Display control device

Abstract

To provide a display control device capable of more appropriately controlling the luminance of a display on the basis of a visual line direction of a driver without impairing the convenience of the driver.SOLUTION: A human machine interface control unit (HCU) determines, on the basis of a line-of-sight distribution of a driver in a predetermined period after start of traveling, a front line-of-sight range being a range of a line-of-sight vertical angle when the driver directs his or her line of sight to the front of a vehicle. Then, the HCU determines a standby threshold being a threshold for changing the luminance of a display with reference to a center or a lower end of the front line-of-sight range. When the line-of-sight vertical angle of the driver is equal to or greater than the standby threshold, the HCU sets the luminance of the display to a standby level. Meanwhile, when the line-of-sight vertical angle of the driver is below the standby threshold, the HCU sets the luminance of the display to a normal level.SELECTED DRAWING: Figure 8

Description

Technical Field

[0001] The present disclosure relates to a display control device that controls the brightness used for information display on a vehicle display.

Background Art

[0002] Patent Document 1 discloses a configuration in which when it is determined that the driver is looking at the display, the brightness used for the display is set to the amount of light for visual recognition, and when it is determined that the driver is not looking at the display, the amount of light is set to a standby light amount lower than the amount of light for visual recognition. Thereby, reduction of the power consumption of the display is achieved.

[0003] Patent Document 2 discloses a technique for correcting the reference of the driver's line-of-sight direction by allowing the driver to visually recognize an icon displayed on the display before the start of driving of the vehicle (in other words, at the time of departure).

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In order to properly implement brightness control based on gaze direction, as disclosed in Patent Document 1, it is necessary to appropriately set criteria (e.g., thresholds) for determining whether the driver is looking ahead or at the display. If the criteria for determining whether the driver is looking ahead or at the display are inappropriate, the screen may remain bright even when the driver is looking ahead (in other words, not at the display), potentially preventing a reduction in power consumption. Alternatively, the screen may remain dark even when the driver is looking at the display, potentially degrading the visibility of the displayed content.

[0006] Patent Document 1 does not describe any method for setting criteria for determining whether or not a driver is looking ahead to the vehicle. One possible configuration is one in which the system determines that the driver is looking ahead to the vehicle if the driver's gaze direction falls within a predetermined angle range that has been designed in advance. However, there are individual differences in the direction of a driver's gaze when they are looking ahead. Therefore, it is difficult to pre-design appropriate criteria that can be applied to a large number of people.

[0007] As described in Patent Document 2, a configuration that learns the driver's gaze direction before the vehicle starts moving may allow for the setting of appropriate judgment criteria according to the driver's physique, etc. However, with this method, the driver needs to register their gaze direction with the system before starting to move, which may reduce the driver's convenience.

[0008] This disclosure is based on the above considerations or observations, and one of its purposes is to provide a display control device that can more appropriately control the brightness of the display based on the driver's gaze direction without impairing the driver's convenience. [Means for solving the problem]

[0009] The display control device disclosed herein comprises a receiving unit (24) that receives data indicating the direction of the vehicle driver's gaze, and a control unit (21) that controls the brightness of a display installed in the vehicle based on the data received by the receiving unit. The control unit is configured to perform the following actions based on the distribution information of gaze directions received by the receiving unit within a predetermined period after the vehicle starts running: identify a forward gaze range, which is the range of gaze directions corresponding to the state in which the driver is looking forward at the vehicle; set the brightness to a normal level based on the gaze direction being outside the forward gaze range; and set the brightness to a standby level lower than the normal level based on the gaze direction being within the forward gaze range.

[0010] In the above-described display control device, the forward gaze range is determined based on the distribution of the driver's gaze direction after driving begins, and the display brightness is controlled using this determined forward gaze range. With this configuration, the display brightness is controlled based on criteria that correspond to the driver's physique, etc., making it possible to control the display brightness more appropriately based on the driver's gaze direction. Furthermore, the driver does not need to register their gaze direction before driving begins. Therefore, the risk of impairing driver convenience is also reduced. In short, it is possible to control the display brightness more appropriately based on the driver's gaze direction without impairing driver convenience.

[0011] The reference numerals in parentheses in the claims indicate the correspondence with the specific means described later in the embodiments, and do not limit the technical scope of this disclosure. [Brief explanation of the drawing]

[0012] [Figure 1] This is a block diagram showing the overall configuration of the in-vehicle system. [Figure 2] This figure shows an example of the position and shape of a display. [Figure 3] This figure shows an example of the mounting location for the crew monitor. [Figure 4] This is a functional block diagram of the HCU. [Figure 5] It is a diagram showing an example of the distribution of the vertical and horizontal angles of the line of sight. [Figure 6] It is a diagram for explaining a method of specifying a display line-of-sight range based on the distribution of the vertical and horizontal angles of the line of sight. [Figure 7] It is a diagram for explaining a method of determining a standby threshold based on the distribution of fixation points. [Figure 8] It is a flowchart showing the operation of a processor related to setting the standby threshold. [Figure 9] It is a flowchart showing the operation of a processor related to the brightness control of a display. [Figure 10] It is a diagram showing an example of controlling the brightness level of a display according to the vertical and horizontal angles of the line of sight. [Figure 11] It is a diagram showing another example of controlling the brightness level of a display according to the vertical and horizontal angles of the line of sight. [Figure 12] It is a flowchart showing the operation of the HCU when displaying a warning image. [Figure 13] It is a flowchart for explaining the operation of the HCU related to adjusting the standby threshold. [Figure 14] It is a diagram showing another configuration example of an in-vehicle display.

Embodiments for Carrying Out the Invention

[0013] Hereinafter, embodiments of the present disclosure will be described with reference to the drawings. The present disclosure is not limited to the following embodiments, and various modifications described hereinafter are also included in the technical scope of the present disclosure. Further, various changes can be made and implemented within the scope not departing from the gist other than the following. Various supplements and modifications can be appropriately combined and implemented within the range where no technical contradiction occurs. For members having the same function, the same reference numerals may be given, and the description thereof may be omitted. Also, when only a part of the configuration is mentioned, the description described elsewhere can be applied to other parts.

[0014] FIG. 1 is a diagram showing an example of a schematic configuration of an in-vehicle system 100 to which the present disclosure is applied. As shown in FIG. 1, the in-vehicle system 100 includes a display 11, an occupant monitor 12, a vehicle state sensor 13, a locator 14, a driving support device 15, an input device 16, and an HCU (HMI Control Unit) 20. HMI is an abbreviation for Human Machine Interface.

