JP5600256B2 - Information display device - Google Patents

Description

  The present invention particularly relates to an information display device that displays various types of information in a region around the visual field of an observer.

  Conventionally, when operating a vehicle such as an automobile, an airplane, or a train, monitoring a radar, or working in an office, the vicinity of an observer is displayed through various display means such as a meter, a head-up display, a warning lamp, or a display device. Various proposals have been made for information display devices for displaying additional information on the visual field.

  In this type of information display device, it is important to accurately display other information in the peripheral visual field without disturbing the observer's gaze on the main observation target. Therefore, in this type of information display device, in order to display information that can be read even in the peripheral visual field region, and to prevent the eye movement from being obstructed, for example, Patent Document 1 discloses a standard A temporal frequency and a spatial frequency at which the contrast sensitivity of the observer can be obtained in the peripheral part of the visual field for the peripheral part of the visual field far from the central visual field of the observer (driver etc.) A technique for displaying a display pattern which is an image composed of frequency components in the range of the temporal frequency and the spatial frequency of the edge and the spatial edge is disclosed.

JP 2006-184854 A

  However, the technique disclosed in Patent Document 1 described above is an effective technique only when an observer observes a specific direction. Therefore, for example, when the observer is a driver or the like driving a car or the like, the line of sight of the driver or the like frequently moves, so that the displayed information is always suitably visible. Not necessarily.

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an information display device that can display information that can be suitably viewed even when the line of sight of the observer moves.

One aspect according to the information display device of the present invention, the visual axis detecting means for detecting a line of sight of the driver, and display means for displaying information to the driver, the display form of the image displayed by said display means, said visual axis Display control means for variably controlling the peripheral visual field power of the image with respect to the information display device, comprising an effective visual field estimation means for estimating the effective visual field of the driver, and the display The control means sets the contrast of the image displayed by the display means higher as the effective field of view becomes narrower.

  According to the information display device of the present invention, it is possible to display information that can be suitably viewed even when the observer's line of sight moves.

1 is a schematic configuration diagram of an information display device mounted on a vehicle according to a first embodiment of the present invention. Same as above, explanatory diagram of variance of gaze behavior in front view and width of preceding vehicle Same as above, explanatory diagram of examples of various attention rating values Same as above, flowchart showing information display control routine As above, an explanatory diagram showing the relationship between the driver's line of sight and the display form Schematic configuration diagram of a head-up display device according to a second embodiment of the invention Same as above, flowchart showing information display control routine As above, an explanatory diagram showing the relationship between the driver's line of sight and the display form

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIGS. 1 to 5 relate to the first embodiment of the present invention, FIG. 1 is a schematic configuration diagram of an information display device mounted on a vehicle, and FIG. 2 is a diagram showing a variance value of a line-of-sight behavior in a front view and a width of a preceding vehicle. FIG. 3 is an explanatory diagram showing examples of various attention evaluation values, FIG. 4 is a flowchart showing an information display control routine, and FIG. 5 is an explanatory diagram showing the relationship between the driver's line of sight and the display form.

  In FIG. 1, reference numeral 1 denotes a vehicle such as an automobile (own vehicle), and various information is given to the vehicle 1 via a display device 10 as a display unit for an occupant who is an observer (for example, a driver 100). An information display device 2 for displaying is mounted. In the present embodiment, an example of displaying the vehicle speed via the display device 10 will be described.

  The information display device 2 includes, for example, a stereo camera 3 that images the front outside the vehicle, a stereo image recognition device 4 that processes a signal from the stereo camera 3, a visual field camera 5 that captures the eye movement of the driver 100, and an infrared lamp 6. And a visual line detection device 7 that detects the visual line of the driver 100 using the visual field camera 5 and the infrared lamp 6, and a control unit 8.

  The vehicle 1 is also provided with various sensors such as a vehicle speed sensor 11 that detects a vehicle speed, a handle angle sensor 12 that detects a handle angle, and a yaw rate sensor 13 that detects a yaw rate. The vehicle speed from the vehicle speed sensor 11 is input to the stereo image recognition device 4 and the control unit 8, and the steering wheel angle from the steering wheel angle sensor 12 and the yaw rate from the yaw rate sensor 13 are input to the stereo image recognition device 4.

