Head-up display device
By intersecting display light at specific cross points within a virtual circle, the head-up display device is miniaturized and reduces optical path interference, addressing space constraints in existing designs.
Patent Information
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- NIPPON SEIKI CO LTD
- Filing Date
- 2025-08-08
- Publication Date
- 2026-05-15
AI Technical Summary
Existing head-up display devices are enlarged due to the need to arrange mirrors without obstructing the optical path, leading to space constraints.
A head-up display device design where the display light intersects at specific cross points, with a portion of the first mirror's reflective surface contained within a virtual circle defined by these cross points, minimizing the mirror's size and reducing interference with other components.
The design allows for miniaturization of the head-up display device and reduces interference with optical path components, enhancing design flexibility.
Smart Images
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Abstract
Description
Technical Field
[0001] The present disclosure relates to a head-up display device.
Background Art
[0002] For example, the head-up display device described in Patent Document 1 includes a display that emits display light, a first mirror that reflects the display light emitted by this display, and a second mirror that reflects the display light reflected by this first mirror. The first mirror causes the reflected display light to cross vertically at a crossing point before reaching the second mirror.
Prior Art Documents
Patent Documents
[0003]
Patent Document 1
Summary of the Invention
Problems to be Solved by the Invention
[0004] In the configuration described in Patent Document 1 above, it is necessary to arrange various members such as the first mirror and the second mirror so as not to obstruct the optical path of the display light, and the head-up display device has been enlarged.
[0005] In view of the above situation, the present disclosure has been made, and an object thereof is to provide a head-up display device that can be miniaturized.
Means for Solving the Problems
[0006] To achieve the above object, a head-up display device according to the present disclosure is a head-up display device that enables a viewer whose viewing point is within a visible region to visually recognize a virtual image by projecting display light onto a projection member, and includes a display unit that emits the display light, and a first mirror having a reflecting surface that reflects the display light emitted from the display unit A second mirror reflects the display light reflected by the first mirror toward the projection member,The display light intersects at a first cross point and a second cross point in a specific direction, and at least a portion of the reflective surface of the first mirror has a diameter equal to the line segment connecting the first cross point and the second cross point. sphere The first cross point is the point where the display light corresponding to the viewpoint of the first end of the visible region in the specific direction intersects, and the second cross point is the point where the display light corresponding to the viewpoint of the second end of the visible region in the specific direction opposite to the first end intersects. [Effects of the Invention]
[0007] According to this disclosure, miniaturization of the head-up display device is possible. [Brief explanation of the drawing]
[0008] [Figure 1] This is a schematic diagram of a vehicle according to one embodiment of the present disclosure. [Figure 2] This is a schematic diagram of a head-up display device according to one embodiment of the present disclosure. [Figure 3] This is a schematic diagram of a head-up display device according to one embodiment of the present disclosure, where the viewpoint is located in the center of the visible area. [Figure 4] This is a schematic diagram of a head-up display device according to one embodiment of the present disclosure, where the viewpoint is located at the upper edge of the visible area. [Figure 5] This is a schematic diagram of a head-up display device according to one embodiment of the present disclosure, where the viewpoint is located at the lower end of the visible area. [Figure 6] This is a schematic diagram showing the optical path of the display light as viewed from the width direction according to one embodiment of the present disclosure. [Figure 7] This is a schematic diagram showing the optical path of the display light as viewed from the width direction in a comparative example. [Figure 8] This is a schematic diagram showing the optical path of the display light as viewed from the width direction, relating to a modified example of this disclosure. [Modes for carrying out the invention]
[0009] One embodiment of the head-up display device relating to this disclosure will be described with reference to the drawings. As shown in Figure 1, the head-up display device 100 is mounted on the dashboard of the vehicle 200. The head-up display device 100 projects display light L onto the windshield 201, which is the projection target, thereby displaying a virtual image V containing vehicle information within the virtual image display area K in a way that is visible to the viewer 1 (for example, the driver of the vehicle 200). The viewer 1 can see the virtual image V when their viewpoints EP1, EP2, and EP3 are within the visible area R.
[0010] As shown in Figure 2, the head-up display device 100 comprises a first mirror 11, a second mirror 12, a display unit 20, and a case 30. The case 30 is formed in a box shape from a light-shielding resin or metal. The first mirror 11, the second mirror 12, and the display unit 20 are housed inside the case 30. The case 30 is provided with a window portion 31 made of a light-transmitting material that transmits the display light L generated in the internal space of the case 30 toward the windshield 201.
