JP2001183137A - Gyro device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate erroneous functioning of a gyro device even with addition of acceleration to an angular velocity detection element and distinguish the signals of acceleration and angular velocity. SOLUTION: An acceleration signal component removal circuit for removing signal components generated by the acceleration working on a vibrator from the output of a detection means detecting the displacement of a vibrator based on Coriolis force added to the vibrator is provided. The acceleration signal component removal circuit is made a filter circuit for shielding the frequency of the acceleration signal and it sets the frequency of the drive signal at a higher frequency than the shielding frequency of the filter circuit.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyro device, and more particularly, to a vibratory gyro device using an angular velocity detecting element formed by semiconductor fine processing technology.

[0002]

2. Description of the Related Art In recent years, minute gyro devices have been used in cameras, car navigation devices, and the like. In a camera, an angular velocity signal of a gyro device is used to prevent camera shake during photographing, and in a car navigation device, to indicate a course of an automobile.

FIG. 6 shows a circuit block of a conventional gyro device. In FIG. 6, an angular velocity detecting element 1 includes a vibrating body 11, drive electrode units 12 and 13 for electrostatically vibrating the vibrating body 11, and a detection device for electrostatically detecting a displacement of the vibrating body 11. It has electrode portions 14 and 15. The capacitance-voltage conversion circuit 2 converts a change in the capacitance of the angular velocity detecting element 1 into a voltage, and includes two field-effect transistors (hereinafter, referred to as “FETs”) 21 and 22. The gate 21a of one FET 21 is connected to the detection electrode section 14 of the angular velocity detecting element 1, and the other gate 22a
Are connected to the drive electrode unit 15. FETs 21 and 22
Of the DC power supply Vcc
, And the sources 21c and 22c are grounded via source resistances 21d and 22d, respectively. Output voltages are respectively taken from both ends of the source resistors 21d and 22d of the source follower circuit.

The DC cutoff circuit 3 includes DC cut capacitors 31 and 32, and the output voltage of the capacitance-voltage conversion circuit 2 is supplied to the signal separation circuit 4 through the DC cut capacitors 31 and 32, respectively. The signal separation circuit 4 includes two amplifiers 41 and 42, a differential amplifier 43, and a summing amplifier 44. The output terminals of the amplifiers 41 and 42 are connected to the input terminals of the differential amplifier 43 and the summing amplifier 44 Is connected to the input terminal of The drive circuit 5 includes an amplitude circuit / triangular wave generation circuit 51 and an inverting amplifier circuit 52. An input terminal of the amplitude circuit / triangle wave generation circuit 51 is connected to an output terminal of the addition amplifier 44. The output terminal is connected to the drive electrode unit 13 of the angular velocity detecting element 1 and to the drive electrode unit 12 via the inverting amplifier circuit 52. The output circuit 6 includes a synchronous detection circuit 61, an offset adjustment circuit 62, and a sensitivity adjustment amplifier 63. The input terminal of the synchronous detection circuit 61 is connected to the output terminal of the differential amplifier 43. In addition, the synchronous detection circuit 6
The output terminal 1 is connected to the input terminal of the sensitivity adjustment amplifier 63 together with the output terminal of the offset adjustment circuit 62.

The operation of the circuit block will be described. The drive electrodes 12 and 13 of the angular velocity detecting element 1
When a driving signal having a constant frequency and a constant amplitude is added to the driving force Fe to give a driving force Fe, the vibrating body 11 mechanically vibrates at a specific vibration frequency in a certain direction. The drive circuit 5 normally applies a drive signal having a frequency substantially equal to the mechanical resonance frequency of the vibrating body 11, for example, 15 kHz, to the drive electrode units 12 and 13. When no acceleration or angular velocity is applied to the vibrating body 11, the detecting electrode unit 1 of the angular velocity detecting element 1
No output is generated from 4,15. When acceleration or angular velocity is given to the vibrating body 11 of the angular velocity detecting element 1,
The vibrating body 11 is displaced, and a change in capacitance appears on the detection electrode portions 14 and 15. In the case of acceleration, the vibrating body 11 is displaced in the direction in which the acceleration force Fk is applied, and in the case of angular velocity, it is displaced in the direction in which the Coriolis force Fc is generated. That is, as shown by the vector in FIG. 8, when the angular velocity occurs, the vibrating body 11
Vibration vector F obtained by combining Coriolis force Fc and driving force Fe
When it vibrates at d and acceleration occurs, it vibrates with a vibration vector obtained by combining the acceleration force Fk and the driving force Fe. And
When the angular velocity and the acceleration are generated simultaneously, the resultant vector vibration is generated.

