Virtual image display device and virtual image display method

Abstract

This virtual image display device is provided with a displacement mechanism that switches the position of a display region in which a virtual image is displayed between a plurality of positions including a normal position and an upper position, a display control unit (73) that causes a virtual image of first content of a type to be displayed in the normal position and second content of a type to be displayed in the upper position to be displayed in accordance with the switching of the position of the display region by the displacement mechanism, and an event status identifying unit (74) that identifies the status of a specific event, wherein: the displacement mechanism switches the display region to the upper position if the occurrence of the specific event has been identified and the position of the display region is not the upper position; and, if the occurrence of the specific event has been identified and the position of the display region is not the upper position, the display control unit (73) displays the second content from before the switching of the display region to the upper position is complete.

Description

Virtual image display device and virtual image display method CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application is based on Patent Application No. 2023-184262 filed in Japan on October 26, 2023, and the contents of the original application are incorporated by reference in their entirety.

[0002] The present disclosure relates to a virtual image display device and a virtual image display method that display a virtual image that is visible to a driver of a vehicle.

[0003] Patent Document 1 discloses a virtual image display device equipped with a switching mechanism that moves the angle of view at which a virtual image is displayed. The technology of Patent Document 1 virtually expands the range in which a virtual image can be displayed by moving the angle of view from a normal position to a superimposed position. The technology of Patent Document 1 displays related content that is related to a specific content to be displayed at the superimposed position before the angle of view is completely moved from the normal position to the superimposed position. This technology of Patent Document 1 attempts to reduce the discomfort of the display caused by the time lag until the display starts due to the angle of view being moved by the switching mechanism.

[0004] JP 2022-66149 A

[0005] Depending on the event requiring the display of a virtual image, the content to be displayed at the superimposition position may need to be displayed promptly after the event occurs. In contrast, with the technology of Patent Document 1, the specific content to be displayed at the superimposition position is not displayed until the movement of the angle of view to the superimposition position is completed. Therefore, there is a risk that the content that needs to be displayed promptly after the event occurs cannot be displayed promptly. As a result, there is a risk that the convenience of the virtual image display device may be impaired.

[0006] One object of this disclosure is to provide a virtual image display device and a virtual image display method that are less likely to reduce convenience for the vehicle driver, even when the display area of ​​the virtual image is configured to be switchable.

[0007] In order to achieve the above-mentioned object, the virtual image display device of the present disclosure is a virtual image display device that displays a virtual image that is visible to the driver of a vehicle, and includes a switching mechanism that switches the position of the display area where the virtual image is displayed between a plurality of positions including a first position and a second position, a display control unit that displays virtual images of a first content, which is a type of content to be displayed at the first position, and a second content, which is a type of content to be displayed at the second position, in accordance with the switching of the position of the display area by the switching mechanism, and an event situation identification unit that identifies the situation of a specific event, which is an event that requires the second content to be displayed, and the switching mechanism switches the display area to the second position when the event situation identification unit identifies that a specific event has occurred and the position of the display area is not at the second position, and the display control unit displays the second content before the switching of the display area to the second position by the switching mechanism is completed when the event situation identification unit identifies that a specific event has occurred and the position of the display area is not at the second position.

[0008] In order to achieve the above-mentioned object, the virtual image display method of the present disclosure is a virtual image display method that displays a virtual image that is visible to a driver of a vehicle, and includes a switching process executed by at least one processor for switching the position of a display area in which the virtual image is displayed between a plurality of positions including a first position and a second position; a display control process for displaying virtual images of a first content, which is a type of content to be displayed at the first position, and a second content, which is a type of content to be displayed at the second position, in accordance with the switching of the position of the display area by the switching process; and an event situation identification process for identifying the situation of a specific event, which is an event that requires the display of the second content; in the switching process, if the event situation identification process identifies that a specific event has occurred and the position of the display area is not at the second position, the display area is switched to the second position; and in the display control process, if the event situation identification process identifies that a specific event has occurred and the position of the display area is not at the second position, the second content is displayed before the switching of the display area to the second position in the switching process is completed.

[0009] According to the above configuration, when a specific event requiring the display of the second content occurs and the display area is not at the second position, the second content can be displayed before the switching of the display area to the second position is completed. Therefore, compared to when the second content is displayed after the switching of the display area to the second position is completed, the second content can be displayed more quickly after the specific event occurs. Therefore, content that must be displayed quickly after the event occurs can be displayed more quickly. As a result, even when the display area of ​​the virtual image is configured to be switchable, convenience for the vehicle driver is less likely to be reduced.

[0010] 1 is a diagram for explaining a virtual image display function of a HUD according to an embodiment of the present disclosure. FIG. 1 is a block diagram showing the electrical configuration of a display system. FIG. 2 is a diagram showing the positional relationship between a normal position and an upper position of a display area, together with an example of a virtual image displayed in each display area. FIG. 3 is a flowchart showing details of a display control process performed by a head-up ECU. FIG. 4 is a diagram for explaining an example of a display transition when the display area VA is moved. FIG. 5 is a diagram for explaining an example of a display transition when the display area VA is moved in the case of a first situation type. FIG. 6 is a diagram for explaining an example of a display transition when the display area VA is moved in the case of a second situation type. FIG. 7 is a diagram for explaining an example of a display transition when the display area VA is moved in the case of a third situation type. FIG. 8 is a diagram for explaining an example of a display transition when the display area VA is moved in the case of a fourth situation type. FIG. 9 is a diagram for explaining an example of an automatic braking content displayed in the upper position. FIG. 10 is a diagram for explaining an example of a change in the appearance of the automatic braking content. FIG. 11 is a diagram for explaining an example of a virtual image displayed in the normal position. FIG. 12 is a diagram for explaining an example of a size adjustment applied to a bar-shaped image portion displayed in both the normal position and the upper position. FIG. 13 is a diagram for explaining an example of an inclination adjustment applied to a line-shaped image portion displayed in both the normal position and the upper position. FIG. 1 is a diagram for explaining an example of tilt adjustment applied to a line-shaped image portion displayed in an upper position. FIG. 2 is a diagram showing an example of route guidance content displayed in an upper position. FIG. 3 is a diagram showing an example of route guidance content. FIG. 4 is a diagram showing an example of route guidance content. FIG. 5 is a diagram showing an example of FCTA content displayed in an upper position. FIG. 6 is a diagram showing an example of pedestrian warning content displayed in an upper position.

[0011] A number of embodiments for the purpose of disclosure will be described with reference to the drawings. For the sake of convenience, parts having the same functions as parts shown in the drawings used in the previous explanations in the number of embodiments will be given the same reference numerals, and their description may be omitted. For parts given the same reference numerals, the explanations in other embodiments may be referred to.

[0012] (Embodiment 1) <Schematic Configuration of Display System 1> Hereinafter, a first embodiment of the present disclosure will be described with reference to the drawings. A display system 1 shown in FIGS. 1 and 2 can be used in a vehicle Am. FIG. 1 is a diagram for explaining the virtual image display function of a HUD 100. FIG. 2 is a block diagram showing the electrical configuration of the display system 1. Although a vehicle using the display system 1 is not necessarily limited to an automobile, the following description will be given taking the case where the display system 1 is used in an automobile as an example. The display system 1 includes a meter display device 30 and a head-up display (hereinafter, HUD) 100. The HUD 100 is a virtual image display device that displays a virtual image Vi. The display system 1 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, etc.

[0013] The meter display device 30 and the HUD 100 are communicatively connected to a communication bus of an in-vehicle network installed in 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.

[0014] The navigation ECU 21 is a processing device having a processor, RAM, storage, etc., and performs route guidance to a destination set by the occupant. When the navigation ECU 21 approaches a guidance area that provides guidance on going straight, turning right or left, branching off, merging, etc. during route guidance, the navigation ECU 21 provides route information for the guidance area to the HUD 100 and the meter display device 30.

[0015] The driving assistance ECU 22 is a processing device having a processor, RAM, storage, etc., and realizes a plurality of driving assistance functions that assist the driver of the vehicle A. Examples of the driving assistance functions include Lane Departure Warning (LDW), Adaptive Cruise Control (ACC), Front Cross Traffic Alert (FCTA), Pre-Crash Safety system (PCS), and Proactive Driving Assist (PDA).

[0016] The driving assistance ECU 22 uses the LDW function to determine whether the vehicle has deviated from its own lane, such as protruding from the lane markings Lml and Lmr, based on the detection information of the lane markings acquired from the periphery monitoring sensor. When the driving assistance ECU 23 determines that the vehicle has deviated from its own lane, it provides lane departure information to the HUD 100 and the meter display device 30 and issues a lane departure warning to the driver.

[0017] The driving assistance ECU 22 uses the ACC function to make the vehicle Am travel at a constant speed or follow-up travel. "Constant speed travel" refers to making the vehicle A travel at a constant speed at a target vehicle speed. "Follow-up travel" refers to making the vehicle Am follow the vehicle in front while maintaining a certain distance from the vehicle in front. When the ACC function is operating, the driving assistance ECU 22 provides the HUD 100 and the meter display device 30 with status information indicating the control state of the ACC function.

[0018] The meter display device 30 is one of a plurality of display devices mounted on the vehicle Am. The meter display device 30 presents information to the driver by displaying an image on a display screen. The meter display device 30 corresponds to a combination meter. The meter display device 30 is housed in the instrument panel 9 with its display screen facing the driver's seat. The meter display device 30 includes a meter display 31 and a meter ECU 32.

[0019] The meter display 31 is, for example, a liquid crystal display or an organic EL display. The meter display 31 displays various images on a display screen based on video data acquired from the meter ECU 32. The images displayed on the meter display 31 include, for example, a speedometer image, a tachometer image, a navigation map image, and a driving assistance image.

[0020] 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.

[0021] The HUD 100 is one of multiple display devices mounted on the vehicle Am. The HUD 100 presents information to the driver by forming a virtual image Vi in the space in front of the driver. The HUD 100 is housed in a storage space provided inside the instrument panel 9. The HUD 100 projects light formed as the virtual image Vi toward a projection range PA of the windshield WS. The light formed as the virtual image Vi will be referred to as display light Lvi hereinafter. 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.

[0022] 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 70 .

[0023] 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. The magnifying optical system 62 is a plane mirror, which will be described later. The PGU 61 displays each frame image of the video data on the display surface of the LCD panel and transmits and illuminates the display surface with a backlight. The PGU 61 thereby emits display light Lvi, which is formed as a virtual image Vi, toward the magnifying optical system 62.

[0024] 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.

