Optical member, display device, and manufacturing method

Abstract

To provide an optical member and the like capable of outputting image light with uniform distribution.SOLUTION: An optical member 30, 30a includes: a hologram element 40 for diffracting image light representing an image generated by an image light output unit 50 and outputs the same; and a translucent part on which the hologram element 40 is placed. The hologram element 40 has multiple areas that include a first area and a second area that is an area different from the first area. At least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimal angle of incidence with respect to the deflection angle varies in the first area and the second area so as to suppress brightness unevenness caused from surface unevenness of the translucent part, non-uniform thickness of the translucent part, or non-uniformity in the distribution of the image light output from the image light output unit 50.SELECTED DRAWING: Figure 5

Description

Technical Field

[0001] The present disclosure relates to an optical member, a display device, and a manufacturing method.

Background Art

[0002] As a conventional technique, there is disclosed an optical device that forms a hologram optical element having a plurality of corresponding diffraction peak wavelengths on a transparent substrate by exposing a hologram photosensitive material attached to the transparent substrate with laser light of a plurality of wavelengths from a light source for manufacturing.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the optical device of Patent Document 1, for example, when the surface of the transparent substrate is uneven, the thickness of the transparent substrate is uneven, the light distribution emitted from the image display element is uneven, or even in the case of exposure set to a certain diffraction efficiency value, the light of the two light beams is uneven or non-uniformity due to the material characteristics of the hologram element occurs, there is a problem that the light seen through the hologram optical element does not look uniform.

[0005] Therefore, an object of the present disclosure is to provide an optical member, a display device, and a manufacturing method capable of emitting image light with a uniform distribution.

Means for Solving the Problems

[0006] An optical member according to one aspect of the present disclosure includes a hologram element that diffracts and emits image light showing an image generated by an image light emitting unit, and a light-transmitting portion provided with the hologram element. The hologram element has a plurality of regions including a first region and a second region different from the first region. At least one of the diffraction efficiency of the hologram element, the deflection angle of the image light in the hologram element, and the optimum incident angle with respect to the deflection angle is different between the first region and the second region so as to suppress luminance unevenness caused by unevenness on the surface of the light-transmitting portion, unevenness in the thickness of the light-transmitting portion, or unevenness in the distribution of the image light emitted by the image light emitting unit.

Advantages of the Invention

[0007] According to the optical member and the like of the present disclosure, image light with a uniform distribution can be emitted.

Brief Description of the Drawings

[0008]

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DETAILED DESCRIPTION OF THE INVENTION

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

[0010] Note that all of the embodiments described below show comprehensive or specific examples. Numerical values, shapes, materials, components, arrangement positions of components, connection forms, etc. shown in the following embodiments are merely examples and are not intended to limit the present disclosure. In addition, among the components in the following embodiments, components not described in the independent claims are described as optional components.

[0011] Also, each figure is a schematic diagram and is not necessarily drawn precisely. Also, in each figure, the same reference numerals are given to the same constituent members.

[0012] Also, in the following embodiments, expressions such as rectangular shape, substantially parallel, and X-axis direction are used. For example, the rectangular shape, substantially 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, including an error of about several percent. Also, the rectangular shape, parallel, and X-axis direction mean rectangular, substantially parallel, and X-axis direction within the range where the effects according to the present disclosure can be achieved. The same applies to other expressions using "shape", "substantially", and "direction".

[0013] (Embodiment) <Configuration> First, the configuration of the display device 1 will be described with reference to FIGS. 1 to 4.

[0014] FIG. 1 is a schematic diagram showing an example of a vehicle 2 in which the display device 1 according to the embodiment is installed. FIG. 2 is a schematic diagram showing the display device 1 and the vehicle 2 according to the embodiment as viewed from the side. FIG. 3 is a perspective view showing the display device 1 using the light guide plate according to the embodiment. FIG. 4 is a view showing the display device 1 using the light guide plate according to the embodiment. FIG. 4(a) is a front view of the display device 1, FIG. 4(b) is a cross-sectional view of the display device 1 taken along line B-B of FIG. 4(a), and FIG. 4(c) is a cross-sectional view of the display device 1 taken along line C-C of FIG. 4(a).

[0015] As shown in FIGS. 1 and 2, the display device 1 can cause image light to enter a person's eye by emitting and reflecting the image light from a light reflector. For example, when the display device 1 is used in a vehicle 2, the display device 1 can cause image light to enter a person's eye by reflecting the image light emitted to a front window 3 as a light-transmitting member. In this case, by the display device 1 emitting the image light, an image shown in the image light is projected onto the light-transmitting member, and a virtual image corresponding to the image can be displayed on the light-transmitting member. The image light is light showing an image and is light for displaying a virtual image in front of the front window 3. The image is a still image or a moving image and is an image showing numbers, characters, figures, and the like.

[0016] As shown in FIGS. 2 and 3, the display device 1 includes an image light emitting unit 50 and an optical member 30. FIGS. 2 and 3 illustrate a case where, as an example of the light-transmitting portion, the light-transmitting portion is a light guide portion 31 (light guide plate) that propagates image light.

[0017] The image light emitting unit 50 is an image generation device that emits image light to the optical member 30. By the image light emitting unit 50 emitting image light showing a rectangular image, the image light is projected onto the front window 3 via the optical member 30. Thereby, a virtual image is recognized by the user.

[0018] Such an image light emitting unit 50 has a plurality of emitters, a plurality of dichroic mirrors, a condenser lens, a mirror, and an emission surface.

[0019] Each of the plurality of emitters is different from one another and emits a light beam that is light in a predetermined wavelength band. Each of the plurality of dichroic mirrors is disposed on the light beam emitted by the emitter and can reflect a light beam in a predetermined wavelength band and transmit light beams in other wavelength bands. The condenser lens is a lens that condenses the light beam emitted through the dichroic mirror onto the plurality of mirrors. The emission surface is a screen such as a microlens array or a liquid crystal display element such as a liquid crystal on silicon (LCOS). When irradiated with light beams in a plurality of wavelength bands from the mirror side, the transmitted light can be emitted toward the optical member 30 as image light.

[0020] The optical member 30 is a holographic light guide plate that displays the image indicated by the image light to the user. The optical member 30 has light transmissivity and can stretch and emit the image shown in the image light emitted by the image light emitting unit 50 in the X-axis direction and the Y-axis direction. The optical member 30 is disposed so as to face the image light emitting unit 50 and the front window 3.

[0021] The optical member 30 is formed with an incident surface 31a and an emission surface 31b.

[0022] The incident surface 31a is disposed so as to face the emission surface of the image light emitting unit 50. Image light emitted from the emission surface of the image light emitting unit 50 is incident on the incident surface 31a. The incident surface 31a is a part of the back surface of the rectangular optical member 30. The back surface is the surface on the side opposite to the emission surface 31b of the optical member 30.

[0023] The emission surface 31b emits, toward the front window 3, the image light that is the image light incident from the incident surface 31a and has propagated inside the optical member 30. The emission surface 31b faces the front window 3 and is separated from the front window 3 by a predetermined distance. The emission surface 31b is a part of the surface of the optical member 30.

[0024] As shown in FIG. 4, the optical member 30 includes a light guide unit 31 having light transmissivity and one or more hologram elements 40. In the present embodiment, a plurality of hologram elements 40 are exemplified.

[0025] An incident surface 31a facing the image light emitting unit 50 is formed on the light guide unit 31. The incident surface 31a is a surface facing the image light emitting unit 50 and is a part of the back surface of the light guide unit 31. Further, an emission surface 31b is formed on the light guide unit 31 so as to face the front window 3. The emission surface 31b is a part of the surface of the light guide unit 31.

[0026] The light guide unit 31 is made of a material having light transmissivity such as glass and resin materials, for example.

[0027] Inside the light guide unit 31, a plurality of hologram elements 40 that diffract and emit image light indicating an image generated by the image light emitting unit 50 are included. As shown in FIG. 4, the plurality of hologram elements 40 are light transmissive optical elements that diffract and emit light propagating through the light guide unit 31. The plurality of hologram elements 40 are included in the light guide unit 31 in a posture substantially parallel to the incident surface 31a and the emission surface 31b of the light guide unit 31. The plurality of hologram elements 40 are made of a material having light transmissivity.

