Light guide plate and image display device

Abstract

The purpose of the present invention is to provide a technology for displaying a clear image.　The present invention provides: a light guide plate (1) which includes a first surface (1a) disposed on the side of an observer and a second surface (1b) facing said first surface (1a), comprises a plurality of reflective optical elements (3) disposed parallel to each other, and has a light-shielding unit (5) disposed near a planar-direction end of each of the reflective optical elements (3), and in which a portion of image light entering from the outside is guided to the pupil of the observer via the reflective optical element (5) and the first surface (1a), and a portion of the image light entering from the outside is shielded by the light-shielding unit (5); and an image display device comprising said light guide plate (1) and an image display element (1004).

Description

Light guide plate and image display device

[0001] The technology according to the present disclosure (hereinafter also referred to as "the technology") relates to a light guide plate and an image display device.

[0002] Augmented reality (AR) is a technology that displays virtual information superimposed on real-world scenes. AR technology superimposes computer-generated information onto real-world images, providing viewers with an experience that integrates real and virtual information.

[0003] In AR technology, image light emitted from an image display element is guided into the observer's field of view using a light guide plate. The light guide plate is an important component for efficiently transmitting image light and superimposing a clear virtual image onto the observer's field of view.

[0004] Light guide plates are incorporated into image display devices such as head-mounted displays and smart glasses, allowing viewers to receive virtual information within their natural field of vision, making AR technology applicable in a variety of fields, including entertainment, education, medicine, and manufacturing.

[0005] For example, Patent Documents 1 to 3 disclose techniques relating to light guide plates.

[0006] International Publication No. 2023 / 026515 Special Publication No. 2023-504611 Special Publication No. 2022-552701

[0007] However, conventional light guide plates have room for improvement in terms of displaying clear images.

[0008] Therefore, a main object of the present technology is to provide a light guide plate and an image display device that display clear images.

[0009] The present technology provides a light guide plate including a first surface disposed on the viewer side and a second surface opposite the first surface, and including a plurality of reflective optical elements parallel to each other, and a light-shielding portion disposed near an end of each of the reflective optical elements in a planar direction, wherein a portion of image light incident from outside is guided to the viewer's pupil via the reflective optical elements and the first surface, and a portion of the image light incident from outside is blocked by the light-shielding portion. The light guide plate may include at least two optical members, and the light-shielding portion may be disposed on at least one of the optical members. The light guide plate may include at least two optical members, and the opposing surfaces of the two optical members may be formed to have a sawtooth cross-sectional shape, and the light-shielding portion may be disposed on at least one of the convex portion and concave portion of the surface. The light guide plate may include at least two optical members, and the optical members may be coupled to each other via a coupling portion. A difference between the refractive index of the coupling portion and the refractive index of the optical members may be less than 0.1. The connecting portion may include a plurality of parallel portions arranged parallel to one another along the longitudinal direction of the optical element, and the light-shielding portion may be arranged in a portion of the connecting portion excluding the parallel portions. The light-shielding portion may be a colored portion of the connecting portion. The light-shielding portion may be a light-absorbing coating or a light-shielding coating. The light-shielding portion may include a metal or a resin. The light-shielding portion may include a wire or a strip-shaped member. The light-shielding portion may have a thickness of 0.2 mm or less in its thinnest direction. The size of each light-shielding portion may vary depending on its position. Image light incident from outside may be totally reflected at least once inside the optical element. The optical element may further include a collimator optical system that converts the image light incident from outside into a substantially parallel beam and outputs it to the reflecting optical element. The collimator optical system may be arranged internally or externally. The light guide plate may include at least two optical elements, and the optical element may include a plurality of flat surfaces arranged parallel to one another along the longitudinal direction, and the reflecting optical elements may be arranged on the plurality of flat surfaces. Each of the reflective optical elements may reflect some or all of the image light.At least one of the first surface and the second surface may be a flat surface. At least one of the first surface and the second surface may be a curved surface. The present technology also provides an image display device including: a light guide plate; and an image display element that emits image light to the light guide plate, wherein the light guide plate includes a first surface disposed on a viewer side and a second surface facing the first surface, and a plurality of reflective optical elements that are parallel to each other, and each of the reflective optical elements has a light-shielding portion disposed near an end in a planar direction thereof, wherein a portion of the image light incident from the image display element is guided to the viewer's pupil via the reflective optical element and the first surface, and a portion of the image light incident from the image display element is shielded by the light-shielding portion.

[0010] 1 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 2 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 3 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 4 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 5 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 6 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 7 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 8 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 9 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 10 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 11 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. 12 is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology. Fig. 21A is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to an embodiment of the present technology; Fig. 21B is a schematic perspective view showing an example of a configuration of an image display device 1000 according to an embodiment of the present technology; Fig. 21C is a schematic cross-sectional view showing an example of a configuration of a light guide plate 1 according to a comparative example of the present technology; Fig. 21D ...E is a schematic cross-sectional view showing an example of an image displayed by an image display element 1004; Fig. 21F is a schematic cross-sectional view showing an example of an image visually recognized by an observer;

[0011] Hereinafter, preferred embodiments for implementing the present technology will be described with reference to the drawings. Note that the embodiment described below shows an example of a typical embodiment of the present technology, and does not limit the scope of the present technology. In addition, the present technology can be combined with any of the following examples and their modifications.

[0012] In the following description of the embodiments, configurations may be described using terms including "approximately," such as "approximately parallel" and "approximately perpendicular." For example, "approximately parallel" does not only mean completely parallel, but also means substantially parallel, i.e., including a state where the orientation is deviated from the completely parallel state by, for example, a few percent. The same applies to other terms including "approximately." Furthermore, each figure is a schematic diagram and is not necessarily an accurate depiction. The scale of the drawings has been exaggerated to make the features of the technology easier to understand. Therefore, it should be noted that the scale of the drawings and the scale of the actual device are not necessarily the same.