[0025] The displacement mechanism 63 mechanically moves the area of ​​the windshield WS that becomes the projection range PA. The displacement mechanism 63 corresponds to a switching mechanism. The projection range PA is the range into which the display light Lvi is projected. The projection range PA is the range into which the virtual image Vi appears as seen by the driver. The displacement mechanism 63 includes an actuator 63a, a gear unit, and the like. The displacement mechanism 63 transmits the driving force of the actuator 63a to the housing of the concave mirror 62a via the gear unit. By transmitting the driving force in this manner, the displacement mechanism 63 rotates the concave mirror 62a around a rotation axis defined in the left-right direction Yo. 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 causes the projection range PA of the display light Lvi to move at least in the up-down direction US. Furthermore, by moving the projection range PA in this way, the position of the display area VA visually recognized by the driver also moves at least in the vertical direction US.

[0026] More detailed explanations are provided below. The display area VA is defined based on a virtual line connecting the driver's eye point EP and the outer edge of the imaging surface IS. The imaging surface IS is a virtual range in space in which the virtual image Vi can be formed. The display area VA is the range of the angle of view in which the virtual image Vi is displayed as viewed from the eye point EP. In the HUD 100, the horizontal angle of view in the horizontal direction is larger than the vertical angle of view in the vertical direction. The vertical direction corresponds to the up-down direction US in FIG. 1. The horizontal direction corresponds to the left-right direction Yo in FIG. 1. The vertical angle of view is, for example, approximately 2°. The horizontal angle of view is, for example, approximately 6°.

[0027] The displacement mechanism 63 displaces the position of the display area VA along the up-down direction US of the vehicle Am. This moves the forward range that overlaps with the display area VA in the fore-and-aft direction ZG. The forward range is the range in the foreground. As an example, if the displacement mechanism 63 positions the display area VA downward at a depression angle of about 4°, the range within the display area VA will be approximately 10 to 20 meters forward from the vehicle Am. On the other hand, if the displacement mechanism 63 positions the display area VA upward at a depression angle of about 2°, the range within the display area VA will be approximately 20 to 60 meters forward from the vehicle Am.

[0028] 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 of the vehicle Am. The longitudinal direction of the vehicle Am can also be said to be the traveling direction 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.

[0029] 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.

[0030] The head-up ECU 70 is a control circuit for 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 unit 53, an input / output interface, and a bus connecting these components. In the following description, the computer is assumed to be a microcomputer, for example. The head-up ECU 70 further includes a drive circuit and a detection circuit. The drive circuit is a drive circuit for driving the LCD panel, the backlight, and the actuator 63a. The detection circuit is a detection circuit for acquiring an output signal from the position sensor 64.

[0031] The head-up ECU 70 changes the content CT (see FIG. 3 ) displayed as a virtual image Vi in association with the position of the display area VA. Specifically, the head-up ECU 70 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. The head-up ECU 70 performs this switching in cooperation with the displacement mechanism 63 by controlling the drive of the actuator 63a. The head-up ECU 70 displays a virtual image Vi corresponding to each of the normal position VP1 and the upper position VP2 in response to the switching of the position of the display area VA. FIG. 3 is a diagram showing the positional relationship between the normal position VP1 and the upper position VP2 of the display area VA, along with an example of a virtual image Vi displayed in the display area VA.

[0032] The normal position VP1 is a position of the display area VA where a virtual image Vi is displayed in the driver's peripheral visual field PVF (see FIG. 3). The normal position VP1 corresponds to the first position. The normal position VP1 is defined below the upper position VP2. The normal position VP1 is a 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. In the display area VA at the normal position VP1, content CT indicating vehicle information, such as vehicle speed content CTv (see FIG. 3), is displayed. The vehicle speed content CTv indicates the current vehicle speed of the vehicle Am. The vehicle speed content CTv indicates the current vehicle speed of the vehicle Am in text. In the following description, the content CT corresponding to the normal position VP1 is referred to as the first content CT1 (see FIG. 3). The driver can recognize the virtual image Vi of the first content CT1 displayed in the display area VA at the normal position VP1 when he or she wants to obtain information.

[0033] In addition to the vehicle speed CTv, the information displayed in the first content CT1 also includes shift content. The shift content indicates the current shift position of the vehicle Am. The shift content indicates the current shift position of the vehicle Am using text such as "D" or "R." The information displayed in the first content CT1 may include map-related information such as intersection names. The information displayed in the first content CT1 may also include information indicating vehicle conditions other than the vehicle speed and shift position. The first content CT1 is displayed at a specific position within the projection range PA at the normal position VP1 below the upper position VP2, without specifying a superimposition target. This allows the driver to view the first content CT1 as if it were fixed relatively to vehicle components such as the windshield WS.

[0034] 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 Figure 3). The upper position VP2 corresponds to the second position. 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 is moved from the normal position VP1 to the upper position VP2 when a specific event occurs. A specific event is an event that requires the display of the second content CT2 of the type to be displayed at the upper position VP2. Examples of specific events include approaching a guidance area and activation of a driving assistance function. Approaching the guidance area can be determined by the head-up ECU 70 when the distance between the guidance area and the vehicle Am becomes less than a specified distance.

[0035] Within the display area VA at the upper position VP2, second content CT2 related to a specific event is displayed. The second content CT2 shown as an example in FIG. 3 is route guidance content CTrg. The route guidance content CTrg is a so-called turn-by-turn display. The route guidance content CTrg is second content CT2 related to a specific event, such as approaching a guidance area. Examples of second content CT2 other than the route guidance content CTrg include driving assistance content related to assistance provided by a driving assistance function. The second content CT2 displayed within the display area VA at the upper position VP2 can be recognized by the driver without significantly shifting their gaze from the road ahead. The second content CT2 is displayed at a specific position within the projection range PA at the upper position VP2, which is above the normal position VP1, without specifying a superimposed object. In other words, the second content CT2 is not an AR display object used for augmented reality (AR) display. The AR display object is displayed superimposed on a specific superimposed object within the angle of view VA. The AR display object is movable as seen by the driver, following the specific superimposed object, as if it were fixed relatively to the specific superimposed object.

[0036] 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 above 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.

[0037] The head-up ECU 70 executes a virtual image display program stored in the storage 53 to realize virtual image display control linking the display area VA and the content. The head-up ECU 70 includes a plurality of functional blocks related to this virtual image display control. The functional blocks of the head-up ECU 70 include an information acquisition unit 71, a data storage unit 72, a display control unit 73, and an abnormality detection unit 74. Execution of processing by each functional block of the head-up ECU 70 by a computer corresponds to execution of a vehicle control method.

[0038] The information acquisition unit 71 acquires information related to the virtual image display. The information acquisition unit 71 is connected to the communication bus and the meter ECU 32. The information acquisition unit 71 acquires route information provided by the navigation ECU 21 from the communication bus. The information acquisition unit 71 acquires target information and control status information around the vehicle provided by the driving assistance ECU 22 from the communication bus. Image data for the virtual image display generated by the meter ECU 32 is sequentially input to the information acquisition unit 71.

[0039] The information acquisition unit 71 is electrically connected to the operation unit 68. The operation unit 68 is a switch that allows the driver to adjust the position of the display area VA and switch the display of the virtual image Vi on and off. For example, the operation unit 68 may be a dedicated switch provided on the instrument panel 9. The operation unit 68 may be a steering switch provided on the steering wheel. The operation unit 68 may be a center display having a touch panel function. The operation unit 68 may be a voice input device that detects the driver's speech. When the operation unit 68 is operated by the driver or the like, the information acquisition unit 71 acquires input information input to the operation unit 68. The input information is provided from the information acquisition unit 71 to the display control unit 73, and the position of the display area VA is adjusted and the virtual image display is switched on and off in accordance with the driver's operation.

[0040] The data storage unit 72 is a storage area that stores a plurality of data items referenced by the display control unit 73. The data storage unit 72 may be a storage area secured in the RAM 52, or may be a part of a storage area in the storage 53. In the data storage unit 72, a lookup table, mirror position data, and graphic data are prepared so as to be referenced by the display control unit 73.

[0041] The lookup table contains information linking the display area VA with the content CT. Furthermore, the lookup table stores information linking the type of fault occurring in the HUD 100 with a method for avoiding the fault. The mirror position data for the normal position VP1 is information that defines the angular position of the concave mirror 62a when the display area VA is set to the normal position VP1. The mirror position data for the upper position VP2 is information that defines the angular position of the concave mirror 62a when the display area VA is set to the upper position VP2. Each piece of mirror position data may be a value that can be adjusted by the driver to match the position of the driver's eye point EP. The graphic data for the normal position VP1 is image data used when the display area VA is in the normal position VP1. The graphic data for the upper position VP2 is image data used when the display area VA is in the upper position VP2. The graphic data for the downward transition is image data used when the display area VA is in the process of transitioning toward the normal position VP1. These pieces of image data are called material data.

[0042] The display control unit 73 is a control unit that performs integrated control of the PGU 61 and the actuator 63a. The switching of the position of the display area VA in the displacement mechanism 63 is performed by controlling the actuator 63a of the display control unit 73. Therefore, the process of switching the position of the display area VA in the display control unit 73 corresponds to a switching process. The display control unit 73 generates video data and control signals to be output to the PGU 61, and a drive signal to be output to the actuator 63a. The display control unit 73 selects content CT to be displayed as a virtual image Vi, and controls the position of the display area VA according to the details of the content CT to be displayed. The process of displaying the content CT in the display control unit 73 corresponds to a display control process.

[0043] More specifically, the display control unit 73 references the lookup table in the data storage unit 72 based on the information acquired by the information acquisition unit 71. Then, the display control unit 73 selects the content CT to be virtual image displayed and the position of the display area VA based on the reference result. The display control unit 73 extracts material data of images to be used to generate video data from the RAM 52 or the storage 53 based on the selection result of the content CT. The display control unit 73 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 73 sequentially outputs video data consisting of a large number of consecutive frame images to the PGU 61.

[0044] The display control unit 73 displays virtual images Vi of the first content CT1 to be displayed at the normal position VP1 and the second content CT2 to be displayed at the upper position VP2 in response to switching of the position of the display area VA by the displacement mechanism 63. When switching of the position of the display area VA is performed, the display area VA transitions between the normal position VP1 and the upper position VP2 in response to driving of the actuator 63a. Even during this transition, the display control unit 73 displays the content CT to reduce the sense of discomfort caused by interruptions in the display. Details of switching of the position of the display area VA and switching of the content CT to be displayed by the display control unit 73 will be described later.

