JPH10221083A - Vibration-type gyro apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a vibration-type gyro apparatus by which the temperature characteristic of an output signal in a detecting system is improved in the same manner as that in a driving system by a method wherein a feedback control signal which is formed for the temperature compensation of a mechanical Q-value in the driving system is utilized as the temperature compensation of a mechanical Q-value in the detecting system. SOLUTION: A vibration-type gyro apparatus is provided at least with a driving electrode part 2 which drives a vibrating body, with a monitoring electrode part 3 which measures the amplitude of the vibration of the vibrating body and with detecting electrode parts 4, 5 which detect a vibration based on the Coriolis force. In the vibration-type gyro apparatus, detection signals of the detecting electrode parts 4, 5 based on the Coriolis force are corrected by using a feedback control signal (s) which is formed on the basis of the displacement signal of the monitoring electrode part 3 and which controls the amplitude of the vibration of the vibrating body so as to become constant.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration type gyro device used for a camera shake preventing camera, a car navigation device and the like.

[0002]

2. Description of the Related Art A conventional vibration type gyro device is, for example,
It comprises a functional block circuit as shown in FIG. 2
Reference numeral 2 denotes an angular velocity sensor as shown in FIG. L-shaped support beam 3 having rectangular vibrating body 31 provided at its four corners
It is coupled to the fixing portion 33 so as to be able to vibrate through the second member 2. The movable comb electrodes 34 are provided on both sides of the short side of the vibrating body 31.
a and 35a are provided. In addition, fixed comb-tooth electrodes 34b and 35b which form capacitors in opposition to these movable comb-tooth electrodes 34a and 35a are also provided. And
The fixed comb electrodes 34b, 35b are fixed electrodes 36a,
37a. The left movable comb electrode 34a and the fixed comb electrode 34b constitute a drive electrode unit 36, and the right movable comb electrode 35a and the fixed comb electrode 35b.
Constitutes the monitor electrode unit 37.

Further, on both sides of the long side of the vibrating body 31,
Elongated detection electrodes 38a and 38b are provided at intervals. And, these detection electrodes 38a, 3
A capacitor is formed between 8b and the vibrating body 31.

A vibrating body 31, movable comb electrodes 34a and 35a, and an L-shaped support beam 32 indicated by a point set part can float freely from a substrate (not shown) and freely vibrate.

Next, the general operation of the angular velocity sensor 22 will be described. When the peak value of the driving electrode portion 36 is 0 V and 5
The vibrating body 31 is vibrated in the X-axis direction by applying an AC voltage of V. Then, the monitor electrode unit 37 detects a change amount of the capacitance due to the vibration of the vibrating body 31 (the movable comb electrode 35a). As described above, when the angular velocity sensor 22 rotates about its central axis perpendicular to the paper surface while the angular velocity sensor 22 is vibrating, the vibrating body 31 also vibrates in the Y-axis direction due to Coriolis force. become. Then, the capacitance that increases or decreases alternately appears on the detection electrodes 38a and 38b.

In FIG. 3, reference numeral 20 denotes an oscillation circuit, which is several k to
It oscillates at a frequency f of several tens of kHz. This oscillation frequency f
A bias voltage is superimposed on the oscillation voltage of the above, and this is used as a drive signal 21. 23 is a signal processing circuit, which is an angular velocity sensor 22
The change amount (displacement signal) of the capacitance detected by the monitor electrode unit 37 is converted into a voltage, and the converted voltage (monitor voltage) is amplified. Reference numeral 24 denotes a feedback circuit having an addition / subtraction circuit, which compares the input monitor voltage with a reference voltage, adjusts the oscillation voltage of the oscillation circuit 20 according to the magnitude of the reference voltage, and adjusts the oscillation amplitude of the oscillator 31 of the angular velocity sensor 22. Control to constant.

The closed loop circuit of the oscillation circuit 20 to the feedback circuit 24 constitutes a control circuit of a drive system of the vibration type gyro device. In the vibrating gyro device, not only the elastic constant but also the viscous resistance of air causes the mechanical Q of the structure of the driving system to decrease due to the temperature change, and the detection sensitivity of the Coriolis force decreases. That is, the mechanical Q value is determined by the temperature coefficient of the elastic constant of the material such as the vibrating body and the movable comb electrode constituting the vibrating gyro device, and the external temperature such as the temperature and humidity of the air in which these structures are placed. It also fluctuates depending on environmental conditions. In particular, in a vibrating gyro device manufactured by a semiconductor microfabrication technique using silicon as a material, the mechanical Q of a structure that fluctuates due to the viscous resistance of air changes. The closed loop circuit controls the amplitude of the vibration of the vibrating body 31 to be a constant amplitude in order to prevent the amplitude from decreasing due to the decrease in the mechanical Q value.

