JP2998248B2 - Angular velocity sensor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates are, for example to drive the tuning fork structure vibrating angular velocity sensor using the ceramic piezoelectric element, to an angular velocity sensor device <br/> for outputting a voltage proportional to the angular velocity.

[0002]

2. Description of the Related Art A conventional angular velocity sensor device will be described with reference to the drawings. FIG. 6 is a block diagram showing a configuration of a conventional angular velocity sensor device , wherein 1 is a first amplifier, 2 is a rectifier, 3
Is a smoothing circuit, 4 is a second amplifier, 5 is a third amplifier, 6
Denotes a phase detector, 7 denotes a smoothing circuit, 8 denotes a DC amplifier, and 9 denotes a tuning-fork structure vibration type angular velocity sensor.

The tuning fork structure vibration type angular velocity sensor device includes a first amplifier 1 for amplifying a surface charge of a monitoring piezoelectric element 102, a rectifier 2 for rectifying an output voltage thereof, and a smoothing device for smoothing an output voltage of the rectifier 2. Circuit 3 and the smoothing circuit 3
The amplitude of the voltage applied to the driving piezoelectric element 101 is controlled by the second amplifier 4 which is configured so that the amplification degree decreases as the output voltage value increases and the amplification degree increases as the output voltage value decreases. The tuning fork vibrates at an amplitude.

The first and second detecting piezoelectric elements 10
Electric charges are generated in the 3,104 surface electrodes in accordance with the applied angular velocity. This electric charge is amplified by the third amplifier 5 and phase-detected by the phase detector 6 at the period of the tuning fork oscillation to obtain a voltage proportional to the angular velocity. This voltage was configured to be DC-amplified by the DC amplifier 8 and output.

[0005]

SUMMARY OF THE INVENTION Tuning fork structure vibration type angular velocity
The sensor detects the angular velocity generated in the direction orthogonal to the tuning fork vibration direction.
The basic principle is to use the signal according to the degree.
Because of the presence of the signal
Ingredients are easily generated.

For example, the angular velocity signal is zero due to the orthogonal accuracy of the driving piezoelectric element 101 and the first detecting piezoelectric element 103 and the orthogonal accuracy of the monitoring piezoelectric element 102 and the second detecting piezoelectric element 104. Even the third amplifier 5
A charge is generated at the input end of the device due to tuning fork vibration.

This charge can be completely removed when passing through the phase detector 6, but since this charge has a very large value with respect to the charge generated by the angular velocity, the third amplifier before the phase detection is performed. 5, the amplification cannot be increased, and therefore, it is necessary to increase the amplification of the DC amplifier 8 after performing the phase detection.
Output voltage becomes unstable due to fluctuations in the switching speed of the DC amplifier 8, and there is large performance variation due to the occurrence of drift due to a temperature change in the output voltage due to offset fluctuations of the DC amplifier 8, which adversely affects output signals such as ripples and noise. It had problems.

An object of the present invention is to provide an angular velocity sensor device which solves the above-mentioned problems and achieves stable performance.

[0009]

In order to solve the above-mentioned problems, an angular velocity sensor device according to the present invention comprises an angular velocity sensor having a tuning fork structure.
A sensor, a first amplifier to which an electric charge generated on a surface electrode of a monitor piezoelectric element of the angular velocity sensor is input, an inverting amplifier to which an output voltage of the first amplifier is input, and an output voltage of the inverting amplifier. A second amplifier that variably adjusts and outputs a driving voltage of the driving piezoelectric element as an input, and an electric charge generated by inputting electric charges generated at surface electrodes of the first and second detecting piezoelectric elements of the angular velocity sensor as an input. A third amplifier that outputs a voltage proportional to the following, a phase detector that detects the output voltage of the third amplifier by the timing of the tuning fork oscillation, a smoothing circuit that smoothes the output signal of the phase detector, A DC amplifier for DC-amplifying the output voltage of the smoothing circuit; and a resistance element between one of the output terminal of the first amplifier and the output terminal of the inverting amplifier and the input terminal of the third amplifier. Ku is obtained by the configuration of connecting the capacitor element.

[0010]

With this configuration, it is possible to cancel the leak signal component due to the tuning fork vibration included in the input signal of the third amplifier, thereby increasing the amplification of the third amplifier.

That is, the leak signal component due to the tuning fork vibration is a signal component having the same phase or a 180 ° phase shift from the output voltage of the first amplifier which amplifies the tuning fork vibration voltage.

Therefore, in the case of the same phase, if a signal obtained by inverting and amplifying this signal is added in a fixed amount according to the magnitude of the leak signal, the leak signal can be canceled, and the output of the first amplifier can be cancelled. If the signal component is 180 ° out of phase with the voltage, the output signal of the first amplifier can be canceled by adding a fixed amount according to the magnitude of the leak signal.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the angular velocity sensor device according to the present invention will be described below with reference to the drawings.