  The stereo camera 3 is composed of a pair of left and right CCD cameras using a solid-state imaging device such as a charge coupled device (CCD) as a stereo optical system. These left and right CCD cameras are each mounted at a predetermined interval in front of the ceiling in the passenger compartment, take a stereo image of an object (a three-dimensional object) outside the vehicle from different viewpoints, and output image data to the stereo image recognition device 4.

  The stereo image recognition device 4 receives image data, vehicle speed, steering wheel angle, yaw rate, and other signals from the stereo camera 3, and based on the image data, the front of the three-dimensional object data, sidewall data, white line data, etc. Information is detected, and the traveling path of the host vehicle 1 (own vehicle traveling path) is estimated from the forward information and the driving state of the host vehicle 1. Then, a travel area is set based on the estimated travel path of the own vehicle, and a preceding vehicle ahead of the own vehicle 1 is identified and extracted according to the presence state of the three-dimensional object with respect to the travel area. Output to.

  The above-described estimation of the own vehicle traveling path is performed as follows, for example. At this time, the three-dimensional coordinate system in the real space is a fixed coordinate system of the host vehicle 1, the left and right (width) rear of the host vehicle 1 is the X coordinate, the vertical direction of the host vehicle 1 is the Y coordinate, The front-rear direction is indicated by the Z coordinate. Then, with the road surface directly below the center of the two CCD cameras constituting the stereo camera 3 as the origin, the right side of the host vehicle 1 is the + side of the X axis, the upper side of the host vehicle 1 is the + side of the Y axis, and the host vehicle 1 Is set as the positive side of the Z axis.

  a. Estimating the traveling path of the vehicle based on the white line ... If both the left and right or left and right white line data are obtained and the shape of the lane in which the vehicle 1 is traveling can be estimated from the white line data, the own vehicle travels The road is formed in parallel with the white line in consideration of the width of the host vehicle 1 and the position of the host vehicle 1 in the current lane.

  b. Self-vehicle travel path estimation based on side data of guardrails, curbs, etc. Side wall data on both the left and right sides or left and right sides is obtained, and the shape of the lane in which the vehicle 1 is traveling is estimated from these side wall data If possible, the own vehicle traveling path is formed in parallel with the side wall in consideration of the width of the own vehicle 1 and the position of the own vehicle 1 in the current lane.

  c. Estimating own vehicle traveling path based on preceding vehicle trajectory: Estimating the own vehicle traveling path based on the past traveling trajectory of the preceding vehicle extracted from the three-dimensional object data.

  d. Estimating own vehicle travel path based on travel path of own vehicle 1 ... Estimating the own vehicle travel path based on the driving state of the own vehicle 1. For example, assuming that the yaw rate is γ, the host vehicle speed is Vo, and the steering wheel angle is θh, the host vehicle traveling path is estimated by the following procedure.

  First, it is determined whether the yaw rate sensor 13 is valid. If the yaw rate sensor 13 is valid, the current turning curvature Cua is calculated by the following equation (1).

Cua = γ / Vo (1)
On the other hand, if the yaw rate sensor 13 is invalid, it is determined whether or not the steering angle δ obtained from the steering wheel angle θh is greater than or equal to a predetermined value (for example, 0.57 degrees). When steering is performed at 57 degrees or more, the current turning curvature Cua is calculated by using the steering angle δ and the own vehicle speed Vo, for example, by the following equations (2) and (3).

Re = (1 + A · Vo ² ) · (L / δ) (2)
Cua = 1 / Re (3)
Here, Re is a turning radius, A is a vehicle stability factor, and L is a wheelbase.

  When the steering angle δ is smaller than 0.57 degrees, the current turning curvature Cua is set to 0 (straight running state).

  In this way, the average turning curvature is calculated from the turning curvature of the past predetermined time (for example, about 0.3 seconds) to which the obtained current turning curvature Cua is added, and the own vehicle traveling path is estimated.

  Even when the yaw rate sensor 13 is valid and the current turning curvature Cua is calculated by the above equation (1), if the steering angle δ is smaller than 0.57 degrees, the current turning curvature is Cua may be corrected to 0 (straight running state).

  For example, a width of about 1.1 m on the left and right sides is set as the travel area of the host vehicle 1 with the host vehicle traveling path estimated as described above as a reference.

