JPH08178648A - Intervehicle distance detecting device - Google Patents

Abstract

PURPOSE: To accurately detect the distance to a preceding vehicle using light receiving elements one-dimensionally. CONSTITUTION: This intervehicle distance detecting device has a pair of lenses 1A, 1B provided at a fixed interval to each other, a line CCD module 2 inside which a number of light receiving elements, on each of which an image of the rear face of a preceding vehicle is focused through the lenses 1A, 1B, are provided on a straight line parallel to a line L2 connecting the lenses 1A, 1B, and an arithmetic means for calculating the distance to the preceding vehicle from the deviation of the distribution of luminous intersity detected by the line CCD module 2. The line CCD module 2 is inclined so as to have an angle to a horizontal line L1 that is principal line constituting the design of the rear face of the preceding vehicle.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an inter-vehicle distance detecting device, and more particularly to a device for detecting an image of the rear surface of a preceding vehicle by a pair of lenses provided at intervals and detecting the distance to the preceding vehicle by the parallax.

[0002]

2. Description of the Related Art The principle of a device for detecting distance by parallax will be described below. Line CCD in distance detection device
The module 2 has a pair of left and right lenses 1A and 1B as shown in FIG. 8, and a large number of light receiving elements are provided in the left and right directions at a rear focal length position to form a light receiving screen 6.
The object M in front of the lens X is imaged on the left side portion of the light receiving screen 6 by the left lens 1A, and the detected light intensity distribution of the light receiving screen 6 is as shown in FIG. 9, for example. Further, the image formation of the object M by the right lens 1B occurs on the right side portion of the light receiving screen 6 as shown in FIG. 10, and the detected luminous intensity distribution is as shown in FIG. After all, the detected light intensity distribution on the light receiving screen 6 formed by the image formation of the left and right lenses 1A and 1B has the same shape as shown in FIG. 12, and is shifted by n pixels in the left and right direction. If the pixel pitch is Ep, the deviation of the distribution of the detected light intensity is Ep.n.

In FIG. 13, a light receiving screen 6 by the left lens 1A is located at a point on the front X on the optical axis of the left lens 1A.
The image forming point above is P L, the image forming point by the right lens 1B is P
Assuming that R is the image point of the right lens 1B at a point at infinity by P ∞, X =
Bf / y. f is the focal length of each lens 1A, 1B,
Since the distance B between PL and P∞ is the lens interval, these are known, and if the distance y between PR and P∞ is known, the distance X can be calculated by the above formula. Here, the distance between PL and PR is equal to the above Ep.n because it is the shift of the image forming position by both lenses 1A and 1B. Therefore, y = EP.multidot.n-B, and the distance X can be known from the deviation amount n of the detected light intensity distribution.

By the way, in order to reduce the number of pixels of the light receiving elements constituting the light receiving screen 6 and reduce the cost, the light receiving elements are not arranged in a two-dimensional plane, but are arranged one-dimensionally on a straight line. There is.

[0005]

However, in the case where the light receiving elements arranged one-dimensionally on a horizontal straight line are adapted to receive the light within the range surrounded by each frame line on the rear surface of the preceding vehicle B in FIG. Since the main line that constitutes the design of the rear surface of the vehicle B is in the horizontal direction that coincides with the arrangement direction of the light receiving elements, the detected light intensities obtained from the respective light receiving elements have almost no difference in size (FIG. 15). ). When the difference in detected light intensity (contrast) between the light receiving elements is small as described above, it is difficult to accurately detect the deviation of the detected light intensity distribution (FIG. 16) between the left and right lenses 1A and 1B, which causes an error in distance measurement. There's a problem.

An object of the present invention is to solve the above problems and an object of the present invention is to provide an inter-vehicle distance detecting device capable of accurately detecting the inter-vehicle distance from a preceding vehicle by means of a one-dimensionally arranged light receiving element.

