Head-up display device and method of controlling head-up display device

Abstract

To provide a head-up display device which enables easy viewing of virtual images, and a method of controlling the head-up display device.SOLUTION: A HUD device 1 disclosed herein comprises a display 20 and a microcomputer 50. The display 20 displays a virtual image by projecting display light onto a combiner. The microcomputer 50 controls brightness of the display light projected by the display 20 on the basis of a projection angle of the display light with respect to the combiner.SELECTED DRAWING: Figure 2

Description

[Technical field]

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

[0002] Some head-up display devices adjust the projection direction of display light by changing the projection angle of the display light emitted from a display unit onto a projected member such as a windshield.

[0003] For example, Patent Document 1 discloses a head-up display device that includes a display that emits display light and a mirror that reflects the display light emitted by the display, and that displays a virtual image by the mirror reflecting the display light and projecting it onto a projected member, and that the mirror is rotated to prevent the virtual image from tilting relative to the road surface on which the vehicle on which the head-up display device is installed is traveling. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2023-19874 A Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-mentioned projected member, the reflectance of the display light changes depending on the incident angle of the display light, in other words, the projection angle. Therefore, when the mirror is rotated in the head-up display device described in Patent Document 1 to change the projection angle of the display light to the projected member, the reflectance of the display light changes and the luminance of the display light may decrease. As a result, it may become difficult for the user to view the virtual image.

[0006] The present invention has been made to solve the above-mentioned problems, and has an object to provide a head-up display device in which a virtual image is easily visible, and a control method for the head-up display device. [Means for solving the problem]

[0007] In order to achieve the above object, a head-up display device according to a first aspect of the present invention comprises: a display that displays a virtual image by projecting the display light onto a projection member; a control unit that controls the luminance of the display light projected by the display device based on a projection angle of the display light with respect to the projection target member; Equipped with.

[0008] A method for controlling a head-up display device according to a second aspect of the present invention includes: A method for controlling a head-up display device including a display device that displays a virtual image by projecting display light onto a projection member, comprising: controlling the luminance of the display light projected by the display device based on a projection angle of the display light with respect to the projection target member; Includes. Effect of the Invention

[0009] According to the configuration of the present invention, the control unit controls the luminance of the display light projected by the display device based on the projection angle of the display light with respect to the projection target member, so that the virtual image is easily visible. [Brief description of the drawings]

[0010] [Figure 1] 1 is a schematic cross-sectional view of a head-up display device according to a first embodiment of the present invention. [Diagram 2] 1 is a block diagram of a head-up display device according to a first embodiment. [Diagram 3] 1 is a conceptual diagram of a vehicle equipped with a head-up display device according to a first embodiment. [Figure 4]3 is a conceptual diagram showing a display range of an image formed by display light projected onto a combiner included in the head-up display device according to the first embodiment. FIG. [Diagram 5] 1A is a graph showing the reflectance of the display light with respect to the projection angle of the combiner, and FIG. 1B is an enlarged view of the VB region shown in FIG. [Figure 6] 4 is a data structure diagram of a brightness adjustment table stored in a storage device included in the head-up display device according to the first embodiment. FIG. [Figure 7] FIG. 11 is a block diagram of a head-up display device according to a second embodiment. [Figure 8] FIG. 11 is a block diagram of a head-up display device according to a third embodiment. [Figure 9] FIG. 11 is a cross-sectional view of a display device included in a head-up display device according to a third embodiment. [Figure 10] FIG. 11 is a data structure diagram of a brightness adjustment table stored in a storage device included in a head-up display device according to the third embodiment. [Figure 11] 4 is a schematic cross-sectional view of a modified example of the head-up display device according to the first embodiment. FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] A head-up display device and a control method for the head-up display device according to an embodiment of the present invention will be described in detail below with reference to the drawings. In the drawings, the same or equivalent parts are given the same reference numerals. In addition, in the specification, front / rear, left / right, and top / bottom refer to front / rear, left / right, and top / bottom of a vehicle in which the head-up display device is installed.

[0012] (Embodiment 1) A head-up display device (hereinafter referred to as HUD device) according to the first embodiment is a device that is installed in a vehicle and projects display light that represents an image, for example, an image including information about the vehicle (such as the vehicle's speed and navigation information; hereinafter referred to as vehicle information), onto a projection member. In this HUD device, in order to make a virtual image easier to see, a control unit controls the brightness of the display light based on the projection angle (hereinafter referred to as the incidence angle) of the display light onto the projection member. Below, the configuration of the HUD device and its microcontroller (hereinafter referred to as microcomputer) will be described using an example in which the projection member is a combiner and the control unit is a microcontroller. First, the overall configuration of the HUD device will be described.

[0013] As shown in FIG. 1, the HUD device 1 includes a housing 10, a display 20, a mirror member 30, a combiner 40, and a microcomputer 50.

