JPS6281520A - Range finder - Google Patents

Abstract

PURPOSE:To measure a range with stable accuracy even when an S/N ratio largely varies, by outputting only the range operation signal in a reference S/N range by controlling a range operation means on the basis of the output of a S/N discriminator. 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. A light receiving lens 5 picks up the image of the light spot 4 to form the same on the light receiving surface of a light receiving element 5. Two electric signals iA, iB from the light receiving element 6 are added by an adder 7 and inputted to an S/N discriminator 11 to discriminate whether the added value is within a reference S/N range. If the inputted S/N is out of the reference S/N range, no output is issued from the S/N discriminator 11 and, therefore, a converter 12 emits no range signal (l). That is, the converter 12 outputs the range signal (l) only when the measurement of a range is normally performed.

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. 3 shows a conventional non-contact type distance measuring device. In Fig. 3, 1 is a light source, 2 is a light beam emitted from the light source 1, which is focused and projected onto an object 3 to be measured. This is a light projecting lens.

The light source 1, the projecting lens 2, and the target object 3 are located on the axis A, and the light source 1 emits light and the dimension is projected onto the target object 3 by the lens 2, forming a source spot 4f1 of one luminous flux. .

5 is a light receiving lens that forms an image of the original spot 4;

6 is a light receiving element that generates an electric signal corresponding to the imaging position P of the image of the original spot 4 formed by the light receiving lens 5; The receiving lens 5 receiving element 6 is on the axis aB
, and in this case, this axis B is disposed between said axis A and θ
form an angle.

Then, the two electric signals tA+ output from the light receiving element 6
iB are each adder 7. It is input to the subtracter 8, and the sum of both signals (iA+lB) is determined by the adder 7GC2.
A subtracter 8 calculates the difference (iA-iB) between both signals. 9 is a divider that divides the output of the subtracter 8 by the output of the adder T, and 10 is a converter that converts the position output P of the divider 9 into a distance output t.

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

Such a light receiving element 6 includes, for example, an original position detector that outputs an original signal proportional to the imaging position of the spot image toward both ends, and is disposed at both ends of this original position detector, and is arranged on the light receiving surface. It is composed of a photodetector that generates electric signals 1A and 1Bfr corresponding to the original signals incident on the oscilloscope. Therefore, the electrical signals iA, iB.

Depending on the value, the imaging position P of the original spot image is.

i　A+i　B It can be found as

By the way, the output of the light receiving element 6 is proportional to the imaging position P of the original spot image and its intensity, and produces a dead output signal. Therefore, in Equation (1) above, the term (iA+iB), which is a signal that changes in proportion to the change in intensity of the one-dimensional spot image, is introduced into the denominator, and ``#'' is proportional only to the imaging position of the spot image. I'm trying to get a signal to do that.

The adder T, the subtracter 8, and the divider 9 are arithmetic circuits for implementing the arithmetic operation shown in the above (l+ formula) based on the output signals iA, iB of the light receiving element 6, and in this way, At the output of the divider 9, an output value P corresponding to the imaging position of the original spot image is obtained.

On the other hand, suppose the distance to the target object 3 is 2t, and the installation interval between the light projecting lens 2 and the light receiving lens 5 is L.

t is.

t= □ ・・・・・・ (
2) It can be obtained as −θ. 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 one-dimensional 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=to-P...
13). In this case, 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 13), inputs one position output pt, and outputs a distance output t'2.

[Problem that the invention seeks to solve]

In conventional non-contact distance measuring devices, the amount of light and sound incident on the light-receiving element may be extremely reduced or increased due to the inclination or surface roughness of the target object.

And if the amount of incident i becomes extremely small.

Large variations occur in the arithmetic circuit. Furthermore, when the amount of incident light becomes extremely large, the signal becomes saturated and calculation becomes impossible. In other words, in either case, there was a problem in that accurate distance measurement was not possible.

This invention was made to solve the above problems, and by removing the distance calculation output when the S/N ratio is outside the range of the standard Sihe ratio, the S/N ratio can be increased. It is an object of the present invention to provide a distance measuring device that can measure distances with stable accuracy by outputting only normal measurement results even when there are fluctuations.

[Means for solving problems]

The distance measuring device according to the present invention includes an S/N ratio discriminator and does not output a distance calculation signal when the S/N ratio is outside the range of the reference SA ratio.

[Effect]

The distance measuring device according to the second aspect of the present invention controls the distance calculating means with the output of the SA ratio discriminator.

Only distance calculation signals within the range of the standard S/N ratio are output,
To measure distance with stable accuracy even when the S/N ratio fluctuates greatly.

〔Example〕

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

FIG. 1 is a block diagram of a non-contact distance measuring device showing an embodiment of the present invention, in which the same parts as in FIG. 3 are given the same reference numerals. 2 in Figure 1.