[0013] Unless otherwise specified, in the drawings, "top" means the top or upper side in the drawing, "bottom" means the bottom or lower side in the drawing, "left" means the left or left side in the drawing, and "right" means the right or right side in the drawing. Furthermore, in the drawings, the same or equivalent elements or members are given the same reference numerals, and redundant explanations will be omitted.

[0014] The description will be given in the following order: 1. First embodiment of the present technology (Example 1 of light guide plate) (1) Overall configuration (2) Comparative example (3) Example 2. Second embodiment of the present technology (Example 2 of light guide plate) 3. Third embodiment of the present technology (Example 3 of light guide plate) 4. Fourth embodiment of the present technology (Example 4 of light guide plate) 5. Fifth embodiment of the present technology (Example 5 of light guide plate) 6. Sixth embodiment of the present technology (Example 6 of light guide plate) 7. Seventh embodiment of the present technology (Example 7 of light guide plate) 8. Eighth embodiment of the present technology (Example 8 of light guide plate) 9. Ninth embodiment of the present technology (Example 9 of light guide plate) 10. Tenth embodiment of the present technology (Example of image display device)

[0015] [1. First Embodiment of the Present Technology (Example 1 of Light Guide Plate)] [(1) Overall Configuration] A light guide plate according to the present technology is incorporated into an image display device such as a head-mounted display or smart glasses. An example of this image display device will be described with reference to Fig. 18 . Fig. 18 is a schematic perspective view showing a configuration example of an image display device 1000 according to an embodiment of the present technology.

[0016] As shown in Fig. 18, a frame 1001 forms the framework of the entire image display device 1000 and serves to support or secure the other components. The frame 1001 is designed to allow the viewer to wear the device stably. Temples 1002 are attached to both sides of the frame 1001. The temples 1002 are placed over the viewer's ears to help secure the device and provide stability and comfort when worn.

[0017] A drive substrate 1003 is disposed on the frame 1001. The drive substrate 1003 controls or drives the image display element 1004 and other electronic components, and processes signals and supplies power. The image display element 1004 is disposed on the drive substrate 1003. This image display element 1004 generates a virtual image that is visually recognized by the observer. Technologies such as organic light emitting diodes (OLEDs) and liquid crystal displays (LCDs) are used for the image display element 1004.

[0018] In addition, a flexible substrate 1007 is disposed on the frame 1001 to ensure electrical connection between the components. The flexible substrate 1007 allows wiring to be flexibly arranged in the limited space within the device, and efficiently transmits signals between the components.

[0019] An image signal generator 1005 and a power supply 1006 are disposed on temple 1002. This image signal generator 1005 is responsible for generating and transmitting signals for display on image display element 1004. Image signal generator 1005 includes a processor, a graphics chip, etc., and processes and converts content.

[0020] The power supply 1006 is an important component that supplies power to the entire image display device 1000. Typically, a battery or other cell is used as the power supply 1006, and determines the operating time of the device.

[0021] The arrangement positions of the components are not limited to this example. For example, in this example, the drive substrate 1003 is arranged on the frame 1001, but the drive substrate 1003 may be arranged on the temple 1002.

[0022] The light guide plate 1 serves to guide the image light emitted from the image display element 1004 into the viewer's field of view. The light guide plate 1 is mainly composed of a transparent optical member, and efficiently transmits the image light and superimposes a virtual image in the viewer's field of view. This optical member is made of, for example, a transparent or translucent resin.

[0023] A plurality of reflective optical elements 3 are arranged parallel to one another along the longitudinal direction inside the light guide plate 1. Each reflective optical element 3 is arranged at an angle with respect to the surface that faces the viewer, and reflects part or all of the image light, thereby guiding the image light to the viewer's pupil.

[0024] The reflective optical element 3 may be a mirror that reflects all of the image light, or a half mirror that reflects part of the image light and transmits part of it. When the reflective optical element 3 is a half mirror, the reflective optical element 3 is also visible when the observer views the outside world through the light guide plate 1, making the field of view brighter.

[0025] The reflective optical element 3 may include a metal thin film such as aluminum (Al), gold (Au), silver (Ag), or chromium (Cr). Alternatively, the reflective optical element 3 may include a dielectric multilayer film made of, for example, silicon dioxide (SiO), titanium dioxide (TiO), aluminum oxide (AlO), zirconium oxide (ZrO), or niobium pentoxide (NbO). Alternatively, the reflective optical element 3 may include a multilayer film combining the metal and the dielectric.

[0026] In this configuration example, the collimator optical system 41 is disposed inside the light guide plate 1. The collimator optical system 41 converts image light incident from the image display element 1004 disposed outside the light guide plate 1 into a substantially parallel beam of light and emits the parallel beam of light to each of the reflecting optical elements 3. Each of the reflecting optical elements 3 reflects the image light in an appropriate direction to display an image in the field of view of the observer. The image light converted into a substantially parallel beam of light by the collimator optical system 41 is guided to the observer's eyes by the multiple reflecting optical elements 3.

[0027] The light beams do not have to be perfectly parallel, and may deviate slightly from the parallelism. When the collimator optical system 41 converts the image light into perfectly parallel light beams, the image seen by the observer is perceived as being at infinity. However, when using this image display device to observe a virtual image while looking at something close to the observer, the display position of the virtual image needs to be approximately the same as that of the outside world.

