Head-up display device

Abstract

To provide a head-up display device capable of further improving display quality.SOLUTION: The head-up display device displays a virtual image by projecting display light L onto a windshield. The head-up display device includes a display 11 for emitting display light L, and a concave mirror 30 for reflecting the display light L. The display 11 is provided in a direction inclined with respect to the X direction corresponding to the lateral direction of the virtual image in the direction orthogonal to the optical axis center Lc of the display light L.SELECTED DRAWING: Figure 2

Description

[Technical Field]

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

[0002] Patent document 1 discloses a correction means for offsetting distortion of a virtual image caused by the curved shape of the windshield in a head-up display device that displays a virtual image on a vehicle windshield. Examples of this correction means include correction using a free-form concave mirror that offsets distortion of the virtual image, and correction by deforming the displayed image to offset distortion of the virtual image (correction by image warping) (see paragraph 0004 of Patent document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2023 / 286742 Summary of the Invention [Problem to be solved by the invention]

[0004] Even with the above-described correction means, there is still room for improvement in the display quality of the virtual image.

[0005] The present disclosure has been made in consideration of the above-described circumstances, and aims to provide a head-up display device that can further improve display quality. [Means for solving the problem]

[0006] In order to achieve the above object, a head-up display device according to the present disclosure includes: A head-up display device that displays a projection image by projecting display light onto a projection target, a display panel that emits the display light; a curved mirror that reflects the display light, The display panel is provided in a direction inclined with respect to a reference direction corresponding to the lateral direction of the projected image, among directions orthogonal to the center of the optical axis of the display light. [Effects of the Invention]

[0007] According to the present disclosure, the display quality can be further improved. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic diagram of a vehicle equipped with a head-up display device according to an embodiment of the present disclosure. [Figure 2] 1 is a schematic plan view showing the positional relationship between a display panel and a concave mirror when viewed from above according to an embodiment of the present disclosure. FIG. [Figure 3] FIG. 10 is a schematic diagram showing the positional relationship between a display panel and a concave mirror when viewed from above in a comparative example. [Figure 4] 10A and 10B are schematic diagrams illustrating changes in the horizontal angle of the display panel relative to the concave mirror when viewed from above according to an embodiment of the present disclosure. [Figure 5] FIG. 2 is a schematic diagram illustrating eyepoints within an eyebox according to an embodiment of the present disclosure. [Figure 6] 10 is a graph showing the tilt of a virtual image at each eye point with respect to a change in horizontal angle of a display panel according to an embodiment of the present disclosure. [Figure 7] FIG. 10 is a schematic diagram of a vehicle equipped with a head-up display device according to a modified example. [Figure 8] FIG. 10 is a schematic diagram of a vehicle equipped with a head-up display device according to a modified example. DETAILED DESCRIPTION OF THE INVENTION

[0009] A head-up display device according to an embodiment of the present disclosure will be described with reference to the drawings. As shown in FIG. 1, the head-up display device 100 is installed in the dashboard of the vehicle 200. The head-up display device 100 emits display light L that displays an image toward a windshield 201, which is an example of a projection target member of the vehicle 200. The display light L is reflected by the windshield 201 and reaches a viewer 1 (mainly the driver of the vehicle 200). As a result, the head-up display device 100 displays a virtual image V as a projection image so as to be superimposed on the actual scenery seen through the windshield 201. A virtual image display area in which the virtual image V can be displayed forms a rectangle that is short in the vertical (up-down) direction and long in the horizontal (left-right) direction when viewed from the viewer 1.

[0010] The head-up display device 100 includes a display device 10, a concave mirror 30, and a housing 60. The housing 60 is made of a light-blocking resin or metal and houses the display device 10 and the concave mirror 30. An opening 60a is formed in the housing 60 at a position facing the windshield 201. The housing 60 has a plate-shaped window 60b made of a light-transmitting resin material or glass material that closes the opening 60a.

[0011] The concave mirror 30 has a reflecting surface 30a that reflects and magnifies the display light L from the display device 10 toward the windshield 201. The reflecting surface 30a has a concave curved shape in the vehicle width direction and the vehicle height direction. The reflecting surface 30a is formed of a free-form surface that offsets distortion of the virtual image V caused by the curved shape of the windshield 201. The reflecting surface 30a is not limited to a free-form surface that cannot be expressed by a simple mathematical formula, but may be formed by a curved surface that can be expressed by a simple mathematical formula.