[0014] The housing 10 is formed in a box shape. In addition, it is formed of a material having light-shielding properties. This allows the housing 10 to house components therein and prevents unnecessary reflection of light inside. In order to generate display light L, components such as a display 20 and a mirror member 30 are housed inside the housing 10.

[0015] The display 20 has a backlight 21 that emits light to generate display light L, and a liquid crystal panel 22 that generates the display light L that displays an image by adjusting the degree of light transmission of the backlight 21. The backlight 21 and the liquid crystal panel 22 are disposed in the front portion F inside the housing 10.

[0016] The backlight 21 is composed of, for example, a plurality of LEDs (Light Emitting Diodes). The backlight 21 is driven by a PWM (Pulse Width Modulation) signal generated by an LED driver 23 shown in FIG. 2. The PWM signal is generated based on a command signal output by a microcomputer 50. The backlight 21 emits light in response to the PWM signal and emits light at a luminance according to the PWM signal. As a result, the backlight 21 is turned on based on the command signal output by the microcomputer 50, and emits light at a luminance according to the command signal when turned on. As shown in FIG. 1, a liquid crystal panel 22 is disposed behind the backlight 21 at B, and the backlight 21 irradiates the liquid crystal panel 22 when turned on.

[0017] The liquid crystal panel 22 is configured, for example, by a transmissive TFT (Thin Film Transistor) liquid crystal panel. The liquid crystal panel 22 has a display section in which a plurality of pixels are arranged in a matrix, not shown, and changes the light transmittance of each pixel by being controlled by a liquid crystal driver 24 shown in FIG. 2. The liquid crystal panel 22 is irradiated from the front F by the above-mentioned backlight 21, as shown in FIG. 1. The liquid crystal panel 22 adjusts the transmittance of the light irradiated from the backlight 21 for each pixel to generate display light L including an image. Then, the generated display light L is further emitted backward B. A mirror member 30 is disposed behind the liquid crystal panel 22. The liquid crystal panel 22 emits the display light L to the mirror member 30.

[0018] The display 20 may have a fluorescent display tube instead of the backlight 21 and the liquid crystal panel 22. In that case, the display 20 may emit display light L generated by the fluorescent display tube to the mirror member 30.

[0019] The mirror member 30 has a rectangular, flat reflective surface. The mirror member 30 is fixed to the housing 10 with the reflective surface facing obliquely upward in the forward direction F. As a result, the mirror member 30 reflects the display light L emitted from the liquid crystal panel 22 toward the obliquely upward direction F. An opening 11 formed on the top surface of the housing 10 is located in the obliquely upward direction in the forward direction F.

[0020] The opening 11 is provided to emit the display light L reflected by the mirror member 30 to the outside. Its shape is approximately rectangular. A combiner 40 is provided at the front end portion of the opening 11 to direct the emitted display light L to a driver (also called a user). As shown in FIG. 3, the housing 10 is installed on the dashboard 4 of the vehicle 2 with the front end portion of the opening 11, where the combiner 40 is provided, facing the windshield 3 side. As a result, the combiner 40 is disposed near the rear of the windshield 3.

[0021] Although not shown, the combiner 40 is formed in the shape of a rectangular plate bent into a shape having a concave surface. The combiner 40 is formed of an opaque material that has a certain thickness and transmits almost no visible light. The longitudinal direction of the plate surface of the combiner 40 faces the left-right direction. In this state, as shown in FIG. 1, one end of the plate surface of the combiner 40 in the lateral direction is supported by a support member 41 arranged at the front end portion within the opening 11.

[0022] Although not shown, the support member 41 is fixed to a rotation shaft arranged parallel to the longitudinal direction of the plate surface of the combiner 40. The rotation shaft is rotated by a combiner drive motor 25 shown in FIG. 2 which operates based on a rotation command output by the microcomputer 50. As a result, the support member 41 rotates about the rotation shaft based on the rotation command from the microcomputer 50. As a result, the orientation of the combiner 40 can be changed between an upright orientation shown by a solid line in FIG. 1, which is the orientation when the HUD device 1 is used, and a laid-down orientation shown by a dotted line in FIG. 1, which is the orientation when the HUD device 1 is not used.

[0023] When the combiner 40 is oriented in the upright direction, the plate surface on the rear side B faces slightly diagonally downward. As a result, the combiner 40 causes the display light L reflected by the mirror member 30 to enter the combiner 40 as shown in Fig. 3, and reflects the display light L in the direction of the driver 5 in the driver's seat diagonally above the rear side B. As a result, the combiner 40 allows the driver 5 to visually recognize a virtual image V. The combiner 40 may be formed of a material that transmits visible light, in addition to the opaque material described above. In that case, the combiner 40 transmits light from the front F of the vehicle 2, and allows the driver 5 to visually recognize the virtual image V superimposed on the scenery in the front F.

[0024] On the other hand, when the combiner 40 is facing in the lying down direction, the plate surface of the combiner 40 faces in a direction along the upper surface of the housing 10 and covers the opening 11. In this way, the combiner 40 closes the opening 11. In addition, the combiner 40 does not block the driver's 5 field of vision.

