JP7344635B2 - heads up display device - Google Patents

Description

The present invention relates to a head-up display device that is mounted on a vehicle and can adjust the display distance of images.

In recent years, vehicle video display devices (head-up display devices (hereinafter referred to as HUDs)) that display video information as a virtual image in front of a vehicle through a windshield have been put into practical use. At that time, by providing information for the driver as displayed video information, it is possible to support the driving operation of the vehicle.

When displaying an image (virtual image), the first method fixes the distance (display distance) from the driver's eyes to the visible virtual image, and the first method fixes the distance (display distance) from the driver's eyes to the virtual image, and the There is a second method that matches the distance, and a third method that matches the distance to the viewpoint position of the driver's attention. In the second and third systems in which the display distance is variable, the HUD is equipped with an adjustment mechanism for adjusting the display distance of the virtual image. For example, Patent Document 1 proposes a method using a movable lens, a functional liquid crystal film, and the like.

International Publication No. 2017-134861

The distance at which the driver's viewpoint is focused changes depending on the surrounding environment and driving conditions when driving. In the first method in which the display distance of the virtual image is fixed, the displayed virtual image and the viewpoint do not match, making it difficult to see. Therefore, the driver is required to move his/her viewpoint to the virtual image, which may increase eye fatigue and make it difficult to concentrate on driving.

On the other hand, in the second method, which adjusts to the distance to the forward object (such as a preceding vehicle or pedestrian), if the driver's viewpoint is at the object position, there is no need to move the viewpoint to the virtual image. However, the object ahead is not necessarily the object that the driver focuses on, and when there are multiple objects, it is difficult to determine which object the driver should focus his or her attention on. Furthermore, in the third method of adjusting to the driver's viewpoint distance, since the viewpoint distance while driving changes frequently depending on traffic conditions, etc., the displayed distance is made to follow this in real time, which is inconvenient for the driver. It becomes difficult to see. As described above, it is difficult to say that any of the first to third methods provides a display that is comfortable for the driver to view.

SUMMARY OF THE INVENTION An object of the present invention is to provide a head-up display device that allows a driver to comfortably view images with less movement of his or her viewpoint.

In order to solve the above problems, a head-up display device according to the present invention includes a vehicle information acquisition unit that acquires vehicle information regarding the driving state of the vehicle, a video display device that generates an image to be projected, and a A display distance adjustment mechanism that adjusts the display distance to the virtual image, and a control section that controls the video display device and the display distance adjustment mechanism, and the control section uses the vehicle information acquired through the vehicle information acquisition section. The current driving state of the vehicle is determined, and the display distance to the virtual image is adjusted according to the driving state via a display distance adjustment mechanism. Here, the viewpoint distance at which the driver is most likely to concentrate in each driving state is stored in the memory as the recommended value of the display distance for that driving state, and the control unit determines the display distance by referring to the recommended value stored in the memory. adjust.

According to the present invention, since the image is displayed based on the viewpoint distance at which the driver is most likely to concentrate depending on the driving condition, there is an effect that the image can be viewed comfortably with less movement of the viewpoint.

FIG. 1 is a diagram showing an outline of a head-up display device (HUD) mounted on a vehicle. The figure which shows the video display operation by HUD. The block diagram which shows the structure of the control system of HUD. FIG. 3 is a diagram illustrating an example of the configuration of hardware related to acquiring vehicle information. The figure which shows the example of a structure of a display distance adjustment mechanism. Flowchart showing display distance control. FIG. 3 is a diagram showing the results of measuring the driver's viewpoint distance in various driving states. FIG. 3 is a diagram showing the relationship between display distance and double image generation. The figure which shows the example of the recommended value of the display distance set according to a driving state.

Embodiments of a head-up display device (hereinafter referred to as HUD) according to the present invention will be described with reference to the drawings.