[0007]

In the first structure of the present invention, a plurality of lenses are provided on a straight line parallel to a line connecting the lenses, and a pair of lenses provided at regular intervals. An inter-vehicle distance detecting device having a light receiving element on which an image of the rear surface of a vehicle is formed and a calculating means for calculating a distance to a preceding vehicle from a deviation of detected light intensity distributions in these light receiving elements constitutes a design of the rear surface of the preceding vehicle. The lens and the light receiving element are arranged so as to form an angle with respect to the main line.

In the second structure of the present invention, the rotation driving means for rotating the pair of the lens and the light receiving element integrally to change the arrangement direction of the light receiving elements with respect to the main lines forming the design of the rear surface of the preceding vehicle. Further provide.

In the third structure of the present invention, rotation control means for activating the rotation drive means is further provided to an angular position where the light intensity difference of the detected light intensity distribution in the light receiving element becomes a predetermined value or more.

[0010]

In the first structure described above, the direction of arrangement of the pair of lenses provided at regular intervals and the light-receiving elements arranged one-dimensionally on a straight line is the main line forming the design of the rear surface of the preceding vehicle. Since they form an angle with respect to each other, a large difference in detected light intensity of each light receiving element appears. Therefore, it becomes possible to accurately detect the deviation of the detected light intensity distribution by the left and right lenses, and the inter-vehicle distance to the preceding vehicle can be obtained with high accuracy.

In the second structure, no matter which direction the main lines forming the design of the rear surface of the preceding vehicle extend, the arrangement direction of the light receiving elements can be always positioned at an angle. .

In the third structure, the light receiving element is immediately rotated to the optimum position, which enables rapid inter-vehicle distance detection.

[0013]

【Example】

(Embodiment 1) In FIG. 1, an inter-vehicle distance detecting device 5 is provided on the upper side of a windshield W of a vehicle, and a line CCD module 2 (for example, FM6222T manufactured by Fuji Electric Co., Ltd.) is provided in front of the device 5. ) A pair of lenses 1
A and 1B are spaced apart. Above line CC
As described in the prior art, the D module 2 has a built-in light receiving screen (line CCD) in which a large number of light receiving elements are arranged one-dimensionally on a straight line parallel to the line L2 connecting the lenses 1A and 1B. . The line L2 connecting the two lenses 1A and 1B is inclined with respect to the horizontal line L1 of the vehicle.

In FIG. 2, the CPU 3 in the apparatus 5 outputs a signal designating the light receiving element number in the line CCD module 2 for which the light intensity signal is desired to be output through the shift register 31, and the line CCD module 2 outputs the signal. The reciprocal of the distance calculated based on the detected light intensity signal in the light receiving element array within a certain range including the designated light receiving element is output via the shift register 32. The signal transfer of the shift registers 31 and 32 and the line CCD module 2 is synchronized with the clock pulse from the oscillation circuit 33.

Since the light receiving elements of the line CCD module 2 are arranged so as to be inclined with respect to the horizontal line, the light receiving range of each light receiving element constitutes the design of the rear surface of the preceding vehicle B as shown by the frame line in FIG. While the main lines are horizontal or vertical, they form an angle with the lines of these designs. Therefore, the detected light intensity obtained from each light receiving element by the image formation of one lens shows sufficient contrast as shown in FIG. 4, and this detected light intensity distribution and the detected light intensity distribution obtained by the image formation of the other lens. By calculating the amount of deviation by the CPU 3, the inter-vehicle distance from the preceding vehicle can be accurately detected by the procedure described in the related art. The inter-vehicle distance data is output from the CPU 3 (FIG. 2) and used for vehicle traveling control and the like.

(Embodiment 2) Since the main lines forming the design on the rear surface of the preceding vehicle are not always horizontal or vertical, in this embodiment, as shown in FIG. It is connected to a step motor 4 provided inside and is rotatable to a predetermined angle position (arrow in the figure).
The apparatus configuration in this case is shown in FIG. 6, and is the same as FIG. 2 except that the step motor 4 is provided. Step motor 4 is C
It rotates in the range of 0 to 360 degrees by the command from PU3.