[0025] The microcomputer 50 controls the orientation of the combiner 40. Next, the configuration of the microcomputer 50 will be described.

[0026] As shown in FIG. 2, the microcomputer 50 includes a central processing unit (CPU) 51, a read only memory (ROM) 52, a random access memory (RAM) 53, and the like.

[0027] The CPU 51 is communicably connected to an ECU (Electronic Control Unit) 61 and an ignition switch (hereinafter, referred to as IGSW) 62 provided in the vehicle 2 and controlling each part of the vehicle 2, via a CAN (Controller Area Network) signal line 60. The CPU 51 executes a control program stored in the ROM 52 to perform various control processes for operating the LED driver 23, the liquid crystal driver 24, and the combiner drive motor 25 provided in the HUD device 1.

[0028] For example, the CPU 51 drives the combiner drive motor 25 based on the output signal of the IGSW 62. As a result, the CPU 51 switches the orientation of the combiner 40 between the upright orientation and the lying orientation described above. Note that the HUD device 1 may be provided with a start button, and the CPU 51 may switch the orientation of the combiner 40 based on an on signal or an off signal of the start button.

[0029] Furthermore, when the CPU 51 turns the combiner 40 to the upright direction, it transmits image information based on the vehicle information output from the ECU 61 to the liquid crystal driver 24, and transmits brightness information to the LED driver 23. As a result, the CPU 51 adjusts the light transmittance of pixels in the display section of the liquid crystal panel 22 included in the display 20, and causes the LEDs of the backlight 21 to emit light. As a result, the CPU 51 causes the display 20 to emit display light L that represents an image including vehicle information.

[0030] Furthermore, the CPU 51 is electrically connected to adjustment buttons 26, 27 (also referred to as input devices) provided in the HUD device 1, and determines the pixel group that emits the display light L in the display section of the liquid crystal panel 22 based on the output of the adjustment buttons 26, 27.

[0031] In detail, the CPU 51 adjusts the light transmittance of a pixel group in a partial region (hereinafter referred to as the display region) in the display section of the above-mentioned liquid crystal panel 22, and generates the display light L only from the pixel group. The adjustment buttons 26, 27 are buttons for shifting the display region in the display section of the liquid crystal panel 22 and adjusting the position of the display region in order to direct the display light L in a direction according to the physique of the driver 5.

[0032] The adjustment buttons 26 and 27 will be described in detail. The adjustment button 26 is a button for shifting the position of the display area upward. For example, the adjustment button 26 is a button for shifting the position of the display area A shown by the solid line in FIG. 4 to the position of the display area A shown by the dashed line. The adjustment button 26 outputs an upward shift signal (also called position information) every time the driver 5 presses the adjustment button 26. In contrast, the adjustment button 27 is a button for shifting the position of the display area downward. For example, the adjustment button 27 is a button for shifting the position of the display area A shown by the solid line in FIG. 4 to the position of the display area A shown by the dotted line. The adjustment button 27 outputs a downward shift signal (also called position information) every time the driver 5 presses the adjustment button 27.

[0033] When the CPU 51 receives an up shift signal from the adjustment button 26, it adjusts the image information to be sent to the liquid crystal driver 24, and shifts the position of the display area A in the display section of the liquid crystal panel 22 upward by a fixed distance from the current position. Also, when the CPU 51 receives a down shift signal from the adjustment button 27, it adjusts the image information to be sent to the liquid crystal driver 24, and shifts the position of the display area A downward by a fixed distance from the current position. In this way, the CPU 51 shifts the display area A in response to the pressing of the adjustment buttons 26 and 27, and causes the pixel group included in the display area A to generate display light L. As a result, the CPU 51 directs the display light L in a direction in response to the pressing of the adjustment buttons 26 and 27.

[0034] Since there is a limit to the range in which the position of display area A can be shifted due to the size of the display section of liquid crystal panel 22, when the current position of display area A has reached the upper limit position, CPU 51 shifts the position of display area A only in response to a down shift signal, not an up shift signal. When the current position of display area A has reached the lower limit position, CPU 51 shifts the position of display area A only in response to an up shift signal, not a down shift signal.

[0035] In this way, the CPU 51 adjusts the position of the display area A in response to pressing of the adjustment buttons 26 and 27, and adjusts the direction in which the display light L is projected.

[0036] However, when the position of the display area A is adjusted, the incident angle θ of the display light L with respect to the combiner 40 shown in Fig. 1 changes, and as a result, the reflectance of the display light L reflected by the combiner 40 may change. This causes a change in the luminance of the display light L, and the visibility of the driver 5 may decrease.