11 is an SA ratio discriminator, and the %S/N ratio is the sum of the amount of received light.

In other words, since it is proportional to the calculation output of the adder 7, the calculation output is inputted as the S/N ratio, and a preset standard S/N ratio is set.
1.12 is a converter that receives a large input position output Pf and outputs a distance signal t. , the distance signal t is not output unless there is an output from the SA ratio discriminator 11. This converter 12 and the adder 7. Subtractor 8. The distance calculation means 13 is composed of the divider 9 and the distance calculation means 13.

The distance measuring device having the above configuration operates as follows.

A light beam emitted from a light source 1 is transmitted to a projection lens 2 and is irradiated onto a target object 3 as a source spot 4.

The light-receiving lens 5 images this original spot 4 and forms the image on the light-receiving surface of the light-receiving element 6. After the two electric signals tA+iB from the light receiving element 6 are added by the adder T,
The signal is input to the S/M discriminator 11, and it is determined whether or not it is within the standard S/N ratio.

If the input S/l'J ratio is within the standard hoko ratio,
Since the S/N ratio discriminator 11 has the power, the converter 12 receives the above output and outputs the distance signal t.

On the other hand, if the input SA ratio is outside the range of the reference SA ratio, there will be no output from the ratio discriminator 11.

Transducer 12 does not provide a distance signal t. That is, converter 1
Reference numeral 2 outputs the distance signal t only when distance measurement is normally performed.

FIG. 2 shows a second embodiment of the invention.

13 is a distance calculator, which receives the electrical signal lAt from the light receiving element 6;
Determine the address based on the IB. And S/N
Upon receiving the output of the ratio/discriminator 11, the distance signal tf is read out from the tf memory (not shown) stored at the address location. However, if the SA ratio discriminator 11
If there is no output at , the distance calculation means 13 does not output the distance output t.

〔Effect of the invention〕

As described above, according to the present invention, since only the results in the normal measurement range are output, there is an effect that stable measurement accuracy is always ensured.

[Brief explanation of drawings]

Fig. 1 is a block diagram of a distance measuring device showing a first embodiment of the present invention, Fig. 2 is a block diagram of a distance measuring device showing a second embodiment thereof, and Fig. 3 is a block diagram of a conventional distance measuring device. It is. 1 is the light source, 2 is the light projecting lens, 3 is the target object, 4 is the original spot image%, 5 is the light receiving lens, 6 is the light receiving element, 11 is the S/
N ratio discriminator, 13 is distance calculation means. In Figure 21, the same reference numerals indicate the same or equivalent parts.・Patent applicant Patent attorney representing Mitsubishi Electric Corporation 1) Hiroshi Sawa (2 others) $IWi,. 21241: L's 3° Sweet Earned Stick 4, Se[S1 Marito Zu ni 5: Keijigo [Reni 2 people] 6: Guko Tokyo 11, Keisho S 1 vessel 13: Kagame Sho Takashi Ling Diagram 2 Figure 311F Procedural Amendment: (Voluntary) Niu'N+i'l Office L2 Office 1, IC, Indication of 't,'i' Request 1986-22
2265 No. 2・Name of the invention Distance measuring device 3, person making the correction・Relationship with 19 cases Patent applicant address Tokyo Shimo-dai III-ku Marunouchi■-cho[-
12 No. 3 shi” / Name (601) Shoryoden + Geitai Company Representative Mamoru Shiki Late 4, Agent Postal code 105 Address
East 3: (Miyakominato-ku Nishi-Shinbashi 1-T'rl 4-tone 10 Telephone number 03 (591) 5095 '5, Subject of amendment (1) Claims column of the specification (2) Invention of the specification Detailed Explanation Column 6, Contents of Amendment (1) The scope of claims is amended by attaching it to the attached sheet. (2) Specification 1'F is amended as follows. 7. Patent after amendment of list of attached documents A document stating the scope of claims; one or more amended claims; a projection lens that irradiates light from a light source onto a target object as a light spot of an appropriate size; and an image of the light spot that forms an image of the light spot; In the distance measuring device, the distance measuring device has a light receiving lens that outputs an LH electric signal to the imaging position of the light spot image, and a distance calculating means that calculates a measured distance based on the electric signal. Based on signal S/
The N ratio is compared with the standard S/N ratio, and the S/N ratio is determined as the standard S/N.
A distance measuring device comprising an S/N ratio discriminator that controls the distance calculating means to generate a distance output only when the distance is within the ratio.

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, the S/N ratio based on the electrical signal is compared with a reference S/N ratio. and an S/N ratio that controls the distance calculation means so that the distance calculation means generates a distance output only when the S/N ratio is within the reference S/N ratio.
A distance measuring device characterized by having an N ratio discriminator.