WO2024257559A1 - Optical system and head-up display device - Google Patents

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

Optical system and head-up display device

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

Head-up display devices are known that project an image onto the windshield of a moving object such as an automobile or aircraft, allowing the projected image to be viewed as a virtual image through the windshield.

For example, Patent Document 1 discloses a conventional head-up display device that "includes a projection optical system that projects light from behind a transmissive liquid crystal display panel and enlarges and projects the image displayed on the liquid crystal display panel."

JP 2009-229552 A

In the example of a head-up display device disclosed in Patent Document 1, the driver observes a virtual image by projecting an "enlarged real image of the image formed by the relay lens" onto the windshield using a projection lens. In other words, by obtaining an enlarged real image of the liquid crystal display panel using the relay lens, it is possible to use a small liquid crystal display panel.

However, reducing the size of the LCD panel in a head-up display device poses problems that differ from those encountered when reducing the size of a normal optical system. These are explained using Figures 7A, 7B, and 7C.

FIGS. 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 FIGS. 7A to 7C, the projection optical system 20b includes at least the mirror 5 and the windshield 6.

FIG. 7A is a diagram showing an image display element 2 of a reference size. In FIG. 7A, the size of the reference image display element 2 is designated as A. The brightness F value of the projection optical system 20b is determined by F = (focal length) / (pupil diameter = size of eye box 8) = 1/2/tan (θ/2). FIG. 7B is a diagram showing an example of a small image display element 2.

FIG. 7B is a diagram of FIG. 7A miniaturized by being transformed to 1/3 the size, with the size of the image display element 2 being A/3. With the configuration of FIG. 7B, the size of the eye box 8 is also small, so it is not possible to ensure the size of the eye box 8 required for the head-up display device 30. FIG. 7C is a diagram showing another example of a small image display element 2.

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

In other words, if the LCD panel is made smaller, the optical performance of the projection optical system will be significantly degraded, or a larger number of lenses will be required to ensure the optical performance, resulting in a problem of larger size. Furthermore, if only the image display element 2 is made smaller, the virtual image will also become smaller, narrowing the viewing angle of the head-up display device.

The present invention was made in consideration of the above-mentioned circumstances, and aims to provide a small head-up display device.

In order to solve the above problem, one representative head-up display device of the present invention includes a display panel, a light source that supplies light to the display panel, a relay optical system that maps the image light emitted from the display panel, and a diffusion element that diffuses the image light mapped by the relay optical system, and the diffusion element has different optical effects in the horizontal and vertical directions of the diffusion element that correspond to the horizontal and vertical directions of the viewer.

The present invention provides a small head-up display device. Problems, configurations, and advantages other than those described above will become clear from the description of the following embodiment.

FIG. 1 is a schematic configuration diagram of a head-up display device. 1 is a schematic configuration and functional block diagram of a head-up display device. 1 is a schematic configuration and functional block diagram of a head-up display device. FIG. 1 is a plan view of a vehicle, which is a moving object equipped with a head-up display device, as viewed from the front. FIG. 13 is a diagram showing a configuration using a display panel of a standard size. FIG. 1 is a diagram showing a configuration using a display panel, a relay optical system, and a screen plate. FIG. 13 is a diagram showing a configuration using a display panel, a relay optical system, and a diffusion element unit. FIG. 4 is a diagram showing an example of a configuration of a diffusion element portion. 13 is a diagram showing another example of the configuration of the diffusion element portion. FIG. 13 is a diagram showing another example of the configuration of the diffusion element portion. FIG. FIG. 13 is a diagram showing the diffusion of image light when no microlenses are used. FIG. 13 is a diagram showing an example of diffusion of image light when a microlens is used. 13A and 13B are diagrams illustrating another example of diffusion of image light when a microlens is used. 13A and 13B are diagrams illustrating another example of diffusion of image light when a microlens is used. 1A to 1C are diagrams illustrating an example of a projection optical system depending on the size of a display panel. 1A to 1C are diagrams illustrating an example of a projection optical system depending on the size of a display panel. 1A to 1C are diagrams illustrating an example of a projection optical system depending on the size of a display panel. FIG. 1 is a schematic configuration diagram of a head-up display device. 1 is a schematic configuration and functional block diagram of a head-up display device. 1 is a schematic configuration and functional block diagram of a head-up display device. 3A and 3B are diagrams illustrating the basic configuration and function of a diffusion element portion. FIG. 13 is a diagram showing mapping of incident light rays on a diffusion element portion. FIG. 13 is a diagram showing mapping of emitted light rays from a diffusion element portion. FIG. 11 is a diagram showing an example of lens data of a diffusion element portion. FIG. 13 is a diagram showing an example of free-form surface coefficients of a diffusion element portion. FIG. 13 is a diagram showing an example of diffusion of image light when a microlens is used. FIG. 13 is a diagram showing an example of diffusion of image light, with the same incident light as that shown in FIG. 1A and 1B are diagrams showing examples of ray diagrams in the YZ section and the XZ section of a free curved lens; FIG. 13 is a diagram showing another example of lens data of the diffusion element portion. FIG. 11 is a diagram showing another example of the free-form surface coefficients of the diffusion element portion. 13A and 13B are diagrams illustrating another example of diffusion of image light when a microlens is used. 13 is a diagram showing another example of diffusion of image light, with the same incident light as that of the image light without a microlens. FIG. 11A and 11B are diagrams showing another example of ray diagrams in the YZ section and the XZ section of the free curved lens.

Below, an embodiment of the present invention and various examples will be explained using drawings etc. The following explanations show specific examples of the contents of the present invention, and the present invention is not limited to these explanations. Various changes and modifications are possible by those skilled in the art within the scope of the technical ideas disclosed in this specification. Furthermore, in all figures used to explain the examples, parts having the same function are given the same reference numerals, and repeated explanations may be omitted.

The basic configuration of the head-up display device 30 will be described using FIG. 1. The head-up display device may also be called a display device, a virtual image display device, etc.

1 is a schematic diagram of a head-up display device 30. The head-up display device 30 shown in FIG. 1 includes an image forming unit and an image projection unit. In an embodiment of the present invention, the image forming unit includes a light source 1 and an image display element or display panel 2. The image projection unit may include a mirror 5. The light source 1 emits light 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 FIG. 3) and incident on the observer's eye 9. In the present invention, the projection of the image light onto the windshield 6 of the vehicle is described, but the projection unit that projects the image light may be a projection member such as a combiner. With this configuration, when viewed from the observer's eye 9, it appears as if the observer is viewing image information on the virtual image plane 7.

