JPH10170277A - Detection circuit of piezoelectric oscillation angular velocity meter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To accurately detect rotational angular velocity, by forming plural electrodes on two vertically facing surfaces of sides which expand in the direction of the center of rotation. SOLUTION: A piezoelectric material 10-1 for driving has an earth electrode 14 on its upper side and an excitation electrode 11 entirely on its lower side, and a piezoelectric material 10-2 for detection has an earth electrode 14 lower a feedback electrode 12 and detection electrodes 13L, 13R on its upper side. The detection electrodes 13L, 13R are bilaterally symmetric in relation to a rotation axis 1 and expand along the rotation axis 1, and the feedback electrode 12 is in the intermediate area between two detection electrodes 13L, 13R and expands in parallel with them. A cross section vertical to the rotation axis 1 of the oscillator 10 is almost square to make mechanical resonance frequency (fc) in the excitation direction (v direction) equal to that in the direction that Coriolis force occurs.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a detection circuit of a piezoelectric vibration gyro for detecting a rotational angular velocity.

[0002]

2. Description of the Related Art FIG. 4 shows a block diagram of a detection circuit of a conventional piezoelectric vibrating gyro. This detection circuit 4
Is a vibrator 100 composed of, for example, a rectangular parallelepiped piezoelectric body.
Is used to measure the output signal from the detection electrode 103 of FIG.

The vibrator 100 includes a driving piezoelectric body 100-1 extending in the direction of the rotation center 1 and a detecting piezoelectric body 10-1.
0-2, a ground electrode 104 formed between the two piezoelectric bodies 100-1 and 100-2, and a driving piezoelectric body 10
An excitation electrode 101 formed on the outer lower surface of 0-1;
A detection electrode 103 formed on the outer upper surface of the detection piezoelectric body 100-2 by being divided into two right and left parts in the direction of the rotation center 1.
L, 103R, and a feedback electrode 102 formed at the center between the two detection electrodes so as to extend in parallel with the two detection electrodes.

An excitation electrode 101 formed on the lower surface of the outside of the driving piezoelectric element 100-1 and a detecting piezoelectric element 100-2
A self-excited drive circuit 30 for exciting and driving the vibrator 100 between the feedback electrode 102 formed on the outer upper surface of
0 is connected, and the two detection electrodes 103L and 103R formed on the outer upper surface of the detection piezoelectric body 100-2 are an inverting (-) input terminal and a non-inverting (+) input terminal of the differential circuit 200, respectively. And the differential circuit 200
The configuration is such that an output difference between the two detection electrodes 103L and 103R is detected.

The output of the differential circuit 200 is a synchronous detection circuit 40
It is input to 0 and detected. The output of the differential circuit 200 is 0 in principle when the vibrator is not rotating.
During the rotation of, the excitation signal for the same phase is canceled out, and only the AC Coriolis signal for the opposite phase is obtained. The synchronous switching signal is input from the phase adjustment circuit 500 to the synchronous detection circuit 400 so that the detection can be performed in synchronization with the Coriolis signal phase. The phase adjustment circuit 500 is connected to the self-excitation drive circuit 300, and is a circuit for shifting the phase of the excitation signal by approximately 90 degrees to generate a switching signal having the same phase as the Coriolis signal phase. The output of the synchronous detection circuit 400 is input to the smoothing circuit 600 and is converted into a DC signal with little ripple.

[0006] Such a conventional detection circuit 4 operates as follows during non-rotation. By applying an AC voltage (excitation signal) having a mechanical resonance frequency of the driving piezoelectric body 100-1 to the excitation electrode 101 by the self-excitation drive circuit 300,
The vibrator 100 is excited (bent) in an exciting direction (vertical direction of the oscillator 100, a direction indicated by v in FIG. 4). The signal of the mechanical resonance frequency accompanying this vibration,
Detection is performed from detection electrodes 103R and 103L formed on the outer upper surface of the detection piezoelectric body 100-2, and a detection signal at this time is detected by the detection electrodes 103R and 103L.
The amplitude and the phase are the same, and the output of the differential circuit 200 is 0 in principle. Therefore, the output of the synchronous detection circuit 400 is also 0, and the output of the smoothing circuit 600 is also 0.

