Display backlight with optical expander structure

Abstract

The present invention relates generally to information displays, and more particularly to a system and method for a backlight assembly for an information display that includes a light expander structure. The backlight assembly can include a light expander structure having a plurality of layer sets, where each layer set includes a reflective polarizing layer and a wave retarder layer. Together, the layer sets can be operable to convert a point source of light, such as a laser light beam, into an area source of light for use as a backlight for various types of information displays.

Description

Technical Field

[0001] The present disclosure generally relates to a backlight for a display, and in at least some implementations, to a backlight used in a cross-eye display or a head-mounted display.

Background Art

[0002] An information display with a backlight, such as a liquid crystal display (“LCD”), includes several components. Two of those components are a display matrix that creates a display image by blocking light on a high-granularity sub-pixel basis, and a light source or backlight. The light source is generally positioned behind the display matrix and illuminates the display image. For a color display, the backlight generally emits broad-spectrum light, i.e., white light.

[0003] Conventionally, the light sources used in backlit displays have often been one or more cold cathode fluorescent lamps (“CCFLs”). Physically, CCFLs somewhat resemble a smaller version of the fluorescent tubes used in commercial office buildings. However, CCFLs create light in a different way than those commercial fluorescent lights. More recently, the use of CCFLs has shifted to the use of one or more light-emitting diodes (“LEDs”) as the light source within an information display. Currently, LED technology is the most common backlight type for LCD displays.

[0004] Backlights can generally be classified into two types: edge-type backlights, which provide light to the display panel through its sides, and direct-type backlights, which provide light to the display panel through its bottom. Edge-type backlights have a light source for generating light and an optical guide panel or panel for controlling the direction of light propagation. The light source is placed on one side of the optical guide panel, which guides the light transmitted from the light source to the display panel. Depending on the shape of the light beam generated by the light source, the light source can be classified, for example, as a point source, a linear source, or a surface source.

[0005] Close-eye display technology can be used to present information and images to a user as part of a virtual reality ("VR") or augmented reality ("AR") system. Such close-eye displays can be integrated into a head-mounted display ("HMD") device or headset. HMDs can take many forms, including helmets, visors, goggles, masks, glasses, and other head or eyewear. In some embodiments, virtual and augmented reality systems have additional components, including a controller or computer that generates image information to operate the virtual or augmented reality environment. Such environments may be for a single user or for multiple users. HMDs in virtual and augmented reality systems can use a single information display or multiple information displays to present images to the user. While these close-eye information displays can be adapted for direct viewing, they are often coupled to one or more lenses within the HMD. These lenses can enhance the virtual or augmented reality experience. [Brief explanation of the drawing]

[0006] In drawings, the same reference numerals identify similar elements or actions. The size and relative position of elements in a drawing are not necessarily drawn to scale. For example, the shapes and angles of various elements are not necessarily drawn to scale, and some of these elements may be arbitrarily enlarged and positioned to improve the readability of the drawing. Furthermore, the specific shapes of these elements that are depicted may not necessarily be intended to convey any information about the actual shape of those particular elements, but may have been chosen simply to facilitate recognition in the drawing.

[0007] [Figure 1] This is a diagram illustrating an example of a head-mounted display device with dual display panels, based on one exemplary implementation.

[0008] [Figure 2] This is a diagram illustrating an example of a laptop computer with a display panel, representing one exemplary implementation.

[0009] [Figure 3] This is a diagram illustrating an example of a smartphone with a display panel, representing one non-restrictive illustrative implementation.

[0010] [Figure 4] This describes an exemplary backlight assembly in one non-restrictive illustrative implementation.

[0011] [Figure 5] This shows a front view of an exemplary backlight assembly in one non-restrictive illustrative implementation.

[0012] [Figure 6] This is a perspective view of a backlight assembly in one non-restrictive illustrative implementation.

[0013] [Figure 7]Top view of the backlight assembly of FIG. 6 according to one non-limiting illustrative implementation.

[0014] [Figure 8] Elevation view of the backlight assembly of FIG. 6 according to one non-limiting illustrative implementation.

[0015] [Figure 9] Enlarged view of a portion of the second light expander structure of the backlight assembly of FIG. 6 according to one non-limiting illustrative implementation.

[0016] [Figure 10] Enlarged view of a portion of the first light expander structure of the backlight assembly of FIG. 6 according to one non-limiting illustrative implementation.