[0011] The display unit 20 has a light-emitting surface 21 that emits display light L representing an image. The display unit 20 may be of a type that has a liquid crystal panel and an illumination device, or it may be of a type that has a reflective display element such as a DMD (Digital Micro Mirror Device) element and a projector. In this example, the display unit 20 emits display light L as diffused light. The light emission surface 21 faces the rear upper side of the vehicle. The image displayed on the light emission surface 21 is subjected to distortion correction to correct the distortion of the virtual image V seen by the viewer 1.
[0012] As shown in Figure 2, the first mirror 11 is a curved mirror that curves concavely along the height direction of the vehicle and extends linearly along the width direction of the vehicle. In the width direction of the vehicle, the first mirror 11 may be curved concavely or convexly. The first mirror 11 reflects the display light L emitted from the display unit 20 toward the second mirror 12. The concave curved reflective surface 11a of the first mirror 11 faces the front and lower side of the vehicle.
[0013] As shown in Figures 3, 4, and 5, the first mirror 11 reflects the display light L from the display unit 20 (see Figure 2) toward the second mirror 12 such that it intersects at cross points CP1, CP2, and CP3 in the height direction of the vehicle 200. The cross points CP1, CP2, and CP3 are located between the first mirror 11 and the second mirror 12 in the optical path of the display light L. The display light L converges from the first mirror 11 to the cross points CP1, CP2, and CP3, and then diverges toward the second mirror 12 from the cross points CP1, CP2, and CP3. Although a portion of the display light L intersects at the cross points CP1, CP2, and CP3, the position where the display light L is imaged does not necessarily coincide with the position of the cross points. In the head-up display device 100 of this disclosure, the display light L is imaged at a position different from the cross points between the first mirror 11 and the second mirror 12 in the height direction. The method for setting the positions of cross points CP1, CP2, and CP3 will be explained in detail later.
[0014] As shown in Figure 2, the second mirror 12 is a concave mirror that curves along the height and width directions of the vehicle. The second mirror 12 reflects the display light L reflected from the first mirror 11 toward the windshield 201. The second mirror 12 reflects the display light L from the first mirror 11 toward the windshield 201 in a way that amplifies it. The concave curved reflective surface 12a of the second mirror 12 faces the rear upper side of the vehicle. The second mirror 12 works in cooperation with the first mirror 11 to suppress distortion of the virtual image caused by reflection at the windshield 201.
[0015] Next, we will explain how to set the positions of the cross points CP1, CP2, and CP3, referring to Figures 3, 4, and 5. The positions of the crossing points CP1, CP2, and CP3 on the optical path of the light L are adjusted according to the radius of curvature of the reflecting surface 11a of the first mirror 11 and the divergence angle of the display light L emitted by the display unit 20. For example, as the radius of curvature of the reflecting surface 11a of the first mirror 11 increases, the positions of the crossing points CP1, CP2, and CP3 approach the reflecting surface 11a. Also, as the divergence angle of the display light L emitted by the display unit 20 increases, the positions of the crossing points CP1, CP2, and CP3 approach the reflecting surface 11a. The crossing points CP1, CP2, and CP3 are provided closer to the first mirror 11 than the intermediate position between the first mirror 11 and the second mirror 12.
[0016] Specifically, the crossing points CP1, CP2, and CP3 will be described. As shown in FIG. 4, the crossing point CP2 is the position where the light rays L2T and L2B of the display light L corresponding to the viewpoint EP2 located at the upper end of the visible region R in the height direction intersect when viewed from the width direction. The light ray L2T is the light ray corresponding to the upper end of the virtual image display area K, and the light ray L2B is the light ray corresponding to the lower end of the virtual image display area K. As shown in FIG. 5, the crossing point CP3 is the position where the light rays L3T and L3B of the display light L corresponding to the viewpoint EP3 located at the lower end of the visible region R in the height direction intersect when viewed from the width direction. The light ray L3T is the light ray corresponding to the upper end of the virtual image display area K, and the light ray L3B is the light ray corresponding to the lower end of the virtual image display area K. As shown in FIG. 3, the crossing point CP1 is the position where the light rays L1T and L1B of the display light L corresponding to the viewpoint EP1 located at the center of the visible region R in the height direction intersect when viewed from the width direction. The light ray L1T is the light ray corresponding to the upper end of the virtual image display area K, and the light ray L1B is the light ray corresponding to the lower end of the virtual image display area K. Each of the viewpoints EP1, EP2, and EP3 is located at the center of the visible region R in the width direction of the vehicle.
