Directional display device

Abstract

The invention relates to a directional display device. A switchable privacy display includes a transmit SLM, a parallax barrier, a switchable LC retarder, and a passive retarder disposed between parallel output polarizers. In a privacy mode, on-axis light from the SLM is directed losslessly, while the parallax barrier and retarder layer cooperate to increase the VSL to an off-axis snooper. The display may be rotated to enable privacy operations in both lateral and longitudinal orientations. In common mode, LC delay is adjusted such that off-axis brightness increases, thus increasing image visibility for multiple users. The display may also switch between daytime and nighttime operations, e.g., for use in an automotive environment. A low reflectivity emissive display for ambient lighting includes an SLM having emissive pixels, an absorptive parallax barrier, and a hyperspectral leakage optical isolator. Front light from the pixels is directed with increased transmittance efficiency while ambient light is strongly absorbed.

Description

[0001] This application is a divisional application of the invention patent application with the Chinese patent application number 202080059812.7 and the invention title "Directional Display Device", which is the Chinese national phase entry of the PCT international application PCT / US2020 / 040686 filed on July 2, 2020. Technical Field

[0002] The present disclosure generally relates to illumination from a light modulation device, and more particularly, to an optical stack for providing control of illumination used in displays including privacy displays and night displays. Background Art

[0003] A privacy display provides image visibility to a primary user (typically located in an on-axis position) and reduces the visibility of image content to a snoop (typically located in an off-axis position). The privacy function can be provided by a microshutter optical film that transmits some light in the on-axis direction from the display and low brightness in the off-axis position. However, such films have high losses for front illumination, and due to pixel jitter of the spatial light modulator, the microshutters may cause Moiré artefacts. The pitch of the microshutters may need to be selected for the panel resolution, increasing inventory and cost.

[0004] A switchable privacy display can be provided by controlling off-axis optical output.

[0005] Control can be provided by means of brightness reduction, such as by means of a switchable backlight for a liquid crystal display (LCD) spatial light modulator. Display backlights typically employ waveguides and edge-emitting sources. Some imaging directional backlights have the additional ability to direct illumination through the display panel to the viewing window. An imaging system can be formed between multiple sources and corresponding window images. An example of an imaging directional backlight is an optical valve that can employ a folded optical system and can thus also be an example of a folded imaging directional backlight. Light can propagate through the optical valve with substantially no loss in one direction, while light propagating in the reverse direction can be extracted by reflecting inclined facets, as described in U.S. Patent No. 9,519,153, which is incorporated herein by reference in its entirety. Summary of the Invention

[0006] According to a first aspect of the present disclosure, there is provided a display device including: an emission spatial light modulator including a pixel array disposed in a pixel layer; a parallax barrier forming a hole array, wherein the parallax barrier is spaced from the pixel layer by a parallax distance along an axis normal to the plane of the pixel layer; and each pixel is aligned with a hole. The parallax barrier can direct light from each pixel into a common viewing window. Advantageously, a full-resolution image with a low reflectivity and reduced off-axis brightness can be achieved.

[0007] Along the direction in which the holes are closest, the holes have a width a and the pixels have a width w, which can satisfy the requirement a≥w. Advantageously, full brightness can be achieved in at least one viewing direction.

[0008] Along the direction in which the holes are closest, the holes have a width a, the pixels have a pitch p and the pixels have a width w, which can satisfy the requirement a≤(p - w / 2). Advantageously, for at least one viewing direction, the off-axis brightness can be reduced to at most 50%.

[0009] The parallax barrier has a spacing d from the pixels and the pixels have a pitch p along the direction in which the holes are closest, and the material between the parallax barrier and the pixels has a refractive index n, which can satisfy the requirement The direction of the minimum brightness can be at least 45 degrees to advantageously achieve the desired off-axis brightness for a privacy display.

[0010] The parallax barrier has a spacing d from the pixels and the holes have a width a along the direction in which the holes are closest, and the material between the parallax barrier and the pixels has a refractive index n, which can satisfy the requirement Providing at most 50% brightness at a polar angle of 90 degrees to advantageously achieve the desired off-axis brightness for a privacy display.

[0011] The parallax barrier has a spacing d from the pixels and the holes have a width a along the direction in which the holes are closest, and the material between the parallax barrier and the pixels has a refractive index n, which can satisfy the requirement Providing at most 50% brightness at a polar angle of 60 degrees to advantageously achieve the desired off-axis brightness for a privacy display.

[0012] The pitch p' along the direction in which the holes are closest is less than the pitch p of the corresponding aligned pixels along the direction in which the pixels are closest; and the viewing window is formed at a viewing window plane on the output side of the spatial light modulator.

[0013] The pitch P along the direction in which the holes are closest is less than the pitch p of the corresponding aligned pixels along the direction in which the pixels are closest; and the viewing window is formed at a viewing window plane on the output side of the spatial light modulator.

[0014] The pitch p' along the direction closest to the holes can be smaller than the pitch p of the corresponding aligned pixels along the direction closest to the pixels; and the viewing window can be formed at the viewing window plane on the output side of the spatial light modulator. Advantageously, it increases the brightness uniformity for front display users.

[0015] The parallax barrier can form a two-dimensional array of holes, with each pixel aligned with a corresponding hole. Reduction of brightness in the side and elevation angles can be achieved. Advantageously, it can provide lateral and longitudinal privacy operations for a privacy display. The display reflectivity can be reduced and the display efficiency in the front direction can be increased.

[0016] The pixels can be arranged in columns and rows, the direction closest to the holes can be at 45 degrees with respect to the electric vector transmission direction of the output linear polarizer; and each pixel can have a light-emitting region in the shape of a square, where the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer. The holes can have a square shape, where the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer, or the holes can have a circular shape. Advantageously, uniform brightness attenuation and brightness reduction at high polar angles can be achieved along the lateral and elevation azimuth directions.

[0017] For at least some of the pixels, the light-emitting region can include a light-emitting sub-region and a non-light-emitting sub-region. For red, green, and blue pixels, the area ratio of the light-emitting sub-region to the non-light-emitting region may be different. The color pixels can be driven with a similar drive voltage to achieve an output brightness that matches those provided in a display without a parallax barrier. Advantageously, the control and driver electronics reduce complexity and increase efficiency.

[0018] The parallax barrier can form a one-dimensional array of holes, with the pixels arranged in columns, and each pixel column aligned with a corresponding hole. Modifications to the pixel arrangement can be reduced, thereby reducing costs. Each pixel can have a light-emitting region that extends in the direction in which the holes extend; the widths of the red, green, and blue light-emitting regions can be the same for each pixel; and the heights of the light-emitting regions for the red, green, and blue light-emitting pixels can be different. The display can be conveniently rotated in one direction about an axis to advantageously provide a comfortable viewing height for front observers. The yield and cost of aligning the parallax barrier can be reduced.

[0019] The parallax barrier can be arranged to absorb the light incident thereon. Display reflection can be reduced, thereby advantageously increasing the display contrast in a brightly lit environment.

[0020] The absorption rate of the parallax barrier region between the holes can be less than 100% and can be greater than 80%, preferably greater than 90% and more preferably greater than 95%. Compared with a parallax barrier having a 100% absorption rate in the absorption region, the off-axis image visibility of the display can be increased.

[0021] The display device is for ambient lighting, and the parallax barrier absorbs at least some of the ambient lighting reflected from the pixel layer and transmitted through the holes.

[0022] The display device can be used for ambient lighting, and the parallax barrier can absorb at least some of the ambient lighting reflected from the pixel layer and transmitted through the holes. Reflection is reduced, thereby advantageously increasing the observed image contrast. The display device can have one or more additional layers between the pixel layer and the parallax barrier, where the pixels, the one or more additional layers, and the parallax barrier can be formed as a monolithic stack. Advantageously, the separation of the pixel layer and the parallax barrier layer can have high stability during the applied mechanical force.

[0023] The one or more additional layers can include at least one light-transmissive inorganic layer arranged to provide a barrier against water and oxygen. The parallax barrier can include at least one light-transmissive inorganic material arranged to provide a barrier against water and oxygen. The parallax barrier can be arranged between the pixel layer and the at least one light-transmissive inorganic layer, which can be arranged to provide a barrier against water and oxygen. Advantageously, the lifespan of the display can be increased.

[0024] The output polarizer can be arranged on the output of the spatial light modulator, and the output polarizer is a linear polarizer; and the reflection control quarter-wave retarder can be arranged between the output polarizer and the spatial light modulator. Advantageously, reflection from the pixel layer can be reduced.

[0025] The parallax barrier can be arranged between the pixel layer and the reflection control quarter-wave retarder. Advantageously, a small gap between the pixel layer and the parallax barrier can be conveniently achieved.

[0026] The display device can further include an additional polarizer arranged on the output side of the output polarizer, and the additional polarizer is a linear polarizer; and at least one polarity control retarder arranged between the output polarizer and the additional polarizer. A privacy display with a high level of visual security can be advantageously provided.

[0027] When crossed with a conceptual polarizer of the same material, the transmittance of at least one of the output polarizer and the additional polarizer for wavelengths from 520 nm to 560 nm can be less than the transmittance for wavelengths from 450 nm to 490 nm. The transmittance for wavelengths from 450 nm to 490 nm can be greater than 1%, preferably greater than 2% and most preferably greater than 3%; and the transmittance for wavelengths from 520 nm to 560 nm can be less than 3%, preferably less than 2% and most preferably less than 1%. Compared with a broadband absorption polarizer, the transmittance of the display can be increased. Advantageously, the display efficiency is increased. For blue wavelengths, the transmittance may be relatively large. Advantageously, the lifespan of the display can be increased.

[0028] At least one polarization control retarder may further comprise at least one passive retarder.

[0029] At least one polarization control retarder may be capable of simultaneously: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the output polarizer along the axis normal to the plane of the at least one polarization control retarder, and introducing a relative phase shift to the orthogonal polarization components of the light transmitted by the reflection polarizer along the axis inclined to the normal of the plane of the at least one polarization control retarder. The at least one passive retarder may comprise a retarder having an optical axis perpendicular to the plane of the retarder, and the at least one passive retarder has a retardation for light with a wavelength of 550 nm in the range of -150 nm to -900 nm, preferably in the range of -200 nm to -500 nm, and most preferably in the range of -250 nm to -400 nm. A larger off-axis polarization region with reduced brightness can be achieved. Advantageously, for many snooper positions, the visual safety level is high.

[0030] At least one retarder may comprise: a first quarter-wave plate and a second quarter-wave plate arranged between an additional polarizer and an output polarizer, the first quarter-wave plate being arranged on the input side of the second quarter-wave plate and being arranged to convert the polarization state of linearly polarized light transmitted by the output polarizer on its input side into a circularly polarized state, and the second quarter-wave plate on the output side being arranged to convert the polarization state of circularly polarized light incident thereon into a linearly polarized state transmitted by the additional polarizer on its output side; and at least one retarder arranged between the pair of quarter-wave plates. The retarder arranged between the pair of quarter-wave plates may comprise a retarder having an optical axis perpendicular to the plane of the retarder, and the at least one passive retarder has a retardation for light with a wavelength of 550 nm in the range of -150 nm to -500 nm, preferably in the range of -200 nm to -400 nm, and most preferably in the range of -250 nm to -350 nm. A rotationally symmetric polarization brightness reduction curve can be provided. Advantageously, the privacy display can be operated in both transverse and longitudinal modes. For a snooper looking down from above the user's head, a high visual safety can be obtained.

[0031] At least one polarization control retarder may include a switchable liquid crystal (LC) retarder including a liquid crystal material layer and electrodes arranged to apply a voltage to switch the liquid crystal material layer. The at least one polarization control retarder may be arranged to simultaneously perform the following in a first switchable state of the switchable liquid crystal retarder: not introducing a net relative phase shift to an orthogonal polarization component of light transmitted by a reflective polarizer along an axis normal to the plane of the at least one polarization control retarder, and introducing a net relative phase shift to an orthogonal polarization component of light transmitted by the reflective polarizer along an axis inclined to the normal of the plane of the at least one polarization control retarder; and simultaneously perform the following in a second switchable state of the switchable liquid crystal retarder: not introducing a net relative phase shift to an orthogonal polarization component of light transmitted by the reflective polarizer along an axis normal to the plane of the at least one polarization control retarder, and not introducing a net relative phase shift to an orthogonal polarization component of light transmitted by the reflective polarizer along an axis inclined to the normal of the plane of the at least one polarization control retarder. Advantageously, the display may be switched between a privacy operation mode and a public operation mode. Extend regions that provide high visual security to off-axis snoops in the privacy mode and high image visibility to off-axis users in the public mode. Frontal users see the image with high efficiency and high image visibility in both modes.

[0032] The display device may further include a reflective polarizer disposed between the output polarizer and the at least one polarization control retarder, and the reflective polarizer is a linear polarizer arranged to transmit a polarization component of the same linear polarization as the output polarizer. In the privacy operation mode, the privacy display may have a high reflectivity. In the privacy mode, the visual security level may be maintained for various ambient lighting conditions. In the public mode, the display reflectivity is reduced to achieve high image visibility for various viewing positions.

[0033] The output polarizer may be a reflective polarizer. Advantageously, the display efficiency may be increased. The display reflectivity may be reduced compared to a display without a parallax barrier.

[0034] The pixel may include a light-emitting diode. Advantageously, high luminous efficiency, high contrast, and high brightness may be achieved through a wide color gamut.

[0035] The light-emitting diode may be an organic light-emitting diode including an organic light-emitting material. Advantageously, a thin and robust display may be provided. For each of the red, green, and blue light-emitting regions, the thickness of the light-emitting material may be different. For all colors, the pixel size may be nominally the same such that color attenuation is substantially the same for all polar angles. The cost and complexity of the driving electronics may be reduced.

[0036] At least some of the light-emitting diodes may be inorganic micro light-emitting diodes. Advantageously, extremely high brightness can be achieved. A barrier layer for water and oxygen can be omitted, thereby advantageously reducing costs. A larger area can be provided between the micro LEDs. Advantageously, the reflectivity of the pixel layer can be reduced. A leakage polarizer can be provided for a switchable privacy display to achieve increased output efficiency.

[0037] The holes have an absorption rate, and at the edges of the holes, the absorption rate may have a transmittance gradient, and the transmittance gradient has a transmittance gradient width greater than 1 micron, preferably greater than 2 microns and more preferably greater than 3 microns. Diffraction effects can be reduced to advantageously achieve increased uniformity. The brightness attenuation curve can have an increased polar width to improve the uniformity of off-axis use.

[0038] A hole array may be formed on a touch sensor electrode array. At least one absorption region of the parallax barrier may include the touch sensor electrode array. Advantageously, a low-reflectivity touch electrode can be conveniently provided.

[0039] At least some of the holes in the parallax barrier may include color filters. The holes in the parallax barrier include an array of red, green, and blue color filters. Advantageously, cross-interference between adjacent pixels can be reduced. The color gamut can be increased.

[0040] The display device may not have a polarizer disposed on the output side of the spatial light modulator.

[0041] According to a second aspect of the present disclosure, a method of forming a display device is provided. The method includes the steps of: forming an emission pixel array on a backplane by guiding an emission material through a fine metal mask, and the fine metal mask forms an encapsulation layer including at least one transparent inorganic layer on the emission pixel array; forming a parallax barrier including a hole array on the surface of the encapsulation layer by guiding a light absorption material through a fine metal. Advantageously, the same equipment used to form an OLED display can be used to form the parallax barrier, thereby reducing costs.

[0042] According to a third aspect of the present disclosure, a method of forming a display device is provided. The method includes the steps of: forming an emission pixel array on a backplane by guiding an emission material through a fine metal mask, and the fine metal mask forms an encapsulation layer including at least one transparent inorganic layer on the emission pixel array; forming a parallax barrier including a hole array on the surface of the encapsulation layer by photolithographic patterning. Advantageously, an accurate parallax barrier can be conveniently aligned with the pixel layer.

[0043] According to a fourth aspect of the present disclosure, there is provided a reflectivity control display device for ambient lighting, the reflectivity control display device including the display device of the first aspect, wherein the parallax barrier absorbs at least some of the ambient lighting. Advantageously, the output efficiency can be increased while maintaining or reducing the display reflectivity.

[0044] The parallax barrier absorbs at least some of the ambient lighting reflected from the pixel layer.

[0045] The present disclosure also provides a method of forming a display device, the method including: forming an array of emissive pixels on a backplane by guiding emissive material through a fine metal mask; forming an encapsulation layer on the array of emissive pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on a surface of the encapsulation layer by guiding light-absorbing material through a fine metal mask.

[0046] The present disclosure also provides a method of forming a display device, the method including: forming an array of emissive pixels on a backplane by guiding emissive material through a fine metal mask; forming an encapsulation layer on the array of emissive pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on a surface of the encapsulation layer by photolithographic patterning.

[0047] The pixels have a pitch p in a direction closest to the holes, the material between the parallax barrier and the pixels has an overall refractive index n, and the encapsulation layer has a thickness d satisfying the requirement thereof.

[0048] The holes have a width a in a direction closest to the holes, the material between the parallax barrier and the pixels has an overall refractive index n, and the encapsulation layer has a thickness d satisfying the requirement thereof.

[0049] The present disclosure also provides a method of forming a reflectivity control display device, the method including: forming an array of emissive pixels on a backplane by guiding emissive material through a fine metal mask; forming an encapsulation layer on the array of emissive pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on a surface of the encapsulation layer by guiding light-absorbing material through a fine metal mask. The present disclosure also provides a method of forming a reflectivity control display device, the method including: forming an array of emissive pixels on a backplane by guiding emissive material through a fine metal mask; forming an encapsulation layer on the array of emissive pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on a surface of the encapsulation layer by photolithographic patterning.

[0050] The holes have a width a in a direction closest to the holes, the material between the parallax barrier and the pixels has an overall refractive index n, and the encapsulation layer has a thickness d satisfying the requirement The thickness d.

[0051] Any aspect of the present disclosure can be applied in any combination.

[0052] Embodiments of the present disclosure can be used in various optical systems. The embodiments can be included or used in conjunction with a variety of projectors, projection systems, optical components, displays, microdisplays, computer systems, processors, self - contained projector systems, vision and / or audio - visual systems, and electrical and / or optical devices. Various aspects of the present disclosure can actually be used with any device related to optical and electrical devices, optical systems, presentation systems, or any device that can contain any type of optical system. Thus, embodiments of the present disclosure can be used in optical systems, devices for visual and / or optical display, visual peripherals, etc., as well as in a variety of computing environments.

[0053] Before entering into the detailed disclosed embodiments, it should be understood that the present disclosure is not limited to the details of the specific arrangements shown in its application or creation, as the present disclosure is capable of having other embodiments. In addition, aspects of the present disclosure can be presented in different combinations and arrangements to define unique embodiments in terms of their own rights. Moreover, the terms used herein are for the purpose of description and not limitation.

