2d / multi-view switchable display and operating method therefor

Abstract

The present disclosure provides a two-dimensional (2D) / multi-view switchable display, comprising: a display panel, configured to provide pixels of a composite image, wherein the composite image comprises multi-view image content and 2D image content; a lens device, comprising a first material layer and a second material layer forming a lens element array, wherein one of the first material layer and the second material layer comprises a birefringent material having a first refractive index; and a switchable liquid crystal device, arranged between the display panel and the lens device and having electric control birefringence, wherein the switchable liquid crystal device is configured to: adjust, when the display panel displays the 2D image content, the refractive index of incident light to be matched with the first refractive index, and adjust, when the display panel displays the multi-view image content, the refractive index the incident light to be not matched with the first refractive index. The present disclosure also provides a method of operating the 2D / multi-view switchable display.

Description

2D / multi-view switchable display and method of operating the same TECHNICAL FIELD

[0001] The present disclosure relates to the field of display technology, and more particularly to a 2D / multi-view switchable display and a method of operating the 2D / multi-view switchable display. BACKGROUND

[0002] Electronic displays are almost ubiquitous media for conveying information to users of various devices and products. Known displays incorporate a lens arrangement as an imaging device, for example, the lenses can direct a two-dimensional image patch from an associated display pixel to the left and right eyes of a user in front of the lenses respectively, so that the user views a single stereoscopic image. In order to enable the display to display both two-dimensional (2D) image content (2D display mode) and three-dimensional (3D) image content (3D display mode), one way is to provide an electrically switchable lens array. In order to display 2D and 3D image content, the electrically switchable lens array is formed of an electro-optical material (e.g. liquid crystal) that can be switched at different refractive indices. In conventional applications, the switchable lens array is configured with an electrically controlled birefringence material in an adjacent layer, thereby resulting in problems such as non-uniformity of the electrically controlled birefringence layer thickness, high switching voltage, long switching time, poor product stability, etc., which can limit the use of such switchable lens array in many practical applications.

[0003] SUMMARY

[0004] In order to implement applications requiring a refractive index switching response time as short as possible, such as implementing a hybrid display mode of a display, for example, alternatingly displaying two-dimensional (2D) content and three-dimensional (3D) content at a certain frequency, the present disclosure provides a 2D / multi-view switchable display and a method of operating the 2D / multi-view switchable display.

[0005] According to a first aspect of the present disclosure, there is provided a 2D / multi-view switchable display, comprising: a display panel configured to provide pixels of a composite image, the composite image comprising multi-view image content and two-dimensional (2D) image content; a lens arrangement comprising a first material layer and a second material layer forming an array of lens elements, one of the first material layer and the second material layer comprising a birefringent material having a first refractive index; a switchable liquid crystal arrangement arranged between the display panel and the lens arrangement and having an electrically controlled birefringence, wherein the switchable liquid crystal arrangement is configured to: adjust an incident light refractive index to match the first refractive index when the display panel displays the 2D image content; and adjust the incident light refractive index to not match the first refractive index when the display panel displays the multi-view image content.

[0006] According to some embodiments of the disclosure, both the first material layer and the second material layer have the first refractive index.

[0007] According to some embodiments of the disclosure, the lens element array comprises the birefringent material, and the second material layer is formed of a non-birefringent material.

[0008] According to some embodiments of the disclosure, the lens element array comprises a non-birefringent material, and the second material layer is formed of the birefringent material.

[0009] According to some embodiments of the disclosure, each pixel of the switchable liquid crystal device is configured with a switching element for adjusting the electrically controlled birefringence of the corresponding pixel of the switchable liquid crystal device. In some embodiments, the switching element can be any one of a thin film transistor, a low temperature poly-silicon, and the like driving element.

[0010] According to some embodiments of the disclosure, the switching element is configured to:

[0011] When the display panel displays the 2D image content, the electrically controlled birefringence of the pixels of the switchable liquid crystal device corresponding to the display area of the 2D image content is adjusted to match the adjusted incident light refractive index with the first refractive index; and

[0012] When the display panel displays the multi-view image content, the electrically controlled birefringence of the pixels of the switchable liquid crystal device corresponding to the display area of the multi-view image content is adjusted to mismatch the adjusted incident light refractive index with the first refractive index.

[0013] According to some embodiments of the disclosure, the switchable liquid crystal device can use one of the following structures: a twisted nematic mode structure, a planar switching mode structure, and a vertical alignment mode structure, and other liquid crystal structures with similar functions.

[0014] According to some embodiments of the disclosure, the switchable liquid crystal device can use various known liquid crystal materials, such as nematic liquid crystal, ferroelectric liquid crystal, blue phase liquid crystal, and the like liquid crystal materials.

[0015] According to a second aspect of the disclosure, there is provided a method of operating a 2D / multi-view switchable display, the 2D / multi-view switchable display comprising a display panel configured to provide a composite image comprising multi-view image content and two-dimensional (2D) image content, a lens device comprising a birefringent material having a first refractive index, and a switchable liquid crystal device, wherein the method comprises: adjusting an incident light refractive index to match the first refractive index when the display panel displays the 2D image content; and adjusting the incident light refractive index to not match the first refractive index when the display panel displays the multi-view image content.

[0016] According to some embodiments of the disclosure, the lens device comprises a first material layer and a second material layer forming an array of lens elements, one of the first material layer and the second material layer comprising a birefringent material having a first refractive index.

[0017] According to some embodiments of the disclosure, both the first material layer and the second material layer have the first refractive index.

[0018] According to some embodiments of the disclosure, the array of lens elements comprises the birefringent material, and the second material layer is formed of a non-birefringent material.

[0019] According to some embodiments of the disclosure, the array of lens elements comprises a non-birefringent material, and the second material layer is formed of the birefringent material.

[0020] According to some embodiments of the disclosure, the method comprises adjusting a refractive index of each pixel of the switchable liquid crystal device respectively by controlling a switching element of each pixel of the switchable liquid crystal device. In some embodiments, the switching element can be any one of a thin film transistor, a low temperature poly-silicon, or the like driving element.

[0021] According to some embodiments of the disclosure, the method comprises: when the display panel displays the 2D image content, controlling each switching element to adjust an electrically controlled birefringence of a pixel of the switchable liquid crystal device corresponding to a display area of the 2D image content to match the adjusted incident light refractive index to the first refractive index; and when the display panel displays the multi-view image content, controlling each switching element to adjust an electrically controlled birefringence of a pixel of the switchable liquid crystal device corresponding to a display area of the multi-view image content to not match the adjusted incident light refractive index to the first refractive index.

[0022] According to some embodiments of the present disclosure, the switchable liquid crystal device can use one of the following structures: a twisted nematic mode structure, a planar switch mode structure, and a vertical alignment mode structure, and other liquid crystal structures with similar functions.

[0023] According to some embodiments of the present disclosure, the switchable liquid crystal device can use known various liquid crystal materials, such as nematic liquid crystal, ferroelectric liquid crystal, blue phase liquid crystal, and other liquid crystal materials.

[0024] In the above aspects of the present disclosure, by adjusting the refractive index of the individual switchable liquid crystal device, the refractive index relationship between the switchable liquid crystal device and the lens device is adjusted, the switching response time of the switchable lens array from 2D display mode to multi-view / 3D display mode and from multi-view / 3D display mode to 2D display mode is shortened, the overlap of 2D frames and multi-view frames is avoided, for example, displaying multi-view image content in 2D mode, and good display performance of the entire screen in the mixed display mode is achieved. BRIEF DESCRIPTION OF DRAWINGS

[0025] Various features and embodiments of examples and implementations in accordance with the principles described herein can be more readily understood by reference to the following detailed description, taken in conjunction with the accompanying drawings, in which like reference numerals designate like structural elements, and in which:

[0026] FIG. 1A illustrates a perspective view of a multi-view display in an example according to embodiments consistent with the principles described herein.

[0027] FIG. 1B illustrates a graphical representation of an angular component of a light beam having a particular principal angular direction in an example according to embodiments consistent with the principles described herein.

[0028] FIG. 2 illustrates a side view of a 2D / multi-view switchable display in an example according to embodiments consistent with the principles described herein.

[0029] FIG. 3 illustrates a block diagram of a 2D / multi-view switchable display in an example according to embodiments consistent with the principles described herein.

[0030] FIG. 4A illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light transmission state in an example according to embodiments consistent with the principles described herein.

[0031] FIG. 4B illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light steering state in an example according to embodiments consistent with the principles described herein.

[0032] FIG. 5A illustrates a schematic diagram of a composite image perceived by a user in an example according to embodiments consistent with the principles described herein.

[0033] FIG. 5B illustrates a schematic diagram of an example 2D / multi-view switchable display switching between 2D mode and multi-view mode, according to an embodiment consistent with the principles described herein.

[0034] FIG. 6A illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light transmissive state in an example, according to another embodiment consistent with the principles described herein.

[0035] FIG. 6B illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light directing state in an example, according to another embodiment consistent with the principles described herein.

[0036] FIG. 6C illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light transmissive state in another example, according to another embodiment consistent with the principles described herein.

