SU1599650A1 - Transducer of linear displacements - Google Patents

Abstract

The invention relates to a measurement technique and can be used to measure linear movements of an object. The aim of the invention is to improve the manufacturability and accuracy by eliminating the drift of the photodetectors, stabilizing the steepness of their characteristics and the luminous flux of the radiator. The goal is achieved by the fact that a second photodetector 2, three AC amplifiers 5,6,10, alternator 9 alternators are inserted into the linear displacement transducer containing the LED 3 and the linear photodetector 1 located on the same optical axis on opposite sides of the transparent moving line 4. voltage, two adders 7.8 and detector 11. The output signal of the generator 9 through the adder 7 and the amplifier 10 is supplied to the LED 3, creating a variable light flux through the transparent ruler 4, on which an opaque strip is diagonally applied. The output signal of the adder 8 is proportional to the linear displacement of the ruler 4. The stabilization of the steepness of the characteristics of the photodetectors 1.2 and the radiation flux from the LED 3 occurs due to the generator automatically maintaining a voltage equal to the total signal received from the photodetectors 1.2. 2 Il.

Description

The invention relates to a measurement technique and can be used to measure linear movements of an object.

The aim of the invention is to improve the manufacturability and accuracy by eliminating the drift of the photodetectors, stabilizing the steepness of their characteristics and the luminous flux of the radiator.

FIG. 1 is a block diagram of a converter; in fig. 2 - B1elemen charts.

The linear displacement transducer contains two linear photodetectors i and 2 forming a microassembly, and a movable transparent ruler 4 located between them and the LED 3, on which an opaque strip half the width of the ruler is diagonally applied, so that the darkened parts on the ends of the ruler are their transparent sections, the photodetectors 1 and 2 are located perpendicular to the movement of the ruler and the line of their division runs along its longitudinal axis of symmetry, the outputs of the photodetectors 1 and 2 are connected to the inputs of the first Silitel 5 and second amplifier 6 AC, respectively, the output of amplifier 5 is connected to the first summing inputs of the first adder 7 and second adder 8, and the output of amplifier 6 is connected to the second summing input of the adder 7 and to the second subtracting input of the adder 8, the output of the generator 9 AC voltage is combined with the third subtracting and summing inputs of adders 7 and 8, respectively, the output of the adder 7 through the third amplifier 10 AC and the LED 3 are united by a common point of the circuit, and the output of the second adder 8 is black Detector 11 output terminal of the entire device.

The device works as follows.

The output signal of the alternating voltage generator 9 (Fig. 2), stabilized in amplitude, through the adder 7 and the amplifier 10 enters the LED 3, creating a variable light beam of rays through the transparent ruler 4. At the outputs of amplifiers 5 and 6, which receive signals from photodetectors 1 and 2, respectively, is formed by an alternating voltage with a generator frequency of 9 and amplitudes linearly related to the amount of movement of the left end of the ruler relative to the optical axis of the photoreceivers 1 and 2 (Fig. 2).

And at the output of amplifier 5 there is a signal directly proportional to the displacement:

(, L,

(one)

where X is the normalized displacement of the left 0 end of the ruler relative to the optical axis of the photosensor, varying in odds from 0 to 1; / Ci is the transmission coefficient of the first conversion path, and at the output of amplifier 6, voltage 5

U6 - / (2 (1-A), (2)

where Kz is the transmission coefficient of the second conversion path.

The transmission coefficients of the first and second paths, due to the sensitivity of the photodetectors and the amplification factors of amplifiers 5 and 6, are chosen the same. К К2. To obtain the output signal of the converter 5, the summing input of the adder 8 receives the voltage from the output of the amplifier 5, and its subtracting input - from amplifier 6, while

/ V5-l / e 2 /, X - /, (3)

0 The output signal 8 is directly proportional to the magnitude of the displacement, but has an offset (-K.) This offset is eliminated when the third summing input of the adder 8 is fed to the signal from the output of generator 9, whose amplitude is selected based on

5 equality. Finally

Ub, (iA-K., + (, X (4)

and after detecting, at the output of the converter, an analog signal is obtained directly proportional to the linear displacement of line 4 relative to the optical sensor.

The combination of blocks 7, 10, 3, 1, 2, 5, 6, 9 forms a closed loop designed to stabilize the steepness of the entire optoelectronic path, depending on the sensitivity of the FS of the detectors 1 and 2 and on the intensity of the radiation from the LED 3.

A stable amplitude voltage from the output of the generator 9 is applied to the input of the closed system. This setpoint is compared with the sum of the output voltages 5 and 6. Lastly, at any position of the sensor, it should be constant

i /, (, A4 - / (i +; 0.

Summer 7 compares the sum of these voltages with the set point, and the error is amplified by amplifier 10, the output voltage of which is supplying power to LED 3.

Such a stabilization system monitors possible changes in both the sensitivity slope of the photodetectors and the change in the radiation intensity of the LED 3, since equality (5) is violated both by changing the sensitivity and by changing the intensity, which leads to a change in the supply voltage 3 changes in the transmission coefficient of the entire optical path.

The drift of the output signal of the photodetectors 1 and 2 is eliminated by using the variable component of the output signal of the AC amplifiers 5 and 6 as motion information.

Claims (1)

Claims of the Invention A linear displacement transducer comprising an optically transparent movable ruler, a light guide and a linear photocamera located on the same optical axis on opposite sides of a transparent movable ruler, characterized in that in order to improve the measurement accuracy by eliminating the component of photodetector drift, changes  About the steepness of its characteristics and changes in the flux of the light emitter, it is equipped with a second photodetector, three AC amplifiers, an alternating voltage generator, two adders and a detector, the first and second photodetectors are located on the same axis, perpendicular to the movement of the optically transparent ruler, that the line of their separation is located along the longitudinal axis of symmetry of the ruler, the ruler is made with an opaque stripe diagonally printed, half the width of the ruler and the size of the darkened edge on the wallpaper line ends, equal to the transparent portion, connected to the outputs of photodetectors vho25 give the first and second amplifiers respectively AC, the AC output of the first amplifier is connected to the first summing inputs of the first and second adders, a second output AC amplifier connected to the second 30 summing the input of the first adder and the second subtracting input of the second adder, the output of the alternating voltage generator is combined with the third subtractive and summing inputs of the first and second adders, respectively, output 35 of the first adder via the third AC amplifier and the LED is combined with the common point of the circuit, the output of the second adder is connected to the detector input, and the detector output is the output of the converter.  5 Out 6 t 6 and / y.8 Byby Xi Hg FIG. g