[0054] By reading the entire content of the present disclosure, these and other advantages and features of the present disclosure will become apparent to those of ordinary skill in the art. BRIEF DESCRIPTION OF THE DRAWINGS

[0055] Embodiments are illustrated by way of example in the drawings, where like reference numerals indicate like parts, and wherein:

[0056] Figure 1A is a schematic side - perspective view of a switchable privacy display for ambient lighting, the switchable privacy display including an OLED emissive spatial light modulator, a parallax barrier, an output polarizer, and a reflective control quarter - wave retarder, a reflective polarizer, a switchable polarity control retarder, and an additional polarizer disposed on the output side of the spatial light modulator;

[0057] Figure 1B is a front - view illustration of Figure 1A the alignment of the optical layers in the optical stack of

[0058] Figure 2A and 2B is a side - view illustration of the parallax barrier for a Figure 1A -B privacy display;

[0059] Figure 3A is a side - perspective view illustration of the parallax barrier for non - pupil output and Figure 1ASchematic diagram of alignment of pixels;

[0060] Figure 3B is a side perspective view illustrating a parallax barrier for pupil output and Figure 1A Schematic diagram of alignment of pixels;

[0061] Figure 4 is a top view illustrating the arrangement of uniform emission pixels and eye point positions for various polar viewing angles;

[0062] Figure 5 is a top view illustrating the arrangement of structured emission pixels and eye point positions for various polar viewing angles;

[0063] Figure 6 is a side view illustrating the structure of a spatial light modulator and an aligned parallax barrier including an upper incident reduction layer;

[0064] Figure 7 is a side view illustrating the structure of a spatial light modulator and an aligned parallax barrier including a glass cover layer;

[0065] Figure 8A , 8B and 8C are schematic diagrams illustrating the variation of parallax barrier transmittance with the position of various parallax barrier structures;

[0066] Figure 9 is a perspective side view illustrating the arrangement of a switchable retarder in a common mode, where the switchable retarder includes a horizontally aligned switchable LC layer and a crossed A - plate polarity control retarder;

[0067] Figure 10A is a side view illustrating the propagation of output light from a spatial light modulator through Figure 1A an optical stack;

[0068] Figure 10B is a side view illustrating the propagation of light rays from an ambient light source through Figure 1A an optical stack;

[0069] Figure 10C is a side view illustrating the propagation of output light from a spatial light modulator through Figure 1A an optical stack in a privacy operation mode;

[0070] Figure 10D is a side view illustrating the propagation of light rays from an ambient light source through Figure 1A an optical stack in a privacy operation mode;

[0071] Figure 11A isFigure 1A Component weight ratios and output polar plot arrays of the arrangement, including spatial light modulator luminance, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode luminance, privacy mode luminance, and polar plots for a visual safety level of 1.0 lux / nit ratio;

[0072] Figure 11B is Figure 11A Component weight ratios and output line graph arrays of the arrangement, including line graphs at azimuth angles of 0 degrees (east direction), 90 degrees (north direction), 45 degrees (northeast direction), and 225 degrees (southwest direction);

[0073] Figure 11C is for a lux / nit ratio of 0.25 Figure 11A Polar graphs and linear polar graphs of illustrative embodiments of -B;

[0074] Figure 12A is for an illustrative arrangement in which the parallax barrier is removed Figure 1A Component weight ratios and output polar plot arrays of the arrangement, including spatial light modulator luminance, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode luminance, privacy mode luminance, and polar plots of the visual safety level;

[0075] Figure 12B is Figure 12A Component weight ratios and output line graph arrays of the arrangement, including line graphs at azimuth angles of 0, 90, 45, and 225 degrees;

[0076] Figure 13A is for an illustrative arrangement in which the switchable retarder is removed Figure 1A Component weight ratios and output polar plot arrays of the arrangement, including spatial light modulator luminance, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode luminance, privacy mode luminance, and polar plots of the visual safety level;

[0077] Figure 13B is Figure 13A Component weight ratios and output line graph arrays of the arrangement, including line graphs at azimuth angles of 0, 90, 45, and 225 degrees;

[0078] Figure 14 is a schematic diagram showing the reflection of ambient light in the Figure 1A display in a side view;

[0079] Figure 15 is a schematic diagram showing the variation of output luminance with the wavelength of the broadband absorption polarizer and the leakage absorption polarizer;

[0080] Figure 16A It is a schematic diagram showing the variation of the transmittance of a polarizer with the wavelength of a broadband absorption polarizer and a leakage absorption polarizer, and the spectral output of red, green, and blue emission pixels with respect to the transmitted light Figure 14 ;

[0081] Figure 16B It is a schematic diagram showing the variation of the reflectance with the wavelength of a broadband absorption polarizer and a leakage absorption polarizer, and the spectral output of red, green, and blue emission pixels with respect to the reflected light Figure 14 ;

[0082] Figure 17A It is a schematic diagram in side perspective showing a switchable privacy display for ambient lighting, including a micro-LED emitting spatial light modulator, a parallax barrier, an output polarizer, and a reflection control quarter-wave retarder, a passive polarization control retarder, a reflective polarizer, a switchable polarization control retarder, and an additional polarizer arranged on the output side of the spatial light modulator

[0083] Figure 17B It is a schematic diagram in front view showing Figure 17A the alignment of the optical layers in the optical stack of

[0084] Figure 17C It is a schematic diagram in top view showing the arrangement of micro-LED emission pixels and eye point positions for various polarization viewing angles

[0085] Figure 17D It is a schematic diagram in side perspective showing the passive polarization control retarder arranged between the output polarizer and the reflective polarizer

[0086] Figure 18A It is a schematic diagram in side view showing the structure of the spatial light modulator and the alignment parallax barrier including the vignetting parallax barrier holes

[0087] Figure 18B , 18C and 18D are schematic diagrams showing the variation of the parallax barrier transmittance with the position of various parallax barrier structures

[0088] Figure 19A It is Figure 17A a polar plot array of the component weights and outputs of the arrangement of

[0089] Figure 19B It is Figure 19AArray of linear graphs of component weights and outputs of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees;

[0090] Figure 19C is Figure 17A Array of polar graphs of component weights and outputs of the arrangement, including polar graphs of spatial light modulator brightness, parallax barrier transmittance, passive polarization control retarder, switchable retarder transmittance, switchable retarder reflectance, common mode brightness, privacy mode brightness, and visual safety level;

[0091] Figure 19D is Figure 19C Array of linear graphs of component weights and outputs of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees;

[0092] Figure 20A is for an illustrative arrangement in which the parallax barrier is removed Figure 17A Array of polar graphs of component weights and outputs of the arrangement, including polar graphs of spatial light modulator brightness, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode brightness, privacy mode brightness, and visual safety level;

[0093] Figure 20B is Figure 20A Array of linear graphs of component weights and outputs of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees;

[0094] Figure 21A is for an illustrative arrangement in which the switchable retarder and passive polarization control retarder are removed and the parallax barrier provides transmittance in the light absorption region Figure 17A Array of polar graphs of component weights and outputs of the arrangement; including polar graphs of spatial light modulator brightness, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode brightness, privacy mode brightness and visual safety level;

[0095] Figure 21B is Figure 21A Array of linear graphs of component weights and outputs of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees;

[0096] Figure 21C is for an illustrative arrangement in which the switchable retarder and passive polarization control retarder are removed and the parallax barrier does not provide transmittance in the light absorption region Figure 17AComponent ratios of the arrangement and an array of output polar plots; polar plots including spatial light modulator brightness, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode brightness, privacy mode brightness, and visual safety level;

[0097] Figure 21D is Figure 21A An array of component ratios of the arrangement and output line graphs, including line graphs at azimuth angles of 0, 90, 45, and 225 degrees;

[0098] Figure 22A A diagram showing the arrangement of the switchable retarder in privacy mode in perspective side view, where the switchable retarder includes a switchable LC layer with horizontal alignment arranged between C-plate passive polarization control retarders;

[0099] Figure 22B A diagram showing the arrangement of the switchable retarder in common mode in perspective side view, where the switchable retarder includes a switchable LC layer with horizontal alignment arranged between C-plate passive polarization control retarders;

[0100] Figure 23A A schematic diagram showing the arrangement of the retarder layer of a 270-degree super twisted switchable liquid crystal retarder arranged between quarter-wave plates and included between parallel polarizers in perspective side view;

[0101] Figure 23B is Figure 23A An array of component ratios of the arrangement and output polar plots, including polar plots of spatial light modulator brightness, parallax barrier transmittance, switchable retarder transmittance, switchable retarder reflectance, common mode brightness, privacy mode brightness, and visual safety level;

[0102] Figure 23C is Figure 23B An array of component ratios of the arrangement and output line graphs, including line graphs at azimuth angles of 0, 90, 45, and 225 degrees;

[0103] Figure 24A A schematic diagram showing the brightness appearance of a mobile device in common mode in perspective view, including Figure 1A the display of Figure 23A and the polarization control retarder, whose appearance is shown in a clockwise order from the upper left: front horizontal, front vertical, top-down vertical, and right-side horizontal;

[0104] Figure 24B A schematic diagram showing the brightness appearance of a mobile device in privacy mode in perspective view, including Figure 1A the display of Figure 23AThe polar control retarder, whose appearance is shown in a clockwise order from the upper left: front horizontal, front vertical, top-down vertical, and right-side horizontal;

[0105] Figure 24C It is a schematic diagram showing the appearance of the reflectivity of a mobile device in privacy mode, including Figure 1A the display of Figure 23A the polar control retarder, whose appearance is shown in a clockwise order from the upper left: front horizontal, front vertical, top-down vertical, and right-side horizontal;

[0106] Figure 25A It is a schematic diagram showing a motor vehicle with a switchable directional display arranged in a vehicle cockpit in a night operation mode from a top view;

[0107] Figure 25B It is a schematic diagram showing a motor vehicle with a switchable directional display arranged in a vehicle cockpit in a night operation mode from a side view;

[0108] Figure 26 It is a schematic diagram showing a switchable privacy display for ambient lighting in a side perspective view, including an OLED emitting spatial light modulator, a one-dimensional parallax barrier, an output polarizer, a reflection control quarter-wave retarder, a reflective polarizer, a switchable polar control retarder, and an additional polarizer arranged on the output side of the spatial light modulator;

[0109] Figure 27 It is a front view showing Figure 26 the alignment of the optical layers in the optical stack of

[0110] Figure 28 It is a schematic diagram showing a switchable privacy display for ambient lighting in a side perspective view, including a micro-LED emitting spatial light modulator, a parallax barrier, and an output polarizer serving as a reflective polarizer, a reflection control quarter-wave retarder, a switchable polar control retarder, and an additional polarizer arranged on the output side of the spatial light modulator;

[0111] Figure 29 It is a side view showing Figure 28 the reflection of ambient light in the display of

[0112] Figure 30 It is a schematic diagram showing a low-reflectivity display for ambient lighting in a side perspective view, including an OLED emitting spatial light modulator, a two-dimensional parallax barrier, a leakage output polarizer, and a reflection control quarter-wave retarder arranged on the output side of the spatial light modulator;

[0113] Figure 31 It is a side view showing Figure 30Schematic diagram of reflection of ambient light in a display;

[0114] Figure 32 Is a schematic diagram in side perspective view illustrating a touchscreen low-reflectivity display for ambient lighting, including an OLED emitting spatial light modulator, a two-dimensional parallax barrier including a touch sensor electrode layer, a leakage output polarizer, and a reflection control quarter-wave retarder disposed on the output side of the spatial light modulator;

[0115] Figure 33 Is a front view illustration of Figure 32 Schematic diagram of reflection of ambient light in a display;

[0116] Figure 34 Is a side view illustration of Figure 32 Schematic diagram of the structure of;

[0117] Figure 35A Is a schematic diagram in side perspective view illustrating a low-reflectivity display for ambient lighting, including an OLED emitting spatial light modulator, a two-dimensional parallax barrier and no output polarizer disposed on the output side of the spatial light modulator;

[0118] Figure 35B Is a side view illustration of Figure 35A Schematic diagram of reflection of ambient light in a display;

[0119] Figure 36A Is a schematic diagram in side perspective view illustrating a low-reflectivity display for ambient lighting, including an OLED emitting spatial light modulator, two one-dimensional parallax barriers and no output polarizer disposed on the output side of the spatial light modulator;

[0120] Figure 36B Is a side view illustration of Figure 36A Schematic diagram of reflection of ambient light in a display;

[0121] Figure 37A Is a side view illustration of an array of reflection-refraction optical elements disposed between pixels of a spatial light modulator and a parallax barrier;

[0122] Figure 37B Illustrates the change of output brightness with Figure 37A Polar angle of the arrangement;

[0123] Figure 38A 、 38B 38C and 38D are schematic diagrams in side view illustrating a method of manufacturing a parallax barrier of an emissive display using a fine metal mask;

[0124] Figure 39A 、 39B, 39C, 39D, 39E, and 39F are schematic diagrams showing a method of manufacturing a parallax barrier for an emissive display using photolithography in side view;

[0125] Figure 40A , 40B , 40C, and 40D are schematic diagrams showing a method of manufacturing a parallax barrier for an emitter using printing in side view;

[0126] Figure 41 is a schematic diagram showing a switchable privacy display for ambient lighting in side perspective view, including an OLED emissive spatial light modulator containing tangible OLED pixels, an output polarizer, a reflective control quarter-wave retarder, a reflective polarizer, a switchable polarity control retarder, and an additional polarizer disposed on the output side of the spatial light modulator;

[0127] Figure 42 is a schematic diagram showing a pixel of an OLED emissive spatial light modulator in side perspective view, wherein the OLED pixel is a tangible OLED pixel including a tangible well and a high refractive index filling material;

[0128] Figure 43 is a schematic diagram showing a pixel of an OLED emissive spatial light modulator in side view, wherein the OLED pixel includes a tangible well and a high refractive index filling material;

[0129] Figure 44 is a schematic diagram showing the variation of the luminous intensity of tangible and intangible OLED pixels;

[0130] Figure 45A is Figure 41 a polar plot array of the component weights and outputs of the arrangement, including polar plots of the spatial light modulator brightness, the switchable retarder transmittance, the switchable retarder reflectance, the common mode brightness, the privacy mode brightness, and the visual safety level;

[0131] Figure 45B is Figure 45A a linear graph array of the component weights and outputs of the arrangement, including linear graphs at azimuth angles of 0, 90, 45, and 225 degrees;

[0132] Figure 46 is a schematic diagram showing a switchable privacy display for ambient lighting in side perspective view, including an emissive spatial light modulator, a parallax barrier, a first polarity control retarder disposed between the display polarizer of the emissive spatial light modulator and a first additional polarizer; and a reflective polarizer and a second polarity control retarder disposed between the first additional polarizer and a second additional polarizer;

[0133] Figure 47A is a front perspective view showing for Figure 46Schematic diagram of the arrangement of a polarizer and a polarization control retarder in an embodiment, where the first and second polarization control retarders cross;

[0134] Figure 47B It is a graph showing the simulated polarization curve of the luminance output of an emission spatial light modulator without a barrier structure;

[0135] Figure 47C It is a graph showing the simulated polarization curve of the transmittance of the barrier structure of light from pixels of an emission spatial light modulator;

[0136] Figure 47D It is for explaining the Figure 47A simulated polarization curve of the transmittance of the second polarization control retarder arranged between the first and second additional polarizers, where the transmission directions of the electric vectors of the polarizers are parallel;

[0137] Figure 47E It is for explaining the Figure 47A simulated polarization curve of the reflectance of the second polarization control retarder arranged between a reflective polarizer and a second additional polarizer, where the transmission directions of the electric vectors of the polarizers are parallel;

[0138] Figure 47F It is for explaining the Figure 47E simulated polarization curve of the total reflectance including the reflectance and the Fresnel reflectance from the front surface of a display device;

[0139] Figure 47G It is for explaining the Figure 47A simulated polarization curve of the transmittance of the first polarization control retarder arranged between a display polarizer and a first additional polarizer, where the transmission directions of the electric vectors of the polarizers are parallel;

[0140] Figure 47H It is for explaining Figure 47A simulated polarization curve of the logarithm of the total output luminance of a spatial light modulator and the first and second polarization control retarders;

[0141] Figure 47I It is for explaining Figure 47A simulated polarization curve of the security level S for the ambient illuminance measured in lux in the privacy mode, where the ambient illuminance is twice the front display luminance measured in nits; and

[0142] Figure 47J It is for explaining Figure 47A simulated polarization curve of the security level S for the ambient illuminance measured in lux in the public mode, where the ambient illuminance is twice the front display luminance measured in nits. Detailed Description

[0143] Terms related to optical retarders for the purposes of the present disclosure will now be described.

[0144] In a layer including a uniaxial birefringent material, there is a direction that controls the direction of optical anisotropy, and all directions perpendicular to it (or at a given angle to it) have equal birefringence.

[0145] The optical axis of an optical retarder refers to the direction of propagation of light in a uniaxial birefringent material that does not undergo birefringence. This is different from the optical axis of an optical system, which can be parallel to a symmetry line or perpendicular to the display surface along which the chief ray propagates, for example.

[0146] For light propagating in a direction orthogonal to the optical axis, when linearly polarized light with the direction of the electric vector parallel to the slow axis propagates at the slowest speed, the optical axis is the slow axis. The slow axis direction is the direction with the highest refractive index at the design wavelength. Similarly, the fast axis direction is the direction with the lowest refractive index at the design wavelength.

[0147] For a positive dielectric anisotropy uniaxial birefringent material, the slow axis direction is the extraordinary axis of the birefringent material. For a negative dielectric anisotropy uniaxial birefringent material, the fast axis direction is the extraordinary axis of the birefringent material.

[0148] The terms half-wave and quarter-wave refer to the operation of the retarder for a design wavelength λ0 that can typically be between 500 nm and 570 nm. In this illustrative embodiment, unless otherwise stated, exemplary retardation values are provided for a wavelength of 550 nm.

[0149] The retarder provides a phase shift between two perpendicular polarization components of the incident light wave, and is characterized by the amount of relative phase Γ imparted on the two polarization components; the relative phase is related to the birefringence Δn and the thickness d of the retarder:

[0150] Γ = 2.π.Δn.d / λ0 Equation 1

[0151] In Equation 1, Δn is defined as the difference between the extraordinary refractive index and the ordinary refractive index, i.e.,

[0152] Δn = n e -n o Equation 2

[0153] For a half-wave retarder, the relationship between d, Δn, and λ0 is selected such that the phase shift between the polarization components is Γ = π. For a quarter-wave retarder, the relationship between d, Δn, and λ0 is selected such that the phase shift between the polarization components is Γ = π / 2.

[0154] As used herein, the term half-wave retarder generally refers to light that is perpendicular to the retarder and perpendicular to the light propagating through the spatial light modulator.

[0155] Some aspects of light propagation through a transparent retarder between a pair of polarizers will now be described.

[0156] The state of polarization (SOP) of light is described 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 only acts on their relative phases. Providing a net phase shift between the orthogonal polarization components changes the SOP, while maintaining the net relative phase preserves the SOP. In the present description, the SOP may be referred to as the polarization state.

[0157] A linear SOP has a polarization component with a non-zero amplitude and an orthogonal polarization component with a zero amplitude.

[0158] A linear polarizer transmits the only linear SOP with a linear polarization component parallel to the transmission direction of the electric vector of the linear polarizer and attenuates light with a different SOP.

[0159] An absorption polarizer is a polarizer that absorbs one polarization component of the incident light and transmits the second orthogonal polarization component. An example of an absorption linear polarizer is a dichroic polarizer.

[0160] A reflective polarizer is a polarizer that reflects one polarization component of the incident light and transmits the second orthogonal polarization component. Examples of reflective polarizers that are linear polarizers are multi-layer polymer film stacks, such as the DBEF from 3M Corporation TM or APF TM , or a wire grid polarizer, such as the ProFlux from Moxtek TM . A reflective linear polarizer may further include a cholesteric reflective material and a quarter-wave plate arranged in series.

[0161] A retarder disposed between a linear polarizer and a parallel linear analyzing polarizer that does not introduce a relative net phase shift provides complete transmission of light except for residual absorption within the linear polarizer.

[0162] A retarder that provides a relative net phase shift between the orthogonal polarization components changes the SOP and provides attenuation at the analyzing polarizer.

[0163] In the present disclosure, an "A plate" refers to an optical retarder utilizing a layer of birefringent material with its optical axis parallel to the plane of the layer.

[0164] A "positive A plate" is a positive birefringent A plate, i.e., an A plate with a positive Δn.

[0165] In the present disclosure, a "C-plate" refers to an optical retarder utilizing a birefringent material layer, wherein the optical axis of the optical retarder is perpendicular to the plane of the layer. A "positive C-plate" is a positive birefringent C-plate, i.e., a C-plate having a positive Δn. A "negative C-plate" is a negative birefringent C-plate, i.e., a C-plate having a negative Δn.

[0166] An "O-plate" refers to an optical retarder utilizing a birefringent material layer, wherein the optical axis of the optical retarder has a component parallel to the plane of the layer and a component perpendicular to the plane of the layer. A "positive O-plate" is a positive birefringent O-plate, i.e., an O-plate having a positive Δn.

[0167] An achromatic retarder can be provided, wherein the material of the retarder has a retardation value Δn.d that varies with wavelength λ, as

[0168] Δn.d / λ = κ Equation 3

[0169] where κ is substantially constant.

[0170] Examples of suitable materials include modified polycarbonates from Teijin Films. An achromatic retarder can be provided in the present embodiment to advantageously minimize color variations between a viewing direction at a polar angle with low brightness reduction and a viewing direction at a polar angle with increased brightness reduction, as described below.

[0171] Various other terms related to retarders and liquid crystals used in the present disclosure will now be described.

[0172] A liquid crystal cell has a retardation given by Δn.d, where Δn is the birefringence of the liquid crystal material in the liquid crystal cell and d is the thickness of the liquid crystal cell, independent of the alignment of the liquid crystal material in the liquid crystal cell.

