JP2015101189A - Onboard display device, head up display, control method, program, and memory medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an onboard display device which enables reduction of flickering in display which a user senses in a suitable manner.SOLUTION: MCU66 of a head up display 2 detects, on the basis of a line of sight information Ie, that a driver is not directing its line of sight to a combiner 9 that reflects the light constituting an image toward the driver of a vehicle Ve. The MCU66, when detecting that the driver is not directing its line of sight to the combiner 9, sets an image brightness Db independent of brightness of external light, so that flickering component of light is reduced than when the above stated state is not detected.

Description

  The present invention relates to a technique for reducing display flicker.

  2. Description of the Related Art Conventionally, in an in-vehicle display device, there is a technique for changing the luminance of a display screen in accordance with external light in order to compensate for a decrease in visibility due to the influence of external light. For example, Patent Document 1 discloses an in-vehicle display device that automatically adjusts the brightness of a display device according to a use time or a travel location without providing a sensor for detecting the brightness. Patent Document 2 discloses information that can control the display unit based on the brightness of external light detected by the optical sensor and an input value that is input to set display characteristics of the display unit. A display device is disclosed.

Japanese Patent Laid-Open No. 11-184446 JP-A-11-316566

  In the display devices described in Patent Literature 1 and Patent Literature 2, the brightness of the screen is controlled regardless of the direction of the user's line of sight. However, in general, when the display device enters the field of view without being directly looking, the user tends to feel flickering by the display device more sensitively than when the display device is directly looking. Patent Document 1 and Patent Document 2 do not discuss any of the above problems.

  The present invention has been made to solve the above-described problems, and a main object of the present invention is to provide an in-vehicle display device and a head-up display capable of suitably reducing display flickering felt by a user. And

  The invention described in the claims is an in-vehicle display device, and the driver does not direct or hardly direct the line of sight to a display surface that emits or reflects light constituting an image toward the driver of the vehicle. Detection means for detecting that the state is present, and control means for controlling the state of light emitted or reflected by the display surface, wherein the control means causes the driver to move the display surface to the display surface. When it is detected that the line of sight is not directed or is difficult to direct, the flicker component of the light is reduced as compared to when the state is not detected.

  The invention described in the claims is a control method executed by the vehicle display device, wherein the driver looks at the display surface that emits or reflects light constituting the image toward the driver of the vehicle. A detection step for detecting that the light is not directed or difficult to direct, and a control step for controlling the state of light emitted or reflected by the display surface, wherein the control step is performed by the detection step. The flicker component of the light is reduced compared to when the state is not detected when the driver detects that the line of sight is not directed to the display surface or is in a difficult state.

  The invention described in the claims is a program executed by a computer, and the driver does not point his / her line of sight toward a display surface that emits or reflects light constituting an image toward the driver of the vehicle. Or the detection means for detecting that the state is difficult to direct, and the control means for controlling the state of light emitted or reflected by the display surface, wherein the control means is configured to operate the operation by the detection means. The flicker component of the light is reduced when the person detects that the person is not turning his / her line of sight toward the display surface or is in a state where it is difficult to turn his eyes.

1 shows a schematic configuration of a display system according to a first embodiment. 1 shows a schematic configuration of a navigation device. 1 shows a schematic configuration of a head-up display. The schematic structure of a light source unit is shown. The flowchart which shows the process performed in 1st Example is shown. The flowchart which shows the process performed in 2nd Example is shown.

  In one preferred embodiment of the present invention, the driver does not turn his / her line of sight to the display surface that emits or reflects the light constituting the image toward the driver of the vehicle, or is in a state where it is difficult to direct. And a control means for controlling the state of light emitted or reflected by the display surface. The control means causes the driver to point the line of sight toward the display surface by the detection means. When it is detected that the state is not present or difficult to direct, the flicker component of the light is reduced as compared to when the state is not detected.

  The on-vehicle display device includes a detection unit and a control unit. The detection means detects that the driver does not direct his / her line of sight to the display surface that emits or reflects light constituting the image toward the driver of the vehicle. The control means controls the state of light emitted or reflected by the display surface. Further, when the detecting means detects that the driver is not turning his / her line of sight to the display surface or is in a difficult state, the control means reduces the light flicker component compared to when the state is not detected. Thereby, the vehicle-mounted display apparatus can suppress suitably the flicker which a user feels when a user visually recognizes a display surface by peripheral vision which is visions other than a gaze direction.

  In one aspect of the in-vehicle display device, the display device further includes an external light detection unit that detects the brightness of external light, and the control unit is configured to display the display surface according to the brightness of the external light when the state is not detected. The luminance displayed is changed, and when the state is detected, the luminance is not changed according to the brightness of the external light. Generally, when the brightness of a display that the user does not capture in the line-of-sight direction changes, the user tends to feel flicker. Therefore, according to this aspect, when the user visually recognizes the display surface in peripheral vision, the in-vehicle display device suitably suppresses the flicker felt by the user by suppressing a change in luminance of the image displayed on the display surface. be able to. In addition, when the user is looking directly at the display surface, the in-vehicle display device can improve the visibility by changing the luminance of the image displayed on the display surface according to the brightness of external light. it can.

