Light guide plate, and display device

Abstract

To provide a light guide plate and the like capable of improving the usage efficiency of image light entering the light guide plate.SOLUTION: Each of light guide plates 30-30q includes: a first input part 41a that is composed of a volume hologram that diffracts the incident light (image light); a first plane 131 that supports a first incident light part 41a, and on which light (image light) is incident; a first base plate 31 having a first plane 131 and a second plane 132 opposite the same; and a first reflective structure 61 that is placed opposing the second plane 132 to reflect the light (image light) that has passed through the first incident light section 41a.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present disclosure relates to a light guide plate and a display device. [Background technology]

[0002] In recent years, devices that generate virtual images have been installed in vehicles. For example, the volume hologram in Patent Document 1 is disposed at the entrance portion of an exit pupil expansion element that includes a flat waveguide portion that guides light, an entrance portion that inputs light into the waveguide portion, and an exit portion that is disposed on the waveguide portion or is configured integrally with the waveguide portion and that expands the exit pupil by dividing it into multiple portions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent Publication No. 2021-173878 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the diffraction efficiency of the volume hologram in Patent Document 1 is 50% or less, although it depends on the wavelength of the light, the thickness of the light guide plate, and the grating direction, meaning that more than half of the light incident on the entrance leaks out, resulting in a problem of reduced light utilization efficiency.

[0005] Therefore, an object of the present disclosure is to provide a light guide plate that can improve the utilization efficiency of image light that is incident on the light guide plate and the display device. [Means for solving the problem]

[0006] A light guide plate according to one embodiment of the present disclosure includes a first incident portion configured of a volume hologram that diffracts incident light, a first substrate that supports the first incident portion and has a first surface through which the light is incident and a second surface opposite the first surface, and a first reflection structure that is arranged opposite the second surface and reflects the light that has passed through the first incident portion. [Effects of the Invention]

[0007] According to the light guide plate and the like of the present disclosure, it is possible to improve the utilization efficiency of image light incident on the light guide plate. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a schematic diagram showing an example of a vehicle in which a display device according to an embodiment is installed. [Figure 2] FIG. 2 is a schematic diagram showing an example of a light guide plate and a display medium according to the embodiment. [Figure 3] FIG. 3 is a perspective view illustrating an example of a light guide plate according to the embodiment. [Figure 4] FIG. 4 is a diagram illustrating an example of a light guide plate and image light propagating through the light guide plate. [Figure 5] FIG. 5 is a diagram showing an example of image light propagating in the first entrance portion, the first reflection structure, the first extension portion, and the second extension portion, which are configured by a multiple-exposed volume hologram. [Figure 6] FIG. 6 is a plan view showing an example of a light guide plate having a first incident portion. [Figure 7] FIG. 7 is a diagram showing an example of image light propagating in a first entrance portion, a first reflection structure, a first extension portion, and a second extension portion, each of which is made up of a one-side exposed volume hologram. [Figure 8] FIG. 8 is a plan view showing an example of another light guide plate having a first entrance portion, one first exit portion, and the like. [Figure 9] FIG. 9 is a plan view showing an example of yet another light guide plate having a first entrance portion, one first exit portion, and the like. [Figure 10] FIG. 10 is a plan view showing an example of a light guide plate having a first incident portion and a second incident portion, etc., and in which a first reflection structure is arranged so as to straddle the first incident portion and the second incident portion. [Figure 11] FIG. 11 is a perspective view showing an example of image light propagating through a light guide plate having a first incident portion and a second incident portion, etc., and in which a first reflection structure is arranged so as to straddle the first incident portion and the second incident portion. [Figure 12] FIG. 12 is a plan view showing an example of another light guide plate having a first incident portion and a second incident portion, etc., and in which a first reflection structure is arranged so as to straddle the first incident portion and the second incident portion. [Figure 13] FIG. 13 is a plan view showing an example of a light guide plate having a first incident portion, a second incident portion, and one first exit portion, and the first reflection structure is arranged so as to straddle the first incident portion and the second incident portion. [Figure 14] FIG. 14 is a plan view showing an example of another light guide plate having a first incident portion, a second incident portion, and one first exit portion, etc., and in which a first reflection structure is arranged so as to straddle the first incident portion and the second incident portion. [Figure 15] FIG. 15 is a diagram showing an example of image light propagating in a light guide plate having a first incident portion, a first reflecting structure, a second reflecting structure, a third reflecting structure, a half wavelength plate, a polarizing beam splitter, and the like. [Figure 16] FIG. 16 is a diagram showing an example of image light propagating in a light guide plate having a first incident portion, a first reflecting structure, a second reflecting structure, a third reflecting structure, a fourth reflecting structure, a half-wave plate, and the like. [Figure 17] FIG. 17 is a diagram showing an example of image light propagating in a light guide plate having a first incident portion, a first reflection structure, a quarter-wave plate, a specular polarized reflection film, and the like. [Figure 18] FIG. 18 is a diagram showing an example of image light propagating in a light guide plate having a first substrate, a second substrate, a third substrate, and the like. [Figure 19] FIG. 19 is a diagram showing an example of image light propagating in a light guide plate having a first substrate, a second substrate, a third substrate, a first reflecting structure, a second reflecting structure, a third reflecting structure, and the like. [Figure 20] FIG. 20 is a plan view showing an example of a light guide plate having a first entrance portion, one first exit portion having a pentagonal shape, and the like. [Figure 21] FIG. 21 is a plan view showing an example of another light guide plate having a first entrance portion, one first exit portion having a pentagonal shape, and the like. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, the embodiments will be specifically described with reference to the drawings.

[0010] The embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection configurations, steps, and step order shown in the following embodiments are merely examples and are not intended to limit the present disclosure. Furthermore, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0011] In addition, each drawing is a schematic diagram and is not necessarily an exact illustration. In addition, the same components are denoted by the same reference numerals in each drawing.

[0012] Furthermore, in the following embodiments, expressions such as rectangular, approximately parallel, and X-axis direction are used. For example, rectangular, approximately parallel, and X-axis direction do not only mean completely rectangular, parallel, and X-axis direction, but also mean substantially rectangular, parallel, and X-axis direction, that is, with an error of about a few percent. Furthermore, rectangular, parallel, and X-axis direction mean rectangular, approximately parallel, and X-axis direction within the scope in which the effects of the present disclosure can be achieved. The same applies to other expressions using "shape," "approximately," and "direction."

[0013] (Embodiment) <Configuration> First, the configuration of a display device 1 including a light guide plate 30 will be described with reference to FIGS.

[0014] FIG. 1 is a schematic diagram showing an example of a vehicle 2 in which a display device 1 according to an embodiment is installed. FIG. 2 is a schematic diagram showing an example of a light guide plate 30 and a display medium according to an embodiment. FIG. 3 is a perspective view showing an example of a light guide plate 30 according to an embodiment. FIG. 4 is a diagram showing an example of a light guide plate 30 and image light propagating through the light guide plate 30. FIG. 5 is a diagram showing an example of image light propagating in a first entrance portion 41a, a first reflection structure 61, a first extension portion 42a, and a second extension portion 42b formed of a multiple-exposed volume hologram.

[0015] As shown in FIGS. 1 and 2, a display device 1 is disposed on a dashboard (also referred to as an instrument panel) of a vehicle 2 such as an automobile. A windshield 3 (also referred to as a windshield) is disposed above the dashboard of the vehicle 2. A light guide plate 30 of the display device 1 is disposed between the dashboard and the windshield 3. The light guide plate 30 is configured by incorporating a diffractive optical element in a light guide body having an incident surface 31a and an exit surface 31b. The specific configuration of the light guide plate 30 will be described later. The windshield 3 is an example of a display medium. The display medium may also be a combiner provided on the light guide plate 30.

[0016] The display device 1 can make the image light incident on a human eye by emitting the image light to a light-transmitting member and reflecting it. For example, when the display device 1 is used in a vehicle 2, the display device 1 can make the image light incident on a human eye by reflecting the image light emitted to a windshield 3 serving as a light-transmitting member. In this case, the display device 1 can emit the image light and project an image represented by the image light onto the light-transmitting member, thereby displaying a virtual image corresponding to the image on the light-transmitting member. The image light is light representing an image, and is light that displays a virtual image in front of the windshield 3. The image is a still image or a moving image, and is an image showing numbers, letters, figures, etc.

[0017] As shown in FIGS. 3 and 4, the display device 1 includes an image light emitting section 50 and a light guide plate 30.

[0018] The image light emitting unit 50 is an image generating device that emits image light to the light guide plate 30. When the image light emitting unit 50 emits image light that represents a rectangular image, the image light is projected onto the windshield 3 via the light guide plate 30. This allows the user to recognize a virtual image. The image light emitting unit 50 is an example of a light source.

[0019] The image light emitting section 50 has a plurality of emitters, a plurality of dichroic mirrors, a condenser lens, a mirror, and an exit surface 31b.

[0020] Each of the multiple emitters emits a light beam that is different from the others and is light of a predetermined wavelength band. Each of the multiple dichroic mirrors is positioned on the light beam emitted by the emitter, and can reflect light beams of a predetermined wavelength band and transmit light beams of other wavelength bands. The condenser lens is a lens that condenses the light beams emitted via the dichroic mirrors onto the multiple mirrors. The exit surface 31b is a screen such as a microlens array or a liquid crystal display element such as an LCOS (Liquid Crystal On Silicon) liquid crystal display, and when light beams of a plurality of wavelength bands are irradiated from the mirror side, the transmitted light can be emitted toward the light guide plate 30 as image light.

[0021] The light guide plate 30 can display an image represented by the image light to the user. The light guide plate 30 is optically transparent and can extend and emit an image represented by the image light emitted by the image light emitting unit 50 in the X-axis direction and the Y-axis direction. The light guide plate 30 is disposed so as to face the image light emitting unit 50 and the windshield 3.

[0022] As shown in FIGS. 3 and 4, the light guide plate 30 has an incident surface 31a and an exit surface 31b.

[0023] The incident surface 31a is disposed to face the exit surface of the image light exit unit 50. The image light emitted from the exit surface of the image light exit unit 50 is incident on the incident surface 31a. The incident surface 31a is a part of the back surface of the rectangular light guide plate 30. The back surface is the surface of the light guide plate 30 opposite to the exit surface 31b.

[0024] The exit surface 31b emits the image light that has entered from the entrance surface 31a and propagated inside the light guide plate 30 toward the windshield 3 in FIG. 2. The exit surface 31b faces the windshield 3 and is separated a predetermined distance from the windshield 3. The exit surface 31b is a part of the surface of the light guide plate 30.

[0025] The light guide plate 30 includes a first substrate 31 having optical transparency, a plurality of hologram elements 40, and a first reflecting structure 61.

[0026] The first substrate 31 has a first surface 131 onto which light is incident, and a second surface 132 opposite the first surface 131. An incident surface 31a facing the image light output section 50 is formed on the first surface 131. The incident surface 31a faces the image light output section 50 and is a part of the first surface 131 onto which the image light emitted by the image light output section 50 is incident. The first substrate 31 also has an exit surface 31b formed on the opposite side to the incident surface 31a, facing the windshield 3 of FIG. 2. The exit surface 31b is a part of the second surface 132 from which third image light, which will be described later, is output.

[0027] The first substrate 31 is made of a light-transmitting material such as glass or a resin material.

[0028] The first substrate 31 contains a plurality of hologram elements 40 that diffract and emit image light representing an image generated by the image light emitting unit 50. As shown in FIG. 4, the plurality of hologram elements 40 are light-transmitting optical elements that diffract and emit light propagating through the first substrate 31. The plurality of hologram elements 40 are contained and supported in the first substrate 31 in an orientation that is approximately parallel to the entrance surface 31a and the exit surface 31b of the first substrate 31. The plurality of hologram elements 40 are made of a light-transmitting material.

[0029] The plurality of hologram elements 40 each include a first entrance portion 41a, a first extension portion 42a and a second extension portion 42b, and a first exit portion 43a and a second exit portion 43b. The first entrance portion 41a, the first extension portion 42a, the second extension portion 42b, the first exit portion 43a, and the second exit portion 43b are configured with a volume hologram that diffracts incident image light. In particular, the first entrance portion 41a is a multiple-exposed volume hologram. Note that the first entrance portion 41a, the first extension portion 42a and the second extension portion 42b, and the first exit portion 43a and the second exit portion 43b may be collectively referred to simply as the hologram element 40.