[0006] Detecting electrode portions 14 and 15 of angular velocity detecting element 1
, Two signals 180 degrees out of phase from each other are output and supplied to the capacitance-voltage conversion circuit 2. The frequency of this output signal is the vibration frequency of the vibrating body 11. The capacitance-voltage conversion circuit 2 includes detection electrode portions 14 and 15 of the angular velocity detection element 1.
Are converted to voltages by source follower circuits. These two output signals are supplied to the DC cutoff circuit 3
And the DC component included in the output voltage of the capacitance-voltage conversion circuit 2 is removed, leaving only the AC signal component. The signal that has passed through the DC cutoff circuit 3 is input to the signal classification circuit 4 and is amplified by the amplifiers 41 and 42. Two amplifiers 41, 42
Is input to a differential amplifier 43 and a summing amplifier 44. The differential amplifier 43 extracts the difference between the output signals of the two amplifiers 41 and 42 and extracts the angular velocity signal component due to the Coriolis force.
Of the angular velocity detecting element 1
A vibration amplitude signal component generated by the first vibration is extracted.

[0007] The amplitude circuit and the triangular wave generation circuit 51 to which the signal having the vibration amplitude signal component obtained from the addition amplifier 44 is input, output a drive signal having a constant amplitude for continuing the vibration of the angular velocity detecting element 1. This drive signal is supplied to the drive electrode unit 13 of the angular velocity detection element 1, and is further supplied to the drive electrode unit 12 after inverting the phase by 180 degrees through the inverting amplifier circuit 52. As a result, the vibrating body 11 of the angular velocity detecting element 1 is energized by the drive signals having phases different from each other by 180 degrees. A self-excited oscillation system that drives the angular velocity detecting element 1 by feedback of the vibration amplitude signal component from the addition amplifier 44 to the drive circuit 5 is configured.

The angular velocity signal component obtained from the differential amplifier 43 is supplied to an output circuit 6. The synchronous detection circuit 61 of the output circuit 6 performs synchronous detection of the output signal of the differential amplifier 43 using the drive signal of the amplitude circuit and the triangular wave generation circuit 51 as a reference signal, and extracts only the angular velocity signal. The offset adjustment circuit 62 outputs an adjustment signal for adjusting the offset voltage of the angular velocity signal passed through the synchronous detection circuit 61 to the sensitivity adjustment amplifier 63. That is, when the angular velocity signal input from the synchronous detection circuit 61 includes an offset voltage, the sensitivity adjustment amplifier 63 outputs the angular velocity signal subjected to the offset adjustment.

An example of the angular velocity detecting element 1 will be described with reference to FIG. Inside the quadrilateral support frame 7, support portions 71 and 72 are provided to face each other. The outer frame vibrating portion 16 of the vibrating body 11 is provided with support portions 71, 72 at the distal ends of the support portions 71, 72.
Are supported by both ends of outer beams 16a and 16b extending in a direction perpendicular to the outer beams. On the inner side of the outer frame vibrating portion 16, the projecting portions 16c, 1 are directed inward and opposed to each other at a position orthogonal to the direction connecting the supporting portions 71 and 72.
6d are provided. Inner beams 17a, 17b are provided at the distal ends of the protruding portions 16c, 16d so as to extend in a direction orthogonal to the extending direction of the outer beams 16a, 16b. At both ends of the inner beams 17a and 17b, inner frame vibrating portions 17 are supported. Inside the inner frame vibrating portion 17, a mass portion 17 extending in a direction connecting the support portions 71 and 72 of the support frame 7 is provided.
c is provided.

