JPS59202012A - Optical range finder - Google Patents

Abstract

PURPOSE:To minimize obscuration of a spot light image at the photoelectric sensor and increase accuracy by a device wherein the photoelectric sensor is arranged such that an angle made by the photoelectric sensor of light receiving means crossing the light receiving optical axis substantially equals to an angle made by the light projecting optical axis of light projecting means crossing the light receiving optical axis. CONSTITUTION:Light projecting means to project a spot light and light receiving means to detect a spot light image projected on the measured objective from the light projecting means are provided. A photoelectric sensor 5' is arranged such that an angle theta made by a light projecting optical axis 7 crossing a light receiving optical axis 8 becomes substantially equal to an angle theta made by the photoelectric sensor 5' crossing the light receiving axis 8. With this arrangement, the spot light image is focused substantially on the photoelectric sensor 5' as an image A'', B'' with no obscuration. Thus, when using a PSD or CCD element as the photoelectric sensor, sensitivity and accuracy of positional detection can be improved drastically.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an optical distance meter that is used as a non-contact distance measuring device for assembly and inspection, or as a non-contact sensor for production machines such as robots. be.

Configuration of conventional examples and their problems In the past, various devices have been proposed and tried as non-contact optical rangefinders that use light, but the representative device that is currently in practical use is the first one. The configuration shown in the figure is adopted. That is, a semiconductor laser or an LED is made to emit light,
A light projecting means 1 condenses the light into a spot light (circular parallel light flux) 2 and projects the light onto the object to be measured, and a spot light image (A) from above the object to be measured.

A light-receiving means constituted by a condensing lens 4 and a one-dimensional or two-dimensional photoelectric sensor 6 that receives the reflected light 3 of 0, B), and a light-emitting means based on the principle of triangulation based on the data from this light-receiving means. 1 or a distance calculating circuit 6 that calculates the distance from the light receiving lens 4 to the object to be measured. The principle of distance measurement is to configure an optical system so that a spot light image (0) on the object to be measured located at a measurement reference distance l○ from the light projecting means 1 is imaged by the photoelectric sensor 5''200'. Then, the object to be measured is the distance to be measured! I:l! When displaced like A and lB, the spot light images for them become A and B,
So lA and lB are found. Here, the angle between the light emitting axis and the receiving optical axis is θ, and the photoelectric sensor 5 detects the received light i1i+
It is arranged perpendicular to b.

However, in this case, as shown in FIG. 2, the images A/, B' on the photoelectric sensor 6 for A and B are blurred, resulting in a decrease in position detection accuracy and detection sensitivity of the photoelectric sensor 5, and a complicated There was a problem in that a correction circuit and an IJ expansion circuit were required.

The purpose of the invention is to provide a highly accurate and inexpensive optical distance.

Structure of the Invention As a structure for this purpose, the present invention includes a light projecting means for projecting a spot light, and a light receiving means for detecting a spot light image projected onto an object to be measured by the light projecting means. The photoelectric sensor 5' is arranged so that the angle θ between the optical axis 7 and the light receiving optical axis 8 is approximately equal to the angle θ between the photoelectric sensor 5' and the light receiving optical axis 8. With this configuration, the spot light image is formed as images A' and B' approximately on the photoelectric sensor 6', and there is no image blurring.
When using an SD element or a CCD element, the sensitivity and accuracy of position detection can be dramatically improved.

Note that the imaging position d2 by the condensing lens 4 is strictly a curve, and a photoelectric sensor that follows the curve may be manufactured.
Even if the curve is approximated by a straight line as in this embodiment (the angle between the light receiving optical axis 8 and this straight line is θ) and the photoelectric sensor 5' is arranged, there is no practical problem and it is inexpensive. It can be manufactured in

DESCRIPTION OF THE EMBODIMENTS An embodiment of the present invention will be described below with reference to FIGS. 2 to 3 of the drawings.

As a light projecting means, 25 mW, λ=830 nm
A semiconductor laser of
．． 6rmnφ) and project the light onto the welded workpiece with black coating. A convex lens of f = 30 mm and an interference filter were used as the light receiving means, and a one-dimensional PSD element was used as the photoelectric sensor 6'. The angle θ between the light emitting optical axis 7 and the receiving optical axis 8 is 2.
6"-' and (measurement reference distance l) was set to 120 mm.Next, the output signal from the PSD element is processed by a current-voltage conversion circuit 9, a low-pass filter circuit 10, an addition circuit 11, and a subtraction circuit, as shown in FIG. Circuit 12, analog divider circuit 13.8
Via the A/D conversion circuit 14, it is input to the microconbeater 16, and from the light projecting means the black skinned welded workpiece 1
The distance is displayed on the display 16. As a result, the distance measurement range (i.e. between A and B in Figure 2) is 50 m.
m could be measured with an accuracy of ±0.2 rnm. On the other hand, in a conventional device in which the PSD element is placed perpendicular to the light receiving optical axis, the accuracy is within ±0.3 to ±0.4 rah.

Effects of the Invention As described above, the present invention has excellent effects in that it is possible to measure distances with even higher precision than in the past, and it also has a simple configuration that reduces costs. be.

[Brief explanation of the drawing]

Fig. 1 is an explanatory diagram of a conventional optical rangefinder, Fig. 2 is an explanatory diagram showing the drawbacks of the conventional example and the configuration of the optical rangefinder of the present invention, and Fig. 3 is a signal of a PSD element in an embodiment of the present invention. It is a professional diagram showing a processing circuit. 1... Light projecting means, 2... Spot light, 3...
・Reflected light, 4... Condensing lens, 5'...-
...Photoelectric sensor, 6...Distance calculation circuit, 7...
...Emitting optical axis, 8...Receiving optical axis. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure “T 1 Figure 2 8

Claims (1)

[Claims] A light projecting means for projecting a spot light and the photoelectric sensor are arranged so that the spot light image projected onto the object to be measured by the light projecting means is substantially equal.