 47. Rays along the inclination axis 447 may represent the direction for minimum brightness from the display device 100. Rays along the field of view axis 445 may be positioned at a non-zero angle with respect to the direction of the normal 199. Advantageously, the angular separation of the passenger 45 from the driver 47 can be increased to achieve an increased security factor S for the driver 47. Also, the passenger 45 may be positioned in a desirable seating position that is at a different angle with respect to the optical axis 199.

[0475] It is desirable that the passenger 45 be able to view information such as entertainment without images that would distract the driver 47, i.e., the narrow-angle state refers to a low-driver-distraction mode. The narrow-angle state is compared to a mode in which the passenger display is turned off when the vehicle is moving in order to prevent driver distraction. More specifically, it is desirable to maximize the security factor S at an angle α from the optical axis 199 that exceeds 30°, preferably 25°, in the direction from the optical axis 199 toward the driver 47, in order to minimize the visibility of distracting images to the driver 47 both at the nominal driver position along axis 447 and when the driver leans forward to the display while driving. It is also desirable to achieve a high security factor S with respect to the polar angle at least at angle β from the optical axis 199 in order to minimize the visibility of reflected light from surfaces inside the vehicle 650.

[0476] Furthermore, in the low stray light function under narrow-angle conditions, it may be desirable to provide an image to the passengers 45 within the narrow-angle light cone 461 at a desired brightness while reducing the brightness on reflective and scattering surfaces inside the vehicle. Advantageously, the brightness inside the vehicle 650 may be reduced during nighttime driving, potentially reducing driver distraction. Additionally, an increased display area may be provided while preferably maintaining a low level of stray light illumination inside the cabin of the vehicle 650.

[0477] In wide-angle mode, the display device 100 is positioned to be viewed by the driver 47 on an off-axis tilt axis 447. Such use may be made when it is safe to view the display content, such as when the vehicle is stationary, or when the content is appropriate, such as maps or instrument data.

[0478] As illustrated in Figure 31B, for example, the asymmetric diffraction profile 430 in Figure 15D can be configured to achieve an optical cone 465 that preferentially tilts toward the driver 47 in the wide-angle state. Advantageously, compared to embodiments including a symmetric diffraction profile 430, image visibility to the driver may be increased.

[0479] For example, when the display device 100 is tilted at an angle greater than 10° relative to the eyes of viewers 45 and 47, it may be desirable to improve the uniformity of the light output from the display device 100 so that it can be seen by viewers 45 and 47 who are closer to the display device.

[0480] Figure 32A is a schematic diagram illustrating an alternative transmissive electrode configuration 904 in a top view, in which the electrode pitch p varies across the display device 100; Figure 32B is a schematic diagram illustrating the operation of the display device 100 with the alternative transmissive electrode configuratio...

Claims

1. A display device, A spatial light modulator (SLM) is arranged to output spatially modulated light, A display polarizer disposed on one side of the SLM, which is a linear polarizer, and An additional polarizer, which is a linear polarizer, is disposed on the same side as the display polarizer outside the SLM, and is located outside the display polarizer. A switchable diffraction field of view control retarder configuration disposed between the additional polarizer and the display polarizer, comprising a switchable diffraction liquid crystal retarder comprising a liquid crystal material layer and a transparent electrode configuration disposed to drive the liquid crystal material layer, The transparent electrode configuration selectively targets the liquid crystal material layer. The liquid crystal material layer has an orientation structure that introduces a net phase shift uniform across the region of the liquid crystal material layer to light having a predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to the light having the predetermined polarization state, and introduces different net relative phase shifts along the field axis and an inclined axis tilted with respect to the field axis to the orthogonal polarization components of the light having the predetermined polarization state to the switchable diffraction field angle control retarder configuration, in a narrow-angle state, A display device in which the liquid crystal material layer is patterned to be driven to a wide-angle state and a wide-angle state, having an orientation structure that causes the liquid crystal material layer to introduce a spatially varying net phase shift across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby causing the liquid crystal material layer to provide a diffraction effect to the light having the predetermined polarization state.

2. The display device according to claim 1, wherein the transparent electrode configuration is patterned to selectively drive the liquid crystal material layer into an intermediate state having an orientation structure that causes the liquid crystal material layer to introduce a net phase shift uniform across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to the light having the predetermined polarization state, and causing the switchable diffraction field of view angle control retarder configuration to introduce a net relative phase shift that is the same along the field of view axis and the tilt axis to the orthogonal polarization component of the light having the predetermined polarization state.