[0037] The decrease in visibility for the driver 5 will be described in more detail with reference to Figures 5(A) and (B). Figures 5(A) and (B) are graphs of the reflectance of the display light L versus the incident angle θ of the combiner 40. Note that in Figures 5(A) and (B), a graph Gs of s-polarized light contained in the display light L is shown by a solid line. Also, a graph Gp of p-polarized light contained in the display light L is shown by a dotted line.

[0038] As shown in Figures 5(A) and (B), in both cases where the display light L is s-polarized light and where the display light L is p-polarized light, the reflectance of the combiner 40 changes according to the incident angle θ. In detail, as shown in Figure 5(A), when the display light L is s-polarized light, the reflectance of the combiner 40 increases as the incident angle θ increases. Also, when the display light L is p-polarized light, the reflectance of the combiner 40 decreases until the incident angle θ changes from 0 to Brewster's angle θb, and then the reflectance of the combiner 40 increases as the incident angle θ increases.

[0039] In this way, in the combiner 40, the reflectance varies depending on the incident angle θ. As a result, as shown in FIG. 5B, when the position of the display area A is adjusted and the incident angle θ changes by several degrees in the vicinity of 60-70°, which is often the incident angle θ of the display light L in the HUD device 1, the reflectance changes significantly. For example, when the position of the display area A is adjusted and the incident angle θ of the display light L changes from 65° to 70°, the reflectance changes by about 2-3 times in the case of p-polarized light. Also, the reflectance changes by about 1.5-1.6 times in the case of s-polarized light. Conversely, when the position of the display area A is adjusted and the incident angle θ of the display light L changes from 70° to 65°, the reflectance changes by about 0.3-0.5 times in the case of p-polarized light, and by about 0.6-0.7 times in the case of s-polarized light. Such a change in reflectance changes the luminance of the display light L reaching the driver 5, and in some cases the visibility of the driver 5 may be reduced.

[0040] Therefore, in order to suppress the decrease in visibility, in the HUD device 1, when the position of the display area A is shifted by the adjustment buttons 26 and 27, the microcomputer 50 adjusts the luminance of the backlight 21 in accordance with the shifted position.

[0041] The configuration of the microcomputer 50 will be described in detail. The microcomputer 50 includes a storage device 54 in which a luminance adjustment table 55 is stored, as shown in Fig. 2. The luminance adjustment table 55 is obtained in advance through experiments. In the luminance adjustment table 55, as shown in Fig. 6, positions P0, +Pn, -Pn (n = 1, 2, 3, ...) of the display area A in the display section of the liquid crystal panel 22 are associated with reflectances R1, R2, R3, ... of the display light L of the combiner 40 when the display light L is emitted from those positions.

[0042] Note that position P0 is the origin position of the display area A. Positions +Pn and -Pn are positions shifted upward or downward by a fixed distance n times from the origin position P0. Moreover, while the positions P0, +Pn, -Pn have been described as being specified by positions within the display section of the liquid crystal panel 22, it is preferable that the positions P0, +Pn, -Pn are specified by the incident angle θ of the display light L with respect to the combiner 40. In that case, it is preferable that the positions +Pn, -Pn are positions shifted upward or downward by a certain angle from the origin position P0. This is because the reflectances R1, R2, R3,... associated with these positions P0, +Pn, -Pn in the brightness adjustment table 55 are reflectances with respect to the incident angle θ.

[0043] 2, the storage device 54 stores position calculation data 56. The position calculation data 56 stores the current position of the display area A and the shift amount when the display area A is shifted up or down.

[0044] Each time the position of display area A is shifted in response to the up shift signal or down shift signal of adjustment buttons 26, 27, microcomputer 50 reads position calculation data 56 from storage device 54, and determines the current position of display area A after the shift from the current position and shift amount of display area A contained in position calculation data 56. Then, microcomputer 50 writes the determined current position of display area A into position calculation data 56 as the current position of display area A to use it as data for calculating the next current position.

[0045] Furthermore, the microcomputer 50 reads out the brightness adjustment table 55 from the storage device 54, and in the read out brightness adjustment table 55, specifies a position corresponding to the obtained current position of the display area A. Then, the microcomputer 50 divides the reflectance at the origin position P0 by the reflectance at the specified position to calculate a reflectance ratio indicating how many times the reflectance of the origin position P0 is compared to the specified position. The microcomputer 50 generates brightness information in which the brightness changes by the calculated reflectance ratio, and transmits the brightness information to the LED driver 23. As a result, the backlight 21 emits light at a brightness higher than the normal brightness by the calculated reflectance ratio. Or, it emits light at a lower brightness. By performing such processing, the microcomputer 50 adjusts the brightness of the display light L every time it receives an up shift signal or a down shift signal from the adjustment buttons 26 and 27 to shift the position of the display area A. As a result, the microcomputer 50 maintains the visibility of the virtual image V formed by the display light L.

[0046] As described above, in the HUD device 1 according to the first embodiment, the microcomputer 50 controls the luminance of the display light L projected by the display 20 to the combiner 40 based on the position of the display area A on the display 20, in other words, based on the projection position of the display light L on the combiner 40. For this reason, even if the projection position of the display light L on the combiner 40 is adjusted, the virtual image V is easily visible to the driver 5.