[0017] The two rays L1T, L1B, L2T, L2B, L3T, and L3B that constitute the crossing points CP1, CP2, and CP3 intersect when viewed two-dimensionally from the width direction. However, in reality, the rays L1T, L1B, L2T, L2B, L3T, and L3B extend into three-dimensional space and do not necessarily intersect at the crossing points CP1, CP2, and CP3. Therefore, in this example, the crossing points CP1, CP2, and CP3 are defined as the intersection points obtained by projecting the rays L1T, L1B, L2T, L2B, L3T, and L3B onto the plane PL on which the line segments of rays L2T and L3B both lie.
[0018] As shown in Figure 6, the cross points CP1, CP2, and CP3 are positioned so that a portion of the reflective surface 11a of the first mirror 11 is contained within a virtual circle C, whose diameter is the line segment connecting the two cross points CP2 and CP3. Cross point CP1 is located at the center of the virtual circle C. The virtual circle C is determined by experiment or simulation.
[0019] In the comparative example in Figure 7, the cross points CP1, CP2, and CP3 are set at positions where the reflective surface 11a of the first mirror 11 is not included within the virtual circle C. In this comparative example, the cross points CP1, CP2, and CP3 are further from the reflective surface 11a compared to the embodiment in Figure 6. Due to the optical path design, it is necessary to form the reflective surface 11a at a position obtained by tracing the direction of propagation of the display light L from the cross points CP2 and CP3 toward the reflective surface 11a in the reverse direction. Therefore, in this comparative example, the size of the reflective surface 11a needs to be increased. As a result, the gap S2 between the upper end of the reflective surface 11a of the first mirror 11 and the display light L reflected by the second mirror 12, in particular the ray L2T, becomes smaller. Therefore, in this comparative example, the size of the reflective surface 11a needs to be increased, and various members such as the mirror holder (not shown) that holds the first mirror 11 may interfere with the optical path of the display light L.
[0020] On the other hand, in this embodiment shown in Figure 6, the cross points CP1, CP2, and CP3 are closer to the reflective surface 11a compared to the comparative example in Figure 7. As a result, as shown in Figure 6, the display light L, particularly ray L2T, does not reach the optional region 11b of the reflective surface 11a, and the display light L, particularly ray L3B, does not reach the optional region 11c of the reflective surface 11a. Therefore, the optional regions 11b and 11c of the reflective surface 11a can be omitted, and the size of the reflective surface 11a can be reduced. Furthermore, the gap S1 between the upper end of the reflective surface 11a of the first mirror 11 and the display light L, particularly the light ray L2T, reflected by the second mirror 12 becomes larger. As a result, interference of the optical path of the display light L by various members such as the mirror holder (not shown) that holds the first mirror 11 can be suppressed.
[0021] (effect) According to the embodiment described above, the following effects are achieved. (1) The head-up display device 100 projects display light L onto a windshield 201, which is an example of a projection target, thereby enabling a viewer 1 whose viewpoints EP1, EP2, and EP3 are within the visible region R to view a virtual image V. The head-up display device 100 includes a display unit 20 that emits display light L, a first mirror 11 having a reflective surface 11a that reflects the display light L emitted from the display unit 20, and a second mirror 12 that reflects the display light L reflected by the first mirror 11 toward the windshield 201. The display light L intersects at cross point CP2, which is an example of a first cross point, and cross point CP3, which is an example of a second cross point, in the height direction, which is an example of a specific direction. A part of the reflective surface 11a of the first mirror 11 is contained within a virtual circle C with a diameter D of the line segment connecting cross points CP2 and CP3. Cross point CP2 is the point where the display light L corresponding to viewpoint EP2 at the first end (upper end) of the visible region R in the height direction intersects. The cross point CP3 is the point where the display light L corresponding to viewpoint EP3 at the second end (lower end) of the visible region R in the height direction intersects. With this configuration, a portion of the reflective surface 11a of the first mirror 11 is included within the virtual circle C, so that the cross points CP2 and CP3 are set close to the reflective surface 11a of the first mirror 11. For this reason, the size of the reflective surface 11a can be reduced. This makes it possible to miniaturize the head-up display device 100. Furthermore, interference between the optical path of the display light L and various components such as the mirror holder (not shown) that holds the first mirror 11 can be suppressed. This increases the design flexibility of the head-up display device 100.