[0030] The first incident portion 41a is disposed so as to overlap the incident surface 31a of the light guide plate 30 when viewed along the Z-axis direction and also overlap the exit surface of the image light exit portion 50 disposed on the negative Z-axis side of the light guide plate 30. The first incident portion 41a is disposed between the first extension portion 42a and the second extension portion 42b and is disposed closer to the light incident side of the light guide plate 30 than the first extension portion 42a and the second extension portion 42b. The first extension portion 42a and the second extension portion 42b are supported by the first substrate 31 so as to be disposed adjacent to the first incident portion 41a. Specifically, the first extension portion 42a, the first incident portion 41a, and the second extension portion 42b are disposed side by side along the X-axis direction. More specifically, the first extension portion 42a is disposed on the positive X-axis side of the first incident portion 41a and on the light exit side of the first incident portion 41a. The second extension portion 42b is disposed on the negative X-axis direction side of the first incident portion 41a, on the light exit side of the first incident portion 41a.

[0031] The first extension portion 42a and the second extension portion 42b are located on the negative Y-axis direction side of the first emission portion 43a and the second emission portion 43b, and are arranged closer to the light incident side of the light guide plate 30 than the first emission portion 43a and the second emission portion 43b.

[0032] The first incident portion 41a can diffract the image light emitted by the image light emitting portion 50 and emit the first image light toward the first extension portion 42a and the second extension portion 42b.

[0033] The first extension portion 42a can diffract the first image light emitted from the first incident portion 41a and emit the second image light toward the first exit portion 43a. The second extension portion 42b can diffract the first image light emitted from the first incident portion 41a and emit the second image light toward the second exit portion 43b.

[0034] The first exit portion 43a is supported by the first substrate 31 so as to be disposed adjacent to the first extension portion 42a. The second exit portion 43b is supported by the first substrate 31 so as to be disposed adjacent to the second extension portion 42b. Specifically, the first extension portion 42a and the first exit portion 43a are disposed side by side along the Y-axis direction, and the second exit portion 43b and the second extension portion 42b are also disposed side by side along the Y-axis direction. Specifically, the first exit portion 43a is disposed on the positive Y-axis side of the first extension portion 42a and on the light exit side of the first extension portion 42a. The second exit portion 43b is disposed on the positive Y-axis side of the second extension portion 42b and on the light exit side of the second extension portion 42b. Furthermore, the first exit portion 43a and the second exit portion 43b are disposed so as to overlap with and face the exit surface 31b of the light guide plate 30.

[0035] The first emission portion 43a diffracts the second image light emitted by the first extension portion 42a and emits the third image light to the outside, and the second emission portion 43b diffracts the second image light emitted by the second extension portion 42b and emits the third image light to the outside.

[0036] The first incident portion 41a has a rectangular shape. The first extension portion 42a and the second extension portion 42b have a rectangular shape that is elongated along the X-axis direction. The width of the first extension portion 42a and the second extension portion 42b in the Y-axis direction is equal to the width of the first incident portion 41a in the Y-axis direction. The width of the first exit portion 43a and the second exit portion 43b in the X-axis direction is equal to the width of the first extension portion 42a and the second extension portion 42b in the X-axis direction. Furthermore, the width of the first extension portion 42a and the first exit portion 43a in the X-axis direction may be equal to the width of the second extension portion 42b and the second exit portion 43b in the X-axis direction.

[0037] 5, first reflecting structure 61 is disposed to face second surface 132. Specifically, when first reflecting structure 61 and first incident portion 41a are viewed along the Z-axis direction, first reflecting structure 61 overlaps with and covers first incident portion 41a.

[0038] The first reflecting structure 61 can reflect light that has passed through the first incident portion 41a. In this embodiment, the first reflecting structure 61 is a reflecting plate having a retroreflective structure. Leakage light, which is a portion of the image light that has been emitted from the emission surface of the image light emitting portion 50 and that has passed through the first incident portion 41a as it is, is incident on the first reflecting structure 61.

[0039] Normally, such leaked light would pass through the first incident portion 41a and not enter the first extension portion 42a or the second extension portion 42b. However, the first reflecting structure 61 of the present disclosure is disposed opposite the first incident portion 41a and has a retroreflective structure, and therefore can reflect a portion of the image light that has passed through the first incident portion 41a and return it to the first incident portion 41a. Because the first reflecting structure 61 has a retroreflective structure, it can retroreflect the image light in a direction along the optical path of the image light from the first incident portion 41a toward the first reflecting structure 61. In other words, a portion of the image light that passed through the first incident portion 41a returns to the first incident portion 41a.

[0040] Here, the state of the image light when the image light is retroreflected by the first reflecting structure 61 will be specifically described.

[0041] Assume that the amount of image light emitted by the image light output unit 50 is 100% incident on the first incident unit 41a. If the diffraction efficiency of the first incident unit 41a is 30%, 30% of the total amount of image light is propagated toward the first extension unit 42a and the second extension unit 42b. Specifically, 15% of the total amount of image light is deflected by diffraction as the first image light and propagated toward the first extension unit 42a, and 15% of the total amount of image light is deflected by diffraction as the first image light and propagated toward the second extension unit 42b. 70% of the total amount of image light incident on the first incident unit 41a passes through the first incident unit 41a and enters the first reflecting structure 61, where it is retroreflected and enters the first incident unit 41a. Of the 70% total amount of image light (the amount of reflected image light), another 30%, or 21%, is propagated toward the first extension portion 42a and the second extension portion 42b. Specifically, 10.5% of the total amount of image light becomes first image light deflected by diffraction and propagates toward the first extension portion 42a, and 10.5% of the total amount of image light becomes first image light deflected by diffraction and propagates toward the second extension portion 42b. The remaining image light, that is, 49% of the total amount of image light, is emitted from the light guide plate 30.

[0042] In this way, a portion of the image light that has passed through the first incident portion 41a can be returned to the first incident portion 41a, and therefore, this light guide plate 30 and an illumination device using the light guide plate 30 are expected to improve the utilization efficiency of the image light.

[0043] Next, the state of the image light emitted from the image light emitting section 50 until the image light is emitted from the light guide plate 30 will be described.

[0044] 3 and 4, the image light emitted from the emission surface of the image light emission unit 50 is incident on the first incident unit 41a. When the image light incident on the light guide plate 30 propagates through the light guide plate 30, the first incident unit 41a deflects the image light by diffraction in accordance with the diffraction efficiency of the first incident unit 41a. Because the first incident unit 41a is a multiple-exposed volume hologram, it emits the image light as first image light (deflected light) that propagates along the positive direction of the X axis toward the first extension unit 42a, and also emits the image light as first image light (deflected light) that propagates along the negative direction of the X axis toward the second extension unit 42b. In other words, the image light incident on the first substrate 31 from the incident surface 31a enters the first incident section 41a, and then its direction of travel is changed from the first incident section 41a to the first extension section 42a and from the first incident section 41a to the second extension section 42b, and is emitted as the first image light by the first incident section 41a.

[0045] Furthermore, a portion of the image light incident on the first incident portion 41a passes through the first incident portion 41a as is and enters the first reflecting structure 61. The first reflecting structure 61 retroreflects the image light incident from the first incident portion 41a in a direction along the optical path of the image light traveling from the first incident portion 41a to the first reflecting structure 61. The image light retroreflected by the first reflecting structure 61 enters the first incident portion 41a. As the returned image light propagates through the light guide plate 30, the first incident portion 41a deflects the returned image light by diffraction in accordance with the diffraction efficiency of the first incident portion 41a. Because the first incident portion 41a is a multiple-exposed volume hologram, the first incident portion 41a emits the first image light propagating along the positive direction of the X-axis toward the first extension portion 42a and the first image light propagating along the negative direction of the X-axis toward the second extension portion 42b. The image light retro-reflected by the first reflecting structure 61 enters the first incident section 41a, and then its direction of travel is changed from the first incident section 41a to the first extension section 42a and from the first incident section 41a to the second extension section 42b, and is emitted as the first image light by the first incident section 41a.

[0046] Each time the first image light transmitted through the first incident portion 41a is incident (transmitted), the first extension portion 42a and the second extension portion 42b further deflect the incident first image light by diffraction and output the second image light toward the first exit portion 43a and the second exit portion 43b. Specifically, when the first image light incident on the first extension portion 42a propagates through the light guide plate 30 along the positive direction of the X axis, the first extension portion 42a further deflects the first image light by diffraction in accordance with the diffraction efficiency of the first extension portion 42a. When the first image light incident on the second extension portion 42b propagates through the light guide plate 30 along the negative direction of the X axis, the second extension portion 42b further deflects the second image light by diffraction in accordance with the diffraction efficiency of the second extension portion 42b. At this time, the first extension portion 42a and the second extension portion 42b elongate the image of the first image light along the X axis direction. As a result, the first extension portion 42a and the second extension portion 42b emit the second image light, which has been elongated along the X-axis direction, along the positive direction of the Y-axis. The second image light, which has been deflected by diffraction in the first extension portion 42a and the second extension portion 42b, is incident on the first exit portion 43a and the second exit portion 43b. Note that the first extension portion 42a and the second extension portion 42b may be configured so that the diffraction efficiency increases from areas closer to the first entrance portion 41a to areas farther away, in order to suppress brightness unevenness.

[0047] Each time the second image light that has passed through the first extension portion 42a and the second extension portion 42b is incident (transmitted), the first exit portion 43a and the second exit portion 43b further deflect the incident second image light by diffraction and emit third image light at a predetermined exit angle. Specifically, when the second image light deflected by diffraction by the first extension portion 42a and the second extension portion 42b propagates through the light guide plate 30 along the positive direction of the Y axis, the first exit portion 43a and the second exit portion 43b further deflect the second image light by diffraction in accordance with the diffraction efficiency of the first exit portion 43a and the second exit portion 43b. At this time, the first exit portion 43a and the second exit portion 43b further elongate the image of the second image light that has been elongated along the X axis direction substantially along the Y axis direction. As a result, the first exit portion 43a and the second exit portion 43b emit the third image light, which has been elongated along the X-axis direction and approximately the Y-axis direction, to the outside of the light guide plate 30 at a predetermined emission angle. In other words, the first exit portion 43a and the second exit portion 43b further elongate the second image light, which has been emitted by the first extension portion 42a and the second extension portion 42b, in the approximately Y-axis direction, thereby emitting the third image light, which has been expanded in the X-axis direction and the Y-axis direction, at a predetermined emission angle. In this embodiment, the first exit portion 43a and the second exit portion 43b emit the third image light in the positive direction of the Z-axis toward the windshield 3. Note that the first exit portion 43a and the second exit portion 43b may be configured so that their diffraction efficiency increases from areas closer to the first extension portion 42a and the second extension portion 42b to areas farther from them, in order to suppress brightness unevenness.

[0048] Next, as shown in FIGS. 6 and 7, the light guide plate 30a of this embodiment may have the following configuration.

[0049] Fig. 6 is a plan view showing an example of a light guide plate 30a having a first incident portion 41a. Fig. 7 is a diagram showing an example of image light propagating through the first incident portion 41a, the first reflecting structure 61, the first extension portion 42a, and the second extension portion 42b, which are formed of a one-side exposed volume hologram.

[0050] For example, the first entrance portion 41a may be a one-side exposed volume hologram as shown in Fig. 6. Unless otherwise specified, the light guide plate 30a in Fig. 6 has the same configuration and function as the light guide plate 30 in Fig. 4.

[0051] In this case, because the first incident portion 41a is a one-side exposed volume hologram, the light exits as first image light propagating toward the first extension portion 42a. That is, the image light incident on the first substrate 31 from the first surface 131 is deflected by diffraction at the first incident portion 41a after entering the first incident portion 41a, and its traveling direction is changed from the first incident portion 41a to the first extension portion 42a, and the light exits from the first incident portion 41a as the first image light.

