Head-up display device

Abstract

The purpose of the present invention is to provide a head-up display device that enables a reduction in size.　A head-up display device (100) according to the present invention displays a virtual image (V) by projecting display light (L) onto a windshield (201). The head-up display device (100) comprises: a display unit (20) that radiates the display light (L); a second mirror (12) having a reflective surface (12a) that reflects the display light (L) toward the windshield (201); and a drive mechanism (40) that rotates the second mirror (12) among a plurality of rotation positions centered on an axis of rotation (Ax) such that the irradiation position of the display light (L) on the windshield (201) changes in the height direction. When the second mirror (12) is at each rotation position, display light reflection regions for reflecting the display light (L) on the reflective surface (12a) are set to be substantially the same.

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 projection unit that projects projection light showing an image, a reflective screen that diffusely reflects the projection light, a concave mirror that enlarges and reflects image light, which is the light diffusely reflected by the reflective screen, toward a projection member, and a concave mirror motor that rotates the 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 configuration described in Patent Document 1 above, as the concave mirror rotates, the light reflection region, which is the usage area on the reflection surface of the concave mirror, moves. The size of the reflection surface is set to include the entire area of the light reflection region that moves as the concave mirror rotates. For this reason, the concave mirror, and thus the head-up display device, has become large-sized.

[0005] The present disclosure has been made in view of the above actual situation, 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 objective, a head-up display device according to the first aspect of this disclosure is a head-up display device that displays a virtual image by projecting display light onto a projection member, comprising: a display unit that emits the display light; a mirror having a reflective surface that reflects the display light toward the projection member; and a drive mechanism that rotates the mirror between a plurality of rotational positions about a rotation axis so that the irradiation position of the display light on the projection member changes, wherein when the mirror is in each of the rotational positions, the display light reflection regions on the reflective surface that reflect the display light are set to be substantially the same.

[0007] To achieve the above objective, a head-up display device according to a second aspect of this disclosure is a head-up display device that displays a virtual image within a virtual image display area by projecting display light onto a projection member, comprising: a display unit that emits the display light; a mirror having a reflective surface that reflects the display light toward the projection member; and a drive mechanism that rotates the mirror between a plurality of rotational positions about a rotation axis so that the irradiation position of the display light on the projection member changes, wherein a ray of the display light corresponding to the center position of the virtual image display area passes through the center position of the display image within the display light reflection area that reflects the display light on the reflective surface, and when the mirror is in each of the rotational positions, the amount of displacement of the display light reflection area is set to be smaller than the amount of displacement of the center position of the display image. [Effects of the Invention]

[0008] According to this disclosure, miniaturization of the head-up display device is possible. [Brief explanation of the drawing]

[0009] [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, when the second mirror is at a rotation angle for the midpoint of the view. [Figure 3]This is a schematic diagram of a head-up display device according to one embodiment of the present disclosure, when the second mirror is at a low-view rotation angle. [Figure 4] This is a schematic diagram of a head-up display device according to one embodiment of the present disclosure, when the second mirror is at a rotation angle for a high viewpoint. [Figure 5] This is a schematic diagram of the display light reflection region and the center position of the display image related to the comparative example. [Figure 6] This is a schematic diagram of the display light reflection region and the display image center position according to one embodiment of the present disclosure. [Figure 7] This is a schematic diagram showing the display light reflection region and the display image center position according to one embodiment and comparative example of the present disclosure. [Figure 8] This figure shows the display light reflection region and the display image center position according to one embodiment and comparative example of the present disclosure. [Figure 9] This is a schematic diagram showing the optical path of a head-up display device relating to a comparative example. [Figure 10] This is a schematic diagram showing the display light reflection area and the center position of the display image in a comparative example. [Modes for carrying out the invention]

[0010] 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. This makes a virtual image V containing vehicle information visible to the viewer 1 (for example, the driver of the vehicle 200) whose viewpoint is located within the eye box EB. The virtual image V is displayed in a virtual image display area K that is virtually located outside the vehicle. The windshield 201 is curved so as to bulge outwards from the vehicle and is positioned so that its height decreases as it approaches the front of the vehicle 200.

