Head-up display device, control method for head-up display device, and display control program

Abstract

To reduce discomfort experienced by a viewer due to overlapping of a forward field of view of a vehicle and a virtual image, even when a depression angle determined depending on the viewer's height is small.SOLUTION: A head-up display device (HUD device 100) that forms, on an imaging plane virtually set in front of a vehicle, an image in which scenery of a forward field of view of the vehicle and a generated virtual image are superimposed and allows a viewer to view the image, includes an image display unit 30 that displays the virtual image, and a control unit 10 that controls the image display unit 30 to display the virtual image with reduced display brightness when a depression angle being an angle formed between a virtual line parallel to a road surface from a viewpoint position in a height direction of the eyes of the viewer and a straight line connecting the viewpoint position and a center of the virtual image is smaller than a standard value.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a head-up display device or the like that superimposes a foreground, which is the scenery in the forward field of view of the vehicle, and a generated virtual image on an imaging plane that is virtually set in front of the vehicle, and projects the image onto a projection target so that the viewer can see it. [Background technology]

[0002] A head-up display device is known that has an imaging optical system that projects an image onto a projection target mounted on a vehicle, and superimposes the scenery in the vehicle's forward field of view (foreground) and the generated virtual image onto an imaging surface virtually set in front of the vehicle, and projects the image onto the projection target, allowing the viewer to view it. To enable the driver (the viewer) to view the virtual image, the head-up display device must recognize and set the position of the eyebox according to the viewer's height. This changes the depression angle, which is the angle between a virtual line parallel to the road surface from the viewer's eye-height (eyebox) and a straight line connecting the viewer's viewpoint and the center of the virtual image.

[0003] For example, Patent Document 1 describes a display control device technology that suppresses fluctuations in the display position of an image due to pitching or rolling of a vehicle by controlling a control unit that performs image correction including at least one of pitching correction and rolling correction, so that if it is determined that the viewpoint position in the eye height direction of the viewer, the driver, is higher than a standard position, the amount of image correction is made larger than the amount of correction from the standard position, and if it is determined that the viewpoint position is lower, the amount of correction is made smaller than the amount of correction from the standard position. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2012-128906 (see paragraphs

[0011] to

[0015] and Figure 3) Summary of the Invention [Problem to be solved by the invention]

[0005] In the above-described head-up display device, if the depression angle, which is determined depending on the viewer's height, is small, i.e., for a short viewer, the virtual image is inevitably displayed higher. This means that when the viewer, the driver, directs his or her gaze forward to drive, the virtual image is likely to enter the viewer's line of sight. Head-up display devices are expected to have the advantage of allowing the viewer to view information (images displayed by the head-up display device) with minimal eye movement. However, if the virtual image is displayed in the same direction (very close) as the driver's gaze to drive, the driver's visual attention will be excessively directed to the virtual image rather than the foreground ahead of the vehicle. For this reason, it is expected that the virtual image entering the driver's line of sight will cause the driver to feel annoyed and get in the way when trying to check the forward visibility for driving. Patent Document 1 does not mention this issue at all, nor does it mention any solutions to address it.

[0006] An object of the present invention is to provide a head-up display device or the like that can reduce the annoyance felt by the driver due to the overlap of the forward field of view of the vehicle with a virtual image, even when the depression angle, which is determined depending on the height of the driver who is the viewer, is small.

[0007] Other objects of the present invention will become apparent to those skilled in the art by referring to the following exemplary aspects and best modes, as well as the accompanying drawings. [Means for solving the problem]

[0008] In order to facilitate an understanding of the outline of the present invention, the following examples are given of embodiments according to the present invention.

[0009] A first aspect of the present invention is a head-up display device that superimposes a foreground, which is the scenery in the forward field of view of the vehicle, and a generated virtual image on an imaging plane that is virtually set in front of the vehicle, and projects the image onto a projection target so that the viewer can view it.The head-up display device has an image display unit that displays the virtual image, and a control unit that controls the display of the virtual image on the image display unit to reduce the display brightness if the depression angle, which is the angle between a virtual line parallel to the road surface from the viewpoint position at eye height of the viewer and a straight line connecting the viewpoint position and the center of the virtual image, is smaller than a standard value.

[0010] In the first aspect, for example, as shown in Figure 1, when the depression angle LD, which is the angle between a virtual line VL parallel to the road surface from the viewer's viewpoint at eye height and a straight line (shown as a dashed line in Figure 1) connecting the viewer's viewpoint and the center of the virtual image V, is smaller than a standard value, in other words, when the viewer is short, the control unit performs control to lower the display brightness of the virtual image V.This makes it less noticeable when the viewer, the driver, tries to check the forward field of view, and therefore reduces the annoyance felt by the viewer due to the virtual image getting in the way.

[0011] In a second aspect dependent on the first aspect, the control unit may have a dimming table in which the display brightness is set, and may perform control such that the setting value of the display brightness set in the dimming table gradually decreases as the depression angle becomes smaller.

[0012] In a second aspect, the control unit performs control such that the smaller the depression angle of the virtual image (display area) seen by the viewer, the gradually lower the setting value of the display brightness set in the dimming table. The depression angle of the virtual image (display area) seen by the viewer can vary depending on, for example, the viewer's height. Generally, the shorter the viewer's height (the lower the viewer's eye height), the smaller the depression angle of the virtual image (display area) seen by the viewer. Furthermore, when the height of the area (eyebox) in which the virtual image can be properly viewed is changed according to the viewer's height, the height of the virtual image (display area) also changes. Specifically, when the height of the area (eyebox) in which the virtual image can be properly viewed is lowered by controlling the head-up display device, the position of the display area becomes higher. In other words, the depression angle of the virtual image (display area) seen by the viewer becomes smaller due to the lower eye height (the height of the eyebox adapted thereto) and the higher position of the display area. Conversely, if the height of the area (eyebox) in which the virtual image can be properly viewed is increased by controlling the head-up display device, the position of the display area will be lowered. That is, the depression angle of the virtual image (display area) seen by the viewer increases due to the high eye height (the height of the eyebox adapted thereto) and the low position of the display area. In the second aspect, the display brightness is changed according to the depression angle. The depression angle of the virtual image (display area) seen by the viewer can be estimated from the position of the viewer's eyes in the height direction, which is detected by a DMS or the like. The depression angle of the virtual image (display area) seen by the viewer can also be estimated from setting information on the height direction position of the display area (for example, the angle of the concave mirror in the head-up display device).

[0013] In a third aspect dependent on the second aspect, the control unit may have a dimming table in which the display brightness is set, and if the depression angle is equal to or greater than the standard value, the control unit may perform control to keep the set value of the display brightness constant regardless of the depression angle. For example, as shown in the block surrounded by the dashed line in Figure 7, the display brightness value is set to "1" for "shorter1," a viewer with a small depression angle among "shorters," the display brightness value is set to "2" for "shorter2," a viewer with a large depression angle among "shorters," and the display brightness value is set to "3" for "nominal," a viewer with a standard height other than "shorters," and "taller," a viewer with a tall height.

[0014] That is, "shorter1" has the lowest display brightness value, and "shorter2" has the second lowest display brightness value. Furthermore, for "nominal" and "taller," the display brightness value is set higher than for "shorter," but remains constant regardless of the depression angle (the display brightness value is set to "3" in both cases). In this way, when a shorter viewer tries to check the forward field of view (foreground) while driving, even if a virtual image is superimposed, the display brightness value tends to be lower and less noticeable, reducing the annoyance it may cause.

[0015] In a fourth aspect dependent on the first aspect, the control unit may perform control to gradually decrease the display brightness when the depression angle is smaller than the standard value by a predetermined difference, control to gradually decrease the display brightness value when the depression angle is smaller by a first difference in a first region, and further control to gradually decrease the display brightness when the depression angle is smaller by a second difference that is smaller than the first difference in a second region lower than the first region.

