Optical system and head-up display device

Abstract

The purpose of the present invention is to provide a compact head-up display device.　A head-up display device (30) according to the present invention comprises a display panel (2), a light source (1) that supplies light to the display panel (2), a relay optical system (3) that maps image light emitted from the display panel (2), and a diffusion element part (4) that diffuses the image light mapped by the relay optical system (3). The diffusion element part (4) has different optical actions in the horizontal direction and the vertical direction of the diffusion element part (4) that correspond to the horizontal direction and the vertical direction of a viewer.

Description

Technical Field

[0001] The present invention relates to an optical system and a head-up display device.

Background Art

[0002] A head-up display device is known that projects an image onto a windshield (windshield) provided in a moving body such as an automobile or an aircraft, and allows the projected image to be observed as a virtual image through the windshield.

[0003] For example, Patent Document 1 discloses, as a conventional head-up display device, a device "including a projection optical system that irradiates light from behind a transmissive liquid crystal display panel and magnifies and projects an image displayed on the liquid crystal display panel."

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] In the example of the head-up display device disclosed in Patent Document 1, a driver observes a virtual image by projecting an "enlarged real image of an image formed by a relay lens" onto a windshield by a projection lens. That is, by obtaining an enlarged real image of a liquid crystal display panel by a relay lens, a small liquid crystal display panel can be used.

[0006] However, in miniaturizing a liquid crystal display panel in a head-up display device, there are problems different from those in miniaturizing a normal optical system. This will be described using FIGS. 7A, 7B, and 7C.

[0007] Figures 7A, 7B, and 7C are explanatory diagrams showing the relationship between the miniaturization of the image display element 2 and the projection optical system 20b. In Figures 7A to 7C, the projection optical system 20b includes at least a mirror 5 and a windshield 6.

[0008] Figure 7A shows a standard-sized image display element 2. In Figure 7A, the size of the standard image display element 2 is denoted as A. The brightness F-number of the projection optical system 20b is determined by F = (focal length) / (pupil diameter = size of eye box 8) = 1 / 2 / tan(θ / 2). Figure 7B shows an example of a small image display element 2.

[0009] Figure 7B is a scaled-down version of Figure 7A, scaled down to 1 / 3, with the size of the image display element 2 being A / 3. In the configuration of Figure 7B, the size of the eyebox 8 is also reduced, making it impossible to secure the necessary size for the eyebox 8 required for the head-up display device 30. Figure 7C shows another example of a smaller image display element 2.

[0010] Figure 7C, like Figure 7B, shows the size of the image display element 2 as A / 3, but the size of the eye box 8 has been restored to the same size as in Figure 7A. In the configuration of Figure 7C, the size of the eye box 8 required for the head-up display device 30 is secured, but the brightness F value of the projection optical system 20b becomes F = 1 / 2 / tan(3θ / 2), so a significantly brighter projection optical system 20b is required.

[0011] In other words, miniaturizing the liquid crystal display panel leads to a significant deterioration in the optical performance of the projection optical system, or requires a larger number of lenses to maintain optical performance, resulting in an increased size. Furthermore, miniaturizing only the image display element 2 also reduces the size of the virtual image, narrowing the viewing angle of the head-up display device.

[0012] This invention has been made in view of the above-described circumstances, and aims to provide a compact head-up display device. [Means for solving the problem]

[0013] To solve the above problems, one representative head-up display device of the present invention comprises a display panel, a light source that supplies light to the display panel, a relay optical system that projects the image light emitted from the display panel, and a diffusion element section that diffuses the image light projected by the relay optical system, wherein the diffusion element section has different optical functions in the horizontal and vertical directions corresponding to the horizontal and vertical directions of the viewer. [Effects of the Invention]

[0014] According to the present invention, a compact head-up display device can be provided. Other problems, configurations, and effects will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0015] [Figure 1] This is a schematic diagram of a head-up display device. [Figure 2A] This is a schematic configuration and functional block diagram of a head-up display device. [Figure 2B] This is a schematic configuration and functional block diagram of a head-up display device. [Figure 3] This is a plan view of a car, a mobile vehicle equipped with a head-up display device, as seen from the front. [Figure 4A] This diagram shows a configuration using a standard-sized display panel. [Figure 4B] This diagram shows a configuration using a display panel, relay optics, and a screen plate. [Figure 4C] This diagram shows a configuration using a display panel, a relay optical system, and a diffusion element. [Figure 5A] This figure shows an example of the configuration of the diffusion element section. [Figure 5B] This figure shows another example of the configuration of the diffusion element section. [Figure 5C] This figure shows another example of the configuration of the diffusion element section. [Figure 6A]This is a diagram showing the diffusion of video light when no microlens is used. [Figure 6B] This is a diagram showing an example of the diffusion of video light when a microlens is used. [Figure 6C] This is a diagram showing another example of the diffusion of video light when a microlens is used. [Figure 6D] This is a diagram showing another example of the diffusion of video light when a microlens is used. [Figure 7A] This is a diagram showing an example of a projection optical system according to the size of the display panel. [Figure 7B] This is a diagram showing an example of a projection optical system according to the size of the display panel. [Figure 7C] This is a diagram showing an example of a projection optical system according to the size of the display panel. [Figure 8] This is a schematic configuration diagram of a head-up display device. [Figure 9A] This is a schematic configuration and functional block diagram of a head-up display device. [Figure 9B] This is a schematic configuration and functional block diagram of a head-up display device. [Figure 10] This is a diagram showing the basic configuration and operation of the diffusion element section. [Figure 11A] This is a diagram showing the mapping of incident light rays of the diffusion element section. [Figure 11B] This is a diagram showing the mapping of outgoing light rays of the diffusion element section. [Figure 12A] This is a diagram showing an example of the lens data of the diffusion element section. [Figure 12B] This is a diagram showing an example of the free-form surface coefficient of the diffusion element section. [Figure 13A] This is a diagram showing an example of the diffusion of video light when a microlens is used. [Figure 13B] This is a diagram showing video light when there is no microlens, with the same incident light as an example of the diffusion of video light. [Figure 14] This is a diagram showing an example of a ray diagram in the YZ cross-section and XZ cross-section of a free-form surface lens. [Figure 15A]This figure shows another example of lens data for the diffusion element section. [Figure 15B] This figure shows another example of the free surface coefficient of the diffusion element. [Figure 16A] This figure shows another example of light diffusion in images when using microlenses. [Figure 16B] This figure shows the image light in the absence of microlenses, using the same incident light as another example of light diffusion in images. [Figure 17] This figure shows another example of the ray diagrams of a free-form lens in the YZ and XZ sections. [Modes for carrying out the invention]

[0016] The following description will explain one embodiment of the present invention and various examples with reference to the drawings and other figures. The following description provides specific examples of the content of the present invention, and the present invention is not limited to this description. Various changes and modifications are possible by those skilled in the art within the scope of the technical ideas disclosed herein. In addition, in all the figures used to explain the examples, components having the same function are denoted by the same reference numerals, and repeated descriptions may be omitted.