First, a tuning fork structure vibration type angular velocity sensor will be described with reference to FIGS. FIG. 3 is a perspective view showing a configuration of the angular velocity sensor according to the present invention, which is mainly composed of a driving element 101 composed of four piezoelectric elements, a monitor element 102, first and second detection elements 103 and 104, and a driving element. A first vibration unit 109 in which a first sensing element 103 and a first sensing element 103 are orthogonally joined at a joining portion 105;
The second vibration unit 110, in which the second and second sensing elements 104 are orthogonally joined at the joining portion 106, is connected by a connecting plate 107, and the connecting plate 107 is configured in a tuning fork structure in which the connecting plate 107 is supported at one point by a support rod 108. I have. The above four piezoelectric elements 1
Each of 01 to 104 is formed by joining a piezoelectric body to a tuning fork made of a metal vibrator.

When a sinusoidal voltage signal is applied to the driving element 101 of the angular velocity sensor thus configured, the first vibration unit 109 starts to vibrate due to the inverse piezoelectric effect, and the second vibration unit 110 also vibrates due to the tuning fork vibration. To start. Therefore, the monitor element 1 is caused by the piezoelectric effect of the monitor element 102.
The electric charge generated on the surface 02 is proportional to the sinusoidal voltage signal applied to the driving element 101. By detecting the electric charge generated in the monitor element 102 and controlling the sine wave voltage signal applied to the drive element 101 so that the electric charge has a constant amplitude, a stable tuning fork vibration can be obtained.

The mechanism by which the angular velocity sensor 9 generates an output proportional to the angular velocity will be described with reference to FIGS.

FIG. 4 shows a state in which the angular velocity sensor 9 shown in FIG. 3 is viewed from above. When the rotation of the angular velocity ω is applied to the first detection element 103 vibrating at the velocity υ, the first
A “Coriolis force” is generated in the detecting element 103 of FIG. This “Coriolis force” is perpendicular to the speed υ and has a magnitude of 2 mυω. Since the first sensing element 103 is oscillating at the tuning fork, if it is oscillating at the speed υ at a certain point in time, the second sensing element 104 is oscillating at the speed −υ and the “Coriolis force” is -2mυω. Therefore, as shown in FIG. 5, the first and second sensing elements 103 and 104 are mutually "Coriolis forces".
Is deformed in the direction in which the function is effected, and charges are generated on the surfaces of the first and second sensing elements by the piezoelectric effect.

[0018] Here, υ is a movement caused by the vibration of the tuning fork, tuning fork vibration _{υ = a · sinω 0 t a} : amplitude of the tuning fork vibration ω _0: if the period of the vibration of the tuning fork, "Coriolis force" is F _c = a · ω · sin ω ₀ t, which is proportional to the angular velocity ω and the tuning fork amplitude a, and serves as a force for deforming the first and second detection elements 103 and 104 in the plane direction.

Therefore, the first and second sensing elements 103, 10
4 is Q 量 a · ω · sin ω ₀ t, and if the tuning fork amplitude a is controlled to be constant, then Q∝ω · sin ω ₀ t, and the first and second sensing elements 103, 104 Is obtained as an output proportional to the angular velocity ω,
If this signal is synchronously detected at ω ₀ t, a DC signal proportional to the angular velocity ω can be obtained.

Note that even if a translational motion other than the angular velocity is given to this sensor, the first detecting element 103 and the second detecting element 10
Since electric charges of the same polarity are generated on the two element surfaces of No. 4, when converted into a DC signal, they cancel each other out and no output is produced.

FIG. 1 shows an embodiment of an angular velocity sensor device according to the present invention. FIG. 1 shows an angular velocity sensor according to the present invention.
FIG. 2 is a block diagram showing the configuration of the device , wherein 1 is a first amplifier, 2 is a rectifier, 3 is a smoothing circuit, 4 is a second amplifier, 5
Is a third amplifier, 6 is a phase detector, 7 is a smoothing circuit, 8 is a DC amplifier, 9 is a tuning fork structure vibration type angular velocity sensor , 10
Denotes an inverting amplifier, and 11 denotes a capacitive element.

FIGS. 2A, 2B and 2C are output waveform diagrams showing output voltages of respective parts in the block diagram shown in FIG. 1, and FIG. The output voltage, (b) is the output voltage of the inverting amplifier 10, the dashed line (c) is an electric charge having an amplitude proportional to the angular velocity signal input to the third amplifier 5 and having the same period as the tuning fork oscillation period, and the solid line is the tuning fork oscillation period. This is the charge of the leak signal component. As described above, the leak signal component of the tuning fork vibration is generated by the angular deviation in assembling the angular velocity sensor, and the amplitude is proportional to the magnitude of the deviation. 18) by side
The phases differ by 0 °.