In the present 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 direction at a set angle or in a specified 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 causing the projected image light to be visually recognized as a virtual image by the eye 9 of a user such as a driver. The mirror 5 in this embodiment is composed of a mirror having a concave reflective surface.

The configuration of the head-up display device of this embodiment will be explained with reference to Figure 2.

2A and 2B are configuration and functional block diagrams of the head-up display device of this embodiment. As shown in FIGS. 2A and 2B, the head-up display device includes a display panel 2, a light source 1, and a controller 200 that controls the operations of these components. The head-up display device further includes a relay optical system 3 and a diffusion element unit 4. Light is irradiated from the light source 1 to the display panel 2, and image information (video information) displayed on the display panel 2 is emitted toward the mirror 5 via the relay optical system 3 and the diffusion element unit 4. The combination of the light source 1, the display panel 2, the relay optical system 3, and the diffusion element unit 4 may be referred to as an optical system.

The light source 1 is typically configured to include an LED (Light Emitting Diode) light source, and multiple light sources may be arranged for use. The image display element or display panel 2 is typically a liquid crystal panel (Liquid Crystal Display: LCD). The display panel 2 creates an image based on image data input instructed by 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 be referred to as a liquid crystal display panel, liquid crystal display element, display element, display panel, etc. The light source 1 may also be referred to as a backlight.

As shown in FIG. 2A, in an embodiment of the present invention, the head-up display device 30 is a device equipped with a controller 200. Also, as shown in FIG. 2B, if the controller 200 is not provided, it is possible for the control unit of the automobile to function as the controller 200. When controlled by the control unit of the automobile, the control is almost the same as that of the controller 200 of the head-up display device 30, and the following embodiment will be described using the controller 200 of the head-up display device 30. In other words, the head-up display device 30 may be equipped with the controller 200, or an external control device such as an automobile may be used.

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

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

The microcomputer 202 is equipped with a RAM (Random Access Memory) 203 for storing various data from external devices, a CPU (Central Processing Unit) 205 for performing calculations to generate image data that is the basis of the virtual image viewed by the observer, and a ROM (Read Only Memory) 204 for storing programs and parameters that can execute the calculations in the CPU 205.

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 by the light emitted by the backlight 1 through the relay optical system 3 and the diffusion element section 4 towards the mirror 5.

Returning to FIG. 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 as if the observer's eye 9 were looking at the image information on the virtual image surface 7. Note that 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.

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

The eyebox 8 is the range in which points V1, V2, and V3 on the virtual image plane 7 can be seen even if the observer moves the position of the eye 9. In this way, the relay optical system 3, the diffusion element section 4, and the mirror 5 may be called a 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 does not have to include the mirror 5.

Here, an example of a case where the head-up display device 30 according to this embodiment is mounted on a vehicle or moving object will be described with reference to FIG. 3.

FIG. 3 is a plan view of an automobile 500, which is a moving body equipped with a head-up display device 30, as seen from the front. In the automobile 500 shown in FIG. 3, a windshield 6, which is a front glass used as a windshield, is disposed in front of the driver's seat.

The head-up display device 30 projects image light onto the windshield 6, allowing the driver and observers in the vehicle 500 to view various information related to the vehicle 500 as virtual images. The image light is projected onto the front of the driver's seat or its surroundings. For example, the image light is projected onto the position shown in the dashed rectangular area R1.

Next, the basic configuration for miniaturizing the image display element 2 in this embodiment will be described with reference to 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-collecting effect, so it has the same effect as a convex lens. However, the projection optical system 20b is not a convex lens, and the optical components may include a concave lens in addition to the mirror 5. The relay optical system may also be the same, and may be composed of multiple lenses including a field lens. Note that by using θ, the F-number, which represents the brightness of the optical system, is determined by F = 1/2/tan (θ/2). The smaller the F-number, the brighter the image, i.e., the larger θ, the brighter the image.

Fig. 4A is a diagram showing a configuration using an image display element 2 of a standard size. In Fig. 4A, the size of the standard image display element 2 is designated as A. Using θ, the F-number, which represents the brightness of the optical system, is determined as F = (focal length) / (pupil diameter = size of eye box 8) = 1/2/tan (θ/2). The smaller the F-number, the brighter the image; in other words, the larger θ, the brighter the image.

Fig. 4B is a diagram showing a configuration using a small image display element 2, relay optical system 3, and screen plate 4b. In Fig. 4B, the size of the image display element 2 is A/3. In Fig. 4B, a relay optical system 3 with a magnification of 3x is used to map onto the screen plate 4b, ensuring the size of the eyebox 8. The angle of the relay optical system 3 on the screen plate 4b side is θ, the angle of the relay optical system 3 on the image display element 2 side is 3θ, and the F-number is F = 1/2/tan (3θ/2), so the relay optical system 3 has a very large aperture.

Fig. 4C is a diagram showing a configuration using a small image display element 2, relay optical system 3, and diffusion element section 4. In Fig. 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, and the angle of the relay optical system 3 on the diffusion element section 4 side is set to θ/3, and the diffusion element section 4 diffuses the image light, ensuring the size of the eye box 8. The angle θ in Fig. 4C is made up of the light entering the upper part of the relay optical system 3 from the image display element 2 and the light entering the lower part of the relay optical system 3.

The configuration of Fig. 4C makes it possible to use a small image display element 2 without enlarging the relay optical system 3. Details of this diffusion element section 4 will be described with reference to Figs. 5A to 5C. Note that with respect to the vehicle, driver or viewer, the X-axis is the horizontal direction, left-right direction, lateral direction or width direction of the vehicle, the Y-axis is the up-down direction, vertical direction or length direction of the vehicle, and the Z-axis, which is perpendicular to the lateral direction of the vehicle, is the front-rear direction of the vehicle or the traveling direction of the vehicle.

