Virtual image display device

Abstract

To provide a virtual image display device capable of suppressing an influence on a user due to the occurrence of abnormalities even with the configuration capable of displacing the display area of virtual image.SOLUTION: An HUD 100 is a virtual image display device used on a vehicle Am and displays a virtual image Vi superimposed on a foreground. The HUD 100 includes: a displacement mechanism 63 that changes the position of a display area VA on which the virtual image Vi is displayed along the vertical direction US of the vehicle Am; and a head-up ECU 70 that controls the position of the display area VA depending on the content displayed as the virtual image Vi. The head-up ECU 70 detects at least a fixation of the display area VA as an abnormality of the displacement of the display area VA. The head-up ECU 70 is configured so as to, when fixation of the display area VA is detected, perform fail-safe control according to the fixed position of the display area VA.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The disclosure in this specification relates to a virtual image display device that displays a virtual image. [Background technology]

[0002] Patent Document 1 discloses a head-up display device that reflects an image displayed on an image display device using a mirror and projects the image onto the windshield of the vehicle, allowing the driver to view the projected image. If an abnormality occurs in the head-up display device, the display of the virtual image is controlled so as not to interfere with driving. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 6953539 Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, virtual image display devices have been conceived that vertically displace the position of a display area where a virtual image is displayed according to the content displayed as the virtual image. In such virtual image display devices, an abnormality may occur in the displacement mechanism that displaces the display area. However, Patent Document 1 does not disclose any control method in the event of an abnormality in the displacement mechanism. As a result, there is a risk that the occurrence of an abnormality may have an excessive impact on the user.

[0005] The present disclosure aims to provide a virtual image display device that can suppress the impact on a user caused by the occurrence of an abnormality, even when the display area of ​​the virtual image is configured to be displaceable. [Means for solving the problem]

[0006] In order to achieve the above object, one disclosed embodiment is used in a vehicle (Am), By projecting the display light (Lvi) formed as a virtual image (Vi) onto the projection range (PA) of the vehicle's windshield (WS), the image can be seen through the projection range. Imaginary images superimposed on the foreground statue The virtual image display device includes a displacement mechanism (63) that displaces the position of a display area (VA) where a virtual image is displayed along the vertical direction (US) of the vehicle, a display control unit (72) that controls the position of the display area according to the content (CT) that is displayed as a virtual image, and an abnormality detection unit (73) that detects at least fixation of the display area as an abnormality in the displacement of the display area, wherein the displacement mechanism switches the position of the display area between a plurality of positions that include at least a first position (VP1) and a second position (VP2) that is higher than the first position, and the display control unit, when the abnormality detection unit detects that the display area is fixed, performs fail-safe control according to the fixed position of the display area, and when the display area is fixed at the second position, starts an abnormality response by the fail-safe control earlier than when the display area is fixed at the first position. 。

[0007] this In one aspect, when fixation of the display area is detected as an abnormality in the displacement of the display area, fail-safe control is performed according to the position where the display area is fixed. Therefore, even if the virtual image display device is configured to be able to displace the display area of ​​the virtual image, it is possible to suppress the impact on the user due to the occurrence of an abnormality. Another disclosed aspect is a virtual image display device used in a vehicle (Am), which projects display light (Lvi) formed as a virtual image (Vi) toward a projection range (PA) of a windshield (WS) of the vehicle, thereby displaying a virtual image superimposed on a foreground seen through the projection range, and which includes a displacement mechanism (63) that displaces the position of a display area (VA) where the virtual image is displayed along the vertical direction (US) of the vehicle, a display control unit (72) that controls the position of the display area according to the content (CT) displayed as a virtual image, and an abnormality detection unit (73) that detects at least an abnormality in the display area continuing to shake in the vertical direction as an abnormality in the displacement of the display area, and when the abnormality detection unit detects continued shaking of the display area, the display control unit determines whether or not content that is predefined as interfering with the driver's field of view is being displayed, and if content that is predefined as interfering with the field of view is being displayed, stops displaying the virtual image, and if content that is predefined as interfering with the field of view is not being displayed, performs a reset process for the displacement mechanism. Even in this aspect, the virtual image display device can suppress the influence on the user caused by the occurrence of an abnormality, even if the virtual image display device is configured to be able to change the display area of ​​the virtual image.

[0008] It should be noted that the reference numbers in parentheses above and in the claims merely indicate an example of the correspondence with the specific configurations in the embodiments described below, and do not limit the technical scope in any way. Furthermore, claims not explicitly stated in the claims may be combined together if no particular problems arise in the combination. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram for explaining a virtual image display function of a head-up display according to an embodiment of the present disclosure. [Figure 2] FIG. 2 is a block diagram showing the electrical configuration of the display system. [Figure 3]FIG. 10 is a diagram showing the positional relationship between the normal position and the upper position of the display area. [Figure 4] 10A and 10B are diagrams illustrating an example of content that is displayed as a virtual image at a normal position and an upper position. [Figure 5] 10 is a flowchart showing details of a fail-safe transition process performed by a head-up ECU. [Figure 6] FIG. 10 is a diagram for explaining details of fail-safe control in abnormality type 1. [Figure 7] 10 is a timing chart showing an example of a predetermined timing. [Figure 8] FIG. 10 is a diagram for explaining details of fail-safe control in abnormality type 2. [Figure 9] FIG. 10 is a diagram for explaining details of fail-safe control in abnormality type 3. [Figure 10] FIG. 10 is a diagram for explaining details of fail-safe control in abnormality type 4. [Figure 11] FIG. 10 is a diagram for explaining details of fail-safe control in abnormality type 5. [Figure 12] FIG. 10 is a diagram for explaining details of fail-safe control in abnormality type 6. DETAILED DESCRIPTION OF THE INVENTION

[0010] 1 and 2, a head-up display (hereinafter, referred to as HUD) 100 according to an embodiment of the present disclosure is a virtual image display device that displays a virtual image Vi. The HUD 100 constitutes a display system 110 together with a meter display device 30 and the like. The display system 110 is used in a vehicle Am, and presents various information related to the vehicle Am to the driver by linking the virtual image display by the HUD 100 with the screen display by the meter display device 30 and the like.

[0011] The meter display device 30 and the HUD 100 are communicatively connected to a communication bus of an in-vehicle network mounted on the vehicle Am. Other in-vehicle ECUs, such as a navigation ECU (Electronic Control Unit) 21 and a driving assistance ECU 22, are further connected to the communication bus of the in-vehicle network. These components connected as nodes to the communication bus can communicate with each other. Specific nodes among these ECUs may be directly electrically connected to each other and can communicate without going through the communication bus.

[0012] The meter display device 30 is one of a plurality of display devices mounted on the vehicle Am, and presents information to the driver by displaying images on a display screen. The meter display device 30 has a configuration equivalent to a combination meter, and is housed in the instrument panel 9 with the display screen facing the driver's seat. The meter display device 30 includes a meter display 31 and a meter ECU 32.

[0013] The meter display 31 is, for example, a liquid crystal display or an organic EL display, etc. Based on video data acquired from the meter ECU 32, the meter display 31 displays a speedometer image, a tachometer image, a navigation map image, a driving assistance image, etc. on a display screen.

[0014] The meter ECU 32 is an electronic control device that manages the user interface functions of the vehicle Am. The meter ECU 32 comprehensively controls the displays of display devices such as the meter display 31, the HUD 100, and the center display. The meter ECU 32 mainly includes a computer equipped with a processing unit, RAM, storage, an input / output interface, and buses connecting these. The meter ECU 32 generates video data to be provided to the meter display 31 based on various information output to the communication bus. The meter ECU 32 cooperates with the head-up ECU 70 (described later) to perform arithmetic processing for virtual image display. The meter ECU 32 generates image data used to display the virtual image Vi and sequentially outputs the generated image data to the HUD 100.

[0015] The HUD 100 is one of multiple display devices mounted on the vehicle Am, and presents information to the driver by a virtual image Vi formed in the space in front of the driver. The HUD 100 is housed in a housing space provided inside the instrument panel 9. The HUD 100 projects light formed as the virtual image Vi (hereinafter referred to as display light Lvi) toward a projection range PA of the windshield WS. The display light Lvi projected onto the windshield WS is reflected toward the driver's seat in the projection range PA and perceived by the driver. The driver visually recognizes a display in which the virtual image Vi is superimposed on the foreground visible through the projection range PA.

[0016] The HUD 100 includes a PGU (Picture Generation Unit) 61, a magnifying optical system 62, a displacement mechanism 63, a position sensor 64, and a head-up ECU .