[0011] As shown in FIG. 2, the head-up display device 100 includes a first mirror 11, a second mirror 12, a display unit 20, a case 30, a drive mechanism 40, and a control unit 50. 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 accommodated in the case 30. The case 30 includes a window portion 31 made of a light-transmissive member that transmits the display light L generated in the internal space of the case 30 toward the front glass 201.

[0012] The display unit 20 has a light emission surface 21 that emits display light L representing an image. The display unit 20 may be of a type having a liquid crystal panel and a lighting device, or may be of a type having a reflective display element such as a DMD (Digital Micro mirror Device) element. The image shown on the light emission surface 21 is subjected to distortion correction for correcting the distortion of the virtual image V viewed by the viewer 1.

[0013] As shown in FIG. 2, the first mirror 11 reflects the display light L emitted from the display unit 20 toward the second mirror 12. The first mirror 11 is a plane mirror. Note that the first mirror 11 is not limited to a plane mirror and may be a concave mirror. The reflecting surface 11a of the first mirror 11 faces the lower front side of the vehicle.

[0014] As shown in FIG. 2, the second mirror 12 is a concave mirror that curves along the height direction and the width direction of the vehicle. The second mirror 12 reflects the display light L reflected from the first mirror 11 toward the front glass 201. The reflecting surface 12a forming the concave curved surface of the second mirror 12 faces the upper rear side of the vehicle. The length of the reflecting surface 12a in the vertical direction (height direction) is set to about 80 mm, for example, 80.2 mm. The second mirror 12 has a function of suppressing the distortion of the virtual image due to reflection by the front glass 201 in cooperation with the first mirror 11. The second mirror 12 is supported rotatably in the case 30 about a rotation axis Ax extending along the width direction of the vehicle 200.

[0015] ​ Under the control of the control unit 50, the drive mechanism 40 rotates the second mirror 12 about the rotation axis Ax so that the irradiation height of the display light L on the windshield 201 changes. The drive mechanism 40 includes a motor (not shown) and a conversion mechanism (not shown) that converts the rotational motion of the motor into linear motion. This conversion mechanism rotates the second mirror 12 about the rotation axis Ax by transmitting the converted linear motion to the second mirror 12.

[0016] The second mirror 12 is set by the drive mechanism 40 to any one of the rotation angles of the high-viewpoint rotation position PT (see FIG. 4), the middle-viewpoint rotation position PN (see FIG. 2), and the low-viewpoint rotation position PS (see FIG. 3). When the second mirror 12 is at the high-viewpoint rotation position PT (see FIG. 4), the reflecting surface 12a faces the rear of the vehicle. When the second mirror 12 is at the low-viewpoint rotation position PS (see FIG. 3), the reflecting surface 12a faces upward of the vehicle. The middle-viewpoint rotation position PN (see FIG. 2) is set at an intermediate angle between the high-viewpoint rotation position PT (see FIG. 4) and the low-viewpoint rotation position PS (see FIG. 3). When the second mirror 12 is at the high-viewpoint rotation position PT (see FIG. 4), the display light L is irradiated at a higher position on the windshield 201 than when the second mirror 12 is at the middle-viewpoint rotation position PN (see FIG. 2) and the low-viewpoint rotation position PS (see FIG. 3). Thereby, the instrument box EB is set at the high position P1. When the second mirror 12 is at the low-viewpoint rotation position PS, the display light L is irradiated at a lower position on the windshield 201 than when the second mirror 12 is at the middle-viewpoint rotation position PN and the high-viewpoint rotation position PT. Thereby, the instrument box EB is set at the low position P2. Also, when the second mirror 12 is at the middle-viewpoint rotation position PN, the instrument box EB is set at the middle position P3 between the high position P1 and the low position P2.