In Figures 5A to 5C, the X-axis and Y-axis correspond to the horizontal and vertical directions of the field of view (eye box 8) that the observer can observe. In the horizontal direction, the observation range is larger by the distance between the left and right eyes. For example, the eye box 8 is 130 mm horizontally and 50 mm vertically. Therefore, the side of the diffusion element 4 that corresponds to the X-axis direction requires a larger observation range than the side that corresponds to the Y-axis direction. Also, if the microlens is a cylinder lens, the radius of curvature of the cylinder lens can only be seen from a specific direction, for example, when the light incident side of the microlens array 41 is viewed from the left or right, and the light exit side of the microlens array 41 is viewed from above or below.

In Figure 5A, the light incident side of the microlens array 41 is flat, and the light exit 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 exit 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 flat, and the light exit side of the microlens array 41 diffuses light in the horizontal direction.

5A(1) to 5A(3) are diagrams showing an example of the configuration of the diffusion element section 4. In FIG. 5A, the diffusion element section 4 includes a microlens array 41 and a light-shielding grating 42a. The light-shielding grating and the microlens array are arranged via an adhesive or a holding section. The microlens array 41 has one or more microlenses. The light-shielding grating 42a has one or more openings and is arranged on the light-emitting side of the microlens array 41. The microlens array 41 also corresponds to the openings of the light-shielding grating 42a. One microlens may correspond to one opening, or one or more microlenses may correspond to one opening, and there is no particular limitation. In other words, the light-shielding grating has an opening, the opening has one or more openings, and the opening corresponds to at least one microlens. In this embodiment, the openings of the light-shielding grating for performing the shielding action 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.

In FIG. 5A, the light incident side of the microlens array 41 is flat, and the light exit side of the microlens array 41 diffuses light in both the vertical and horizontal directions. 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 of the microlens array 41 in the horizontal direction (X-axis direction) is greater than the divergence effect of each microlens of the microlens array 41 in the vertical direction (Y-axis direction). Note that the "diffusion effect" in this invention may also be referred to as a "divergence effect".

For example, a toroidal lens or a free-form lens can be used as the microlens. Each opening of the light-shielding grid 42a corresponds to each lens of the microlens array 41, and blocks light that spreads to the periphery of each cell in the focused image (spot) of light in each cell of the microlens array 41 mapped by the relay optical system 3. Although it differs 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 degradation of resolution is prevented by blocking the light beam of the relay optical system 3 that spreads beyond the magnification.

Fig. 5B(1) to Fig. 5B(4) are diagrams showing another example of the configuration of the diffusion element section 4. In Fig. 5A, the light-shielding grating 42a is arranged on the light-emitting side of the microlens array 41, but in Fig. 5B, the light-shielding grating 42c is arranged on the light-incident side of the microlens array 41, and the light-shielding grating 42b is arranged on the light-emitting side of the microlens array 41. The light-shielding grating and the microlens array are arranged by bonding or via a structure, etc.

In the microlens array 41 of FIG. 5B, the microlenses on the light incident side diffuse light in the Y-axis direction, and the microlenses on the light exit side diffuse light in the X-axis direction. A light-shielding grating 42b is arranged in the X-axis direction, and a light-shielding grating 42c is arranged in the Y-axis direction. Alternatively, in FIG. 5B, the light incident side of the microlens array 41 diffuses light in the vertical direction, and the light exit side of the microlens array 41 diffuses light in the horizontal direction. Also, while FIG. 5B shows a light-shielding grating arranged in the direction of diffusion, the light-shielding grating 42a of FIG. 5A may also be used.

FIGS. 5C(1) to 5C(3) are diagrams showing another example of the configuration of the diffusion element section 4. The microlens array 41 in FIG. 5C has a shape with a radius of curvature only in the X-axis direction, and for example, a cylindrical lens array or a free-form lens array can be used. In FIG. 5C, the incident side of the microlens array 41 is flat, and the exit side of the microlens array 41 diffuses light in the horizontal direction. The microlens array 41 in FIG. 5C has a diffusing effect only in the X-axis direction. In other words, each microlens of the microlens array 41 has a diverging effect only in the horizontal direction (X-axis). Therefore, in FIG. 5C, a light-shielding grating 42b that has a shading effect only in the Y-axis direction is arranged on the light exit side.

The light-shielding grating 42b in Fig. 5C may have a shape that has a shielding effect only in the Y-axis direction, or the light-shielding grating 42a in Fig. 5A may be used. Also, the microlens array 41 shown in Figs. 5A to 5C may be configured to have different divergence effects on the light incident side and the light exit side.
5A to 5C, the diffusion element unit 4 may have a structure (holding) the microlens array 41 and the light-shielding gratings 42a, 42b, and 42c as an integral unit. Each microlens of the microlens array 41 may have a diffusion effect on at least one of the light entrance surface side and the light exit surface side of the diffusion element unit. In addition, between the relay optical system 3 and the diffusion element unit 4, a telecentric optical design may be performed, or a lenticular lens may be disposed immediately before the diffusion element unit 4.

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 the image light is incident on the microlens array 41 from the relay optical system 3 side.

FIG. 6A is a diagram showing the diffusion of image light when no microlenses are used. FIG. 6A shows the case where the microlens array 41 is not used as a reference, and the shape of the image light on the image display element side or relay optical system side is approximately the same as that on the Eyebox side.

FIG. 6B is a diagram showing an example of the diffusion of image light when a microlens is used. In FIG. 6B, a microlens array 41 with positive refractive power is placed in front of the focusing position of the relay optical system 3, thereby increasing the angle at which the image light is diffused.

FIG. 6C is a diagram showing another example of diffusion of image light when microlenses are used. In FIG. 6C, a microlens array 41 with positive refractive power is placed in front of the focusing position of the relay optical system 3 and with negative refractive power is placed behind the focusing position, thereby further increasing the angle at which the image light is diffused.

FIG. 6D is a diagram showing another example of diffusion of image light when microlenses are used. In FIG. 6D, a microlens array 41 with a decentered negative refractive power is placed after the focusing position of the relay optical system 3, thereby increasing the angle at which the image light is diffused and emitting the light at an angle. Note that in FIG. 6D, each microlens of the microlens array 41 may be a decentered lens.

The head-up display device of this embodiment includes a light source 1, a display panel 2, a relay optical system 3 that maps the image light emitted from the display panel 2, and a diffusion element unit 4 that diffuses the image light mapped by the relay optical system 3. A mirror 5 that reflects the image light diffused by the diffusion element unit 4 may also be included. When the 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. When the mirror 5 is not included, the image light diffused by the diffusion element unit 4 is output to 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 microlens array 41 has different optical effects 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.