The outer frame vibrating section 16 includes outer beams 16a and 16b.
The drive electrode section 12 and the drive electrode section 13 shown in FIG. This drive electrode unit 1
Reference numerals 2 and 13 denote plate-shaped outer frame movable comb electrodes 12a and 13a formed on the outer frame vibrating portion 16, and the outer frame movable comb electrode 1
Plate-shaped outer frame driving comb-shaped electrodes 12b, 13b opposed to micro-spaces 2a, 13a;
It comprises outer frame fixed electrodes 12c and 13c that support 2b and 13b. Also, inside the inner frame vibrating part 17,
The detection electrode parts 14 and 15 are provided on the left and right of the mass part 17c. The detection electrode portions 14 and 15 are composed of plate-shaped inner frame movable comb electrodes 14a and 15a implanted in the mass portion 17c,
Plate-shaped inner frame detection comb electrodes 14b, 15b opposed to the inner frame movable comb electrodes 14a, 15a via a minute space;
It is composed of inner frame fixed electrodes 14c, 15c that support the inner frame detection comb electrodes 14b, 15b.

FIG. 7 does not show a support substrate and a lid substrate of the angular velocity detecting element 1, but the support frame 7, the outer frame fixed electrodes 12c and 13c, and the inner frame fixed electrodes 14c and 15c are fixed to the support substrate. The other supporting portions 71, 72, the entire vibrating body 11, and the comb-shaped electrodes 12, 13, 14, 15 are provided with a gap between the supporting substrate and the lid substrate, so that the vibrating body 11 can freely vibrate. I have. The lid substrate is in contact with the support frame 7 and covers the angular velocity detecting element 1. The angular velocity detecting element 1 has a thickness in a direction perpendicular to the drawing. In particular, in the above-mentioned comb-shaped electrodes 12a to 15a, the plate-shaped surfaces in the thickness direction face each other via a minute space, and the capacitance is reduced. It is configured to be provided. The outer frame fixed electrodes 12c and 13c and the inner frame fixed electrodes 14c and 15c are electrically connected to the outside of the support substrate via via holes formed in the support substrate.

When a driving voltage is applied to the outer frame fixed electrodes 12c and 13c of the angular velocity detecting element 1 as shown in FIG. 6, the outer frame movable comb electrodes 12a and 12a of the driving electrode portions 12 and 13 are applied.
An electrostatic force acts between 13a and the outer frame driving comb electrodes 12b and 13b, and this acts as a driving force Fe to cause the outer frame vibrating section 16 together with the inner frame vibrating section 17 in the direction of the support sections 71 and 72 with a constant amplitude. Vibrate. That is, the outer beams 16a and 16b bend,
The entire vibrating body 11 vibrates in the horizontal direction in the drawing. In this state, when the angular velocity detecting element 1 rotates around its center, in other words, when it rotates around an axis perpendicular to the drawing passing through the center of the vibrating body 11, the driving force Fe is applied to the vibrating body 11.
The Coriolis force Fc acts in a direction perpendicular to the direction in which the inner beams 17a and 17b act, and the inner frame vibrating portion 17 is displaced in a direction perpendicular to the inner beams 17a and 17b due to the bending of the inner beams 17a and 17b. Due to this displacement vibration, the capacitance between the inner frame movable comb electrodes 14a, 15a of the detection electrode portions 14, 15 and the inner frame detection comb electrodes 14b, 15b changes. Then, the capacitance change including the angular velocity signal component is taken out from the inner frame fixed electrodes 14c and 15c and transmitted to the gates 21a and 22a of the FETs 21 and 22. On the other hand, when acceleration acts on the angular velocity detecting element 1 from an arbitrary direction, the inner frame vibrating part 17 is displaced alone or together with the outer frame vibrating part 16, and the inner frame fixed electrode 1 is moved in the same manner as described above.
4c and 15c output a signal indicating a change in capacitance including an acceleration signal component.