[0047] The microcomputer 50 acquires reflectance data of the display light L of the combiner 40 at the position of the display area A, and controls the luminance of the display light L based on the acquired reflectance data of the display light L. Therefore, the microcomputer 50 can accurately control the luminance of the display light L. As a result, the visibility of the virtual image V can be easily maintained uniform.

[0048] (Variation 1) In the above-described luminance adjustment table 55, the reflectance of the combiner 40 at each position in the display area A is simply associated with each position, but the luminance adjustment table 55 is not limited to this. In the luminance adjustment table 55, it is preferable that the position where the incident angle of the generated display light L to the combiner 40 is the Brewster angle θb shown in FIG. 5A or the position closest to the Brewster angle θb is the origin position P0, and that the reflectance based on the distance from the origin position P0 is associated with the positions +Pn and -Pn in the display area A. This is because such a luminance adjustment table 55 allows luminance adjustment that maintains the visibility of the virtual image V when the display light L is mainly p-polarized light.

[0049] In this case, it is desirable that the reflectance corresponding to positions +Pn, -Pn of the display area A of the brightness adjustment table 55 increases with increasing distance from the origin position P0. This is because, with such a brightness adjustment table 55, the microcomputer 50 can control the brightness of the backlight 21 to be lowered as the positions +Pn, -Pn of the display area A are farther away from the origin position P0. This is because, when the display light L is mainly p-polarized light, the visibility of the virtual image V can be effectively maintained.

[0050] The microcomputer 50 may adjust the luminance of the liquid crystal panel 22 without using such a luminance adjustment table 55. In this case, the microcomputer 50 may set a pixel of the liquid crystal panel 22 at a position where the incident angle of the generated display light L to the combiner 40 is the Brewster angle θb or at a position closest to the Brewster angle θb as a reference pixel, and control the luminance of the light emitted from each pixel of the liquid crystal panel 22 based on the position from the reference pixel.

[0051] (Variation 2) Moreover, in the brightness adjustment table 55, it is desirable that the corresponding reflectance increases as the incident angle to the combiner 40 of the display light L emitted from each of the positions P0, +Pn, and -Pn in the display area A increases. This is because such a brightness adjustment table 55 allows brightness adjustment that maintains the visibility of the virtual image V when the display light L is mainly s-polarized light.

[0052] In this case, the microcomputer 50 may adjust the luminance of the liquid crystal panel 22 without using the luminance adjustment table 55. In this case, the microcomputer 50 may perform control to lower the luminance of the light emitted from each pixel as the angle of incidence of the light emitted from each pixel of the liquid crystal panel 22 to the combiner 40 increases.

[0053] (Embodiment 2) In the first embodiment, the HUD device 1 includes adjustment buttons 26, 27, and the driver 5 presses the adjustment buttons 26, 27 to direct the display light L to a height desired by the driver 5. However, the present invention is not limited to this. The HUD device 1 may include a viewpoint information acquisition device that detects the viewpoint of the driver 5, instead of the adjustment buttons 26, 27.

[0054] In the second embodiment, the HUD device 1 includes an eye tracker, which is a type of viewpoint information acquisition device. The configuration of the second embodiment will be described below with reference to Fig. 7. In the second embodiment, the configuration different from the first embodiment will be mainly described.

[0055] Although not shown, eye tracker 28 is equipped with an imaging device that images driver 5, and an image processing device that extracts an image portion of the driver's 5 pupil or iris from the image captured by the imaging device to measure the gaze, and outputs viewpoint information including measured gaze data.

[0056] The microcomputer 50 receives the gaze data output by the eye tracker 28, and adjusts the position of the display area A described in the first embodiment to a position corresponding to the gaze point based on the gaze data. In detail, the microcomputer 50 calculates the shift amount of the position of the display area A from the origin position P0 based on the gaze data measured by the eye tracker 28. Then, the microcomputer 50 adjusts the image information to be sent to the liquid crystal driver 24 based on the calculated shift amount. In this way, the microcomputer 50 adjusts the position of the display area A to a position corresponding to the gaze point.

[0057] Furthermore, the microcomputer 50 reads out the brightness adjustment table 55 from the storage device 54, and reads out the reflectance associated with the position corresponding to the adjusted position of the display area A in the brightness adjustment table 55. The microcomputer 50 divides the reflectance at the origin position P0 by the read reflectance to calculate a reflectance ratio indicating how many times the reflectance of the origin position p0 is compared with the adjusted position of the display area A. As described in the first embodiment, the microcomputer 50 generates brightness information in which the brightness changes by the calculated reflectance ratio, and transmits the brightness information to the LED driver 23. As a result, the backlight 21 emits light at a brightness higher than the normal brightness by the calculated reflectance ratio. Or, it emits light at a lower brightness. As a result, the microcomputer 50 adjusts the brightness of the display light L to maintain the visibility of the virtual image V formed by the display light L.

