JPH01254811A - Distance detection sensor utilizing trigonometric survey - Google Patents

Abstract

PURPOSE:To accurately measure the distance to an obstacle by using photodetecting elements and setting obstacle detection distance ranges widely in an overlapping state. CONSTITUTION:The measurement light emitted by a projecting element 1 is reflected irregularly by the surface of the obstacle 3 toward the element 1 and photodetected by the photodetecting elements 51a and 51b which are provided at specific intervals to the element 1. Here, the elements 51a and 51b are selected so that their ranges of the distances to be obstacle overlap with each other. Consequently, the distance measurement range can be divided into three by the elements 51a and 51b to improve the distance resolution. Then the elements 1, 51a, and 51b and a distance display device 11 are all controlled by a microcomputer 12, where the relation between the detection outputs of the elements 51a and 51b and the distance to the obstacle 3 is stored within the three distance measurement ranges. For the purpose, a distance stored in the microcomputer 12 is displayed on the device 11 according to the combination of the detection outputs of the elements 51a and 51b. Thus, the distance to the obstacle is accurately measured.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention relates to a distance detection sensor using triangulation, which is particularly suitable for mounting on a vehicle, and has improved distance separation ability to obstacles around the vehicle. , relates to a distance detection sensor.

[Incoming technology]

Since then, devices have been devised in which a distance detection sensor is mounted on a vehicle to measure the distance to obstacles around the vehicle to help prevent vehicle accidents.

In such a device, a distance detection sensor
An important premise is that the distance from the vehicle to the obstacle can be accurately detected.

Incidentally, distance detection sensors using triangulation are known, and the conventional sensors of this type have a configuration as shown in FIG. 4.

Referring to FIG. 4, the measurement light 2 irradiated forward from the baking element 1 is reflected by an obstacle 3 or 3' existing in front of it, and the reflection is also reflected in a predetermined direction as 41 or 42. Ru.

A light receiving element 51 is provided at a distance D1 from the light projecting element 1, and a light receiving element 52 is provided at a distance D2 from the light projecting element 1.

Each of the light receiving elements 51 and 52 is capable of receiving reflected light 41 and 42 that are incident only from a predetermined angle, respectively.

Therefore, the distance to the obstacle can be detected depending on whether the light receiving element 51 emits the reflected light or the light receiving element 52 receives the reflected light. That is, the reflected light 41 reflected by the obstacle 3 that is a distance L1 away from the light projecting element 1 is received by the light receiving element 51,
The reflected light 42 reflected by the obstacle 3' separated by a distance L2 is received by the light receiving element 52.

[Problem that the invention seeks to solve]

However, normally, as shown in FIG.
52 each have a certain angle of view (also called field of view) 61
, 62, and light incident from this angle of view can be received.

Therefore, the light reflected by an obstacle existing within the angle of view 61 is received by the light receiving element 51.

In other words, even if there is an obstacle at distance L11 or L12, the reflected light will be received by the light receiving element 51. This means that the obstacles are determined to be at the same distance.

Therefore, the light-receiving elements 51 and 52 continue to derive light-receiving output when an obstacle exists within a certain distance range, and a light-receiving element with an angle of view cannot accurately detect the distance to the obstacle. The problem was that it was not possible.

Therefore, an object of the present invention is to provide a distance detection sensor that can measure the distance to an obstacle extremely accurately by increasing the distance resolution to the obstacle even with a light receiving element having a wide angle of view. shall be.

[Means for solving problems]

In this invention, a plurality of light receiving elements are used and installed so that a portion of the obstacle detection distance range of each light receiving element overlaps with each other.

This allows certain light receiving elements to detect a common obstacle detection distance range. Therefore, the distance to the obstacle is calculated based on which set of light receiving elements simultaneously detect the reflected light from the obstacle, so if each light receiving element has a wide range of obstacle detection distance, However, by overlapping these obstacle detection distance ranges as widely as possible, the distance measurement resolution to the obstacle is improved.

[Effect]

Which light-receiving element or set of light-receiving elements receives the reflected light from the obstacle, depending on the relationship between one light-receiving element or a set of two or more light-receiving elements and the corresponding obstacle detection distance range set in advance. The distance to the obstacle can be calculated depending on the distance.

〔Example〕

FIG. 1 is an illustrative diagram for explaining the principle of a distance detection sensor according to an embodiment of the present invention using two light receiving elements. FIG. 2 is a block diagram of a configuration for displaying the distance to an obstacle using the distance detection sensor shown in FIG.

Embodiments of the present invention will be described in detail below with reference to FIGS. 1 and 2.

In FIG. 1, when there is an obstacle 3 in front of the measuring light 2 emitted forward from the light projecting element 1, it is diffusely reflected on the surface of the obstacle 3 and is directed toward the light projecting element 1 as reflected light. return.

Light receiving elements 51a and 51b are provided at a predetermined distance from the light projecting element 1.

The light receiving element 51a is provided so as to be able to detect the reflected light reflected by the obstacle 3 when the obstacle 3 exists within the range of distance La1 to La2.
1b is that when the obstacle 3 is within the distance Lb1 to Lb2, the reflected light reflected by the obstacle 3 can be detected.

