Display device

Abstract

To provide a display device capable of suppressing the decrease of usage efficiency of light representing an image emitted from an output hologram element.SOLUTION: A display device 1 is a display device 1 that projects an image onto a curved display medium (front window 3) provided on a moving body (vehicle 2) to display a virtual image. The display device includes: an image generation unit 20 that generates light representing an image (image light); and a light guide 30 that has a first hologram element with a non-rectangular square shape (output hologram element 43). The first hologram element emits light representing an image that propagates inside the light guide 30.SELECTED DRAWING: Figure 4A

Description

[Technical Field]

[0001] The present disclosure relates to a display device. [Background technology]

[0002] Patent Document 1 discloses a conventional device for generating a virtual image, which includes an image generating unit that generates an image, an optical unit that projects the image toward a curved windshield to generate a virtual image, and an optical guide having a rectangular output hologram. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Special Publication No. 2021-528681 Summary of the Invention [Problem to be solved by the invention]

[0004] When the virtual image generating device of Patent Document 1 is used as a HUD (Head-Up Display), light representing an image emitted from an emission hologram is projected onto the windshield, but because the windshield has a curved surface, it is preferable to shape the emission hologram in a shape that matches the curved surface of the windshield.However, the light representing an image emitted from the rectangular emission hologram of the virtual image generating device of Patent Document 1 generates light representing an image that is not actually used, which poses a problem of reduced light utilization efficiency.

[0005] Therefore, an object of the present disclosure is to provide a display device that can suppress a decrease in the utilization efficiency of light that represents an image emitted from an emission hologram element. [Means for solving the problem]

[0006] A display device according to one aspect of the present disclosure is a display device that displays a virtual image by projecting an image onto a curved display medium provided on a moving body, and includes an image generating device that generates light representing the image, and a light guide body having a first hologram element having a non-rectangular quadrangular shape, and the first hologram element emits the light representing the image propagating inside the light guide body toward the display medium. The first hologram element emits light representing the non-rectangular quadrangular image toward the display medium of the moving body, and the display medium reflects the incident non-rectangular quadrangular light by distorting its shape into light representing the rectangular image. . [Effects of the Invention]

[0007] According to the display device of the present disclosure, it is possible to suppress a decrease in the efficiency of use of light representing an image emitted from an emission hologram element. [Brief explanation of the drawings]

[0008] [Figure 1A] FIG. 1A is a schematic diagram showing an example of a vehicle in which a display device according to an embodiment is installed. [Figure 1B] FIG. 1B is a schematic diagram showing the display device and the vehicle according to the embodiment as viewed from the right. [Figure 2] FIG. 2 is a diagram showing the display device according to the embodiment as viewed from the right. [Figure 3A] FIG. 3A is a perspective view showing a display device according to an embodiment. [Figure 3B] FIG. 3B is a diagram showing the correspondence between the left-right direction and the X-axis direction, the front-rear direction and the Y-axis direction, and the up-down direction and the Z-axis direction. [Figure 4A] FIG. 4A is a diagram showing a display device. [Figure 4B] FIG. 4B is a diagram showing a third hologram element according to an embodiment of the present invention, which is different from the rectangular hologram element. [Figure 4C] FIG. 4C is a diagram showing the shape and path of image light emitted from the display device. [Figure 5] FIG. 5 is a schematic diagram showing a rotating display device according to the first modification of the embodiment and a vehicle when viewed in a forward direction. [Figure 6]FIG. 6 is a schematic diagram showing a rotating light guide according to the first modification of the embodiment and a vehicle as viewed in a forward direction. [Figure 7] FIG. 7 is a schematic diagram showing the attitude of the rotated display device. [Figure 8] FIG. 8 is a plan view showing a light guide of a display device according to a second modification of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

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

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

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

[0012] Furthermore, in the following embodiments, expressions such as "approximately parallel" or "rectangular" are used. For example, "approximately parallel" or "rectangular" not only means that the shape is completely parallel or rectangular, but also means that the shape is substantially parallel or rectangular, i.e., includes an error of a few percent. Furthermore, "approximately parallel" or "rectangular" means that the shape is parallel or rectangular within the range in which the effects of the present disclosure can be achieved. The same applies to other expressions using "approximately" or "rectangular."

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

[0014] FIG. 1A is a schematic diagram showing an example of a vehicle 2 on which a display device 1 according to an embodiment is installed. FIG. 1B is a schematic diagram showing the display device 1 according to an embodiment and the vehicle 2 as viewed from the right. FIG. 2 is a diagram showing the display device 1 according to an embodiment as viewed from the right. FIG. 3A is a perspective view showing the display device 1 according to an embodiment. FIG. 3B is a diagram showing the correspondence between the left-right direction and the X-axis direction, the front-rear direction and the Y-axis direction, and the up-down direction and the Z-axis direction. FIG. 4A is a diagram showing the display device 1. (a) of FIG. 4A is a front view of the display device 1, (b) of FIG. 4A is a side view of the display device 1, and (c) of FIG. 4A is a front view of the display device 1. FIG. 4B is a diagram showing an emission hologram element 43 according to an embodiment with respect to a rectangular hologram element. FIG. 4C is a diagram showing the shape and path of image light emitted from the display device 1. In FIG. 4C, the progression of the image light is indicated by dashed arrows.