3. The display device according to claim 1, wherein, in the wide-angle state, the orientation structure of the liquid crystal material layer causes the liquid crystal material layer to introduce a net phase shift that spatially varies in one direction across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby causing the liquid crystal material layer to provide the diffraction effect in one direction.

4. The display device according to claim 1, wherein the permeable electrode configuration comprises at least one isolation electrode array.

5. The display device according to claim 4, wherein the at least one separation electrode array is arranged in one direction, and the separation electrodes extend across the region of the liquid crystal material layer in a direction orthogonal to the one direction.

6. The display device according to claim 5, wherein the separation electrode has a common connection portion.

7. The display device according to claim 6, wherein the common connection portion is formed by a bar located outside the region of the SLM.

8. The display device according to claim 4, wherein the at least one isolation electrode array comprises two sets of mutually mated isolation electrodes.

9. The display device according to claim 8, wherein the at least one separation electrode array comprises two separation electrode arrays on either side of the switchable diffractive liquid crystal retarder, each comprising two inter-mating separation electrode sets.

10. The display device according to claim 8, wherein each set of isolated electrodes has a common connection portion.

11. The display device according to claim 10, wherein the common connection portion of each isolation electrode set is formed by a bar, and the bar is located outside the SLM region on both sides of the liquid crystal material layer.

12. The display device according to claim 4, wherein the separating electrodes are spaced so close together that applying a common voltage to the liquid crystal material layer generates an electric field capable of driving the liquid crystal material layer to the narrow-angle state.

13. The display device according to claim 4, wherein the transparent electrode configuration further comprises a control electrode extending over the entire SLM, the control electrode being disposed outside the separation electrode array and on the same side of the liquid crystal material layer as the separation electrode array.

14. The display device according to claim 4, wherein the transparent electrode configuration further comprises a reference electrode extending over the entire SLM, the reference electrode being disposed on the opposite side of the separation electrode array from the liquid crystal material layer.

15. The display device according to claim 1, further comprising a control system disposed to supply a voltage to the transparent electrode configuration in order to drive the liquid crystal material layer.

16. The control system, In the narrow-angle state, the permeable electrode configuration is supplied with a voltage selected to drive the liquid crystal material layer into the narrow-angle state, and The display device according to claim 15, wherein, in the wide-angle state, the transparent electrode configuration is arranged to supply a voltage selected to drive the liquid crystal material layer to the wide-angle state.

17. The display device according to claim 4, wherein the switchable liquid crystal retarder comprises two surface alignment layers adjacent to and located on both sides of the liquid crystal material layer, and each of the surface alignment layers is arranged to provide alignment of the adjacent liquid crystal material.

18. The display device according to claim 17, wherein the surface alignment layer on one side of the liquid crystal material layer adjacent to the separation electrode array has an alignment component in the plane of the liquid crystal material layer in a direction perpendicular to the one direction.

19. The display device according to claim 17, wherein at least one of the surface alignment layers is arranged to provide homogeneous alignment of the adjacent liquid crystal materials.

20. Each of the surface alignment layers is arranged to provide homogeneous alignment of the adjacent liquid crystal materials. The liquid crystal material layer of the switchable diffractive liquid crystal retarder has a retardation in the range of 500 nm to 900 nm for light with a wavelength of 550 nm. The aforementioned switchable diffraction liquid crystal retarder A passive single-axis retarder having an optical axis perpendicular to the plane of the switchable diffractive liquid crystal retarder and having a retardation in the range of -300 nm to -700 nm for light with a wavelength of 550 nm, or The display device according to claim 17, further comprising any pair of passive single-axis retarders having optical axes in the plane of intersecting switchable diffractive liquid crystal retarders, each having a retardation in the range of 300 nm to 800 nm for light with a wavelength of 550 nm.

21. One of the surface alignment layers is arranged to provide homogeneous alignment of the adjacent liquid crystal materials, and the other of the surface alignment layers is arranged to provide homeotropic alignment of the adjacent liquid crystal materials. The liquid crystal material layer of the switchable diffractive liquid crystal retarder has a retardation range of 700 nm to 2000 nm for light with a wavelength of 550 nm. The aforementioned switchable diffraction liquid crystal retarder A passive single-axis retarder having an optical axis perpendicular to the plane of the switchable diffractive liquid crystal retarder and having a retardation in the range of -300 nm to -1800 nm for light with a wavelength of 550 nm, or The display device according to claim 17, further comprising any pair of passive single-axis retarders having optical axes in the plane of intersecting switchable diffractive liquid crystal retarders, each having a retardation in the range of 300 nm to 1800 nm for light with a wavelength of 550 nm.