[0015] The display 11 is directly connected to the HCU 20 using a cable. The occupant monitor 12, the vehicle state sensor 13, the locator 14, the driving support device 15, and the input device 16 are communicably connected to the HCU 20 via an in-vehicle network 101. The in-vehicle network 101 is a communication network constructed inside the vehicle. The standard of the in-vehicle network 101 may be any standard such as Controller Area Network (CAN is a registered trademark), Ethernet (registered trademark), FlexRay (registered trademark), etc. The network topology shown in FIG. 2 is an example and may be changed as appropriate.

[0016] The display 11 is a display device provided on the instrument panel. The display 11 is configured to be capable of full-color display. The display 11 displays an image according to an input signal from the HCU 20.

[0017] In the present embodiment, as shown in FIG. 2, the display 11 is continuously formed from the right end to the left end of the instrument panel at the upper end of the instrument panel. Such a display 11 can also be called a pillar-to-pillar display. The display 11 may have a display screen with a width of 0.5 m or more. The display 11 may be configured to be capable of displaying a plurality of screens (windows) for different functions in parallel. The display 11 may be capable of displaying, in parallel, a meter window showing the traveling speed and the like, a navi window showing a navigation image, and an audio window displaying information related to an audio function, based on an instruction from the HCU 20.

[0018] The display screen of display 11 may be divided, either physically or virtually, into a driver area, a passenger area, and a central area. The driver area is the area directly in front of the driver's seat. The passenger area is the area located directly in front of the passenger seat. The central area refers to the display area between the driver area and the passenger area. The aforementioned meter window may be located in the driver area.

[0019] The display 11 may be a liquid crystal display with a partially dimmable direct-lit backlight. The display 11 may also be an organic EL display. The display 11 may also be an edge-type liquid crystal display with independent light sources in the center, right edge, and left edge, for example.

[0020] The display 11 of this embodiment includes one or more light sources. The light sources may be provided independently of the image elements, such as the backlight in a liquid crystal display. Alternatively, the light sources may be individual image elements that constitute a self-emissive display, such as an organic EL display.

[0021] The display 11 is configured to allow uniform adjustment of the brightness (i.e., luminance) of the entire display screen. For example, the display 11 is configured to allow stepwise adjustment of luminance from a luminance of 0 to a predetermined normal level. Here, the normal level refers to a luminance value at which the driver can sufficiently recognize the displayed content and which does not cause glare. The specific value of the normal level may be designed as appropriate.

[0022] The normal level may be configured to be adjustable by the driver via a predetermined settings screen. A brightness of 0 means that the lights are completely off and nothing is displayed. Naturally, the normal level in night display mode and the normal level in day display mode may have different physical light quantities (cd), etc. The night display mode is a display mode that is applied when the illuminance outside the vehicle is below a predetermined value, such as at night or in a tunnel, or when the headlights are on. The day display mode is a display mode that is applied when the illuminance outside the vehicle is above a predetermined value or when the headlights are off. The display 11 may also be configured to allow partial adjustment of the brightness (i.e., luminance) of the display screen.

[0023] The occupant monitor 12 is a sensor for detecting the driver's gaze direction. The occupant monitor 12 may be a visible light / infrared camera installed in the vehicle interior in a position to capture images of the driver's face. As shown in Figure 3, the occupant monitor 12 is positioned on the upper surface of the steering column cover with its optical axis directed towards the headrest of the driver's seat. Of course, the occupant monitor 12 may also be mounted on the upper surface of the instrument panel, the upper edge of the windshield, or the A-pillar on the driver's side. The occupant monitor 12 may also be mounted on the upper edge of the display 11. In Figure 3, the dashed line indicates the optical axis of the occupant monitor 12, and the dashed line indicates the shooting range. The solid arrow in Figure 3 indicates the driver's gaze direction.

[0024] The occupant monitor 12 sequentially detects the driver's state by analyzing the driver's face image included in the captured video. The driver's state may include the driver's face orientation (neck angle) and eye opening. The occupant monitor 12 also detects the driver's gaze direction through image analysis. The gaze direction may be detected in various ways. For example, the occupant monitor 12 may detect the driver's gaze direction by combining the driver's face orientation vector and the eye orientation vector relative to the face. The gaze direction may be expressed relative to the vehicle or relative to the optical axis of the occupant monitor 12.

[0025] The line of sight direction may be expressed, for example, as the vertical angle of sight and the horizontal angle of sight. The vertical angle of sight corresponds to the vertical component of the driver's line of sight direction. The horizontal angle of sight corresponds to the horizontal component of the driver's line of sight direction. In this embodiment, the vertical angle of sight is assumed to increase upwards (positive direction), and the horizontal angle of sight is assumed to increase to the right (positive direction). The vertical angle of sight may be the angle that the line of sight direction makes with respect to the vehicle horizontal plane. The vehicle horizontal plane refers to a plane perpendicular to the vertical direction of the vehicle, in other words, a plane parallel to the longitudinal and lateral directions of the vehicle. The vertical angle of sight may be rephrased as the line of sight pitch angle or line of sight elevation angle. The horizontal angle of sight may be rephrased as the line of sight yaw angle.

[0026] The occupant monitor 12 sequentially outputs data indicating the driver's status, identified based on the captured images, to the HCU 20. The HCU 20 may, for example, have a function to detect the driver's status based on the camera's video signal. Alternatively, the occupant monitor 12 may be a millimeter-wave radar / LiDAR configured to detect the direction of the driver's face.

[0027] The vehicle state sensor 13 is a group of sensors that detect information about the state of the vehicle. The vehicle state sensor 13 includes a vehicle speed sensor, a steering angle sensor, etc. The vehicle speed sensor is a sensor that detects the vehicle's speed. The steering angle sensor is a sensor that detects the steering angle. The vehicle state sensor 13 inputs a signal to the HCU 20 indicating the current value (i.e., the detection result) of the physical state quantity to be detected. The vehicle state sensor 13 may also include a turn signal switch and a parking brake switch. The HCU 20 may receive signals indicating the operation status of the turn signals, signals indicating the operation status of the parking brake, etc. The types of sensors connected to the HCU 20 may be designed as appropriate.

[0028] Locator 14 is a device that generates highly accurate positional information for its own vehicle by combining multiple pieces of information through composite positioning. The vehicle's positional information may be represented by three-dimensional coordinates of latitude, longitude, and altitude. Locator 14 may be equipped with a GNSS receiver and a map storage device. The GNSS receiver is a device that sequentially detects its current position by receiving navigation signals (hereinafter referred to as positioning signals) transmitted from positioning satellites that constitute the GNSS (Global Navigation Satellite System). The map storage device is a storage medium in which map data showing the road network is stored. Locator 14 may calculate the vehicle's position by combining the positioning result of the GNSS receiver, the output of the acceleration sensor, and the map data.