FIG. 1 is a diagram showing an outline of a HUD mounted on a vehicle. The HUD 1 is mounted on the vehicle 2 and projects an image generated by the image display device 30 onto the windshield 3 (also called a windshield) of the vehicle 2 via the mirror 52. The image reflected by the windshield 3 enters the driver's eyes, allowing him to visually recognize the image. The images displayed include driving-related information and assist in driving operations.

Inside the HUD 1, there is a vehicle information acquisition unit 10 that acquires various types of vehicle information 4, a control unit 20 that generates video information to be displayed based on this, a display distance adjustment mechanism 40 that adjusts the display distance of the video, It includes a mirror drive unit 50 that drives a mirror 52, a speaker 60 that outputs audio information, and the like. The vehicle information 4 includes, in addition to speed information and gear information indicating the driving state of the vehicle, steering wheel angle information, illuminance information indicating the brightness outside the vehicle, map information indicating the driving position, and the like.

FIG. 2 is a diagram showing the video display operation by the HUD 1. An image for display is emitted from an image display device 30 installed at the bottom of the dashboard of the vehicle 2. The display distance of the emitted image is adjusted by the display distance adjustment mechanism 40, reflected by the first mirror 51 and the second mirror 52, and projected toward the windshield 3. The first mirror 51 is fixed, and the second mirror 52 is rotatable by a mirror drive unit 50.

The image converged and projected from the mirror 52 is reflected by the windshield 3, enters the driver's eyes 5, and forms an image on the driver's retina, so that the image can be visually recognized. At that time, the driver is looking at the virtual image 9 that exists in front of the windshield 3. Here, the display distance adjustment mechanism 40 adjusts the display distance from the driver's eyes 5 to the virtual image 9 in the direction of the arrow according to the driving state under control from the control unit 20. The mirror drive unit 50 rotates the mirror 52 according to the height of the driver's eyes 5 to adjust the display position (height direction) of the virtual image 9. These adjustments allow the driver to visually recognize the virtual image 9 at a position where it is easy to see.

FIG. 3 is a block diagram showing the configuration of the control system of the HUD 1. As shown in FIG. Various types of vehicle information 4 are input to the vehicle information acquisition section 10 and sent to the control section 20 . An electronic control unit (ECU) 21 in the control section 20 generates a video signal (display content) to be displayed by the HUD 1 and various control signals for the HUD 1 based on the input vehicle information 4. The audio output section 22 generates an audio signal to be sent to the speaker 60. The nonvolatile memory 23 stores programs executed by the ECU 21 and various control data, and the memory 24 stores video information and control information.

The image display device 30 includes a light source 31 such as an LED or a laser, an illumination optical system (not shown), and a display element 32 such as a liquid crystal element. The light is emitted toward the mirror 52.

A light source adjustment section 25 within the control section 20 controls a light source 31 within the video display device 30. The distortion correction section 26 corrects the distortion of the video signal to be displayed, and the display element driving section 27 drives the display element 32 in the video display device 30 based on the corrected video signal.

The display distance adjustment unit 28 outputs a drive signal for adjusting the display distance of the image to the display distance adjustment mechanism 40. The mirror adjustment section 29 outputs a drive signal for adjusting the position and orientation of the mirror 52 to the mirror drive section 50.

In this embodiment, the ECU 21 uses vehicle information 4 acquired through the vehicle information acquisition section 10 to determine the current driving state, and instructs the display distance adjustment section 28 to control the display distance. Specifically, the running states are classified as shown in FIG. 9, which will be described later. Therefore, the illuminance information and time information in the vehicle information 4 are used to determine whether it is daytime or nighttime. It also uses speed information, gear information, and map information to determine whether to drive on a local road or a highway. Furthermore, the steering information and map information are used to determine whether the vehicle is turning right or left or going straight. The display distance adjustment unit 28 switches the display distance of the image according to these driving conditions.

In controlling the display distance, the viewpoint distance at which the driver is most likely to concentrate under various driving conditions is determined in advance, and this is set as the recommended value for that driving condition and stored in the non-volatile memory 23. The ECU 21 determines the display distance by referring to this recommended value.

