DISPLAY CONTROL DEVICE, DISPLAY CONTROL PROGRAM, AND DISPLAY CONTROL METHOD

Abstract

To provide a display control device capable of reducing discomfort of an occupant to behavior of a virtual image.SOLUTION: A road surface unevenness correction part 33 extracts information of a frequency band including a vehicle natural frequency fe from output signals of vehicle pitch angle sensors 91 to 94 as pitching posture change information, and corrects deviation of a display position of a virtual image 40 to an overlapping object in a foreground on the basis of the pitching posture change information. A correction inappropriate state determination part 34 determines a correction inappropriate state in detecting or predicting that a correction amount of the virtual image 40 by the road surface unevenness correction part 33 continuously becomes larger than a prescribed area of a display area PA, that a movement speed of the virtual image 40 due to correction becomes faster than a prescribed speed, or that the movement of the virtual image 40 due to the correction continuously becomes small to be different from movement of the overlapping object. A correction suppression part 35 reduces or stops correction of the display position by the road surface unevenness correction part 33 when the correction inappropriate state determination part 34 determines a correction inappropriate state.SELECTED DRAWING: Figure 13

Description

[Technical field]

[0001] The present invention relates to a display control device, a display control program, and a display control method for controlling the display position of a virtual image superimposed on a superimposition object in the foreground visible to a vehicle occupant. [Background technology]

[0002] Augmented reality head-up displays (hereinafter referred to as "AR-HUD") are known that superimpose a virtual image onto an object in the foreground that is visible to the driver. AR-HUD is an abbreviation for Augmented Reality-Head Up Display.

[0003] Patent Document 1 discloses a method for controlling the display position of a virtual image displayed by an AR-HUD. In the control method described in Patent Document 1, vehicle pitching attitude change information of 0.5 Hz or less (i.e., low frequency band) and vehicle pitching attitude change information of a band including the vehicle's natural frequency (i.e., high frequency band) are extracted from an output signal of a gyro sensor that detects changes in vehicle attitude. Note that vehicle pitching attitude changes in the low frequency band are caused by an increase or decrease in the number of occupants or gradual acceleration or deceleration of the vehicle. On the other hand, vehicle pitching attitude changes in the high frequency band are caused by unevenness of the road surface on which the vehicle is traveling.

[0004] In the control method described in Patent Document 1, the rendering ECU transmits image data whose position has been corrected based on the pitching attitude change information in the low frequency band to the HUD device. Furthermore, the HUD device corrects the projection position of the image based on the pitching attitude change information in the high frequency band, and projects the image light onto a display area defined on the front windshield (hereinafter simply referred to as "windshield") of the vehicle. In this way, the control method described in Patent Document 1 corrects the positional deviation of the virtual image with respect to the superimposed object in the foreground caused by the pitching attitude change of the vehicle. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent No. 6724885 Summary of the Invention [Problem to be solved by the invention]

[0006] The inventors of the present invention have found through repeated driving experiments of a vehicle equipped with an AR-HUD that in certain scenes, the driver feels discomfort due to a large positional deviation between the superimposed object in the foreground and the virtual image, even in the control method described in Patent Document 1. Examples of such scenes include driving on a bank, driving on a large uphill or downhill slope, passing over a step, driving on a road surface with gentle undulations, and sudden acceleration or deceleration of the vehicle.

[0007] In view of the above, an object of the present invention is to provide a display control device, a display control program, and a display control method that can reduce the discomfort felt by an occupant due to the behavior of a virtual image. [Means for solving the problem]

[0008] In order to achieve the above object, according to the invention of claim 1, a display control device that projects light onto a display area (PA) defined on a windshield (WS) of a vehicle and controls the display position of a virtual image (40-42, 41a, 41b) that is superimposed on a superimposed object in the foreground visible to an occupant, includes a road surface unevenness correction unit (33), a correction inappropriate state determination unit (34), and a correction suppression unit (35). The road surface unevenness correction unit extracts information of a frequency band including the vehicle's natural frequency (fe) as pitching attitude change information from the output signal of the vehicle pitch angle sensor (91-94) that detects changes in the vehicle's attitude, and corrects the deviation of the display position of the virtual image relative to the superimposed object in the foreground based on the pitching attitude change information. The correction inappropriate state determination unit determines that the correction is inappropriate when it detects or predicts that the amount of correction of the virtual image by the road surface unevenness correction unit continues to be greater than a specified range of the display area, or that the movement speed of the virtual image due to the correction becomes faster than a specified speed, or that the movement of the virtual image due to the correction becomes continuously minute and different from the movement of the superimposed object. When the correction inappropriate state determination section determines that the correction is inappropriate, the correction suppression section reduces or stops the correction of the display position by the road surface unevenness correction section.

[0009] According to this, in a scene where the vehicle is traveling on a specific road surface where the positional deviation between the superimposed object in the foreground and the virtual image is large, a correction inappropriate state is determined, and the amount of correction by the road surface unevenness correction unit is reduced or the virtual image is displayed without correction. Specifically, the virtual image is prevented from sticking to the upper or lower end of a predetermined range of the display area, from moving instantly toward the upper or lower end of the predetermined range of the display area, and from continuously making minute movements different from the movement of the superimposed object in the foreground. Therefore, this display control device can prevent the occupant from feeling discomfort due to the behavior of the virtual image. In this specification, the predetermined range of the display area may be the same range as the display area, or may be a range that is arbitrarily set within the display area.

[0010] Furthermore, the inventors have found that in a scene different from the specific scene, when the superimposed object in the foreground and the virtual image are corrected to be accurately aligned in response to vibrations from road surface unevenness as in the control method described in Patent Document 1, the behavior of the virtual image may not match the sensibility of the occupant. In other words, when the pitching attitude of the vehicle changes due to road surface unevenness, a moderate misalignment between the superimposed object in the foreground and the virtual image may suit the occupant's sensibility. Note that such occupant sensibility differs depending on each individual occupant.

[0011] Therefore, according to the invention of claim 10, a display control device that projects light onto a display area (PA) defined on a windshield (WS) of a vehicle and controls the display position of a virtual image (40-42, 41a, 41b) that is displayed superimposed on a superimposition object in the foreground visible to an occupant includes the road surface unevenness correction unit (33) and an adjustment unit (200). The adjustment unit can adjust a gain (K) used for correcting the display position by the road surface unevenness correction unit according to the occupant's preference.

[0012] According to this, the occupant can adjust the correction gain according to his / her preference, thereby reducing the amount of correction by the road surface unevenness correction unit so as to match the occupant's own sensibility. As a result, the behavior of the virtual image corrected by the road surface unevenness correction unit becomes familiar with the sensibility of each individual occupant, and it is possible to prevent the occupant from feeling uncomfortable.

[0013] The invention according to claim 13 relates to a display control program for controlling the display position of a virtual image (40-42, 41a, 41b) that is displayed superimposed on a superimposition object in the foreground seen by an occupant by projecting light onto a display area (PA) defined on a windshield (WS) of a vehicle. This display control program causes at least one processing unit (11, 12) to function as the road surface unevenness correction unit (33), the correction inadequate state determination unit (34), and the correction suppression unit (35). According to this, the display control program recited in claim 13 can also achieve the same effects as those of claim 1.

[0014] According to the invention of claim 14, there is provided a display control method for controlling a display position of a virtual image (40-42, 41a, 41b) that is displayed superimposed on a superimposed object in the foreground as seen by an occupant by projecting light onto a display area (PA) defined on a windshield (WS) of a vehicle. This display control method includes the following processes: Extracting information of a frequency band including a vehicle's natural frequency (fe) as pitching attitude change information from an output signal of a vehicle pitch angle sensor (91-94) that detects a change in the attitude of the vehicle, and correcting a deviation of the display position of the virtual image with respect to the superimposed object in the foreground based on the pitching attitude change information (S10, S20); Determining that the correction is inappropriate when it is detected or predicted that the correction amount of the virtual image continues to be larger than a predetermined range of the display area, or that the moving speed of the virtual image due to the correction becomes faster than a predetermined speed, or that the movement of the virtual image due to the correction becomes continuously minute and different from the movement of the superimposed object (S30). If it is determined that the correction is inappropriate, the correction of the display position is reduced or stopped (S50). According to this, the display control method according to claim 14 can also achieve the same advantageous effects as those of claim 1.

