JPH0369042B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an optical detection device that receives and detects direct light from a light emitting device or reflected light obtained by reflecting light from a light emitting device onto an object.

Such optical detection is necessary for detecting the surface position of an object. Conventionally, an optical filter is provided in front of the light receiving means in order to reduce the adverse effects of ambient light, but this is not a reliable measure against ambient light. In other prior art, light is modulated and emitted from the light emitting means, but in such prior art, the detection circuit in the light emitting means is complicated and the detection time is long.

The purpose of the present invention is to prevent the harmful effects of ambient light,
Moreover, it is an object of the present invention to provide an optical detection device that requires less time for detection.

The present invention includes a light emitting means 15 that irradiates light onto an object 42, and a light receiving means 1 that receives reflected light 41 from the object 42.
a first pair of opposing electrodes 2 and 3 provided in a spaced apart manner within the semiconductor element;
A light receiving means 1 has electrodes 2 and 3 and a second pair of opposing electrodes 4 and 5 provided at a distance, which are orthogonal to each other, and derives a current corresponding to the amount of light to be received.
and sample hold means 51, 52, 5 for holding the output from each electrode 2, 3; 4, 5 of the light receiving means 1.
3, 54, and the outputs of the sample and hold means 51, 52 which turn on and off the light emitting means 15 and hold the outputs of the first electrodes 2, 3 immediately before the lighting are X1n, X2n, The outputs of the sample hold means 53, 54 holding the outputs of the first electrodes 4, 5 are Y1n, Y2n, and the sample hold means 51 holds the outputs of the first electrodes 2, 3 during lighting. ,52 outputs
X^1n, X^2n, a sample hold means 53 which holds the output of each second electrode 4, 5 during lighting;
54 are designated as Y^1n and Y^2n, furthermore, the outputs of the sample and hold means 51 and 52 which hold the outputs of the first electrodes 2 and 3 immediately after the light is turned off are designated as X〓1n and X〓2n, When the outputs of the sample and hold means 53 and 54 holding the outputs of the second electrodes 4 and 5 immediately after the lights are turned off are Y〓1n and Y〓2n, ΔX1n=X^1n−X〓1n+X1n/2 ΔX2n =X^2n−X〓2n+X2n/2 ΔY1n=Y^1n−Y〓1n+Y1n/2 ΔX2n=Y^2n−Y〓2n+Y2n/2 Calculate the two-dimensional coordinates (Xn, Yn), Xn=ΔX1n−ΔX2n /ΔX1n+ΔX2n Yn=ΔY1n−ΔY2n/ΔY1n+ΔY2n.

FIG. 1 is a block diagram of the basic structure of the present invention. The light receiving means 1 receives the light from the light emitting means 15 directly, as indicated by the reference numeral 30, or alternatively, as indicated by the reference numeral 41, from the object 4.
2 receives the reflected light. The light emitting means 15 is realized by a light emitting diode or the like. Light receiving means 1
In the semiconductor device, four electrodes 2, 3, 4, and 5 are provided orthogonally to each other. electrodes 2, 3,
Photocurrents IX1, IX2, IY1, derived from 4, 5
IY2 is changed to a voltage value by current-voltage conversion circuits 6, 7, 8, and 9, and is converted into signals X1, X2, Y1, and Y2. Photocurrents Ix1, Ix2, from light receiving means 1
Iy1 and Iy2 are levels corresponding to the amount of light received, for example, levels that are directly proportional. Outputs from the current-voltage conversion circuits 6, 7, 8, 9 are sample-and-hold circuits 11, 16; 12, 17; 13, 18;
Given on April 4, 19. Among these, the outputs from the sample and hold circuits 11 and 16 are given to the arithmetic circuit 20 and calculated, and similarly, the outputs from the sample and hold circuits 12, 17;
The outputs from 4 and 19 are sent to arithmetic circuits 21, 22, and 2.
3 are given respectively. Timing control circuit 1
0, the light emitting means 15 is energized to emit light for a period indicated by the reference mark W1 in FIG.
The light emitting means 15 is turned off for a period indicated by , and the light emitting means 15 lights up intermittently in this way. In FIG. 2, a signal X1 from the current-voltage conversion circuit 6 due to the disturbance light detected by the light-receiving means 1 is indicated by reference numeral 11, and a signal X1 from the current-voltage conversion circuit 6 during lighting of the light-emitting means 15 The output X1 of is indicated by reference 12.