Another example of the angular velocity detecting element 1 will be described with reference to FIG. Inside the support frame 9, four beams 9a, 9b, 9 extending from the four inner edges of the support frame 9 and joining in a cross shape are provided.
c, 9d are provided. Four beams 9a, 9b, 9
A weight 9e indicated by a dotted line is vertically provided at the connection point between c and 9d. These become the vibrating body 11 shown in FIG. Each beam 9
On the surfaces of a, 9b, 9c and 9d, a piezoelectric drive unit corresponding to the drive electrode units 12 and 13 shown in FIG.
A piezoelectric detection unit corresponding to 15 is provided. The piezoelectric driving section and the piezoelectric detecting section are composed of piezoelectric driving elements 12e and 13e and piezoelectric detecting elements 14e and 15e formed of a piezoelectric thin film. The beams 9a, 9b, 9c, 9d are formed to have a small thickness in a direction perpendicular to the drawing, and can bend in a direction perpendicular to the drawing. When a drive signal is applied to the piezoelectric drive elements 12e and 13e as shown in FIG.
The beams 9c and 9d are bent by the bending motions of the beams e and 13e, and the lower end of the weight 9e is vibrated in the extending direction of the beams 9c and 9d. At this time, when Coriolis force is applied to the weight 9e, the weight 9e
Displaces the beams 9a and 9b in the extending direction, and bends the beams 9a and 9b to bend the piezoelectric detecting elements 14e and 15e. As a result, a voltage signal based on the Coriolis force is generated from the piezoelectric detection elements 14e and 15e. Further, the angular velocity detecting element 1
When an acceleration is applied to the vibrating body 11 from an arbitrary direction, the lower end of the weight 9e is greatly displaced in the direction of the acceleration to deflect the four beams 9a, 9b, 9c, 9d, and the piezoelectric detecting element 14
e and 15e generate an output including an acceleration signal component. In the case of the angular velocity detecting element 1, the capacitance-voltage conversion circuit 2 shown in FIG.
The output of e is directly input to the acceleration component removing circuit 8.

[0014]

As shown in FIG. 8, the vibrating body 11 of the angular velocity detecting element 1 vibrates under the influence of Coriolis force when an angular velocity is applied. Contains a drive signal component and an angular velocity signal component, and vibrates under the influence of an acceleration force when an acceleration is applied. Therefore, the output of the angular velocity detection element 1 includes a drive signal component and an acceleration signal component, Further, when the angular velocity and the acceleration are added, the output of the angular velocity detecting element 1 includes all of the drive signal component, the angular velocity signal component, and the acceleration signal component.

However, although the angular velocity and the acceleration have completely different physical quantities, the angular velocity detecting element 1 outputs not only a signal in which the angular velocity signal component is superimposed on the acceleration signal component, but also a unit gravity acceleration (1 gravity acceleration). ) To which the output of the angular velocity detecting element 1 is expressed by the unit angular velocity (1 degree /
Second) plus 100 times the output of the angular velocity detecting element 1
0 to 10000 times larger and difficult to distinguish. In particular, in applications such as automobiles, the acceleration sensitivity (output per unit gravitational acceleration) is converted into angular velocity sensitivity (output per unit angular velocity) as 1 ° / s / G as the output of the angular velocity detecting element 1.
(Degree / second / gravity) or less, but it was difficult to realize.

The acceleration signal component included in the output of the angular velocity detecting element 1 is, for example, 2
It has a frequency component up to about kHz, and when an excessive acceleration is applied, each part of the circuit block in FIG. 6 exceeds the range permitted by the power supply voltage, and an angular velocity signal may be obtained. In some cases, it was not possible.

An object of the present invention is to provide a gyro device capable of reliably extracting an angular velocity signal even when an angular velocity and an acceleration are simultaneously applied to an angular velocity detecting element.

[0018]

According to a first aspect of the present invention, there is provided a gyro apparatus comprising: a vibrating body;
The vibrating body includes a supporting means for oscillating the vibrating body, a driving means for vibrating the vibrating body in a fixed direction, and a detecting means for detecting a displacement of the vibrating body based on a Coriolis force applied to the vibrating body. The feature is that an acceleration signal component removing circuit for removing a signal component generated by the acceleration acting on the vibrating body from the output of the detecting means is provided.

