JPH0829181A - Vibration control apparatus - Google Patents

Abstract

PURPOSE:To provide a vibration control apparatus which can realize a stable self-oscillation without an amplitude change to a change of a surrounding temperature and eliminate a temperature dependency of a detecting sensitivity upon an input angular velocity thereby to enhance a detecting accuracy when applied to a vibration gyro. CONSTITUTION:A vibrator 4 has a substantial pair of piezoelectric elements 2 and 3 at a side face of a vibrator with a resonant, point. The vibration control apparatus makes the vibrator 4 self-oscillate, and is provided with a driving device 60. The driving device 60 has a driving signal output circuit 29 a voltage gain of which shows a temperature dependency corresponding to a temperature dependency of an equivalent resistance of the vibrator 4, and an automatic gain control circuit, 28 which maintains constant a resultant current value of currents passing the substantial pair of piezoelectric elements 2 and 3.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration control device used in, for example, a piezoelectric vibration gyro, and more particularly to a vibration control device having stable angular velocity detection sensitivity in a wide temperature range.

[0002]

2. Description of the Related Art As a conventional vibrating gyroscope, for example,
There is one as shown in FIG. In this vibrating gyro, the piezoelectric elements 2 and 3 forming the vibrator 4 are connected to the output side of the driving device 6 via impedance elements Z ₁ and Z ₂ , respectively, and the output side of the driving device 6 is further connected. The capacitor C is also connected via another impedance Z _{3 so} that the driving voltage from the driving device 6 is simultaneously applied to the piezoelectric elements 2 and 3 and the capacitor C.

The outputs at the connection points of the impedance elements Z ₁ and Z ₂ and the piezoelectric elements 2 and 3 are combined, and the combined output and the output at the connection point of the impedance element Z ₃ and the capacitive element C are combined. By supplying the differential output to the differential amplifier 7 and feeding back the differential output to the driving device 6, the vibrator 4 is caused to self-oscillate, and further, these impedance elements Z ₁ and Z ₂ and the piezoelectric elements 2 and 3 are connected. The outputs at the respective connection points are supplied to the other differential amplifier 8 so that the angular velocity detection signal is obtained based on the output of the differential amplifier 8.

Here, for example, as shown in FIG. 14, the vibrator 4 has a quadrangular cross section, and the piezoelectric element 2 is adjacent to one side surface 1a of the vibrating body 1 having a resonance point. The piezoelectric element 3 is formed on each of the other side surfaces 1b, and the piezoelectric elements 2 and 3 are formed on the same side surface of the vibrating body 1 in the width direction as shown in FIG.
1, the piezoelectric elements 2 and 3 are formed on the opposite side surfaces of the vibrating body 1 so as to be displaced in the width direction, or
As shown in FIG. 7, piezoelectric elements 2a and 2b are formed and connected in parallel so that they substantially act as one piezoelectric element 2 on the opposite side surfaces of the vibrating body 1, and
Piezoelectric elements 3a and 3b are formed and connected in parallel so that they substantially act as one piezoelectric element 3 on the other opposing side surfaces.

Further, as another vibrator 4, as shown in FIG. 18, one having piezoelectric elements 2 and 3 formed on two side surfaces of a vibrating body 1 having a triangular cross section and having a resonance point, As shown in FIG. 19, on the side surface of a vibrating body having various cross-sectional shapes, such as one in which the piezoelectric elements 2 and 3 are formed on the circumferential side surface of the vibrating body 1 having a circular cross-sectional shape and having a resonance point. Substantially two piezoelectric elements are used.

The vibrator 4 illustrated in FIGS. 14 to 19 has a damping capacitance Cd in a series resonance circuit of a coil L1, a capacitor C1 and a resistor R1 for one piezoelectric element, as shown in the equivalent circuit of FIG. It is represented as a parallel resonant circuit connected in parallel. Note that, here, as illustrated in FIGS. 14 to 19, the vibrator 4 formed by substantially forming the two piezoelectric elements 2 and 3 on the vibrating body 1 is represented as shown in FIG. 21. .

In the conventional vibrating gyro shown in FIG. 13, the drive signal from the drive device 6 is applied to the impedance element Z.
_Since it is applied to the piezoelectric elements 2 and 3 via ₁ and Z ₂ ,
When the impedance of the piezoelectric elements 2 and 3 decreases near the mechanical series resonance frequency fs of the vibrator 4, the signal level applied to the piezoelectric elements 2 and 3 decreases and the output of the differential amplifier 7 becomes maximum. There is a problem that the frequency and the mechanical series resonance frequency fs of the vibrator 4 do not match.

In order to solve such a problem, the applicant of the present invention has filed Japanese Patent Application Nos. 6-2364 and 6-10348.
No. 6, the oscillator can vibrate and self-excitate stably at the frequency set to the mechanical series resonance frequency fs, and when applied to a vibration gyro, the generation and fluctuation of null voltage can be effectively reduced. A control device has already been proposed.