[0173] Horizontal alignment refers to the alignment of liquid crystals in a switchable liquid crystal display, where the molecules are aligned substantially parallel to the substrate. Horizontal alignment is sometimes referred to as planar alignment. Horizontal alignment typically provides a small pretilt angle, e.g., 2 degrees, such that the molecules on the surface of the alignment layer of the liquid crystal cell are slightly tilted, as described below. The pretilt angle is set to minimize degradation during cell switching.

[0174] In the present disclosure, vertical alignment is a state in which rod-shaped liquid crystal molecules are aligned substantially perpendicular to the substrate. In discotic liquid crystals, vertical alignment is defined as a state in which the axis of the columnar structure formed by discotic liquid crystal molecules is perpendicular to the surface alignment. In vertical alignment, the pretilt angle is the pretilt angle of the molecules close to the alignment layer and typically close to 90 degrees and can be, for example, 88 degrees.

[0175] In a twisted liquid crystal layer, a twisted configuration (also referred to as a helical structure or helix) of nematic liquid crystal molecules is provided. The twist can be achieved by non-parallel alignment of the alignment layer. Additionally, a cholesteric dopant can be added to the liquid crystal material to break the degeneracy of the twist direction (clockwise or counterclockwise) and further control the twist pitch in the relaxed (usually undriven) state. A super twisted liquid crystal layer has a twist greater than 180 degrees. The twisted nematic layer used in a spatial light modulator typically has a 90-degree twist.

[0176] Liquid crystal molecules with positive dielectric anisotropy are switched from a horizontal alignment (e.g., A-plate retarder orientation) to a vertical alignment (e.g., C-plate or O-plate retarder orientation) by an applied electric field.

[0177] Liquid crystal molecules with negative dielectric anisotropy are switched from a vertical alignment (e.g., C-plate or O-plate retarder orientation) to a horizontal alignment (e.g., A-plate retarder orientation) by an applied electric field.

[0178] Rod-shaped molecules have positive birefringence such that n e >n o , as described in Equation 2. Disc-shaped molecules have negative birefringence such that n e <n o .

[0179] 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 disc-shaped liquid crystal molecules.

[0180] Parallel liquid crystal cell alignment refers to the alignment directions of the horizontal alignment layers being parallel or more typically anti-parallel. In the case of pre-tilted vertical alignment, the alignment layer can have components that are substantially parallel or anti-parallel. A liquid crystal cell with hybrid alignment can have one horizontal alignment layer and one vertical alignment layer. A twisted liquid crystal cell can be provided by alignment layers that do not have parallel alignment (e.g., oriented 90 degrees to each other).

[0181] A transmissive spatial light modulator can further include a retarder between the input display polarizer and the output display polarizer, for example, as disclosed 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 position from the passive retarder of the present embodiment. Such a retarder compensates for the contrast degradation at off-axis viewing positions, which is a different effect from the brightness reduction at the off-axis viewing positions of the present embodiment.

[0182] Terms related to the appearance of a privacy display will now be described.

[0183] The dedicated operating mode of the display is the mode in which the observer sees low contrast sensitivity such that the image is not clearly visible. Contrast sensitivity is a measure of the ability to distinguish different levels of brightness in a static image. Reverse contrast sensitivity can be used as a measure of visual security because a high level of visual security (VSL) corresponds to low image visibility.

[0184] For a privacy display that provides an image to an observer, the visual security can be given as follows:

[0185] VSL = (Y + R) / (Y - K) Equation 4

[0186] Where VSL is the visual security level, Y is the brightness of the white state of the display at the snooper's viewing angle, K is the brightness of the black state of the display at the snooper's viewing angle, and R is the brightness of the reflected light from the display.

[0187] The panel contrast ratio is given as:

[0188] C = Y / K Equation 5

[0189] For the high-contrast optical LCD mode, the white state transmittance remains substantially constant with the viewing angle. In the contrast-reducing liquid crystal mode of the present embodiment, the white state transmittance generally decreases as the black state transmittance increases, such that

[0190] Y + K ~ P.L Equation 6

[0191] Then, the visual security level can be further given as:

[0192]

[0193] Where the off-axis relative luminance P is typically defined as a percentage of the front luminance L at the snooper's angle, and the display can have an image contrast C, and the surface reflectance is ρ.

[0194] The off-axis relative luminance P is sometimes referred to as the confidentiality level. However, such a confidentiality level P describes the relative luminance of the display at a given polar angle compared to the front luminance and is not a measure of the confidentiality appearance.

[0195] The display can be illuminated by a Lambertian ambient illuminance I. Thus, in a completely dark environment, a high-contrast display has a VSL of approximately 1.0. When the ambient illuminance increases, the perceived image contrast decreases, the VSL increases, and a private image is perceived.

[0196] For a typical liquid crystal display, for almost all viewing angles, the panel contrast C is above 100:1, allowing the visual security level to approach:

[0197] VSL = 1 + I·ρ / (π·P·L) Equation 8

[0198] The perceived image security can be determined from the logarithmic response of the eye such that

[0199] S = log 10 (v) Equation 9

[0200] The required limit value of S is determined as follows. In the first step, a privacy display device is provided. A bright-light measuring device is used to measure the change in the privacy level P(θ) of the display device in the polar viewing angle and the change in the reflectance ρ(θ) of the display device in the polar viewing angle. For example, a light source of a light box with substantially uniform brightness is arranged to provide illumination from an illumination area, and the illumination area is arranged to irradiate the privacy display device along the incident direction so as to be reflected to the observer position at a polar angle greater than 0° with respect to the normal of the display device. Considering the change in the reflectance ρ(θ), the change in the illuminance I(θ) of a substantially Lambertian emission light box in the polar viewing angle is determined by measuring the change in the reflected brightness recorded in the polar viewing angle. The measurements of P(θ), r(θ), and I(θ) are used to determine the change in the safety factor S(θ) in the polar viewing angle along the zero elevation angle axis.

[0201] In the second step, a series of high-contrast images are provided on the privacy display, 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 moving image.

[0202] In the third step, each observer (with vision correction if appropriate to observe at 1000 mm) observes each image from a distance of 1000 m, and adjusts its polar viewing angle at zero elevation until an image cannot be seen by one eye at a position near or on the center line of the display. The polar position of the observer's eye is recorded. The safety factor at the said polar position is determined according to the relationship S(θ). For different images, various display luminances Y max 、different light box illuminances I(q = 0), different background lighting conditions, and different observers, the measurements are repeated.

[0203] Based on the above measurements, S < 1.0 provides low or no visual security, 1.0 ≤ S < 1.5 provides visual security depending on the contrast, spatial frequency, and temporal frequency of the image content, 1.5 ≤ S < 1.8 provides acceptable image invisibility (i.e., the image contrast cannot be observed) for most images and most observers, and S ≥ 1.8 provides complete image invisibility independent of the image content for all observers.

[0204] The desired wide-angle display is readily observable under standard ambient illumination conditions compared to a privacy display. One measure of image visibility is contrast sensitivity, such as Michelson contrast, which is given by:

[0205] M = (I max - I min ) / (I max + I min ) Equation 10

[0206] And thus:

[0207] M = ((Y + R) - (K + R)) / ((Y + R) + (K + R)) = (Y - K) / (Y + K + 2.R) Equation 11

[0208] Thus, the Visual Safety Level (VSL) is equal to (but different from) 1 / M. In this discussion, for a given off-axis relative luminance P, the wide-angle image visibility W is approximately

[0209] W = 1 / VSL = 1 / (1 + I.ρ / (π.P.L)) Equation 12

[0210] In this discussion, assuming a typical display spectral emitter, the color change Δη of the output color (u w '+ Δη', v w '+ Δη') from the desired white point (u w ', v w ') can be determined by the CIELUV color difference metric and is given by:

[0211] Δη = (Δu' 2 + Δv' 2 ) 1 / 2 Equation 13

[0212] The reflective refraction element employs both refraction and reflection, which may be total internal reflection or reflection from a metallized surface.

[0213] The structures and operations of various directional display devices will now be described. In this specification, common elements have common reference numerals. Note that the disclosure related to any element applies to each device in which the same or corresponding elements are provided. Thus, for the sake of brevity, such disclosures will not be repeated.

[0214] There is a need to provide a switchable privacy display using an emissive spatial light modulator.

[0215] Figure 1AFIG. 0 is a schematic diagram showing, in side perspective view, a switchable privacy display 100 for ambient lighting 604, including an OLED emissive spatial light modulator 48, a parallax barrier 700, an output polarizer 218, and a reflective control quarter-wave retarder 228, a reflective polarizer 302, a switchable polarity control retarder 300, and an additional polarizer 318 disposed on the output side of the spatial light modulator 48; and Figure 1B FIG. 1 is a front view showing Figure 1A the alignment of the optical layers in the optical stack of.

[0216] The emissive spatial light modulator 48 includes an array of red, green, and blue pixels 220, 222, 224 disposed in a pixel layer 214 on a backplane substrate 212. The pixels are arranged to output light 400 along an output direction. The pixels 220, 222, 224 include light-emitting diodes, which are organic light-emitting diodes including an organic light-emitting material 232.

[0217] The regions 226 between the pixels 220, 222, 224 include control electronics, and for the OLED pixel layer 214, the regions 226 are typically reflective.

[0218] The parallax barrier 700 includes an array of holes 702 with light-absorbing regions 704 therebetween. The parallax barrier 700 is arranged as a two-dimensional array of holes 702, with each pixel 220, 222, 224 aligned with a corresponding hole.

[0219] The parallax barrier 700 is disposed on a spacer layer 216, which provides a spacing from the pixel layer 214 at a parallax distance d along an axis 199 normal to the plane of the pixel layer 214.

[0220] The output polarizer 218 is disposed on the output of the spatial light modulator 48. The output polarizer 218 is a linear polarizer having an electric vector transmission direction 219. A reflective control quarter-wave retarder 228 having an optical axis direction 229 is disposed between the output polarizer 218 and the spatial light modulator 48. The retarder 228 can be provided by a stretched birefringent film such as polycarbonate. Advantageously, a low-cost retarder 228 can be provided.

[0221] In Figure 1A -B embodiments, the parallax barrier 700 is disposed between the pixel layer 214 and the reflective control quarter-wave retarder 228. In other embodiments (not shown), the quarter-wave retarder 228 can be formed by a layer formed between the pixel layer 214 and the parallax barrier 700. For example, such a retarder 228 can include a cured reactive liquid crystal cell liquid crystal layer. Advantageously, the retarder can have a thickness equal to or less than the required thickness d, as will be further described below.

[0222] An additional polarizer 318 is arranged on the output side of the output polarizer 218, and the additional polarizer 318 is a linear polarizer. A polarity control retarder 300 is arranged between the output polarizer 218 and the additional polarizer 318. The output polarizer 218 and the additional polarizer 318 are arranged to pass through the polarization states of the corresponding linearly polarized light.

[0223] The polarity control retarder 300 includes passive retarders 330A, 330B and a switchable liquid crystal retarder 301. The switchable liquid crystal retarder includes transparent substrates 312, 316 and a switchable liquid crystal layer 314. A voltage driver 350 can be used to select an operation mode and can be controlled by a controller 352.

[0224] Regarding Figure 9 、 Figure 17D 、 Figure 22A -B and Figure 23A Illustrative embodiments are described, which will be described in further detail below.

[0225] Figure 1A The embodiments of further include a reflective polarizer 302 arranged between the output polarizer 218 and at least one polarity control retarder 300. The reflective polarizer 302 is a linear polarizer having an electric vector transmission direction 303, and the polarizer is arranged to pass through the polarization state of the same linear polarization as the output polarizer 218.

[0226] The structures and operations of the polarity control retarder 300 and the reflective polarizer 302 are described in more detail in U.S. Patent Publication No. 2019-0086706, U.S. Patent Publication No. 2019-0250458, U.S. Patent Publication No. 2018-0321553, U.S. Patent Publication No. 2020-0159055 and WIPO Publication No. WO 2018 / 208618. All U.S. patent publications are incorporated herein by reference in their entireties. The polarity control retarder in this specification can be replaced by any of the polarity control retarders described therein.

[0227] Below will be referred to Figure 10A-D further describes the operation of the switchable liquid crystal retarder. In the privacy operation mode, at least one polar control retarder 300 is capable of simultaneously performing the following operations: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the output polarizer 218 along the axis 199 normal to the plane of at least one polar control retarder 300, and introducing a relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer 302 along the axis 197 inclined to the normal of the plane of at least one polar control retarder 300. In the common operation mode, at least one polar control retarder 300 is capable of simultaneously performing the following operations: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the output polarizer 218 along the axis 199 normal to the plane of at least one polar control retarder 300, and substantially not introducing a relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer 302 along the axis 197 inclined to the normal of the plane of at least one polar control retarder 300.

[0228] When combined with the reflective polarizer 302, this phase control of the output light advantageously achieves a reduction in off-axis brightness and an increase in Figure 1A the off-axis reflectivity of the display in the privacy mode. In the common mode, high transmittance and low display reflectivity are achieved at various polar angles. Additionally, in both operation modes, high transmittance and low reflectivity are achieved for on-axis display users. Advantageously, the display users see high-brightness and high-contrast images in both modes, while off-axis snoops see a high level of visual security in the privacy mode and off-axis users see high image visibility in the common mode.

[0229] The structure and operation of the parallax barrier 700 will now be described.

[0230] In emissive displays, high brightness is typically provided at high polar angles. For example, a typical emissive display such as an OLED display can provide a brightness greater than 25% of the front brightness at a polar angle of 60 degrees. A micro-LED display including inorganic LEDs can have a substantially Lambertian brightness output, so the brightness at 60 degrees can be close to 100% of the front brightness.

[0231] As will be described in Figure 11A -B, the polar control retarder 300 is typically arranged to provide the best level of visual security at the designed polar positions. For example, this polar position can be the + / - 45-degree side angle and the 0-degree elevation angle. At a side angle with a 5-degree difference from the designed polar position, the reduction in brightness and the increase in reflectivity will be reduced.

[0232] There is a need to provide a switchable privacy display that has high visual security in privacy mode at polar angles greater than 45 degrees and high image visibility in public mode at polar angles greater than 45 degrees. For high image visibility under typical ambient lighting conditions, the off-axis luminance can desirably be at least 2.5% and preferably at least 5% of the front luminance. For high image security under typical ambient lighting conditions, the off-axis luminance can desirably be less than 1% and preferably less than 0.5%. There will further be a need to provide low chromaticity variation at polar viewing angles.

[0233] Figure 2A -B illustrates in side view a parallax barrier 700 of a privacy display 100 for Figure 1A -B. Figure 2A -B illustrates a cross-section in the direction θ closest to the holes 702.

[0234] It can be assumed that features of the Figure 2A - 2B arrangement not further discussed in detail correspond to features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0235] For purposes of description, various output layers such as polarizers and retarders disposed at the output of the parallax barrier are indicated by a monolithic layer 110.

[0236] An ideal range of the parallax barrier structure has been established through simulation of retarder stacks, parallax barriers, pixel arrangements, and experiments through the display optical stack.

[0237] Light rays 710 guided along an axis 199 perpendicular to the spatial light modulator 48 are guided through respective alignment holes 702 of width a. The hole size a is greater than the pixel width w to achieve 100% luminance in the front direction. Thus, along the direction closest to the holes 702, the holes 702 have a width a and the pixels 220, 222, 224 have a width w that satisfies the following requirement:

[0238] a ≥ w Equation 14

[0239] Some light rays 726 are guided in an off-axis direction such that the luminance in the off-axis direction is reduced compared to the front luminance of the light rays 710. The minimum absorption rate provided by the parallax barrier is desirably 50%, such that along the direction closest to the holes 702, the holes 702 have a width a, the pixels 220, 222, 224 have a pitch p, and the pixels 220, 222, 224 have a width w that satisfies the following requirement:

[0240] a ≤ (p - w / 2) Equation 15

[0241] Some of the light rays 712 from pixels 220, 222, 224 can be incident on the lower side of the parallax barrier absorption region 704 and can be absorbed. When the light ray 712 from the center of the pixel is incident on the center of the absorption region 704, the minimum transmission angle is provided. The polar angle in air can be at least 45 degrees such that along the direction closest to the hole 702, the material between the parallax barrier 700 and the pixels 220, 222, 224 has a refractive index n that satisfies the following requirements:

[0242]

[0243] The light ray 716 from the center of pixels 220, 222, 224 that is incident on the edge of the absorption region of the parallax barrier 700 is at a polar angle at which the luminance is at most 50% of the front luminance. Ideally, (in air) is at most 90 degrees, and thus the parallax barrier has a spacing d from the pixels 220, 222, 224 that satisfies the following requirements:

[0244]

[0245] In other embodiments, the ideal angle of

[0246]

[0247] Illustrative dimensions in microns for a pixel pitch of 50 microns in the direction closest to the pixels are given in Table 1, along with a refractive index of 1.5 for the medium between the pixel layer 214 and the parallax barrier 700.

[0248]

[0249] Table 1

[0250] Therefore, the thickness d of the parallax barrier separation layer 216 is approximately 30 μm. As will be further described below, such a thickness is typical for a typical encapsulation layer of an OLED panel. The parallax barrier 700 can be formed ideally close to the pixel layer 214 to advantageously achieve the desired performance of the switchable privacy display.

[0251] By comparison with embodiments of the present invention, Table 2 illustrates the structure of a dual-view parallax barrier autostereoscopic display for the same pixel pitch and pixel width, where pixel columns point to the viewing windows, and each window provides a left-eye or right-eye image. An ideal thickness range is provided for a minimum window size of 60 mm, a maximum window size of 67 mm, a minimum viewing distance of 250 mm, and a maximum window distance of 700 mm.

[0252]

[0253] Table 2

[0254] Advantageously, compared to embodiments for autostereoscopic displays, embodiments of the present invention achieve increased brightness and lower thickness. The autostereoscopic display parallax barrier does not achieve the desired privacy display brightness control characteristics.

[0255] Some of the light 714 can pass through the holes 702 at an angle greater than the critical angle and thus total internally reflect. Such light can be absorbed by the top of the parallax barrier absorption region 704. Other absorption mechanisms will be discussed further below.

[0256] The absorption region 704 can be partially absorbing. Due to the reduced absorption rate of the absorbing material, some of the light 712 can pass through the absorption region 704. Additionally or alternatively, the absorption region 704 can be disposed within the sub-holes 722, which are arranged to permit the propagation of the light 712. The sub-holes 722 can have a size and density arranged to provide a desired illumination distribution in a common operating mode.

[0257] In an illustrative example, the barrier region 704 can transmit 5% of the incident light by means of the sub-holes 722. For Lambertian emission pixels 220, 222, 224, the brightness at a 60-degree angle can be arranged to be 5% by controlling the density and size of the sub-holes 722 and the hole width for a given pixel pitch p and pixel size a. In the privacy mode, the brightness can be less than 1%. Advantageously, the image visibility in the common operating mode can be increased, while a high level of visual security can be achieved in the privacy mode by means of the polarization control retarder 300.

[0258] The arrangement of the parallax barrier pitch p' compared to the pixel pitch p will now be described.

[0259] Figure 3A is a schematic illustration of the alignment of the parallax barrier 700 for non-pupil output with Figure 1A the pixels 220, 222, 224.

[0260] The parallax barrier 700 directs light from each pixel 220, 222, 224 to the common viewing window 26. In Figure 3AIn it, the common viewing windows are angled, in other words, the common sub-windows 26 from each pixel overlap the aligned barrier holes 702 at infinity and are collimated. The window represents the angular distribution of light from each slit. Advantageously, this arrangement provides a spatial attenuation across the display 100 similar to that of the polarization control retarder 300 and the polarizers 218, 318. For a moving observer, a natural variation in image uniformity across the display area is achieved, that is, the part of the display closest to the user appears the brightest.

[0261] Figure 3B is a schematic illustration in side perspective of the alignment of the parallax barrier 700 for pupil output with Figure 1A the pixels 220, 222, 224. The pitch p' along the direction closest to the hole 702 is less than the pitch p of the corresponding aligned pixels 220, 222, 224 along the direction closest to the pixels 220, 222, 224. In any given direction, the pitch s' of the closest hole 702 is less than the pitch s of the corresponding aligned pixels 220, 222, 224.

[0262] The viewing window 26 is formed at a viewing window plane at a distance v, which is on the output side of the spatial light modulator 48, such that the common viewing window at the overlap of the viewing windows is at a finite distance. Advantageously, for a front observer located at the window plane, the brightness uniformity across the display area is increased.