Then, the distance range La1-La2 and the distance range Lb1-L
b2 means that the distance ranges are selected so that some of them overlap.

As a result, with the two light receiving elements 51a and 51b,
The distance measurement range is La1~Lb1, Lb1~Lb2, La
It can be divided into three parts, 2 to Lb2, and the distance resolution can be improved.

Next, the measurement light emitted from the light emitting element is reflected by an obstacle, and the distance to the obstacle is determined based on which light receiving element detects the reflected light, and the distance is displayed. To explain from the block diagram in the figure, the light emitting element 1
, the light receiving elements 51a, 51b, and the distance display device 11 are all controlled by a microcomputer 12, and the microcomputer 12 detects the detection output from each of the light receiving elements 51a, 51b due to reflected light and the obstacle 3. The relationship between the three distance measurement ranges La1 to Lb1, Lb1 to La2, and La2 to Lb2 shown in FIG. 1 is stored as follows.

In other words, when only the light receiving element 51a has a detection output, the obstacle 3 is located within the distance range of La1 to Lb1, and both the light receiving elements 51a and 51b derive the detection output. If so, the obstacle 3 is Lb1~La2
Similarly, if only the light receiving element 51b has a detection output, the obstacle 3 is located in the distance range of La2 to Lb2.
This means that it is located within a distance of

Therefore, the distance stored in the microcomputer 12 is displayed on the distance display device 11 by the combination of the detection outputs of the light receiving elements 51a and 51b. At this time, the distance value shown on the distance display device 11 is the shorter distance, for example, in the distance range La1 to Lb1 in which only the light receiving element 51a detects reflected light, the distance from the light emitting element 1 to Lb1. If it is displayed, there will be no practical problem.

In the explanation of FIGS. 1 and 2, two light receiving elements are used,
The principle of this invention has been explained, but in order to use the present invention in a car to determine the distance to an obstacle, many light receiving elements are used. four light receiving elements 51, 52, 53---58
If the distance ranges detected by each of these light-receiving elements are set to overlap as shown in Fig. 3, if only the light-receiving element 51 has a detection output, there will be no problem. Object 3 is within the distance La1 to Lb1, and the distance display device 11 shows the distance from the car 10 to Lb1, and the two light receiving elements 51 and 52 are outputting detection outputs. For example, if the three light receiving elements 51, 52, and 53 have the same detection output as the distance to LC1, the distance to La2 will be shown on the distance display device 11, respectively. It becomes possible to measure distances over a wide range.

Furthermore, the tips La1 and Lb of the measurement range of each light receiving element are
1, Lc1, Ld1 --- If you install each receiving element so that they are as close as possible, no matter how wide the measurement range of each light receiving element is, for example, if it is light receiving element 51, the distance Even though the measurement range is wide from La1 to La2, according to the present invention, the distance measurement range of the light receiving element 51 can be made extremely narrow from La1 to Lb1, so it is possible to increase the distance resolution. Become.

Note that the eight light receiving elements 51, 52, 5 shown in the example of FIG.
3----58 distance ranges are arranged so that the warping distances overlap in order, but even if the warping distances are set to overlap randomly, the combination of light receiving elements corresponding to the overlapping distances will not be the same. There is nothing wrong with just changing.

〔Effect of the invention〕

As described above, according to the present invention, each light receiving element is installed so that a part of the distance measurement range of each light receiving element overlaps, and the detection output of the light receiving element common to the overlapping distance range is used. With the same number of light receiving elements, the number of distance measurement ranges becomes 2n-1 (n is the number of light receiving elements), which can be approximately doubled. Furthermore, no matter how wide the angle of view photodetectors are used, distance resolution can be increased by setting the overlapping area of the distance measurement range of each photodetector to be wide, and the distance to the obstacle can be determined extremely accurately. It becomes possible to measure

Furthermore, if the present invention is utilized for measuring the distance to a subject in a camera, it becomes possible to create an inexpensive autofocus camera.

[Brief explanation of the drawing]

FIG. 1 is an illustrative diagram for explaining the principle of the present invention. FIG. 2 is a block diagram of a configuration for displaying the distance to an obstacle according to an embodiment of the present invention. FIG. 3 is a diagram showing another embodiment of the invention. FIGS. 4 and 5 are diagrams for explaining a distance detection sensor using a conventional triangulation method and its problems. In the figure, 1 is a light projecting element, 2 is a measurement light, 3 is an obstacle,
4 is reflected light, 51a, 51b, 51 to 58 are light receiving elements,
10 is a car, 11 is a distance display device, and 12 is a microcomputer.

Claims (1)

[Claims] A sensor that detects the distance to an object using triangulation, and a light projector that emits measurement light in a predetermined direction;
A light receiving means is provided at a predetermined distance from the light projecting means and receives reflected light incident only from a predetermined angle when the light projected from the light projecting means is reflected by a target object. , the light receiving means is composed of a plurality of pieces, and the mounting positions thereof are set so that a part of the object detection distance range of each light receiving element overlaps with each other, so that the non-overlapping distance range and the overlapping distance Depending on the relationship between the range and the corresponding one light-receiving element or set of two or more light-receiving elements, which light-receiving element or set of light-receiving elements is receiving the reflected light from the target object, A distance detection sensor using a triangulation method, characterized in that the distance is determined.