[0015] In FIG. 1A, the forward direction is the direction along the overall length of the vehicle 2, extending from the interior of the vehicle 2 through the windshield 3 toward the exterior of the vehicle 2. In other words, the forward direction is the traveling direction of the vehicle 2. The direction opposite the forward direction is the rearward direction. The direction perpendicular to the forward and rearward directions and extending along the overall width of the vehicle 2 is the left-right direction. In the left-right direction, when a user looks forward from inside the vehicle 2, the right-hand side of the user is the right direction, and the left-hand side of the user is the left direction. The direction of light representing an image output from the display device 1 toward the windshield 3 is the upward direction. The direction opposite the upward direction is the downward direction. In FIG. 3A, the alignment direction of the folded hologram element 42 relative to the input hologram element 41 is defined as the positive X-axis direction, the alignment direction of the folded hologram element 42 relative to the output hologram element 43 is defined as the positive Y-axis direction, and the alignment direction of the input hologram element 41 relative to the image generating device 20 is defined as the positive Z-axis direction. 3B also shows the correspondence relationships between the left-right direction and the X-axis direction, the front-rear direction and the Y-axis direction, and the up-down direction and the Z-axis direction. As shown in FIG. 3B, the Y-axis direction is tilted relative to the front-to-back direction, with the X-axis direction as the axis, on an imaginary plane indicated by the two-dot chain lines in the up-down and front-to-back directions. The positive side of the Y-axis corresponds to the front side of the display device 1, and the negative side of the Y-axis corresponds to the rear side of the display device 1. The positive X-axis direction is approximately parallel to the right side of the display device 1, the negative X-axis direction is approximately parallel to the left side of the display device 1, the positive Z-axis direction is approximately parallel to the upward direction of the display device 1, and the negative Z-axis direction is approximately parallel to the downward direction of the display device 1. The correspondence relationships in FIG. 3B apply to each figure.

[0016] As shown in FIGS. 1A and 1B, the display device 1 is disposed on the dashboard (also referred to as an instrument panel) of a vehicle 2 such as an automobile. A windshield 3 (also referred to as a windshield) is disposed above the dashboard of the vehicle 2. The light guide 30 of the display device 1 is disposed between the dashboard and the windshield 3. The light guide 30 is configured by incorporating a diffractive optical element in a light guide plate 31 having an incident surface 31a and an exit surface 31b. The specific configuration of the light guide 30 will be described later. The windshield 3 is an example of a display medium.

[0017] The display device 1 can make the image light, which is light representing an image emitted from the light guide 30, incident on the windshield 3 for a user such as a driver or a passenger, enter the eyebox of the user. In other words, the display device 1 can project an image represented by the image light emitted by the image generating device 20 forward on the windshield 3, thereby displaying a virtual image corresponding to the image on the windshield 3. The image light is light representing an image, and is light displayed as a virtual image in front of the windshield 3. The image is a still image or a moving image, such as an image of numbers, letters, or figures.

[0018] As shown in FIGS. 1A and 2, the display device 1 includes an image generating device 20 and a light guide 30. The image generating device 20 is a light guiding element.

[0019] <Image generating device 20> The image generating device 20 emits image light that represents an image with a rectangular outline, thereby projecting a predetermined image onto the windshield 3 via the light guide 30. The image generating device 20 can emit the image light from a rectangular emission surface. The image light emitted from the image generating device 20 enters and passes through the light guide 30, and is then emitted from the light guide 30 to be irradiated onto the windshield 3. As a result, the image light is reflected by the windshield 3, and an image is projected onto the windshield 3, causing the user to recognize a virtual image.

[0020] The image generating device 20 includes a plurality of emitters, a plurality of dichroic mirrors, a condenser lens, a mirror, and an exit surface.

[0021] Each of the multiple emitters emits a light beam that is different from the others and is light of a predetermined wavelength band. Each of the multiple dichroic mirrors is positioned on the light beam emitted by the emitter, and can reflect light beams of a predetermined wavelength band and transmit light beams of other wavelength bands. The condenser lens is a lens that condenses the light beams emitted via the dichroic mirrors onto the multiple mirrors. The emission surface is a screen such as a microlens array or a liquid crystal display element such as a liquid crystal display (LCD), and when light beams of a plurality of wavelength bands are irradiated from the mirror side, the transmitted light can be emitted as image light.