[0263] At least some of the holes of the parallax barrier may include color filters 703R, 703G, 703B, so the holes of the parallax barrier include an array of red, green, and blue color filters. The color filters may correspond to the colors of the corresponding aligned pixels 220, 222, 224. The filters reduce color crosstalk, such as blue light leaking into the red pixel holes, thus advantageously achieving an increased color gamut.

[0264] Alternatively, only some of the holes 702 may include color filters. For example, the holes 702 corresponding to the red and green emitting pixels 220, 222 may include a yellow transmissive filter. In some embodiments, color emission may be achieved by, for example, a blue emitting pixel and a color conversion material aligned with the pixels 220, 222 to achieve a color output. The yellow filter of the hole 702 may provide absorption of residual blue light, thus advantageously achieving an increased color gamut.

[0265] The material of the color filter of the hole 702 may include a non-scattering or low-scattering material such that the angular control function of the hole 702 and the absorption region 704 is maintained.

[0266] It may be assumed that the features of the arrangement of Figure 3A -B not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0267] Figure 4 FIG. is a schematic diagram showing the arrangement of the uniform emission pixels 220, 222, 224 and the eye point positions 260, 262, 264 for various polar viewing angles in a top view.

[0268] The pixels 220, 222, 224 are arranged in columns and rows, and the direction closest to the aperture 702 is 45 degrees with respect to the electric vector transmission direction 219 of the output linear polarizer; and each pixel 220, 222, 224 has a light emitting region in the shape of a square, where the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer.

[0269] The aperture 702 has a square shape, where the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer.

[0270] The eye point positions 260, 262, 264 represent the images of the observer's pupils at the pixel layer 214 provided by the aperture 702. The eye point position 260 represents the position of the pupil of a front observer. Since the point position 260 has a size larger than that of the pixel, the observer sees the same brightness as the pixel and achieves 100% brightness.

[0271] For the position 262, the observer's eye is located in the display quadrant (with non-zero side angle and elevation angle) and has a minimum transmittance. For the position 262, the observer's eye is positioned at zero elevation angle, has a lateral offset, and has a minimum transmittance.

[0272] The eye point position 264 has a greater spacing from the on-axis position compared to the position 262, such that the minimum transmittance is in the quadrant rather than closest in the lateral direction. Advantageously, the suppression in the viewing quadrant can be optimized.

[0273] In addition, Figure 4 the pixel arrangement achieves an ideal rendering of horizontal and vertical lines while reducing the number of red and blue pixels compared to the number of green pixels.

[0274] Due to the different luminous intensities (lumen / mm 2 ) of the corresponding material systems, OLED displays typically provide different emission regions for red, green, and blue pixels. By means of the comparison in the Figure 4 embodiment, when used with a two-dimensional aperture 702 array, the pixels 220, 222, 224 of the present disclosure include emission regions having substantially the same area for all pixels. Advantageously, the variation of the white point with the viewing angle can be minimized.

[0275] It is necessary to compensate for the different luminous intensities of the red, green, and blue emitters in the OLED display to achieve the desired white point.

[0276] The luminance of each pixel 220, 222, 224 can be changed by adjusting the drive current between different color pixels, thus maintaining the white point. Thus, the green pixel 222 can have, for example, an emission area twice that of a conventionally used one. The drive currents of the green pixel 222 and the red pixel 220 can be reduced to achieve the desired white point.

[0277] It may be necessary to provide the same drive current as that used for a typical OLED display.

[0278] Figure 5 FIG. is a schematic diagram showing the arrangement of the structured emission pixels 220, 222, 224 and the eye point positions for various polar viewing angles in a top view.

[0279] For at least some of the pixels 220, 222, 224, the light-emitting regions of at least some pixels include light-emitting sub-regions 232R, 232G, 232B and non-light-emitting sub-regions 234. For the red, green and blue pixels 220, 222, 224, the area ratios of the light-emitting sub-regions to the non-light-emitting regions are different. For each pixel, the sub-regions 232R, 232G, 232B can be provided within the same region. The distribution of the sub-regions 232 and the size of the eye point 260 can be arranged to provide a substantially uniform attenuation of the luminance with the polar angle, so as to advantageously achieve a minimum change in the white point with the viewing angle; and the required drive current can be provided for each of the color pixels 220, 222, 224.

[0280] It can be assumed that the features of the Figures 4 to 5 arrangement not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0281] Now, the structure of an OLED display including a parallax barrier 700 will be described.

[0282] Figure 6 FIG. is a schematic diagram showing the spatial light modulator 48 and the structure of the aligned parallax barrier 700 including the upper incident reduction layers 750, 752 in a side view.

[0283] The pixel layer 214 is formed on the substrate 212 and includes a thin-film control circuit system 240, which includes thin-film transistors, capacitors, electrodes and other electronic control components. The electrical vias 242 provide connections to the electrodes 230, which are typically reflective. The emission layers 232R, 232G, 232B are arranged between the electron transport layers 236R, 232G, 232B and the hole transport layers 238R, 238G, 238B. The transparent electrodes 244 are arranged to provide output-side electrical connections.

[0284] The thicknesses of the emission layer 233R, 233G, 233B and the electron transfer layer 237R, 237G, 237B can be adjusted to provide suitable light output characteristics. For each of the red, green, and blue light-emitting regions in pixels 220, 222, 224, the thicknesses 233R, 233G, 233B of the light-emitting material are different.

[0285] In another arrangement (not shown), the hole and electron transport layers 236, 238 can be alternately arranged below and above the emission region 232. The total thickness of the pixel layer 214 can generally be 1 micron or less, and thus the difference in the position of the emission layer 232 is small compared to the distance to the spacer layer 216.

[0286] The display device 100 has one or more additional layers 750, 752 in the spacer layer 216 disposed between the pixel layer 214 and the parallax barrier 700, where the pixels 220, 222, 224, one or more additional layers, and the parallax barrier 700 are formed as a monolithic stack. The one or more additional layers include at least one light-transmissive inorganic layer 752, which is arranged to provide a barrier against water and oxygen. For example, the material 752 can be an oxide material such as SiOx.

[0287] The layer 750 can have an organic material. The substrate 212 can further have layers 750, 752 (not shown). The ingress of water and oxygen can be suppressed while maintaining the flexible display structure with the desired mechanical properties. Advantageously, the display lifetime can be increased.

[0288] The total thickness d can be adjusted to advantageously achieve the desired brightness attenuation as described elsewhere herein.

[0289] The parallax barrier 700 further includes at least one light-transmissive inorganic material, which is arranged to provide a barrier against water and oxygen. Advantageously, the lifetime can be increased. In addition, a non-transmissive barrier layer can be provided in the absorption region 704 to achieve enhanced suppression of ingress on at least a portion of the barrier.

[0290] Further reduction of ingress may be required. The parallax barrier 700 is disposed between the pixel layer 214 and at least one light-transmissive inorganic layer 752, which is arranged to provide a barrier against water and oxygen. The inorganic layer 752 is separated by the organic layer 750. Advantageously, high resistance to the ingress of water and oxygen can be provided in the flexible substrate.

[0291] Figure 7 is a schematic diagram showing the structure of the spatial light modulator 48 and the alignment parallax barrier including the glass material 110 in a side view. Compared with Figure 6 the arrangement, the glass material 110 can be provided for the cover layer 217, and the cover layer is associated withFigure 6 Layers 752 and 750 provide a high barrier layer against the ingress of oxygen and water as compared to. The separation layer 216 may be provided by an adhesive material or a polymeric material. Alternatively, the separation layer 216 may be provided by a glass material which is thinned by chemical mechanical polishing after the backplane 212 and the pixel layer 214 are manufactured to achieve the desired thickness d.

[0292] It can be assumed that the features of the Figure 7 arrangement not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0293] The arrangement of the transmittance curve of the parallax barrier 700 will now be described in more detail.

[0294] Figure 8A -C is a schematic diagram illustrating the variation of the transmittance of the parallax barrier 700 with the position of various parallax barrier 700 structures.

[0295] Figure 8A A first transmittance curve 701 illustrating the relative transmittance with respect to the position in the direction θ closest to the holes; wherein the absorption region 704 has 100% absorption. Advantageously, at polar angles greater than 45 degrees, extremely low brightness can be achieved in the privacy mode.

[0296] Figure 8B Illustrates the transmittance 705 of the absorption region 704 increased, for example, by controlling the thickness of the material used to form the absorption region 704. The absorption rate of the region of the parallax barrier 700 between the holes 702 is less than 100% and greater than 80%, preferably greater than 90% and more preferably greater than 95%. The transmittance 705 can be, for example, less than 5% or less than 2.5%. Advantageously, in the common operating mode, increased brightness can be provided at higher polar viewing angles.

[0297] Figure 8C Illustrates by, for example, Figure 2A the transmittance of the absorption region 704 increased by the sub-hole region 722 illustrated in. The average transmittance 705 across the light absorption region 704 can be, for example, less than 5% or less than 2.5%. Advantageously, in the common operating mode, increased brightness can be provided at higher polar viewing angles.

[0298] The structure of an illustrative embodiment of the Figure 1A polarity retarder will now be described.

[0299] It can be assumed that the features of the Figure 8A -B arrangement not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0300] In Figure 1AIn an embodiment of -B, the polarization control retarder 300 includes a passive polarization control retarder 330 and a switchable liquid crystal retarder 301, but can generally be replaced by other configurations of at least one retarder, some examples of which are present in the devices described below.

[0301] Figure 9 FIG. illustrates the arrangement of the switchable polarization control retarder 300 including the liquid crystal retarder 301 in a perspective side view. The liquid crystal retarder includes a switchable liquid crystal layer 314 with horizontal alignment and crossed A - plate polarization control retarders 330A, 330B. It can be assumed that the features of the arrangement not further discussed in detail Figure 9 correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0302] Table 3 provides illustrative embodiments and polarization curves in the privacy and public modes.

[0303]

[0304] Table 3

[0305] The switchable liquid crystal retarder 301 includes two surface alignment layers 419a, 419b, which are adjacent to the liquid crystal material 421 layer and disposed on opposite sides thereof, and each is arranged to provide horizontal alignment in the adjacent liquid crystal material 421. The layer 314 of the liquid crystal material 421 of the switchable liquid crystal retarder 301 includes a liquid crystal material 421 having a positive dielectric anisotropy.

[0306] The passive polarization control retarder 330 is provided by a pair of A - plates 330A, 330B with crossed axes. In this embodiment, "crossed" means an angle of substantially 90° between the optical axes of the two retarders in the plane of the retarder. To reduce the cost of the retarder material, it is desirable to provide materials with some variation in the retarder orientation, such as due to stretching errors during thin - film manufacturing. Variations in the retarder orientation away from the preferred direction can reduce the front - face brightness and increase the minimum transmittance. Preferably, the angle 310A is at least 35° and at most 55°, more preferably at least 40° and at most 50°, and most preferably at least 42.5° and at most 47.5°. Preferably, the angle 310B is at least 125° and at most 145°, more preferably at least 130° and at most 135°, and most preferably at least 132.5° and at most 137.5°.

[0307] Horizontal alignment advantageously provides reduced recovery time during mechanical deformation, such as when touching a display. A stretched film can be used to provide the passive retarders 330A, 330B, to advantageously achieve low cost and high uniformity. Additionally, the field of view of the liquid crystal retarder with horizontal alignment is increased, while providing elasticity for the visibility of the flow of the liquid crystal material during the application of pressure /

[0308] At least one polarization control retarder 300 is arranged to perform the following operations simultaneously in a first switchable state of the switchable liquid crystal retarder 301: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer 302 along the axis 199 normal to the plane of at least one polarization control retarder 300, and introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer 302 along the axis 197 inclined to the normal of the plane of at least one polarization control retarder 300; and performing the following operations simultaneously in a second switchable state of the switchable liquid crystal retarder 301: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer 302 along the axis 199 normal to the plane of at least one polarization control retarder 300, and not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer 302 along the axis 197 inclined to the normal of the plane of at least one polarization control retarder 300.

[0309] Such phase shifts provide polarization transmittance and reflectance curves that achieve the following: (i) high on-axis transmittance and low reflectance; (ii) in the privacy mode, off-axis reduced transmittance and increased reflectance; and (ii) in the common mode, off-axis high transmittance and low reflectance. Advantageously, as will now be described, the switchable privacy display provides high image quality to the front user, a high level of visual security to the off-axis snooper, and high image visibility to the off-axis display user.

[0310] Figure 10A is a schematic side view showing the propagation of the output light from the spatial light modulator 48 through Figure 1A the optical stack in the common operating mode.

[0311] In the common operating mode, the light rays 710 emitted by the pixels 220, 222, 224 in the on-axis direction and transmitted through the holes 702 of the barrier 700 have a polarization state 360 parallel to the electric vector transmission direction 219 of the output polarizer 218. The on-axis light rays 710 then pass through a plurality of retarder layers 300 including the switchable liquid crystal retarder 301 and the passive retarder 330. In the common mode, the switchable liquid crystal retarder 301 is in the off state, where the control voltages across the liquid crystal layer 314 are different.

[0312] Accordingly, the polarization state of the on-axis ray 710 undergoes a delay when passing through the switchable liquid crystal retarder 301. In the case where the passive retarder 330 is a C-plate retarder, the on-axis ray 710 propagates in a direction substantially parallel to the optical axis of the passive retarder 330. Accordingly, the on-axis ray 710 undergoes a minimum delay when passing through the passive retarder 330. The combined effect of the plurality of retarders 300 causes the on-axis ray 710 to exit the plurality of retarders 300 with a linear polarization state 362 that is the same as or similar to the linear polarization 360 with which the on-axis ray 710 enters the plurality of retarders 300. This linear polarization state 362 is parallel to the electric vector transmission direction 319 of the additional polarizer 318, and thus the on-axis ray 710 exits the display device 100 with a relatively constant brightness.

[0313] In the common mode, the off-axis ray 726 transmitted through the apertures 702 of the barrier 700 passes through the plurality of retarders 300 in a manner similar to that of the on-axis ray 710. Accordingly, when the switchable liquid crystal retarder 301 is in the first of the two states, the plurality of retarders 300 do not provide an overall transformation of the polarization states 360, 361 of the following rays: the ray 710 passing through it perpendicular to the plane of the switchable retarder or the ray 726 passing through it at an acute angle to the plane perpendicular to the switchable retarder 301.

[0314] The polarization state 362 is substantially the same as the polarization state 360, and the polarization state 364 is substantially the same as the polarization state 361. Accordingly, the angular transmission curve transmits substantially uniformly over a wide polar region.

[0315] In other words, when the layer 314 of the liquid crystal material 414 is in the first of the two states, the plurality of retarders 300 do not provide an overall delay to the light passing through it perpendicular to the plane of the retarder or at an acute angle to the plane perpendicular to the plurality of retarders 300.

[0316] Advantageously, the change in the display brightness with the viewing angle in the first state is substantially unchanged. Multiple users can conveniently view the display from a wide range of viewing angles.

[0317] Figure 10B FIG. is a side view illustrating the propagation of light rays from the ambient light source 604 through Figure 1A the optical stack in the common operating mode.

[0318] The on-axis ray 410 of the ambient light 604 passes through the plurality of retarders 300 in a manner similar to the on-axis rays 710 emitted from the emission pixels 220, 222, 224 discussed above. Although the direction in which the on-axis ray 410 passes through the plurality of retarders 300 is opposite to the direction in which the on-axis rays 710 are emitted from the emission pixels 220, 222, 224, passing through the plurality of retarders 300 in the opposite direction does not change the effect of the plurality of retarders 300 on the light, as discussed above for the light emitted from the emission pixels 220, 222, 224. Thus, the on-axis ray 410 reaches the absorption region 704 of the parallax barrier 700 where it is absorbed; or the pixel layer 214 where it can be absorbed or reflected, as will be further described below.

[0319] In a similar manner, the off-axis ray 412 does not undergo an overall transformation of its polarization state when passing through the plurality of retarders 300. The ambient light 604 is unpolarized and the off-axis ray is initially not polarized 370. The additional polarizer 318 allows the polarization component 372 parallel to the electric vector transmission direction 319 of the additional polarizer to pass through. The additional polarizer 318 absorbs most of the polarization state 372 perpendicular to the electric vector transmission direction 319 of the additional polarizer 318. Some light is reflected from the front surface of the polarizer 318 by Fresnel reflection at the external air interface. After passing through the plurality of retarders 300, the linear polarization state 374 of the off-axis ray 412 is thus parallel to the electric vector transmission direction 303 of the reflective polarizer 302, and the off-axis ray is not reflected but passes through the reflective polarizer 302 to reach the parallax barrier 700, where it can be absorbed by the absorption region of the parallax barrier or transmitted to the pixel layer 214. As will be further described below, some of the reflected rays 412 will be further absorbed by the absorption region 704 of the parallax barrier 700.

[0320] Advantageously, the display reflectance in the common mode is reduced over a wide viewing angle range. Multiple users can conveniently view the display with high image contrast from a wide range of viewing angles.

[0321] Figure 10C A side view is used to illustrate the propagation of the output light from the spatial light modulator 48 through Figure 1A the optical stack in the privacy operation mode.

[0322] In the privacy mode, the switchable liquid crystal retarder 301 is in a conducting state, where a voltage is applied to the liquid crystal layer 314. The switchable liquid crystal retarder 301 can thus be in the second of the two states. In the case where the switchable liquid crystal retarder 301 has positive dielectric anisotropy, the switchable liquid crystal retarder 301 thus acts in a similar manner in the second state to adjust the phase of the incident polarization state of the output. When passing through the switchable liquid crystal retarder 301 in the second state, the on-axis ray 710 does not experience retardation, so the linear polarization state 360 of the on-axis ray 710 before passing through the plurality of retarders 300 is the same as the linear polarization state 362 after passing through the plurality of retarders 300. Thus, the on-axis ray 710 exits the display through the additional polarizer 318 with substantially unchanged brightness in the privacy operation mode.

[0323] The off-axis ray 726 emitted from the emission pixels 220, 222, 224 and transmitted through the holes 702 of the barrier 700 undergoes a polarization transformation when passing through the material of the switchable liquid crystal retarder 301. This is because the off-axis ray 726 is incident at an acute angle. Thus, the off-axis ray 726 arrives at the additional polarizer 318 with a linear polarization state 364 that is at least partially rotated compared to the linear polarization state 361. The linear polarization 364 has at least some components perpendicular to the electric vector transmission direction 319 of the additional polarizer 318, so the brightness of the off-axis ray 726 is reduced compared to the on-axis ray 710.

[0324] Advantageously, the display brightness at a wide viewing angle can be reduced in the second state. Thus, snoopers can be prevented from observing the image emitted by the display device 100 at a wide viewing angle. Stray light can be reduced during night operation, while the front user can see the image.

[0325] Figure 10D FIG. is a side view illustrating the propagation of light from the ambient light source 604 through Figure 1A the optical stack in the privacy operation mode.

[0326] In the privacy mode of operation, the incident on-axis ray 410 from the ambient light source 604 is similar to that regarding Figure 10CThe described manner of emitting on-axis light rays 710 from the emission pixels 220, 222, 224 passes through the plurality of retarders 300. Although the direction in which the on-axis light rays 410 pass through the plurality of retarders 300 is opposite to the direction in which the on-axis light rays 710 are emitted from the emission pixels 220, 222, 224, the direction of the plurality of retarders 300 entering and exiting the display does not change the effect of the plurality of retarders 300 on the light rays, as discussed for the light emitted from the emission pixels 220, 222, 224. Thus, the on-axis light rays 410 reach the parallax barrier 700, where the on-axis light rays can be absorbed by the absorption regions of the parallax barrier or transmitted to the pixel layer 214. As further described below, some of the reflected light rays 412 will be further absorbed by the absorption regions 704 of the parallax barrier 700.

[0327] In contrast, the off-axis light rays 412 undergo a polarization transformation when passing through the material 414 of the switchable liquid crystal retarder 301. This is because the off-axis light rays 412 are incident at an acute angle, as discussed in further detail below. Thus, the off-axis light rays 412 reach the reflective polarizer 302 with a linearly polarized state 374 that is at least partially rotated compared to the linearly polarized state 372. The linearly polarized state 374 has at least some states perpendicular to the electric vector transmission direction 303 of the reflective polarizer 302 and is thus at least partially reflected by the reflective polarizer 302. Then, the light rays 412 pass through the plurality of retarders 300 in the opposite direction, thereby reversing the polarization conversion from the first pass through the plurality of retarders 300 and generating a polarization state 376 parallel to the electric vector transmission direction of the additional polarizer 318. Thus, the off-axis light rays 412 leave the display device 100 in the polarization state 378, causing the stack to appear as a mirror when viewed from a wide angle. The additional polarizer 318 absorbs most of the polarization states 372 perpendicular to the electric vector transmission direction 319 of the additional polarizer but can reflect a small portion of the perpendicular state 404.