Next, the detection system will be described. The amount of change in capacitance (detection signal) detected by the detection electrodes 38a and 38b based on the vibration of the Coriolis force is determined by the signal processing circuit 2
5 and converted into a voltage (detection voltage). This detection voltage is input to the phase detection circuit 26, and phase detection is performed using the displacement signal from the feedback circuit 24 as a reference phase, and an angular velocity signal based on Coriolis force is obtained. Then, this angular velocity signal is amplified and output.

[0009]

However, the conventional vibrating gyro apparatus has a vibration body 31 of the acceleration sensor 22.
Is provided with a feedback circuit of a drive system for controlling the amplitude to a constant amplitude against the viscous resistance of air due to temperature change, but the mechanical Q value of the detection system is controlled against the viscous resistance of air due to temperature change. No circuit is provided for compensating the detection sensitivity due to the fluctuation of the constant.

That is, as described above, the mechanical Q value of the vibrating body 31 largely depends on the elastic constant such as the Young's modulus of the vibrating body 31, particularly the viscosity of the surrounding gas. When the vibrating body 31 operates under atmospheric pressure, the mechanical Q value is affected by the temperature-dependent viscosity of air. In the vibrating gyro device, a loop control is performed via a feedback circuit so that the vibration displacement of the vibrating body 31 becomes constant. That is, even if the viscosity of the air changes due to the temperature change and the viscous resistance of the air changes, the driving electrode unit 36 and the monitor electrode unit 37
And the vibration amplitude of the drive system including the vibrating body 31 is kept constant.

However, in the conventional vibrating gyro apparatus, the detecting electrode portions 38a and 38b and the vibrating body 3
Although the detection system including No. 1 operates under the same air viscosity as the vibration system, the detection system does not have the correction means based on the viscous resistance of the air like the drive system. Therefore, in the conventional vibration type gyro device, the mechanical Q value of the detection system is reduced, and the detection sensitivity is reduced.

Therefore, the present invention utilizes the feedback control signal formed for temperature compensation of the mechanical Q value of the drive system also for temperature compensation of the mechanical Q value of the detection system. Similarly, another object of the present invention is to improve the temperature characteristics of a detection signal of a detection system.

[0013]

The present invention comprises at least a driving electrode section for driving a vibrating body, a monitor electrode section for measuring the amplitude of vibration of the vibrating body, and a detecting electrode section for detecting vibration based on Coriolis force. In the vibrating gyro device comprising: a feedback control signal formed based on a displacement signal of the monitor electrode unit, and controlling the amplitude of vibration of the vibrating body to be constant, based on the Coriolis force. This is for correcting the detection signal of the detection electrode section.

According to the present invention, the amplitude of the vibration of the vibrating body is detected by the monitor electrode portion as the amount of change in capacitance (displacement signal).
The detected amount of electricity is converted into, for example, a voltage (monitor voltage), and the monitor voltage is compared with a set reference voltage to form a feedback control signal. The feedback control signal is fed back to the oscillation circuit of the driving system including the vibrating body and the driving electrode unit, and is also input to the signal processing circuit of the detection system including the vibrating body and the detecting electrode unit.
In addition, while controlling the fluctuation of the amplitude of the vibration of the vibrating body of the drive system due to the fluctuation of the viscous resistance of the air based on the temperature change, the fluctuation of the vibration of the vibrating body of the detection system due to the viscous resistance of the air based on the temperature change. Compensate for fluctuations in detection sensitivity. This compensation value does not correspond one-to-one with the compensation value for the drive system. This is because in the structure and operation of the vibration type gyro device, the mechanical Q of the drive system and the mechanical Q of the detection system are different.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Next, an embodiment of a vibration type gyro device according to the present invention will be described with reference to FIGS. Note that FIG. 1 relates to the improvement of the conventional vibration type gyro device shown in FIG. 3, and therefore, the same parts as those in FIG.