  In another aspect of the in-vehicle display device, the control unit, when scanning the light with respect to the display surface, increases the refresh rate when detecting the state than when not detecting the state. . According to this aspect, when the user visually recognizes the display surface in peripheral vision, the in-vehicle display device can increase the refresh rate and suitably suppress flickering felt by the user.

  In another aspect of the in-vehicle display device, the detection unit detects that the driver is not turning his or her line of sight toward the display surface based on an image obtained by photographing the driver. According to this aspect, the in-vehicle display device can suitably determine whether or not the driver is in a state where the line of sight is not directed to the display surface.

  In another aspect of the in-vehicle display device, the detection means determines whether or not the driver is difficult to turn the line of sight toward the display surface based on ease of driving on the road on which the vehicle is traveling. Determine. According to this aspect, the in-vehicle display device can suitably determine whether or not the driver is in a state in which it is difficult for the driver to direct his / her line of sight to the display surface.

  In another preferred embodiment of the present invention, the head-up display visually recognizes a virtual image to the driver by reflecting any of the on-vehicle display devices described above and light constituting the image toward the driver of the vehicle. A display surface. In the head-up display, since the display on the display surface is always in the field of view of the driving user, the driving user often feels the display flickering troublesome. Even in this case, when it is detected that the driver does not turn his / her line of sight to the display surface or is difficult to turn, by reducing the flicker component of light than when the state is not detected, Flickering felt by the user when the user visually recognizes the display surface in peripheral vision can be suitably suppressed.

  In still another embodiment of the present invention, a control method executed by a vehicle display device, wherein the driver looks at a display surface that emits or reflects light constituting an image toward the driver of the vehicle. A detection step for detecting that the light is not directed or difficult to direct, and a control step for controlling the state of light emitted or reflected by the display surface, wherein the control step is performed by the detection step. When it is detected that the driver does not direct the line of sight to the display surface or is in a difficult state, the flicker component of the light is reduced compared to when the state is not detected. By executing this control method, the vehicle display device can suitably suppress flickering felt by the user when the user visually recognizes the display surface in peripheral vision.

  In still another embodiment of the present invention, the program is executed by a computer, and the driver does not point his / her eyes at a display surface that emits or reflects light constituting an image toward the driver of the vehicle. Or the detection means for detecting that the state is difficult to direct, and the control means for controlling the state of light emitted or reflected by the display surface, wherein the control means is configured to operate the operation by the detection means. When it is detected that the person is not directing the line of sight to the display surface or is in a difficult state, the flicker component of the light is reduced compared to when the state is not detected. By executing this program, the computer can suitably suppress flickering felt by the user when the user visually recognizes the display surface in peripheral vision. Preferably, the program is stored in a storage medium.

  Hereinafter, preferred first and second embodiments of the present invention will be described with reference to the drawings.

[First embodiment]
(1) System Configuration FIG. 1 shows a configuration example of a display system 100 according to the first embodiment. As shown in FIG. 1, the display system 100 is mounted on a vehicle Ve and includes a navigation device 1, a head-up display 2, a camera 6, and an external light sensor 7. Instead of the configuration shown in FIG. 1, the head-up display 2 may incorporate a function corresponding to the navigation device 1.

  The navigation device 1 has a function of performing route guidance from a departure place to a destination. The navigation device 1 can be, for example, a stationary navigation device installed in the vehicle Ve, a portable terminal such as a PND (Portable Navigation Device), or a smartphone.

  The head-up display 2 generates an image that displays map information including the current position, route guidance information, travel speed, and other information that assists driving, and the image is converted into a virtual image from the position (eye point) of the driver's eyes. It is a device for visual recognition. The head-up display 2 is supplied from the navigation device 1 with various information used for navigation processing such as the position of the vehicle, the traveling speed of the vehicle, map information, and facility data. The head-up display 2 may receive the image generated by the navigation device 1 instead of generating the above-described image, and cause the driver to visually recognize the image as a virtual image.

  The camera 6 is installed in a state directed toward the driver, generates an image of the driver (also referred to as “captured image Im”), and supplies the image to the head-up display 2. The external light sensor 7 supplies a detection signal (also referred to as “detection signal Sd”) indicating the brightness (illuminance) of external light to the head-up display 2.

  When the navigation device 1 is a mobile terminal such as a smartphone, the navigation device 1 may be held by a cradle or the like. In this case, the navigation device 1 may exchange information with the head-up display 2 via a cradle or the like.

(2) Configuration of Navigation Device FIG. 2 shows the configuration of the navigation device 1. As shown in FIG. 2, the navigation device 1 includes a self-supporting positioning device 10, a GPS receiver 18, a system controller 20, a disk drive 31, a data storage unit 36, a communication interface 37, a communication device 38, an interface 39, and a display unit 40. A voice output unit 50 and an input device 60.

  The autonomous positioning device 10 includes an acceleration sensor 11, an angular velocity sensor 12, and a distance sensor 13. The acceleration sensor 11 is made of, for example, a piezoelectric element, detects the acceleration of the vehicle Ve, and outputs acceleration data. The angular velocity sensor 12 is composed of, for example, a vibrating gyroscope, detects the angular velocity of the vehicle Ve when the direction of the vehicle Ve is changed, and outputs angular velocity data and relative azimuth data. The distance sensor 13 measures a vehicle speed pulse composed of a pulse signal generated with the rotation of the wheel of the vehicle Ve.