[0037] FIG. 6D illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light directing state in another example, according to another embodiment consistent with the principles described herein.

[0038] FIG. 6E illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light transmissive state in an example, according to yet another embodiment consistent with the principles described herein.

[0039] FIG. 6F illustrates a cross-sectional view of a lens device and a switchable liquid crystal device in a light directing state in an example, according to yet another embodiment consistent with the principles described herein.

[0040] FIG. 7 shows a flowchart of a method of operating a 2D / multi-view switchable display in an example, according to an embodiment consistent with the principles described herein.

[0041] Certain examples and embodiments can have other features that are one of additions to, or alternatives for, the features shown in the above-described figures. These and other features are described in detail below with reference to the above-described figures. DETAILED DESCRIPTION

[0042] Examples and embodiments in accordance with the principles described herein provide 2D / multi-view switchable displays and methods of operating 2D / multi-view switchable displays that are applied to display two-dimensional (2D) images, multi-view or three-dimensional (3D) images, and 2D / multi-view hybrid images. In particular, in accordance with the principles described herein, 2D / multi-view switchable displays can employ independent switchable liquid crystal devices with switchable media in cooperation with lens devices. The switchable media (e.g., birefringent liquid crystal media) is used to effectively turn on and off the refractive effect of individual lens elements in the lens devices. By turning on and off individual lens elements, images can be provided with only 2D content, only multi-view content, or a combination of 2D / multi-view hybrid content. In accordance with various embodiments, the 2D / multi-view switchable displays include a display panel, a lens device, and a switchable liquid crystal device disposed between the display panel and the lens device. The 2D / multi-view switchable displays can be operated in a variety of modes, including a 2D mode configured to provide 2D images, a multi-view mode configured to provide multi-view images, and a 2D / multi-view hybrid mode configured to provide 2D / 3D hybrid images. Further, in accordance with various embodiments, the 2D / multi-view hybrid mode can include one or both of zoned hybrid and temporal hybrid to provide 2D / 3D hybrid images.

[0043] In accordance with various embodiments, the multi-view mode of the 2D / multi-view switchable displays can provide so-called "glasses-free" or auto-stereoscopic images, while the 2D mode can facilitate presenting 2D information or content at a relatively higher native resolution than is available in the multi-view mode, especially in the absence of a third dimension or benefitting from a third dimension. In this way, the composite images provided by time-division multiplexing and / or zoned multiplexing of 2D and multi-view modes can provide high resolution 2D and slightly lower resolution, multi-view or 3D content simultaneously in the same image or on the same display. The uses of the 2D / multi-view switchable displays described herein include, but are not limited to, mobile phones (e.g., smart phones), watches, tablets, mobile computers (e.g., laptops), personal computers and computer monitors, automobile display consoles, camera displays, and various other mobile and substantially non-mobile display applications and devices.

[0044] In this document, a 2D mode of a two-dimensional (2D) display or an equivalent multi-mode display is defined as a display or mode configured to provide an image view that is substantially the same regardless of which direction the image is viewed from (i.e., within a predetermined viewing angle or range of the 2D display or 2D mode). A conventional liquid crystal display (LCD) found in many smartphones and computer displays is an example of a 2D display. In contrast, a multi-view display or equivalently a multi-view mode of a multi-mode display is defined in this document as an electronic display, display system, or display mode of a multi-mode display configured to provide different views of a multi-view image in or from different viewing angle directions. In particular, the different views can represent different perspective views of a scene or object of the multi-view image. In some cases, a multi-view display or multi-view mode can also be referred to as a three-dimensional (3D) display or 3D mode, e.g., when two different views of a multi-view image are simultaneously viewed to provide a perception of viewing a three-dimensional image.

[0045] FIG. 1A illustrates a perspective view of a multi-view display 10 (or multi-view mode of a multi-mode display) in an example, according to an embodiment consistent with the principles described herein. As shown in FIG. 1A, the multi-view display 10 includes a screen 12 to display a multi-view image to be viewed. The multi-view display 10 provides different views 14 of the multi-view image in different view directions 16 relative to the screen 12. The view directions 16 are illustrated as arrows extending from the screen 12 in various different principal angular directions. The different views 14 are illustrated as shaded polygonal boxes at the ends of the arrows (i.e., delineating the view directions 16). Only four views 14 and four view directions 16 are illustrated, all of which are exemplary and not limiting. Note that while the different views 14 are illustrated above the screen in FIG. 1A, the views 14 actually appear on or near the screen 12 when the multi-view image is displayed on the multi-view display 10. Depicting the views 14 above the screen 12 is merely for simplicity of illustration and is intended to represent viewing the multi-view display 10 from a respective one of the view directions 16 corresponding to a particular view 14.

[0046] According to the definitions herein, a view direction or equivalently a light beam having a direction corresponding to a view direction of a multi-view display generally has a principal angular direction given by an angular component {θ, φ}. The angular component θ is referred to herein as the "elevation angle component" or "elevation angle" of the light beam. The angular component φ is referred to as the "azimuth angle component" or "azimuth angle" of the light beam. By definition, the elevation angle θ is the angle within a vertical plane (e.g., a plane normal to a multi-view display screen) and the azimuth angle φ is the angle within a horizontal plane (e.g., parallel to a multi-view display screen plane).

[0047] Figure IB illustrates a graphical representation of the angular components {0, f} of a light beam 20 having a particular principal angular direction or simply "direction" corresponding to a view direction (e.g., view direction 16 in Figure 1A) of a multiview display in an example consistent with the principles described herein. Moreover, according to the definition herein, the light beam 20 is emitted or emanates from a particular point. In other words, by definition, the light beam 20 has a central ray associated with a particular origin point within the multiview display. Figure IB also illustrates the origin point O of the light beam (or view direction).

[0048] Moreover, herein, the term "multiview" as used in the terms "multiview image," "multiview display," and "multiview mode" is defined to mean a plurality of views representing different viewing angles or including angular parallax between the views in the plurality of views. Moreover, according to the definition herein, the term "multiview" herein expressly includes more than two different views (i.e., at least three views, and typically more than three views). Thus, "multiview display" and "multiview mode" as employed herein expressly distinguish from a stereoscopic display or stereoscopic mode that includes only two different views to represent a scene or image. Note, however, that while a multiview image and multiview display can include more than two views, according to the definition herein, the multiview image can be viewed as a pair of stereoscopic images (e.g., on a multiview display) by selecting only two views of the multiview at a time (e.g., one view per eye).

[0049] A "multiview pixel" is defined herein to mean a collection of subpixels representing a "view" pixel in each of a similar plurality of different views of a multiview display or a multi-mode display in a multiview mode. In particular, a multiview pixel can have individual subpixels corresponding to or representing a view pixel in each of the different views of a multiview image. Moreover, according to the definition herein, the subpixels of a multiview pixel are so-called "directional pixels" in that each subpixel is associated with a predetermined view direction of a corresponding view in the different views. Moreover, according to various examples and embodiments, the different view pixels represented by the subpixels of a multiview pixel can have equal or at least substantially similar positions or coordinates in each of the different views. For example, a first multiview pixel can have individual subpixels corresponding to a view pixel located at {xl, yl} in each of the different views of a multiview image, while a second multiview pixel can have individual subpixels of a view pixel located at {x2, y2} in each of the different views, and so on.

[0050] In this document, a "light guide" is defined as a structure that guides light within the structure using total internal reflection or "TIR." In particular, a light guide can include a core that is substantially transparent at the operating wavelengths of the light guide. In various examples, the term "light guide" generally refers to a dielectric optical waveguide that employs total internal reflection to guide light at the interface between the dielectric material of the light guide and the material or medium that surrounds the light guide. By definition, the condition for total internal reflection is that the refractive index of the light guide is greater than the refractive index of the surrounding medium adjacent to the surface of the light guide material. In some embodiments, the light guide can include a coating in addition to or in lieu of the aforementioned difference in refractive index to further facilitate total internal reflection. For example, the coating can be a reflective coating. The light guide can be any of a number of light guides, including but not limited to one or both of a plate or slab light guide and a strip light guide.

[0051] Further, in this document, the term "plate" when applied to a light guide as in "plate light guide" is defined as a layer or sheet of segments or parallax planes, which is sometimes referred to as a "slab" light guide. In particular, a plate light guide is defined as a light guide that is configured to guide light in two substantially orthogonal directions that are bounded by a top surface and a bottom surface (i.e., opposite surfaces) of the light guide. Further, according to the definition herein, the top surface and the bottom surface are both separated from one another and can be substantially parallel to one another at least in a parallax sense. That is, within any segment of the plate light guide that is of little difference, the top surface and the bottom surface are substantially parallel or coplanar.

[0052] In this document, a "light source" is defined as a source of light (e.g., an optical emitter configured to produce and emit light). For example, a light source can include an optical emitter such as a light emitting diode (LED) that emits light when activated or turned on. In particular, a light source herein can be substantially any light source or substantially include any optical emitter, including but not limited to one or more of a light emitting diode (LED), a laser, an organic light emitting diode (OLED), a polymer light emitting diode, a plasmonic-based optical emitter, a fluorescent lamp, an incandescent lamp, and nearly any other light source. The light produced by a light source can have a color (i.e., can include light of a particular wavelength), or can be a range of wavelengths (e.g., white light). In some embodiments, a light source can include multiple optical emitters. For example, a light source can include a collection or grouping of optical emitters, where at least one optical emitter produces light having a color or wavelength that is different from the color or wavelength of light produced by at least one other optical emitter in the collection or grouping. For example, different colors can include primary colors (e.g., red, green, blue).