[0022] Note that a reflective liquid crystal element may be used for the image generating device 20. In this case, by irradiating the reflective liquid crystal element with light rays of a plurality of wavelength bands, the reflected light can be emitted as image light.

[0023] <Light guide 30> 2, 3A, and 4A, the light guide 30 is a holographic light guide that displays an image represented by image light to a user. The light guide 30 can elongate an image represented by the image light emitted by the image generating device 20 in the X-axis direction and the Y-axis direction and emit the image.

[0024] The light guide 30 has a rectangular, flat plate shape that is substantially parallel to the XY plane. The light guide 30 is disposed so that the incident surface 31a faces the image generating device 20.

[0025] The light guide 30 includes a light guide plate 31 , an entrance hologram element 41 , a return hologram element 42 , and an exit hologram element 43 .

[0026] The light guide plate 31 is a light-transmitting, rectangular, flat plate that is substantially parallel to the XY plane. The light guide plate 31 has an incident surface 31a and an exit surface 31b.

[0027] The incident surface 31a receives the image light emitted from the exit surface of the image generating device 20. The incident surface 31a is a part of the rear surface of the rectangular light guide plate 31, and is located at one of the four corners of the rear surface. The rear surface is the surface of the light guide plate 31 opposite to the exit surface 31b.

[0028] The exit surface 31b emits the image light that has entered from the entrance surface 31a and propagated inside the light guide plate 31 toward the windshield 3. The exit surface 31b faces the windshield 3 and is spaced a predetermined distance from the windshield 3. The exit surface 31b is a part of the surface of the light guide plate 31.

[0029] The incident hologram element 41 is a light-transmitting incident diffractive optical element contained in the light guide plate 31. The incident hologram element 41 has a rectangular plate shape. The incident hologram element 41 is an example of a second hologram element.

[0030] The entrance 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.

[0031] The incident hologram element 41 can emit first deflected light obtained by deflecting, by diffraction, the image light that is emitted from the exit surface of the image generating device 20 and travels along the positive direction of the Z axis and that is incident on the incident surface 31a. Specifically, the incident hologram element 41 deflects the image light by diffraction in accordance with its own diffraction efficiency as the image light propagates through the light guide 30, and emits the first deflected light (image light) that is guided along the positive direction of the X axis. The first deflected light deflected by diffraction by the incident hologram element 41 is incident on the folded hologram element 42.

[0032] The folded hologram element 42 is a light-transmitting, output diffractive optical element that is contained within the light guide plate 31. The folded hologram element 42 has a plate shape that is long along the X-axis direction. The folded hologram element 42 is an example of a third hologram element.

[0033] The folded hologram element 42 is arranged on the positive X-axis side of the incident hologram element 41, on the light exit side of the incident hologram element 41, and on the positive Y-axis side of the exit hologram element 43, along the light entrance side of the exit hologram element 43.

[0034] The folded hologram element 42 receives first deflected light, which is image light incident on the incident surface and deflected by diffraction at the entrance hologram element 41. Each time the folded hologram element 42 receives (transmits) the first deflected light that has passed through the entrance hologram element 41, the folded hologram element 42 further deflects the incident first deflected light by diffraction to generate second deflected light (image light) toward the exit hologram element 43. Specifically, when the first deflected light propagates through the light guide 30 along the positive direction of the X axis, the folded hologram element 42 deflects the first deflected light by diffraction in accordance with its own diffraction efficiency, and outputs the second deflected light (image light) that propagates along the negative direction of the Y axis. At this time, the folded hologram element 42 serves to stretch the image of the image light in the X axis direction. The folded hologram element 42 emits the second deflected light in the negative direction of the Y axis. The second deflected light is incident on the exit hologram element 43.

[0035] The diffraction efficiency of the folded hologram element 42 may be set lower the closer it is to the incident hologram element 41 and higher the farther it is from the incident hologram element 41. This can improve the uniformity of the displayed image.

[0036] Emission hologram element 43 is a light-transmitting emission diffractive optical element contained within light guide plate 31. Emission hologram element 43 has a non-rectangular plate shape. Emission hologram element 43 is an example of a first hologram element.

[0037] Exit hologram element 43 is disposed on the negative Y-axis direction side of folded hologram element 42, facing the light incident side of folded hologram element 42. In addition, exit hologram element 43 is disposed so as to overlap with and face exit surface 31b of light guide 30.

[0038] 4A(a), when light guide 30 is viewed from above, rearmost edge 43a, which is located furthest rearward (negative Y-axis direction) among the four sides of output hologram element 43, is inclined with respect to the left-right direction. In other words, rearmost edge 43a, which is located on the user side among the four sides of output hologram element 43, is inclined with respect to the X-axis direction and also with respect to the edge of light guide plate 31 on the negative Y-axis direction side.