  The GPS receiver 18 receives radio waves 19 carrying downlink data including positioning data from a plurality of GPS satellites. The positioning data is used to detect the absolute position (also referred to as “current position”) of the vehicle Ve from latitude and longitude information.

  The system controller 20 includes an interface 21, a CPU (Central Processing Unit) 22, a ROM (Read Only Memory) 23, and a RAM (Random Access Memory) 24, and controls the entire navigation apparatus 1.

  The interface 21 performs an interface operation with the acceleration sensor 11, the angular velocity sensor 12, the distance sensor 13, and the GPS receiver 18. From these, vehicle speed pulses, acceleration data, relative azimuth data, angular velocity data, GPS positioning data, absolute azimuth data, and the like are input to the system controller 20. The CPU 22 controls the entire system controller 20. The ROM 23 includes a nonvolatile memory (not shown) in which a control program for controlling the system controller 20 is stored. The RAM 24 stores various data such as route data preset by the user via the input device 60 so as to be readable, and provides a working area to the CPU 22.

  A system controller 20, a disk drive 31 such as a CD-ROM drive or a DVD-ROM drive, a data storage unit 36, a communication interface 37, a display unit 40, an audio output unit 50, and an input device 60 are mutually connected via a bus line 30. It is connected to the.

  The disk drive 31 reads and outputs content data such as music data and video data from a disk 33 such as a CD or DVD under the control of the system controller 20. The disk drive 31 may be either a CD-ROM drive or a DVD-ROM drive, or may be a CD and DVD compatible drive.

  The data storage unit 36 is configured by, for example, an HDD and stores various data used for navigation processing such as map data. The map data includes road data represented by links corresponding to roads and nodes corresponding to road connecting portions (intersections), facility information about each facility, and the like.

  The communication device 38 is configured by, for example, an FM tuner, a beacon receiver, a mobile phone, a dedicated communication module, and the like, and via a communication interface 37, traffic jams distributed from a VICS (registered trademark, Vehicle Information Communication System) center Receive road traffic information such as traffic information and other information. In addition, the communication device 38 transmits to the head-up display 2 various information used for navigation processing, such as current position information acquired from the GPS receiver 18, information such as vehicle speed pulses acquired from the autonomous positioning device 10, and map data. To do.

  The display unit 40 displays various display data on a display device such as a display under the control of the system controller 20. Specifically, the system controller 20 reads map data from the data storage unit 36. The display unit 40 displays the map data read from the data storage unit 36 by the system controller 20 on the display screen. The display unit 40 includes a graphic controller 41 that controls the entire display unit 40 based on control data sent from the CPU 22 via the bus line 30 and a memory such as a VRAM (Video RAM), and can display image information that can be displayed immediately. A buffer memory 42 that temporarily stores, a display control unit 43 that controls display of a display 44 such as a liquid crystal display or a CRT (Cathode Ray Tube) based on image data output from the graphic controller 41, and a display 44 are provided. . The display 44 functions as an image display unit, and includes, for example, a liquid crystal display device having a diagonal of about 5 to 10 inches and is mounted near the front panel in the vehicle.

  The audio output unit 50 performs D / A (Digital to Analog) conversion of audio digital data sent from the CD-ROM drive 31, DVD-ROM 32, RAM 24, or the like via the bus line 30 under the control of the system controller 20. A D / A converter 51 to perform, an amplifier (AMP) 52 that amplifies the audio analog signal output from the D / A converter 51, and a speaker 53 that converts the amplified audio analog signal into sound and outputs the sound into the vehicle. It is prepared for.

  The input device 60 includes keys, switches, buttons, a remote controller, a voice input device, and the like for inputting various commands and data. The input device 60 is disposed around the front panel and the display 44 of the main body of the in-vehicle electronic system mounted in the vehicle. When the display 44 is a touch panel system, the touch panel provided on the display screen of the display 44 also functions as the input device 60.

(3) Configuration of Head-Up Display FIG. 3 is a schematic configuration diagram of the head-up display 2. As shown in FIG. 3, the head-up display 2 according to the present embodiment includes a light source unit 4 and a combiner 9. The vehicle Ve includes a front window 25, a ceiling portion 27, a hood 28, a dashboard 29, and the like. It is attached.

  The light source unit 4 is installed on the ceiling portion 27 in the passenger compartment via the support members 5a and 5b, and emits light constituting an image indicating information for assisting driving toward the combiner 9. Specifically, the light source unit 4 has a projection device 45, and the projection device 45 generates an original image (real image) of the display image in the light source unit 4 and emits light constituting the image to the combiner 9. Thus, the driver is caused to visually recognize the virtual image “Iv” via the combiner 9.