When the vibrator 100 rotates about the center of rotation 1, the Coriolis force is applied in a direction perpendicular to the excitation direction v of the vibrator 100 and the center of rotation 1 of the vibrator 100 (the left-right direction in the drawing of FIG. 1). With the addition of Fc, the vibrator 100 vibrates with a slight shift in the left and right directions from the excitation direction during non-rotation. The difference is the two detection electrodes 103R,
103L is detected as a Coriolis signal.

By the way, the two detection electrodes 103L and 103R are symmetrical with respect to the center of rotation 1. When one of the electrodes is extended, the other electrode is reduced, and polarization charges opposite to each other due to the piezoelectric transverse effect are generated. 103L,
Induced to 103R. Accordingly, the Coriolis signals detected from the two left and right detection electrodes 103L and 103R are AC signals having the same amplitude and opposite mechanical resonance frequencies.

In principle, one of the Coriolis signals from the two detection electrodes 103L and 103R has a 90-degree leading phase and the other has a 90-degree lagging phase with respect to the excitation signal.
Therefore, when the angular speed Ω of rotation is constant, the differential circuit 20
At the output of 0, the Coriolis signal is output with an amplitude value proportional to the rotational angular velocity with a phase difference of 90 degrees with respect to the excitation signal. By smoothing and measuring this output with the smoothing circuit 600, the rotational angular velocity Ω can be detected.

[0010]

The detection circuit 4 of such a conventional piezoelectric vibrating gyro uses an external environment or the vibrator 100.
Even when the output of the differential circuit 200 does not become 0 during non-rotation due to a change with time of the piezoelectric body forming the element and an error signal is generated, the Coriolis signal is Since the error signal is output with a phase difference of about 90 degrees, the error signal after differential circuit output is detected by synchronizing with the phase of the Coriolis signal so that the positive and negative parts are always symmetrical. can do. Therefore, this error signal is canceled by the smoothing circuit 600, and has an advantage that the influence on the accurate measurement of the rotational angular velocity can be reduced.

However, the detection electrode 103 is not used due to variations in the characteristics of the piezoelectric bodies forming the vibrator 100 among individual members, changes in capacitance with time, changes in the external environment, and the like.
Since the amplitude and phase of the feedback excitation signal generated from the R and 103L are not always the same in reality, the error signal between the two at the time of non-rotation does not exactly have a phase difference of 90 degrees from the Coriolis signal phase. In some cases, the error signal may not be completely canceled even after passing through the synchronous detection circuit 400 and the smoothing circuit 600. Therefore, more accurate measurement of the rotational angular velocity Ω may not be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned problems, and is less susceptible to variations in characteristics among individual vibrators and changes in the external environment, and is capable of detecting a rotational angular velocity more accurately. It is an object of the present invention to provide a detection circuit for a vibration angular velocity meter, and to provide a detection circuit suitable for a piezoelectric vibration angular velocity meter that can be mass-produced and can be provided at low cost and that uses a small vibrator.

[0013]

In order to achieve the above object, a vibrator for a piezoelectric vibrating gyro used in the present invention comprises a piezoelectric body elongated in the direction of the center of rotation, And a plurality of electrodes formed on side surfaces extending in the direction of the center of rotation. In particular, the piezoelectric body has a rectangular parallelepiped shape,
It is preferable that the plurality of electrodes are vibrators formed on two vertically opposed sides of the side extended in the direction of the rotation center. Further, in order to ensure the excitation of the vibrator, a ground electrode surface is formed inside the piezoelectric body in parallel with the two vertically opposed side surfaces, and the piezoelectric body is moved in the vertical direction by two.
It is optimal to divide the two into a driving piezoelectric body and a detecting piezoelectric body.