[0028] Therefore, in this case, the display position of the virtual image can be adjusted by slightly diverging the image light from the image display device 1000. For example, if it is desired to display a virtual image one meter ahead of the observer, the angle of each light beam can be adjusted to match the angle of light emitted from an object at that distance, thereby making it possible to display the virtual image one meter ahead.

[0029] (2) Comparative Example Before describing one of the features of the present technology, a comparative example of the present technology will be described with reference to Fig. 19. Fig. 19 is a schematic cross-sectional view showing an example of the configuration of a light guide plate 1 according to the comparative example of the present technology.

[0030] 19, this light guide plate 1 is constructed by laminating multiple pieces of glass. There are multiple internal surfaces 1h within the light guide plate 1. Each internal surface 1h is disposed at an angle to the parallel external surface 1g of the light guide plate 1. Each internal surface 1h is covered with a coating that has specific reflective properties.

[0031] Image light incident from the outside is repeatedly internally reflected within the light guide plate 1, reflected by each of the inner surfaces 1h, and guided into the field of view of the observer.

[0032] Such a light guide plate 1 is produced by laminating glass, cutting, and polishing it, which tends to be expensive to manufacture and heavy. Furthermore, the glass light guide plate 1 is vulnerable to impacts and poses safety problems.

[0033] Another comparative example of the present technology will be described with reference to Fig. 20. Fig. 20 is a schematic cross-sectional view showing an example of the configuration of a light guide plate 1 according to the comparative example of the present technology.

[0034] 20 , this light guide plate 1 is configured by joining two optical members 11 and 12 together at a joint (such as with an adhesive). Opposing surfaces 1e and 1f of the two optical members 11 and 12 are formed to have sawtooth cross-sectional shapes. These surfaces 1e and 1f include a plurality of planes parallel to each other. A reflective optical element 3 is disposed on each plane.

[0035] Image light incident from the outside is repeatedly internally reflected within the light guide plate 1, reflected by each of the reflecting optical elements 3, and guided into the field of view of the observer.

[0036] The optical members 11 and 12 are manufactured by injection molding of resin, which makes it possible to reduce manufacturing costs and also provides the advantage of being lighter in weight than glass.

[0037] However, there is room for improvement in terms of clear image display in this light guide plate 1. Image light passing through the circled region R in this light guide plate 1 is refracted in an unintended direction, resulting in unwanted light called flare.

[0038] This will be described with reference to Fig. 21. Fig. 21A is an example of an image displayed by the image display element 1004. Fig. 21B is an example of an image visually recognized by the observer.

[0039] As shown in Fig. 21A, image display element 1004 displays an image of a white square on a black background. In this case, the image seen by the viewer has flare F that looks like a tail above and below the white square, as shown in Fig. 21B, causing the image to appear blurred and reducing the clarity of the image. Research by the inventors has revealed that this phenomenon is caused by the slight refraction of certain light rays within the light guide plate.

[0040] This will be described with reference to Fig. 22. Fig. 22 is a schematic cross-sectional view showing an example of the configuration of a light guide plate 1 according to a comparative example of the present technology. A schematic cross-sectional view of the entire light guide plate 1 is shown on the left side of the figure, and a detailed view of an enlarged portion of the cross-sectional view is shown on the right side.

[0041] As shown in the enlarged detailed view, a joint 2 is filled between the first optical member 11 and the second optical member 12. The first optical member 11 and the second optical member 12 are each made by injection molding of resin, which causes a slight curvature at the corners.

[0042] This detailed view shows how image light traveling within the light guide plate 1 is refracted, causing flare. The first image light L1 is slightly refracted at the interface between the second optical member 12 and the coupling unit 2, and also slightly refracted at the interface between the coupling unit 2 and the first optical member 11. The first image light L1 before passing through the coupling unit 2 and the first image light L1 after passing through the coupling unit 2 are approximately parallel to each other. Therefore, the first image light L1 travels along an ideal light transmission path and is guided to the viewer's field of view.

[0043] On the other hand, the second image light L2 is slightly refracted at the interface between the second optical member 12 and the coupling portion 2, and is also slightly refracted at the interface between the coupling portion 2 and the first optical member 11. The second image light L2 before passing through the coupling portion 2 and the second image light L2 after passing through the coupling portion 2 are non-parallel to each other. This refraction causes flare, which impairs the clarity of the image.

[0044] [(3) Example] Therefore, the present technology provides a light guide plate that can display a clear image by suppressing the occurrence of this flare. Specifically, the present technology provides a light guide plate that includes a first surface disposed on the viewer side and a second surface facing the first surface, and that is equipped with a plurality of reflective optical elements that are parallel to each other, and a light-shielding portion disposed near an end of each of the reflective optical elements in a planar direction, so that a portion of image light incident from outside is guided to the viewer's pupil via the reflective optical elements and the first surface, and a portion of the image light incident from outside is blocked by the light-shielding portion.

[0045] A configuration example of a light guide plate according to an embodiment of the present technology will be described with reference to Fig. 1. Fig. 1 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology.

[0046] 1, the light guide plate 1 includes a first surface 1a disposed on the viewer side and a second surface 1b opposite to the first surface 1a, and is internally provided with a plurality of parallel reflective optical elements 3. In this configuration example, the first surface 1a and the second surface 1b are flat surfaces.

[0047] A first collimator optical system 41 is disposed on a third surface 1c facing the image display element 1004. A second collimator optical system 42 is disposed on a fourth surface 1d facing the third surface 1c.

[0048] Image light incident from outside the light guide plate 1 is totally reflected at least once inside the light guide plate 1. In this configuration example, image light incident from the image display element 1004 is refracted by the first collimator optical system 41 to become a nearly parallel beam of light, and is totally reflected by the second surface 1b. Total reflection of light refers to a phenomenon in which, when light travels from a medium with a high refractive index to a medium with a low refractive index, if the angle of incidence is equal to or greater than the critical angle, the light is completely reflected and does not pass through the medium boundary.