[0017] The control unit 50, for example, is composed of a microcomputer and controls the drive mechanism 40 and the display unit 20 based on information from an in-vehicle ECU (Electronic Control Unit) (not shown). The control unit 50 sets the second mirror 12 to one of the following rotation angles (rotation position): high-view rotation position PT, medium-view rotation position PN, or low-view rotation position PS, based on the operation of a switch (not shown) by the viewer 1 or a detection unit (not shown) that detects the viewer 1's viewpoint position.

[0018] Next, with reference to Figures 7 and 8, the display light reflection regions NE, SE, TE and the display image center positions GrN, GrS, GrT, which are set on the reflective surface 12a corresponding to each rotation position PT, PN, and PS, will be described. The display light reflection regions NE, SE, and TE are the usable areas of the reflective surface 12a that are illuminated by the display light. The display light reflection region NE is the region when the second mirror 12 is in the rotation position PN for the mid-viewpoint (see Figure 2). The display light reflection region SE is the region when the second mirror 12 is in the rotation position PS for the low-viewpoint (see Figure 3). The display light reflection region TE is the region when the second mirror 12 is in the rotation position PT for the high-viewpoint (see Figure 4). In this embodiment, the display light reflection regions NE, SE, and TE for each rotation position PT, PN, and PS are set to be approximately the same.

[0019] The display image center positions GrN, GrS, and GrT are the positions reached by tracing the ray of display light L, which corresponds to the center position of the virtual image display area K (see Figure 2), and are the positions that reach the reflective surface 12a. Due to various reasons, the display image center positions GrN, GrS, and GrT do not necessarily coincide with the area-wise center positions of the display light reflection areas NE, SE, and TE. These various reasons include, for example, that the image displayed on the light emission surface 21 is subjected to distortion correction, and that the distance to the windshield 201 differs depending on the position of the reflective surface 12a due to the inclination of the reflective surface 12a. The display image center position GrN is located within the display light reflection area NE when the second mirror 12 is in the rotation position PN for the mid-viewpoint. The display image center position GrS is located within the display light reflection area SE when the second mirror 12 is in the rotation position PS for the low-viewpoint, and is shifted upward from the display image center position GrN. The display image center position GrT is located within the display light reflection area TE when the second mirror 12 is in the high-view rotation position PT, and is shifted downward from the display image center position GrN.

[0020] As shown in Figure 6, in this embodiment, the distance ΔG in the Y direction between the two display image center positions GrN and GrT is set to be greater than the Y-direction displacement amounts YmaxE and YminE between the two display light reflection regions NE and TE. Also, as shown in Figure 7, the distance in the Y direction between the two display image center positions GrN and GrS is set to be greater than the Y-direction displacement amounts between the two display light reflection regions NE and SE. The X direction is along the longitudinal direction of the reflective surface 12a and the width direction of the vehicle, and the Y direction is along the short direction of the reflective surface 12a and the height direction of the vehicle. The origin of the XY coordinate system is located at the center of the reflective surface 12a. The deviation amount YmaxE is obtained by subtracting the maximum value YNmax located at the upper end of the display light reflection region NE from the maximum value YTmax located at the upper end of the display light reflection region TE. The deviation amount YminE is obtained by subtracting the maximum value YNmin located at the lower end of the display light reflection region NE from the maximum value YTmin located at the lower end of the display light reflection region TE. Here, with the center of the display light reflection region NE in the Y direction as the origin, the upward direction from the origin is a positive value, and the downward direction from the origin is a negative value. In this case, it is preferable that the sum of the deviation amount YmaxE and the deviation amount YminE is set so that the following formula holds. -0.5mm < YmaxE + YminE < 0.5mm As in the example of FIG. 6, when the length of the display light reflection region TE in the Y direction is longer than the length of the display light reflection region NE in the Y direction, and the display light reflection region NE is positioned so as to be included in the display light reflection region TE in the Y direction, the deviation amount YmaxE becomes a positive value and the deviation amount YminE becomes a negative value. Therefore, if the absolute values of these values are the same value, "YmaxE + YminE" becomes zero and satisfies the above formula.