[0328] Advantageously, in the second state, the reflectivity at a wide viewing angle can be increased. Thus, a snoop can be prevented from viewing the image emitted by the display device 100 at a wide viewing angle, as the reflected light reduces the contrast of the image emitted by the display device and thus increases the visual security level VSL due to the increased reflectivity R, as described in Equation 7 above.

[0329] It can be assumed that the features of the Figure 10A -D arrangement correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0330] The simulated output of the illustrative embodiment will now be described.

[0331] Figure 11A is Figure 1AComponent ratios of the arrangement and the output polar plot array, including the spatial light modulator 48 luminance, the parallax barrier 700 transmittance, the switchable retarder 300 transmittance, the normalized switchable retarder 300 reflectance, the common mode luminance, the privacy mode luminance, and polar plots for a visual safety level of 1.0 lux / nit ratio; and Figure 11B is Figure 11A Component ratios of the arrangement and the output line graph array, including line graphs at azimuth angles of 0 degrees (east direction), 90 degrees (north direction), 45 degrees (northeast direction), and 225 degrees (southwest direction). For the purposes of the current description, on Figure 11A the SLM luminance map of Figure 11B illustrates the azimuth orientation of the curves in

[0332] Figure 11A -B The illustrative parallax barrier 700 and OLED pixel parameters are provided in the first row of Table 4 with a spacing p of 50 μm in the direction closest to the pixel. In Figure 4 the diamond arrangement of

[0333]

[0334] Table 4

[0335] Considering the transmission of polarized light by the polarizer 318 and the reflection of polarized light by the reflection polarizer 302, a peak eQM reflectivity of 36% is used, which corresponds to the 100% contour on the graph of the normalized switchable retarder reflection.

[0336] The SLM 48 luminance map illustrates that the OLED display provides non-Lambertian luminance attenuation, which is typically greater than 20% of the front luminance provided at a polar angle of 50 degrees.

[0337] The parallax barrier 700 transmittance map illustrates the differences in the curves for azimuth angles of 0 degrees and 45 degrees due to the different separations of the pixels in this orientation.

[0338] The switchable retarder 300 transmittance and reflectance maps illustrate the use of Figure 9 the structure to control the phase along the lateral direction.

[0339] The common mode illuminance is determined by the transmittance of the parallax barrier 700 for the light from the spatial light modulator 48. The switchable polarity control retarder 300 provides only a small modulation of this luminance curve.

[0340] Privacy Mode Brightness Description Provides less than 1% brightness in the lateral direction and in the upper viewing quadrant. The display has high visibility for 0 degree side angles and for rotation about the horizontal axis. Advantageously, a comfortable viewing angle can be set for a user to view the display from an on-axis position.

[0341] The effect of ambient light level on visual safety level will now be described.

[0342] Figure 11C The lux / nit ratio is 0.25 Figure 11A The display 100 characteristics are described in the second row of Table 4.

[0343] The Visual Safety Level (VSL) graph depends on the ambient illumination conditions. Ambient illumination is provided as a ratio of the frontal luminance. Thus, in a typical office environment, a display with a frontal luminance of 300 nits and an ambient luminance of 300 lux falling on the display has a lux / nit ratio of 1.0. In a darkened aircraft cockpit, a frontal luminance of 100 nits may be provided for an ambient luminance of 25 nits, providing a lux / nit ratio of 0.25.

[0344] The switchable reflectivity of embodiments of the present invention achieves increased visual safety levels at low lux / nit ratios. In addition, parallax barrier 700 can further reduce off-axis brightness to advantageously achieve further increased visual safety under low illumination conditions.

[0345] It has been determined by means of experiments and simulations that a visual safety level greater than 3.0 and preferably greater than 4.0 in privacy mode is required for a high degree of isolation of the displayed image from off-axis snoopers. It has also been determined by means of experiments and simulations that an image visibility W greater than 50% and preferably greater than 83.3% (a visual safety level V less than 2.0 and preferably less than 1.2 in public mode) achieves the desired image visibility of the displayed image for off-axis users.

[0346] Figure 11B The visual safety level curve for -C illustrates that a visual safety level of greater than 4.0 can be achieved for side angles and in the viewing quadrant at side angles of at least 45 degrees, and for azimuth angles in the viewing quadrant in the lateral direction and under lighting conditions of less than 0.25 lux / nit. Advantageously, high visual safety levels can be achieved for off-axis users at various polar positions. The visual safety level does not degrade at higher polar angles in the lateral direction.

[0347] By comparison with the embodiment of the present invention, the embodiment in which the parallax barrier 700 is omitted will now be described. Figure 1A A simulated appearance of the arrangement.

[0348] Figure 12A for an illustrative arrangement in which the parallax barrier 700 is removed Figure 1A a polar plot array of the component weights and outputs of the arrangement, including the spatial light modulator 48 luminance, the parallax barrier 700 transmittance, the switchable retarder transmittance, the switchable retarder reflectance, the common mode luminance, the privacy mode luminance, and the polar plot of the visual safety level at 1.0 lux / nit; and Figure 12B is Figure 12A a linear graph array of the component weights and outputs of the arrangement, including the linear graphs at azimuth angles of 0, 90, 45, and 225 degrees. The characteristics of the display 100 are described in the third row of Table 4.

[0349] By comparison with an embodiment of the present invention as will be described in Figure 12A -B, the polarizing control retarder 300 may not achieve the desired visual safety level in a display having a high off-axis luminance level, such as is typically provided by the emissive spatial light modulator 48 in which the parallax barrier 700 is absent.

[0350] Considering the linear polar graph of the visual safety level in the lateral (0 degree) direction at angles greater than 60 degrees, for 1.0 lux / nit, the VSL is below 4.0. This arrangement provides an undesired visual security to off-axis snoops, although having a high VSL at an angle of approximately 45 degrees.

[0351] By comparison with an embodiment of the present invention, the simulated appearance of the arrangement omitting the polarizing control retarder 300 will now be described. Figure 1A

[0352] Figure 13A for an illustrative arrangement in which the switchable retarder is removed Figure 1A a polar plot array of the component weights and outputs of the arrangement, including the spatial light modulator 48 luminance, the parallax barrier 700 transmittance, the switchable retarder transmittance, the switchable retarder reflectance, the common mode luminance, the privacy mode luminance, and the polar plot of the visual safety level for 1.0 lux / nit; and Figure 13B is Figure 13A a linear graph array of the component weights and outputs of the arrangement, including the linear graphs at azimuth angles of 0, 90, 45, and 225 degrees.

[0353] The characteristics of the display 100 are described in the fourth row of Table 4. The parallax barrier thickness 700 is designed to be a minimum thickness to provide a VSL greater than 4.0 at at least one azimuth angle at a 45 degree polar angle in the lateral direction.

[0354] ​This display has an undesirable privacy performance within a wide range of polar viewing angles, especially in the viewing quadrants, without significantly reducing the aperture size and subsequent undesirable loss of transmission efficiency.

[0355] We will now further consider the spectral transmission and spectral reflection of ambient light from the surface of display 100 in a common operating mode. Figure 1A of display 100.

[0356] Figure 14 is a side view illustrating a schematic diagram of the reflection of ambient light in display 100. It can be assumed that the features of the arrangement not further discussed in detail Figure 1A of display 100 correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features. Figure 14

[0357] Ray 710 is transmitted by linear polarizers 218, 318, where the spectral transmission of polarizers 218, 318 provides spectral modification of the light from pixels 220, 222, 224.

[0358] Rays 714, 715 are totally internally reflected from the outer surface of display 100. Ray 714, which would be absorbed upon incidence, is directed onto absorption region 704 of parallax barrier 700. Ray 715 is reflected from reflective pixel layer 214. Reflective retarder 228 provides a circular polarization state 442 that undergoes a phase change upon reflection to provide a circular polarization state 444 after reflection, which is converted to a polarization state orthogonal to direction 219 and absorbed.

[0359] Thus, rays 714, 715 pass through polarizers 218, 318 two or three times, thus modifying the spectral absorption rate.

[0360] Parallax barrier 700 is arranged to absorb the light incident thereon. Ray 410 from ambient source 604 is transmitted by polarizers 218, 318 and absorbed by barrier region 704. Ray 412 that passes through the barrier and is reflected can be absorbed by the barrier after reflection. Display 100 device can be used for ambient illumination 604, and parallax barrier 700 absorbs at least some of the ambient illumination rays 412 of ambient illumination 604 that are reflected from pixel layer 214 and transmitted through aperture 702.

[0361] There is a need to increase the spectral transmittance of display 100. Additionally, there is a need to increase the blue transmittance without degrading the appearance of the display reflection. Figure 1A

[0362] Figure 15 ​​It is a schematic diagram showing the change in output luminance with respect to wavelength in the case where the additional polarizer 318 is a broadband absorption polarizer and in the case where the additional polarizer 318 is a leakage absorption polarizer. Curve 870 shows the change in luminance transmitted by the parallel broadband polarizer; curve 872 shows the change in luminance transmitted by the parallel leakage polarizer; curve 874 shows the change in luminance transmitted by the crossed broadband polarizer; and curve 876 shows the change in luminance transmitted by the crossed leakage polarizer. The leakage polarizer 318 increases the leakage in the blue spectral band and increases the transmittance.

[0363] When crossed with a second conceptual polarizer of the same material, the transmittance of the output polarizer 218 and the additional polarizer 318 for wavelengths from 520 nm to 560 nm is less than the transmittance for wavelengths from 450 nm to 490 nm. The transmittance for wavelengths from 450 nm to 490 nm is greater than 1%, preferably greater than 2% and most preferably greater than 3%; and the transmittance for wavelengths from 520 nm to 560 nm is less than 3%, preferably less than 2% and most preferably less than 1%.

[0364] The operation of the display 100 when using a leakage polarizer will now be described. Figure 1A when using a leakage polarizer.

[0365] Figure 16A It is a schematic diagram showing the change in the transmittance of the polarizers 218, 318 with respect to wavelength for the broadband absorption polarizer and the leakage absorption polarizer and the spectral outputs 890R, 890G, 890B of the red, green, and blue emission pixels 220, 222, 224 with respect to the transmitted light ray 710. Figure 14 with respect to the transmitted light ray 710.

[0366] Curve 882 shows the spectral transmittance of an embodiment including the leakage polarizers 218, 318. Figure 1A of an embodiment including the leakage polarizers 218, 318.

[0367] By comparison with an embodiment of the present invention, curve 880 shows the spectral transmittance of an embodiment including the broadband absorption polarizers 218, 318. Advantageously, the embodiment of the present invention illustrated by curve 882 has a substantially higher transmittance in the red, green, and blue channels compared to an arrangement including the broadband polarizers 218, 318. Figure 1A compared to an arrangement including the broadband polarizers 218, 318.

[0368] Further comparison with embodiments of the present invention shows that curve 870 illustrates the spectral output of a display that includes a broadband absorption polarizer and a broadband reflectance control quarter-wave retarder, and does not include barrier 700, polar control retarder 300, or additional polarizer 318. Advantageously, the embodiment of the present invention illustrated by curve 882 has substantially the same blue light transmittance as a display that does not include additional polarizer 318. Efficient blue light emission provides a longer service life for the OLED display. Advantageously, the embodiments of the present invention achieve the same display life as a conventional display without an additional polarizer 318.

[0369] Figure 16B illustrates the variation of reflectance with the wavelength of broadband absorption polarizers 218, 318 and leakage absorption polarizers 218, 318 and the spectral outputs 890R, 890G, 890B of red, green, and blue emission pixels 220, 222, 224 with respect to the transmitted light Figure 14 and is a schematic diagram.

[0370] The reflectance is at least partially determined by Figure 14 the transmittance of light 440 in through polarizers 218, 318 after passing through reflectance-reducing quarter-wave retarder 228 and the absorption rate of parallax barrier 700.

[0371] Continuing with the illustrative embodiment of the first row of Table 4, the aperture ratio of the parallax barrier is 25%, such that Figure 14 the barrier absorption rate of light 410, 412 is 75%. Returning to the embodiment of Figure 14 including leakage polarizers 218, 318, curve 888 illustrates the average spectral transmittance of the display integrated in terms of viewing angle. Advantageously, a very low average reflectance can be provided by the display. As Figure 16A illustrated, the display efficiency is further increased.

[0372] Curve 884 illustrates Figure 14 the spectral transmittance of the display for light 440 transmitted and reflected by the holes 702 of parallax barrier 700. Compared with curve 876, curve 884 shows a significant improvement in extinction when the leakage at the peak blue spectral wavelength is less than 1%. Advantageously, a low reflectance is achieved.

[0373] Further comparison with embodiments of the present invention shows that curve 886 illustrates the spectral output of a display that includes a broadband absorption polarizer and a broadband reflectance control quarter-wave retarder, and does not include barrier 700, polar control retarder 300, or additional polarizer 318. This display achieves a low reflectance in a wide spectral range but reduces the spectral transmittance.

[0374] Further comparison with embodiments of the present invention shows that curve 876 illustrates the spectral output of a display that includes a leaky absorption polarizer and a broadband reflectance control quarter-wave retarder and does not include barrier 700, polarizer control retarder 300, or additional polarizer 318. This display achieves low reflectance over a broad spectral range. This display provides an undesirable reflectance of light, particularly in the blue and green portions of the spectrum. Thus, the leaky polarizers with spectral transmittance curves 872, 876 are not suitable for reflectance control in emissive displays.

[0375] The operation of embodiments including inorganic micro LEDs will now be described.

[0376] Figure 17A FIG. 7 is a schematic side view illustration of a switchable privacy display 100 for ambient lighting 604, including a micro LED emitting spatial light modulator 48, a parallax barrier 700, an output polarizer 218, and a reflection control quarter-wave retarder 228, a passive polarizer control retarder 380, a reflective polarizer 302, a switchable polarizer control retarder 300, and an additional polarizer 318 disposed on the output side of the spatial light modulator 48; and Figure 17B FIG. 9 is a front view illustration of Figure 17A the alignment of the optical layers in the optical stack. It can be assumed that the features of the arrangement of Figure 18A -B correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0377] Compared with OLED materials, the pixels 220, 222, 224 including inorganic micro LEDs can have a luminance greater than 10 3 lm / mm 2 ). To achieve the same brightness, the area of the micro LED pixels 220, 222, 224 can be significantly smaller than the area used for the OLED pixels 220, 222, 224. Due to the reduced use of monolithic semiconductor area, the other smaller micro LED pixels 220, 222, 224 are less costly. For example, for a pixel pitch of 50 microns in the direction of closest pixels, the micro LED can have a width or diameter of less than 5 microns.

[0378] There is a need to implement a common operating mode with high image visibility over a wide polar range and a privacy mode with a high level of visual security for off-axis snoops.

[0379] The pixel layer 214 may include a light absorbing material 227 to advantageously achieve a reduced reflectance compared to the typical reflective pixel layer of the Figure 1A OLED pixel layer 214.

[0380] Figure 17A is also different from Figure 1A in that it includes holes 702 having a circular shape. Advantageously, the symmetry of the transmittance curve can be increased.

[0381] Pixels 220, 222, 224 are arranged on a square grid instead of a rhombic grid. This arrangement reduces the brightness in the lateral direction while increasing the brightness in the quadrants. Advantageously, the visual security level in the privacy mode can be increased for small elevation angles, as described below.

[0382] In an embodiment (not shown), a display (not shown) including a mixture of OLEDs and micro-LED pixels can be provided. For example, blue micro-LEDs and green and blue OLED pixels can be provided. Advantageously, the blue lifetime can be increased without using color conversion for the micro-LEDs.

[0383] Figure 17C is a schematic diagram showing the arrangement of micro-LED emission pixels 220, 222, 224 and eye point positions for various polar viewing angles in a top view.

[0384] Figure 17D is a schematic diagram showing a passive polar control retarder 380 arranged between an output polarizer 218 and a reflective polarizer 302 in a side perspective view.

[0385] The passive polar control retarder 380 is arranged between the output polarizer 218 and the reflective polarizer 302. The passive polar control retarder 380 is capable of simultaneously performing the following operations: not introducing a net relative phase shift to the orthogonal polarization component of the light transmitted by the output polarizer 218 along the axis 199 normal to the plane of at least one polar control retarder 380, and introducing a relative phase shift to the orthogonal polarization component of the light transmitted by the reflective polarizer 302 along the axis 197 inclined to the normal of the plane of at least one polar control retarder 380.

[0386] At least one passive retarder 380 includes a retarder material 430 having an optical axis 431 perpendicular to the plane of the retarder. The at least one passive retarder 330 has a retardation for light with a wavelength of 550 nm in the range of -150 nm to -900 nm, preferably in the range of -200 nm to -500 nm, and most preferably in the range of -250 nm to -400 nm.

[0387] The operation of the passive polar control retarder 380 will be further described below with respect to Figure 19A -B.

[0388] It is necessary to optimize the spatial brightness uniformity of the display 100 including the micro-LED pixels 220, 222, 224.

[0389] Figure 18A FIG. 2 is a schematic view showing a spatial light modulator and the structure of an alignment parallax barrier including a vignetting parallax barrier hole in side view.

[0390] The hole 702 has an absorption rate, and at the edge of the hole 702, the absorption rate has a transmittance gradient, and the transmittance gradient has a transmittance gradient width ε greater than 1 μm, preferably greater than 2 μm, and more preferably greater than 3 μm.

[0391] In operation, the point emitter 720 within the pixel 222 emits a spherical wavefront 711 towards the hole 702. When the wavefront 711 is incident on the hole 702, the residual wavefront curvature causes near-field Fresnel diffraction, such that light rays 714 are provided at an unexpected angle in the far field.

[0392] In a parallax barrier having a hard edge such that the transmittance gradient width ε is less than 1 μm, such light rays can provide an undesired polar brightness variation from a point source and provide a visible uniformity variation that an observer can see over an area of the display 100.

[0393] In an illustrative micro-LED embodiment, the pixel pitch p can be 50 μm and the pixel width can be 3 μm. In an illustrative OLED embodiment, the pixel pitch p can be 50 μm and the pixel width can be 25 μm. In both arrangements, the hole 702 width a can be 16 μm. In a display having organic emitters such as those shown in Figure 1A the diffraction light rays are blurred due to convolution with a large pixel area. Advantageously, high display uniformity can be achieved. Due to the small size of the micro-LED emitters 220, 222, 224, the convolution blur in the OLED arrangement may be substantially greater than that in the micro-LED display.

[0394] In an embodiment of the present invention, the transmittance gradient width ε provides a diffraction apodization of the diffraction light rays 714, particularly for small emission regions such as micro-LEDs that do not provide a large amount of convolution blur. The brightness variation of the diffraction light rays 714 decreases with the decrease of the transmittance gradient width ε. Advantageously, the visibility of the spatial brightness variation on a display using the micro-LED pixels 220, 222, 224 is reduced.

[0395] The transmittance curves of various parallax barriers 700 will now be further described.

[0396] Figure 18B -D is a schematic view showing the variation of the parallax barrier transmittance with the position of the structure of various parallax barriers 700.

[0397] Figure 18BDescribe the first apodized transmittance curve 701 of the relative transmittance with respect to the position in the direction θ closest to the hole; wherein the absorption region 704 has 100% absorption. The slope can be formed by the thickness variation of the absorbing material and / or a halftone pattern across the width ε. Advantageously, the brightness variation across the display can be minimized. Within the width ε of the slope of curve 701, as referenced Figure 18A as described, the transmittance varies to apodize the output.

[0398] Figure 18C Describe the transmittance 705 of the absorption region 704 increased, for example, by controlling the thickness of the material used to form the absorption region 704. The absorption rate of the parallax barrier 700 region between the holes 702 is less than 100% and greater than 80%, preferably greater than 90% and more preferably greater than 95%. The transmittance 705 can be, for example, less than 5% or less than 2.5%. Advantageously, in the common operating mode, increased brightness can be provided at higher polar viewing angles.

[0399] Figure 18D Describe the transmittance of the absorption region 704 increased by, for example, Figure 2A the sub - hole region 722 as illustrated in. The average transmittance 705 across the light - absorbing region 704 can be, for example, less than 5% or less than 2.5%. Advantageously, in the common operating mode, increased brightness can be provided at higher polar viewing angles.

[0400] Now will describe Figure 17A the simulated output of the illustrative embodiment of.

