SU1260680A1 - Device for measuring linear displacements - Google Patents

Abstract

The invention relates to a measurement technique and can be used in measuring linear displacements using ultrasonic surface waves. The aim of the invention is to improve the measurement accuracy by measuring at intervals adjacent to the displacement by an integer number of half-waves. According to a device for measuring linear displacements in a stationary piezoelectric plate, a surface acoustic wave is excited by an interdigital transducer, which is received by an interdirectional transducer located on a mobile piezoelectric plate. When moving the latter, the phase difference between the emitted mjiM and the received signals changes, by which the magnitude of the displacement is judged. Upon reaching a predetermined phase angle close to the phase angle of the dead zone, the surface acoustic wave is received by a second interdigital transducer located on a mobile piezoelectric plate at a distance of a quarter of the wavelength from the first transducer. 1 il. SS cl

Description

"one

The invention relates to a measurement technique and can be used to measure linear displacements using ultrasound surface waves.

The aim of the invention is to improve the measurement accuracy by measuring in the intervals that are attached to an integer number of half-waves.

The drawing shows a device for measuring linear displacements.

The device comprises a stationary piezoelectric plate 1 with an interdigitator transducer 2 located on it and applied 3 surface acoustic wave absorbers and a movable piezoelectric plate A with identical interdigital transducer 5 and 6 and absorbers of 7 surface acoustic waves located on it. The on-pin converter 2 is connected to the generator 8. The on-pin converter 5 is connected to the input of the phase difference meter 9, the other input of which is connected to the generator 8. The on-pin converter 6 is connected to

ts

20

25

phases in between. The measured phase difference is proportional to the distance between the counter-pin converters 2 and 5 and corresponds to the measured displacement, which is determined by the reading unit 11, which continuously determines the value of the phase angle and compares it with the specified reference angle. the angle close to the phase angle of the dead zone, the reading unit 11 switches to the operation of the counter-pin converter 6. Since the counter-pin converter 6 is located relative to the counter-pin transducer 5 is at a certain distance, i.e. on / 4, the signal taken from it and measured by the meter 10

the input of the second meter 10 phase difference, phase-shifted on these phases, the other input of which is also 12 relative to the signal, is removed — connected to the generator 8. Outputs of phase difference 9 and 10 emitted from the counter-pin converter 5 and the phase difference measured by the meter 9. Thus, 35 the measured phase angle by the meter 10 phase difference will be equal to

dinenets to the reading unit 11. The anti-pin converter 6 is set at a quarter-wavelength distance from the outermost electrode of the anti-pin converter 5, which is required to create an additional phase shift, the distance depending on the step size of the electrodes of the anti-pin converter. A phase difference meter 10 connected by an input to an anti-pin converter 45 6 gives a phase shift equal to - ii / 2, the value of which can be determined by a calculation method and depends on the value of the wavelength emitted by the anti-pin converter 50.

A device for measuring linear displacements operates as follows.

When applying the exciting voltage of 55 NIN from generator B to the interdigital transducer 2, the surface acoustic excitation is excited in it.

I

I

Ф 2Тп + 1Г / 2 + со tip.

i.e., for example, when the phase difference meter 940 measures a phase angle equal to (O, the phase difference meter 10 measures a phase angle equal to (pO, the phase difference meter 10 measures a phase angle equal to Cf 90. To determine the true the value of the phase angle and the corresponding position of the displacement, the phase shift Cf 90 is subtracted in block 11 of the reading.

Claims (1)

Invention Formula A device for measuring linear displacements containing stationary and mobile piezoelectric plates with counter-pin converters, a phase meter, a reading unit, connected in series the wave propagates in the piezoelectric plate 1. The surface acoustic wave is received by the counter-pin transducers 5 and 6. When moving the mobile piezoplate 4 relative to the fixed piezoplate 1, the phase difference meter 9, receiving signals from the generator 8 and the interdigital pin converter 5, measure the difference phases in between. The measured phase difference is proportional to the distance between the counter-pin converters 2 and 5 and corresponds to the measured displacement, which is determined by the reading unit 11, which continuously determines the value of the phase angle and compares it with the specified reference angle. the angle close to the phase angle of the dead zone, the reading unit 11 switches to the operation of the counter-pin converter 6. Since the counter-pin converter 6 is located relative to the counter-pin transducer 5 is at a certain distance, i.e. on / 4, the signal taken from it and measured by the meter 10 the phase difference is shifted by 12 relative to the signal from the counter-pinner 5 and the phase difference measured by Lem 9. So the measured phase angle and 10 phase difference will be equal to I I Ф 2Тп + 1Г / 2 + со tip. i.e., for example, when the phase difference meter 9 measures a phase angle equal to (O, the phase difference meter 10 measures a phase angle equal to (p O, the phase difference meter 10 measures a phase angle equal to Cf 90. To determine the true value the phase angle and the corresponding position of the displacement; the phase shift Cf 90 is subtracted in block 11 of the reading. Invention Formula A device for measuring linear displacements containing stationary and mobile piezoelectric plates with counter-pin converters, a phase meter, a reading unit, connected in series with the output of the counter-pin converter on the mobile piezoelectric plate, and the generator, the output of which is connected to the counter-pin converter on the fixed piezoelectric plate and with the second input of the phase meter, characterized in that Editor N.Gorvat Compiled by G.Fyodorov Tehred L.Oleynik Proofreader O.Lugov Order 5214/36 Circulation 670 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 equipped with a third interdigital transducer located on a movable plate at a distance of a quarter of the wavelength from another transducer, and a second phase meter, the inputs of which are connected to the generator and the third interdigital transducer, and the output to the readout unit.