[0016] In a fourth aspect, the control unit performs control to gradually decrease the display brightness if the viewpoint position in the eye height direction of the viewer (the depression angle determined depending on the viewer's height) is smaller by a predetermined difference. For example, as shown in FIG. 8, in a first region (see "taller" to "nominal"), the control unit performs control to gradually decrease the display brightness if the depression angle is smaller by a first difference, and in a second region (see "shorter2" to "shorter1") lower than the first region, the control unit performs control to gradually decrease the display brightness if the depression angle is smaller by a second difference that is smaller than the first difference. Here, the first difference for "taller" to "nominal" to "shorter2" is roughly the same, and the second difference is about 60% of the first difference. For short viewers, even slight differences (differences) in height can greatly affect the degree to which the virtual image superimposed on the field of view ahead of the vehicle is perceived as a nuisance. Therefore, even for short viewers other than "shorter1" and "shorter2" ("taller" - "nominal"), the smaller the depression angle becomes depending on height, so by controlling the display brightness value set in the dimming table to gradually decrease, it is possible to provide an optimal viewing environment for short viewers with a finer display brightness that reflects differences in height and reduce annoyance.

[0017] In a fifth aspect dependent on any one of the second to fourth aspects, the control unit After the setting value of the display brightness in the light adjustment table is determined, control may be performed so that the light adjustment table is not changed even if the depression angle is changed by the viewer adjusting the depression angle.

[0018] In the fifth aspect, after the setting value of the display brightness for the dimming table has been determined, the control unit controls the dimming table so that it does not change even if the depression angle changes due to the viewer adjusting the depression angle.As a result, even if the display position of the virtual image is changed due to the depression angle adjustment, the display brightness does not change, so the virtual image can be moved to a preferred display position while maintaining the display brightness.

[0019] In a sixth aspect dependent on any of the second to fourth aspects, the control unit may be configured to, after the setting value of the display brightness for the dimming table has been determined, change the setting value of the display brightness for the dimming table in accordance with the changed depression angle when the depression angle is changed by the viewer adjusting the depression angle.

[0020] In the sixth aspect, after the setting value of the display brightness on the dimming table has been determined, if the viewer adjusts the depression angle to change the depression angle, the control unit performs control to change the setting value of the display brightness on the dimming table in accordance with the changed depression angle, thereby making it possible to change the brightness when the display position of the virtual image is changed by adjusting the depression angle, and by performing control to reduce the brightness at this time, it is possible to reduce the annoyance felt by viewers of short stature.

[0021] In a seventh aspect dependent on the fifth or sixth aspect, the image forming optical system includes an operating member and an optical member that projects the virtual image onto the imaging surface, and the control unit may operate the operating member to rotate the optical member, thereby allowing the viewer to adjust the depression angle.

[0022] In the seventh aspect, the control unit operates an operating member (for example, the operation input device 302 shown in FIG. 2) to rotate an optical member such as a concave mirror (see 141 in FIGS. 3(a) and 3(b)), thereby allowing the viewer to adjust the depression angle, thereby facilitating and speeding up the identification of the height position of the viewer's eye gaze (estimating the position of the eye box). Note that the position information of the optical member (such as the rotation angle of the concave mirror) obtained by adjusting the depression angle can be used as objective data for estimating the height position of the viewer's gaze point.

[0023] In an eighth aspect dependent on the fifth or sixth aspect, the control unit may estimate the depression angle by performing image recognition based on an image of the viewer's eyes obtained by photographing the viewer, with respect to the viewpoint position in the eye height direction, or by detecting the setting position of a seat on which the viewer is seated.

[0024] In the eighth aspect, the control unit performs image recognition based on an image of the viewer's eyes obtained by photographing the viewer, regarding the viewpoint position in the eye height direction, or estimates the depression angle by detecting the set position of the seat on which the viewer is seated, thereby being able to determine the viewer's height with high accuracy.

[0025] A ninth aspect is a control method for a head-up display device having a control unit and an image display unit, which superimposes a foreground, which is the scenery in the forward field of view of the vehicle, and a generated virtual image on an imaging plane that is virtually set in front of the vehicle, and projects the superimposed image onto a projection target so that the viewer can view it.The control unit has a first step of comparing the depression angle, which is the angle between a virtual line parallel to the road surface from the viewer's viewpoint in the height direction and a straight line connecting the viewpoint and the center of the virtual image, with a standard value, and a second step of controlling the image display unit to lower the display brightness of the virtual image if the depression angle is smaller than the standard value.

[0026] In the ninth aspect, a control unit controls the display brightness of the virtual image V to be lowered when the depression angle LD, which is the angle between a virtual line VL parallel to the road surface from the viewpoint position at eye height of the viewer and a straight line (shown as a wavy line in FIG. 1) connecting the viewpoint position and the center of the virtual image V, is smaller than a standard value, for example, as shown in FIG. 1, in other words, when the viewer is short, so that when the viewer, the driver, tries to check the forward field of view, the virtual image V displayed superimposed on the forward field of view becomes less noticeable, thereby providing a control method for a head-up display device that can reduce the annoyance felt by the viewer due to the virtual image V getting in the way.

[0027] A tenth aspect is a display control program for a head-up display device having a control unit and an image display unit, which superimposes a foreground, which is the scenery in the forward field of view of the vehicle, and a generated virtual image on an imaging plane that is virtually set in front of the vehicle, and projects the image onto a projection target so that the viewer can view it.The program causes a processor in the control unit to execute a first process of comparing the depression angle, which is the angle between a virtual line parallel to the road surface from the viewer's viewpoint in the height direction and a straight line connecting the viewpoint position and the center of the virtual image, with a standard value, and a second process of controlling the image display unit to lower the display brightness of the virtual image if the depression angle is smaller than the standard value.

[0028] In the tenth aspect, a processor possessed by a control unit of a head-up display device sequentially reads and executes a display control program recorded in an internal or external memory, and, for example, as shown in Figure 1, when the depression angle LD, which is the angle between a virtual line VL parallel to the road surface from the viewpoint position at eye height of the viewer and a straight line (shown as a wavy line in Figure 1) connecting the viewpoint position of the viewer and the center of the virtual image V, is smaller than a standard value, in other words, when the viewer is short, control is performed to lower the display brightness of the virtual image V. This makes the virtual image V, which is displayed superimposed on the forward field of view, less noticeable when the viewer, the driver, tries to check the forward field of view, thereby reducing the annoyance felt by the viewer due to the virtual image V getting in the way.