[0049] Specifically, when light travels from a medium with a high refractive index (such as glass or plastic) to a medium with a low refractive index (such as air), if the angle of incidence exceeds a certain angle (critical angle), the light is completely reflected at the interface. At this time, the reflected light is reflected at an angle equal to the angle of incidence. The critical angle depends on the refractive index of both media and is calculated based on Snell's law.

[0050] Total internal reflection (TIR) ​​can be used to transmit light efficiently and minimize loss. For example, a light guide plate can use this phenomenon to reflect light internally and guide it toward the viewer's field of view.

[0051] The image light totally reflected by the second surface 1b is converted into a substantially parallel beam by the second collimator optical system 42 and is incident on each of the plurality of reflective optical elements 3. Each reflective optical element 3 is disposed at an angle with respect to the first surface 1a. As a result, each reflective optical element 3 reflects the image light from the second collimator optical system 42 and guides the image light into the viewer's field of view. In other words, a portion of the image light incident from outside is guided to the viewer's pupil via the reflective optical element 3 and the first surface 1a.

[0052] The light guide plate 1 has light-shielding portions 5 arranged near the ends of each of the reflective optical elements 3 in the planar direction. A portion of the image light incident from the outside is blocked by these light-shielding portions 5. In the figure, the shape of these light-shielding portions 5 is shown schematically. These light-shielding portions 5 block image light that causes flare. This allows the present technology to improve image clarity and provide the viewer with a high-quality visual experience.

[0053] The term "vicinity" refers to a range immediately adjacent to or very close to a specific reference point. Specifically, even if the light-shielding portion 5 is disposed at a position away from the end of the reflective optical element 3 in the planar direction, it means that the light-shielding portion 5 is disposed near the end as long as it is within a range where it can block image light.

[0054] The above description of the light guide plate according to the first embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0055] 2. Second Embodiment of the Present Technology (Example 2 of Light Guide Plate) A configuration example of a light guide plate according to an embodiment of the present technology will be described with reference to Fig. 2. Fig. 2 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology.

[0056] 2, the light guide plate 1 includes at least two optical members 11 and 12. The opposing surfaces of the two optical members 11 and 12 are formed to have a sawtooth cross-sectional shape. These surfaces include a plurality of flat surfaces arranged parallel to each other along the longitudinal direction of the optical members 11 and 12. A reflective optical element 3 is arranged on each of the plurality of flat surfaces.

[0057] Each light-shielding portion 5 is disposed near an end in the planar direction of each reflective optical element 3. Each light-shielding portion 5 may be disposed near one end in the planar direction of each reflective optical element 3, or may be disposed near both ends in the planar direction. In this configuration example, the light-shielding portion 5 is disposed near the end on the second surface 1b side in the planar direction.

[0058] Another configuration example of the light guide plate will be described with reference to Fig. 3 and Fig. 4. Fig. 3 and Fig. 4 are schematic cross-sectional views showing a configuration example of the light guide plate 1 according to an embodiment of the present technology.

[0059] As shown in Fig. 3, the light-shielding portion 5 may be disposed near the end portion on the first surface 1a side in the planar direction. Alternatively, as shown in Fig. 4, the light-shielding portion 5 may be disposed near the end portions on both the first surface 1a side and the second surface 1b side in the planar direction.

[0060] Although not shown in the figure, there may be a mixture of shading sections 5 arranged near the end on the second surface 1b side in the planar direction and shading sections 5 arranged near the end on the first surface 1a side in the planar direction.

[0061] Here, a state before the two optical members 11 and 12 are bonded to each other will be described with reference to Fig. 5. Fig. 5 is a schematic cross-sectional view showing an example of the configuration of a light guide plate 1 according to an embodiment of the present technology.

[0062] 5 , the light-shielding portion 5 may be disposed on at least one of at least two optical members (a first optical member 11 and a second optical member 12). In this configuration example, the light-shielding portion 5 is disposed on the second optical member 12. The reflective optical element 3 is disposed on the first optical member 11.

[0063] The opposing surfaces 1e and 1f of the first optical member 11 and the second optical member 12 are formed to have a sawtooth cross-sectional shape. Therefore, these surfaces 1e and 1f have convex portions and concave portions. The light-shielding portion 5 is disposed on at least one of the convex portions and concave portions of the surfaces 1e and 1f. In this configuration example, the light-shielding portion 5 is disposed in the concave portion of the surface 1f of the second optical member 12.

[0064] On the other hand, the surface 1e of the first optical member 11 also has a convex portion and a concave portion. The side surfaces of the convex portion and the concave portion are parallel to each other. The reflective optical elements 3 are respectively disposed on these parallel surfaces.

[0065] The first optical member 11 and the second optical member 12 are joined together via a joining portion (such as an adhesive), thereby producing the light guide plate 1 shown in FIG.

[0066] The bonding portion is preferably made of a highly transparent optical resin material. The bonding portion can be formed using, for example, an acrylic adhesive, an epoxy adhesive, a silicone adhesive, or a transparent adhesive film. Each of these adhesive materials has its own unique properties, and is selected depending on the application and environment in which it will be used.

[0067] The above description of the light guide plate according to the second embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0068] 3. Third Embodiment of the Present Technology (Example 3 of Light Guide Plate) A configuration example of a light guide plate according to an embodiment of the present technology will be described with reference to Fig. 6. Fig. 6 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology. Fig. 6 is a detailed view in which a portion of the sawtooth cross section is enlarged.