[0017] The basic configuration of the head-up display device 30 will be explained using Figure 1. The head-up display device may also be referred to as a display device, virtual image display device, etc.

[0018] Figure 1 is a schematic diagram of the head-up display device 30. The head-up display device 30 shown in Figure 1 comprises an image forming unit and an image projection unit. In an embodiment of the present invention, the image forming unit has a light source 1 and an image display element or display panel 2. The image projection unit may include a mirror 5. Light is emitted from the light source 1 to the image display element or display panel 2, and then the image light from the display panel 2 is incident on the mirror 5. The image light emitted from the mirror 5 is reflected by the windshield 6 of a vehicle (for example, the automobile 500 in Figure 3) and incident on the observer's eye 9. In this invention, the explanation uses the projection of image light onto the windshield 6 of a vehicle, but the projection unit that projects the image light may be a projection member such as a combiner. With this configuration, from the perspective of the observer's eye 9, it appears as if they are viewing image information on a virtual image surface 7.

[0019] In this invention, the mirror 5 functions as an image projection unit that magnifies and reflects the image light from the image display element or display panel 2 in a set angle direction or a predetermined direction. The mirror 5 is, for example, a concave mirror (magnifying mirror) and is provided on the optical path between the image display element or display panel 2 and the windshield 6. The mirror 5 functions as an image light projection unit that projects the image light emitted from the display panel 2 onto the windshield 6, thereby allowing the projected image light to be seen as a virtual image by the eyes 9 of a user such as a driver. The mirror 5 in this embodiment is made of a mirror having a concave reflective surface.

[0020] The configuration of the head-up display device in this embodiment will be described with reference to Figure 2.

[0021] Figures 2A and 2B are configuration and functional block diagrams of the head-up display device of this embodiment. As shown in Figures 2A and 2B, the head-up display device comprises a display panel 2, a light source 1, and a controller 200 that controls their operation. The head-up display device further comprises a relay optical system 3 and a diffusion element unit 4. Light is irradiated from the light source 1 onto the display panel 2, and the image information (video information) displayed on the display panel 2 is emitted towards the mirror 5 via the relay optical system 3 and the diffusion element unit 4. The light source 1, display panel 2, relay optical system 3, and diffusion element unit 4 may be referred to as an optical system.

[0022] Light source 1 typically includes an LED (Light Emitting Diode) light source, and multiple light sources may be used in an array. The image display element or display panel 2 is typically a liquid crystal display (LCD). The display panel 2 creates an image based on the image data instructed and input from the controller 200 and displays it on the display surface of the display element of the display panel 2. The image display element 2 may also be called a liquid crystal display panel, liquid crystal display element, display element, display panel, etc. Light source 1 may also be called a backlight.

[0023] As shown in Figure 2A, in the embodiment of the present invention, the head-up display device 30 is a device equipped with a controller 200. Also, as shown in Figure 2B, if there is no controller 200, the control unit of the automobile can function as the controller 200. When controlled by the control unit of the automobile, the control is substantially the same as the control of the controller 200 of the head-up display device 30, and the following embodiments will be described using the controller 200 of the head-up display device 30. That is, the head-up display device 30 may be equipped with a controller 200, or an externally equipped control device such as an automobile may be used.

[0024] Various types of information are input to this controller 200 from external devices. For example, a navigation device 208 that generates and outputs information about the operation of a mobile body equipped with a head-up display device 30, and an ECU (Electronic Control Unit) 209 that controls the operation of the mobile body are connected to it. Various sensors 210 on the mobile body are connected to the ECU 209 and are configured to notify the ECU 209 of the detected information.

[0025] The controller 200 includes a microcontroller 202 that processes various data from the external devices described above, a storage device 206 connected to the microcontroller 202, and a backlight drive circuit 207 for driving the backlight 1.

[0026] The microcontroller 202 has RAM (Random) for storing various data from external devices. Access Memory)203 and the CPU (Central Processing Unit) which performs the calculations to generate the image data that forms the basis of the virtual image seen by the observer. It includes a CPU 205 (Unit) and a ROM (Read Only Memory) 204 that stores programs and parameters capable of executing arithmetic processing in the CPU 205.

[0027] The controller 200, having the above configuration, displays image information on the image display element 2. The image information displayed on the image display element 2 is emitted as image light towards the mirror 5 via the relay optical system 3 and the diffusion element section 4, using light emitted by the backlight 1.

[0028] Returning to Figure 1, the image light emitted from the display panel 2 is projected onto the windshield 6 by the mirror 5. The image light projected from the mirror 5 onto the windshield 6 is reflected by the windshield 6 and reaches the position of the observer's eye 9. This creates a relationship where, from the observer's eye 9's perspective, it is as if they are viewing the image information of the virtual image surface 7. If the mirror 5 is not provided, the image light from the display panel 2 is emitted onto the windshield 6, and the image light emitted onto the windshield 6 is reflected by the windshield 6 and reaches the position of the observer's eye 9.

[0029] As shown in Figure 1, consider virtual points P1, P2, and P3 on the light emission surface of the image display element 2. The light emitted from these virtual points is mapped by the relay optical system 3 to points Q1, Q2, and Q3 on the diffusion element section 4. Considering the virtual points on the virtual image plane 7 corresponding to the light emitted from points Q1, Q2, and Q3, these are points V1, V2, and V3, as shown in Figure 1.

[0030] The eye box 8 is the range in which points V1, V2, and V3 on the virtual image plane 7 can be seen even when the observer moves the position of their eye 9. Thus, a system including the relay optical system 3, the diffusion element section 4, and the mirror 5 may be called a projection optical system or projection optical system that displays an image (virtual image) of an object (spatial image) in front of the observer's eye 9. Note that the projection optical system or projection optical system does not necessarily include the mirror 5.

[0031] Here, an example of mounting the head-up display device 30 according to this embodiment on a vehicle or mobile body will be explained using Figure 3.

[0032] Figure 3 is a plan view from the front of a vehicle 500, which is a mobile vehicle equipped with a head-up display device 30. In a vehicle 500 like the one shown in Figure 3, a windshield 6, which is a wind deflector, is located in front of the driver's seat.