  The combiner 9 projects the display image emitted from the light source unit 4 and reflects the display image to the driver's eye point “Pe” to display the display image as a virtual image Iv. And the combiner 9 has the support shaft part 8 installed in the ceiling part 27, and rotates the support shaft part 8 as a spindle. The support shaft portion 8 is installed, for example, in the vicinity of the ceiling portion 27 in the vicinity of the upper end of the front window 25, in other words, the position where a sun visor (not shown) for the driver is installed. The support shaft portion 8 may be installed instead of the above-described sun visor. The reflecting surface of the combiner 9 is an example of the “display surface” in the present invention.

  In the example of FIG. 3, the camera 6 and the external light sensor 7 are integrally mounted on the dashboard 29. Then, the camera 6 and the external light sensor 7 transmit the captured image Im and the detection signal Sd to the light source unit 4 by wire or wirelessly.

(4) Configuration of Projection Unit FIG. 4 shows the configuration of the projection device 45 according to the first embodiment. As shown in FIG. 4, the projection device 45 includes an image signal input unit 62, a video ASIC 63, an MCU (Micro Control Unit) 66, a line-of-sight recognition unit 67, a laser driver IC 70, a MEMS mirror control unit 80, A frame memory 84, a ROM 85, a RAM 86, a laser light source 90, and a screen 94 are provided. The projection device 45 is an example of the “vehicle display device” in the present invention.

  The image signal input unit 62 generates an image signal indicating a guide image based on the guide route information received by the light source unit 4 from the navigation device 1 and outputs the image signal to the video ASIC 63. The video ASIC 63 controls the laser driver IC 70 and the MEMS mirror control unit 80 based on the image signal input from the image signal input unit 62 and the scanning position information input from the MEMS mirror 95 in the laser light source unit 90. And is configured as an ASIC (Application Specific Integrated Circuit). The video ASIC 63 includes a video processing unit 64 and a timing controller 65.

  The video processing unit 64 separates the image data and the synchronization signal displayed on the image display unit from the image signal input from the image signal input unit 62, and stores the image data for each frame included in the image signal in the frame memory 84. Write to. Further, the video processing unit 64 reads out the image data written in the frame memory 84 and converts it into bit data, and converts the converted bit data into a signal representing the light emission pattern of each laser. The timing controller 65 controls the operation timing of the video processing unit 64. The timing controller 65 also controls the operation timing of the MEMS mirror 95 via the MEMS mirror control unit 80.

  In the frame memory 84, the image data separated by the video processing unit 64 is written. The ROM 85 stores a control program and data for operating the video ASIC 63. Various data are sequentially read from and written into the RAM 86 as a work memory when the video ASIC 63 operates.

  The laser driver IC 70 is a block that generates a signal for driving a laser diode (LD) provided in the laser light source unit 90, and is configured as an IC (Integrated Circuit). The laser driver IC 70 includes a red laser driving circuit 71, a green laser driving circuit 72, and a blue laser driving circuit 73. The red laser driving circuit 71 drives the red laser LD1 based on the signal output from the video processing unit 64, and the green laser driving circuit 72 drives the green laser LD2 based on the signal output from the video processing unit 64, The blue laser driving circuit 73 drives the blue laser LD3 based on a signal output from the video processing unit 64.

  A MEMS mirror (Micro Electro Mechanical Systems) control unit 80 controls the MEMS mirror 95 based on a signal output from the timing controller 65. The MEMS mirror control unit 80 includes a servo circuit 81 and a driver circuit 82. The servo circuit 81 controls the operation of the MEMS mirror 95 based on the signal from the timing controller 65. The driver circuit 82 amplifies the control signal of the MEMS mirror 95 output from the servo circuit 81 to a predetermined level and outputs the amplified signal.

  The laser light source unit 90 emits laser light based on the drive signal output from the laser driver IC 70. Specifically, the laser light source unit 90 mainly includes a red laser LD1, a green laser LD2, a blue laser LD3, collimator lenses 91a to 91c, dichroic mirrors 92a to 92c, and a MEMS mirror 95. .

  The red laser LD1 emits red laser light, the green laser LD2 emits green laser light, and the blue laser LD3 emits blue laser light. Hereinafter, when the red laser LD1, the green laser LD2, and the blue laser LD3 are used without being distinguished from each other, they are simply referred to as “laser LD”, and the red laser light, the green laser light, and the blue laser light are used without being distinguished from each other. In this case, it is simply expressed as “laser light”. Further, in this specification, laser light is appropriately expressed as “beam”.

  The collimator lenses 91a, 91b, and 91c convert the red laser light, the green laser light, and the blue laser light into parallel lights and emit them to the dichroic mirrors 92a to 92c, respectively. The dichroic mirror 92b reflects green laser light, and the dichroic mirror 92a transmits green laser light and reflects red laser light. The dichroic mirror 92c transmits only blue laser light and reflects green laser light and red laser light. The blue laser light transmitted through the dichroic mirror 92 c and the green laser light and red laser light reflected by the dichroic mirror 92 c are incident on the MEMS mirror 95.

  The MEMS mirror 95 reflects the beam (laser light) incident through the dichroic mirror 92c as described above toward the screen 94. Specifically, the MEMS mirror 95 controls the beam under the control of the MEMS mirror control unit 80 so as to display an image composed of a plurality of continuous frames corresponding to the image input to the image signal input unit 62. Operates to scan the screen 94. Further, the MEMS mirror 95 outputs the scanning position information (for example, information such as the angle of the mirror) at that time to the video ASIC 63.