[0029] Those skilled in the art will easily understand that the exemplified embodiments according to the present invention can be further modified without departing from the spirit of the present invention. [Brief explanation of the drawings]

[0030] [Figure 1] FIG. 1 is a diagram showing an example of application of a head-up display device according to an embodiment of the present invention to a vehicle. [Figure 2] FIG. 2 is a block diagram showing a head-up display device according to an embodiment of the present invention and a peripheral configuration of the head-up display device included in a vehicle display device. [Figure 3]FIG. 3 is a diagram showing the cross-sectional structure of a head-up display device according to an embodiment of the present invention, in which FIG. 3(a) shows the rotation of the optical element (concave mirror) when the eyebox is in the reference position, and FIG. 3(b) shows the rotation of the optical element (concave mirror) when the position of the eyebox is changed. [Figure 4] FIG. 4 is a flowchart showing the operation of the head-up display device according to the embodiment of the present invention. [Figure 5] FIG. 5 shows an example of the data structure of a dimming table stored in a memory unit of a head-up display device according to an embodiment of the present invention, where FIG. 5(A) shows a dimming table based on illuminance, and FIG. 5(B) shows the brightness (display brightness) for each viewer's eye height (viewpoint position) at illuminance L(x). [Figure 6] FIG. 6 is a diagram (part 1) cited to explain the relationship between the display position of the foreground where the eyebox virtual image is superimposed and displayed, and the relationship with the display luminance value set in the eyebox dimming table. [Figure 7] FIG. 7 is a diagram (part 2) cited to explain the relationship between the display position of the foreground on which the virtual image is superimposed for each eyebox and the display brightness value set in the eyebox dimming table. [Figure 8] Figure 8 is a diagram (part 3) cited to explain the relationship between the display position of the foreground on which the virtual image is superimposed for each eyebox and the display brightness value set in the eyebox dimming table. [Figure 9] FIG. 9 is a diagram (part 1) cited to explain the range over which the virtual image can be moved as a result of depression angle adjustment by the driver who is the viewer, and the display brightness after adjustment. [Figure 10] FIG. 10 is a diagram (part 2) cited to explain the range over which the virtual image can be moved as a result of depression angle adjustment by the driver who is the viewer, and the display brightness after adjustment. DETAILED DESCRIPTION OF THE INVENTION

[0031] The best mode described below is used to facilitate understanding of the present invention, and therefore, those skilled in the art should be aware that the present invention is not unduly limited by the mode described below (hereinafter referred to as the present mode).

[0032] (Configuration of the embodiment) FIG. 1 shows an example of application of a head-up display device (hereinafter referred to as an HUD device 100) of this embodiment to a vehicle CR.

[0033] 1, the projection display by the HUD device 100 is a display device provided inside the instrument panel IP of the vehicle CR, and the display light L projected by the HUD device 100 is reflected by the windshield WS of the vehicle CR toward the driver DR, who is a viewer seated in the driver's seat inside the cabin of the vehicle CR, to display a virtual image V. Here, the HUD device 100 can display the virtual image V anywhere within a specific display area VA (virtual image formation surface) that is virtually set in front of the vehicle CR.

[0034] In other words, the HUD device 100 emits (projects) display light L emitted from a liquid crystal display 120 (see FIG. 2) of the image display unit 30, which will be described later, onto a windshield WS, which is a member to be projected, and allows the driver DR, who is a viewer, to view the display light L (virtual image V) obtained in response to this emission. This allows the driver DR to view the virtual image V superimposed on the foreground, which is the scenery ahead of the vehicle CR.

[0035] In this case, the HUD device 100 projects display light L such that the virtual image V is tilted at an angle of 45 degrees or less (0 to 45 degrees) with respect to the road surface on which the vehicle CR is traveling, and the upper part of the virtual image V appears to be tilted farther away from the viewer than the lower part. This allows the driver DR, who is the guide vehicle, to view the virtual image V displayed mainly superimposed on the road surface ahead of the vehicle CR, and obtain various information indicated by the content of the image.

[0036] In the HUD device 100, an eyebox IB is set to be the same as the area (also called the iris) where the driver DR's viewpoint is expected to be located, or to include a large portion (e.g., 80% or more) of the iris. The term "eyebox" used in the description of this embodiment refers to (1) an area within which the entire virtual image V of the image displayed by the liquid crystal display 120 can be seen, and at least a portion of the virtual image V of the image cannot be seen outside the area, (2) an area within which at least a portion of the virtual image V of the image can be seen, and at least a portion of the virtual image V of the image cannot be seen outside the area, (3) an area within which at least a portion of the virtual image V of the image can be seen with a predetermined brightness or higher, and at least a portion of the virtual image V of the image cannot be seen outside the area, or (4) an area within which, when the HUD device 20 can display a virtual image V that can be seen stereoscopically, at least a portion of the virtual image V can be seen stereoscopically, and at least a portion of the virtual image V cannot be seen stereoscopically outside the area. That is, if the observer places his / her eyes (both eyes) outside the eyebox IB, the observer cannot see the entire virtual image V of the image displayed by the liquid crystal display 120, the entire visibility of the virtual image V of the image is very low and it is difficult to perceive, or the observer cannot see the virtual image V of the image in three dimensions. The predetermined brightness is, for example, about 1 / 50 of the brightness of the virtual image of the image viewed at the center of the eyebox.

[0037] FIG. 2 is a block diagram showing an example of the configuration of a vehicle display system 1000 to which the HUD device 100 of this embodiment is applied.

[0038] As shown in FIG. 2, the vehicle display system 1000 includes the HUD device 100 of this embodiment, a DMS (Driver Monitoring System) 301, an operation input device 302, and a vehicle monitoring device 303, all of which are connected to a CAN (Control Area Network) 200, which is an in-vehicle LAN.

[0039] The HUD device 100 of this embodiment is a head-up display device that superimposes a foreground FV, which is the scenery in the forward field of view of the vehicle CR, and a generated virtual image V on an imaging plane VA that is virtually set in front of the vehicle CR, and allows the viewer, the driver DR, to see the image, and includes a control unit 10, a memory unit 20, and an image display unit 30.

[0040] For example, as explained in Figure 1, when the depression angle LD, which is the angle between a virtual line VL parallel to the road surface from the viewpoint position at eye height of the viewer, the driver DR, and a straight line connecting the viewpoint position and the center of the virtual image V, is smaller than a standard value, the control unit 10 controls the image display unit 30 (liquid crystal display 120) to lower the display brightness of the virtual image V.

[0041] The control unit 10 also has a light adjustment table 20a (stored in a partial storage area of ​​the storage unit 20) in which the display brightness is set, and can perform control such that the display brightness setting value set in the light adjustment table 20a gradually decreases as the depression angle LD, which is determined depending on the height of the driver DR who is the viewer, becomes smaller. The control unit 10 can also perform control such that the display brightness setting value set in the light adjustment table 20a gradually decreases as the depression angle LD becomes smaller, even if the depression angle LD is the same as or greater than the standard value.

[0042] For example, as shown in the block surrounded by the dashed line in Figure 7 (described later), the display luminance value is set to "1" for "shorter1," a viewer with a small depression angle LD among "shorters," a viewer of short stature; the display luminance is set to "2" for "shorter2," a viewer with a large depression angle LD among "shorters," and the display luminance is set to "3" for "nominal," a viewer of average height other than "shorter," and "taller," a viewer of tall stature. In other words, the display luminance value is the lowest for "shorter1," and the second lowest for "shorter2." Furthermore, the display luminance values ​​for "nominal" and "taller" are set higher than for "shorter," but are constant regardless of the depression angle LD (the display luminance value is set to "3" for both).

[0043] Furthermore, the control unit 10 performs control to gradually decrease the display brightness if the depression angle LD is smaller by a predetermined difference. For example, as shown in FIG. 8, in a first region (see, for example, "taller" to "nominal" in FIG. 8), the control unit 10 performs control to gradually decrease the display brightness if the viewpoint position in the eye height direction of the driver DR (depression angle LD determined depending on the viewer's height) is smaller by a first difference, and in a second region (see "shorter2" to "shorter1") lower than the first region, the control unit 10 performs control to gradually decrease the display brightness if the viewpoint position in the eye height direction of the driver DR (depression angle LD determined depending on the viewer's height) is smaller by a second difference that is smaller than the first difference. Here, the first difference for "taller" to "nominal" to "shorter2" is roughly the same, and the second difference is about 60% of the first difference. For a viewer of short stature, even a slight difference in height can significantly change the degree to which the virtual image superimposed on the viewer's forward field of vision from the vehicle is perceived as a nuisance. Therefore, even for a viewer other than a "shorter" ("taller" - "nominal") who is a viewer DR of short stature, the smaller the depression angle LD becomes depending on the height, the more control can be performed to gradually decrease the display brightness value set in the dimming table 20a. Specifically, when the depression angle LD changes from "taller" to "nominal" by the first difference, the display brightness is decreased by one step (the display brightness for "taller" is decreased by 10% of the display brightness for "taller"). Also, when the depression angle LD changes by the first difference from "nominal" to "shorter2," the display brightness is decreased by one step (the display brightness for "nominal" is decreased by 10% of the display brightness for "taller"). On the other hand, when the depression angle LD changes from "shorter2" to "shorter1" by a second difference (smaller than the first difference), the display brightness is also lowered by one step (reducing the display brightness of "shorter2" by 10% of the display brightness at "taller").