[0033] The head-up display device 30 projects image light onto the windshield 6, making various information related to the automobile 500 visible as a virtual image to the driver and observers inside the automobile 500. The image light is projected in front of and around the driver's seat. For example, the image light is projected at the position shown in the dashed rectangular area R1.

[0034] Next, the basic configuration for miniaturizing the image display element 2 in this embodiment will be explained using Figures 4A to 4C. In Figures 4A to 4C, the projection optical system 20b includes a mirror 5 (Figure 2A). In this embodiment, the mirror 5 is a concave mirror and has a light-gathering effect, which is equivalent to the effect of a convex lens. However, the projection optical system 20b is not a convex lens, and in addition to the mirror 5, it may also include a concave lens or other optical components. Similarly, the relay optical system may be composed of multiple lenses, including a field lens. The F-number, which represents the brightness of the optical system, is determined by using θ as F = 1 / 2 / tan(θ / 2). The smaller the F-number, the brighter it is; in other words, the larger the θ, the brighter it is.

[0035] Figure 4A shows a configuration using a standard-sized image display element 2. In Figure 4A, the size of the standard image display element 2 is denoted as A. The F-number, which represents the brightness of the optical system using θ, is determined by F = (focal length) / (pupil diameter = size of eye box 8) = 1 / 2 / tan(θ / 2). A smaller F-number indicates brighter, meaning that a larger θ indicates brighter.

[0036] Figure 4B shows a configuration using a small image display element 2, a relay optical system 3, and a screen plate 4b. In Figure 4B, the size of the image display element 2 is set to A / 3. In Figure 4B, the size of the eye box 8 is secured by mapping the image onto the screen plate 4b using a relay optical system 3 with a magnification of 3x. The angle of the relay optical system 3 on the screen plate 4b side is θ, and the angle of the relay optical system 3 on the image display element 2 side is 3θ, and the F value is F = 1 / 2 / tan(3θ / 2), so the relay optical system 3 has a very large aperture.

[0037] Figure 4C shows a configuration using a small image display element 2, a relay optical system 3, and a diffusion element section 4. In Figure 4C, the size of the image display element 2 is A / 3, but the angle of the relay optical system 3 on the image display element 2 side remains θ, while the angle of the relay optical system 3 on the diffusion element section 4 side is set to θ / 3, and the size of the eye box 8 is secured by diffusing the image light with the diffusion element section 4. The configuration is as follows. The angle θ in Figure 4C is the distance from the video display element 2 to the top of the relay optical system 3. It consists of light incident on the front and light incident on the lower part of the relay optical system 3.

[0038] According to the configuration shown in Figure 4C, a small image display element 2 can be used without increasing the size of the relay optical system 3. Details of this diffusion element section 4 will be explained using Figures 5A to 5C. With respect to the vehicle, driver, or viewer, the X-axis is the horizontal direction, left-right direction, lateral direction of the vehicle, or width direction of the vehicle; the Y-axis is the up-down direction, vertical direction, or longitudinal direction of the vehicle; and the Z-axis, which is perpendicular to the lateral direction of the vehicle, is the front-back direction of the vehicle or the direction of travel of the vehicle.

[0039] In Figures 5A to 5C, the X and Y axes correspond to the horizontal and vertical directions, respectively, of the field of view (eyebox 8) observable by the observer. The horizontal observation range is larger by the distance between the left and right eyes. For example, eyebox 8 is 130 mm horizontally x 50 mm vertically. Therefore, the side of the diffusion element 4 corresponding to the X-axis direction requires a larger observation range than the side corresponding to the Y-axis direction. Also, if the microlenses are cylindrical lenses, the radius of curvature of the cylindrical lens is visible only when viewed from a specific direction; for example, the light incidence side of the microlens array 41 is viewed from the left or right, and the light emission side of the microlens array 41 is viewed from above or below.

[0040] In Figure 5A, the light-incident side of the microlens array 41 is planar, and the light-emitting side of the microlens array 41 diffuses light in the vertical and horizontal directions. In Figure 5B, the light-incident side of the microlens array 41 diffuses light in the Y-axis direction (vertical direction), and the light-emitting side of the microlens array 41 diffuses light in the X-axis direction (horizontal direction). In Figure 5C, the light-incident side of the microlens array 41 is planar, and the light-emitting side of the microlens array 41 diffuses light in the horizontal direction.

[0041] Figures 5A(1) to 5A(3) show an example of the configuration of the diffusion element section 4. In Figure 5A, the diffusion element section 4 comprises a microlens array 41 and a light-shielding grating 42a. The light-shielding grating and the microlens array are arranged via adhesive or holding parts. The microlens array 41 has one or more microlenses. The light-shielding grating 42a has one or more apertures and is located on the light-emitting side of the microlens array 41. The microlens array 41 also corresponds to the apertures of the light-shielding grating 42a. One microlens may correspond to one aperture, or one or more microlenses may correspond to one aperture, and this is not particularly limited. In other words, the light-shielding grating has apertures, each aperture has one or more apertures, and each aperture corresponds to at least one microlens. In this embodiment, the apertures of the light-shielding grating for shielding are arranged according to the microlens array. Each pixel of the image display element 2 corresponds to each cell of the microlens array 41 mapped by the relay optical system 3.

[0042] Figure 5A shows that the light incident side of the microlens array 41 is planar, and the light output side of the microlens array 41 exhibits diffusion in both the vertical and horizontal directions. The microlens array 41 has different radii of curvature in the XZ cross section and in the YZ cross section, and the diffusion angle in the X-axis direction is greater than the diffusion angle in the Y-axis direction. In other words, the divergence effect of each microlens in the horizontal direction (X-axis direction) of the microlens array 41 is greater than the divergence effect of each microlens in the vertical direction (Y-axis direction) of the microlens array 41. Note that the term "diffusion effect" in this invention may also be referred to as "divergence effect."

[0043] Microlenses can include, for example, toroidal lenses and free-form lenses. Each aperture of the light-shielding grating 42a corresponds to each lens of the microlens array 41, and shields the light that extends to the periphery of each cell of the focused light image (spot) of the microlens array 41 projected by the relay optical system 3. Although it varies depending on the panel size and resolution, for example, the aperture ratio of each pixel of the image display element 2 is about 50%, so by shielding the light beam of the relay optical system 3 that extends beyond the magnification, the degradation of resolution is prevented.