[0029] The vehicle's position information calculated by the locator 14 is output to the in-vehicle network 101 and referenced by the HCU 20, etc. The locator 14 may also output forward road data to the HCU 20, indicating the remaining distance to intersections, merging / diverging points, and railroad crossings determined from map data and current position information. In this embodiment, the locator 14 is a device different from a navigation device, but in other embodiments, the locator 14 may be a navigation device.

[0030] The driver assistance device 15 is a device that performs control to assist the driver's driving based on the recognition results of the driving environment using surrounding monitoring sensors. The surrounding monitoring sensors are sensors that detect objects present within their detection range. The surrounding monitoring sensors may be cameras that image the outside of the vehicle, millimeter-wave radar, LiDAR (Light Detection and Ranging / Laser Imaging Detection and Ranging), or sonar. The driver assistance device 15 calculates parameters indicating the possibility of contact with an obstacle based on the output signals of the surrounding monitoring sensors that form a detection area in front of the vehicle (including diagonally in front), and may display a warning image or output a warning sound based on the calculation results. The parameters indicating the possibility of contact with an obstacle may be the time to collision (TTC).

[0031] The display of a warning image and the output of a warning sound may be achieved by outputting a warning request signal to the HCU 20. The HCU 20 may display a warning image, etc., based on the input of a warning request signal from the driver assistance device 15. The driver assistance device 15 may be a device that performs Autonomous Emergency Braking (AEB), which forcibly decelerates the vehicle based on the presence of an object whose TTC is below a predetermined value. The driver assistance device 15 may also be a device that recognizes traffic lights based on images captured by a front camera, which is a camera that takes pictures of the area in front of the vehicle, and provides warnings / notifications regarding the illuminated state.

[0032] The input device 16 is a device for receiving driver instructions and operations for the in-vehicle system 100. The input device 16 may be a steering wheel switch, a touch panel, a haptic device, etc. The input device 16 outputs an operation signal, which is an electrical signal corresponding to the driver's operation, to the HCU 20. The operation signal includes information indicating the content of the driver's operation. The HCU 20 controls the display of the display 11 based on the operation signal input from the input device 16.

[0033] HCU20 is a device that controls the display content and display brightness of the display 11 based on signals input from various sensors / devices. HCU20 corresponds to the display control device. HCU20 may be a system realized by the cooperation of multiple devices. HCU20 may be a computer equipped with a processor 21, memory 22, storage 23, communication interface 24, etc. The processor 21 is hardware for arithmetic processing coupled with the memory 22. The processor 21 includes at least one arithmetic core such as a CPU (Central Processing Unit) or GPU (Graphics Processing Unit). The processor 21 performs various arithmetic processes by accessing the memory 22. The memory 22 is volatile memory such as RAM (Random Access Memory). The processor 21 corresponds to the control unit.

[0034] Storage 23 is a non-volatile storage medium such as flash memory. Storage 23 stores a display control program, which is a program executed by the processor 21. When the processor 21 executes the display control program, it is equivalent to executing a display control method, which is a method corresponding to the display control program.

[0035] The communication interface 24 is a circuit for the processor 21 to communicate with other in-vehicle devices. The communication interface 24 includes a connector to which a communication cable is connected and a PHY chip compliant with the communication standards of the in-vehicle network 101. The communication interface 24 also includes a circuit for outputting video signals to the display 11 and a circuit for sending and receiving control signals to and from the display 11. The control signals include signals for adjusting the display brightness of the display 11. The communication interface 24 receives signals from various in-vehicle devices installed in the vehicle. The communication interface 24 receives signals indicating driving speed, signals indicating the operation status of the turn signals, signals indicating the driver's status (e.g., gaze direction), forward road data, warning request signals, etc. The communication interface 24 corresponds to the receiving unit.

[0036] The HCU20 provides functions corresponding to the various functional blocks shown in Figure 4 by executing the display control program stored in the storage 23. Specifically, the HCU20 includes a gaze acquisition unit F1, a threshold setting unit F2, and a display control unit F3 as functional blocks. In this disclosure, the gaze acquisition unit F1, threshold setting unit F2, display control unit F3, and HCU20 may be read as processor 21 as appropriate.

[0037] The gaze acquisition unit F1 periodically acquires data indicating the driver's gaze direction from the occupant monitor 12 while the vehicle power is on. The vehicle power is the power supply that is turned on when the vehicle is running. If the vehicle is an engine-powered vehicle, the ignition power corresponds to the vehicle power. If the vehicle is an electric vehicle or a hybrid vehicle, the system main relay corresponds to the vehicle power. The interval at which the gaze acquisition unit F1 acquires the gaze direction may be 1 second, 0.5 seconds, 1.5 seconds, etc. The data indicating the gaze direction is stored in memory 22 along with data indicating the acquisition time / acquisition order.

[0038] The gaze acquisition unit F1 may store data indicating the direction of gaze in association with data indicating the state of the vehicle at the time of data acquisition (hereinafter also referred to as vehicle state data). Specifically, the gaze acquisition unit F1 may store data indicating the direction of gaze in association with some or all of the driving speed, shift position, parking brake operation status, turn signal operation status, and steering angle at the time of data acquisition. If the vehicle is equipped with an autonomous driving function that allows for eyes-off, the vehicle state data may also include data indicating the operating status of the autonomous driving system. Autonomous driving that allows for eyes-off refers to autonomous driving at a level where the driver is not required to monitor the surroundings (so-called Level 3).

[0039] Furthermore, the gaze acquisition unit F1 may store data indicating the direction of gaze in association with data indicating the driving environment (hereinafter also referred to as driving environment data). The driving environment data may include, for example, the remaining distance to an intersection or the recognition status of traffic signals by the driver assistance device 15.

[0040] The HCU20 may also have a function to identify the driver's gaze direction from the facial image. In this disclosure, "acquisition" includes generating / detecting data (e.g., video signals) from other devices / sensors through internal calculations. This is because the functional arrangement within the system can be changed as appropriate. In this disclosure, the set of data showing the observed values ​​of the driver's gaze direction at multiple points in time, stored in memory 22, is also referred to as gaze history data. Data showing individual gaze directions is also referred to as gaze direction data. Multiple gaze direction data sets are acquired at different times.

[0041] The threshold setting unit F2 is configured to set a threshold (hereinafter referred to as the standby threshold) for reducing the brightness of the display 11 based on the gaze history data stored in the memory 22. The standby threshold may be understood as a threshold for the gaze direction for determining that the driver is not looking at the display 11. The standby threshold may be set based on the forward gaze range. In this disclosure, the forward gaze range is the range of vertical angles of the gaze when the driver is looking in front of the vehicle (forward direction). The standby threshold is set to be located above the display gaze range. The display gaze range indicates the range of vertical angles of the gaze that the driver can take when looking at the display 11. Various gaze ranges may be expressed by the upper limit (maximum value) and lower limit (minimum value) of the vertical angle of the gaze.

