SU756318A1 - Device for tolerance checking of piezoelectric resonators - Google Patents

Description

The invention relates to radio engineering, in particular to measuring devices for automatic tolerance control piezoelectric resonators.

The automatic tolerance control device of piezoelectric resonators is known, which provides automatic tolerance control of the differential quality factor of piezoelectric resonators by the level of differential (side) resonators by measuring the absolute values of the maximum values (11 ^) and the minimum (and _g ) of additional values of the maximum values (Y) and minimum (and _d ) additional resonance. The relative value ^ / (^ is compared with the predetermined trigger threshold of the comparator [1].

A disadvantage of this device is the inability to conduct a percentage tolerance control due to the fact that two of the same sign-. The amplitudes of the differential resonance 4ί = II- and ₂ , located below or above the amplitude-frequency characteristic (AFC) of the resonator, correspond to different values of the ratio and ₁ ! I) ₂ sequentially,

2

Different response thresholds are required for resonator screening.

Another disadvantage of the known device is the possibility of a false 5 response in the presence of even very small differential resonances on the back slope of the frequency response.

The purpose of the invention is to increase the resolution and expansion of 10 functionality.

This goal is achieved by the fact that the device _ control of piezoelectric resonators, containing in series 15 connected voltage controlled oscillator, resistive quadrupole for connecting the measured resonator, matching amplifier, amplitude and peak detectors and 20 comparison unit, is additionally equipped with an analog adder, a second peak detector, control unit. and a logic element, with the output of the amplitude detector connected to the 25th input of the control unit, the input of the second peak detector and the first input of the analog adder, the output of which is connected to the second input of the comparison circuit, the output of the second pico 3® of the second detector

the sistor is connected to the second input of the analog adder, the outputs of the control unit are connected respectively to the generator and the first input of the logic element, and the second input of the logic element is connected to the output of the comparison circuit.

FIG. 1 is a block diagram of the device, * in FIG. 2 - typical frequency response of the resonator (solid line), voltage at the output of the peak detector (dotted line), voltage at the output of the analog adder (dash-dotted line) ‘in FIG. 3 - timing charts of the device.

The device contains a voltage-controlled harmonic oscillator 1, a resistive quadrupole 2 with the resonator under test, a matching amplifier 3, an amplitude detector 4, a peak detector 5, a comparison unit 6, an analog adder 7, a peak detector 8, a control unit 9 and a logic element 10 having information output 11, a variable resistor 12 to set a given level of screening. ·

In the initial state, the voltage at the input of the generator is zero. The frequency of the generator is minimal.

When applying the command ^Λ Reset "the voltage at the input of the generator, and hence its frequency, begins to increase smoothly. The output voltage of the amplitude detector is fed to the inputs of two peak detectors 5 and 8, to the input of the analog adder and to the control unit 9. At the outputs of peak detectors after frequency deviation over the entire frequency range, extreme values of the voltage at the output of the amplitude BP detector are remembered. ^ Thus, at least one frequency deviation of the frequency is required for normal operation of the device -frequency range. After that, start working work cycles.

When the frequency is changed again (Fig. 3a), the output of the analog adder produces the sum of the current value of the BP voltage and a certain fraction of the memorized voltage (Fig. 3B, solid line). The voltage of the peak detector 5 (Fig. 3B, point-. Dash) is reset at the beginning and end of the frequency range by the signal "Reset"

(fig. Sv). The control unit generates the enabling signal from the command "Reset" to the maximum frequency response (Fig. Zg). The voltage at the output of the comparison circuit (Fig. Zd) is fed to the input of the logic element. The signal from the output of the logic element blocks possible false positives of the comparison circuit on the back slope of the frequency response. To analyze the back slope of the frequency response, the procedure is repeated, and the frequency changes, in this case from higher to lower. In this case, the rear slope of the frequency response will be the front and vice versa. Thus, the device is triggered when there is a differential resonator that exceeds the specified maximum frequency response level located on any slope of the frequency response. The specified level of grading is set by resistor 12.

Claims (1)

Claim The device tolerance control of piezoelectric resonators, containing a series-connected voltage controlled oscillator, resistive quadrupole for connecting the measured resonator, torus, matching amplifier, amplitude and peak detectors, and a comparison circuit, characterized in that, in order to increase the resolution and enhance functionality, it is additionally equipped with an analog adder, a second peak detector, a control unit and a logic element, with the output amplitude The detector is connected to the input of the control unit, the input of the second peak detector and the first analog input, the adder, the output of which is connected to the second input of the comparator, the output of the second peak detector is connected via a variable resistor to the second input of the analog adder, and the outputs of the control unit are connected respectively to the generator and with the first input of the logic element, and the second input of the logic element is connected to the output of the comparison unit.