[0021] Next, a method for setting the display light reflection regions NE, SE, TE and the display image center positions GrN, GrS, GrT will be described while comparing with a comparative example. In the comparative example, as shown in Figure 9, the design ensures that the line segment connecting the center position of the eye box EB and the center position of the virtual image display area K passes through intersection point W, regardless of the rotational position of the second mirror 12 around its rotation axis Ax. As a result, as shown in Figures 5 and 10, in the comparative example, the display image center positions GrN', GrS', and GrT' approximately coincide on the reflective surface 12a. In other words, the rotation angle of the second mirror 12 for each rotational position PT, PN, and PS is set so that the display image center positions GrN', GrS', and GrT' approximately coincide on the reflective surface 12a. This approximate coincidence is set within a range that includes positional displacement of the display image center positions GrN', GrS', and GrT' due to the shape of the windshield 201, etc. Setting the display image center positions GrN', GrS', and GrT' in this way increases the amount of positional displacement of the display light reflection areas NE', SE', and TE' due to the rotation of the second mirror 12 between rotational positions PT, PN, and PS. As a result, in the comparative example, as shown in Figure 10, the size of the combined region GE', which is formed by merging the misaligned display light reflection regions NE', SE', and TE', increased, and the size of the reflective surface 12a also increased.

[0022] On the other hand, in this embodiment, as shown in Figure 7, the rotation angle of the second mirror 12 is set so that the display light reflection regions NE, SE, and TE are approximately coincided, while allowing for positional misalignment of the display image center positions GrN, GrS, and GrT. In other words, the combined region GE, which is the sum of the display light reflection regions NE, SE, and TE, is made smaller.

[0023] The following describes a method for setting the rotation angle of the second mirror 12 so that the display light reflection regions NE, SE, and TE are approximately aligned. This setting method is performed, for example, by utilizing the simulation results executed by a processing unit, which is a computer separate from the head-up display device 100. The processing unit rotates the second mirror 12 in the simulation and searches for a rotation angle of the second mirror 12 that satisfies the following condition. In the above conditional equation YmaxE + YminE = 0, the deviation amounts YmaxE and YminE (see Figure 6) of the display light reflection regions SE and TE relative to the reference display light reflection region NE are calculated by the following formula. YmaxE=YTmax-YNmax YminE=YTmin-YNmin

[0024] The following section specifically explains how to set the display light reflection region TE to match the display light reflection region NE in this setting method. The processing unit first obtains the maximum value YNmax and minimum value YNmin of the display light reflection area NE when the second mirror 12 is in the rotation position PN for the central viewpoint. In this example, the display light reflection area NE is used as the reference.

[0025] The processing unit then rotates the second mirror 12 in either a positive or negative direction within an allowable range from the initial value of the high-viewpoint rotation position PT, calculating the maximum value YTmax and minimum value YTmin of the display light reflection area TE, and searches for a rotation angle of the second mirror 12 that satisfies the above condition. This allowable range is set to the angle range that is allowed for the high-viewpoint rotation position PT. Once the processing unit finds a rotation angle of the second mirror 12 that satisfies the above condition, it sets this rotation angle as the high-viewpoint rotation position PT. This completes the setting of the display light reflection area TE. Furthermore, if the processing unit cannot find a rotation angle for the second mirror 12 that satisfies the above condition within the above tolerance range, it may set a rotation angle for the second mirror 12 within the range where "YmaxE + YminE" is greater than -0.5 mm and less than 0.5 mm as the high-viewpoint rotation position PT.