[0042] For example, the threshold setting unit F2 may identify the forward gaze range based on the gaze history data and set a waiting threshold based on its lower limit or median. Specifically, the threshold setting unit F2 may create data equivalent to a histogram of gaze directions within a certain period of time and set the class with the most occurrences as the center of the forward gaze range. The classes (divisions / bins) of gaze directions may be, for example, in increments of 2 degrees, 4 degrees, or 5 degrees.

[0043] Furthermore, the threshold setting unit F2 may consider the angle range that is within a certain value (α) from the median of the most frequently occurring class as the forward line of sight range. α may be 2.5 degrees, 3 degrees, 5 degrees, etc. For example, as shown in Figure 5, if the most frequent class is 0.1 degrees to 5.0 degrees, the forward line of sight range may be determined to be within ±3 degrees from its median of 2.5 degrees. The most frequent class is the class with the largest number of samples (frequency). The median of the most frequent class corresponds to the center of the forward line of sight range. Multiple classes for the vertical angle of sight correspond to multiple angle ranges.

[0044] The threshold setting unit F2 may set the standby threshold to an angle value that is a certain value below the median of the most frequent class, i.e., the center of the forward line of sight range. For example, the threshold setting unit F2 may set the standby threshold to -3.5 degrees, which is 2.5 degrees to 6 degrees lower. The threshold setting unit F2 may also set the standby threshold to the lower limit of the forward line of sight range, or an angle value that is a predetermined amount smaller than the lower limit of the forward line of sight range.

[0045] In another embodiment, as shown in Figure 6, the threshold setting unit F2 may determine the center of the display viewing range as the median of the class with the most frequent occurrences within a candidate region that is an angle range below a certain value (e.g., 5 degrees) or more below the median of the class with the most frequent occurrences. Figure 6 illustrates a case where an angle range of -2 degrees or less is set as the candidate region. In the example shown in Figure 6, the class that is greater than -8 degrees and less than or equal to -6 degrees is the most frequent class within the candidate region. In this case, -7 degrees corresponds to the center of the display viewing range. The threshold setting unit F2 may consider an angle range that is within a certain value from the center of the display viewing range as the display viewing range. Furthermore, the threshold setting unit F2 may set the upper limit of the display viewing range, or an angle value that is a certain value greater than the upper limit of the display viewing range, as the standby threshold.

[0046] Furthermore, the threshold setting unit F2 may identify the forward gaze range and the display gaze range by clustering the distribution of gaze direction / point of gaze as shown in Figure 7, and set a standby threshold between these clusters. Here, the point of gaze may be the direction in which the gaze has been continuously directed for a predetermined time (e.g., 0.8 seconds) or longer. The detection of the point of gaze may be performed by the occupant monitor 12 or by the HCU 20.

[0047] Cluster C1, shown in Figure 7, is a set of gaze points (cluster) corresponding to the state where the driver is looking forward. Cluster C2 is a set of gaze points corresponding to the state where the driver is looking at the driver area of ​​the display 11. Cluster C3 is a set of gaze points corresponding to the state where the driver is looking at the central area of ​​the display 11. Cluster C4 corresponds to the state where the driver is looking at the right side mirror, and cluster C5 corresponds to the state where the driver is looking at the left side mirror. Cluster C6 is a set of gaze points corresponding to the state where the driver is looking at the rearview mirror.

[0048] The processor 21 may consider the cluster with the most concentrated gaze points as the cluster corresponding to the state in which the driver is looking forward, and may identify the state of the driver corresponding to other clusters based on the positional relationship with that cluster. For example, the processor 21 may determine that the cluster located below the cluster with the most concentrated gaze points is the cluster corresponding to the state in which the driver is looking at the display 11 (particularly the driver area). In the example shown in Figure 7, the threshold setting unit F2 may set an arbitrary value (e.g., an intermediate value) located between the vertical gaze angle (a1) at the upper end of cluster C2 and the vertical gaze angle (a2) at the lower end of cluster C1 as the standby threshold. This configuration also corresponds to a configuration in which the standby threshold is determined based on the forward gaze range.

[0049] The display control unit F3 is configured to adjust the brightness of the display 11 based on the driver's gaze direction. The display control unit F3 compares the vertical angle of the driver's gaze acquired by the gaze acquisition unit F1 with the standby threshold set by the threshold setting unit F2. If the driver's vertical angle of gaze is smaller than the standby threshold, the display control unit F3 sets the brightness of the display 11 to the normal level. On the other hand, if the driver's vertical angle of gaze is larger than the standby threshold, the display control unit F3 sets the brightness of the display 11 to a predetermined standby level. Note that the case where the driver's vertical angle of gaze is larger than the standby threshold corresponds to a state where the driver is not looking at the display 11.

[0050] The standby level is set lower than the normal level. The standby level is set to a value equivalent to 10% of the normal level. The standby level may be greater than 0% of the normal level. In other embodiments, the standby level may be set to a value equivalent to 5%, 20%, 25%, or 40% of the normal level. The lower the standby level, the greater the power saving effect. The standby level may be set to a level at which the driver can barely recognize the contents displayed on the display 11.

[0051] In this way, the HCU20 determines whether the driver's gaze is directed towards the display 11, that is, whether the driver is looking at the display 11. When the driver is not looking at the display 11, the HCU20 reduces power consumption by setting the display brightness of the display 11 to a standby level. When the HCU20 determines that the driver's gaze is directed towards the display 11, it increases the brightness from the standby level to the normal level. This ensures that the driver can see the displayed content.

[0052] <Example of HCU operation with standby threshold setting> Here, the threshold setting process performed by the HCU20 will be explained using the flowchart shown in Figure 8. The threshold setting process is a series of processes for setting a standby threshold. The threshold setting process may be executed based on the vehicle power switching from off to on, or on the start of driving. The HCU20 may determine that driving has started based on the first time the vehicle speed exceeds a predetermined value after the vehicle power is turned on. Alternatively, the HCU20 may consider the timing when the shift position is first set to the forward position (so-called D position) after the vehicle power is turned on as the time corresponding to the start of driving. The threshold setting process includes steps S11 to S15.

[0053] Step S11 is the step in which the gaze acquisition unit F1 acquires data indicating the driver's gaze direction from the occupant monitor 12 and stores it in memory 22 along with other predetermined data. The other predetermined data may include the time, driving speed, and the operating status of the turn signals. After step S11, the threshold setting unit F2 executes step S12.