FIG. 22 shows an example of the configuration of the vibration control device proposed by the applicant. This vibration control device forms substantially two piezoelectric elements 2 and 3 on the side surface of a vibrator 4 as shown in FIGS. 14 to 19, that is, a vibrator 1 having various cross-sectional shapes having resonance points. The vibration of the vibrator 4 is controlled. In FIG. 22, the signal output terminal 9 of the driving device 6 has a feedback resistor Rf.
Feedback amplifier 10L with _l and variable feedback resistor Rf
_The feedback amplifier 10R having _R is connected to the signal input terminals 11L and 11R, respectively.
The feedback input terminals 12L and 12R of L and 10R are respectively connected to one electrodes of the piezoelectric elements 2 and 3 to apply a drive signal.

The other electrodes of the piezoelectric elements 2 and 3 are connected to the compensation signal output terminal 13 of the driving device 6 for outputting the compensation signal of the braking capacity of the vibrator 4 via the capacitor Cc. The signal on the other electrode side of 3 and the compensation signal are combined. This combined signal is amplified by a summing amplifier 17, and the signal at its output terminal 18 is fed back to the input terminal 14 of the driving device 6 to cause the vibrator 4 to self-oscillate.

The output of the summing amplifier 17 and the drive signal at the signal output terminal 9 of the drive device 6 are supplied to the differential amplifier 22 for differential amplification, and the output of the differential amplifier 22 is changed to the variable resistor VR. To the feedback input terminals 12L and 12R of the feedback amplifiers 10L and 10R, and the feedback input terminals 12L and 12R correspond to current values flowing through the equivalent resistances of the piezoelectric elements 2 and 3 and their temperature dependence. By causing the currents that change in accordance with the characteristics to flow in and supplying the outputs of the feedback amplifiers 10L and 10R to the differential amplifier 20, the Coriolis force generated by the angular velocity acting on the oscillator 4 is detected as a voltage. I am trying to do it.

FIG. 23 shows an example of the configuration of the driving device 6 having the compensation signal output terminal 13 shown in FIG. This drive device 6 has a non-inverting amplifier 15 and an inverting amplifier 16, amplifies the signal from the input terminal 14 by the non-inverting amplifier 15, and supplies the output to the compensation signal output terminal 13 as a compensation signal. The signal is amplified by the inverting amplifier 16 and supplied to the signal output terminal 9 as a drive signal. That is, in the driving device 6, the phase of the drive signal supplied to the signal output terminal 9 and the phase of the compensation signal supplied to the compensation signal output terminal 13 are different by 180 °, and the amplitude ratio of these signals is inverted by an inverting amplifier. 16 is set appropriately.

According to the vibration control device shown in FIG. 22, of the current components flowing through the piezoelectric elements 2 and 3, the imaginary number component relating to each braking capacitance Cd is canceled by the compensation signal synthesized via the capacitor Cc. , Summing amplifier 1
The output of 7 is only the real number component of the current components flowing through the piezoelectric elements 2 and 3. Therefore, the voltage gain of the summing amplifier 17 becomes maximum at the mechanical series resonance frequency fs of the vibrator 4, so that the vibrator 4 is stably self-excited at a frequency exactly matching the mechanical series resonance frequency fs. Can be vibrated. Also, its mechanical series resonance frequency fs
The self-excited vibration can be further stabilized by using, as the capacitor Cc, one having a temperature dependence corresponding to the temperature dependence of the braking capacitance Cd of the vibrator 4.

[0014]

However, as a result of various studies by the present inventor, it was found that the vibration control device proposed by the applicant has the following points to be improved. That is, in the case of the above-mentioned vibrator 4, since the piezoelectric elements 2 and 3 themselves are substantially self-excited to vibrate without providing an independent piezoelectric element for obtaining the feedback output, The amplitude does not fluctuate due to the characteristic difference of the piezoelectric element itself as in the case where a feedback piezoelectric element for self-excited vibration is provided separately from the element. However, since the current passing through the pair of piezoelectric elements 2 and 3 forming the vibrator 4 is determined by the impedance of the vibrator 4, the equivalent resistance, the braking capacity, etc. of the vibrator 4 change due to the change of the ambient temperature. Then, it will change accordingly.

In the above-mentioned vibration control device, the fluctuation due to the temperature change of the braking capacity is compensated by the capacitor Cc, and the fluctuation due to the temperature change of the equivalent resistance causes the output of the differential amplifier 22 to pass through the variable resistor VR and the feedback amplifier 10L ,. Although the compensation is made by supplying the feedback input terminals 12L and 12R of 10R, it is difficult to completely compensate the fluctuations in such a configuration. For this reason, the amplitude of the self-excited vibration of the oscillator 4 fluctuates according to the reciprocal of the equivalent resistance or the like due to the temperature change, and accordingly, the input angular velocity in the direction orthogonal to the self-excited vibration direction corresponds. The amplitude of vibration may also fluctuate, the detection sensitivity may fluctuate, and the detection accuracy may decrease.

