JP2001071790A - Vehicular display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vehicular display device that enables easy recognition of obstructions existing far from one's own vehicle. SOLUTION: With an automatic mode selected in S1 as well as a zoom-on/off switch set on in S4, if the distance D between one's own vehicle and a detected obstruction is larger than a display threshold Th, the image of the obstruction included in infrared images is enlarged on the screen in S8 to S10. The display threshold Th as the criterion of the distance D is set larger is S7 as the vehicle speed is higher.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a display device for a vehicle, and more particularly to a display device suitable for being mounted on a typical vehicle such as an automobile.

[0002]

2. Description of the Related Art Conventionally, in order to assist a driver in a driving environment where visibility is poor such as at night or in dense fog, an image taken in front of a vehicle using infrared rays is displayed on a display provided in front of a driver's seat. For example, Japanese Patent Application Laid-Open No. 60-231193 and Japanese Patent Application Laid-Open No.
No. 84 or Japanese Patent Application Laid-Open No. 10-230805.

[0003]

According to the display devices proposed in these prior arts, it is possible to effectively assist the driver's vision, but when an obstacle located far away is photographed, Since the obstacle is displayed small in the infrared image, the driver cannot recognize at a glance what is being displayed on the display screen, and cannot effectively assist the driver's vision. .

Accordingly, an object of the present invention is to provide a display device of a vehicle which can easily recognize an obstacle located far from the host vehicle.

[0005]

In order to achieve the above object, a vehicle display device according to the present invention has the following configuration.

That is, a photographing device provided in a vehicle for photographing the front of the vehicle using, for example, infrared rays, and a display for displaying an image photographed by the photographing device in front of a driver's seat of the vehicle. Detecting means for detecting an obstacle existing in front of the vehicle and detecting a distance between the obstacle and the vehicle; and a distance between the obstacle and the vehicle detected by the detecting means being greater than a predetermined value. A display control unit for enlarging and displaying at least the image portion of the obstacle in the image captured by the image capturing device when the image is long.

The vehicle further includes running state detecting means or running environment detecting means for detecting a running state (vehicle speed or the like) or running environment (weather or the like) of the vehicle, and the display control means detects the detected running state or running environment. The start timing of enlarging and displaying the image portion of the obstacle on the display may be adjusted by changing the predetermined value or correcting the distance between the obstacle and the vehicle in accordance with the following.

[0008]

According to the present invention described above, it is possible to provide a display device for a vehicle which can easily recognize an obstacle located far from the host vehicle.

In other words, according to the first aspect of the present invention, the enlarged display is performed only when the detected obstacle exceeds the predetermined value and is located far away, thereby assisting the visual sense without giving the driver an uncomfortable feeling. And accurate driving support can be provided.

According to the second and fourth aspects of the present invention, an enlarged display of an obstacle can be displayed, for example, during high-speed running where quick judgment is required, or in stormy weather when driving operation requires a mental burden. Since the start timing can be advanced, more accurate driving support can be performed.

According to the third aspect of the present invention, the driver is surprised by the start of the enlarged display when the vehicle is performing a turning operation in which the driving operation is mentally burdensome as compared with the straight driving. Can be prevented.

Further, according to the invention of claim 5, the driver can easily recognize that the enlarged display is being performed.

Further, according to the invention of claim 6, since the function of the enlarged display can be turned on / off according to the driver's preference, the convenience can be improved.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a vehicle display device according to the present invention will be described in detail with reference to the drawings as an embodiment in which the display device is applied to a typical automobile.

FIG. 1 shows a first embodiment of the present invention.
It is a block configuration diagram of a display device of a vehicle in the embodiment.

In FIG. 1, reference numeral 2 denotes a CCD (Charge Coup) for detecting the distance to an obstacle in front of the host vehicle by a general method.
led Device) An obstacle sensor such as a camera, a laser radar, or a millimeter-wave radar. Reference numeral 3 denotes an infrared (infrared) camera that captures an environment in front of the host vehicle using infrared light.

Reference numeral 4 denotes a vehicle speed sensor for detecting a vehicle speed as a running state of the own vehicle. Reference numeral 5 denotes a steering angle sensor that detects a steering angle of the host vehicle.

Reference numeral 8 denotes a display such as a liquid crystal display or a head-up display for displaying an image taken by the infrared light camera 3 (hereinafter referred to as an infrared image). Here, the display 8 is located in front of the driver's seat of the host vehicle and at a position where the driver can easily see an infrared image without performing a large line-of-sight movement when the driver stares ahead (near the center position of the dashboard. May be arranged).

