Image display device

Abstract

If the HUD is positioned too far forward in the vehicle, there is a risk that it may interfere with other components such as the front panel. [Solution] The image display device according to this disclosure comprises an image generation unit that generates an image and emits image light of the image, and an optical system that irradiates a projection unit with the image light emitted from the image generation unit. The optical system has a first reflecting unit that reflects the image light emitted from the image generation unit, and a second reflecting unit that reflects the image light reflected by the first reflecting unit toward the projection unit. The second reflecting unit is composed of a plane mirror.

Description

Technical Field

[0001] The present invention relates to an image display device.

Background Art

[0002] Patent Document 1 discloses a head-up display (hereinafter referred to as HUD) that displays a virtual image by reflecting light irradiated by an image irradiation unit onto a windshield with a concave mirror.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the case of a vehicle with a shallow windshield tilt angle, compared to a vehicle with a deep windshield tilt angle, it is necessary to place the HUD closer to the front side of the vehicle. However, if the HUD is placed closer to the front side of the vehicle, there is a risk that the HUD will interfere with other components such as the front panel.

[0005] An object of the present invention is to make it easier to place the HUD on the front side of the vehicle.

Means for Solving the Problems

[0006] One aspect of the present invention for achieving the above object is an image generation unit that generates an image and emits image light of the image, an optical system that irradiates the image light emitted from the image generation unit onto a projection unit, and the optical system includes a first reflection unit that reflects the image light emitted from the image generation unit, A second reflecting unit that reflects the image light reflected by the first reflecting unit toward the projection unit, It has, The image display device is characterized in that the second reflective section is composed of a plane mirror.

[0007] Further issues disclosed in this application, and methods for solving them, will be made clear in the section on embodiments for carrying out the invention and in the drawings. [Effects of the Invention]

[0008] According to the present invention, it is possible to easily position the HUD on the front side of the vehicle. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is an explanatory diagram of HUD10. [Figure 2] Figures 2A and 2B are explanatory diagrams illustrating the placement of the HUD10. [Figure 3] Figure 3 is a comparative explanatory diagram of the arrangement of the second reflector 12B. [Modes for carrying out the invention]

[0010] Hereinafter, embodiments for carrying out the present invention will be described with reference to the drawings. In the following description, identical or similar components may be denoted by the same reference numerals, and redundant descriptions may be omitted.

[0011] ===Implementation Method=== <Overall Structure> Figure 1 is an explanatory diagram of HUD10.

[0012] In the following explanation, we may use the directions shown in Figure 1. Note that "front" and "rear" are defined according to the front and rear of the vehicle. Additionally, "up" and "down" are defined along the vertical direction.

[0013] The HUD10 is an image display device mounted in the vehicle that displays a virtual image 40 in front of the vehicle. The HUD10 is a so-called head-up display. The HUD10 projects image light onto the projection unit 31. The image light reflected by the projection unit 31 enters the driver's eyes, allowing the driver to see the virtual image 40 displayed in front of the vehicle through the projection unit 31. The projection unit 31 transmits light from outside the vehicle while reflecting image light from the HUD10. The projection unit 31 is the vehicle's windshield and functions as a transmissive reflector (a so-called half-mirror). The driver sees the background visible through the projection unit 31 superimposed with the virtual image 40 (spatial image) created by the image light reflected by the projection unit 31.

[0014] The HUD 10 includes an image generation unit 11, an optical system 12, a drive mechanism 13, a HUD-side control unit 14, and a housing 15.

[0015] The image generation unit 11 generates an image to be projected onto the projection unit 31. The image generation unit 11 in the figure is composed of a liquid crystal display equipped with a liquid crystal display unit 11A and a backlight 11B. As the liquid crystal display unit 11A displays an image, the backlight 11B irradiates light from the back of the liquid crystal display unit 11A, causing image light to be emitted from the image generation unit 11. Note that the image generation unit 11 is not limited to a liquid crystal display; it can be any device that can generate an image and emit image light. For example, the image generation unit 11 may be composed of an organic EL display device, a micro LED display device, or a projector device using a laser light source.