[0044] Figures 5B(1) to 5B(4) show another example of the configuration of the diffusion element section 4. In Figure 5A, the light-shielding grating 42a is located on the light-emitting side of the microlens array 41, but in Figure 5B, the light-shielding grating 42c is located on the light-indicating side of the microlens array 41, and the light-shielding grating 42b is located on the light-emitting side of the microlens array 41. Note that the light-shielding grating and the microlens array are connected by adhesive or a structure.

[0045] In Figure 5B, the microlens array 41 diffuses light in the Y-axis direction using the microlenses on the light-incident side and in the X-axis direction using the microlenses on the light-exit side. A light-shielding grating 42b is positioned in the X-axis direction, and a light-shielding grating 42c is positioned in the Y-axis direction. Alternatively, in Figure 5B, the light-incident side of the microlens array 41 diffuses light vertically, and the light-exit side diffuses light horizontally. Furthermore, while Figure 5B shows the light-shielding grating positioned in the direction of diffusion, the light-shielding grating 42a in Figure 5A may also be used.

[0046] Figures 5C(1) to 5C(3) show another example of the configuration of the diffusion element section 4. The microlens array 41 in Figure 5C has a shape with a radius of curvature only in the X-axis direction, and for example, an array of cylindrical lenses or a free-form surface lens array can be applied. In Figure 5C, the incident side of the microlens array 41 is planar, and the exit side of the microlens array 41 diffuses in the horizontal direction. In the microlens array 41 of Figure 5C, the diffusion effect is only in the X-axis direction. In other words, each microlens of the microlens array 41 has a divergent effect only in the horizontal direction (X-axis). Therefore, in Figure 5C, a light-shielding grating 42b that has a shielding effect only in the Y-axis direction is placed on the light-emitting side.

[0047] The light-shielding grating 42b in Figure 5C may have a shape that provides shielding only in the Y-axis direction, or the light-shielding grating 42a in Figure 5A may be used. Furthermore, the microlens array 41 shown in Figures 5A to 5C may be configured to have different divergent effects on the light-incident side and the light-exit side. In Figures 5A to 5C, the diffusion element section 4 may have a microlens array 41 and light-shielding gratings 42a, 42b, and 42c integrated into a single structure (holding). Each microlens of the microlens array 41 may have a diffusing effect on at least one of the light incident surface side and the light exit surface side of the diffusion element section. Furthermore, the optical design between the relay optical system 3 and the diffusion element section 4 may be telecentric, or a lenticular lens may be placed directly in front of the diffusion element section 4.

[0048] Next, the diffusion effect of the image light in the microlens array 41 of the diffusion element section 4 will be explained using Figures 6A to 6D. Figures 6A to 6D show the state in which image light is incident on the microlens array 41 from the relay optical system 3 side.

[0049] Figure 6A shows the diffusion of image light when microlenses are not used. As a reference, Figure 6A shows the case when the microlens array 41 is not used, and the shape of the image light on the image display element side or relay optical system side and the Eyebox side are almost the same.

[0050] Figure 6B shows an example of light diffusion when using microlenses. In Figure 6B, the angle at which light diffuses is increased by placing a microlens array 41 with positive refractive power in front of the focusing position of the relay optical system 3.

[0051] Figure 6C shows another example of the diffusion of image light when microlenses are used. In Figure 6C, the angle at which the image light diffuses is further increased by placing a microlens array 41 with positive refractive power in front of the focusing position of the relay optical system 3 and negative refractive power after the focusing position.

[0052] Figure 6D shows another example of light diffusion when using microlenses. In Figure 6D, by placing a microlens array 41 that eccentricizes the negative refractive force after the focusing position of the relay optical system 3, the angle of light diffusion is increased and the light is emitted at an angle. Note that in Figure 6D, each microlens in the microlens array 41 may be an eccentric lens.

[0053] The head-up display device of this embodiment includes a light source 1, a display panel 2, a relay optical system 3 that projects the image light emitted from the display panel 2, and a diffusion element unit 4 that diffuses the image light projected by the relay optical system 3. Furthermore, a mirror 5 that reflects the image light diffused by the diffusion element unit 4 may also be included. If a mirror 5 is included, the light reflected by the mirror 5 is projected onto a projection member such as a windshield 6 to display a virtual image. If a mirror 5 is not included, the image light diffused by the diffusion element unit 4 is projected onto a projection member such as a windshield 6 to display a virtual image. The diffusion element unit 4 includes a microlens array 41 having a plurality of microlenses, and the optical action of the microlens array 41 differs in the horizontal and vertical directions of the microlens array 41, which correspond to the horizontal and vertical directions of the field of view in which the virtual image can be observed.

[0054] As a result, according to this embodiment, even if the image display element 2 is miniaturized, the optical performance of the projection optical system 20b can be ensured without increasing the number of lenses, and a compact head-up display device can be provided.

[0055] In addition to a transmissive liquid crystal display panel, the image display element 2 may also be a reflective image display element or the like.

[0056] Alternatively, the optical design between the relay optical system 3 and the diffusion element section 4 may be telecentric, or a lenticular lens may be placed directly in front of the diffusion element section 4.

[0057] <Other examples> The basic configuration of the head-up display device 30 will be explained using Figure 8. The head-up display device may also be referred to as a display device, virtual image display device, etc.

[0058] Figure 8 is a schematic diagram of the head-up display device 30. The head-up display device 30 shown in Figure 8 comprises an image forming unit and an image projection unit. In an embodiment of the present invention, the image forming unit has a light source 1 and an image display element or display panel 2. The image projection unit may include a concave lens 10 and a mirror 5. Light is emitted from the light source 1 to the image display element or display panel 2, and then the image light from the display panel 2 is incident on the mirror 5, and the image light emitted from the mirror 5 is reflected by the windshield 6 of a vehicle (for example, the automobile 500 in Figure 3) and incident on the observer's eye 9. In the present invention, the projection of image light onto the windshield 6 of a vehicle is used for explanation, but the projection unit that projects the image light may be a projection member such as a combiner. With this configuration, from the perspective of the observer's eye 9, it appears as if they are viewing image information on a virtual image surface 7.

[0059] In this invention, the mirror 5 functions as an image projection unit that magnifies and reflects the image light from the image display element or display panel 2 in a set angle direction or a predetermined direction. The mirror 5 is, for example, a concave mirror (magnifying mirror) and is provided on the optical path between the image display element or display panel 2 and the windshield 6. The mirror 5 functions as an image light projection unit that projects the image light emitted from the display panel 2 onto the windshield 6, thereby allowing the projected image light to be seen as a virtual image by the eyes 9 of a user such as a driver. The mirror 5 in this embodiment is made of a mirror having a concave reflective surface. The mirror 5 may also be referred to as a reflective element, a reflective mirror, etc.