FIG. 4 is a diagram showing an example of a hardware configuration related to acquiring vehicle information 4. As shown in FIG. Acquisition of the vehicle information 4 is performed by, for example, information acquisition devices such as various sensors installed in the vehicle 2 under the control of an electronic control unit (ECU) 21 in the control section 20. Note that it is not necessary to have all of these devices in order to execute the operations of this embodiment, and other types of devices may be added as appropriate.

Vehicle speed sensor 101 acquires speed information of vehicle 2 . Shift position sensor 102 acquires current gear information of vehicle 2. The steering wheel steering angle sensor 103 acquires steering wheel steering angle information. The headlight sensor 104 acquires lamp lighting information related to turning on/off the headlights. The illuminance sensor 105 and the chromaticity sensor 106 acquire information on the brightness and hue of external light. The distance sensor 107 acquires distance information between the vehicle 2 and an external object. The infrared sensor 108 acquires infrared information related to the presence or absence of an object in a short distance from the vehicle 2, the distance, and the like. Engine start sensor 109 detects engine on/off information.

The acceleration sensor 110 and the gyro sensor 111 acquire acceleration gyro information consisting of acceleration and angular velocity as information on the attitude and behavior of the vehicle 2. The temperature sensor 112 acquires temperature information inside and outside the vehicle. The radio transceiver 113 for road-to-vehicle communication performs road-to-vehicle communication between the vehicle 2 and a roadside device, and the radio transceiver 114 for vehicle-to-vehicle communication performs vehicle-to-vehicle communication between the vehicle 2 and other nearby vehicles. , acquire information around the vehicle 2.

The camera (inside the vehicle) 115 and the camera (outside the vehicle) 116 take images of the inside and outside of the vehicle, respectively, and obtain camera image information (inside the vehicle/outside the vehicle). In particular, the camera (outside the vehicle) 116 photographs the surrounding situation, such as the front and rear of the vehicle 2. By analyzing the obtained images, it is possible to understand, for example, the presence of moving objects such as other vehicles and pedestrians in the vicinity, buildings, topography, and road surface conditions (rain, snow, ice, unevenness, etc.). It is.

A GPS (Global Positioning System) receiver 117 receives GPS signals and acquires GPS information. A VICS (Vehicle Information and Communication System, registered trademark (hereinafter the same)) receiver 118 receives a VICS signal and acquires VICS information. By acquiring this information and comparing it with map data, map information indicating the position and traveling direction of the vehicle 2 is generated.

FIG. 5 is a diagram showing an example of the configuration of the display distance adjustment mechanism 40. The display distance adjustment mechanism 40 is a mechanism that adjusts the distance of the displayed virtual image from the driver's eyes 5 based on instructions from the control unit 20 (display distance adjustment unit 28), and uses various display distance adjustment methods. is possible. Here, as an example, a display distance adjustment mechanism 40 using a movable lens will be described.

The image projected from the image display device 30 is formed into an image by a diffuser 41, and then enters a mirror 52 via a movable lens 42 that is divided into a plurality of areas (three in this case). Ru. Each movable lens 42 can be individually moved along the optical axis direction by a lens moving mechanism (not shown). The display position of the virtual image 9 based on the image projected from the image display device 30 is determined according to the distance between the diffuser plate 41 and each movable lens 42. Therefore, by moving the movable lens 42, the focal length can be changed for each area, and the display distance of the virtual image can be changed.

Specifically, as shown in FIG. 5, for example, by moving the movable lens 42 to a position close to the diffuser plate 41 in the uppermost area, the display distance of the corresponding virtual image can be shortened. On the other hand, in the bottom area, by moving the movable lens 42 to a position far from the diffuser plate 41, the display distance of the corresponding virtual image can be increased. Note that the number of movable lenses 42 is not limited to three as shown in the figure, and may be configured as appropriate depending on the desired number of areas.

Other display distance adjustment methods include a method using a movable diffuser plate in which the lens position is fixed and the diffuser plate is moved in the optical axis direction, a method using a functional liquid crystal film as the diffuser plate, and the like.