[0016] The optical system 12 irradiates the projection unit 31 with the image light emitted from the image generation unit 11. The optical system 12 includes a first reflection unit 12A and a second reflection unit 12B. The first reflection unit 12A is an optical element that reflects the image light emitted from the image generation unit 11. As will be described later, the first reflection unit 12A is configured to be rotatable. The second reflection unit 12B is an optical element that reflects the image light reflected by the first reflection unit 12A toward the projection unit 31. The second reflection unit 12B is disposed on the side closer to the projection unit 31 than the first reflection unit 12A (when the image generation unit 11 is the upstream side of the optical path, it is on the downstream side of the optical path from the first reflection unit 12A). Also, the second reflection unit 12B is disposed in front of the first reflection unit 12A. By having the first reflection unit 12A and the second reflection unit 12B in the optical system 12, the optical path between the image generation unit 11 and the projection unit 31 is folded, and the HUD 10 can be downsized.

[0017] The first reflection unit 12A is configured by a concave mirror. The first reflection unit 12A has a concave reflecting surface. The reflecting surface of the first reflection unit 12A is configured by a spherical surface, an aspherical surface, or a free-form surface. By including a concave mirror in the optical system 12, it is possible to set the distance between the virtual image 40 displayed in front of the vehicle and the driver's eyes to be long, and to shorten the optical path of the image light to downsizing the HUD 10. The first reflection unit 12A (concave mirror) is a curved plate-like member, and the surface opposite to the reflecting surface is configured to be convex.

[0018] The second reflection unit 12B is configured by a plane mirror. The second reflection unit 12B has a flat reflecting surface. The second reflection unit 12B (plane mirror) is configured by a flat plate-like member, and the surface opposite to the reflecting surface is also configured to be flat. The reason why the second reflection unit 12B is configured by a plane mirror will be described later.

[0019] The drive mechanism 13 is a mechanism for rotating the first reflection part 12A. The drive mechanism 13 has a motor 13A and a gear 13B. By rotating the gear 13B by the driving force of the motor 13A, the first reflection part 12A rotates. In response to the rotation of the first reflection part 12A, the display position of the virtual image 40 is adjusted. The drive mechanism 13 is disposed on the rear side of the first reflection part 12A (the opposite side of the reflection surface of the first reflection part 12A).

[0020] The HUD side control unit 14 controls the HUD 10. The HUD side control unit 14 controls the image generation unit 11. Specifically, the HUD side control unit 14 outputs image data to the liquid crystal display unit 11A and controls the image to be displayed on the liquid crystal display unit 11A. Further, the HUD side control unit 14 outputs a drive signal to the backlight 11B and controls the ON / OFF of the backlight 11B and the brightness of the backlight 11B. The HUD side control unit 14 controls the drive mechanism 13. Specifically, the HUD side control unit 14 outputs a drive signal to the motor 13A and controls the rotation position of the first reflection part 12A. Note that the HUD side control unit 14 controls the image generation unit 11 and the drive mechanism 13 based on the image data and control data received from the vehicle side control unit 20.

[0021] The HUD side control unit 14 is composed of a computer including an arithmetic processing unit and a storage device not shown. The arithmetic processing unit is composed of a CPU, MPU, GPU, etc. The storage device is composed of a ROM, RAM, etc. Various processes performed by the HUD side control unit 14 are realized by the arithmetic processing unit executing a program stored in the storage device.

[0022] The housing 15 is a component that constitutes the exterior of the HUD 10. The housing 15 houses the other components of the HUD 10. Specifically, the housing 15 houses the image generation unit 11, the optical system 12, the drive mechanism 13, and the HUD-side control unit 14. The housing 15 is provided with an opening 15A. Image light is irradiated from the opening 15A toward the projection unit 31. The housing 15 is positioned below the upper surface of the vehicle's dashboard 32. An opening is also formed in the upper surface of the dashboard 32 to allow image light to pass through.