Reference numeral 11 denotes a wiper switch capable of setting an operation state such as a start / stop and an operation speed (cycle) of the wiper provided in the host vehicle. Reference numeral 12 denotes a fog lamp switch provided on the host vehicle and capable of turning on and off a fog lamp. Reference numeral 13 denotes a headlight switch provided on the host vehicle and capable of turning on and off a headlight.

Reference numeral 14 denotes a power switch that allows an operator to turn on and off power supply to the display control device 1. 15 is
A mode changeover switch that allows the operator to switch the display mode of the infrared image on the display 8. The display modes selectable by this switch include a manual mode in which an infrared light image is displayed on the display 8 while the operator turns on the manual on / off switch 17, and an auto mode by the mode switch 15. There is an auto mode in which when selected, an infrared image is displayed on the display 8 in accordance with a display control process described later.

Reference numeral 16 denotes a zoom on / off switch 16 for selecting whether to enlarge (zoom) and display an image of an obstacle included in the infrared image when the auto mode is selected by the mode changeover switch 15. It is.

The manual on / off switch 17 is a switch for displaying an infrared image on the display 8 while the operator is in the on state when the manual mode is selected by the mode changeover switch 15. .

The display controller 1 controls the display of the infrared image on the display 8 based on the output signals (data corresponding to the output signals) of the respective sensors and the detected operation states of the operation switches. (Details will be described later). The display control process by the display control device 1 is performed by RA
While using M102 as a work area,
CPU according to the software stored in M103 etc.
This is executed by 101.

Next, in this embodiment, the display control device 1
A specific display control process performed by the server will be described.

FIG. 2 is a flowchart of a display control process performed by the display device of the vehicle according to the first embodiment. The CPU 101 operates while the ignition key switch of the host vehicle is on and the power switch 11 is on. The procedure of the software to be executed is shown.

In FIG. 5, step S1: it is determined whether or not the automatic mode is selected by detecting the operation state of the mode changeover switch 15. When the determination is NO (manual mode), the flow proceeds to step S2. , YES (auto mode), step S4
Proceed to.

Step S2: Since the manual mode has been selected, it is determined whether or not the manual on / off switch 17 has been set to the on state.
When ES (switch 17: on), the process proceeds to step S11 to start or continue the display of the infrared image, and when NO (switch 17: off), the process proceeds to step S3 to stop the display of the infrared image.

Step S3: The display of the infrared image on the display 8 is stopped or the stopped state is continued.

Step S4: Since the auto mode has been selected, it is determined whether or not the zoom on / off switch 16 has been set to the on state. If the determination is YES (the switch 16 is on), the flow proceeds to step S5. If NO (the switch 16 is OFF), the process proceeds to step S11 to start or continue to display the infrared image captured by the infrared camera 3.

Step S5: Data corresponding to the output signal of each sensor described with reference to FIG. 1 and a signal representing the operation state of each switch are read.

Step S6: The data corresponding to the output signals of the vehicle speed sensor 4 and the steering angle sensor 5 obtained in step S5 is used to determine whether or not the own vehicle is currently turning and running. It is determined whether the speed is larger than the speed and the steering angle is larger than a predetermined angle. When the determination is YES (turning), the process proceeds to step S11 to start or continue the display of the infrared image captured by the infrared camera 3, and when the determination is NO (not turning), the process proceeds to step S7. move on.

Here, the reason why the enlarged display of the obstacle is not performed during the turning operation of the own vehicle is that there are generally more information to be determined and operations to be performed by the driver in the turning operation than in the straight driving. This is because a mental burden is imposed on the driving operation, and there is a reason to prevent the driver from being surprised when the enlarged display is started in such a situation.

Step S7: By referring to a map (table) stored in the ROM 103 in advance, an infrared image display is performed in accordance with the size of the data corresponding to the output signal of the vehicle speed sensor 4 obtained in step S5. A display threshold value Th is set as a criterion for determining whether or not to perform the zoom display when the display on the display 8 is performed. As specific characteristics of the display threshold Th stored in this map, a larger threshold may be set as the vehicle speed increases.