[0017] The PGU 61 has an LCD (Liquid Crystal Display) panel and a backlight. The PGU 61 is fixed to the housing of the HUD 100 with the display surface of the LCD panel facing the magnifying optical system 62 (a plane mirror, described later). The PGU 61 displays each frame image of the video data on the display surface of the LCD panel, transmits illumination onto the display surface with a backlight, and emits display light Lvi, which is focused as a virtual image Vi, toward the magnifying optical system 62.

[0018] The magnifying optical system 62 includes at least a plane mirror and a concave mirror 62a, which are made of a base material made of synthetic resin, glass, or the like and on which a metal such as aluminum is vapor-deposited. The plane mirror reflects the display light Lvi emitted from the PGU 61 toward the concave mirror 62a. The concave mirror 62a reflects and expands the display light Lvi incident from the plane mirror, and projects it into the projection range PA above.

[0019] The displacement mechanism 63 mechanically moves the area of ​​the windshield WS that becomes the projection range PA. The projection range PA is the range onto which the display light Lvi is projected and the range onto which the virtual image Vi appears as seen by the driver. The displacement mechanism 63 is composed of an actuator 63a, a gear unit, and the like. The displacement mechanism 63 rotates the concave mirror 62a around a rotation axis defined in the left-right direction Yo by transmitting the driving force of the actuator 63a to the housing of the concave mirror 62a via the gear unit. The displacement mechanism 63 increases or decreases the tilt angle of the concave mirror 62a, thereby changing the emission direction of the display light Lvi from the concave mirror 62a toward the windshield WS. This change in the attitude of the concave mirror 62a moves the projection range PA of the display light Lvi, and therefore the position of the display area VA viewed by the driver, at least in the up-down direction US.

[0020] More specifically, when the imaginary range in space where the virtual image Vi can be formed is defined as an imaging plane IS, the display area VA is determined based on a virtual line connecting the driver's eye point EP and the outer edge of the imaging plane IS. The display area VA is the range of the angle of view within which the virtual image Vi is displayed as viewed from the eye point EP. In HUD 100, the horizontal angle of view (e.g., approximately 6°) is larger than the vertical angle of view (e.g., approximately 2°).

[0021] The displacement mechanism 63 displaces the position of the display area VA in the up-down direction US of the vehicle Am, and moves the forward range that overlaps with the display area VA in the fore-and-aft direction ZG. As an example, when the displacement mechanism 63 positions the display area VA downward (for example, at a depression angle of about 4°), the range in the forward direction is about 10 to 20 meters. On the other hand, when the displacement mechanism 63 positions the display area VA upward (for example, at a depression angle of about 2°), the range in the forward direction is about 20 to 60 meters.

[0022] Here, the longitudinal direction ZG and the left-right direction Yo are defined based on the vehicle Am resting on a horizontal plane. Specifically, the longitudinal direction ZG is defined along the longitudinal direction (direction of travel) of the vehicle Am. The left-right direction Yo is defined along the width direction of the vehicle Am. Furthermore, the up-down direction US is defined along the vertical direction of the horizontal plane that defines the longitudinal direction ZG and the left-right direction Yo. Note that for simplicity of description, the symbols indicating each direction may be omitted as appropriate.

[0023] The position sensor 64 is provided integrally with the actuator 63a or the gear unit. The position sensor 64 electrically or magnetically detects the tilt angle of the concave mirror 62a adjusted by the displacement mechanism 63. The position sensor 64 sequentially outputs an output signal indicating the current tilt angle of the concave mirror 62a to the head-up ECU 70.

[0024] The head-up ECU 70 is a control circuit of the HUD 100 that performs integrated control of the PGU 61 and the actuator 63a. The head-up ECU 70 mainly includes a computer equipped with a processing unit 51, a RAM 52, a storage 53, an input / output interface, and a bus connecting these components. The head-up ECU 70 further includes a drive circuit for driving the LCD panel, the backlight, and the actuator 63a, and a detection circuit for acquiring an output signal from the position sensor 64.

[0025] The head-up ECU 70 changes the content CT (see FIGS. 3 and 4) to be displayed as a virtual image Vi in association with the position of the display area VA. Specifically, the head-up ECU 70, in cooperation with the displacement mechanism 63, switches the position of the display area VA, where the virtual image Vi is displayed, between a plurality of positions including a normal position VP1 and an upper position VP2, by controlling the drive of the actuator 63a. The head-up ECU 70 displays the virtual images Vi associated with the normal position VP1 and the upper position VP2, respectively, in response to the switching of the position of the display area VA by the actuator 63a (see FIG. 4).

[0026] The normal position VP1 is the position of the display area VA where a virtual image Vi is displayed in the driver's peripheral vision PVF (see Figure 3). The normal position VP1 is defined below the upper position VP2. The normal position VP1 is the reference position of the display area VA and corresponds to a permanent position that is used for a longer period of time than the upper position VP2. Within the display area VA at the normal position VP1, content CT indicating vehicle information such as a speedometer CTv (see the upper part of Figure 4) is displayed. In the following description, the content CT associated with the normal position VP1 will be referred to as the first content CT1. The driver can recognize the virtual image Vi of the first content CT1 displayed within the display area VA at the normal position VP1 at the timing when he or she wishes to obtain information.

[0027] The upper position VP2 is the position of the display area VA where the virtual image Vi is displayed so as to overlap the driver's central visual field CVF (see FIG. 3). The upper position VP2 is defined above the normal position VP1 so as not to overlap with the normal position VP1. The display area VA moves from the normal position VP1 to the upper position VP2 when a specific event that should be notified to the driver occurs. Event-related content CT, such as route guidance content CTrg (see the lower part of FIG. 4) and pedestrian notification content, is displayed within the display area VA at the upper position VP2. In the following description, the content CT associated with the upper position VP2 is referred to as second content CT2. When an event occurs, the driver can recognize the virtual image Vi of the second content CT2 displayed within the display area VA at the upper position VP2 without significantly averting their gaze from the road ahead.

[0028] The relative positional relationship between the normal position VP1 and the upper position VP2 may be changed as appropriate. For example, the lower edge of the upper position VP2 may be in contact with the upper edge of the normal position VP1, or may be slightly spaced apart from the upper edge of the normal position VP1. Furthermore, the display area VA of the upper position VP2 and the display area VA of the normal position VP1 may partially overlap.

[0029] To realize the virtual image display control that links the field of view position and the content CT described above, the head-up ECU 70 executes a program (virtual image display program) stored in the storage 53 using the processing unit 51, and includes multiple functional units. Specifically, the head-up ECU 70 includes functional units such as an information acquisition unit 71, a display control unit 72, and an abnormality detection unit 73.

[0030] The information acquisition unit 71 is connected to the communication bus and the meter ECU 32. The information acquisition unit 71 acquires, from the communication bus, route information provided by the navigation ECU 21, and target information and control status information around the vehicle provided by the driving assistance ECU 22. Image data for virtual image display generated by the meter ECU 32 is sequentially input to the information acquisition unit 71.

[0031] The information acquisition unit 71 is electrically connected to an operation unit 68. The operation unit 68 is a switch that allows the driver to adjust the position of the display area VA and to switch the display of the virtual image Vi on and off. A dedicated switch provided on the instrument panel 9, a steering switch provided on the steering wheel, a center display with a touch panel function, a voice input device that detects the driver's speech, etc. can be used as the operation unit 68.

[0032] The information acquisition unit 71 acquires input information to the operation unit 68 when the operation unit 68 is operated by a driver or the like. The input information is provided from the information acquisition unit 71 to the display control unit 72, which adjusts the position of the display area VA and switches the virtual image display on and off in accordance with the driver's operation. The adjustment of the position of the display area VA corresponds to user calibration for adapting the position of the display area VA to the individual driver. The user calibration is performed when each individual driver uses the HUD 100 (vehicle Am) for the first time. In the user calibration, the driver operates the operation unit 68 to adjust the normal position VP1 and the upper position VP2 so that the virtual image Vi is not cut off even when the eye point EP is slightly moved in the up-down direction US, the left-right direction Yo, and the front-back direction ZG. Through such user calibration, the setting value of the position of the display area VA associated with each individual driver is stored in the storage 53.

[0033] The display control unit 72 is a control unit that performs integrated control of the PGU 61 and the actuator 63a. The display control unit 72 generates video data and control signals to be output to the PGU 61, and drive signals to be output to the actuator 63a. The display control unit 72 selects content CT to be displayed as a virtual image Vi, and controls the position of the display area VA according to the content CT to be displayed.