The CPU 3 executes the line CCD according to the procedure shown in FIG.
The module 2 is rotated and the distance is calculated. That is, in step 101, the detected light intensity data from the line CCD module 2 is acquired, and in step 102, error data such as insufficient contrast and insufficient light amount of the entire line, which are also output from the line CCD module 2, are acquired. In step 103, it is confirmed whether an error has occurred. If an error has occurred, the step motor 4 rotates the line CCD module 2 by a predetermined angle, and step 101 is repeated.
Repeat the following. If no error occurs in step 103, the distance to the preceding vehicle is calculated from the deviation amount of the detected luminous intensity distribution obtained from the line CCD module 2 in step 104, and this is output in step 105.

According to this embodiment, even when the main lines forming the design on the rear surface of the preceding vehicle are not horizontal or vertical, the line CCD module 2 is appropriately rotationally displaced so that the line connecting the left and right lenses is the main line. It is possible to always have an angle with respect to a straight line, and it is possible to accurately detect the inter-vehicle distance corresponding to various designs on the rear surface of the preceding vehicle.

[0019]

As described above, according to the inter-vehicle distance detecting device of the present invention, the inter-vehicle distance to the preceding vehicle can be always accurately detected by the one-dimensionally arranged light receiving elements.

[Brief description of drawings]

FIG. 1 is an enlarged perspective view of an upper side of a vehicle windshield provided with an inter-vehicle distance detecting device according to a first embodiment of the present invention.

FIG. 2 is an overall block configuration diagram of an inter-vehicle distance detection device.

FIG. 3 is a rear view of the preceding vehicle showing a light receiving range of the line CCD module.

FIG. 4 is a diagram showing a light receiving range of a line CCD module and a detected light intensity distribution of a light receiving element.

FIG. 5 is a perspective view of an inter-vehicle distance detecting device according to a second embodiment of the present invention.

FIG. 6 is an overall block configuration diagram of an inter-vehicle distance detection device.

FIG. 7 is a processing flowchart of a CPU.

FIG. 8 is an optical path diagram of a line CCD module.

FIG. 9 is a diagram showing a detected luminous intensity distribution due to the image formation of one lens.

FIG. 10 is an optical path diagram of a line CCD module.

FIG. 11 is a diagram showing a detected light intensity distribution due to the image formation of the other lens.

FIG. 12 is a diagram showing a detected light intensity distribution due to image formation of left and right lenses.

FIG. 13 is an optical path diagram for explaining the distance detection principle of the line CCD module.

FIG. 14 is a rear view of the preceding vehicle showing the light receiving range of the line CCD module of the conventional inter-vehicle distance detecting device.

FIG. 15 is a diagram showing a light receiving range of the line CCD module and a detected light intensity distribution of the light receiving element.

FIG. 16 is a diagram showing a detected luminous intensity distribution due to image formation of left and right lenses.

[Explanation of symbols]

 1A, 1B lens 2 line CCD module (light receiving element) 3 CPU (calculation means, rotation control means) 4 step motor (rotation drive means) 5 inter-vehicle distance detection device B preceding vehicle

Claims (3)

[Claims] 1. A pair of lenses provided at regular intervals, a plurality of light receiving elements provided on a straight line parallel to the line connecting these lenses, and an image of the rear surface of the preceding vehicle being formed through the respective lenses, and In an inter-vehicle distance detecting device including a calculation means for calculating a distance to a preceding vehicle based on a deviation of a detected light intensity distribution in a light receiving element, the pair is formed so as to form an angle with a main line forming a design of a rear surface of the preceding vehicle. An inter-vehicle distance detecting device, in which the lens and the light receiving element are arranged. 2. The rotation driving means for rotating the pair of lenses and the light-receiving element integrally to change the arrangement direction of the light-receiving element with respect to a main line constituting the design of the rear surface of the preceding vehicle. Inter-vehicle distance detection device. 3. The inter-vehicle distance detecting device according to claim 2, further comprising rotation control means for activating the rotation driving means to an angular position where the light intensity difference of the detected light intensity distribution in the light receiving element becomes a predetermined value or more.