[0045] The event status identification unit 74 identifies the status of the specific event. The processing in this event status identification unit 74 corresponds to an event status identification step. Examples of the status of the specific event identified by the event status identification unit 74 include the occurrence of the specific event and the end of the specific event. The event status identification unit 74 identifies the status of the specific event from information acquired by the information acquisition unit 71 from the navigation ECU 21 and the driving assistance ECU 22. Examples are as follows: Approaching a guidance area may be identified as the start of the specific event. Passing through a guidance area may be identified as the end of the specific event. The start of driving assistance by the driving assistance function may be identified as the start of the specific event. The end of driving assistance by the driving assistance function may be identified as the end of the specific event. The event status identification unit 74 may identify the start and end of the specific event for each specific event.

[0046] The situation type identification unit 75 identifies a situation type that is either a situation type of the occurrence of a specific event or a situation type of the end of a specific event. When a specific event is occurring and the display area VA is located at the upper position VP2, the situation type identification unit 75 preferably identifies a first situation type in which a new specific event has occurred, the set priority of which is higher than that of the specific event. A specific event occurring refers to a situation in which the specific event has started but not yet ended, and no new specific event has occurred. Priorities are set in advance for each type of specific event. For example, the higher the urgency of a specific event, the higher the priority may be set. For example, the priority of PCS driving assistance may be set higher than that of approaching a guidance area. In this case, a situation in which approaching a guidance area occurs, the second content CT2 regarding the approaching guidance area is displayed at the upper position VP2, and PCS driving assistance is initiated corresponds to the first situation type.

[0047] It is preferable that the situation type identification unit 75 identify a second situation type in which a specific event has ended while the displacement mechanism 63 is in the process of switching the position of the display area VA to the upper position VP2 due to the occurrence of the specific event. The situation type identification unit 75 may identify that the displacement mechanism 63 is in the process of switching the position of the display area VA to the upper position VP2 by monitoring the actuator 63a.

[0048] It is preferable that the situation type identification unit 75 identifies a third situation type in which a new specific event has occurred while a specific event is occurring and the displacement mechanism 63 is switching the position of the display area VA to the upper position VP2, and the set priority of the new specific event is higher than that of the specific event.

[0049] It is preferable that the situation type identification unit 75 identify a fourth situation type in which a new specific event occurs while the displacement mechanism 63 is switching the position of the display area VA to the lower position VP1 due to the end of a specific event. The situation type identification unit 75 can identify that the displacement mechanism 63 is in the process of switching the position of the display area VA to the lower position VP1 by monitoring the actuator 63a.

[0050] The abnormality detection unit 76 is connected to the PGU 61, the actuator 63a, and the position sensor 64. This allows the abnormality detection unit 76 to detect 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 76 detects abnormalities in the PGU 61, abnormalities in the actuator 63a, and malfunctions of the gear unit. In addition to these, the abnormality detection unit 74 also detects circuit abnormalities in the head-up ECU 70 and software abnormalities in the virtual image display program. When an abnormality in the HUD 100 is detected, the display control unit 73 may display information indicating the abnormality detection and information indicating the type of the detected abnormality. The display control unit 73 may display this information by outputting image data that displays this information as a virtual image to the PGU 61. When an abnormality in the HUD 100 is detected, the display control unit 73 may prevent the HUD 100 from displaying the information. <Display Control Processing>

[0051] Next, an example of a display control process performed by the head-up ECU 70, mainly by the display control unit 73, will be described with reference to the flowchart of FIG. 4. The display control unit 73 may start the display control process when the power supply to the HUD 100 is turned on and the head-up ECU 70 is powered on. The display control process constantly monitors for the occurrence of a fault related to the virtual image display. The display control process is repeatedly performed until the power supply to the head-up ECU 70 is turned off.

[0052] First, in step S101, the display control unit 73 determines whether or not a fault has occurred in the virtual image display based on whether or not abnormality detection information has been acquired from the abnormality detection unit 74. If abnormality detection information has been acquired and it has been determined that a fault has occurred (YES in S101), the process proceeds to step S102. On the other hand, if abnormality detection information has not been acquired from the abnormality detection unit 74 and it has been determined that no fault has occurred (NO in S101), the process proceeds to step S104.

[0053] In step S102, the display control unit 73 determines the type of fault based on the abnormality type information acquired from the abnormality detection unit 74. In step S103, the display control unit 73 selects a fault avoidance method. Specifically, the display control unit 73 selects an avoidance method that is pre-associated with the fault type determined in S102 by referring to the lookup table in the data storage unit 72. Then, the display control unit 73 performs fail-safe display processing in accordance with the selected avoidance method. In the fail-safe display processing, display processing is performed to change the content of the virtual image display so as not to interfere with normal driving by the driver.

[0054] In step S104, the display control unit 73 determines the position of the display area VA to be set as the position where the content CT should be displayed. Specifically, the display control unit 73 selects the content CT to be displayed as a virtual image and the position of the display area VA. The display control unit 73 may make this selection by referring to the lookup table of the data storage unit 72 based on the information acquired by the information acquisition unit 71. If it is determined that the display area VA should be set to the upper position VP2 (YES in S104), the process proceeds to step S108. On the other hand, if it is determined that the display area VA should be set to the normal position VP1 (NO in S104), the process proceeds to step S105.

[0055] In step S105, the display control unit 73 reads mirror position data associated with the normal position VP1 from the data storage unit 72. In step S106, the display control unit 73 reads graphic data associated with the normal position VP1 from the data storage unit 72. In step S107, the display control unit 73 displays the virtual image Vi of the content CT, whose display was determined in step S104, in the display area VA of the normal position VP1. Then, the process returns to step S101 and repeats.

[0056] Meanwhile, in step S108, the display control unit 73 reads mirror position data associated with the upper position VP2 from the data storage unit 72. In step S109, the display control unit 73 reads graphic data associated with the upper position VP2 from the data storage unit 72. In step S110, the display control unit 73 displays the virtual image Vi of the content CT, whose display was determined in S104, in the display area VA of the upper position VP2. Then, the process returns to S101 and repeats.

[0057] <Display Switching Timing> When the event status identification unit 74 identifies that a specific event has occurred, the display control unit 73 displays the second content CT2 in the upper position VP2. However, if the display area VA is not in the upper position VP2, the second content CT2 cannot be displayed in the upper position VP2 the moment it is identified that a specific event has occurred. It takes time to move the display area VA to the upper position VP2 after it is identified that a specific event has occurred. This is described in more detail below.

[0058] First, there is the processing time (hereinafter referred to as M processing time) in the microcomputer of the head-up ECU 70. The M processing time is the time required to select the content CT to be displayed as a virtual image and the position of the display area VA. Next, there is the time required for communication between the head-up ECU 70 and the displacement mechanism 63 (hereinafter referred to as communication time). This communication time is the time required for the head-up ECU 70 to transmit to the displacement mechanism 63 an instruction to drive and control the actuator 63a to the position of the display area VA selected by the head-up ECU 70. There is also the time required for the displacement mechanism 63 to control the actuator 63a (hereinafter referred to as actuation control time). The actuation control time is the time required from when the displacement mechanism 63 receives an instruction to drive and control the actuator 63a to when it starts driving the actuator 63a. Finally, there is the time required for the actuator 63a to operate (hereinafter referred to as actuation time). The actuation time is the time required for the actuator 63a to move the display area VA to the specified position of the display area VA. The M processing time, communication time, active control time, and active operation time are hereinafter collectively referred to as delay time.

[0059] If the occurrence of a specific event is identified and then the display area VA is moved to the upper position VP2 before the second content CT2 is displayed, the following problem occurs. Specifically, due to the delay time described above, there is a time gap between the occurrence of the specific event and the display of the second content CT2. This may result in the content that needs to be displayed promptly after the event occurrence not being displayed promptly.

[0060] In response to this, when the event status identification unit 74 identifies that a specific event has occurred and the position of the display area VA is not at the upper position VP2, the display control unit 73 performs the following operation: The display control unit 73 instructs the displacement mechanism 63 to switch the display area VA to the upper position VP2. Furthermore, the display control unit 73 displays the second content CT2 even before the displacement mechanism 63 has completed switching of the display area VA to the upper position VP2 (see FIG. 5 ).

[0061] FIG. 5 is a diagram illustrating an example of a display transition when the display area VA is moved. CTT in the diagram indicates the transition content. CT1 in the diagram indicates the first content CT1. CT2 in the diagram indicates the second content CT2. As an example, the transition content is a combination of vehicle speed content CTv and shift content. The transition content is content that includes at least a portion of the first content CT1. The first content is as described above. As an example, the second content CT2 is the driving assistance content or route guidance content CTg plus the vehicle speed content CTv and shift content. ES in the diagram indicates the start timing of a specific event. EE in the diagram indicates the end timing of a specific event. P in the diagram indicates the M processing time. C in the diagram indicates the communication time. SR in the diagram indicates the timing at which the displacement mechanism 63 receives an instruction from the head-up ECU 70. MC in the diagram indicates the activation control time. MB in the diagram indicates the activation operation time. The same applies to the subsequent diagrams.

[0062] According to the above configuration, the second content CT2 can be displayed more quickly after a specific event occurs. Therefore, content that must be displayed quickly after an event occurs can be displayed more quickly. As a result, even if the virtual image display area VA is configured to be switchable, convenience for the driver of the vehicle Am is less likely to be reduced. As shown in the example of FIG. 5 , the aforementioned delay time is required from the occurrence of a specific event until the display area VA is switched to the upper position VP2. It takes at least M processing time to elapse from the occurrence of a specific event until the second content CT2 for that specific event is selected as the display content. Therefore, when a specific event occurs, the display control unit 73 may display the second content CT2, for example, immediately after the M processing time has elapsed. This allows the second content CT2 to be displayed before the switching of the display area VA to the upper position VP2 is completed.

[0063] When the event status identification unit 74 identifies that a specific event has occurred and the position of the display area VA is the normal position VP1, the display control unit 73 preferably performs the following operation. The display control unit 73 instructs the displacement mechanism 63 to switch the display area VA from the normal position VP1 to the upper position VP2. The display control unit 73 may display the second content CT2 from the timing when the display area VA is located at the normal position VP1, before the displacement mechanism 63 completes switching of the display area VA from the normal position VP1 to the upper position VP2 (see FIG. 5 ). For example, as described above, the second content CT2 may be displayed immediately after the M processing time has elapsed when the occurrence of a specific event has been identified.

[0064] According to the above configuration, when a specific event occurs, it is possible to display the second content CT2 from the timing when the display area VA is located at the normal position VP1. Therefore, even when the display area VA is located at the normal position VP1, it is possible to more quickly display content that must be displayed promptly after the occurrence of an event.