22. Each of the surface alignment layers is arranged to provide homeotropic alignment of the adjacent liquid crystal materials. The liquid crystal material layer of the switchable diffractive liquid crystal retarder has a retardation in the range of 500 nm to 1000 nm for light with a wavelength of 550 nm. The aforementioned switchable diffraction liquid crystal retarder A passive single-axis retarder having intersecting optical axes in the plane of the switchable diffractive liquid crystal retarder and having a retardation in the range of -300 nm to -900 nm for light with a wavelength of 550 nm, or The display device according to claim 17, further comprising any pair of passive single-axis retarders having optical axes in the plane of intersecting switchable diffractive liquid crystal retarders, each having a retardation in the range of 300 nm to 800 nm for light with a wavelength of 550 nm.

23. The display device according to claim 1, wherein the switchable diffraction field angle control retarder configuration further comprises at least one passive compensation retarder.

24. The display device according to claim 1, wherein the region of the liquid crystal material layer extends over the entire SLM.

25. The display device according to claim 1, wherein the field of view axis is perpendicular to the plane of the SLM.

26. The display device further comprises a backlight arranged to emit light, The display device according to claim 1, wherein the SLM is a transmissive SLM arranged to receive the light output from the backlight.

27. The display device according to claim 26, wherein the backlight provides brightness at an extreme angle with respect to the normal of the SLM greater than 45 degrees, where the brightness along the normal of the SLM is up to 30%, preferably up to 20%, and most preferably up to 10%.

28. The display polarizer is an input display polarizer disposed on the input side of the SLM. The display device according to claim 26, wherein the additional polarizer and the switchable diffraction field angle control retarder configuration are disposed between the backlight and the SLM.

29. The display device according to claim 1, wherein the display polarizer is an output display polarizer disposed on the output side of the SLM.

30. The display device according to claim 29, wherein the display device further comprises a reflective polarizer disposed between the output display polarizer and the switchable diffraction field angle control retarder configuration, and the reflective polarizer is a linear polarizer.

31. The switchable diffraction field-of-view angle control retarder configuration further comprises a further switchable liquid crystal retarder having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder, The further transparent electrode configuration selectively controls the liquid crystal material layer of the further switchable liquid crystal retarder. The liquid crystal material layer has an orientation structure that introduces a net relative phase shift, which varies along the field axis and the tilt axis, into the orthogonal polarization component of the light having a predetermined polarization state, in the switchable diffractive liquid crystal retarder configuration, in a narrow-angle state, The display device according to any one of claims 1 to 30, wherein the liquid crystal material layer can be driven to a wide-angle state and a wide-angle state, having an orientation structure that introduces a net relative phase shift, which is the same along the viewing axis and the tilt axis, into the orthogonal polarization component of the light having a predetermined polarization state, to the switchable diffractive liquid crystal retarder configuration.

32. A further additional polarizer, which is a linear polarizer, is located on the same side as the additional polarizer in the SLM and is disposed either a) between the display polarizer and the switchable diffraction field angle control retarder configuration, or b) outside the additional polarizer. a) When the further additional polarizer is disposed between the display polarizer and the display polarizer, or b) When the further additional polarizer is disposed outside the additional polarizer, the further additional liquid crystal retarder configuration is disposed between the additional polarizer and the additional additional polarizer, The further switchable liquid crystal retarder configuration comprises a further switchable liquid crystal retarder having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder configuration, The further transparent electrode configuration selectively controls the liquid crystal material layer of the further switchable liquid crystal retarder. The liquid crystal material layer has an orientation structure that introduces a net relative phase shift, which varies along the viewing axis and the tilt axis, into the orthogonal polarization component of the light having a predetermined polarization state, into the further switchable liquid crystal retarder configuration, in a narrow-angle state, The display device according to any one of claims 1 to 30, wherein the liquid crystal material layer can be driven to a further switchable liquid crystal retarder to a wide-angle state and a wide-angle state, having an orientation structure that causes the retarder to introduce a net relative phase shift, which is the same along the viewing axis and the tilt axis, into the orthogonal polarization component of the light having a predetermined polarization state.