As a result, according to this embodiment, even if the image display element 2 is made smaller, the optical performance of the projection optical system 20b can be ensured without increasing the number of lenses, making it possible to provide a compact head-up display device.

In addition, the image display element 2 may be a reflective image display element in addition to a transmissive liquid crystal display panel.

Furthermore, between the relay optical system 3 and the diffusion element section 4, a telecentric optical design may be used, or a lenticular lens may be placed immediately before the diffusion element section 4.

<Other Examples>
A basic configuration of the head-up display device 30 will be described with reference to Fig. 8. The head-up display device may be called a display device, a virtual image display device, or the like.

8 is a schematic diagram of a head-up display device 30. The head-up display device 30 shown in FIG. 8 includes an image forming unit and an image projection unit. In an embodiment of the present invention, the image forming unit includes 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. The light source 1 emits light 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 FIG. 3) and incident on the observer's eye 9. In the present invention, the projection of the image light onto the windshield 6 of the vehicle is described, but the projection unit that projects the image light may be a projection member such as a combiner. With this configuration, when viewed from the observer's eye 9, it appears as if the observer is viewing image information on the virtual image plane 7.

In the present 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 specified 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 causing the projected image light to be visually recognized as a virtual image by the eye 9 of a user such as a driver. The mirror 5 in this embodiment is composed of a mirror having a concave reflective surface. The mirror 5 may also be called a reflective element, a reflective mirror, etc.

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

9A and 9B are configuration and functional block diagrams of the head-up display device of this embodiment. As shown in FIGS. 9A and 9B, the head-up display device includes a display panel 2, a light source 1, and a controller 200 that controls the operations of these components. The head-up display device further includes a relay optical system 3, a diffusion element section 4, and a concave lens 10. Light is irradiated from the light source 1 to the display panel 2, and image information (video information) displayed on the display panel 2 is emitted toward the mirror 5 via the relay optical system 3, the diffusion element section 4, and the concave lens 10. The combination of the light source 1, the display panel 2, the relay optical system 3, the diffusion element section 4, and the concave lens 10 may be referred to as an optical system.

The light source 1 is typically configured to include an LED (Light Emitting Diode) light source, and multiple light sources may be arranged for use. The image display element or display panel 2 is typically a liquid crystal panel (Liquid Crystal Display: LCD). The display panel 2 creates an image based on image data input instructed by 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 be called a liquid crystal display panel, liquid crystal display element, display element, display panel, etc. The light source 1 may also be called a backlight. The concave lens 10 may also be called an optical element.

As shown in FIG. 9A, in an embodiment of the present invention, the head-up display device 30 is a device equipped with a controller 200. Also, as shown in FIG. 9B, if the controller 200 is not provided, it is possible for the control unit of the automobile to function as the controller 200. When controlled by the control unit of the automobile, the control is almost the same as that of the controller 200 of the head-up display device 30, and the following embodiment will be described using the controller 200 of the head-up display device 30. In other words, the head-up display device 30 may be equipped with the controller 200, or an external control device such as an automobile may be used.

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

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

The microcomputer 202 is equipped with a RAM (Random Access Memory) 203 for storing various data from external devices, a CPU (Central Processing Unit) 205 for performing calculations to generate image data that is the basis of the virtual image viewed by the observer, and a ROM (Read Only Memory) 204 for storing programs and parameters that can execute the calculations in the CPU 205.

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 by the light irradiated by the backlight 1 through the relay optical system 3, the diffusion element section 4, and the concave lens 10 toward the mirror 5.

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 as if the observer's eye 9 were looking at the image information on the virtual image surface 7. Note that 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.

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

The eyebox 8 is the range in which points V1, V2, and V3 on the virtual image plane 7 can be seen even if the observer moves the position of the eye 9. In this way, 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 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 does not have to include the mirror 5.

Here, an example of a case where the head-up display device 30 according to this embodiment is mounted on a vehicle or moving object will be described with reference to FIG. 3.

FIG. 3 is a plan view of an automobile 500, which is a moving body equipped with a head-up display device 30, as seen from the front. In the automobile 500 shown in FIG. 3, a windshield 6, which is a front glass used as a windshield, is disposed in front of the driver's seat.

The head-up display device 30 projects image light onto the windshield 6, allowing the driver and observers in the vehicle 500 to view various information related to the vehicle 500 as virtual images. The image light is projected onto the front of the driver's seat or its surroundings. For example, the image light is projected onto the position shown in the dashed rectangular area R1.

Next, the basic configuration for miniaturizing the image display element 2 in this embodiment will be described with reference to 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-collecting effect, so it has the same effect as a convex lens. However, the projection optical system 20b is not a convex lens, and the optical components may include a concave lens in addition to the mirror 5. Similarly, the relay optical system 3 may be composed of multiple lenses including a field lens. Note that by using θ, the F-number, which represents the brightness of the optical system, is determined by F = 1/2/tan (θ/2). The smaller the F-number, the brighter the image, i.e., the larger θ, the brighter the image.

Fig. 4A is a diagram showing a configuration using an image display element 2 of a standard size. In Fig. 4A, the size of the standard image display element 2 is designated as A. Using θ, the F-number, which represents the brightness of the optical system, is determined as F = (focal length) / (pupil diameter = size of eye box 8) = 1/2/tan (θ/2). The smaller the F-number, the brighter the image; in other words, the larger θ, the brighter the image.

Fig. 4B is a diagram showing a configuration using a small image display element 2, relay optical system 3, and screen plate 4b. In Fig. 4B, the size of the image display element 2 is A/3. In Fig. 4B, a relay optical system 3 with a magnification of 3x is used to map onto the screen plate 4b, ensuring the size of the eyebox 8. The angle of the relay optical system 3 on the screen plate 4b side is θ, the angle of the relay optical system 3 on the image display element 2 side is 3θ, and the F-number is F = 1/2/tan (3θ/2), so the relay optical system 3 has a very large aperture.

Fig. 4C is a diagram showing a configuration using a small image display element 2, relay optical system 3, and diffusion element section 4. In Fig. 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, and the angle of the relay optical system 3 on the diffusion element section 4 side is set to θ/3, and the diffusion element section 4 diffuses the image light, ensuring the size of the eye box 8. The angle θ in Fig. 4C is made up of the light entering the upper part of the relay optical system 3 from the image display element 2 and the light entering the lower part of the relay optical system 3.