In this means, the supporting means for supporting the vibrating body comprises a supporting portion and a beam, and a beam is interposed between the vibrating body and the supporting portion to allow the vibrating body to vibrate by bending the beam. . The support is fixed to a support frame 7 as shown in FIG. 6 or a support substrate (not shown). The driving means for driving the vibrating body includes a piezoelectric driving section in which a piezoelectric element is attached to a driving electrode section or a beam section as shown in FIG. 6, and a driving circuit for supplying a driving signal to these. The drive signal is a sine wave AC signal, and the frequency is determined according to the use of the gyro device. This frequency is, for example, 3 kHz to 20 kHz. When a drive signal is supplied from the drive circuit to the drive electrode unit and the piezoelectric drive unit, the vibrator vibrates in a certain direction with a certain amplitude. The detection means includes a detection electrode section or a piezoelectric detection section similar to the drive means, and the detection electrode section is provided with a capacitance-voltage conversion circuit. If no angular velocity or acceleration acts on the vibrating body, no output is generated on the detecting means, but if any of the angular velocity or acceleration acts on, the output is generated on the detecting means according to the magnitude.

The acceleration signal component removing circuit removes a signal component generated by acceleration from the output of the detecting means. When an acceleration is applied to the vibrating body, the vibrating body vibrates and an output is generated. The vibration frequency due to the acceleration is assumed to be up to about 2 kHz in consideration of the application of the gyro device. When the frequency of the output due to the largest acceleration expected in a specific application is the maximum acceleration frequency, the frequency of the drive signal is set to a frequency higher than the maximum acceleration frequency, for example, 3 kHz.
In addition, the acceleration signal component removal circuit is configured to pass only a frequency higher than the maximum acceleration frequency and to block a signal having a frequency lower than the maximum acceleration frequency.

In the gyro device according to a second aspect, the driving means includes a driving electrode section for driving the vibrating body with electrostatic force.
The detection means includes a detection electrode unit that detects vibration of the vibrating body as a change in capacitance, and a capacitance-voltage conversion circuit that converts a change in capacitance in the detection electrode unit into a change in voltage. An acceleration signal component removing circuit is connected to an output terminal of the capacitance-voltage conversion circuit.

According to the above-described structure, the drive electrode portion has two comb-shaped electrodes, and the flat surfaces of the two electrodes are opposed to each other via a minute space. The vibrating body is vibrated by electrostatic force when a drive signal is applied from a circuit. The detection electrode unit has the same configuration as the drive electrode unit, extracts a change in the capacitance generated between the two electrodes, inputs the change to the capacitance-voltage conversion circuit, and converts it into a voltage signal in the capacitance-voltage conversion circuit. The acceleration signal component removal circuit
Connected to the capacitance-voltage conversion circuit to block the passage of the acceleration signal component included in the voltage signal of the capacitance-voltage conversion circuit,
The angular velocity signal component and the drive signal component are passed.

According to a third aspect of the present invention, there is provided a gyro apparatus including a monitor for detecting an amplitude of vibration of the vibrating body. The vibrating body is excited by the drive signal, but the monitor means directly detects the state of vibration of the vibrating body and generates a monitor signal.
The monitor means has a monitor electrode part having the same electrode structure as the drive means. The monitor electrode part is provided with a capacitance-voltage conversion circuit, and converts a change in capacitance at the monitor electrode part into a voltage signal. are doing.

In the gyro apparatus according to a fourth aspect, the acceleration signal component removing circuit is constituted by a filter circuit for cutting off a frequency component of the acceleration signal, and cuts off the frequency of a drive signal for driving the vibrating body by cutting off the filter circuit. That is, it is set higher than the frequency. Since the frequency of the acceleration in the environment where the gyro device is used is mostly included in the range of DC to about 2 kHz, the cut-off frequency of the filter circuit is set to, for example, 3 kHz while considering the frequency of the drive signal.
Hz or higher to prevent the passage of the acceleration signal component. Since the frequency of the drive signal is set higher than the cutoff frequency of the filter circuit, the acceleration signal component passes without being attenuated by the filter circuit. For example, when the cutoff frequency of the filter circuit is 3 kHz, the frequency of the drive signal is set to a frequency higher than 3 kHz.

In the gyro apparatus according to a fifth aspect, the filter circuit is a high-pass filter or a band-pass filter that passes a frequency component of the angular velocity signal. The frequency of the drive signal for driving the vibrating body can be determined in consideration of the frequency of acceleration that can be assumed according to the use of the gyro device. Therefore, by setting the frequency of the drive signal higher than the frequency of the acceleration, the high-pass filter or the band-pass filter passes the frequency component of the angular velocity and the frequency component of the drive signal and is not included in the bands of these frequencies. Attenuate the acceleration signal component.