[0065] Furthermore, when the event status determination unit 74 determines that all specific events have ended, the display control unit 73 displays the first content CT1 at the normal position VP1. However, the first content CT1 cannot be displayed at the normal position VP1 the instant it is determined that the specific event has ended. After determining that the specific event has ended, moving the display area VA to the normal position VP1 also requires the aforementioned M processing time, communication time, activation control time, and activation operation time.

[0066] To display the first content CT1 after the specific event ends, it is necessary to terminate the display of the second content CT2. If it is determined that all specific events have ended, and then the display area VA is moved to the normal position VP1, and then the display of the second content CT2 is terminated, the following problem occurs. Specifically, due to the aforementioned delay time, there is a time gap between the occurrence of the specific event and the termination of the display of the second content CT2. As a result, even though the event has ended, the content for that event may not be terminated promptly. As a result, the driver may feel uncomfortable, and the convenience for the driver may be reduced.

[0067] In response to this, when the event status identification unit 74 has identified the ends of all specific events whose starts have been identified, the display control unit 73 may do the following: The display control unit 73 instructs the displacement mechanism 63 to switch the display area VA to the normal position VP1. Furthermore, the display control unit 73 may end the display of the second content CT2 and display the transition content before the displacement mechanism 63 has completed switching of the display area VA to the normal position VP1 (see FIG. 5 ). The display control unit 73 may display the first content CT1 after the display area VA has switched to the normal position VP1, as shown in FIG. 5 .

[0068] According to the above configuration, it is possible to more quickly terminate the display of the second content CT2 after all specific events have ended. Therefore, it is possible to more quickly terminate the display of content for completed events. As a result, even if the virtual image display area VA is configured to be switchable, convenience for the driver of the vehicle Am is less likely to be reduced. As shown in the example of FIG. 5 , the aforementioned delay time is required from the end of a specific event until the display area VA is switched to the normal position VP1. It takes at least M processing time to elapse from the end of a specific event until the transition content CTT is selected as the display content. Therefore, when a specific event has ended, the display control unit 73 may display the transition content CTT, for example, immediately after the M processing time has elapsed. This allows the display of the second content CT2 to be terminated and the transition content CTT to be displayed before the display area VA has been switched to the normal position VP1.

[0069] When the event status identification unit 74 has identified the ends of all specific events whose starts have been identified, and the position of the display area VA is at the upper position VP2, the display control unit 73 preferably performs the following operation. The display control unit 73 instructs the displacement mechanism 63 to switch the display area VA from the upper position VP2 to the normal position VP1. The display control unit 73 may terminate the display of the second content CT2 and display the transition content from the timing when the display area VA is at the upper position VP2, before the displacement mechanism 63 has completed switching the display area VA from the upper position VP2 to the normal position VP1.

[0070] With the above configuration, when all specific events have ended, it is possible to end the display of the second content CT2 from the timing when the display area VA is located at the upper position VP2. Therefore, even when the display area VA is located at the upper position VP2, it is possible to more quickly end the display of the content for the ended event.

[0071] <Transition of display area and displayed content according to type of situation>

[0072] Depending on the situation of an event requiring the display of a virtual image, the timing of the transition of the display area and the displayed content may differ in order to notify the driver of information without causing discomfort. In contrast, Patent Document 1 does not anticipate varying the timing of the transition of the display area and the displayed content depending on the situation of the event. Therefore, the technology of Patent Document 1 may cause the transition of the display area and the displayed content to be performed in a way that causes discomfort to the driver depending on the situation of the event. As a result, there is a risk that convenience for the occupants may be impaired.

[0073] In response to this, it is preferable that the display control unit 73 perform the following processing at a timing according to the situation type identified by the situation type identification unit 75. The display control unit 73 instructs the displacement mechanism 63 to switch the display area VA at a timing according to the identified situation type. The display control unit 73 switches the content CT to be displayed at a timing according to the identified situation type.

[0074] According to the above configuration, the display area and the displayed content can be transitioned depending on the situation of an event that requires the display of a virtual image, so that the driver is notified of information without feeling uncomfortable. As a result, even if the display area VA of the virtual image is configured to be switchable, convenience for the driver of the vehicle Am is further unlikely to be reduced.

[0075] An example of the transition of the display area VA and the displayed content CT according to the type of situation will be described below using Figures 6 to 9. Figures 6 to 9 are diagrams for explaining an example of the display transition when the display area VA is moved according to the type of situation. Among the symbols in Figures 6 to 9, the symbols that are the same as those in Figure 5 are the same as those described above, and their explanation will be omitted.

[0076] When the situation type identification unit 75 identifies the first situation type, the display control unit 73 preferably performs the following operation. The first situation type is a situation in which a specific event is occurring, the display area VA is located at the upper position VP2, and a new specific event occurs whose set priority is higher than that of the specific event. This new specific event is hereinafter referred to as a priority new event. The display control unit 73 simply maintains the position of the display area VA at the upper position VP2 without temporarily switching it from the upper position VP2 to the normal position VP1 (see FIG. 6 ). In this case, since the display control unit 73 maintains the display area VA at the upper position VP2, there is no need to issue a new instruction to the displacement mechanism 63. The display control unit 73 simply starts displaying the second content CT2 for the priority new event from the timing when the situation type identification unit 75 identifies the first situation type. This allows the second content CT2 for the priority new event to be displayed (see FIG. 6 ). Here, the start of display of the second content CT2 refers to the timing when a display instruction is issued from the HUD 70, which is the timing before the second content CT2 is actually displayed. HNES in FIG. 6 indicates the timing when the priority new event starts. CTN in FIG. 6 indicates the second content CT2 for the priority new event. Hereinafter, the second content CT2 for the priority new event will be referred to as new content CTN.

[0077] According to the above configuration, even if a priority new event occurs during the occurrence of a specific event, it is not necessary to end the specific event and temporarily switch the position of the display area VA from the upper position VP2 to the normal position VP1. Therefore, the time from the occurrence of the priority new event to the display of the new content CTN can be shortened accordingly. Furthermore, it is possible to start displaying the new content CTN from the timing at which it is determined that the priority new event has occurred. Therefore, it is possible to display the new content CTN more quickly without waiting for the end of the previous event. Therefore, the display of the new content CTN in response to the occurrence of the priority new event is less likely to cause discomfort to the driver. As a result, even if the virtual image display area VA is configured to be switchable, it is less likely that the convenience for the driver of the vehicle Am will be reduced. As shown in the example of FIG. 6 , when a priority new event occurs during the occurrence of a specific event, it is sufficient to display the new content CTN immediately after the M processing time for the priority new event has elapsed. This makes it possible to display the new content CTN more quickly without waiting for the end of the previous event.

[0078] When the situation type identification unit 75 identifies the second situation type, the display control unit 73 preferably performs the following operation. The second situation type is a situation in which a specific event ends while the displacement mechanism 63 is switching the position of the display area VA to the upper position VP2 due to the occurrence of the specific event. The display control unit 73 instructs the displacement mechanism 63 to switch the position of the display area VA to the normal position VP1 even if the position has not yet been switched to the upper position VP2 (see FIG. 7 ). In the example of FIG. 7 , the position of the display area VA is switched to the normal position VP1 without reaching the upper position VP2. The display control unit 73 may start terminating the display of the second content CT2 from the timing when the situation type identification unit 75 identifies the second situation type. This may terminate the display of the second content CT2. Then, the display of the transition content CTT may be started to be displayed (see FIG. 7 ). Here, the start of the end of the display of the second content CT2 refers to the timing when an instruction to switch the display is given from the HUD 70, which is a timing before the display of the second content CT2 actually ends. Furthermore, the start of the display of the transition content CTT refers to the timing when an instruction to display is given from the HUD 70, which is a timing before the transition content CTT is actually displayed. Furthermore, after the position of the display area VA reaches the normal position VP1, the display control unit 73 may display the first content CT1.

[0079] According to the above configuration, if a specific event ends while the position of the display area VA is being switched to the upper position VP2, it is no longer necessary to temporarily move the position of the display area VA to the upper position VP2. Therefore, unnecessary movement of the display area VA can be minimized. Therefore, it is possible to prevent the driver from feeling uncomfortable due to unnecessary movement of the display area VA. Furthermore, it is possible to start displaying the transition content CTT even if the position of the display area VA has not yet reached the upper position VP2. Therefore, it is possible to switch the display to the transition content CTT more quickly compared to waiting for the position of the display area VA to reach the upper position VP2 before switching to displaying the transition content CTT. Therefore, it is possible to more quickly end the display of content for a completed event. As a result, even if the virtual image display area VA is configured to be switchable, convenience for the driver of the vehicle Am is further unlikely to be reduced. 7, if a specific event ends while the display area VA is being switched to the upper position VP2, the transition content CTT can be displayed immediately after the M processing time for the end of the specific event has elapsed. This makes it possible to quickly end the display of the second content CT2 after the specific event ends, and to more quickly display the new content CTN.

[0080] When the situation type identification unit 75 identifies the third situation type, the display control unit 73 preferably performs the following operation. The third situation type is a situation in which a specific event is occurring and a priority new event occurs while the displacement mechanism 63 is switching the position of the display area VA to the upper position VP2. The display control unit 73 instructs the displacement mechanism 63 to continue switching the position of the display area VA to the upper position VP2 without temporarily switching it from the upper position VP2 to the normal position VP1 (see FIG. 8 ). The display control unit 73 may start displaying the new content CTN from the timing when the situation type identification unit 75 identifies the third situation type. This allows the new content CTN to be displayed (see FIG. 8 ). The start of displaying the new content CTN here refers to the timing when a display instruction is issued from the HUD 70, which is a timing before the new content CTN is actually displayed. In the example of FIG. 8, new content CTN is displayed before the display area VA reaches the upper position VP2, without waiting for the second content CT2 for the immediately preceding specific event to be displayed at the upper position VP2.

[0081] According to the above configuration, if a priority new event occurs while the position of the display area VA is being switched to the upper position VP2 due to the occurrence of a specific event, it is not necessary to end the specific event and temporarily switch the position of the display area VA from the upper position VP2 to the normal position VP1. Therefore, the time from the occurrence of the priority new event to the display of the new content CTN can be shortened accordingly. As a result, even if the virtual image display area VA is configured to be switchable, convenience for the driver of the vehicle Am is further reduced. As shown in the example in FIG. 8 , if a priority new event occurs during the occurrence of a specific event, the new content CTN can be displayed immediately after the M processing time for the priority new event has elapsed. This can be performed even if the display area VA is moving to the upper position VP2. This makes it possible to display the new content CTN more quickly without waiting for the end of the previous event.