[0060] The configuration of the head-up display device in this embodiment will be described with reference to Figures 9A and 9B.

[0061] Figures 9A and 9B are configuration and functional block diagrams of the head-up display device of this embodiment. As shown in Figures 9A and 9B, the head-up display device comprises a display panel 2, a light source 1, and a controller 200 that controls their operation. The head-up display device further comprises a relay optical system 3, a diffusion element unit 4, and a concave lens 10. Light is irradiated from the light source 1 onto the display panel 2, and the image information (video information) displayed on the display panel 2 is emitted towards the mirror 5 via the relay optical system 3, the diffusion element unit 4, and the concave lens 10. The light source 1, the display panel 2, the relay optical system 3, and the diffusion element unit 4 and the concave lens 10 may be referred to as an optical system.

[0062] Light source 1 typically includes an LED (Light Emitting Diode) light source, and multiple light sources may be used in an array. The image display element or display panel 2 is typically a liquid crystal display (LCD). The display panel 2 creates an image based on the image data instructed and input from the controller 200 and displays it on the display surface of the display element of the display panel 2. The image display element 2 may also be called a liquid crystal display panel, liquid crystal display element, display element, display panel, etc. Light source 1 may also be called a backlight. The concave lens 10 may also be called an optical element.

[0063] As shown in Figure 9A, in the embodiment of the present invention, the head-up display device 30 is a device equipped with a controller 200. Also, as shown in Figure 9B, if there is no controller 200, the control unit of the automobile can function as the controller 200. When controlled by the control unit of the automobile, the control is substantially the same as the control of the controller 200 of the head-up display device 30, and the following embodiments will be described using the controller 200 of the head-up display device 30. That is, the head-up display device 30 may be equipped with a controller 200, or an externally equipped control device such as an automobile may be used.

[0064] Various types of information are input to this controller 200 from external devices. For example, a navigation device 208 that generates and outputs information about the operation of a mobile body equipped with a head-up display device 30, and an ECU (Electronic Control Unit) 209 that controls the operation of the mobile body are connected to it. Various sensors 210 on the mobile body are connected to the ECU 209 and are configured to notify the ECU 209 of the detected information.

[0065] The controller 200 includes a microcontroller 202 that processes various data from the external devices described above, a storage device 206 connected to the microcontroller 202, and a backlight drive circuit 207 for driving the backlight 1.

[0066] The microcontroller 202 has RAM (Random) for storing various data from external devices. Access Memory)203 and the CPU (Central Processing Unit) which performs the calculations to generate the image data that forms the basis of the virtual image seen by the observer. It includes a CPU 205 (Unit) and a ROM (Read Only Memory) 204 that stores programs and parameters capable of executing arithmetic processing in the CPU 205.

[0067] The controller 200, having the above configuration, displays image information on the image display element 2. The image information displayed on the image display element 2 is emitted as image light towards the mirror 5 via the relay optical system 3, the diffusion element section 4, and the concave lens 10, using light emitted by the backlight 1.

[0068] Returning to Figure 8, the image light emitted from the display panel 2 is projected onto the windshield 6 by the mirror 5. The image light projected from the mirror 5 onto the windshield 6 is reflected by the windshield 6 and reaches the position of the observer's eye 9. This creates a relationship where, from the observer's eye 9's perspective, it is as if they are viewing the image information of the virtual image surface 7. If the mirror 5 is not provided, the image light from the display panel 2 is emitted onto the windshield 6, and the image light emitted onto the windshield 6 is reflected by the windshield 6 and reaches the position of the observer's eye 9.

[0069] As shown in Figure 8, consider virtual points P1, P2, and P3 on the light emission surface of the image display element 2. The light emitted from these virtual points is mapped by the relay optical system 3 to points Q1, Q2, and Q3 on the diffusion element section 4. Considering the virtual points on the virtual image plane 7 corresponding to the light emitted from points Q1, Q2, and Q3, these correspond to points V1, V2, and V3, as shown in Figure 8.

[0070] The eye box 8 is the range in which points V1, V2, and V3 on the virtual image plane 7 can be seen even when the observer moves the position of their eye 9. Thus, a system including the relay optical system 3, the diffusion element section 4, the concave lens 10, and the mirror 5 may be called a projection optical system or projection optical system that displays an image (virtual image) of an object (spatial image) in front of the observer's eye 9. Note that the projection optical system or projection optical system does not necessarily include the mirror 5.

[0071] Here, an example of mounting the head-up display device 30 according to this embodiment on a vehicle or mobile body will be explained using Figure 3.

[0072] Figure 3 is a plan view from the front of a vehicle 500, which is a mobile vehicle equipped with a head-up display device 30. In a vehicle 500 like the one shown in Figure 3, a windshield 6, which is a wind deflector, is located in front of the driver's seat.

[0073] The head-up display device 30 projects image light onto the windshield 6, making various information related to the automobile 500 visible as a virtual image to the driver and observers inside the automobile 500. The image light is projected in front of and around the driver's seat. For example, the image light is projected at the position shown in the dashed rectangular area R1.

[0074] Next, the basic configuration for miniaturizing the image display element 2 in this embodiment will be explained using Figures 4A to 4C. In Figures 4A to 4C, the projection optical system 20b includes a mirror 5 (Figure 9A). In this embodiment, the mirror 5 is a concave mirror and has a light-gathering effect, which is equivalent to the effect of a convex lens. However, the projection optical system 20b is not a convex lens, and in addition to the mirror 5, it may also include a concave lens or other optical components. Similarly, the relay optical system 3 may be composed of multiple lenses, including a field lens. The F-number, which represents the brightness of the optical system, is determined by using θ as F = 1 / 2 / tan(θ / 2). The smaller the F-number, the brighter it is; in other words, the larger the θ, the brighter it is.

[0075] Figure 4A shows a configuration using a standard-sized image display element 2. In Figure 4A, the size of the standard image display element 2 is denoted as A. The F-number, which represents the brightness of the optical system using θ, is determined by F = (focal length) / (pupil diameter = size of eye box 8) = 1 / 2 / tan(θ / 2). A smaller F-number indicates brighter, meaning that a larger θ indicates brighter.