[0012] The display device 10 emits display light L under the control of a control unit (not shown). The display device 10 includes a display 11 and an illumination device 12 that illuminates the display 11. The lighting device 12 includes a plurality of light-emitting diodes (LEDs) as light sources and a group of light distribution lenses that distribute light from the LEDs to the display 11 in accordance with the light distribution.

[0013] The display 11 receives illumination light from the illumination device 12 and emits display light L. The display 11 is a TFT (Thin Film Transistor) liquid crystal display panel. The display 11 has a display surface 11a on the side from which the display light L is emitted. The display surface 11a has a rectangular shape corresponding to the virtual image display area. A display image D corresponding to the display light L is displayed on the display surface 11a. In the following description, as shown in FIG. 2, the X and Y directions are perpendicular to the optical axis center Lc of the display light L between the display surface 11a and the reflecting surface 30a and are also perpendicular to each other. The X direction extends along the longitudinal direction of the display surface 11a and corresponds to the horizontal direction of the virtual image V as seen by the viewer 1. The Y direction extends along the lateral direction of the display surface 11a and corresponds to the vertical direction of the virtual image V as seen by the viewer 1. The Z direction extends in the same direction as the optical axis center Lc and corresponds to the depth direction of the virtual image V as seen by the viewer 1. In this example, the X direction extends in the vehicle width direction, the Y direction extends in the vehicle height direction, and the Z direction extends in the vehicle longitudinal direction.

[0014] As shown in FIG. 2, the reflecting surface 30a is positioned opposite the display surface 11a on the optical path of the display light L. The reflecting surface 30a is inclined at a horizontal tilt angle α with respect to the X direction around a central axis K located at the center of the reflecting surface 30a in the X direction. The central axis K extends in the Y direction. The horizontal tilt angle α is a rotation angle in the horizontal direction (XY direction) formed by a tangent direction to the center position of the reflecting surface 30a with respect to the X direction. When viewed from above in the Y direction, the clockwise direction of the concave mirror 30 around the central axis K is a positive direction of the horizontal tilt angle α, and the counterclockwise direction is a negative direction. The horizontal tilt angle α is set to a value other than 0 (zero)°, for example, between 5° and 15°, or between −5° and −15°. In this example, the horizontal tilt angle α is set to between −11° and −13°, and more preferably to about −12°.

[0015] 1, the display surface 11a extends in the Y direction when viewed from the X direction. That is, in this example, the display surface 11a is not inclined with respect to the Y direction. However, without being limited to this example, the display surface 11a may be inclined with respect to the Y direction. Specifically, as shown in Fig. 7, the display surface 11a may be inclined with respect to the Y direction so as to face diagonally downward and forward of the vehicle.

[0016] As shown in FIG. 2, when viewed from above in the Y direction, the display surface 11a is inclined at a horizontal inclination angle θ with respect to the X direction. The horizontal tilt angle θ is the rotation angle of the display 11 in the horizontal direction (XY direction) around a central axis J located at the center of the display 11 in the X direction. The central axis J extends in the Y direction. The horizontal tilt angle θ is 0 (zero)° when the display surface 11a is oriented to extend in the X direction. When viewed from above in the Y direction, the horizontal tilt angle θ is positive when the display 11 is rotated clockwise around the central axis J, and negative when rotated counterclockwise.

[0017] The horizontal tilt angle θ according to this embodiment is set to an angle other than 0°, which reduces the difference in optical path lengths A1, A2 of the display light L between the display surface 11a and the reflective surface 30a, compared to when the horizontal tilt angle θ according to the comparative example in FIG. 3 is 0°. The horizontal tilt angle θ is set to a positive value when the horizontal tilt angle α is a positive value, and is set to a negative value when the horizontal tilt angle α is a negative value. The horizontal tilt angle θ is set to, for example, -3° to -15°. In the example of FIG. 2, it is set to -5° to -10°.