  The processing of the image data from the stereo camera 3 in the stereo image recognition device 4 is performed as follows, for example. First, a distance representing a three-dimensional distance distribution is obtained by performing a process for obtaining distance information based on a principle of triangulation from a shift amount of a corresponding position on a stereo image in front of the host vehicle 1 captured by a CCD camera of the stereo camera 3. Generate an image. Then, based on this data, a well-known grouping process is performed and compared with frames (windows) such as three-dimensional road shape data, side wall data, and three-dimensional object data stored in advance. Sidewall data such as guardrails and curbs, and three-dimensional object data such as vehicles are extracted.

  The white line data, the side wall data, and the three-dimensional object data extracted in this way are assigned different numbers for each data. Further, regarding the three-dimensional object data, the stopped object and the order of moving in the same direction as the own vehicle 1 are determined from the relationship between the relative change in the distance from the own vehicle 1 and the vehicle speed of the own vehicle 1. It is classified and output as a moving object. Then, for example, among the forward moving objects protruding into the own vehicle traveling area, the three-dimensional object closest to the own vehicle 1 is registered as a preceding vehicle, which is detected continuously for a predetermined time.

  On the other hand, the detection of the driver's line of sight in the present embodiment is performed by a so-called pupil / corneal reflection method. Therefore, the visual field camera 5 is composed of a camera equipped with an infrared CCD, and the infrared lamp 6 is composed of an LED lamp. The field-of-view camera 5 captures a virtual image formed on the cornea by infrared rays irradiated from the infrared lamp 6 together with the pupil center. The line-of-sight detection device 7 detects the line of sight by detecting the behavior of a virtual image on the cornea that is translated by eye movement based on the difference between the centers of rotation of the cornea and the eyeball, using the pupil center as a reference. As described above, the visual field camera 5, the infrared lamp 6, and the line-of-sight detection device 7 realize the function as the line-of-sight detection means. The detection of the line of sight is not limited to such a detection method, and other detection methods (for example, EOG (Electro-Oculography) method, scleral reflection method, corneal reflection method, search coil method, etc.) are available. May be applied.

  The control unit 8 is input with the own vehicle traveling path, traveling region, preceding vehicle information, and three-dimensional object information other than the preceding vehicle from the stereo image recognition device 4, and the gaze behavior signal of the driver 100 ( The unit is an angle), and the vehicle speed Vo is further input from the vehicle speed sensor 11.

  At this time, as shown in FIG. 2, the width information of the preceding vehicle from the stereo image recognition device 4 is given in length units (W in FIG. 2), and the driver's gaze behavior is given in angle units. For example, as shown in FIG. 3, the width W of the preceding vehicle is converted into a value α in angular units.

This conversion formula is based on the following formula (4).
α = 2 · arctan ((W / 2) / L) (4)
Here, L is the inter-vehicle distance.

Also, from the gaze behavior signal of the driver 100 input to the control unit 8, a dispersion value β is calculated by the following equation (5) as a value indicating the gaze behavior variation with respect to the preceding vehicle. That is, a gazing point on the virtual plane is calculated based on the rotation angle of the eyeball. When the horizontal component of the gazing point on the virtual plane is xi and a certain time span [t1, t2] (for example, 30 to 60 seconds) is set, the horizontal dispersion value β during that time is
β = (1 / (t2−t1 + 1)) · Σ _{j = t1} ^t2 (xj ² −xa ² ) (5)
Here, xa is an average value and is obtained by the following equation (6).

xa = (1 / (t2−t1 + 1)) · Σ _{j = t1} ^t2 xj (6)
Note that the standard deviation sx may be used as a value indicating the variation in the line-of-sight behavior with respect to the preceding vehicle.
sx = ((1 / n) · Σ _{j = t1} ^t2 (xj ² −xa ² )) ^1/2 (7)
Then, the control unit 8 calculates the ratio of the width α of the preceding vehicle to the variance value β of the gaze behavior of the driver 100 as the attention evaluation value Sh representing the attention state (Sh = α / β). When the evaluation value Sh is equal to or higher than a preset evaluation value Shc (for example, 0.1) (for example, in a state of β1 with respect to β0 in FIG. 3), the driver 100 is careful about the preceding vehicle. It is determined that the state is strong. On the other hand, when the attention evaluation value Sh is smaller than the preset evaluation threshold Shc (for example, in the case of β2 with respect to β0 in FIG. 3), the control unit 8 is a driver for the preceding vehicle. It is determined that the attention state of 100 is not strong.