The angular velocity detecting circuit of the piezoelectric vibrating gyro according to the present invention is connected between at least two of a plurality of electrodes formed on the vibrator, and drives the vibrator to drive in synchronization with an excitation signal. An excitation drive circuit, a PLL circuit connected to any one of the plurality of electrodes, and generating a rectangular wave having the same phase by following a detection output from the electrode; A band-pass filter circuit for extracting a sine wave of a frequency; an amplitude adjustment circuit for adjusting the sine wave of the fundamental frequency from the band-pass filter circuit to a reproduced sine wave having the same amplitude as a detection output; A differential circuit for detecting the output difference between
A phase adjustment circuit that generates a switching signal having a phase different from the rectangular wave by 90 degrees, a synchronous detection circuit that detects the output of the differential circuit in synchronization with the switching signal, and a smoothing circuit that smoothes the output of the synchronous detection circuit. It is composed of

In the detection circuit of the piezoelectric vibrating gyro configured as described above, the outputs from the two detection electrodes are simultaneously input to the differential circuit and the same phase of the excitation signal component is canceled out, as in the prior art. Rather than extracting only the Coriolis force components having different phase, the detection output from one detection electrode and a sine wave having the same phase as the excitation signal reproduced from the detection output are used by using the tracking delay of the PLL circuit. Then, the signals are compared by a differential circuit, and the Coriolis signal is detected by taking the difference. In other words, since the Coriolis signal is extracted using only the output from one detection electrode, there is no variation in the capacitance between individual piezoelectric materials, aging, and changes in the external environment due to changes in the external environment. An error signal during rotation is less likely to be output from the differential circuit, and more accurate angular velocity detection is possible.

The Coriolis signal is clearly 9
It has a phase difference of 0 degrees, and the synchronous detection circuit performs detection in synchronization with the switching signal having the same phase as this Coriolis signal.
0% will be detected. Even if the phase of the excitation signal changes, the Coriolis signal is always output with a phase difference of 90 degrees with respect to the phase-changed excitation signal, so that the detection efficiency can always be 100%.

[0017]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a basic configuration of a vibrator used in an embodiment of the present invention. The vibrator 10 made of a piezoelectric material has a rectangular parallelepiped shape as a whole, and is formed in a long shape in the direction of the rotation center 1. The vibrator 10 has a two-layer laminated structure of a piezoelectric material with respect to an excitation direction (the direction of v in the drawing), and a ground electrode extending over the entire coupling surface between the upper and lower piezoelectric bodies 10-1 and 10-2. 14 are formed.

An excitation electrode 11 is formed on the entire outer side surface of the piezoelectric body 10-1 for driving, which is opposite to the ground electrode 14, and a ground electrode 14 is formed on the piezoelectric body 10-2 for detection. A return electrode 12 and detection electrodes 13L and 13R are formed on an external side surface opposite to the above. The detection electrodes 13L and 13R are formed symmetrically with respect to the rotation center 1 and extend in the direction of the rotation center 1.
Reference numeral 2 is formed so as to extend in the center of the two detection electrodes 13R and 13L in parallel with the two electrodes. The cross section perpendicular to the rotation center 1 of the vibrator 10 is formed in a substantially square shape in order to match the mechanical resonance frequency fo in the direction of excitation (v direction) with the direction in which Coriolis force is generated.

FIG. 2 is a configuration diagram of the detection circuit 2 of the piezoelectric vibration gyro according to the present invention using the vibrator 10 described above. The input terminal of the self-excitation drive circuit 30 is connected to the feedback electrode 12, and the output terminal of the self-excitation drive circuit 30 is connected to the excitation electrode 11. The self-excited drive circuit 30 is a circuit that excites the vibrator 10 and supplies an AC voltage for applying mechanical vibration. The self-excited drive circuit 30 includes an amplifier for applying a gain and a loop filter for preventing unnecessary spurious oscillation (both are used). (Not shown).

The self-excited drive circuit 30 generates an AC voltage near the mechanical resonance frequency fo of the vibrator 10 by satisfying the oscillation condition when the power is turned on.
By feeding back a sine wave output from, unnecessary vibration modes other than the fundamental mode are removed by the loop filter, and the vibrator 10 can be excited and driven in the fundamental mode near the mechanical resonance frequency. Furthermore, since the resonance frequency in the left-right direction (the Fc direction in FIG. 1) on which the Coriolis force acts and the resonance frequency in the excitation direction v are matched with each other by setting the cross section perpendicular to the rotation center 1 to be substantially square, the vibration due to the Coriolis force is also reduced. A resonance state can be achieved, and Coriolis detection sensitivity is improved.