[0054] Step S12 is a step in which the threshold setting unit F2 determines whether a predetermined initial data collection time has elapsed since the start of driving. The initial data collection time is the time required to collect gaze direction data for determining the standby threshold. The initial data collection time may be set to 60 seconds, 90 seconds, 120 seconds, etc. The period from the start of driving until the predetermined initial data collection time has elapsed corresponds to the predetermined period. Step S12 is performed periodically.

[0055] If the initial data collection time has not elapsed since the start of travel (S12 NO), the processor 21 repeats steps S11 to S12. If the initial data collection time has elapsed since the start of travel (S12 YES), the process proceeds to step S13. Step S11 may be executed periodically even after step S13.

[0056] Step S13 is a step in which the threshold setting unit F2 determines whether the number of valid samples is equal to or greater than a predetermined value. The number of valid samples here refers to the number of valid gaze direction data among the gaze direction data stored in memory 22. Valid gaze direction data refers to gaze direction data acquired in scenes where there is a high probability that the driver is looking straight ahead of the vehicle. The processor 21 may treat gaze direction data acquired when the driving speed is equal to or greater than a predetermined value (e.g., 20 km / h) and the turn signals are not activated as valid gaze direction data.

[0057] Furthermore, when the vehicle is driving near an intersection, the driver's gaze is likely to be directed away from the front to check the status of traffic lights and the surrounding traffic conditions. In other words, gaze direction data acquired when driving near an intersection can become noise in determining the forward gaze range. For these reasons, the processor 21 may be configured not to treat gaze direction data acquired while driving near an intersection as valid gaze direction data. Whether or not the vehicle is driving near an intersection may be determined based on the forward road data provided by the locator 14 or the recognition status of traffic lights in the driver assistance device 15. In addition, the processor 21 may treat gaze direction data acquired while performing autonomous driving with eyes-off enabled as invalid gaze direction data.

[0058] The processor 21 may be configured to save only the gaze direction data acquired in specific situations where it is easy to acquire valid gaze direction data to the memory 22. For example, the processor 21 may be configured to save the gaze direction data acquired when the turn signal is off and the vehicle speed is above a predetermined value to the memory 22.

[0059] The minimum number of effective samples required to determine the forward line of sight range may be set to any value such as 40, 50, 60, or 80. If the number of effective samples is greater than or equal to a predetermined value (e.g., 50) (S13 YES), the threshold setting unit F2 executes step S14. On the other hand, if the number of effective samples is less than the predetermined value (S13 NO), the threshold setting unit F2 may repeat steps S11 to S13 until the number of effective samples becomes greater than or equal to the predetermined value.

[0060] Step S14 is the step in which the threshold setting unit F2 identifies the forward line of sight range based on valid line of sight direction data. As described above, the forward line of sight range may be identified by various methods. Once the identification of the forward line of sight range is complete, the threshold setting unit F2 executes step S15.

[0061] Step S15 is a step in which a standby threshold is determined based on the forward line of sight range identified in step S14. The standby threshold can also be determined in various ways, as described above. The threshold setting unit F2 may set the standby threshold to an angle value that is approximately 5° to 10° below the center of the forward line of sight range. Alternatively, the threshold setting unit F2 may set the standby threshold to the lower limit of the forward line of sight range itself, or an angle value that is a predetermined amount smaller than the lower limit of the forward line of sight range. After step S15, the line of sight acquisition unit F1 may periodically acquire and save line of sight direction data.

[0062] Step S13 is optional and may be omitted. The threshold setting unit F2 may also execute step S14 using the gaze direction data accumulated up to that point when the initial data collection time has elapsed since the start of driving.

[0063] Furthermore, the threshold setting unit F2 may determine the standby threshold using the display line of sight range determined from the forward line of sight range. Step S14 may include a step of identifying the display line of sight range based on the forward line of sight range, based on the line of sight direction data stored in the memory 22.

[0064] The processor 21 may be configured to store gaze direction data separately for when the vehicle is in motion and when it is stationary. When the vehicle is stationary, the driver is more likely to look at the display 11 than when it is in motion. Therefore, the processor 21 may determine the display gaze range based on the gaze direction data when the vehicle is stationary. Alternatively, the processor 21 may determine the operation timing, which is the timing when the driver operates the input device 16, based on the signal from the input device 16, and determine the display gaze range using the gaze direction data within a predetermined time from the operation timing. This is because when the driver is operating the input device 16, there is a high probability that the driver is looking at the display 11.

[0065] <Example of HCU operation related to display control> Here, the operation of the HCU20 related to display control will be explained using the flowchart shown in Figure 9. The process related to display control includes steps S21 to S25 as shown in Figure 9. The process shown in Figure 9 may be executed periodically while the vehicle power is on.

[0066] Step S21 is a step in which the display control unit F3 determines whether or not the standby threshold has been determined. The state in which the standby threshold has been determined corresponds to the state in which the standby threshold has been set in step S15. If the determination of the standby threshold has not yet been completed (S21 NO), the display control unit F3 turns off the brightness control function based on the vertical viewing angle (S22). The brightness control function based on the vertical viewing angle refers to the control that changes the brightness of the display 11 according to the vertical viewing angle. When the brightness control function is off, the display control unit F3 continues to set the brightness of the display 11 to the normal level. In other words, in the initial state, such as immediately after the vehicle power is turned on, the brightness control function is off, and the display 11 continues to display the image at the normal level of brightness.

[0067] On the other hand, if the standby threshold has been determined (S21 YES), the display control unit F3 determines in step S23 whether the current driver's vertical gaze angle (φ) is less than the standby threshold (Thp). In the figure, "φ" represents the vertical gaze angle, and "Thp" represents the standby threshold. The current vertical gaze angle may be the vertical gaze angle indicated by the latest gaze direction acquired by the gaze acquisition unit F1.

[0068] The display control unit F3 sets the brightness of the display 11 to the normal level if the driver's vertical gaze angle is less than the standby threshold (S24). If the driver's vertical gaze angle is greater than or equal to the standby threshold, the brightness of the display 11 is set to the standby level (S25). As a result, when the driver is looking at the display 11, the screen of the display 11 is displayed at the normal level (bright), and when the driver is not looking at the display 11, the screen of the display 11 is displayed at the standby level (dim).

[0069] Figure 10 shows an example of display brightness control of the display 11 by the display control unit F3 according to the vertical viewing angle. In Figure 10, the horizontal axis represents time, and the vertical axis represents the brightness level. Time T1 in Figure 10 is the time when the vertical viewing angle transitions from a state where it is above the standby threshold to a state where it is below the standby threshold. Before time T1, the vertical viewing angle is above the standby threshold. In other words, the time period before time T1 corresponds to a state where the driver is not looking at the display 11. Time T2 is the time when the vertical viewing angle transitions from a state where it is below the standby threshold to a state where it is above the standby threshold. Between times T1 and T2, the vertical viewing angle is maintained below the standby threshold. Between times T1 and T2 corresponds to a situation where the driver is looking at the display 11. After time T2, the vertical viewing angle is above the standby threshold, and the driver is not looking at the display 11.