[0069] As shown in Fig. 6, the optical members 11 and 12 are coupled to each other via a coupling portion 2. In this case, if there is a large difference between the refractive index of the coupling portion 2 and the refractive index of the optical members 11 and 12, light rays are refracted significantly. As a result, when a viewer views the outside world through the light guide plate 1, the outside world appears distorted at the refracted portion, which may cause a sense of discomfort. Therefore, it is preferable that the difference between the refractive index of the coupling portion 2 and the refractive index of the optical members 11 and 12 is small. Specifically, it is preferable that the difference between the refractive index of the coupling portion 2 and the refractive index of the optical members 11 and 12 is less than 0.1.

[0070] The connecting portion 2 includes a plurality of parallel portions 2a arranged parallel to one another along the longitudinal direction of the optical members 11 and 12. In this case, the light-shielding portion 5 is arranged in a portion of the connecting portion 2 excluding the parallel portions 2a. The light-shielding portion 5 blocks image light that causes flare.

[0071] The embodiment of the light-shielding portion 5 is not particularly limited. The following provides examples of the configuration of the light-shielding portion 5, but it goes without saying that the light-shielding portion 5 is not limited to these examples. For example, as shown in FIG. 6 , the light-shielding portion 5 may have a colored portion of the coupling portion 2. The color to be colored is preferably a color that has a light-absorbing function. Examples of light-absorbing colors include black, dark blue, and dark brown. These colors have the property of effectively absorbing light in a wide wavelength range, and are therefore suitable for the purpose of the light-shielding portion.

[0072] The light-shielding portion 5 is disposed at the corner of the surface having a sawtooth cross section. By coloring the entire connecting portion 2 disposed at this corner, it is possible to widely block image light that causes flare.

[0073] Other configuration examples of the light blocking portion 5 will be described with reference to Fig. 7 and Fig. 8. Fig. 7 and Fig. 8 are schematic cross-sectional views showing configuration examples of the light guide plate 1 according to an embodiment of the present technology.

[0074] As shown in Figure 7, the first optical member 11 and the second optical member 12 are each made by injection molding of resin, which causes slight curvature at the corners. A light-shielding portion 5 that blocks image light that causes flare may be disposed at the corners with this slight curvature. This light-shielding portion 5 is a light-absorbing coating or a light-shielding coating. The light-shielding portion 5 is disposed at the convex portion of the surface of the first optical member 11 that has a sawtooth cross-sectional shape.

[0075] The light-absorbing coating is a coating material that has the property of absorbing light. The light-shielding coating is a coating material that has high light-shielding properties. The light-absorbing coating or the light-shielding coating may be, for example, a dielectric multilayer film or a multilayer film similar to that of the reflecting optical element 3. Furthermore, the light-absorbing coating or the light-shielding coating may be a paint in which a light-shielding pigment such as carbon black or a titanium-based black pigment is dispersed.

[0076] Furthermore, the light-absorbing or light-blocking coating may be made of a structural light-absorbing material. A structural light-absorbing material is an advanced material that utilizes a fine nanostructure to achieve excellent light-absorbing properties. This nanostructure causes multiple reflections and absorption of light, improving the efficiency of light absorption. Specific examples include nanowire structures, nanotube structures, and black silicon.

[0077] In this configuration example, the light blocking portion 5 is a strip-shaped member. The strip-shaped member is a long, thin material with a flat, rectangular cross section (see FIG. 18), and is characterized by its wide width and thin thickness.

[0078] As another configuration example of the light-shielding portion 5, as shown in Fig. 8, the light-shielding portion 5 may be embedded in the coupling portion 2 filled between the first optical member 11 and the second optical member 12. The light-shielding portion 5 is disposed at the corner of the surface having a sawtooth cross-sectional shape. The light-shielding portion 5 includes metal or resin.

[0079] Examples of the metal used for the light-shielding portion 5 include the same metal as that used for the reflecting optical element 3. Examples of the resin that can be used include polycarbonate, ABS resin, and epoxy resin. These materials may also be used with paints in which light-shielding pigments such as carbon black and titanium-based black pigments are dispersed.

[0080] In this configuration example, the light blocking portion 5 is a wire material. The wire material is a long, thin material with a circular cross section (see FIG. 18).

[0081] In the configurations shown in FIGS. 7 and 8, the area where the light-shielding portion 5 is arranged is more partial than in the configuration shown in FIG. 6, but still has a sufficient light-shielding function.

[0082] Although there are no particular limitations on the thickness of the light-shielding portion 5, it is preferable that the thickness of the light-shielding portion 5 in the thinnest direction be 0.2 mm or less. If the thickness of the light-shielding portion 5 is this value, the light-shielding portion 5 is difficult to see even when placed in front of the viewer's eyes, and therefore is unlikely to give the viewer a sense of incongruity.

[0083] The above description of the light guide plate according to the third embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0084] [4. Fourth Embodiment of the Present Technology (Example 4 of Light Guide Plate)] In the above-described configuration example related to the present technology, a plurality of reflective optical elements are arranged on the first optical member, and a plurality of light-blocking portions are arranged on the second optical member. This configuration is not limited to this, and, for example, a plurality of light-blocking portions and a plurality of reflective optical elements may be arranged on the second optical member. This will be described with reference to FIG. 9 . FIG. 9 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology.

[0085] 9 , in this configuration example, a plurality of light-shielding portions 5 and a plurality of reflective optical elements 3 are arranged on the second optical member 12. By combining this second optical member 12 with the first optical member 11, the light guide plate 1 can be manufactured.