[0017] [Figure 11] Elevation view of a stack comprising a plurality of layer sets used to form a backlight assembly according to one non-limiting illustrative implementation.

[0018] [Figure 12] Perspective view of a stack comprising a plurality of layer sets of FIG. 11 according to one non-limiting illustrative implementation.

[0019] [Figure 13A] Illustrative steps for manufacturing a backlight assembly comprising a first light expander structure and a second light expander structure formed from a stack having a plurality of layer sets according to one non-limiting illustrative implementation are shown. [Figure 13B] Illustrative steps for manufacturing a backlight assembly comprising a first light expander structure and a second light expander structure formed from a stack having a plurality of layer sets according to one non-limiting illustrative implementation are shown. [Figure 13C]An exemplary step for manufacturing a backlight assembly comprising a first light expander structure and a second light expander structure formed from a stack having a plurality of layer sets according to one non-limiting illustrative implementation is shown.

[0020] [Figure 14] A perspective view of a backlight assembly according to one non-limiting illustrative implementation, the backlight assembly including an optical component for homogenizing light from a light source before the light enters the light expander of the backlight assembly.

DETAILED DESCRIPTION OF THE INVENTION

[0021] In the following description, specific specific details are set forth in order to provide a thorough understanding of the various disclosed implementations. However, one of ordinary skill in the art will recognize that the implementations may be practiced without one or more of these specific details, or with other methods, components, materials, etc. In other instances, well-known structures associated with computer systems, server computers, and / or communication networks have not been shown or described in detail in order to avoid unnecessarily obscuring the description of the implementations.

[0022] Throughout this specification and the following claims, unless the context requires otherwise, the word "comprise" and variations thereof such as "comprises" and "comprising" are to be interpreted in an inclusive sense, i.e., in the sense of "including, but not limited to".

[0023] Throughout this specification, any reference to “one implementation” or “one implementation” means that the specific features, structures, or characteristics described in relation to that implementation are included in at least one implementation. Therefore, where the phrases “in one implementation” or “in an implementation” appear in various places throughout this specification, they do not necessarily all refer to the same implementation. Furthermore, specific features, structures, or characteristics may be combined in any suitable manner in one or more implementations.

[0024] Where used herein and in the appended claims, the singular forms "a," "an," and "the" refer to multiple subjects unless the context clearly indicates otherwise. It should also be noted that, unless the context clearly indicates otherwise, the term "or" is generally used to mean "and / or."

[0025] The headings and abstracts of this disclosure provided herein are for convenience only and do not constitute an interpretation of the scope or meaning of the implementations.

[0026] One or more implementations of this disclosure are intended for displays for electronic devices such as head-mounted display devices, laptop computers, tablet computers, televisions, smartphones, wearable computers, and computer monitors. Non-limiting examples of electronic devices that may include such displays are shown in Figures 1 to 3.

[0027] Liquid crystal displays (LCDs) are a common example of non-emissive displays that require a separate light source, referred to as a backlight unit or assembly. The backlight assembly provides such displays with homogeneous and bright light having appropriate color characteristics. Backlight technology has become more important in recent years, with the advent of edge-illuminated light-emitting diode (LED) backlights, which enable displays to be much thinner than conventional displays while simultaneously reducing power consumption. It is crucial to make backlight assemblies as efficient as possible to meet energy regulations or other requirements. As will be further discussed below, this disclosure improves the performance of backlight assemblies by providing a backlight assembly that includes a beam expander structure that expands a collimated beam of light in multiple dimensions to create a highly efficient expanded surface light source compared to existing technologies.

[0028] Figure 1 shows a non-limiting example of an electronic device in the form of a head-mounted display device 100, which can optionally be coupled to a video rendering computing system via a wired or wireless connection to provide a virtual reality display to a human user. During operation, the user wears the HMD device 100 on their head, secured via one or more straps 101, and receives displayed information of a simulated environment different from the actual physical environment from the computing system to each eye via displays 102a and 102b supported by the support structure 116 of the HMD device, the computing system acting as an image rendering system that supplies images of the simulated environment to the HMD device for display to the user, such as images generated by a game program (not shown) and / or other software program (not shown) running on the computing system. The user may further have one or more I / O ("input / output") devices that allow the user to further interact with the simulated environment, such as a handheld controller which is communicably coupled to the computing system via a wired or wireless connection, and the user may further be able to move around in the actual physical environment. The HMD device may include one or more user interfaces 104 and 106 that enable the user to provide input to the HMD device 100 or to a computing system coupled to the HMD device. As the user moves to a different location and / or changes the orientation of the HMD device 100, the position of the HMD device may be tracked, for example, to enable the user to see a corresponding portion of a simulated environment on the HMD device, and the controller may further utilize similar techniques for use in tracking the controller's position (and optionally for use in assisting in determining and / or verifying the position of the HMD device).After the tracking location of the HMD device 100 is known, the corresponding information is transmitted to a computing system, which uses this tracking location information to generate one or more images of a simulated environment for display to the user via displays 102a and 102b.