[0401] Figure 19A is the component weights and output polar plot array of the arrangement of Figure 17A omitting the passive - polarizing control retarder 380, including the spatial light modulator 48 brightness, parallax barrier 700 transmittance, switchable retarder 300 transmittance, normalized switchable retarder 300 reflectivity, common - mode brightness, privacy - mode brightness, and polar plots of the visual safety level for a lux / nt ratio of 1.0; and Figure 19B is Figure 19A the component weights and output linear - graph array of the arrangement of.

[0402] Figure 19A The illustrative parallax barrier 700 and micro - LED pixel 220, 222, 224 parameters for - B in the direction closest to the pixel are provided in the first row of Table 5 for a pitch p of 50 μm. The pixels 220, 222, 224 are provided in a Figure 17C square - packed arrangement and provide square parallax - barrier 700 holes 702 (compared to the illustrated circular holes). The direction closest to the pixel is for an azimuth angle of 0 degrees.

[0403]

[0404] Table 5

[0405] Compared with Figure 11A the output of, the luminance curves from the micro-LED pixels 220, 222, 224 are shown as Lambertian, and thus provide a higher level of luminance at higher polar angles.

[0406] The polar output curve from the parallax barrier 700 has a high center output region and then slopes to 5% luminance at high polar angles using an arrangement such as Figure 2A . Advantageously, the common operating mode maintains the required image visibility at high viewing angles.

[0407] The slope of the luminance decay in the common mode is determined by the profile of the barrier edge, which is a hard edge in this illustrative embodiment. Figure 18A A soft-edge parallax barrier of -D can further achieve a smoother decay of the luminance curve in the common operating mode. Advantageously, the luminance uniformity for front use and the uniformity of the off-axis polar viewing region are improved.

[0408] In the privacy operating mode, a visual safety level greater than 4.0 is advantageously achieved for polar angles greater than 45 degrees and especially in the viewing quadrant. In other embodiments not shown, the visual safety level can be further increased by reducing the transmission level of the absorption region 704 of the parallax barrier 700.

[0409] Further luminance reduction may be required in the viewing quadrant.

[0410] Figure 19C is Figure 17A a polar plot array of the component weights and outputs of the arrangement, including the luminance of the spatial light modulator 48, the transmittance of the light absorption region 704 of the parallax barrier 700, the transmittance of the passive polar control retarder 380, the transmittance of the switchable retarder 300, the reflectance of the switchable retarder 300, the common mode luminance, the privacy mode luminance, and the polar plot of the visual safety level; and Figure 19D is Figure 19C a linear graph array of the component weights and outputs of the arrangement, including the linear curves at azimuth angles of 0, 90, 45, and 225 degrees. The characteristics of the display 100 are described in the second row of Table 5. The passive polar control retarder 380 reduces the luminance in the viewing quadrant. Advantageously, the visual safety level in the viewing quadrant can be improved.

[0411] By comparison with embodiments of the present invention, the simulated appearance of an arrangement that omits the parallax barrier 700 and the polar control retarder 380 will now be described. Figure 17A of the arrangement.

[0412] Figure 20Afor an illustrative arrangement in which the parallax barrier 700 is removed Figure 17A a polar plot array of component weights and outputs of the arrangement, including spatial light modulator 48 luminance, parallax barrier 700 light absorption region 704 transmittance, switchable retarder 300 transmittance, switchable retarder 300 reflectance, common mode luminance, privacy mode luminance, and a polar plot of the visual safety level; and Figure 20B is ​ a linear graph array of component weights and outputs of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees. The display 100 characteristics are described in the third row of Table 5.

[0413] In comparison with embodiments of the present invention, the polarizing control retarder 300 may not achieve the desired visual safety level in a display having a high off-axis luminance level, such as typically provided by a transmissive spatial light modulator 48 including micro LEDs in which no parallax barrier 700 is present.

[0414] Considering the linear polar graph of the visual safety level in the lateral (0 degree) direction at angles greater than 60 degrees, for almost all polar viewing angles, the VSL remains below 4.0 for 1.0 lux / nt. This arrangement provides undesirable visual security for off-axis snoops.

[0415] In comparison with embodiments of the present invention, the simulated appearance of an arrangement omitting the polarizing control retarders 300, 380 will now be described ​ of the arrangement

[0416] ​ for an illustrative arrangement in which the switchable retarder 300 and the passive polarization control retarder 380 are removed and the parallax barrier 700 provides transmission in the light absorption region 704 ​ a polar plot array of component weights and outputs of the arrangement; including spatial light modulator 48 luminance, parallax barrier 700 transmittance, switchable retarder 300 transmittance, switchable retarder 300 reflectance, common mode luminance, privacy mode luminance, and a polar plot of the visual safety level; and ​ is ​ a linear graph array of component weights and outputs of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees. The display 100 characteristics are described in the fourth row of Table 5. To achieve the desired image visibility in the common mode, the luminance at high polar viewing angles is 5%. However, the visual safety level is below 4.0 for all polar viewing angles and below 2.0 for most polar viewing angles. This display does not provide a satisfactory privacy operation mode.

[0417] ​an illustrative arrangement in which the switchable retarder 300 and the passive polarization control retarder 380 are omitted and the parallax barrier 700 provides no transmission in the light absorption region 704 ​ polar plot arrays of the component weights and outputs of the arrangement; including polar plots of spatial light modulator 48 luminance, parallax barrier 700 transmittance, switchable retarder 300 transmittance, switchable retarder 300 reflectance, common mode luminance, privacy mode luminance, and visual security level; and ​ is ​ linear graph arrays of the component weights and outputs of the arrangement, including linear graphs at azimuth angles of 0, 90, 45, and 225 degrees. The characteristics of the display 100 are described in the fifth row of Table 5. To achieve the desired visual security level in the privacy mode, the luminance at high polar viewing angles is 0%, i.e., the absorption region 704 is highly absorptive. However, for polar viewing angles greater than about 45 degrees, no image visibility is provided. This display does not provide a satisfactory common operating mode. Transmission levels between 0% and 5% do not provide a satisfactory compromise between the privacy operating mode and the common operating mode.

[0418] Advantageously, embodiments of the present invention achieve a high visual security level over a wide polar range in the privacy mode and high image visibility over a wide polar range in the common mode. In addition, high front image visibility is achieved in both the privacy and common operating modes.

[0419] Other arrangements of the polarization control retarder will now be described.

[0420] ​ is a schematic diagram illustrating the arrangement of the switchable retarder in the privacy mode in a perspective side view, where the switchable retarder includes a switchable LC layer having a horizontal alignment disposed between C-plate passive polarization control retarders 330A, 330B; and ​ is a schematic diagram illustrating the arrangement of the switchable retarder in the common mode in a perspective side view, where the switchable retarder includes a switchable LC layer having a horizontal alignment disposed between C-plate passive polarization control retarders 330A, 330B. It can be assumed that the features of the arrangement of -B correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features. Figure 22A -B

[0421] The retarders 330A, 330B may include substrates for the switchable liquid crystal layer 314. Advantageously, the thickness can be reduced. In addition, a flexible substrate can be provided. The display 100 can be provided in an active flexible embodiment (which can be bent by the user multiple times) or in a passive flexible embodiment (which can be bent during manufacturing) to achieve a free-form display profile.

[0422] Displays that operate in both landscape and portrait orientations for both privacy and public operating modes are required.

[0423] Figure 23A FIG. 4 is a schematic diagram showing the arrangement of a retarder layer disposed between parallel polarizers and including a 270-degree supertwist switchable liquid crystal retarder 301 disposed between quarter-wave plates. It can be assumed that the features of the arrangement of -C correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features. Other embodiments of a polarity control retarder that achieves a symmetric polarity distribution are described in U.S. Patent Publication No. 2020-0159055, which is incorporated herein by reference in its entirety. Figure 23A -C's arrangement features correspond to those with equivalent reference numerals as discussed above, including any potential variations in the features. Other embodiments of a polarity control retarder that achieves a symmetric polarity distribution are described in U.S. Patent Publication No. 2020-0159055, which is incorporated herein by reference in its entirety.

[0424] A first quarter-wave plate 296A and a second quarter-wave plate 296B are disposed between an additional polarizer 318 and an output polarizer 218. The first quarter-wave plate 296A is disposed on the input side of the second quarter-wave plate 296B and is arranged to convert the polarization state of linearly polarized light transmitted by the output polarizer 218 on its input side into a circularly polarized state. The second quarter-wave plate 296B on the output side is arranged to convert the polarization state of circularly polarized light incident thereon into a linearly polarized state transmitted by the additional polarizer 318 on its output side. At least one retarder 301 is disposed between the pair of quarter-wave plates 296A, 296B.

[0425] At least one polarity control retarder 300 includes a switchable liquid crystal retarder 301, which includes a liquid crystal material layer and electrodes arranged to apply a voltage to switch the liquid crystal material layer. The liquid crystal material layer has a 360-degree twist and has a retardation for light of a wavelength of 550 nm in the range of 1100 nm to 1400 nm, and most preferably in the range of 1150 nm to 1300 nm.

[0426] Now, an illustrative embodiment including Figure 23A a switchable polarity control retarder Figure 17A will be described with simulated outputs.

[0427] Figure 23B is a polar plot array of component weights and outputs of an arrangement that omits the passive polarity control retarder 380, including polar plots of spatial light modulator 48 brightness, parallax barrier 700 transmittance, switchable retarder 300 transmittance, normalized switchable retarder 300 reflectance, common mode brightness, privacy mode brightness, and visual safety level for a lux / nt ratio of 1.0; and Figure 17A is Figure 23C isFigure 23A Component ratio of the arrangement and the linear graph array of the output

[0428] The illustrative liquid crystal retarder 300 is described in Table 6. Figure 23B -C The illustrative parallax barrier 700 and OLED pixels 220, 222, 224 are described in Table 7 with a spacing p of 50 μm in the direction closest to the pixels. The pixels 220, 222, 224 are Figure 4 provided in a square packaging arrangement and provide square parallax barrier 700 holes 702. The direction closest to the pixels is for an azimuth angle of 0 degrees.

[0429]

[0430] Table 6

[0431]

[0432] Table 7

[0433] Advantageously, a rotationally symmetric privacy mode can be achieved compared to the laterally symmetric curves achieved by embodiments using a polarizing control retarder 300 (such as Figure 9 those).

[0434] Figure 24A is a schematic diagram showing the brightness appearance of the mobile device in the public mode in perspective view, including Figure 1A the display device 100 of and the polarizing control retarder 300 of FIG. 23, and its appearance is shown in the order clockwise from the upper left: front lateral, front longitudinal, top-down longitudinal, and right-side view lateral.

[0435] The viewing direction along the axis 199 of the display device 100 is perpendicular to the viewing surface of the display device 100. In all the shown orientations, in the public mode, the image emitted by the display device 100 is visible to the observer, as represented by the white color representing the image emitted by the display device 100. The image is visible in the lateral and longitudinal orientations 520 on all axes, the top-down longitudinal orientation 522, and the right-side view lateral orientation 528.

[0436] Figure 24B is a schematic diagram showing the brightness appearance of the mobile device in the privacy mode in perspective view, including Figure 1A the display device 100 of and the switchable polarizing control retarder 300 of FIG. 23, and its appearance is shown in the order clockwise from the upper left: front lateral, front longitudinal, top-down longitudinal, and right-side view lateral.

[0437] In the privacy mode, the observer's field of view remains unchanged in the on-axis horizontal and vertical orientations 520, and the image emitted by the display device 100 is visible to the observer. However, in the top-down vertical orientation 522 and the right-side horizontal orientation 528, the image emitted by the display device is no longer visible. Instead, a snooper viewing from a wide angle observes the mirror-like surface provided by the reflective polarizer 302 as described above.

[0438] Figure 24C FIG. is a schematic diagram illustrating the reflectivity appearance of a mobile device in privacy mode, including Figure 1A display device 100 of and the switchable polarization control retarder 300 of FIG. 23, whose appearance is shown in clockwise order from the upper left: front horizontal, front vertical, top-down vertical, and right-side horizontal.

[0439] In the privacy mode, due to the minimum reflectivity from the additional polarizer 318, the observer's field of view remains unchanged in the on-axis horizontal and vertical orientations 520. However, in the top-down vertical orientation 522 and the right-side horizontal orientation 528, the reflection from the surface of the additional polarizer 318 can produce a front-end reflection as described above, thereby ideally increasing the visual safety level VSL.

[0440] Figure 25A FIG. is a schematic diagram illustrating a motor vehicle 600 having a switchable directional display 100 disposed within a vehicle cockpit 602 in a night operation mode.

[0441] The night mode of the switchable directional display 100 can correspond to the privacy mode discussed above. The light cone 620 (e.g., representing a light cone with a brightness greater than 50% of the peak brightness emitted by the switchable directional display 100) can indicate the angular range within which the image emitted by the switchable directional display 100 is distinguishable. As Figure 25A shown, when the switchable directional display 100 is in the night mode, the driver 604 is within the area defined by the light cone 620 in the horizontal direction, and the image emitted by the switchable directional display 100 is thus distinguishable to the driver 604. In contrast, the high-angle light rays 622 falling outside the light cone 620 in the horizontal direction have a reduced brightness, and thus the image emitted by the switchable directional display 100 may not be distinguishable to the passengers 608 in the vehicle 600. This can be advantageous if the passengers are trying to sleep or relax at night.

[0442] In this arrangement, if the visibility of a certain image to other users is acceptable, the reflective polarizer 302 can be omitted. Advantageously, the display efficiency can be increased and the visibility of stray light can be reduced.

[0443] Figure 25BFIG. 0 is a schematic view of a motor vehicle 600 having a switchable directional display 100 disposed within a vehicle cockpit 602 in a night operation mode, as viewed from above.

[0444] In the night mode, the volume 606 occupied by the driver's face is within the region defined by the light cone 620 in the vertical direction, and thus the image emitted by the switchable directional display 100 is distinguishable to the driver within the volume 606. However, the high-angle light rays 622 that fall outside the light cone 620 in the vertical direction may have reduced brightness in the night operation mode. The brightness of the high-angle light rays 622 that can be reflected from the windshield 618 of the motor vehicle 600 can be reduced. This can advantageously reduce the reflection of the display 100 perceived by the driver on the windshield 618 within the volume 606.

[0445] Increased uniformity is required for the rotation of the display 100 about the horizontal axis, and the alignment tolerance between the parallax barrier 700 and the pixel layer 214 is relaxed.

[0446] Figure 26 FIG. 10 is a schematic view of a switchable privacy display 100 for ambient lighting 604, as viewed from a side perspective, including an OLED emissive spatial light modulator 48, a one-dimensional parallax barrier 700, an output polarizer 218, and a reflective control quarter-wave retarder 228, a reflective polarizer 302, a switchable polarity control retarder 300, and an additional polarizer 318 disposed on the output side of the spatial light modulator 48; and Figure 27 FIG. 12 is a front view illustration Figure 26 of the alignment of the optical layers in the optical stack. It can be assumed that the features of the Figures 26 - 27 arrangement not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0447] The polarity control retarder 300 is illustrated in Figure 22A -B.

[0448] The parallax barrier 700 forms a one-dimensional array of holes 702, and the pixels 220, 222, 224 are arranged in columns, with each column of pixels 220, 222, 224 aligned with a corresponding hole.

[0449] The pixels 220, 222, 224 have light-emitting regions that extend in the direction in which the holes 702 extend; the widths of the red, green, and blue light-emitting regions are the same for each pixel 220, 222, 224; and the heights of the light-emitting regions are different for the red, green, and blue light-emitting pixels 220, 222, 224.

[0450] Advantageously, a switchable privacy display can have high image visibility for off-axis users in the landscape direction and high visual security for off-axis snoops in the landscape direction, respectively, in a public mode and a privacy mode. The viewing freedom of rotation about the horizontal axis can be increased. Advantageously, the front user position can be conveniently adjusted with high luminance uniformity in the elevation angle direction.

[0451] In addition, compared with an arrangement in which alignment is controlled on the lateral, vertical, and orientation axes Figure 1A the alignment of the parallax barrier 700 with the pixel layer can be controlled on the lateral and orientation axes. Advantageously, the yield can be increased and the cost can be reduced.

[0452] There is a need to increase the efficiency of the display 100 while providing a low reflectance of light from the reflective pixel layer 214.

[0453] Figure 28 FIG. 12 is a schematic side view illustration of a switchable privacy display 100 for ambient lighting 604, including a micro-LED emitting spatial light modulator 48, a parallax barrier 700, and an output polarizer 218 as a reflective polarizer 302, a reflective control quarter-wave retarder 228, a switchable polarity control retarder 300, and an additional polarizer 318 disposed on the output side of the spatial light modulator 48; and Figure 29 FIG. 13 is a side view illustration of the reflection of ambient light in the display 100 of Figure 28 It can be assumed that the features of the arrangement not further discussed in detail Figures 28 - 29 correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0454] Compared with Figure 1A and 17A the arrangement of, reflective output polarizers 218, 302 are provided. The absorptive polarizer 218 is omitted, such that advantageously the transmittance of the display is increased, thereby achieving increased luminance and reduced power consumption for the desired image brightness.

[0455] Compared with Figure 14 the embodiment of, light rays 760 from the ambient light source 604 have a polarization state that is substantially reflected from the reflective output polarizers 218, 302 to provide light rays 762 that are absorbed by the absorptive regions 704 of the parallax barrier 700. Light rays 764 transmitted by the reflective polarizers 218, 302 are absorbed by the polarizer 318. Advantageously, the reflection of the ambient light 760 is reduced.

[0456] There is a need to provide a low-reflectance display with high efficiency.

[0457] Figure 30A schematic diagram showing a low-reflectivity display 200 for ambient lighting 604 in a perspective side view, including an OLED emitting spatial light modulator 48, a two-dimensional parallax barrier 700, a leakage output polarizer 218, and a reflection control quarter-wave retarder 228 disposed on the output side of the spatial light modulator 48; and Figure 31 is a side view showing Figure 30 the reflection of ambient light in the display 200 of. It can be assumed that the features of the Figures 30 - 31 arrangement not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0458] The reflectivity control display 200 device for ambient lighting includes the display 200, wherein the parallax barrier 700 absorbs at least some of the ambient lighting 604.

[0459] Compared with Figure 1A the arrangement of, the display 200 does not provide a privacy display 100. For example, the output can be provided as illustrated in Figure 21A -B and in the illustrative embodiment of the fourth row of Table 5, such that the aperture ratio of the holes 702 is 25% and the transmittance of the absorption region 704 of the parallax barrier 700 is 5%. The polarizer 218 includes, for example Figure 15 the leakage polarizer as illustrated in. Advantageously, the output efficiency in the front direction is increased compared with the arrangement with a high extinction type polarizer.

[0460] A touch sensor for the low-reflectivity display 200 needs to be provided.

[0461] Figure 32 A schematic diagram showing a touch screen low-reflectivity display 200 for ambient lighting 604 in a perspective side view, including an OLED emitting spatial light modulator 48, a two-dimensional parallax barrier 700 including a touch sensor electrode layer, a leakage output polarizer 218, and a reflection control quarter-wave retarder 228 disposed on the output side of the spatial light modulator 48; Figure 33 is a front view showing Figure 32 the reflection of ambient light in the display 200 of; and Figure 34 is a side view showing Figure 32 the structure of. It can be assumed that the features of the Figures 32 - 34 arrangement not further discussed in detail correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0462] An array of holes 702 is formed on the touch sensor electrode array 500. The position of the finger 25 at or near the protective cover layer 320 is detected by the touch electrode arrays 500, 502, the touch drivers 452, 454, and the touch control system 450. The touch electrode array 500 may be formed on the surface of the parallax barrier 700 or on the surface of the quarter-wave retarder.

[0463] The pair of touch electrode arrays 500, 502 are arranged in layers separated by a dielectric layer 504. The dielectric layer 504 is arranged between the switchable liquid crystal layer 314 and the additional polarizer 318. The first touch electrode array 500 and the second touch electrode array 502 are arranged on the dielectric layer 504 and on opposite sides of the dielectric layer 504.

[0464] The touch electrode arrays 500, 502 are arranged between the pixel layer 214 and the parallax barrier 700, or as Figure 32 illustrated, arranged between the parallax barrier 700 and the quarter-wave reflection control retarder 228.

[0465] The touch input display device 100 further includes a control system 450, wherein the control system 450 is arranged to address the touch electrode arrays 500, 502 for capacitive touch sensing.

[0466] The control system 450 is further arranged to address the SLM 48. The control system includes a system controller, which is arranged to control the application to and measurement from the touch electrode arrays 500, 502 via the touch drivers 452, 454.