[0028] Such a plurality of hologram elements 40 include an incident hologram element 41, a turning-back hologram element 42, and an emission hologram element 43. Note that the incident hologram element 41, the turning-back hologram element 42, and the emission hologram element 43 may be collectively referred to simply as the hologram element 40.

[0029] The incident hologram element 41 and the return hologram element 42 are arranged side by side along the X-axis direction. The return hologram element 42 and the exit hologram element 43 are arranged side by side along the Y-axis direction. Further, the incident hologram element 41 overlaps with the incident surface 31a of the optical member 30 when viewed along the Z-axis direction, and is arranged so as to overlap with the exit surface of the image light exit portion 50 arranged on the minus Z-axis direction side of the optical member 30. The incident hologram element 41 is on the plus X-axis direction side of the return hologram element 42 and is arranged on the light incident side of the optical member 30 with respect to the return hologram element 42.

[0030] The incident hologram element 41 is a hologram element 40 into which the image light emitted from the image light exit portion 50 is incident. The incident hologram element 41 is an example of the first hologram element.

[0031] The incident hologram element 41 is incident with the image light traveling along the plus Z-axis direction emitted from the exit surface of the image light exit portion 50, and emits the incident image light toward the return hologram element 42. Specifically, when the image light incident on the optical member 30 propagates within the optical member 30, the incident hologram element 41 diffracts the image light according to the diffraction efficiency of the incident hologram element 41, and emits it as the first image light (diffracted light) propagating along the minus X-axis direction. The first image light diffracted by the incident hologram element 41 is incident on the return hologram element 42.

[0032] The return hologram element 42 is on the minus X-axis direction side of the incident hologram element 41, is arranged on the light exit side of the incident hologram element 41, is on the minus Y-axis direction side of the exit hologram element 43, and is arranged on the light incident side of the optical member 30 with respect to the exit hologram element 43.

[0033] The return hologram element 42 is a hologram element 40 that is long along the X-axis direction, diffracts the first image light emitted from the incident hologram element 41, and emits the second image light to the exit hologram element 43. The return hologram element 42 is an example of the first hologram element or the second hologram element.

[0034] Each time the first image light transmitted through the incident hologram element 41 enters (transmits through) the return hologram element 42, the return hologram element 42 emits the second image light (deflected light) obtained by further deflecting the incident first image light by diffraction toward the emission hologram element 43. Specifically, when the first image light incident on the return hologram element 42 propagates in the optical member 30 along the negative X-axis direction, the return hologram element 42 further deflects the first image light by diffraction according to the diffraction efficiency of the return hologram element 42. The return hologram element 42 is configured such that the diffraction efficiency increases from a position close to the incident hologram element 41 toward a position far from the incident hologram element 41 in order to suppress luminance unevenness. At this time, the return hologram element 42 stretches the image of the first image light along the X-axis direction. As a result, the return hologram element 42 emits the second image light stretched along the X-axis direction along the positive Y-axis direction. The second image light deflected by diffraction by the return hologram element 42 enters the emission hologram element 43.

[0035] The emission hologram element 43 is on the positive Y-axis direction side of the return hologram element 42 and is disposed on the light emission side of the return hologram element 42. Further, the emission hologram element 43 is disposed so as to overlap and face the emission surface 31b of the optical member 30.

[0036] The emission hologram element 43 is a hologram element 40 having a rectangular shape when viewed along the Z-axis direction. The emission hologram element 43 is an example of the second hologram element.

[0037] Each time the second image light transmitted through the folded hologram element 42 is incident (transmitted) on the output hologram element 43, the output hologram element 43 outputs the third image light (deflected light) obtained by further deflecting the incident second image light by diffraction at a predetermined output angle. Specifically, when the second image light deflected by the folded hologram element 42 by diffraction propagates in the optical member 30 along the +Y axis direction, the output hologram element 43 further deflects the second image light by diffraction according to the diffraction efficiency of the output hologram element 43. The output hologram element 43 is configured such that the diffraction efficiency increases from the vicinity of the folded hologram element 42 toward the distant part in order to suppress luminance unevenness. At this time, the output hologram element 43 further extends the image of the second image light extended along the X axis direction substantially along the Y axis direction. As a result, the output hologram element 43 outputs the third image light extended along the X axis direction and substantially along the Y axis direction to the outside of the optical member 30 at a predetermined output angle. That is, the output hologram element 43 outputs the third image light enlarged in the X axis direction and the Y axis direction at a predetermined output angle by further extending the second image light output from the folded hologram element 42 substantially along the Y axis direction. In the present embodiment, the output hologram element 43 outputs the third image light in the +Z axis direction so as to face the front window 3.

[0038] Here, the predetermined output angle is the output angle of the third image light output from the output surface of the output hologram element 43, and is the angle of the light output with respect to the normal line of the output surface of the output hologram element 43.

[0039] Next, with reference to FIGS. 5 to 10, a specific configuration of the hologram element 40 will be described.

[0040] FIG. 5 is a diagram showing the diffraction efficiency of a conventional hologram element using a light guide plate, the deflection angle and incident angle of image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonically increasing from one side to the other, and the deflection angle and incident angle of the image light in the hologram element 40. Here, "from one side to the other" may be any direction, for example, any of the +X axis direction, -X axis direction, +Y axis direction, -Y axis direction, +Z axis direction, and -Z axis direction. In (a3) and (b4) of FIG. 5, (a3) and (b4) of FIG. 6, (a3) and (b4) of FIG. 7, (a3) and (b4) of FIG. 8, and (a3) and (b3) of FIG. 9, although the actual light guide plate (optical member 30) is curved according to the curved hologram element 40, a flat optical member 30 is shown in order to simplify the drawing so that the drawing does not become complicated.

[0041] (a1) of FIG. 5 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 5 shows the luminance unevenness of the optical member when using a conventional hologram element. (a3) of FIG. 5 shows the deflection angle and incident angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element. The amount of light is indicated by the length of the arrow. The same applies to the following figures.

[0042] (b1) of FIG. 5 shows the non-linearly increasing diffraction efficiency of the hologram element 40. (b2) of FIG. 5 shows the linearly increasing diffraction efficiency of the hologram element 40. (b3) of FIG. 5 shows the luminance uniformized by the optical member 30 when using the hologram element 40.

[0043] (b4) of FIG. 5 shows the deflection angle and incident angle of the image light monotonically increasing in the curved hologram element 40 and the amount of light emitted from the curved hologram element 40. The amount of light is indicated by the length of the arrow.

[0044] In addition, FIGS. 5(a1), 5(b1), and 5(b2) show cases where the diffraction efficiency decreases as the direction of the Y-axis minus increases. For example, in the output hologram element 43, the diffraction efficiency A2 on the minus side of the Y-axis is smaller than the diffraction efficiency A1 on the plus side of the Y-axis. In the incident hologram element 41 and the folding-back hologram element 42, the diffraction efficiency A2 on the minus side of the Y-axis is the same as the diffraction efficiency A1 on the plus side of the Y-axis. The same applies to the subsequent figures.

[0045] In addition, in FIGS. 5(b1) and 5(b2), the diffraction efficiency of the hologram element 40 is changed as the direction of the X-axis plus increases, but it is not limited to this. The optimum incident angle with respect to the deflection angle in the hologram element 40 may be changed as the direction of the X-axis plus increases. That is, in the hologram element 40, at least one of the diffraction efficiency and the optimum incident angle with respect to the deflection angle may be changed as the direction of the X-axis plus increases.

[0046] In addition, in FIG. 5, a plurality of regions are arranged along the X-axis direction, but it is not limited to this. A plurality of regions may be arranged not only along the X-axis direction but also along the Y-axis direction. That is, in a plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle in the hologram element 40 may be changed not only in one direction but also along two directions.

[0047] FIG. 6 is a diagram showing the diffraction efficiency of a conventional hologram element using a light guide plate, the deflection angle and the incident angle of the image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonically increasing from the central portion to the edge in the hologram element 40, and the deflection angle and the incident angle of the image light in the hologram element 40.

