SU794652A1 - Photoelectric displacement-to-code converter - Google Patents

Description

one

The invention relates to the field of automation and computer technology and can be used to connect analog sources of information with a digital computing device.

A device is known that contains a coordinate-sensitive bifotocell on which a rectangular light spot is projected. The photocell outputs are connected to the load resistances with which the voltage difference measuring circuit from photocurrent 1 is connected. In such a device, the bias is measured only at one coordinate and the measurement accuracy is limited by the instability of the photocell and the emitter parameters.

A known converter containing a chaefequadrant photodetector, the outputs of which are connected to the load resistances, and an analog information processing unit 2. A disadvantage of such a device is the poor accuracy of operation.

The closest technical solution to the invention is a photoelectric displacement transducer containing a reading unit with four photodetector elements, the outputs of which are connected to load resistances and comparators, and current summation units 3. Insufficient accuracy of operation

device due to the instability of the transfer coefficients of the output signals of the photodetectors, as well as the instability of the photodetectors themselves and the source

radiation.

The aim of the invention is to increase the accuracy of the converter.

The goal is achieved by the fact that a photoelectric transducer translates into a code containing a reading unit with four photodetector elements, two of which are connected to the corresponding inputs of the comparator, a switch, two resistor arrays,

two key blocks, a pulse generator and a register, the direct and inverse outputs of which are connected to the same inputs of the comparator through serially connected key blocks and a resistor array, and

through a switch connected to two other photodetector elements, and the output of the comparator is connected to one register input, the other input of which is connected to a pulse generator.

The block diagram of the converter is represented in the drawing.

The converter contains a reading unit 1 with four photo-receiving elements a, b, c, d and a shadow aperture with

square hole. Two diagonal

The located photodetector elements a and c are connected directly to the inputs of comparator 2, and the other two bud photodetectors are connected to the same inputs of comparator 2 via switch 3. The output of comparator 2 is connected to another input of register 4, the direct outputs of which are through a block of 5 keys and a resistor the matrix 6 {R, 2R, ...,) is connected to one input of comparator 2. The inverse outputs of register 4 are connected via block 7 of keys and the resistor matrix 8 to another input of comparator 2. The other input of register 4 is connected to the output of generator 9 of pulses.

The converter forms the position code of the light spot relative to the reading unit 1, first along one coordinate (for example, X), and then along another coordinate (Y). To form the position code of the light spot along the X coordinate, the switch 3 is set to a state where elements a and 6 are connected to one input of the comparator 2 and matrix 6, and the elements end to the other input of the comparator 2 and matrix 8. The output streams of elements a and 6, as well as cud, are pairwise summed.

In the zero position of the light spot on the X coordinate, the pairs of added currents / are equal, register 4 has a code corresponding to half its capacity, keys 5 and 7 connect the resistors of matrices 6 and 8 so that the load resistance R of the inputs of the comparator 2 are equal to each other with the margin of error of the younger order. In this case, the output signal of comparator 2 is zero.

When the light spot is displaced from the zero position, one total current increases (1/4-A), and the other decreases / 2 / - A / i. At the output of comparator 2, a light spot signal appears in a certain direction.

The register code 4 under the influence of the pulses of the generator 9 begins to change so that by switching on the corresponding dimensions of the matrices 6 and 8 to compensate for the inequality of the directions at the inputs of the comparator 2. After the compensation, the equality

L () / a (/ + 4),

where AJ is the change in the resistance of the matrices 6 and 8, proportional to the change in the AL / register code 4.

After converting this equality, we obtain a proportional relationship between the increment of A / current, which characterizes the magnitude of AZ displacement, and the increment of A / resistance of the matrix

d; Jm

or finally

dl

where K is the proportionality coefficient. Thus, the register 4 sets the code jV corresponding to the position of the light spot relative to block 1 along

10 coordinate X.

After transmitting the output code of register 4 to the consumer, the determination of the position of the light spot by the Y coordinate begins. Switch 3 is set to a state where elements a and cf are connected to one input of comparator 2 and elements of comparator 2 are connected to matrix 6 and to matrix 8, elements b and c are connected. Next, the measurement process occurs

0 as described.

The accuracy of the measurement of movement in the proposed converter is significantly improved compared with the known devices of similar purpose, since the influence of instability of the parameters of the electronic units, photodetector and radiation source is reduced.

Claims (3)

Invention Formula 0 Photoelectric transducer of movement into a code containing a reading unit with four photoreceiving elements, two of which are connected to the corresponding inputs of the comparator, in order to improve the accuracy of the converter, a switch is inserted into it , two resistor arrays, two key blocks, a pulse generator and a register, the forward and inverse outputs of which are connected via serially connected key blocks and a resistor matrix to the same inputs of the comparator and through a switch dinene with two other photodetector elements 5, and the comparator output is connected to one register input, the other input of which is connected to a pulse generator. Sources of information taken into account in the examination 0 1. Liseikin V.P. et al. Coordinate-sensitive bifotolem. Sat “Semiconductor devices and their application. Ed. Ya. A. Fedotova, vol. 16, “Owls. radio, M., 1966, p. 24, fig. 2 5 2. USSR Author's Certificate No. 442370, cl. G 08 C 19/36, 1974. 3. Klimashin, V.P., et al. Photocell position sensor. "Optical-mechanical industry, No. 10, 1976, p. 38, rice 1 (prototype).