JPH03131790A - Obstacle detecting device for vehicle - Google Patents

Abstract

PURPOSE:To reduce the influence of reflection on the internal surface of a protection cover by providing a light receiving element for a light emitting element on a side where the angle between one main surface of an outer cover and the optical axis of the light emitting element is acute. CONSTITUTION:Laser light emitted by the light emitting element 11 is diverged by the light emitting element on the light emission side in a specific direction of the vehicle, the outer cover 2 again and then through an optical system on the light reception side, and photodetected by the photodetecting element 22. Further, part of the laser light emitted by the light emitting element 11 after passing through an optical means 12 on the light emission side is reflected by the outer cover 2 and the reflected light from the outer cover is transmitted through the optical system 21 on the photodetection side, and received by the light receiving means 2. In this case, the light receiving element is provided for the light emission element so that the angle between one main surface of the outer cover and the optical axis of the light emitting element becomes acute, so the quantity of detection of the reflected light reflected by the outer cover is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a vehicle obstacle detection device that uses laser light to detect obstacles in a predetermined direction of a traveling vehicle.

[Conventional technology]

Conventionally, this type of device emits laser light from a laser diode to the front of the vehicle through a convex lens for light emission.
Some vehicles detect obstacles in front of a vehicle by receiving reflected light from an obstacle in front of the vehicle by a light receiving element via a convex lens for receiving light. In these devices, a transparent protective cover is usually used to protect the light-emitting element and the light-receiving element, but the light emitted from the light-emitting element is reflected on the inner surface of this protective cover and enters the light-receiving element. The problem was that accurate information could not be obtained with the light receiving element.

[Problem to be solved by the invention]

The present invention has been made in view of the above problems, and an object of the present invention is to provide a vehicle obstacle detection device that is less affected by reflection on the inner surface of a protective cover.

[Means to solve the problem]

In order to achieve the above object, in the present invention.

The laser light emitted by the light emitting element is diverged in a predetermined direction of the vehicle by an optical means for emitting light, and the reflected light from an obstacle in the predetermined direction is focused by an optical means for receiving light, and then the light is emitted to a light receiving element. In the vehicle obstacle detection device that detects an obstacle in a predetermined direction of the vehicle by receiving light, there is a space between the optical means on the light emitting side and the light receiving side and the obstacle, and , comprising an outer cover that protects the light emitting element, the light receiving element, and the optical means, and a side where the angle between one main surface of the outer cover and the optical axis of the light emitting element is an acute angle with respect to the light emitting element. To,
The light receiving element is provided.

[Function] In the vehicle obstacle detection device configured as described above, the laser light emitted by the light emitting element is diverged in a predetermined direction of the vehicle by the optical means on the light emitting side, passes through the outer cover, and detects the obstacle. It is reflected by.

The reflected light reflected by the obstacle passes through the outer cover again, passes through the optical means on the light receiving side, and is received by the light receiving element.

Further, after the laser light emitted by the light emitting element passes through the optical means on the light emitting side, it is partially reflected by the outer cover, and the reflected light from the outer cover passes through the optical means on the light receiving side, and the light is transmitted through the light receiving element. The light is received at Here, the light receiving element is provided on the side where the angle between one main surface of the outer cover and the optical axis of the light emitting element is an acute angle with respect to the light emitting element. The amount of light detected by the light receiving element is reduced.