[0082] When the situation type identification unit 75 identifies the fourth situation type, the display control unit 73 preferably performs the following operation. The fourth situation type is a situation in which a new specific event occurs while the displacement mechanism 63 is switching the position of the display area VA to the lower position VP1 due to the end of a specific event. The display control unit 73 instructs the displacement mechanism 63 to switch the position of the display area VA to the upper position VP2 even if the position has not yet been switched to the normal position VP1 (see FIG. 9 ). In the example of FIG. 9 , the position of the display area VA is switched to the upper position VP2 without reaching the normal position VP1. Note that, depending on the delay time, the position of the display area VA may be switched to the upper position VP2 after reaching the normal position VP1. The display control unit 73 may start displaying the second content CT2 for the new specific event from the timing when the situation type identification unit 75 identifies the fourth situation type. This allows the second content CT2 for the new specific event to be displayed (see FIG. 9 ). 9 indicates the start timing of a new specific event. When the fourth situation type is identified, the display control unit 73 may display the second content CT2 for the new specific event even when the display area VA is in the normal position VP1.

[0083] According to the above configuration, when a new specific event occurs while the position of the display area VA is being switched to the normal position VP1 due to the end of a specific event, it is not necessary to temporarily move the position of the display area VA to the normal position VP1. Therefore, unnecessary movement of the display area VA can be minimized. Therefore, it is possible to prevent the driver from feeling uncomfortable due to unnecessary movement of the display area VA. Furthermore, even if the position of the display area VA has not yet reached the upper position VP2, it is possible to quickly start displaying the second content CT2 for the new specific event. Therefore, it is possible to switch the display to the second content CT2 more quickly than if the display area VA were to reach the upper position VP2 and then switch to the display of the second content CT2. As a result, even if the display area VA of the virtual image is configured to be switchable, convenience for the driver of the vehicle Am is further unlikely to be reduced. 9, if a new specific event ends while the position of the display area VA is being switched to the normal position VP1 due to the end of a specific event, the second content CT2 can be displayed immediately after the M processing time for the new specific event has elapsed. This allows the second content CT2 to be displayed promptly after the start of the new specific event, thereby enabling the second content CT2 to be displayed more quickly. <Aspect Rules>

[0084] When the display area of ​​the virtual image is configured to be switchable, display problems such as display annoyance or distraction specific to switching the display area may occur. When such problems occur, convenience for the occupants may be impaired. Therefore, when the display area of ​​the image is configured to be switchable, it is required to reduce the display annoyance or distraction specific to switching the display area.

[0085] Therefore, in the above-described display control process, if the position of the selected display area VA is not the normal position VP1, it is preferable to display the virtual image Vi to which the aspect rule is applied. The aspect rule is a rule linked to at least one of the type of content CT and the position of the display area VA. The cases where the position of the display area VA is not the normal position VP1 include the case where the display area VA is at the upper position VP2 or the case where the display area VA is moving.

[0086] By applying the aspect rules to the virtual image Vi, the display control unit 73 can display the content CT in an expression method that is less bothersome or eye-catching. In this embodiment, it is assumed that lookup tables and graphic data corresponding to multiple pre-set aspect rules are prepared in the data storage unit 72. The display control unit 73 can display the virtual image Vi to which the aspect rules have been appropriately applied by referring to the lookup tables and graphic data. Details of the multiple types of aspect rules used in this embodiment will be explained in order below. Note that multiple aspect rules may be applied in combination, or only some of the aspect rules may be applied. When combining multiple aspect rules, combinations that result in mutually contradictory aspects may be excluded.

[0087] <First Aspect Rule> The first aspect rule is a aspect rule associated with the upper position VP2. The first aspect rule is applied to the virtual image Vi displayed at the upper position VP2. By applying the first aspect rule, the aspect of the virtual image Vi displayed at the upper position VP2 is more limited than the aspect of the virtual image Vi displayed at the normal position VP1. As a result, the virtual image Vi displayed at the upper position VP2 is less likely to be a distraction to the driver.

[0088] [Limitation of Character Information] The display control unit 73 applies the first aspect rule to the character information MJ (see FIG. 10 ) displayed at the upper position VP2. The character information MJ includes an image portion that changes in real time to indicate vehicle speed, street name, etc., as well as an image portion that notifies the user of an application that is currently running. By applying the first aspect rule, the character information MJ displayed at the upper position VP2 is limited in at least one of the number of characters and the character size compared to the character information MJ displayed at the normal position VP1. The display control unit 73 of this embodiment limits both the number of characters and the character size of the character information MJ at the upper position VP2. As a result, the amount of information in the character information MJ at the upper position VP2 is reduced compared to the amount at the normal position VP1. The amount of information can also be referred to as volume.

[0089] Specifically, no limit is set on the number of characters for the character information MJ displayed at the normal position VP1. On the other hand, a limit is applied to the number of characters for the character information MJ displayed at the upper position VP2, such as a limit of less than 10 characters or the number of characters that can be written in one line. Furthermore, for example, only a minimum character size limit is set for the character information MJ displayed at the normal position VP1. On the other hand, both a minimum and maximum character size limit are set for the character information MJ displayed at the upper position VP2. The minimum character size limit at the upper position VP2 is set larger than the minimum character size limit at the normal position VP1. The maximum character size limit is determined, for example, by the ratio of the vertical and horizontal sizes of the display area VA. Furthermore, the spacing between characters at the upper position VP2 is ensured to be wider than at the normal position VP1.

[0090] According to the above configuration, the number of characters and / or the character size of the character information MJ is limited compared to when the character information MJ is displayed at the normal position VP1, which prevents the character information MJ, which takes time to read, from being displayed near the central visual field CVF and causing a distraction.

[0091] [Restrictions on Filled Background] The display control unit 73 applies the first aspect rule to the filled background NH (see FIG. 10 ) displayed at the upper position VP2. The text information MJ is displayed superimposed on the filled background NH. The filled background NH is an image portion that emphasizes the text information MJ and is drawn in a display color different from that of the text information MJ. As an example, the filled background NH is a chromatic, high-brightness display color. In this case, the display color may be, for example, red. On the other hand, the text information MJ is an achromatic, high-brightness display color. In this case, the display color may be, for example, white.

[0092] When the display control unit 73 displays the text information MJ overlaid on the filled-in background NH at the upper position VP2, it emphasizes the outlines Ri of the characters included in the text information MJ by outlining them in a color different from that of the filled-in background NH. The outlines Ri are, for example, achromatic and low-brightness display colors. The outlines Ri create a visual effect that enhances the contrast between the light and dark between the filled-in background NH and the text information MJ. As a result, the readability of the text information MJ can be improved.

[0093] The display control unit 73 applies the first aspect rule to the filled-in background NH displayed at the upper position VP2 to limit the duration of the display of the filled-in background NH (see FIG. 11 ). Specifically, the display control unit 73 limits the duration of the display of the filled-in background NH to a very short time. This time may be, for example, approximately 0.1 seconds. The display control unit 73 prompts the driver's attention by displaying the filled-in background NH for a short period of time. Thereafter, the display control unit 73 terminates the display of the filled-in background NH so as not to obstruct the driver's field of vision with a wide range of the filled-in background NH. While continuing to display the text information MJ, the display control unit 73 displays frame-shaped images WK (see the lower part of FIG. 11 ) on both the left and right sides of the text information MJ in place of the filled-in background NH. The frame-shaped images WK are drawn in a linear form in the same display color as the filled-in background NH so as not to obstruct the driver's forward field of vision.

[0094] According to the above configuration, the display duration of the filled-in background NH is limited. Therefore, it is less likely that a wide area will be filled in and block the driver's field of vision for a long period of time. Furthermore, by providing the outline Ri as described above, the readability of the character information MJ is improved. As a result, even if the character information MJ is displayed near the central visual field CVF, it is less likely to be excessively eye-catching.

[0095] <Second Aspect Rule> The second aspect rule is a aspect rule associated with the moving display area VA. The second aspect rule is applied to the virtual image Vi when the displacement mechanism 63 moves the display area VA from the normal position VP1 to the upper position VP2. Application of the second aspect rule suppresses the appearance of an eye-catching image while the display area VA is moving and the optical illusion before and after the movement of the display area VA.

[0096] [Display Restriction During Movement] When the displacement mechanism 63 moves the display area VA from the normal position VP1 to the upper position VP2, the display control unit 73 applies the second aspect rule to do the following: The display control unit 73 hides the virtual image Vi that was displayed at the normal position VP1 before the movement of the display area VA begins. As an example, if the vehicle speed CTv and the route guidance content CTrg are displayed at the normal position VP1 as the first content CT1, the display control unit 73 does the following: After hiding these virtual images Vi, the display control unit 73 starts moving the display area VA by the displacement mechanism 63 (see FIG. 12 ). After the display area VA moves to the upper position VP2, the display control unit 73 re-displays the vehicle speed CTv and the route guidance content CTrg.

[0097] The display control unit 73 may do the same when the displacement mechanism 63 moves the display area VA from the upper position VP2 to the normal position VP1. That is, the display control unit 73 may hide the virtual image Vi that was displayed at the upper position VP2 before the display area VA starts to move. In this case, the display control unit 73 also re-displays the content CT that was once hidden after the display area VA moves to the normal position VP1. With the above configuration, the virtual image Vi displayed when the display area VA moves is less likely to attract the driver's attention and cause discomfort.

[0098] [Size Adjustment in the Perspective Direction] When displaying content CT that is common before and after movement from the normal position VP1 to the upper position VP2, the display control unit 73 applies the second aspect rule as follows. The display control unit 73 adjusts the display size of the virtual image Vi so that the relationship with the vanishing point VNP in the foreground is maintained. As an example, if the first content CT1 including a bar-shaped image portion Phb extending along the horizontal direction is displayed at the normal position VP1, the display control unit 73 may perform the following. The display control unit 73 may reduce the bar-shaped image portion Phb in the perspective direction and display it at the upper position VP2 (see FIG. 13 ). The bar-shaped image portion Phb is included in the content CT indicating, for example, the operation of the ACC, and is displayed as an image portion indicating a vehicle ahead. The horizontal direction corresponds to the left-right direction Yo in FIG. 13 .

[0099] If a bar-shaped image portion Phb with the same display size as that at the normal position VP1 were displayed at the upper position VP2, the bar-shaped image portion Phb would appear enlarged relative to the foreground. This display mode of the bar-shaped image portion Phb could cause unintended emphasis of the foreground. Therefore, the display control unit 73 adjusts the size of the bar-shaped image portion Phb displayed at the upper position VP2 to be smaller, in accordance with the perspective reference lines PL that converge at the vanishing point VNP. This adjustment of the display size avoids unintended emphasis due to the Ponzi illusion.