[0026]

Embodiments of the present invention will be described below with reference to the drawings. 6 and 7 are denoted by the same reference numerals, and description thereof is omitted. In FIG. 1, the acceleration signal component removing circuit 8 is connected between the capacitance-voltage converting circuit 2 and the signal separating circuit 4. The acceleration signal component removing circuit 8 is composed of filter circuits 81 and 82, and the filter circuit 81
It is connected between the source 21c of T21 and the amplifier 41. Further, the filter circuit 82 includes the source 2 of the FET 22.
2c and the amplifier 42. The filter circuits 81 and 82 are high-pass filters or band-pass filters that pass the frequency component of the angular velocity and the frequency component of the drive signal, and their cutoff frequencies are frequencies that attenuate the frequency component of the acceleration signal, for example, 3 It is set in the range of 10 to 10 kHz. In the high-pass filter, the frequency of the drive signal is set to a frequency higher than the cutoff frequency,
The angular velocity signal component is separated and taken out from the acceleration signal component.
In the band-pass filter, the frequency of the drive signal is set within the frequency band allowed by the filter, and only the frequency component of the angular velocity and the frequency component of the drive signal are passed.

For example, when the maximum acceleration frequency of the acceleration assumed in the application of the gyro device is about 2 kHz, the cutoff frequency of the filter circuits 81 and 82, ie,-
The frequency when the signal is attenuated by 3 dB is set to 10 kHz, and the frequency of the drive signal is set to, for example, 15 kHz. When the maximum acceleration frequency is about 100 Hz, the cutoff frequency of the filter circuits 81 and 82 is set to 3 kHz, and the frequency of the drive signal at this time is set to 3 kHz or more. In the case of a band-pass filter, the frequency of the drive signal is determined by the lower cutoff frequency and the upper cutoff frequency.

FIG. 2 shows an embodiment of the filter circuit. 2A and 2B show a high-pass filter, and FIG. 2C shows a band-pass filter. In the example shown in FIG. 2A, the space between two capacitors C1 and C2 connected in series is grounded via a coil L1. FIG. 2 (b)
In the example, the resistor R1 is connected between the negative input terminal and the output terminal of the differential amplifier A, and a series circuit of the resistor R2 and the capacitor C3 is connected to the negative input terminal to input a signal. Furthermore,
In the example of FIG. 2C, the coils L2 and L3 and the capacitor C
4, and two series circuits C5 are grounded via a parallel circuit of a coil L4 and a capacitor C6.

FIG. 3 is a circuit block diagram showing another embodiment of the present invention. 1, 6, and 7 are denoted by the same reference numerals, and description thereof is omitted. The circuit block diagram shown in FIG. 3 shows a mode in which a monitor output is obtained from the angular velocity detection element 1 and self-excited oscillation is performed. In FIG. 3, the angular velocity detecting element 1 is provided with a new monitor electrode section 18 on the side of the drive electrode section 12 or the drive electrode section 13, and electrostatically detects the state of drive vibration of the vibrating body 11. ing. The monitor electrode section 18 is connected to the gate 23a of the FET 23 that forms the capacitance-voltage conversion circuit 20.
The drain 23b of the FET 23 is connected to a DC power supply Vcc, and the source 23c of the FET 23 is grounded via a source resistor 23d, and converts a change in capacitance caused by the vibration of the vibrating body 11 into a change in voltage. ing. The capacitance-voltage conversion circuit 20 is connected to the acceleration signal component removal circuit 80. The acceleration signal component removing circuit 80 includes a filter circuit 83 and an amplifier 84, and an output terminal of the amplifier 84 is connected to the drive circuit 5. The filter circuit 83 has the same configuration as the filter circuits 81 and 82 of the acceleration signal component removing circuit 8. The output circuit 60 is connected to the acceleration signal component removal circuit 82. This output circuit 60
Is connected to a filter circuit 81 and amplifies its output signal, an amplifier 66 is connected to a filter circuit 82 and amplifies its output signal, and is connected to the output terminals of these two amplifiers 65 and 66. Two amplifiers 65,
A differential amplifier 64 for differentially amplifying the output signal 66 is provided. The differential amplifier 64 is connected to the synchronous detection circuit 61 as in FIG.