[0034] The display control unit 72 refers to a preset data table based on the information acquired by the information acquisition unit 71 and selects the content CT to be displayed as a virtual image and the position of the display area VA. Based on the selection result of the content CT, the display control unit 72 extracts material data of images to be used to generate video data from the RAM 52 or the storage 53. The display control unit 72 appropriately combines image data generated from the material data with image data provided by the meter ECU 32 to generate each frame image of the video data. The display control unit 72 sequentially outputs video data consisting of a large number of consecutive frame images to the PGU 61.

[0035] When the display control unit 72 determines to move the display area VA, it switches the content CT to be displayed as a virtual image in association with the start or end of driving of the actuator 63a. As an example, when the display control unit 72 moves the display area VA from the normal position VP1 to the upper position VP2, it switches the content CT to be displayed as a virtual image immediately before starting to move the display area VA. Conversely, when the display area VA moves from the upper position VP2 to the normal position VP1, it switches the content CT to be displayed as a virtual image immediately after completing the movement of the display area VA. Furthermore, during the above-mentioned user calibration, the display control unit 72 displays, for example, virtual images Vi indicating the positions of the four corners, four sides, and center of the display area VA as content CT for position adjustment.

[0036] The abnormality detection unit 73 is connected to the PGU 61, the actuator 63a, and the position sensor 64, and detects various abnormalities occurring in the HUD 100, such as abnormalities in the displacement of the display area VA and abnormalities in the image. Specifically, the abnormality detection unit 73 can detect abnormalities in the PGU 61, abnormalities in the actuator 63a, malfunctions of the gear unit, as well as circuit abnormalities in the head-up ECU 70 and software abnormalities in the virtual image display program. If the abnormality detection unit 73 detects the same abnormality multiple times (for example, about three times), it determines that the abnormality has occurred. If the abnormality detection unit 73 detects an abnormality in the HUD 100 and determines that an abnormality has occurred, it provides the display control unit 72 with information indicating the abnormality detection (hereinafter, abnormality detection information) and information indicating the type of the detected abnormality (hereinafter, abnormality type information).

[0037] When an abnormality occurs in the virtual image display by the HUD 100, the display control unit 72 performs fail-safe control so as not to impede normal driving by the driver. The display control unit 72 starts a fail-safe transition process (see FIG. 5) based on acquisition of abnormality detection information from the abnormality detection unit 73. The display control unit 72 acquires abnormality type information attached to the abnormality detection information (S11), and determines the type of abnormality (described below) based on the abnormality type information (S12). The display control unit 72 selects an abnormality response pre-associated with the determined type of abnormality (S13), and starts the fail-safe control that has been decided to be implemented by transitioning to fail-safe mode (S14). Details of the fail-safe control for each abnormality type performed by the display control unit 72 will be described below based on FIGS. 6 to 12 and with reference to FIGS. 1 and 2.

[0038] <Abnormality type 1: Display range VA is too high> The abnormality detection unit 73 detects an abnormality in the displacement of the display area VA, such as an excessive rise in the display area VA from its normal position (see the lower reference line RBL), as shown in Figure 6, between the normal position VP1H and the upper position VP2H. The abnormality detection unit 73 references the output signal of the position sensor 64, compares the current position with the desired position, and if it detects a state in which the difference between the current and desired positions (see the arrows) exceeds a threshold value multiple times (e.g., three times) consecutively, it determines that an excessive rise is an abnormality (see Figure 7, "Abnormal Occurrence"). The phenomenon of the display area VA rising too high is caused by repeated displacement in the up-down direction US during driving, which causes the tilt angle of the concave mirror 62a to deviate from its normal position due to vibration or the like. If the display area VA rises too high, the content CT, which is displayed as a virtual image at the upper position VP2H, may be positioned in the central visual field CVF and obstruct the driver's forward visibility, potentially impeding normal driving. When the abnormality detection unit 73 detects that the display area VA has risen too much, it provides the display control unit 72 with abnormality type information indicating that the display area VA has risen too much, in addition to the abnormality detection information.

[0039] The display control unit 72 continues to display the virtual image Vi even when the abnormality detection unit 73 detects that the display area VA has risen too high. When the abnormality detection unit 73 detects that the display area VA has risen too high, the display control unit 72 may continue to allow the display area VA to be displaced, or may restrict (prohibit) the displacement of the display area VA. As fail-safe control, the display control unit 72 performs a return process for the displacement mechanism 63 at a predetermined timing. The predetermined timing may be, for example, the next time the HUD 100 is started, or more specifically, the timing when the ignition of the vehicle Am switches from an OFF state to an ON state (see FIG. 7 IG ON). The ON state of the ignition of the vehicle Am indicates a state in which the vehicle Am can be driven by shifting to the drive range.

[0040] In the restoration process, the display control unit 72 controls the drive of the actuator 63a while referring to the output signal of the position sensor 64, and resets the reference position (zero point) of the tilt angle of the concave mirror 62a (see ZPD in FIG. 7). After resetting the reference position, the display control unit 72 can restore the display area VA to the normal position by reading the value set in the user calibration. Note that the display control unit 72 resets the reference position when the "enable" of the HUD 100 is switched to the OFF state, regardless of whether an abnormality occurs or not, in other words, in both normal and abnormal conditions (see EN OFF in FIG. 7). The display control unit 72 resets the reference position based on the ignition power being switched ON as the restoration process only in the event of an abnormality, thereby allowing the display area VA to be restored to the normal position earlier than in normal conditions.

[0041] After determining that an abnormality has occurred in the display area VA due to excessive increase, the display control unit 72 may continue both the displacement of the display area VA and the display of the virtual image Vi. In this case, the display control unit 72 maintains a state in which the position of the display area VA can be changed by operation input to the operation unit 68 until the HUD 100 is turned off. That is, as a fail-safe control, the display control unit 72 sets the position of the display area VA to a state in which the position can be changed, and then performs a restoration process at a predetermined timing. Even if the driver has performed a position adjustment to return the display area VA that has increased too much, the display control unit 72 restores the position of the display area VA to the initial value set by the initial user calibration in the restoration process.

[0042] According to the above fail-safe control, the driver can adjust the excessively raised upper position VP2H and normal position VP1H to appropriate positions by inputting an operation to the operation unit 68 during a period when the vehicle Am is temporarily stopped, etc. In addition, according to the restoration process at the next startup, the vertical movement of the display area VA within the normal movable range is resumed without causing cutting off of the virtual image Vi. Note that when the restoration process is performed, the result of the adjustment of the angle of view position performed after the detection of excessively raised position may be discarded.

[0043] <Abnormality type 2: Fixation of display area VA at upper position VP2> The abnormality detection unit 73 detects the fixation of the display area VA as an abnormality in the displacement of the display area VA. The abnormality detection unit 73 determines that fixation has occurred when the tilt angle of the concave mirror 62a, i.e., the output signal of the position sensor 64, remains unchanged despite the actuator 63a being driven. Fixation of the display area VA can be caused by malfunction of the actuator 63a, a malfunction of the gear unit, a malfunction of the control circuit or software, or the like. When the abnormality detection unit 73 detects fixation of the display area VA, it further identifies the location of the fixation by referring to the output signal of the position sensor 64. When the abnormality detection unit 73 detects fixation of the display area VA, it provides the display control unit 72 with abnormality type information indicating the occurrence of fixation and the location of the fixation, in addition to the abnormality detection information.

[0044] As shown in Figure 8, when the display area VA is fixed at the upper position VP2, the first content CT1 that should be displayed at the normal position VP1 is displayed inside or near the central visual field CVF. The first content CT1 displayed at the normal position VP1 is often a fast-moving display or a display with a large amount of information. Therefore, if the display area VA does not move down and the first content CT1 is displayed within the display area VA at the upper position VP2, the driver's forward visibility may be obstructed, which may hinder normal driving.

[0045] When the display area VA is stuck at the upper position VP2, the display control unit 72 initiates an abnormality response using fail-safe control earlier than when the display area VA is stuck at the normal position VP1. Specifically, when the display area VA is stuck at the upper position VP2, the display control unit 72 determines whether the currently displayed content CT obstructs the driver's field of view. The display control unit 72 estimates whether a phenomenon such as flickering occurs based on the display size, display change speed, display position within the angle of view, etc. of the currently displayed content CT. The display control unit 72 may estimate that a phenomenon such as flickering occurs when a predetermined specific content CT is being displayed, or may estimate whether a phenomenon such as flickering occurs by grasping the display state of the currently displayed content CT. When the display control unit 72 estimates that a phenomenon such as flickering occurs, it determines that the currently displayed content CT obstructs the field of view.