[0053] In this document, a "multi-view image" is defined as a plurality of images (i.e., more than three images), where each image of the plurality of images represents a different view corresponding to a different view direction of the multi-view image. Thus, a multi-view image is a collection of images (e.g., two-dimensional images) that, when displayed on a multi-view display or during a multi-view mode of a multi-mode display, can for example facilitate a perception of depth and thus appear to a viewer as images of a 3D scene. A multi-view image that provides pairs of views representing different but related perspectives of a 3D scene consistent with viewing by a viewer is defined as a 3D image.

[0054] By definition, "wide-angle" emitted light is defined as light having a cone angle that is greater than the cone angle of the views of a multi-view image or multi-view display. In particular, in some embodiments, wide-angle emitted light can have a cone angle that is greater than about twenty degrees (e.g., > ±20°). In other embodiments, the cone angle of wide-angle emitted light can be greater than about thirty degrees (e.g., > ±30°), or greater than about forty degrees (e.g., > ±40°), or greater than fifty degrees (e.g., > ±50°). For example, the cone angle of wide-angle emitted light can be about sixty degrees (e.g., > ±60°).

[0055] In some embodiments, the wide-angle emitted light cone angle can be defined to be about the same as the viewing angle of an LCD computer monitor, LCD tablet, LCD television, or similar digital display intended for wide-angle viewing (e.g., about ±40-65°). In other embodiments, wide-angle emitted light can also be characterized or described as diffuse light, substantially diffuse light, non-directional light (i.e., lacking any specific or defined directionality), or light having a single or substantially uniform direction.

[0056] Embodiments consistent with the principles described herein can be implemented using various devices and circuits, firmware, software (such as program modules or instruction sets), and combinations of two or more of the above, including but not limited to one or more of an integrated circuit (IC), a very large scale integration (VLSI) circuit, an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), a graphics processor unit (GPU), and the like. For example, an embodiment or element thereof can be implemented as a circuit element within an ASIC or VLSI circuit. An implementation with an ASIC or VLSI circuit is an example of a hardware-based circuit implementation.

[0057] In another example, an embodiment can be implemented as software using a computer programming language (e.g., C / C++) that is executed on an operating environment or software-based modeling environment (e.g., MATLAB® by The MathWorks, Inc. of Natick, Massachusetts). ) is executed, the software-based modeling environment is further executed by a computer (e.g., stored in memory and executed by a processor or a graphics processor of a general purpose computer). Note that one or more computer programs or software can constitute a computer program mechanism, and the programming language can be compiled or interpreted, e.g., configurable or configured (which can be used interchangeably in this discussion), to be executed by a processor or a graphics processor of a computer.

[0058] In yet another example, a block, module, or element of an apparatus, device, or system (e.g., an image processor, a camera, etc.) described herein can be implemented using actual or physical circuitry (e.g., as an IC or ASIC), while another block, module, or element can be implemented in software or firmware. In particular, according to the definitions herein, some embodiments can be implemented using an essentially hardware-based circuit approach or device (e.g., IC, VLSI, ASIC, FPGA, DSP, firmware, etc.), while other embodiments can also be implemented using a computer processor or graphics processor to execute software, as software or firmware, or as a combination of software or firmware and hardware-based circuitry.

[0059] Furthermore, as used herein, the term "a" is intended to have its ordinary meaning in the patent arts, i.e., "one or more." For example, "a lens" refers to one or more lenses, and thus "the lens" means "the one lens or the multiple lenses" herein. In addition, any reference herein to "top," "bottom," "upper," "lower," "up," "down," "front," "back," "first," "second," "left," or "right" is not intended to be a limitation. In this document, the term "about" when applied to a value generally means within the range of manufacturing tolerances for equipment used to produce the value, or can mean plus or minus 10%, or plus or minus 5%, or plus or minus 1%, unless otherwise expressly stated. Furthermore, the term "substantially" as used herein refers to a majority of, or nearly all of, or all of, or an amount in a range of about 51% to about 100%. In addition, examples herein are intended merely to be illustrative and presented for discussion purposes, and are not presented by way of limitation.

[0060] FIG. 2 illustrates a side view of a 2D / multiview switchable display 100 in an example, according to embodiments consistent with the principles described herein. The 2D / multiview switchable display 100 includes a display panel 102. In some embodiments, the display panel 102 can include a backlight 104 configured to emit light and an array of light valves 106 configured to modulate the light emitted by the backlight 104 to provide pixels (e.g., of a composite image), as described below. In other embodiments, other suitable configurations can also be used as the display panel 102, e.g., a direct-lit display such as, but not limited to, an organic light-emitting diode (OLED) display.

[0061] In embodiments employing a backlight, the backlight 104 can be configured to emit light, such as white light, to a range of propagation angles. In some embodiments, the range of propagation angles can include a continuous range of propagation angles that extends across a range of angles that spans a range of viewing angles of the display panel 102. According to various embodiments, the backlight 104 can include a light source, such as one or more light emitting diodes, that can produce white light or light having a specified spectral profile. In some embodiments, the backlight 104 can include a light guide that can be configured to propagate light away from the light source. The light guide can direct light out of the light guide over a specified surface area of an emission surface of the light guide.

[0062] As illustrated in FIG. 2, the 2D / multi-view switchable display 100 also includes a light valve array 106. The light valve array 106 is configured to modulate light from the backlight 104 to provide an image. In various embodiments, the light valve array 106 can include, but is not limited to, liquid crystal light valves, electrophoretic light valves, light valves based on electrical wicking, or other suitable mechanisms for modulating light. In some embodiments, the light valve array 106 can include independently controllable light valves arranged on a substrate.

[0063] According to various embodiments, the display panel 102 can be configured to provide pixels of a composite image. In various embodiments, the composite image can include both multi-view image content and two-dimensional (2D) image content. Combining multi-view image content and 2D image content onto the same display panel 102 can allow the 2D image content to be presented at a higher resolution than the multi-view image content. For example, for an embodiment of the display panel 102 that produces four views of multi-view image content, the resolution of the multi-view image content can be four times less than the resolution of the 2D image content. As one particular example, the composite image can include an image of a person and a subtitle that includes text, such that when a viewer moves in a field of view of the display panel 102, the viewer can observe various different views of the person. In this example, the 2D image content can include the subtitle with text that can include no change (e.g., have only a single view) as the observer moves in the field of view of the display panel 102. In the example presented above, the display panel 102 can present the subtitle with a higher resolution than the image of the person, which can improve readability of the text of the subtitle.

[0064] The 2D / multi-view switchable display 100 illustrated in FIG. 2 also includes a switchable liquid crystal device 108 and a lens array 110, where the switchable liquid crystal device 108 is arranged between the display panel 102 and the lens array 110. According to various embodiments, the switchable liquid crystal device 108 and the lens array 110 can be combined to form a composite image according to the pixels. As illustrated, the lens array 110 can include lens elements 112A, 112B, 112C, collectively referred to herein as lenses 112. The combination of a lens 112 and a corresponding pixel of the switchable liquid crystal device 108 can be switched between a light-transmissive state and a light-directing state. In the light-directing state, the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 is configured to provide multi-view image content according to the corresponding pixel of the composite image. In the light-transmissive state, the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 is configured to provide 2D image content according to the corresponding pixel of the composite image. For example, in the light-transmissive state, the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 can effectively become a transparent optical element that lacks or substantially lacks optical power. In other words, the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 in the light-transmissive state passes light through with no or only minimal optical effect. In one or more regions of the 2D / multi-view switchable display 100 configured to display 2D image content, the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 can be set to the light-transmissive state and thus not affect the propagation direction of light rays exiting the display panel 102. In this way, the pixels of the display panel 102 in these regions are viewable from a continuous range of view directions, i.e., viewable in or as a 2D image within the region.

[0065] Alternatively, when the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 is set to the light-directing state, the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 has optical power and is configured to affect the propagation direction of various light rays from the display panel 102 through and out of the lens 112. In particular, in one or more regions of the 2D / multi-view switchable display 100 in which the combination of the lens 112 and the corresponding pixel of the switchable liquid crystal device 108 is in the light-directing state, light rays from the display panel 102 exit the lens 112 in directions corresponding to various view directions of a multi-view image to provide multi-view image content in these regions.