[0467] The electrodes 500, 502 are arranged between the holes 702 of the parallax barrier. Advantageously, high efficiency can be achieved.

[0468] In other embodiments as Figure 34 illustrated, at least one absorption region 704 of the parallax barrier 700 includes the touch sensor electrode array 502. Advantageously, the touch sensor electrode arrays 500, 502 can have a reduced reflectivity. In addition, touch electrodes 504 can be provided at the pixel layer 214.

[0469] In other embodiments (not shown), the touch sensing electrode layer may be arranged at the pixel layer 214. Advantageously, the control of the sensing electrodes can be provided together with the control of the pixel data, thereby reducing cost and complexity.

[0470] It is further necessary to achieve increased transmission efficiency.

[0471] Figure 35AA schematic diagram showing a low-reflectivity display 200 for ambient lighting 604 in a perspective view from the side, including an OLED emissive spatial light modulator 48, a two-dimensional parallax barrier 700, and an output polarizer not arranged on the output side of the spatial light modulator; and Figure 35B is a side view showing Figure 35A the reflection of ambient light in the display 200 of Figure 35A -B. It can be assumed that the features of the arrangement not further discussed in detail

[0472] correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features. Figure 30 Compared with the embodiment of

[0473] the output polarizer 218 is omitted. Advantageously, the efficiency is increased.

[0474] Ambient light rays 410, 412 are absorbed by the absorption region 704, while the output light rays 710 in the normal direction are transmitted without loss. High-angle light rays 712 from the pixels 220 are further absorbed. Thus, some ambient light is absorbed, thereby advantageously increasing the image contrast.

[0474] It is necessary to further reduce the reflectivity of ambient light.

[0475] Figure 36A A schematic diagram showing a low-reflectivity display for ambient lighting in a perspective view from the side, including an OLED emissive spatial light modulator, two one-dimensional parallax barriers 700A, 700B, and an output polarizer not arranged on the output side of the spatial light modulator 48; and Figure 36B is a side view showing Figure 36A the reflection of ambient light in the display of Figure 36A -B. It can be assumed that the features of the arrangement not further discussed in detail

[0476] The barriers 700A, 700B can be arranged on separate substrates 216A, 216B that provide the spacing of the barriers. Light can be trapped within the substrate 216B and absorbed.

[0477] Compared with the embodiment of Figure 35A -B, the alignment tolerances of each of the barriers 700A, 700B can be relaxed, thereby increasing the yield and reducing the cost. In addition, additional high light rays 713 can be absorbed, thereby reducing the leakage between pixels. Advantageously, the image contrast can be increased.

[0478] It may be necessary to reduce the off-axis light from the emitting pixels and increase the efficiency in the forward direction.

[0479] Figure 37AFIG. 0 is a schematic diagram showing, in side view, an array of reflective-refractive optical elements disposed between pixels 220, 222, 224 of a spatial light modulator 48 and a parallax barrier 700; and Figure 37B FIG. Figure 37A is a schematic diagram showing the variation of the output luminance with the Figure 37A polar angle of the arrangement of Figure 37A The features of the arrangement of

[0480] not further discussed in detail may be assumed to correspond to features with equivalent reference numerals as discussed above, including any potential variations in the features. The reflective-refractive optical elements for an emissive display are described in WIPO Publication No. WO 2019 / 138243 (Attorney Docket No. 442002), which is incorporated herein by reference in its entirety.

[0481] A reflective-refractive optical structure 800 is aligned with emissive pixels 220, 222, 224 to provide a directional light output distribution from the spatial light modulator 48 that is similar to the Figure 11A or Figure 19A directional light output distribution illustrated in. The reflective-refractive optical structure 800 includes a plurality of reflective-refractive optical elements 838 disposed in an array of reflective-refractive optical elements. Each of the plurality of reflective-refractive optical elements 838 in the plurality of reflective-refractive optical elements 800 is correspondingly aligned with one or more of the pixels of the plurality of pixels 220, 222, 224, and each of the pixels of the plurality of LEDs is aligned only with a corresponding one of the reflective-refractive optical elements 838 of the reflective-refractive optical structure 800.

[0482] Each of the plurality of reflective-refractive optical elements 838 includes a first cross-sectional outer interface 804A and a second cross-sectional outer interface 804B facing the first cross-sectional outer interface 804A in at least one reflective-refractive cross-sectional plane passing through its optical axis 199.

[0483] The first cross-sectional outer interface 804A and the second cross-sectional outer interface 804B each include a curved interface that includes a first outer interface region 840 and a second outer interface region 842.

[0484] The first cross-sectional outer interface 804A and the second cross-sectional outer interface 804B extend from a first end of the reflective-refractive optical element 838 to a second end of the reflective-refractive optical element 838, and the second end of the reflective-refractive optical element 838 faces the first end of the reflective-refractive element.

[0485] The distance between the first and second cross-sectional outer interfaces at the first end of the reflective-refractive optical element located at the pixel layer is less than the distance between the first and second cross-sectional outer interfaces 804A, 804B at the second end of the reflective-refractive optical element 838 at the output side of the reflective-refractive optical element 838.

[0486] At least one transparent internal interface 810 is disposed between the first and second ends and between the first and second external interfaces 804A, 804B.

[0487] The reflective refraction optical structure 838 includes: (i) a first transparent non-gaseous material having a first refractive index, which is disposed between the first and second cross-sectional external interfaces and the at least one transparent internal interface and between the first and second ends of each of the reflective refraction optical elements; (ii) a second transparent non-gaseous material having a second refractive index less than the first refractive index, which is disposed between the corresponding aligned pixels 220, 222, 224 and the transparent internal interfaces of each of the reflective refraction optical elements; (iii) a third transparent non-gaseous material having a third refractive index less than the first refractive index, which is disposed between the first cross-sectional external interface of the first reflective refraction optical element and the second cross-sectional external interface of an adjacent reflective refraction optical element among the plurality of reflective refraction optical elements, and between the first and second ends of each of the reflective refraction optical elements.

[0488] The tilt angle of the optical axis 199 with respect to the interface normal of each of the first cross-sectional external interface 804A and the second cross-sectional external interface 804B varies continuously as the distance c from the first end towards the second end. The derivative of the tilt angle with respect to the distance ξ from the optical axis 199 has a discontinuity at the boundary 844 between the corresponding first and second external interface regions 840, 842 of the first and second cross-sectional external interfaces 804A, 804B.

[0489] The materials 802, 814 can be transparent and are conveniently provided in the layer 800, thereby reducing manufacturing costs and complexity.

[0490] Embodiments of the present invention achieve encapsulation of OLED pixels through a solid reflective refraction optical element 838 having interfaces 804A, 804B, which are arranged to advantageously achieve directional illumination with a low level of crosstalk to snoopers. Figure 37B The curve 850 of can be provided by the illustrative embodiments of Table 8.

[0491]

[0492] Table 8

[0493] Most of the main light rays 820 in the second external interface region 842 are guided by total internal reflection in a direction close to parallel to the optical axis 199, thereby providing a high level of collimation for the light rays reflected from the outer surfaces 804A, 804B. The light rays 822 incident on the region 840 are guided in a direction close to but different from the collimation direction of the known low-cost materials in the solid reflective refraction optical element 38.

[0494] Advantageously, losses are reduced and the efficiency of the on-axis light is increased.

[0495] In other embodiments, the interface 804 may be provided by a metal surface to provide some collimation of the output light.

[0496] It is desirable to reduce the number of light rays at higher polar angles. The absorption region 704 of the parallax barrier 700 may be arranged to reduce the brightness at higher polar angles.

[0497] In other embodiments, the shapes of the surfaces 804A, 804B may be arranged to provide controlled light rays at high polar angles to achieve increased brightness at higher polar angles, such as between 2.5% and 15% of the front brightness. A common-mode brightness with high image visibility may be provided. The polarizers 218, 318 and the polarity control retarder 300 may be arranged to achieve switching between the common mode and the privacy mode. Other pixels may be arranged on the pixel layer between the reflective refractive optical elements 838 to achieve increased light at high polar angles, as described in WO 2018 / 185475 (Agent Ref. No. 439002), which is incorporated herein by reference in its entirety.

[0498] A method of manufacturing a display device embodying the present invention will now be described.

[0499] Figure 38A -D is a schematic view showing a method of manufacturing the parallax barrier 700 of the emissive displays 100, 200 using a fine metal mask 900 in a side view.

[0500] Figure 38A It is illustrated that in a first step, an array of emissive pixels 220, 222, 224 is formed on the backplane by guiding the emissive material 802 through a fine metal mask. For example, the structure of the pixels 220, 222, 224 is further described in Figure 6 The structure of the pixels 220, 222, 224 is further described in.

[0501] Figure 38B It is illustrated that in a second step, an inorganic layer 752 and an organic layer 750 are added to provide the substrate 216 as an encapsulation layer for the pixel layer 214. The step of forming the encapsulation layer on the array of emissive pixels 220, 222, 224 thus includes forming at least one transparent inorganic layer 752. The at least one transparent inorganic layer may be a glass layer. By chemical mechanical polishing of a thicker glass layer, the glass layer may have an appropriate thickness d. The organic layer 750 may be omitted. An adhesive layer 244 may be provided between the pixel layer 214 and the substrate 216.

[0502] Figure 38CIt is described that a parallax barrier 700 including an array of holes 702 is formed on the surface of the encapsulation layer substrate 216 by guiding a light-absorbing material 903 through a fine metal mask 904. The mask 904 can be the same as the mask 900. The alignment of the mask 904 is shifted in the lateral position relative to the alignment of the mask 900 to achieve the alignment of the holes 702 with the centers of the pixels 220, 222, 224.

[0503] Figure 38D It is described that the barrier is formed on the layer 216 before layers such as other encapsulation layers, a reflection-reducing retarder 228, polarizers 218, 318, and a polarity control retarder 300 are arranged on the parallax barrier.

[0504] Advantageously, similar devices and masking techniques used to form the pixels 220, 222, 224 can be used to form the parallax barrier 700. The cost of applying the parallax barrier 700 can be advantageously reduced.

[0505] The pixels 220, 222, 224 have a pitch p along the direction closest to the holes 702, the material between the parallax barrier 700 and the pixels 220, 222, 224 has an overall refractive index n, and the encapsulation layer has a thickness d that satisfies the requirements The holes 702 have a width a along the direction closest to the holes 702, the material between the parallax barrier 700 and the pixels 220, 222, 224 has an overall refractive index n and the encapsulation layer has a thickness d that satisfies the requirements and preferably satisfies the requirements of the thickness d.

[0506] The parallax barrier needs to be provided by high-precision lithography.

[0507] Figure 39A -F is a schematic view showing a method of manufacturing a parallax barrier 700 of an emissive display using lithography in a side view.

[0508] A method of forming a display device includes the following steps: forming an array of emissive pixels 220, 222, 224 on a backplane by guiding an emissive material through a fine metal mask, the fine metal mask forming an encapsulation layer including at least one transparent inorganic layer on the array of emissive pixels 220, 222, 224; forming a parallax barrier 700 including an array of holes 702 on the surface of the encapsulation layer by lithographic patterning.

[0509] In the first and second steps, an emissive display is provided as illustrated in Figure 38A -B.

[0510] Figure 39A It is described that in the third step, a barrier material 904 is formed on the upper surface of the layer 216.

[0511] Figure 39B It is illustrated that in the fourth step, the photolithography masking material 906 is disposed on the upper surface of the material 904.

[0512] Figure 39C It is illustrated that in the fifth step, the photomask 908 is aligned with the pixels 220, 222, 224 and exposed to the UV radiation 910.

[0513] Figure 39D It is illustrated that in the sixth etching step, the material 904 is removed.

[0514] Figure 39E It is illustrated that in the seventh step, the photolithography material is removed.

[0515] Figure 39F It is illustrated the final device after adding another encapsulation layer.

[0516] Advantageously, a high-resolution and accurately aligned parallax barrier can be provided, thereby reducing costs and complexity and providing the highest brightness in the normal direction aligned with the axis 199.

[0517] It may be necessary to provide the parallax barrier on a separate layer and align it with the spatial light modulator 48.

[0518] Figure 40A -D is a schematic view illustrating a method of using printing to fabricate the parallax barrier 700 of the emissive displays 100, 200 in a side view.

[0519] Figure 40A It is illustrated that a printing method such as inkjet printing, photolithography, flexographic printing or other known printing techniques can be used to provide the parallax barrier 700 to apply the absorbing material to the region 704. The parallax barrier 700 can be disposed on the substrate 110.

[0520] Figure 40B It is illustrated that the parallax barrier can be aligned with the pixel layer 214. The material 246 is input into the gap between the substrate 216 and the parallax barrier 700.

[0521] Figure 40C It is illustrated the device structure after curing the adhesive material 246.

[0522] Figure 40D It is illustrated that the substrate 110 is thinned, for example, by chemical mechanical polishing of the substrate 110.

[0523] Advantageously, the parallax barrier can be formed after fabricating the emissive display.

[0524] It can be assumed that Figure 38A -D, Figure 39A -F and Figure 40AThe features of the -D arrangement correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0525] There is a need to provide an emissive privacy display with increased frontal efficiency and reduced off-axis brightness.

[0526] Figure 41 FIG. is a schematic side view illustrating a switchable privacy display 100 for ambient lighting, including an OLED emissive spatial light modulator 48 containing tangible OLED pixels 220, 222, 224, an output polarizer 218, and a reflective control quarter-wave retarder 228, a reflective polarizer 302, a switchable polarity control retarder 300, and an additional polarizer 318 disposed on the output side of the spatial light modulator 48; and Figure 42 FIG. is a schematic side view illustrating a pixel of the OLED emissive spatial light modulator 48, wherein the OLED pixels 220, 222, 224 are tangible OLED pixels including a tangible well 272 and a high refractive index filling material 270. It is assumed that Figures 41 - 42 the features of the arrangement correspond to the features with equivalent reference numerals as discussed above and below, including any potential variations in the features.

[0527] The structure and operation of one of the pixels 220 will now be described.

[0528] Figure 43 FIG. is a schematic side view illustrating a pixel of the OLED emissive spatial light modulator, wherein the OLED pixel includes a tangible well 272 and a high refractive index filling material 270. The pixel 220 is driven by a pixel circuitry 249 including electrodes 243, 245 and layers 241, 251, 253 including semiconductors and dielectrics to provide transistors, capacitors, and other drive circuitry elements. As Figures 6 - 7 illustrated in, a via 242 is arranged to connect to an electrode 234, which in turn contacts a rear reflector 240, which can be, for example, a silver electrode. An electron transport layer 236, an emissive layer 232, a hole transparent electrode layer 238, and a transparent electrode 244 are disposed on the electrode 234 to implement the emissive pixel 220.

[0529] The pixel 220 has a well profile 272 and may further have a planar surface or a curved surface, the well profile having a central region 273 that can be substantially planar and a sloped inclined region 271.

[0530] The filling material 270 is disposed between the inclined regions 271. The filling material can have, for example, a refractive index of approximately 1.8. The refractive index of the filling material can be similar to the refractive index of the emissive layer 232 material.

[0531] In operation, light is provided by source 269, which has an angular distribution of luminous intensity determined by the wavelength, reflection of the reflective layer, interference between coherent wavefronts, guiding within the layer, and surface plasmon absorption in the metal layer. Such propagation characteristics are commonly referred to as the microcavity emission effect.

[0532] In an embodiment of the present invention, the light ray 276 emitted towards the normal direction is directly output without being incident on the outer region 271 of the pixel 220. The light ray 274 is output after being incident on the reflective layer of the inclined region 271. The light ray 276 is guided within the filling material 270 and output after being incident on the inclined region 271.

[0533] Advantageously, the light rays 274 and 276 that would be lost by guiding in the cover layer 246 are guided in the forward direction. Compared with the arrangements described elsewhere, the parallax barrier 700 can be omitted and the cost can be reduced. In other embodiments, Figures 41 - 43 the tangible pixels not shown and the parallax barrier 700 can be provided. Advantageously, the efficiency is increased and the off-axis visual safety level is increased for the privacy operation mode.

[0534] Returning to Figure 42 , for the red, green, and blue pixels 220, 222, 224, the profile of the inclined region 271 may be different. Such differences can compensate for the different color attenuations of the microcavity interference effect. Advantageously, the color uniformity can be improved.

[0535] Figure 44 is a schematic diagram illustrating the variation of the luminous intensity of the tangible and intangible OLED pixels. Compared with the curve of luminance versus polar angle, a curve of luminous intensity versus azimuth angle is provided. Thus, the Lambertian output curve 280 has a cosθ curve. Curves 282 for conventional OLED pixels and the desired curves 284 and 286 that can be provided by the tangible pixel 220 with the inclined region 271 are provided. Ideally, the luminous intensity at a polar angle of at least 45 degrees is less than 15% of the maximum luminous intensity, and preferably less than 10% of the maximum luminous intensity. In addition, the maximum luminous intensity at a polar angle of at least 60 degrees is less than 7.5% of the maximum luminous intensity, and preferably less than 5% of the maximum luminous intensity.

[0536] Figure 45A is Figure 41 a polar plot array of the component weights and outputs of the arrangement, including Figure 44 the spatial light modulator luminance, switchable retarder transmittance, switchable retarder reflectance, common mode luminance, privacy mode luminance, and polar plot of the visual safety level of the luminous intensity curve 286 in Figure 45B is Figure 45AGraphs of the component weights and output linearity of the arrangement, including linear curves at azimuth angles of 0, 90, 45, and 225 degrees.

[0537] The physical OLED pixels 220, 222, 224 are arranged to provide increased front brightness and reduced off-axis brightness. Advantageously, the visual security level is increased for off-axis snoops in the privacy operation mode. Additionally, the output efficiency is increased for front users.

[0538] There may be a need to provide a display that provides privacy features in both landscape and portrait operation modes.

[0539] Figure 46 Is a schematic side perspective view of a switchable privacy display device 100 for ambient lighting 604, including an emissive spatial light modulator 48, a parallax barrier 700, a first polarization control retarder 300A disposed between the display polarizer 218 of the emissive spatial light modulator 48 and a first additional polarizer 318A; and a reflective polarizer 302 and a second polarization control retarder 300B disposed between the first additional polarizer 318A and a second additional polarizer 318B.

[0540] Figure 47A Is a front perspective view illustration for Figure 46 Is a schematic view of the arrangement of polarizers and polarization control retarders for an embodiment of, where the first and second polarization control retarders cross and the spatial light modulator includes a parallax barrier 700. In this embodiment, the liquid crystal alignment in the switchable polarization control retarder 301A is provided by a vertical alignment layer having an alignment direction 419AAz with a pretilt direction 419AAy and a horizontal alignment layer having a pretilt direction 419AB, where the directions 419AAy, 419AB are antiparallel; and the liquid crystal alignment in the switchable polarization control retarder 301B is provided by a vertical alignment layer having an alignment direction 419BAz with a pretilt direction 419BAy and a horizontal alignment layer having a pretilt direction 419BB, where the directions 419BAy, 419BB are antiparallel and the directions 419AAy, 419AB are perpendicular to the directions 419BAy, 419BB.

[0541] It can be assumed that the features of the embodiments not further discussed in detail Figure 47A Correspond to the features with equivalent reference numerals as discussed above, including any potential variations in the features.

[0542] Figure 47B Is a graph illustrating the simulated polarization curves of the brightness output of an emissive spatial light modulator without a Figure 46 Barrier structure 700.

[0543] Figure 47CIt is a graph showing the simulated polarization curve of the transmittance of the barrier structure of FIG. 2 that describes the light from the pixels of the emission spatial light modulator. Illustrative examples are provided in Table 9, where the emission spatial light modulator 48 and the aligned parallax barrier 700 have an output luminance curve with a full width at half maximum of up to 40 degrees.

[0544] Parameter, x - axis direction Explanatory value Pixel 224 pitch 20 microns Pixel 224 emission width 10 microns Barrier hole 702 width 10 microns Barrier spacing, d 20 microns

[0545] Table 9

[0546]

[0547] Table 10

[0548] Figure 47D It is to illustrate the Figure 47A and the simulated polarization curve of the transmittance of the second polarization control retarder in Table 10 arranged between the first and second additional polarizers, where the transmission directions of the electric vectors of the polarizers are parallel; Figure 47E It is to illustrate the Figure 47A and the simulated polarization curve of the reflectance of the second polarization control retarder in Table 10 arranged between the reflective polarizer and the second additional polarizer, where the transmission directions of the electric vectors of the polarizers are parallel; Figure 47F It is to illustrate the Figure 47E and the simulated polarization curve of the total reflectance including the Figure 47G reflectance in Table 10 and the Fresnel reflectance from the front surface of the display device; Figure 47A It is to illustrate the Figure 47H and the simulated polarization curve of the transmittance of the first polarization control retarder in Table 10 arranged between the display polarizer and the first additional polarizer, where the transmission directions of the electric vectors of the polarizers are parallel; and Figure 47A It is a graph showing the simulated polarization curve of the logarithm of the total output luminance of the

[0549] Figure 47I It is to illustrate the Figure 47A spatial light modulator and the first and second polarization control retarders in Table 9 and Table 10.