[0039] Specifically, when the output hologram element 43 is viewed from above, the rearmost side 43a is tilted clockwise with respect to the left-right direction when an image is projected onto the right side of the vehicle 2 on the windshield 3. In other words, when the display device 1 is placed on the right side of the vehicle 2, the rearmost side 43a is tilted clockwise with respect to the left-right direction.

[0040] Furthermore, when the output hologram element 43 is viewed from above, the rearmost side 43a is tilted counterclockwise with respect to the left-right direction when an image is projected onto the left side of the vehicle 2 on the windshield 3. In other words, when the display device 1 is placed on the left side of the vehicle 2, the rearmost side 43a is tilted counterclockwise with respect to the left-right direction.

[0041] The front edge 43b is inclined in the same direction as the rear edge 43a with respect to the left-right direction. In other words, the front edge 43b, which is located furthest forward among the four edges of the emission hologram element 43, is inclined with respect to the left-right direction and is also inclined with respect to the longitudinal direction of the folded hologram element 42. Figure 3A and other figures illustrate an example in which the front edge 43b and the rear edge 43a are inclined clockwise with respect to the left-right direction.

[0042] The second deflected light beam emitted from the folding hologram element 42 is incident on the output hologram element 43. Each time the second deflected light beam that has passed through the folding hologram element 42 enters (transmits), the output hologram element 43 further deflects the incident second deflected light beam by diffraction to emit third deflected light (image light) at a predetermined output angle. Specifically, when the second deflected light beam deflected by diffraction by the folding hologram element 42 propagates through the light guide 30 along the negative Y-axis direction, the output hologram element 43 deflects the second deflected light beam by diffraction in accordance with its own diffraction efficiency, and outputs the third deflected light beam that propagates along the positive Z-axis direction. At this time, the output hologram element 43 serves to further stretch the image of the second deflected light beam, which has been stretched along the X-axis direction, along the Y-axis direction. That is, the output hologram element 43 can output image light of an image expanded in the X-axis and Y-axis directions by further stretching the image represented by the image light output by the image generating device 20 in the Y-axis direction. The output hologram element 43 also outputs the third deflected light, i.e., the image light, in the positive direction of the Z-axis. The image light is output from the output surface 31b. As a result, the image light output from the output surface 31b enters the windshield 3.

[0043] The diffraction efficiency of output hologram element 43 may be set lower the closer it is to folded hologram element 42 and higher the farther it is from folded hologram element 42 .

[0044] The emission angle of the third deflected light emitted from the emission surface of emission hologram element 43 is the angle of the emitted light with respect to the normal to the emission surface of emission hologram element 43 .

[0045] Furthermore, output hologram element 43 may diverge the output image light so that the output angles of the third deflected light are different. When output hologram element 43 deflects the incident image light by diffraction, output hologram element 43 may vary the output angle depending on the position (portion) on output hologram element 43. This allows output hologram element 43 to vary the output angles of some of the image light deflected by output hologram element 43 by diffraction.

[0046] <Operation> In such a display device 1, image light emitted from the exit surface of image generating device 20 enters entrance surface 31a of light guide plate 31, propagates through light guide 30, and enters entrance hologram element 41. The image light incident on entrance hologram element 41 is deflected by diffraction by entrance hologram element 41, and is emitted from entrance hologram element 41 as first deflected light. The first deflected light emitted from entrance hologram element 41 enters folding hologram element 42, where a portion of the first deflected light is deflected by diffraction and exits folding hologram element 42 as second deflected light, and the remainder propagates through light guide plate 31, is reflected by the front and back surfaces, and enters folding hologram element 42 again. The first deflected light is deflected by diffraction again by folding hologram element 42 and exits as second deflected light, so that the image light emitted from image generating device 20 is elongated in the X-axis direction by folding hologram element 42. The second deflected light emitted from the folding hologram element 42 enters the emission hologram element 43, where a portion of the light is deflected by diffraction and emitted from the emission hologram element 43 as third deflected light, and the remainder propagates through the light guide plate 31, reflecting at the front and back surfaces and then entering the emission hologram element 43 again. The second deflected light is deflected again by diffraction by the emission hologram element 43 and emitted as the third deflected light, and the second deflected light that has been stretched in the X-axis direction by the folding hologram element 42 is then stretched in the Y-axis direction by the emission hologram element 43. This enlarges the image represented by the image light emitted from the image generating device 20. The second deflected light is deflected again by diffraction by the emission hologram element 43, whereby the second deflected light is emitted from the emission hologram element 43 as third deflected light, and the third deflected light (image light) is emitted from the exit surface 31b.

[0047] In this way, output hologram element 43 emits non-rectangular quadrangular image light toward windshield 3 of vehicle 2. Windshield 3 reflects the incident non-rectangular quadrangular image light by distorting its shape into rectangular image light. The image light reflected by windshield 3 is directed toward the eyebox of the user of vehicle 2.

