JPS6281519A - Range finder - Google Patents

Abstract

PURPOSE:To secure stable measuring accuracy without being affected by the variation in an S/N ratio, by repeatedly measuring the average number of times set on the basis of the S/N ratio at the time of measurement and dividing the sum total value, obtained by adding measured results, by the average number of times. CONSTITUTION:The luminous flux emitted from a light source 1 is transmitted to a projection lens 2 to irradiate an objective matter 3 to a light spot 4 while a light receiving lens 5 picks up the image of he light spot 4 to form the same on the light receiving surface of a light receiving element 6. The electric signals iA, iB outputted from the light receiving element 6 by the formation of the image are added by an adder 7 and the average number of times are set on the basis of the S/N ratio determined by the added value by an average-number- of-time setting means 11 and measurement is repeated by the set average number of times and the processing is performed by an average processing circuit 15 so that the sum total value of the measured results is divided by the above- mentioned average number of times to obtain the average value of the measured results.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a distance measuring device that measures the distance to a target object in a non-contact manner.

[Conventional technology]

FIG. 4 shows a conventional non-contact distance measuring device. In FIG. 4, 1 is a light source, and 2 is a device that focuses the light beam emitted from the light source 1 and projects it onto the target object 3 to be measured. This is a light projecting lens.

The light source 1, the light projection lens 2, and the target object 3 are located on the axis A, and the light emitted from the light source 1 is irradiated onto the target object 3 by the light projection lens 2, forming a light spot 4 of a luminous flux.

5 is a light receiving lens that forms an image of the light spot 4; 6 is a light receiving element that generates an electric signal corresponding to the imaging position P of the image of the light spot 4 formed by the light receiving lens 5; , the light-receiving lens 5, and the light-receiving element 6 are located on the phase line B, and in this case, this axis line B makes an angle θ with the axis line person.

Then, two electrical signals iA output from the light receiving element 6,
jH is input to an adder 7 and a subtracter 8, respectively, and the adder 7 calculates the sum of both signals (i person +'u), and the subtracter 8 calculates the difference between both signals (jA-'Il+). It will be done. A divider 9 divides the output of the subtracter 8 by the output of the adder 7, and a converter 10 converts the position output P of the divider 9 into a distance output tVC.

Next, the operation will be explained. The light beam emitted from the light source 1 is converted into a light spot 4 of an appropriate size by a projection lens 2.
The target object 3 is irradiated with the light. The light spot 4 is imaged by the light receiving lens 5, and an image of the light spot 4 is formed on the light receiving surface of the light receiving element 6.

Such a light receiving element 6 includes, for example, a light position detector 1a that outputs an optical signal proportional to the imaging position of a spot image toward both ends, and a light receiving surface arranged at both ends of this light position detector. It is composed of a photodetector that generates an electric signal 'A+'H according to the optical signal incident above. Therefore, depending on the values of the electric signals IA and 1H, the imaging position P of the optical spot image is determined.
can be determined as +A4-LH.

By the way, the output of the light receiving element 6 produces an output signal proportional to the imaging position P of the light spot image and its intensity. Therefore, in the above equation (1), the term (1 person + jB), which is a signal that changes in proportion to the intensity change of the light spot image, is introduced into the denominator, and a signal that is proportional only to the imaging position of the light spot image is introduced into the denominator. I'm trying to get it.

The adder 7, the subtracter 8, and the divider 9 are circuits for implementing the operation shown in equation (1) above based on the output signals IA and IB of the light receiving element 6, and in this way, the divider 9, an output value P corresponding to the imaging position of the light spot image is obtained.

On the other hand, if the distance to the target object 3 is t, and the installation interval between the light projecting lens 2 and the light receiving lens 5 is L, then t can be obtained as follows. Here, θ is the light receiving lens 5
It is determined by the installation position and focal length of , the installation interval between the light receiving element 6 and the light receiving lens 5, and the output P related to the imaging position of the light spot image. Since all of these except the position output P can be determined as fixed values, in the end, the target object 3
The distance t is t=K −P ・
・−・−・・It is obtained as (3). In this case, K is a constant determined by each of the above fixed values, and is set by prior calculation or experiment. The converter 10 implements the above equation (3), inputs the position output P, and outputs the distance output t.