[0100] [Tilt Adjustment Taking Vanishing Point into Account] The display control unit 73 applies the second aspect rule to the line-shaped image portion PbL extending toward the vanishing point VNP in the foreground. This second rule is applied when displaying the content CT including the line-shaped image portion PbL before and after movement from the normal position VP1 to the upper position VP2. The display control unit 73 adjusts the tilt of the line-shaped image portion PbL so that the orientation toward the vanishing point VNP is maintained (see FIG. 14). As an example, the line-shaped image portion PbL is an image portion that emphasizes the lane markings of the vehicle in each of the first content CT1 and the second content CT2 (see also FIG. 21).

[0101] The display control unit 73 adjusts the inclination of the line-shaped image portion PbL according to the position of the display area VA, in accordance with the perspective reference lines PL that converge at the vanishing point VNP. As a result, the line-shaped image portion PbL of the first content CT1 is displayed in a more vertical orientation than the line-shaped image portion PbL of the second content CT2. In other words, the line-shaped image portion PbL of the second content CT2 is displayed in a more horizontal orientation than the line-shaped image portion PbL of the first content CT1. This makes it less likely that a situation will occur where the orientation of the line-shaped image portion PbL is misaligned with respect to a dividing line or the like in the foreground, causing a sense of incongruity.

[0102] 13 and 14 are virtual lines used for explanation purposes and are not actually displayed. Furthermore, size adjustment in the perspective direction and tilt adjustment taking into account the vanishing point VNP are aspect rules that are linked to the type of content CT as well as the position of the display area VA.

[0103] <Third Aspect Rule> The third aspect rule is a aspect rule linked to both the type of content CT and the position of the display area VA. The third aspect rule is applied to the second content CT2 displayed in the display area VA at the upper position VP2. The third aspect rule is a rule that ensures that the second content CT2 does not point to a specific object in the foreground. As described above, the second content CT2 of this embodiment is not an AR display object and does not specify a superimposed object. Therefore, if the second content CT2 is configured to point to a specific object in the foreground, there is a risk that the driver will misinterpret it. The third aspect rule prevents such misinterpretation by the driver.

[0104] When displaying the second content CT2 at the upper position VP2, the display control unit 73 may apply the third aspect rule as follows. The display control unit 73 may avoid, for example, displaying the second content CT2 superimposed on a specific object in the foreground. An example of the specific object is a lane marking. As an example, a case will be described in which the content CT indicating the operation of the LDW is displayed as the second content CT2 including the line-shaped image portion PbL (see FIG. 15 ). In this case, the display control unit 73 superimposes the line-shaped image portion PbL inside the lane marking in the foreground so that the line-shaped image portion PbL does not overlap with the lane marking. This prevents the lane marking from drawing excessive attention and from motivating the driver to unintentionally align the line-shaped image portion PbL with the lane marking.

[0105] The following is an example of a manner for suppressing the driver's motivation to align the linear image portion PbL with the lane marking. For example, as shown in Fig. 15, the inclination of the linear image portion PbL may be set to a value that does not match the inclination of the lane marking. This also makes it possible to suppress the driver's motivation to align the linear image portion PbL with the lane marking.

[0106] <Fourth Aspect Rule> The fourth aspect rule is a aspect rule that is linked to both the type of content CT and the position of the display area VA. The fourth aspect rule aims to reduce the cognitive load of the content CT and shorten the time required for the driver to recognize, judge, and operate. The fourth aspect rule is applied to a specific type of content CT that is displayed in the display area VA at the upper position VP2. By applying the fourth aspect rule, the virtual image Vi is displayed in an expression that takes into consideration correct perception, intuitive understanding, and understanding of the relationship with outside-vehicle information.

[0107] [Automatic Braking Content] When displaying the automatic braking content CTpc shown in Figures 10 and 11 at the upper position VP2, the display control unit 73 applies the fourth aspect rule. The fourth aspect rule is applied to the automatic braking content CTpc. The automatic braking content CTpc is content CT that notifies the driver of the activation of the PCS by the driving assistance ECU 22 (see Figure 2). PCS may also be referred to as Autonomous Emergency Braking. The display control unit 73 displays a virtual image Vi formed by superimposing text information MJ of "BRAKE" on a solid background NH as the automatic braking content CTpc in the display area VA at the upper position VP2.

[0108] The display control unit 73 applies a fourth rule including the first rule to the automatic braking content CTpc. Specifically, when displaying the automatic braking content CTpc, the display control unit 73 applies visual effects such as blinking and enlargement to the virtual image Vi (see the upper part of FIG. 11). This is to allow the driver to quickly notice the warning.

[0109] In addition, the display control unit 73 adds a dark outline Ri to each character of the character information MJ and limits the number and size of characters in the character information MJ, thereby improving readability of the character information MJ (see the middle rows of FIGS. 10 and 11). After alerting the driver to the problem, the display control unit 73 performs the following steps to avoid blocking the driver's forward visibility: The display control unit 73 ends the display of the solid background NH and switches to the display of a frame-shaped image WK (see the bottom row of FIG. 11).

[0110] [Route Guidance Content] When displaying the route guidance content CTrg shown in Figures 16 to 19 at the upper position VP2, the display control unit 73 applies the fourth aspect rule to the route guidance content CTrg. The route guidance content CTrg is a so-called turn-by-turn display. The route guidance content CTrg is displayed based on route information provided by the navigation ECU 21 and is used for route guidance at guidance points. Specifically, the route guidance content CTrg guides the driver to the locations of destinations and intermediate points, directions to turn right or left, branching points and merging points, etc.

[0111] The route guidance content CTrg displayed in the upper position VP2 is composed of an arrow image portion PgA, a road surface marking portion Prm, a remaining distance meter Pdm, etc. The arrow image portion PgA includes a plurality of arrow-shaped image elements arranged in the left-right direction Yo. The arrow image portion PgA indicates the traveling direction of the vehicle at the guidance point using each image element. An example of a guidance point is an intersection. In the example of FIG. 16 , the traveling direction of the vehicle is to the right. The road surface marking portion Prm is located below the arrow image portion PgA. The road surface marking portion Prm is drawn in an L-shape and is superimposed on the road surface ahead to guide the vehicle along the planned route at the guidance point. In the example of FIG. 16 , the planned route is a right turn. The remaining distance meter Pdm indicates the remaining distance to the guidance point as a numerical value based on route information.

[0112] The display control unit 73 moves the display area VA from the normal position VP1 (see FIG. 12) to the upper position VP2 just before the remaining distance to the guidance point becomes approximately 100 m. If the route guidance content CTrg (see FIG. 12) is displayed at the normal position VP1, the display control unit 73 performs the following. In accordance with the first aspect rule, the display control unit 73 hides the route guidance content CTrg before the display area VA starts to move. The display control unit 73 may fade out the route guidance content CTrg toward the guidance point. The route guidance content CTrg may also fade out toward the vanishing point VNP as shown in FIG. 13.

[0113] The display control unit 73 displays the route guidance content CTrg in the display area VA moved to the upper position VP2 (see the upper part of Figure 16). The display control unit 73 applies the fourth aspect rule to the route guidance content CTrg as follows: The display control unit 73 limits changes in the aspect of the route guidance content CTrg until the remaining distance from vehicle Am to the guidance point becomes less than a predetermined value. As an example, the display control unit 73 fixes the aspect of the route guidance content CTrg until the remaining distance becomes less than 50 meters. Then, when the remaining distance becomes less than 50 meters, the display control unit 73 changes the aspect of the route guidance content CTrg depending on the remaining distance from vehicle Am to the guidance point.

[0114] The display control unit 73 fixes the value of the remaining distance meter Pdm at the initial value of "100 m" until the remaining distance becomes less than 50 m. Then, when the remaining distance becomes 50 m, the display control unit 73 changes the value of the remaining distance meter Pdm from "100 m" to "50 m" (see the lower part of FIG. 16). After this, the display control unit 73 continuously decreases the value of the remaining distance meter Pdm until the vehicle Am reaches the guidance point (see FIGS. 17 and 18). Then, after the vehicle Am arrives at the guidance point, the display control unit 73 continues to display the remaining distance meter Pdm showing the value of "0 m" until the route guidance ends (see FIG. 19).

[0115] Furthermore, the display control unit 73 does not change the display color and shape of the arrow image unit PgA and the road marking unit Prm until the remaining distance becomes less than 50 m. When the remaining distance becomes less than 50 m, the display control unit 73 performs the following: The display control unit 73 starts an animation display in which the display color of each image element of the arrow image unit PgA changes sequentially in the direction in which the vehicle Am is turning right or left (see FIGS. 17 and 18 ). The display control unit 73 continues to display the animation of the arrow image unit PgA until the vehicle Am has finished turning right or left (see FIG. 19 ).

[0116] Furthermore, the display control unit 73 starts changing the appearance of the route guidance content CTrg when the remaining distance becomes less than 50 meters. The display control unit 73 changes at least one of the display position and display color of the route guidance content CTrg, or displays an animation. In this way, the display control unit 73 helps the driver understand the remaining distance. Specifically, the display control unit 73 may perform the following when the remaining distance becomes less than 50 meters: The display control unit 73 changes the display color of the road marking unit Prm from an achromatic color to a chromatic color that is the same as or similar to the arrow image unit PgA (see FIG. 17 ). An example of an achromatic color is gray. An example of a chromatic color is blue or light blue. Furthermore, the display control unit 73 continuously changes the shape of the road marking unit Prm as the vehicle Am approaches the guidance point (see FIGS. 17 to 19 ).

[0117] The above-described route guidance content CTrg can visually indicate the distance to the guidance point by transitioning from a state in which behavioral changes are restricted to a state in which behavioral changes are utilized. Furthermore, the timing of right and left turns, etc., is clearly indicated to the driver by, for example, displaying an animation of the arrow image portion PgA. Furthermore, since all virtual images Vi are erased when the display area VA moves, the annoyance caused by switching the display area VA is reduced. This allows the route guidance content CTrg to appropriately assist the driver in understanding the remaining distance to the guidance point. As a result, the driver can receive appropriate guidance and pass the guidance point.

[0118] [FCTA Content] When the display control unit 73 displays the FCTA content CTta shown in FIG. 20 at the upper position VP2, it applies the fourth aspect rule to the FCTA content CTta. The FCTA content CTta is notification content that notifies the driver of other vehicles approaching from the front, left, and right of the vehicle Am, which are risk targets around the vehicle Am. These other vehicles will be referred to as approaching vehicles Av hereinafter. The FCTA content CTta is displayed based on the recognition of the approaching vehicle Av by the driving assistance ECU 22, for example, in a scene such as entering an intersection.