[0029] Figure 2 shows an exemplary electronic device in the form of a laptop computer 200 having an upper housing 202 and a lower housing 204, the upper housing 202 and the lower housing 204 being joined together via a hinge 206 that allows these housings to rotate relative to each other. The lower housing 204 includes a keyboard 208 and may include other structures (e.g., a touchpad, various ports). The upper housing 202 includes a display panel 210 that may be used to display content to the user.

[0030] Figure 3 shows an exemplary electronic device in the form of a smartphone 300. The smartphone 300 includes a housing 302 which contains a display panel 304 and a number of input components 306 (e.g., buttons). In at least some implementations, the display panel 304 may be, for example, a touchscreen display.

[0031] More generally, the displays of this disclosure may be implemented in the devices shown in Figures 1 to 3, or in any other type of electronic device, including music players, gaming devices, navigation units, vehicle displays, wearable devices, kiosks, or other types of devices having one or more displays.

[0032] Figure 4 shows an exemplary backlit LCD display 400 having a backlight assembly in a head-mounted display configuration, such as within a virtual reality or augmented reality headset. Figure 4 shows how the backlight assembly 402 emits light 430 that displays a visible image, passing through the LCD 410. The LCD display may optionally include a diffusion layer 404 to make the light more uniform, and in at least some implementations, it may optionally include a reflective polarizing layer 406 to recycle the light and improve efficiency. The light 440 that leaves the LCD 410 then passes through a lens assembly 420 having one or more lenses. In certain embodiments, the lenses in the lens assembly 420 may be conventional spherical, aspherical, Fresnel, or any other type of imaging lens. The lens assembly 420 may have a single type of lens surface or a combination of multiple lens types. In some implementations, the lens assembly 420 may have a pancake configuration, which may have a polarization-based reflective or refractive optical system. In this case, the lens assembly 420 may comprise an assembly of optical elements configured to direct light from the LCD 410 toward the user's eye 460 using an on-axial optical bend that is at least partially based on the polarization of the light. The lens assembly 420 may also include various optical elements other than lenses. For example, the lens assembly 420 may comprise at least one polarizing beam splitter and a substrate having a twisted liquid crystal element. The twisted liquid crystal element may be configured to correct the phase of light within the lens assembly 420. Light 450 exits the lens assembly 420, directed toward the user's eye 460. In some embodiments, the light 450 creates an eyebox of about 10 millimeters (e.g., 5 to 25 mm). Those skilled in the art will understand that Figure 4 is not intended to show a physical design or layout of the HMD system, but rather to show the general flow of light between the illustrated components in some embodiments.

[0033] In certain embodiments, a head-mounted display is designed to be viewed by both the left and right eyes of the user. This can be achieved using separate LCD displays for the left and right eyes, or it can be achieved using a single LCD display. Similarly, a virtual reality or augmented reality headset may have a single lens assembly, or it may use separate lens assemblies for the left and right eyes.

[0034] Figure 5 shows a front view of an exemplary backlight assembly 500 according to a particular embodiment of the present disclosure. The backlight assembly 500 may include an elongated first optical expander structure 502 and a rectangular (e.g., square) second optical expander structure 504. The second optical expander structure may have a length and width substantially the same as the length and width of the display that has the backlight assembly as a part of itself. The first optical expander structure 502 can receive incoming light 508 from a light source 506 (e.g., one or more laser light sources) and can redirect the incoming light 508 toward the second optical expander structure 504. In this configuration, the incoming light 508 is received at the end of the first optical expander structure 502 and output as redirected light 510 from the plane of the first optical expander structure. Next, the redirected light 510 can be received at the end of the second optical expander structure 504, which can redirect the light 510 upward (outside the page in the figure) as light 512 toward the pixelated display panel (for example, toward the LCD 410 in Figure 4). Thus, the emitted light 512 is output from the plane of the second optical expander structure 504. This causes the light 512 to be emitted from the backlight assembly 500. In some embodiments, the light 512 may pass through additional components before its light is received by the pixelated display panel.