The timing control circuit 10 holds the signals X1n, X2n, Y1n, and Y2n from the current-voltage conversion circuit 6 immediately before lighting the light emitting means 15 in sample and hold circuits 11, 12, 13, and 14. Next, the light emitting means 15 is turned on for a period W1, and the outputs of the current-voltage conversion circuits 6, 7, 8, and 9 at this time are
X^1n, X^2n, Y^1n, and Y^2n are held in sample and hold circuits 16, 17, 18, and 19, respectively. Arithmetic units 20, 21, 22, and 23 calculate the first to fourth equations.

ΔX1n=X^1n−X1n…(1) ΔX2n=X^2n−X2n…(2) ΔY1n=Y^1n−Y1n…(3) ΔY2n=Y^2n−Y2n…(4) In the computing units 24 and 25 , the quadratic coordinates (Xn, Yn) of the light spot A are calculated based on the fifth and sixth equations.

Xn = ΔX1n - ΔX2n / ΔX1n + ΔX2n (5) Yn = ΔY1n - ΔY2n / ΔY1n + ΔY2n (6) The timing control circuit 10 operates the sample and hold circuits 26 and 27, thereby controlling the value Xn that is unstable during sampling. , Yn are stabilized, these values Xn and Yn are held and derived.

In the above configuration, the sample values X1n, X2n, Y1n,
Although Y2n was the value immediately before the light emitting means 15 was turned on, it may be sampled immediately after the light emitting means 15 is turned on as another basic structure of the present invention.

FIG. 3 is a block diagram of one embodiment of the present invention. This embodiment is similar to the previously described configuration, and corresponding parts are provided with the same reference numerals. The outputs from the electrodes 2, 3, 4, and 5 of the light receiving means 1 are converted into voltage values by current-voltage conversion circuits 6, 7, 8, and 9, and are applied to sample and hold circuits 51, 52, 53, and 54, respectively. sample and hold. The outputs from the sample and hold circuits 51, 52, 53, and 54 are selectively and sequentially switched by a multiplexer 55, converted to digital values by an analog-to-digital converter 56, and then sent to a microcomputer or the like. A processing circuit 50 is thus implemented. The processing circuit 50 controls the sample and hold circuits 51, 52, 53, and 54, and also controls the operation of the multiplexer 55.
It also controls the analog-to-digital converter 56. The drive circuit 57 intermittently drives the light emitting means 15 in response to the output from the processing circuit 50.

The operation will be explained with reference to FIG. step
Moving from m1 to step m2, outputs X1n,
Y1n and Y2n (see FIG. 5) are sampled and held by sample and hold circuits 51, 52, 53, and 54, and taken into the processing circuit 50. These values X1,
X2, Y1, and Y2 are signal levels due to disturbance light, and it is determined whether the values are the saturated light amount of the light receiving means 1. When the amount of light is not saturated, the step
Moving to m4, the light emitting means 15 is turned on. step
m5 receives direct light 30 or reflected light 41 when the light emitting means 15 is turned on, and receives sample values X^1n,
X^2n, Y^1n, and Y^2n are sampled and held and input to the processing circuit 50. Thereafter, in step m6, the light emitting means 15 is turned off. In step m7, it is determined whether the sample values X^1n, X^2n, Y^1n, Y^2n are less than the saturation light amount of the light receiving means 1, and if so, the process moves to step m8. In step m8, the light emitting means 1
Current-voltage conversion circuits 6, 7, immediately after turning off the light of 5
Sample value of output from 8, 9 X〓1n, X〓2n,
Y〓1n and Y〓2n are sampled and input to the processing circuit 52. At step m9, these values X〓1n, X〓2n, Y〓1n,
It is determined whether Y〓2n is less than the saturated light amount of the light receiving means 1, and if so, the process moves to step m10. step
In m10, the values ΔX1n, ΔX2n, ΔY1n, and ΔY2n are obtained by calculating equations 7 to 10.

ΔX1n=X^1n−X〓1n+X1n/2 …(7) ΔX2n=X^2n−X〓2n+X2n/2 …(8) ΔY1n=Y^1n−Y〓1n+Y1n/2 …(9) ΔY2n=Y^2n -Y〓2n+Y2n/2...(10) The value of the second item in these equations 7 to 10 is the average value of the values immediately before and after the lighting of the light emitting means 15. The sample value ΔX1n by the light receiving means 1 when the light is turned off and when the light is turned on can be accurately determined.

