JPH04181115A - Distance measuring device - Google Patents

Abstract

PURPOSE:To prevent a distance to a target object from being detected improperly previously by calculating two outputs which becomes a constant ratio within a specified distance range and then outputting one of them as a distance- measurement output when a ratio of two outputs matches a constant ratio. CONSTITUTION:Detection signals Va and Vb of light-receiving regions 2a and 2b and detection signals Vb and Vc of light-receiving regions 2b and 2c are added 11 and 12 and are fed to a division circuit 13 for obtaining a distance output Vs. On the other hand, a division circuit 14 divides an output of the addition circuit 11 by the signal Vc and obtains a monitor output Vs'. The outputs Vs and Vs' are determined to show nearly a straight-line relationship with a distance at a specified distance range and the ratio is equal to a contact ration m. The output Vs which is amplified by coefficients r1 and r2 which are in a relationship r1 < m < r2 at amplifiers 15 and 16 is fed to comparators 17 and 18 along with the output Vs' and the output is supplied to a switch SW through an AND gate 19. Then, when a position of a target object 3 is proper, a ratio of the output Vs to the output Vs' is nearly equal to a constant ratio m so that the SW is closed and the output Vs is output. On the other hand, when the object 3 is not located properly, no output Vs is output.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Industrial Application Field This invention relates to a light projecting element that projects light onto a target object, and a light projecting element that emits light from the light projecting element in a direction perpendicular to the light projecting direction of the light projecting element. The present invention relates to a triangular distance measuring device that includes a light receiving element that receives reflected light from a target object at a position separated by a certain baseline length and outputs a signal according to the amount of received light.

(b) Conventional technology In a distance measuring device that measures the distance to a target object using a triangulation method, generally a light emitting element 1 is used as shown in FIG.
The light is projected onto the target object 3 through the light projecting lens 4, and the reflected light from the target object 3 is received by the light receiving element 2 through the light receiving lens 5. Emitter lens 4 and receiver lens 5
and are installed apart from each other by the base line length in a direction perpendicular to the light projection direction of the light projection element 1. In this configuration, when the distance from the light projecting lens 4 to the target object 3 changes, the incident angle of the light reflected from the target object 3 to the light receiving lens 5 changes, and the light receiving point on the light receiving element 2 (the center of the light receiving range)
changes, and the light receiving element 2 outputs a signal according to the position of the light receiving point. By detecting the output of this light receiving element 2, the distance R between the light projecting section and the target object is detected.

(C1 Problem to be Solved by the Invention - However, in the conventional distance measuring device described above, as shown in FIG. 2, when the target object 3 moves in the longitudinal direction of the light-receiving surface of the light-receiving element 2, that is, in the direction of the arrow X in the figure, the target object 3
As a result, the light receiving range of the light receiving element 2 of the reflected light from the target object 3 changes from the light receiving range S shown by the solid line in FIG. As the light receiving element 2 moves, the light receiving point on the light receiving element 2 is displaced, causing an error in the distance MR to the target object and the distance measurement output of the light receiving element 2.

However, none of the conventional distance measuring devices is capable of detecting such changes in the light receiving state, and when the target object 3
There is a problem in that when the light-receiving element 2 moves horizontally with respect to the light-receiving element 2, erroneous distance detection occurs.

An object of the present invention is to configure a large number of light-receiving regions in the longitudinal direction (baseline length direction) of the light-receiving element on the light-receiving surface of the light-receiving element,
Two outputs that have a constant ratio within a predetermined distance measurement range are calculated by changing the combination of light-receiving areas, and when the ratio of the two outputs obtained matches the constant ratio, one of the two outputs is used for distance measurement. By outputting it as an output, it is possible to determine whether or not the target object is in the correct position in the horizontal direction, and if the target object is displaced from the correct position, the detection output of the light receiving element is disabled, An object of the present invention is to provide a distance measuring device that can prevent erroneous detection of distance.