[0046] If the display control unit 72 determines that the currently displayed content CT obstructs the field of view, it does not perform the above-described restoration process, but continues displaying the second content CT2 (see FIG. 4 ) and stops displaying the first content CT1. This prevents flickering of the virtual image Vi, for example, due to changes in the numbers on the speedometer CTv. After canceling the display of the virtual image Vi, such as the first content CT1, the display control unit 72 performs restoration processing of the displacement mechanism 63 at a predetermined timing, such as the next startup when the ignition of the vehicle Am changes from the OFF state to the ON state (see FIG. 7 IG ON). Even if a type 2 sticking abnormality occurs, the display control unit 72 resets the reference position as a restoration process only when the ignition state is switched ON (see FIG. 7 ZPD in the Abnormal State). If the sticking is resolved by the restoration process, the display control unit 72 resumes displaying the first content CT1. On the other hand, if the sticking is not resolved even after the restoration process, the display control unit 72 continues the state in which the display of the first content CT1 is suspended.

[0047] If the display control unit 72 determines that the content CT being displayed does not obstruct the field of view, it immediately starts the above-mentioned restoration process as fail-safe control. If the fixation is resolved by the restoration process, the display control unit 72 resumes displaying the virtual image Vi. On the other hand, if the fixation is not resolved even by the restoration process, the display control unit 72 continues displaying the second content CT2 and stops displaying the first content CT1.

[0048] <Abnormality type 3: Display area VA stuck at the middle position> 9, even if the display area VA does not completely transition and is stuck between the normal position VP1 and the upper position VP2 (hereinafter referred to as the intermediate position VPM), the first content CT1 such as the speedometer CTv is displayed near the central field of vision CVF. In this case, as in the case where the display area VA is stuck at the upper position VP2, the driver's forward visibility is blocked, which may hinder normal driving.

[0049] When the abnormality detection unit 73 detects a sticking at the middle position VPM, the display control unit 72 performs the same fail-safe control as when a sticking at the upper position VP2 is detected. Specifically, the display control unit 72 determines whether the currently displayed content CT obstructs the driver's field of view. If the display control unit 72 determines that the currently displayed content CT obstructs the field of view, the display control unit 72 continues displaying the second content CT2 (see FIG. 4) and stops displaying the first content CT1. After stopping the display of the first content CT1, the display control unit 72 performs the above-described restoration process at a predetermined timing, such as the next startup when the ignition of the vehicle Am changes from the OFF state to the ON state (see FIG. 7, IG ON). Even when a type 3 sticking abnormality occurs, the display control unit 72 resets the reference position as restoration process only when the abnormality occurs, based on the switching of the ignition state to ON (see FIG. 7, ZPD in Abnormal Condition). On the other hand, if the display control unit 72 determines that the currently displayed content CT does not obstruct the field of view, the display control unit 72 immediately starts the above-described restoration process as fail-safe control.

[0050] <Anomaly type 4: Non-smooth displacement> The abnormality detection unit 73 detects irregularities in the displacement of the display area VA, such as irregularities in the displacement as shown in FIG. 10. Normally, the display area VA moves between the normal position VP1 and the upper position VP2 at a generally constant speed (see the dashed line in FIG. 10). In contrast, if an abnormality occurs in the actuator 63a, the drive circuit, the gear unit, or the like, the speed at which the display area VA moves will fluctuate (see the solid line in FIG. 10). The abnormality detection unit 73 refers to the output signal of the position sensor 64, and if the fluctuation in the speed of movement exceeds a threshold, determines that irregularities in the displacement have occurred.

[0051] The display control unit 72 continues to display the virtual image Vi even when the abnormality detection unit 73 detects and determines that the displacement is not smooth. In this case, although the lack of smoothness may cause annoyance to the driver, the display position of the content CT is the same as in normal conditions and is unlikely to obstruct the driver's forward visibility. Therefore, the display control unit 72 prioritizes the driver's convenience and continues to present information using the virtual image Vi. As a fail-safe control, the display control unit 72 performs the above-mentioned restoration process at a predetermined timing, such as the next time the ignition of the vehicle Am is turned on (see IG ON in FIG. 7). Even when a type 4 non-smoothness abnormality occurs, the display control unit 72 resets the reference position as a restoration process based on the ignition state being turned on only when the abnormality occurs (see ZPD in abnormal conditions in FIG. 7). Even if the restoration process does not resolve the non-smoothness, the display control unit 72 continues to display the virtual image Vi.

[0052] <Abnormality type 5: Display area VA stuck at normal position VP1> The abnormality detection unit 73 detects fixation of the display area VA at the normal position VP1 as shown in FIG. 11 as an abnormality in the displacement of the display area VA. When the display area VA is fixed at the normal position VP1, the second content CT2, which should be displayed at the upper position VP2, is displayed at the normal position VP1. In this case, the second content CT2 is simply displayed lower than normal and is unlikely to obstruct the driver's forward visibility. Therefore, when the display area VA is fixed at the normal position VP1, the display control unit 72 continues to display the virtual image Vi. As a fail-safe control, the display control unit 72 performs the above-described restoration process at a predetermined timing, such as the next startup when the ignition of the vehicle Am changes from the OFF state to the ON state (see FIG. 7, IG ON). Even when a Type 5 fixation abnormality occurs, the display control unit 72 resets the reference position as a restoration process only when the ignition state is switched ON (see FIG. 7, ZPD during abnormality). Even if the fixation is not resolved by the recovery process, the display control unit 72 continues to display the virtual image Vi.

[0053] <Anomaly Type 6: Display Range VA Drops Too Much> The abnormality detection unit 73 detects an abnormality in the displacement of the display area VA, such as an excessive drop in the display area VA from a normal position (see the upper reference line RTL), such as the normal position VP1L and the upper position VP2L shown in Figure 12. The abnormality detection unit 73 references the output signal of the position sensor 64, compares the current position with the desired position, and determines that an excessive drop has occurred if the difference between the current and desired positions (see the arrows) exceeds a threshold. Similar to the excessive rise abnormality described above, the phenomenon of the display area VA dropping too low is caused by the tilt angle of the concave mirror 62a deviating from its normal position due to repeated displacement of the display area VA while driving.

[0054] If the display area VA drops too low, the display positions of the first content CT1 and the second content CT2 will be farther from the central visual field CVF than normal, but the forward visibility will not be obstructed. Therefore, the display control unit 72 continues to display the virtual image Vi even if the abnormality detection unit 73 detects that the display area VA has dropped too low. If the abnormality detection unit 73 detects that the display area VA has dropped too low, the display control unit 72 may continue to allow the display area VA to be displaced, or may restrict (prohibit) the displacement of the display area VA. As a fail-safe control, the display control unit 72 performs a recovery process at a predetermined timing, such as the next time the ignition of the vehicle Am is switched from the OFF state to the ON state (see FIG. 7, IG ON). Even if a Type 6 excessive drop abnormality occurs, the display control unit 72 resets the reference position as a recovery process when the ignition state is switched ON only when an abnormality occurs (see FIG. 7, ZPD during an abnormality).

[0055] After determining that an abnormality has occurred in the excessively lowered display area VA, the display control unit 72 may continue both the displacement of the display area VA and the display of the virtual image Vi. In this case, the display control unit 72 maintains a state in which the position of the display area VA can be changed by an operation input to the operation unit 68 until the HUD 100 is turned off. That is, as a fail-safe control, the display control unit 72 sets the position of the display area VA to a state in which the position can be changed, and then performs a restoration process at a predetermined timing. Even if the driver has performed a position adjustment to return the display area VA that has been lowered too much, the display control unit 72 restores the position of the display area VA to the initial value set by the initial user calibration in the restoration process.

[0056] According to the above fail-safe control, the driver can adjust the upper position VP2L and the normal position VP1L, which have fallen too low, to appropriate positions by inputting an operation to the operation unit 68, for example, during a period when the vehicle Am is temporarily stopped. In addition, according to the restoration process at the next startup, the vertical movement of the display area VA within the normal movable range is resumed without causing cutting off of the virtual image Vi.

[0057] <Anomaly Type 7: Display area VA continues to fluctuate up and down> The abnormality detection unit 73 detects an abnormality in the displacement of the display area VA, such as the display area VA continuing to oscillate (continue to move) in the vertical direction US without being fixed at a specific position. For example, if an abnormality occurs in the actuator 63a, the drive circuit, the gear unit, or the like, the display area VA will continue to move slightly in the vertical direction US, in other words, the position of the display area VA will become unstable. The abnormality detection unit 73 refers to the output signal of the position sensor 64, and if it observes a continuous fluctuation in the position of the display area VA that exceeds a threshold, it determines that the display area VA is continuing to oscillate up and down.