[0023] Figures 2A and 2B are explanatory diagrams for the arrangement of the HUD 10. Figure 2A is an explanatory diagram for the arrangement of the HUD 10 when the tilt angle of the projection unit 31 is large. Figure 2B is an explanatory diagram for the arrangement of the HUD 10 when the tilt angle of the projection unit 31 is small. The tilt angle of the projection unit 31 is the angle of the projection unit 31 with respect to the horizontal direction in the area to which the image light is irradiated. In Figure 2A, a projection unit 31 with a tilt angle of 30 degrees is shown as an example. In Figure 2B, a projection unit 31 with a tilt angle of 20 degrees is shown as an example.

[0024] As shown in Figure 2A, in typical vehicles, the inclination angle of the projection section 31 is mainly around 30 degrees. However, in recent years, due to improvements in aerodynamic performance and design, there has been a trend towards smaller inclination angles of the projection section 31, as shown in Figure 2B. In the case of vehicles with a small inclination angle of the projection section 31, as shown in Figure 2B, the HUD 10 needs to be positioned closer to the front of the vehicle in order for the driver to be able to see the virtual image 40, compared to vehicles with a large inclination angle. However, if the HUD 10 is positioned below the top surface of the dashboard 32 and is positioned closer to the front of the vehicle (in other words, if the HUD 10 occupies the space below the dashboard 32 at the front of the vehicle), the HUD 10 may interfere with other parts such as the front panel (parts located below the dashboard 32 at the front of the vehicle). Furthermore, as shown in Figure 2B, in the case of a vehicle with a small inclination angle of the projection section 31, the second reflecting section 12B will be positioned in an upright position so that the normal to the reflective surface of the second reflecting section 12B approaches the horizontal direction, compared to a vehicle with a large inclination angle.

[0025] Figure 3 is a comparative diagram illustrating the arrangement of the second reflector 12B. The upper part of the figure shows the optical system 12 of this embodiment, illustrating the arrangement of the second reflector 12B when the second reflector 12B is a plane mirror. The lower part of the figure shows the optical system 12' of a comparative example, illustrating the arrangement of the second reflector 12B' when the second reflector 12B' is a concave mirror.

[0026] As already explained, in the case of a vehicle with a small tilt angle of the projection section 31, the second reflecting section 12B is positioned upright so that the normal to the reflective surface of the second reflecting section 12B approaches the horizontal direction (see Figure 2B). As a result, as shown in the comparative example (lower side of Figure 3), when the second reflecting section 12B' is a concave mirror, the portion P' below the upper end P of the second reflecting section 12B' protrudes forward of the upper end P of the second reflecting section 12B'. In other words, when the second reflecting section 12B' is a concave mirror, the portion P' below the upper end P of the second reflecting section 12B' becomes the foremost portion of the optical system 12'.

[0027] In contrast, when the second reflector 12B is a plane mirror, as in this embodiment (upper side of Figure 3), the upper end P of the second reflector 12B becomes the foremost part of the optical system 12. In other words, by configuring the second reflector 12B with a plane mirror as in this embodiment, the foremost part of the optical system 12 can be moved back compared to the case where the second reflector 12B' is a concave mirror, as in the comparative example. The figure shows that in this embodiment, the foremost part of the optical system 12 can be moved back by a length X compared to the comparative example. Thus, by configuring the second reflector 12B with a plane mirror, the expansion of the HUD 10's occupied area (the area occupied by the housing 15) forward can be suppressed, making it easier to position the HUD 10 closer to the front of the vehicle. For this reason, in this embodiment, as shown in Figure 1, the second reflector 12B is configured with a plane mirror.

[0028] As the second reflecting section 12B is composed of a plane mirror, in this embodiment the first reflecting section 12A is composed of a concave mirror. This allows a concave mirror to be provided in the optical system 12, making it possible to set a longer distance between the virtual image 40 and the driver's eye, and also shortening the optical path of the image light, thereby enabling miniaturization of the HUD 10.

[0029] The first reflector 12A is configured to be rotatable in order to adjust the display position of the virtual image 40. It is also possible to adjust the display position of the virtual image 40 by rotating the second reflector 12B. However, if the second reflector 12B is configured to be rotatable, the position of the upper end of the second reflector 12B (the foremost part of the optical system 12) changes, causing the occupied area of ​​the HUD 10 to expand forward. In contrast, in a structure in which the display position of the virtual image 40 is adjusted by fixing the second reflector 12B and rotating the first reflector 12A, the position of the upper end of the second reflector 12B (the foremost part of the optical system 12) does not change, so the expansion of the occupied area of ​​the HUD 10 forward can be suppressed, and a structure can be made in which the HUD 10 can be easily positioned closer to the front of the vehicle.