[Problem 1 to be solved by the invention Since the conventional non-contact distance measuring device is configured as described above, the 8/8
There is a problem in that when the N ratio changes, the measurement accuracy fluctuates in response to this change.

The present invention was made to solve these problems, and aims to provide a non-contact distance measuring device with excellent responsiveness and stable measurement accuracy.

[Means for solving problems]

The distance measuring device according to the present invention includes an average number setting means for setting the average number based on the S/N ratio, and a total value obtained by repeating measurement by the set average number of times and adding each measurement result at the average number. The average processing means for performing division is provided.

[For production]

In the distance measuring device of the present invention, the measurement results are averaged by repeating the measurement an average number of times set by the S//N at the time of measurement, and dividing the total value obtained by adding each measurement result by the average number of times, To ensure stable measurement ff11 degrees without being affected by fluctuations in S/N ratio.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a diagram of a non-contact distance measuring device showing an embodiment of the present invention. 1 to 10 are the same as those of the above-mentioned conventional device. 11 is an average number setting means, and an adder 7
The output of is proportional to the S/N, and the dispersion of the distance output is proportional to the reciprocal of the product of the square root of the average number and the S value.
Set the average number automatically. Reference numeral 12 denotes an averaging processing means for calculating an average value by dividing the total sum of the measurement results of the measurements repeated the number of times set by the number of averages setting means 11 by the number of times of averaging.

Next, the operation will be explained. A luminous flux emitted from a light source 1 is transmitted to a projection lens 2, and is irradiated onto a target object 3 as a light spot 4. On the other hand, the light-receiving lens 5 images the light spot 4 and forms the image on the light-receiving surface of the light-receiving element 6 .

The electrical signal I output from the light receiving element 6 by this image formation
A and 1B are added by adder 7, and S/ is determined by this added value.
The average number of times is set by the average number of times setting means 11 based on the N ratio, the measurement is repeated for the set average number of times, and the total value of each measurement result is divided by the above average number of times to obtain the average value of the measurement results. Second, the average processing circuit 12 processes the data.

FIG. 2 shows a second embodiment of the present invention, in which an address is determined by the electric signal 'A+'B outputted from the light receiving element 6, and the distance output t corresponding to this address is sent to the distance calculator 1.
3 from memory (not shown). On the other hand, the electric signals IA and IB output from the light receiving element 6 are sent to an adder 14.
The average number is set by the average number setting means 11 based on the output of this adder 14, that is, the S ratio f which is proportional to this output, and the measurement is repeated for the set average number of times. The average processing circuit 12 divides the total sum of the distance outputs read from the memory by the number of times of averaging to obtain an average value.

〔Effect of the invention〕

As described above, according to the present invention, the number of averages is automatically determined in accordance with the S/N ratio obtained from the measurement results, and the total value obtained by sequentially adding each measurement result is divided by the number of averages. Since the measurement result is obtained as an average value, there is an effect that stable measurement accuracy can always be obtained without being affected by fluctuations in the S ratio during measurement.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram of a distance measuring device showing one embodiment of the present invention, FIG. 2 is a configuration diagram of a distance measuring device showing another embodiment,
FIG. 3 is a configuration diagram of a conventional distance measuring device. 1 is a light source, 2 is a light projection lens, 3 is a target object, 4 is a light spot image, 5 is a light receiving lens, 6 is a light receiving element, 11 is an averaging number setting means, and 12 is an averaging processing means. In addition, in the figures, the same symbols indicate the same or corresponding parts.

Claims (1)

[Claims] a light projecting lens that irradiates light from a light source onto a target object as a light spot of an appropriate size; a light receiving lens that forms an image of the light spot; and a plurality of lenses that are proportional to the imaging position of the light spot image. In a distance measuring device having a light-receiving element that outputs electrical signals, and a distance calculating means that calculates a measured distance based on the electrical signals, an average number of times is set based on an S/N ratio determined by the electrical signals. A distance measuring device comprising: an average number setting means; and an average processing means for obtaining an average value by dividing a sum value obtained by sequentially adding the outputs of the distance calculation means by the average number of times by the average number.