[0044] Furthermore, after the setting value of the display brightness for the light adjusting table 20a has been determined, the control unit 10 can perform control not to change the light adjusting table 20a even if the depression angle LD changes due to depression angle adjustment by the driver DR, who is the viewer. Also, the control unit 10 can perform control to change the setting value of the display brightness for the light adjusting table 20a in accordance with the changed depression angle LD. Here, the depression angle adjustment by the driver DR, who is the viewer, is performed by operating an operation member (operation input device 302) to rotate and drive the optical members 130 and 140 (for example, concave mirror 141).

[0045] In addition, the control unit 10 can estimate the depression angle LD by performing image recognition based on an image of the eyes of the driver DR, who is the viewer, obtained by photographing the driver DR, or by detecting the set position of the seat on which the driver DR, who is the viewer, is seated, with respect to the viewpoint position in the eye height direction.

[0046] To perform the above-described control, the control unit 10 includes, for example, a processor with built-in memory (ROM / RAM) or an external memory, and a graphics controller that draws images generated by the processor in a video RAM (VRAM) allocated to a predetermined area of ​​the RAM and displays the images on the image display unit 30 (liquid crystal display 120) according to the display timing, and the processor executes a program recorded in the ROM to perform the above-described functions. Also, at least some of the above-described functions can be realized by hardware such as a field programmable gate array (FPGA) or logic circuit, without using a processor.

[0047] The storage unit 20 is a memory that is allocated a program area and a work area and that implements, for example, static RAM, dynamic RAM, flash memory, etc. Here, various programs such as a display control program required to control the HUD device 100 of this embodiment are written in the program area, and information generated in the execution process of the various programs described above, for example, a dimming table 20a whose data structure is shown in Fig. 5, as well as a reference value (standard value) for the depression angle LD and a display brightness value that is set by default are assigned and written in the work area.

[0048] FIG. 5 shows an example of the data structure of the light adjustment table 20a. In the HUD device 100 of this embodiment, when the depression angle LD is smaller than a standard value, the control unit 10 controls the image display unit 30 (liquid crystal display 120) to display the virtual image V at a lower display brightness. For example, when L(x) is set as a reference illuminance, the control unit 10 controls the luminance to be relatively constant by changing the luminance relative to the illuminance. FIG. 5(A) shows an example of the data structure of the light adjustment table 20a based on the illuminance in the environment in which the virtual image V displayed by the HUD device 100 is viewed (for example, the detected value of an illuminance sensor (not shown) provided in the vehicle CR). As the illuminance of the surrounding environment increases (L(x-2), L(x-1), L(x), L(x+1)), the HUD device 100 gradually increases the display brightness (B(x-2), B(x-1), B(x), B(x+1)). In addition, if H(y) is the reference viewpoint position of the viewer, the driver DR, and anything below that is designated as "shorter," and control is exercised to reduce the display brightness for "shorter," an example of the data structure of the dimming table 20a for each viewpoint position of the viewer, the driver DR, at illuminance L(x) is shown in Figure 5(B).

[0049] In the dimming table 20a shown in FIG. 5(B), a standard display luminance B(x) is set using the position H(y) of the eyebox IB of a viewer of average height as the reference eye height, and the display luminance is set to decrease sequentially from B(x-1) to B(x-2) as the viewer's height decreases (H(y-1) → H(y-2)). On the other hand, for a tall viewer whose eyebox IB is positioned (H(y+1)) higher than the reference position H(y) of the eyebox IB, the display luminance is set to the same as the standard display luminance B(x). Note that the standard display luminance shown in FIG. 5(B) is B(X), which is set when the illuminance is L(x). For example, if the illuminance is L(x-1), the standard display luminance may be changed to B(x-1) instead of B(X) shown in FIG. 5.

[0050] The image display unit 30 includes a liquid crystal display 120, imaging optical systems 130 and 140 (see FIGS. 3(a) and 3(b)) including a concave mirror 141, and a drive unit 110 to display the virtual image V generated by the control unit 10.

[0051] 3(a) and 3(b), the liquid crystal display 120 is mainly composed of a light source 121 made of a light emitting diode mounted on a wiring board, and a TFT (Thin Film Transistor Liquid Crystal) liquid crystal display element 122 located on the emission side (directly above) of the light source 121 so as to transmit illumination light from the light source 121 and form display light L. This means that the light source 121 is provided behind the liquid crystal display element 122, and the liquid crystal display element 122 displays a predetermined image (virtual image V) using the light emitted from the light source 121.

[0052] 3(a) and 3(b), the liquid crystal display 120 has a display surface 120a disposed obliquely with respect to the optical axis, and outputs display light L consisting of light in the visible wavelength range. For example, a light source 121 emitting white light can be used, and the light emitted from this light source 121 passes through the liquid crystal display element to output display light L containing a desired image. The liquid crystal display element forms a desired image based on display image data (drive signals) generated by drawing calculations performed by the control unit 10. The liquid crystal display element displays an image (virtual image V) generated by the control unit 10, such as numerical values ​​or icons, that displays, for example, the speed and remaining energy of the vehicle CR, time, route guidance images, etc. Note that any display format can be adopted, not limited to vehicle information such as the speed and remaining energy of the vehicle CR.

[0053] As shown in FIGS. 3(a) and 3(b), the imaging optical systems 130 and 140 are composed of multiple reflectors, including a concave mirror 141, which is an optical element (reflecting element), and project display light L generated by the liquid crystal display 120 onto a windshield WS, which is a projection target, through an opening window 152 provided at the top of the HUD device 100. Details of the imaging optical systems 130 and 140 will be described later with reference to FIGS. 3(a) and 3(b). The driving unit 110 is connected to the concave mirror 141, which is an optical element (reflecting element), and can rotate the concave mirror 141 to a predetermined angular position based on a control signal generated by the control unit 10. The rotational position of the concave mirror 141 has several steps, and can be adjusted within that range. The concave mirror 141 uses a stepping motor for rotational drive, and can rotate by a predetermined number of steps corresponding to the position (setting information) of the eyebox IB, which is set by operating the operation input device 302.

[0054] Meanwhile, turning to the peripheral configuration of the HUD device 100 of this embodiment, the DMS 301 is a system for monitoring the driving state of the driver DR using an in-vehicle camera included in the vehicle monitoring device 303, with the aim of preventing dangerous driving and accidents. Here, the DMS 301 is also used for the purpose of detecting the eye-height position of the driver DR by combining it with face authentication (image recognition). The operation input device 302 is, for example, switches provided near the steering wheel (steering handle). The operation input device 302 allows the driver DR, who is the viewer, to operate these switches to switch the HUD device 100 on / off and set the air volume of the air conditioner, and further to set setting information (the position of the eye box IB) that instructs the rotation operation of the optical member (see the concave mirror 141 shown in FIGS. 3(a) and 3(b)) by the drive unit 110 of the HUD device 100.