[0066] According to some embodiments, the lens array 110 can include a first material layer 114 and a second material layer 115. The first material layer 114 can include the fixed lenses 112 of the lens array 110. One of the first material layer 114 and the second material layer 115 can include a birefringent liquid crystal material having a fixed refractive index. According to some embodiments, the switchable liquid crystal device 108 can include a birefringent liquid crystal layer 109. For example, the birefringent liquid crystal layer 109 of the switchable liquid crystal device 108 has a first controllable state and a second controllable state, where the first controllable state can be configured to adjust the refractive index of the incoming light to match or substantially match the fixed refractive index of the lens array 110, and the second controllable state can be configured to adjust the refractive index of the incoming light to not match the fixed refractive index of the lens array 110. In other words, the first controllable state can be configured to adjust the refractive index of the incoming light through the switchable liquid crystal device 108 to match or substantially match the fixed refractive index of the lens array 110, and the second controllable state can be configured to adjust the refractive index of the incoming light through the switchable liquid crystal device 108 to not match the fixed refractive index of the lens array 110. In some embodiments, the second material layer 115 can contact the first material layer 114, such as along a boundary shaped with a curved portion that can determine a position of the lenses 112 in the lens array 110. The second material layer 115 can fill or substantially fill the shape of the fixed lenses of the lens array 110, for example as illustrated in FIG. 2. In some embodiments, the first material layer 114 can be disposed between the second material layer 115 and the switchable liquid crystal device 108. In these embodiments, the fixed lenses of the first material layer 114 can be positive lenses. In other embodiments, the second material layer 115 can be disposed between the first material layer 114 and the switchable liquid crystal device 108. In some embodiments, the fixed lenses of the first material layer 114 can be negative lenses. As an example and not a limitation, in the example of FIG. 2, the first material layer 114 is between the switchable liquid crystal device 108 and the second material layer 115.

[0067] In other examples (not shown), the second material layer 115 can be between the switchable liquid crystal device 108 and the first material layer 114. In the example of FIG. 2, the boundary between the first material layer 114 and the second material layer 115 is shaped with a curved portion corresponding to each lens 112 in the lens array 110. In the example of FIG. 2, a center of the curved portion is a first distance from the switchable liquid crystal device 108, an edge of the curved portion is a second distance from the switchable liquid crystal device 108, and the second distance is less than the first distance. Alternatively, the second distance can be greater than the first distance. For all of these configurations, the curvature of the layer boundary and the refractive indices of the first material layer 114 and the second material layer 115 can be selected such that the lenses 112 have a positive optical power.

[0068] In some embodiments, the lens array 110 can include a one-dimensional (ID) array of cylindrical lenses arranged parallel to each other. The cylindrical lenses can be elongated in a vertical direction, such as along the X-direction in FIG. 2, and can direct light into multiple views 116 of a multi-view image. The views 116 can be horizontally adjacent to each other, such as having adjacent positions along the Y-direction in FIG. 2. In some embodiments, the cylindrical lenses in the light directing state can have a focal length selected such that the views 116 have a center-to-center spacing 120 at a designated viewing plane 118 corresponding to an average interpupillary distance of a human. In some embodiments, the lenses in the lens array 110 can be half-cylindrical lenses. In some embodiments, the lenses in the lens array 110 can be convex cylindrical lenses, concave cylindrical lenses, or any other suitable shape of lenses.

[0069] In other embodiments, the lens array 110 can include a two-dimensional array of lenses. In some embodiments, the lenses 112 in the lens array 110 can be rotationally symmetric lenses, such as lenses that are symmetric about a longitudinal axis of the lenses. In some embodiments, the lenses 112 of the lens array 110 can be rotationally asymmetric lenses, such as anamorphic lenses. An anamorphic lens can have a first focal length along a first direction, such as along the X-direction in FIG. 2, and a second focal length along a second direction, such as along the Y-direction in FIG. 2, the second direction being orthogonal to the first direction. In some embodiments, the lenses of the lens array 110 can be spherical lens elements or aspherical lens elements.

[0070] In some configurations, the switchable liquid crystal device 108 can include electrodes 122 configured to deliver at least one of a voltage or a current to independently switch the birefringent liquid crystal layer 109 of each pixel in the switchable liquid crystal device 108 between a first controllable state and a second controllable state to thereby direct light according to a refractive index difference with a corresponding lens 112 in the lens array 110. For example, the electrodes 122 can be configured to switch the pixels in the switchable liquid crystal device 108 corresponding to each lens 112 independently of the pixels in the switchable liquid crystal device 108 corresponding to each other lens. The electrodes 122 can include an upper electrode and a lower electrode configured to apply a voltage or deliver a current across a region of the birefringent liquid crystal layer 109. The region can correspond to a single lens 112 or a grouping of lenses 112. In some embodiments, the upper electrode or the lower electrode can extend across some or all of the birefringent liquid crystal layer 109, while the lower electrode or the upper electrode can extend across a region corresponding to a single lens. According to various embodiments, the electrodes 122 can be transparent or substantially transparent, for example, the electrodes 122 can include indium tin oxide (ITO) or similar optically transparent electrode material.

[0071] In some embodiments, switchable liquid crystal device 108 can include electrodes 122 configured to switch pixels of switchable liquid crystal device 108 corresponding to one zone of the composite image independently of pixels of switchable liquid crystal device 108 corresponding to other zones of the composite image. For some embodiments, electrodes 122 can be configured to switch pixels of switchable liquid crystal device 108 corresponding to a set of lenses 112 together independently of other pixels in switchable liquid crystal device 108. Electrodes 122 can include upper and lower electrodes configured to apply a voltage or deliver a current across a region of birefringent liquid crystal layer 109. The region can correspond to a set of lenses 112. In some embodiments, one of electrodes 122 can extend across some or all of birefringent liquid crystal layer 109, while an opposing electrode 122 can extend over a region corresponding to birefringent liquid crystal layer 109, such as in a designated zone of the composite image.

[0072] In some embodiments (e.g., embodiments as exemplified in FIG. 2), 2D / multi-view switchable display 100 further includes a switching controller 124. Switching controller 124 can be configured to control birefringent liquid crystal layer 109 to be in a first controllable state that adjusts the refractive index of incident light to be different from a fixed refractive index to provide a light directing state. Switching controller 124 can also control birefringent liquid crystal layer 109 to be in a second controllable state that adjusts the refractive index of incident light to match the fixed refractive index to provide a light transmitting state. For example, switching controller 124 can selectively provide at least one of a voltage or a current to a particular pair of electrodes 122 that in turn are configured to distribute the at least one of a voltage or a current over a suitable region of switchable liquid crystal device 108. For zone switching, switching controller 124 can switch pixels of switchable liquid crystal device 108 corresponding to one zone of the composite image together between the light directing state to provide a multi-view image and the light transmitting state to provide a 2D image. In the example of FIG. 2, switching controller 124 is not part of display panel 102. In other embodiments, switching controller 124 can be part of display panel 102.

[0073] In some embodiments, the 2D / multi-view switchable lens display 100 can also include a controller 130. In various embodiments, the controller 130 can be configured to provide video image signals or static image signals to the light valve array 106. The video image signals or static image signals can include data corresponding to video images or static images that can be displayed on the 2D / multi-view switchable display 100. The controller 130 can be connected by a wireless or wired connection to receive the video image signals or static image signals from a server or network. In some embodiments, the controller 130 can be configured to provide a separate video image signal or a separate static image signal for each view direction of the 2D / multi-view switchable display 100. In some embodiments, the controller 130 can also control the switching controller 124 or the light sources in the backlight 104. An optional eye tracker can determine the position of the user's eyes 128 and can provide data representing the eye position to the controller 130. In the example of FIG. 2, the controller 130 is not part of the display panel 102; in other configurations, the controller 130 can be part of the display panel 102.

[0074] According to various embodiments, the display panel 102 of the 2D / multi-view switchable display 100 can be configured to provide pixels of a composite image by temporal mixing or zonal mixing of pixels representing multi-view image content and 2D image content within the composite image.

[0075] Temporal mixing can include time division multiplexing of light directing states and light transmitting states of the lens array 110 and switchable liquid crystal device 108 to time division multiplex multi-view image content and 2D image content within a composite image. For example, for a particular region of the composite image, the display panel 102 can time alternate between displaying multi-view image content (and setting the combination of the lens array 110 and switchable liquid crystal device 108 to a light directing state) and displaying 2D image content (and setting the combination of the lens array 110 and switchable liquid crystal device 108 to a light transmitting state). The time alternation can occur at every video frame, or at another suitable time division multiplexing rate. For a time division multiplexing rate that is higher than the response rate of the human eye, the temporal mixing can be perceived as a 2D image superimposed on the multi-view image. As the observer moves in the field of view of the display panel 102, the multi-view image can change with different views while the 2D image remains constant. As an example, the light valve array 106 can be an LCD panel operating at 120 Hz, and the switch controller 124 can be configured to cause the combination of the lens array 110 and switchable liquid crystal device 108 to switch between the light directing state and the light transmitting state at 60 Hz to provide time division multiplexing. In another example, the LCD panel or light valve array can operate at 240 Hz, and the switch controller 124 can be configured to cause the combination of the lens array 110 and switchable liquid crystal device 108 to switch between the light directing state and the light transmitting state at 120 Hz.

[0076] Zonal mixing can include switching different subsets of pixels in different regions of the combination of the switchable liquid crystal device 108 and lens array 110 corresponding to different zones of the composite image to the light directing state to provide multi-view image content and to the light transmitting state to provide 2D image content. For example, a first region of the display panel 102 can be configured to provide multi-view image content, and a second region of the display panel 102 can be configured to provide 2D image content. In some embodiments, the multi-view image content and the 2D image content can be provided simultaneously. As the observer moves in the field of view of the display panel 102, the multi-view image can change with different views in the first region while the 2D image remains constant in the second region.