[0052] Furthermore, a portion of the image light incident on the first incident portion 41a passes through the first incident portion 41a as is and enters the first reflecting structure 61. The first reflecting structure 61 retroreflects the image light incident from the first incident portion 41a in a direction along the optical path of the image light traveling from the first incident portion 41a to the first reflecting structure 61. The image light retroreflected by the first reflecting structure 61 enters the first incident portion 41a. As the retroreflected image light propagates through the light guide plate 30a, the first incident portion 41a deflects the retroreflected image light by diffraction in accordance with the diffraction efficiency of the first incident portion 41a. Because the first incident portion 41a is a one-side exposed volume hologram, the retroreflected image light exits as the first image light that propagates toward the second extension portion 42b. In other words, the image light retroreflected by the first reflecting structure 61 enters the first incident section 41a, then its direction of travel is changed from the first incident section 41a to the second extension section 42b, and it is emitted from the first incident section 41a as the first image light.

[0053] Here, a case where image light is retroreflected by first reflecting structure 61 will be specifically described.

[0054] As shown in FIG. 7, it is assumed that the amount of image light emitted by the image light output unit 50 is 100% incident on the first incident unit 41a. When the diffraction efficiency of the first incident unit 41a is 30%, 30% of the total amount of image light is propagated toward the first extension unit 42a. Specifically, 30% of the total amount of image light is deflected by diffraction to become first image light and propagate toward the first extension unit 42a. 70% of the total amount of image light incident on the first incident unit 41a is transmitted through the first incident unit 41a and enters the first reflecting structure 61, is retroreflected by the first reflecting structure 61, and enters the first incident unit 41a. Another 30% of the 70% total amount of image light (the amount of reflected image light), or 21%, is propagated toward the second extension unit 42b. Specifically, 21% of the total amount of image light is deflected by diffraction to become first image light, which propagates toward the second extension portion 42b.

[0055] In this way, when the first entrance portion 41a of the one-sided exposed volume hologram is used, the amount of image light incident on the first extension portion 42a differs from the amount of light incident on the second extension portion 42b. Therefore, the width L1 of the first extension portion 42a and the first exit portion 43a in the X-axis direction is set larger than the width L2 of the second extension portion 42b and the second exit portion 43b in the X-axis direction. Specifically, in a plan view of the light guide plate 30a, the ratio of the first area of ​​the first extension portion 42a to the second area of ​​the second extension portion 42b is equal to the ratio of the amount of light whose traveling direction is changed at the first entrance portion 41a toward the first extension portion 42a to the amount of light whose traveling direction is changed at the first entrance portion 41a toward the second extension portion 42b. As a result, the ratio between the area of ​​the first exit portion 43a and the area of ​​the second exit portion 43b is equal to the ratio between the amount of second image light incident on the first exit portion 43a and the amount of second image light incident on the second exit portion 43b. Therefore, image light of equal brightness is emitted from the first exit portion 43a and the second exit portion 43b. Note that the plan view refers to the case where the light guide plate 30a is viewed along the Z-axis direction so as to face the light guide plate 30a.

[0056] Next, as shown in FIG. 8, the light guide plate 30b of this embodiment may have the following configuration.

[0057] FIG. 8 is a plan view showing an example of another light guide plate 30b having a first incident portion 41a, one first exit portion 43a, and the like.

[0058] As shown in Fig. 8, for example, in light guide plate 30b of the present embodiment, first extension portion 42a and second extension portion 42b may be asymmetric in shape, and only one first emission portion 43a may be provided. Unless otherwise specified, light guide plate 30b in Fig. 8 has the same configuration and function as light guide plate 30 in Fig. 4.

[0059] In this case, the first emission section 43a is supported by the first substrate 31 so as to be disposed adjacent to the first extension section 42a and the second extension section 42b. Specifically, the first extension section 42a and the second extension section 42b and the first emission section 43a are disposed side by side along the Y-axis direction. Specifically, the first emission section 43a is disposed on the positive Y-axis side of the first extension section 42a and the second extension section 42b, and on the light emission side of the first extension section 42a and the second extension section 42b.

[0060] The first exit portion 43a diffracts the second image light emitted by the first extension portion 42a and the second extension portion 42b, and emits the third image light to the outside. The first exit portion 43a is disposed so as to overlap with and face the exit surface 31b of the light guide plate 30b.

[0061] The first extension portion 42a and the second extension portion 42b have an asymmetric trapezoidal shape. In a plan view relative to the light guide plate 30b, the side of the first extension portion 42a facing the positive Y-axis is inclined upward toward the negative X-axis. In a plan view relative to the light guide plate 30b, the side of the second extension portion 42b facing the positive Y-axis is inclined upward toward the positive X-axis.

[0062] The first extension portion 42a and the second extension portion 42b emit the second image light propagating toward the first exit portion 43a. Specifically, the second image light emitted from one side of the first extension portion 42a on the positive side of the Y axis and the second image light emitted from one side of the second extension portion 42b on the positive side of the Y axis are incident on one side of the first exit portion 43a on the negative side of the Y axis and are emitted by the first exit portion 43a as the third image light. In other words, the second image light incident on the first extension portion 42a and the second extension portion 42b has its traveling direction changed from the first extension portion 42a and the second extension portion 42b to the direction of the first exit portion 43a and is emitted by the first exit portion 43a as the third image light.

[0063] Next, as shown in FIG. 9, a light guide plate 30c of this embodiment may have the following configuration.

[0064] FIG. 9 is a plan view showing an example of yet another light guide plate 30c having a first incident portion 41a, one first exit portion 43a, and the like.

[0065] 9, for example, in light guide plate 30c of the present embodiment, first extension portion 42a and second extension portion 42b may have asymmetric shapes, and first emission portion 43a and second emission portion 43b may be provided. Unless otherwise specified, light guide plate 30c in FIG. 9 has the same configuration and function as light guide plate 30b in FIG. 8.

[0066] In this case, the first emission section 43a is supported by the first substrate 31 so as to be disposed adjacent to the first extension section 42a. The second emission section 43b is supported by the first substrate 31 so as to be disposed adjacent to the second extension section 42b. Specifically, the first extension section 42a and the first emission section 43a are disposed side by side along the positive direction of the Y axis. Furthermore, the second extension section 42b and the second emission section 43b are disposed side by side along the negative direction of the Y axis.

[0067] The first extension portion 42a and the second extension portion 42b have an asymmetric trapezoidal shape. In a plan view relative to the light guide plate 30c, the side of the first extension portion 42a facing the negative Y-axis is inclined upward toward the positive X-axis. In a plan view relative to the light guide plate 30c, the side of the second extension portion 42b facing the positive Y-axis is inclined upward toward the positive X-axis.

[0068] The first extension portion 42a emits the second image light propagating toward the first exit portion 43a. The second extension portion 42b emits the second image light propagating toward the second exit portion 43b. Specifically, the second image light emitted from one side of the first extension portion 42a on the negative Y-axis direction is incident on one side of the first exit portion 43a on the positive Y-axis direction and is emitted by the first exit portion 43a as the third image light. Furthermore, the second image light emitted from one side of the second extension portion 42b on the positive Y-axis direction is incident on one side of the second exit portion 43b on the negative Y-axis direction and is emitted by the second exit portion 43b as the third image light. That is, the second image light incident on the first extension portion 42a has its traveling direction changed from the first extension portion 42a to the first exit portion 43a, and is emitted as the third image light by the first exit portion 43a. Also, the second image light incident on the second extension portion 42b has its traveling direction changed from the second extension portion 42b to the second exit portion 43b, and is emitted as the third image light by the first exit portion 43a.

[0069] Next, as shown in FIGS. 10 and 11, a light guide plate 30d of the present embodiment may have the following configuration.

[0070] Fig. 10 is a plan view showing an example of a light guide plate 30d having a first incident portion 41a and a second incident portion 41b, etc., and a first reflecting structure 61 arranged to straddle the first incident portion 41a and the second incident portion 41b. Fig. 11 is a perspective view showing an example of image light propagating through a light guide plate 30d having a first incident portion 41a and a second incident portion 41b, etc., and a first reflecting structure 61 arranged to straddle the first incident portion 41a and the second incident portion 41b.

[0071] As shown in FIGS. 10 and 11 , for example, light guide plate 30d of the present embodiment may include first incident portion 41a and second incident portion 41b disposed adjacent to first incident portion 41a, and first reflecting structure 61 may be disposed from first incident portion 41a to second incident portion 41b in a planar view. That is, in a planar view of light guide plate 30d, the center of first reflecting structure 61 is disposed offset from the center of first incident portion 41a. First incident portion 41a and second incident portion 41b are disposed side by side in the Y-axis direction. First extension portion 42a is disposed on the positive side of first incident portion 41a along the X-axis. Second extension portion 42b is disposed on the negative side of second incident portion 41b along the X-axis. Unless otherwise noted, light guide plate 30d in FIG. 10 has the same configuration and function as light guide plate 30 in FIG. 4.

[0072] In this case, the first incident portion 41a is a one-sided exposed volume hologram. Image light emitted from the exit surface of the image light emitting portion 50 enters the first incident portion 41a. When the image light incident on the light guide plate 30d propagates through the light guide plate 30d, the first incident portion 41a deflects the image light by diffraction in accordance with the diffraction efficiency of the first incident portion 41a. The first incident portion 41a emits the image light as first image light propagating along the positive direction of the X-axis toward the first extension portion 42a. In other words, the image light from the image light emitting portion 50 that enters the first incident portion 41a and is diffracted by the first incident portion 41a has its traveling direction changed from the first incident portion 41a to the first extension portion 42a, and is then emitted from the first incident portion 41a as the first image light.

[0073] Furthermore, a portion of the image light incident on first incident portion 41 a travels toward first reflecting structure 61 .

[0074] The image light that passes through the first incident portion 41a is incident on the first reflecting structure 61. The image light that enters the first reflecting structure 61 is retro-reflected from the first reflecting structure 61 toward the second incident portion 41b and then enters the second incident portion 41b. The second incident portion 41b is a one-side exposed volume hologram. When the image light that enters the light guide plate 30d propagates through the light guide plate 30d, the second incident portion 41b deflects the image light by diffraction according to the diffraction efficiency of the second incident portion 41b. The second incident portion 41b emits the first image light that propagates along the negative X-axis direction toward the second extension portion 42b. In other words, the image light that is incident on the second incident portion 41b, is retroreflected by the first reflection structure 61, and is diffracted by the second incident portion 41b, has its direction of travel changed from the second incident portion 41b to the second extension portion 42b, and is emitted from the second incident portion 41b as the first image light.

[0075] Next, as shown in FIG. 12, a light guide plate 30e of this embodiment may have the following configuration.

[0076] FIG. 12 is a plan view showing an example of another light guide plate 30e having a first incident portion 41a and a second incident portion 41b, etc., and a first reflecting structure 61 arranged so as to straddle the first incident portion 41a and the second incident portion 41b.

[0077] 12, the area of ​​first extension portion 42a is different from the area of ​​second extension portion 42b, and the area of ​​first emission portion 43a is different from the area of ​​second emission portion 43b. Unless otherwise specified, light guide plate 30e in FIG. 12 has the same configuration and function as light guide plate 30d in FIG.

[0078] In this case, the first incident portion 41a and the second incident portion 41b are one-side exposed volume holograms. Assume that the amount of image light emitted by the image light emitting portion 50 is 100% incident on the first incident portion 41a. If the diffraction efficiency of the first incident portion 41a is 30%, 30% of the total amount of image light is propagated toward the first extension portion 42a. Specifically, 30% of the total amount of image light is deflected by diffraction to become first image light and propagate toward the first extension portion 42a. 70% of the total amount of image light incident on the first incident portion 41a is transmitted through the first incident portion 41a and enters the first reflecting structure 61, where it is retroreflected and enters the second incident portion 41b. When the image light incident on the light guide plate 30e propagates through the light guide plate 30e, the second incident portion 41b deflects the image light by diffraction in accordance with the diffraction efficiency of the second incident portion 41b. When the diffraction efficiency of the second incident portion 41b is 30%, 21%, which is another 30% of the total amount of image light (70% of the amount of reflected image light), is propagated toward the second extension portion 42b. Specifically, 21% of the total amount of image light becomes the first image light deflected by diffraction and propagates toward the second extension portion 42b.