[0035] Figure 6 shows a perspective view of an exemplary optical guide panel assembly 600 for a backlight assembly in one or more implementations of the present disclosure. Various other figures of the optical guide panel assembly 600 are shown in Figures 7 to 10. The optical guide panel assembly 600 may be a component in any of the various types of displays, such as the displays discussed herein.

[0036] The optical guide panel assembly 600 includes a first optical expander structure 602 and a second optical expander structure 604. The first and second optical expander structures 602 and 604 may be similar to or identical to the first and second optical expander structures 502 and 504, respectively. The first and second optical expander structures 602 and 604 can be bonded to each other by a suitable optically transparent adhesive (OCA). The first optical expander structure 602 may include a strip-shaped elongated waveguide adjacent to and parallel to the end of the second optical expander structure 604. The first optical expander structure 602 is operable to receive light 616 emitted from the light source 614 and redirect it in the longitudinal ("x") direction of the first optical expander structure 602. The light source 614 may be one or more laser light sources (e.g., red, green, and blue semiconductor lasers) that emit a polarized beam 616 of light having specific dimensions (e.g., a square of 1 to 5 mm × 1 to 5 mm, Gaussian, etc.). The light source 614 may also comprise multiple laser sources, each emitting light of a different color (e.g., red, green, and blue). The light source 614 may emit coherent light having linear polarization in a first polarization state (e.g., horizontal polarization). The light source 614 may also comprise one or more other light sources and an optional lens that provide collimated light to the optical expander structure 602.

[0037] As shown in Figures 7 and 10, the first optical expander structure 602 may comprise a first set of layers (e.g., 3 to 50 layers), where each layer set has a substrate 608 (e.g., plastic) and a layer 606 including a reflective polarizing layer 611 and a wave retarder layer 613. The reflective polarizing layer 611 and the wave retarder layer 613 are oriented at a 45-degree angle to the light 616 received from the light source 614, and this light passes through the first optical expander structure (shown as light 618 within structure 602).

[0038] Each of the reflective polarizing layers 611 may be configured to reflect linearly polarized light having a second polarization state (e.g., perpendicular polarization) orthogonal to the polarization emitted by the light source 614. The reflective polarizing layers 611 may comprise a polarizing film (e.g., DBEF), a wire grid polarizer (WGP), or any other suitable reflective polarizer capable of acting to achieve the functionality discussed herein.

[0039] Since the reflective polarizing layers 611 are not ideal reflective polarizers, they do not simply reflect 100% of vertically polarized light and transmit 100% of non-vertically polarized light. Rather, even for purely horizontally polarized light, the reflective polarizing layers 611 reflect a small percentage of the light (e.g., 5 to 15 percent) and transmit the rest (e.g., 85 to 95 percent).

[0040] The wave retarder layers 613 are configured to shift the direction of polarization of light by a predetermined amount of rotation (e.g., 5 to 20 degrees). Each of the wave retarder layers 613 may be a half-wave plate, a quarter-wave plate, or any other suitable wave retarder capable of shifting or rotating the direction of polarization of light by a predetermined amount. Each wave retarder layer 613 may shift the direction of polarization by the same amount, or different wave retarder layers may shift the direction of polarization by different amounts. As a non-limiting example, a first set of wave retarder layers 613 may result in a 10-degree rotation shift, a second set of wave retarder layers may result in a 15-degree shift, and a third set of wave retarder layers may result in a 20-degree shift. The number of retarder layers in each set may be the same or different.

[0041] As shown in Figures 7, 8, and 9, the second optical expander structure 604 may comprise a second set of layers (e.g., 3 to 50, or more), where each layer set comprises a substrate 612 (e.g., acrylic plastic or other plastic) and a layer 610 including a reflective polarizing layer 611 and a wave retarder layer 613. The reflective polarizing layer 611 and the wave retarder layer 613 are oriented at a 45-degree angle to the light 620 received from the first optical expander structure 602, as will be discussed further below.