[0550] Figure 47J It is to illustrate the Figure 47A, graphs of the simulated polarization curves of the safety level S for the ambient illuminance measured in lux for the arrangements of Tables 9 and 10, where the ambient illuminance is twice the front display luminance measured in nits. In the public mode, the output is determined by multiplying curve 47B by curve 47C. Figure 47J The safety factor is illustrated in Figure 47J . Advantageously, the safety factor S is less than 0.1 over a wide range of polar angles, such that the image can be clearly seen on the display.

[0551] As an alternative to the embodiment of Table 10, the retardation and alignment layers of the first and / or second polarization control retarders 301A, 301B can be provided by two horizontal alignment layers or two vertical alignment layers. Compared to the arrangement of Table 10, the polarization range of the high safety factor and the resilience to applied pressure can be modified to achieve the desired alternative characteristics.

[0552] As can be used herein, the terms “substantially” and “about” provide an industrially acceptable tolerance for the correlation between their corresponding terms and / or items. Such an industrially acceptable tolerance ranges from zero percent to ten percent and corresponds to, but is not limited to, component values, angles, etc. The range of such correlation between items is between approximately zero percent and ten percent. As can be used herein, the term describing “the direction closest to the hole” refers to the direction in which the minimum distance between holes extends. Similarly, as can be used herein, the term describing “the direction closest to the pixel” refers to the direction in which the minimum distance between pixels extends.

[0553] Although various embodiments in accordance with the principles disclosed herein have been described above, it should be understood that these embodiments are presented by way of example only and not limitation. Accordingly, the breadth and scope of the present disclosure should not be limited by any of the above-described exemplary embodiments, but should be defined only in accordance with any issued claims and their equivalents. Further, the above advantages and features are provided in the described embodiments, but the application of such issued claims should not be limited to the processes and structures for achieving any one or all of the above advantages.

[0554] In addition, the section headings provided herein are for consistency with the recommendations under 37 CFR 1.77 or to provide organizational cues. These headings should not limit or characterize the embodiments set forth in any claims that may be issued from this disclosure. Specifically and by way of example, although the heading refers to the "Technical Field", the claims should not be limited by the language selected under the heading to describe the so-called field. Further, the technical descriptions in the "Background Art" should not be construed as an admission that certain techniques are prior art to any embodiments in this disclosure. The "Summary of the Invention" is also not considered a characteristic of the embodiments set forth in the issued claims. Additionally, any reference to the singular form of the "invention" in this disclosure should not be used to argue that there is only a single novel point in this disclosure. Multiple embodiments may be set forth in accordance with the limitations of the multiple claims issued from this disclosure, and such claims correspondingly define the embodiments protected thereby and their equivalents. In all cases, the scope of these claims should be considered in accordance with the merits of this disclosure on its own, but should not be limited by the headings set forth herein.

Claims

1. A display device, the display device comprising: An emissive spatial light modulator, the emissive spatial light modulator comprising an array of pixels arranged in a pixel layer; A parallax barrier, the parallax barrier forming an array of holes, wherein the parallax barrier is spaced from the pixel layer by a parallax distance along an axis normal to the plane of the pixel layer; Each pixel is aligned with a hole.

2. The display device according to claim 1, wherein the parallax barrier guides light from each pixel into a common viewing window.

3. The display device according to claim 1 or 2, wherein along the direction in which the holes are closest, the holes have a width a and the pixels have a width w satisfying the requirement a≥w.

4. The display device according to any one of the preceding claims, wherein along the direction in which the holes are closest, the holes have a width a, the pixels have a pitch p and the pixels have a width w satisfying the requirement a≤(p - w / 2).

5. The display device according to any one of the preceding claims, wherein the parallax barrier has a spacing d from the pixels, and the pixels have a pitch p in the direction closest to the holes, and the material between the parallax barrier and the pixels has a refractive index n satisfying the requirements .

6. The display device according to any one of the preceding claims, wherein the parallax barrier has a spacing d from the pixels, and the holes have a width a along the direction closest to the holes, and the material between the parallax barrier and the pixels has a refractive index n that meets the requirements wherein.

7. The reflectivity control display device according to claim 6, wherein the parallax barrier has a spacing d from the pixels, and the holes have a width a along the direction closest to the holes, and the material between the parallax barrier and the pixels has a refractive index n satisfying the requirements thereof.

8. The display device according to any one of the preceding claims, wherein the pitch p' along the direction in which the holes are closest is less than the pitch p of the correspondingly aligned pixels along the direction in which the pixels are closest; and The viewing window is formed at a viewing window plane on the output side of the spatial light modulator.

9. The display device according to any one of the preceding claims, wherein the parallax barrier forms a two-dimensional array of holes, and each pixel is aligned with a corresponding hole.

10. The display device according to claim 9, wherein the pixels are arranged in columns and rows, The direction in which the holes are closest is at 45 degrees with respect to the electric vector transmission direction of the output linear polarizer; and Each pixel has a light-emitting region in the shape of a square, wherein the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer.

11. The display device according to claim 10, wherein the holes have a square shape, wherein the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer; or the holes have a circular shape.

12. The display device according to any one of the preceding claims, wherein for at least some of the pixels, the light-emitting region comprises a light-emitting sub-region and a non-light-emitting sub-region.

13. The display device according to claim 12, wherein the area ratio of the light-emitting sub-region to the non-light-emitting region is different for red, green and blue pixels.

14. The display device according to any one of claims 1 to 8, wherein the parallax barrier forms a one-dimensional array of holes, the pixels are arranged in columns, and each column of pixels is aligned with a corresponding hole.

15. The display device according to claim 14, wherein each pixel has a light-emitting region extending in the direction in which the holes extend; The widths of the red, green and blue light-emitting regions are the same for each of the pixels; and The heights of the light-emitting regions are different for red, green and blue light-emitting pixels.

16. The display device according to any one of the preceding claims, wherein the parallax barrier is arranged to absorb light incident thereon.

17. The display device according to any one of the preceding claims, wherein the absorptivity of the region of the parallax barrier between the holes is less than 100%, and Greater than 80%, preferably greater than 90%, and more preferably greater than 95%.

18. The display device according to claim 16 or 17, wherein the display device is for ambient lighting, and the parallax barrier absorbs at least some of the ambient lighting reflected from the pixel layer and transmitted through the holes.

19. The display device according to any one of the preceding claims, wherein the display device has one or more additional layers between the pixel layer and the parallax barrier, and the pixels, the one or more additional layers, and the parallax barrier are formed as a monolithic stack.

20. The display device according to claim 19, wherein the one or more additional layers include at least one light-transmissive inorganic layer arranged to provide a barrier against water and oxygen.

21. The display device according to any one of the preceding claims, wherein the parallax barrier includes at least one light-transmissive inorganic material arranged to provide a barrier against water and oxygen.

22. The display device according to any one of the preceding claims, wherein the parallax barrier is arranged between the pixel layer and at least one light-transmissive inorganic layer, and the at least one light-transmissive inorganic layer is arranged to provide a barrier against water and oxygen.

23. The display device according to any one of the preceding claims, wherein an output polarizer is arranged on the output of the spatial light modulator, and the output polarizer is a linear polarizer; and a reflection control quarter-wave retarder is arranged between the output polarizer and the spatial light modulator.

24. The display device according to claim 23, wherein the parallax barrier is arranged between the pixel layer and the reflection control quarter-wave retarder.

25. The display device according to any one of the preceding claims, further comprising an additional polarizer arranged on the output side of the output polarizer, and the additional polarizer is a linear polarizer; and at least one polarity control retarder arranged between the output polarizer and the additional polarizer.

26. The display device according to any one of claims 23 to 25, wherein when crossed with a conceptual polarizer of the same material, the transmittance of at least one of the output polarizer and the additional polarizer for wavelengths from 520 nm to 560 nm is less than the transmittance for wavelengths from 450 nm to 490 nm.

27. The display device according to claim 26, wherein the transmittance for wavelengths from 450 nm to 490 nm is greater than 1%, preferably greater than 2% and most preferably greater than 3%; and the transmittance for wavelengths from 520 nm to 560 nm is less than 3%, preferably less than 2% and most preferably less than 1%.

28. The display device according to any one of claims 25 to 27, wherein the at least one polarity control retarder further includes at least one passive retarder.

29. The display device according to claim 28, wherein the at least one polarization control retarder is capable of simultaneously performing the following operations: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the output polarizer along the axis normal to the plane of the at least one polarization control retarder, and introducing a relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer along the axis inclined to the normal of the plane of the at least one polarization control retarder.

30. The display device according to claim 28 or 29, wherein the at least one passive retarder includes a retarder having an optical axis perpendicular to the plane of the retarder, and the retardation of the at least one passive retarder for light with a wavelength of 550 nm is in the range of -150 nm to -900 nm, preferably in the range of -200 nm to -500 nm, and most preferably in the range of -250 nm to -400 nm.

31. The display device according to claim 28 or 29, wherein the at least one retarder comprises: A first quarter-wave plate and a second quarter-wave plate arranged between the additional polarizer and the output polarizer, the first quarter-wave plate being arranged on the input side of the second quarter-wave plate and being arranged to convert the polarization state of linearly polarized light transmitted by the output polarizer on its input side into a circularly polarized state, and the second quarter-wave plate on the output side being arranged to convert the polarization state of circularly polarized light incident thereon into the polarization state of linearly polarized light transmitted by the additional polarizer on its output side; and at least one retarder arranged between the pair of quarter-wave plates.

32. The display device according to claim 31, wherein the retarder arranged between the pair of quarter-wave plates includes a retarder having an optical axis perpendicular to the plane of the retarder, and the retardation of the at least one passive retarder for light with a wavelength of 550 nm is in the range of -150 nm to -500 nm, preferably in the range of -200 nm to -400 nm, and most preferably in the range of -250 nm to -350 nm.

33. The display device according to any one of claims 25 to 29, wherein the at least one polarization control retarder includes a switchable liquid crystal retarder, and the switchable liquid crystal retarder includes a liquid crystal material layer and electrodes, and the electrodes are arranged to apply a voltage to switch the liquid crystal material layer.

34. The display device according to claim 33, wherein the at least one polarization control retarder is arranged to: in a first switchable state of the switchable liquid crystal retarder, simultaneously perform the following operations: not introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer along the axis normal to the plane of the at least one polarization control retarder, and introducing a net relative phase shift to the orthogonal polarization components of the light transmitted by the reflective polarizer along the axis inclined to the normal of the plane of the at least one polarization control retarder; and In the second switchable state of the switchable liquid crystal retarder, the following operations are performed simultaneously: no net relative phase shift is introduced to the orthogonal polarization components of the light transmitted by the reflective polarizer along the axis normal to the plane of the at least one polarization control retarder, and no net relative phase shift is introduced to the orthogonal polarization components of the light transmitted by the reflective polarizer along the axis inclined to the normal of the plane of the at least one polarization control retarder.

35. The display device according to any one of the preceding claims, further comprising a reflective polarizer disposed between the output polarizer and the at least one polarization control retarder, the reflective polarizer being a linear polarizer arranged to transmit the polarization components of the same linear polarization as the output polarizer.

36. The display device according to any one of claims 23 to 35, wherein the output polarizer is a reflective polarizer.

37. The display device according to any one of the preceding claims, wherein the pixel includes a light emitting diode.

38. The display device according to claim 37, wherein the light emitting diode is an organic light emitting diode including an organic light emitting material.

39. The display device according to claim 38, wherein the thickness of the light emitting material is different for each of the red, green, and blue light emitting regions.

40. The display device according to claim 37, wherein at least some of the light emitting diodes are inorganic micro light emitting diodes.

41. The display device according to claim 40, wherein the hole has an absorption rate, and at the edge of the hole, the absorption rate has a transmittance gradient, and the transmittance gradient has a transmittance gradient width greater than 1 micron, preferably greater than 2 microns, and more preferably greater than 3 microns.

42. The display device according to any one of the preceding claims, wherein the array of holes is formed on a touch sensor electrode array.

43. The display device according to any one of the preceding claims, wherein at least one absorption region of the parallax barrier includes a touch sensor electrode array.

44. The display device according to any one of the preceding claims, wherein color filters are included at least at some of the holes of the parallax barrier.

45. The display device according to claim 44, wherein the holes of the parallax barrier include an array of red, green, and blue color filters.

46. A method of forming a display device, the method comprising: forming an array of emission pixels on a backplane by guiding an emission material through a fine metal mask; forming an encapsulation layer on the array of the emission pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on the surface of the encapsulation layer by guiding a light absorbing material through a fine metal mask.

47. A method of forming a display device, the method comprising: forming an array of emission pixels on a backplane by guiding an emission material through a fine metal mask; forming an encapsulation layer on the array of the emission pixels, the encapsulation layer including at least one transparent inorganic layer; and A parallax barrier including an array of holes is formed on the surface of the encapsulation layer by photolithographic patterning.

48. The method according to claim 46 or 47, wherein the pixels have a pitch p in the direction closest to the hole, the material between the parallax barrier and the pixels has a bulk refractive index n, and the encapsulation layer has a thickness d satisfying the requirement of.

49. The method according to any one of claims 46 to 48, wherein the hole has a width a along the direction in which the holes are closest, the material between the parallax barrier and the pixels has an overall refractive index n, and the encapsulation layer has a thickness d satisfying the requirement of.

50. A reflectivity control display device for ambient lighting, the reflectivity control display device including the display device according to claim 1, wherein the parallax barrier absorbs at least some of the ambient lighting.

51. The reflectivity control display device according to claim 50, wherein the parallax barrier guides light from each pixel into a common viewing window.

52. The reflectivity control display device according to claim 50 or 51, wherein the parallax barrier absorbs at least some of the ambient lighting reflected from the pixel layer.

53. The reflectivity control display device according to claim 51 or 52, wherein along the direction closest to the holes, the holes have a width a and the pixels have a width w satisfying the requirement a≥w.

54. The reflectivity control display device according to any one of claims 50 to 53, wherein along the direction closest to the holes, the holes have a width a, the pixels have a pitch p, and the pixels have a width w satisfying the requirement a≤(p - w / 2).

55. The reflectance control display device according to any one of claims 50 to 54, wherein the parallax barrier has a spacing d from the pixels, the pixels have a pitch p along the direction closest to the holes, and the material between the parallax barrier and the pixels has a refractive index n satisfying the requirements thereof.

56. The reflectivity control display device according to claim 55, wherein the parallax barrier has a spacing d from the pixels, the holes have a width a along the direction closest to the holes, and the material between the parallax barrier and the pixels has a refractive index n satisfying the requirements thereof.

57. The reflectivity control display device according to any one of claims 50 to 56, wherein the pitch P along the direction closest to the holes is less than the pitch p of the correspondingly aligned pixels along the direction closest to the pixels; and A viewing window is formed at a viewing window plane on the output side of the spatial light modulator.

58. The reflectivity control display device according to any one of claims 50 to 57, wherein the parallax barrier forms a two-dimensional array of holes, and each pixel is aligned with a corresponding hole.

59. The reflectivity control display device according to claim 58, wherein the pixels are arranged in columns and rows, the direction closest to the holes is at 45 degrees with respect to the electric vector transmission direction of the output linear polarizer; and each pixel has a light-emitting region in a square shape, wherein the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer.

60. The reflectivity control display device according to claim 59, wherein the holes have a square shape, wherein the edges are rotated 45 degrees with respect to the electric vector transmission direction of the output linear polarizer; or the holes have a circular shape.

61. The reflectivity control display device according to any one of claims 50 to 60, wherein the absorption rate of the region of the parallax barrier between the holes is less than 100%, and greater than 80%, preferably greater than 90%, and more preferably greater than 95%.

62. The reflectivity control display device according to any one of claims 50 to 61, wherein the display device has one or more additional layers between the pixel layer and the parallax barrier, and the pixels, the one or more additional layers, and the parallax barrier are formed as a monolithic stack.

63. The reflectivity control display device according to claim 62, wherein the one or more additional layers include at least one light-transmissive inorganic layer arranged to provide a barrier against water and oxygen.

64. The reflectance control display device according to any one of claims 50 to 63, wherein the parallax barrier includes at least one light-transmissive inorganic material arranged to provide a barrier to water and oxygen.

65. The reflectance control display device according to any one of claims 50 to 64, wherein the parallax barrier is arranged between the pixel layer and at least one light-transmissive inorganic layer, and the at least one light-transmissive inorganic layer is arranged to provide a barrier to water and oxygen.

66. The reflectance control display device according to any one of claims 50 to 65, wherein an output polarizer is arranged on the output of the spatial light modulator, and the output polarizer is a linear polarizer; and a reflection control quarter-wave retarder is arranged between the output polarizer and the spatial light modulator.

67. The reflectance control display device according to claim 66, wherein the parallax barrier is arranged between the pixel layer and the reflection control quarter-wave retarder.

68. The reflectance control display device according to claim 66 or 67, wherein when crossed with a conceptual polarizer of the same material, the transmittance of at least one of the output polarizer and the additional polarizer for wavelengths from 520 nm to 560 nm is less than the transmittance for wavelengths from 450 nm to 490 nm.

69. The reflectance control display device according to claim 68, wherein the transmittance for wavelengths from 450 nm to 490 nm is greater than 1%, preferably greater than 2% and most preferably greater than 3%; and the transmittance for wavelengths from 520 nm to 560 nm is less than 3%, preferably less than 2% and most preferably less than 1%.

70. The reflectance control display device according to any one of claims 50 to 69, wherein the pixel includes a light-emitting diode.

71. The reflectance control display device according to claim 70, wherein the light-emitting diode is an organic light-emitting diode including an organic light-emitting material.

72. The reflectance control display device according to claim 71, wherein the thickness of the light-emitting material is different for each of the red, green, and blue light-emitting regions.

73. The reflectance control display device according to claim 72, wherein for at least some of the pixels, the light-emitting region includes a light-emitting sub-region and a non-light-emitting sub-region.

74. The reflectance control display device according to claim 73, wherein the area ratio of the light-emitting sub-region to the non-light-emitting region is different for red, green, and blue pixels.

75. The reflectance control display device according to any one of claims 50 to 74, wherein at least some of the light-emitting diodes are inorganic micro light-emitting diodes.

76. The reflectance control display device according to claim 75, wherein the hole has an absorption rate, and at the edge of the hole, the absorption rate has a transmittance gradient, and the transmittance gradient has a transmittance gradient width greater than 1 micron, preferably greater than 2 microns and more preferably greater than 3 microns.

77. The reflectance control display device according to any one of claims 50 to 76, wherein the array of holes is formed on a touch sensor electrode array.

78. The reflectance control display device according to any one of claims 50 to 77, wherein at least one absorption region of the parallax barrier includes a touch sensor electrode array.

79. The display device according to any one of claims 50 to 78, wherein the display device does not have a polarizer disposed on the output side of the spatial light modulator.

80. A method of forming a reflectance control display device, the method comprising: forming an array of emissive pixels on a backplane by guiding an emissive material through a fine metal mask; forming an encapsulation layer on the array of the emissive pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on a surface of the encapsulation layer by guiding a light absorbing material through a fine metal mask.

81. A method of forming a reflectance control display device, the method comprising: forming an array of emissive pixels on a backplane by guiding an emissive material through a fine metal mask; forming an encapsulation layer on the array of the emissive pixels, the encapsulation layer including at least one transparent inorganic layer; and forming a parallax barrier including an array of holes on a surface of the encapsulation layer by photolithographic patterning.

82. The method according to claim 80 or 81, wherein the pixels have a pitch p along the direction closest to the hole, the material between the parallax barrier and the pixels has an overall refractive index n, and the encapsulation layer has a thickness d satisfying the requirement s.

83. The method according to any one of claims 80 to 82, wherein the hole has a width a along the direction closest to the hole, the material between the parallax barrier and the pixel has an overall refractive index n, and the encapsulation layer has a thickness d that satisfies the requirement of.

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