[0055] The vehicle monitoring device 303 is a set of sensors necessary for recognizing the surrounding driving environment including the area ahead of the vehicle CR, and includes a camera, a LiDAR (Light Detection and Ranging), etc. It also includes an IMU (Inertial Measurement Unit), a vehicle speed sensor, a seat sensor, etc. that detect the behavior of the vehicle CR. Information recognized or detected by the vehicle usage monitoring device 303 is transferred to the HUD device 100 of this embodiment via the I / O interface 200.

[0056] The camera includes an exterior camera that captures the forward field of view (foreground) of the vehicle CR, as well as an interior camera that captures the face of the driver DR and outputs the image to the DMS301 for facial recognition (here, detecting the viewpoint position at eye height of the driver). LiDAR uses near-infrared light, visible light, and ultraviolet light to, for example, illuminate an obstacle in front of the vehicle CR captured by the exterior camera, capture the reflected light with an optical sensor, and determine the distance to the obstacle based on the time difference. The IMU uses a three-axis acceleration sensor and a three-axis angular velocity sensor (gyro sensor) to measure the vehicle's driving situation and attitude (acceleration [m / s 2The seat sensor can detect the position of the seat in which the driver DR, who is the viewer, sits.

[0057] The I / O interface 200 communicates (also referred to as CAN communication) with the DMS 301, the operation input device 302, and the vehicle monitoring device 303, in addition to the display control device 300, via an ECU (not shown) provided in the vehicle CR in accordance with, for example, the CAN (Controller Area Network) standard. Note that the communication standard adopted by the I / O interface 200 is not limited to CAN, and includes, for example, wired communication interfaces such as CANFD (CAN with Flexible Data Rate), LIN (Local Interconnect Network), Ethernet (registered trademark), MOST (Media Oriented Systems Transport: MOST is a registered trademark), UART (Universal Asynchronous Receiver Transmitter), or USB (Universal Serial Bus), or an in-vehicle communication (internal communication) interface that is a short-range wireless communication interface within a distance of several tens of meters, such as a personal area network (PAN) such as a Bluetooth (registered trademark) network or a local area network (LAN) such as an 802.11x Wi-Fi (registered trademark) network.

[0058] The I / O interface 500 may also include an external communication interface such as a wide area communication network (e.g., an Internet communication network) based on cellular communication standards such as a wireless wide area network (WWAN0, IEEE802.16-2004 (WiMAX: Worldwide Interoperability for Microwave Access)), IEEE802.16e-based (Mobile WiMAX), 4G, 4G-LTE, LTE Advanced, and 5G.

[0059] Fig. 3 shows the cross-sectional structure of the HUD device 100 of this embodiment. Fig. 3(a) shows the state of rotation of the optical member (concave mirror 141) when the eyebox IB is at the reference position, and Fig. 3(b) shows the state of rotation of the optical member (concave mirror 141) when the position of the eyebox IB is changed.

[0060] 3(a) and 3(b), the HUD device 100 is mainly composed of a liquid crystal display 120, a first reflector 130 and a second reflector 140 which are imaging optical systems, and a housing 150. As described above, the liquid crystal display 120 has a virtual image display surface 120a and outputs display light L consisting of light in the visible wavelength range. For example, a light source 121 that emits white light can be applied, and the light emitted from this light source 121 is transmitted through the liquid crystal display element to output display light L containing a desired image.

[0061] The first reflector 130 includes a cold mirror 131. The cold mirror 131 reflects light in the visible wavelength range (450 to 750 nm), which includes the emission wavelength range of the liquid crystal display 120, with a high reflectance of, for example, 80% or more, and reflects light outside the visible wavelength range with a low reflectance. In this case, the cold mirror 131 is configured to reflect light outside the visible wavelength range, particularly light in the infrared wavelength range (heat rays from external light such as sunlight), with a low reflectance of, for example, 15% or less. Light that is not reflected by the reflective layer of the cold mirror 131 is configured to pass through the cold mirror 131. The cold mirror 131 can prevent the liquid crystal display element 122 from becoming too hot due to heating by sunlight or the like.

[0062] The second reflector 140 includes a concave mirror 141 that reflects the display light L from the cold mirror 131 (that is, the liquid crystal display element 122), and a mirror holder 142 that holds the concave mirror 141.

[0063] The concave mirror 141 has a second reflective layer 141a formed by vapor deposition on a resin substrate made of polycarbonate having a concave surface. The concave mirror 141 is provided at an angle such that the second reflective layer 141a faces the cold mirror 131 and the light-transmitting cover 153 and can be seen from the light-transmitting cover 153.

[0064] The concave mirror 141 magnifies the display light L from the cold mirror 131 and reflects (projects) it toward the light-transmitting cover 153 (the windshield WS of the vehicle CR). This means that the concave mirror 141 magnifies the display light L reflected by the cold mirror 131 and projects the magnified display light L onto the windshield WS through the light-transmitting cover 153. The concave mirror 141 is adhered to a mirror holder 142 with a double-sided adhesive member. The mirror holder 142 is made of a synthetic resin such as ABS (Acrylonitrile Butadiene Styrene) and is fixed to the housing 150.

[0065] The concave mirror 141 is connected to the drive unit 110 and can be rotated within a predetermined angle range depending on the situation. This allows the point at which the display light L reaches inside the windshield WS to be changed. In other words, the position of the eye box IB of the HUD device 100 changes. This allows the driver DR, who is the viewer, to change the viewpoint position in the height direction so that the image can be viewed, and the display position within the display area VA where the image is displayed to be changed.

[0066] Here, the lower the position of the eyebox IB, the higher the display position of the image (virtual image V) within the display area VA. This means that the depression angle LD, which is the angle between two lines: a line VL parallel to the road surface based on the viewpoint position in the height direction of the viewer DR, and a line connecting the viewpoint position in the height direction of the eyes of the viewer, the driver DR, and the image (virtual image V), changes in the direction of decreasing. On the other hand, the higher the position of the eyebox IB, the lower the display position of the image within the display area VA. This means that the depression angle LD (see Figure 1), which is the angle between two lines: a line parallel to the road surface based on the viewpoint position in the height direction of the viewer, the driver DR, and a line connecting the eyes of the driver DR and the image (virtual image V), changes in the direction of increasing.

[0067] In other words, when concave mirror 141, which is in the reference position shown in Fig. 3(a), rotates clockwise, the position of eyebox IB rises as shown in Fig. 3(b), and conversely, when it rotates counterclockwise, the position of eyebox IB falls. Note that because depression angle LD is uniquely determined by a predetermined formula depending on the position of eyebox IB, calculating the display position of an image at the position of eyebox IB is equivalent to calculating the display position of the image in the display area VA using depression angle LD.

[0068] The housing 150 is made of, for example, a black light-blocking synthetic resin material, is formed in a substantially box-like shape, and holds and houses the projection unit consisting of the liquid crystal display 120, the first reflector 130, and the second reflector 140 in a space portion 151, which is its internal space. The housing 150 is provided with an opening window portion 152 where the upper part (on the windshield WS side) of the concave mirror 141 of the second reflector 140 opens. The housing 150 is also provided with a light-transmitting cover 153, which serves as an emission unit, so as to cover the opening window portion 152. The light-transmitting cover 153 is made of a light-transmitting synthetic resin material (for example, acrylic resin), is formed in a curved shape (curved surface shape), and functions as a light-transmitting member through which the display light L reflected by the concave mirror 141 passes (passes through). In other words, the display light L reflected by the cold mirror 131 and the concave mirror 141, i.e., the display light L output by the projection unit, is projected onto the windshield WS, which is the projection target, through the translucent cover 153 formed on the housing 150, thereby displaying the virtual image V.