The present invention has been made by paying attention to the above points, and it is possible to perform stable self-excited vibration without amplitude fluctuation even when the ambient temperature changes. Therefore, when it is applied to a vibration gyro. Another object of the present invention is to provide a vibration control device appropriately configured to eliminate the temperature dependence of the detection sensitivity with respect to the input angular velocity and improve the detection accuracy.

[0017]

In order to achieve the above object, the first invention is a vibration control device for self-exciting a vibrator having a pair of piezoelectric elements substantially on the side surface of a vibrator having a resonance point. A drive signal output circuit which outputs a drive signal to be applied to the substantially pair of piezoelectric elements, and whose voltage gain has temperature dependency corresponding to the temperature dependency of the equivalent resistance of the vibrator, and the substantially pair of piezoelectric elements. The present invention is characterized by comprising a drive device having an automatic gain control circuit for maintaining a constant combined current value of respective currents passing through the element.

Further, the second invention is a vibration control device for self-oscillating a vibrator having substantially a pair of piezoelectric elements on a side surface of a vibrating body having a resonance point, which is applied to the substantially pair of piezoelectric elements. A drive signal output circuit that outputs a drive signal and has a voltage gain whose temperature dependence is opposite to the temperature dependence of the braking capacity of the vibrator, and among the respective currents that pass through the substantially pair of piezoelectric elements, The present invention is characterized by including a drive device having an automatic gain control circuit that maintains a constant combined current value of the currents obtained by subtracting the current corresponding to the braking capacity.

[0019]

[Operation] The current passing through the piezoelectric element forming the vibrator is
It changes with changes in the equivalent resistance value and the braking capacitance value of the vibrator. When a vibrator is self-excited to vibrate by a pair of piezoelectric elements themselves, a piezoelectric element for driving and a piezoelectric element for feedback, respectively, as in the case of self-exciting oscillation using separate piezoelectric elements for driving and feedback. Since the amplitude does not fluctuate due to the characteristic difference of the elements, the amplitude of the self-excited vibration of the vibrator fluctuates corresponding to the reciprocal of the equivalent resistance or the like. Also,
For example, when the angular velocity is also detected using the same pair of piezoelectric elements, the detection sensitivity corresponding to the angular velocity is determined by the magnitude of the vibration amplitude in the direction orthogonal to the self-excited vibration direction. However, the amplitude of the vibration in this case also fluctuates corresponding to the reciprocal of the equivalent resistance or the like. However, in this case, since the fluctuations of these vibrations are related to the substantially same pair of piezoelectric elements, if the amplitude in one direction is kept constant, the amplitude in the other direction orthogonal to the other is also kept constant. It will be. Therefore, if the equivalent resistance of the vibrator is controlled to be apparently constant, the detection sensitivity to the angular velocity can also be maintained constant.

In the first aspect of the invention, since the combined current value of the respective currents that substantially pass through the pair of piezoelectric elements is maintained constant by the automatic gain control circuit, stable self-excited vibration without amplitude fluctuation is performed. In addition, since the voltage gain of the drive signal output circuit that outputs the drive signal applied to the pair of piezoelectric elements has a temperature dependence corresponding to the temperature dependence of the equivalent resistance of the vibrator, the ambient temperature Even if the value changes, the change in the current flowing through the equivalent resistance of the vibrator is suppressed,
Therefore, the control range of the automatic gain control circuit is reduced and its operable range is substantially expanded.

According to the second aspect of the invention, of the currents passing through the pair of piezoelectric elements, the combined current value of the currents obtained by subtracting the current corresponding to the braking capacity, that is, the real number component of the combined currents, is automatically gained. Since it is maintained constant by the control circuit, similarly, it becomes possible to perform stable self-excited vibration without amplitude fluctuation, and at the same time, of the drive signal output circuit that outputs the drive signal applied to the pair of piezoelectric elements. Since the voltage gain has a temperature dependence that is contrary to the temperature dependence of the damping capacity of the vibrator, even if the ambient temperature changes, the change in the current flowing through the equivalent resistance of the vibrator is suppressed, and therefore, the automatic gain control circuit. The control range is reduced, and the operable range is substantially expanded.

That is, the temperature dependences of the equivalent resistance and the braking capacity of the vibrator generally have contradictory tendencies, as shown in FIG. 24, for example, so that they flow to the equivalent resistance side and the braking capacity side of the vibrator, respectively. The temperature dependence of the current value will have a similar tendency. Therefore, if the voltage gain of the drive signal output circuit has temperature dependence that is contrary to the temperature dependence of the braking capacity of the vibrator, the current flowing through the braking capacity side will always have the same amplitude as the current corresponding to the braking capacity. Moreover, since the temperature dependences of the current values flowing on the equivalent resistance side and the damping capacity side of the vibrator tend to be similar, changes in the current flowing through the equivalent resistance of the vibrator are suppressed, and therefore the automatic gain control circuit The control range is reduced and its operable range is substantially expanded.

