SU757865A1 - Device for testing piezotransducer operability - Google Patents

Description

The invention relates to a vibration measuring technique, in particular for studying the performance of piezo transducers and vibration shock accelerations. five

A device is known for testing the operability of piezoelectric transducers, containing a series-connected electrical pulse generator and a response selection circuit, connected by the U input to the checked piezoelectric transducer, and a spectrum analyzer [1].

The disadvantage of this device is low sensitivity due to the presence of pulsed. 15

interference from response selection circuits and from an electric pulse generator.

The purpose of the invention is to increase the sensitivity,

.. This goal is achieved by the fact that the device is equipped with a series-connected pulse shaper connected to the second output of the electric pulse generator, and a second selection circuit, with a differential 2-5 differential adder connected! inputs to the outputs of the first and second selection schemes, respectively, and the output to the spectrum analyzer and a capacitor connected to the output of the form-30

2

pulse generator, the capacity of which is equivalent to the input capacitance of the piezo transducer under test and its input cable.

The drawing shows a block diagram of the device.

A device for testing the performance of piezo transducers contains connected in series. an electric pulse generator 1 and a response selection circuit 2, connected by an input to a piezo transducer under test 3, a spectrum analyzer 4 serially connected pulse generator 5 connected to the second output of an electric pulse generator, and a second 6 sectional circuit, a differential adder 7 connected by inputs the outputs of the first and second selection schemes, and the output to the spectrum analyzer, and the capacitor 8 connected to the output of the pulse shaper, whose capacitance is equivalent to the input capacitance verifiable and peeopreobrazovatelya ego.vhodnogo cable 9.

The device works as follows.

Impulses generated by the generator

1 electric pulses served

3

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on the piezo former 3, where, due to the inverse piezoelectric effect, they are transformed into short-term pulses of mechanical effort, causing the elements of the transducer structure to oscillate. . Electrical impulses are also present * at the circuit input. 2 selections. The duration and repetition period of the excitation pulses are selected in accordance with the dynamic properties of the controlled piezoelectric transducer? ’Θ L, and as a criterion for selecting the pulse duration is the maximum allowable value of the error in determining the frequency response of the converter, for the repetition period, the time for reducing the amplitude of the response to a given level relative to the maximum.

If a controlled piezoelectric transform (the body is attached to the object, then 20

the area of the object directly adjacent to the surface of fastening. converter. Mechanical oscillations due to the direct piezoelectric effect are converted into an electrical signal (response) present at the input of the circuit 2 of selek ^ and during the pause between the excitation pulses. The pulse shaper 5 generates pulses, amplitude, efficiency and repetition period of which coincides with similar characteristics of the excitation pulses. As a pulse shaper, an amplifier is used that is similar to the output amplifier of the generator 1 of the electrical im-’·’ pulses, and the synchronizing voltage for it is taken from the output of the pre-final cascade. The capacity of the piezodrive 3 together with the capacity of the cable shunts, the generator output 1, 40

distorting the shape of the excitation pulse.

Exactly the same distortion should be at the output signal of the driver)

5 pulses, for which its output is shunted by a capacitor 8. Thus, there is a voltage at the output of the second selection circuit 6,

the parameters of which coincide with the parameters of voltage interference. In differential adder 7 is ON, 'gp

interference compensation. As the h of the adder, you can use any \

balanced amplifier having a frequency response that is uniform in the range of determining the frequency response of a controlled piezoelectric transducer.

The amplitude of the interference from the sawtooth pulse decreases by a larger number of times, and the amplitudes of two short pulses by a smaller number of times. This difference in the results of compensating for both types of interference is due to the fact

) that long-duration smooth pulses are easier to compensate for, than short peaked ones. Incomplete compensation is mainly due to the instability of the parameters of individual units of the device.

The device can be used to control piezo transducers in the process of their production, as well as to periodically check during operation.

Claims (1)

Claim A device for testing the operability of piezoelectric transducers, containing a series-connected electric pulse generator and a response selection circuit, linked. an input with a tested piezoelectric transducer, and a spectrum analyzer, which is designed to increase sensitivity, it is equipped with a series-connected pulse generator connected to the second output of the electric pulse generator, and the second selection circuit, a differential the adder connected by the inputs <respectively to the outputs of the first and second selection schemes, and the output to the spectrum analyzer and a capacitor connected to the output of the pulse shaper, whose capacitance is equivalent to the input capacitor the bones of the piezo transducer under test and its input cable.