[0042] In operation, according to one non-limiting example, a collimated beam of horizontally polarized light 616 from the light source 614 enters the edge of the first optical expander structure 602. When the light 618 reaches each reflecting polarizer 611 and the subsequent wave retarder layer 613, a small portion of the light (e.g., 5 to 15 percent) (indicated by arrow 620) is reflected toward the second optical expander structure 604 in the "y" direction, and the remaining portion (e.g., 85 to 95 percent) is rotated by the subsequent wave retarder layer 613 to create light 618a (Figure 10) rotated by a predetermined amount (e.g., 10 degrees, 15 degrees, 20 degrees). Therefore, when light 618 travels along the first optical expander structure 602 in the "x" direction, a portion of the light is directed toward the second optical expander structure 604 by each reflecting polarizer 611 of the first optical expander structure 602, so as to travel along the "y" direction of the second optical expander structure.

[0043] The operation of the second optical expander structure 604 is similar. Light 620 traveling in the "y" direction from the first optical expander structure 602 is received by the second optical expander structure 604 at intervals determined by the position of the reflective polarizing layer 611 of the first optical expander structure 602. When the light 620 reaches each reflective polarizer 611 of the second optical expander structure 604 and the subsequent wave retarder layer 613, a small portion of the light (e.g., 5 to 15 percent) (indicated by arrow 622) is reflected in the "z" direction toward the display module (not shown in Figure 6), and the remaining portion (e.g., 85 to 95 percent) is rotated by the subsequent wave retarder layer 613 to create light 620a (Figure 9) rotated by a predetermined amount (e.g., 10 degrees, 15 degrees, 20 degrees). Therefore, as light 620 travels along the second optical expander structure 602 in the "y" direction, a portion of the light is directed upward (as shown in the figure) toward the display module, along the "z" direction of the second optical expander structure 604. Since the light 620 from the first optical expander structure 602 is dispersed along the "x" dimension of the second optical expander structure 604, the light 622 emitted by the second optical expander structure 604 provides substantially uniform surface illumination in the "z" direction to the display module.

[0044] The number of reflective polarizing layers, the number of wave retarder layers, and the amount of rotation provided by each wave retarder layer can be designed to provide uniform light across the entire region of the second optical expander structure 604. Furthermore, although not shown, various components may have one or more additional reflective layers positioned adjacent to one or more ends to recycle light, thereby improving efficiency.

[0045] Figures 11 to 13C show non-limiting examples of how to manufacture optical guide panel assemblies, such as the optical guide panel assembly 600 shown in Figures 6 to 10.

[0046] First, a set 1100 can be formed consisting of multiple stacked layer sets 1102. Each of the multiple stacked layer sets may include a substrate layer 1108 (e.g., acrylic plastic or other plastic), a wave retarder layer 1104, and a reflective polarizing layer 1106. In this exemplary embodiment, 10 layer sets 1102 are shown, but it should be understood that the number of stacked layer sets can be selected based on the individual application. For example, there may be 3 layer sets, 5 layer sets, 10 layer sets, 20 layer sets, 25 layer sets, 50 layer sets, 100 layer sets, and so on.

[0047] Next, as shown in Figures 11 and 12, the intermediate light guide panel assembly 1110 can be formed by cutting multiple stacked layer sets at a 45-degree angle. Note that in Figure 12, for clarity, only one end of the stack 1100 shows the layer set 1102.

[0048] Figures 13A to 13C illustrate various steps in a method for fabricating the first optical expander structure 602 and the second optical expander structure 604 from the intermediate optical guide panel assembly 1110 shown in Figures 11 and 12.

[0049] As shown in Figure 13A, a portion of the intermediate optical guide panel assembly 1110 can be cut to form the first optical expander structure 602 and the second optical expander structure 604. As shown in Figure 13B, the first optical expander structure 602 can be rotated around the "z" axis and moved relative to the second optical expander structure 604 to bring it closer to the bottom right end (shown) of the second optical expander structure. As shown in Figure 13C, the first optical expander structure 602 can also be rotated clockwise around the "x" axis (as shown) and coupled to the second optical expander structure 604 (e.g., by OCA) to form the optical guide panel assembly 600 discussed herein.