[0048] Therefore, the user can see the virtual image displayed by the display device 1 superimposed on the view ahead seen through the windshield 3 in the traveling direction of the vehicle 2.

[0049] <Action and effect> Next, the effects of the display device 1 according to the present embodiment will be described.

[0050] As described above, display device 1 according to the present embodiment projects an image onto a curved display medium (windshield 3) provided in a moving body (vehicle 2) to display a virtual image, and includes image generating device 20 that generates light representing the image (image light), and light guide 30 having a first hologram element (emission hologram element 43) with a non-rectangular quadrangle shape. The first hologram element emits the light representing the image propagating inside light guide 30 toward the display medium.

[0051] For example, as shown by the two-dot chain line in Fig. 4B, in the case of image light emitted from a rectangular emission hologram, light that is not related to the display of a virtual image on the windshield is emitted from the emission hologram, as shown by the diagonal hatching in Fig. 4B, which results in a decrease in light utilization efficiency for the light representing the image emitted from the rectangular emission hologram.

[0052] However, according to the present embodiment, the shape of output hologram element 43 can be made non-rectangular, i.e., quadrangular, in accordance with the curved windshield 3. As a result, as shown in Fig. 4C, the non-rectangular image light output from output hologram element 43 becomes rectangular, i.e., has the same shape as the outline of the image light output from image generation device 20, after being reflected by windshield 3. In other words, display device 1 can output image light related to the display of a virtual image on windshield 3 better than the prior art.

[0053] Therefore, the display device 1 can prevent the efficiency of use of the light representing the image emitted from the emission hologram element 43 from decreasing.

[0054] In particular, in the display device 1 of the present embodiment, compared to the prior art, light that is not related to the display of a virtual image on the windshield 3 is less likely to be emitted, and therefore the generation of stray light can be suppressed.

[0055] Furthermore, in the display device 1 according to this embodiment, if the direction along the overall length of the moving body is defined as the forward direction from the inside of the moving body through the display medium to the outside of the moving body, the direction opposite to the forward direction is defined as the rearward direction, and the direction perpendicular to the forward and rearward directions and along the overall width of the moving body is defined as the left-right direction, the rearmost edge 43a of the four edges of the first hologram element, which is located furthest to the rear, is inclined with respect to the left-right direction.

[0056] For example, if an output hologram element is disposed between the rearmost side and the edge of the light guide, light that is not related to the display of a virtual image on the windshield will be output.

[0057] However, according to the present embodiment, by tilting the rearmost side 43a in accordance with the curved windshield 3, it is possible to avoid disposing the emission hologram element 43 between the rearmost side 43a and the edge of the light guide 30. This makes it possible to prevent light that is not related to the display of a virtual image on the windshield 3 from being emitted.

[0058] Furthermore, in the display device 1 according to this embodiment, when the first hologram element is viewed in a plane, the rearmost edge 43a is tilted clockwise relative to the left-right direction when an image is projected onto the right side of the moving body on the display medium, and is tilted counterclockwise relative to the left-right direction when an image is projected onto the left side of the moving body on the display medium.

[0059] According to this, the image light reflected by the right windshield 3 of the vehicle 2 is reflected by rotating the rearmost edge 43a, which is tilted clockwise with respect to the left-right direction, counterclockwise. Also, the image light reflected by the left windshield 3 of the vehicle 2 is reflected by rotating the rearmost edge 43a, which is tilted counterclockwise with respect to the left-right direction, clockwise. Therefore, a rectangular image having the same shape as the outline of the image light emitted by the image generation device 20 can be projected onto the windshield 3. Therefore, the image projected onto the windshield 3 can be displayed without distortion.

[0060] Furthermore, in display device 1 according to the present embodiment, front side 43b, which is located furthest forward among the four sides of first hologram element, is inclined in the same direction as rearmost side 43a with respect to the left-right direction.

[0061] For example, if the output hologram element 43 is disposed between the forefront side 43b and the edge of the light guide 30, light that is not related to the display of a virtual image on the windshield 3 will be emitted.

[0062] However, according to the present embodiment, by tilting the forefront edge 43b in accordance with the curved windshield 3, it is possible to avoid disposing the emission hologram element 43 between the forefront edge 43b and the edge of the light guide 30. This makes it possible to prevent light that is not related to the display of a virtual image on the windshield 3 from being emitted.

[0063] In the display device 1 according to the present embodiment, the first hologram element emits light representing a non-rectangular quadrangular image toward the display medium of the moving body, and the display medium reflects the incident non-rectangular quadrangular light by distorting its shape into light representing a rectangular image.