  More specifically, the MEMS mirror 95 scans the beam in the direction along the direction of the scanning line that forms the image to be displayed (corresponding to the horizontal direction in the image, and hereinafter referred to as “main scanning direction”). Rocks. Thereby, the scanning line which comprises the image which should be displayed is produced | generated. At the same time, the MEMS mirror 95 emits a beam in a direction perpendicular to the direction of the scanning line (which corresponds to the vertical direction in the image and is orthogonal to the main scanning direction, hereinafter referred to as “sub-scanning direction”). Swing to scan. Thereby, a predetermined number of scanning lines arranged in the sub-scanning direction are generated. As described above, the MEMS mirror 95 swings to form a single image (that is, a frame) that forms a moving image or the like. When the MEMS mirror 95 finishes scanning one frame as described above, the MEMS mirror 95 starts scanning the next frame and sequentially refreshes the projected frames. This frequency of refresh per unit time is called “refresh rate”.

  The screen 94 receives the beam reflected by the MEMS mirror 95. Therefore, the beam is scanned on the screen 94 by the operation of the MEMS mirror 95 as described above. For example, the screen 94 functions to form an intermediate image of the image to be displayed. In one example, a diffusing plate such as EPE (Exit-Pupil Expander) can be applied as the screen 94.

  The line-of-sight recognition unit 67 analyzes information indicating the driver's line-of-sight direction (“line-of-sight information”) by analyzing a region in which the driver's face is displayed in the captured image Im based on the captured image Im supplied from the camera 6. Ie "). In this case, for example, the line-of-sight recognition unit 67 detects the driver's line of sight using a known line-of-sight detection technique, and generates line-of-sight information Ie. Then, the line-of-sight recognition unit 67 supplies the line-of-sight information Ie to the MCU 66.

  The MCU 66 controls the video processing unit 64 in the video ASIC 63 based on the line-of-sight information Ie received from the line-of-sight recognition unit 67 and the detection signal Sd received from the external light sensor 7. In the present embodiment, the MCU 66 uses a video so that the brightness of the projected image (also referred to as “image brightness Db”) changes according to the brightness of the external light indicated by the detection signal Sd in order to improve visibility. The ASIC 63 and the like are controlled. Further, the MCU 66 switches the presence / absence of automatic adjustment of the image luminance Db based on the above-described detection signal Sd according to the line-of-sight information Ie supplied from the line-of-sight recognition unit 67. Details of the control performed by the MCU 66 will be described later. The MCU 66 is an example of the “detection unit”, “control unit”, “external light detection unit”, and “computer” in the present invention.

(5) Image Luminance Adjustment Next, an image luminance Db adjustment method executed by the MCU 66 in the first embodiment will be described. Schematically, when the MCU 66 determines that the driver's line of sight is not suitable for the image displayed by the combiner 9 (also simply referred to as “display image”) based on the line-of-sight information Ie, the detection signal Sd. The image brightness Db based on the above is not automatically adjusted. Thereby, MCU66 suppresses suitably that the flickering of a display image is conspicuous when the driver | operator concentrates on driving | running | working seeing the front scenery.

  In general, in human visual angle characteristics, when capturing flickering light (flicker light) in the central vision, which is visual in the line of sight, and when capturing flicker light in peripheral vision, which is visual other than the visual field direction, Peripheral vision is known to be more sensitive to flickering caused by blinking. Therefore, when the brightness of the display that is not in the direction of the user's line of sight changes, the user can easily feel the flicker of the display. In particular, since the image displayed by the head-up display 2 is always displayed within the field of view of the driving user, the driving user often feels annoying the flickering of the display image.

  Considering the above, the MCU 66 does not automatically adjust the image luminance Db based on the detection signal Sd when it is determined that the driver's line of sight is not suitable for the display image. Thereby, when the driver looks at the front scenery and concentrates on driving, it is possible to suitably suppress the flickering of the display image due to switching of the image luminance Db.

  FIG. 5 is a flowchart showing the image brightness Db adjustment processing executed by the MCU 66 in the first embodiment. The MCU 66 repeatedly executes the processing of the flowchart shown in FIG.

  First, the MCU 66 acquires the line-of-sight information Ie generated by the line-of-sight recognition unit 67 based on the captured image Im (step S101). Next, the MCU 66 determines whether or not the driver's line of sight is directed to the display image based on the line-of-sight information Ie (step S102). For example, the MCU 66 stores in advance information on the line-of-sight direction when the driver is looking at the display image, and compares the line-of-sight direction indicated by the line-of-sight information Ie with the previously stored line-of-sight direction. It is determined whether or not the driver's line of sight is directed to the display image.

  When the MCU 66 determines that the driver's line of sight is directed to the display image (step S102; Yes), the MCU 66 automatically adjusts the image luminance Db according to the brightness of the external light indicated by the detection signal Sd ( Step S103). For example, the MCU 66 can make the display image easily viewable according to the brightness of the external light by increasing the image brightness Db as the external light is brighter.