[0086] Although not shown, for example, a plurality of light-shielding portions may be arranged on the first optical member and a plurality of reflective optical elements may be arranged on the second optical member, or a plurality of light-shielding portions and a plurality of reflective optical elements may be arranged on the first optical member.

[0087] Furthermore, some of the plurality of light-shielding portions may be arranged on the first optical member and the rest on the second optical member. Also, some of the plurality of reflective optical elements may be arranged on the first optical member and the rest on the second optical member.

[0088] The above description of the light guide plate according to the fourth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0089] [5. Fifth Embodiment of the Present Technology (Fifth Light Guide Plate Example)] In the above-described configuration example related to the present technology, the opposing surfaces of the two optical members 11 and 12 are formed to have a sawtooth cross-sectional shape. However, the surface of one optical member facing the other optical member may be formed to have, for example, a flat shape. This will be described with reference to FIGS. 10 and 11. FIGS. 10 and 11 are schematic cross-sectional views showing an exemplary configuration of a light guide plate 1 according to an embodiment of the present technology.

[0090] 10 , in this configuration example, the surface 1e of the first optical member 11 that faces the second optical member 12 is formed to have a flat shape. When manufacturing a light guide plate 1 with such a configuration, it is not necessary to form both of the opposing surfaces to have a sawtooth cross-sectional shape. This reduces manufacturing costs and makes it easier to position both optical members.

[0091] 11 can be manufactured by bonding the first optical member 11 and the second optical member 12 via the bonding portion 2. The bonding portion 2 can be filled into the gap between the surface 1e having a planar shape and the surface 1f having a sawtooth cross-sectional shape.

[0092] Although not shown in the drawings, for example, the surface of the second optical member that faces the first optical member may be formed to have a flat shape.

[0093] The above description of the light guide plate according to the fifth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0094] [6. Sixth Embodiment of the Present Technology (Example 6 of Light Guide Plate)] A light guide plate according to the present technology includes a first surface disposed on the viewer side and a second surface facing the first surface. In this case, at least one of the first surface and the second surface may be a curved surface. Furthermore, at least one of the first surface and the second surface may be a flat surface. This will be described with reference to FIGS. 12 and 13. FIGS. 12 and 13 are schematic cross-sectional views showing configuration examples of a light guide plate 1 according to an embodiment of the present technology.

[0095] As shown in Figure 12, the light guide plate 1 includes a first surface 1a disposed on the viewer side and a second surface 1b opposite the first surface 1a. In this configuration example, the first surface 1a is a curved surface. The curved first surface 1a refracts light according to the viewer's visual acuity, enabling diopter correction. This allows the viewer to view a clearer image. In this configuration example, the first surface 1a is concave toward the viewer side and has a shape that is recessed inward. This allows the light guide plate 1 to adjust the degree of myopia of the viewer.

[0096] By joining the first optical member 11 and the second optical member 12 via the joining portion 2, the light guide plate 1 shown in FIG. 13 can be manufactured.

[0097] Although not shown in the drawings, the first surface 1a may be convex toward the viewer and may have a shape that bulges outward, allowing the degree of farsightedness of the viewer to be adjusted.

[0098] In addition, although the second surface 1b is a flat surface in this configuration example, the second surface 1b may be a curved surface. This will be described with reference to Fig. 14. Fig. 14 is a schematic cross-sectional view showing an example of the configuration of a light guide plate 1 according to an embodiment of the present technology.

[0099] As shown in Fig. 14, in this configuration example, the light guide plate 1 includes a first optical member 11, a second optical member 12, and a third optical member 13. The light guide plate 1 includes a first surface 1a disposed on the viewer side and a second surface 1b facing the first surface. The second surface 1b is a curved surface. Because the second surface 1b is a curved surface, light is refracted in accordance with the viewer's eyesight, enabling diopter correction. This allows the viewer to clearly see the outside world.

[0100] The image light incident from the image display element 1004 needs to be totally reflected at least once inside the optical member 1004. Therefore, it is preferable to dispose a layer that reflects the image light between the second optical member 12 and the third optical member 13. This layer can be, for example, an air layer or an optical filter.

[0101] Because the air layer has a low refractive index, total reflection easily occurs at the interface with the adjacent second optical member 12, which has a high refractive index. Since no special material is required to form the air layer, it is cost-effective. Furthermore, since the air layer does not substantially increase the mass, it contributes to reducing the weight of the light guide plate 1.

[0102] Optical filters can be designed to reflect light of specific wavelengths, allowing image light to be reflected with high efficiency while blocking light of unnecessary wavelengths. By adjusting the refractive index of optical filters, the conditions for total reflection can be optimized, enabling higher quality image display.

[0103] Furthermore, the optical filter is preferably designed to transmit light from the outside world, thereby allowing the observer to see the outside world.

[0104] For example, when an air layer is used, a certain gap is provided between the second optical member 12 and the third optical member 13, and the design is such that air is present between them. On the other hand, when an optical filter is used, the conditions for total reflection can be optimized by thinly coating the surface of the second optical member 12 with an optical filter layer.

[0105] Although not shown in the drawings, both the first surface 1a and the second surface 1b may be curved surfaces.

[0106] The above description of the light guide plate according to the sixth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0107] 7. Seventh Embodiment of the Present Technology (Seventh Example of Light Guide Plate) A configuration example of a light guide plate according to an embodiment of the present technology will be described with reference to Fig. 15. Fig. 15 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology.

[0108] 15 , the collimator optical system 41 may be disposed outside the light guide plate 1. This collimator optical system 41 converts the image light incident from the image display element 1004 into a substantially parallel beam. The image light converted into a substantially parallel beam is totally reflected by the second surface 1 b and reflected by the second reflecting optical element 32. Thereafter, a portion of this image light is guided to the viewer's pupil via the first reflecting optical element 3 and the first surface 1 a, and a portion of the image light is blocked by the light blocking portion 5.