[0069] The HUD device 100 of this embodiment projects and outputs an image (virtual image V) displayed on the display surface 120a of the liquid crystal display 120 of the image display unit 30 onto the lower side of the windshield WS, which is the projection target. Therefore, from the driver DR side, who is the viewer, the virtual image V can be observed from the lower area of ​​the windshield WS, superimposed on the foreground FV, which is the scenery ahead of the vehicle. Therefore, the driver DR, who is the viewer, sees the virtual image V as being displayed mainly on the road surface near the vehicle CR. Furthermore, due to the configuration of the projection unit of the HUD device 100 of this embodiment, the virtual image V is outputted so that the upper part of the output image appears to be tilted so that it is farther from the vehicle CR than the lower part.

[0070] (Operation of the embodiment) 4 is a flowchart showing the operation of the head-up display device according to the embodiment of the present invention. 6 to 8 are diagrams (parts 1 to 3) cited to explain the relationship between the display position of the foreground FV where the virtual image is superimposed and displayed for each eyebox, and the relationship with the display brightness value set in the eyebox-specific dimming table. Also, Figs. 9 and 10 are diagrams (parts 1 and 2) cited to explain the range over which the virtual image can be moved as a result of depression angle adjustment by the driver DR who is the viewer, and the display brightness after adjustment.

[0071] Hereinafter, the operation of the HUD device 100 of this embodiment shown in FIGS. 1 to 3 will be described in detail with reference to FIGS.

[0072] 4. In the HUD device 100 of this embodiment, the control unit 10 first detects the viewpoint position (eye box IB) in the eye height direction of the driver DR who is the viewer (step ST101). The viewpoint position in the eye height direction of the driver DR can be detected, for example, by the DMS 301 or by performing image recognition on a facial image of the driver DR who is the viewer, captured by an in-vehicle camera provided in the vehicle monitoring device 303.

[0073] Next, the control unit 10 performs an estimation calculation of the depression angle LD (step ST102). Since the depression angle LD is uniquely determined by a predetermined calculation formula depending on the position of the eyebox IB, calculating the display position of the virtual image V at the position of the eyebox IB is equivalent to calculating the display position of the virtual image V in the display area VA using the depression angle LD.

[0074] As described above, the lower the position of the eyebox IB, the higher the display position of the virtual image V within the display area VA, which means that the depression angle LD, which is the angle between two lines: a line VL parallel to the road surface based on the viewpoint position in the height direction of the driver DR who is the viewer, and a line connecting the viewpoint position in the height direction of the eyes of the driver DR who is the viewer and the image (virtual image V), changes in the direction of decreasing.On the other hand, the higher the position of the eyebox IB, the lower the display position of the image within the display area VA, which means that the depression angle LD, which is the angle between two lines: a line parallel to the road surface based on the viewpoint position in the height direction of the driver DR who is the viewer, and a line connecting the eyes of the driver DR who is the viewer and the image (virtual image V), changes in the direction of increasing.

[0075] Next, the control unit 10 determines whether the depression angle LD obtained as a result of the estimation calculation is lower than a reference value (standard value) of the depression angle LD (step ST103). Here, the reference value (standard value) is the depression angle LD corresponding to the case where the viewer, the driver DR, is of average height, and is stored in advance in a designated area of ​​the storage unit 20. Here, if it is determined that the depression angle LD obtained by the estimation calculation is equal to or lower than the reference value (standard value) (step ST103 "YES"), the control unit 10 executes control to gradually or stepwise update the display brightness setting set in the light adjustment table 20a stored in a predetermined area of ​​the storage unit 20 to a lower value (step ST104). If it is determined that the depression angle LD is equal to or higher than the reference value (standard value) (step ST103 "NO"), the control unit 10 executes control to set the display brightness value set in the light adjustment table 20a to a default value (B(x) in the light adjustment table 20a in FIGS. 5(A) and 5(B)) (step ST105). The default values ​​are assumed to be stored in a predetermined area of ​​the storage unit 20 in advance.

[0076] Next, the control unit 10 determines whether the eyebox IB has changed due to the depression angle adjustment by the driver DR, who is the viewer (step ST106). As described above, the driver DR, who is the viewer, can adjust the depression angle LD by operating the operation input device 302 to rotate the optical member (concave mirror 141) in the reference position clockwise or counterclockwise. Here, when the optical member (concave mirror 141) is rotated clockwise, for example, the position of the eyebox IB becomes higher as shown in FIG. 3(b), and when it is rotated counterclockwise, the position of the eyebox IB becomes lower.

[0077] If the eyebox IB is changed by the depression angle adjustment of the driver DR, who is the viewer (step ST106 “YES”), the driver DR can select whether the control unit 10 executes control not to change the dimming table 20a by adjusting the depression angle after the display brightness setting value has been determined, or whether the control unit 10 executes control to change the display brightness setting value of the dimming table 20a according to the changed depression angle LD. This selection (step ST107: whether the change is valid or not) can also be set by, for example, the driver DR, who is the viewer, operating the operation input device 302 to enable or disable the depression angle adjustment. For example, if the former is selected, the display brightness does not change even if the display position of the virtual image V is changed by adjusting the depression angle, so the virtual image V can be moved to a desired display position while maintaining the display brightness. On the other hand, if the latter is selected, the brightness can be changed when the display position of the virtual image V is changed by adjusting the depression angle, and by performing control to reduce the brightness at this time, the annoyance felt by a viewer who is short in stature.

[0078] 9 and 10 show diagrams (1) and (2) cited to explain the range in which virtual image V can be moved as a result of depression angle adjustment by driver DR, who is the viewer, and the display brightness after adjustment. FIG. 9 shows the case in which depression angle adjustment is disabled, and FIG. 10 shows the case in which depression angle adjustment is enabled. In (1) of FIG. 9, the range in which the display position can be moved by depression angle adjustment is indicated by X, and the display brightness set in each range X is "3." After depression angle LD is determined, even if driver DR operates operation input device 302 to adjust the depression angle and change the display position of virtual image V, the setting values ​​Y1, Y2, and Y3 of the display brightness after adjustment within movement range X remain unchanged from "3," so the virtual image can be moved to a desired position while maintaining that brightness.

[0079] 10 (part 2), the range in which the display position can be moved as a result of depression angle adjustment by the driver DR, who is the viewer, is indicated by X, and the display brightness set on the light control table 20a within that range X is "2," "3," and "4" in ascending order of depression angle LD (in ascending order of the display position of the virtual image V). After the depression angle LD is determined, when the driver DR adjusts the depression angle by operating the operation input device 302, the display brightness set on the light control table 20a is gradually reduced as the depression angle LD becomes smaller. In this way, by lowering the display brightness set as the virtual image V moves and its display position becomes higher due to depression angle adjustment, it is possible to reduce the annoyance felt by the driver DR, who is a viewer who is short in stature.

[0080] 4 for the explanation. If it is determined in step ST107 that the change in the eye box IB due to the depression angle adjustment by the driver DR, who is the viewer, is valid (step ST107 "YES"), the process returns to the estimation calculation process of the depression angle LD in step ST102, and the update of the display brightness setting in the dimming table 20a (step ST103) or the setting process of the default value (step ST104) is repeatedly executed. On the other hand, if the depression angle adjustment by the driver DR, who is the viewer, has not been performed in step ST106 (step ST106 "NO"), or if it is determined in step ST107 that the change in the eye box IB due to the depression angle adjustment is invalid (step ST107 "NO"), the control unit 10 generates a virtual image V and determines its display position (step ST108), and performs control to superimpose the generated virtual image V on the foreground FV and display it on the image display unit 30 (liquid crystal display 120) (step ST109).