  On the other hand, when the driver's line of sight is not directed to the display image (step S102; No), the MCU 66 fixes the image luminance Db to a predetermined value regardless of the brightness of the external light (step S104). In this case, the MCU 66 may fix the image luminance Db to the luminance value of the image luminance Db that was set when the process of step S103 was last performed, or may fix the image luminance Db to a predetermined luminance value. May be. In the latter case, the MCU 66 may make the display image less noticeable by setting the image brightness Db to a relatively low value (for example, 20% of the maximum brightness). Thereby, MCU66 can suppress the flicker of the display image resulting from switching of the image brightness | luminance Db, and can concentrate a driving | operation on a driver | operator.

  As described above, the MCU 66 of the head-up display 2 according to the first embodiment does not direct the driver's line of sight to the combiner 9 that reflects the light constituting the image toward the driver of the vehicle Ve. Is detected based on the line-of-sight information Ie. When the MCU 66 detects that the driver is not looking at the combiner 9, the MCU 66 sets the image luminance Db regardless of the brightness of the outside light, so that the above state is not detected. Rather than reducing the flickering component of light. Thereby, flickering felt by the user when the user visually recognizes the display image in peripheral vision can be suitably suppressed.

[Second Embodiment]
In the second embodiment, the MCU 66 is different from the first embodiment in that the refresh rate is switched instead of or in addition to switching whether or not the image brightness Db is automatically adjusted. Specifically, in the second embodiment, the MCU 66 increases the refresh rate when the driver's line of sight is not facing the display image, compared to when the driver's line of sight is facing the display image. As a result, as in the first embodiment, the MCU 66 suitably suppresses the flickering of the display image from being noticeable when the driver concentrates on driving while looking at the front scenery. In addition, about the part similar to 1st Example, the same code | symbol is attached | subjected suitably and the description is abbreviate | omitted.

  In general, surface-emitting display elements such as organic EL displays and LCDs, that is, display elements are formed of fixed pixels, and CRTs and laser projectors are used rather than display elements that display images when each fixed pixel emits light. Scan type display elements such as the above, that is, display elements that display an image by scanning a spot of light at a high speed are more likely to cause flicker. Since the projection device 45 of the head-up display 2 is the latter scan type display element, the driver is relatively likely to feel flicker. In addition, as described in the first embodiment, flickering due to blinking is more likely to be felt in peripheral vision than in central vision. Therefore, even if the user of the head-up display 2 does not feel flicker when viewing the display image by central vision, the user may feel flicker when viewing the display image by peripheral vision.

  In consideration of the above, when the driver's line of sight is not suitable for the display image, the MCU 66 increases the refresh rate to a predetermined rate at which the user does not feel the flicker of the display image even in peripheral vision. The above-mentioned predetermined rate is set based on, for example, experiments, and is stored in advance by the MCU 66 or the like. Thereby, the flickering of the display image in peripheral vision can be suitably suppressed.

  FIG. 6 is a flowchart showing the image brightness Db adjustment processing executed by the MCU 66 in the second embodiment. The MCU 66 repeatedly executes the processing of the flowchart shown in FIG.

  First, the MCU 66 acquires the line-of-sight information Ie generated by the line-of-sight recognition unit 67 based on the captured image Im, as in the first embodiment (step S201). Then, the MCU 66 determines whether or not the driver's line of sight is directed to the display image based on the line-of-sight information Ie (step S202).

  When the driver's line of sight is directed to the display image (step S202; Yes), the MCU 66 sets the refresh rate to a normal rate (for example, 60 Hz) (step S203). On the other hand, when the driver's line of sight is not directed to the display image (step S202; No), the MCU 66 sets the refresh rate higher than the normal rate (step S204). For example, in this case, the MCU 66 refreshes by increasing the scanning speed in the main scanning direction, which is the direction along the scanning line direction, and the scanning speed in the sub-scanning direction perpendicular to the main scanning direction by 20%. Increase the rate by 20% (up to 72 Hz if the normal rate is 60 Hz). Thereby, the flickering of the display image in peripheral vision can be suitably suppressed.

  As another method for suppressing the flicker, a refresh rate (that is, a step in which the user does not feel the flicker of the display image even in peripheral vision, regardless of whether or not the driver's line of sight is directed to the display image). A method of fixing to the refresh rate used in S204 is also conceivable. However, in this case, since the number of times of driving the MEMS mirror 12 increases, the product life may be shortened and the power consumption may increase. On the other hand, in the control method of FIG. 6, the MCU 66 limits the period during which the refresh rate is increased. Therefore, the flickering of the display image in peripheral vision is preferably suppressed while minimizing the influence of the above-described problem. Can be suppressed.

  Note that the head-up display 2 of the second embodiment may not have the function of automatically adjusting the image luminance Db based on the brightness of external light. Further, the second embodiment can be suitably combined with the first embodiment. In this case, when the MCU 66 determines that the driver's line of sight is not directed to the display image, the MCU 66 stops the automatic adjustment of the image luminance Db based on the detection signal Sd and increases the refresh rate from the normal rate.