[0015] The reference symbols in parentheses attached to each component indicate an example of the correspondence between the component and specific components described in the embodiments described below. [Brief description of the drawings]

[0016] [Figure 1] 1 is a diagram illustrating an example of a configuration of an in-vehicle system related to a display control device according to a first embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an example of a specific configuration of an HCU, an autonomous driving ECU, and a vehicle control ECU. [Diagram 3] FIG. 13 is a diagram showing an example of a virtual image display during automatic driving. [Figure 4] FIG. 13 is a diagram showing another example of a virtual image display during automatic driving. [Diagram 5] 4 is a graph showing an example of vibration characteristics occurring in a vehicle. [Figure 6] FIG. 4 is a diagram illustrating an example of a specific configuration of a road surface unevenness correction unit. [Figure 7] 6 is a graph showing an example of a filter characteristic of a road surface unevenness corrector. [Figure 8] FIG. 4 is a diagram for explaining a pitching attitude of a vehicle. [Figure 9] 11 is a graph showing pitching attitude change information when traveling on an uneven road surface. [Figure 10] FIG. 2 is a diagram for explaining a state when a vehicle is running on a bank. [Figure 11] 11 is a graph showing pitching attitude change information when traveling on a bank. [Figure 12] 11 is a graph showing pitching attitude change information when traveling on a bank. [Figure 13] 10 is a flowchart of a display control process executed by a display control device according to a second embodiment. [Figure 14] 13 is a graph showing pitching attitude change information when traveling uphill or downhill with large undulations in the second embodiment. [Figure 15] 13 is a graph showing pitching attitude change information when passing over a step in the third embodiment. [Figure 16] 13 is a graph showing pitching attitude change information when the vehicle is traveling on a gently undulating road surface in the fourth embodiment. [Figure 17] 13 is a graph showing pitching attitude change information during rapid acceleration in the fifth embodiment. [Figure 18] FIG. 13 is a diagram illustrating an example of the configuration of an in-vehicle system related to a display control device according to a sixth embodiment. [Figure 19] FIG. 23 is a diagram illustrating an example of the configuration of an in-vehicle system related to a display control device according to a seventh embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0017] Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, the same or equivalent parts are denoted by the same reference numerals, and the description thereof will be omitted.

[0018] (First embodiment) A first embodiment of the present invention will be described. In the first embodiment, a display control device that controls the display position of a virtual image by an AR-HUD is configured by, for example, an HCU 10 shown in Fig. 1 and Fig. 2. The HCU 10 is mounted on a vehicle together with electronic control units such as a vehicle control ECU 80 and an autonomous driving ECU 50. Note that HCU is an abbreviation for HMI (Human Machine Interface) Control Unit. Also, ECU is an abbreviation for Electronic Control Unit. The HCU 10, the vehicle control ECU 80, and the autonomous driving ECU 50 are directly or indirectly electrically connected, and can communicate with each other via, for example, a communication bus 99 of an in-vehicle network.

[0019] As shown in Fig. 2, the vehicle control ECU 80 is mainly composed of a computer having a processor 81, a RAM 83, a memory device 84, an input / output interface 85, etc. The vehicle control ECU 80 performs integrated control of the acceleration / deceleration, steering, etc. of the vehicle by executing a vehicle control program stored in the memory device 84 by the processor 81. As shown in Fig. 1, the vehicle control ECU 80 is directly or indirectly electrically connected to a group of on-vehicle sensors and a group of on-vehicle actuators (not shown) mounted on the vehicle.

[0020] The on-board sensors include, for example, a gyro sensor 91, an acceleration sensor 92, a height sensor 93, and a wheel speed sensor 94. The gyro sensor 91 is a sensor that detects an angular velocity corresponding to a change in the attitude of the vehicle as a voltage value. The gyro sensor 91 is fixed to the vehicle and measures the angular velocity generated around each axis for three mutually orthogonal axes that are predefined for the vehicle. Specifically, the gyro sensor 91 measures the angular velocity associated with the yawing, pitching, and rolling of the vehicle, and sequentially outputs the measurement data to the vehicle control ECU 80 or the like.

[0021] The acceleration sensor 92 is a sensor that detects acceleration as a voltage value. The acceleration sensor 92 is fixed to the vehicle and measures acceleration in a direction along each of three axes defined for the vehicle. Specifically, the acceleration sensor 92 measures the acceleration in the front-rear direction, the acceleration in the left-right direction, and the acceleration in the up-down direction of the vehicle, and sequentially outputs the measurement data to the vehicle control ECU 80, etc.

[0022] The height sensor 93 is a sensor that detects the height of the vehicle. The height sensor 93 is provided, for example, near each wheel, and measures the amount of sinking of each wheel relative to the vehicle body, which is displaced up and down due to the operation of the suspension system. The height sensor 93 sequentially outputs measurement data measuring the amount of sinking of each wheel to the vehicle control ECU 80, etc. The height sensor 93 may be configured to directly measure the distance from the vehicle body to the road surface by irradiating ultrasonic waves or laser light from the vehicle body toward the road surface.

[0023] The wheel speed sensor 94 is a sensor that detects the rotation of the vehicle wheels. The wheel speed sensor 94 is provided near each wheel of the vehicle, and measures the rotation speed of the wheel from the difference between the rotation speed of a rotor that rotates with the wheel and the rotation speed of a detection unit fixed to the vehicle body. The wheel speed sensor 94 sequentially outputs measurement data obtained by measuring the rotation speed of each wheel to the vehicle control ECU 80, etc.

[0024] Any of the above-mentioned gyro sensor 91, acceleration sensor 92, height sensor 93, and wheel speed sensor 94 can be used as a vehicle pitch angle sensor that detects a change in the attitude of the vehicle. In the following description, the gyro sensor 91 is used as an example of the vehicle pitch angle sensor, but the vehicle pitch angle sensor can be an acceleration sensor 92, a height sensor 93, a wheel speed sensor 94, or the like, instead of or in addition to the gyro sensor 91.

[0025] Although not shown, the group of on-board actuators electrically connected to the vehicle control ECU 80 includes, for example, an electronically controlled throttle, an injector, a brake actuator, a driving and regenerative motor generator, a steering actuator, etc. The vehicle control ECU 80 controls the behavior of the vehicle by controlling each on-board actuator according to instructions from at least one of the driver and the autonomous driving ECU 50.

[0026] The autonomous driving ECU 50 cooperates with the vehicle control ECU 80 to control the acceleration / deceleration and steering of the vehicle. By installing the autonomous driving ECU 50 and the vehicle control ECU 80, the vehicle is equipped with an autonomous driving function. The autonomous driving function is capable of driving the vehicle on behalf of the driver. The autonomous driving function includes an autonomous driving function that does not require monitoring by the driver. In addition, advanced driving assistance functions such as ACC (Adaptive Cruise Control) and LTC (Lane Trace Control) are also included in the autonomous driving function.

[0027] 2, the autonomous driving ECU 50 is mainly composed of a computer having a main processor 51, a graphic processor 52, a RAM 53, a memory device 54, and an input / output interface 55. As shown in Fig. 1, the autonomous driving ECU 50 is directly or indirectly electrically connected to a group of surrounding monitoring sensors 65, a Global Navigation Satellite System (GNSS) receiver 66, a map database 67, and the like.

[0028] The periphery monitoring sensor group 65 includes, for example, a camera unit, a lidar, and a millimeter wave radar. The periphery monitoring sensor group 65 detects moving objects around the vehicle, such as pedestrians and other vehicles, as well as stationary objects, such as fallen objects on the road, traffic signals, guardrails, curbs, road signs, road markings, and dividing lines. Each component of the periphery monitoring sensor group 65 sequentially outputs detection information of moving objects and stationary objects to the autonomous driving ECU 50. In addition, the periphery monitoring sensor group 65 may be capable of detecting information related to unevenness of the road surface in the travel direction, such as seams on a highway, and outputting the information to the autonomous driving ECU 50.

[0029] The GNSS receiver 66 receives positioning signals from multiple artificial satellites. The GNSS receiver 66 measures the current position of the vehicle based on the received positioning signals. The GNSS receiver 66 sequentially outputs the measured vehicle position information to the autonomous driving ECU 50.

[0030] The map database 67 is mainly composed of a large-capacity storage medium storing a large amount of map data. The map data includes structural information such as the curvature value, gradient value, and section length of each road, as well as non-temporary traffic regulation information such as speed limits and one-way streets. The map data may also be linked to information related to unevenness of the road surface collected by the vehicle itself and other autonomous vehicles. The autonomous driving ECU 50 acquires map data of the surroundings and traveling direction of the vehicle from the map database 67 based on the position information measured by the GNSS receiver 66.

[0031] The autonomous driving ECU 50 can execute the autonomous driving program stored in the memory device 54 by the processors 51, 52. Based on the autonomous driving program, the autonomous driving ECU 50 constructs a route generation unit 61 as a functional block related to autonomous driving. The route generation unit 61 generates a route plan for autonomous driving of the vehicle based on the driving environment around the vehicle recognized by the surrounding monitoring sensor group 65 and map data provided from a map database 67. Based on the route plan generated by the route generation unit 61, the autonomous driving ECU 50 causes the vehicle control ECU 80 to execute steering for lane keeping and lane changing, acceleration / deceleration for speed adjustment, sudden braking for collision avoidance, and the like.