First, the structure and function of the angular velocity sensor 10, which is the center of the present embodiment, will be described with reference to FIG. Reference numeral 1 denotes a rectangular plate-shaped vibrating body, and movable handles 2a and 3a extend at right angles and in both directions from both ends in the longitudinal direction. On one side of the movable handles 2a, 3a, a plurality of parallel movable comb-tooth electrodes 2b, 3b (point set portions) are formed at right angles. The movable comb electrode 2
b, 3b and a plurality of fixed comb-teeth electrodes 2c, 3c forming a capacitor, and these fixed comb-teeth electrodes 2c, 3c
Fixed electrodes 2d and 3d (white portions) which are connected at right angles to c are formed on the surface of a substrate (not shown). The left movable comb electrode 2b and the fixed comb electrode 2c constitute the drive electrode unit 2, and the right movable comb electrode 3b and the fixed comb electrode 3c constitute the monitor electrode unit 3.

Since the movable comb electrodes 2b and 3b of the drive electrode section 2 and the monitor electrode section 3 and the vibrating body 1 are integrally formed of silicon using a semiconductor fine processing technique, their vibration displacements are reduced. Will be the same. Therefore, the monitor electrode unit 3 functions as a monitor that detects the displacement of the drive electrode unit 2 and the vibrating body 1 via the capacitance.

A plurality of movable handles 4a, 5a extend in a perpendicular direction from both side surfaces of the vibrating body 1, and movable comb electrodes 4b, 5b (point set portions) are formed on both sides thereof. . Also, fixed comb electrodes 4c, 5c (white portions) forming capacitors in opposition to the movable comb electrodes 4b, 5b, fixed patterns 4d, 5d connected thereto, and connected thereto. The fixed electrodes 4e and 5e and the extraction electrodes 4f and 5f are respectively formed on a substrate (not shown).

The upper movable comb electrode 4b and the fixed comb electrode 4c and the lower movable comb electrode 5b and the fixed comb electrode 5c constitute detection electrode portions 4 and 5, respectively.

Further, the vibrating body 1 is supported by the fixed portions 6 and 7 via the U-shaped support beams 6a and 7a respectively coupled to the tips of the movable handles 2a and 3a so as to be able to vibrate in the horizontal plane direction. .

Next, the operation of the angular velocity sensor 10 shown in FIG. 2 will be described. The movable comb electrode 2b of the drive electrode unit 2
And the fixed comb-teeth electrode 2c, for example, an arbitrary bias of 2V
Apply a peak-to-peak AC signal. Then, the movable comb electrode 2b is attracted toward the fixed electrode 2d so as to increase the area of opposition to the fixed comb electrode 2c due to electrostatic force, or the suction is released, and the vibrating body 1 is moved. X
Vibrates in the axial direction. The movable comb electrode 3b of the monitor electrode unit 3 also vibrates in the same manner as the vibrating body 1, and a variable capacitance (displacement signal) is formed between the movable comb electrode 3b and the fixed comb electrode 3c. Is done. By detecting this displacement signal,
The vibration circuit 1 is controlled by a feedback circuit described later so that the amplitude of the vibration of the vibrating body 1 becomes constant.

If the angular velocity sensor 10 rotates about the Z-axis perpendicular to the plane of the drawing while the vibrating body 1 is vibrating in the X-axis direction, vibration due to Coriolis force appears in the Y-axis direction, 1 also vibrates in the Y-axis direction. Then, the capacitance of the detection electrode units 4 and 5 on both sides of the vibrating body 1 increases and the other decreases. By subjecting the increasing / decreasing capacitance (detection signal) to voltage conversion and differential amplification, a vibration component in the X-axis direction is removed, a vibration component due to a Coriolis force in the Y-axis direction is extracted, and the rotational angular velocity and the The rotation angle can be obtained by integration.

Next, the configuration and function of the block circuit will be described with reference to FIG. First, in the driving system, the oscillation circuit 20 includes, for example, a CR oscillation circuit, a Wien bridge oscillation circuit, and the like, and oscillates at a frequency f of several to several tens of kHz. A bias voltage is superimposed on the oscillation voltage of the oscillation frequency f, and this is used as a drive signal 21.

Next, as shown in FIG. 2, the drive signal 21 is applied to the movable comb electrode 2 of the drive electrode section 2 of the angular velocity sensor 10.
b between the fixed comb electrode 2c and the fixed comb electrode 2c to attract the movable comb electrode 2b toward the fixed electrode 2d by electrostatic force.
Further, the suction is released, and the vibrating body 1 is vibrated in the X-axis direction. At this time, since the movable comb electrode 3b of the monitor electrode unit 3 is formed integrally with the movable comb electrode 2b of the drive electrode unit 2 and the vibrator 1 as described above, the movable comb electrode 3b vibrates at the same amplitude as these. The monitor electrode unit 3 detects the displacement of the vibration of the vibrating body 1 as a change in the capacitance.