  As described above, the MCU 66 of the head-up display 2 according to the second embodiment is such that the driver does not point his / her eyes at the combiner 9 that reflects the light constituting the image toward the driver of the vehicle Ve. Is detected based on the line-of-sight information Ie. When the MCU 66 detects that the driver is not looking at the combiner 9, the MCU 66 sets the refresh rate higher than the normal rate, thereby making the light flicker component more than when the above state is not detected. Decrease. Thereby, similarly to the first embodiment, flickering felt by the user when the user visually recognizes the display image in peripheral vision can be suitably suppressed.

[Modification]
Hereinafter, modified examples suitable for the first and second embodiments will be described. The following modifications may be applied in any combination to the above-described embodiments.

(Modification 1)
In the first and second embodiments, when the MCU 66 determines in step S102 in FIG. 5 or step S202 in FIG. 6 that the driver's line of sight is not directed to the display image, the MCU 66 displays the display image in peripheral vision. Processing to reduce flicker was performed. Instead, the MCU 66 may perform a process of reducing flickering of the display image in the peripheral vision when the driver determines that the driving state is difficult to direct the line of sight to the display image.

  In this case, for example, the navigation device 1 transmits information related to the ease of driving on the road on which the vehicle Ve is currently traveling (also referred to as “traveling road”) to the MCU 66 of the head-up display 2. For example, the navigation device 1 has a case where the traveling road has a sharp curve, the road width of the traveling road is narrower than a predetermined width, the traveling road is a mountain road, and / or the traveling road has a gradient of a predetermined angle or more. In addition, the travel road is recognized as a road that is difficult to drive, and information to that effect is transmitted to the MCU 66. Then, the MCU 66 determines that it is difficult for the driver to concentrate on driving when the information indicating that the traveling road is a road that is difficult to drive is received from the navigation apparatus 1, and that it is difficult to direct the line of sight to the display image. Processing to reduce flickering of the display image in peripheral vision is performed.

  Here, specific methods (first to third methods) in which the navigation device 1 determines whether or not the traveling road is a road that is difficult to drive will be described.

  In the first method, for each link stored in the map data, the data storage unit 36 stores in advance flag information indicating whether the road indicated by the link is a road that is difficult to drive as map data. Keep it. Then, when the system controller 20 recognizes a link corresponding to the traveling road based on the outputs of the autonomous positioning device 10 and the GPS receiver 18, the system controller 20 refers to flag information associated with the link on the map data, It is determined whether or not the traveling road is a road that is difficult to drive.

  In the second method, the system controller 20 determines whether or not the traveling road is a road that is difficult to drive based on the output of the autonomous positioning device 10 and the positioning history of the current position by the GPS receiver 18. For example, the system controller 20 recognizes the road gradient of the traveling road based on the output of the acceleration sensor 11 or the like, and recognizes that the traveling road is a road that is difficult to drive when the gradient is equal to or greater than a predetermined angle. In another example, the system controller 20 determines that the vehicle Ve is traveling along a sharp curve when an angular velocity greater than a predetermined value is detected based on the output of the angular velocity sensor 12 or the like, and the traveling road is driven. Recognize that it is a difficult road.

  In the third method, instead of the flag information of the first method, for each link, road width information, inclination angle information, and / or curve curvature information indicated by the link are stored in the data storage unit 36. Is stored as map data. Further, the data storage unit 36 stores a range (value range) in which it is determined that the traveling road is a difficult road for each of the above-described road width information, inclination angle information, and the like. Then, the system controller 20 refers to road width information associated with the link corresponding to the recognized traveling road, and any of them corresponds to a range in which it is determined that the traveling road is difficult to drive. In this case, the travel road is recognized as a road that is difficult to drive.

(Modification 2)
Instead of the information related to the ease of driving described in the first modification, the navigation device 1 may transmit information related to the ease of changing external light on the traveling road to the MCU 66.

  For example, when the vehicle Ve is traveling on a road between forests or a road sandwiched adjacent to the road during the day, the navigation device 1 is likely to change the outside light. Information indicating that the road is a road is transmitted to the MCU 66. Then, when the MCU 66 receives information from the navigation device 1 that the traveling road is a road that easily changes outside light, the MCU 66 stops the automatic adjustment of the image luminance Db based on the detection signal Sd. In this case, for example, as in the first method of the first modification, for each link stored in the map data, flag information indicating whether the road is easily changed by external light is used as the map data as a data storage unit. 36 is stored in advance.

(Modification 3)
In FIG. 3, the head-up display 2 has a combiner 9 and makes the driver visually recognize the virtual image Iv based on the emitted light of the light source unit 4 reflected by the combiner 9. However, the configuration to which the present invention is applicable is not limited to this. Instead of this, the head-up display 2 may not have the combiner 9 and may allow the driver to visually recognize the virtual image Iv based on the emitted light of the light source unit 4 reflected by the windshield 25. In this case, the reflection surface of the windshield 25 is an example of the “display surface” in the present invention.

  Further, the position of the light source unit 4 is not limited to the case where it is installed on the ceiling portion 27. Instead of this, the light source unit 4 may be installed on the dashboard 29 or installed inside the dashboard 29. When installed on the dashboard 29, the combiner 9 is provided on the dashboard 29, or light is directly reflected from the light source unit 4 on the windshield 25 to allow the driver to recognize the virtual image Iv. When installed in the dashboard, the dashboard 29 is provided with an opening for allowing light to pass through the combiner 9 or the windshield 25.