[0076] Figure 4B shows a configuration using a small image display element 2, a relay optical system 3, and a screen plate 4b. In Figure 4B, the size of the image display element 2 is set to A / 3. In Figure 4B, the size of the eye box 8 is secured by mapping the image onto the screen plate 4b using a relay optical system 3 with a magnification of 3x. The angle of the relay optical system 3 on the screen plate 4b side is θ, and the angle of the relay optical system 3 on the image display element 2 side is 3θ, and the F value is F = 1 / 2 / tan(3θ / 2), so the relay optical system 3 has a very large aperture.

[0077] Figure 4C shows a configuration using a small image display element 2, a relay optical system 3, and a diffusion element section 4. In Figure 4C, the size of the image display element 2 is A / 3, but the angle of the relay optical system 3 on the image display element 2 side remains θ, while the angle of the relay optical system 3 on the diffusion element section 4 side is set to θ / 3, and the size of the eye box 8 is secured by diffusing the image light with the diffusion element section 4. The configuration is as follows. The angle θ in Figure 4C consists of light incident from the image display element 2 to the upper part of the relay optical system 3 and light incident to the lower part of the relay optical system 3.

[0078] According to the configuration shown in Figure 4C, a small image display element 2 can be used without increasing the size of the relay optical system 3. Details of this diffusion element section 4 will be explained using Figures 10 to 17. With respect to the vehicle, driver, or viewer, the X-axis is the horizontal direction, left-right direction, lateral direction of the vehicle, or width direction of the vehicle; the Y-axis is the up-down direction, vertical direction, or longitudinal direction of the vehicle; and the Z-axis, which is perpendicular to the lateral direction of the vehicle, is the front-back direction of the vehicle or the direction of travel of the vehicle.

[0079] In Figure 10, the X and Y axes correspond to the horizontal and vertical directions, respectively, of the field of view (eyebox 8) that the observer can observe. The horizontal observation range is larger by the distance between the left and right eyes. For example, eyebox 8 is 130 mm horizontally x 50 mm vertically. Therefore, the side of the diffusion element 4 corresponding to the X-axis direction requires a larger observation range than the side corresponding to the Y-axis direction.

[0080] In Figure 10(1), diffusion occurs between the convex surface on the light-incident side and the concave surface on the light-exit side of the microlens array 41. A light-shielding grating 42a is placed on the light-incident side of the microlens array 41, and a light-shielding grating 42b is placed on the light-exit side of the microlens array 41. Each opening of the light-shielding grating 42a in Figure 10(2) corresponds to each cell of the microlens array 41. Each opening of the light-shielding grating 42a corresponds to each microlens of the microlens array 41, and it shields the light that has spread to the periphery of each cell of the microlens array 41, which is the focused light image (spot) of the light at each cell of the microlens array 41 projected by the relay optical system 3. Although it varies depending on the panel size and resolution, for example, the aperture ratio of each pixel of the image display element 2 is about 50%, so by shielding the light beam of the relay optical system 3 that has spread beyond the magnification, the degradation of resolution is prevented.

[0081] The light-shielding grating and the microlens array are arranged via adhesive or other means. In Figure 10, the diffusion element section 4 may have the microlens array 41 and the light-shielding gratings 42a and 42b as a single integrated structure (holding). Alternatively, the optical design between the relay optical system 3 and the diffusion element section 4 may be telecentric, or a Fresnel lens may be placed directly in front of the diffusion element section 4. The relay optical system 3 is also designed telecentrically so that the same light beam is incident on each microlens of the microlens array 41.

[0082] Next, using Figures 11A and 11B, we will explain the basic concept for achieving different diffusion effects in the X-axis direction (horizontal direction) and Y-axis direction (vertical direction) of the microlens array 41 in order to convert the incident light beam with a circular cross-sectional shape into an exit light beam with a rectangular cross-sectional shape to match the eye box 8.

[0083] Figure 11A is a cross-sectional view of the incident light beam for each microlens in the microlens array 41 of Figure 10(1), showing a mapping with representative points A0 to A5. Similarly, Figure 11B is a cross-sectional view of the outgoing light beam for each microlens in the microlens array 41 of Figure 10(1), showing a mapping with representative points B0 to B5. Since the circular shape is converted to a rectangular shape, there is left-right symmetry and up-down symmetry. In the cross-sectional view of Figure 11A, the center point is A0, and A1 to A5 are arranged at equal intervals around the outer edge of the light beam in the first quadrant (in the range of α = 0 to 90 degrees in the figure). Similarly, since there is left-right symmetry and up-down symmetry, in the cross-sectional view of Figure 11B, the center point is B0, and B1 to B5 are arranged at equal intervals around the outer edge of the light beam in the third quadrant (in the range of α = 180 to 270 degrees in the figure). The reason why the arrangement differs between Figure 11A and Figure 11B is that the light beam is focused within the microlens array 41, so the sign of the values ​​on the X axis and the sign of the values ​​on the Y axis are reversed for the incident and exiting light rays.

[0084] By the way, when converting an incident light beam with a circular cross-section to an outgoing light beam with a rectangular cross-section to match the eye box 8, if the light density is converted to be nearly constant, large variations in brightness are less likely to occur. Therefore, it is necessary to match the area ratio cut from the circular shape with the area ratio of the corresponding rectangular shape. Since it is symmetrical both vertically and horizontally, in order to match the four divisions of the circular shape in Figure 11A (areas of circles cut from arcs A1 to A5 and point A0) with the four divisions of the rectangular shape in Figure 11B (areas of rectangles cut from outer perimeters B1 to B5 and point B0), point A0 in the cross-section of the incident light beam is matched with point B0 in the cross-section of the outgoing light beam, point A1 is matched with point B1, and point A5 is matched with point B5.

[0085] Next, in Figure 11A, point A3 is placed at α=45 degrees, and the line segment A0-A3 further divides the four sections into two, resulting in eight divisions of the original circular area. In Figure 11B, point B3 is placed at the diagonal of the rectangular shape, and the line segment B0-B3 further divides the four sections into two, resulting in eight divisions of the original rectangular area. That is, point A3 in the cross-section of the incident light beam corresponds to point B3 in the cross-section of the emitted light beam. Similarly, in Figure 11A, point A2 is placed at α=22.5 degrees and point A4 is placed at α=67.5 degrees, and the line segments A0-A2 and A0-A4 further divide the eight sections into two, resulting in sixteen divisions of the original circular area. In Figure 11B, point B2 is placed midway between points B1 and B3 of the rectangular shape, and point B4 is placed midway between points B3 and B5. By dividing the 8 divisions with line segments B0-B2 and B0-B4 into two more segments, the area of ​​the original rectangular shape is divided into 16 parts. This can be understood from the fact that points B2 and B4 are the midpoints of the bases of the 8 divided triangles.