[0058] When the abnormality detection unit 73 detects continuous shaking of the display area VA, the display control unit 72 determines whether the currently displayed content CT obstructs the driver's field of view. If the display control unit 72 determines that the currently displayed content CT obstructs the driver's field of view, it immediately stops displaying the virtual image Vi as fail-safe control without performing a recovery process. This prevents the virtual image Vi from continuously moving within the driver's field of view, causing the driver to lose attention to their surroundings and hindering normal driving. In this case, the display control unit 72 performs the recovery process described above at a predetermined timing, such as the next time the ignition of the vehicle Am is switched from the OFF state to the ON state (see FIG. 7, IG ON). Even if a Type 7 continuous movement abnormality occurs, the display control unit 72 resets the reference position as a recovery process only when the abnormality occurs, based on the ignition state being switched ON (see FIG. 7, ZPD during abnormality). On the other hand, if it determines that the currently displayed content CT does not obstruct the field of view, the display control unit 72 immediately starts the recovery process described above as fail-safe control.

[0059] <Anomaly Type 8: Inconsistency between video and actuator 63a operation> The abnormality detection unit 73 detects an abnormality in the displacement of the display area VA, such as a mismatch between the timing of switching the content CT and the timing of displacing the display area VA. The abnormality detection unit 73 determines the timing of switching the content CT (video) based on display control information acquired from the display control unit 72. Furthermore, the abnormality detection unit 73 references the output signal of the position sensor 64 to determine the start timing of the angle of view movement. Based on the determined timings, the abnormality detection unit 73 detects the occurrence of an event such as the operation of the actuator 63a being slower than specified timing and the video switching being slower than specified timing.

[0060] The display control unit 72 continues to display the virtual image Vi even when the abnormality detection unit 73 detects a timing discrepancy. In this case, although the driver may feel uncomfortable when the position of the display area VA is switched, the content CT is unlikely to obstruct the forward field of view. Therefore, by continuing to display the virtual image Vi, priority may be given to ensuring convenience for the driver.

[0061] <Anomaly type 9: Abnormal noise and vibration due to displacement> Abnormalities in the displacement of the display area VA are expected to include abnormal noise or vibrations caused by the position of the display area VA being moved up or down. Such abnormalities are difficult for the abnormality detection unit 73 to detect. For this reason, the HUD 100 is provided with an operation unit 68 that can switch the display on and off. If the driver finds the abnormal noise and vibrations bothersome, they can input an operation to turn off the display into the operation unit 68. The display control unit 72 stops displaying the virtual image Vi based on the input information acquired from the operation unit 68. In this way, although the abnormal noise and vibrations caused by the displacement of the display area VA may be bothersome to the driver, they are unlikely to obstruct the forward visibility. Therefore, ensuring the driver's convenience may be prioritized by continuing to display the virtual image Vi.

[0062] <Anomaly Type 10: White Painting> The abnormality detection unit 73 detects an abnormality in the PGU 61 that emits the display light Lvi, in addition to an abnormality in the displacement of the display area VA. Specifically, the abnormality detection unit 73 detects an abnormality in the PGU 61 in which backlight light is directly emitted (hereinafter referred to as a white-image abnormality) as an abnormality in the PGU 61. The white-image abnormality occurs due to an abnormality in the LCD panel, drive circuit, etc. When the white-image abnormality occurs, the driver is forced to look away from the road and is unable to continue normal driving. Therefore, when the abnormality detection unit 73 detects a white-image abnormality in the PGU 61, the display control unit 72 immediately stops displaying the virtual image Vi as a fail-safe control without performing a recovery process. This prevents a situation in which the glare of the white image makes it difficult to see ahead and hinders normal driving.

[0063] <Summary of implementation> In the present embodiment described so far, when fixation of the display area VA is detected as an abnormality in the displacement of the display area VA, fail-safe control is performed according to the position where the display area VA is fixed. Therefore, even if the HUD 100 is configured to be able to displace the display area VA of the virtual image Vi, it is possible to suppress the impact of the occurrence of an abnormality on users such as the driver.

[0064] Specifically, whether to continue displaying the virtual image Vi can be appropriately determined depending on the position where the display area VA is fixed. As a result, in a scene where the virtual image Vi is likely to obstruct the driver's field of vision, the display of the virtual image Vi is stopped, and in a scene where the virtual image Vi is unlikely to obstruct the driver's field of vision, the continuation of the display of the virtual image Vi is permitted. Therefore, even if an abnormality occurs, the impact on the driver can be minimized.

[0065] Additionally, in this embodiment, the position of the display area VA is switched between a plurality of positions including at least the normal position VP1 and an upper position VP2 above the normal position VP1. If the display area VA is stuck at the upper position VP2, the fail-safe control is initiated to deal with the abnormality earlier than if the display area VA is stuck at the normal position VP1. If the display area VA is stuck at the upper position VP2, there is a risk that the annoying content CT will be displayed inside or near the central visual field CVF. However, if the abnormality is dealt with early in the fixation at the upper position VP2, the virtual image Vi can be quickly resolved even if it obstructs the driver's field of vision.

[0066] Furthermore, in this embodiment, when the display area VA is fixed at the upper position VP2, it is determined whether the currently displayed content CT obstructs the driver's field of view. If the currently displayed content CT obstructs the field of view, the display of the second content CT2 associated with the upper position VP2 continues, while the display of the first content CT1 associated with the normal position VP1 is stopped. As a result, it is unlikely that the first content CT1, which exhibits rapid display changes, will be displayed in the display area VA at the upper position VP2, which overlaps with the central visual field CVF, obstructing the driver's field of view. Furthermore, because the display of the content CT associated with the upper position VP2 continues, convenience for the driver is unlikely to be impaired.

[0067] Furthermore, in this embodiment, when the display area VA is fixed at the upper position VP2, if the displayed content CT does not obstruct the field of view, a recovery process is performed as fail-safe control. By immediately performing this recovery process, the fixation of the display area VA can be resolved. As a result, the virtual image display can be resumed with only a temporary interruption, making it less likely that the driver's convenience will be impaired.

[0068] Additionally, in this embodiment, if the display area VA is fixed at the normal position VP1, the display of the virtual image Vi continues. Then, a return process is performed as fail-safe control at a predetermined timing. Even if the second content CT2 that should be displayed at the upper position VP2 is displayed at the fixed normal position VP1, the driver's field of vision is unlikely to be obstructed. Furthermore, since the return process is performed at a predetermined timing, the fixation of the display area VA can be resolved. As described above, by performing a process to continue the display of the virtual image Vi, the impact on the driver due to the occurrence of fixation can be minimized.

[0069] In this embodiment, when the display area VA is fixed at an intermediate position VPM between the normal position VP1 and the upper position VP2, it is determined whether the currently displayed content CT obstructs the driver's field of view. If the currently displayed content CT obstructs the field of view, the display of the second content CT2 associated with the upper position VP2 is continued, while the display of the first content CT1 associated with the normal position VP1 is stopped. This reduces the likelihood of the first content CT1, which undergoes rapid display changes, being displayed near the central visual field CVF and obstructing the driver's field of view. Additionally, if the currently displayed content CT does not obstruct the field of view, a return process is immediately performed, allowing the virtual image display to be resumed with only a temporary interruption. As a result, driver convenience is less likely to be impaired.

[0070] Furthermore, in this embodiment, irregularities in the displacement of the display area VA are detected. If irregularities are detected, the display of the virtual image Vi continues. In this way, even if the displacement becomes irregular, each content CT can be displayed at an appropriate display position, so that the driver's forward visibility is less likely to be obstructed. Furthermore, by performing a restoration process at a predetermined timing and resolving the irregularities, the impact on the driver due to the occurrence of an abnormality can be suppressed.

[0071] Additionally, in this embodiment, an excessive increase in the display area VA is detected as an abnormality in the displacement of the display area VA. If an excessive increase in the display area VA is detected, the display of the virtual image Vi continues, and a return process is performed at a predetermined timing. By resetting the position of the display area VA in this manner, the movable range of the display area VA can be returned to a normal range. As a result, even if an abnormality such as an excessive increase occurs, the impact on the driver can be minimized.

[0072] Furthermore, if the abnormality detection unit 73 detects that the display area VA has risen too high, the display control unit 72 continues to display the virtual image Vi while allowing the driver to adjust the position of the display area VA, and executes a return process of the displacement mechanism 63 as fail-safe control at a predetermined timing. Therefore, the driver can adjust the position of the display area VA that has risen too high downward, for example, when the vehicle is stopped, to return it to an appropriate position. As a result, the impact on the driver of the occurrence of an abnormality due to the display area VA being too high can be further suppressed.