[0032] The HCU 10 comprehensively controls the presentation of information to the driver. As shown in Fig. 2, the HCU 10 is mainly composed of a computer having a main processor 11, a graphic processor 12, a RAM 13, a memory device 14, and an input / output interface 15. The HCU 10 is electrically connected to a plurality of notification devices that notify the driver of information. As shown in Fig. 1, the plurality of notification devices includes an AR-HUD device (hereinafter referred to as "HUD device 20").

[0033] The HUD device 20 is a display device that displays a virtual image 40 in front of a vehicle occupant, for example, a driver. The HUD device 20 projects image light for displaying the virtual image 40 onto a display area PA defined on a windshield WS. The light projected onto the windshield WS is reflected by the display area PA toward the driver and reaches an eye box that is predefined to be located around the driver's head. The driver, who positions his / her eyepoint in the eye box, can visually recognize the image light projected onto the display area PA as a virtual image 40 superimposed on a superimposition object set in the foreground visible to the driver.

[0034] The virtual image 40 includes a near virtual image 42 and a far virtual image 41. The near virtual image 42 and the far virtual image 41 are formed at different positions in the front-rear direction and the up-down direction of the vehicle.

[0035] As shown in Fig. 1 and Fig. 3, the near virtual image 42 is formed in a space of about 2 to 3 meters ahead of the vehicle from the eye point. As an example, the near virtual image 42 is displayed about 2 meters ahead of the eye point. The near virtual image 42 mainly presents vehicle information indicating the vehicle status to the driver. For example, indicators indicating the vehicle's running speed and the activation and operation status of the automatic driving function are displayed as the near virtual image 42.

[0036] On the other hand, the distant virtual image 41 is formed at a position farther from the windshield WS than the near virtual image 42, specifically, in a space about 10 to 20 meters ahead of the vehicle from the eye point. As an example, the distant virtual image 41 is displayed about 15 meters ahead of the eye point. The distant virtual image 41 is displayed as an augmented reality (hereinafter referred to as "AR") display by being superimposed on a superimposition target object as seen by the driver. When the automatic driving function of the vehicle is in operation, the distant virtual image 41 presents the driver with information related to automatic driving. On the other hand, when the vehicle is in a manual driving state, the distant virtual image 41 presents the driver with warning information.

[0037] 3, when the automatic driving function is in an active state, the HUD device 20 displays an AR route 41a as an example of a distant virtual image 41. The AR route 41a is displayed based on a route plan generated by the route generating unit 61, by superimposing the AR route 41a on the road surface along which the vehicle is scheduled to travel, thereby simulating the illumination of the road surface along which the vehicle is scheduled to travel.

[0038] As shown in Fig. 4, when the constant speed driving / following distance control function causes the vehicle to follow the vehicle ahead VF, the HUD device 20 displays a marking 41b as an example of a distant virtual image 41 below or around the vehicle ahead VF. The marking 41b indicates that the vehicle ahead VF to which it is attached is a vehicle to be followed. Note that the shape, position, size, etc. of the marking 41b are not limited to those shown in Fig. 4 and can be changed as appropriate. Note that, for the sake of explanation, dots are added to the AR route 41a and the marking 41b in Figs. 3 and 4.

[0039] Although not shown in the drawings, when the automatic driving function is in a stopped state, the HUD device 20 displays a warning marker as an example of the distant virtual image 41. The warning marker is superimposed on a notification object such as a pedestrian approaching the vehicle to alert the driver to the presence of the notification object.

[0040] As shown in FIG. 1, the HUD device 20 includes a far display 21, a near display 23, and a projection optical system 25 as a configuration for displaying a near virtual image 42 and a far virtual image 41. Image data of the display images displayed on the far display 21 and the near display 23 is generated by the HCU 10 and input to the far display 21 and the near display 23. The far display 21 and the near display 23 each have a display surface or screen (not shown) that emits light to display the display image. The far display 21 emits light of the display image formed as the far virtual image 41 at a position farther from the vehicle than the near virtual image 42, toward the projection optical system 25. The near display 23 emits light of the display image formed as the near virtual image 42, toward the projection optical system 25.

[0041] The projection optical system 25 reflects the light of each display image emitted from the far display device 21 and the near display device 23 toward the display area PA using a reflecting mirror (not shown). The reflecting mirror is formed by depositing a metal such as aluminum on the surface of a colorless and transparent base material made of, for example, synthetic resin or glass. The light of each display image is projected onto the display area PA by the projection optical system 25.

[0042] 2, the HCU 10 executes a display control program stored in the memory device 14 by the processors 11 and 12 in order to control the display positions and display modes of the far virtual image 41 and the near virtual image 42 displayed by the HUD device 20. As shown in FIG 1, in the HCU 10, an information acquisition unit 31, a drawing unit 32, a road surface unevenness correction unit 33, a correction inappropriate state determination unit 34, and a correction suppression unit 35 are constructed as functional blocks based on the display control program.

[0043] The information acquisition unit 31 selectively acquires information necessary for display control from various vehicle information and status information output from the autonomous driving ECU 50 and the vehicle control ECU 80 to the communication bus 99. Specifically, the information acquisition unit 31 acquires angular velocity measurement data by a gyro sensor 91 as information indicating the attitude state of the vehicle. The information acquisition unit 31 can also acquire acceleration measurement data by an acceleration sensor 92, vehicle height change measurement data by a height sensor 93, wheel speed measurement data by a wheel speed sensor 94, gradient information and road surface unevenness information linked to map data, etc.

[0044] The rendering unit 32 generates image data of the display images formed as the far virtual image 41 and the near virtual image 42 based on various vehicle information acquired by the information acquisition unit 31. The rendering unit 32 sequentially outputs the rendered image data to each of the far display device 21 and the near display device 23. The rendering unit 32 changes the type, arrangement, and other aspects of the images displayed as the far virtual image 41 and the near virtual image 42 based on the vehicle information.

[0045] Incidentally, an intersection position CP where a virtual line defined between an object to be superimposed of the distant virtual image 41 (for example, a road surface and a preceding vehicle, etc.) and the driver's eye point intersects with the display area PA of the windshield WS moves with a change in the vehicle's attitude. Therefore, the road surface unevenness correction unit 33 corrects the display position of the distant virtual image in accordance with the change in the vehicle's attitude so that the distant virtual image 41 is correctly superimposed on the object to be superimposed.

[0046] Here, the vibration characteristics induced in the vehicle by input from the road surface have a relationship between frequency and amplitude as shown in Fig. 5. As shown in Fig. 5, the amplitude of vibration induced in the vehicle increases significantly at the vehicle's natural frequency fe (e.g., about 1.5 Hz) and nearby frequencies (e.g., about 0.5 to 2.0 Hz). The natural frequency fe is a value determined by the sprung and unsprung weights of the vehicle, as well as the spring constant of the springs provided in the suspension device of each wheel, etc.

[0047] Therefore, the road surface unevenness correction unit 33 extracts information of a frequency band including the vehicle's natural frequency fe and its neighboring frequency band as pitching attitude change information from information of all frequency bands included in the output signal of the gyro sensor 91 as an example of a vehicle pitch angle sensor. Then, the road surface unevenness correction unit 33 corrects the deviation of the display position of the virtual image 40 relative to the superimposed object in the foreground based on the pitching attitude change information. Note that, of the distant virtual image 41 and the near virtual image 42, the road surface unevenness correction unit 33 of this embodiment corrects the deviation of the display position only for the distant virtual image 41. Note that, as described above, the road surface unevenness correction unit 33 may extract pitching attitude change information using output signals from the acceleration sensor 92, the height sensor 93, the wheel speed sensor 94, etc. instead of or together with the gyro sensor 91 as an example of a vehicle pitch angle sensor.

[0048] The road surface unevenness correction unit 33 adjusts the display position of the distant virtual image 41 at least in the vertical direction based on the pitching attitude change information so that the distant virtual image 41 is correctly superimposed on the superimposition object. Specifically, the road surface unevenness correction unit 33 outputs a road surface unevenness correction angle for moving the drawing position of the distant display image formed as the distant virtual image 41 on the display surface or screen of the distant display device 21 based on the pitching attitude change information. When the drawing unit 32 of the HCU 10 or the HUD device 20 moves the drawing position of the distant display image based on the road surface unevenness correction angle, the projection position of the light of the distant display image changes in the display area PA, so that the display position of the distant virtual image 41 also moves. The road surface unevenness correction unit 33 outputs the road surface unevenness correction angle for moving the drawing position of the distant display image so that the attitude change of the vehicle is offset, thereby maintaining the state in which the distant virtual image 41 is correctly superimposed on the superimposition object.