  The control unit 8 estimates that the effective visual field of the driver 100 is narrow when it is determined that the attention state is strong, and estimates that the effective visual field of the driver 100 is wide when it is determined that the attention state is not strong.

  Thus, in this embodiment, the control unit 8 has a function as an effective visual field estimation means. In the above description, an example of a method of classifying the driver 100 into a binary value indicating whether the effective field of view of the driver 100 is wide or narrow based on the variation in the line-of-sight behavior with respect to the preceding vehicle has been described. Of course, it may be classified. Further, for example, the estimation of the effective field of view when no preceding vehicle is detected can be performed using the vehicle speed or the like as a parameter. That is, when the host vehicle 1 is traveling at a low speed, a situation in which the host vehicle 1 is traveling on a narrow road or a situation in which the host vehicle travel path is congested is expected. Since 100 tends to gaze forward, it can be estimated that the effective visual field is narrow. On the other hand, when the host vehicle 1 is traveling at a high speed, a situation in which the host vehicle 1 is traveling on a relatively wide traveling path, a situation in which the host vehicle traveling path has few obstacles, and the like are expected. In such a case, since the driver's 100 gaze tends to be slow, it can be estimated that the effective visual field is wide.

  Further, the control unit 8 is configured to display information on the display device 10 based on, for example, the effective visual field information of the driver 100 estimated as described above and the gaze information of the driver 100 detected by the gaze detection device 7. The display form of the image 10a is variably controlled.

  That is, in the present embodiment, the control unit 8 variably controls the size (display size) of the image 10a displayed on the display device 10 according to the line of sight of the driver 100, for example. In addition, the control unit 8 variably controls the contrast of the image 10 a displayed on the display device 10 according to the effective field of view of the driver 100. The control unit 8 can control only the display size based on the line of sight or only the contrast based on the effective visual field, as the display mode control of the image 10a.

  Specifically describing each control, the control unit 8 expands or contracts the display size of the image 10a with respect to the change in the retinal eccentricity E of the driver 100 with respect to the display device 10 (image 10a) due to the movement of the line of sight. The peripheral visual acuity of the driver 100 with respect to the image 10a is kept constant. That is, the control unit 8 enlarges the image 10a displayed on the display device 10 as the retinal eccentricity E of the driver 100 increases, and reduces the image 10a displayed on the display device 10 as the retinal eccentricity E decreases. To do. The retinal eccentricity E is an angle formed by three points of a line of sight (gaze position), an intraocular focal position (image formation position), and an object (image 10a on the display 10 in the present embodiment). (See FIG. 1). The peripheral visual acuity refers to visual acuity in the peripheral visual field that is distant from the central visual field.

In this case, the control unit 8 keeps the peripheral visual acuity of the driver 100 with respect to the image 10a constant, for example, by changing the display size F of the image 10a so as to satisfy the relationship of the following expression (8).
F = 1 + E / E2 (8)
Here, in the equation (8), E2 is a coefficient.

The coefficient E2 is “1” in the visual acuity defined by the Landolt ring C, for example. In this case, for example,
When retinal eccentricity E = 10 degrees, F = 1 + 10/1 = 11
When retinal eccentricity E = 15 degrees, F = 1 + 15/1 = 16
It becomes. Therefore, when the visual acuity defined by the Landolt ring C is used, when the line of sight moves and the retinal eccentricity E changes from 10 degrees to 15 degrees, the display size of the image 10a may be increased by 1.45 times. (See FIGS. 5A and 5B). In FIG. 5, reference numeral 1 a indicates the windshield of the vehicle 1, and the line-of-sight direction of the driver 100 viewed from the inside of the windshield 1 a is indicated by a star. Here, the coefficient E2 may be variably set for each display pattern of the image 10a, for example.

  Further, the control unit 8 variably controls the contrast of the image 10a so that the contrast becomes lower as the effective visual field becomes wider and the contrast becomes higher as the effective visual field becomes narrower.

  Thus, in this embodiment, the control unit 8 has a function as display control means.