[0048] (a1) of FIG. 6 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 6 shows the luminance unevenness of the optical member when a conventional hologram element is used. (a3) of FIG. 6 shows the deflection angle and incident angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0049] (b1) of FIG. 6 shows the non-linearly increasing diffraction efficiency of the hologram element 40. (b2) of FIG. 6 shows the monotonically increasing diffraction efficiency of the hologram element 40. (b3) of FIG. 6 shows the luminance uniformized by the optical member 30 when the hologram element 40 is used. (b4) of FIG. 6 shows the monotonically increasing deflection angle and incident angle of the image light in the curved hologram element 40 and the amount of light emitted from the curved hologram element 40.

[0050] FIG. 7 is a diagram showing the diffraction efficiency of a conventional hologram element using a light guide plate, the deflection angle and incident angle of the image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonically increasing and monotonically decreasing are repeated in the hologram element 40, and the deflection angle and incident angle of the image light in the hologram element 40.

[0051] (a1) of FIG. 7 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 7 shows the luminance unevenness of the optical member when a conventional hologram element is used. (a3) of FIG. 7 shows the deflection angle and incident angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0052] (b1) of FIG. 7 shows the diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the X-axis direction. (b2) of FIG. 7 shows another diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the X-axis direction. (b3) of FIG. 7 shows the luminance uniformized by the optical member 30 when the hologram element 40 is used. (b4) of FIG. 7 shows the deflection angle and incident angle of the image light that repeats monotonic increase and monotonic decrease in the wave-shaped hologram element 40, and the amount of light emitted from the wave-shaped hologram element 40.

[0053] Note that in FIG. 7, a plurality of regions are arranged along the X-axis direction, but it is not limited thereto. The plurality of regions may be arranged not only along the X-axis direction but also along the Y-axis direction. That is, in the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle in the hologram element 40 may be changed along not only one direction but also two directions.

[0054] FIG. 8 is another diagram showing the diffraction efficiency of a conventional hologram element using a light guide plate, the deflection angle and incident angle of the image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when the hologram element 40 repeats monotonic increase and monotonic decrease, and the deflection angle and incident angle of the image light in the hologram element 40.

[0055] (a1) of FIG. 8 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 8 shows the luminance unevenness of the optical member when the conventional hologram element is used. (a3) of FIG. 8 shows the deflection angle and incident angle of the image light in the conventional hologram element, and the amount of light emitted from the conventional hologram element.

[0056] (b1) of FIG. 8 shows the diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the Y-axis direction. (b2) of FIG. 8 shows another diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the Y-axis direction. (b3) of FIG. 8 shows the luminance uniformized by the optical member 30 when the hologram element 40 is used. (b4) of FIG. 8 shows the deflection angle and incident angle of the image light that repeats monotonic increase and monotonic decrease in the wavy hologram element 40, and the amount of light emitted from the wavy hologram element 40.

[0057] In addition, in FIG. 8, a plurality of regions are arranged along the Y-axis direction, but it is not limited thereto. The plurality of regions may be arranged not only along the X-axis direction but also along the Y-axis direction. That is, in the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle in the hologram element 40 may be changed along not only one direction but also two directions.

[0058] FIG. 9 is a diagram showing the diffraction efficiency of a conventional hologram element using a light guide plate, the deflection angle and incident angle of the image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when the hologram element 40 having a plurality of high regions and low regions is used, and the deflection angle and incident angle of the image light in the hologram element 40.

[0059] (a1) of FIG. 9 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 9 shows the luminance unevenness of the optical member when the conventional hologram element is used. (a3) of FIG. 9 shows the deflection angle and incident angle of the image light in the conventional hologram element, and the amount of light emitted from the conventional hologram element.

[0060] (b1) of FIG. 9 shows the diffraction efficiency of the hologram element 40 in which a plurality of high regions and low regions are arranged in a matrix. (b2) of FIG. 9 shows the luminance uniformized by the optical member 30 when the hologram element 40 in which a plurality of high regions and low regions are arranged in a matrix is used. (b3) of FIG. 9 shows the deflection angle and incident angle of the image light in the hologram element 40 in which a plurality of high regions and low regions are arranged in a matrix, and the amount of light emitted from the hologram element 40 in which a plurality of high regions and low regions are arranged in a matrix.

[0061] In FIG. 9, in a plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle in the hologram element 40 may be changed not only in one direction but also along two directions. Further, the plurality of high regions and low regions arranged in a matrix shape may be non-linearly connected.

[0062] FIG. 10 is a diagram showing a display device 1a using a light guide unit 131 with non-uniform thickness. (a1) of FIG. 10 shows the light guide unit 131 with non-uniform thickness. (a2) of FIG. 10 shows the luminance unevenness caused by using the light guide unit 131 with non-uniform thickness. (a3) of FIG. 10 shows the luminance unevenness caused by the non-uniformity of the distribution in the image light emitted from the image light emitting unit 50. (b1) of FIG. 10 shows the deflection angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element. (b2) of FIG. 10 shows the deflection angle of the image light in the hologram element 40 included in the light guide unit 131 with non-uniform thickness and the amount of light emitted from the hologram element 40. In (b1) of FIG. 10, the amount of light guiding the light guide plate and in (b2) of FIG. 10, the amount of light guiding the light guide unit 131 are indicated by the thickness of the solid line.

[0063] As shown in (b1) to (b4) of FIG. 5, the hologram element 40 has a plurality of regions. The plurality of regions include a first region and a second region different from the first region. Further, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 is different between the first region and the second region along the X-axis direction or the Y-axis direction. And at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 is different between the first region and a third region different from the first region and the second region along the Y-axis direction or the X-axis direction. For example, the diffraction efficiency and the optimum incident angle with respect to the deflection angle of the image light may increase monotonically first from the first region toward the second region, and may increase monotonically second from the first region toward the third region. The first monotonic increase and the second monotonic increase may have the same or different increasing tendencies. The X-axis direction or the Y-axis direction is an example of a first direction. The Y-axis direction or the X-axis direction is an example of a second direction. The first direction is a direction different from the second direction, and in the present embodiment, it is an orthogonal direction.

[0064] Each of the plurality of regions is a cell that diffracts and emits image light. The size of the cell is on the order of several hundred μm.

[0065] Between the first region and the second region, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 is different so as to suppress luminance unevenness caused by non-uniformity of the surface of the light guide unit 31, non-uniformity of the thickness of the light guide unit 31, or non-uniformity of the distribution in the image light emitted from the image light emitting unit 50.

[0066] For example, when the surface of the light guide unit 31 is non-uniform, the hologram element 40 may be formed so as to suppress luminance unevenness caused by the non-uniformity of the surface of the light guide unit 31 and adjust at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40. The surface of the light guide unit 31 being non-uniform means that the surface roughness of the light guide unit 31 is non-uniform, or that irregularities are formed on the surface of the light guide unit 31. That is, in order to suppress luminance unevenness caused by the non-uniformity of the surface of the light guide unit 31, the hologram element 40 is formed with a plurality of regions for adjusting at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40.

[0067] For example, as shown in FIGS. 10(a1) and 10(a2), when the thickness of the light guide unit 131 is non-uniform, the hologram element 40 may be formed so as to suppress luminance unevenness caused by the non-uniformity of the thickness of the light guide unit 131 and adjust the deflection angle of the image light in the hologram element 40. The thickness of the light guide unit 131 being non-uniform means that the thickness of the light guide unit 131 gradually increases or decreases from one side to the other side of the light guide unit 131, or that the thickness of the central portion of the light guide unit 131 is thicker or thinner than the peripheral portion of the light guide unit 131. In FIG. 10(a1), an example is shown in which the thickness of the light guide unit 131 gradually increases from the incident hologram element 41 side and the return hologram element 42 side of the light guide unit 131 toward the exit hologram element 43. At this time, as shown in FIG. 10(b1), since the angle of the light propagating inside the light guide plate changes, the angle of incidence on the hologram element changes along the Y-axis direction, and the angle of the light diffracted at the deflection angle Θ also changes along the Y-axis direction when exiting the hologram element. On the other hand, as shown in FIG. 10(b2), when the deflection angle Θ of the hologram element 40 is changed to the deflection angle Ω in accordance with the angle of the light propagating inside the light guide unit 131, the angle of exit from the hologram element 40 can be made constant even if the angle of incidence on the hologram element 40 is different. That is, in order to suppress luminance unevenness caused by the non-uniformity of the thickness of the light guide unit 131, the hologram element 40 is formed with a plurality of regions for adjusting the deflection angle of the image light in the hologram element 40.