With this configuration, when the vibrating body 11 is driven and vibrated, a capacitance that changes at a frequency corresponding to the drive signal appears on the monitor electrode portion 18, and the change in the capacitance is formed by the FET 23. It is converted into a voltage signal by a source follower circuit. This voltage signal has only the frequency component of the drive signal when acceleration is not acting on the vibrating body 11, and when the acceleration is acting, the frequency component of the drive signal and the frequency component of the acceleration signal are superimposed. Frequency component. The voltage signal converted by the capacitance-voltage converter 20 is F
The signal is input from the source 23c of the ET 23 to the filter circuit 83. In this filter circuit 83, the frequency component of the acceleration signal is removed. The drive signal component amplified by the amplifier 84 is input to the drive circuit 5, and the drive vibration of the angular velocity detecting element 1 is continued.

FIG. 4 shows an embodiment of the angular velocity detecting element 1. The difference from FIG. 7 is that a monitor electrode section 18 is provided. The monitor electrode section 18 is provided on the outer frame vibrating section 16 adjacent to the drive electrode section 13. The monitor electrode section 18 is, as shown in an enlarged manner in FIG.
And a monitor movable comb-shaped electrode 18b, 18c, which is connected to the monitor movable comb-shaped electrode 18b by a plate-shaped connection electrode 18a. It is composed of a plate-shaped monitor fixed comb electrode 18d and a monitor fixed electrode 18e supporting the monitor fixed comb electrode 18d.

When the vibrating body 11 of the angular velocity detecting element 1 vibrates in the direction of the arrow x in FIG. 5, that is, in the horizontal direction of the drawing, according to the drive signal, the capacitance change that changes with the vibration frequency of the vibrating body 11 is applied to the monitor fixed electrode 18e. Appears. At this time, vibrator 1
When the Coriolis force is applied to 1, the inner frame vibrating part 17 is displaced in a direction perpendicular to the arrow x, but the outer frame vibrating part 16
Since a and 16b are not bent, they are not displaced in a direction perpendicular to the arrow x. The monitor fixed electrode 18d and the monitor movable electrode 1
Assuming that the capacitance between the outer frame vibrating portion 16 and the outer frame vibrating portion 16 is displaced in a direction perpendicular to the arrow x, the capacitance between the outer frame vibrating portion 16 and the outer frame vibrating portion 16 is displaced in the direction perpendicular to the arrow x. (C1 + C2) does not change. Therefore, even if an angular velocity is applied to the angular velocity detecting element 1, the monitor fixed electrode 18
The capacitance change occurring at d does not include the angular velocity signal component. In addition, when an acceleration in an arbitrary direction acts on the vibrating body 11, the vibration has a vibration component in the direction of the arrow x in FIG. 5, so that the capacitance change generated in the monitor fixed electrode 18e includes an acceleration signal component. . This acceleration signal component is attenuated by the filter circuit 83 of the acceleration signal component removal circuit 80. Therefore, only the drive signal component is fed back to the drive circuit 5, and the oscillation of the drive circuit 5 is continued. On the other hand, in the output circuit 60, the two signals input from the filter circuits 81 and 82 are amplified by the amplifiers 65 and 66, respectively, and then differentially amplified by the differential amplifier 64. As in FIG. Performs synchronous detection to obtain an angular velocity signal. The function of the offset adjusting circuit 62 is the same as that of FIG.

In the circuit blocks shown in FIGS. 1 and 3, the driving of the angular velocity detecting element 1 has been described as self-excited oscillation. However, the driving circuit 5 may be provided with an oscillating circuit and may be driven separately. In this case, a drive signal component feedback circuit is not required. As shown by a dotted line in FIG. 9, a monitor piezoelectric element 9f serving as a monitor piezoelectric section is provided on the beams 9c and 9d on which the piezoelectric drive elements 12e and 13e are formed, and the signal voltage of the monitor piezoelectric element 9f is filtered by the filter shown in FIG. A self-excited oscillation system for driving the angular velocity detecting element 1 by inputting to the circuit 83 may be formed.