Step S8: Based on data corresponding to the output signal of the obstacle sensor 2 obtained in step S5, it is determined whether there is an obstacle ahead of the host vehicle, and YES is determined in this determination.
If (there is an obstacle), the process proceeds to step S9 and NO
If (there is no obstacle), the process proceeds to step S11 in order to start or continue to display the infrared image captured by the infrared light camera 3.

Step S9: Based on the data corresponding to the output signal of the obstacle sensor 2 obtained in step S5, the position of the obstacle and the distance D between the obstacle and the host vehicle are determined.
And determines whether or not the distance D is greater than the display threshold Th set in step S7.
When the determination is YES (D> Th), the obstacle is located far away, and it is difficult for the naked eye to recognize the display content. Therefore, the process proceeds to step S10 to perform the enlarged display.
If NO (D ≦ Th), the process proceeds to step S11 to start or continue the display of the infrared image captured by the infrared camera 3.

Step S11: The display of an infrared image (for example, an image without the inner frame from the image illustrated in FIG. 5) as photographed by the infrared light camera 3 is started or continued.

Step S10: The obstacle detected by the obstacle sensor 2 is associated with the image of the obstacle included in the infrared image taken by the infrared camera 3, and the image of the obstacle is displayed on the display 8. The zoom amount that can be displayed in the full vertical or horizontal length is calculated, and a partial image corresponding to the zoom amount is extracted from the image captured by the infrared light camera 3. Then, an enlarged image obtained by subjecting the extracted partial image to a general digital zoom process is displayed on the display 8 (for example, as shown in the display example of FIG. 6 with respect to the image captured by the infrared camera 2 shown in FIG. 5). I do. When displaying the enlarged image on the display 8 in this step, a symbol indicating that the image is in an enlarged state as shown in FIG. 6 may be displayed together so that the driver can recognize that fact.

Here, a specific method for associating the obstacle detected by the obstacle sensor 2 with the image of the obstacle included in the infrared image captured by the infrared light camera 3 will be described.

FIG. 4 is a diagram showing a state in which the detection range of the obstacle sensor 2 is viewed from above. The detection range corresponding to the image captured by the infrared light camera 3 shown in FIG. , An obstacle A (preceding other vehicle) and an obstacle B (pedestrian) are included.

In this embodiment, the detection results of the obstacle A and the obstacle B by the obstacle sensor 2 are based on the distance Da between the host vehicle and the obstacle A and the angle θa (≒ 0) formed between the vehicle and the center axis,
And the distance Db between the host vehicle and the obstacle B and the angle θb with the center axis.

Therefore, if the positional relationship between the central axis in the detection range of the obstacle sensor 2 and the coordinate axis of the imaging plane (angle of view) of the infrared camera 3 is previously associated, the obstacle sensor 2
As shown in FIG. 3, the distance D and the angle θ to the obstacle output from are counted as the number of lines (the number of pixels) from the lower side of the imaging surface, as shown in FIG.
The angle θ is counted as the number of pixels from the left and right center lines of the imaging surface, so that the radiant heat source including the position (pixel) in the imaging surface specified by the count is:
It can be determined that it corresponds to the entire shape (pixel group) of the obstacle detected by the obstacle sensor 2. Therefore, if such processing is performed in step S10, the display control device 1 is made to recognize the partial image of the obstacle included in the image captured by the infrared camera 3 and the distance D to the obstacle in association with each other. be able to.

In the process of step S10, when it is determined from the data corresponding to the output signal of the obstacle sensor 2 obtained in step S5 that there are a plurality of obstacles, which of the obstacles is In order to recognize whether the obstacle is present at the closest position, the obstacle D having the shortest distance among the distances D of the plurality of obstacles is shown in FIG.
It is preferable to display the value of the separation distance in a state of being overwritten on the enlarged display of the obstacle as in the display example of FIG.

In the process of step S10, the distance D included in the data corresponding to the output signal of the obstacle sensor 2 is compared with the display threshold Th, but in a running environment such as fog or rain. For example, the display threshold value T is set so that the image of the detected obstacle is enlarged and displayed earlier.
Prior to the comparison with the distance h, the distance D is set to the wiper switch 1
The greater the operating state of the fog lamp switch 11 is, the larger the operating speed is (i.e., the shorter the operating cycle is). It should be corrected to a value. Or, conversely, prior to the comparison with the display threshold Th, the display threshold T set in step S7 is set.
h is corrected to a smaller value when the operation state of the wiper switch 11 indicates a higher operation speed (that is, as the operation cycle is shorter), or when the operation state of the fog lamp switch 11 indicates the lighting state, It may be corrected to a smaller value as compared with.