One of the two detection electrodes 13L and 13R (13R is used in FIG. 2) is connected to one of the input terminals (inverted input terminal in FIG. 2) of the differential circuit 20. Connected to the input terminal of PLL circuit 21. In the two detection electrodes 13L and 13R, the phases of the Coriolis signals detected from the respective electrodes are only opposite, and in principle, substantially the same signal is detected in either case.
Therefore, either of them may be used, and which one is used is free.

The PLL circuit 21 has one detection electrode 13R.
The detection output is a sine wave even if the excitation signal is a rectangular wave, a triangular wave, or the like due to the filtering action of the piezoelectric body constituting the vibrator 10 (FIG. 3).
(a) (1)). Accordingly, when the vibrator 10 is not rotating, it has a sine wave having the same phase as the excitation signal (hereinafter referred to as a feedback sine wave). When the rotation is applied around the rotation center 1, the amplitude and the amplitude are increased due to the Coriolis force. The sine waves have the same frequency and are out of phase (FIG. 3 (b) (1)). When the vibrator 10 is not rotating, the PLL circuit 21 follows a feedback sine wave having the same phase as the excitation signal and outputs a rectangular wave having the same phase as the excitation signal (FIGS. 3A and 2B). When the vibrator 10 rotates and a phase change occurs in the input sine wave signal, the output is always controlled so that the phase difference from the input sine wave becomes zero.

The output of the PLL circuit 21 is connected to a band pass filter circuit 22. The bandpass filter circuit 22 outputs a sine wave having the same phase as the excitation signal output from the detection electrode 13R by removing harmonic components from the rectangular wave output of the PLL circuit 21 and extracting only the fundamental frequency component. This output is input to an amplitude adjustment circuit (hereinafter, referred to as an AGC circuit) 23.

The AGC circuit 23 is a circuit for making the amplitude of the detection output from the detection electrode 13R equal to the amplitude of the sine wave output from the bandpass filter circuit 22. Therefore, a detection output (a feedback sine wave when the motor is not rotating) is directly input from the detection electrode 13R to the AGC circuit 23 as an amplitude monitor signal, and a sine wave having the same amplitude as the amplitude of the detection output is generated. In particular, the same sine wave as the feedback sine wave when the vibrator 10 is not rotating is temporarily referred to as a reproduced sine wave (FIG. 3).
(a) (3)). This reproduced sine wave is input to another non-inverting (+) input terminal different from the inverting (-) input terminal of the differential circuit 20 to which the output from the detection electrode 13R is input.

The differential circuit 20 detects a difference between the output of the detection electrode 13R and the output of the reproduced sine wave. When the vibrator 10 is not rotating, the output of the detection electrode 13R is a feedback sine wave, which is the same as the reproduced sine wave and the phase amplitude.
The output of the differential circuit 20 is 0 (FIGS. 3A and 4D).
When the vibrator 10 rotates, Coriolis force is generated and an AC Coriolis signal is generated. The output of the differential circuit 20 is input to the synchronous detection circuit 40 and detected. The detection is performed in synchronization with the phase of the AC Coriolis signal, which is the output signal of the differential circuit 20, and a switching signal from the phase adjustment circuit 50 is input to the synchronous detection circuit 40 as the synchronization signal.

The phase adjusting circuit 50 shifts the phase of the rectangular wave output of the PLL circuit 21 by approximately 90 degrees, and the switching signal matches the phase of the AC Coriolis signal detected when the oscillator rotates (FIGS. 3A and 5). Is a circuit for generating. Then, by inputting the output detected by the synchronous detection circuit 40 to the smoothing circuit 60, the AC output of the differential circuit 20 is converted into a DC output with little ripple, and
To obtain an analog output proportional to the rotational angular velocity Ω.

The operation of the detection circuit 2 of the piezoelectric vibrating gyro configured as described above will be described with reference to the drawings. When a sine wave AC voltage is applied as an excitation signal from the self-excited drive circuit 30 to the oscillator 10 when the oscillator 10 is not rotated, an alternating electric field is generated between the self-excited electrode 11 and the ground electrode 14. As a result, the driving piezoelectric body 10-1 sandwiched between the two electrodes expands and contracts in the direction of the rotation center 1 due to the inverse piezoelectric effect. On the other hand, the excitation signal is not directly applied to the detecting piezoelectric body 10-2, and the vibrator 10 performs bending vibration in the direction of the applied voltage (v direction) as a whole in order to suppress the expansion and contraction movement. become.