[0058] As described above, in the HUD device 1 according to the second embodiment, the microcomputer 50 adjusts the position of the display area A of the display light L to a position corresponding to the line of sight based on the line of sight data output by the eye tracker 28. Therefore, even if the driver 5 changes and the height of the line of sight changes, the virtual image V by the display light L can be displayed at a position corresponding to the line of sight.

[0059] Furthermore, the microcomputer 50 controls the luminance of the display light L projected by the display 20 to the combiner 40, based on the position corresponding to the line of sight after the adjustment. Therefore, in the HUD device 1 according to the second embodiment, the visibility of the virtual image V is unlikely to decrease even if the driver 5 changes.

[0060] (Embodiment 3) In the first and second embodiments, the display 20 is configured with the backlight 21 and the liquid crystal panel 22, but the present invention is not limited thereto. In the present invention, the display 20 may display a virtual image by projecting the display light L onto a projection member, for example, the combiner 40. Therefore, the display 20 may have a configuration other than the backlight 21 and the liquid crystal panel 22, or may include a configuration other than the backlight 21 and the liquid crystal panel 22. For example, the display 20 may include a dial on which a symbol mark is formed, and a backlight that illuminates the dial.

[0061] In the first and second embodiments, the microcomputer 50 adjusts the position of the display area A in the display unit of the liquid crystal panel 22 based on the output of the adjustment buttons 26 and 27 or the viewpoint information of the eye tracker 28, and adjusts the brightness of the backlight 21 according to the adjusted position. However, the present invention is not limited to this. In the present invention, the microcomputer 50, i.e., the control unit, may control the brightness of the display light L projected by the display unit 20 based on the projection angle of the display light L to the projection target member, specifically based on the incident angle θ. For this reason, in the present invention, for example, the microcomputer 50 may adjust the position of the display area A in the display unit of the liquid crystal panel 22 based on the output of the adjustment buttons 26 and 27 or the viewpoint information of the eye tracker 28, adjust the brightness of the backlight 21 according to the adjusted position, and adjust the brightness of the backlight that illuminates the dial according to the adjusted position. Alternatively, the microcomputer 50 may directly adjust the brightness of the backlight that illuminates the dial based on the output of the adjustment buttons 26 and 27 or the viewpoint information of the eye tracker 28.

[0062] In the third embodiment, the HUD device 1 includes the dial and backlight described above, as well as an eye tracker 28, which is a type of viewpoint information acquisition device described in the second embodiment. A microcomputer 50 directly adjusts the brightness of the backlight based on viewpoint information from the eye tracker 28. The configuration of the third embodiment will be described below with reference to Figs. 8 to 10. The third embodiment will be described mainly with respect to the configuration different from the first and second embodiments.

[0063] As shown in FIG. 8, the display 20 has, in addition to the backlight 21 and liquid crystal panel 22 described in embodiments 1 and 2, a dial plate 71 on which a symbol mark is formed, and a second backlight 72 that illuminates the dial plate 71.

[0064] The dial plate 71 (also simply called a dial) is flat as shown in FIG. 9. The liquid crystal panel 22 and the second backlight 72 are arranged side by side, and the dial plate 71 covers both the liquid crystal panel 22 and the second backlight 72. The dial plate 71 has an opening in the portion covering the liquid crystal panel 22, and a symbol mark (not shown) for issuing a warning is formed in the portion covering the second backlight 72. The portion in which the symbol mark is formed is colored transparent, colorless transparent, or translucent, and light can pass through. The second backlight 72 shown in FIG. 9 is provided below the portion in which the symbol mark is formed.

[0065] In addition, a symbol mark for issuing a warning is also called a warning symbol mark or a telltale symbol mark, and is, for example, a mark that warns of a seat belt not being fastened or low gasoline.

[0066] The second backlight 72 (also simply referred to as backlight) is composed of, for example, an LED. The second backlight 72 is driven by a second LED driver 74 generating a PWM signal based on a command signal from the microcomputer 50 shown in Fig. 8, and lights up in response to the PWM signal and emits light at a brightness corresponding to the PWM signal. When turned on, the second backlight 72 irradiates the above-mentioned symbol mark portion of the dial plate 71 and generates display light L including the symbol mark.

[0067] On the other hand, the microcomputer 50 receives the viewpoint information output by the eye tracker 28 described in the second embodiment, and adjusts the luminance of the second backlight 72 based on the line of sight data included in the viewpoint information.

[0068] In detail, the microcomputer 50 calculates the incident angle θ of the display light L to the combiner 40 when the display light L visible from the line of sight measured by the eye tracker 28 is emitted toward the driver 5. Then, the microcomputer 50 further reads out the brightness adjustment table 57 from the storage device 54.

