SU1624690A1 - Photoelectric position-to-number converter - Google Patents

Abstract

The invention relates to automation and computer technology and can be used: for converting movement into code for analog-to-digital conversion of information. The aim of the invention is to increase the reliability of the conversion. The goal is achieved by the fact that in the photoelectric transducer movement into a code containing sequentially located

Description

2WH -K // L. V // A V // A Y /// 1 U // L

3УЈД -№У ///////////////// Л У // У //// // Л

The radiation source 1, the slit diaphragm 3, the photodetectors 4 and 5, the summing amplifier 4, the amplifier 8, the resistor divider 10, the comparators 13 and the decoder 14, additionally introduced the photodetector 6, the reader E, the reference resistor 12 and the coded element 2 located between the radiation source 1 and the slit diaphragm 3. The photoreceivers 4 and 5 form periodically varying antiphase signals, and the photodetector 6 operates in the dark mode. Anti-phase signals are summed at summing amplifier 4, and the value of dark potential is subtracted from subtractor 9. The resulting difference is applied to one input of resistor divider 10, to the other input of which voltage is applied, formed by amplifier 8 from output of photodetector 6. Resistor divider 10 generates threshold signals proportional to displacement taking into account destabilizing factors, and binary comparator 13 and decoder 14 allocate binary code. 2 Il.

The invention relates to automation and computing and can be used to convert motion into code in the analog-to-digital conversion of information.

The purpose of the invention is to increase the reliability of the converter,

FIG. 1 shows the structure of a photoelectric displacement transducer to a code; in fig. 2 - an example of constructing a decryption - 10 rtor.

The photoelectric converter for moving to a code contains successively located radiation source 1, coded element 2 (only the low-order code track is shown 15), slit aperture 3, photodetectors 4, 5 and 6, summing amplifier 7, amplifier 8, subtractor 9, resistor voltage divider 10, containing in series 20 connected variable resistors 11, offset voltage sensor, made on the reference resistor 12, comparators 13 of the same name, decoder 14, which contains the elements EXCLUSIVE- 25 15

When changing external conditions, such as temperature, fluctuations in the dark current values of photodetectors 4, 5 and 6 can be quite significant. The sum of the 30 voltages of the photodetectors 4 and 5, labeled Ui and LJ2, respectively, is divided into a proportionally displaced part of the resistor 10 voltage divider excluding dark currents, and the quantization levels 35 are determined not relative to the common potential bus. and with respect to the voltage determined by the dark current b of the photodetector 6. The voltage of the jth quantization level is determined by the expression 40

Uj (Ui + U2-2UT) Kj + UT, (1)

where IJj is the voltage of the jth ro quantization level constituting the Kjth part of the sum of the antiphase voltages Ui and U2,

UT - IrRon,

where it is the current of the photodetector 6 operating in the dark mode; 1

Ron - the value of the reference resistor 12.

The antiphase voltages of the photodetectors 4 and 5 provided by the arrangement of the slots in the slit diaphragm 3 are added to the summing amplifier 7, and the subtractor 9 is subtracted from the sum DT. This voltage is applied to one of the inputs of the resistor divider 10. To the other input of the resistor divider 10, the voltage DT is supplied from the reference resistor 12. The value UT stabilized by the output of the amplifier 8 is shifted to the reference resistor 12, which shifts the quantization levels. Comparators 13 compare the voltages selected by the quantized levels with the voltage of the photodetector 4. The response thresholds of the comparators 13 thus vary in proportion to the amplitude of the signals of the photoreceivers 4 and 5 and their dark current of the photoreceivers. The decoder 14 generates a binary code, which is fed to the output of the converter.

The photoelectric transducer to the code works as follows.

The coded element 2, illuminated by the radiation source 1, is moved relative to the slit diaphragm 3, the antiphase signals Ui and 1) 2 are periodically changing at the photo receiver 4 and the photodetector 5, the total of which is represented by the voltage of the sum amplifier 7. At the inputs of the resistor divider 10, the potential difference is Ui + Da - 2U, since one input voltage is applied to the voltage Ui + Da - UT from the subtractor 9, and to the other - UT from the reference resistor 12, which is controlled by the output of the amplifier 8 This is on The strand is divided according to the quantization levels into parts determined by the coefficients Kj. At the output of the comparators 13, the voltage thresholds are triggered by taking into account the magnitude of the UT from the reference resistor 12. At the comparators 13, quantized levels are extracted from the voltage of the photo receiver 4, and the output of the decoder 14 is the output of the output code.

When the amplitude of the antiphase signals changes, the sum of the voltages at the output of the summing amplifier 7 and the magnitude of the thresholds of the comparators 13 change accordingly.

When the dark current changes, the voltage UT changes accordingly at the output of amplifier 8 and at the input of the subtractor 9, the reference resistor 12, which leads to a corresponding change in the thresholds of the comparators 13.

Thus, the magnitude of the threshold operation of the comparators 13 varies with external influences proportional to the change of voltage parameters, Ui, and the switching of the comparators 13 depends only on the amount of movement of the coded element 2, which ensures the reliability of the converter.

Claims (1)

Invention A photoelectric transducer of displacement into a code containing an amplifier, a successive source of radiation, an aperture with a slit, a first and a second photodetector, the outputs of which are connected to the inputs of a summing amplifier, a resistor voltage divider. the outputs of which are connected to the first inputs of the comparators of the same name, the second inputs of which are combined, and the outputs are connected to the inputs of the decoder, the outputs of which are the outputs of the converter, characterized in that, with the aim of increasing the reliability of the converter, a subtractor, a third photoreceiver, is inserted into it , the bias voltage adjuster and the coded element, made in the form of alternating identical in size transparent and opaque portions, and the second aperture is made in the diaphragm, the width of the slots is equal to the width of the coded section the distance between the sides of the slits of the same name is equal to an odd number of areas of the coded element installed between the radiation source and the diaphragm, the third photodetector is located between the aperture slits, the first and second photoprismum sensors are located opposite the aperture slits and are optically connected through the aperture and encoded element of the radiation source, the output of the third photodetector is connected to the input of the amplifier, the output of which is connected to the first output of the bias voltage setting device, the first input of the resistor The first divider and the first input of the subtractor, the output of which is connected to the second input of the resistor divider, the output of the summing amplifier, is connected to the second input of the subtractor, the output of the first photodetector is connected to the second input of one of the comparators, the second output of the bias voltage setting device is connected to the common potential bus. 15 g sixteen FIG. g 18 P