[0022] (2) Crossing points CP2 and CP3 are located between the first mirror 11 and the second mirror 12 in the optical path of the display light L. This configuration allows for miniaturization of the head-up display device 100.
[0023] This disclosure is not limited to the embodiments and drawings described above. Modifications (including the deletion of components) can be made as appropriate, provided they do not alter the essence of this disclosure. An example of such a modification is described below.
[0024] (modified version) In the above embodiment, the cross points CP1, CP2, and CP3 were set between the first mirror 11 and the second mirror 12 in the optical path of the display light L. However, the embodiment is not limited to this, and as shown in Figure 8, they may also be set between the reflective surface 11a and the light emitting surface 21. In this case, the light emitting surface 21 emits display light L that converges to intersect at the cross points CP1, CP2, and CP3 before reaching the reflective surface 11a. Even in this case, a part of the reflective surface 11a of the first mirror 11 is included within a virtual circle C with diameter D being the line segment connecting the two cross points CP2 and CP3. This provides the same effects as in the above embodiment.
[0025] In the above embodiment, the display light L intersected in the height direction of the vehicle 200, but instead of this, or in addition to this, it may intersect in the width direction of the vehicle 200. In this case, the reflective surface 11a of the first mirror 11 is formed in a curved concave shape along the width direction of the vehicle 200. In this modified example as well, at least a portion of the reflective surface 11a is set to be included within a virtual circle identified from the cross point where the lights intersect in the width direction, using the same method as in the above embodiment.
[0026] In the above embodiment, a portion of the reflective surface 11a of the first mirror 11 was included within the virtual circle C when viewed from the width direction, but this is not limited to this, and the entire reflective surface 11a may be included within the virtual circle C. Furthermore, in the above embodiment, the positions of the cross points CP1, CP2, and CP3 were set so that a portion of the reflective surface 11a of the first mirror 11 is included within the virtual circle C. However, from a similar viewpoint, the positions of the cross points CP1, CP2, and CP3 may be set so that a portion of the reflective surface 11a of the first mirror 11 is included within a virtual sphere containing the virtual circle C.
[0027] In the above embodiment, the second mirror 12 may be configured to rotate by a mirror drive unit around a rotation axis along the width direction of the vehicle. By rotating the second mirror 12 around the rotation axis, the position of the illumination of the display light L to the viewer 1 can be adjusted in the height direction. In this case, for example, the cross points CP1, CP2, CP3 and the virtual circle C are identified at the rotation angle of the second mirror 12 where the illumination position of the display light L is at the central position in the height direction.
[0028] In the above embodiment, the head-up display device 100 was mounted in a vehicle, but it is not limited to this and may be mounted in other vehicles such as airplanes or ships. Furthermore, the projected member is not limited to the windshield 201, but may be a dedicated combiner. [Explanation of Symbols]
[0029] 1. Sighted person 11 First Mirror 11a,12a Reflective surface 11b,11c Optional area 12 Second Mirror 20 Display section 21 Light-emitting surface 30 cases 100 Head-Up Display Devices 200 vehicles 201 Windshield C Virtual Yen D diameter K Virtual Image Display Area L display light R visible range S1, S2 gap V Illusion L1B,L2B,L3B,L1T,L2T,L3T rays CP1, CP2, CP3 Crossing Point EP1, EP2, EP3 perspectives PL plane
Claims
1. A head-up display device that projects display light onto a projection target, thereby enabling a viewer whose viewpoint is within the visible area to perceive a virtual image, A display unit that emits the aforementioned display light, A first mirror having a reflective surface that reflects the display light emitted from the display unit, The system comprises a second mirror that reflects the display light reflected by the first mirror toward the projection member, The aforementioned display light intersects at a first cross point and a second cross point in a specific direction. At least a portion of the reflective surface of the first mirror is contained within a virtual sphere whose diameter is the line segment connecting the first cross point and the second cross point. The first cross point is the point where the display light corresponding to the viewpoint of the first end of the visible region in the specific direction intersects, The second cross point is the point where the display light corresponding to the viewpoint of the second end of the visible region in the specific direction, opposite to the first end, intersects. Head-up display device.
2. The first cross point and the second cross point are located between the first mirror and the second mirror in the optical path of the display light, The head-up display device according to claim 1.