[0023]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows an embodiment of the present invention, which is applied to a vibrating gyroscope for detecting an angular velocity. In this embodiment, substantially two piezoelectric elements 2 and 3 are formed on the side surface of a vibrator 4 as shown in FIGS. 14 to 19, that is, a vibrator 1 having various cross-sectional shapes having resonance points. The vibrator 4 is self-excited.

In FIG. 1, the signal output terminal 9 of the driving device 60 is the signal input terminal 1 of the feedback amplifiers 10L and 10R.
These feedback amplifiers 10 are connected to 1L and 11R, respectively.
The feedback input terminals 12L and 12R of the L and 10R are respectively connected to one electrodes of the piezoelectric elements 2 and 3. The other electrodes of the piezoelectric elements 2 and 3 are connected to the inverting input terminal side of a summing amplifier 17 having a feedback resistance Rfy, and its output terminal 1 is connected.
A voltage corresponding to the product of the combined current passing through the piezoelectric elements 2 and 3 and the feedback resistance Rfy is output to the output circuit 8, and the output voltage is applied to the input terminal 14 of the driving device 60 to drive the oscillator 4 by itself. Make it vibrate.

The outputs of the feedback amplifiers 10L and 10R are supplied to the differential amplifier 20 so that the Coriolis force generated by the angular velocity acting on the vibrator 4 is detected as a voltage. In addition, each feedback amplifier 10L, 10
R output side and corresponding feedback input terminals 12L, 12R
Feedback resistors Rf _L and Rf _R are connected to the respective sides.

FIG. 2 shows the structure of an example of the driving device shown in FIG. This drive device 60 has an automatic gain control circuit (hereinafter referred to as an AGC circuit) 28 and a drive signal output circuit 29. The AGC circuit 28 has a comparator 23 and an amplitude controller 24. The comparator 23 converts the input signal from the input terminal 14 into a direct current, compares it with a reference level, and generates a direct current signal according to the comparison result. And supplies it to the amplitude controller 24. The amplitude controller 24 is, for example, FE
The input signal from the input terminal 14 is supplied to the source / drain path of this FET, the output from the comparator 23 is supplied to the gate, and the input signal from the input terminal 14 is supplied based on the output of the comparator 23. The signal amplitude is controlled and output to the drive signal output circuit 29. It should be noted that the AGC circuit 28 is not limited to this example, and may be configured using, for example, an integrated multiplier or the like.

The drive signal output circuit 29 includes a non-inverting amplifier 2
5 and an inverting amplifier 26, and a signal whose amplitude is controlled by the amplitude controller 24 of the AGC circuit 28 is supplied to the non-inverting amplifier 25.
After being amplified to a predetermined size by, it is inverted by the inverting amplifier 26 and supplied to the signal output terminal 9. The inverting amplifier 26
Inverts the signal from the non-inverting amplifier 25.
In Japanese Patent Laid-Open No. -113336, as proposed by the applicant of the present application, the oscillator 4 is inserted in the positive feedback loop.

In this embodiment, the output of the drive signal output circuit 29 is changed according to the temperature dependence of the equivalent resistance of the vibrator 4. Therefore, the feedback resistance Rf of the inverting amplifier 26
₂₆ shows the temperature dependence of the equivalent resistance of the oscillator 4, for example, FIG.
A negative characteristic thermistor R _T having a temperature dependence corresponding to the temperature dependence of the equivalent resistance shown in FIG.

In this embodiment, when the equivalent resistance of each of the pair of piezoelectric elements 2 and 3 increases or decreases due to a change in ambient temperature, the piezoelectric elements 2 and 3 are correspondingly increased.
The current passing through it decreases or increases. This allows
The output of the comparator 23 decreases or rises, the resistance between the source and drain of the FET of the amplitude controller 24 increases or decreases, and the magnitude of the signal supplied to the inverting amplifier 26 is determined by the comparator 23. The input signal increases or decreases until it reaches a constant value corresponding to the reference level.

Further, when the current passing through the piezoelectric elements 2 and 3 is decreased or increased due to the change of the ambient temperature, the voltage gain of the inverting amplifier 26 is simultaneously changed to the negative characteristic thermistor R.
_Since the temperature dependence of _T increases or decreases, as a result, the amount of decrease or increase of the current flowing through the piezoelectric elements 2 and 3 is suppressed, and the amplitude change of the signal supplied to the input terminal 14 of the driving device 60 is low. It can be suppressed.