(Modification 4)
The display system 100 performs a process of reducing flickering on the display image of the head-up display 2. However, the configuration to which the present invention is applicable is not limited to this. For example, instead of this, the display system 100 may not include the head-up display 2, and the system controller 20 of the navigation device 1 may perform a process of reducing flicker on the display 44. Even in this case, it is possible to suitably suppress the flickering of the screen of the display 44 when the driver is concentrating on driving while looking at the forward scenery. In this case, the display 44 of the display unit 40 is an example of the “display surface” in the present invention. The navigation device 1 is an example of the “in-vehicle display device” in the present invention, and the system controller 20 includes the “detection unit”, “control unit”, “external light detection unit”, and “computer” in the present invention. It is an example.

(Modification 5)
In the configuration example of the display system 100 in FIG. 1, the camera 6 and the external light sensor 7 are connected to the head-up display 2. Instead of this, the camera 6 and / or the external light sensor 7 may be connected to the navigation device 1.

  In this case, for example, the navigation device 1 transfers the captured image Im or / and the detection signal Sd received from the camera 6 or / and the external light sensor 7 to the projection device 45 of the head-up display 2. In another example, the navigation device 1 generates the line-of-sight information Ie by performing the process executed by the line-of-sight recognition unit 67 based on the captured image Im received from the camera 6, and transmits the line-of-sight information Ie to the projection device 45. . In yet another example, the navigation device 1 generates the line-of-sight information Ie based on the captured image Im received from the camera 6, and then determines whether or not to further reduce the flickering of the display image. An instruction signal indicating whether or not to perform the process of reducing the flicker of the image is transmitted to the projection device 45.

  Thus, even when the navigation device 1 executes part of the processing executed by the projection device 45, the display system 100 preferably executes processing for reducing flickering of the display image in peripheral vision. be able to. In this case, the system controller 20 of the navigation device 1 is an example of the “detection unit” in the present invention.

(Modification 6)
5 and 6, the line-of-sight recognition unit 67 generates line-of-sight information Ie indicating the driver's line-of-sight direction and transmits it to the MCU 66. The MCU 66 directs the driver to the display image based on the line-of-sight information Ie. It was determined whether or not. Instead of this, the line-of-sight recognition unit 67 may further determine whether or not the driver is directing his / her line of sight to the display image after recognizing the driver's line-of-sight direction, and transmit the determination result to the MCU 66. In this case, the MCU 66 does not need to determine whether or not the driver is looking at the display image.

DESCRIPTION OF SYMBOLS 1 Navigation apparatus 2 Head-up display 4 Light source unit 9 Combiner 25 Windshield 28 Bonnet 29 Dashboard 100 Display system

Claims (9)

Detection means for detecting that the driver is not turning his / her line of sight to a display surface that emits or reflects light constituting an image toward the driver of the vehicle,
Control means for controlling the state of light emitted or reflected by the display surface,
The control means detects the flicker component of the light more than when the state is not detected when the detection means detects that the driver does not direct the line of sight to the display surface or is in a difficult state. An in-vehicle display device characterized by being reduced. It further comprises external light detection means for detecting the brightness of external light,
The control means changes the luminance of the image displayed on the display surface according to the brightness of the external light when the state is not detected, and changes the luminance when the state is detected. The in-vehicle display device according to claim 1, wherein the on-vehicle display device is not changed according to the height.   3. The control unit according to claim 1, wherein when the light is scanned with respect to the display surface, the control unit increases a refresh rate when the state is detected, compared with when the state is not detected. The on-vehicle display device described. 4. The detection unit according to claim 1, wherein the detection unit detects, based on an image of the driver, that the driver is not turning his / her line of sight toward the display surface. 5. The vehicle-mounted display device according to one item.   The detection means determines whether or not the driver is in a state in which it is difficult for the driver to turn his / her line of sight on the display surface based on ease of driving on a road on which the vehicle is traveling. The vehicle-mounted display apparatus as described in any one of thru | or 3. The in-vehicle display device according to any one of claims 1 to 5,
A head-up display, comprising: a display surface that reflects light constituting an image toward a driver of a vehicle so that the driver can visually recognize a virtual image. A control method executed by a vehicle display device,
A detection step of detecting that the driver is not turning his / her line of sight to the display surface which emits or reflects light constituting the image toward the driver of the vehicle,
A control step of controlling the state of light emitted or reflected by the display surface,
The control step detects the flicker component of the light more than when the state is not detected when the detection step detects that the driver does not direct the line of sight to the display surface or is in a difficult state. A control method characterized by subtracting. A program executed by a computer,
Detection means for detecting that the driver is not turning his / her line of sight to a display surface that emits or reflects light constituting an image toward the driver of the vehicle,
Causing the computer to function as control means for controlling the state of light emitted or reflected by the display surface;
The control means detects the flicker component of the light more than when the state is not detected when the detection means detects that the driver does not direct the line of sight to the display surface or is in a difficult state. A program characterized by subtracting.   A storage medium storing the program according to claim 8.

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