SU924629A1 - Device for measuring piezoceramic transitional characteristic - Google Patents

Description

(St) DEVICE FOR MEASURING THE TRANSITION CHARACTERISTICS OF A PIE-CERAMICS PLAYER

I

The invention relates to a measurement technique and can be used to measure the dynamic parameters of piezoceramic transducers. .

A device for measuring the dynamic parameters of piezoceramics, which contains a pulse generator connected in series, a piezotransducer under study, an interference compensation device, an amplifier and an oscilloscope, is known. The compensation of the exciting pulse (HI) is realized by the voltage of the opposite polarity. In this device, on the signal of the reaction (CP) there are usually impulses of the fronts of PI due to their incomplete compensation, leading to a distortion of the CP. In this case, the compensation of the VI is carried out individually for each sample of the piezoceramics due to possible variations in its capacitance t1.

The disadvantage of this device is the small amplitude of the CP due to

damping of oscillations of piezoelectric ceramics by the output resistance of a torus generator. Damping begins already at the back of the VI due to the smooth approach of the voltage on the piezoceramics to zero. After termination of the VI when registering the CP, the small output impedance of the pulse generator shunts the capacitance of the piezoelectric ceramics and thereby reduces the amplitude of the CP and introduces

10 attenuation, i.e. distorts information about the form of CP. In addition, the separation capacitance at the input of the CP amplifiers prevents the passage of the aperiodic component of the CP.

15

A device for measuring the electrophysical characteristics of piezoelectric ceramics is known, which contains a test signal source, a frequency indicator switch, an amplitude sensor, an amplitude and quality transducer, a divider and an extremizer 123. 392 A disadvantage of the known device is the low noise immunity of the piezoceramic ceramics signal. The purpose of the invention is to reduce the effect of interference on the response signal of piezoelectric ceramics. The goal is achieved in that the device containing the test signal source connected to the input of the switch, the first output of which is connected to one of the input terminals of the device, and the indicator, has a key, a threshold amplifier, an adjustable voltage divider and a voltage follower, at 5

This second switch output is connected to one of the inputs of the threshold amplifier, the second input of which is connected via an adjustable voltage divider to the indicator input and to the output of a voltage follower, the input of which is connected to the input terminal and the first output of the switch, the second output of which is connected to the second input terminal of the device, and the key input is connected to the output of the threshold amplifier.

Fig. 1 shows a block diagram of the device; Fig. 2 is an electrical functional diagram; Fig. 3 is a schematic electrical scheme;

The device contains a switch 2, 1 Bezoceramics 3, a voltage follower k, an oscilloscope 5, a threshold amplifier b, a switch 7, equipped with a current limiter, an adjustable voltage divider 8, and the input terminals 9 and 10 of the device. The device works as follows.

Consider the operation of the device under the simplified scheme (). When the switch 2 is not pressed, the piezoelectric ceramics are charged before the voltage of source 1 and the key 7 is open. When you press button 2, source 1 is disconnected from the piezoelectric ceramics and a voltage is applied to the first input of the threshold amplifier, which causes voltage on its output, which opens the key 7 and the piezoelectric ceramics starts to quickly discharge. The voltage on the piezoceramics 3 and. at the output of the repeater k at the same time, As soon as the voltage at the output of the repeater reaches zero, the threshold amplifier 6 and the key 7 are triggered

Fits the impedance of the connecting wires and the key.

In the proposed device there are no separation tanks in the CP channel. The slope of the differential voltage on the piezoceramics is great. During CP registration, piezoelectric ceramics are not shunted by the resistances of the instruments. This allows, first, to get

without loss of information, undistorted CP, including from the aperiodic component, and secondly, to have a sharply increased amplitude in the analysis. CP, which allows us to explore CP without

additional gain.

Thus, on controlled samples when adjusting the gas laser mirrors, the initial amplitude of the oscillations of the SL is close to the value of the excitation voltage across the piezoceramics (in known analogues, the amplitudes of the VI and the CP differ by two to three times). The advantage of the proposed device is the lack of powerful

source of excitation pulse voltage and a small amount of elements used.

Claims (2)

1. Industrial Electronics, 1979, If 2, p. 189. 2. USSR author's certificate 1 Jr l fI I