[0073] In this embodiment, an abnormality in the displacement of the display area VA is detected as an excessive drop in the display area VA. If an excessive drop in the display area VA is detected, the display of the virtual image Vi continues, and a return process is performed at a predetermined timing. By resetting the position of the display area VA in this manner, the movable range of the display area VA can be returned to a normal range. As a result, even if an abnormality such as an excessive drop occurs, the impact on the driver can be minimized.

[0074] Furthermore, if the abnormality detection unit 73 detects that the display area VA has dropped too low, the display control unit 72 continues to display the virtual image Vi while allowing the driver to adjust the position of the display area VA, and executes a fail-safe control to restore the displacement mechanism 63 at a predetermined timing. Therefore, the driver can adjust the position of the display area VA that has dropped too low downward, for example, when the vehicle is stopped, and return it to an appropriate position. As a result, the impact on the driver of the occurrence of an abnormality such as excessive dropping can be further suppressed.

[0075] Furthermore, in this embodiment, an abnormality in the displacement of the display area VA is detected when the display area VA continues to shake in the vertical direction US. If the continuous shaking of the display area VA is detected, it is determined whether the currently displayed content CT obstructs the driver's field of vision. If the currently displayed content CT obstructs the field of vision, fail-safe control is performed to immediately stop the display of the virtual image Vi. If the currently displayed content CT does not obstruct the field of vision, fail-safe control is performed to perform a recovery process, and the position of the display area VA is reset. As a result, the movable range of the display area VA can return to a normal range. According to the above abnormality response, even if an abnormality occurs in which the display area VA continues to shake, the impact on the driver can be minimized.

[0076] Additionally, in this embodiment, an abnormality in the displacement of the display area VA is detected when the timing of switching the content CT does not coincide with the timing of displacing the display area VA. Even if a timing discrepancy is detected, the display of the virtual image Vi continues. In this way, if the image and the operation of the actuator 63a do not match, the driver may feel uncomfortable when the display area VA is switched, but the forward field of view is unlikely to be obstructed. Therefore, by taking an abnormality response that continues the display of the virtual image Vi, it is possible to minimize the impact on the driver even if a timing discrepancy occurs.

[0077] In this embodiment, the display of the virtual image Vi is stopped based on input information to the operation unit 68, which switches the display of the virtual image Vi on and off. Therefore, if an abnormal sound or vibration occurs due to the movement of the display area VA, the driver who feels uncomfortable can stop the display of the virtual image Vi at their own discretion. Therefore, by preparing the operation unit 68, it is possible to suppress the impact on the driver even if an abnormality that cannot be detected by the abnormality detection unit 73 occurs.

[0078] Furthermore, in this embodiment, an abnormality in the PGU 61 that emits the display light Lvi that is imaged as the virtual image Vi is detected. If an abnormality in the PGU 61 is detected, the display of the virtual image Vi is stopped. If a white screen abnormality occurs due to a malfunction of the PGU 61, the driver is forced to look away from the road ahead. Therefore, by not performing the recovery process and immediately stopping the display of the virtual image Vi, the period during which the driver's normal driving is hindered is shortened. As a result, the impact of the abnormality in the PGU 61 on the driver can be minimized.

[0079] In the above embodiment, the normal position VP1 corresponds to the "first position", the upper position VP2 corresponds to the "second position", the PGU61 corresponds to the "display unit", the information acquisition unit 71 corresponds to the "input grasping unit", and the HUD100 corresponds to the "virtual image display device".

[0080] (Other embodiments) Although one embodiment of the present disclosure has been described above, the present disclosure should not be construed as being limited to the above embodiment, and can be applied to various embodiments and combinations within the scope that does not deviate from the gist of the present disclosure.

[0081] The fail-safe control in the event of a Type 1 abnormality (excessive increase in the display area VA) in the above embodiment may be modified as appropriate. Specifically, in Modification 1 of the above embodiment, when an excessive increase in the display area VA is detected, the display control unit 72 stops displaying all virtual images Vi. Furthermore, in Modification 2 of the above embodiment, the display control unit 72 stops the function of displacing the display area VA and fixes the position of the display area VA to the normal position VP1. The display control unit 72 displays the second content CT2 at the normal position VP1 in addition to the first content CT1.

[0082] The display control unit 72 in Modification 3 of the above embodiment automatically adjusts the upper position VP2 based on abnormal detection of excessively elevated display range VA. In other words, the display control unit 72 reduces the upward displacement from the normal position VP1 and sets the upper position VP2 at a lower position. Furthermore, the display control unit 72 in Modification 4 of the above embodiment immediately performs a return process based on abnormal detection of excessively elevated display range VA.

[0083] The display control unit 72 of the fifth modification of the above embodiment changes the content CT to a previously prepared content CT for abnormality response that does not obstruct the forward field of view, based on the abnormality detection of the excessively rising display area VA. The content CT for abnormality response has characteristics such as a smaller display size, a lower display position, and a slower display change than the content CT for normal use.

[0084] In the sixth modification of the above embodiment, real-time detection information of the eye point EP by the driver monitor is provided to the head-up ECU 70. The display control unit 72, in cooperation with the driver monitor, adjusts the excessively raised upper position VP2 and normal position VP1 in accordance with the current position of the eye point EP based on the detection information.

[0085] In the seventh modification of the above embodiment, information indicating the seat position of the driver's seat (hereinafter referred to as seat position information) is provided to the head-up ECU 70. The display control unit 72 estimates the current position of the eye point EP based on the seat position information, and adjusts the excessively raised upper position VP2 and normal position VP1 to match the estimated eye point EP.

[0086] The fail-safe control in the event of an abnormality of types 1 and 6 (excessive increase or decrease in the display area VA) in the above-described embodiments may be modified as appropriate. Specifically, in Modification 8 of the above-described embodiment, when an excessive increase or decrease in the display area VA is detected, the display of the virtual image Vi continues, while the driver's adjustment of the position of the display area VA is restricted (prohibited). Therefore, a situation in which the display of the virtual image Vi continues in a state where clipping is likely to occur due to emergency position adjustment following the occurrence of an abnormality can be avoided.

[0087] The fail-safe control in the event of a type 2 or 3 abnormality (sticking at the upper position VP2 or the intermediate position VPM) in the above embodiment may be modified as appropriate. Specifically, in Modification 9 of the above embodiment, in order to avoid obstruction of the field of view due to the content CT, the display control unit 72 immediately stops displaying the virtual image Vi without performing a recovery process. Then, the display control unit 72 performs the recovery process at the next startup.

[0088] In Modifications 10 and 11 of the above embodiment, the determination of whether the displayed content CT obstructs the driver's field of view is omitted. When the display area VA is fixed at the upper position VP2 or the intermediate position VPM, the display control unit 72 in Modification 10 continues displaying the second content CT2 and stops displaying the first content CT1 as fail-safe control. Furthermore, when the display area VA is fixed at the upper position VP2 or the intermediate position VPM, the display control unit 72 in Modification 11 immediately performs recovery processing as fail-safe control.

[0089] In a 12th modification of the above embodiment, the display control unit 72 changes the mode of the content CT displayed as the virtual image Vi as fail-safe control when the display area VA is stuck at the upper position VP2 or the middle position VPM. As in the 5th modification, the display control unit 72 changes the content CT to a previously prepared abnormality response content CT that does not obstruct the forward field of view. In the 12th modification, the content CT whose display mode is changed may be only the first content CT1.

[0090] The fail-safe control in the event of a Type 4 abnormality (unsmooth displacement) in the above-described embodiments may be modified as appropriate. Specifically, in Modification 13 of the above-described embodiment, when an abnormality that causes unsmooth displacement is detected, the display control unit 72 stops displaying all virtual images Vi. Furthermore, in Modification 14 of the above-described embodiment, the display control unit 72 stops the function of displacing the display area VA and fixes the position of the display area VA to the normal position VP1. Furthermore, in Modification 15 of the above-described embodiment, the display control unit 72 immediately performs a return process.

[0091] The fail-safe control in the case where a Type 7 abnormality (the display area VA continues to shake up and down) occurs in the above embodiment may be modified as appropriate. Specifically, in Modification 16 of the above embodiment, even when the abnormality detection unit 73 detects that the display area VA is continuing to shake, the display control unit 72 continues to display the virtual image Vi. When a Type 7 abnormality occurs, the continuously moving virtual image Vi may give the driver a sense of discomfort. However, if the structure is such that a Type 7 abnormality is extremely unlikely to occur, the display control unit 72 may be configured to continue to display the virtual image Vi.