Therefore, the change in the output of the comparator 23 due to the temperature change becomes small, and the change amount of the resistance between the source and the drain of the FET of the amplitude controller 24 becomes small. As a result, the vibrator in the wide temperature range. Even when the equivalent resistance of No. 4 changes significantly, the change of the passing current is small, and the operable range of the AGC circuit 28 can be substantially expanded.

In this way, the output voltage of the summing amplifier 17, that is, the combined current passing through the piezoelectric elements 2 and 3 is maintained constant, so that the equivalent resistance of the oscillator 4 in the self-excited oscillation direction is Apparently constant. As a result, the equivalent resistance to the vibration of the vibrator 4 formed by the same piezoelectric element 2 and 3 in the sensitivity direction is apparently kept constant. It becomes constant regardless of changes in temperature, and high-precision detection is possible.

FIG. 3 shows a second embodiment of the present invention. In this embodiment, in the configuration shown in FIG. 1, the output at the output terminal 18 of the summing amplifier 17 is inverted and amplified by the inverting amplifier 19 to have the same phase as the drive signal, and this in-phase signal is fed back via the variable resistor VR. amplifiers 10L, 10R feedback input terminals 12L of supplies to 12R, feedback amplifiers 10L, 10R feedback resistance Rf _L of at least one of Rf _R, in this embodiment, a feedback resistor Rf _R with a variable feedback resistor It was done.

That is, in this embodiment, the variable resistance VR
Thus, the subtle difference in the equivalent resistance of the piezoelectric elements 2 and 3 is adjusted, and the current of the real number component corresponding to the current value flowing through the equivalent resistance of the respective piezoelectric elements 2 and 3 is fed back to the feedback input terminal 12.
L, 12R, so that the feedback resistors Rf _L , R
The current flowing through f _R is made equal to the current flowing through the braking capacity of the corresponding piezoelectric elements 2 and 3, respectively. Further, the variable feedback resistance Rf _{R is used} to adjust a subtle difference due to the braking capacity of the piezoelectric elements 2 and 3, and an imaginary component current corresponding to each current value flowing through the braking capacity of the piezoelectric elements 2 and 3, The respective products of the corresponding feedback resistance Rf _L and the variable feedback resistance Rf _R , that is, the voltages of the imaginary number components are made equal.

In this way, the feedback amplifiers 10L, 1
Since currents flowing in the 0R feedback input terminals 12L and 12R corresponding to the current values flowing through the equivalent resistances of the respective piezoelectric elements 2 and 3 and corresponding to the temperature dependence thereof, flow in. Feedback resistors R of the feedback amplifiers 10L and 10R
Only the current corresponding to the Coriolis force flows through f _l and Rf _R. Therefore, the feedback amplifiers 10L, 1
At 0R, the generation of null voltage can be effectively reduced, and the phase component corresponding to the input angular velocity can be effectively amplified. Therefore, in addition to the effect of the first embodiment, the angular velocity can be detected with higher accuracy.

FIG. 4 shows a third embodiment of the present invention. In this embodiment, in the configuration shown in FIG.
Instead of the driving device 60, a driving device 61 having a compensation signal output terminal 13 that outputs a compensation signal for the braking capacity of the vibrator 4
, And the compensation signal is combined with the signal on the other electrode side of the piezoelectric elements 2 and 3 via the capacitor Cc. The output of the summing amplifier 17 and the drive signal from the drive device 61 are supplied to the differential amplifier 22 for differential amplification, and the output is supplied to the feedback input terminals 12L and 12R via the variable resistor VR. To do. Other configurations are similar to those of the second embodiment.

FIG. 5 shows an example of the structure of the driving device 61 shown in FIG. The driving device 61 supplies the output of the non-inverting amplifier 25 of the driving signal output circuit 29 to the inverting amplifier 26 in the driving device 60 shown in FIG. 2 and also supplies it to the compensation signal output terminal 13 as a compensation signal. The other configuration is the same as that of FIG. That is, in the drive device 61, the drive signal output to the signal output terminal 9 and the compensation signal output terminal 13
The phase of the compensation signal output to the output signal is different from that of the compensation signal by 180 °, and their amplitude ratio is appropriately set by the inverting amplifier 26.

Here, the feedback resistor Rf ₂₆ of the inverting amplifier 26 is used.
Has a negative characteristic thermistor R _T having a temperature dependence that is opposite to the temperature dependence of the damping capacity of the vibrator 4, the output of the inverting amplifier 26 is contrary to the temperature dependence of the damping capacity of the vibrator 4. It will change. For example, the piezoelectric element 2,
When each braking capacity of 3 increases or decreases due to a change in ambient temperature, the current passing through the braking capacity side of the piezoelectric elements 2 and 3 increases or decreases accordingly, and at the same time,
The voltage gain of the inverting amplifier 26 decreases or increases. Therefore, the current passing through the braking capacity of the piezoelectric elements 2 and 3 is
The current supplied from the compensation signal output terminal 13 via the capacitor Cc becomes equal in magnitude and is canceled.