[0068] For example, as shown in (a1) to (a3) of FIG. 10, when the thickness of the light guide unit 131 is non-uniform and further the distribution of the image light emitted from the image light emitting unit 50 is non-uniform, taking into account the luminance unevenness caused by the non-uniformity of the thickness of the light guide unit 131, the hologram element 40 is formed so as to suppress the luminance unevenness caused by the non-uniformity of the distribution of the image light emitted from the image light emitting unit 50, and to adjust at least one of the diffraction efficiency of the hologram element 40 and the deflection angle of the image light in the hologram element 40. The non-uniformity of the distribution of the image light means, as shown in (a3) of FIG. 10, a case where the intensity distribution of the image light emitted from the emission surface of the image light emitting unit 50 is non-uniform. That is, in the hologram element 40, a plurality of regions are formed to adjust at least one of the diffraction efficiency of the hologram element 40 and the deflection angle of the image light in the hologram element 40 so as to suppress the luminance unevenness caused by the non-uniformity of the distribution of the image light emitted from the image light emitting unit 50. For example, a plurality of regions may be formed so that at least one of the diffraction efficiency of the hologram element 40 and the deflection angle of the image light in the hologram element 40 monotonically changes along the +Y axis direction.

[0069] Here, with reference to FIGS. 5 to 10, specific examples in the case where at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is different will be described.

[0070] First, as shown in (b1) to (b4) of FIG. 5, in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 monotonically changes from one side to the other side in the hologram element 40.

[0071] For example, as shown in (b2) and (b4) of FIG. 5, in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 linearly changes from one side to the other side in the hologram element 40. The linear change indicates a change in a straight line. Therefore, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 indicates a continuous change from one side to the other side in the hologram element 40.

[0072] For example, as shown in (a3) of FIG. 5, in a conventional hologram element, in the case of a curved shape, image light having an incident angle different from the incident angle at the time of two-beam exposure with laser light is incident, so that the angles of the diffracted image light are different from each other. For this reason, there are portions where the amount of image light diffracted by the conventional hologram element and emitted from the optical member 30 becomes small. Specifically, a high diffraction efficiency is obtained at the location A indicated by the two-dot chain line in (a3) of FIG. 5, but at the location B of the two-dot chain line, the diffraction efficiency is lower than that at the location A because the tangent plane of the conventional hologram element is inclined more than the horizontal plane. This is because, like the relationship between the angle α and the angle β shown by the conventional two-beam exposure with laser light (the relationship between the incident angle α by the reference light and the incident angle β by the object light), in the conventional hologram element, the same two-beam exposure with laser light is performed at any location, so that the angle formed by the tangent plane and the incident light is different from that at the location A, and it becomes difficult to obtain diffracted light efficiently. As a result, the image light emitted from the optical member cannot be made constant, and it becomes difficult to obtain desired image light.

[0073] Therefore, in (b4) of FIG. 5, different from the location D indicated by the two-dot chain line, by performing two-beam exposure with laser light in relation to the angles γ and δ suitable for the location E, it is possible to obtain a diffraction efficiency as high as that of the location D or adjust the deflection angle even at the location E. Specifically, by performing two-beam exposure with laser light in relation to the angles γ and δ suitable for the location E indicated by the two-dot chain line (the relationship between the incident angle γ by the reference light and the incident angle δ by the object light), it is possible to obtain a diffraction efficiency as high as that of the location D or adjust the deflection angle even at the location E. For example, as shown in (a3) of FIG. 5, for a portion where the amount of image light diffracted by a conventional hologram element and emitted from an optical member becomes small, in the present disclosure, as shown in (b4) of FIG. 5, by performing two-beam exposure of the output hologram element 43 with laser light so as to change the relationship between the incident angle and the exit angle with respect to the output hologram element 43, the image light emitted from the optical member 30 can be made constant. Here, the relational expression α + β = γ + δ holds among the angles α, β, γ, and δ.

[0074] In (a3) of FIG. 5, the tangent plane in contact with the conventional hologram element and in (b4) of FIG. 5, the tangent plane in contact with the hologram element 40 are indicated by a one-dot chain line. The tangent plane is also indicated by a one-dot chain line in the following figures.

[0075] For example, as shown in (b1) and (b4) of FIG. 5, in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 changes non-linearly from one side to the other side in the hologram element 40. Non-linear change means a change other than a linear change, and for example, shows a stepwise change, an exponential or logarithmic continuous arc-shaped change.

[0076] When changing in a stepped manner, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 may be constant. Specifically, in the case of the diffraction efficiency, in the hologram element 40, the diffraction efficiency of the hologram element 40 is constant for each region, and a plurality of regions may be formed so that the diffraction efficiency of the hologram element 40 changes stepwise from one side to the other in the hologram element 40. In the case of the optimum incident angle with respect to the deflection angle, in the hologram element 40, the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 is constant for each region, and a plurality of regions may be formed so that the optimum incident angle increases stepwise from one side to the other in the hologram element 40.

[0077] When changing in a continuous arc shape, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 may change continuously. Specifically, in the hologram element 40, a plurality of regions may be formed so that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 changes in a continuous arc shape from one side to the other in the hologram element 40.

[0078] As shown in (a1) to (a3) of FIG. 5, in an optical member using a conventional hologram element, since the diffraction efficiency and the optimum incident angle with respect to the deflection angle are the same at any location, when the incident angle of the image light with respect to the hologram element is different, the image light cannot be sufficiently diffracted, and a portion where the light amount of the image light emitted from the conventional hologram element decreases occurs, resulting in luminance unevenness. However, as shown in (b1) to (b4) of FIG. 5, in the optical member 30 using the hologram element 40 of the present disclosure, it is possible to suppress luminance unevenness caused by non-uniformity of the surface of the light-transmitting portion and non-uniformity of the thickness of the light-transmitting portion.

[0079] Next, as shown in FIGS. 6(b1) to 6(b4), in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 monotonically changes from the central portion to the edge in the hologram element 40.

[0080] For example, as shown in FIGS. 6(b1), 6(b2), and 6(b4), in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 nonlinearly changes from the central portion to the edge in the hologram element 40.

[0081] In the case of a stepwise change, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 may be constant. Specifically, in the case of the diffraction efficiency, in the hologram element 40, the diffraction efficiency of the hologram element 40 may be constant for each region, and a plurality of regions may be formed such that the diffraction efficiency of the hologram element 40 changes stepwise from the central portion to the edge in the hologram element 40. In the case of the optimum incident angle with respect to the deflection angle, in the hologram element 40, the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 may be constant for each region, and a plurality of regions may be formed such that the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 changes stepwise from the central portion to the edge in the hologram element 40.

[0082] In the case of a continuously arcuate change, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 may change continuously. Specifically, in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 changes in a continuously arcuate manner from the central portion to the edge in the hologram element 40.

[0083] For example, in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 linearly changes from the central portion to the edge in the hologram element 40.

[0084] Also in this case, in each of the plurality of regions, it is shown that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 continuously changes from the central portion to the edge in the hologram element 40.

[0085] As shown in (a1) to (a3) of FIG. 6, in an optical member using a conventional hologram element, since the diffraction efficiency and the optimum incident angle with respect to the deflection angle are the same at any location, when the incident angle of the image light with respect to the hologram element 40 is different, the image light cannot be sufficiently diffracted, and a portion where the amount of light of the image light emitted from the conventional hologram element decreases occurs, resulting in luminance unevenness. However, as shown in (b1) to (b4) of FIG. 6, in the optical member 30 using the hologram element 40 of the present disclosure, it is possible to suppress luminance unevenness caused by non-uniformity of the surface of the light-transmitting portion and non-uniformity of the thickness inside the light-transmitting portion.

[0086] Next, as shown in (b1) to (b4) of FIG. 7 and (b1) to (b4) of FIG. 8, in the hologram element 40, a plurality of regions may be formed such that at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 repeats monotonic increase and monotonic decrease in the hologram element 40.

[0087] As shown in (a1) to (a3) of FIG. 7 and (a1) to (a3) of FIG. 8, in an optical member using a conventional hologram element, since the optimum incident angle with respect to the diffraction efficiency and the deflection angle is the same at any location, if the incident angle of the image light with respect to the hologram element is different, the image light cannot be sufficiently diffracted, and a portion where the light amount of the image light emitted from the conventional hologram element decreases occurs, resulting in luminance unevenness. However, as shown in (b1) to (b4) of FIG. 7 and (b1) to (b4) of FIG. 8, in the optical member 30 using the hologram element 40 of the present disclosure, it is possible to suppress the luminance unevenness caused by the non-uniformity of the surface of the light-transmitting portion and the non-uniformity of the thickness of the light-transmitting portion.