The configuration of Fig. 4C makes it possible to use a small image display element 2 without enlarging the relay optical system 3. Details of this diffusion element section 4 will be described with reference to Figs. 10 to 17. Note that with respect to the vehicle, driver or viewer, the X-axis is the horizontal direction, left-right direction, lateral direction or width direction of the vehicle, the Y-axis is the up-down direction, vertical direction or length direction of the vehicle, and the Z-axis, which is perpendicular to the lateral direction of the vehicle, is the front-rear direction of the vehicle or the direction of travel of the vehicle.

In FIG. 10, the X-axis and Y-axis correspond to the horizontal and vertical directions of the field of view (eye box 8) that the observer can observe. In the horizontal direction, the observation range is larger by the distance between the left and right eyes. For example, the eye box 8 is 130 mm horizontally and 50 mm vertically. Therefore, the side of the diffusion element 4 that corresponds to the X-axis direction requires a larger observation range than the side that corresponds to the Y-axis direction.

In FIG. 10(1), the convex surface on the light incident side of the microlens array 41 and the concave surface on the light exit side of the microlens array 41 perform the diffusion effect. A light-shielding grating 42a is arranged on the light incident side of the microlens array 41, and a light-shielding grating 42b is arranged on the light exit side of the microlens array 41. Each cell of the microlens array 41 corresponds to each opening of the light-shielding grating 42a in FIG. 10(2). Each opening of the light-shielding grating 42a corresponds to each microlens of the microlens array 41, and blocks light that spreads to the periphery of each cell from the focused image (spot) of light in each cell of the microlens array 41 mapped by the relay optical system 3. Although it differs 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 that the deterioration of the resolution is prevented by blocking the light beam of the relay optical system 3 that spreads more than the magnification.

The light-shielding grating and the microlens array are arranged by bonding or via a structure. In FIG. 10, the diffusion element section 4 may have a structure (holding) the microlens array 41 and the light-shielding gratings 42a, 42b as an integrated unit. In addition, a telecentric optical design may be used between the relay optical system 3 and the diffusion element section 4, or a Fresnel lens may be placed just before the diffusion element section 4. The relay optical system 3 is also designed to be telecentric, so that light beams of the same conditions are incident on each microlens of the microlens array 41.

Next, the basic idea of 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 an incident light beam with a circular cross-sectional shape into an outgoing light beam with a rectangular cross-sectional shape to match the eyebox 8 will be explained using Figures 11A and 11B.

FIG. 11A is a cross-sectional view of the incident light beams for each microlens of the microlens array 41 in FIG. 10(1), and shows a mapping in which A0 to A5 are assigned to representative points. Similarly, FIG. 11B is a cross-sectional view of the exiting light beams for each microlens of the microlens array 41 in FIG. 10(1), and shows a mapping in which B0 to B5 are assigned to representative points. Since the circular shape is converted into a rectangular shape, it is symmetrical from left to right and from top to bottom, so in the cross-sectional view of FIG. 11A, the center point is A0, and A1 to A5 are arranged at equal intervals on the outer periphery of the light beam in the first quadrant (α = 0 to 90 degrees in the figure). Similarly, since it is symmetrical from left to right and from top to bottom, in the cross-sectional view of FIG. 11B, the center point is B0, and B1 to B5 are arranged at equal intervals on the outer periphery of the light beam in the third quadrant (α = 180 to 270 degrees in the figure). The reason why the placement locations are different in Figures 11A and 11B is that the light beam is focused inside the microlens array 41, so the signs of the values on the X-axis are reversed between the incident light beam and the outgoing light beam, and the signs of the values on the Y-axis are reversed.

When converting an incident light beam with a circular cross section into an exiting light beam with a rectangular cross section to fit the eye box 8, if the light density is converted to be approximately constant, large unevenness in brightness is less likely to occur. Therefore, it is necessary to match the area ratio cut out from the circular shape with the area ratio of the corresponding rectangular shape. Since it is symmetrical top to bottom and left to right, in order to match the four divisions of the circular shape in Figure 11A (the area of the circle cut out by arcs A1-A5 and point A0) with the four divisions of the rectangular shape in Figure 11B (the area of the rectangle cut out by the perimeters B1-B5 and point B0), point A0 on the cross section of the incident light beam is made to correspond to point B0 on the cross section of the exiting light beam, point A1 is made to correspond to point B1, and point A5 is made to correspond to point B5.

Next, in Figure 11A, point A3 is placed at α = 45 degrees, and the line segment A0-A3 further divides the four divisions into two, resulting in eight divisions of the area of the original circular shape. In Figure 11B, point B3 is placed at the diagonal of the rectangular shape, and the line segment B0-B3 further divides the four divisions into two, resulting in eight divisions of the area of the original rectangular shape. In other words, point A3 on the cross section of the incident light beam corresponds to point B3 on the cross section of the outgoing 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 segment A0-A2 and line segment A0-A4 further divide the eight divisions into two, resulting in 16 divisions of the area of the original circular shape. In Figure 11B, point B2 is placed halfway between points B1 and B3 of the rectangular shape, and point B4 is placed halfway between points B3 and B5. The eight-division area is then further divided into two parts by line segments B0-B2 and B0-B4, resulting in a 16-division of the area of the original rectangular shape. This can also be understood from the fact that points B2 and B4 are the midpoints of the bases of the triangles divided into eight parts.

As described above, the points A1 to A5 are evenly spaced around the outer periphery of the circular cross section of the incident light beam, and the light density around the outer periphery of the rectangular cross section of the exiting light beam is uniform, and points A0 to A5 in Figure 11A correspond in order to points B0 to B5 in Figure 11B.

Next, the correspondence between the points inside the circular shape of the cross section of the incident light beam (Fig. 11A) and the points inside the rectangular shape of the cross section of the outgoing light beam (Fig. 11B) will be described. In Fig. 11A, the circular shape including points A1 to A5 is reduced by 50% to become the circular shape shown by the dotted line, which has a quarter of the area of the original circle. Similarly, in Fig. 11B, the rectangular shape including points B1 to B5 is reduced by 50% to become the rectangular shape shown by the dotted line, which has a quarter of the area of the original rectangle. Therefore, a sequence of points similar to points A1 to A5 is placed on the dotted circular shape in Fig. 11A, and a sequence of points similar to points B1 to B5 is placed on the dotted rectangular shape in Fig. 11B to make the points correspond to each other. Note that in order to make the light density of the entire light beam uniform, different reduction ratios are used as necessary, and the number of points placed on the periphery is increased.