[0081] FIG. 6 shows a diagram (part 1) cited to explain the relationship between the display position of the foreground FV on which the virtual image V is superimposed for each eyebox and the relationship to the display brightness value set in the eyebox-specific dimming table 20a. Here, the eyeboxes of a short person ("shorter"), a person ("nominal") with a standard height, and a tall person ("taller") are illustrated as viewpoint positions. The diagram shows that the lower the position of the eyebox IB, which is determined based on height, the higher the display position of the foreground FV within the display area VA of the image (virtual image V). The higher the position of the eyebox IB, the lower the display position of the foreground FV within the display area VA of the image (virtual image V). Here, the display brightness is set to "2" for the "shorter" person, and to "3" for the "nominal" and "taller" people.

[0082] That is, for a "shorter" who is short, a lower display brightness of "2" is set compared to the others. In this way, in the HUD device 100 of this embodiment, by setting the display brightness to be lower for the driver DR who is a viewer who is short, the virtual image V becomes less noticeable, and therefore it is possible to reduce the annoyance felt by the driver DR who is a viewer when gazing at the foreground FV due to the virtual image V getting in the way.

[0083] Fig. 7 shows a diagram (part 2) cited to explain the relationship between the display position of the foreground FV on which a virtual image is superimposed and displayed for each eyebox, and the relationship with the display brightness value set in the per-eyebox dimming table. According to Fig. 7, as shown in the block surrounded by the dashed line, the display brightness setting value is "1" for "shorter1," a viewer who is a short viewer and has a small depression angle LD, the display brightness setting value is "2" for "shorter2," a viewer who is a short viewer and has a large depression angle LD, and the display brightness setting value is "3" for "nominal," a viewer of average height other than "shorter," and "taller," a tall viewer.

[0084] That is, "shorter1" has the lowest display brightness value, and "shorter2" has the second lowest display brightness value. Furthermore, for "nominal" and "taller," the display brightness value is set higher than for "shorter," but remains constant regardless of the depression angle LD (the display brightness value is set to "3" in both cases). In this way, when a shorter viewer is trying to check the forward field of view (foreground FV) while driving, the display brightness setting tends to be lower and less noticeable even if a virtual image is superimposed, which reduces the annoyance it may cause.

[0085] 8 shows a diagram (part 2) cited for explaining the relationship between the display position of the foreground FV on which the virtual image V is superimposed and displayed for each eyebox, and the relationship with the display brightness value set in the eyebox-specific dimming table 20a. The control unit 10 controls the display brightness to be gradually reduced if the depression angle LD is smaller by a predetermined difference, controls the display brightness to be gradually reduced if the display brightness is smaller by the first difference in a first region (e.g., "taller" to "nominal"), and controls the display brightness to be gradually reduced if the display brightness is smaller by a second difference that is smaller than the first difference in a second region (e.g., "shorter2" to "shorter1") that is lower than the first region. Here, the first difference for "taller" to "nominal" to "shorter2" is approximately the same, and the second difference is approximately 60% of the first difference. For short viewers, slight differences in height can greatly affect the degree to which the virtual image V superimposed on the field of view ahead of the vehicle is perceived as a nuisance. Therefore, even for short viewers other than "shorter1" and "shorter2" ("taller" - "nominal"), the smaller the depression angle LD becomes depending on the height, the more the display brightness set in the dimming table 20a is controlled to gradually decrease. This makes it possible to provide an optimal viewing environment for short viewers with a finer display brightness that reflects differences in height, while also reducing annoyance.

[0086] (Effects of the embodiment) As described above, the head-up display device of this embodiment is a HUD device 100 that, for example, as shown in Fig. 1, forms an image by superimposing a foreground FV, which is a landscape in the field of view ahead of the vehicle CR, and a generated virtual image V on an imaging plane (display area VA) that is virtually set in front of the vehicle CR, and projects the image onto a windshield WS, which is a projection target, so that the image is visually recognized by a driver DR who is a viewer. The HUD device 100 includes, for example, an image display unit 30 that displays the virtual image V, and a control unit 10 that controls the image display unit 30 to lower the display brightness of the virtual image V when a depression angle LD, which is the angle formed by a virtual line VL (see Fig. 1) parallel to the road surface from a viewpoint position at eye height of the driver DR who is a viewer, and a straight line (shown as a wavy line in Fig. 1) connecting the viewpoint position of the viewer and the center of the virtual image V, is smaller than a standard value.

[0087] In the HUD device 100 of this embodiment, the control unit 10 controls the display brightness of the virtual image V to be lowered when the depression angle LD, which is the angle between a virtual line VL parallel to the road surface from the viewpoint position at eye height of the viewer and a straight line connecting the viewpoint position and the center of the virtual image, is smaller than a standard value, in other words, when the viewer is short.As a result, when the viewer, the driver, tries to check the forward field of view, the virtual image displayed superimposed on the forward field of view becomes less noticeable, thereby reducing the annoyance felt by the viewer due to the virtual image V getting in the way.

[0088] Furthermore, in the HUD device 100 of this embodiment, the control unit 10 performs control such that the display brightness setting set on the dimming table 20a gradually decreases as the depression angle LD becomes smaller. This reduces the annoyance felt by shorter viewers when they try to check the forward field of view (foreground FV) for driving, since even if the virtual image V overlaps, the display brightness value tends to be low and inconspicuous.

[0089] Furthermore, in the HUD device 100 of this embodiment, the control unit 10 controls the display luminance setting value to be constant regardless of the depression angle LD if the depression angle LD is equal to or greater than the standard value. Therefore, when a viewer of shorter stature attempts to check the forward field of view (foreground FV) while driving, the display luminance value tends to be low and inconspicuous even when a virtual image is superimposed, which can reduce the annoyance felt by the viewer.

[0090] Furthermore, in the HUD device 100 of this embodiment, the control unit 10 performs control to gradually decrease the display brightness when the depression angle LD is smaller than the standard value by a predetermined difference, performs control to gradually decrease the display brightness value when the depression angle LD is smaller by the first difference in a first region, and further performs control to gradually decrease the display brightness when the depression angle is smaller by a second difference that is smaller than the first difference in a second region lower than the first region. In this way, by performing control to gradually decrease the display brightness value as the depression angle decreases depending on the height, it is possible to provide an optimal viewing environment for a short viewer with a finer display brightness that reflects differences in height and reduce annoyance.

[0091] Furthermore, in the HUD device 100 of this embodiment, after the control unit 10 determines the setting value of the display brightness for the dimming table 20a, it controls the dimming table 20a so that it does not change even if the depression angle changes due to depression angle adjustment by the viewer.As a result, even if the display position of the virtual image V is changed due to depression angle adjustment, the display brightness does not change, so the virtual image can be moved to a desired display position while maintaining the display brightness.

[0092] Furthermore, in the HUD device 100 of this embodiment, after the setting value of the display brightness on the dimming table 20a has been determined, if the viewer adjusts the depression angle LD to change the depression angle, the control unit 10 performs control to change the setting value of the display brightness on the dimming table 20a in accordance with the changed depression angle LD. This allows the brightness to be changed when the display position of the virtual image V is changed by adjusting the depression angle, and by performing control to reduce the brightness at this time, the annoyance felt by shorter viewers can be reduced.

[0093] Furthermore, in the HUD device 100 of this embodiment, the control unit 10 operates an operation member (operation input device 302) to rotate an optical member such as the concave mirror 141, thereby allowing the viewer to adjust the depression angle, thereby facilitating and speeding up the identification of the height position of the viewer's eyes (estimating the position of the eyebox IB). Note that position information of the optical member obtained by adjusting the depression angle (such as the rotation angle of the concave mirror 141) can be used as objective data for estimating the height position of the viewer's viewpoint.

[0094] Furthermore, in the HUD device 100 of this embodiment, the control unit 10 performs image recognition based on an image of the viewer's eyes obtained by photographing the viewer, with respect to the viewpoint position in the eye height direction, or detects the set position of the seat in which the viewer is seated (detected by a seat sensor provided in the vehicle monitoring device 303), thereby estimating the forward depression angle LD and making it possible to determine the viewer's height with high accuracy.