[0064] According to this, the non-rectangular, quadrangular image light emitted by output hologram element 43 can be distorted into rectangular image light by being reflected by the curved windshield 3. As a result, rectangular image light enters the user's eyebox, allowing the user to recognize the virtual image projected on windshield 3 without feeling uncomfortable.

[0065] In display device 1 according to the present embodiment, light guide 30 further includes a rectangular second hologram element (folded hologram element 42) and a rectangular third hologram element (incident hologram element 41). When light representing an image emitted by image generating device 20 enters second hologram element, second hologram element deflects the light representing the image by diffraction and causes the light to propagate inside light guide 30. The third hologram element further deflects the light representing the image deflected by the second hologram element by diffraction and causes the light representing the deflected image to propagate inside light guide 30. The first hologram element further deflects the light representing the image deflected by diffraction by the third hologram element by diffraction and causes the light representing the deflected image to exit light guide 30.

[0066] According to this, the size of the image represented by the image light emitted by the image generating device 20 can be enlarged by the entrance hologram element 41, the return hologram element 42, and the exit hologram element 43, and projected onto the windshield 3. Therefore, the image can be displayed at a size that is visible to the user.

[0067] (First Modification of the Embodiment) This modification differs from the display device of the embodiment in that the display device 1a rotates. Unless otherwise specified, the other configurations of this modification are the same as those of the display device of the embodiment, and the same components are assigned the same reference numerals and detailed descriptions of the configurations are omitted.

[0068] The configuration of the display device 1a will be described with reference to FIGS.

[0069] Fig. 5 is a schematic diagram showing a rotating display device 1a according to a first modified example of the embodiment and a vehicle 2 when viewed in a forward direction. Fig. 6 is a schematic diagram showing a rotating light guide 30 according to a first modified example of the embodiment and a vehicle 2 when viewed in a forward direction. Fig. 7 is a schematic diagram showing the attitude of the rotated display device 1a.

[0070] In this modification, as shown in FIGS. 5 and 6, at least the light guide 30 can rotate about an axis in the left-right direction and an axis in the front-rear direction.

[0071] 5, the entire display device 1a may be rotated from a position in which the surface of the light guide 30 is parallel to the horizontal plane to tilt about an axis in the left-right direction relative to the horizontal plane. Alternatively, the entire display device 1a may be rotated from a position in which the surface of the light guide 30 is parallel to the horizontal plane to tilt about an axis in the front-rear direction relative to the horizontal plane.

[0072] 6, in the display device 1a, only the light guide 30 may rotate from a position in which the surface of the light guide 30 is parallel to the horizontal plane to tilt with respect to the horizontal plane around an axis in the front-to-rear direction. Also, in the display device 1a, only the light guide 30 may rotate from a position in which the surface of the light guide 30 is parallel to the horizontal plane to tilt with respect to the horizontal plane around an axis in the left-to-right direction. In this case, the image generating device 20 is fixed to the vehicle 2 and does not rotate.

[0073] Furthermore, when the light guide 30 is viewed in the forward direction, the light guide 30 may be tilted clockwise around the longitudinal axis from a state parallel to the left-right direction when an image is projected onto the right side of the vehicle 2 on the windshield 3. In other words, when the display device 1a is disposed on the right side of the vehicle 2, the light guide 30 may be disposed in a position tilted clockwise from a state parallel to the left-right direction.

[0074] Furthermore, when the light guide 30 is viewed in the forward direction, the light guide 30 may be tilted counterclockwise around the longitudinal axis from a state parallel to the left-right direction when an image is projected onto the left side of the vehicle 2 on the windshield 3. In other words, when the display device 1a is disposed on the left side of the vehicle 2, the light guide 30 may be disposed in a posture tilted counterclockwise from a state parallel to the left-right direction.

[0075] 7, when the light guide 30 is viewed in the forward direction, the light guide 30 is disposed so as to approach a posture approximately parallel to a tangent to the windshield 3 at an intersection A1 between the principal ray of the image light emitted by the image generating device 20 and the windshield 3. Specifically, the posture of at least the light guide 30 can be tilted so that a plane tangent to the intersection A1 and the surface of the light guide 30 are approximately parallel.

[0076] In this way, by adjusting at least the posture of the light guide 30, the optical axis of the light representing the image emitted by the image generating device 20 and the chief ray of the light representing the image emitted by the light guide 30 are made approximately parallel.

[0077] In the display device 1a of this modified example, at least the light guide 30 rotates so that the surface of the light guide 30 is tilted about an axis in the front-to-rear direction on the horizontal plane from a position in which the surface of the light guide 30 is parallel to the horizontal plane.

[0078] According to this, when the entire display device 1a rotates, the attitude of the display device 1a can be adjusted so that the irradiation direction of the image light emitted by the image generating device 20 is parallel to the irradiation direction of the image light emitted from the light guide 30. Therefore, blurring of the image projected onto the windshield 3 can be suppressed.