FIG. 6 is a flowchart showing display distance control. The following processing is performed by the ECU 21 in the control section 20 controlling the display distance adjustment section 28 according to the driving state. Note that the running state will be explained according to the divisions in FIG. 9, which will be described later.
S201: The ECU 21 acquires information regarding the driving state of the vehicle via the vehicle information acquisition unit 10. Specifically, illuminance information indicating the brightness of outside light, time information, vehicle speed information, gear information, steering information, map information, etc. are acquired.

S202: The ECU 21 determines whether the current brightness is daytime or nighttime based on the illuminance information and time information. However, here, the time when the illuminance is brighter than a predetermined value is defined as daytime, and the time when illuminance is lower than the predetermined value is defined as nighttime. Therefore, even if it is daytime according to the time information, if the illuminance is low, it is determined that it is nighttime.
S203: The ECU 21 determines whether the road the vehicle is traveling on is a general road or an expressway based on the speed information, gear information, and map information.

S204: Furthermore, the ECU 21 uses the steering information and map information to determine whether the driving operation state is when the vehicle is turning right or left (including when driving at an intersection) or when driving straight. As a result of the determination, if the vehicle is running in a right or left turn (determination: Yes), the process proceeds to S206, and if the vehicle is traveling straight ahead (other than an intersection) (determination: No), the process proceeds to S205.

S205: The ECU 21 refers to the recommended display distance value stored in the nonvolatile memory 23 and reads out the recommended value La for the current driving state. An example of the recommended value of the display distance will be described later with reference to FIG.
S206: The ECU 21 measures the distance Lb to the forward object (preceding vehicle, pedestrian, traffic light, etc.) using the distance measurement sensor 107.

S207: The ECU 21 sends the values of the display distances La and Lb acquired in S205 or S206 to the display distance adjustment unit 28. The display distance adjustment unit 28 drives the display distance adjustment mechanism 40 to adjust the display distance of the image projected from the image display device 30 to be La and Lb. After that, the process returns to S201 and repeats the above processing.

In the above flowchart, the display distance is adjusted according to the current driving condition by determining whether the driving condition is daytime or nighttime and whether the road is a local road or a highway, but the classification of the driving condition is just an example. Yes, but not limited to.
Next, the setting of the optimum display distance (recommended value) in various driving conditions will be explained.

FIG. 7 is a diagram showing the results of measuring the driver's viewpoint distance in various driving states. The viewpoint distance of general subjects was measured while driving using a commercially available line-of-sight measuring device, and the measurement results are expressed as a frequency distribution (%) for each viewpoint distance. Note that the viewpoint distance is divided into 0 to 0.8 m and 0.8 to 5 m. The driving conditions are daytime/nighttime comparisons, and the driving roads are general roads (urban areas, residential areas) and expressways. As a result of the viewpoint measurement, there is a range with a high frequency distribution of viewpoint distance (range where the viewpoint is most likely to be concentrated) depending on the driving condition, and the following findings regarding the optimal display distance were obtained.

In each driving state, the driver looks within 40 meters with a probability of 85% or more. That is, even if a virtual image is displayed at a distance exceeding 40 meters, the virtual image will not be in focus if the driver's viewpoint remains the same as when driving, and viewing the virtual image will involve moving the viewpoint.

On public roads during the day, the probability of seeing a relatively long distance is high, but it is rare to see more than 20 meters. Therefore, the display distance on public roads during the day is preferably 20 meters or less. The display distance on expressways during the day should be farther than on general roads, and should be 40 meters or less.
On public roads at night, the total probability of seeing 5 meters or less is 93.4%. Based on this result, the display distance is fixed at 5 m. The display distance on expressways at night should be farther than on general roads, and should not exceed 40 meters.