[0070] In such cases, the display control unit F3 increases the brightness of the display 11 in a step-by-step manner from the standby level to the normal level based on the fact that the vertical viewing angle falls below the standby threshold at time T1. Furthermore, even if the vertical viewing angle exceeds the standby threshold at time T2, the display control unit F3 does not immediately reduce the brightness of the display 11 from the normal level to the standby level. The display control unit F3 reduces the brightness of the display 11 to the standby level after a predetermined brightness retention time (Ta) has elapsed from the moment the vertical viewing angle exceeds the standby threshold. In this way, the display control unit F3 reduces the brightness to the standby level if the driver's gaze is away from the display 11 for a predetermined period of time. The brightness retention time may be set to 3 seconds, 5 seconds, 8 seconds, etc. Hereafter, the period from when the vertical viewing angle exceeds the standby threshold until the brightness retention time has elapsed will also be referred to as the brightness retention period.

[0071] With this configuration, the brightness of the display 11 can be kept at a normal level (i.e., constant) in scenes where the driver frequently shifts their gaze from the front of the vehicle to the display 11. As a result, the risk of causing inconvenience to the driver can be reduced.

[0072] In another configuration, the display control unit F3 may change the brightness level in real time in conjunction with (follow) the changes in the driver's gaze vertical angle. That is, if the gaze vertical angle exceeds a standby threshold, the brightness may be quickly reduced to the standby level. However, in such a configuration, the brightness of the display 11 may fluctuate in scenes where the driver frequently shifts their gaze from the front of the vehicle to the display 11, which may be bothersome to the driver. Therefore, it is preferable that the display control unit F3 is configured to maintain a normal level for a certain period of time or to gradually reduce the brightness, rather than immediately reducing it to the standby level when the gaze vertical angle exceeds a standby threshold.

[0073] As shown in Figure 11, the display control unit F3 may be configured to gradually reduce the brightness to a standby level from the time the brightness retention period ends (T3). Alternatively, when the vertical viewing angle falls below the standby threshold, the display control unit F3 may increase the brightness of the display 11 from the standby level to the normal level in steps rather than in steps. For example, when the vertical viewing angle falls below the standby threshold, the display control unit F3 may increase the brightness in steps to a level equivalent to 70% of the normal level, and then gradually reduce the brightness to the normal level.

[0074] Incidentally, the developers of this disclosure conducted various tests and found that when the screen is dimmed based on the driver's gaze shifting away from the display 11, many drivers felt uncomfortable with a configuration where only a portion of the screen remained at a normal level of display. Furthermore, the test results also revealed that when a portion of the screen remains at a normal level of display, the driver's attention is more likely to be directed to that area. For these reasons, the display control unit F3 may, in principle, dim the entire screen uniformly when lowering the screen to a standby level. With such a configuration, the risk of causing discomfort to the driver can be reduced.

[0075] In another embodiment, the display control unit F3 may be configured to maintain a normal or intermediate level of brightness for a portion of the screen provided by the display 11, such as the area where the meter is displayed, even if the driver's vertical gaze angle is greater than or equal to a standby threshold. The intermediate level is a brightness level that lies between the normal level and the standby level, and may be, for example, a brightness level equivalent to 50% of the normal level. In other words, the display control unit F3 may be configured to apply brightness control according to the vertical gaze angle only to a portion of the screen provided by the display 11.

[0076] Furthermore, if a window displaying rear-side camera footage is located on a portion of the display 11 screen (for example, at the left or right edges), the brightness of the window may be maintained at a normal or intermediate level even if the driver's vertical line of sight angle exceeds a standby threshold. The configuration that displays a window showing rear-side camera footage corresponds to a configuration in which a portion of the display 11 functions as a monitor for the electronic side mirrors.

[0077] Furthermore, the HCU20 may be configured to allow the user to specify, via a predetermined settings screen, the type of display area / application (function) whose brightness will be reduced when the vertical viewing angle exceeds a standby threshold. The HCU20 may also be configured to reduce the display brightness of the display area / application window, which is pre-configured by the driver, to a standby level when the vertical viewing angle exceeds a standby threshold.

[0078] <Effects of this embodiment> Here, we introduce the first and second comparative configurations and describe the advantages of this embodiment over each comparative configuration. The first comparative configuration is one in which brightness control is performed using a pre-designed standby threshold. The second comparative configuration is one in which the standby threshold is determined before the start of driving by executing a predetermined gaze learning sequence before the start of driving. The gaze learning sequence may include, for example, requesting the driver to look at the display and detecting the driver's gaze direction at that time, and requesting the driver to look ahead of the vehicle and detecting the driver's gaze direction at that time.

[0079] The difference between the first comparative configuration and this embodiment is that the standby threshold is a pre-designed fixed value. In the first comparative configuration as well, if the standby threshold can be set to an appropriate value, it is possible to achieve both reduced power consumption and ensured screen visibility.

[0080] However, the developers of this disclosure attempted to determine a general-purpose standby threshold based on eye-gaze distribution information from multiple individuals with different physiques, and found that the range of the vertical angle of gaze when looking straight ahead of the vehicle varies greatly from person to person. The range of the vertical angle of gaze when looking at the display also varies greatly from person to person. In other words, it was found that it is difficult to determine a standby threshold that can be commonly applied to various individuals. This is because the orientation of the driver's face / gaze direction when viewing the display differs depending on various factors such as the driver's physique, seating position, posture, and habits. Due to the above circumstances, in the first comparative configuration, malfunctions are likely to occur, such as the standby level being maintained even when the driver is looking at the display 11, or the normal level being maintained even when the driver is not looking at the display 11.

[0081] In contrast to the first comparative configuration, the second comparative configuration allows for the setting of a waiting threshold according to the driver's physique, etc., in order to learn the vertical angle of gaze when the driver is looking at the front of the vehicle / display 11 before starting to drive. The second comparative configuration is expected to improve the accuracy of distinguishing between when the driver is looking at the display 11 and when they are not. However, the second comparative configuration requires the driver to perform a gaze learning sequence before starting to drive, which may reduce driver convenience.