Similarly, in the process of step S9, the display threshold value Th set in step S7 is compared with the detected distance D in accordance with the detected vehicle speed. The threshold Th may be a constant, and the distance D may be corrected according to the vehicle speed.

Further, instead of performing the enlarged display as shown in FIG. 6, only the obstacle located closest to the host vehicle is displayed in a deformed state as shown in FIG. As shown in (2), the reduced image of the original infrared image A including the obstacle B and the enlarged obstacle B may be displayed simultaneously. Since image processing for realizing these display modes is common at present, detailed description in this embodiment is omitted.

According to the above-described embodiment, when the auto mode is selected and the zoom on / off switch 16 is set to on, the distance D between the host vehicle and the obstacle is set to be smaller than the display threshold Th. When the size is large, the image of the obstacle included in the infrared image is enlarged and displayed, so that the driver can easily recognize the obstacle located far from the host vehicle.

The display threshold value Th used for determining whether or not to perform enlarged display is set to a larger value as the detected vehicle speed is higher. This allows the driver to:
At the time of high-speed running, an obstacle existing in front of the vehicle can be recognized at an early stage, and an avoidance operation or the like can be performed with a margin.

Further, the display threshold value Th is corrected according to the driving environment estimated according to the operating state of the wiper and the lighting state of the fog lamp prior to determining whether or not to perform the enlarged display. In stormy weather when a heavy burden is imposed, the enlarged display is started earlier than in fine weather, so that the driver's vision can be accurately supported.

In the present embodiment, the above-described display control is performed in the automatic mode. However, the above-described process of enlarging and displaying an obstacle may be performed when an image is displayed on the display 8 in the manual mode. good.

[Second Embodiment] Next, a second embodiment based on the vehicle display device according to the first embodiment will be described. In the following description, the same configuration as that of the first embodiment will not be described repeatedly, and the description will focus on the characteristic portions of the present embodiment.

FIG. 10 is a flowchart of a display control process by the display device of the vehicle according to the second embodiment, in which the CPU 101 operates while the ignition key switch of the vehicle is on and the power switch 11 is on. The procedure of the software to be executed is shown.

In the figure, steps S21 to S25: Step S1 in the first embodiment (FIG. 2)
The processing similar to the processing from step S5 to step S5 is performed. If the result of the determination in step S24 is that the zoom is off, the process proceeds to step S32.

Step S26: Referring to a map (table) stored in the ROM 103 in advance,
In accordance with the operating environment (operating speed, operating cycle) of the wiper and the driving environment estimated according to the lighting state of the fog lamp, it becomes a criterion for determining whether or not to perform zoom display when displaying the infrared image on the display 8. Display threshold Th
Set. As a specific process, the display threshold Th
To the wiper switch 11 obtained in step S25.
The greater the operating state of the device represents a higher operating speed (ie,
Set a smaller value (the shorter the operation cycle). Alternatively, when the operation state of the fog lamp switch 11 indicates the lighting state, the display threshold value Th is set to a smaller value as compared with the case where the fog lamp switch 11 is turned off.

Steps S27 and S28: Steps S8 and S in the first embodiment (FIG. 2)
Similarly to the processing in step 6, if there is an obstacle, and if there is an obstacle, it is determined whether or not the own vehicle is turning, and if not, the process proceeds to step S30.

Step S29: Since the own vehicle is turning, it is not preferable that the detected obstacle relatively approaches the traveling path on which the own vehicle travels. Therefore, in this step, it is determined whether or not the detected obstacle is moving in a direction away from the turning direction of the host vehicle, or whether or not the detected obstacle is stopped. In the case of (approaching state), the process proceeds to step S30 because the obstacle should be enlarged and displayed. In the case of YES (the obstacle is moving in the opposite direction or has stopped), the infrared light camera 3 Step S3 to start or continue the display of the infrared image as captured
Proceed to 2.