〔Example〕

An embodiment of the present invention will be described below with reference to FIGS. 1 to 6. FIG. 1 is a configuration diagram showing the main parts of this embodiment. In this FIG. 1, 100 is an element section that emits pulsed laser light and receives reflected light reflected from an obstacle, and 200 is an element section that responds to a light emission signal and a light reception signal from the element section 100. It is a calculating means for calculating the distance to an obstacle, and 300 is a display means for displaying the distance in response to the distance signal from the calculating section 200. Reference numeral 2 denotes a light-transmitting outer cover provided for reasons of protection and design of the vehicle light, and is made of, for example, glass or plastic. Element part lO
In O, the light emitting means 10 includes a laser diode 11 as a light emitting element that emits laser light, a light emitting lens 12 (for example, a convex lens) as a light emitting side optical means that narrows the emitted laser light to a predetermined divergence angle, and a laser diode. 1
1 in response to a trigger signal from the arithmetic unit 200, and a light emitting circuit 13 that outputs a light emission signal to the arithmetic unit 200, and a case 14 for the light emitting means. The light receiving means 20 includes a light receiving lens 21 (for example, a Fresnel lens) as a light receiving optical means for condensing reflected light from an obstacle, a light receiving element 22 (for example, a PTN photodiode) for receiving reflected light, and a light receiving element 22 (for example, a PTN photodiode) for receiving reflected light. It is composed of a light receiving circuit 23 that amplifies a signal and outputs a received light signal to the calculation means 200, and a light receiving unit case 24. The light emitting means 10 and the light receiving means 20 are connected to the element part 10 by screws.
00 body case 30. The light receiving means 20 having the light receiving element 22 is provided on the side where the angle α between one principal surface of the outer cover 2 and the optical axis of the element portion 100 is an acute angle. As shown in Fig. 1, the fact that the angle α is an acute angle means that the angle θ formed by the outer cover 2 and the upper direction perpendicular to the optical axis is inclined to the negative side in Fig. 1. It is.

FIG. 2(a) is a sectional view of the main part of the engine room of the vehicle, and FIG. 2(b) is a sectional view of the main part of the side view thereof. In FIGS. 2(a) and 2(b), 3 is a vehicle headlight, 4 is a front grill, 5 is a bumper, and 6 is light emitted from the element part 100 of the vehicle obstacle detection device according to the present invention. It's a laser beam. Reference numeral 7 indicates reflected light that is generated when the laser beam 6 hits an obstacle and is reflected. Note that the element section 10
0 is a stay (not shown) installed at a position adjacent to the headlight 3.

Further, FIG. 2(a) shows a case where two element parts 100 are used, and one element part is 100. The other element part is 10
It is set to 0'.

FIG. 3 is a schematic diagram for explaining reflection of laser light by obstacles. In FIG. 3, most of the laser light emitted from the light emitting means 10 passes through the outer cover 2 and reaches the obstacle, but some of the laser light is reflected by the outer cover 2 and is reflected by the light receiving means. Proceed to step 20. The influence of this reflected light from the outer cover 2 differs depending on the polarization angle θ of the outer cover 2 shown in the figure. Note that the deflection angle θ of the outer cover 2 is between the axis perpendicular to the optical axis of the element section 100, and
This is the angle formed by the outer cover 2, and in the figure, the left side is negative and the right side is positive. The fact that the deflection angle θ of the outer cover 2 is negative means that the angle α is an acute angle. Here, in order to see the influence of the declination angle θ of the outer cover 2, an acrylic plate (
Distance to the acrylic plate and light reception signal output when using a blue smoke color (2mm thick) and using the declination angle θ as a parameter. 1, and this relationship is shown in FIG.

Here, the distance is the distance between the front surface of the element section 100 and the acrylic plate, and the light reception signal output (■). ut indicates the output value of the light receiving signal from the light receiving circuit 23. What can be seen from the results in Figure 4 is that in the case of the arrangement shown in Figure 3,
It can be seen that when the polarization angle θ of the outer cover 2 is positive, the influence of the reflected light becomes large, and conversely, when the polarization angle θ is negative, the influence becomes small.

FIG. 5 is a block diagram showing the electrical connections in FIG. 1. In the calculation means 200, 40 is a trigger circuit that generates a trigger signal for causing the laser diode 11 to emit light;
0 is a signal processing circuit that outputs a distance signal proportional to the distance to the obstacle in response to the light emission signal from the light emission circuit 13 and the light reception signal from the light reception circuit 23; 60 is a signal processing circuit that outputs a distance signal proportional to the distance to the obstacle in response to the distance signal; 70 is a power supply circuit that supplies predetermined voltages and currents to each circuit element.