[0018] In the comparative example of FIG. 3 , the horizontal tilt angle θ is 0 (zero) degrees, so the difference between the optical path lengths A1 and A2 of the display light L at both ends in the X direction between the display surface 11a′ and the reflecting surface 30a is large. The optical path lengths are determined according to the inter-surface distance between the display surface 11a′ and the reflecting surface 30a. The optical path length A1 is located at the right end of the display light L, and the optical path length A2 is located at the left end of the display light L. Because the horizontal tilt angle α is set to a negative angle (counterclockwise with respect to the X direction), in this comparative example, the optical path length A1 is longer than the optical path length A2. The difference between the optical path lengths A1 and A2 causes a difference in the magnification of the display light L in the X direction, which can cause distortion in the virtual image V (projected image) when a viewer observes the virtual image V with both eyes.

[0019] In this embodiment, as shown in Fig. 2, the horizontal tilt angle θ is set to a negative value (for example, -5° or -10°), so that the inter-surface distance corresponding to the optical path length A1 is smaller and the inter-surface distance corresponding to the optical path length A2 is larger than in the comparative example. In this example, the horizontal tilt angle θ is set so that the difference between the optical path lengths A1 and A2 is zero. By reducing the difference between the optical path lengths A1 and A2, distortion of the virtual image V (projected image) when the viewer observes it with both eyes is suppressed. Furthermore, by tilting the display surface 11a with respect to the X direction, sunlight traveling back along the optical path of the display light L is prevented from becoming stray light.

[0020] The inventors of the present application conducted simulations to determine rotation values ​​that indicate the inclination of virtual image V at each of eyepoints EP1 to EP6 when the horizontal inclination angle θ of display surface 11a was changed within the range of −10° to 10°. In this simulation, as shown in FIG. 4, the horizontal tilt angle θ is changed in 5° intervals within the range of −10° to 10°. As shown in Figure 5, eyepoints EP1 to EP6 are the viewer's viewpoint positions and are set at different positions within the eyebox. When the viewer's viewpoint enters the eyebox, the viewer can view the virtual image V. Eyepoint EP1 is located in the upper left corner of the eyebox, eyepoint EP3 is located in the upper right corner of the eyebox, eyepoint EP4 is located in the lower left corner of the eyebox, eyepoint EP6 is located in the lower right corner of the eyebox, eyepoint EP2 is located midway between eyepoints EP1 and EP3, and eyepoint EP5 is located midway between eyepoints EP4 and EP6.

[0021] As shown in the graph of FIG. 6, which shows the simulation results, the absolute value of the rotation value for each eyepoint EP1 to EP6 decreases as the horizontal tilt angle θ decreases, and the absolute value of the rotation value for each eyepoint EP1 to EP6 increases as the horizontal tilt angle θ increases. When the horizontal tilt angle θ is -10°, the rotation value for each eyepoint EP1 to EP6 is minimized, reducing the distortion of the virtual image V. This is because the difference between the optical path lengths A1 and A2 decreases as the horizontal tilt angle θ decreases. When the horizontal tilt angle θ is between -5° and -10°, the distribution range of the rotation values ​​for each eyepoint EP1 to EP6 falls within allowable range B. Allowable range B is set, for example, to a range of 0.7° of the rotation value.

[0022] (effect) According to the embodiment described above, the following effects are achieved. (1) The head-up display device 100 displays a virtual image V, which is an example of a projection image, by projecting display light L onto a windshield 201, which is an example of a projection target. The head-up display device 100 includes a display 11, which is an example of a display panel that emits the display light L, and a concave mirror 30, which is an example of a curved mirror that reflects the display light L. The display 11 is disposed in a direction that is inclined with respect to the X direction, which is an example of a reference direction that corresponds to the lateral direction of the virtual image V among directions orthogonal to the optical axis center Lc of the display light L. According to this configuration, by tilting the display 11 with respect to the X direction, the display quality of the virtual image V can be further improved compared to a configuration in which the display 11 is not tilted with respect to the X direction.

[0023] (2) The concave mirror 30 is a correction mirror having a reflecting surface 30a made of a free-form surface formed so as to correct the distortion of the virtual image V. According to this configuration, the display quality of the virtual image V can be further improved by the free-form surface of the concave mirror 30 in addition to the tilt of the display 11 with respect to the X direction.

[0024] (3) The curved mirror that reflects the display light L is a concave mirror 30.