[0079] In this way, when the first entrance portion 41a and the second entrance portion 41b of a one-sidedly exposed volume hologram are used, the amount of image light incident on the first extension portion 42a differs from the amount of light incident on the second extension portion 42b. Therefore, the width L1 of the first extension portion 42a and the first exit portion 43a in the X-axis direction is set larger than the width L2 of the second extension portion 42b and the second exit portion 43b in the X-axis direction. Specifically, the ratio of the amount of image light incident on the first extension portion 42a to the amount of image light incident on the second extension portion 42b is equal to the ratio of the area of ​​the first extension portion 42a to the area of ​​the second extension portion 42b. The ratio of the amount of image light incident on the first exit portion 43a to the amount of image light incident on the second exit portion 43b is equal to the ratio of the area of ​​the first exit portion 43a to the area of ​​the second exit portion 43b. Therefore, image light of equal brightness is emitted from the first emission portion 43a and the second emission portion 43b.

[0080] Next, as shown in FIG. 13, a light guide plate 30f of this embodiment may have the following configuration.

[0081] FIG. 13 is a plan view showing an example of a light guide plate 30f having a first incident portion 41a, a second incident portion 41b, and one first exit portion 43a, etc., and a first reflecting structure 61 arranged so as to straddle the first incident portion 41a and the second incident portion 41b.

[0082] As shown in Fig. 13, for example, light guide plate 30f of the present embodiment may be provided with only one first emission portion 43a. Unless otherwise specified, light guide plate 30f in Fig. 13 has the same configuration and function as light guide plate 30e in Fig. 12.

[0083] In this case, the first extension portion 42a extends along the X-axis direction and is disposed on the positive side of the X-axis relative to the first incident portion 41a. The second extension portion 42b extends along the X-axis direction and is disposed on the positive side of the X-axis relative to the second incident portion 41b. The second extension portion 42b is disposed on the positive side of the X-axis relative to the first extension portion 42a, and is disposed so that the first extension portion 42a and the second extension portion 42b do not overlap when viewed along the Y-axis. The first exit portion 43a is supported by the first substrate 31 so as to be disposed adjacent to the first extension portion 42a and the second extension portion 42b. Specifically, the first exit portion 43a is disposed on the positive side of the Y-axis relative to the first extension portion 42a and the second extension portion 42b, and is disposed on the light exit side of the first extension portion 42a and the second extension portion 42b.

[0084] The sum of the width of the first extension portion 42a and the width of the second extension portion 42b in the X-axis direction is equal to the width of the first emission portion 43a in the X-axis direction.

[0085] The first extension portion 42a and the second extension portion 42b emit the second image light propagating toward the first exit portion 43a. Specifically, the second image light emitted by the first extension portion 42a is incident on the portion of the first exit portion 43a on the negative side of the X-axis, and the second image light emitted by the second extension portion 42b is incident on the portion of the first exit portion 43a on the positive side of the X-axis. The second image light incident on the first extension portion 42a and the second extension portion 42b has its traveling direction changed from the first extension portion 42a and the second extension portion 42b to the direction of the first exit portion 43a, and is emitted by the first exit portion 43a as third image light.

[0086] Next, as shown in FIG. 14, a light guide plate 30g of this embodiment may have the following configuration.

[0087] FIG. 14 is a plan view showing an example of another light guide plate 30g having a first incident portion 41a, a second incident portion 41b, and one first exit portion 43a, etc., and in which a first reflecting structure 61 is arranged so as to straddle the first incident portion 41a and the second incident portion 41b.

[0088] As shown in Fig. 14, for example, light guide plate 30g of the present embodiment may be provided with only one first emission portion 43a. Unless otherwise specified, light guide plate 30g in Fig. 14 has the same configuration and function as light guide plate 30f in Fig. 13.

[0089] In this case, the first extension section 42a extends along the X-axis direction, is disposed on the positive X-axis side of the first incident section 41a, and is disposed on the positive Y-axis side of the first exit section 43a. The second extension section 42b extends along the Y-axis direction, is disposed on the positive Y-axis side of the second incident section 41b, and is disposed on the negative X-axis side of the first exit section 43a. The first exit section 43a is supported by the first substrate 31 so as to be disposed adjacent to the first extension section 42a and the second extension section 42b. Specifically, the first exit section 43a is disposed on the positive Y-axis side of the first extension section 42a, the positive X-axis side of the second extension section 42b, and on the light exit sides of the first extension section 42a and the second extension section 42b.

[0090] The first extension portion 42a and the second extension portion 42b emit the second image light propagating toward the first emission portion 43a. Specifically, the second image light emitted by the first extension portion 42a is incident on one side of the first emission portion 43a on the negative Y-axis direction side, and the second image light emitted by the second extension portion 42b is incident on one side of the first emission portion 43a on the negative X-axis direction side. The traveling direction of the second image light is changed from the first emission portion 43a to the direction of the emission surface 31b, and the second image light is emitted by the first emission portion 43a as third image light.

[0091] Next, as shown in FIG. 15, a light guide plate 30h of this embodiment may have the following configuration.

[0092] Fig. 15 is a diagram showing an example of image light propagating in a light guide plate 30h having a first incident portion 41a, a first reflecting structure 161, a second reflecting structure 162, a third reflecting structure 163, a half-wave plate 72, and a polarizing beam splitter 70. Although Fig. 15 illustrates an example in which the first image light propagates to one side, the first incident portion 41a may be a multiple-exposed volume hologram, and the first image light may propagate toward both sides.

[0093] 15, for example, light guide plate 30h of the present embodiment further includes second reflecting structure 162 provided on the outer side of first substrate 31, third reflecting structure 163 provided on the outer side of first substrate 31, polarized beam beam splitter 70 provided on the outer side of first substrate 31, and half-wave plate 72 provided between second reflecting structure 162 and third reflecting structure 163. Unless otherwise specified, light guide plate 30h in FIG. 15 has the same configuration and function as light guide plates 30 and 30a in FIGS. 4 and 6, etc.

[0094] First reflecting structure 161 is disposed on the second surface 132 side of first substrate 31, while being spaced apart from first substrate 31. Lens 75 is disposed between first reflecting structure 161 and second surface 132. Therefore, first reflecting structure 161, lens 75, and first incident portion 41a are disposed side by side. First reflecting structure 161, second reflecting structure 162, and third reflecting structure 163 have the function of reflecting image light.

[0095] Second reflecting structure 162 faces first reflecting structure 161 and half-wave plate 72 , and is disposed in a position that allows it to further reflect the image light reflected by first reflecting structure 161 and guide it to half-wave plate 72 .

[0096] The half-wave plate 72 is disposed between the second reflecting structure 162 and the third reflecting structure 163, and is a polarizing plate that can polarize the image light.

[0097] The third reflecting structure 163 faces the polarizing beam splitter 70 via the half-wave plate 72 and the lens 76, and is disposed in a position that allows the half-wave plate 72 to further reflect the polarized image light and guide it to the polarizing beam splitter 70. The lens 76 is disposed between the third reflecting structure 163 and the polarizing beam splitter 70. The third reflecting structure 163, the lens 76, and the polarizing beam splitter 70 are disposed side by side.

[0098] The polarized beam splitter 70 can transmit the image light emitted from the image light emitting section 50 as is, and can reflect the image light polarized by the half wavelength plate 72 toward the incident surface 31a.

[0099] The image light emitted from image light emission section 50 is referred to as a P wave. In FIG. 15, P waves are indicated by solid arrows, and S waves are indicated by dashed arrows. In this case, the image light (P wave) passes through polarized beam splitter 70, enters incident surface 31a of light guide plate 30h, and enters first incident section 41a. The image light (P wave) that entered first incident section 41a has its traveling direction changed from first incident section 41a to the direction of first extension section 42a, and is emitted by first incident section 41a as first image light (P wave). A portion of the image light that entered first incident section 41a passes through first incident section 41a as it is, is collected by lens 75, and enters first reflecting structure 161. First reflecting structure 161 reflects image light (P waves) incident from first incident portion 41a via lens 75 toward second reflecting structure 162 along a horizontal direction parallel to second surface 132 of first substrate 31. Second reflecting structure 162 reflects image light (P waves) incident from first reflecting structure 161 toward half-wave plate 72 along a vertical direction perpendicular to first surface 131 of first substrate 31. Half-wave plate 72 polarizes the image light (P waves) reflected by second reflecting structure 162 into image light (S waves) and emits it toward third reflecting structure 163. Third reflecting structure 163 reflects the image light (S waves) polarized by half-wave plate 72 toward polarizing beam splitter 70 via lens 76 along a horizontal direction parallel to first surface 131 of first substrate 31. The polarized beam beam splitter 70 reflects the image light (S waves) collected by the lens 76 toward the first incident portion 41a along a vertical direction perpendicular to the first surface 131 of the first substrate 31. As described above, the image light (S waves) is incident on the incident surface 31a of the light guide plate 30h and then incident on the first incident portion 41a.

[0100] The image light (S waves) incident on first incident portion 41a changes its traveling direction from first incident portion 41a to the direction of first extension portion 42a and is output by first incident portion 41a as first image light (S waves). A portion of the image light incident on first incident portion 41a is transmitted through first incident portion 41a without modification, is collected by lens 75, and is then incident on first reflecting structure 161. First reflecting structure 161 reflects the image light (S waves) incident from first incident portion 41a via lens 75 toward second reflecting structure 162 along a horizontal direction parallel to second surface 132 of first substrate 31. Second reflecting structure 162 reflects the image light (S waves) incident from first reflecting structure 161 toward half-wave plate 72 along a vertical direction perpendicular to second surface 132 of first substrate 31. The half-wave plate 72 polarizes the image light (S waves) reflected by the second reflecting structure 162 into image light (P waves) and emits it toward the third reflecting structure 163. The third reflecting structure 163 reflects the image light (P waves) polarized by the half-wave plate 72 toward the polarizing beam splitter 70 via the lens 76 along the horizontal direction parallel to the first surface 131 of the first substrate 31. The image light (P waves) is not reflected by the polarizing beam splitter 70 and is absorbed.

[0101] Next, as shown in FIG. 16, a light guide plate 30j of this embodiment may have the following configuration.

[0102] 16 is a diagram showing an example of image light propagating in light guide plate 30j having first incident portion 41a, first reflecting structure 161, second reflecting structure 162, third reflecting structure 163, fourth reflecting structure 164, and half-wave plate 72. First reflecting structure 161, second reflecting structure 162, third reflecting structure 163, and fourth reflecting structure 164 have the function of reflecting image light.

[0103] 16, for example, light guide plate 30j of the present embodiment further includes a second reflecting structure 162 provided on the outer side of first substrate 31, a third reflecting structure 163 provided on the outer side of first substrate 31, a fourth reflecting structure 164 provided on the outer side of first substrate 31, a polarized beam beam splitter 70 provided on the outer side of first substrate 31, and a half-wave plate 72 provided between second reflecting structure 162 and third reflecting structure 163. Unless otherwise specified, light guide plate 30j in FIG. 16 has the same configuration and function as light guide plates 30 and 30a in FIGS. 4 and 6.

[0104] First reflecting structure 161 is arranged on the second surface 132 side of first substrate 31, while being spaced apart from first substrate 31. Lens 75 is arranged between first reflecting structure 161 and second surface 132. First reflecting structure 161, lens 75, and first incident portion 41a are arranged side by side.

[0105] Second reflecting structure 162 faces first reflecting structure 161 and half-wave plate 72 , and is disposed in a position that allows it to further reflect the image light reflected by first reflecting structure 161 and guide it to half-wave plate 72 .

[0106] The half-wave plate 72 is disposed between the second reflecting structure 162 and the third reflecting structure 163 and is a polarizing plate that can polarize the image light reflected by the second reflecting structure 162 .

[0107] The third reflecting structure 163 faces the polarizing beam splitter 70 via the half-wave plate 72 and the lens 76, and is disposed in a position that allows the half-wave plate 72 to further reflect the polarized image light and guide it to the polarizing beam splitter 70. The lens 76 is disposed between the third reflecting structure 163 and the polarizing beam splitter 70. The third reflecting structure 163, the lens 76, and the polarizing beam splitter 70 are disposed side by side.