33. The display device further comprises a backlight arranged to emit light, The SLM is a transmissive SLM arranged to receive the light output from the backlight, The display polarizer is either a) an input polarizer or b) an output polarizer. The display device further comprises a further display polarizer which is either a) an output polarizer when the display polarizer is an input polarizer, or b) an input polarizer when the display polarizer is an output polarizer. The display device further comprises an additional polarizer disposed either a) on the output side of the output polarizer when the display polarizer is an input polarizer, or b) between the input polarizer and the backlight when the display polarizer is an output polarizer. The display device further comprises a further switchable liquid crystal retarder configuration disposed between the further additional polarizer and the further display polarizer, The further switchable liquid crystal retarder configuration comprises a further switchable liquid crystal retarder having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the further switchable liquid crystal retarder, The further transparent electrode configuration selectively controls the liquid crystal material layer of the further switchable liquid crystal retarder. The liquid crystal material layer has an orientation structure that introduces a net relative phase shift, which varies along the viewing axis and the tilt axis, into the orthogonal polarization component of the light having a predetermined polarization state, into the further switchable liquid crystal retarder configuration, in a narrow-angle state, The display device according to any one of claims 1 to 30, wherein the liquid crystal material layer can be driven to a wide-angle state and a wide-angle state, having an orientation structure that causes the further switchable liquid crystal retarder configuration to introduce a net relative phase shift, which is the same along the viewing axis and the tilt axis, into the orthogonal polarization component of the light having a predetermined polarization state.

34. The aforementioned further switchable liquid crystal retarder is a switchable diffractive liquid crystal retarder, In the aforementioned narrow-angle state, the liquid crystal material layer has an orientation structure that introduces a net phase shift uniform across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to the light having the predetermined polarization state. The display device according to claim 31, wherein, in the wide-angle state, the liquid crystal material layer has an orientation structure that causes the liquid crystal material layer to introduce a net phase shift that varies spatially across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby causing the liquid crystal material layer to provide a diffraction effect to the light having the predetermined polarization state.

35. The display device according to claim 31, wherein the further switchable liquid crystal retarder is a switchable non-diffractive liquid crystal retarder, and in each of the narrow-angle state and the wide-angle state, the liquid crystal material layer has an orientation structure that causes the liquid crystal material layer to introduce a net phase shift to the light having the predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to the light having the predetermined polarization state.

36. The switchable diffraction field of view angle control retarder configuration further comprises a switchable diffractive liquid crystal element having a liquid crystal material layer, and a further transparent electrode configuration disposed to drive the liquid crystal material layer of the switchable diffractive liquid crystal element, The further transparent electrode configuration selectively controls the liquid crystal material layer of the further switchable diffractive liquid crystal retarder. The liquid crystal material layer has an orientation structure that introduces a net phase shift uniform across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby preventing the liquid crystal material layer from providing a diffraction effect to the light having the predetermined polarization state, thus resulting in a non-diffraction state. The display device according to any one of claims 1 to 30, wherein the liquid crystal material layer is patterned to be driven to a wide-angle state and to a wide-angle state, having an orientation structure that causes the liquid crystal material layer to introduce a spatially varying net phase shift across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby causing the liquid crystal material layer to provide a diffraction effect to the light having the predetermined polarization state.

37. A display device, A spatial light modulator (SLM) is arranged to output spatially modulated light, A display polarizer disposed on one side of the SLM, which is a linear polarizer, and An additional polarizer, which is a linear polarizer, is disposed on the same side as the display polarizer outside the SLM, and is located outside the display polarizer. A switchable non-diffraction liquid crystal retarder configuration disposed between the additional polarizer and the display polarizer, comprising a switchable non-diffraction liquid crystal retarder having a liquid crystal material layer, and a transparent electrode configuration that selectively controls the liquid crystal material layer, The liquid crystal material layer introduces a net relative phase shift, which varies along the field axis and an inclined axis tilted to the field axis, into the orthogonal polarization component of light having a predetermined polarization state, in the switchable non-diffraction liquid crystal retarder configuration, in a narrow-angle state, The liquid crystal material layer comprises a transparent electrode configuration arranged to drive the switchable non-diffraction liquid crystal retarder configuration to a wide-angle state, which introduces a net relative phase shift that is the same along the viewing axis and the tilt axis into the orthogonal polarization component of the light having a predetermined polarization state, and A display device comprising a switchable optical dispersion configuration arranged in series with the SLM, the display polarizer, the additional polarizer, and the switchable non-diffractive liquid crystal retarder configuration, the switchable optical dispersion configuration being switchable between a non-dispersive state that does not provide light dispersion and a dispersed state that provides light dispersion.

38. The display device according to claim 37, wherein the switchable light dispersion configuration provides unidirectional dispersion of the dispersed light state across the region of the liquid crystal material layer.

39. The display device according to claim 37, further comprising a control system disposed to supply a voltage to the transparent electrode configuration in order to drive the liquid crystal material layer, and disposed to control the switchable light dispersion configuration.