[0077] In an example of zonal mixing, the pixels of the composite image can be grouped into mutually exclusive subsets of pixels. Each subset of pixels can correspond to a corresponding subset of pixels of the switchable liquid crystal device 108 and a respective lens 112 of the lens array 110. The combination of the switchable liquid crystal device 108 and lens array 110 is configured to direct light from the corresponding subset of pixels to a respective view direction of the multi-view image as a view pixel of a different view of the multi-view image when the lens 112 of the lens array 110 and the corresponding subset of pixels of the switchable liquid crystal device 108 are in the light directing state.

[0078] In the example of FIG. 2, the lens array 110 includes three lenses 112A, 112B, 112C. Each lens 112A, 112B, 112C is associated with a group of six light valves 106 of the light valve array 106. The leftmost lens 112A is associated with the leftmost group 132 of light valves. The rightmost lens 112C is associated with the rightmost group 134 of light valves. The center lens 112B is associated with the center group 136 of light valves. Each of the three groups of light valves corresponds to a respective zone of the composite image. FIG. 2 shows the leftmost lens and the corresponding pixel of the switchable liquid crystal device 108 in a light-transmissive state (as indicated by the dashed line), and the center and rightmost lenses and the corresponding pixels of the switchable liquid crystal device 108 in a light-directing state. Thus, the leftmost zone of the composite image is presented in 2D, while the center and rightmost zones of the composite image are presented in multi-view.

[0079] FIG. 3 illustrates a block diagram of a 2D / multi-view switchable display 300 in an example, in accordance with an embodiment consistent with the principles described herein. As illustrated, the 2D / multi-view switchable display 300 includes a display panel 302 configured to provide a composite image including both multi-view image content and two-dimensional (2D) image content. The 2D / multi-view switchable display 300 can include a lens array 310 and a switchable liquid crystal device 308, the combination of which is switchable between a light-directing state and a light-transmissive state. In some embodiments, the lens array 310 and the switchable liquid crystal device 308 can be substantially similar to the lens array 110 and the switchable liquid crystal device 108 described above.

[0080] The 2D / multiview switchable display 300 illustrated in FIG. 3 also includes a display controller 306. The display controller 306 is configured to provide a composite image using temporal mixing or zoned mixing of multiview image content and 2D image content. Temporal mixing can include time-multiplexing light directing states and light transmitting states of the combination of the lens array 310 and the switchable liquid crystal device 308 to superimpose multiview image content and 2D image content within the composite image. Time-multiplexing can include a duty cycle that can be optionally controlled or varied to control or vary the relative intensities of the multiview image content and the 2D image content within the composite image. Zoned mixing can include selectively switching the combination of the lens array 310 and the switchable liquid crystal device 308 in a first zone 320 of the composite image to a light directing state to provide multiview image content in the first zone 320 and selectively switching the combination of the lens array 310 and the switchable liquid crystal device 308 in a second zone 322 of the composite image to a light transmitting state to provide 2D image content in the second zone 322. In some embodiments, the display controller 306 can be substantially similar to the switching controller 124 or the controller 130 as described above.

[0081] In some embodiments, the lens array 310 can include a first material layer that forms the lens elements. In some embodiments, the first material layer of the lens array 310 can be substantially similar to the first material layer 114 as described above. In some embodiments, the lens array 310 can include a second material layer that is in contact with the first material layer and fills or substantially fills the shape of the fixed lenses of the lens array 310. In some embodiments, the second material layer of the lens array 310 can be substantially similar to the second material layer 115 as described above. One of the first material layer and the second material layer can include a birefringent liquid crystal material having a fixed refractive index.

[0082] The electrically controlled birefringence can have a first controllable state that adjusts the refractive index of the incident light to match the fixed refractive index of the first material layer and a second controllable state that adjusts the refractive index of the incident light to be different from the fixed refractive index.

[0083] In some embodiments, the switchable liquid crystal device 308 can include electrodes configured to selectively deliver current or voltage to independently switch individual pixels in the switchable liquid crystal device 308 between different refractive indices. In some embodiments, the electrodes can be substantially similar to the electrodes 122 as described above.

[0084] In some embodiments, switchable liquid crystal device 308 can include electrodes configured to selectively deliver current or voltage to switch pixels of switchable liquid crystal device 308 corresponding to one zone of a composite image independently from regions of switchable liquid crystal device 308 corresponding to other zones of the composite image. In some embodiments, electrodes of switchable liquid crystal device 308 can be substantially similar to electrodes 122 as described above.

[0085] In some embodiments, lenses in lens array 310 can be lenticular lenses. Lenticular lenses can be elongated in a vertical direction and configured to direct light in directions corresponding to multiple views of a multi-view image. The views can be horizontally adjacent to each other. In some embodiments, lenticular lenses in a light-directing state can have a focal length selected such that at a designated viewing plane, the views can have a center-to-center spacing corresponding to an average inter-pupillary distance of a human.

[0086] FIGS. 4A and 4B illustrate cross-sectional views of a lens device 410 and a switchable liquid crystal device 420 in a light-transmitting state and in a light-directing state, respectively, in an example according to an embodiment consistent with the principles described herein. As illustrated, lens device 410 includes a combination of a lens 412 switchable between a light-directing state and a light-transmitting state and switchable liquid crystal device 420. In some embodiments, lens device 410 can be substantially similar to lens array 110 described above, and switchable liquid crystal device 420 can be substantially similar to switchable liquid crystal device 108 described above.

[0087] Lens device 410 illustrated in FIGS. 4A and 4B includes a first material layer 414 forming lens elements. In some embodiments, first material layer 414 of lens device 410 can be substantially similar to first material layer 114 as described above. Lens device 410 can include a second material layer 415, which can be in contact with first material layer 414 and fill or substantially fill the shape of lens elements of lens device 410. In some embodiments, second material layer 414 of switchable lens array 400 can be substantially similar to second material layer 115 as described above. In some embodiments, such as the embodiment of FIGS. 4A and 4B, second material layer 115 includes a birefringent liquid crystal material having a fixed refractive index.

[0088] Switchable liquid crystal device 420 illustrated in FIGS. 4A and 4B employs a twisted nematic (TN) mode structure, which includes electrodes 422 configured to selectively deliver current or voltage to switch the orientation of liquid crystals in switchable liquid crystal device 420 to adjust the refractive index of incident light after passing through switchable liquid crystal device 420. In some embodiments, electrodes 422 can be substantially similar to electrodes 122 as described above.

[0089] In the embodiment illustrated in FIGS. 4A and 4B, the switchable liquid crystal device 420 further includes a switch 432 and a power supply 430. In other embodiments, the switch 432 and the power supply 430 can not be included in the switchable liquid crystal device 420. In some embodiments, as shown in FIG. 4A, when the switch 432 is open, the current and voltage of the power supply 430 are not provided to the electrodes 422, no electric field acts on the switchable liquid crystal device 420, and the liquid crystal molecules in the switchable liquid crystal device 420 are arranged in a helical shape, gradually twisting the vibration direction of the input linear light (shown as ordinary light, O light, in FIG. 4A) by 90°, so that the extraordinary light (E light) is output to be input into the lens device 410. Since the vibration direction of the E light is consistent with the direction (the long axis direction in the case of positive liquid crystal) of the liquid crystal of the second material layer 415 having the refractive index n e . In other words, the long axis of the material crystal of the second material layer 415 extends in a direction perpendicular to the cross section of FIG. 4A or a direction substantially perpendicular to the cross section, and the vibration direction of the E light is perpendicular to the cross section, so the E light passes through the lens device 410 without refraction, thereby achieving normal 2D display.

[0090] In the embodiment of FIG. 4A, the light input into the switchable liquid crystal device 420 is converted by the switchable liquid crystal device 420 into light having a vibration direction consistent with the refractive direction of the liquid crystal of the lens device 410, so that the lens device 410 is in a light transmission state. In the light transmission state, the refractive index (equivalent to the refractive index n e ) after the incident light passes through the switchable liquid crystal device 420 matches the fixed refractive index of the second material layer 415, and thus the lens 412 allows the light to pass through without or with minimal optical effect.

[0091] In some embodiments, as shown in FIG. 4B, when the switch 432 is closed, the current or voltage of the power supply 430 is provided to the electrodes 422, generating an electric field parallel to the normal direction of the cross section acting on the switchable liquid crystal device 420, so that the liquid crystal molecules in the switchable liquid crystal device 420 are arranged along the normal direction of the light output surface of the switchable liquid crystal device 420. Therefore, the input O light does not change the vibration direction, i.e., twisted by 0°, after passing through the switchable liquid crystal device 420, so that the O light is output to be input into the lens device 410. Since the vibration direction of the O light is parallel to the cross section, i.e., perpendicular to the refractive direction of the liquid crystal of the second material layer 415 of the lens device 410, the O light is refracted by the lens device 410, thereby achieving multi-view display.