[0082] In contrast to the first and second comparative configurations, the configuration of this embodiment dynamically identifies a standby threshold appropriate to the driver based on the distribution information of the driver's vertical gaze angle during driving, and reflects this in the brightness control. With this configuration, since the standby threshold is determined based on the actual vertical gaze angle of the driver, system malfunctions can be suppressed. Furthermore, the driver does not need to perform a gaze direction registration procedure before starting to drive. This embodiment may offer greater convenience than the second comparative configuration. In other words, this embodiment can improve user convenience while suppressing system malfunctions.

[0083] <Supplement (1)> When the brightness of the display 11 is set to the standby level, the driver assistance device 15 may input a warning request signal requesting the display of a warning image. However, when the display brightness is set to the standby level, the visibility of the warning image may be reduced compared to when it is at the normal level. For this reason, the display control unit F3 may be configured to display the warning image at the normal level even if the vertical angle of the line of sight is greater than or equal to the standby threshold when a request for the display of a warning image is input from the driver assistance device 15.

[0084] Figure 12 is a flowchart corresponding to the above technical concept, which may be executed based on the input of a request to display a warning image. When the display control unit F3 receives a request to display a warning image, it determines whether the standby level is currently applied (S31). If the image is not displayed in the standby level (S31 NO), the display control unit F3 displays the warning image at a predetermined position on the display 11. On the other hand, if the image is being displayed in the standby level (S31 YES), the display control unit F3 returns the brightness of the entire area of ​​the display 11 to the normal level (S33) and displays the warning image (S34). Steps S33 and S34 may be executed simultaneously, or the execution order may be reversed. Step S33 may be a control that returns only the display area / window displaying the warning image to the normal level. The above control policy may be applied not only when displaying warning images, but also when displaying various notifications. The HCU 20 may also increase the brightness from the standby level to the normal level when providing notifications of low fuel / battery power or traffic congestion.

[0085] <Supplement (2)> The display control unit F3 may, after initially determining the standby threshold, update the standby threshold again after a predetermined time has elapsed. This is because setting the standby threshold based on more gaze direction data is expected to improve accuracy.

[0086] Figure 13 is a flowchart illustrating the operation of the threshold setting unit F2 based on the above technical concept. Steps S41 to S42 shown in Figure 13 can be understood as corresponding to steps S11 to S15 mentioned above. That is, the threshold setting unit F2 determines a standby threshold (S42) based on the gaze direction data acquired up to the time when the first hour has elapsed since the start of driving (S41). The first hour is a parameter corresponding to the initial data acquisition time.

[0087] Subsequently, the threshold setting unit F2, at the time when two hours have elapsed since the start of driving (S43 YES), re-identifies the forward gaze range / display gaze range and updates the standby threshold (S44). The second hour only needs to be longer than the first hour, and its specific value can be designed as appropriate. The second hour may be the first hour plus 30 seconds / 60 seconds / 120 seconds. The standby threshold reset in step S44 may be based on gaze direction data collected up to the time two hours have elapsed since the start of driving. With this configuration, it becomes possible to set a more appropriate standby threshold.

[0088] <Supplement (3)> The processor 21 may perform brightness control according to the vertical and horizontal viewing angles. For example, the processor 21 may be configured to display the driver area of ​​the display 11 at a normal level when the driver's gaze is directed towards the driver area, while maintaining the other display areas at a standby level.

[0089] The developers of this disclosure conducted extensive testing on brightness control of the display 11 based on gaze direction and found that there was significant variation among drivers in the vertical gaze angle (so-called individual differences), while there was little individual variation in the horizontal gaze angle. Specifically, they found that the horizontal gaze angle when looking at the driver's area, the horizontal gaze angle when looking at the central area, and the horizontal gaze angle when looking at the passenger seat area all fell within a certain range for most people.

[0090] For these reasons, thresholds for the left-right viewing angle, which are used to perform brightness control according to the viewing angle, may be pre-registered in storage 23 as part of the display control program. The thresholds for the left-right viewing angle may include multiple thresholds for determining whether the driver is looking at the driver area, the center area, or the passenger seat area. The processor 21 may perform brightness control based on the viewing angle using the pre-designed thresholds. Of course, in another embodiment, the processor 21 may determine the thresholds for the left-right viewing angle based on a set of viewing direction data acquired from the time the vehicle power is turned on until a predetermined time has elapsed.

[0091] As described above, the HCU20 may perform brightness control of the display 11 based on both the vertical and horizontal viewing angles, or it may perform brightness control of the display 11 based only on the vertical viewing angle, as in the embodiment described above. The HCU20 may be configured to perform brightness control based only on the horizontal viewing angle until a standby threshold is determined, and then to perform brightness control of the display 11 based on both the vertical and horizontal viewing angles after the standby threshold has been determined.

[0092] <Supplement (4)> The occupant monitor 12 may be configured to detect the gaze direction of the passenger seat occupant and transmit data indicating that gaze direction to the HCU 20. The processor 21 may also set a standby threshold for the passenger seat occupant based on the distribution of the passenger seat occupant's vertical gaze angle. The standby threshold for the passenger seat occupant is a separate parameter from the driver's standby threshold. The processor 21 may increase the brightness of the display 11 from the standby level to the normal level based on the passenger seat occupant's vertical gaze angle falling below the passenger seat occupant standby threshold. The area in which the processor 21 increases brightness when the passenger seat occupant's vertical gaze angle falls below the passenger seat occupant standby threshold may be limited to the passenger seat area only, or to the passenger seat area and the central area. Brightness control according to the passenger seat's gaze direction may be enabled only when the presence of a passenger seat occupant is detected. The presence or absence of a passenger seat occupant may be determined based on the output signal of a seating sensor installed in the passenger seat or on the in-vehicle camera image.

[0093] <Supplement (5)> This disclosure is not limited to pillar-to-pillar type displays, but may be applied to display devices of various shapes. Furthermore, the in-vehicle system 100 may include multiple physically independent display devices. For example, as shown in Figure 14, the in-vehicle system 100 may include a meter display 11M, a center display 11C, a right side monitor 11R, and a left side monitor 11L. The right side monitor 11R is a display for showing camera images of the right rear. The left side monitor 11L is a display for showing camera images of the left rear. The display mode and brightness of the images displayed on each display are controlled by the HCU 20. Of the four display devices shown in Figure 14, only the meter display 11M and the center display 11C may have their brightness controlled by the processor 21 based on the vertical viewing angle. Since the right side monitor 11R and the left side monitor 11L are display devices for monitoring the surroundings, they may always be displayed at a normal level. In another embodiment, the processor 21 may set the brightness of the right side monitor 11R to a standby level or an intermediate level based on whether the vertical viewing angle is greater than or equal to a standby threshold, or whether the horizontal viewing angle is within a predetermined range. Similarly, the brightness of the left side monitor 11L may be set to a standby level or an intermediate level based on whether the horizontal viewing angle is within a predetermined range.