[0026] By satisfying the above conditions, as shown in Figure 6, the absolute values ​​of the displacement amounts YmaxE and YminE become equal, and the display light reflection regions NE and TE become symmetrical in the height direction (Y direction). Furthermore, although the display image center positions GrN and GrT of the display light reflection regions NE and TE are offset from each other in the height direction, the center positions of the display light reflection regions NE and TE are approximately the same. In this example, the distance ΔG between the display image center positions GrN and GrT of the display light reflection regions NE and TE is set to be larger than the displacement amounts YmaxE and YminE. After setting the display light reflection area TE, the processing unit sets the display light reflection area SE to match the display light reflection area NE, similar to the display light reflection area TE. That is, it rotates the second mirror 12 to find the low-viewpoint rotation position PS that satisfies the above condition, and sets the low-viewpoint rotation position PS. With this, the setting of each rotation position PT, PN, PS and each display light reflection area NE, SE, TE is completed. While the above setting method was performed through simulation, it is not limited to this method and may also be performed through experimentation.

[0027] In the comparative example, as shown in Figure 10, the display light reflection regions NE', SE', and TE' are offset from each other in the height direction, so the combined region GE' of the display light reflection regions NE', SE', and TE' is large. On the other hand, in this embodiment, as shown in Figure 7, the offset of the display light reflection regions NE, SE, and TE is small, and the combined region GE of the display light reflection regions NE, SE, and TE is small. Therefore, in this embodiment, the region other than the combined region GE of the display light reflection regions NE, SE, and TE can be omitted, and the second mirror 12 can be miniaturized. Figures 5-7 and 10 schematically illustrate the display light reflection regions NE, SE, TE, NE', SE', and TE', while Figure 8 illustrates the display light reflection regions NE, SE, TE, NE', SE', and TE' in more detail.

[0028] (effect) According to the embodiment described above, the following effects are achieved. (1) The head-up display device 100 displays a virtual image V 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 unit 20 that emits display light L, a second mirror 12 which is an example of a mirror having a reflective surface 12a that reflects the display light L toward the windshield 201, and a drive mechanism 40 that rotates the second mirror 12 around a rotation axis Ax between a plurality of rotation positions (high-view rotation position PT, medium-view rotation position PN, low-view rotation position PS) so that the irradiation position of the display light L toward the windshield 201 changes in the height direction. When the second mirror 12 is in each rotation position PT, PN, PS, the display light reflection regions NE, SE, TE that reflect the display light L on the reflective surface 12a are set to be substantially the same. This configuration allows for a reduction in the size of the reflective surface 12a. Therefore, the second mirror 12, and consequently the head-up display device 100, can be miniaturized.

[0029] (2) The head-up display device 100 displays a virtual image V within a virtual image display area K by projecting display light L onto the windshield 201. The head-up display device 100 includes a display unit 20 that emits display light L, a second mirror 12 having a reflective surface 12a that reflects the display light L toward the windshield 201, and a drive mechanism 40 that rotates the second mirror 12 around a rotation axis Ax between a plurality of rotation positions (high-view rotation position PT, medium-view rotation position PN, low-view rotation position PS) so that the irradiation position of the display light L toward the windshield 201 changes in the height direction. Of the display light L, the light ray (Gutray) corresponding to the center position of the virtual image display area K passes through the display image center positions GrN, GrS, GrT in the display light reflection areas NE, SE, TE that reflect the display light L on the reflective surface 12a. When the second mirror 12 is in the respective rotation positions PT, PN, and PS, the displacement amounts YmaxE and YminE of the display light reflection regions NE, SE, and TE are set to be smaller than the displacement amount (distance ΔG) of the display image center positions GrN, GrS, and GrT. This configuration allows for a reduction in the size of the reflective surface 12a. Therefore, the second mirror 12, and consequently the head-up display device 100, can be miniaturized.