(d) Means for Solving the Problems The distance measuring device of the present invention includes a light projecting element that projects light onto a target object, and a constant direction from the light projecting element in a direction perpendicular to the light projecting direction of the light projecting element. A triangular distance measuring device comprising: a light receiving element that receives reflected light from a target object at a position separated by a baseline length and outputs a signal according to the amount of received light; Output calculating means for calculating two outputs that are divided into a plurality of light receiving areas and that are outputs related to different combinations of the light receiving areas and have a constant ratio in a predetermined distance measurement range, and two outputs calculated by the output calculating means. The present invention is characterized in that an output determining means is provided, which outputs one of the two outputs as a distance measurement output when the ratio of the two outputs matches the fixed ratio.

(91 Action) In this invention, triangulation is performed in which the light reflected from the light emitting element on the target object is received by the light receiving element and the distance to the target object is measured.

The light-receiving element is divided into a plurality of light-receiving regions in its longitudinal direction, and two outputs are calculated by the output calculating means by changing the combination of light-receiving regions among the plurality of light-receiving regions. These two outputs are determined to have a constant ratio within a predetermined distance measurement range. The output determination means calculates the ratio of the two outputs calculated by the output calculation means, and outputs one of the two outputs as a distance measurement output only when this ratio matches a certain ratio when the target object is in a proper position. . Therefore, if the target object is displaced from its proper position in the horizontal direction, the ratio of the two outputs calculated by the output calculation means will not match the predetermined integral ratio, and the output determination means will change the distance measurement output. No output. Therefore, no error occurs between the actual distance to the target object and the distance measurement output output from the light receiving element.

(f) Embodiment FIG. 1 is a diagram showing a circuit configuration diagram of a distance measuring device which is an embodiment of the present invention.

A detection signal VaxVc corresponding to the amount of received light is extracted from each of the three light-receiving regions 2a to 2C in the light-receiving element (multi-division photodiode) 2. The detection signals ■a and Vb of the light-receiving areas 2a and 2b are input to an adder circuit 11, and the detection signals Vb and Vc of the light-receiving areas 2b and 2c are input to an adder circuit 12. The outputs of the adder circuits 11 and 12 are input to the divider circuit 13. Further, the output of the adder circuit 11 is sent to the divider circuit 1 along with the detection signal Vc of the light receiving area 2c.
4 is input. The division circuit 13 divides the output of the addition circuit 11 by the output of the addition circuit 12 to obtain the ranging output Vs. On the other hand, the division circuit 14 converts the output of the addition circuit 11 into the light receiving area 2C.
is divided by the detection signal Vc to obtain the monitor output Vs'. As shown in FIG. 2, the distance measurement output Vs obtained in the division circuit 13 and the monitor output Vs' obtained in the division circuit 14 have a substantially linear relationship with the distance R in the predetermined distance measurement range R0 to R2. show. Further, as shown in the figure, the dividing circuit 13,
The calculation formula in 1.4 has been determined experimentally.

The ranging outputs Vs are multiplied by a coefficient r in an amplifier 15 and summed and inputted to an inverting input terminal of a comparator 17, and multiplied by a coefficient r2 in an amplifier 16 and summed and inputted to a non-inverting input terminal of a comparator 18. This coefficient rI+r2 has the relationship r,<m<:r2. Further, the monitor output Vs' obtained in the division circuit 14 is input to the non-inverting input terminal of the comparator 17 and the inverting input terminal of the comparator 18. The outputs of the comparators 17 and 18 are input to the AND gate 19, and the output of the AND gate 19 is supplied to the switch SW. This switch SW is provided in the output path of the ranging output Vs, and closes the output path when the output of the AND gate 19 is at the "H" level, and opens the output path with the "LL" level.

With the above configuration, when the target object 3 is at an appropriate position in the horizontal direction (X direction in FIG. 4), the reflected light from the target object 3 is transmitted to the light receiving area S of FIG. 5(A) in the light receiving element 2. The light is received in the state of , and the detection signal in the light receiving element 2 has a waveform that is symmetrical about the light receiving point as shown in FIG. 5(B).

In this way, when the target object 3 is at an appropriate position in the horizontal direction, the light-receiving range S moves in the longitudinal direction of the light-receiving surface of the light-receiving element 2 as the distance changes, and the detection signal of the light-receiving element 2 changes. As a result, the peak position is displaced in the longitudinal direction while maintaining a symmetrical waveform.