[0092] Furthermore, in the seventeenth modification of the above embodiment, when an abnormality of continuous up-and-down movement is detected, the display control unit 72 stops the function of displacing the display area VA and fixes the position of the display area VA to the normal position VP1. Furthermore, in the eighteenth modification of the above embodiment, the display control unit 72 stops all display of the virtual image Vi without performing a return process.

[0093] The fail-safe control in the event of a Type 8 abnormality (mismatch in operation) in the above embodiment may be modified as appropriate. Specifically, in Modification 19 of the above embodiment, when an abnormality that results in a mismatch in operation is detected, the display control unit 72 stops the function of displacing the display area VA and fixes the position of the display area VA to the normal position VP1.

[0094] The fail-safe control in the case where a Type 10 abnormality (white image) occurs in the above embodiment may be modified as appropriate. Specifically, in Modification 20 of the above embodiment, even when the abnormality detection unit 73 detects an abnormality in the PGU 61, the display control unit 72 continues to display the virtual image Vi. When a Type 10 abnormality occurs, the driver is forced to look away from the road, which hinders normal driving. However, if the structure is such that a Type 10 abnormality is extremely unlikely to occur, the display control unit 72 may be configured to continue to display the virtual image Vi.

[0095] The displacement mechanism 63 of the 21st modification of the above embodiment can displace the display area VA not only in the up-down direction US but also in the left-right direction Yo. Furthermore, the displacement mechanism 63 may position the display area VA at a position different from the normal position VP1 and the upper position VP2. Furthermore, the displacement mechanism 63 may displace the entire optical unit including the PGU 61 and the magnifying optical system 62 relative to the housing of the HUD 100. Furthermore, the displacement mechanism 63 may displace the housing of the HUD 100 relative to the vehicle Am.

[0096] In a modification 22 of the above embodiment, some or all of the processing functions of the head-up ECU 70 are implemented in the meter ECU 32 or another in-vehicle ECU. In this modification 22, a system including the meter ECU 32 or another in-vehicle ECU may serve as a "virtual image display device."

[0097] The PGU 61 of the above embodiment may be provided with an EL (Electro Luminescence) panel instead of the LCD panel and backlight. Furthermore, the PGU 61 may use a display device such as a plasma display panel, a cathode ray tube, or an LED instead of the EL panel. Furthermore, a laser projector or a DLP (Digital Light Processing, registered trademark) and a screen may be provided instead of the LCD panel and backlight. In the PGU 61 employing such a configuration, a display image drawn on the screen is projected onto the windshield WS by the magnifying optical system 62 and formed as a virtual image Vi. Furthermore, the optical element employed in the magnifying optical system 62 is not limited to a concave mirror and may be changed as appropriate to various mirrors, lenses, holographic optical elements, etc.

[0098] The processing units provided in the head-up ECU 70 and the meter ECU 32 in the above-described embodiments are hardware for arithmetic processing coupled to a RAM. The processing units include at least one arithmetic core, such as a CPU (Central Processing Unit) and a GPU (Graphics Processing Unit). The processing units may further include, for example, an FPGA (Field-Programmable Gate Array) and an IP core with other dedicated functions. Meanwhile, the RAM may include a video RAM for generating images. The processing units access the RAM to execute various processes for realizing the virtual image display method of the present disclosure.

[0099] The storage includes a non-transitory tangible storage medium. The storage of each ECU 32, 70 stores various programs (such as a display control program) executed by the processing unit. Such a storage medium is not limited to being provided on a circuit board, but may be provided in the form of a memory card or the like, inserted into a slot, and electrically connected to the control circuit of each ECU 32, 70. Furthermore, the storage medium may be an optical disk, a hard disk drive, or the like, from which the programs are copied to each ECU 32, 70.

[0100] In the above embodiment, the functions provided by the head-up ECU 70 and the meter ECU 32 can be provided by software and hardware that executes the software, software alone, hardware alone, or a combination of these. Furthermore, when such functions are provided by electronic circuits as hardware, the functions can also be provided by digital circuits including multiple logic circuits or analog circuits.

[0101] Vehicles equipped with the above-described display system are not limited to ordinary private passenger cars, but may also be rental cars, manned taxis, ride-sharing vehicles, freight vehicles, buses, etc. Furthermore, vehicles equipped with the display system may be right-hand drive vehicles or left-hand drive vehicles. Furthermore, the traffic environment in which the vehicle travels may be one based on left-hand traffic or one based on right-hand traffic. The display control according to the present disclosure may be optimized as appropriate according to the road traffic laws of each country and region, as well as the position of the vehicle's steering wheel.

[0102] The controller and methods described herein may be implemented by a special-purpose computer comprising a processor programmed to perform one or more functions embodied in a computer program. Alternatively, the apparatus and methods described herein may be implemented by special-purpose hardware logic circuitry. Alternatively, the apparatus and methods described herein may be implemented by one or more special-purpose computers comprising a processor executing a computer program in combination with one or more hardware logic circuits. Furthermore, the computer program may be stored as instructions executed by a computer on a computer-readable non-transitory storage medium.

[0103] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0104] (Technical thought 1) A virtual image display device used in a vehicle (Am) and displaying a virtual image (Vi) superimposed on a foreground, a displacement mechanism (63) that displaces the position of a display area (VA) in which the virtual image is displayed along the vertical direction of the vehicle; a display control unit (72) that controls the position of the display area in accordance with the content (CT) displayed as the virtual image; an abnormality detection unit (73) that detects at least sticking of the display area as an abnormality in the displacement of the display area, The virtual image display device is configured such that, when the abnormality detection unit detects that the display area is stuck, the display control unit performs fail-safe control according to the position where the display area is stuck. (Technical thought 2) the displacement mechanism switches the position of the display area between a plurality of positions including at least a first position (VP1) and a second position (VP2) above the first position; The virtual image display device described in Technical Idea 1, wherein the display control unit starts responding to an abnormality using the fail-safe control earlier when the display area is stuck at the second position than when the display area is stuck at the first position. (Technical Thought 3) The virtual image display device described in Technical Idea 2, wherein the display control unit performs fail-safe control to continue displaying the second content (CTrg) associated with the second position and stop displaying the first content (CTv) associated with the first position when the display area is stuck at the second position. (Technical Thought 4) The virtual image display device according to Technical Idea 2, wherein the display control unit performs a return process of the displacement mechanism as the fail-safe control when the display area becomes stuck at the second position. (Technical Thought 5) The display control unit If the display area is stuck at the second position, determining whether the displayed content obstructs the driver's view; If the content being displayed obstructs the view, the display of the second content (CT2) associated with the second position is continued, and the display of the first content (CT1) associated with the first position is stopped; The virtual image display device according to Technical Idea 2, wherein if the content being displayed does not obstruct the field of view, a return process of the displacement mechanism is performed as the fail-safe control. (Technical Thought 6) The virtual image display device described in Technical Idea 2, wherein the display control unit changes the manner of the content to be displayed as the virtual image as the fail-safe control when the display area becomes stuck at the second position. (Technical Thought 7) A virtual image display device described in any one of Technical Ideas 2 to 6, wherein the display control unit continues to display the virtual image when the display area becomes stuck at the first position, and performs a return process of the displacement mechanism at a predetermined timing as the fail-safe control. (Technical Thought 8) The display control unit If the display area is stuck between the first position and the second position, determining whether the displayed content obstructs the driver's view; If the content being displayed obstructs the view, the display of the second content (CT2) associated with the second position is continued, and the display of the first content (CT1) associated with the first position is stopped; The virtual image display device according to any one of Technical Ideas 2 to 7, wherein, when the content being displayed does not obstruct visibility, a return process of the displacement mechanism is carried out as the fail-safe control. (Technical Thought 9) The abnormality detection unit further detects non-smoothness of displacement as an abnormality in the displacement of the display area, A virtual image display device described in any one of technical ideas 2 to 8, wherein the display control unit continues to display the virtual image when the abnormality detection unit detects the non-smoothness, and performs the return process of the displacement mechanism at a predetermined timing as the fail-safe control. (Technical Thought 10) The abnormality detection unit further detects an excessive rise in the display area as an abnormality in the displacement of the display area, A virtual image display device described in any one of Technical Ideas 1 to 9, wherein the display control unit performs a return process of the displacement mechanism as the fail-safe control at a predetermined timing when the abnormality detection unit detects that the display area has risen too high. (Technical Thought 11) The abnormality detection unit further detects an excessive decrease in the display area as an abnormality in the displacement of the display area, A virtual image display device described in any one of Technical Ideas 1 to 10, wherein the display control unit performs a return process of the displacement mechanism as the fail-safe control at a predetermined timing when the abnormality detection unit detects that the display area has dropped too low. (Technical Thought 12) The abnormality detection unit further detects, as the abnormality in the displacement of the display area, an abnormality in which the display area continues to shake in the up and down direction, The display control unit When the abnormality detection unit detects that the display area is continuously shaking, it is determined whether the content being displayed obstructs the driver's field of vision; If the content being displayed obstructs visibility, the fail-safe control stops displaying the virtual image; 12. The virtual image display device according to any one of Technical Ideas 1 to 11, wherein, when the content being displayed does not obstruct visibility, a return process of the displacement mechanism is performed as the fail-safe control. (Technical Thought 13) The abnormality detection unit further detects, as the abnormality in the displacement of the display area, an abnormality in which the display area continues to shake in the up and down direction, A virtual image display device described in any one of Technical Ideas 1 to 11, wherein the display control unit continues to display the virtual image even when the abnormality detection unit detects continued shaking of the display area. (Technical Thought 14) the abnormality detection unit further detects, as the abnormality in the displacement of the display area, an abnormality in which a timing for switching the content does not coincide with a timing for displacing the display area; 14. The virtual image display device according to any one of Technical Ideas 1 to 13, wherein the display control unit continues to display the virtual image even when the abnormality detection unit detects a timing deviation. (Technical Thought 15) an input grasping unit (71) that acquires input information to an operation unit (68) that switches the display of the virtual image on and off, 15. The virtual image display device according to any one of Technical Ideas 1 to 14, wherein the display control unit stops displaying the virtual image based on the input information. (Technical Thought 16) The abnormality detection unit further detects an abnormality in a display unit (61) that emits display light (Lvi) that is formed as the virtual image, A virtual image display device described in any one of Technical Ideas 1 to 15, wherein the display control unit stops displaying the virtual image as the fail-safe control when the abnormality detection unit detects an abnormality in the display unit. (Technical Thought 17) The abnormality detection unit further detects an abnormality in a display unit (61) that emits display light (Lvi) that is formed as the virtual image, The virtual image display device according to any one of Technical Ideas 1 to 15, wherein the display control unit continues to display the virtual image even when the abnormality detection unit detects an abnormality in the display unit. [Explanation of symbols]