[0108] The polarized beam beam splitter 70 can transmit the image light emitted from the image light emitting section 50 as it is, and can reflect the image light polarized by the half wavelength plate 72 and reflect it toward the incident surface 31a.

[0109] The fourth reflecting structure 164 is positioned opposite the polarized beam splitter 70 and is held in a position that reflects image light incident in a horizontal direction parallel to the first surface 131 of the first substrate 31 toward the third reflecting structure 163.

[0110] The image light emitted from the image light emitting section 50 is referred to as a P wave. In Fig. 16, the P wave is indicated by a solid arrow, and the S wave is indicated by a dashed arrow.

[0111] In this case, the image light (P wave) passes through the polarizing beam splitter 70, enters the incident surface 31a of the light guide plate 30j, and enters the first incident portion 41a. The image light (P wave) that entered the first incident portion 41a has its traveling direction changed from the first incident portion 41a to the direction of the first extension portion 42a, and is output by the first incident portion 41a as the first image light (P wave). A portion of the image light (P wave) that entered the first incident portion 41a passes directly through the first incident portion 41a, is collected by the lens 75, and enters the first reflecting structure 161. The first reflecting structure 161 reflects the image light (P wave) that entered the first incident portion 41a from the first incident portion 41a via the lens 75 toward the second reflecting structure 162 along the horizontal direction parallel to the second surface 132 of the first substrate 31. The second reflecting structure 162 reflects the image light (P waves) incident from the first reflecting structure 161 toward the half-wave plate 72 along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The half-wave plate 72 polarizes the image light (P waves) reflected by the second reflecting structure 162 into image light (S waves) and emits it toward the third reflecting structure 163. The third reflecting structure 163 reflects the image light (S waves) polarized by the half-wave plate 72 toward the polarizing beam splitter 70 via the lens 76 along a horizontal direction parallel to the second surface 132 of the first substrate 31. The polarizing beam splitter 70 reflects the image light (S waves) focused on the lens 76 toward the first incident portion 41a along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The image light (S waves) is incident on the first incident portion 41a.

[0112] The image light (S waves) incident on first incident portion 41a changes its traveling direction from first incident portion 41a to first extension portion 42a and is output by first incident portion 41a as first image light (S waves). A portion of the image light (S waves) incident on first incident portion 41a passes through first incident portion 41a as is, is collected by lens 75, and is incident on first reflecting structure 161. First reflecting structure 161 reflects the image light (S waves) incident from first incident portion 41a via lens 75 toward second reflecting structure 162 along a horizontal direction parallel to second surface 132 of first substrate 31. Second reflecting structure 162 reflects the image light (S waves) incident from first reflecting structure 161 toward half-wave plate 72 along a vertical direction perpendicular to second surface 132 of first substrate 31. The half-wave plate 72 polarizes the image light (S waves) reflected by the second reflecting structure 162 into image light (P waves), and emits the image light toward the third reflecting structure 163. The third reflecting structure 163 reflects the image light (P waves) polarized by the half-wave plate 72 toward the polarizing beam splitter 70 and the fourth reflecting structure 164 via the lens 76 along the horizontal direction parallel to the second surface 132 of the first substrate 31. Note that the polarizing beam splitter 70 of this embodiment is disposed on the optical path between the lens 76 and the fourth reflecting structure 164, but has the property of transmitting P waves.

[0113] Fourth reflecting structure 164 reflects the image light (P wave) that has passed through lens 76 and polarizing beam splitter 70 and is incident from third reflecting structure 163, toward third reflecting structure 163 via polarizing beam splitter 70 and lens 76, along the horizontal direction parallel to first surface 131 of first substrate 31. Third reflecting structure 163 reflects the image light (P wave) that has been incident from fourth reflecting structure 164, toward half-wave plate 72, along the vertical direction perpendicular to first surface 131 of first substrate 31. Half-wave plate 72 polarizes the image light (P wave) reflected by third reflecting structure 163 into image light (S wave), and emits the image light toward second reflecting structure 162. The second reflecting structure 162 reflects the image light (S waves) polarized by the half-wave plate 72 toward the first reflecting structure 161 along a horizontal direction parallel to the second surface 132 of the first substrate 31. The first reflecting structure 161 reflects the image light (S waves) incident from the second reflecting structure 162 toward the first incident portion 41a via the lens 75 along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The image light (S waves) incident on the first incident portion 41a has its traveling direction changed from the first incident portion 41a to the direction of the second extension portion 42b, and is output by the first incident portion 41a as first image light (S waves). A portion of the image light (S waves) incident on the first incident portion 41a passes through the first incident portion 41a as it is, is collected by the lens 75, and is incident on the polarizing beam splitter 70.

[0114] Polarizing beam beam splitter 70 reflects the image light (S waves) via lens 76 toward third reflecting structure 163 along the horizontal direction parallel to second surface 132 of first substrate 31. Third reflecting structure 163 reflects the image light (S waves) incident from fourth reflecting structure 164 toward half-wave plate 72 along the vertical direction perpendicular to first surface 131 of first substrate 31. Half-wave plate 72 polarizes the image light (S waves) reflected by third reflecting structure 163 into image light (P waves) and emits it toward second reflecting structure 162. Second reflecting structure 162 reflects the image light (P waves) polarized by half-wave plate 72 toward first reflecting structure 161 along the horizontal direction parallel to second surface 132 of first substrate 31. First reflecting structure 161 reflects the image light (P wave) incident from second reflecting structure 162 toward first incident portion 41a via lens 75, along a vertical direction perpendicular to second surface 132 of first substrate 31. The image light (P wave) incident on first incident portion 41a has its traveling direction changed from first incident portion 41a to the direction toward second extension portion 42b, and is emitted by first incident portion 41a as first image light (P wave). A portion of the image light (P wave) incident on first incident portion 41a passes through polarizing beam splitter 70 and is emitted to the outside.

[0115] In this way, by making the image light incident from both sides of the first incident portion 41a, the light can be made incident on the first extension portion 42a and the second extension portion 42b.

[0116] Next, as shown in Fig. 17, the light guide plate 30k of the present embodiment may have the following configuration: In Fig. 17, P waves are indicated by solid arrows, S waves are indicated by dashed arrows, and circularly polarized image light is indicated by a two-dot chain line.

[0117] FIG. 17 is a diagram showing an example of image light propagating in a light guide plate 30k having a first incident portion 41a, a first reflecting structure 61, a quarter-wave plate 74, a specular polarizing reflecting film 65, and the like.

[0118] 17, for example, light guide plate 30k of the present embodiment further includes a quarter-wave plate 74 provided on the outer side of first substrate 31, and a specular polarized reflective film 65 provided on the outer side of first substrate 31. Unless otherwise specified, light guide plate 30k in FIG. 17 has the same configuration and function as light guide plates 30 and 30a in FIGS. 4 and 6, etc.

[0119] First reflecting structure 61 is provided on the second surface 132 side of first substrate 31 in a state separated from first substrate 31 , and is held in a position approximately parallel to second surface 132 .

[0120] A quarter-wave plate 74 is disposed between first reflecting structure 61 and second surface 132. Quarter-wave plate 74 is a circular polarizing filter that can polarize the image light to make it circularly polarized image light. Quarter-wave plate 74 is configured, for example, with a linear polarizing plate and quarter-wave plate 74.

[0121] The specular polarized reflective film 65 is provided on the first surface 131 side of the first substrate 31 and is held in a position substantially parallel to the first surface 131. The specular polarized reflective film 65 can transmit image light of P waves and reflect image light of S waves.

[0122] The image light emitted from the image light emitting section 50 is referred to as a P wave. In Fig. 17, the P wave is indicated by a solid arrow, the S wave is indicated by a dashed arrow, and circularly polarized light is indicated by a two-dot chain arrow.

[0123] In this case, the image light (P wave) passes through the specular polarized reflective film 65, enters the incident surface 31a of the light guide plate 30k, and enters the first incident portion 41a. The image light (P wave) that entered the first incident portion 41a is redirected from the first incident portion 41a toward the first extension portion 42a and is emitted by the first incident portion 41a as first image light (P wave). A portion of the image light (P wave) that entered the first incident portion 41a passes directly through the first incident portion 41a and enters the quarter-wave plate 74. The quarter-wave plate 74 polarizes the image light (P wave) into circularly polarized image light and emits it toward the first reflecting structure 61. The first reflecting structure 61 retroreflects the circularly polarized image light toward the quarter-wave plate 74 along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The quarter-wave plate 74 further polarizes the circularly polarized image light retroreflected by the first reflecting structure 61, and outputs the polarized image light (S waves) toward the first incident portion 41a along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The image light (S waves) is incident on the first incident portion 41a.

[0124] The image light (S waves) incident on the first incident portion 41a has its traveling direction changed from the first incident portion 41a to the direction of the second extension portion 42b, and is output by the first incident portion 41a as first image light (S waves). A portion of the image light (S waves) incident on the first incident portion 41a passes through the first incident portion 41a as is and is incident on the specular polarized reflective film 65. The specular polarized reflective film 65 reflects the image light (S waves) toward the first incident portion 41a along a vertical direction perpendicular to the second surface 132 of the first substrate 31.

[0125] The image light (S waves) incident on the first incident portion 41a changes its traveling direction from the first incident portion 41a to the first extension portion 42a and is output by the first incident portion 41a as first image light (S waves). A portion of the image light (S waves) incident on the first incident portion 41a passes through the first incident portion 41a as is and enters the quarter-wave plate 74. The quarter-wave plate 74 polarizes the image light (S waves) into circularly polarized image light and outputs it toward the first reflecting structure 61. The first reflecting structure 61 retroreflects the circularly polarized image light toward the quarter-wave plate 74 along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The quarter-wave plate 74 further polarizes the circularly polarized image light reflected by the first reflecting structure 61, and outputs the polarized image light (P wave) toward the first incident portion 41a along a vertical direction perpendicular to the second surface 132 of the first substrate 31. The image light (P wave) is incident on the first incident portion 41a.

[0126] The image light (P wave) incident on the first incident portion 41a has its traveling direction changed from the first incident portion 41a to the direction of the second extension portion 42b, and is emitted as the first image light (P wave) by the first incident portion 41a. A portion of the image light (P wave) incident on the first incident portion 41a is transmitted directly through the first incident portion 41a and the specular polarized reflection film 65, and is emitted to the outside of the light guide plate 30k.

[0127] Next, as shown in FIG. 18, a light guide plate 30m of this embodiment may have the following configuration.

[0128] FIG. 18 is a diagram showing an example of image light propagating in a light guide plate 30m having a first substrate 31, a second substrate 32, a third substrate 33, and the like.

[0129] As shown in Fig. 18, for example, in the light guide plate 30m of this embodiment, multiple substrates may be arranged to overlap. That is, the light guide plate 30m may have multiple substrates arranged to overlap. In Fig. 18, red light is indicated by a solid line, green light by a dashed-dotted line, and blue light by a dashed-two-dotted line. For convenience, the red light, green light, and blue light contained in the image light are depicted separately in Fig. 18. Unless otherwise specified, the light guide plate 30m in Fig. 18 has the same configuration and function as the light guide plates 30 and 30a in Figs. 4 and 6, etc.

[0130] In this embodiment, the multiple substrates include the above-mentioned first substrate 31, a second substrate 32 arranged to overlap the first substrate 31 and supporting a second entrance portion 41b consisting of a volume hologram, and a third substrate 33 arranged to overlap the second substrate 32 and supporting a third entrance portion 41c consisting of a volume hologram.

[0131] In addition, the second substrate 32 may support a first extension section 42a and a second extension section 42b having the same configuration as the first substrate 31, and may support a first emission section 43a having the same configuration as the first substrate 31, or may support a first emission section 43a and a second emission section 43b having the same configuration as the first substrate 31.

[0132] In addition, the third substrate 33 may support a first extension section 42a and a second extension section 42b having the same configuration as the first substrate 31, and may support a first emission section 43a having the same configuration as the first substrate 31, or may support a first emission section 43a and a second emission section 43b having the same configuration as the first substrate 31.

[0133] The first incident portion 41a, the second incident portion 41b, and the third incident portion 41c each have wavelength selectivity, and can diffract light of different wavelengths.

