JPS6345504A - Range finder - Google Patents

Abstract

PURPOSE:To simplify the constitution of a range finder and to speedily measure distance by setting properly the relative positions of a light projection part which projects a projection pattern on a target body and a photodetection part where the projection is image-formed. CONSTITUTION:A parallel light beam which gives the target body X at a proper position the same projection pattern Y even when the distance R to the target body X varies is projected from the projection part 1 through a convex lens 11. The photodetection part 2 photodetects the light in this projection direction through a half-mirror 20 and a convex lens 21 to form the projection pattern image on an image formation surface. The size of this formed image Y' is decided from the output of a formed image detection part 3 and the diameter of the formed image Y' is further detected by a signal processing part, thereby calculating the distance R by considering the diameter of the projection pattern Y as L.

Description

[Detailed description of the invention] [Technical field] The present invention relates to an optical distance measuring 5 IC arrangement.

[Background Art] Conventionally, this type of optical distance measuring device applies a known pattern to a target object in advance, and imports the pattern into an image processing means using an image input means such as a television camera to perform image processing. By this, the pattern situation is determined, and the distance to the target object is determined based on the size of the pattern image.

However, in such a conventional example, an image input means such as a television camera is required, and the image processing for determining the position of the pattern on the target object is complicated, so the device is large. There are problems in that the cost increases due to formalization and processing time is required.

[Object of the Invention] The present invention has been made in view of the above-mentioned points, and its purpose is to simplify the configuration and reduce costs, and to shorten the signal processing time so that it can be quickly processed. An object of the present invention is to provide a compact distance measuring device capable of measuring distance.

[Disclosure of the Invention] (Example) The first example shows an example of the present invention, in which the same light projection pattern Y is applied to the appropriate position of the target object X even if the distance R to the target object X changes. a light projecting section 1 that receives light from the projecting direction, and a light receiving section 2 that forms an image of a projected light pattern Y on a target object X.
, an image formation detection section 3 consisting of a light-receiving probe array that detects the image formation situation, a signal processing section 4 that determines the size of the image Y' based on the output of the image formation detection section 3, and an output of the signal processing section 4. and a distance determining section 5 that determines the distance R to the target object X based on. Here, in the embodiment, the light emitting unit 1 is formed of a light emitting element 10 made of a near-infrared light emitting diode and a convex lens 11 for light emitting, and the light emitting element 10 is arranged at the focal point and α position of the convex lens 11. As a result, a parallel beam is projected onto the target object X, and the projection pattern Y matches the shape of the convex lens 11 (circular in this embodiment).

Further, the light emitting element 10 is driven by a signal with an appropriate modulation frequency to emit light at a constant cycle in order to prevent malfunctions due to disturbances. On the other hand, the light receiving section 2 includes a half mirror 20 arranged at an angle of 45° to the optical axis of the light projecting section 1 and a receiving convex lens 21 arranged perpendicularly to the projecting convex lens 10. The optical axis thereof is aligned with the optical axis of the light projecting section 1 to receive light from the projecting direction. The image detection unit 3 disposed on the image forming surface of the light receiving unit 3 is formed by a light receiving element array in which a large number of light receiving elements 30 are arranged in a row, and an analog switch 31 for sequentially outputting the outputs of the light receiving elements 30. has been done. A signal processing unit 4 to which the output of this image detection unit 3 is input.
is an amplifier 40 that amplifies the analog switch 31 output;
It is formed of a bandpass filter 41 that extracts the modulation frequency and a signal processing circuit 42 that detects and compares the outputs of each light receiving element 30 in accordance with the operation of the analog switch 31.

The operation of the embodiment will be described below. Figure @3 is a diagram showing the distance measurement principle of the present invention. Now, the distance from the convex lens 21 to the light projection pattern Y is R1, the distance from the convex lens 21 to the image Y on the imaging plane is 2, and the distance from the projection pattern Y is 2, and the distance from the convex lens 21 to the image formation Y on the image plane is 2. If the length of the pattern Y is L1 and the height of the imaging Y° is Lo, then the following equation holds true.