As described above, by matching the points while keeping the area ratio the same, it is possible to make the light density closer to uniform in the rectangular shape of the cross section of the emitted light beam.

Next, using Figures 12A to 14, we will explain 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 makes the light density closer to uniform. The microlens of the diffusion element 4 in Figure 12A is composed of a single free-form lens, and Figure 12B shows its free-form surface coefficients (Equation 1). The incident light beam that enters this single free-form lens and the converted outgoing light beam will be explained using Figures 13A and 13B.

In Fig. 13A, the diffusion effect of a rotationally asymmetric free-form lens (Figs. 12A and 12B) arranged at the focusing position of the incident light beam with a circular cross section at θ = 6 degrees realizes an exit light beam with a rectangular cross section at a horizontal angle of 18.3 degrees and a vertical angle of 5.7 degrees. The size of the image plane is 3226 mm horizontal x 1001 mm vertical, which realizes the same ratio as the eye box 8 of 130 mm x 40 mm. The reason for leaving a gap of 10 m (Fig. 12A) in front of and behind the free-form lens is to simply show the distribution of the exit angle of the light beam on the image plane in the spot diagram by separating the image plane to a distance where the height of the light beam on the free-form lens can be ignored compared to the height of the light beam on the image plane. Therefore, optical elements are arranged immediately before and after the actual free-form lens (microlens array 41) (Fig. 8). In this embodiment, a convex Fresnel lens is arranged on the reduction side, and a concave lens 10 is arranged on the enlargement side. For comparison, Figure 13B shows the same incident light beam as Figure 13A, but shows the emitted light beam without the microlens array 41, and is also the incident light beam itself. Therefore, in Figure 13A, it can be seen that the emitted light beam has a large emission angle in the horizontal direction, and has a rectangular cross section in the horizontal and vertical directions.

Figure 14 is a ray diagram at the YZ cross section and XZ cross section of a free-form lens, where the light beam at the entrance surface is circular and the light beam at the exit surface is elongated. The size of the light beam at the entrance surface and exit surface of the free-form lens is less than twice as large because the cross-sectional area of the light beam at the YZ cross section and the XZ cross section is minimized between the entrance surface and exit surface of the microlens array 41 (free-form lens), preventing the free-form lens from becoming too large. The light beam at the exit surface of the free-form lens is aligned into a vertically elongated rectangular shape, and the free-form surface at the exit surface greatly expands the horizontal diffusion angle, thereby realizing a horizontally elongated rectangular shape on the image plane.

Next, using Figures 15A to 17 and Figures 7A to 7C, we will explain another 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 makes the light density closer to uniform. The microlens of the diffusion element 4 in Figure 15A is composed of two free-form lenses, and Figure 15B shows the free-form surface coefficients (Equation 1). The incident light beam that enters these two free-form lenses and the converted outgoing light beam will be explained using Figures 16A and 16B.

In Fig. 16A, the diffusion effect of a rotationally asymmetric free-form lens (Figs. 15A and 15B) arranged at the focusing position of the incident light beam with a circular cross section at θ = 4 degrees realizes an exit light beam with a rectangular cross section at a horizontal angle of 18.5 degrees and a vertical angle of 5.8 degrees. The size of the image plane is 3262 mm horizontal x 1010 mm vertical, which realizes the same ratio as the eye box 8 of 130 mm x 40 mm. The reason for leaving a gap of 10 m (Fig. 15A) in front of and behind the free-form lens is to simply show the distribution of the exit angle of the light beam on the image plane in the spot diagram by separating the image plane to a distance where the height of the light beam at the free-form lens can be ignored compared to the height of the light beam on the image plane. Therefore, optical elements are arranged immediately before and after the actual free-form lens (microlens array 41) (Fig. 8). In this embodiment, a convex Fresnel lens is arranged on the reduction side, and a concave lens 10 is arranged on the enlargement side. For comparison, Figure 16B shows the same incident light beam as Figure 16A, but shows the emitted light beam without the microlens array 41, and is also the incident light beam itself. Therefore, in Figure 16A, it can be seen that the emitted light beam has a large emission angle in the horizontal direction, and has a rectangular cross section in the horizontal and vertical directions.

Figure 17 is a ray diagram at the YZ cross section and XZ cross section of a free-form lens, where the light beam at the entrance surface is circular and the light beam at the exit surface is elongated. The size of the light beam at the entrance surface and exit surface of the free-form lens is approximately the same because the cross-sectional area of the light beam at the YZ cross section and the XZ cross section between the entrance surface and exit surface of the microlens array 41 (free-form lens) is minimized, preventing the free-form lens from becoming too large. The light beam at the exit surface of the free-form lens is aligned into a vertically elongated shape, and the free-form surface at the exit surface greatly expands the horizontal diffusion angle, thereby achieving a horizontally elongated rectangular shape on the image plane.

The microlens array 41 has a different radius 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 of the microlens array 41 in the horizontal direction (X-axis direction) is greater than the divergence effect of each microlens of the microlens array 41 in the vertical direction (Y-axis direction). Note that the "diffusion effect" in this invention may also be referred to as a "divergence effect."

The head-up display device of this embodiment includes a light source 1, a display panel 2, a relay optical system 3 that maps the image light emitted from the display panel 2, a diffusion element unit 4 that diffuses the image light mapped by the relay optical system 3, and a concave lens 10. A mirror 5 that reflects the light diffused by the diffusion element unit 4 and passing through the concave lens 10 may also be included. When the 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. When the mirror 5 is not included, the light emitted from the concave lens 10 is emitted 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 microlens array 41 has different optical effects in the horizontal and vertical directions of the microlens array 41, which correspond to the horizontal and vertical directions of the visual field range in which the virtual image can be observed.

As a result, according to this embodiment, even if the image display element 2 is made smaller, the optical performance of the projection optical system 20b can be ensured without increasing the number of lenses, making it possible to provide a compact head-up display device.

