SU767661A1 - Device for measuring resonance and antiresonance frequencies of piezoceramic resonators - Google Patents

Description

(54) DEVICE OF FREQUENCIES FOR MEASUREMENT OF RESONANT AND ANTI-RESONANCE PIEZO-CERAMIC RESONATORS

     one . The invention relates to a measurement technique, in particular to measurements of parameters of piezoelectric resonators, and can be used in the electronics industry for as- thematically controlling the parameters of such resonators.

There are known devices for measuring resonant and antiresonant frequencies, containing harmonic oscillator with electronic frequency tuning element, resistive quadrupole with a measured resonator, which is a balanced discriminator of a variable voltage converter into a constant, operational amplifier and .RC. - chain. i The disadvantage of the known device is low speed.

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Of the known devices, the closest in technical essence of the present invention is a device comprising a harmonic oscillator, a quadruple with a measured resonator, a phase detector, a DC amplifier, and a frequency meter 2.

The disadvantage of this device is its quick response.

The purpose of the invention is to increase speed.

This is achieved by the fact that a device containing a series-connected harmonic oscillator, a quadrupole with a measured resonator, a phase detector and a DC amplifier, and a frequency meter, whose input is connected to the second output of a harmonic oscillator, and the second voltage input of the phase detector is connected to to the output of a harmonic oscillator, a serially connected differentiator, comparator, RS-trigger, a linear-varying voltage generator and a commutator, a second input cat cerned Connected to the output of the DC amplifier, the third switch is connected to .The inputs You are a. G move the 5-flip-flop, and the switch output. podklk cheI to the input of the generator of harmonic oscillations.

FIG. 1 shows a block diagram of the proposed device; Fig.2 timing diagram of the device.

The device contains a harmonic oscillator 1, a quadrupole 2 with a measured resonator, a phase detector 3, a differentiator 4,

comparator 5, DC amplifier 6, switch 7, RS-trigger 8, generator 9 linear varying voltage (LIN) frequency counter 10.

The device works as follows.

The search is based on the properties of the phase-frequency characteristics of the piezoelectric resonator. At resonance, there is a sharp phase shift from + P / 2 to -II / 2. In the resonant gap, the phase rotation remains equal to -P / 2 and, on the anti-resonance, a sharp rotation from -P / 2 to + P / 2. On the side modes, a smaller phase rotation is achieved, after differentiation of the characteristic, opposite polarity pulses are produced at the resonance and antresonance frequencies. On the side modes, the pulses have a smaller amplitude. This makes it possible to easily isolate useful impulses at the frequencies of the resonance and anti-resonance of the fundamental mode using comparators with non-zero thresholds.

In the initial state, the RS-flip-flop 8 is in the zero position, the LIN generator does not work, the electronic switch 7 is in the position 2. On the Start command, the RS-flip-flop 8 goes into a single position. The electronic switch 7 is transferred to position 1, the LIN generator, through the electronic switch 7, starts pumping generator 1 over the frequency range containing the resonance and antiresonance of the main mode. The pumping continues until the differentiated voltage exceeds a predetermined threshold, i.e. frequency of oscillator 1 will become close to non-resonance. The exact frequency of the fundamental mode of the resonator. The signal from the output of comparator 5 sets the RS flip-flop 8 to the zero state, and the electronic switch 7 is switched to position 2, as a result, the output of the phase detector 3 through the d amplifier is connected to the electronic frequency control element of the oscillator 1. Precise tracking of the resonant occurs. frequency of the system of phase automatic tuning of the frequency of the oscillator 1. After achieving precise tuning to the resonance frequency of the main mode, it is measured by its frequency meter 10. Similarly, are measurement antiresonant frequency of the fundamental mode.

Claims (2)

1. USSR author's certificate No. 414544, cl. G 01 T 23/12, 19.07.72. 2. USSR author's certificate No. 214666, cl. C, 01 Tg 23/12, 20.0167. I / and f l