[0079] Furthermore, when only the light guide 30 rotates, the attitude of the light guide 30 relative to the image generating device 20 can be changed, and therefore the attitude of the light guide 30 can be adjusted so that the irradiation direction of the image light emitted by the image generating device 20 is parallel to the irradiation direction of the image light emitted from the light guide 30. This makes it possible to suppress image blurring of the image projected onto the windshield 3.

[0080] Furthermore, in the display device 1a of this modified example, when the light guide 30 is viewed in the forward direction, the light guide 30 is tilted clockwise relative to a state parallel to the left-right direction when an image is projected onto the right side of the moving body on the display medium, and is tilted counterclockwise relative to a state parallel to the left-right direction when an image is projected onto the left side of the moving body on the display medium.

[0081] For example, the greater the curvature of the left or right side of the windshield, the more non-parallel the windshield and the light guide become, which tends to reduce the acute angle of the non-rectangular quadrangle of the output hologram element. In this case, the output hologram element becomes longer, which in turn increases the size of the light guide.

[0082] However, according to this modification, the attitude of the light guide 30 can be adjusted so that the light guide 30 and the windshield 3 are substantially parallel to each other. This prevents the acute angles in the non-rectangular quadrangle shape of the output hologram element 43 from becoming too small. As a result, the length of the output hologram element 43 is prevented from increasing, and the size of the light guide 30 is prevented from increasing.

[0083] Furthermore, in the display device 1a of this modified example, when the light guide 30 is viewed in the forward direction, the light guide 30 is positioned so that it is approximately parallel to the tangent of the display medium at the intersection A1 between the chief ray of the light representing the image emitted by the image generating device 20 and the display medium.

[0084] This allows the light guide 30 to be arranged so that the surface of the light guide 30 is approximately parallel to the windshield 3. This more reliably prevents the acute angles in the non-rectangular quadrangular shape of the output hologram element 43 from becoming too small. As a result, the length of the output hologram element 43 is prevented from increasing, and the size of the light guide 30 is more reliably prevented from increasing.

[0085] In the display device 1a of this modified example, the optical axis of the light that represents the image emitted by the image generating device 20 and the chief ray of the light that represents the image emitted by the light guide 30 are substantially parallel to each other.

[0086] If the optical axis of the light representing the image emitted by the image generating device is non-parallel to the chief ray of the light representing the image emitted by the light guide, the angle of incidence of the image light emitted by the image generating device onto the light guide will also be non-parallel to the angle of emergence of the chief ray of the image light emitted by the light guide, which will result in blurring of the image projected onto the windshield.

[0087] However, according to the display device 1a of this modified example, it is possible to suppress image blurring of the image projected onto the windshield 3.

[0088] (Modification 2 of the embodiment) In this modification, the most extreme case of the output hologram element 43 of the display device 1b is before Side 43 b The display device of this modified example differs from that of the embodiment in that output hologram element 43 is arranged so that the direction of the light emitted from output hologram element 43 is approximately parallel to the longitudinal direction of folded hologram element 42. Unless otherwise specified, the other configurations of this modified example are the same as those of the display device of the embodiment, and the same components are denoted by the same reference numerals, and detailed description of the configurations will be omitted.

[0089] The configuration of the light guide 30 in the display device 1b will be described with reference to FIG.

[0090] FIG. 8 is a plan view showing a light guide 30 of a display device 1b according to a second modification of the embodiment.

[0091] In this modification, compared to the light guide before rotation as in the embodiment shown by the two-dot chain line, light guide 30a of this modification rotates clockwise or counterclockwise about the X-axis direction and the Y-axis direction when the surface is taken as a reference position substantially parallel to the XY plane. In other words, light guide 30a is rotated clockwise or counterclockwise about the Z-axis direction, compared to the light guide before rotation as in the embodiment. Emission hologram element 43 of this modification is disposed in substantially the same position within vehicle 2 as the emission hologram element of the embodiment.

[0092] Specifically, when the display device 1b is disposed on the right side of the vehicle 2, the position of the display device 1b excluding the output hologram element 43 is rotated clockwise around the Z-axis direction.

[0093] Furthermore, when display device 1b is disposed on the left side of vehicle 2, display device 1b excluding output hologram element 43 is disposed at a position rotated counterclockwise around the Z-axis direction.

[0094] The output hologram element 43 is disposed inside the light guide plate 31 with the front side 43b or the rear side 43a of the output hologram element 43 being approximately parallel to the longitudinal direction parallel to the long side of the folded hologram element 42. In FIG. Front side 43b The output hologram element 43 is disposed inside the light guide plate 31 so that the front edge 43b approaches the second deflected light emitted from the folded hologram element 42 in parallel with the long side of the folded hologram element 42. The front edge 43b is disposed inside the light guide plate 31 so as to be perpendicular to the second deflected light emitted from the folded hologram element 42.