[0049] As shown in Fig. 6, the road surface unevenness correction unit 33 includes a high-pass filter 36, a low-pass filter 37, a correction angle calculation circuit 38, and the like. An angular velocity signal from a gyro sensor 91 is input to the high-pass filter 36. Then, the road surface unevenness correction unit 33 passes the angular velocity signal through the high-pass filter 36 and the low-pass filter 37 to extract a signal related to a change in the pitching attitude of the vehicle (i.e., pitching attitude change information). In the following description, the high-pass filter 36 and the low-pass filter 37 are collectively referred to as a "filter circuit 39." The filter circuit 39 is a band-pass filter.

[0050] Fig. 7 shows an example of the filter characteristics of the filter circuit 39 included in the road surface unevenness correction unit 33. As shown in Fig. 7, the filter circuit 39 has filter characteristics that pass mainly signals in a frequency band of, for example, 0.5 Hz to 2.0 Hz among the angular velocity signals transmitted from the gyro sensor 91, and attenuate signals in other frequency bands. In detail, the high-pass filter 36 mainly attenuates signals with frequencies lower than 0.5 Hz. The low-pass filter 37 mainly attenuates signals with frequencies higher than 2.0 Hz.

[0051] The signal that has passed through the filter circuit 39 (i.e., pitching attitude change information) is input to a correction angle calculation circuit 38. The correction angle calculation circuit 38 has an amplifier circuit. The correction angle calculation circuit 38 outputs a road surface unevenness correction angle using a predetermined gain K based on the signal that has passed through the filter circuit 39 (i.e., pitching attitude change information). As a result, the drawing unit 32 of the HCU 10 or the HUD device 20 uses the road surface unevenness correction angle output from the correction angle calculation circuit 38 to move the drawing position of the distant display image so that the change in the attitude of the vehicle is offset, and maintains a state in which the distant virtual image 41 is correctly superimposed on the superimposition target object.

[0052] Next, with reference to FIG. 8 and FIG. 9, pitching attitude change information that is extracted as a target by the filter circuit 39 of the road surface unevenness corrector 33 of this embodiment from the angular velocity signal from the gyro sensor 91 will be described.

[0053] As shown in Fig. 8, the vehicle pitching attitude is the attitude of the vehicle rotating around a virtual axis Y that extends in the vehicle width direction. The vehicle pitching attitude when the vehicle is traveling at a constant speed on a level road surface is defined as the neutral position or 0. A posture in which the front of the vehicle faces upward from the neutral position is defined as positive, and a posture in which the front of the vehicle faces downward from the neutral position is defined as negative.

[0054] FIG. 9 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness correction unit 33 when the vehicle runs on the road surface RS having the unevenness as shown in FIG. 8. In FIG. 9, the horizontal axis indicates time, and the vertical axis indicates the vehicle pitching attitude. As shown in the graph of FIG. 9, when the vehicle runs on the road surface RS having the unevenness as shown in FIG. 8, the pitching attitude change information oscillates at about 1 to 2 Hz with the 0 point as the center. The filter circuit 39 of the road surface unevenness correction unit 33 is designed to be able to mainly extract pitching attitude change information of, for example, about 2 deg. That is, the road surface unevenness correction unit 33 of this embodiment is designed to be able to output a road surface unevenness correction angle corresponding to the unevenness of the road surface RS when the vehicle runs on the road surface RS having the unevenness as shown in FIG. 8.

[0055] Next, the pitching attitude of the vehicle when the vehicle runs on a banked road will be described. Figure 10 is a view of the bank road BR as seen from above. As shown in Figure 10, the bank road BR is a corner where the outside of the curve is higher and the inside is lower. Therefore, from the perspective of a passenger in vehicle A traveling along the entrance BR1 of the bank road BR, the exit BR2 of the bank road BR appears above the bonnet of vehicle A. Therefore, while vehicle A is traveling along the bank road BR, the front of the vehicle continues to face upwards.

[0056] FIG. 11 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness correction unit 33 from the angular velocity signal output by the gyro sensor 91 when the vehicle runs on the bank road BR as shown in FIG. 10. As described above, since the front part of the vehicle continues to face upward while running on the bank road, the pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness correction unit 33 is offset from 0 in either the positive or negative direction (the positive direction in the example of FIG. 11) and the positive and negative are not reversed for a certain period of time. Therefore, as the vehicle travels on the bank road BR, the pitching attitude change information becomes a large angle of several tens of degrees (for example, 180 deg.). This is because the high-pass filter 36 of the road surface unevenness correction unit 33 is designed to attenuate low-frequency components of, for example, 0.5 Hz or less with a predetermined gain, but when a very large low-frequency component is input, it cannot be removed even with such a gain.

[0057] If the low-frequency elimination of the high-pass filter 36 were strengthened so as to eliminate the large low-frequency components input when traveling on a banked road BR, the phase and gain of the high-frequency components to be extracted would also decrease. For this reason, it is not possible to create such a high-pass filter 36. In other words, the filter circuit 39 cannot simultaneously "eliminate continuous large changes in vehicle pitching attitude" and "extract the targeted changes in vehicle pitching attitude caused by road surface irregularities."

[0058] Next, Fig. 12 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness corrector 33 when the vehicle has an uneven road surface RS as shown in Fig. 8 and travels on a bank road BR as shown in Fig. 10. When actually traveling on a bank road BR, such pitching attitude change information is extracted by the filter circuit 39. That is, the pitching attitude change information is offset from 0 in either the positive or negative direction (the positive direction in the example of Fig. 12), and the state in which the positive and negative are not reversed continues for a certain period of time.

[0059] When such pitching attitude change information is input from the filter circuit 39 to the correction angle calculation circuit 38, the correction angle calculation circuit 38 outputs a road surface unevenness correction angle using a predetermined gain K based on the pitching attitude change information. In this case, the road surface unevenness correction angle is much larger than the road surface unevenness correction angle output when traveling on a road surface RS having unevenness as shown in FIG. 8. Therefore, the correction amount of the distant virtual image 41 becomes larger than the predetermined range of the display area, and the distant virtual image 41 is stuck to the upper end of the predetermined range of the display area PA. In such a state, the positional deviation between the superimposed object in the foreground and the distant virtual image 41 becomes large, and this continues for a long time, so that the occupant feels uncomfortable. The predetermined range of the display area is exemplified by an angle of view of about 4 deg.

[0060] 1 detects or predicts that a state will occur in which the correction amount of the far virtual image 41 by the road surface unevenness correction unit 33 continues to be larger than a predetermined range of the display area PA, the correction inadequate state determination unit 34 determines that the correction of the far virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. Specifically, the correction inadequate state determination unit 34 determines that the correction inadequate state is present when a state in which the pitching attitude change information is offset from 0 in one direction and does not reverse positive and negative continues for a certain period of time. Note that, for example, when the natural frequency fe of the vehicle is about 1.5 Hz, the certain period of time may be set to 0.75 seconds or more, which is half of one period of the natural frequency fe.

[0061] When the correction inappropriate state determination unit 34 determines that the correction is inappropriate, the correction suppression unit 35 reduces or stops the correction of the display position of the far virtual image 41 by the road surface unevenness correction unit 33. When the correction suppression unit 35 reduces or stops the correction control by the road surface unevenness correction unit 33, the correction suppression unit 35 reduces the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle. As a result, the far virtual image 41 is displayed at or near the display position when the vehicle is in the neutral position. Therefore, vehicle information related to autonomous driving and warning information for the driver are continuously presented through the far virtual image 41.

[0062] Alternatively, when the correction suppression unit 35 reduces or stops the correction control by the road surface unevenness correction unit 33, the road surface unevenness correction unit 33 may move the distant virtual image 41 to a specific display position. Note that the specific display position is, for example, a display position of the distant virtual image 41 when it is assumed that the vehicle is in a neutral position. Alternatively, the specific display position may be a display position that is set in advance within a range in which the distant virtual image 41 can be displayed.

[0063] Furthermore, when the correction inappropriate state is determined by the correction inappropriate state determination unit 34, the correction suppression unit 35 may gradually reduce the correction of the display position by the road surface unevenness correction unit 33. In other words, the correction suppression unit 35 may gradually decrease the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle.

[0064] Alternatively, when reducing the correction of the display position by the road surface unevenness corrector 33, the correction suppressor 35 may set the gain K used for the correction near the upper and lower limits of the predetermined range of the display area PA to be smaller than the gain K used for the correction in the center of the predetermined range of the display area PA. This also makes it possible to prevent the distant virtual image 41 from being stuck to the upper end of the predetermined range of the display area PA.