[0050] Figure 14 is a perspective view of a backlight assembly 600, also shown in Figure 6, which includes an optical component 1400 that homogenizes light from a light source 614 before it enters the first optical expander structure 602 of the backlight assembly. The optical component 1400 may comprise a microlens array (as shown) having multiple microlenses 1402 (e.g., a 5x5 array, a 10x10 array, etc.). In at least some implementations, or in addition to the above, the optical component 1400 may further include a diffuser, other types of optical components, or a combination of two or more components that can operate to homogenize the light 616 emitted by the light source 614 to provide homogenized light 1404 to the first optical expander structure 602 of the backlight assembly 600.

[0051] The microlens array 1400 may be useful for homogenizing various modern light sources 614, including laser diodes and high-power LEDs. Advantageously, the microlens array 1400 can bring highly efficient, non-Gaussian uniformity to the light.

[0052] The microlens array 1400 can be used for beam homogenization and shaping to change the light from the light source 614 from a Gaussian pattern to a spot pattern or a square "flat-top" pattern. Thus, expanding the light as discussed herein results in substantially more uniform light than in the case where the light remains in a Gaussian pattern. In non-limiting examples, the microlens array 1400 may include multiple square microlens arrays. Furthermore, as described above, the optical component 1400 may include one or more optical components (e.g., a microlens array and a second lens, a microlens array and a diffuser) for providing homogenized light to the optical expander structures 602 and 604 of the backlight assembly 600.

[0053] Those skilled in the art will recognize that many of the methods or algorithms described herein may utilize additional operations, omit some operations, and / or perform operations in an order different from that specified. Further implementations can also be provided by combining the various implementations described herein. These and other modifications may be made to implementations in consideration of the detailed descriptions above. In general, the terms used in the following claims should not be construed to limit the claims to any specific implementation disclosed herein and in the claims, but rather to include all possible implementations along with the entire scope of equivalents covered by such claims. Therefore, the claims are not limited by this disclosure.

Claims

1. Display module; and Backlight assembly that provides light to the aforementioned display module A display device equipped with, The aforementioned backlight assembly Light source; and Optical guide panel assembly It has, The optical guide panel assembly, A first optical expander structure positioned to receive light from the light source, the first optical expander structure comprising a first set of layers, each of which comprises a reflective polarizing layer and a wave retarder layer; and A second optical expander structure is positioned adjacent to the first optical expander structure to receive light from it and emit light toward the display module, the second optical expander structure comprising a second set of layers, each of which comprises a reflective polarizing layer and a wave retarder layer. including, Display device.

2. At least one of the wave retarder layers of the first set of layers and the second set of layers is configured to shift the polarization direction of the light by a first amount, At least one of the wave retarder layers is configured to shift the polarization direction of the light by a second amount different from the first amount, The first and second amounts are each between 5 and 20 degrees. The display device according to claim 1.

3. The first amount and the second amount are selected, respectively, to control the partial light extraction by the reflective polarizing layer. The display device according to claim 2.

4. The display device according to any one of claims 1 to 3, wherein the light source emits a coherent beam of light linearly polarized in a first polarization state, and the reflective polarization layer in the first set of layers is configured to reflect light linearly polarized in a second polarization state, and the second polarization state is orthogonal to the first polarization state.

5. The display device according to any one of claims 1 to 4, wherein each of the wave retarder layers of the first set of layers and the second set of layers includes a half-wave plate.

6. The display device according to any one of claims 1 to 5, wherein each of the wave retarder layers of the first set of layers and the second set of layers includes a half-wave plate that shifts the polarization direction of light by 5 to 20 degrees.

7. The display device according to any one of claims 1 to 6, wherein each of the reflective polarizing layers and each of the wave retarder layers are oriented at an angle of 45 degrees with respect to light incident on the reflective polarizing layer and the wave retarder layer.

8. The display device according to any one of claims 1 to 7, wherein each layer set among the first set of layers and the second set of layers includes a layer of transparent plastic.

9. The display device according to any one of claims 1 to 8, wherein each of the first set of layers and the second set of layers comprises 3 to 50 sets of layers.

10. The display device according to any one of claims 1 to 9, wherein each of the reflective polarizing layers includes at least one of a reflective polarizing film or a wire grid polarizer.

11. The display device according to any one of claims 1 to 10, wherein each of the wave retarder layers of the first set of layers and the second set of layers includes a quarter-wave plate.

12. The display device according to any one of claims 1 to 11, wherein the light source emits light in a first direction, the first optical expander structure is operable to direct the light received from the light source in a second direction perpendicular to the first direction, and the second optical expander structure is operable to direct the light received from the first optical expander structure in a third direction perpendicular to the first and second directions.