[0134] For example, the first incident portion 41a has wavelength selectivity that allows it to deflect, by diffraction, red light contained in the image light emitted by the image light output portion 50, becoming first image light and propagating toward the first extension portion 42a of the first substrate 31. The first incident portion 41a has a function of transmitting image light having wavelength components other than red light. The image light having wavelength components other than red light contained in the image light transmits through the first incident portion 41a and enters the second incident portion 41b.

[0135] The image light that has passed through the first incident portion 41a is incident on the second incident portion 41b. The second incident portion 41b has wavelength selectivity that allows it to deflect the green light included in the image light by diffraction and become the first image light that propagates toward the first extension portion 42a of the second substrate 32. The second incident portion 41b has a function of transmitting image light that has wavelength components other than the green light.

[0136] The image light that has passed through the second incident portion 41b is incident on the third incident portion 41c. The third incident portion 41c has wavelength selectivity that allows it to deflect blue light contained in the image light by diffraction and become first image light that propagates toward the first extension portion 42a of the third substrate 33. The third incident portion 41c has a function of transmitting image light that has wavelength components other than blue light.

[0137] In this case, the image light emitted by the image light emitting unit 50 enters the first incident unit 41a. The red light included in the image light that enters the first incident unit 41a is deflected by diffraction by the first incident unit 41a. As a result, the traveling direction of this image light is changed from the first incident unit 41a toward the first extension unit 42a of the first substrate 31, and the image light is emitted by the first incident unit 41a as first image light (red light).

[0138] A portion of the image light incident on the first incident portion 41a passes through the first incident portion 41a as is and enters the second incident portion 41b. The green light included in the image light incident on the second incident portion 41b is deflected by diffraction by the second incident portion 41b. As a result, the traveling direction of this image light is changed from the second incident portion 41b toward the first extension portion 42a of the second substrate 32, and the image light is emitted as the first image light (green light) by the second incident portion 41b.

[0139] A portion of the image light incident on the second incident portion 41b passes through the second incident portion 41b as is and enters the third incident portion 41c. The blue light contained in the image light incident on the third incident portion 41c is deflected by diffraction by the third incident portion 41c. As a result, the traveling direction of this image light is changed from the third incident portion 41c toward the first extension portion 42a of the third substrate 33, and the image light is emitted as the first image light (blue light) by the third incident portion 41c.

[0140] A portion of the image light that is incident on third incident portion 41c passes through third incident portion 41c as is and is incident on first reflecting structure 61. The image light that is incident on first reflecting structure 61 is retro-reflected from first reflecting structure 61 in the direction of third incident portion 41c and is incident on third incident portion 41c.

[0141] The blue light included in the image light incident on the third incident portion 41c is deflected by diffraction by the third incident portion 41c, whereby the traveling direction of this image light is changed from the third incident portion 41c toward the second extension portion 42b of the third substrate 33, and the image light is emitted as the first image light (blue light) by the third incident portion 41c.

[0142] A portion of the image light incident on the third incident portion 41c passes through the third incident portion 41c as is and enters the second incident portion 41b. The green light included in the image light incident on the second incident portion 41b is deflected by diffraction by the second incident portion 41b. As a result, the traveling direction of this image light is changed from the second incident portion 41b toward the second extension portion 42b of the second substrate 32, and the image light is emitted as the first image light (green light) by the second incident portion 41b.

[0143] A portion of the image light incident on the second incident portion 41b passes through the second incident portion 41b as is and enters the first incident portion 41a. The red light included in the image light incident on the first incident portion 41a is deflected by diffraction by the first incident portion 41a. As a result, the traveling direction of this image light is changed from the first incident portion 41a toward the second extension portion 42b of the first substrate 31, and the image light is emitted by the first incident portion 41a as first image light (red light). Then, the remaining image light that passed through the first incident portion 41a is emitted to the outside from the light guide plate 30m.

[0144] In addition, the first extension section 42a and the second extension section 42b and the first exit section and the second exit section of the first substrate 32, the second substrate 32 and the third substrate 33 may also have wavelength selectivity similar to that of the first entrance section 41a, the second entrance section 41b and the third entrance section 41c.

[0145] Next, as shown in FIG. 19, a light guide plate 30n of this embodiment may have the following configuration.

[0146] FIG. 19 is a diagram showing an example of image light propagating in a light guide plate 30n having a first substrate 31, a second substrate 32, a third substrate 33, a first reflecting structure 61, a second reflecting structure 62, a third reflecting structure 63, etc.

[0147] As shown in Fig. 19, for example, in the light guide plate 30n of this embodiment, multiple substrates may be arranged to overlap. That is, the light guide plate 30n may have multiple substrates arranged to overlap. In Fig. 19, red light is indicated by a solid line, green light by a dashed-dotted line, and blue light by a dashed-two-dotted line. For convenience, the red light, green light, and blue light contained in the image light are depicted separately in Fig. 19. Unless otherwise specified, the light guide plate 30n in Fig. 19 has the same configuration and function as the light guide plate 30m in Fig. 18.

[0148] In this embodiment, the light guide plate 30n further includes a second reflecting structure 62 that selectively retroreflects image light of a predetermined wavelength, and a third reflecting structure 63 that selectively retroreflects image light of a predetermined wavelength.

[0149] A first reflecting structure 61 is disposed between the first substrate 31 and the second substrate 32. A second reflecting structure 62 is disposed between the second substrate 32 and the third substrate 33. A third reflecting structure 63 is disposed on the side of the third substrate 33 opposite to the second substrate 32 side.

[0150] The first incident portion 41a, the first reflecting structure 61, the second incident portion 41b, the second reflecting structure 62, the third incident portion 41c, and the third reflecting structure 63 are arranged side by side so as to overlap along the Z-axis direction.

[0151] The first reflecting structure 61, the second reflecting structure 62, and the third reflecting structure 63 can reflect image light of different wavelengths, respectively.

[0152] For example, the first reflecting structure 61 has a function of selectively retroreflecting red light wavelengths, the second reflecting structure 62 has a function of selectively retroreflecting green light wavelengths, and the third reflecting structure 63 has a function of selectively retroreflecting blue light wavelengths.

[0153] For example, the first incident portion 41a has wavelength selectivity that allows it to deflect, by diffraction, red light contained in the image light emitted by the image light output portion 50, becoming first image light and propagating toward the first extension portion 42a of the first substrate 31. The first incident portion 41a has a function of transmitting image light having wavelength components other than red light. The image light having wavelength components other than red light contained in the image light transmits through the first incident portion 41a and enters the second incident portion 41b.

[0154] The image light that has passed through the first incident portion 41a is incident on the second incident portion 41b. The second incident portion 41b has wavelength selectivity that allows it to deflect the green light included in the image light by diffraction and become the first image light that propagates toward the first extension portion 42a of the second substrate 32. The second incident portion 41b has a function of transmitting image light that has wavelength components other than the green light.

[0155] The image light that has passed through the second incident portion 41b is incident on the third incident portion 41c. The third incident portion 41c has wavelength selectivity that allows it to deflect blue light contained in the image light by diffraction and become first image light that propagates toward the first extension portion 42a of the third substrate 33. The third incident portion 41c has a function of transmitting image light that has wavelength components other than blue light.

[0156] In this case, the image light emitted by the image light emitting unit 50 enters the first incident unit 41a. The red light included in the image light that enters the first incident unit 41a is deflected by diffraction by the first incident unit 41a. As a result, the traveling direction of this image light is changed from the first incident unit 41a toward the first extension unit 42a of the first substrate 31, and the image light is emitted by the first incident unit 41a as first image light (red light).

[0157] A portion of the image light incident on the first incident portion 41a passes through the first incident portion 41a as is and enters the first reflecting structure 61. Of the image light incident on the first reflecting structure 61, the red component image light is retro-reflected from the first reflecting structure 61 toward the first incident portion 41a and enters the first incident portion 41a. The red light included in the image light incident on the first incident portion 41a is deflected by diffraction by the first incident portion 41a. As a result, the traveling direction of this image light is changed from the first incident portion 41a toward the second extension portion 42b of the first substrate 31, and the first incident portion 41a emits the first image light (red light). The remaining image light that passed through the first incident portion 41a is emitted to the outside from the light guide plate 30n.

[0158] A portion of the image light incident on first reflecting structure 61 passes through first reflecting structure 61 as is and enters second incident portion 41b. Green light included in the image light incident on second incident portion 41b is deflected by diffraction by second incident portion 41b. As a result, the traveling direction of this image light is changed from second incident portion 41b toward first extension portion 42a of second substrate 32, and is emitted by second incident portion 41b as first image light (green light).

[0159] A portion of the image light incident on the second incident portion 41b passes through the second incident portion 41b as is and enters the second reflecting structure 62. Of the image light incident on the second reflecting structure 62, the green component image light is retroreflected from the second reflecting structure 62 toward the second incident portion 41b and enters the second incident portion 41b. The green light included in the image light incident on the second incident portion 41b is deflected by diffraction by the second incident portion 41b. As a result, the traveling direction of this image light is changed from the second incident portion 41b toward the second extension portion 42b of the second substrate 32 and is emitted by the second incident portion 41b as the first image light (green light). The remaining image light that passed through the second incident portion 41b is emitted to the outside from the light guide plate 30n.

[0160] A portion of the image light incident on second reflecting structure 62 passes through second reflecting structure 62 as is and enters third incident portion 41c. Blue light included in the image light incident on third incident portion 41c is deflected by diffraction by third incident portion 41c. As a result, the traveling direction of this image light is changed from third incident portion 41c to the direction of first extension portion 42a of third substrate 33, and is emitted by third incident portion 41c as first image light (blue light).

[0161] A portion of the image light incident on the third incident portion 41c passes through the third incident portion 41c as is and enters the third reflecting structure 63. Of the image light incident on the third reflecting structure 63, the blue component image light is retroreflected from the third reflecting structure 63 toward the third incident portion 41c and enters the third incident portion 41c. The blue light included in the image light incident on the third incident portion 41c is deflected by diffraction by the third incident portion 41c. As a result, the traveling direction of this image light is changed from the third incident portion 41c toward the second extension portion 42b of the third substrate 33 and is emitted by the third incident portion 41c as the first image light (blue light). The remaining image light that passed through the third incident portion 41c is emitted to the outside from the light guide plate 30n.

[0162] Next, as shown in FIGS. 20 and 21, the light guide plates 30p and 30q of this embodiment may have the following configuration.

[0163] Fig. 20 is a plan view showing an example of a light guide plate 30p having a first incident portion 41a and one pentagonal first exit portion 43a. Fig. 21 is a plan view showing an example of another light guide plate 30q having a first incident portion 41a and one pentagonal first exit portion 43a. Unless otherwise specified, the light guide plate 30p in Fig. 20 has the same configuration and function as the light guide plate 30b in Fig. 8. Unless otherwise specified, the light guide plate 30q in Fig. 21 has the same configuration and function as the light guide plate 30c in Fig. 9.

[0164] 20, the first emission portion 43a may have a pentagonal shape. In a plan view of the light guide plate 30p, of the two sides of the first emission portion 43a on the negative Y-axis side, one side in the positive X-axis direction (first side 143a) may be inclined downward toward the positive X-axis direction, and the other side in the negative X-axis direction (second side 143b) may be inclined downward toward the negative X-axis direction.

[0165] In this case, the first image light emitted from the first extension portion 42a is incident on the first side 143a of the first emission portion 43a, and the first image light emitted from the second extension portion 42b is incident on the second side 143b of the first emission portion 43a.

[0166] 21 , the first and second emission portions 43a and 43b may have a pentagonal shape. In a plan view with respect to the light guide plate 30q, of the two sides of the first emission portion 43a on the positive Y-axis side, one side in the positive X-axis direction (first side 143a) may be inclined upward toward the positive X-axis direction, and the other side in the negative X-axis direction may be inclined upward toward the negative X-axis direction. In a plan view with respect to the light guide plate 30q, of the two sides of the second emission portion 43b on the negative Y-axis side, one side in the positive X-axis direction may be inclined downward toward the positive X-axis direction, and the other side in the negative X-axis direction (second side 143b) may be inclined downward toward the negative X-axis direction.

[0167] In this case, the first image light emitted from the first extension portion 42a is incident on the first side of the first emission portion 43a, and the first image light emitted from the second extension portion 42b is incident on the second side of the second emission portion 43b.