[0092] In the embodiment of FIG. 4B, the incident light input into the switchable liquid crystal device 420 is controlled by the switchable liquid crystal device 420 to have a vibration direction that is not aligned with the refractive direction of the liquid crystal of the lens device 410, such that the lens device 410 is in a light-directing state. In the light-directing state, the refractive index (equivalent to the refractive index n o ) of the light after passing through the switchable liquid crystal device 420 is not matched with the fixed refractive index of the second material layer 415, and thus the lens 412 affects the propagation direction of various light rays from the switchable liquid crystal device 420 passing through and exiting the lens 412. By way of example only and without limitation, the long axis of the material crystal of the switchable liquid crystal device 420 in FIG. 4B all extend in a direction parallel to the vertical direction of the cross section and the long axis of the liquid crystal of the lens device 410 all extend in a direction perpendicular to the cross section, to indicate that the refractive index of the two crystals are different. Those skilled in the art should understand that the twisted arrangement of the material crystal of the switchable liquid crystal device 420 such that the vibration direction of the light output therefrom is different from the direction perpendicular to the cross section can represent that the refractive index of the light after passing through the switchable liquid crystal device 420 is different from the fixed refractive index of the lens device 410, and the long axis direction of the crystal of the switchable liquid crystal device 420 at each sub-zone can be adjusted to different directions according to various viewing directions, such that the switchable liquid crystal device 420 is in different controllable states at each sub-zone.

[0093] FIGS. 4A and 4B describe the combination of the lens device 410 and the switchable liquid crystal device 420 switching between the light-transmitting state and the light-directing state using the structure of the TN mode as an example, and those skilled in the art should understand that the switchable liquid crystal device 420 can adopt the structure of the planar conversion mode, the structure of the vertical alignment mode, or other liquid crystal structures with similar functions. In some embodiments, the switchable liquid crystal device 420 can use various known liquid crystal materials, such as nematic liquid crystals, ferroelectric liquid crystals, blue phase liquid crystal materials, etc. Those skilled in the art should understand that the angle at which the switchable liquid crystal device adjusts the deflection direction of the light can be designed to be between 0 degrees and 90 degrees according to design requirements.

[0094] In some embodiments, each pixel of the switchable liquid crystal device 420 in FIGS. 4A and 4B is provided with a switching element that independently controls the refractive index of each pixel. In some embodiments, the switching element that independently controls the refractive index of each pixel of the switchable liquid crystal device 420 can include a thin-film transistor (TFT) cell. In some embodiments, by selectively controlling the on-off of each TFT cell, it can be made that: when the display panel displays 2D image content, the electrically controlled birefringence of the pixels of the switchable liquid crystal device 420 corresponding to the display area of the 2D image content is adjusted to make the adjusted incident light refractive index match the fixed refractive index of the second material layer 415; and when the display panel displays multi-view image content, the electrically controlled birefringence of the pixels of the switchable liquid crystal device 420 corresponding to the display area of the multi-view image content is adjusted to make the adjusted incident light refractive index not match the fixed refractive index of the second material layer 415.

[0095] According to other embodiments of the principles described herein, a method of operating a 2D / multi-view switchable display is provided. In particular, the method of operating a 2D / multi-view switchable display can have at least two modes, i.e., a 2D mode and a multi-view mode, which are time-division multiplexed or time-interleaved. According to various embodiments, two-dimensional (2D) image content can be displayed in the 2D mode, while three-dimensional (3D) or multi-view image content can be displayed in the multi-view mode. Time-division multiplexing combines the 2D image content with the 3D or multi-view image content into a composite image having both the 2D image and the multi-view image content or information. Since switching between the light transmission state and the light directing state can be achieved by simply switching the state of the switchable liquid crystal device 420, the switching time between the light transmission state and the light directing state can be made to be about 1 ms.

[0096] FIG. 5A illustrates a composite image perceived by a user in an example according to embodiments consistent with the principles described herein. According to some embodiments, as illustrated in FIG. 5A, the time-division multiplexed display displays a 2D image 510 (represented by diagonal hatching) during the 2D mode and a 3D or multi-view image 520 (represented by horizontal hatching) during the multi-view mode, which, as described above, superimposes the 2D image 510 and the 3D or multi-view image 520 on the time-division multiplexed display by time-division multiplexing the 2D mode and the multi-view mode to provide a composite image 530.

[0097] FIG. 5B illustrates a schematic diagram of an example 2D / multi-view switchable display switching between 2D mode and multi-view mode, according to embodiments consistent with the principles described herein. In the example of FIG. 5B, the light valve array is an LCD panel running at 120Hz, and the lenses of the lens array (e.g., lens units) are switched between light transmission state and light steering state at 60Hz by adjusting the refractive index of the switchable liquid crystal device to provide time-division multiplexing. As illustrated in the top row of FIG. 5B, the first and third frames are intended to display 2D content and the second and fourth frames are intended to display 3D or multi-view content, and so on. During image update, the light valve (e.g., liquid crystal light valve) array is line-by-line gate scanned according to the content to be displayed to refresh the corresponding light valve array across the full screen. Upon receiving the gate scan signal, the liquid crystal in the light valve needs a response time to complete the corresponding transition, i.e., the liquid crystal pixel will be delayed to show the correct content. In some cases, the total time for all rows (i.e., full screen) of the light valve array to complete the gate scan and liquid crystal response far exceeds the frame period of one frame. In each frame period, the backlight is turned on to display the correct 2D image content or multi-view image content only after the liquid crystal in the light valve completes the transition and the lens array completes the state switching. The holding time of the backlight turning on needs to meet the minimum brightness requirement of the display. Therefore, within the limited frame period, if the total time for all rows of the light valve array to complete the gate scan and liquid crystal response is too long, it can result in only a portion of the area of the entire display being updated such that the partial content of the previous frame and the partial content updated by the current frame overlap, thereby affecting the mixing performance.

[0098] As shown in FIG. 5B, in order to display the correct image content, the gate scan time T LCD_SCAN of the light valve array, the liquid crystal response time T LCD_RESP of the light valve array, the turning-on time T BLU of the backlight, and the frame period T of one frame satisfy the following equation (1): T LCD_SCAN + T LCD_RESP + T BLU (1).

[0099] As shown in FIG. 5B, equation (1) applies to both 2D frames and 3D frames. As illustrated by way of example and not limitation in FIG. 5B, the refresh frequency of the light valve array (and thus the LCD panel) can be kept at 120 Hz, and the lens unit switches between the light transmitting state and the light directing state at 60 Hz. Those skilled in the art will appreciate that while FIG. 5B illustrates by way of example and not limitation an embodiment in which the light valve array is refreshed at 120 Hz and the lens unit switches between the light transmitting state and the light directing state at half the refresh frequency, in other embodiments the light valve array can have other refresh frequencies and the lens unit can switch between the light transmitting state and the light directing state at half the refresh frequency. In some examples, the light valve array can operate at 180 Hz and the lens unit can switch between the light transmitting state and the light directing state at 90 Hz.

[0100] In some embodiments, the driving rate of the light valve array can be kept constant (i.e., the gate scan time T LCD_SCAN is unchanged), while the refresh frequency of the light valve array is reduced so that the frame period T is extended in order to satisfy equation (1). It should be noted that, as described above, the refresh frequency of the light valve array needs to exceed at least the visual persistence of a viewer using the display so that each of the 2D image content and the multi-view image content appears constant to the user and there is no perceptible flicker in the composite image. A switching rate of at least about 60 Hz (i.e., a refresh frequency of about 120 Hz) will provide this visual persistence goal (i.e., about or less than 1 millisecond in each mode) for each of the 2D mode and the multi-view mode.

[0101] In the embodiment illustrated in FIG. 5B, the gate scan time T LCD_SCAN , the liquid crystal response time T LCD_RESP , and the minimum illumination time required by the backlight are adjusted so that their sum is less than or equal to one frame period T so that the corresponding content is displayed correctly on the full screen in each frame (i.e., the backlight is activated when the 2D image content is fully refreshed on the light valve array and the backlight is activated when the multi-view image content is fully refreshed on the light valve array), and the illumination time T BLU of the backlight is greater than its minimum required illumination time.

[0102] On the other hand, in order to correctly display the 2D image content and the multi-view image content, the switchable liquid crystal device also requires a certain response time to change the arrangement of the liquid crystals therein so that the lenses of the lens array switch from the light directing state to the light transmitting state or vice versa. If the switching response time of the switchable liquid crystal device is too long so that the state of the lens array has not completed switching when the backlight is illuminated, then the switchable liquid crystal device and the lens array cannot correctly direct the light from the light valve array so that the correct image content cannot be displayed on the switchable display.

[0103] As shown in FIG. 5B, to display correct image content, the maximum switching response time T SLC_MAX of the switchable liquid crystal device, the lighting time T BLU of the backlight, and the frame period T of a frame satisfy the following equation (2): T > T SLC_MAX + T BLU (2).

[0104] As shown in FIG. 5B, equation (2) is applicable to both 2D frames and 3D frames, i.e., the maximum switching response time T SLC_MAX represents the maximum of the response time of the lens from the light guiding state to the light transmitting state and the response time of the lens from the light transmitting state to the light guiding state.