[0109] In this configuration example, the collimator optical system 41 is disposed on the side facing the image display element 1004, but the location of the collimator optical system 41 is not particularly limited.

[0110] The above description of the light guide plate according to the seventh embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0111] 8. Eighth Embodiment of the Present Technology (Eighth Example of Light Guide Plate) A configuration example of a light guide plate according to an embodiment of the present technology will be described with reference to Fig. 16. Fig. 16 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology.

[0112] 16 , the image display element 1004 may be disposed below the light guide plate 1 as viewed from the viewer. In this configuration example, the image light incident from the image display element 1004 is converted into a substantially parallel beam of light by the collimator optical system 42. A portion of this image light is guided to the viewer's pupil via the reflective optical element 3 and the first surface 1 a, and a portion of the image light is blocked by the light blocking portion 5.

[0113] The above description of the light guide plate according to the eighth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0114] 9. Ninth Embodiment of the Present Technology (Ninth Example of Light Guide Plate)] A configuration example of a light guide plate according to an embodiment of the present technology will be described with reference to Fig. 17. Fig. 17 is a schematic cross-sectional view showing a configuration example of a light guide plate 1 according to an embodiment of the present technology.

[0115] 17, it is preferable that the size of each light-shielding portion 5 differs depending on the position where it is arranged. This is because the angle of the image light incident on each reflective optical element 3 is slightly different between the upper and lower portions. To accommodate this difference in angle, it is preferable that the sizes of the light-shielding portions 5 differ.

[0116] In this configuration example, the size of the light-shielding portion 5 gradually increases from the top to the bottom of the light guide plate 1, but the configuration is not limited to this. For example, the size of the light-shielding portion 5 may gradually decrease from the top to the bottom of the light guide plate 1.

[0117] In this figure, the change in size of the light-shielding portion 5 is exaggerated so that the change in size of the light-shielding portion 5 can be clearly seen.

[0118] The above description of the light guide plate according to the ninth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0119] [10. Tenth Embodiment of the Present Technology (Example of Image Display Device)] The present technology provides an image display device including: a light guide plate; and an image display element that emits image light to the light guide plate, wherein the light guide plate includes a first surface disposed on the viewer side and a second surface facing the first surface; and wherein the image display device includes a plurality of reflective optical elements that are parallel to each other, and each of the reflective optical elements has a light-shielding portion disposed near an end in a planar direction thereof, wherein a portion of the image light incident from the image display element is guided to a pupil of the viewer via the reflective optical element and the first surface, and a portion of the image light incident from the image display element is shielded by the light-shielding portion.

[0120] An example configuration of an image display device according to an embodiment of the present technology will be described with reference to Fig. 18 again. As shown in Fig. 18, the image display device 1000 includes a light guide plate 1 and an image display element 1004 that emits image light to the light guide plate 1.

[0121] The light guide plate 1 includes a first surface disposed on the viewer side and a second surface opposite to the first surface, and is provided with a plurality of reflective optical elements 3 that are parallel to one another.

[0122] The light guide plate 1 has light blocking portions 5 arranged near the ends of the respective reflecting optical elements 3 in the planar direction.

[0123] A part of the image light incident from the image display element 1004 is guided to the viewer's pupil via the reflecting optical element 3 and the first surface, and a part of the image light incident from the image display element 1004 is blocked by the light blocking portion 5 .

[0124] The above description of the image display device according to the tenth embodiment of the present technology can be applied to other embodiments of the present technology unless there is a particular technical contradiction.

[0125] It should be noted that the embodiments of the present technology are not limited to the above-described embodiments, and various modifications are possible within the scope of the present technology. The specific numerical values, shapes, materials (including compositions), etc. described in each embodiment are merely examples, and the present technology is not limited to these.

[0126] The present technology can also have the following configurations. [1] A light guide plate including a first surface disposed on the viewer side and a second surface opposite the first surface, and including a plurality of reflective optical elements parallel to each other, and a light-shielding portion disposed near an end of each of the reflective optical elements in a planar direction, wherein a portion of image light incident from outside is guided to the viewer's pupil via the reflective optical elements and the first surface, and wherein a portion of the image light incident from outside is blocked by the light-shielding portion. [2] The light guide plate according to [1], wherein the light guide plate includes at least two optical members, and the light-shielding portion is disposed on at least one of the optical members. [3] The light guide plate according to [1] or [2], wherein the light guide plate includes at least two optical members, and wherein opposing surfaces of the two optical members are formed to have a sawtooth cross-sectional shape, and the light-shielding portion is disposed on at least one of a convex portion and a concave portion of the surface. [4] The light guide plate according to any one of [1] to [3], wherein the light guide plate includes at least two optical members, and the optical members are coupled to each other via a coupling portion. [5] The light guide plate according to [4], wherein the difference between the refractive index of the coupling portion and the refractive index of the optical members is less than 0.1. [6] The light guide plate according to [4] or [5], wherein the coupling portion includes a plurality of parallel portions arranged parallel to each other along the longitudinal direction of the optical members, and the light-shielding portion is arranged in a portion of the coupling portion excluding the parallel portions. [7] The light guide plate according to any one of [4] to [6], wherein the light-shielding portion is a colored portion of the coupling portion. [8] The light guide plate according to any one of [1] to [7], wherein the light-shielding portion is a light-absorbing coating or a light-shielding coating. [9] The light guide plate according to any one of [1] to [8], wherein the light-shielding portion contains a metal or a resin.

[10] The light guide plate according to any one of [1] to [9], wherein the light-shielding portion includes a wire or a strip-shaped member.