[0088] Next, as shown in (b1) to (b3) of FIG. 9, the plurality of regions may include a plurality of high regions arranged in a matrix and regions other than the plurality of high regions, and at least one of a first condition that the diffraction efficiency is lower than the diffraction efficiency of the high regions and a second condition that the difference between the incident angle of the image light and the optimum incident angle in the hologram element 40 is larger than the difference in the high regions.

[0089] The shape of the plurality of high regions is not limited to a frustum of a pyramid as shown in FIG. 9. The shape of the plurality of high regions may be a frustum of a cone, a rectangular parallelepiped, a polygonal prism, a cylinder, or the like. Therefore, the shape of the plurality of low regions is also not limited.

[0090] As shown in (a1) to (a3) of FIG. 9, in an optical member using a conventional hologram element, since the optimum incident angle with respect to the diffraction efficiency and the deflection angle is the same at any location, if the incident angle of the image light with respect to the hologram element is different, the image light cannot be sufficiently diffracted, and a portion where the light amount of the image light emitted from the conventional hologram element decreases occurs, resulting in luminance unevenness. However, as shown in (b1) to (b3) of FIG. 9, in the optical member 30 using the hologram element 40 of the present disclosure, it is possible to suppress the luminance unevenness caused by the non-uniformity of the surface of the light-transmitting portion and the non-uniformity of the thickness of the light-transmitting portion.

[0091] Next, even when luminance unevenness occurs as a result of a combination of luminance unevenness caused by non-uniformity in the distribution of image light emitted by the image light emitting unit 50 as shown in (a3) of FIG. 10 and luminance unevenness caused by using the light guide unit 131 with non-uniform thickness as shown in (a2) of FIG. 10, in the optical member 30 using the hologram element 40 of the present disclosure, by adjusting at least one of the diffraction efficiency and the deflection angle of the image light, it is possible to suppress the non-uniformity in the distribution of the image light emitted by the image light emitting unit 50 and the luminance unevenness caused by the non-uniformity in the thickness of the light guide unit 131.

[0092] <Modification example> First, referring to FIG. 11, the optical member 30a of this modification example will be described.

[0093] FIG. 11 is a diagram showing a display device 1b using a combiner 130. In FIG. 11, as an example of the light transmissive part, the case where the light transmissive part is a combiner 130 is illustrated.

[0094] In this modification example, it is different from the above-described embodiment in that a combiner 130 is used instead of the above-described light guide unit. In this modification example, for the same configurations as those in the above-described embodiment, the same reference numerals are given and the description is appropriately omitted.

[0095] The display device 1b of this modification example includes a device main body 110, an image light emitting unit 50 disposed in the device main body 110, a reflector 60, and an optical member 30a. The optical member 30a includes a combiner 130 and a hologram element 40.

[0096] The device main body 110 is disposed and fixed on the dashboard of the vehicle 2.

[0097] The image light emitting unit 50 emits image light toward the reflector 60.

[0098] The reflector 60 is a reflection mirror that reflects the image light emitted by the image light emitting unit 50 toward the combiner 130. That is, the image light emitted by the image light emitting unit 50 enters and is reflected by the reflector 60 and then enters the combiner 130.

[0099] The combiner 130 is composed of a half mirror such as a transparent resin material. The hologram element 40 is provided on the combiner 130. The hologram element 40 may be provided on the emission surface 131b of the combiner 130 or on the opposite surface 131c, or may be included in the combiner 130.

[0100] The emission surface 131b of the combiner 130 is the surface facing the user and displays an image. The emission surface 131b can display a virtual image when the image light reflected by the reflector 60 is projected. That is, the combiner 130 can display a virtual image corresponding to the image when the image light is reflected and diffracted by the hologram element 40. Also, the surface 131c opposite to the emission surface 131b of the combiner 130 is the surface facing the front window 3 in FIG. 1, and light including the scenery enters from the front through the front window 3. For this reason, the combiner 130 is formed so that the user can visually see the traveling direction of the vehicle 2 through the combiner 130. That is, the user can superimpose and view the image of the combiner 130 on the forward scenery visible through the front window 3 in the traveling direction of the vehicle 2 in FIG. 1.

[0101] The combiner 130 is a convex plate or a concave plate. For example, the emission surface 131b of the combiner 130 is a curved surface. The combiner 130 is substantially rectangular in plan view, but the shape is not particularly limited and may be polygonal, circular, or the like.

[0102] Next, with reference to FIGS. 12 to 16, the specific configuration of the hologram element 40 will be described.

[0103] FIG. 12 is a diagram showing the diffraction efficiency of a conventional hologram element using a combiner, the deflection angle and incident angle of image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonically increasing from one side to the other in the hologram element 40, and the deflection angle and incident angle of image light in the hologram element 40. In FIG. 12, the illustration of the hologram element 40 is omitted. The same applies to the subsequent figures.

[0104] (a1) of FIG. 12 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 12 shows the luminance unevenness of the optical member when using a conventional hologram element. (a3) of FIG. 12 shows the deflection angle and incident angle of image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0105] (b1) of FIG. 12 shows the non-linearly increasing diffraction efficiency of the hologram element 40. (b2) of FIG. 12 shows the linearly increasing diffraction efficiency of the hologram element 40. (b3) of FIG. 12 shows the luminance uniformized by the optical member 30 when using the hologram element 40. (b4) of FIG. 12 shows the monotonically increasing deflection angle and incident angle of image light in the curved hologram element 40 and the amount of light emitted from the curved hologram element 40. The amount of light is indicated by the length of the arrow.

[0106] In FIG. 12, since it is the same as the description of FIG. 5 above, the description of FIG. 12 is omitted.

[0107] FIG. 13 is a diagram showing the diffraction efficiency of a conventional hologram element using a combiner, the deflection angle and incident angle of image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonically increasing from the central portion to the edge in the hologram element 40, and the deflection angle and incident angle of image light in the hologram element 40.

[0108] (a1) of FIG. 13 shows the diffraction efficiency of a conventional hologram element in which the area of the present disclosure is not formed. (a2) of FIG. 13 shows the luminance unevenness of the optical member when a conventional hologram element is used. (a3) of FIG. 13 shows the deflection angle and incident angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0109] (b1) of FIG. 13 shows the non-linearly increasing diffraction efficiency of the hologram element 40. (b2) of FIG. 13 shows the monotonically increasing diffraction efficiency of the hologram element 40. (b3) of FIG. 13 shows the luminance uniformized by the optical member 30 when the hologram element 40 is used. (b4) of FIG. 13 shows the monotonically increasing deflection angle and incident angle of the image light in the curved hologram element 40 and the amount of light emitted from the curved hologram element 40.

[0110] In FIG. 13, since it is the same as the description of FIG. 6 above, the description of FIG. 13 is omitted.

[0111] FIG. 14 is a diagram showing the diffraction efficiency of a conventional hologram element using a combiner, the deflection angle and incident angle of the image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonically increasing and decreasing are repeated in the hologram element 40, and the deflection angle and incident angle of the image light in the hologram element 40.

[0112] (a1) of FIG. 14 shows the diffraction efficiency of a conventional hologram element in which the area of the present disclosure is not formed. (a2) of FIG. 14 shows the luminance unevenness of the optical member when a conventional hologram element is used. (a3) of FIG. 14 shows the deflection angle and incident angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0113] (b1) of FIG. 14 shows the diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the X-axis direction. (b2) of FIG. 14 shows another diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the X-axis direction. (b3) of FIG. 14 shows the luminance equalized by the optical member 30 when the hologram element 40 is used. (b4) of FIG. 14 shows the deflection angle and incident angle of the image light that repeats monotonic increase and monotonic decrease in the wave-shaped hologram element 40, and the amount of light emitted from the wave-shaped hologram element 40.

[0114] In FIG. 14, since it is the same as the description of FIG. 7 above, the description of FIG. 14 is omitted.