L゛=(α/R)XL・・・・・・・・・・・・・・・
(1) From formula (1), R=(L/L')Xα・・・・・・・・・・・・・・・
(2), the length of the light projection pattern Y is L1, the convex lens 21
If the distance a from to the image plane is known, then the distance from the convex lens 21 to the projection pattern Y, that is, the distance R to the target object X, can be determined by knowing the length of the image Y°.

Next, a specific distance measuring operation will be explained. Now, even if the distance R to the target object X changes, the light projection pattern Y remains the same.
A parallel beam that gives the target object ls2
Then, the light from this projection direction is received through the half mirror 20 and the convex lens 21 to form a projection pattern image on the imaging plane. Next, the size of the image formation Y° is determined by the image formation detection unit 3
Judgment is made based on the output, and in this embodiment, the outputs of the light-receiving elements 30 arranged in a row as shown in FIG. The detection output Vo obtained by extracting the modulated frequency component with the bandpass filter 41 is shown in Figure (b).
7 Here, the period during which this detection output Vo is equal to or higher than the reference voltage VLb (that is, the period corresponding to the number of light receiving elements 30 receiving light of a predetermined level or higher) is measured. By doing this, the size of the image Y゛ is Lo
is determined (Lo is calculated based on the period when the voltage is equal to or higher than the reference voltage Vtl+). Note that the reference voltage vth
is set based on the average value of the output of each light receiving element 30, and the distance B
R1 This is to prevent the influence of the reflectance of the target object X, etc. In addition, when determining accurate Lo,
The output of each light-receiving element 30 is interpolated using an appropriate interpolation method to determine an approximate curve, and this approximate curve is compared with the reference voltage to determine Lo. The size Lo of the image Y' is input to the distance gtq section flfi5, and the distance R to the target object X is determined based on equation (2). In this case, since the shape of the light projection pattern Y is circular, the image forming detection section 3 consisting of a light receiving element array and the signal path J! ! ! The diameter of the image Y' is detected as Lo by the unit 4, and sR is calculated by setting the diameter of the light projection pattern Y (that is, the diameter of the convex lens) as L.

[Effects of the Invention 1] As described above, the present invention includes a light projecting section that applies the same light projection pattern to a suitable location on the target object even if the distance to the target object changes, and a light projecting section that receives light from the direction of the light projection. A light-receiving section that forms an image of the light projection pattern on the target object, an image-forming detecting section consisting of seven light-receiving elements that detects the image-forming situation, and a signal processing section that determines the size of the image based on the output of the image-forming detecting section. and distance a 4'JI for determining the distance to the target object based on the signal processing unit output.
The light-receiving element array consists of a part a and a light-receiving element array. Since it is possible to detect the size of the image of the projected light pattern using the image forming detection section, there is no need to use an image input means such as a television camera, which simplifies the configuration and reduces costs. In addition, the size of the image can be easily determined based on the output of the image detection section consisting of the photodetector array, which reduces signal processing time and enables rapid distance measurement. This has the effect of allowing you to do this.

[Brief explanation of the drawing]

FIG. 1 is a schematic diagram of the main part of an embodiment of the present invention, FIG. 2 is a circuit diagram of the main part of the same, and Pt53 and FIG. 4 are explanatory diagrams of the operation of the same. X is I''I target object, Y is the light projection pattern, Y is the image formation, 1
is the light emitting part, 2 is the light receiving part, 3 is the imaging detection*I\lS, and 4 is the signal foil F[! Section 5 is a distance scale Wr section.

Claims (1)

[Claims] (1) A light projection unit that applies the same light projection pattern to the appropriate location on the target object even if the distance to the target object changes, and a light projection unit that receives light from the direction of the light projection and forms an image of the light projection pattern on the target object. an image detection section consisting of a light receiving element array that detects the image formation situation, a signal processing section that determines the size of the image based on the output of the image detection section, and a target object based on the output of the signal processing section. A distance measuring device comprising a distance determining unit that determines the distance to.