[0119] The FCTA content CTta is displayed on the left-right side of the display area VA where the approaching vehicle Av is located (see FIG. 20). Specifically, when the approaching vehicle Av is approaching the vehicle from the left side, the FCTA content CTta is displayed in an area to the left of the center of the display area VA (see FIG. 20). On the other hand, when the approaching vehicle Av is approaching the vehicle from the right side, the FCTA content CTta is displayed in an area to the right of the center of the display area VA.

[0120] When displaying the FCTA content CTta at the upper position VP2, the display control unit 73 may apply the fourth aspect rule as follows. The display control unit 73 sets a non-display area ANP in which the virtual image Vi is not displayed within the display area VA that has moved from the normal position VP1 to the upper position VP2. When the approaching vehicle Av is approaching the vehicle from the left side, the display control unit 73 sets the area to the right of the center of the display area VA as the non-display area ANP (see FIG. 20 ). On the other hand, when the approaching vehicle Av is approaching the vehicle from the right side, the display control unit 73 sets the area to the left of the center of the display area VA as the non-display area ANP. By setting the non-display area ANP in this way, the visibility of the FCTA content CTta that notifies the driver of a risk object is less likely to be obstructed by other virtual images Vi. As a result, the driver can quickly grasp the type and relative position of the risk object.

[0121] In addition, the display control unit 73 applies the fourth aspect rule to limit the number of display colors that can be used for the virtual image Vi. Furthermore, the display control unit 73 displays the FCTA content CTta in a manner that allows it to be distinguished from the route guidance content CTrg by display color and shape. Specifically, the display control unit 73 displays the route guidance content CTrg in a display color such as blue or light blue. On the other hand, the display control unit 73 displays the FCTA content CTta in a display color such as yellow or amber. Such a display color restriction can help the driver to instantly understand the information.

[0122] The approaching vehicle warning icon PaC is, for example, an image portion in which an "!" symbol is surrounded by a triangular frame, and alerts the driver to the presence of the approaching vehicle Av. The approaching vehicle warning icon PaC is drawn in an oblique position that becomes deeper as it approaches the center by rotating around an axis along the up-down direction US. The approaching vehicle warning icon PaC is displayed superimposed on the plane arrow image portion PaR.

[0123] The plane arrow image portion PaR has a shape extending in a band shape along the left-right direction Yo. The plane arrow image portion PaR employs a gradation representation in the left-right direction Yo. The plane arrow image portion PaR is drawn with high saturation and high brightness on the side closer to the approaching vehicle Av in the left-right direction Yo. In the example of FIG. 20 , the plane arrow image portion PaR is drawn with high saturation and high brightness on the left side in the left-right direction Yo. Furthermore, the plane arrow image portion PaR highlights the relative position of the approaching vehicle Av to the driver through an animation display that flows starting from the side closer to the approaching vehicle Av.

[0124] As described above, the plane arrow image section PaR employs a combination of a plane arrow shape and a gradation representation. This allows it to be clearly distinguished from the arrow image section PgA of the route guidance content CTrg. In addition, the approaching vehicle warning icon PaC superimposed on the plane arrow image section PaR instantly notifies the driver that it is a warning. Therefore, the FCTA content CTta is less likely to be mistaken for the route guidance content CTrg.

[0125] [Avoidance Assistance Content] When displaying the avoidance assistance content CTas shown in Fig. 21 at the upper position VP2, the display control unit 73 applies the fourth aspect rule to the avoidance assistance content CTas. The avoidance assistance content CTas is notification content that notifies of pedestrians PE, cyclists, etc. approaching from the front left and right of the vehicle Am, among risk objects around the vehicle Am. The avoidance assistance content CTas is displayed when the driving assistance ECU 22 performs steering assistance control or deceleration assistance control to avoid the pedestrian PE, etc.

[0126] The avoidance assistance content CTas is displayed on the side of the display area VA in the left-right direction Yo where the pedestrian PE, etc. are present. Specifically, when the pedestrian PE is approaching the host vehicle from the left side, the avoidance assistance content CTas is displayed in an area to the left of the center of the display area VA (see FIG. 21 ). On the other hand, when the pedestrian PE is approaching the host vehicle from the right side, the avoidance assistance content CTas is displayed in an area to the right of the center of the display area VA.

[0127] When displaying the avoidance assistance content CTas at the upper position VP2, the display control unit 73 applies the fourth aspect rule as follows. The display control unit 73 sets a non-display area ANP within the display area VA that has moved to the upper position VP2. When a pedestrian PE or the like is approaching the host vehicle from the left side, the display control unit 73 sets the area to the right of the center of the display area VA as the non-display area ANP (see FIG. 21 ). On the other hand, when a pedestrian PE or the like is approaching the host vehicle from the right side, the display control unit 73 sets the area to the left of the center of the display area VA as the non-display area ANP. By setting the non-display area ANP in this way, the visibility of the avoidance assistance content CTas that notifies the driver of a risk object is less likely to be obstructed by other virtual images Vi. As a result, the driver can quickly grasp the type and relative position of the risk object.

[0128] Furthermore, by applying the fourth aspect rule, the display control unit 73 limits the number of display colors that can be used for the virtual image Vi after the display area VA moves from the normal position VP1 to the upper position VP2. As an example, the display control unit 73 displays the avoidance assistance content CTas, which is composed of the pedestrian warning icon PaP and the line-shaped image portion PbL, in a single color. For example, the avoidance assistance content CTas may be displayed in a single color such as yellow or amber. Such a limitation on the display colors can help the driver understand the information instantaneously.

[0129] The pedestrian warning icon PaP is an image portion in which an icon resembling a pedestrian PE is surrounded by a triangular frame, and alerts the driver to the presence of the pedestrian PE. The pedestrian warning icon PaP indicates the direction of movement of the pedestrian PE using a minimum of elements. As an example, the minimum elements are the dynamic poses of the hands and feet drawn on the icon, and the drawing of the icon in a diagonal pose that becomes deeper as it approaches the center.

[0130] The line-shaped image portion PbL is an image portion extending toward the vanishing point VNP (see FIG. 14) in the foreground. The line-shaped image portion PbL is disposed so as to contact the edge of the lower center of the pedestrian warning icon PaP, and together with the pedestrian warning icon PaP, it emphasizes and indicates to the driver the relative position of the pedestrian PE.

[0131] As described above, the display control unit 73 makes it easier for the driver to recognize the pedestrian PE by displaying the avoidance assistance content CTas in a large, easily visible manner. Furthermore, the avoidance assistance content CTas can instantly inform the driver of the left and right directions in which the pedestrian PE is approaching. This can be achieved by setting the non-display area ANP and the pedestrian warning icon PaP, which is displayed in a single color in a tilted position.

[0132] While one embodiment of the present disclosure has been described above, the present disclosure should not be construed as being limited to the above embodiment. Various embodiments and combinations can be applied within the scope of the present disclosure.

[0133] In the first modification, the display of the text information MJ, such as vehicle speed and street name, in the upper position VP2 is restricted. Specifically, the text information MJ, whose content changes in real time, is not displayed in the display area VA in the upper position VP2. Furthermore, in the first modification, the solid background NH is not displayed in the display area VA in the upper position VP2.

[0134] The displacement mechanism 63 of Modification 2 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.

[0135] In the third modification, real-time detection information of the eye point EP by the interior camera is provided to the head-up ECU 70. The interior camera is a camera that captures images of the interior of the vehicle Am. The display control unit 73 adjusts each position of the display area VA and the display position of the virtual image Vi in accordance with the current position of the eye point EP based on the detection information in cooperation with the interior camera.

[0136] The content CT to which each aspect rule is applied is not limited to the content described above. Each aspect rule can be applied to various content CT that can be displayed by the HUD 100. For example, each aspect rule can be applied to ACC content, LTC content, RSA (Road Sign Assist) content, narrow road driving assistance content, etc.

[0137] Additionally, the shape, luminous color, display position, etc. of each content image may be changeable according to the driver's preferences. Furthermore, the driver may select whether or not to apply each aspect rule. For example, the number of colors, number of characters, and character size permitted to be displayed at the upper position VP2 may be adjustable. Furthermore, the language and unit types included in the text information MJ may be changed as appropriate based on user settings such as the driver's settings and settings such as the country and region where the vehicle Am is used.

[0138] In the fourth modification, 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 the fourth modification, a system including the meter ECU 32 or another in-vehicle ECU corresponds to the virtual image display device.

[0139] In the fifth modification, some or all of the processing functions of the head-up ECU 70 are implemented in an integrated control device such as an HCU (Human Machine Interface Control Unit). The processing functions of the meter ECU 32 may be further integrated in the HCU. In the fifth modification, the system including the HUD 100 and the HCU corresponds to a virtual image display device.

[0140] The PGU 61 may be provided with an EL (Electro Luminescence) panel instead of the LCD panel and backlight. Alternatively, the PGU 61 may use a display 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 a PGU 61 having 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. Additionally, the optical element used in the magnifying optical system 62 is not limited to the concave mirror 62a and may be various mirrors, lenses, holographic optical elements, or the like, as appropriate.

[0141] The processing units provided in the head-up ECU 70 and the meter ECU 32 are hardware for arithmetic processing coupled to a RAM. The processing units include at least one arithmetic core, such as a central processing unit (CPU) and a graphics processing unit (GPU). The processing units may further include, for example, a field-programmable gate array (FPGA) and an IP core with other dedicated functions. Meanwhile, the RAM may include a video RAM for image generation. The processing units access the RAM to execute various processes for realizing the virtual image display method of the present disclosure.

[0142] The storage includes a non-transitory tangible storage medium. The storage of each ECU 32, 70 stores various programs executed by the processing unit. These programs include, for example, a display control program. Such a storage medium is not limited to being mounted 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 or distributed to each ECU 32, 70.

[0143] 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 a large number of logic circuits or analog circuits.

[0144] The vehicle equipped with the display system 1 is not limited to a general private passenger car. The vehicle equipped with the display system 1 may be a rental car vehicle, a manned taxi vehicle, a ride-sharing vehicle, a freight vehicle, a bus, etc. The vehicle equipped with the display system 1 may be a right-hand drive vehicle or a left-hand drive vehicle. Furthermore, the traffic environment in which the vehicle travels may be a traffic environment based on left-hand traffic or a traffic environment 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, the position of the vehicle's steering wheel, etc.