[0105] In some embodiments, to display correct image content, the backlight is activated or lit when the light valve array finishes refreshing and the switchable liquid crystal device finishes state switching, i.e., equation (1) and (2) are satisfied simultaneously.

[0106] In some embodiments, as shown in FIG. 5B, the backlight is a strobed backlight or a scanning backlight working in a strobed mode, in other words, the backlight is turned on and off as a whole, and the entire area of the backlight is lit simultaneously during the lighting of the backlight to emit light to the entire light valve array. In the embodiment of FIG. 5B, by applying power or removing power to all pixels of the switchable liquid crystal device, all rows of the lens unit or lens array can be switched from the light guiding state to the light transmitting state or from the light transmitting state to the light guiding state simultaneously after the end of a frame, and the entire backlight can be activated or lit when all rows of the light valve array finish refreshing and all rows of the lens unit or lens array finish state switching.

[0107] In some embodiments, all pixels of the switchable liquid crystal device finish refractive index switching, i.e., all rows of the lens array finish state switching, can be earlier than all rows of the light valve array finish refreshing, and the entire backlight can be lit when all rows of the light valve array finish refreshing. In other words, the maximum switching response time T SLC_MAX of the switchable liquid crystal device is less than or equal to the sum of the gate scan time T LCD_SCAN of the light valve array and the liquid crystal response time T LCD_RESP . In other embodiments, all rows of the light valve array finish refreshing can be earlier than all pixels of the switchable liquid crystal device finish refractive index switching, and the entire backlight can be lit when all pixels of the switchable liquid crystal device finish refractive index switching.

[0108] In some embodiments, the time for all rows of the lens array to switch from the light directing state to the light transmitting state can be different from the time for all rows of the lens array to switch from the light transmitting state to the light directing state. Thus, in some embodiments, the backlight can be illuminated for the entire backlight to complete the state switching of all rows of the lens array in a case where the formulas (1) and (2) are satisfied, so that the backlight illumination time for displaying 2D image content is different from the backlight illumination time for displaying multi-view image content. In other embodiments, although the time for all rows of the lens array to switch from the light directing state to the light transmitting state is different from the time for all rows of the lens array to switch from the light transmitting state to the light directing state, the backlight illumination can still be selected so that the backlight illumination time for displaying 2D image content is the same as the backlight illumination time for displaying multi-view image content. In the embodiment illustrated in FIG. 5B, the term "lens array" can be used interchangeably with "lens unit". Although the above explains the requirement of the switching response time of the refractive index switching of the switchable liquid crystal device, i.e., the switching of the lens array between the light directing state and the light transmitting state, with the embodiment of FIG. 5B, such requirement is also applicable to other related embodiments.

[0109] FIGS. 6A and 6B respectively illustrate cross-sectional views of a lens device 610 and a switchable liquid crystal device 620 in a light transmitting state and in a light directing state in an example according to another embodiment consistent with the principles described herein. Similar to the lens device 410 and the switchable liquid crystal device 420 illustrated in FIGS. 4A and 4B, the combination of the lens array 610 and the switchable liquid crystal device 620 illustrated in FIGS. 6A and 6B can switch between the light directing state and the light transmitting state. Unlike the lens device 410 illustrated in FIGS. 4A and 4B, the first material layer 614 of the lens device 610 illustrated in FIGS. 6A and 6B includes a birefringent liquid crystal material having a fixed refractive index, and the second material layer 615 of the lens device 610 has non-birefringent properties.

[0110] FIGS. 6C and 6D respectively illustrate cross-sectional views of a lens device 610 and a switchable liquid crystal device 620 in a light transmitting state and in a light directing state in another example according to other embodiments consistent with the principles described herein. The lens device 610 and the switchable liquid crystal device 620 illustrated in FIGS. 6C and 6D are substantially similar to the lens device 610 and the switchable liquid crystal device 620 illustrated in FIGS. 6A and 6B, except that the first material layer 614 of the lens device 610 illustrated in FIGS. 6C and 6D forming the lens elements is disposed closer to the switchable liquid crystal device 620, while the first material layer 614 of the lens device 610 illustrated in FIGS. 6A and 6B forming the lens elements is disposed farther away from the switchable liquid crystal device 620.

[0111] FIGS. 6E and 6F respectively illustrate cross-sectional views of the lens device 610 and the switchable liquid crystal device 620 in the light transmission state and in the light steering state in another example, according to some other embodiments consistent with the principles described herein. Similar to the lens device 410 and the switchable liquid crystal device 420 illustrated in FIGS. 4A and 4B, the combination of the lens array 610 and the switchable liquid crystal device 620 illustrated in FIGS. 6E and 6F can be switched between the light steering state and the light transmission state. Unlike the lens device 410 illustrated in FIGS. 4A and 4B, the refractive direction of the liquid crystal of the second material layer 615 of the lens device 610 is parallel to the horizontal direction of the cross-section. As shown in FIG. 6E, when the switch 632 is closed, the current or voltage of the power source 630 is provided to the electrode 622, generating an electric field parallel to the vertical direction of the cross-section acting on the switchable liquid crystal device 620, so that the liquid crystal molecules in the switchable liquid crystal device 620 align along the normal direction of the light exit surface of the switchable liquid crystal device 620. Therefore, the input O light does not change the vibration direction after passing through the switchable liquid crystal device 620, i.e., twisted by 0°, and thus the output O light is input into the lens device 610. Since the vibration direction of the O light is parallel to the cross-section, i.e., consistent with the refractive direction of the liquid crystal of the second material layer 615 of the lens device 610, the O light does not refract when passing through the lens device 610, thus achieving normal 2D display.

[0112] In the embodiment of FIG. 6E, the light input into the switchable liquid crystal device 620 is controlled by the switchable liquid crystal device 620 to have a vibration direction consistent with the refractive direction of the liquid crystal of the lens device 610, so that the lens device 610 is in the light transmission state. In the light transmission state, the refractive index of the incident light after passing through the switchable liquid crystal device 620 matches the fixed refractive index of the second material layer 615, and thus the lens 612 passes the light without or with minimal optical effect.

[0113] Further, as shown in FIG. 6F, when the switch 632 is turned off, the current and voltage of the power supply 630 are not provided to the electrode 622, no electric field acts on the switchable liquid crystal device 620, so that the liquid crystal molecules in the switchable liquid crystal device 620 are arranged in a helical shape, and thus the vibration direction of the input O light is gradually twisted by 90°, thereby outputting E light to be input into the lens device 610. Since the vibration direction of the E light is inconsistent with the refractive direction of the liquid crystal of the second material layer 615, in other words, the long axis of the material crystal of the second material layer 615 extends in a direction parallel to the cross section of FIG. 6F or substantially parallel to the cross section and the vibration direction of the E light is perpendicular to the cross section, the E light is refracted by the lens device 610, thereby achieving multi-view display. In the embodiment of FIG. 6F, the light input into the switchable liquid crystal device 620 is switched by the switchable liquid crystal device 620 to have a vibration direction inconsistent with the refractive direction of the liquid crystal of the lens device 610, so that the lens device 610 is in the light guiding state. In the light guiding state, the refractive index of the incident light after passing through the switchable liquid crystal device 620 does not match the fixed refractive index of the second material layer 615, and thus the lens 612 affects the propagation direction of various light rays from the switchable liquid crystal device 620 passing through and exiting the lens 612.

[0114] Those skilled in the art should understand that, in addition to the cooperation of the arrangement direction of the liquid crystal in the lens device 610 and the refractive state of the switchable liquid crystal device 620 varying according to the energized state, the positive crystal type and the negative crystal type of the respective crystals in the lens device 610 and the switchable liquid crystal device 620 can also be selected to cooperate with the arrangement direction of the liquid crystal in the lens device 610 and the energized state of the switchable liquid crystal device 620 to achieve switching between the light transmitting state and the light guiding state.

[0115] FIG. 7 illustrates a flowchart of a method 700 of operating a 2D / multi-view switchable display in an example consistent with the principles described herein. As illustrated in FIG. 7, the method 700 of operating a 2D / multi-view switchable display includes adjusting, by a switchable liquid crystal device, a refractive index of incident light to match a first refractive index of a lens device when a display panel displays two-dimensional (2D) image content 710. In some embodiments, the display panel can be substantially similar to the display panel 102 described above with reference to FIG. 2. In some embodiments, the switchable liquid crystal device can be substantially similar to the switchable liquid crystal device 108 described above with reference to FIG. 2, the switchable liquid crystal device 308 described with reference to FIG. 3, the switchable liquid crystal device 420 described with reference to FIGS. 4A-4B, and the switchable liquid crystal device 620 described with reference to FIGS. 6A-6F. In some embodiments, the lens device can be substantially similar to the lens array 110 described above with reference to FIG. 2, the lens array 310 described with reference to FIG. 3, the lens device 410 described with reference to FIGS. 4A-4B, and the lens device 610 described with reference to FIGS. 6A-6F.