[0065] Next, the above-described display control process of the far virtual image 41 by the HCU 10 will be described with reference to the flowchart of FIG.

[0066] The display control process is executed by the HCU 10 when the HUD device 20 starts displaying a virtual image.

[0067] In step S10, the filter circuit 39 of the road surface unevenness correction unit 33 extracts information of a frequency band including the vehicle's natural frequency fe and its vicinity from the output signal of a gyro sensor 91, which is an example of a vehicle pitch angle sensor, as pitching attitude change information.

[0068] Next, in step S20, the correction angle calculation circuit 38 of the road surface unevenness correction unit 33 calculates and outputs a road surface unevenness correction angle using a predetermined gain K based on the pitching attitude change information extracted by the filter circuit 39.

[0069] Next, in step S30, the correction inadequate state determination unit 34 determines whether the correction of the far virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. In the first embodiment, when the pitching attitude change information is offset from 0 in one direction and the positive and negative are not reversed for a certain period of time, the correction inadequate state determination unit 34 determines that the correction of the far virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. In other words, the correction inadequate state determination unit 34 can also determine that the correction is inadequate when it detects or predicts that a state will occur in which the correction amount of the far virtual image 41 by the road surface unevenness correction unit 33 will continue to be larger than a predetermined range of the display area PA.

[0070] In contrast, the correction inappropriate state determination unit 34 determines that the correction is not inappropriate (i.e., the correction is appropriate) when the pitching attitude change information is in a state where the positive and negative signs are reversed across 0. In other words, the correction inappropriate state determination unit 34 can also determine that the correction is not inappropriate (i.e., the correction is appropriate) when the amount of correction of the distant virtual image 41 by the road surface unevenness correction unit 33 is smaller than a predetermined range of the display area PA.

[0071] When it is determined in step S30 that the correction is not inappropriate (i.e., the correction is appropriate), the process proceeds to step S40. In step S40, the rendering position of the distant display image is corrected based on the road unevenness correction angle output by the correction angle calculation circuit 38 of the road unevenness correction unit 33. This maintains the state in which the distant virtual image 41 is correctly superimposed on the superimposed object in the external scene seen by the driver.

[0072] On the other hand, if it is determined in step S30 that the correction is inappropriate, the process proceeds to step S50. In step S50, the correction suppression unit 35 reduces or stops the correction of the display position of the far virtual image 41 by the road surface unevenness correction unit 33. For example, the correction suppression unit 35 reduces the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle. As a result, the far virtual image 41 is displayed at or near the display position of the far virtual image 41 when the vehicle is in the neutral position.

[0073] The HCU 10 repeatedly executes the above-described display control process until the virtual image display by the HUD device 20 is terminated.

[0074] The display control device according to the first embodiment described above provides the following advantageous effects.

[0075] (1) The display control device of the first embodiment includes a road surface unevenness correction unit 33, a correction inadequate state determination unit 34, and a correction suppression unit 35. The road surface unevenness correction unit 33 extracts pitching attitude change information from an output signal of a gyro sensor 91 as an example of a vehicle pitch angle sensor, and corrects a deviation of the display position of the distant virtual image 41 relative to a superimposed object in the foreground based on the information. The correction inadequate state determination unit 34 determines that a correction inadequate state exists when it is detected or predicted that the correction amount of the distant virtual image 41 by the road surface unevenness correction unit 33 will continue to be larger than a predetermined range of the display area PA. When the correction inadequate state is determined, the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33.

[0076] According to this, in a scene where the vehicle is traveling on a specific road surface where the positional deviation between the superimposed object in the foreground and the distant virtual image 41 becomes large and continues for a long time, a correction inappropriate state is determined, and the amount of correction by the road surface unevenness corrector 33 is reduced or the distant virtual image 41 is displayed without correction. Specifically, the distant virtual image 41 is prevented from sticking to the upper end or lower end of a predetermined range of the display area PA. Therefore, this display control device can prevent the occupant from feeling uncomfortable about the behavior of the distant virtual image 41.

[0077] (2) In the first embodiment, the compensation inadequate state determination unit 34 determines that the compensation is inadequate when the pitching attitude change information is offset in one direction from 0 and the positive / negative sign is not reversed for a certain period of time. According to this, for example, when the vehicle runs on a bank or the like, the front part of the vehicle continues to face upward in the pitching attitude of the vehicle, so it is detected or predicted that the pitching attitude change information will continue to be offset from 0 in the positive direction and the positive and negative values ​​will not be reversed for a certain period of time. In this case, the correction inappropriate state determination unit 34 determines the correction inappropriate state, and the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33, thereby preventing the distant virtual image 41 from sticking to the upper end or lower end of a predetermined range of the display area PA.

[0078] (3) In the first embodiment, the memory device 14 of the HCU 10 stores a display control program that causes at least one processing unit to function as the road surface unevenness correction unit 33, the correction inappropriate state determination unit 34, and the correction suppression unit 35. Therefore, the HCU 10 functions as the road surface unevenness correction unit 33, the correction inappropriate state determination unit 34, and the correction suppression unit 35 based on the display control program.

[0079] (4) In the first embodiment, the display control method executed by the HCU 10 includes the following processes: Pitching attitude change information is extracted from an output signal of a gyro sensor 91 as an example of a vehicle pitch angle sensor, and a deviation of the display position of the distant virtual image 41 relative to a superimposed object in the foreground is corrected based on the pitching attitude change information (S10, S20). When it is detected or predicted that the correction amount of the distant virtual image 41 will continue to be larger than a predetermined range of the display area PA, a correction inappropriate state is determined (S30). When a correction inappropriate state is determined, the correction of the display position is reduced or stopped (S50). According to this, in a scene where the positional deviation between the superimposed object in the foreground and the distant virtual image 41 becomes large and continues for a long time, a correction inappropriate state is determined, and the amount of correction by the road surface unevenness corrector 33 is reduced or the distant virtual image 41 is displayed without correction. Therefore, this display control method can prevent the occupant from feeling discomfort due to the behavior of the distant virtual image 41.

[0080] (Second to fifth embodiments) The second to fifth embodiments described below are different from the first embodiment in the traveling scenes in which it is determined that the position correction of the distant virtual image 41 is inappropriate, but are otherwise substantially the same as the first embodiment. Therefore, in the second to fifth embodiments, the differences from the first embodiment will be mainly described, and the description of the other aspects will be omitted.

[0081] Second embodiment The second embodiment will be described with reference to Fig. 14. Fig. 14 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness corrector 33 when the vehicle runs, for example, on an uphill or downhill road with large undulations. In this case, the pitching attitude change information has a large amplitude around the zero point.

[0082] When such pitching attitude change information is input from the filter circuit 39 to the correction angle calculation circuit 38, the road surface unevenness correction angle output from the correction angle calculation circuit 38 becomes much larger than the road surface unevenness correction angle when traveling on the uneven road surface RS shown in FIG. 8 in the first embodiment. Therefore, the correction amount of the distant virtual image 41 continues to be larger than the predetermined range of the display area PA, and the distant virtual image 41 is stuck to the upper end of the predetermined range of the display area PA. In such a state, the positional deviation between the superimposed object in the foreground and the distant virtual image 41 becomes large, which makes the occupant feel uncomfortable.

[0083] Therefore, when the correction inadequate state determination unit 34 detects or predicts the occurrence of a state in which the correction amount of the distant virtual image 41 by the road surface unevenness correction unit 33 continues to be larger than a predetermined range of the display area PA, the correction inadequate state determination unit 34 determines that the correction of the distant virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. Specifically, the correction inadequate state determination unit 34 determines the correction inadequate state when the amplitude of the pitching attitude change information is larger than a predetermined amplitude threshold Th1. The predetermined amplitude threshold Th1 is preset and stored in the memory device 14 as a value at which the correction amount of the distant virtual image 41 by the road surface unevenness correction unit 33 is larger than a predetermined range of the display area PA.

[0084] When the correction inadequate state determination unit 34 determines that the correction is inadequate, the correction suppression unit 35 reduces or stops the correction of the display position of the far virtual image 41 by the road surface unevenness correction unit 33. For example, the correction suppression unit 35 reduces the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle. In this case, the far virtual image 41 is displayed without being attached to the upper end of the predetermined range of the display area PA, or is displayed at or near the display position of the far virtual image 41 when the vehicle is in the neutral position.