[0115] FIG. 15 is another diagram showing the diffraction efficiency of a conventional hologram element using a combiner, the deflection angle and incident angle of the image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when monotonic increase and monotonic decrease are repeated in the hologram element 40, and the deflection angle and incident angle of the image light in the hologram element 40.

[0116] (a1) of FIG. 15 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 15 shows the luminance unevenness of the optical member when the conventional hologram element is used. (a3) of FIG. 15 shows the deflection angle and incident angle of the image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0117] (b1) of FIG. 15 shows the diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the Y-axis direction. (b2) of FIG. 15 shows another diffraction efficiency of the hologram element 40 that repeats monotonic increase and monotonic decrease along the Y-axis direction. (b3) of FIG. 15 shows the luminance equalized by the optical member 30 when the hologram element 40 is used. (b4) of FIG. 15 shows the deflection angle and incident angle of the image light that repeats monotonic increase and monotonic decrease in the wave-shaped hologram element 40, and the amount of light emitted from the wave-shaped hologram element 40.

[0118] In FIG. 15, since it is the same as the description of FIG. 8 above, the description of FIG. 15 is omitted.

[0119] FIG. 16 is a diagram showing the diffraction efficiency of a conventional hologram element using a combiner, the deflection angle and incident angle of image light of the conventional hologram element, the diffraction efficiency of the hologram element 40 when using a hologram element 40 having a plurality of high regions and low regions, and the deflection angle and incident angle of image light in the hologram element 40.

[0120] (a1) of FIG. 16 shows the diffraction efficiency of a conventional hologram element in which the region of the present disclosure is not formed. (a2) of FIG. 16 shows the luminance unevenness of the optical member when using a conventional hologram element. (a3) of FIG. 16 shows the deflection angle and incident angle of image light in the conventional hologram element and the amount of light emitted from the conventional hologram element.

[0121] (b1) of FIG. 16 shows the diffraction efficiency of the hologram element 40 in which a plurality of high regions and low regions are formed in a matrix. (b2) of FIG. 16 shows the luminance uniformized by the optical member 30 when using the hologram element 40 in which a plurality of high regions and low regions are formed in a matrix. (b3) of FIG. 16 shows the deflection angle and incident angle of image light in the hologram element 40 in which a plurality of high regions and low regions are formed in a matrix and the amount of light emitted from the hologram element 40 in which a plurality of high regions and low regions are formed in a matrix.

[0122] In FIG. 16, since it is the same as the description of FIG. 9 above, the description of FIG. 16 is omitted.

[0123] <Manufacturing method> Next, with reference to FIG. 17, a manufacturing method of the optical members 30 and 30a will be described.

[0124] FIG. 17 is a flowchart showing a manufacturing method of the optical members 30 and 30a.

[0125] The manufacturing method of the optical members 30 and 30a is a manufacturing method for producing the optical members 30 and 30a having a hologram element 40 that diffracts and emits image light indicating an image generated by the image light emitting unit 50 and a light transmitting portion provided with the hologram element 40.

[0126] First, as an attaching step, a photosensitive material to be the hologram element 40 is laminated on the surface of a base material serving as an element of the light transmitting portion (S11).

[0127] Next, as an exposure step, a laser beam is irradiated onto the photosensitive material using a laser device, thereby performing two-beam interference exposure on the photosensitive material with the laser beam (S12). The diffraction efficiency is set by adjusting the intensity (output) of the laser beam. The deflection angle is set by adjusting the incident angle of the laser beam. For example, as shown in (b4) of FIG. 5, the optimum incident angle with respect to the deflection angle is set by changing the angle of incidence on the hologram element 40 while keeping the deflection angle constant. In the photosensitive material, at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle with respect to the deflection angle is set for each of a plurality of regions including a first region and a second region different from the first region. Thereby, the hologram element 40 in which a plurality of desired regions are formed is formed.

[0128] Next, as a fixing step, the photosensitive material is fixed to the base material by irradiating the photosensitive material with ultraviolet rays (S13).

[0129] In this way, a light transmitting portion provided with the hologram element 40 can be obtained.

[0130] <Operational Effects> Hereinafter, the operational effects of the optical members 30 and 30a, the display devices 1, 1a, and 1b, and the manufacturing method in the present embodiment will be described.

[0131] As described above, the optical members 30 and 30a of Technology 1 in the present embodiment include a hologram element 40 that diffracts and emits image light indicating an image generated by the image light emitting unit 50, and a light-transmitting unit (light guide units 31, combiner 130) where the hologram element 40 is provided. Further, the hologram element 40 has a plurality of regions including a first region and a second region that is a region different from the first region. Then, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is different between the first region and the second region so as to suppress luminance unevenness caused by unevenness on the surface of the light-transmitting unit, unevenness in the thickness of the light-transmitting unit, or unevenness in the distribution in the image light emitted by the image light emitting unit 50.

[0132] According to this, even if the surface of the light-transmitting unit is uneven, the thickness of the light-transmitting unit is uneven, or the distribution in the image light is uneven, the first region and the second region corresponding to the unevenness are formed in the hologram element 40 so as to suppress the unevenness caused thereby. For this reason, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0133] Therefore, according to the optical members 30 and 30a, it is possible to emit image light with a uniform distribution.

[0134] Further, the optical members 30 and 30a of Technology 2 in the present embodiment are the optical members 30 and 30a described in Technology 1. In this case, in the hologram element 40, a plurality of regions are formed such that at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle monotonically changes from one side to the other side in the hologram element 40.

[0135] According to this, for example, when there is luminance unevenness due to non-uniformity and the luminance monotonically increases from the other side to one side of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed such that the luminance monotonically increases from one side to the other side, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0136] Also, the optical members 30 and 30a of Technology 3 in the present embodiment are the optical members 30 and 30a described in Technology 2. In this case, in the hologram element 40, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is formed with a plurality of regions so as to linearly change from one side to the other side in the hologram element 40.

[0137] According to this, for example, when there is luminance unevenness due to non-uniformity and the luminance linearly increases from the other side to one side of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed such that the luminance linearly increases from one side to the other side, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0138] Also, the optical members 30 and 30a of Technology 4 in the present embodiment are the optical members 30 and 30a described in Technology 2. In this case, in the hologram element 40, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is formed with a plurality of regions so as to non-linearly change from one side to the other side in the hologram element 40.

[0139] According to this, for example, when there is luminance unevenness due to non-uniformity and the luminance non-linearly increases from the other side to one side of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed such that the luminance non-linearly increases from one side to the other side, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0140] In addition, the optical members 30 and 30a of Technology 5 in the present embodiment are the optical members 30 and 30a described in Technology 1. In this case, in the hologram element 40, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is formed with a plurality of regions so as to change monotonically from the central portion to the edge in the hologram element 40.

[0141] According to this, for example, when the luminance unevenness caused by non-uniformity increases monotonically in luminance from the edge to the central portion of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed so that the luminance increases monotonically from the central portion to the edge, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0142] In addition, the optical members 30 and 30a of Technology 6 in the present embodiment are the optical members 30 and 30a described in Technology 5. In this case, in the hologram element 40, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is formed with a plurality of regions so as to change linearly from the central portion to the edge in the hologram element 40.

[0143] According to this, for example, when the luminance unevenness caused by non-uniformity increases linearly in luminance from the edge to the central portion of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed so that the luminance increases linearly from the central portion to the edge of the optical members 30 and 30a, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0144] Further, the optical members 30 and 30a of Technology 7 in the present embodiment are the optical members 30 and 30a described in Technology 5. In this case, in the hologram element 40, a plurality of regions are formed such that at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle changes non-linearly from the central portion to the edge of the hologram element 40.

[0145] According to this, for example, when the luminance unevenness caused by non-uniformity increases non-linearly from the edge to the central portion of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed so as to increase non-linearly from the central portion to the edge of the optical members 30 and 30a, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0146] Further, the optical members 30 and 30a of Technology 8 in the present embodiment are the optical members 30 and 30a described in any one of Technologies 1, 2, 4, 5, and 7. In this case, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is constant.

[0147] According to this, according to the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b, it is possible to set the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 for each region. By using such a hologram element 40, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0148] Further, the optical members 30 and 30a of Technology 9 in the present embodiment are the optical members 30 and 30a described in any one of Technologies 1 to 7. In this case, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle changes continuously.