Next, the information display control executed by the control unit 8 will be described with reference to the flowchart of the information display control routine shown in FIG.
This routine is repeatedly executed every set time. When the routine starts, the control unit 8 first reads the line-of-sight information of the driver 100 detected by the line-of-sight detection device 7 in step S101, and this line-of-sight information. Based on the above, the retinal eccentricity E for the display device 10 (image 10a) is calculated.

  In subsequent step S <b> 102, the control unit 8 estimates the effective visual field of the driver 100 based on, for example, variations in the line-of-sight behavior of the driver 100.

  Then, when proceeding from step S102 to step S103, the control unit 8 checks whether or not the line of sight of the driver 100 has moved by a predetermined angle or more, and determines that the amount of movement of the line of sight is less than the set value. Proceed to step S105.

  On the other hand, if it is determined in step S103 that the driver's line of sight has moved by the set angle or more, the control unit 8 proceeds to step S104, and the image 10a before and after the movement of the line of sight is moved based on the above equation (8). The magnification for maintaining the peripheral visual acuity constant is calculated. Then, the control unit 8 changes the display size of the image 10a displayed on the display device 10 based on the calculated magnification, and then proceeds to step S105.

  When the process proceeds from step S103 or step S104 to step S105, the control unit 8 checks whether or not the effective field of view has changed by a set value or more, and determines that the change amount of the effective field of view is less than the set value. Exit the routine.

  On the other hand, when it determines with the effective visual field having changed more than setting in step S105, the control unit 8 progresses to step S106. When the effective field of view changes from a wide state to a narrow state, the control unit 8 changes the contrast of the image 10a displayed on the display device 10 to a high value side, so that the effective field of view changes from a narrow state to a wide state. If it has changed, the contrast of the image 10a displayed on the display device 10 is changed to the low value side, and then the routine is exited.

  According to such an embodiment, the virtual image formed on the cornea of the driver 100 by irradiation of infrared rays and the center of the pupil are imaged by the visual field camera 5, and the line of sight of the driver 100 is detected based on the captured image. By expanding or reducing the display size of the image 10a displayed on the display device 10 according to the change in the retinal eccentricity E with respect to the display device 10 of the detected line of sight, the peripheral visual acuity of the image 10a with respect to the line of sight of the driver 100 is kept constant. Even when the line of sight of the driver 100 moves, it is possible to perform information display using the image 10a that can be suitably viewed.

  In addition, the effective field of view of the driver 100 is estimated, and the contrast of the image 10a is set higher as the estimated effective field or narrower, and the contrast of the image 10a is set lower as the effective field becomes wider. Visibility can be made more suitable.

  Next, FIGS. 6 to 8 relate to the second embodiment of the present invention, FIG. 6 is a schematic configuration diagram of a head-up display device, FIG. 7 is a flowchart showing an information display control routine, and FIG. It is explanatory drawing which shows the relationship with a display form. Here, in the present embodiment, the information display device 2 displays information by using a head-up display device 30 which is an example of a projection device as a display unit instead of the display device 10. In addition, about the structure similar to the above-mentioned 1st Embodiment, a same sign is attached | subjected and description is abbreviate | omitted.

  As shown in FIG. 6, the head-up display device 30 is, for example, disposed under the windshield 1 a and includes a display element 32 and a housing 31 disposed in an instrument panel (not shown). The mirror 33 is built in and the main part is configured.

  As the display element 32, for example, a self-luminous element such as a VFD (Vacuum Fluorescent Display) or an element using a light source such as an LCD (Liquid Crystal Display) is preferably used. It is possible to display.

  The mirror 33 reflects the image displayed on the display element 32 toward the windshield 1a. In this case, a translucent part 31a is provided in a part of the casing 31, and an image of the display element 32 reflected by the mirror 33 is transmitted through the translucent part 31a and projected onto the windshield 1a. . As a result, an image (virtual image) 35 is formed in front of the windshield 1a, and the driver 100 can recognize the image 35 superimposed on the scenery outside the vehicle 1.

  Here, the mirror 33 is provided with an actuator 34 for changing the angle of the mirror 33. The control unit 8 is connected to the actuator 34, and the control unit 8 projects the image displayed on the display element 32 to an arbitrary position on the windshield 1a by changing the angle of the mirror 33 through the actuator 34. It is possible.

  Then, the control unit 8 keeps the peripheral visual acuity of the image 35 with respect to the line of sight of the driver 100 by variably controlling the position of the image 35 following the movement of the line of sight of the driver 100.