[0105] Am vehicle, CT content, CT1 first content, CT2 second content, Lvi display light, US up / down direction, VA display area, VP1 normal position (first position), VP2 upper position (second position), Vi virtual image, 61 PGU (display unit), 63 displacement mechanism, 68 operation unit, 71 information acquisition unit (input grasp unit), 72 display control unit, 73 abnormality detection unit, 100 HUD (virtual image display device)

Claims

1. A virtual image display device is used in a vehicle (Am), and projects display light (Lvi) that is formed as a virtual image (Vi) toward a projection range (PA) of a windshield (WS) of the vehicle, thereby displaying the virtual image that is superimposed on a foreground that is visible through the projection range, a displacement mechanism (63) that displaces the position of a display area (VA) in which the virtual image is displayed along the up-down direction (US) of the vehicle; a display control unit (72) that controls the position of the display area according to the content (CT) displayed as the virtual image; an abnormality detection unit (73) that detects at least sticking of the display area as an abnormality in the displacement of the display area; the displacement mechanism switches the position of the display area between a plurality of positions including at least a first position (VP1) and a second position (VP2) above the first position; When the abnormality detection unit detects that the display area has become stuck, the display control unit performs fail-safe control according to the position where the display area has become stuck, and when the display area is stuck at the second position, the display control unit begins responding to the abnormality using the fail-safe control earlier than when the display area is stuck at the first position.

2. The virtual image display device according to claim 1, wherein the display control unit, when the display area is fixed at the second position, performs the fail-safe control of continuing to display the second content (CT2) associated with the second position and ceasing the display of the first content (CT1) associated with the first position.

3. The virtual image display device according to claim 1 , wherein the display control unit performs a return process of the displacement mechanism as the fail-safe control when the display area is fixed at the second position.

4. The display control unit When the display area is stuck at the second position, it is determined whether the content that is predefined as obstructing the driver's view is being displayed; When the content that is preliminarily defined as obstructing the view is being displayed, the display of the second content (CT2) associated with the second position is continued, and the display of the first content (CT1) associated with the first position is stopped; The virtual image display device according to claim 1 , wherein, when the content that is predefined as obstructing visibility is not being displayed, a return process of the displacement mechanism is carried out as the fail-safe control.

5. The virtual image display device according to claim 1 , wherein the display control unit changes the aspect of the content to be displayed as the virtual image as the fail-safe control when the display area is stuck at the second position.

6. A virtual image display device according to any one of claims 1 to 5, wherein the display control unit continues to display the virtual image when the display area becomes fixed at the first position, and performs a return process of the displacement mechanism at a predetermined timing as the fail-safe control.

7. The abnormality detection unit further detects non-smoothness of displacement as an abnormality in the displacement of the display area, A virtual image display device as described in any one of claims 1 to 5, wherein the display control unit continues to display the virtual image when the abnormality detection unit detects the non-smoothness, and performs a return process of the displacement mechanism at a predetermined timing as the fail-safe control.

8. The abnormality detection unit further detects an excessive rise in the display area as an abnormality in the displacement of the display area, The virtual image display device according to any one of claims 1 to 5, wherein the display control unit performs a return process of the displacement mechanism as the fail-safe control at a predetermined timing when the abnormality detection unit detects that the display area has risen too high.

9. The abnormality detection unit further detects an excessive decrease in the display area as an abnormality in the displacement of the display area, The virtual image display device according to any one of claims 1 to 5, wherein the display control unit performs a return process of the displacement mechanism as the fail-safe control at a predetermined timing when the abnormality detection unit detects that the display area has dropped too low.

10. The abnormality detection unit further detects, as the abnormality in the displacement of the display area, an abnormality in which the display area continues to shake in the up and down direction, The display control unit When the abnormality detection unit detects that the display area is continuously shaking, it is determined whether or not the content being displayed is a content that is predefined as obstructing the driver's field of view; When the content that is predefined as obstructing visibility is being displayed, the display of the virtual image is stopped as the fail-safe control; 6. The virtual image display device according to claim 1, wherein, when the content that is predefined as obstructing visibility is not displayed, a return process of the displacement mechanism is performed as the fail-safe control.

11. The abnormality detection unit further detects, as the abnormality in the displacement of the display area, an abnormality in which the display area continues to shake in the up and down direction, The virtual image display device according to any one of claims 1 to 5, wherein the display control unit continues to display the virtual image even when the abnormality detection unit detects that the display area is continuing to shake.

12. the abnormality detection unit further detects, as the abnormality in the displacement of the display area, an abnormality in which a timing for switching the content does not coincide with a timing for displacing the display area; The virtual image display device according to any one of claims 1 to 5, wherein the display control unit continues to display the virtual image even when the abnormality detection unit detects a timing deviation.

13. an input grasping unit (71) that acquires input information to an operation unit (68) that switches the display of the virtual image on and off, 6. The virtual image display device according to claim 1, wherein the display control unit stops displaying the virtual image based on the input information.

14. The abnormality detection unit further detects an abnormality in a display unit (61) that emits display light (Lvi) that is formed as the virtual image, The virtual image display device according to any one of claims 1 to 5, wherein the display control unit stops displaying the virtual image as the fail-safe control when the abnormality detection unit detects an abnormality in the display unit.

15. The abnormality detection unit further detects an abnormality in a display unit (61) that emits display light (Lvi) that is formed as the virtual image, The virtual image display device according to any one of claims 1 to 5, wherein the display control unit continues to display the virtual image even when the abnormality detection unit detects an abnormality in the display unit.

16. A virtual image display device is used in a vehicle (Am), and projects display light (Lvi) that is formed as a virtual image (Vi) toward a projection range (PA) of a windshield (WS) of the vehicle, thereby displaying the virtual image that is superimposed on a foreground that is visible through the projection range, a displacement mechanism (63) that displaces the position of a display area (VA) in which the virtual image is displayed along the up-down direction (US) of the vehicle; a display control unit (72) that controls the position of the display area according to the content (CT) displayed as the virtual image; an abnormality detection unit (73) that detects at least an abnormality in which the display area continues to shake in the up and down direction as an abnormality in the displacement of the display area, The display control unit When the abnormality detection unit detects that the display area is continuously shaking, it is determined whether or not the predetermined content is being displayed to obstruct the driver's view, When the content that is predefined as obstructing the view is being displayed, the display of the virtual image is stopped; A virtual image display device that performs a reset process for the displacement mechanism when the content that is predefined as obstructing visibility is not being displayed.

Images