[0149] According to this, the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 can be set for each region according to the gradient of the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b. By using such a hologram element 40, the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b can be suppressed.

[0150] In addition, the optical members 30 and 30a of the technique 10 in the present embodiment are the optical members 30 and 30a described in the technique 1. In this case, in the hologram element 40, at least one of the diffraction efficiency of the hologram element 40 and the optimum incident angle with respect to the deflection angle of the image light in the hologram element 40 has a plurality of regions formed so as to repeat monotonic increase and monotonic decrease in the hologram element 40.

[0151] According to this, for example, when the luminance changes such that the luminance unevenness caused by non-uniformity repeats monotonic increase and monotonic decrease from the other side to one side of the optical members 30 and 30a, by using the hologram element 40 in which a plurality of regions are formed so as to repeat monotonic increase and monotonic decrease from one side to the other side, the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b can be suppressed.

[0152] In addition, the optical members 30 and 30a of the technique 11 in the present embodiment are the optical members 30 and 30a described in the technique 1. In this case, it includes a plurality of high regions arranged in a matrix, a first condition that the diffraction efficiency is lower than that of the high regions, and a low region that satisfies at least one of a second condition that the difference between the incident angle and the optimum incident angle of the image light in the hologram element 40 is larger than the difference in the high regions.

[0153] According to this, for example, when the luminance unevenness of the optical members 30 and 30a caused by non-uniformity is formed in a matrix shape, by using the hologram element 40 formed by a plurality of high regions arranged in a matrix and low regions other than the high regions, the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b can be suppressed.

[0154] In addition, the optical member 30 of Technique 12 in the present embodiment is the optical member 30 described in any one of Techniques 1 to 11. In this case, the light-transmitting portion is a light guide portion 31, 131 that propagates image light and includes a plurality of hologram elements 40. Further, the plurality of hologram elements 40 includes a first hologram element and a second hologram element. Further, the first hologram element is located on the light incident side of the light guide portion 31, 131 where the image light emitted from the image light emitting portion 50 is incident, rather than the second hologram element.

[0155] According to this, it is possible to suppress unevenness in the luminance of the image light emitted from the display devices 1, 1a, 1b including the first hologram element and the second hologram element.

[0156] In addition, the optical member 30 of Technique 13 in the present embodiment is the optical member 30 described in Technique 12. In this case, when the thickness of the light guide portion 31, 131 is non-uniform, the hologram element 40 is formed so as to suppress unevenness in luminance caused by the non-uniformity of the thickness of the light guide portion 31, 131 and adjust the deflection angle of the image light in the hologram element 40.

[0157] According to this, for example, when unevenness in luminance occurs due to non-uniformity of the thickness of the light guide portion 31, 131, it is possible to adjust the deflection angle of the image light in the hologram element 40 according to the non-uniformity of the thickness of the light guide portion 31, 131. Therefore, it is possible to suppress unevenness in the luminance of the image light emitted from the display devices 1, 1a, 1b.

[0158] In addition, the optical members 30, 30a of Technique 14 in the present embodiment are the optical members 30, 30a described in any one of Techniques 1 to 13. In this case, when the surface of the light-transmitting portion is non-uniform, the hologram element 40 is formed so as to suppress unevenness in luminance caused by the non-uniformity of the surface of the light-transmitting portion and adjust at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle.

[0159] According to this, for example, when luminance unevenness occurs due to the surface of the light-transmitting portion, by using the adjusted hologram element 40, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0160] Further, the optical members 30 and 30a of Technique 15 in the present embodiment are the optical members 30 and 30a described in any one of Techniques 1 to 14. In this case, when the distribution of the image light emitted from the image light emitting unit 50 is non-uniform, the luminance unevenness caused by the non-uniformity of the distribution of the image light emitted from the image light emitting unit 50 is suppressed, and the hologram element 40 is formed so as to adjust at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle.

[0161] According to this, even when the distribution of the image light emitted from the image light emitting unit 50 is non-uniform, by using the adjusted hologram element 40, it is possible to suppress the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0162] Further, the optical members 30 and 30a of Technique 16 in the present embodiment are the optical members 30 and 30a described in any one of Techniques 1 to 15. In this case, the plurality of regions further include a third region. Also, between the first region and the second region, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is different along the first direction (X-axis direction or Y-axis direction). And between the first region and the third region, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is different along the second direction (Y-axis direction or X-axis direction) different from the first direction.

[0163] According to this, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle can be varied not only in the first direction but also in the second direction. For this reason, even if there are non-uniformities in the surface of the light-transmitting portion, non-uniformities in the thickness of the light-transmitting portion, or non-uniformities in the distribution of the image light emitted from the image light emitting portion 50, the diffraction efficiency, the deflection angle of the image light, and the optimum incident angle with respect to the deflection angle can be set so as to correspond to these non-uniformities. As a result, unevenness in the luminance of the image light emitted from the display devices 1, 1a, and 1b can be suppressed.

[0164] Further, the optical members 30, 30a of Technique 17 in the present embodiment are the optical members 30, 30a described in any one of Techniques 1 to 11 and 14 to 16. In this case, the light-transmitting portion is a combiner 130 that includes a plurality of hologram elements 40.

[0165] According to this, the optical members 30, 30a of the present disclosure can also be applied to the combiner 130.

[0166] Further, the optical members 30, 30a of Technique 18 in the present embodiment are the optical members 30, 30a described in any one of Techniques 1 to 17. In this case, each of the plurality of regions is a cell that diffracts and emits image light.

[0167] According to this, at least one of the diffraction efficiency, the deflection angle of the image light, and the optimum incident angle with respect to the deflection angle can be adjusted for each cell according to the luminance unevenness of the optical members 30, 30a caused by the non-uniformities. By using such hologram elements 40, unevenness in the luminance of the image light emitted from the display devices 1, 1a, and 1b can be suppressed.

[0168] Further, the display devices 1, 1a, and 1b of Technique 19 in the present embodiment include the optical members 30, 30a described in any one of Techniques 1 to 18 and an image light emitting portion 50 that emits image light to the light-transmitting portion.

[0169] Also in these display devices 1, 1a, and 1b, the same operational effects as described above are achieved.

[0170] Further, the manufacturing method of Technology 20 in the present embodiment is a manufacturing method for producing optical members 30, 30a having a hologram element 40 that diffracts and emits image light indicating an image generated by the image light emitting unit 50 and a light transmissive portion where the hologram element 40 is provided. In the hologram element 40, it includes forming a plurality of regions including a first region and a second region that is a region different from the first region, and at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle is different between the first region and the second region so as to suppress luminance unevenness caused by unevenness on the surface of the light transmissive portion, unevenness in the thickness of the light transmissive portion, or unevenness in the distribution in the image light emitted by the image light emitting unit 50.

[0171] Also in this manufacturing method, the same operational effects as described above are achieved.

[0172] Further, the manufacturing method of Technology 21 in the present embodiment is the manufacturing method described in Technology 20. In this case, in each of the plurality of regions, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle continuously changes.

[0173] According to this, it is possible to obtain a hologram element 40 in which the diffraction efficiency, the deflection angle of the image light, and the optimum incident angle with respect to the deflection angle are adjusted for each region according to the gradient of the luminance unevenness of the image light emitted from the display devices 1, 1a, and 1b.

[0174] Further, the manufacturing method of Technology 22 in the present embodiment is the manufacturing method described in Technology 20 or 21. In this case, each of the plurality of regions is a cell that diffracts and emits image light.

[0175] According to this, a hologram element 40 can be obtained in which at least one of the diffraction efficiency, the deflection angle of the image light, and the optimum incident angle with respect to the deflection angle is adjusted for each cell according to the luminance unevenness of the optical members 30 and 30a due to unevenness.

[0176] (Other modifications) As described above, the optical member, the display device, and the manufacturing method according to the present disclosure have been described based on the above embodiments. However, the present disclosure is not limited to these embodiments. As long as the gist of the present disclosure is not deviated from, various modifications conceived by those skilled in the art applied to the embodiments may also be included within the scope of the present disclosure.

[0177] For example, in the above embodiment, at least one of the diffraction efficiency of the hologram element 40, the deflection angle of the image light in the hologram element 40, and the optimum incident angle with respect to the deflection angle may change monotonically from the central portion to the edge in the hologram element 40. In this case, it is shown in (b1), (b2), (b4) of FIG. 6, and (b1), (b2), (b4) of FIG. 13.