When the detection signal of the light-receiving element 2 is symmetrical about the light-receiving point, that is, when the position of the target object 3 is appropriate, the distance measurement output Vs obtained in the division circuit 13 and the monitor obtained in the division circuit 14 The ratio with the output Vs' substantially matches a constant ratio m. Therefore, the output of the amplifier 15 is smaller than the monitor output Vs', and the output of the amplifier 16 is larger than the monitor output S'. Therefore, the outputs of comparators 17 and 18 both become "H", the output of AND gate 19 also becomes "H" level, and switch SW closes the output path. As a result, the distance measurement output Vs obtained by the division zero path 13 is outputted via the output path.

On the other hand, when the target object 3 is not at an appropriate position in the horizontal direction, the reflected light from the target object 3 is received in a state such as a light receiving range S2 shown in FIG. 5(A). At this time, the detection signal of the light receiving element 2 is the detection signal Vt shown in FIG. 5(B).
The light receiving point is asymmetrical as shown in the figure. In this way, when the detection signal of the light receiving element 2 has an asymmetrical waveform, that is, when the target object 3 is not at an appropriate position in the horizontal direction,
The ratio between the ranging output Vs and the monitor output Vs' no longer matches the constant ratio m. Therefore, the output of the amplifier 15 exceeds the monitor output Vs' or the output of the amplifier 15 becomes lower than the monitor output Vs', and the comparators 17 and 18
, one of the outputs becomes "L". As a result, the output of the AND gate 19 becomes "L" level, the switch SW opens the output path, and the distance measurement output Vs obtained in the divider circuit 13 becomes Output will no longer be output from the output route.

As a result of the above operation, when the target object 3 is not at an appropriate position in the horizontal direction, the switch SW opens the output path, and the distance measurement output Vs is not output from the light receiving element 2. As a result, when the light receiving element 2 receives reflected light in the light receiving range S2 shown in FIG. 5(A), the light receiving point (center of the light receiving range, that is, the peak position of the detection signal) Displaced to the 2a side. Therefore, the distance measurement output Vs of the light receiving element 2 becomes a value corresponding to a longer distance than the actual distance R to the target object 3, and an error occurs between it and the actual distance R, but in this case, the switch SW
is opened and the distance measurement output Vs is not output, so that erroneous detection of distance can be prevented.

Note that the arithmetic expressions in the division circuits 13 and 14 are not limited to those shown in the above embodiments, and other arithmetic expressions may be used that provide two outputs having a constant ratio for a predetermined distance measurement range.

Further, the number of divisions of the light receiving element 2 is not limited to three.

(Slight effect of the invention According to this invention, the ratio of two outputs related to different combinations of a plurality of light-receiving areas constituting a light-receiving element is determined, and if this ratio does not match a predetermined constant ratio by -1, Disabling the distance measurement output prevents distance measurement from occurring when there is an error between the measured distance and the actual distance, which has the advantage of preventing erroneous detection of the distance to the target object. be.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the circuit configuration of a distance measuring device according to an embodiment of the present invention, and FIG. 2 shows two outputs and distance j! in the same distance measuring device. It is a figure showing the relationship with IR. Furthermore, FIG. 3 is a diagram showing the relationship between a light emitting element, a light receiving element, and a target object in a general distance measuring device including an embodiment of the present invention, and FIG. 4 is a diagram showing the usage state of the same general distance measuring device. The external view shown in FIGS. 5A and 5B are diagrams showing the light receiving state and detection signal of the light receiving element in the general distance measuring device, respectively. 1-Light emitting element, 2-Light receiving element, 3-Target object, 13.14-Division circuit (output calculation means), 15.16-
Amplifier (output determination means), 17.18-Comparator (
output judgment means), 19-AND gate (output judgment means)
, SW-switch.

Claims (1)

[Claims] (1) A light projecting element that projects light onto a target object, and a light projecting element that receives reflected light from the target object at a position a certain baseline length away from the light projecting element in a direction perpendicular to the light projection direction of the light projecting element. A triangular distance measuring device comprising a light receiving element that outputs a signal according to the amount of received light, wherein the light receiving element is divided into a plurality of light receiving areas in the base line length direction, and the light receiving areas are divided into different combinations. Output calculating means for calculating two outputs having a constant ratio in a predetermined ranging range, and one of the two outputs when the ratio of the two outputs calculated by the output calculating means matches the constant ratio. A distance measuring device comprising: output determining means for outputting as a distance measurement output.