JPS62187278A - Detecting circuit for light shield quantity - Google Patents

Abstract

PURPOSE:To correct an error in the sensitivity of photodetectors in real time by dividing the outputs of respective photodetectors when light is cut off actually by the outputs of the photodetectors when the light is not cut off, and removing an error in output level. CONSTITUTION:A light source part 1 which has plural light sources is applied with a voltage from a power source 8 and sends light to all photodetectors of a photodetection part 2. The photodetection part 2 supplies an analog output based upon the irradiated light to an analog switch 2. The switch 3 selects one of plural photodetectors of the photodetection part 2 according to an address signal 103 from a clock control circuit 7, performs A/D conversion 4, and then supplies digital data 102 to a memory circuit 5 and an arithmetic circuit 6. The output data of each photodetector when a voltage which is 1/10 as large as usual is applied to the light source part 1 is stored in the circuit 5 with a control signal 107 from the circuit 7 and correcting value input data 105 from the circuit 5 and the output of the photodetector in normal read operation are processed by using a prescribed expression to output data 106.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a detection circuit that detects the presence or absence of an object by blocking light.

[Conventional technology]

Conventionally, errors in the sensitivity of the photodetector of this type of photodetector circuit have been corrected by making the gain of each amplifier variable using a semi-fixed resistor or the like.

[Problem that the invention seeks to solve]

However, there is a problem in that the correction tends to be incorrect due to changes over time, deterioration of the light source, and misalignment of the light source and light receiver due to mechanical vibration.

Therefore, an object of the present invention is to provide a light shielding amount circuit that can correct the sensitivity error t of a light receiver in real time.

[Means for solving problems]

According to the present invention, a plurality of light receivers detecting the amount of emitted light;
An analog switch that selects the signal of one of the receivers, an A/D converter that converts the analog signal of the receiver into a digital signal, a memory that stores correction data, and an actual value that is read from the memory value. A calculation circuit that performs calculations with the value of and obtains an output, a light source that provides light to each light receiver, a power source that applies voltage to the light source, and a clock control circuit that controls the timing of each part.
A characteristic light shielding amount detection circuit is obtained.

That is, the present invention is characterized in that the output when the light is actually shielded is divided by the output of each photoreceiver when the light is not shielded, thereby eliminating errors in the output level.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

Referring to FIG. 1, which is a block diagram of an embodiment of the present invention, a light source 1 of a light source section 1 irradiates light sound onto a light receiver 1 of a light receiving section 2. As shown in FIG. Similarly, the light source 2 irradiates light to the light receiver 2, and the light source N irradiates light to the light receiver N, respectively. The light receiving section 2 provides an analog output to the analog switch 3 according to the amount of irradiated light. Analog switch 3 receives address signal 1 from clock control circuit 7
03, one of the outputs of the N light receivers of the light receiving section 2 is selected and the output 101 is supplied to the A/D converter 4.

The A/D converter 4 receives the supplied analog data 101
is converted into digital data 102 and supplied to the memory circuit 5 and the arithmetic circuit 6. The memory circuit 5 outputs A/A to the address indicated by the address signal 103 of the clock control circuit 7.
Information on the output 102 of the D converter 4 is written using a write timing pulse 104 from the clock control circuit 7.

A/D:y parameter 4 is line address signal 10 except during writing.
The data at the address indicated by 3 is output and given to the arithmetic circuit 6 VC as correction data. The arithmetic circuit 6 receives the output 102 of the A/D converter 4 and the output data 1 of the memory circuit 5.
05 performs a predetermined calculation, (102/105) x G (G=constant), and outputs the result as output data 106. The power supply 8 normally supplies the light source unit 1 with a voltage equivalent to obtaining the optical charge necessary for the reading operation, but the power supply control signal 107 from the clock control circuit 7 reduces the voltage to 1/1 during normal operation.
A voltage corresponding to obtaining a light amount of 0 is supplied to the light source section 2.