[0095] The control method for a head-up display device of this embodiment is a control method for a head-up display device (HUD device 100) having a control unit 10 and an image display unit 30 as shown in Fig. 2, for example, in which a foreground FV, which is a view in the field of view ahead of the vehicle CR, and a generated virtual image V are superimposed on an imaging plane (display area VA) virtually set in front of the vehicle CR, and the superimposed view is projected onto a windshield WS, which is a projection target, so that the viewer can view the superimposed view. The control method includes a first step (steps ST101 to ST103) in which the control unit 10 compares a depression angle LD, which is an angle formed by a virtual line VL parallel to the road surface from the viewer's viewpoint in the height direction and a line connecting the viewer's viewpoint and the center of the virtual image V, with a standard value, as shown in Fig. 4, for example, and a second step (steps ST104 to ST109) in which the control unit 10 controls the image display unit 30 to display the virtual image V at a lower display brightness if the depression angle LD is smaller than the standard value.

[0096] According to the control method for the head-up display device of this embodiment, when the depression angle LD, which is the angle between the virtual line VL parallel to the road surface from the viewpoint position at eye height of the viewer and the straight line connecting the viewpoint position and the center of the virtual image V, is smaller than a standard value, in other words, when the viewer is short, control is performed to lower the display brightness of the virtual image V, so that when the viewer, the driver, tries to check the forward field of view, the virtual image V that is displayed superimposed on the forward field of view becomes less noticeable, thereby providing a control method for the HUD device 100 that can reduce the annoyance felt by the viewer due to the virtual image V getting in the way.

[0097] The display control program for the head-up display device of this embodiment is, for example, a display control program for a HUD device 100 having a control unit 10 and an image display unit 30 shown in Fig. 2, which superimposes a foreground view FV, which is a view in the field of view ahead of the vehicle CR, and a generated virtual image V on an imaging plane (display area VA) virtually set in front of the vehicle CR as shown in Fig. 1, and projects the superimposed image onto a windshield WS, which is a projection target, for viewing by a viewer. The program then causes a processor included in the control unit 10 to execute, for example, a first process (steps ST101 to ST103) of comparing a depression angle LD, which is an angle formed by a virtual line VL parallel to the road surface from the viewer's viewpoint in the height direction and a line connecting the viewpoint and the center of the virtual image V, with a standard value, as shown in Fig. 4, and a second process (steps ST104 to ST109) of controlling the image display unit 30 to display the virtual image V at a lower display brightness if the depression angle LD is smaller than the standard value.

[0098] According to the display control program of the head-up display device of this embodiment, the processor of the control unit 10 of the HUD device 100 sequentially reads and executes the display control program recorded in an internal or external memory, and when the depression angle LD, which is the angle between a virtual line VL parallel to the road surface from the viewpoint position at eye height of the viewer and a straight line connecting the viewpoint position and the center of the virtual image, is smaller than a standard value, in other words, when the viewer is short, control is performed to lower the display brightness of the virtual image V. This makes the virtual image V superimposed on the forward field of view less noticeable when the viewer, the driver, tries to check the forward field of view, and therefore reduces the annoyance felt by the viewer due to the virtual image getting in the way.

[0099] The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent that they fall within the scope of the claims. [Explanation of symbols]

[0100] 10···Control unit, 20···Memory unit, 20a···Light control table, 30···Image display unit, 100···Head-up display device (HUD device), 110···Drive unit, 120···Liquid crystal display, 130, 140···Imaging optical system (130: first reflector, second reflector), 141···Concave mirror, 200···I / O interface, 301···DMS, 302···Operation input device, 303···Vehicle monitoring device, 1000···Vehicle display system, IB···Eye box, VL···Virtual line, LD···Depression angle, IP···Instrument panel, DR···Viewer (driver), CR···Vehicle, WS···Windshield, VA···Display area (virtual image formation surface), L···Display light, V···Virtual image

Claims

1. A head-up display device that forms an image on an imaging plane that is virtually set in front of a vehicle, superimposing a foreground scene that is a view in the field of view ahead of the vehicle and a generated virtual image, and projects the image onto a projection target member to be viewed by a viewer, an image display unit that displays the virtual image; a control unit that controls the image display unit to display the virtual image at a lower brightness when a depression angle, which is an angle between a virtual line parallel to a road surface from a viewpoint position at eye height of the viewer and a straight line connecting the viewpoint position and the center of the virtual image, is smaller than a standard value; and A head-up display device having:

2. The control unit 2. The head-up display device according to claim 1, further comprising a light adjustment table in which the display brightness is set, and performing control such that the display brightness set in the light adjustment table is gradually reduced as the depression angle becomes smaller.

3. The control unit 2. The head-up display device according to claim 1, further comprising a dimming table in which the display brightness is set, and wherein when the depression angle is equal to or greater than the standard value, the display brightness is controlled to be set to a constant value regardless of the depression angle.

4. The control unit When the depression angle is smaller than the standard value by a predetermined difference, the display brightness is gradually reduced.

2. The head-up display device according to claim 1, wherein when the depression angle is smaller by a first difference in a first region, the display brightness is controlled to be gradually reduced, and further when the depression angle is smaller by a second difference that is smaller than the first difference in a second region lower than the first region, the display brightness is controlled to be gradually reduced.

5. The control unit 3. The head-up display device according to claim 2, wherein after the setting value of the display brightness in the light adjustment table is determined, control is performed so that the light adjustment table is not changed even if the depression angle is changed by the viewer adjusting the depression angle.

6. The control unit 3. The head-up display device according to claim 2, wherein, after the setting value of the display brightness in the light adjustment table is determined, if the depression angle is changed by the viewer adjusting the depression angle, control is performed to change the setting value of the display brightness in the light adjustment table in accordance with the changed depression angle.

7. An operating member; an imaging optical system including an optical member that projects the virtual image onto the imaging surface; The control unit 7. The head-up display device according to claim 5, wherein the viewer adjusts the depression angle by operating the operating member to rotate the optical member.

8. The control unit 2. The head-up display device according to claim 1, wherein the depression angle is estimated by performing image recognition based on an image of the viewer's eyes obtained by photographing the viewer, or by detecting a set position of a seat in which the viewer is seated, with respect to the viewpoint position in the eye height direction of the viewer.

9. A control method for a head-up display device having a control unit and an image display unit, which superimposes a foreground scene, which is a view in the field of view ahead of the vehicle, and a generated virtual image on an imaging plane that is virtually set in front of the vehicle, and projects the superimposed image onto a projection target member so that the image is visually recognized by a viewer, The control unit a first step of comparing a depression angle, which is an angle formed by a virtual line parallel to a road surface from a viewpoint position of the viewer's eyes in a height direction and a straight line connecting the viewpoint position and the center of the virtual image, with a standard value; a second step of controlling the image display unit to display the virtual image at a lower luminance when the depression angle is smaller than the standard value; A control method for a head-up display device having the following.

10. A display control program for a head-up display device having a control unit and an image display unit, which forms an image on an imaging plane virtually set in front of the vehicle, in such a way that a foreground, which is a view in the field of view ahead of the vehicle, and a generated virtual image are superimposed on the image, and projects the image onto a projection target member so that the image is visually recognized by a viewer, A processor included in the control unit a first process of comparing a depression angle, which is an angle formed by a virtual line parallel to a road surface from a viewpoint position at eye height of the viewer and a straight line connecting the viewpoint position and the center of the virtual image, with a standard value; a second process of controlling the virtual image to be displayed on the image display unit by lowering the display luminance of the virtual image when the depression angle is smaller than the standard value; A display control program for an up-display device that executes the above.

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