[0094] <Supplement (6)> This disclosure may also be applied to brightness control of a display device provided on an A-pillar or door module. In other words, the display 11 subject to brightness control according to the direction of gaze may be a display device provided on an A-pillar or door module. In such a configuration, the processor 21 may set the standby brightness of the display 11 based on the fact that the driver's direction of gaze has moved from outside the forward line of sight range, which has been determined after the start of driving, to within the forward line of sight range. The processor 21 may set the brightness of the display 11 to a normal level immediately after the start of driving or when the driver's direction of gaze is outside the forward line of sight range.

[0095] <Supplement (7)> In the above, the higher the driver's line of sight is directed relative to the vehicle, the larger the vertical angle of sight becomes. However, the vertical angle of sight may also be expressed with downward as the positive direction. In the above embodiment, the statement "the vertical angle of sight is greater than or equal to the standby threshold" may be reinterpreted as "the vertical angle of sight is less than the standby threshold" if the downward direction relative to the vehicle is considered the positive direction of the vertical angle of sight. In the embodiment, the statement that the vertical angle of sight is greater than or equal to the standby threshold means that the driver's line of sight is directed above the boundary line indicated by the standby threshold.

[0096] <Additional Note> The various flowcharts shown in this disclosure are all examples, and the number of steps constituting the flowchart and the order in which the processes are executed can be changed as appropriate. The terms acquisition, determination, detection, generation, and calculation in this disclosure may be used interchangeably. The devices, systems, and methods described in this disclosure may be implemented by a dedicated computer comprising a processor programmed to perform one or more functions embodied by a computer program. The devices and methods described in this disclosure may be implemented using dedicated hardware logic circuits. The devices and methods described in this disclosure may be implemented by one or more dedicated computers comprising a combination of a processor that executes a computer program and one or more hardware logic circuits. The computer program includes instructions to be executed by the computer. The computer program may be stored on a computer-readable non-transitional tangible recording medium. [Explanation of symbols]

[0097] 11 Display, 12 Occupant monitor, 13 Vehicle status sensor, 14 Locator, 15 Driving assistance system, 16 Input device, 20 HCU, 21 Processor, 22 Memory, 23 Storage, 24 Communication interface (receiving unit), F1 Eye-tracking unit, F2 Threshold setting unit, F3 Display control unit

Claims

1. A receiving unit (24) that receives data indicating the direction of the vehicle driver's gaze, The system includes a control unit (21) that controls the brightness of a display installed in the vehicle based on the data received by the receiving unit, The control unit, Based on the distribution information of the line of sight received by the receiving unit within a predetermined period after the vehicle has started to move, the forward line of sight range, which is the range of the line of sight corresponding to the state in which the driver is looking forward at the vehicle, is identified. Based on the fact that the line of sight direction is outside the forward line of sight range, the brightness is set to a normal level. A display control device configured to set the brightness to a standby level lower than the normal level, based on the fact that the line of sight direction is within the forward line of sight range.

2. The control unit, The receiving unit acquires data indicating the vertical angle of the line of sight, which is the vertical component of the line of sight direction. The display control device according to claim 1, configured to specify the range of the vertical angle of the line of sight corresponding to the state in which the driver is looking forward of the vehicle as the forward line of sight range.

3. The aforementioned display is provided on the instrument panel. The control unit, The receiving unit acquires data indicating the vertical angle of the line of sight, which is the vertical component of the line of sight direction. Based on the set of data indicating the vertical angle of the gaze acquired during the predetermined period, the range of the vertical angle of the gaze corresponding to the state in which the driver is looking forward of the vehicle is identified as the forward gaze range. Based on the range of the vertical angle of the line of sight corresponding to the forward line of sight range, a standby threshold is set for reducing the brightness to the standby level. The display control device according to claim 1, configured to set the brightness to the standby level based on the fact that the vertical angle of view has become greater than or equal to the standby threshold.

4. The display control device according to claim 3, wherein the control unit is configured to set the brightness to the standby level when the brightness is set to the normal level and the vertical viewing angle remains greater than the standby threshold for a predetermined period of time.

5. The display control device according to claim 3, wherein the control unit is configured to increase the brightness in a stepwise manner from the standby level to the normal level when the vertical viewing angle falls below the standby threshold while the brightness is set to the standby level.

6. The aforementioned display has multiple light sources, The control unit, Controlling the brightness of the multiple light sources provided by the display, The display control device according to claim 3, configured to set the brightness of all of the plurality of light sources to the standby level when the vertical angle of the line of sight is greater than or equal to the standby threshold.

7. The display control device according to claim 3, wherein the standby level is set to a value corresponding to 5%, 10%, 20%, 25%, or 40% of the normal level.

8. The display control device according to claim 3, wherein the control unit is configured to raise the brightness to the normal level even if the vertical viewing angle is greater than or equal to the standby threshold when issuing a warning to the driver while the brightness is set to the standby level.

9. The display control device according to claim 3, wherein the control unit is configured to set the brightness to the normal level from the start of the vehicle's movement until the forward line of sight range is identified.

10. The control unit, The receiving unit acquires data indicating the left-right angle of the driver's gaze, which is the angle in the left-right direction the driver's gaze is directed. The display control device according to claim 3, wherein, when the vertical viewing angle is less than the standby threshold, the display control device is configured to set the portion of the display area provided by the display corresponding to the horizontal viewing angle to the normal level, while setting the other portion to the standby level.

11. The control unit, The range of possible values ​​for the vertical angle of the line of sight is divided into multiple angular ranges, Based on the distribution information, identify the angular range in which the line of sight direction is detected most frequently among the multiple angular ranges, The display control device according to claim 3, configured to perform the following: determine the forward line of sight range based on the angular range in which the most frequently detected line of sight directions are found.

12. The display is provided on the A-pillar or door module of the vehicle. The display control device according to claim 1, wherein the control unit is configured to set the brightness from the normal level to the standby level based on the fact that the line of sight direction has moved from outside the forward line of sight range to within the forward line of sight range.

13. The display control device according to any one of claims 1 to 12, wherein the control unit is configured to update the forward line of sight range based on the distribution information of the line of sight direction newly received by the receiving unit during a predetermined time elapsed after the forward line of sight range has been identified.

14. The display control device according to any one of claims 1 to 12, wherein the control unit is configured to determine the forward line of sight range based on the distribution information of the line of sight direction received by the receiving unit when the speed of the vehicle is greater than or equal to a predetermined value.

15. The display control device according to any one of claims 1 to 12, wherein the control unit is configured to determine the forward line of sight range based on the distribution information of the line of sight direction received by the receiving unit when the vehicle's turn signal is not in use.

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