[0085] In the second embodiment described above, the compensation inadequate state determiner 34 determines a compensation inadequate state when the amplitude of the pitching attitude change information is greater than a predetermined amplitude threshold value Th1. According to this, for example, when the vehicle travels on an uphill or downhill road with large undulations, the pitching attitude of the vehicle changes significantly, and the amplitude of the pitching attitude change information becomes large. In this case, the correction inappropriate state determination unit 34 determines the correction inappropriate state, and the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33, thereby preventing the distant virtual image 41 from sticking to the upper end or lower end of the predetermined range of the display area PA. Therefore, this display control device can prevent the occupant from feeling uncomfortable about the behavior of the distant virtual image 41.

[0086] Third embodiment The third embodiment will be described with reference to Fig. 15. Fig. 15 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness correction unit 33 when the vehicle passes over, for example, a step. In this case, the pitching attitude change information is a one-off input with a fast rise of a certain gradient or more. That is, the frequency of the pitching attitude change information becomes high.

[0087] When such pitching attitude change information is input from the filter circuit 39 to the correction angle calculation circuit 38, the road surface unevenness correction angle output from the correction angle calculation circuit 38 changes suddenly. Therefore, the distant virtual image 41 moves instantaneously toward the upper end or the lower end of the predetermined range of the display area PA. Such a sudden movement of the distant virtual image 41 makes the occupant feel uncomfortable.

[0088] Therefore, when the correction inadequate state determination unit 34 detects or predicts that the moving speed of the far virtual image 41 due to the correction by the road surface unevenness correction unit 33 becomes faster than a predetermined speed, it determines that the correction of the far virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. Specifically, the correction inadequate state determination unit 34 determines the correction inadequate state when the frequency of the pitching attitude change information is higher than a predetermined frequency threshold (e.g., 5 Hz). Note that the predetermined frequency threshold is preset and stored in the memory device 14 as a value at which the moving speed of the far virtual image 41 due to the correction by the road surface unevenness correction unit 33 becomes faster than the predetermined speed.

[0089] When the correction inadequate state determination unit 34 determines that the correction is inadequate, the correction suppression unit 35 reduces or stops the correction of the display position of the far virtual image 41 by the road surface unevenness correction unit 33. For example, the correction suppression unit 35 reduces the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle. In this case, the moving speed of the far virtual image 41 in the upward or downward direction slows down, or the far virtual image 41 is displayed at or near the display position of the far virtual image 41 when the vehicle is in the neutral position.

[0090] In the third embodiment described above, the correction inadequate state determination unit 34 determines the correction inadequate state when it is detected or predicted that the moving speed of the far virtual image 41 due to the correction will be faster than a predetermined speed. Specifically, the correction inadequate state determination unit 34 determines the correction inadequate state when the frequency of the pitching attitude change information is higher than a predetermined frequency threshold. According to this, for example, when the pitching attitude of the vehicle changes significantly instantaneously when the vehicle passes over a step, the frequency of the pitching attitude change information becomes high. In this case, the correction inappropriate state determination unit 34 determines the correction inappropriate state, and the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33, thereby preventing the distant virtual image 41 from moving instantaneously toward the upper end or lower end of the predetermined range of the display area PA. Therefore, this display control device can prevent the occupant from feeling uncomfortable about the behavior of the distant virtual image 41.

[0091] (Fourth embodiment) The fourth embodiment will be described with reference to Fig. 16. Fig. 16 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness corrector 33 when the vehicle runs on, for example, a road surface with gentle undulations. In this case, the pitching attitude change information is a minute movement with a small amplitude.

[0092] When such pitching attitude change information is input from the filter circuit 39 to the correction angle calculation circuit 38, the road surface unevenness correction angle output from the correction angle calculation circuit 38 becomes out of phase with the actual movement of the superimposed object, and the distant virtual image 41 and the superimposed object move out of phase with each other. Such a sudden movement of the distant virtual image 41 gives the occupant a sense of discomfort.

[0093] Therefore, when the correction inadequate state determination unit 34 detects or predicts that the movement of the distant virtual image 41 caused by the correction by the road surface unevenness correction unit 33 becomes continuously small and different from the movement of the superimposed object, the correction inadequate state determination unit 34 determines that the correction of the distant virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. Specifically, when the pitching attitude change information is smaller than a predetermined small amplitude threshold value Th2, the correction inadequate state determination unit 34 determines that the correction is inadequate. Note that the predetermined small amplitude threshold value Th2 is preset and stored in the memory device 14 as a value at which the movement of the distant virtual image 41 caused by the correction by the road surface unevenness correction unit 33 becomes continuously small and different from the movement of the superimposed object.

[0094] When the correction inadequate state determination unit 34 determines that the correction is inadequate, the correction suppression unit 35 reduces or stops the correction of the display position of the far virtual image 41 by the road surface unevenness correction unit 33. For example, the correction suppression unit 35 reduces the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle. In this case, the far virtual image 41 is displayed at or near the display position of the far virtual image 41 when the vehicle is in the neutral position.

[0095] In the fourth embodiment described above, the correction inadequate state determination unit 34 determines the correction inadequate state when it is detected or predicted that the movement of the far virtual image 41 due to the correction becomes continuously small and different from the movement of the superimposed object. Specifically, the correction inadequate state determination unit 34 determines the correction inadequate state when the pitching attitude change information is smaller than a predetermined small amplitude threshold Th2. According to this, for example, when traveling on a road surface with gentle undulations, the vehicle continues to have a state in which the change in pitching attitude is small, so the amplitude of the pitching attitude change information becomes small. In this case, the correction inappropriate state determination unit 34 determines a correction inappropriate state, and the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33, thereby preventing the distant virtual image 41 from continuously making small movements different from the movement of the superimposed object. Therefore, this display control device can prevent the occupant from feeling discomfort due to the behavior of the distant virtual image 41.

[0096] Fifth embodiment The fifth embodiment will be described with reference to Fig. 17. Fig. 17 is a graph showing an example of pitching attitude change information extracted by the filter circuit 39 of the road surface unevenness corrector 33 when the vehicle accelerates at a certain speed or more. When the acceleration of the vehicle is large, the front part of the vehicle faces upward significantly, so that the pitching attitude change information has a large amplitude on the positive side.

[0097] When such pitching attitude change information is input from the filter circuit 39 to the correction angle calculation circuit 38, the road surface unevenness correction angle output from the correction angle calculation circuit 38 becomes much larger than the road surface unevenness correction angle when traveling on the uneven road surface RS shown in FIG. 8 in the first embodiment. Therefore, the correction amount of the distant virtual image 41 continues to be larger than the predetermined range of the display area PA, and the distant virtual image 41 is stuck to the upper end of the predetermined range of the display area PA. In this state, the positional deviation between the superimposed object in the foreground and the distant virtual image 41 becomes large, so that the occupant feels uncomfortable. This also occurs when the vehicle decelerates at a certain speed or more. In that case, the distant virtual image 41 is stuck to the lower end of the predetermined range of the display area PA.

[0098] Therefore, when the correction inadequate state determination unit 34 detects or predicts the occurrence of a state in which the correction amount of the distant virtual image 41 by the road surface unevenness correction unit 33 continues to be larger than the predetermined range of the display area PA, the correction inadequate state determination unit 34 determines that the correction of the distant virtual image 41 by the road surface unevenness correction unit 33 is in an inadequate state. Specifically, the correction inadequate state determination unit 34 determines the correction inadequate state when it detects that the vehicle has accelerated to a predetermined acceleration threshold or more or decelerated to a predetermined deceleration threshold or more. The predetermined acceleration threshold and the predetermined deceleration threshold are preset and stored in the memory device 14 as values ​​at which the correction amount of the distant virtual image 41 by the road surface unevenness correction unit 33 is larger than the predetermined range of the display area PA.

[0099] When the correction inadequate state determination unit 34 determines that the correction is inadequate, the correction suppression unit 35 reduces or stops the correction of the display position of the far virtual image 41 by the road surface unevenness correction unit 33. For example, the correction suppression unit 35 reduces the gain K used when the correction angle calculation circuit 38 outputs the road surface unevenness correction angle. In this case, the far virtual image 41 is displayed without being attached to the upper end of the predetermined range of the display area PA, or is displayed at or near the display position of the far virtual image 41 when the vehicle is in the neutral position.

[0100] In the fifth embodiment described above, the compensation inadequate state determination unit 34 determines the compensation inadequate state when it detects that the vehicle is accelerating or decelerating at a certain level or more. According to this, when the acceleration or deceleration of the vehicle is large, the pitching attitude of the vehicle changes significantly. Specifically, when the acceleration of the vehicle is large, the front of the vehicle faces significantly upward, and when the deceleration of the vehicle is large, the front of the vehicle faces significantly downward. In this case, the correction inappropriate state determination unit 34 determines the correction inappropriate state, and the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33, thereby preventing the distant virtual image 41 from sticking to the upper end or lower end of the predetermined range of the display area PA. Therefore, this display control device can prevent the occupant from feeling uncomfortable with the behavior of the distant virtual image 41.