In this way, by setting the display distance to a range where the driver's viewpoint is most likely to concentrate, the driver can comfortably view the image with less movement of his or her viewpoint. In other words, compared to a method in which the display position is tracked one by one according to the distance to the object in front or the current viewpoint position, the display distance is fixed according to the driving condition, which eliminates the hassle of frequently switching the display distance. It will be resolved.

On the other hand, if the display distance is extremely close, there is a problem in that the virtual image becomes difficult to see due to the generation of double images. In a HUD, light reflected from the inside of the windshield and light reflected from the outside of the windshield enter the driver's eyes, causing the virtual image display position to shift and causing double viewing, reducing the visibility of the image. I'll let you. Therefore, it is desirable to avoid this.

FIG. 8 is a diagram showing the relationship between the virtual image display distance and double image generation obtained by simulation. Assuming that the inclination angle of the windshield 3 is 45 degrees, the angle difference Δθ is calculated from the angle θ1 of the inner reflected light and the angle θ2 of the outer reflected light. It can be seen that as the display distance L becomes smaller, the angular difference Δθ becomes larger.

The angular difference Δθ that can be visually recognized by a person with normal visual acuity (binocular visual acuity=0.7) with respect to a double image is said to be 0.024 deg or more. Therefore, if the image is displayed at a distance such that the angular difference Δθ is below this detection limit, no double image will be visually recognized. From this figure, it can be said that it is appropriate to set the lower limit of the display distance L to about 10 m. Note that since the detection limit varies depending on the visual acuity of the driver, the lower limit value of the display distance may be changed accordingly. For example, for a driver with binocular visual acuity=1.0, the lower limit may be set to about 15 m.
In this embodiment, a suitable display distance (recommended value) is determined by combining the viewpoint measurement results shown in FIG. 7 and the double image avoidance conditions shown in FIG.

FIG. 9 is a diagram showing an example of a recommended display distance value La that is set depending on the driving state.
On general roads during the day, the range is set at 10m to 20m to avoid double images, but on general roads at night, the distance is fixed at 5m to prioritize the viewpoint. Expressways (both daytime and nighttime) should be within the range of 10m to 40m, taking double images into account. Note that the driver can set a desired distance within this range.

On the other hand, when making a right or left turn, when driving near a traffic light, near an intersection, etc., the displayed distance is adjusted to the distance Lb to the object in front. The reason for this is that when turning right or left, etc., the viewpoint tends to concentrate on the position of the object in front, so it is preferable to display the distance without the viewpoint moving. For example, when a pedestrian crossing the street is 4 meters ahead, a virtual image (such as a warning icon) is displayed at a distance of 4 meters.

As described above, according to this embodiment, the recommended value of the display distance is determined based on the viewpoint distance where the driver's viewpoint is most likely to concentrate under various driving conditions determined in advance and the lower limit distance at which no double image is visible. The virtual image display position is changed according to the driving condition by referring to this. Therefore, it is possible to provide a head-up display device that allows the driver to comfortably view images with less movement of his/her viewpoint.

It goes without saying that the classification of driving conditions and the recommended values of the displayed distance described in this embodiment are merely examples, and that various modifications can be made depending on the environment in which the vehicle is used.

1: Head-up display device (HUD),
2: Vehicle,
3: Windshield (windshield),
4: Vehicle information,
9: Virtual image,
10: Vehicle information acquisition unit,
20: control unit,
21: Electronic control unit (ECU),
23: Non-volatile memory,
28: Display distance adjustment section,
30: Video display device,
40: Display distance adjustment mechanism,
41: Diffusion plate (diffuser),
42: Movable lens.