[0034]

According to the first aspect of the present invention, the acceleration signal component generated due to the acceleration applied to the vibrating body is reliably attenuated by the acceleration signal component removing circuit, so that the gyro device does not malfunction due to the acceleration. In addition, even if the angular velocity and the acceleration simultaneously act on the vibrating body, only the acceleration signal component is attenuated, and the angular velocity signal component can be extracted.

Further, even if the acceleration signal component becomes large due to the addition of excessive acceleration to the vibrating body, the amplitude of the signal in each signal circuit of the gyro device fluctuates more than allowable. And the angular velocity signal can be reliably obtained.

According to the second aspect of the present invention, the acceleration signal component removing circuit is connected to the output terminal of the capacitance-voltage conversion circuit.
The acceleration signal component included in the change in the capacitance of the detection electrode unit can be removed immediately after conversion into a voltage signal.
Therefore, it becomes easy to separate the angular velocity signal component from the drive signal component.

According to a third aspect of the present invention, the monitor means
Since a monitor signal corresponding to the vibration amplitude of the vibrating body is detected, a self-excited oscillation driving circuit that continuously excites the vibrating body using this monitor signal can be configured. The signal can be used as a control signal for controlling the amplitude and phase of the drive signal.

According to a fourth aspect of the present invention, the acceleration signal component removing circuit is constituted by a filter circuit and its cutoff frequency is set higher than the frequency of the acceleration signal component.
Only the acceleration signal component can be reliably attenuated, and the angular velocity signal component can be extracted.

According to the fifth aspect of the present invention, since a high-pass filter or a band-pass filter is used as the filter circuit, the cut-off frequency of the high-pass filter is set to a frequency at which the acceleration signal component is attenuated, and By setting the frequency of the drive signal higher than the cutoff frequency, the angular velocity signal component can be reliably attenuated without affecting the angular velocity signal component. By determining the passing frequency, an angular velocity signal can be obtained reliably.

[Brief description of the drawings]

FIG. 1 is a circuit block diagram of a gyro device according to the present invention.

FIGS. 2A and 2B show a high-pass filter and FIG. 2C shows a band-pass filter.

FIG. 3 is a circuit block diagram showing another embodiment of the gyro device according to the present invention.

FIG. 4 is a plan view showing an example of an angular velocity detecting element used in the gyro device according to the present invention.

FIG. 5 is an enlarged plan view of the monitor electrode unit of FIG.

FIG. 6 is a circuit block diagram of a conventional gyro device.

FIG. 7 is a plan view showing an example of a conventional angular velocity detecting element.

FIG. 8 is a force vector diagram.

FIG. 9 is a plan view showing another example of a conventional angular velocity detecting element.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Acceleration detection element 2, 20 Capacitance voltage conversion circuit 4 Signal separation circuit 5 Drive circuit 6, 60 output circuit 8, 80 Acceleration signal removal circuit 9f Monitor piezoelectric element 11 Vibration body 12, 13 Drive electrode part 14, 15 Detection electrode part 18 Monitor electrode 81, 82, 83 Filter circuit

Claims (5)

[Claims] 1. A vibrating body, supporting means for oscillating the vibrating body, driving means for vibrating the vibrating body in a fixed direction, and detecting displacement of the vibrating body based on Coriolis force applied to the vibrating body. A gyro apparatus comprising: a gyro apparatus, comprising: an acceleration signal component removing circuit for removing a signal component generated by an acceleration acting on the vibrator from an output of the detecting means. 2. The driving unit includes a driving electrode unit that drives the vibrating body with electrostatic force. The detecting unit detects a vibration of the vibrating body as a change in capacitance. And a capacitance-voltage conversion circuit for converting a change in electrostatic capacity into a change in voltage. A circuit for removing an acceleration signal component is connected to an output terminal of the capacitance-voltage conversion circuit. A gyro device as described. 3. The gyro device according to claim 1, further comprising monitor means for detecting an amplitude of vibration of the vibrating body. 4. An acceleration signal component removing circuit comprising a filter circuit for cutting off a frequency component of an acceleration signal, and a frequency of a drive signal for driving the vibrating body is set higher than a cutoff frequency of the filter circuit. The gyro device according to claim 1 or claim 2 or claim 3. 5. The gyro device according to claim 4, wherein the filter circuit is a high-pass filter or a band-pass filter that passes a frequency component of the angular velocity signal.