[0095] In the display device 1b of this modified example, the second hologram element is elongated along the left-right direction, which is the direction along the overall width of the moving body. before The most before Side 43 b is disposed inside the light guide 30 so as to be substantially parallel to the long side of the second hologram element.

[0096] According to this, the most before Side 43 b and the folded hologram element 42 can be made smaller. before Side 43 b In comparison with the case where the folded hologram element 42 is disposed inside the light guide 30 so as to be non-parallel to the light guide plate 31, the size of the light guide plate 31 can be prevented from increasing.

[0097] (Other variations) While the display device according to the present disclosure has been described above based on the above-described embodiments, the present disclosure is not limited to these embodiments. As long as the modifications do not deviate from the spirit of the present disclosure, modifications that would occur to those skilled in the art may also be included in the scope of the present disclosure.

[0098] In addition, this disclosure also includes forms obtained by making various modifications to the above embodiments that a person skilled in the art would think of, and forms realized by arbitrarily combining the components and functions of the embodiments within the scope that does not deviate from the intent of this disclosure. [Industrial Applicability]

[0099] The present disclosure can be used in a head-up display device for a vehicle, etc. [Explanation of symbols]

[0100] 1, 1a, 1b display device 2. Vehicles (moving objects) 3. Front window (display medium) 20 Image generation device 30, 30a light guide 41 Incident hologram element (second hologram element) 42 Folded hologram element (third hologram element) 43 Output hologram element (first hologram element) 43a End 43b Front edge

Claims

1. A display device that projects an image onto a curved display medium provided on a moving body to display a virtual image, an image generating device that generates light indicative of an image; a light guide having a first hologram element having a non-rectangular quadrangular shape; the first hologram element emits light representing the image propagating inside the light guide toward the display medium; the first hologram element emits light representing the image having a non-rectangular quadrangular shape toward the display medium of the moving body; The display medium reflects the incident non-rectangular square-shaped light by changing its shape into light showing the rectangular image. Display device.

2. In a direction along the overall length of the moving body, the direction from the inside of the moving body toward the outside of the moving body via the display medium is defined as the forward direction, the direction opposite to the forward direction is defined as the rearward direction, and the direction perpendicular to the forward direction and the rearward direction and along the overall width direction of the moving body is defined as the left-right direction. The rearmost side of the four sides of the first hologram element, which is located furthest to the rear side, is inclined with respect to the left-right direction. The display device according to claim 1 .

3. When the first hologram element is viewed in plan from the light exit surface side of the first hologram element, When the image is projected onto the right side of the moving body on the display medium, the image is tilted clockwise with respect to the left-right direction, When the image is projected on the left side of the moving body on the display medium, the image is tilted counterclockwise with respect to the left-right direction. The display device according to claim 2 .

4. The front edge of the first hologram element, which is located furthest in the forward direction among the four edges thereof, is inclined in the same direction as the rear edge with respect to the left-right direction. The display device according to claim 2 or 3.

5. At least the light guide rotates from a position in which the surface of the light guide is parallel to a horizontal plane to tilt on the horizontal plane about an axis of a front-rear direction that is made up of the front direction and the rear direction. The display device according to any one of claims 2 to 4.

6. When the light guide is viewed along the forward direction, When the image is projected onto the right side of the moving body on the display medium, the image is tilted clockwise with respect to a state parallel to the left-right direction, When the image is projected on the left side of the moving body on the display medium, the image is tilted counterclockwise with respect to the state parallel to the left-right direction. The display device according to claim 5 .

7. The light guide is disposed so as to approach a posture approximately parallel to a tangent to the display medium at an intersection between a chief ray of light showing the image emitted from the light guide and the display medium when the light guide is viewed along the forward direction. The display device according to claim 5 or 6.

8. The optical axis of the light representing the image emitted by the image generating device and the chief ray of the light representing the image emitted by the light guide are substantially parallel to each other. The display device according to any one of claims 1 to 7.

9. the light guide further includes a rectangular second hologram element and a rectangular third hologram element; the second hologram element, when receiving light representing the image emitted by the image generating device, deflects the light representing the image by diffraction and propagates the light inside the light guide; the third hologram element further deflects the light representing the image deflected by the second hologram element by diffraction, and propagates the deflected light representing the image inside the light guide; The first hologram element further deflects, by diffraction, the light representing the image deflected by the third hologram element, and emits the deflected light representing the image to the outside of the light guide. The display device according to any one of claims 1 to 8.

10. the second hologram element is elongated along a left-right direction that is a direction along the overall width direction of the moving body, The first hologram element is disposed inside the light guide body such that the frontmost side of the four sides of the first hologram element, which is located on the front side, is substantially parallel to the long side of the second hologram element. The display device according to claim 9 .

Images