FIG. 2 is a timing diagram showing the operation of the first prisoner. When power is supplied to the block diagram of FIG. A voltage corresponding to the light intensity of 1/10 during normal reading is supplied to the light source section 1. Next, as shown in FIG. An address signal 103 indicating l is applied.

Analog switch 3 provides an analog output of light receiver 1 to A/D converter 4 . The A/D converter 4 converts the output of the light receiver 1 into digital data and sends it to the memory circuit 5.
give to After the address signal 103 and the output 102 of the A/D converter 4 are stabilized, the clock control circuit is transferred to the memory circuit 5.
A write signal 104 is applied to the light receiver 1 to write the output data of the light receiver 1 when the light intensity is 1/10 of that of normal reading.

Next, the clock control circuit 7 gives the address signal 103 indicating the photoreceiver 2 to the analog switch 3 and the memory circuit 5, and in the same manner as described above, the address signal 103 indicating the photoreceiver 2 is 1/10 of the normal reading time of the photoreceiver 2.
The output data at the time of the light intensity is written into the memory circuit 5. Thereafter, in the same manner, output data at a light intensity of 1710 during normal reading up to the light receiver N is written into the memory circuit 5.

Next, in order to enter the normal reading operation, the clock control circuit 7 turned off the ML source control No. 18 107 that was being applied to the stain source 8, and the power supply 8 sent the light source 1 to the light amount equivalent to the amount of light during normal reading. supply voltage. Next, in the same way as when writing to the memory, the clock control port yI & 7 gives an address signal 103 to the analog switch 3 and memory circuit 5.The output of the light receiver selected as the analog switch 3 is converted into a digital signal 102 by the A/D converter 4. It is converted into and given to the calculation circuit j166.

The memory circuit 5 has a pre-stored value 1 for normal reading.
It is given as correction value input data 105 to the output data calculation circuit of the light receiver when the light intensity is /10.

Next, the arithmetic circuit 6 calculates (signal 102/signal 105) xu(G
calculates a constant value n with gain and provides it to an external device as output data 106.

As explained above, the pan-skip for each receiver is set to 1/1 in advance.
A light intensity of 10 is given and stored in a memory circuit, and the input data and memory data are calculated during actual measurement to obtain data with variations corrected in real time.

FIG. 3 is a diagram showing the effect of this embodiment. Figure 3 (a
) is the output of the light receiver 1-3 when the light intensity is 1/10 when not shaded and is stored in the memory. FIG. 3(b) shows the output before calculation of the light receiver 1-3 during normal reading when light is not shielded, and it can be seen that there are variations depending on the light receiver. FIG. 3(C) shows the output after calculation, and the variations have been corrected.

In this way, fluctuations in the output level of the light receiver are corrected in real time, so by inserting a medium whose amount of light shielding is to be measured between the light source and the light receiver, measurement data with little error can be obtained.

〔Effect of the invention〕

As explained above, the present invention has the effect of obtaining data with less error by storing the output error of each light receiver in advance and performing calculations with the input data during actual measurement.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, FIG. 2 is a timing chart showing the operation of this block diagram, and FIG. 3 is a diagram showing the output of the light receiver. 1...Light source section, 2...--Light receiving section, 3...
...Analog switch circuit, 4...A/D
Converter, 5...Memory circuit, 6...
Arithmetic circuit, 7... Clock control circuit, 8...
...Power supply for light source. (6 Otsu) (bunsha 3 figure/z 3 A0

Claims (1)

[Claims] a plurality of light receivers that detect the amount of irradiated light; an analog switch that selects a signal from one of the light receivers; and an analog switch that converts the analog signal of the light receiver into a digital signal.
a D converter, a memory that stores correction data, an arithmetic circuit that performs arithmetic operations on the memory value and the read actual value and obtains an output, a light source that provides light to all of the light receivers, and the light source. What is claimed is: 1. A light shielding amount detection circuit comprising: a power source that applies a voltage to the circuit; and a clock control circuit that controls the timing of each part.