[0168] <Action and effect> Next, the effects of the light guide plates 30, 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30j, 30k, 30m, 30n, 30p, and 30q (hereinafter sometimes abbreviated as 30 to 30q) and the display device 1 in this embodiment will be described.

[0169] As described above, the light guide plates 30 to 30q of the first technique relating to this embodiment include a first incident portion 41a configured with a volume hologram that diffracts incident light (image light), a first substrate 31 that supports the first incident portion 41a and has a first surface 131 on which the light (image light) is incident and a second surface 132 opposite to the first surface 131, and a first reflecting structure 61 that is arranged opposite the second surface 132 and reflects the light (image light) that has passed through the first incident portion 41a.

[0170] This allows the image light that has passed through the first incident portion 41a to be reflected by the first reflecting structure 61 and made incident on the first incident portion 41a. In other words, the first reflecting structure 61 can return the image light that has passed through the first incident portion 41a to the first incident portion 41a.

[0171] Therefore, according to the present disclosure, it is possible to improve the utilization efficiency of the image light incident on the light guide plates 30 to 30q.

[0172] Furthermore, the light guide plates 30 to 30q of Technology 2 according to this embodiment are light guide plates 30 to 30q according to Technology 1, further comprising a first extension section 42a supported by the first substrate 31 so as to be positioned adjacent to the first incident section 41a and made up of a volume hologram, and a second extension section 42b supported by the first substrate 31 so as to be positioned adjacent to the first incident section 41a and made up of a volume hologram, in which, after entering the first incident section 41a, the direction of travel of light is changed between the direction from the first incident section 41a to the first extension section 42a and the direction from the first incident section 41a to the second extension section 42b.

[0173] This allows the image light incident on the first incident portion 41a to be split into the first extended portion 42a and the second extended portion 42b. According to the present disclosure, the image light can be displayed over a larger area.

[0174] Furthermore, the light guide plates 30 to 30q of Technology 3 relating to this embodiment are light guide plates 30 to 30q described in Technology 2, which are supported by the first substrate 31 so as to be positioned adjacent to the first extension portion 42a and the second extension portion 42b, and further include a first exit portion 43a formed of a volume hologram, and the direction of travel of light (first image light) incident on the first extension portion 42a and the second extension portion 42b is changed from the first extension portion 42a and the second extension portion 42b toward the first exit portion 43a.

[0175] This allows the second image light that has passed through the first extension portion 42a and the second image light that has passed through the second extension portion 42b to be incident on one first exit portion 43a, thereby improving the utilization efficiency of the image light that enters the light guide plates 30 to 30q.

[0176] Furthermore, the light guide plates 30, 30a, 30c, 30d, 30e, 30h, 30j, 30k, 30m, and 30n of the fourth technique according to the present embodiment are supported by the first substrate 31 so as to be disposed adjacent to the first extension portion 42a and include a first exit portion 43a formed of a volume hologram, and a second exit portion 43b supported by the first substrate 31 so as to be disposed adjacent to the second extension portion 42b and include a volume hologram. The light guide plates 30, 30a, 30c, 30d, 30e, 30h, 30j, 30k, 30m, and 30n according to the second technology further include a light guide plate 30, 30a, 30c, 30d, 30e, 30h, 30j, 30k, 30m, and 30n according to the second technology, wherein the direction of light (first image light) incident on the first extension portion 42a is changed from the first extension portion 42a to the first exit portion 43a, and the direction of light (first image light) incident on the second extension portion 42b is changed from the second extension portion 42b to the second exit portion 43b.

[0177] This allows the image light incident on the first incident portion 41a to be split into the first extended portion 42a and the second extended portion 42b. According to the present disclosure, the image light can be displayed over a larger area.

[0178] Furthermore, light guide plates 30 to 30q of technology 5 relating to this embodiment are light guide plates 30 to 30q described in technology 2 in which light (image light) incident on first substrate 31 from first surface 131 is changed in its traveling direction from first incident portion 41a to first extension portion 42a after entering first incident portion 41a, and light (image light) reflected by first reflecting structure 61 is changed in its traveling direction from first incident portion 41a to second extension portion 42b after entering first incident portion 41a.

[0179] This allows the image light that is not diffracted by first incident portion 41a to be reflected by first reflecting structure 61 and incident on second incident portion 41b, thereby improving the utilization efficiency of the image light that is incident on light guide plates 30 to 30q.

[0180] Furthermore, the light guide plates 30 to 30q of Technology 6 relating to this embodiment are light guide plates 30 to 30q described in Technology 2 in which the light (image light) incident on the first substrate 31 is changed, after entering the first incident portion 41a, to a direction from the first incident portion 41a to the first extension portion 42a and a direction from the first incident portion 41a to the second extension portion 42b, and the light (image light) reflected by the first reflecting structure 61 is changed, after entering the first incident portion 41a, to a direction from the first incident portion 41a to the first extension portion 42a and a direction from the first incident portion 41a to the second extension portion 42b.

[0181] This allows the image light incident on the first incident portion 41a to be split into the first extension portion 42a and the second extension portion 42b, the image light that has passed through the first incident portion 41a to be returned to the first incident portion 41a, and the diffracted image light to be split into the first extension portion 42a and the second extension portion 42b.

[0182] According to the present disclosure, it is possible to improve the utilization efficiency of the image light incident on the light guide plates 30 to 30q and display the image light over a larger area.

[0183] Furthermore, the light guide plates 30a, 30e, 30j, 30k, 30m, and 30n of Technology 7 according to this embodiment are the light guide plates 30a, 30e, 30j, 30k, 30m, and 30n according to Technology 2 in which, when the light guide plate 30 is viewed in a plane, the ratio between the first area of ​​the first extension portion 42a and the second area of ​​the second extension portion 42b is equal to the ratio between the amount of light (first image light) whose traveling direction is changed at the first incident portion 41a toward the first extension portion 42a and the amount of light (first image light) whose traveling direction is changed at the first incident portion 41a toward the second extension portion 42b.

[0184] According to this, the ratio between the amount of first image light incident on the first extension portion 42a and the amount of first image light incident on the second extension portion 42b is equal to the ratio between the amount of first image light incident on the first exit portion 43a and the amount of first image light incident on the second exit portion 43b. Therefore, the amount of third image light emitted by the first exit portion 43a is equal to the amount of third image light emitted by the second exit portion 43b. As a result, the third image light emitted by the first exit portion 43a and the third image light emitted by the second exit portion 43b can be made to have the same brightness, which prevents the user from feeling uncomfortable.

[0185] Furthermore, light guide plates 30d, 30e, 30f, and 30g of technology 8 relating to this embodiment further include a second incident portion 41b arranged adjacent to first incident portion 41a, and when light guide plates 30d, 30e, 30f, and 30g are viewed in a plan view, the center of first reflecting structure 61 is arranged to be offset from the center of first incident portion 41a, and light (image light) incident on first reflecting structure 61 is reflected from first reflecting structure 61 in the direction of second incident portion 41b, the light diffracted by first incident portion 41a (first image light) has its traveling direction changed from first incident portion 41a to first extension portion 42a, and the light diffracted by second incident portion 41b (first image light) has its traveling direction changed from second incident portion 41b to second extension portion 42b.

[0186] This allows the first image light diffracted by the first incident portion 41a to be incident on the first extension portion 42a, and the image light that passes through the first incident portion 41a and is reflected by the first reflecting structure 61 to be incident on the second incident portion 41b, and the first image light diffracted by the second incident portion 41b to be incident on the second extension portion 42b.

[0187] According to the present disclosure, it is possible to improve the utilization efficiency of the image light incident on the light guide plates 30d, 30e, 30f, and 30g, and to display the image light over a larger area.

[0188] Furthermore, the light guide plate 30h of the ninth technique according to the present embodiment further includes a second reflecting structure 162 arranged outside the first substrate 31, a third reflecting structure 163 arranged outside the first substrate 31, a polarizing beam splitter 70 arranged outside the first substrate 31, and a half-wave plate 72 arranged between the second reflecting structure 162 and the third reflecting structure 163, and the light (image light) is directed by the first reflecting structure 161 toward the second reflecting structure 162 along a horizontal direction parallel to the second surface 132 of the first substrate 31. The light guide plate 30h according to any one of the first to eighth techniques is such that the light is reflected by the second reflecting structure 162 toward the half-wave plate 72 along a vertical direction perpendicular to the second surface 132 of the first substrate 31, polarized by the half-wave plate 72 and emitted toward the third reflecting structure 163, reflected by the third reflecting structure 163 toward the polarizing beam splitter 70 along a horizontal direction parallel to the first surface 131 of the first substrate 31, and reflected by the polarizing beam splitter 70 toward the first entrance portion 41a.

[0189] This allows the image light that has passed through the first incident portion 41a to return to the first incident portion 41a from the first surface 131. This makes it possible to improve the utilization efficiency of the image light.

[0190] Furthermore, light guide plate 30j of technique 10 according to the present embodiment further includes second reflecting structure 162 arranged outside first substrate 31, third reflecting structure 163 arranged outside first substrate 31, fourth reflecting structure 164 arranged outside first substrate 31, and half-wave plate 72 arranged between second reflecting structure 162 and third reflecting structure 163, and light (image light) is reflected by first reflecting structure 161 toward second reflecting structure 162 along a horizontal direction parallel to second surface 132 of first substrate 31, and is reflected by second reflecting structure 161 toward fourth reflecting structure 164. The light guide plate 30j according to any one of the techniques 1 to 8 is such that the light is reflected by the structure 162 toward the half-wave plate 72 along a vertical direction perpendicular to the second surface 132 of the first substrate 31, is polarized by the half-wave plate 72 and emitted toward the third reflecting structure 163, is reflected by the third reflecting structure 163 toward the fourth reflecting structure 164 along a horizontal direction parallel to the first surface 131 of the first substrate 31, and is reflected by the fourth reflecting structure 164 to the third reflecting structure 163 along the horizontal direction parallel to the first surface 131 of the first substrate 31.

[0191] This allows the image light (P waves) incident on the first incident portion 41a and the image light (S waves) passing through the half-wave plate 72 to be incident on the first incident portion 41a from the first surface 131 of the first substrate 31 and emitted toward the first extension portion 42a. Because the image light (P waves) and the image light (S waves) are incident on the first extension portion 42a, the utilization efficiency of the image light can be improved.

[0192] Furthermore, by reflecting the image light (S waves) that has returned to the first incident portion 41a by the fourth reflecting structure 164, the image light (P waves) that has passed through the half-wave plate 72 can be made to enter the first incident portion 41a from the first surface 131 of the first substrate 31 and be emitted toward the first extension portion 42a. Furthermore, even if the image light (P waves) passes through the first incident portion 41a, if the image light (S waves) is reflected by the third reflecting structure 163, the image light (P waves) that has passed through the half-wave plate 72 can be made to enter the first incident portion 41a from the second surface 132 of the first substrate 31 and be emitted toward the second extension portion 42b. Because the image light (P waves) and the image light (S waves) are incident on the second extension portion 42b, the utilization efficiency of the image light can be improved.

[0193] Furthermore, the light guide plate 30k of Technology 11 according to this embodiment is the light guide plate 30k according to any one of Technologies 1 to 8, further comprising a specular polarized reflective film 65 arranged on the first surface 131 side, and a quarter-wave plate 74 arranged between the first substrate 31 and the first reflecting structure 61.

[0194] This allows image light (P waves) incident on the first incident portion 41a to be incident on the first incident portion 41a from the first surface 131 of the first substrate 31 and emitted toward the first extension portion 42a, and image light (S waves) passing through the quarter-wave plate 74 to be incident on the first incident portion 41a from the second surface 132 of the first substrate 31 and emitted toward the second extension portion 42b. In other words, even if the first incident portion 41a is not exposed on both sides, light can be incident from both sides of the first incident portion 41a and emitted toward the first extension portion 42a and the second extension portion 42b.

[0195] Since image light (P waves) and image light (S waves) are incident on the first extension portion 42a, according to the present disclosure, the utilization efficiency of the image light incident on the light guide plate 30k can be improved and the image light can be displayed over a larger area.