[0069] Here, the brightness adjustment table 57 will be described. In the first embodiment, it has been described that in the brightness adjustment table 55, the positions P0, +Pn, -Pn in the display section of the liquid crystal panel 22 are desirably specified by the incidence angle θ of the display light L with respect to the combiner 40, but in the brightness adjustment table 57 of the third embodiment, data is configured using this desirable specification method. Specifically, in the brightness adjustment table 57, the positions P0, +Pn, -Pn in the display section of the liquid crystal panel 22 correspond to the incidence angle θ of the display light L emitted at the positions P0, +Pn, -Pn with respect to the combiner 40.

[0070] In detail, as shown in FIG. 10, in the brightness adjustment table 57, the positions P0, +Pn, -Pn of the display area A within the display section of the liquid crystal panel 22 are associated with the angles of incidence θ1, θ2, θ3... of the display light L onto the combiner 40 when the display light L is emitted from those positions, and the reflectances R1, R2, R3... of the display light L of the combiner 40 when the display light L is emitted from those positions.

[0071] Returning to FIG. 8, the microcomputer 50 reads out the brightness adjustment table 57, and obtains the reflectance of the combiner 40 at the obtained incident angle θ based on the data of the incident angles θ1, θ2, θ3·· and the reflectances R1, R2, R3·· of the display light L included in the read brightness adjustment table 57. In addition, although it has been described in the first embodiment that the origin position is the position P0, the microcomputer 50 obtains the reflectance at the position P0, which is the origin position, from the brightness adjustment table 57. The microcomputer 50 divides the reflectance at the origin position P0 by the reflectance of the combiner 40 at the obtained incident angle θ to calculate a reflectance ratio indicating how many times the reflectance of the origin position P0 is compared with the specified position. The microcomputer 50 generates brightness information in which the brightness changes by the calculated reflectance ratio, and transmits the brightness information to the second LED driver 73 shown in FIG. 8. As a result, the second backlight 72 emits light at a brightness higher than the normal brightness by the calculated reflectance ratio. Or, it emits light at a low luminance. As a result, the luminance of the display light L is adjusted to a luminance according to the line of sight data measured by the eye tracker 28. In this way, the microcomputer 50 maintains the visibility of the virtual image V of the display light L generated by the dial plate 71 and the second backlight 72.

[0072] The display 20 includes a light receiving sensor 74 that detects light emitted by the second backlight 72, and the microcomputer 50 (also referred to as a sensor control unit) determines the presence or absence of an abnormality in the second backlight 72 based on the output value of the light receiving sensor 74. For example, when the output value of the light receiving sensor 74 is smaller than a threshold value, the microcomputer 50 determines that there is a break in the wire of the second backlight 72. At this time, the microcomputer 50 may vary the threshold value according to the reflectance ratio calculated in the above-mentioned step of calculating the reflectance ratio, and use the varying threshold value to determine the break in the second backlight 72.

[0073] As described above, in the HUD device 1 according to the third embodiment, the display 20 has the dial plate 71 having a symbol mark and the second backlight 72 that illuminates the dial plate 71. The microcomputer 50 adjusts the luminance of the second backlight 72 based on the line-of-sight data output by the eye tracker 28. Therefore, even if the height of the line of sight of the driver 5 changes, the brightness of the display light L is maintained, and the visibility of the virtual image V is unlikely to decrease.

[0074] Although the head-up display device and the control method for the head-up display device according to the first and second embodiments of the present invention have been described above, the present invention is not limited to this.

[0075] For example, in the first and second embodiments, the luminance adjustment table 55 associates each position P0, +Pn, -Pn in the display area A with the reflectance at each position. The microcomputer 50 reads out the luminance adjustment table 55 and generates the luminance information to be transmitted to the LED driver 23 from the reflectance data in the luminance adjustment table 55. However, the present invention is not limited to this. The luminance adjustment table 55 may associate each position P0, +Pn, -Pn in the display area A with luminance data indicating the luminance of the backlight 21. The microcomputer 50 may then read out the luminance adjustment table 55 and determine the luminance information to be transmitted to the LED driver 23 from the luminance data in the luminance adjustment table 55.

[0076] In the first and second embodiments, the HUD device 1 includes the combiner 40, but in the present invention, the HUD device 1 may not include the combiner 40, and the virtual image V may be formed by projecting the display light L onto the windshield 3 and reflecting the display light L on the windshield 3. In this case, the reflectance associated with each position P0, +Pn, -Pn of the display area A on the brightness adjustment table 55 may be the reflectance of the display light L on the windshield 3, rather than the reflectance of the display light L on the combiner 40.

[0077] In addition, in the present invention, a HUD device 1 including the combiner 40 and a HUD device not including the combiner 40 may be used together.