13. The display device according to any one of claims 1 to 12, wherein the first optical expander structure is bonded to the second optical expander structure by an optically transparent adhesive.

14. The display device according to any one of claims 1 to 13, further comprising a diffusion layer positioned between the backlight assembly and the display module.

15. The display device according to any one of claims 1 to 14, wherein the light source includes a plurality of lasers, each emitting light of a different color.

16. The aforementioned light source, A laser that produces coherent light; or Collimating lens assembly A display device according to any one of claims 1 to 15, comprising at least one of the following.

17. A lens array positioned between the light source and the optical guide panel assembly to homogenize the light emitted by the light source before it enters the first optical expander structure of the optical guide panel assembly. A display device according to any one of claims 1 to 16, further comprising the above.

18. A diffuser positioned between the light source and the optical guide panel assembly to homogenize the light emitted by the light source before it enters the first optical expander structure of the optical guide panel assembly. A display device according to any one of claims 1 to 17, further comprising the above.

19. A first optical expander structure positioned to receive light from a light source, the first optical expander structure having a first set of layers, each of which includes a reflective polarizing layer and a wave retarder layer; and A second optical expander structure is positioned adjacent to the first optical expander structure to receive light from it and emit light toward a display module, the second optical expander structure having a second set of layers, each of which includes a reflective polarizing layer and a wave retarder layer. An optical guide panel assembly equipped with [specific features / features].

20. At least one of the wave retarder layers of the first set of layers and the second set of layers is configured to shift the polarization direction of the light by a first amount, At least one of the wave retarder layers is configured to shift the polarization direction of the light by a second amount different from the first amount, The first and second amounts are each between 5 and 20 degrees. The optical guide panel assembly according to claim 19.

21. The first amount and the second amount are selected, respectively, to control the partial light extraction by the reflective polarizing layer. The optical guide panel assembly according to claim 20.

22. The optical guide panel assembly according to any one of claims 19 to 21, wherein the reflective polarizing layer in the first set of layers is configured to reflect linearly polarized light in a polarization state perpendicular to the polarization state of light emitted by the light source.

23. The optical guide panel assembly according to any one of claims 19 to 22, wherein each of the wave retarder layers of the first set of layers and the second set of layers includes one of a half-wave plate or a quarter-wave plate.

24. The optical guide panel assembly according to any one of claims 19 to 23, wherein each of the wave retarder layers of the first set of layers and the second set of layers is operable to shift the polarization direction of light by 5 to 20 degrees.

25. The optical guide panel assembly according to any one of claims 19 to 24, wherein each of the reflective polarizing layers and each of the wave retarder layers is oriented at an angle of 45 degrees with respect to light incident on the reflective polarizing layer and the wave retarder layer.

26. The optical guide panel assembly according to any one of claims 19 to 25, wherein each of the first set of layers and the second set of layers comprises 3 to 50 sets of layers.

27. The optical guide panel assembly according to any one of claims 19 to 26, wherein the first optical expander structure is operable to receive light from the light source in a first direction and to direct the received light in a second direction perpendicular to the first direction, and the second optical expander structure is operable to direct light received from the first optical expander structure in a third direction perpendicular to the first and second directions.

28. The optical guide panel assembly according to any one of claims 19 to 27, wherein the first optical expander structure is bonded to the second optical expander structure by an optically transparent adhesive.

29. A method for manufacturing an optical guide panel assembly, The step of forming multiple stacked layer sets, each of the multiple stacked layer sets having a reflective polarizing layer, a wave retarder layer, and a plastic layer; The step of cutting the aforementioned set of stacked layers at a 45-degree angle to generate an intermediate light guide panel assembly; A step of cutting a portion of the intermediate light guide panel assembly to form a first optical expander structure and a second optical expander structure; The step of rotating the first optical expander structure relative to the second optical expander structure; and The step of coupling the rotated first optical expander structure to the second optical expander structure to form the optical guide panel assembly. A method that includes [a certain feature].

30. At least one of the wave retarder layers is configured to shift the polarization direction of light by a first amount, At least one of the wave retarder layers is configured to shift the polarization direction of the light by a second amount different from the first amount, The first and second amounts are each between 5 and 20 degrees. The method according to claim 29.

31. The first amount and the second amount are selected, respectively, to control the partial light extraction by the reflective polarizing layer. The method according to claim 30.

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