SU1257573A1 - Device for measuring frequencies of minimum and maximum impedances of piezoelectric vibrators - Google Patents

Abstract

The invention relates to electrical measurements and can be used to automatically control the frequencies of piezoelectric resonators. The purpose of the invention is to improve the accuracy of the measurement. The device contains a generator 1 controlled by a voltage, a resistive quadrupole 2 for connecting the piezoelectric resonator under investigation, a frequency meter 4, the first amplitude detector 9. The goal is achieved by introducing Cvum de / V A lll. rr, f3 cvuftt. fZ} 4C. ifi

Description

3 frequencies for two, control unit 5, switch 6, measurement channels 7 and 8. At the same time, measurement channel 7 contains extremizers 11 and 12 and the first element OR 15, and measurement channel 8 contains amplifier 17, amplitude detector 10, shift unit 1B

The invention relates to electrical measurements and can be used to automatically control the frequencies of piezoelectric resonators.

The purpose of the invention is to improve the measurement accuracy.

Figure 1 shows the functional diagonal circuit of the proposed device, figure 2 shows the time diagrams of its operation,

The device contains a generator 1 controlled by voltage, a resistive measuring quadrupole 2 for connecting a controlled piezoelectric resonator (PED), a divider 3 frequencies into two, a frequency meter 4, a control unit 5, a switch 6 channels, the first and second channels 7 and 8 measurements, the first and second amplitude detectors 9 and 10, the first, second, third, fourth extremators 11-14, the first and second elements OR 15 and 16, the amplifier 17, the voltage level shift unit 18

The first output of control unit 5 is connected to the input of generator 1, controlled by voltage, the output of which is connected to the input of resistive quadrupole 2 and the input of frequency divider 3 to two, the output of which is connected to information input of frequency meter 4, the external start input is connected to output of switch 6 , the first input of which is connected to the output of the first measurement channel 7 and the second input to the output of the second measurement channel 8. The outputs of the control unit 5 are connected respectively: the second output is with the first inputs of channels 7 and B of measurement, the third output is connected with the second inputs of channels 7 and 8 of measurement, the fourth output, with the third inputs of channels 7 and 8 of measurement, n

voltage level, extremators 13 and 14 and the element OR 16. The device provides a double measurement in the field of extremum of piezoelectric resonators with increasing and decreasing frequencies. 2 h. item f-ly, 2 ill. .

0

50

0

the fifth output is with the fourth inputs of the measurement channels 7 and B, the fifth inputs of which are connected respectively to the output of the first amplitude detector 9 and the output of a resistive quadrupole 2, which is connected to the input of the first amplitude detector 9. In the first channel 7 measure 1 and the outputs of the first and second extrementers t1 and 12 are connected to the inputs of the first element OR 15, the output of which is the output of the first measurement channel 7. The first, second, third and fourth inputs of the first measurement channel 7 are respectively the recording input of the first kstrematora 11, the second input of the recording ekstrematora 12, entry readout ekstrematora first 11 and the second input of the read ekstrematora 12 A fifth input of the first measuring channel 7 are connected to data inputs of the first -and second extremal tori 11 and 12.

I -.

In the second measurement channel 8, amplifier 17 is connected in series; the second amplitude detector tO and the voltage level shift unit 18, the outputs of which are connected to the informational inputs of the third and fourth extremators 13 and 14, the outputs of which are connected to the inputs of the second element OR 16, the output of which is the output of the second measurement channel 8. The first, second, third, fourth, and fifth outputs of the second measurement channel 8 are respectively: the recording input of the third extremizer-13, the recording input of the fourth extremer 14, the read input of the third extremer 13, the input of the fourth extremum 14 and the second altimeter detector ten.

31

The device works as follows.

The control unit 5 controls the sawtooth voltage of the frequency of the oscillator 1. At the same time, the frequency of the oscillator 1 varies smoothly over the pitch range. In one cycle of operation of the device, four pumpings are carried out over the range of FIG. 2a).

At the output of the quadrupole 2, the amplitude-frequency characteristic (A.h.h.) of the measured PED (Fig. 2b), which is analyzed by channels at extreme points, is formed four times. Channel 7 is used to detect the frequencies of the maximum of the four-pole signal, channel 8 is for selection of frequencies of the minimum signal.

The amplitude detector 9 of channel 7 highlights the envelope of the positive values of the output voltage of the quadrupole. At the same time, at the output of the detector 9, an abcd is formed full. measured PED (FIG. 2B), which, if necessary, can be viewed on an oscillographic indicator.

In channel 8, a pre-conversion of the signals by mi shm is carried out. PED in maximum signals. For this purpose, the PER output signal is amplified by amplifier 17 and detected by an amplitude detector 10. Amplifier 17 is used to increase the sensitivity in signal areas close to zero and carrying useful information. At the output of the detector 10, a negative envelope of the PER output signal is formed (Fig. 2), which is fed to the input of the voltage level shift unit 18 in the positive voltage range. At the output of the level shifting unit 18, an extremum-maximum is formed (Fig. 29), corresponding to the minimum values of the IED output signal (Fig. 2b, 3).

Extremers 11–14 memorize the maximum values of the input signal and, when repeated, form an output pulse corresponding to an extremum — maximum.