[0025] (4) The inclination of the display 11 with respect to the X direction is set so that the difference between the optical path lengths A1 and A2 of the display light L at both ends of the display 11 and the concave mirror 30 in the X direction is smaller than when the display 11 extends in the X direction and is not inclined with respect to the X direction. According to this configuration, the difference between the optical path lengths A1 and A2 is reduced, and the display quality of the virtual image V can be further improved.

[0026] (5) The inclination of the display 11 with respect to the X direction is set so that there is no difference between the optical path lengths A1 and A2 of the display light L at both ends of the display 11 and the concave mirror 30 in the X direction. This configuration eliminates the difference between the optical path lengths A1 and A2, thereby further improving the display quality of the virtual image V. Here, "eliminating the difference between the optical path lengths A1 and A2" includes a difference between the optical path lengths A1 and A2 of ±3%.

[0027] The present disclosure is not limited to the above-described embodiments and drawings. Modifications (including deletion of components) may be made as appropriate within the scope of the present disclosure. An example of such a modification is described below.

[0028] (Variation) In the above embodiment, the display light L from the display 11 is directly emitted to the concave mirror 30, but this is not limiting. As shown in FIG. 8, the head-up display device 100a includes a folding mirror 40 that reflects the display light L from the display 11 to the concave mirror 30. The folding mirror 40 is a flat mirror. This flat mirror does not optically affect the display light L. Therefore, even in this configuration, the horizontal tilt angle θ of the display 11 and the horizontal tilt angle α of the concave mirror 30 are set in the same way as in the above embodiment. The display 11 is tilted in the X direction so as to reduce the optical path length difference with the curved mirror (including a free-form surface mirror) closest to the display 11 among the optical relays consisting of multiple mirrors that guide the display light L to the windshield 201. Furthermore, if the folding mirror 40 is a correction mirror having a free-form surface, instead of the concave mirror 30 of the above embodiment, the horizontal tilt angle θ of the display 11 relative to the horizontal tilt angle of the folding mirror 40 is set.

[0029] In the above embodiment, the projection target member is the windshield 201, but may be a dedicated combiner. The head-up display device 100, 100a may be mounted not only on a vehicle but also on other vehicles such as an airplane, a ship, etc.

[0030] In the above embodiment, the display panel is a liquid crystal display 11, but it is not limited to the liquid crystal display 11 and may be a screen that forms an image using projected light from a projector.

[0031] In the above embodiment, the display 11 is fixed so as not to be rotatable, but this is not limiting, and the head-up display device 100 may include a display driver that is rotatable about the central axis J so as to adjust the horizontal tilt angle θ. This display driver may adjust the horizontal tilt angle θ so as to reduce the difference between the optical path lengths A1 and A2. [Explanation of symbols]

[0032] 1...Viewer 10...display device, 11...display, 11a, 11a'...display surface 12...Lighting equipment 30...concave mirror, 30a...reflective surface 40...Folding mirror 60... housing, 60a... opening, 60b... window 100, 100a...Head-up display device 200...Vehicle, 201...Windshield α, θ… Horizontal tilt angle, A1, A2… Path length, B… Allowable range, D… Image representation, J, K… Central axis, L… Light representation, Lc… Center of optical axis, V… Virtual image, EP1~EP6… Image

Claims

1. A head-up display device that displays a projection image by projecting display light onto a projection target, a display panel that emits the display light; a curved mirror that reflects the display light, the display panel is provided in a direction inclined with respect to a reference direction corresponding to a lateral direction of the projection image among directions orthogonal to the center of the optical axis of the display light; Head-up display device.

2. the curved mirror is a correction mirror having a reflective surface made of a free-form surface formed so as to correct distortion of the projected image; The head-up display device according to claim 1 .

3. The curved mirror is a concave mirror. The head-up display device according to claim 1 .

4. the inclination of the display panel with respect to the reference direction is set so that a difference in optical path length of the display light between both end portions of the display panel and the curved mirror in the reference direction is smaller than a case in which the display panel extends in the reference direction and is not inclined with respect to the reference direction. The head-up display device according to any one of claims 1 to 3.

5. the inclination of the display panel with respect to the reference direction is set so that there is no difference in the optical path length of the display light between both ends of the display panel and the curved mirror in the reference direction. The head-up display device according to any one of claims 1 to 3.

6. a flat mirror that reflects the display light from the display panel toward the curved mirror; The head-up display device according to any one of claims 1 to 3.

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