[0078] Furthermore, in the first and second embodiments, the HUD device 1 includes a mirror member 30. However, in the present invention, the HUD device 1 is not limited to this. In the present invention, the HUD device 1 may include a display 20 that displays a virtual image V by projecting the display light L onto a projection member, and a microcomputer 50, i.e., a control unit, that controls the brightness of the display light L projected by the display 20 based on the incident angle of the display light L to the projection member, i.e., the projection angle. Therefore, in the present invention, the mirror member 30 is an arbitrary member. In the HUD device 1, the display 20 may directly project the display light L onto the combiner 40. For example, as shown in FIG. 11, the HUD device 1 may include a display 20 housed in a housing 10, the display 20 emitting the display light L toward an opening 11 formed on a top plate portion and covered by a dust cover 12, and a combiner 40 held by a holder 42 provided on the housing 10 and onto which the display light L emitted from the opening 11 is projected.

[0079] In the first and second embodiments, the projection position of the display light L on the combiner 40, specifically the incident angle of the display light L on the combiner 40, is adjusted by changing the display area A in the display unit of the liquid crystal panel 22 included in the display device 20. However, the present invention is not limited thereto. As described above, in the present invention, the display device 20 may display the virtual image V by projecting the display light L on a projection target member. Therefore, the projection angle when the display light L is projected on the projection target member may be adjusted without changing the display area A in the display unit of the liquid crystal panel 22. For example, the HUD device 1 may include a movable mirror that reflects the display light L from the display device 20 and directs the reflected display light L to the combiner 40, and the incident angle of the display light L on the combiner 40 may be adjusted by moving the movable mirror. [Explanation of symbols]

[0080] 1 HUD device 2 Vehicles 3 Windshield 4. Dashboard 5. Driver 10. Chassis 11 Opening 12 Dust cover 20 Display 21 Backlight 22 Liquid crystal panel 23 LED Driver 24 LCD driver 25 Combiner drive motor 26,27 Adjustment buttons 28 Eye Tracker 30 Mirror material 40 Combiner 41 Support member 42 Holder 50 Microcomputer 51 CPU 52 ROM 53 RAM 54 Storage device 55,57 Brightness adjustment table 56 Position calculation data 60 CAN signal lines 61 ECU 62 IGSW 71 Dial Plate 72 Second Backlight 73 Second LED driver 74 Light receiving sensor A Display area B Back F forward Gp,Gs graph L display light V Virtual Image θ angle of incidence

Claims

1. a display that displays a virtual image by projecting the display light onto a projection member; a control unit that controls the luminance of the display light projected by the display device based on a projection angle of the display light with respect to the projection target member; A head-up display device comprising:

2. the display device includes a plurality of pixels each of which projects the display light to display the virtual image representing an image; the control unit controls the luminance of the display light emitted from each of the plurality of pixels based on a position from a reference pixel at which the projection angle is closest to Brewster's angle, among the plurality of pixels. The head-up display device according to claim 1 .

3. the control unit reduces the luminance of the display light emitted from each of the plurality of pixels as the position of the pixel becomes farther from the reference pixel. The head-up display device according to claim 2 .

4. the control unit reduces the luminance of the display light of each of the pixels as the projection angle of the display light emitted from each of the plurality of pixels to the projection target increases. The head-up display device according to claim 2 .

5. A viewpoint information acquisition device is provided for acquiring viewpoint information of a user viewing the virtual image, the display displays the virtual image in a partial region within a display region in which the virtual image can be displayed when all of the pixels project the display light by causing some of the pixels to project the display light; the control unit selects pixels that are to be the part of the plurality of pixels based on the viewpoint information acquired by the viewpoint information acquisition device, and projects the display light onto the selected pixels, thereby adjusting a position of the part of the display area. The head-up display device according to claim 2 .

6. an input device for inputting position information of a partial area in which the virtual image is displayed by projecting the display light from a part of the plurality of pixels within a display area in which the virtual image can be displayed when the entirety of the plurality of pixels projects the display light; the control unit selects pixels that are to be the part of the plurality of pixels based on position information of the partial region input to the input device, and projects the display light to display the virtual image in the partial region. The head-up display device according to claim 2 .

7. The display device has a dial on which a symbol mark is formed and a backlight for illuminating the dial. The head-up display device according to claim 1 .

8. A viewpoint information acquisition device is provided for acquiring viewpoint information of a user viewing the virtual image, the control unit calculates a projection angle of the display light visually recognized by the user with respect to the projection target member based on the viewpoint information acquired by the viewpoint information acquisition device, and controls the luminance of the backlight based on the calculated projection angle. The head-up display device according to claim 7.

9. The display device includes: a light receiving sensor that detects light emitted by the backlight; a sensor control unit that determines that the backlight is disconnected when an output of the light receiving sensor is less than a threshold value; and The sensor control unit changes the threshold value in accordance with the luminance of the backlight based on the projection angle. The head-up display device according to claim 7 or 8.

10. A method for controlling a head-up display device including a display device that displays a virtual image by projecting display light onto a projection member, comprising: controlling the luminance of the display light projected by the display device based on a projection angle of the display light with respect to the projection target member; A method for controlling a head-up display device comprising:

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