In addition, the image display element 2 may be a reflective image display element in addition to a transmissive liquid crystal display panel.

Furthermore, the optical design between the relay optical system 3 and the diffusion element section 4 can be telecentric, or a Fresnel lens can be placed immediately before the diffusion element section 4.

The technology according to this embodiment can display navigation information such as destination and speed, as well as information necessary for driving such as alert information when an oncoming vehicle or pedestrian is detected, in line with the actual view through the windshield. This can prevent traffic accidents by providing an information display device (head-up display device) that reduces the driver's viewpoint movement and contributes to supporting safe driving. This contributes to "Good health and well-being for all," one of the Sustainable Development Goals (SDGs) advocated by the United Nations.

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 surface, 8...eye box, 9...observer's eye, 20b...projection optical system, 30...head-up display device, 41...microlens array, 42a...light-shielding grating, 42b...light-shielding grating, 42c...light-shielding grating

Claims (47)

A display panel;
a light source for supplying light to the display panel;
a relay optical system that maps an image of the image light emitted from the display panel;
a diffusion element unit that diffuses the image light projected by the relay optical system,
The optical system has different optical effects in the horizontal and vertical directions of the diffusion element portion, which correspond to the horizontal and vertical directions of the viewer. 2. The optical system according to claim 1,
The diffusion element portion includes a microlens array,
The microlens array has different divergence effects in the horizontal and vertical directions. 3. The optical system according to claim 2,
The microlens array is an optical system having different divergence effects on the light incident surface side and the light exit surface side. 3. The optical system according to claim 2,
The diffusion element portion is an optical system having a light-shielding grating arranged on the light exit side of the microlens array. 3. The optical system according to claim 2,
The diffusion element portion is an optical system having a light-shielding grating arranged on the light incident side of the microlens array. 3. The optical system according to claim 2,
The diffusion element portion is an optical system having a light-shielding grating arranged on the light incident side and the light exit side of the microlens array. 3. The optical system according to claim 2,
The microlens array includes a plurality of microlenses. 8. The optical system according to claim 7,
An optical system, wherein the microlenses have a divergence effect in the horizontal direction that is greater than the divergence effect in the vertical direction. 8. The optical system according to claim 7,
The optical system, wherein the microlens is a decentered lens. 8. The optical system according to claim 7,
The diffusion element portion includes a light-shielding grating,
The optical system, wherein the light blocking grating has an opening, the opening having one or more apertures, the apertures corresponding to at least one of the microlenses. 3. The optical system according to claim 2,
An optical system, wherein the microlens array has a diverging effect only in the horizontal direction. 3. The optical system according to claim 2,
The microlens array is an optical system having a diverging effect on at least one of a light incident surface side and a light exit surface side of the diffusion element portion. A display panel;
a light source for supplying light to the display panel;
a relay optical system that maps an image of the image light emitted from the display panel;
a diffusion element unit that diffuses the image light projected by the relay optical system,
A head-up display device, wherein the diffusion element portion has different optical effects in the horizontal and vertical directions of the diffusion element portion, which correspond to the horizontal and vertical directions of a viewer. The head-up display device according to claim 13,
The diffusion element portion includes a microlens array,
The microlens array has different divergence effects in the horizontal and vertical directions. The head-up display device according to claim 14,
The microlens array has different divergence effects on the light incident surface side and the light exit surface side. The head-up display device according to claim 14,
A head-up display device, wherein the diffusion element portion has a light-shielding grid arranged on the light-exiting side of the microlens array. The head-up display device according to claim 14,
The diffusion element portion has a light-shielding grating arranged on the light incident side of the microlens array. The head-up display device according to claim 14,
The diffusion element portion has a light-shielding grating arranged on the light incident side and the light exit side of the microlens array. The head-up display device according to claim 14,
A head-up display device, wherein the microlens array has a plurality of microlenses. The head-up display device according to claim 19,
A head-up display device, wherein the microlens has a diverging effect in the horizontal direction that is greater than the diverging effect in the vertical direction. The head-up display device according to claim 19,
A head-up display device, wherein the microlens is a decentered lens. The head-up display device according to claim 19,
The diffusion element portion includes a light-shielding grating,
A head-up display device, wherein the light-shielding grid has an opening, the opening having one or more openings, the opening corresponding to at least one of the microlenses. The head-up display device according to claim 14,
A head-up display device, wherein the microlens array has a diverging effect only in the horizontal direction. The head-up display device according to claim 14,
A head-up display device, wherein the microlens array has a diverging effect on at least one of a light entrance surface side and a light exit surface side of the diffusion element portion. A display panel;
a light source for supplying light to the display panel;
a relay optical system that maps an image of the image light emitted from the display panel;
a diffusion element unit that diffuses the image light projected by the relay optical system;
a reflecting element that reflects the image light diffused by the diffusion element portion,
The optical system has different optical effects in the horizontal and vertical directions of the diffusion element portion, which correspond to the horizontal and vertical directions of the viewer. 26. The optical system according to claim 25,
the diffusion element portion includes a microlens array having a plurality of microlenses;
An optical system, in which, in a horizontal cross section of the optical path from the light incident surface side to the light exit surface side of each microlens of the microlens array, there is a position where the light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than the light flux size at the light incident surface side of each microlens and the light flux size at the light exit surface side of each microlens. 26. The optical system according to claim 25,
the diffusion element portion includes a microlens array having a plurality of microlenses;
An optical system, in which, in a vertical cross section of the optical path from the light incident surface side to the light exit surface side of each microlens of the microlens array, there is a position where the light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than the light flux size at the light incident surface side of each microlens and the light flux size at the light exit surface side of each microlens. 27. The optical system according to claim 26,
An optical system in which, in the horizontal direction of the diffusion element portion, the intersection point between the horizontal coordinates on the light incident surface side of each microlens of the microlens array and the horizontal coordinates on the light exit surface side of each microlens of the microlens array is different. 28. The optical system according to claim 27,
An optical system in which, in the vertical direction of the diffusion element portion, the intersection point between the vertical coordinate on the light incident surface side of each microlens of the microlens array and the vertical coordinate on the light exit surface side of each microlens of the microlens array is different. 26. The optical system according to claim 25,
The cross section of the light beam incident on the diffusion element portion is circular,
The optical system wherein a cross section of a light beam emitted from the diffusion element portion is rectangular. 31. The optical system according to claim 30,