[0145] 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.

[0146] (Disclosure of Technical Ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be described in a multiple dependent form, with the subsequent clause alternatively referring to the preceding clause. Furthermore, some clauses may be described in a multiple dependent form, with the subsequent clause referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0147] (Technical Idea 1) A virtual image display device that displays a virtual image visible to a driver of a vehicle, comprising: a switching mechanism (63) that switches the position of a display area where the virtual image is displayed between a plurality of positions including a first position and a second position; a display control unit (73) that displays the virtual images of a first content, which is a type of content to be displayed at the first position, and a second content, which is a type of content to be displayed at the second position, in accordance with the switching of the position of the display area by the switching mechanism; and an event status identification unit (74) that identifies the status of a specific event, which is an event that requires the second content to be displayed; wherein the switching mechanism switches the display area to the second position when the event status identification unit identifies that the specific event has occurred and the position of the display area is not at the second position; and the display control unit displays the second content before the switching of the display area to the second position by the switching mechanism is completed when the event status identification unit identifies that the specific event has occurred and the position of the display area is not at the second position.

[0148] (Technical Idea 2) A virtual image display device according to Technical Idea 1, wherein the switching mechanism switches the display area from the first position to the second position when the event status identification unit identifies that the specific event has occurred and the position of the display area is the first position, and the display control unit displays the second content from the timing when the display area is located at the first position before the switching of the display area from the first position to the second position by the switching mechanism is completed when the event status identification unit identifies that the specific event has occurred and the position of the display area is the first position.

[0149] (Technical Idea 3) A virtual image display device according to Technical Idea 1 or 2, wherein the switching mechanism switches the display area to the first position when the event status identification unit has identified the end of all of the specific events whose starts have been identified, and the display control unit ends the display of the second content before the switching of the display area to the first position is completed by the switching mechanism when the event status identification unit has identified the end of all of the specific events whose starts have been identified. The virtual image display device displays transition content, which is content including at least a portion of the first content.

[0150] (Technical Idea 4) A virtual image display device according to Technical Idea 3, wherein the switching mechanism switches the display area from the second position to the first position when the event status identification unit has identified the end of all of the specific events whose starts have been identified and the position of the display area is the second position, and the display control unit ends the display of the second content and displays the transition content from the timing when the display area is located at the second position before the switching mechanism has completed switching of the display area from the second position to the first position and the event status identification unit has identified the end of all of the specific events whose starts have been identified and the position of the display area is the second position.

[0151] (Technical Idea 5) A virtual image display device described in any one of Technical Ideas 1 to 4, comprising a situation type identification unit (75) that identifies a situation type that is either a type of situation for the occurrence of the specific event or a type of situation for the end of the specific event, wherein the switching mechanism switches the display area at a timing according to the situation type identified by the situation type identification unit, and the display control unit switches the content to be displayed at a timing according to the situation type identified by the situation type identification unit.

[0152] (Technical Idea 6) A virtual image display device according to Technical Idea 5, wherein the situation type identification unit identifies, as the situation type, at least a first situation type in which a new specific event has occurred while the specific event is occurring and the position of the display area is at the second position, and the switching mechanism, when the situation type identification unit identifies the first situation type, maintains the position of the display area at the second position without temporarily switching it from the second position to the first position, and the display control unit, when the situation type identification unit identifies the first situation type, starts displaying the second content for the new specific event from the timing at which the first situation type is identified, and displays the second content for the new specific event.

[0153] (Technical Idea 7) A virtual image display device according to Technical Idea 5 or 6, wherein the situation type identification unit identifies at least a second situation type as the situation type, in which the specific event ends while the switching mechanism is switching the position of the display area to the second position due to the occurrence of the specific event; when the situation type identification unit identifies the second situation type, the switching mechanism changes the switching to the first position even if the position of the display area has not yet switched to the second position; and when the situation type identification unit identifies the second situation type, the display control unit starts to end the display of the second content from the timing when the second situation type is identified, thereby ending the display of the second content, and starts to display transition content that includes at least a part of the first content, thereby displaying the transition content.

[0154] (Technical Idea 8) A virtual image display device according to any one of Technical Ideas 5 to 7, wherein the situation type identification unit identifies at least a third situation type as the situation type, where a new specific event has occurred while the specific event is occurring and the new specific event has a set priority higher than that of the specific event while the switching mechanism is switching the position of the display area to the second position; when the situation type identification unit identifies the third situation type, the switching mechanism continues switching the position of the display area to the second position without temporarily switching it from the second position to the first position; and when the situation type identification unit identifies the third situation type, the display control unit starts displaying the second content for the new specific event from the timing at which the third situation type is identified, and displays the second content for the new specific event.

[0155] (Technical Idea 9) A virtual image display device described in any one of Technical Ideas 5 to 8, wherein the situation type identification unit identifies at least a fourth situation type as the situation type, where a new specific event has occurred while the switching mechanism is switching the position of the display area to the first position due to the end of the specific event; when the situation type identification unit identifies the fourth situation type, the switching mechanism changes the switching to the second position even if the position of the display area has not yet been switched to the first position; and when the situation type identification unit identifies the fourth situation type, the display control unit starts displaying the second content for the new specific event from the timing when the fourth situation type is identified, and displays the second content for the new specific event.

Claims

1. A virtual image display device that displays a virtual image viewable by a driver of a vehicle, comprising: a switching mechanism (63) that switches the position of a display area in which the virtual image is displayed between a plurality of positions including a first position and a second position; a display control unit (73) that displays the virtual images of a first content, which is a type of content to be displayed at the first position, and a second content, which is a type of content to be displayed at the second position, in response to the switching of the position of the display area by the switching mechanism; and an event status identification unit (74) that identifies a status of a specific event, which is an event that requires the second content to be displayed; wherein the switching mechanism switches the display area to the second position when the event status identification unit identifies that the specific event has occurred and the position of the display area is not at the second position; and the display control unit displays the second content before the switching of the display area to the second position by the switching mechanism is completed when the event status identification unit identifies that the specific event has occurred and the position of the display area is not at the second position.

2. A virtual image display device as described in claim 1, wherein the switching mechanism switches the display area from the first position to the second position when the event status identification unit identifies that the specific event has occurred and the position of the display area is the first position, and the display control unit displays the second content from the time when the display area is located at the first position before the switching mechanism has completed switching of the display area from the first position to the second position when the event status identification unit identifies that the specific event has occurred and the position of the display area is the first position.

3. A virtual image display device as described in claim 1, wherein the switching mechanism switches the display area to the first position when the event status identification unit has identified the end of all of the specific events whose starts have been identified, and the display control unit terminates the display of the second content before the switching mechanism has completed switching of the display area to the first position when the event status identification unit has identified the end of all of the specific events whose starts have been identified. A virtual image display device which displays a transition content which includes at least a portion of the first content.

4. A virtual image display device as described in claim 3, wherein the switching mechanism switches the display area from the second position to the first position when the event status identification unit has identified the ends of all of the specific events whose starts have been identified and the position of the display area is the second position, and the display control unit terminates the display of the second content and displays the transition content from the timing when the display area is located at the second position before the switching of the display area from the second position to the first position by the switching mechanism is completed when the event status identification unit has identified the ends of all of the specific events whose starts have been identified and the position of the display area is the second position.

5. A virtual image display device as described in claim 1, comprising a situation type identification unit (75) that identifies a situation type that is either a situation type of the occurrence of the specific event or a situation type of the end of the specific event, wherein the switching mechanism switches the display area at a timing according to the situation type identified by the situation type identification unit, and the display control unit switches the content to be displayed at a timing according to the situation type identified by the situation type identification unit.

6. A virtual image display device as described in claim 5, wherein the situation type identification unit identifies as the situation type at least a first situation type in which, when the specific event is occurring and the position of the display area is at the second position, a new specific event has occurred with a set priority higher than that of the specific event; when the situation type identification unit identifies the first situation type, the switching mechanism maintains the position of the display area at the second position without switching it from the second position to the first position; and when the situation type identification unit identifies the first situation type, the display control unit starts displaying the second content for the new specific event from the timing at which the first situation type was identified, thereby displaying the second content for the new specific event.

7. A virtual image display device as described in claim 5, wherein the situation type identification unit identifies as the situation type at least a second situation type in which the specific event ends while the switching mechanism is switching the position of the display area to the second position due to the occurrence of the specific event, and when the situation type identification unit identifies the second situation type, the switching mechanism changes the switching to the first position even if the position of the display area has not been switched to the second position, and when the situation type identification unit identifies the second situation type, the display control unit starts to end the display of the second content from the timing when the second situation type is identified, ends the display of the second content, and starts to display a transition content that is content including at least a part of the first content, and displays the transition content.

8. A virtual image display device as described in claim 5, wherein the situation type identification unit identifies as the situation type at least a third situation type in which the specific event is occurring and a new specific event has occurred while the switching mechanism is switching the position of the display area to the second position, the new specific event having a set priority higher than that of the specific event; when the situation type identification unit identifies the third situation type, the switching mechanism continues switching the position of the display area to the second position without temporarily switching the position of the display area from the second position to the first position; and when the situation type identification unit identifies the third situation type, the display control unit starts displaying the second content for the new specific event from the timing at which the third situation type was identified, thereby displaying the second content for the new specific event.

9. A virtual image display device as described in claim 5, wherein the situation type identification unit identifies as the situation type at least a fourth situation type in which a new specific event has occurred while the switching mechanism is switching the position of the display area to the first position due to the end of the specific event, and when the situation type identification unit identifies the fourth situation type, the switching mechanism changes the switching to the second position even if the position of the display area has not been switched to the first position, and when the situation type identification unit identifies the fourth situation type, the display control unit starts displaying the second content for the new specific event from the timing at which the fourth situation type was identified, thereby displaying the second content for the new specific event.

10. A virtual image display method for displaying a virtual image viewable by a driver of a vehicle, the method comprising: a switching step executed by at least one processor for switching the position of a display area in which the virtual image is displayed between a plurality of positions including a first position and a second position; a display control step for displaying the virtual images of a first content, which is a type of content to be displayed at the first position, and a second content, which is a type of content to be displayed at the second position, in accordance with the switching of the position of the display area by the switching step; and an event status identification step for identifying a status of a specific event, which is an event requiring the display of the second content; wherein the switching step switches the display area to the second position when it is identified in the event status identification step that the specific event has occurred and the position of the display area is not at the second position; and the display control step displays the second content before the switching of the display area to the second position is completed in the switching step when it is identified in the event status identification step that the specific event has occurred and the position of the display area is not at the second position.

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