As a specific process in this step, based on the data representing the output signals of the vehicle speed sensor 4 and the steering angle sensor 5 obtained in step S25, the traveling path of the own vehicle (the own vehicle Predicted route)
And the position data obtained by performing coordinate conversion on the position data of the obstacle detected by the obstacle sensor 2 in the previous control cycle in the coordinate system of the estimated traveling path and the position data obtained in step S25 in the current control cycle. And compares the obtained position data of the obstacle. Then, as a result of the comparison, when the two position data in the coordinate system indicate the same location, the obstacle can be determined to be in the stopped state, and when the two different data indicate different locations, it can be determined that the obstacle is moving. Further, when the obstacle is moving, it is determined whether or not the direction of the velocity vector represented by the two position data is the direction approaching the traveling path calculated in this step. It can be determined whether the obstacle is moving in a direction relatively approaching the own vehicle.

The above estimating method of the traveling route is as follows.
For example, Japanese Patent Application Laid-Open No. Hei 10-1008 by the present applicant
No. 20, the detailed description of the present embodiment is omitted.

Steps S30 to S32: Steps S9 to S in the first embodiment (FIG. 2)
In the step S30, the display threshold value Th set in the step S26 is compared with the distance D between the obstacle detected by the obstacle sensor 2 and the display mode illustrated in FIGS. And according to the comparison result,
In step S31, enlarged display is performed, and in step S32, an infrared image as captured by the infrared camera 3 is displayed.

According to the above-described embodiment, when the auto mode is selected and the zoom on / off switch 16 is set to on, the driver can easily recognize an obstacle located far from the host vehicle. In addition, in the event of stormy weather, when the mental load on the driving operation increases according to the driving environment estimated according to the operating state of the wiper and the lighting state of the fog lamp, the enlarged display is started earlier than in fine weather. Can accurately support the visual sense of the person.

When the own vehicle is turning, the enlarged display is performed only when the distance between the detected obstacle and the own vehicle is relatively small. When moving in the direction away from the vehicle, the image of the obstacle is not enlarged and displayed, so that the driver can be prevented from feeling uncomfortable.

[Third Embodiment] Next, a third embodiment based on the vehicle display device according to the first embodiment will be described. In the following description, the same configuration as that of the first embodiment will not be described repeatedly, and the description will focus on the characteristic portions of the present embodiment.

FIG. 11 is a flowchart of a display control process performed by the display device of the vehicle according to the third embodiment, in which the CPU 101 operates while the ignition key switch of the host vehicle is on and the power switch 11 is on. The procedure of the software to be executed is shown.

In the figure, steps S41 to S43: Step S1 in the first embodiment (FIG. 2)
The same processing as the processing from step S3 to step S3 is performed. When the determination result in step S41 is the auto mode,
Proceed to step S44.

Step S44: Headlight switch 1
It is determined whether or not 3 is set to the ON state. If the determination is YES (the switch 13 is on), the process proceeds to step S45. If the determination is NO (the switch 13 is off), the display of the infrared image is stopped. Step S
Proceed to 43.

Step S45: Since the auto mode is selected and the headlights are on, it is determined whether or not the zoom on / off switch 16 is set to the on state. 1
6: ON), the process proceeds to step S46, and if NO (the switch 16: OFF), the process proceeds to step S50 to start or continue the display of the infrared image captured by the infrared camera 3.

Steps S46 and S47: Data corresponding to the output signal of the obstacle sensor 2 is read (step S46), and it is determined whether or not an obstacle exists based on the data (step S47). If (an obstacle is present), the process proceeds to step S48 and N
In the case of O, the process proceeds to step S50 to start or continue the display of the infrared image captured by the infrared light camera 3.

Step S48: If there is only one obstacle at the location of the obstacle included in the data obtained in step S46 and the distance D between the obstacle and the host vehicle, if there is only one existing obstacle, the distance to the obstacle is determined. It is determined whether or not the distance D is larger than a predetermined low beam irradiation distance (range) stored in the ROM 103 in advance. When there are a plurality of obstacles, it is determined whether or not the distance D to the obstacle located closest to the host vehicle is longer than the predetermined low beam irradiation distance. In the determination in this step, when the distance D to the obstacle is larger than the predetermined low beam irradiation distance (YES in step S48), it can be determined that it is difficult for the driver's eyes to recognize the obstacle. When the distance D to the obstacle is smaller than the predetermined low beam irradiation distance (step S4), the process proceeds to step S49 to perform enlarged display of the obstacle (step S4).
8 is NO), the obstacle is present in the low-beam irradiation range, and the driver can determine that the obstacle in the state of being illuminated by the low-beam headlight can be visually recognized by the driver. The process proceeds to step S50 in order to start or continue displaying the infrared image captured by the external light camera 3.