If the self-excited electrode 11 becomes a positive voltage,
When the driving piezoelectric body 10-1 contracts and the vibrator 10 bends to the detection electrode 13 side, the detection piezoelectric body 10-2 expands, and the feedback electrode 12 and the detection electrode 13 A negative voltage due to the lateral piezoelectric effect will be detected. Since the entirety of the detection piezoelectric body 10-2 expands and contracts due to the bending motion, a feedback sine wave having the same frequency as the mechanical vibration is detected from the feedback electrode 12 and the detection electrode 13, and these voltages are in principle It is the same homologous voltage as the sine wave AC voltage of the excitation signal.

The feedback sine wave output from the detection electrode 13R is input to the PLL circuit 21. The PLL circuit 21 follows an input signal (feedback excitation signal) serving as a reference, and obtains an oscillation output having the same phase and frequency as the input signal. After being converted into a rectangular wave having the same phase and the same frequency, it is input to the band-pass filter circuit 22. Then, this rectangular wave is converted into a sine wave having only the fundamental frequency component in the band-pass filter circuit 22. AGC circuit 2
In step 3, a sine wave output (reproduced sine wave) having the same phase and the same voltage as this output is obtained from the feedback sine wave by automatically adjusting the amplitude. Therefore, the output of the differential circuit 20 that detects the difference between the feedback sine wave and the reproduced sine wave is 0 in principle, and no signal output is detected from the output terminal (FIG. 3A).
(7)).

That is, in such a circuit, the vibrator 10
Even if there is a variation in characteristics among the individual piezoelectric materials, the feedback sine wave input to the inverting input terminal (-) of the differential circuit 20 and the reproduced sine wave input to the non-inverting input terminal (+) are the same. Since the amplitudes have the same phase, the output of the differential circuit 20 is always 0. Further, even if the capacitance and the like due to a change over time or a change in the external environment occur and the amplitude and phase of the feedback sine wave from the detection electrode 13R change, the change is a very slow temporal DC change. As a result, the PLL circuit 21 and the AGC circuit 23 operate following the input change, so that the two inputs to the differential circuit 20 have the same amplitude and the same phase. As a result, the output of the differential circuit 20 is always 0 (FIGS. 3A and 4D).

When rotation is applied around the rotation center 1 in a state where the vibrator 10 is oscillating at a mechanical resonance frequency, Coriolis force is generated. The Coriolis force acts in a direction (Fc direction) perpendicular to the direction of the rotation center 1 and the excitation direction (v direction) as shown in FIG.
0 means that the vibration is shifted from the excitation direction v. The vibration caused by this Coriolis force is caused by the vibrator 1 having no electrodes formed.
0, the right and left sides of the vibrator 10 contract, for example, when the right side of the vibrator 10 expands, the voltage generated from the two detection electrodes 13R and 13L is in principle opposite to the same voltage signal of the opposite phase. Become. Since this is caused by Coriolis force, the Coriolis signal (or Coriolis voltage)
Call.

The Coriolis force Fc is Fc = 2 m
It is represented by [v × Ω]. Therefore, when the angular velocity Ω is constant, the Coriolis force Fc is proportional to the excitation velocity v. Since the excitation speed v is represented by the derivative of the displacement of the vibrator 10, when the excitation signal of the vibrator 10 is given as a sine wave AC voltage, the Coriolis signal has the same frequency as the excitation signal and a phase difference of 90 degrees. It is detected as a cosine wave AC voltage having the same. Furthermore, since the vibration by the excitation signal and the vibration by the Coriolis force Fc occur simultaneously in the vibrator 10, the output signal from the detection electrode 13R is a sine wave whose amplitude and phase are changed by superimposing the Coriolis signal on the feedback sine wave (FIG. 3 (b) (1)).