[11] The light guide plate according to any one of [1] to

[10] , wherein the light-shielding portion has a thickness of 0.2 mm or less in the thinnest direction.

[12] The light guide plate according to any one of [1] to

[11] , wherein the size of each of the light-shielding portions varies depending on the position at which it is arranged.

[13] The light guide plate according to any one of [1] to

[12] , wherein image light incident from the outside is totally reflected at least once inside.

[14] The light guide plate according to any one of [1] to

[13] , further comprising a collimator optical system that converts the image light incident from the outside into a substantially parallel beam of light and outputs it to the reflecting optical element.

[15] The light guide plate according to

[14] , wherein the collimator optical system is arranged internally or externally.

[16] The light guide plate according to any one of [1] to

[15] , wherein the light guide plate comprises at least two optical members, each of which includes a plurality of flat surfaces arranged parallel to one another along the longitudinal direction, and the reflecting optical elements are arranged on the plurality of flat surfaces.

[17] The light guide plate according to any one of [1] to

[16] , wherein each of the reflecting optical elements reflects a part or all of the image light.

[18] The light guide plate according to any one of [1] to

[17] , wherein at least one of the first surface and the second surface is a flat surface.

[19] The light guide plate according to any one of [1] to

[18] , wherein at least one of the first surface and the second surface is a curved surface.

[20] An image display device comprising: a light guide plate; and an image display element that emits image light to the light guide plate, wherein the light guide plate includes a first surface arranged on the viewer side and a second surface facing the first surface, and wherein the image display device comprises a plurality of reflective optical elements that are parallel to each other, and each of the reflective optical elements has a light-shielding portion arranged near an end in a planar direction, wherein a portion of the image light incident from the image display element is guided to the pupil of the viewer via the reflective optical element and the first surface, and a portion of the image light incident from the image display element is shielded by the light-shielding portion.

[0127] REFERENCE SIGNS LIST 1000 Image display device 1004 Image display element 1 Light guide plate 11 First optical member 12 Second optical member 13 Third optical member 1a First surface 1b Second surface 1c Third surface 1d Fourth surface 2 Coupling portion 2a Parallel portion 3 Reflecting optical element 32 Second reflecting optical element 41 Collimator optical system 42 Second collimator optical system 5 Light blocking portion

Claims

1. A light guide plate including a first surface arranged on the observer side and a second surface opposite the first surface, and having a plurality of reflective optical elements parallel to each other, and a light-shielding portion arranged near the end of each of the reflective optical elements in a planar direction, wherein a portion of image light incident from outside is guided to the observer's pupil via the reflective optical elements and the first surface, and a portion of the image light incident from outside is blocked by the light-shielding portion.

2. The light guide plate according to claim 1, wherein the light guide plate comprises at least two optical members, and the light blocking portion is disposed on at least one of the optical members.

3. The light guide plate according to claim 1, wherein the light guide plate comprises at least two optical elements, the opposing surfaces of the two optical elements are formed to have a sawtooth cross-sectional shape, and the light blocking portion is disposed on at least one of the convex portions and concave portions of the surfaces.

4. The light guide plate according to claim 1, wherein the light guide plate comprises at least two optical members, the optical members being coupled to each other via a coupling portion.

5. The light guide plate according to claim 4, wherein the difference between the refractive index of the coupling portion and the refractive index of the optical member is less than 0.

1.

6. The light guide plate according to claim 4, wherein the joint portion includes a plurality of parallel portions arranged parallel to one another along the longitudinal direction of the optical member, and the light blocking portion is arranged in a portion of the joint portion excluding the parallel portions.

7. The light guide plate according to claim 4, wherein the light blocking portion is a colored portion of the coupling portion.

8. The light guide plate according to claim 1, wherein the light-shielding portion is a light-absorbing coating or a light-shielding coating.

9. The light guide plate according to claim 1, wherein the light blocking portion includes a metal or a resin.

10. The light guide plate according to claim 1, wherein the light blocking portion includes a wire or a strip-shaped member.

11. The light guide plate according to claim 1, wherein the thickness of the light-shielding portion in the thinnest direction is 0.2 mm or less.

12. The light guide plate according to claim 1, wherein the size of each of the light blocking portions differs depending on the position where the light blocking portions are disposed.

13. The light guide plate according to claim 1, wherein image light incident from the outside is totally reflected at least once inside.

14. The light guide plate according to claim 1, further comprising a collimator optical system that converts image light incident from the outside into a substantially parallel beam and outputs the parallel beam to the reflecting optical element.

15. The light guide plate according to claim 14, wherein the collimator optical system is disposed internally or externally.

16. The light guide plate according to claim 1, wherein the light guide plate comprises at least two optical members, the optical members including a plurality of flat surfaces arranged parallel to one another along a longitudinal direction, and the reflective optical elements are arranged on the plurality of flat surfaces.

17. The light guide plate of claim 1, wherein each of the reflective optical elements reflects some or all of the image light.

18. The light guide plate according to claim 1, wherein at least one of the first surface and the second surface is a flat surface.

19. The light guide plate according to claim 1, wherein at least one of the first surface and the second surface is a curved surface.

20. An image display device comprising: a light guide plate; and an image display element which emits image light to the light guide plate, wherein the light guide plate includes a first surface arranged on the observer side and a second surface opposite the first surface, and comprises a plurality of reflective optical elements which are parallel to each other, and has a light-shielding portion arranged near an end of each of the reflective optical elements in a planar direction, wherein a portion of the image light incident from the image display element is guided to the pupil of the observer via the reflective optical elements and the first surface, and a portion of the image light incident from the image display element is shielded by the light-shielding portion.

Images