[0116] The method 700 of operating a 2D / multi-view switchable display illustrated in FIG. 7 also includes adjusting, by the switchable liquid crystal device, the refractive index of the incident light to not match the first refractive index when the display panel displays multi-view image content 720. In some embodiments, the display panel can be substantially similar to the display panel 102 described above with reference to FIG. 2. In some embodiments, the switchable liquid crystal device can be substantially similar to the switchable liquid crystal device 108 described above with reference to FIG. 2, the switchable liquid crystal device 308 described with reference to FIG. 3, the switchable liquid crystal device 420 described with reference to FIGS. 4A-4B, and the switchable liquid crystal device 620 described with reference to FIGS. 6A-6F.

[0117] In some embodiments, the lens device includes a first material layer and a second material layer forming an array of lens elements, one of the first material layer and the second material layer including a birefringent material having a first refractive index. In some embodiments, both the first material layer and the second material layer have the first refractive index.

[0118] In some embodiments, the array of lens elements includes a birefringent material, and the second material layer is formed of a non-birefringent material.

[0119] In some embodiments, the array of lens elements includes a non-birefringent material, and the second material layer is formed of a birefringent material.

[0120] In some embodiments, a monolithic approach can be used to switch the refractive index of individual pixels of the switchable liquid crystal device. In other embodiments, a pixelated approach can be used to switch the refractive index of individual pixels of the switchable liquid crystal device.

[0121] In some embodiments, the method 700 of operating a 2D / multiview switchable display further includes adjusting a refractive index of each pixel of the switchable liquid crystal device individually by controlling a switching element of the each pixel of the switchable liquid crystal device. In some embodiments, the switchable liquid crystal device can be substantially similar to the switchable liquid crystal device 108 described above with reference to FIG. 2, the switchable liquid crystal device 308 described with reference to FIG. 3, the switchable liquid crystal device 420 described with reference to FIGS. 4A-4B, and the switchable liquid crystal device 620 described with reference to FIGS. 6A-6F. In some embodiments, the switching element can be any one of a thin film transistor, low temperature poly-silicon, etc. driving element.

[0122] In some embodiments, the method 700 of operating a 2D / multiview switchable display includes, while the display panel displays 2D image content, controlling the each switching element to adjust an electrically controllable birefringence of a pixel of the switchable liquid crystal device corresponding to a display area of the 2D image content to match the adjusted incident light refractive index with the first refractive index. In some embodiments, the display panel can be substantially similar to the display panel 102 described above with reference to FIG. 2. In some embodiments, the switchable liquid crystal device can be substantially similar to the switchable liquid crystal device 108 described above with reference to FIG. 2, the switchable liquid crystal device 308 described with reference to FIG. 3, the switchable liquid crystal device 420 described with reference to FIGS. 4A-4B, and the switchable liquid crystal device 620 described with reference to FIGS. 6A-6F. In some embodiments, the lens device can be substantially similar to the lens array 110 described above with reference to FIG. 2, the lens array 310 described with reference to FIG. 3, the lens device 410 described with reference to FIGS. 4A-4B, and the lens device 610 described with reference to FIGS. 6A-6F.

[0123] In some embodiments, the method 700 of operating a 2D / multi-view switchable display further includes, while the display panel displays the multi-view image content, controlling the individual switching elements to adjust the electrically controllable birefringence of the pixels of the switchable liquid crystal device corresponding to the display area of the multi-view image content to a value that causes the adjusted refractive index of the incident light to mismatch the first refractive index. In some embodiments, the display panel can be substantially similar to the display panel 102 described above with reference to FIG. 2. In some embodiments, the switchable liquid crystal device can be substantially similar to the switchable liquid crystal device 108 described above with reference to FIG. 2, the switchable liquid crystal device 308 described with reference to FIG. 3, the switchable liquid crystal device 420 described with reference to FIGS. 4A-4B, and the switchable liquid crystal device 620 described with reference to FIGS. 6A-6F. In some embodiments, the lens device can be substantially similar to the lens array 110 described above with reference to FIG. 2, the lens array 310 described with reference to FIG. 3, the lens device 410 described with reference to FIGS. 4A-4B, and the lens device 610 described with reference to FIGS. 6A-6F.

[0124] In some embodiments, the switchable liquid crystal device uses one of the following structures: a twisted nematic mode structure, a planar switch mode structure, a vertical alignment mode structure, and other liquid crystal structures with similar functionality. In some embodiments, the switchable liquid crystal device can use a variety of known liquid crystal materials, such as nematic liquid crystals, ferroelectric liquid crystals, blue phase liquid crystal materials, and the like.

[0125] Thus, examples and embodiments of 2D / multi-view switchable displays and methods of operating 2D / multi-view switchable displays have been described. For example, embodiments relate to processing multi-view images for display in two modes (e.g., 2D mode and multi-view mode) of a 2D / multi-view switchable display, resulting in a composite multi-view image. It should be understood that the foregoing description is only illustrative of the principles of the application. Numerous and various embodiments of the present application can be made and used in accordance with the broadest scope of the claims that follow. Any and all modifications, variations or equivalent arrangements that fall within the scope of the claims should also be considered.

Claims

1. A 2D / multiview switchable display, comprising: a display panel configured to provide pixels of a composite image, the composite image comprising multiview image content and two-dimensional (2D) image content; a lens device comprising first and second material layers forming an array of lens elements, one of the first and second material layers comprising a birefringent material having a first refractive index; a switchable liquid crystal device arranged between the display panel and the lens device and having an electrically controllable birefringence, wherein the switchable liquid crystal device is configured to: adjust an incident light refractive index to match the first refractive index when the display panel displays the 2D image content; and adjust the incident light refractive index to not match the first refractive index when the display panel displays the multiview image content.

2. The 2D / multiview switchable display of claim 1, wherein, both the first and second material layers have the first refractive index.

3. The 2D / multiview switchable display of claim 1, wherein, the array of lens elements comprises the birefringent material and the second material layer is formed of a non-birefringent material.

4. The 2D / multiview switchable display of claim 1, wherein, the array of lens elements comprises a non-birefringent material and the second material layer is formed of the birefringent material.

5. The 2D / multiview switchable display according to any of claims 1 to 4, wherein, each pixel of the switchable liquid crystal device is configured with a switching element for adjusting the electrically controllable birefringence of the respective pixel of the switchable liquid crystal device.

6. The 2D / multiview switchable display of claim 5, wherein, the switching element is configured to: adjust the electrically controllable birefringence of the pixels of the switchable liquid crystal device corresponding to a display area of the 2D image content to cause an adjusted incident light refractive index to match the first refractive index when the display panel displays the 2D image content; and adjust the electrically controllable birefringence of the pixels of the switchable liquid crystal device corresponding to a display area of the multiview image content to cause the adjusted incident light refractive index to not match the first refractive index when the display panel displays the multiview image content. the switchable liquid crystal device uses one of the following structures: a twisted nematic mode structure, a plane switch mode structure, or a vertical alignment mode structure.

7. The 2D / multiview switchable display of any of claims 1-4, wherein, the switchable liquid crystal device uses one of the following liquid crystal materials: a nematic phase liquid crystal, a ferroelectric liquid crystal, or a blue phase liquid crystal.

8. The 2D / multiview switchable display of any one of claims 1-4, wherein, 9. A method of operating a 2D / multiview switchable display, the 2D / multiview switchable display comprising a display panel configured to provide a composite image comprising multiview image content and two-dimensional (2D) image content, a lens device comprising a birefringent material having a first refractive index, and a switchable liquid crystal device, wherein the method comprises: adjusting an incident light refractive index incident on the switchable liquid crystal device to match the first refractive index when the display panel displays the 2D image content; and adjusting the incident light refractive index to not match the first refractive index when the display panel displays the multiview image content. the lens device comprises first and second material layers forming an array of lens elements, one of the first and second material layers comprising a birefringent material having a first refractive index. ​ 10. The method of claim 9, wherein, ​ 11. The method of claim 10, wherein, The first material layer and the second material layer both have the first refractive index.

12. The method of claim 10, wherein, The lens element array comprises the birefringent material, and the second material layer is formed of a non-birefringent material.

13. The method of claim 10, wherein, The lens element array comprises a non-birefringent material, and the second material layer is formed of the birefringent material.

14. The method of any one of claims 9 to 13, wherein, The method comprises adjusting the refractive index of respective pixels of the switchable liquid crystal device by controlling the switching elements of the pixels.

15. The method of claim 14, wherein, The method comprises: controlling the respective switching elements to adjust the electrically controlled birefringence of the pixels of the switchable liquid crystal device corresponding to the display area of the 2D image content to match the adjusted incident light refractive index to the first refractive index; and controlling the respective switching elements to adjust the electrically controlled birefringence of the pixels of the switchable liquid crystal device corresponding to the display area of the multi-view image content to not match the adjusted incident light refractive index to the first refractive index.

16. The method of any one of claims 9 to 13, wherein, The switchable liquid crystal device uses one of the following structures: a twisted nematic mode structure, a planar switch mode structure, a vertical alignment mode structure.

17. The method of any one of claims 9 to 13, wherein, The switchable liquid crystal device uses one of the following liquid crystal materials: a nematic phase liquid crystal, a ferroelectric liquid crystal, a blue phase liquid crystal.

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