Further, since the temperature dependences of the current values passing through the equivalent resistance side and the damping capacity side of the vibrator 4 have similar tendencies, the increase amount or the decrease amount of the current passing through the equivalent resistance side is also the same. As a result, the amplitude change of the signal supplied to the input terminal 14 of the driving device 61 is suppressed to be low. Therefore, since the change in the output of the comparator 23 due to the temperature change becomes small, the change amount of the resistance between the source and the drain of the FET of the amplitude controller 24 becomes small, and as a result, the equivalent of the oscillator 4 in a wide temperature range. The change in the passing current becomes small even with a large change in resistance, and the AGC circuit 28 is substantially
The operable range of is expanded.

In this way, the output voltage of the summing amplifier 17, that is, the combined current value of the currents obtained by subtracting the current corresponding to the braking capacitance from the combined currents passing through the piezoelectric elements 2 and 3 is maintained constant. Therefore, the equivalent resistance of the vibrator 4 in the self-excited vibration direction is apparently kept constant. Further, since the imaginary number component of the current flowing through the piezoelectric elements 2 and 3 is effectively canceled by the compensation signal corresponding to the temperature dependency of the braking capacitance, the sensitivity direction of the vibrator 4 formed by the same piezoelectric element 2 and 3 is reduced. The equivalent resistance to the vibration of is also apparently kept constant.

Therefore, the voltage gain of the differential amplifier 17 becomes maximum at the mechanical series resonance frequency fs of the vibrator 4, and the vibrator 4 is stable at a frequency exactly matching the mechanical series resonance frequency fs. Since it is excited and oscillated, the detection sensitivity to the input angular velocity becomes constant regardless of the change in ambient temperature, which enables highly accurate detection.

FIG. 6 shows a fourth embodiment of the present invention. In this embodiment, in the configuration shown in FIG. 1, instead of the driving device 60, the compensation signal output terminal 13 shown in FIG.
The driving device 61 having the above is used, and its compensation signal is combined with the signal on the other electrode side of the piezoelectric elements 2 and 3 via the capacitor Cc. Other configurations are the same as in FIG.

Therefore, according to this embodiment, as in the third embodiment, the equivalent resistance to the vibration in the sensitivity direction of the vibrator 4 formed of the same piezoelectric elements 2 and 3 is apparently constant. Therefore, the detection sensitivity to the input angular velocity can be made constant, and the angular velocity can be detected with high accuracy, regardless of changes in the ambient temperature.

FIG. 7 shows a fifth embodiment of the present invention. In this embodiment, in place of the driving device 60 in the second embodiment shown in FIG. 3, a driving device 61 having the compensation signal output terminal 13 shown in FIG. 5 is used, and the compensation signal is passed through a capacitor Cc to generate a piezoelectric signal. It is configured to be combined with the signal on the other electrode side of the elements 2 and 3, and other configurations are the same as in FIG.

Therefore, according to this embodiment, in addition to the effect of the second embodiment, similarly to the third embodiment, the vibration of the vibrator 4 formed by the same piezoelectric elements 2 and 3 in the sensitivity direction is suppressed. As for the equivalent resistance, it can be apparently kept constant regardless of changes in ambient temperature.
The detection sensitivity to the input angular velocity can be made constant, and the angular velocity can be detected with higher accuracy.

FIG. 8 shows a sixth embodiment of the present invention. In this embodiment, in the configuration shown in FIG.
A summing amplifier 21 is used instead of the inverting amplifier 19, and the summing amplifier 21 synthesizes the output of the summing amplifier 17 and the compensation signal, and the output is fed back to the feedback amplifiers 10L and 10R through the variable resistor VR. It is configured to be supplied to the input terminals 12L and 12R for use, and other configurations are the same as those in FIG.

Therefore, according to this embodiment, as in the fifth embodiment, the equivalent resistance to vibration in the sensitivity direction of the vibrator 4 formed of the same piezoelectric elements 2 and 3 is also:
Since it can be apparently kept constant regardless of changes in the ambient temperature, the detection sensitivity to the input angular velocity can be kept constant. Also, the output of the summing amplifier 17 and the compensation signal are combined, and the combined signal is adjusted by the variable resistor VR to adjust the subtle difference in the equivalent resistance of the piezoelectric elements 2 and 3.
Since the feedback input terminals 12L and 12R are made to flow into the feedback input terminals 12L and 12R, the feedback input terminals 12L and 12R correspond to the current values flowing through the equivalent resistances of the respective piezoelectric elements 2 and 3 and have a temperature dependence. A correspondingly changing current will flow in. Therefore, the feedback amplifiers 10L and 10L
R feedback resistor Rf _l of the Rf _R, it means that only the current corresponding exactly to the Coriolis force flows, feedback amplifiers 10L, in 10R, the input angular velocity to reduce the occurrence of null voltage more effectively Amplifies the corresponding phase component,
Coupled with the above-mentioned constant detection sensitivity, the angular velocity can be detected with higher accuracy.