[0196] Furthermore, the light guide plate 30m of Technology 12 relating to this embodiment is the light guide plate 30m described in any one of Technologies 1 to 8, which further includes a second substrate 32 supporting a second incident portion 41b consisting of a volume hologram and a third substrate 33 supporting a third incident portion 41c consisting of a volume hologram, and in which the first incident portion 41a of the first substrate 31, the second incident portion 41b of the second substrate 32, and the third incident portion 41c of the third substrate 33 diffract light of different wavelengths.

[0197] With this, for example, RGB component light included in image light can be diffracted from the first surface 131 side to the first incident portion 41a, the second incident portion 41b, and the third incident portion 41c and then incident on the first extension portion 42a. Also, image light that passes through the first incident portion 41a, the second incident portion 41b, and the third incident portion 41c and is reflected by the first reflecting structure 61 can be diffracted again from the second surface 132 side to the first incident portion 41a, the second incident portion 41b, and the third incident portion 41c and then incident on the second extension portion 42b. In other words, even if the first incident portion 41a is not exposed on both sides, light can be incident from both sides of the first incident portion 41a and emitted toward the first extension portion 42a and the second extension portion 42b.

[0198] According to the present disclosure, it is possible to improve the utilization efficiency of the image light incident on the light guide plate 30m and display the image light over a larger area.

[0199] Furthermore, the light guide plate 30n of Technology 13 according to this embodiment is the light guide plate 30n according to Technology 12, which further includes a second reflection structure 62 that selectively reflects light of a predetermined wavelength (image light), the first reflection structure 61 selectively reflects wavelengths, the first reflection structure 61 and the second reflection structure 62 each reflect light of different wavelengths, and the first reflection structure 61 is disposed between the first substrate 31 and the second substrate 32, and the second reflection structure 62 is disposed between the second substrate 32 and the third substrate 33.

[0200] According to this, the light guide plate 30n can diffract image light of a specific component (e.g., red light) among the RGB components contained in the image light to the first incident portion 41a and make it incident on the first extension portion 42a, and can diffract image light that passes through the first incident portion 41a and is reflected by the first reflection structure 61 again to the first incident portion 41a and make it incident on the second extension portion 42b.

[0201] In addition, the light guide plate 30n can diffract another component of the image light (e.g., green light) among the RGB components contained in the image light to the second incident portion 41b and make it incident on the first extension portion 42a, and can diffract the image light that passes through the second incident portion 41b and is reflected by the second reflection structure 62 again to the second incident portion 41b and make it incident on the second extension portion 42b.

[0202] In addition, the light guide plate 30n can diffract image light of another component (e.g., blue light) of the RGB components contained in the image light to the third incident portion 41c and make it incident on the first extension portion 42a, and can diffract image light that passes through the third incident portion 41c and is reflected by the third reflection structure 63 again to the third incident portion 41c and make it incident on the second extension portion 42b.

[0203] In other words, even if the first incident portion 41a is not exposed on both sides, light can be incident from both sides of the first incident portion 41a and emitted toward the first extension portion 42a and the second extension portion 42b. According to the present disclosure, the utilization efficiency of the image light incident on the light guide plate 30n can be improved, and the image light can be displayed over a larger area.

[0204] Furthermore, the light guide plate 30n of Technology 14 relating to this embodiment is the light guide plate 30n described in Technology 13, which further includes a third reflection structure 63 that selectively reflects light of a predetermined wavelength (image light), the third reflection structure 63 selectively reflects wavelengths, the first reflection structure 61, the second reflection structure 62, and the third reflection structure 63 each reflect light of different wavelengths, and the third reflection structure 63 is arranged on the side of the third substrate 33 opposite to the second substrate 32 side.

[0205] According to this, the light guide plate 30n can diffract image light of another component (e.g., blue light) of the RGB components contained in the image light to the third incident portion 41c and cause it to enter the first extension portion 42a, and can diffract image light (e.g., red light) that has passed through the third incident portion 41c and been reflected by the third reflection structure 63 again to the second incident portion 41b and cause it to enter the second extension portion 42b. In other words, even if the first incident portion 41a is not exposed on both sides, light can be incident from both sides of the first incident portion 41a and emitted toward the first extension portion 42a and the second extension portion 42b.

[0206] According to the present disclosure, it is possible to improve the utilization efficiency of the image light incident on the light guide plate 30n and display the image light over a larger area.

[0207] In the light guide plates 30 to 30q of Technique 15 according to the present embodiment, the first reflecting structure 61 is the light guide plate 30 to 30q according to any one of Techniques 1 to 14 that retroreflects light (image light).

[0208] This allows the first reflecting structure 61 to reflect the image light along the optical path of the image light that has passed through the first incident surface 31a and entered the first reflecting structure 61, thereby allowing the image light to be reflected back toward the first incident surface 31a.

[0209] Furthermore, the display device 1 of Technology 16 according to this embodiment is a light guide plate 30-30q according to any one of Technologies 1-15, which includes a light source (image light emitting section 50) that makes light incident on the light guide plate 30, and a display medium onto which the light emitted from the light guide plate 30 is incident.

[0210] This provides the same effects as the above-described light guide plates 30 to 30q.

[0211] (Other variations) While the light guide plate and display device according to the present disclosure have been described above based on the above-mentioned embodiments, the present disclosure is not limited to these embodiments. As long as the modifications do not deviate from the spirit of the present disclosure, modifications that would occur to those skilled in the art may also be included in the scope of the present disclosure.

[0212] In addition, this disclosure also includes forms obtained by making various modifications to the above embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the intent of this disclosure. [Industrial Applicability]

[0213] The present disclosure can be used in display devices such as head-up displays mounted on vehicles. [Explanation of symbols]

[0214] 1 Display device 3. Front window (display medium) 30, 30a, 30b, 30c, 30d, 30e, 30f, 30g, 30h, 30j, 30k, 30m, 30n, 30p, 30q light guide plate 31 First board 32 Second board 33 Third board 41a 1st entrance part 41b 2nd entrance part 41c 3rd entrance section 42a First Extension 42b Second Extension 43a First exit section 43b 2nd output section 50 Image light emitting unit (light source) 61, 161 1st reflection structure 62, 162 Second reflective structure 63, 163 Third reflection structure 164 4th reflection structure 65 Specular polarized reflective film 70 Polarizing Beam Splitter 72 1 / 2 wave plate 74 1 / 4 wave plate 131 Page 1 132 Page 2

Claims

1. a first incident portion configured by a volume hologram that diffracts incident light; a first substrate supporting the first incident portion and having a first surface onto which the light is incident and a second surface opposite to the first surface; a first reflecting structure that is disposed to face the second surface and that reflects the light that has passed through the first incident portion; light guide plate.

2. a first extension portion supported by the first substrate so as to be disposed adjacent to the first entrance portion and configured as a volume hologram; a second extension portion supported by the first substrate so as to be disposed adjacent to the first entrance portion and configured by a volume hologram, After the light is incident on the first incident portion, the traveling direction of the light is changed from the first incident portion to the first extension portion and from the first incident portion to the second extension portion. The light guide plate according to claim 1 .

3. a first exit section supported by the first substrate so as to be disposed adjacent to the first extension section and the second extension section, the first exit section being made up of a volume hologram; The light incident on the first extension portion and the second extension portion is changed in direction from the first extension portion and the second extension portion to the first exit portion. The light guide plate according to claim 2 .

4. a first exit section supported by the first substrate so as to be disposed adjacent to the first extension section and configured as a volume hologram; a second exit section supported by the first substrate so as to be disposed adjacent to the second extension section and configured by a volume hologram, The light incident on the first extension portion is changed in its traveling direction from the first extension portion to the first exit portion, The light incident on the second extension portion is changed in its traveling direction from the second extension portion to the second exit portion. The light guide plate according to claim 2 .

5. the light incident on the first substrate from the first surface is incident on the first incident portion, and then the traveling direction of the light is changed from the first incident portion to a direction of the first extension portion; The light reflected by the first reflection structure is incident on the first incident portion, and then the traveling direction of the light is changed from the first incident portion to the second extension portion. The light guide plate according to claim 2 .

6. After the light incident on the first substrate is incident on the first incident portion, the traveling direction of the light is changed from the first incident portion to the first extension portion and from the first incident portion to the second extension portion, The light reflected by the first reflection structure is incident on the first incident portion, and then its traveling direction is changed from the first incident portion to the first extension portion and from the first incident portion to the second extension portion. The light guide plate according to claim 2 .

7. When the light guide plate is viewed from above, a ratio between a first area of ​​the first extension portion and a second area of ​​the second extension portion is equal to a ratio between an amount of light whose traveling direction is changed toward the first extension portion at the first incident portion and an amount of light whose traveling direction is changed toward the second extension portion at the first incident portion. The light guide plate according to claim 2 .

8. Further, a second incident portion is disposed adjacent to the first incident portion, When the light guide plate is viewed from above, a center of the first reflection structure is disposed so as to be shifted from a center of the first incident portion, the light incident on the first reflecting structure is reflected from the first reflecting structure toward the second incident portion, The light diffracted by the first incident portion is changed in its traveling direction from the first incident portion to the first extension portion, The light diffracted by the second incident portion is changed in its traveling direction from the second incident portion to the second extension portion. The light guide plate according to claim 2 .

9. a second reflecting structure disposed outside the first substrate, a third reflecting structure disposed outside the first substrate, a polarizing beam splitter disposed outside the first substrate, and a half-wave plate disposed between the second reflecting structure and the third reflecting structure, The light is the first reflecting structure reflects the light toward the second reflecting structure along a horizontal direction parallel to the second surface of the first substrate; the second reflection structure reflects the light toward the half-wave plate along a vertical direction perpendicular to the second surface of the first substrate, The light is polarized by the half-wave plate and emitted toward the third reflection structure; the third reflecting structure is reflected toward the polarizing beam splitter along a horizontal direction parallel to the first surface of the first substrate, The polarized beam is reflected by the polarized beam splitter toward the first incident portion. The light guide plate according to claim 1 .

10. a second reflecting structure disposed outside the first substrate, a third reflecting structure disposed outside the first substrate, a fourth reflecting structure disposed outside the first substrate, and a half-wave plate disposed between the second reflecting structure and the third reflecting structure, The light is the first reflecting structure reflects the light toward the second reflecting structure along a horizontal direction parallel to the second surface of the first substrate; the second reflection structure reflects the light toward the half-wave plate along a vertical direction perpendicular to the second surface of the first substrate, The light is polarized by the half-wave plate and emitted toward the third reflection structure; the light is reflected by the third reflection structure toward the fourth reflection structure along a horizontal direction parallel to the first surface of the first substrate, The fourth reflecting structure reflects the light to the third reflecting structure along a horizontal direction parallel to the first surface of the first substrate. The light guide plate according to claim 1 .

11. The optical element further includes a specular polarized reflective film disposed on the first surface side, and a quarter-wave plate disposed between the first substrate and the first reflective structure. The light guide plate according to claim 1 .

12. further comprising a second substrate supporting a second entrance portion made of a volume hologram, and a third substrate supporting a third entrance portion made of a volume hologram; The first incident portion of the first substrate, the second incident portion of the second substrate, and the third incident portion of the third substrate diffract light of different wavelengths. The light guide plate according to claim 1 .

13. Further provided is a second reflective structure that selectively retroreflects light of a predetermined wavelength, the first reflective structure selectively retroreflects wavelengths; the first reflecting structure and the second reflecting structure reflect light of different wavelengths, the first reflecting structure is disposed between the first substrate and the second substrate; The second reflecting structure is disposed between the second substrate and the third substrate. The light guide plate according to claim 12.

14. Further provided is a third reflection structure that selectively retroreflects light of a predetermined wavelength, the third reflective structure selectively retroreflects wavelengths; the first reflecting structure, the second reflecting structure, and the third reflecting structure each reflect light of a different wavelength; The third reflecting structure is disposed on the opposite side of the third substrate from the second substrate side. The light guide plate according to claim 13.

15. The first reflective structure retroreflects light. The light guide plate according to claim 1 .

16. The light guide plate according to any one of claims 1 to 15, a light source that causes light to enter the light guide plate; a display medium onto which the light emitted from the light guide plate is incident. Display device.

Images