[0101] Sixth embodiment The display control described in the first to fifth embodiments reduces the discomfort felt by the occupant due to the large positional deviation between the superimposed object in the foreground and the distant virtual image 41 in a specific scene. In contrast, the sixth embodiment described below is a result of further study by the inventors, who discovered that even when the superimposed object in the foreground and the distant virtual image 41 are corrected to be accurately aligned with each other in response to vibrations from road surface unevenness, the behavior of the distant virtual image 41 may not match the occupant's sensibility. In other words, when the pitching attitude of the vehicle changes due to road surface unevenness, it may be more familiar to the occupant's sensibility if the superimposed object in the foreground and the distant virtual image 41 are appropriately deviated. Note that such occupant sensibility differs depending on each individual occupant.

[0102] Therefore, as shown in FIG. 18, the sixth embodiment includes an adjustment unit 200 electrically connected directly or indirectly to the HCU 10. The adjustment unit 200 has a function of adjusting a gain K used for correcting the display position by the road surface unevenness correction unit 33 (specifically, a gain K used when the correction angle calculation circuit 38 calculates the road surface unevenness correction angle) by the operation of the occupant. The adjustment unit 200 can be configured, for example, by a switch installed in the vehicle or a communication device such as a smartphone that can be operated by the occupant. The occupant can reduce the amount of correction by the road surface unevenness correction unit 33 to suit the occupant's own sensibility by adjusting the correction gain K according to his / her own preference. As a result, the superimposed object in the foreground and the distant virtual image 41 are appropriately shifted with a change in the pitching attitude of the vehicle due to the road surface unevenness, and the image becomes familiar to the occupant's sensibility. Therefore, the display control device of the sixth embodiment can also prevent the occupant from feeling discomfort in the behavior of the distant virtual image 41.

[0103] The adjustment unit 200 may adjust the gain K used for correcting the display position by the road surface unevenness correction unit 33 when the correction suppression unit 35 reduces the correction of the display position by the road surface unevenness correction unit 33. Alternatively, the adjustment unit 200 may be capable of adjusting the correction gain K regardless of the operation of the correction suppression unit 35.

[0104] The adjustment unit 200 may be capable of independently adjusting the gain K used in the correction of the display position by the road surface unevenness correction unit 33 for the upward correction and the downward correction. In this way, the occupant can independently adjust the correction gain K for the upward correction and the downward correction according to his / her own preference, thereby making it possible to match the behavior of the distant virtual image 41 to the sensibility of each individual occupant.

[0105] Furthermore, the adjustment unit 200 may be capable of independently adjusting the upper limit position and the lower limit position of the distant virtual image 41 that move in response to correction of the display position by the road surface unevenness correction unit 33. In this way, the behavior of the distant virtual image 41 can be adapted to the sensibility of each individual occupant by independently adjusting the upper limit position and the lower limit position of the distant virtual image 41 according to his / her own preference.

[0106] Seventh embodiment A seventh embodiment of the present invention will be described below. In the seventh embodiment, the display control device is configured by a HUD control circuit 30 provided in a HUD device 20, for example, as shown in FIG.

[0107] The HUD device 20 of the seventh embodiment includes an attitude control mechanism 26 and a HUD control circuit 30 in addition to the far display device 21, the near display device 23, and the projection optical system 25. The attitude control mechanism 26 is a mechanism for controlling the attitude of the projection optical system 25. The attitude control mechanism 26 is configured integrally with at least one reflecting mirror that reflects the light of the far display image among the multiple reflecting mirrors included in the projection optical system 25. The attitude control mechanism 26 changes the attitude of the reflecting mirror to vertically move the position in the display area PA where the light of the far display image is projected, thereby vertically moving the imaging position of the far virtual image 41.

[0108] The HUD control circuit 30 includes a plurality of processors and memory devices, similar to the HCU 10 described in the first embodiment and the like, and is connected to the autonomous driving ECU 50 and the vehicle control ECU 80 via a communication bus 99. The HUD control circuit 30 causes each processor to execute a display control program stored in the memory device, thereby constructing an information acquisition unit 31, a drawing unit 32, a road surface unevenness correction unit 33, a correction inappropriate state determination unit 34, and a correction suppression unit 35 that are substantially the same as those in the first embodiment.

[0109] The road surface unevenness correction unit 33 extracts pitching attitude change information from the output signal of the gyro sensor 91, which is an example of a vehicle pitch angle sensor, and outputs a road surface unevenness correction angle based on the information. The attitude control mechanism 26 uses the road surface unevenness correction angle to move the rendering position of the distant display image so that the attitude change of the vehicle is offset. The correction inappropriate state determination unit 34 determines that the correction is inappropriate when it is detected or predicted that the correction amount of the distant virtual image 41 continues to be larger than a predetermined range of the display area PA, or that the moving speed of the distant virtual image 41 due to the correction becomes faster than a predetermined speed, or that the movement of the distant virtual image 41 due to the correction continues to become minute and is different from the movement of the superimposed object. When the correction inappropriate state is determined, the correction suppression unit 35 reduces or stops the correction of the display position by the road surface unevenness correction unit 33.

[0110] As in the seventh embodiment described above, even if a display control device that controls the display position of the distant virtual image 41 is provided in the HUD device 20, it is possible to achieve the same effects as the first to sixth embodiments described above.

[0111] (Other embodiments) In each of the above embodiments, the correction inadequate state determination unit 34 determines whether or not the correction is inadequate based on the pitching attitude change information or the acceleration / deceleration of the vehicle, but this is not limited thereto. For example, the correction inadequate state determination unit 34 may determine whether or not the correction is inadequate based on a combination of pitching attitude change information or the acceleration / deceleration of the vehicle, longitudinal gradient and lateral gradient information such as a map, camera information, or information transmitted from another sensor.

[0112] In each of the above embodiments, only the far virtual image 41 is subject to control for position correction, but the present invention is not limited thereto, and both the far virtual image 41 and the near virtual image 42 may be subject to control for position correction.

[0113] The HUD device in each of the above embodiments has a bifocal configuration that displays the far virtual image 41 and the near virtual image 42, but is not limited thereto, and may have a multifocal configuration that forms the virtual image 40 at three or more focal points, or may have a single-focus configuration that forms the virtual image 40 at one focal point. In addition, the HUD device may have a configuration in which the position of the focal point is movable in the front-rear direction of the vehicle.

[0114] In the above embodiments, the display position of the virtual image 40 is corrected by moving the drawing position on the display surface or screen, controlling the attitude of the reflecting mirror of the projection optical system, or the like. However, the present invention is not limited to this. For example, the display position of the virtual image 40 may be corrected by moving the entire HUD device. Alternatively, the display position of the virtual image 40 may be corrected by controlling the shifting of a distant display within the HUD device. Furthermore, the display position of the virtual image 40 may be corrected by combining a plurality of correction methods.

[0115] Although the virtual image 40 in each of the above embodiments can be displaced mainly in the vertical direction, the present invention is not limited thereto, and for example, the virtual image 40 may be rotated in accordance with the roll of the vehicle so that a positional deviation caused by the roll is corrected. Furthermore, the virtual image 40 may be moved in the horizontal direction.

[0116] In the first embodiment, when the pitching attitude change information is offset in the positive direction and the positive and negative are not reversed for a certain period of time while the vehicle is traveling on a bank road, for example, the correction inappropriate state is determined, and the correction of the display position is reduced or stopped. However, this is not limited to this. For example, when the pitching attitude change information is offset in the negative direction and the positive and negative are not reversed for a certain period of time while the vehicle is traveling on a reverse bank road, the correction inappropriate state may be determined, and the correction of the display position may be reduced or stopped. Note that a reverse bank road refers to a corner with a slope where the inside of the curve is higher and the outside is lower.

[0117] Thus, the present invention is not limited to the above-described embodiments, and can be appropriately modified within the scope of the claims. Moreover, the above-described embodiments are not unrelated to each other, and can be appropriately combined, except when the combination is clearly impossible. Moreover, in each of the above-described embodiments, it goes without saying that the elements constituting the embodiments are not necessarily essential, except when they are specifically stated to be essential or when they are clearly considered to be essential in principle. Moreover, in each of the above-described embodiments, when the numbers, values, amounts, ranges, etc. of the components of the embodiments are mentioned, they are not limited to the specific numbers, except when they are specifically stated to be essential or when they are clearly limited to a specific number in principle. Moreover, in each of the above-described embodiments, when the shapes, positional relationships, etc. of the components are mentioned, they are not limited to the shapes, positional relationships, etc., except when they are specifically stated to be essential or when they are clearly limited to a specific shape, positional relationship, etc. in principle.