[0086] In summary, the light density is uniform at points A1-A5, which are evenly distributed on the outer periphery of the circular cross-section of the incident light beam, and at the outer periphery of the rectangular cross-section of the outgoing light beam. Points A0-A5 in Figure 11A correspond sequentially to points B0-B5 in Figure 11B.

[0087] Next, we will explain the correspondence between the points inside the circular cross-section of the incident luminous beam (Figure 11A) and the points inside the rectangular cross-section of the emitted luminous beam (Figure 11B). In Figure 11A, the circular shape containing points A1 to A5 is reduced to 50% and shown as a dotted line, resulting in a quarter of the original circular area. Similarly, in Figure 11B, the rectangular shape containing points B1 to B5 is reduced to 50% and shown as a dotted line, resulting in a quarter of the original rectangular area. Therefore, we place a sequence of points similar to points A1 to A5 on the dotted circular shape in Figure 11A, and a sequence of points similar to points B1 to B5 on the dotted rectangular shape in Figure 11B, and make the points correspond to each other. In addition, to equalize the ray density across the entire luminous beam, multiple different reduction ratios are used as needed, and the number of points placed on the outer perimeter is increased.

[0088] As described above, by making the relationship between points correspond while maintaining the same area ratio, it is possible to make the light density more uniform in the rectangular shape of the cross-section of the emitted light beam.

[0089] Next, using Figures 12A to 14, we will describe an example of a diffusion element 4 that converts an incident light beam with a circular cross-section into an outgoing light beam with a rectangular cross-section, and also makes the light density more uniform. The microlens of the diffusion element 4 in Figure 12A consists of one free-form surface lens, and Figure 12B is These are the free-form surface coefficients (Equation 1). The incident light beam entering one of these free-form surface lenses and the converted exit light beam will be explained using Figures 13A and 13B.

[0090]

number

[0091] In Figure 13A, the diffusion effect of a rotationally asymmetric free-form lens (Figures 12A and 12B), which has a circular cross-section and is positioned at the focal point of an incident light beam with θ=6 degrees, results in an emitted light beam with a rectangular cross-section and horizontal angles of 18.3 degrees and vertical angles of 5.7 degrees. The size of the image plane is 3226 mm horizontally × 1001 mm vertically, achieving the same ratio as the 130 mm × 40 mm of eye box 8. The reason for leaving a 10 m gap (Figure 12A) in front of and behind the free-form lens is to move the image plane to a distance where the ray height at the free-form lens is negligible compared to the ray height at the image plane, thereby simplifying the representation of the distribution of the light beam emission angle in the spot diagram at the image plane. Accordingly, optical elements are placed immediately in front of and behind the actual free-form lens (microlens array 41) (Figure 8). In this embodiment, a convex Fresnel lens is placed on the reduction side and a concave lens 10 is placed on the magnification side. Figure 13B, for comparison, shows the output light beam with the same incident light beam as Figure 13A, but without the microlens array 41, and is also the incident light beam itself. Therefore, it can be seen that in Figure 13A, the output light beam has a greatly widened output angle in the horizontal direction, and achieves a rectangular cross-section in both the horizontal and vertical directions.

[0092] Figure 14 shows the ray diagrams of the free-form lens in the YZ and XZ sections. The light beam at the incident surface is circular, while the light beam at the exit surface is elongated vertically. The reason there is not even a twofold difference in the size of the light beam at the incident and exit surfaces of the free-form lens is that the free-form lens size is prevented by arranging the microlens array 41 (free-form lens) so that the cross-sectional area of ​​the light beam at the YZ and XZ sections is minimized between the incident and exit surfaces. Furthermore, by aligning the light beam at the exit surface of the free-form lens to a vertically elongated, roughly rectangular shape, and by greatly widening the horizontal diffusion angle through the action of the free-form surface at the exit, a horizontally elongated rectangular shape is achieved at the image plane.

[0093] Next, using Figures 15A to 17 and 7A to 7C, we will describe another example of the diffusion element section 4 that converts an incident light beam with a circular cross-section into an outgoing light beam with a rectangular cross-section, and also makes the light density more uniform. The microlens of the diffusion element section 4 in Figure 15A consists of two free-form lenses, and Figure 15B shows their free-form coefficients (Equation 1). The incident light beam incident on these two free-form lenses and the converted outgoing light beam will be explained using Figures 16A and 16B.

[0094] In Figure 16A, the diffusion effect of a rotationally asymmetric free-form lens (Figures 15A and 15B), which has a circular cross-section and is positioned at the focal point of an incident light beam with θ=4 degrees, results in an emitted light beam with a rectangular cross-section and horizontal angles of 18.5 degrees and vertical angles of 5.8 degrees. The size of the image plane is 3262 mm horizontally × 1010 mm vertically, achieving the same ratio as the 130 mm × 40 mm of eye box 8. The reason for leaving a 10 m gap (Figure 15A) in front of and behind the free-form lens is to move the image plane to a distance where the ray height at the free-form lens is negligible compared to the ray height at the image plane, thereby simplifying the representation of the distribution of the light beam emission angle in the spot diagram at the image plane. Accordingly, optical elements are placed directly in front of and behind the actual free-form lens (microlens array 41) (Figure 8). In this embodiment, a convex Fresnel lens is placed on the reduction side and a concave lens 10 is placed on the magnification side. Figure 16B, for comparison, shows the output light beam with the same incident light beam as Figure 16A, but without the microlens array 41, and is also the incident light beam itself. Therefore, it can be seen that in Figure 16A, the output light beam has a greatly widened output angle in the horizontal direction, and achieves a rectangular cross-section in both the horizontal and vertical directions.

[0095] Figure 17 shows the ray diagrams of the free-form lens in the YZ and XZ sections. The light beam at the incident surface is circular, while the light beam at the exit surface is elongated vertically. The reason the size of the light beam at the incident and exit surfaces of the free-form lens is almost the same is that the microlens array 41 (free-form lens) is arranged so that the cross-sectional area of ​​the light beam at the YZ and XZ sections is minimized between the incident and exit surfaces, thus preventing the free-form lens from becoming too large. Furthermore, by aligning the light beam at the exit surface of the free-form lens to an elongated vertical shape, the horizontal diffusion angle is greatly widened by the action of the free-form surface at the exit surface, thereby achieving a horizontally elongated rectangular shape at the image plane.