Values of formulas 7 to 10 ΔX1n, ΔX2n, ΔY1n,
Based on the value of ΔY2n, in step m11, equations 11 and 12 are calculated, and the light point A(Xn,
Yn) is calculated and its value is derived in step m10.

Xn = ΔX1n - ΔX2n / ΔX1n + ΔX2n (11) Xn = ΔY1n - ΔY2n / ΔY1n + ΔY2n (12) When it is determined in step m13 that the arithmetic operation has been completed, a termination operation is performed in step m14.

If the amount of light received by the light receiving means 1 is equal to or greater than the saturated amount of light at steps m3, m7, and m9, the process moves to step m15, where it is determined that the sample value is abnormal and the process returns to step m2.

As described above, according to the present invention, the position of the object 42 can be determined by the coordinates (Xn, Yn) on the single light receiving means 1.
can be detected two-dimensionally and in a short time. The calculation of the coordinates is performed using the sample values X1n, X2n; Y1n, Y2n immediately before the light emitting means 15 turns on, and the sample values X〓1n, X〓2n; The average value of 〓1n, Y〓2n,
Since this is done based on the difference between the sample values X^1n, X^2n; Y^1n, Y^2n during lighting, it is possible to prevent the adverse effects of ambient light.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the basic configuration of the present invention, FIG. 2 is a waveform diagram for explaining the operation of FIG. 1, FIG. 3 is a block diagram of an embodiment of the present invention, and FIG. FIG. 5 is a flow chart for explaining the operation of the embodiment shown in FIG. 3, and FIG. 5 is a waveform diagram for explaining the operation of the embodiment shown in FIGS. 3 and 4. 1... Light receiving means, 2, 3, 4, 5... Electrode, 6,
7, 8, 9... Current voltage conversion circuit, 10... Timing control circuit, 11-14, 16-19, 26, 2
7, 51-54...sample hold circuit, 15...
Light emitting means, 20, 21, 22, 23...subtractor, 2
4, 25... Arithmetic circuit, 50... Processing circuit, 55... Multiplexer, 56... Analog-digital converter,
57...Drive circuit.

Claims (1)

[Claims] 1. Light emitting means 15 for irradiating light onto the object 42, and light receiving means 1 for receiving reflected light 41 from the object 42.
a first pair of opposing electrodes 2 and 3 provided in a spaced apart manner within the semiconductor element;
A light receiving means 1 has electrodes 2 and 3 and a second pair of opposing electrodes 4 and 5 provided at a distance, which are orthogonal to each other, and derives a current corresponding to the amount of light to be received.
and sample hold means 51, 52, 5 for holding the output from each electrode 2, 3; 4, 5 of the light receiving means 1.
3, 54, and the outputs of the sample and hold means 51, 52 which turn on and off the light emitting means 15 and hold the outputs of the first electrodes 2, 3 immediately before the lighting are X1n, X2n, The outputs of the sample hold means 53, 54 holding the outputs of the first electrodes 4, 5 are Y1n, Y2n, and the sample hold means 51 holds the outputs of the first electrodes 2, 3 during lighting. ,52 outputs
X^1n, X^2n, a sample hold means 53 which holds the output of each second electrode 4, 5 during lighting;
54 are designated as Y^1n and Y^2n, furthermore, the outputs of the sample and hold means 51 and 52 which hold the outputs of the first electrodes 2 and 3 immediately after the light is turned off are designated as X〓1n and X〓2n, When the outputs of the sample and hold means 53 and 54 that hold the outputs of the second electrodes 4 and 5 immediately after the lights are turned off are Y〓1n and X〓2n, ΔX1n=X^1n−X〓1n+X1n/2 ΔX2n =X^2n−X〓2n+X2n/2 ΔY1n=Y^1n−Y〓1n+Y1n/2 ΔX2n=Y^2n−Y〓2n+Y2n/2 Calculate the two-dimensional coordinates (Xn, Yn), Xn=ΔX1n−ΔX2n /ΔX1n+ΔX2n Yn=ΔY1n−ΔY2n/ΔY1n+ΔY2n.