[0030] Furthermore, the drive mechanism 13 for rotating the first reflector 12A is located on the opposite side of the reflective surface of the first reflector 12A. In other words, the drive mechanism 13 for rotating the first reflector 12A is located behind the first reflector 12A. This prevents the drive mechanism 13 from expanding the area occupied by the HUD 10 forward.

[0031] As already explained, when the inclination angle of the projection section 31 is 20 degrees or less, the second reflecting section 12B is positioned upright as shown in Figure 2B. If the second reflecting section 12B is composed of a concave mirror, the part below the upper end of the second reflecting section 12B tends to protrude forward of the upper end of the second reflecting section 12B, as shown in Figure 3. For this reason, a structure in which the second reflecting section 12B is composed of a plane mirror is particularly effective when the inclination angle of the projection section 31 is 20 degrees or less.

[0032] The image generation unit 11 is positioned behind the second reflective section 12B. If the image generation unit 11 were positioned in front of the second reflective section 12B, the area occupied by the housing 15 that houses the image generation unit 11 would expand forward, and the area occupied by the HUD 10 would also expand forward. In contrast, by positioning the image generation unit 11 behind the second reflective section 12B, the expansion of the HUD 10's area forward can be suppressed, making it easier to position the HUD 10 closer to the front of the vehicle.

[0033] Furthermore, the image unit is positioned between the first reflector 12A (specifically, the rearmost part of the first reflector 12A; the lower end of the first reflector 12A in Figure 1) and the second reflector 12B (specifically, the frontmost part of the first reflector 12A; the upper end of the second reflector 12B in Figure 1) in the front-to-back direction. This allows the dimensions of the HUD 10 in the front-to-back direction to be suppressed, and the optical path is folded, enabling miniaturization of the HUD 10.

[0034] Although embodiments of the present invention have been described in detail above, the present invention is not limited to the above embodiments and includes various modifications. Furthermore, the above embodiments are described in detail to explain the configuration in an easy-to-understand manner and are not necessarily limited to those having all the configurations described. In addition, some of the configurations of the above embodiments can be added to, deleted from, or replaced with other configurations. [Explanation of Symbols]

[0035] 10 HUD (Image Display Device), 11 Image Generation Unit, 11A LCD display unit, 11B backlight, 12 Optical system, 12A first reflection section, 12B second reflection section, 13 Drive mechanism, 13A motor, 13B gear, 14 HUD side control unit, 15 housing, 15A opening, 20 Vehicle-side control unit, 31 Projection unit, 32 Dashboard, 40 Illusion

Claims

1. An image generation unit that generates an image and emits image light from the said image, An optical system that irradiates the projection unit with the image light emitted from the image generation unit, Equipped with, The optical system described above is A first reflecting unit that reflects the image light emitted from the image generation unit, A second reflecting unit that reflects the image light reflected by the first reflecting unit toward the projection unit, It has, The image display device is characterized in that the second reflective section is composed of a plane mirror.

2. An image display device according to claim 1, The image display device is characterized in that the first reflective section is composed of a concave mirror.

3. An image display device according to claim 1 or 2, The first reflecting part is configured to be rotatable, An image display device characterized in that the display position of the image is adjusted in accordance with the rotation of the first reflecting part.

4. An image display device according to claim 3, The image display device is characterized in that the drive mechanism for rotating the first reflecting portion is located on the opposite side of the reflective surface of the first reflecting portion.

5. An image display device according to claim 1 or 2, An image display device characterized in that the inclination angle of the projection portion with respect to the horizontal direction is 20 degrees or less.

6. An image display device according to claim 1 or 2, The image display device is characterized in that the image generation unit is positioned behind the second reflective section.

7. An image display device according to claim 6, The image display device is characterized in that the image generation unit is arranged between the first reflective portion and the second reflective portion in the front-rear direction.

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