[0178] Further, in the above embodiment, the plurality of regions include a plurality of low regions arranged in a matrix and regions other than the plurality of low regions, and a third condition that the diffraction efficiency is higher than the diffraction efficiency of the low regions, and a fourth condition that the difference between the incident angle of the image light and the optimum incident angle in the hologram element is smaller than the difference in the low regions. It may include a high region that satisfies at least one of them. In this case, it is shown by the inversion symmetry of (b1), (b3) of FIG. 9 and (b1), (b3) of FIG. 16.

[0179] Also, in the above-described embodiment, at least one of the diffraction efficiency of the incident hologram element 41, the deflection angle of the image light in the incident hologram element 41, and the optimum incident angle with respect to the deflection angle may change monotonically as it approaches the edge portion from the central portion of the incident hologram element 41. For example, the diffraction efficiency of the incident hologram element 41 may increase monotonically as it approaches the edge portion from the central portion of the incident hologram element 41. Further, the difference between the incident angle of the image light in the incident hologram element 41 and the optimum incident angle with respect to the deflection angle may decrease monotonically as it approaches the edge portion from the central portion of the incident hologram element 41. This is because the luminance distribution of the image light emitted from the image light emission unit 50 tends to decrease as it approaches the edge from the central portion.

[0180] Also, in the above-described embodiment, in the output hologram element 43, at least one of the diffraction efficiency, the deflection angle of the image light, and the optimum incident angle with respect to the deflection angle may be adjusted so as to increase as it moves away from the reflection hologram element 42. Further, in the reflection hologram element 42, at least one of the diffraction efficiency, the deflection angle of the image light, and the optimum incident angle with respect to the deflection angle may be adjusted so as to increase as it moves away from the incident hologram element 41. For example, the diffraction efficiency of the output hologram element 43 may be gradually increased as it moves away from the reflection hologram element 42. Further, the difference between the incident angle of the image light in the output hologram element 43 and the optimum incident angle with respect to the deflection angle may be gradually decreased as it moves away from the reflection hologram element 42. Also, the diffraction efficiency of the reflection hologram element 42 may be gradually increased as it moves away from the incident hologram element 41. Further, the difference between the incident angle of the image light in the reflection hologram element 42 and the optimum incident angle with respect to the deflection angle may be gradually decreased as it moves away from the incident hologram element 41. This is because the luminance of the image light emitted from the output hologram element 43 tends to decrease as it moves away from the upstream reflection hologram element 42, and the luminance of the image light emitted from the reflection hologram element 42 tends to decrease as it moves away from the upstream incident hologram element 41.

[0181] Furthermore, in the above embodiment, if the light of the two beams of light is non-uniform during exposure despite a constant diffraction efficiency value being set during exposure, then taking into account the case of non-uniformity due to the material characteristics of hologram element 40, at least one of the diffraction efficiency of hologram element 40, the deflection angle of the image light in hologram element 40, and the optimal incident angle for the deflection angle may be adjusted to suppress uneven brightness of the image light emitted from display devices 1, 1a, 1b.

[0182] Furthermore, in the above embodiment, an example has been given in which hologram element 40 is a reflection hologram that reflects and diffracts light, but hologram element 40 may be configured as a transmission hologram that transmits and diffracts light.

[0183] In addition, the present disclosure also includes forms obtained by applying various modifications to the above-described embodiments that a person skilled in the art may conceive, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the spirit of the present disclosure. [Industrial Applicability]

[0184] The present disclosure can be used in display devices such as head-up display devices for vehicles. [Explanation of symbols]

[0185] 1, 1a, 1b display device 30, 30a Optical member 31, 131 Light guiding part (transparent part) 40 Hologram element 41 Incident hologram element (first hologram element) 42 Folded hologram element (first hologram element or second hologram element) 43 Output hologram element (second hologram element) 50 Image light emitting section 130 Combiner (translucent part)

Claims

1. A hologram element that diffracts and emits image light showing an image generated by an image light emitting unit, and a light-transmitting portion provided with the hologram element, wherein the hologram element has a plurality of regions including a first region and a second region that is a region different from the first region, at least one of the diffraction efficiency of the hologram element, the deflection angle of the image light in the hologram element, and the optimum incident angle with respect to the deflection angle is different between the first region and the second region so as to suppress luminance unevenness caused by unevenness on the surface of the light-transmitting portion, unevenness in the thickness of the light-transmitting portion, or unevenness in the distribution of the image light emitted by the image light emitting unit Optical member.

2. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle monotonically changes from one side to the other side in the hologram element The optical member according to claim 1.

3. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle linearly changes from one side to the other side in the hologram element The optical member according to claim 2.

4. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle non-linearly changes from one side to the other side in the hologram element The optical member according to claim 2.

5. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle monotonically changes from the central portion to the edge in the hologram element The optical member according to claim 1.

6. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle linearly changes from the central portion to the edge in the hologram element The optical member according to claim 5.

7. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle non-linearly changes from the central portion to the edge in the hologram element The optical member according to claim 5.

8. In each of the plurality of the regions, at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle is constant The optical member according to any one of claims 1, 2, 4, 5, and 7.

9. In each of the plurality of the regions, at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle continuously changes The optical member according to any one of claims 1 to 7.

10. In the hologram element, a plurality of the regions are formed such that at least one of the diffraction efficiency and the optimum incident angle monotonically increases and monotonically decreases repeatedly in the hologram element The optical member according to claim 1.

11. The plurality of the regions are a plurality of high regions arranged in a matrix, and regions other than the plurality of the high regions, including low regions satisfying at least one of a first condition that the diffraction efficiency is lower than that of the high regions and a second condition that a difference between an incident angle of the image light in the hologram element and the optimum incident angle is larger than that in the high regions The optical member according to claim 1.

12. The light-transmitting part is a light guide part that propagates image light and includes a plurality of the hologram elements, the plurality of the hologram elements include a first hologram element and a second hologram element, and the first hologram element is located closer to a light incident side of the light guide part where the image light emitted from the image light emitting part is incident than the second hologram element The optical member according to any one of claims 1 to 7.

13. When the thickness of the light guide part is non-uniform, the hologram element is formed so as to suppress luminance unevenness caused by the non-uniformity of the thickness of the light guide part and adjust the deflection angle of the image light in the hologram element The optical member according to claim 12.

14. When the surface of the light-transmitting part is non-uniform, the hologram element is formed so as to suppress luminance unevenness caused by the non-uniformity of the surface of the light-transmitting part and adjust at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle The optical member according to any one of claims 1 to 7.

15. When the distribution of the image light emitted from the image light emitting part is non-uniform, the hologram element is formed so as to suppress luminance unevenness caused by the non-uniformity of the distribution of the image light emitted from the image light emitting part and adjust at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle The optical member according to any one of claims 1 to 7.

16. The plurality of regions further include a third region, in the first region and the second region, at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle is different along the first direction, in the first region and the third region, at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle is different along a second direction different from the first direction The optical member according to any one of claims 1 to 7.

17. The light-transmitting part is a combiner that includes a plurality of the hologram elements The optical member according to any one of claims 1 to 7.

18. Each of the plurality of regions is a cell that diffracts and emits image light The optical member according to any one of claims 1 to 7.

19. An optical member according to any one of claims 1 to 7, and an image light emitting unit that emits image light to the light-transmitting part, A display device.

20. A manufacturing method for manufacturing an optical member having a hologram element that diffracts and emits image light indicating an image generated by an image light emitting unit and a light-transmitting part provided with the hologram element, including forming, in the hologram element, a plurality of regions including a first region and a second region that is a region different from the first region, at least one of the diffraction efficiency of the hologram element, the deflection angle of the image light in the hologram element, and the optimum incident angle with respect to the deflection angle is different between the first region and the second region so as to suppress luminance unevenness caused by unevenness on the surface of the light-transmitting part, unevenness in the thickness of the light-transmitting part, or unevenness in the distribution in the image light emitted by the image light emitting unit Manufacturing method.

21. In each of the plurality of regions, at least one of the diffraction efficiency, the deflection angle, and the optimum incident angle continuously changes The manufacturing method according to claim 20.

22. Each of the plurality of regions is a cell that diffracts and emits image light The manufacturing method according to claim 20 or 21.

Images