[0096] The microlens array 41 has different radii of curvature in the XZ cross-section and the YZ cross-section, and the diffusion angle in the X-axis direction is greater than the diffusion angle in the Y-axis direction. In other words, the divergence effect of each microlens in the microlens array 41 in the horizontal direction (X-axis direction) is greater than the divergence effect of each microlens in the microlens array 41 in the vertical direction (Y-axis direction). Note that the term "diffusion effect" in this invention may also be referred to as "divergence effect".

[0097] The head-up display device of this embodiment includes a light source 1, a display panel 2, a relay optical system 3 that projects the image light emitted from the display panel 2, a diffusion element unit 4 that diffuses the image light projected by the relay optical system 3, and a concave lens 10. Furthermore, a mirror 5 that reflects the light diffused by the diffusion element unit 4 and passed through the concave lens 10 may be included. If a mirror 5 is included, the light reflected by the mirror 5 is projected onto a projection member such as a windshield 6 to display a virtual image. If a mirror 5 is not included, the light emitted from the concave lens 10 is projected onto a projection member such as a windshield 6 to display a virtual image. The diffusion element unit 4 includes a microlens array 41 having a plurality of microlenses, and the optical action of the microlens array 41 differs in the horizontal and vertical directions corresponding to the horizontal and vertical directions of the field of view in which the virtual image can be observed.

[0098] As a result, according to this embodiment, even if the image display element 2 is miniaturized, the optical performance of the projection optical system 20b can be ensured without increasing the number of lenses, and a compact head-up display device can be provided.

[0099] In addition to a transmissive liquid crystal display panel, the image display element 2 may also be a reflective image display element or the like.

[0100] Alternatively, the optical design between the relay optical system 3 and the diffusion element section 4 may be telecentric, or a Fresnel lens may be placed directly in front of the diffusion element section 4.

[0101] The technology described in this embodiment provides an information display device (head-up display device) that can display information necessary for driving, such as navigation information including destination and speed, as well as alert information when oncoming vehicles or pedestrians are detected, in accordance with the actual scenery seen through the windshield. This reduces the driver's eye movement and contributes to supporting safe driving, thereby preventing traffic accidents. This contributes to the United Nations' Sustainable Development Goal (SDG) 3, "Good Health and Well-being." [Explanation of Symbols]

[0102] 1…Light source or backlight, 2…Image display element or display panel, 3…Relay optical system, 4…Diffusion element section, 4b…Screen plate, 5…Mirror, 6…Windshield, 7…Virtual image plane, 8…Eye box, 9…Observer's eye, 20b…Projection optical system, 30…Head-up display device, 41…Microlens array, 42a…Shading grid, 42b…Shading grid, 42c…Shading grid

Claims

1. Display panel and, A light source that supplies light to the display panel, A relay optical system that projects the image light emitted from the display panel, It comprises a diffusion element section that diffuses the image light projected by the relay optical system, The diffusion element section comprises a microlens array and a light-shielding grating positioned on the light-incident side of the microlens array. The aforementioned microlens array is an optical system in which the divergence in the direction corresponding to the viewer's horizontal direction differs from the divergence in the direction corresponding to the viewer's vertical direction.

2. In the optical system according to Claim 1, The microlens array is an optical system having a plurality of microlenses.

3. A display panel and A light source that supplies light to the display panel, A relay optical system that projects the image light emitted from the display panel, It comprises a diffusion element section that diffuses the image light projected by the relay optical system, The diffusion element section comprises a microlens array and light-shielding gratings arranged on the light-incident and light-emitting sides of the microlens array. The aforementioned microlens array is an optical system in which the divergence in the direction corresponding to the viewer's horizontal direction differs from the divergence in the direction corresponding to the viewer's vertical direction.

4. In the optical system described in Claim 3, The microlens array is an optical system having a plurality of microlenses.

5. In the optical system according to claim 4, The aforementioned microlens is an optical system in which the divergence in the direction corresponding to the viewer's horizontal direction is greater than the divergence in the direction corresponding to the viewer's vertical direction.

6. In the optical system according to claim 4, The aforementioned microlenses are eccentric lenses, forming an optical system.

7. In the optical system according to claim 4, An optical system in which the light-shielding grid has an opening, the opening has one or more openings, and the opening corresponds to at least one of the microlenses.

8. A display panel and A light source that supplies light to the display panel, A relay optical system that projects the image light emitted from the display panel, It comprises a diffusion element section that diffuses the image light projected by the relay optical system, The diffusion element section has a microlens array, The aforementioned microlens array is an optical system that has a divergence effect in a direction corresponding to the horizontal direction of the viewer, but does not have a divergence effect in a direction corresponding to the vertical direction of the viewer.

9. Display panel and, A light source that supplies light to the display panel, A relay optical system that projects the image light emitted from the display panel, It comprises a diffusion element section that diffuses the image light projected by the relay optical system, The diffusion element section comprises a microlens array and a light-shielding grating positioned on the light-incident side of the microlens array. The aforementioned microlens array is a head-up display device in which the divergence effect in the direction corresponding to the viewer's horizontal direction differs from the divergence effect in the direction corresponding to the viewer's vertical direction.

10. In the head-up display device according to claim 9, The aforementioned microlens array is a head-up display device having multiple microlenses.

11. A display panel and A light source that supplies light to the display panel, A relay optical system that projects the image light emitted from the display panel, It comprises a diffusion element section that diffuses the image light projected by the relay optical system, The diffusion element section comprises a microlens array and light-shielding gratings arranged on the light-incident and light-emitting sides of the microlens array. The aforementioned microlens array is a head-up display device in which the divergence effect in the direction corresponding to the viewer's horizontal direction differs from the divergence effect in the direction corresponding to the viewer's vertical direction.

12. In the head-up display device according to claim 11, The aforementioned microlens array is a head-up display device having multiple microlenses.

13. In the head-up display device according to claim 12, The aforementioned microlens is a head-up display device in which the divergence effect in the direction corresponding to the viewer's horizontal direction is greater than the divergence effect in the direction corresponding to the viewer's vertical direction.

14. In the head-up display device according to claim 12, The aforementioned microlens is an eccentric lens, in a head-up display device.

15. In the head-up display device according to claim 12, A head-up display device wherein the light-shielding grid has openings, the openings have one or more openings, and the openings correspond to at least one of the microlenses.

16. A display panel and A light source that supplies light to the display panel, A relay optical system that projects the image light emitted from the display panel, It comprises a diffusion element section that diffuses the image light projected by the relay optical system, The diffusion element section has a microlens array, A head-up display device wherein the microlens array has a divergent effect in a direction corresponding to the viewer's horizontal direction, but does not have a divergent effect in a direction corresponding to the viewer's vertical direction.

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