[0118] The control unit and the method described in the present disclosure may be implemented by a special-purpose computer provided by configuring a processor and a memory programmed to execute one or more functions embodied in a computer program. Alternatively, the control unit and the method described in the present disclosure may be implemented by a special-purpose computer provided by configuring a processor with one or more dedicated hardware logic circuits. Alternatively, the control unit and the method described in the present disclosure may be implemented by one or more special-purpose computers configured by a combination of a processor and a memory programmed to execute one or more functions and a processor configured with one or more hardware logic circuits. The computer program may also be stored in a computer-readable non-transitory tangible recording medium as instructions executed by the computer.

[0119] The memory device of each electronic control unit may be a variety of non-transitory tangible storage media such as a flash memory and a hard disk. The storage medium for storing the display control program is not limited to the memory device provided in the HCU, and may be an optical disk or a hard disk drive of a general-purpose computer that is a copy source of the display control program to the memory device. The display control program and the display control method according to the present disclosure may be realized by a configuration different from that of the HCU 10 and the HUD device 20 of each of the above-mentioned embodiments. For example, a navigation device and an automatic driving ECU mounted on a vehicle may execute the display control program by a processor to realize the function of a display control device. Furthermore, a plurality of electronic control units may cooperate to execute the display control program and the display control method according to the present disclosure. Alternatively, a processing unit of an electronic control unit that integrates two or more functions of the HCU, the automatic driving ECU, and the vehicle control ECU may execute the display control program and the display control method according to the present disclosure. [Explanation of symbols]

[0120] 10 HCU (Display Control Unit) 20 HUD device (display control device) 30 HUD control circuit (display control device) 33 Road surface unevenness correction section 34 Correction inappropriate state judgement unit 35 Correction suppressor 40 Virtual Image 41, 41a, 41b Distant virtual image 91 Gyro sensor PA display area

Claims

1. A display control device that projects light onto a display area (PA) defined on a windshield (WS) of a vehicle and controls a display position of a virtual image (40-42, 41a, 41b) that is superimposed on a superimposition object in a foreground visible to an occupant, a road surface unevenness correction unit (33) that extracts information of a frequency band including a natural frequency (fe) of the vehicle as pitching attitude change information from an output signal of a vehicle pitch angle sensor (91 to 94) that detects an attitude change of the vehicle, and corrects a deviation of a display position of the virtual image with respect to the superimposition object based on the pitching attitude change information; a correction inappropriate state determination unit (34) that determines that the correction is inappropriate when it is detected or predicted that the amount of correction of the virtual image by the road surface unevenness correction unit continues to be larger than a predetermined range of the display area, or the moving speed of the virtual image due to the correction becomes faster than a predetermined speed, or the movement of the virtual image due to the correction becomes continuously minute and different from the movement of the superimposed object; a correction suppression unit (35) that reduces or stops the correction of the display position by the road surface unevenness correction unit when a correction inappropriate state is determined by the correction inappropriate state determination unit.

2. In the pitching attitude change information extracted by the road surface unevenness correction unit from the output signal of the vehicle pitch angle sensor, when the attitude of the vehicle when traveling at a constant speed on a level road surface is defined as a neutral position or 0, a attitude in which the front part of the vehicle faces upward with respect to the neutral position is defined as a positive attitude, and a attitude in which the front part of the vehicle faces downward with respect to the neutral position is defined as a negative attitude, The display control device according to claim 1, wherein the correction inadequate state determination unit determines that the correction is inadequate when the pitching attitude change information is offset from 0 in either the positive direction or the negative direction and the positive / negative state is not reversed for a certain period of time.

3. 3. The display control device according to claim 1, wherein the correction inappropriate state determination unit determines a correction inappropriate state when the amplitude of the pitching attitude change information extracted by the road surface unevenness correction unit from the output signal of the vehicle pitch angle sensor is greater than a predetermined amplitude threshold (Th1).

4. 4. The display control device according to claim 1, wherein the correction inappropriate state determination unit determines a correction inappropriate state in which a moving speed of the virtual image due to correction is detected or predicted to be faster than a predetermined speed when a frequency of the pitching attitude change information extracted by the road surface unevenness correction unit from the output signal of the vehicle pitch angle sensor is greater than a predetermined frequency threshold.

5. 5. The display control device according to claim 1, wherein when the pitching attitude change information extracted by the road surface unevenness correction unit from the output signal of the vehicle pitch angle sensor is smaller than a predetermined small amplitude threshold (Th2), the correction inappropriate state determination unit determines that the movement of the virtual image due to the correction becomes continuously small and different from the movement of the superimposed object, thereby determining that the correction is inappropriate.

6. 6. The display control device according to claim 1, wherein the compensation inadequate state determination unit determines the compensation inadequate state when it detects an acceleration equal to or greater than a predetermined acceleration threshold or a deceleration equal to or greater than a predetermined deceleration threshold in the vehicle.

7. The display control device according to claim 1 , wherein the correction suppression unit gradually reduces the correction of the display position performed by the road surface unevenness correction unit when the correction inappropriate state determination unit determines that the correction inappropriate state exists.

8. 8. The display control device according to claim 1, wherein the correction suppression unit, when reducing the correction of the display position by the road surface unevenness correction unit, makes a gain (K) used for correction near the upper and lower limits of a specified range of the display area smaller than a gain used for correction in the center of the specified range of the display area.

9. The display control device according to any one of claims 1 to 8, further comprising an adjustment unit (200) capable of adjusting a gain used in correcting the display position by the road surface unevenness correction unit when the correction suppression unit reduces the correction of the display position by the road surface unevenness correction unit according to the preference of an occupant.

10. A display control device that projects light onto a display area (PA) defined on a windshield (WS) of a vehicle and controls a display position of a virtual image (40-42, 41a, 41b) that is superimposed on a superimposition object in a foreground visible to an occupant, a road surface unevenness correction unit (33) that extracts information of a frequency band including a natural frequency (fe) of the vehicle as pitching attitude change information from an output signal of a vehicle pitch angle sensor (91 to 94) that detects a change in the attitude of the vehicle, and corrects a deviation of a display position of the virtual image with respect to the superimposition object based on the pitching attitude change information; and an adjustment unit (200) capable of adjusting a gain (K) used in correcting the display position by the road surface unevenness correction unit according to the preference of a passenger.

11. The display control device according to claim 10 , wherein the adjustment unit is capable of independently adjusting a gain used in the display position correction by the road surface unevenness correction unit for an upward correction and a downward correction.

12. The display control device according to claim 10 , wherein the adjustment unit is capable of independently adjusting an upper limit position and a lower limit position of the virtual image that move in response to correction of the display position by the road surface unevenness correction unit.

13. A display control program for controlling a display position of a virtual image (40-42, 41a, 41b) that is superimposed on a superimposition object in a foreground visible to an occupant by projecting light onto a display area (PA) defined on a windshield (WS) of a vehicle, At least one processing unit (11, 12), a road surface unevenness correction unit (33) that extracts information of a frequency band including a natural frequency (fe) of the vehicle as pitching attitude change information from an output signal of a vehicle pitch angle sensor (91 to 94) that detects an attitude change of the vehicle, and corrects a deviation of a display position of the virtual image with respect to the superimposition object based on the pitching attitude change information; a correction inappropriate state determination unit (34) that determines that the correction is inappropriate when it is detected or predicted that the amount of correction of the virtual image by the road surface unevenness correction unit continues to be larger than a predetermined range of the display area, or the moving speed of the virtual image due to the correction becomes faster than a predetermined speed, or the movement of the virtual image due to the correction becomes continuously minute and different from the movement of the superimposed object; and a correction suppression unit (35) that reduces or stops the correction of the display position by the road surface unevenness correction unit when the correction inappropriate state determination unit determines that a correction inappropriate state exists.

14. A display control method for controlling a display position of a virtual image (40-42, 41a, 41b) that is superimposed on a superimposition object in a foreground visible to an occupant by projecting light onto a display area (PA) defined on a windshield (WS) of a vehicle, comprising: extracting information of a frequency band including a natural frequency (fe) of the vehicle as pitching attitude change information from an output signal of a vehicle pitch angle sensor (91 to 94) that detects an attitude change of the vehicle, and correcting a deviation of a display position of the virtual image with respect to the superimposition object based on the pitching attitude change information (S10, S20); When it is detected or predicted that the correction amount of the virtual image continues to be larger than a predetermined range of the display area, or the moving speed of the virtual image due to the correction becomes faster than a predetermined speed, or the movement of the virtual image due to the correction becomes continuously minute and different from the movement of the superimposed object, it is determined that the correction is inappropriate (S30); The display control method includes reducing or ceasing correction of the display position when it is determined that the correction is inappropriate (S50).

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