40. The control system, In the narrow-angle state of the aforementioned display device, A voltage is supplied to the transparent electrode configuration to drive the liquid crystal material layer of the switchable non-diffractive liquid crystal retarder to its narrow-angle state. Switching the switchable optical dispersion configuration to the non-dispersive state, In the wide-angle state of the aforementioned display device, A voltage is supplied to the transparent electrode configuration to drive the liquid crystal material layer of the switchable non-diffractive liquid crystal retarder to its wide-angle state. The display device according to claim 39, which is arranged to switch the switchable optical dispersion configuration to the dispersion state.

41. The display device according to claim 37, wherein the switchable optical dispersion configuration is a diffraction element that provides light dispersion by diffraction in the dispersion state.

42. The switchable optical dispersion configuration is Liquid crystal material layer, A switchable diffractive liquid crystal element comprising a transparent electrode configuration arranged to drive the liquid crystal material layer, The transparent electrode configuration selectively targets the liquid crystal material layer. The liquid crystal material layer has an orientation structure that causes the liquid crystal material layer to introduce a net phase shift uniform across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby preventing the liquid crystal material layer from providing dispersion of the light having the predetermined polarization state, and the non-diffractive state corresponds to the non-dispersive state of the switchable light dispersion configuration, The display device according to claim 41, wherein the liquid crystal material layer is patterned to be driven to a diffraction state corresponding to the dispersion state of the switchable light dispersion configuration, having an orientation structure that causes the liquid crystal material layer to introduce a spatially varying net phase shift across the region of the liquid crystal material layer to the light having the predetermined polarization state, thereby causing the liquid crystal material layer to provide dispersion of the light due to the diffraction effect.

43. The display device according to claim 37, wherein the switchable light dispersion configuration is a refractive element that provides light dispersion by refraction in the dispersion state.

44. The switchable optical dispersion configuration is A birefringent layer of a birefringent material having an ordinary refractive index and an extraordinary refractive index, An isotropic layer of an isotropic material having an interface with the birefringent layer, wherein the isotropic material has a refractive index equal to the ordinary refractive index or the extraordinary refractive index of the birefringent material, and the surface of the interface has a dispersive surface relief, The display device according to claim 37, further comprising a polarization control element disposed to selectively control the polarization of light passing through the switchable optical dispersion configuration between a first polarization state experiencing the ordinary refractive index in the birefringent layer and a second polarization state experiencing the extraordinary refractive index in the birefringent layer.

45. The display device according to claim 44, wherein the surface relief is dispersed by refraction.

46. The display device according to claim 45, wherein the surface relief is a lens profile, a prism profile, a random profile, or a designed profile.

47. The display device according to claim 44, wherein the surface relief is dispersion due to diffraction.

48. The display device according to claim 37, wherein the switchable light dispersion configuration is disposed between the display polarizer and the additional polarizer.

49. The display device further comprises a backlight arranged to emit light, The SLM is a transmissive SLM arranged to receive the light output from the backlight, The display device according to claim 48, wherein the display polarizer is an input display polarizer disposed on the input side of the SLM.

50. The display device according to claim 37, wherein the switchable light dispersion configuration is located outside the additional polarizer and on the same side as the display polarizer in the SLM.

51. The display device further comprises a backlight arranged to emit light, The SLM is a transmissive SLM arranged to receive the light output from the backlight, The display polarizer is an input display polarizer disposed on the input side of the SLM. The display device according to claim 50, wherein the switchable light dispersion configuration, the additional polarizer, and the switchable non-diffractive liquid crystal retarder configuration are disposed between the backlight and the SLM.

52. The display device further comprises a backlight arranged to emit light, The display device according to claim 37, wherein the SLM is a transmissive SLM arranged to receive the light output from the backlight.

53. The display polarizer is an output display polarizer disposed on the output side of the SLM. The display device according to claim 52, wherein the switchable light dispersion configuration is disposed between the backlight and the SLM.

54. The display device according to claim 53, further comprising a reflective polarizer disposed between the output display polarizer and the switchable non-diffractive liquid crystal retarder configuration, wherein the reflective polarizer is a linear polarizer.

55. The display device according to claim 51, wherein the backlight provides brightness at an extreme angle with respect to the normal of the SLM greater than 45 degrees, where the brightness along the normal of the SLM is up to 30%, preferably up to 20%, and most preferably up to 10%.

56. The display device according to claim 37, wherein the switchable liquid crystal retarder comprises two surface alignment layers disposed adjacent to and on both sides of the liquid crystal material layer.

57. The display device according to any one of claims 37 to 56, wherein the switchable non-diffractive liquid crystal retarder configuration further includes at least one passive compensation retarder.

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