FIG. 6 shows a time chart comparing the operation of this embodiment with the above configuration with that of the case where θ is positive. A trigger circuit 40 periodically generates a trigger signal as shown in FIG. 6(a). In response to the fall of the trigger signal, the light emitting circuit 13 drives the laser diode 11;
A laser beam as shown in FIG. 6 is emitted. This laser light passes through a light emitting lens 12 as an optical means on the light emitting side and is emitted toward the front of the vehicle. The reflected light reflected by the obstacle in front is passed through the light receiving lens 21, which is an optical means on the light receiving side.
The light is focused and reaches the light receiving element 22. The light receiving element 22 converts the received light into an electrical signal, which is then input to the light receiving circuit 23 and amplified. At this time, the output of the light receiving circuit 23, that is, the light receiving signal is, for example, in the configuration shown in FIG. 3, when the declination angle of the outer cover 2 is negative (when the angle α is an acute angle).
is as shown by the solid line in FIG. 6(C), and when this declination angle θ is positive, it becomes as shown by the chain line in FIG. 6(C). In this FIG. 6(C), P is the result of the reflected light reflected by the outer cover 2, and P2 is the result of the reflected light reflected by the obstacle in front. In addition, outer cover 2
The time T1 at which the light reception signal P generated by the reflected light reaches its peak value is a value determined by the distance between the element section 100 and the outer cover 2 (T+-2L/C, C=speed of light).

The signal processing circuit 50 detects the peaks of the light emission signal and the light reception signal that exceed a predetermined value, and outputs a distance signal as shown in FIG. 6(d). The distance signal shown by the chain line in FIG. 6(d) is affected by the light reception signal P1 generated by the light reflected by the outer cover 2, and is originally a distance signal corresponding to the distance to the obstacle to be detected. No signal is obtained.

The distance signal obtained by this example is shown by a solid line, and the distance signal corresponding to P- is obtained.

Note that the half width T of the received light signal P1. is a value determined by the pulse width of the light emission signal (generally about 80 ns) and the frequency characteristics of the light receiving circuit 230 (generally about 100 ns). Therefore, 1. The influence of the received light signal P is its output value (v, u
t), but the maximum distance in terms of distance is approximately 15m C1
=T,x).

〔Effect of the invention〕

As explained above, according to the present invention, since the light receiving element is provided on the side where the angle between one main surface of the outer cover and the optical axis of the light emitting element is acute with respect to the light emitting element, the light receiving element This has the excellent effect of reducing received light reflected by the outer cover.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing one embodiment of the present invention, FIG. 2(a) is a sectional view of the main part of the engine room of a vehicle, and FIG.
Figure 3 is a configuration diagram showing the reflection of the laser beam by an obstacle; Figure 4 is the distance to the acrylic plate and the received light signal when the polarization angle θ is used as a parameter. Output■
. A graph showing the relationship between □, Fig. 5 is a block diagram showing the electrical connections of the above embodiment, and Figs. This is a time chart. 2... Outer cover, 11... Light emitting element, 12.
... Optical means on the light emitting side, 21... Optical means on the light receiving side,
22... Light receiving element.

Claims (1)

[Scope of Claims] Laser light emitted by a light emitting element is diverged in a predetermined direction of the vehicle by optical means on the light emitting side, and reflected light from an obstacle in the predetermined direction is focused by optical means on the light receiving side. After that, in the vehicle obstacle detection device that detects an obstacle in a predetermined direction of the vehicle by receiving the light with a light receiving element, there is a light between the optical means on the light emitting side and the light receiving side and the obstacle. an outer cover that transmits light and protects the light emitting element, the light receiving element, and the optical means, the angle between one main surface of the outer cover and the optical axis of the light emitting element with respect to the light emitting element is An obstacle detection device for a vehicle, characterized in that the light receiving element is provided on a side that forms an acute angle.