Generally, the rotation applied to the vibrator 10 is not usually constant, but changes at a relatively high frequency. Therefore, the Coriolis signal detected from the detection electrode 13R is a vibrator 1 having a phase difference of 90 degrees from the excitation signal (that is, the feedback sine wave).
A modulated wave is amplitude-modulated at the frequency of the rotation change of 0. Here, by setting the response time of the PLL circuit 21 to which the modulated wave is input to be extremely long so that the PLL circuit 21 does not follow the Coriolis signal having a fast rotation change, the AGC circuit 23 Of the AGC circuit 23, even if rotation that changes at a relatively fast frequency is applied to the vibrator 10, the reproduced sine wave having the same phase as the excitation signal during non-rotation is output as it is. (FIG. 3 (b) (3)).

In this manner, when rotation is applied to the vibrator 10, the feedback sine wave of the excitation signal and the rotation are generated at the inverting (-) input terminal of the differential circuit 20 during non-rotation. A sine wave signal on which a Coriolis signal is superimposed is input, while a non-inverted (+) input terminal receives a reproduced sine wave having the same voltage and the same phase as the feedback sine wave, and the difference is obtained. Therefore, even if the phase of the feedback sine wave changes due to a change with time or a change in capacitance due to a change in the external environment, the excitation signal component in the differential circuit 20 is accurately canceled without generating an error voltage. Only the Coriolis signal having a phase difference of 90 degrees from the excitation signal (feedback sine wave) is output to the output of the driving circuit 20 (see FIGS. 3B and 4D).

The Coriolis signal output of the differential circuit 20 is an AC signal having an amplitude proportional to the rotational angular velocity.
If the output of the differential circuit 20 is detected and smoothed, a DC signal proportional to the angular velocity can be obtained. In this case, even if the feedback sine wave included in the output of the detection electrode 13R during rotation and the reproduced sine wave are not exactly canceled out and an error voltage is output, this error signal is the same as the excitation signal. The post-differential Coriolis signal, which is a signal of the same phase and which is the output of the differential circuit 20, is always 90
Since the signals are output with a phase difference of one degree, when the output of the differential circuit 20 is detected by the synchronous detection circuit 40, if it is performed in synchronization with the switching signal synchronized with the Coriolis signal phase,
The error signal is detected such that the positive and negative parts are symmetrical to each other.

Therefore, by inputting the output of the synchronous detection circuit 40 to the smoothing circuit 60, the positive and negative parts of the error signal are canceled by the smoothing circuit 60 without excess or deficiency. Therefore, the influence of the error signal on accurate angular velocity detection can be eliminated (FIG. 3B).
(7)). Note that the output of the PLL circuit 21 is a rectangular wave having the same phase as the feedback sine wave, and the switching signal can be easily generated by shifting the phase of the output of the PLL circuit 21 by 90 degrees by the phase adjustment circuit 50.

In the above-described embodiment, the feedback electrode 12 is formed on the vibrator 10 and a feedback loop is formed so that the vibrator 10 can be driven near its mechanical resonance frequency with a simple circuit configuration. Although the loop filter prevents unnecessary spurious oscillation and can be driven in a single-frequency excitation mode, the present invention is not limited to this, and the self-excitation drive circuit 30 can directly drive the self-excitation electrode 11 and the ground electrode 14. To drive the vibrator 10. Also, the left and right electrodes may be used as the detection electrodes, and only the polarity of the Coriolis signal is reversed.

Although the operation has been described for the case where the rotational angular velocity Ω is detected based on the non-rotation of the vibrator 10, the detecting circuit 2 of the piezoelectric vibrating angular velocity meter according to the present invention uses the vibrator 1.
Detection electrode 13R when 0 is rotating at an arbitrary constant speed
It is needless to say that the rotational angular velocity can be detected using the detected output as a reference signal.

[0039]

As described above, according to the detection circuit of the piezoelectric vibration gyro according to the present invention, the outputs from the two detection electrodes are input to the differential circuit and compared, and the excitation of the same phase is performed. Rather than detecting only the Coriolis signal that is 90 degrees out of phase with the excitation signal by canceling the signal component, the excitation signal component of the same phase is canceled using only the output from one detection electrode and the Coriolis force component is used. In order to extract only, even if variations among individual piezoelectric bodies, changes over time and changes in capacitance due to changes in the external environment occur, changes in the excitation signal due to these are reliably canceled by the differential circuit, More accurate angular velocity detection becomes possible.