To reduce the maximum selection error in the device, two extremators are used in each channel (extremators 11, 12 in channel 7 and 13, 14 in channel 8).

 Timing diagrams of write and read start sequences

734

information by the extremes 11-14 submission, n (fig.2e-m). When the generator frequency 1 is first pumped over the frequency range, extremators 11 and 13 are commanded by the control unit 5 (Fig. 2e), and reading information from them is actual during the third pumping (Fig. 2). In this case, the maximum pulses are formed in channel 7 at time tj (figure 2 and), and in channel 8 - at time t (figure 2).

For the period of the second pumping of the generator 1 over the frequency range, the recording of the extremators 12 and 14 (Fig. 2k) is started, and the information is read from them during the fourth pumping (Fig. 2A). In this case, the maximum impuing points are formed in channel 7 at the time (Fig. 2 l), and in channel 8 - at time t (Fig. 2m).

The maxima pulses of channel 7 are summed by the element OR 15 at times t and tj, corresponding to the maximum iiiiiM values of the PER output signal, and through the switch 6 channels arrive at the external trigger input of the frequency meter 4, the counting input of which receives a sinusoidal signal from the generator 1 output through a divider 3 frequencies into two.

For two starts (from two pulses of the maximum of channel 7), the frequency meter 4 two times calculates the two halves of the generator frequency. The resulting count is

with

 . 4-f

i.

Since there is always an extremum error in the formation of the moment of extremum-maximum extremum (Fig. 26), point A for the third direct pumping and point B for the fourth reverse pumping is always below the true maximum. Moreover, this error depends on the irregularity of the PER maximum, i.e., on its multiple extremes, which is often encountered, the leading edge of the maximum output pulse always comes just before the true maximum.

However, the use of two extremes 11 and 12 in channel 7: one for direct pumping, and the second for reverse pumping over the frequency range, allows to form positive and negative errors of fixing the maximum relative to the true maximum. In this case, the frequency meter will fix two frequencies that are mixed on either side of the true maximum frequency, but the total average frequency will be exactly equal to the true maximum frequency if the extremum errors are the same or close to it. Due to this, instrumental errors are subtracted, as a result of which the accuracy of measuring the frequency of the maximum PEP signal is greatly increased.

When measuring the frequency of the minimum PEP signal, the 6 channel selector switch | switches to the output of channel 8 and frequency meter 4 similarly measures the frequency of the PER output signal.

Thus, improving the accuracy of measuring the frequencies of the minimum and maximum impedances of PER provides a double measurement in the extremum region with increasing and decreasing cha-jq this first, second, third, and par.

Claims (3)

1. An apparatus for measuring the frequencies of minimum and maximum impedances of piezoelectric resonators, comprising a frequency meter and a series-connected voltage controlled oscillator, a resistive quadrupole for connecting a controlled piezoelectric resonator and a first amplitude detector, with with a precision measurement step, a frequency divider by two, a control unit, the first and second measurement channels and a switch, the first input of which is connected to the output of the first the second input is connected to the generator input controlled by the voltage, the second output of the control unit is connected to the first inputs of the first and second measurement channels, the third output of the control unit is connected to the second inputs of the first and second measurement channels, the fourth output of the control unit is connected to the third inputs of the first and second measurement channels, the fifth output of the control unit is connected to the fourth inputs of the first and second channels measurements, the fifth outputs of which are connected respectively to the output of the first amplitude detector and the resistive quadrupole, and the output of the switch is connected to the external trigger input of the frequency meter, the information input of which is connected to the output of the frequency divider by two, the input of which is connected to the output generator driven voltage.  2. YcTpoiiCTBO according to claim 1, stating that the first measurement channel contains the first and second accelerators and the first OR element, the output of which is the output of the first measurement channel, and the two inputs are connected respectively to the outputs of the first and second extremators, with The aperture inputs of the first measurement channel are, respectively, the recording input of the first extremator, the recording input of the BTopoi o accelerator, the read input of the first extremator, the read input of the second extremator, and the fifth input of the first measurement channel are the connected inputs of the first second extremer. and 3. The device according to claim 1, wherein the measurement channel BTopoj i contains the third and fourth 1st extremators, the second OR element and consistently connected second amplitude detector, amplifier and a unit for shifting the voltage level, the output of which is connected to the information inputs of the third and fourth extremators, whose outputs are soy; corresponding to the first and second inputs of the second OR element, the output of which is the output of the second measurement channel, the first, second, the third and fourth inputs of the second channel rhenium are respectively input recording ekstrematora third, fourth ekstrematora record entry, entry readout zkstrematora third and fourth input read ekstrematora, and a fifth input of the second measuring channel: is the input of the second amplitude detector. 4cfCfT7afr7oL acmamcL antirez. sgsgtta / gta. reason /. Record 9ffcrpeM. A b Count 3tfcrpeM. AS ... / p Btffx 3ff streamer / 5 3 Bh / x. 3f (cT-repair ff and Record H Enstrom. CvLfm emsgl rem. f2. /. . emst m rem. /four ve, / x. 3ffCT-H rem. Z fn2 fg / f 4-Lfg Editor M.Kelemes Compiled by S. Lebedev Tehred L.Oleye iKorrektor M.Maksimishinets Order 49i4 / 44 Circulation 728 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, st. Project, 4