Therefore, the phase and magnitude of the leak signal component are measured in advance for each angular velocity sensor alone, and the optimum capacitive element or resistive element 11 is selected to cancel the leak signal component, and the polarity of the phase of the leak signal component is determined. By selecting either the output terminal of the first amplifier 1 or the output terminal of the inverting amplifier 10 and connecting a capacitive element or a resistive element 11 between the terminal and the input terminal of the third amplifier 5. The leak signal component indicated by the solid line in FIG. 2C can be reduced.

In the angular velocity sensor device configured as described above, the leak signal component indicated by the solid line in FIG. 2C is proportional to the angular velocity signal input to the third amplifier 5 indicated by the broken line. 1 for a charge signal with the same amplitude as the tuning fork oscillation cycle
Assuming that the amplitude is 0 times, the amplification degree of the third amplifier 5 can be increased to 10 times by canceling out the solid line leakage signal component. The amplification degree of 8 may be 1/10.

As a result, the error due to the switching speed of the phase detector 6 and the error due to the offset fluctuation of the DC amplifier 8 are reduced to 1/10, and the noise and ripple are also reduced.

By setting the amplification degree of the third amplifier 5 to 10 times, the offset fluctuation of the third amplifier 5 can be reduced by 10 times.
Although the effect is doubled, this effect is eliminated by using the configuration via the phase detector 6, and the performance can be stabilized.

[0027]

According to the angular velocity sensor device of the present invention, it is possible to cancel the electric charge generated in the detecting piezoelectric element when the angular velocity is zero and inputted to the third amplifier, whereby the amplification in the amplification stage before the phase detection is performed. This makes it possible to reduce the ripple of the tuning fork vibration frequency included in the output signal, reduce the fluctuation of the output voltage and the temperature drift due to the fluctuation of the switching speed of the phase detector, and the output voltage due to the fluctuation of the offset of the DC amplifier. In this case, it is possible to obtain effects such as a reduction in temperature drift of the semiconductor device and a reduction in noise included in the output voltage.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of an angular velocity sensor device according to an embodiment of the present invention.

FIG. 2A is an output waveform diagram showing an output voltage of a first amplifier in the embodiment. FIG. 2B is an output waveform diagram showing an output voltage of an inverting amplifier in the embodiment. Output waveform diagram showing charge

FIG. 3 is a perspective view showing a configuration of an angular velocity sensor in the embodiment.

FIG. 4 is a main part plan view for explaining the operation of the angular velocity sensor in the embodiment.

FIG. 5 is a perspective view of a main part for explaining the operation of the angular velocity sensor in the embodiment.

FIG. 6 is a block diagram showing an example of a conventional angular velocity sensor device .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 1st amplifier 2 Rectifier 3,7 Smoothing circuit 4 2nd amplifier 5 3rd amplifier 6 Phase detector 8 DC amplifier 9 Angular velocity sensor 10 Inverting amplifier 11 Capacitance element 101 Driving piezoelectric element 102 Monitoring piezoelectric element 103 No. No. 1 piezoelectric element for detection 104 Second piezoelectric element for detection 105, 106 Joint 107 Connecting plate 109 First vibration unit 110 Second vibration unit

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Junsei Yoshida 1006 Kadoma, Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (56) References JP-A-61-206516 (JP, A) JP-A-4 -297874 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G01C 19/56 G01P 9/04

Claims (3)

(57) [Claims] An angular velocity sensor having a tuning fork structure and an angular velocity sensor
The charge generated at the surface electrode of the piezoelectric element for sensor monitoring is entered.
A first amplifier to be used as an input and an output voltage of the first amplifier
Amplifier and the output voltage of this inverting amplifier
To adjust the drive voltage of the drive piezoelectric element
A second amplifier for outputting, and first and second of the angular velocity sensors.
The charge generated on the surface electrode of the piezoelectric element for detection 2 is used as an input.
A third amplifier that outputs a voltage proportional to the charge amount,
The output voltage of the third amplifier is used as the timing of the tuning fork oscillation.
Therefore, the phase detector that performs phase detection and the output of this phase detector
A smoothing circuit for smoothing the force signal and an output voltage of the smoothing circuit
DC amplifier for amplifying the DC power of the first amplifier, and the output of the first amplifier
Terminal or the output terminal of the inverting amplifier
A resistor or a capacitor is connected between the third amplifier and the input terminal.
An angular velocity sensor device configured by connecting a quantity element. 2. An angular velocity sensor includes a driving piezoelectric element and a first piezoelectric element.
First vibration formed by orthogonally joining detection piezoelectric elements to each other
Unit and piezoelectric element for monitoring and second piezoelectric element for detection
From the second vibration unit which is orthogonally joined to each other.
And the first and second vibration units are moved along the detection axis.
The driving piezoelectric element and the motor so as to be parallel to each other.
Tuning fork by connecting free ends of piezoelectric element
The angular velocity sensor device according to claim 1, wherein the angular velocity sensor device has a structure. 3. An angular velocity sensor comprising a metal vibrator.
And a piezoelectric body joined to the tuning fork
Item 3. The angular velocity sensor device according to Item 2.