FIG. 9 shows a seventh embodiment of the present invention. In this embodiment, the signal output terminal 9 of the driving device 62 is connected to the signal input terminal 11 of the feedback amplifiers 10L and 10R.
These feedback amplifiers 10 are connected to L and 11R respectively.
The feedback input terminals 12L and 12R of the L and 10R are respectively connected to one electrodes of the piezoelectric elements 2 and 3 to apply a drive signal. The other electrodes of the piezoelectric elements 2 and 3 are grounded.
The outputs of the feedback amplifiers 10L and 10R are combined and supplied to the input terminal 14 of the driving device 62 so that the vibrator 4 is self-oscillated and the outputs of the feedback amplifiers 10L and 10R are differentiated. It is supplied to the dynamic amplifier 20 so that the Coriolis force generated by the angular velocity acting on the oscillator 4 is detected as a voltage.

FIG. 10 shows an example of the structure of the drive unit 62 shown in FIG. The driving device 62 is configured such that, in the driving device 60 shown in FIG. 2, the inverting amplifier 30 is provided in front of the comparator 23 to invert the signal supplied to the input terminal 14 and supply the inverted signal to the comparator 23. The other configuration is similar to that of FIG. That is, in the above-described embodiment, the feedback signal input to the input terminal of the driving device is the output of the summing amplifier 17 and the phase of which is inverted from that of the driving signal. The feedback signal input to the input terminal 14 of 62 is the feedback amplifier 10L,
Since the output signal of 10R has the same phase as the drive signal, the feedback signal is inverted by the inverting amplifier 30 and supplied to the comparator 23.

In this embodiment, the feedback amplifier 10L,
The output of the 10R includes a respective current passing through the piezoelectric elements 2 and 3, the corresponding feedback resistance Rf _l, since the voltage of the product of the Rf _R, output their synthesis pass through the piezo The voltage depends on the magnitude of the combined current. Therefore, if the amplitude of the driving signal to be output is controlled in the driving device 62 having the AGC circuit 28 so that this voltage becomes constant, the same piezoelectric elements 2 and 3 are formed as in the first embodiment. The equivalent resistance of the vibrator 4 to the vibration in the sensitivity direction can be apparently kept constant irrespective of the change of the ambient temperature, so that the detection sensitivity with respect to the input angular velocity can be made constant and the angular velocity can be highly accurately determined. Can be detected.

FIG. 11 shows an eighth embodiment of the present invention. In this embodiment, in the configuration shown in FIG.
Instead of the driving device 62, a driving device 63 having a compensation signal output terminal 13 for outputting a compensation signal for the braking capacity of the vibrator 4
Is used to synthesize the compensation signal into a synthesized signal of the outputs of the feedback amplifiers 10L and 10R, and the input terminal 14 of the driving device 63 is synthesized.
It is intended to be returned to.

FIG. 12 shows an example of the structure of the driving device 63 shown in FIG. This drive device 63 is shown in FIG.
In the drive device 62 shown in FIG. 0, the drive signal output circuit 2
9, a feedback amplifier 27 is added, the output of the non-inverting amplifier 25 is supplied to the inverting amplifier 26, and also the non-inverting input terminal of the feedback amplifier 27 is supplied, and a capacitor Cc is connected to the inverting input terminal of the feedback amplifier 27. Then, the output of the feedback amplifier 27 is supplied to the compensation signal output terminal 13 as a compensation signal, and other configurations are similar to those of FIG.

According to this embodiment, in the feedback signal supplied to the input terminal 14, the imaginary number component related to each braking capacitance Cd among the signal components corresponding to the currents flowing through the piezoelectric elements 2 and 3 is the capacitor Cc. Since it is canceled by the compensating signal synthesized through the above, only the real number component of the current components flowing through the piezoelectric elements 2 and 3 becomes. Therefore, it is possible to stably vibrate the vibrator 4 at a frequency that exactly matches the mechanical series resonance frequency fs.

In the drive device 63, the amplitude of the drive signal to the signal output terminal 9 is controlled by the AGC circuit 28 so that the level of the feedback signal supplied to the input terminal 14 of the drive device 63 is constant. The equivalent resistance to the vibration in the sensitivity direction of the vibrator 4 formed by the piezoelectric elements 2 and 3 of
Regardless of the change in ambient temperature, it is apparently kept constant, so that the detection sensitivity to the input angular velocity is constant, and the angular velocity can be detected with high accuracy. The self-excited vibration at the mechanical series resonance frequency fs is
It is possible to further stabilize by using, as c, one having a temperature dependence corresponding to the temperature dependence of the braking capacitance Cd of the vibrator 4.