Steps S49 and S50: Similar to the processing of steps S10 and S11 in the first embodiment (FIG. 2) and the display modes illustrated in FIGS. 6 to 9, enlarged display is performed in step S49. In step S50, an infrared image as captured by the infrared camera 3 is displayed.

According to the above-described embodiment, when the auto mode is selected and the zoom on / off switch 16 and the headlight switch 13 are set to on, the detection is performed based on the output signal of the obstacle sensor 2. When the obstacle is located farther than the range (distance) to be illuminated when the headlight is in a low beam, the image of the obstacle is enlarged and displayed, so that the driver can easily recognize the obstacle.

[Brief description of the drawings]

FIG. 1 is a block diagram of a display device of a vehicle according to a first embodiment of the present invention.

FIG. 2 is a flowchart of a display control process by the display device of the vehicle according to the first embodiment.

FIG. 3 is a diagram illustrating a coordinate system of an infrared image set corresponding to an output signal of an obstacle sensor 2.

FIG. 4 is a diagram showing a state where the detection range of the obstacle sensor 2 is viewed from above.

FIG. 5 is a diagram exemplifying an infrared image captured by the infrared light camera 3;

FIG. 6 is a diagram illustrating an example in which a partial image including an obstacle is displayed in an enlarged manner in an infrared image.

FIG. 7 is a diagram illustrating an example in which a partial image including an obstacle is displayed in an enlarged manner in an infrared image.

FIG. 8 is a diagram illustrating an example in which a partial image including an obstacle in the infrared image is enlarged and highlighted.

FIG. 9 is a diagram illustrating an example in which a reduced image of an infrared image and an enlarged display image of an obstacle are simultaneously displayed.

FIG. 10 is a flowchart of a display control process performed by the vehicle display device according to the second embodiment.

FIG. 11 is a flowchart of a display control process by a display device of a vehicle according to a third embodiment.

[Explanation of symbols]

 1: display control device, 2: obstacle sensor, 3: infrared light camera, 4: vehicle speed sensor, 5: steering angle sensor, 8: display, 11: wiper switch, 12: fog lamp switch, 13: headlight switch, 14: Power switch, 15: Mode switch, 16: Zoom on / off switch, 17: Manual on / off switch, 101: CPU, 102: RAM, 103: ROM,

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Hiroki Uemura 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. (72) Hidekazu Sasaki 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Mazda Co., Ltd. F-term (reference) 3D044 BA21 BB01 BD01 BD05 BD13

Claims (6)

[Claims] 1. A photographing device provided in a vehicle for photographing the front of the vehicle, an indicator for displaying an image photographed by the photographing device in front of a driver's seat of the vehicle, and a display device in front of the vehicle. Detecting means for detecting an obstacle to be detected and detecting the distance between the obstacle and the vehicle; and detecting the distance between the obstacle and the vehicle detected by the detecting means when the distance between the obstacle and the vehicle is longer than a predetermined value. Of the images taken by the at least the image portion of the obstacle,
A display device for a vehicle, comprising: display control means for enlarging and displaying the display. 2. The vehicle according to claim 1, further comprising a traveling state detection unit configured to detect a traveling state of the vehicle, wherein the display control unit changes the predetermined value according to the traveling state detected by the traveling state detection unit. The display device for a vehicle according to claim 1, wherein a start timing of enlarging and displaying an image portion of the obstacle on the display is adjusted by correcting a distance between the obstacle and the vehicle. 3. The display control device according to claim 1, wherein when the traveling state detection device detects that the vehicle is turning, the display control device prohibits the enlarged display of the image portion of the obstacle. Item 3. A display device for a vehicle according to Item 2. 4. A driving environment detecting means for detecting a driving environment of the vehicle, wherein the display control means changes the predetermined value according to the driving environment detected by the driving environment detecting means. The display device for a vehicle according to claim 1, wherein a start timing of enlarging and displaying an image portion of the obstacle on the display is adjusted by correcting a distance between the obstacle and the vehicle. 5. The display control means according to claim 1, wherein, when an image portion of the obstacle is enlargedly displayed on the display, a symbol indicating that the image is being enlargedly displayed is also displayed on the display screen. The display device for a vehicle according to claim 1, wherein 6. The vehicle display device according to claim 1, further comprising a manual switch capable of turning on and off an enlarged display of an image portion of the obstacle by the display control means.