  That is, as shown in FIGS. 8A and 8B, the control unit 8 follows the movement of the line of sight of the driver 100 to variably control the display position of the image 35, thereby the above-described equation (8). The retinal eccentricity E in the inside is kept constant. As a result, the control unit 8 keeps the peripheral visual acuity for the line of sight of the driver 100 constant while maintaining the display size F of the image 35 constant. In this case, in order to reduce the uncomfortable feeling when the driver 100 recognizes the image 35 in the peripheral visual field, it is desirable that the depression angle (or elevation angle) θ from the center of the line of sight to the image 35 is kept constant.

  Such information display control is performed, for example, according to the flowchart of the information display control routine shown in FIG. Note that the flowchart of the information display control routine of the present embodiment is mainly obtained by changing the processing in step S104 of the first embodiment described above.

  That is, in the information display control of the present embodiment, when the process proceeds from step S103 to step S114, the control unit 8 calculates the retinal eccentricity E with respect to the image 35 before and after the movement of the line of sight based on the above equation (8). The display position for keeping constant is calculated. Then, the control unit 8 moves the image 35 to the calculated display position through drive control of the actuator 34, and then proceeds to step S105. Although detailed description is omitted, the contrast of the image 35 is changed by changing the contrast of the image displayed on the display element 32.

  According to such an embodiment, the virtual image formed on the cornea of the driver 100 by irradiation of infrared rays and the center of the pupil are imaged by the visual field camera 5, and the line of sight of the driver 100 is detected based on the captured image. By controlling the display position of the image 35 (projection position with respect to the windshield 1a) so that the retinal eccentricity E with respect to the detected line of sight is constant, the peripheral visual acuity of the image 35 with respect to the line of sight of the driver 100 is kept constant. Even when the line of sight of 100 moves, information can be displayed by the image 35 that can be suitably viewed.

1 ... Vehicle (own vehicle)
DESCRIPTION OF SYMBOLS 1a ... Windshield 2 ... Information display apparatus 3 ... Stereo camera 4 ... Stereo image recognition apparatus 5 ... Field-of-view camera (line-of-sight detection means)
6 ... Infrared lamp (line-of-sight detection means)
7: Gaze detection device (gaze detection means)
8 ... Control unit (display control means, effective visual field estimation means)
10: Display device (display means)
DESCRIPTION OF SYMBOLS 10a ... Image 11 ... Vehicle speed sensor 12 ... Steering angle sensor 13 ... Yaw rate sensor 30 ... Head-up display apparatus (display means)
DESCRIPTION OF SYMBOLS 31 ... Housing 31a ... Translucent part 32 ... Display element 33 ... Mirror 34 ... Actuator 35 ... Image 100 ... Driver

Claims (6)

Gaze detection means for detecting the gaze of the driver ;
Display means for displaying information to the driver ;
Display control means for variably controlling the display form of the image displayed by the display means so that the peripheral visual field power of the image with respect to the line of sight is kept constant ;
An effective visual field estimating means for estimating an effective visual field of the driver;
The information display apparatus according to claim 1, wherein the display control means sets the contrast of the image displayed on the display means to be higher as the effective visual field becomes narrower . The display means is a display device fixed at a preset position,
2. The information display device according to claim 1, wherein the display control means maintains a peripheral visual acuity of the image with respect to the line of sight by controlling a size of an image displayed on the display device. . The display means is a projection device that displays the image at an arbitrary position by projection,
The information display apparatus according to claim 1, wherein the display control unit maintains a peripheral visual acuity of the image with respect to the line of sight by controlling a position of the projected image.   The display control means controls the display form of the information so as to keep the visual acuity defined by the Landolt ring constant with respect to the line of sight. The information display device described.   A preceding vehicle width detecting means for detecting the width of a preceding vehicle traveling in front of the host vehicle;
  5. The effective visual field estimation unit estimates the effective visual field of the driver based on a variance value of the gaze behavior of the driver and the width of the preceding vehicle. 6. The information display device described in 1.   6. The information according to claim 5, wherein the effective visual field estimation unit estimates the effective visual field based on a vehicle speed of the own vehicle when the width of the preceding vehicle is not detected by the preceding vehicle width detection unit. Display device.

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