[0030] (3) When the second mirror 12 is in the intermediate viewing position PN, which is an example of the first rotation position, the positions of both ends from the origin located in the center of the height direction (Y direction) of the display light reflection area NE are set to be the maximum value YNmax, which is an example of the first maximum value, and the minimum value YNmin, which is an example of the first minimum value. When the second mirror 12 is in the high viewing position PT, which is an example of the second rotation position, the positions of both ends from the origin in the height direction of the display light reflection area TE are set to be the maximum value YTmax, which is an example of the second maximum value, and the minimum value YTmin, which is an example of the second minimum value. The sum of the displacement amount YmaxE, which is an example of the first displacement amount obtained by subtracting the maximum value YNmax from the maximum value YTmax, and the displacement amount YminE, which is an example of the second displacement amount obtained by subtracting the minimum value YNmin from the minimum value YTmin, is set to be greater than -0.5 mm and less than 0.5 mm. This configuration allows the display light reflection areas NE and TE to be symmetrical in the height direction (Y direction), thereby enabling miniaturization of the second mirror 12 and, consequently, the head-up display device 100.

[0031] 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.

[0032] (modified version) In the above embodiment, the distance ΔG between the display image center positions GrN and GrT of the display light reflection regions NE and TE was set to be greater than the displacement amounts YmaxE and YminE, but it is not limited to this and may be set to be less than the displacement amounts YmaxE and YminE.

[0033] The first mirror 11 in the above embodiment may be omitted. In this case, the display light L from the display unit 20 is projected directly onto the reflective surface 12a of the second mirror 12.

[0034] In the above embodiment, "YmaxE + YminE" was set within a range greater than -0.5 mm and less than 0.5 mm, but it may be outside this range.

[0035] In the above embodiment, the display light reflection regions TE and SE were set with respect to the display light reflection region NE, but the invention is not limited to this, and either the display light reflection region TE or SE may be used as the reference.

[0036] 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 projection target is not limited to the windshield 201, but may be a dedicated combiner. [Explanation of Symbols]

[0037] 1…Viewer, 11…First mirror, 11a,12a…Reflective surface, 12…Second mirror, 20…Display unit, 21…Light emitting surface, 30…Case, 31…Window unit, 40…Drive mechanism, 50…Control unit, 100…Head-up display device, 200…Vehicle, 201…Windshield, K…Virtual image display area, L…Display light, EB…Eye box, P1…High position, P2…Low position, P3…Mid position, GE',GE…Merged area, V…Virtual image, W…Intersection, NE,NE',SE,SE',TE,TE'…Display light reflection area, PN…Rotation position for mid-viewpoint, PS…Rotation position for low-viewpoint, PT…Rotation position for high-viewpoint, Ax…Rotation axis, GrN,GrN',GrS,GrS',GrT,GrT'…Display image center position, YminE,YmaxE…Amount of displacement

Claims

1. A head-up display device that displays a virtual image within a virtual image display area by projecting display light onto a projection target member, A display unit that emits the aforementioned display light, A mirror having a reflective surface that reflects the aforementioned display light toward the projected member, The system includes a drive mechanism that rotates the mirror around a rotation axis between a plurality of rotational positions so that the irradiation position of the display light on the projected member changes, Of the aforementioned display light, the ray corresponding to the center position of the virtual image display area passes through the center position of the display image within the display light reflection area that reflects the display light on the reflective surface. When the mirror is in each of the rotational positions, the amount of displacement of the display light reflection area is set to be smaller than the amount of displacement of the center position of the display image. Head-up display device.

2. When the mirror is in a first rotation position among the plurality of rotation positions, the positions of both ends of the display light reflection area from the origin located at the center in the height direction are defined as the first maximum value and first minimum value. When the mirror is in a second rotation position among the plurality of rotation positions, the positions of both ends of the display light reflection area from the origin in the height direction are defined as the second maximum value and second minimum value. The sum of the first deviation amount obtained by subtracting the first maximum value from the second maximum value, and the second deviation amount obtained by subtracting the first minimum value from the second minimum value, is set to a range greater than -0.5 mm and less than 0.5 mm. The head-up display device according to claim 1.

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