An optical system in which the ratio of an area obtained by dividing the circular shape is the same as the ratio of an area obtained by dividing the rectangular shape. 26. The optical system according to claim 25,
the diffusion element portion includes a microlens array having a plurality of microlenses;
in a horizontal cross section of an optical path from a light incident surface side to a light exit surface side of each microlens of the microlens array, there is a position where a light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than a light flux size at the light incident surface side and the light exit surface side of each microlens,
An optical system, in which, in a vertical cross section of the optical path from the light incident surface side to the light exit surface side of each microlens of the microlens array, there is a position where the light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than the light flux size at the light incident surface side and the light exit surface side of each microlens. 33. The optical system according to claim 32,
When the horizontal direction of the diffusion element is defined as the X-axis, the vertical direction is defined as the Y-axis, and the optical axis of each microlens of the microlens array is defined as the Z-axis,
an optical system in which, in an optical path between the light incident surface side and the light exit surface side of each microlens of the microlens array, an intersection between an X coordinate on the light incident surface side and the light exit surface side of each microlens of the microlens array has an opposite sign, and an intersection between a Y coordinate on the light incident surface side and the light exit surface side of each microlens of the microlens array has an opposite sign. 33. The optical system according to claim 32,
The cross section of the light beam incident on the diffusion element portion is circular,
The optical system wherein a cross section of a light beam emitted from the diffusion element portion is rectangular. 35. The optical system according to claim 34,
When the horizontal direction of the diffusion element is defined as the X-axis, the vertical direction is defined as the Y-axis, and the optical axis of each microlens of the microlens array is defined as the Z-axis,
The intersections of the circular ray and the rectangular ray with the X-axis have opposite signs, and the intersections of the circular ray and the rectangular ray with the Y-axis have opposite signs,
An optical system in which the ratio of an area obtained by dividing the circular shape is the same as the ratio of an area obtained by dividing the rectangular shape. A display panel;
a light source for supplying light to the display panel;
a relay optical system that maps an image of the image light emitted from the display panel;
a diffusion element unit that diffuses the image light projected by the relay optical system;
a reflecting element that reflects the image light diffused by the diffusion element portion,
A head-up display device, wherein the diffusion element portion has different optical effects in the horizontal and vertical directions of the diffusion element portion, which correspond to the horizontal and vertical directions of a viewer. 37. The head-up display device according to claim 36,
the diffusion element portion includes a microlens array having a plurality of microlenses;
A head-up display device, wherein in a horizontal cross section of the optical path from the light incident surface side to the light exit surface side of each microlens of the microlens array, there is a position where the light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than the light flux size at the light incident surface side of each microlens and the light flux size at the light exit surface side of each microlens. 37. The head-up display device according to claim 36,
the diffusion element portion includes a microlens array having a plurality of microlenses;
A head-up display device, wherein in a vertical cross section of the optical path from the light incident surface side to the light exit surface side of each microlens of the microlens array, there is a position where the light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than the light flux size at the light incident surface side of each microlens and the light flux size at the light exit surface side of each microlens. 38. The head-up display device according to claim 37,
A head-up display device in which, in the horizontal direction of the diffusion element portion, the intersection point between the horizontal coordinate on the light incident surface side of each microlens of the microlens array and the horizontal coordinate on the light exit surface side of each microlens of the microlens array is different. 39. The head-up display device according to claim 38,
A head-up display device in which, in the vertical direction of the diffusion element portion, the intersection point between the vertical coordinate on the light incident surface side of each microlens of the microlens array and the vertical coordinate on the light exit surface side of each microlens of the microlens array is different. 37. The head-up display device according to claim 36,
The cross section of the light beam incident on the diffusion element portion is circular,
A head-up display device, wherein a cross section of the light beam emitted from the diffusion element portion is rectangular. 42. The head-up display device according to claim 41,
A head-up display device in which the ratio of an area obtained by dividing the circular shape is the same as the ratio of an area obtained by dividing the rectangular shape. 37. The head-up display device according to claim 36,
the diffusion element portion includes a microlens array having a plurality of microlenses;
in a horizontal cross section of an optical path from a light incident surface side to a light exit surface side of each microlens of the microlens array, there is a position where a light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than a light flux size at the light incident surface side and the light exit surface side of each microlens,
A head-up display device, in which, in a vertical cross section of the optical path from the light incident surface side to the light exit surface side of each microlens of the microlens array, there is a position where the light flux size between the light incident surface side and the light exit surface side of each microlens is smaller than the light flux size at the light incident surface side and the light exit surface side of each microlens. 44. The head-up display device according to claim 43,
When the horizontal direction of the diffusion element is defined as the X-axis, the vertical direction is defined as the Y-axis, and the optical axis of each microlens of the microlens array is defined as the Z-axis,
A head-up display device, wherein in the optical paths between the light incident surface side and the light exit surface side of each microlens of the microlens array, the intersections between the X coordinates on the light incident surface side and the light exit surface side of each microlens of the microlens array have opposite signs, and the intersections between the Y coordinates on the light incident surface side and the light exit surface side of each microlens of the microlens array have opposite signs. 37. The head-up display device according to claim 36,
The cross section of the light beam incident on the diffusion element portion is circular,
A head-up display device, wherein a cross section of the light beam emitted from the diffusion element portion is rectangular. 46. The head-up display device according to claim 45,
the diffusion element unit includes a microlens array having a plurality of microlenses, and when the horizontal direction of the diffusion element unit is defined as an X-axis, the vertical direction is defined as a Y-axis, and the optical axis of each microlens of the microlens array is defined as a Z-axis,
The intersections of the circular ray and the rectangular ray with the X-axis have opposite signs, and the intersections of the circular ray and the rectangular ray with the Y-axis have opposite signs,
A head-up display device in which the ratio of an area obtained by dividing the circular shape is the same as the ratio of an area obtained by dividing the rectangular shape. 46. The head-up display device according to claim 45,
a divided area of a cross section of a light beam incident on the diffusion element portion having a circular shape and a divided area of a cross section of a light beam emitted from the diffusion element portion having a rectangular shape are set to the same ratio;
A head-up display device that associates points on each divided cross section of a circular shape with points on each divided cross section of a rectangular shape.

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