Claims (6)

In a head-up display device that is mounted on a vehicle and displays a virtual image in front of the vehicle to a driver by projecting an image,
a vehicle information acquisition unit that acquires vehicle information regarding the driving state of the vehicle;
an image display device that generates an image to be projected;
a display distance adjustment mechanism that adjusts the display distance from the driver's eyes to the virtual image;
comprising a control unit that controls the video display device and the display distance adjustment mechanism,
When the control unit determines that the vehicle is making a right or left turn, or is traveling near a traffic light, or near an intersection, based on the vehicle information acquired by the vehicle information acquisition unit, the control unit determines the distance to an object in front of the vehicle. The display distance is adjusted to display a virtual image according to adjusting the display distance of the virtual image through the display distance adjustment mechanism with reference to the viewpoint distance at which the driver is most likely to concentrate;
The head-up display device is characterized in that the recommended value of the display distance stored in the memory is set to be larger during the daytime than during the night, by distinguishing driving conditions on general roads into daytime and nighttime. In a head-up display device that is mounted on a vehicle and displays a virtual image in front of the vehicle to a driver by projecting an image,
a vehicle information acquisition unit that acquires vehicle information regarding the driving state of the vehicle;
an image display device that generates an image to be projected;
a display distance adjustment mechanism that adjusts the display distance from the driver's eyes to the virtual image;
comprising a control unit that controls the video display device and the display distance adjustment mechanism,
When the control unit determines that the vehicle is making a right or left turn, or is traveling near a traffic light, or near an intersection, based on the vehicle information acquired by the vehicle information acquisition unit, the control unit determines the distance to an object in front of the vehicle. The display distance is adjusted to display a virtual image according to adjusting the display distance of the virtual image through the display distance adjustment mechanism with reference to the viewpoint distance at which the driver is most likely to concentrate;
The head-up display device is characterized in that the recommended value of the display distance stored in the memory distinguishes the driving condition between a general road and a highway, and is set smaller for a general road than for a highway. The head-up display device according to claim 1 or 2,
A head-up display device, characterized in that the recommended value of the display distance stored in the memory is set to be equal to or greater than the lower limit value of the display distance to prevent a driver from seeing a double image of the displayed virtual image. In a video display method that displays video using a head-up display device installed in a vehicle,
projecting an image to display a virtual image in front of the vehicle to the driver;
obtaining vehicle information and determining the current running state of the vehicle;
a step of adjusting the display distance from the driver's eyes to the virtual image according to the driving condition;
In the step of adjusting the display distance, the viewpoint distance of the driver in each driving state is measured in advance, and if it is determined that the vehicle is making a right or left turn, or is traveling near a traffic light, or near an intersection, The display distance is adjusted so that the virtual image is displayed according to the distance to the object in front, and if it is determined that the vehicle is not making a right or left turn, or is not driving near a traffic light, or near an intersection, the driver can A viewpoint distance that is easy to concentrate on is stored in a memory as a recommended display distance value for that driving state, and the display distance is adjusted by referring to the recommended value stored in the memory,
The video display method is characterized in that the recommended value of the display distance stored in the memory is set to be larger during the daytime than during the night, by distinguishing driving conditions on general roads into daytime and nighttime. In a video display method that displays video using a head-up display device installed in a vehicle,
projecting an image to display a virtual image in front of the vehicle to the driver;
obtaining vehicle information and determining the current running state of the vehicle;
a step of adjusting the display distance from the driver's eyes to the virtual image according to the driving condition;
In the step of adjusting the display distance, the viewpoint distance of the driver in each driving state is measured in advance, and if it is determined that the vehicle is making a right or left turn, or is traveling near a traffic light, or near an intersection, The display distance is adjusted so that the virtual image is displayed according to the distance to the object in front, and if it is determined that the vehicle is not making a right or left turn, or is not driving near a traffic light, or near an intersection, the driver can A viewpoint distance that is easy to concentrate on is stored in a memory as a recommended value of the display distance in that driving state, and the display distance is adjusted by referring to the recommended value stored in the memory,
A video display method characterized in that the recommended value of the display distance stored in the memory is set to be smaller in the case of a general road than in the case of an expressway, by distinguishing the driving condition into a general road or a highway. In the video display method according to claim 4 or 5,
In the step of adjusting the display distance, a lower limit value of the display distance for preventing the driver from seeing a double image of the displayed virtual image is determined in advance, and the recommended value of the display distance to be stored in the memory is determined in advance. A video display method characterized by setting a lower limit value or more.

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