The Coriolis signal is clearly defined as the excitation signal.
It has a phase difference of 0 degrees, and the synchronous detection circuit performs detection in synchronization with the switching signal having the same phase as this Coriolis signal.
0% will be detected. Even if the phase of the excitation signal changes, the Coriolis signal is output with a phase difference of 90 degrees with respect to the phase-changed excitation signal, so that the detection efficiency is 100% and the output of the smoothing circuit is constant. Will be kept. Therefore, the rotational angular velocity can be accurately detected.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration example of a vibrator used in the present invention.

FIG. 2 is a diagram showing a configuration example of a detection circuit of the piezoelectric vibration gyro according to the present invention.

FIG. 3 is a detection waveform of each part of the piezoelectric vibration gyro according to the present invention. (A) shows the waveform at the time of no rotation, and (b) shows the waveform at the time of rotation.

FIG. 4 is a configuration diagram of a detection circuit of a conventional piezoelectric vibration gyro.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Rotation center 10, 100 Oscillator 11, 101 Self-excited electrode 12, 102 Feedback electrode 13, 103 Detection electrode 14, 104 Ground electrode 20, 200 Differential circuit 21 PLL circuit 22 Band-pass filter circuit 23 Amplitude adjustment circuit 30, 300 Self-excited drive electrode 40, 400 Synchronous detection circuit 50, 500 Phase adjustment circuit 60, 600 Smoothing circuit

Claims (5)

[Claims] A vibrator in which a plurality of electrodes are formed on a side surface of the piezoelectric body extending in the direction of the rotation center and extending in the direction of the rotation center; and at least two electrodes among the plurality of electrodes. A self-excited drive circuit connected between the plurality of electrodes, the self-excited drive circuit being connected to any one of the plurality of electrodes to generate a rectangular wave having the same phase following a detection output from the electrode; A band-pass filter circuit for extracting a sine wave having the same phase as the rectangular wave and a fundamental frequency from the output of the PLL circuit; and reproducing the sine wave from the band-pass filter circuit with the same amplitude as the detection output. An amplitude adjustment circuit that compensates for a sine wave; a differential circuit that detects a difference between the detection output and the reproduced sine wave; and a phase adjustment circuit that generates a switching signal having a 90-degree phase difference from the rectangular wave. A synchronous detection circuit that detects a differential output of the differential circuit in synchronization with the switching signal; and a smoothing circuit that smoothes a detection output of the synchronous detection circuit, wherein the vibrator has the rotation center. When rotating about an axis, the difference between the detection output in which the voltage due to the polarization charge induced in any one of the electrodes is superimposed and the reproduced sine wave generated by using the tracking delay of the PLL circuit is calculated as the difference A detection circuit for a piezoelectric vibrating gyro, wherein the detection circuit obtains a voltage proportional to the angular velocity due to the rotation. 2. The piezoelectric body according to claim 1, wherein the piezoelectric body is a rectangular parallelepiped piezoelectric body having a center of rotation in a longitudinal direction, and two side faces of the piezoelectric body extending in a direction of the center of rotation are opposed to each other in two vertical directions. 2. The detection circuit according to claim 1, wherein a vibrator having a plurality of electrodes is used. 3. The piezoelectric body of a rectangular parallelepiped shape is divided into a driving piezoelectric body and a detecting piezoelectric body in the vertical direction in a plane perpendicular to the rotation center, and the driving piezoelectric body and the detecting piezoelectric body are separated from each other. 3. A detection circuit for a piezoelectric vibrating gyro according to claim 2, wherein a vibrator configured by arranging a ground electrode therebetween is used. 4. The self-excited drive circuit is formed on one electrode formed on an outer side surface of the driving piezoelectric body extending in the direction of the rotation center and on an outer side surface of the detection piezoelectric body extending in the outer side direction. 4. The detection circuit for a piezoelectric vibration gyro according to claim 3, wherein said detection circuit is connected between said one electrode and said one electrode. 5. The self-excited drive circuit is connected between one of the plurality of electrodes and a ground electrode. Detection circuit of the piezoelectric vibration gyro.