[0055]

As described above, according to the first aspect of the invention, the combined current value of the respective currents that substantially pass through the pair of piezoelectric elements is maintained constant by the AGC circuit, and the voltage of the drive signal output circuit is maintained. Since the gain is made to have a temperature dependence corresponding to the temperature dependence of the equivalent resistance of the vibrator, even if the ambient temperature changes, the AGC circuit has a sufficient margin and the current flowing through the vibrator is increased. Can be suppressed and the equivalent resistance can be maintained apparently constant. Therefore,
Stable self-excited vibration without amplitude fluctuation can be performed, and when applied to a vibration gyro that detects angular velocity using the same pair of piezoelectric elements, the temperature dependence of detection sensitivity with respect to input angular velocity is It is possible to improve the detection accuracy by eliminating it.

According to the second aspect of the invention, the combined current value of the currents obtained by subtracting the current corresponding to the braking capacitance from the respective currents that pass through the substantially pair of piezoelectric elements, that is, the real number component of the combined currents, The AGC circuit keeps the voltage constant and the voltage gain of the drive signal output circuit has a temperature dependence that is contrary to the temperature dependence of the damping capacity of the vibrator. Therefore, even if the ambient temperature changes, In the same manner as in the first aspect of the invention, the AGC circuit is provided with a sufficient margin to suppress the change in the current flowing through the vibrator, and its equivalent resistance can be maintained apparently constant, and thus stable without amplitude fluctuation. In addition to being able to perform self-excited vibration, when applied to a vibration gyro that detects angular velocity using the same pair of piezoelectric elements, the temperature dependence of the detection sensitivity with respect to the input angular velocity. It is possible to improve detection accuracy by eliminating.

[Brief description of drawings]

FIG. 1 is a block diagram showing a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of an example of a driving device shown in FIG.

FIG. 3 is a block diagram showing a second embodiment of the present invention.

FIG. 4 is likewise a block diagram showing a third embodiment.

5 is a block diagram showing a configuration of an example of the driving device shown in FIG.

FIG. 6 is a block diagram showing a fourth embodiment of the present invention.

FIG. 7 is likewise a block diagram showing a fifth embodiment.

FIG. 8 is likewise a block diagram showing a sixth embodiment.

FIG. 9 is likewise a block diagram showing a seventh embodiment.

10 is a block diagram showing a configuration of an example of the driving device shown in FIG.

FIG. 11 is a block diagram showing an eighth embodiment of the present invention.

12 is a block diagram showing a configuration of an example of the drive device shown in FIG.

FIG. 13 is a block diagram for explaining a conventional example.

FIG. 14 is a diagram showing a configuration of an example of a vibrator that can be used in the present invention.

FIG. 15 is a diagram similarly showing a configuration of another example.

FIG. 16 is a diagram similarly showing a configuration of another example.

FIG. 17 is a diagram similarly showing the configuration of another example.

FIG. 18 is a diagram similarly showing the configuration of another example.

FIG. 19 is a diagram similarly showing the configuration of another example.

FIG. 20 is a diagram showing an equivalent circuit of a vibrator.

FIG. 21 is a diagram for explaining display of a vibrator.

FIG. 22 is a block diagram showing the configuration of an example of a vibration control device previously proposed by the applicant.

23 is a block diagram showing the configuration of an example of the drive device shown in FIG.

FIG. 24 is a diagram showing temperature dependence of equivalent resistance and damping capacity of a vibrator.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Vibrating body 2,3 Piezoelectric element 4 Vibrator 60,61,62,63 Driving device 10L, 10R Feedback amplifier 17 Summing amplifier 23 Comparator 24 Amplitude controller 25 Non-inverting amplifier 26 Inversion amplifier 28 AGC circuit 29 Driving signal output Circuit Rf ₂₆ Feedback resistance R _T Negative characteristic thermistor

Claims (2)

[Claims] 1. A vibration control device for self-oscillating a vibrator having substantially a pair of piezoelectric elements on a side surface of a vibrating body having a resonance point, wherein a drive signal applied to the substantially pair of piezoelectric elements is output. A drive signal output circuit whose voltage gain has a temperature dependence corresponding to the temperature dependence of the equivalent resistance of the vibrator, and an automatic circuit for maintaining a constant combined current value of respective currents passing through the substantially pair of piezoelectric elements. A vibration control device comprising a drive device having a gain control circuit. 2. A vibration control device for self-oscillating a vibrator having substantially a pair of piezoelectric elements on a side surface of a vibrating body having a resonance point, which outputs a drive signal applied to the substantially pair of piezoelectric elements, Of the respective currents passing through the drive signal output circuit whose voltage gain has a temperature dependence that is contrary to the temperature dependence of the braking capacity of the vibrator, and the currents passing through the substantially pair of piezoelectric elements, the currents corresponding to the braking capacity. A vibration control device comprising: a drive device having an automatic gain control circuit for maintaining a constant combined current value of the currents obtained by subtracting.