The amount of change (displacement signal) of the capacitance (C) detected by the monitor electrode unit 3 is input to the signal processing circuit 23. The signal processing circuit 23 converts the change in the capacitance into a voltage, and amplifies the converted voltage (monitor voltage). This monitor voltage is supplied to the feedback circuit 2
4 is input. In the feedback circuit 24, the monitor voltage is compared with a reference voltage of the addition / subtraction circuit. Then, the addition / subtraction circuit subtracts a feedback control signal s such that the output voltage is reduced with respect to the reference voltage when the monitor voltage is larger than the reference voltage, and the output voltage is increased when the monitor voltage is small. It is supplied to the oscillation circuit 20 of the drive system.

Next, details of the feedback control signal s will be described. In FIG. 2, the drive electrode unit 2
Are operated by the drive signal 21 to vibrate the vibrating body 1. Here, for example, it is assumed that the viscosity of air increases due to an increase in ambient temperature. Then, the viscous resistance of the air increases, and the mechanical vibration of the vibrating body 1 is damped by the viscous resistance of the air, so that the mechanical Q value decreases and the amplitude of the vibration decreases. Then, the rate of change in the area of the monitor electrode section 3 that opposes the movable comb electrode 3b and the fixed comb electrode 3c decreases, and the amount of change (displacement signal) in the capacitance detected by the monitor electrode section 3 also decreases. Become. Naturally, the amplitude of the monitor voltage converted from the capacitance (C) to the voltage (V) by the signal processing circuit 23 is also reduced. This monitor voltage is input to the feedback circuit 24 and is compared with the reference voltage of the addition / subtraction circuit, and the difference is voltage-amplified to become the feedback control signal s. The feedback control signal s controls the fluctuation of the amplitude of the vibrating body 1 due to the increase and decrease of the viscous resistance of the air based on the change of the ambient temperature so that the fluctuation becomes constant.

Next, the detection system will be described. In FIG. 2, when the vibrating gyro apparatus 10 is vibrating in the X-axis direction and rotates about the Z-axis located at the center thereof, the vibrating body 1 also vibrates in the Y-axis direction due to Coriolis force. I will be. One of the movable comb electrodes 4b, 5b of the detection electrode units 4, 5 on both sides of the vibrating body 1 approaches the fixed comb electrodes 4c, 5c to increase the capacitance, and the other moves away from the fixed comb electrodes 4c, 5c. The capacitance will decrease. The increasing / decreasing electrostatic capacitance (detection signal) is input to the signal processing circuit 25a, and is converted from the capacitance (C) to a voltage (V).
The detection voltage is formed by differential amplification.

On the other hand, a feedback control signal s from the feedback control circuit 24 is also input to the signal processing circuit 25a, as indicated by a thick line. The feedback control signal s is used to make the amplitude of the vibration in the driving direction of the vibrating body 1 constant, and the feedback control signal s is added to a detection voltage formed based on the detection signal detected by the detection system. By multiplying the control coefficient, the output of the detection voltage is affected by the feedback control signal s. Thus, the detection system for detecting the Coriolis force also performs temperature compensation of the mechanical Q value by viscous resistance of air based on the temperature change, similarly to the drive system. When multiplying the control coefficient of the drive system by the output of the detection system,
The correction value confirmed at the design stage in consideration of the structure of the detection system is simultaneously multiplied.

Ambient temperature information from the temperature sensor 27 is also input to the signal processing circuit 25a, and the detected voltage is further amplified by a compensation coefficient in order to compensate for the temperature characteristic of the temperature coefficient of the viscosity of air. Multiplied in degrees. In the temperature sensor 27, while the feedback circuit 24 compensates for the mechanical Q value of the vibrating body 1 and the like based on the viscous resistance of air due to a temperature change, the temperature compensation for the ambient temperature of the circuit such as the signal processing circuit 25a is performed. Is what you do.

The compensated detection voltage is input to the phase detection circuit 26 and phase-detected. The phase detection circuit 26 takes in the voltage (monitor signal) of the drive system from the drive system, for example, the feedback circuit 24, and uses the monitor signal as a reference phase to have a phase difference of 90 ° with respect to the phase of the monitor signal. Only signals based on a certain Coriolis force are extracted, in other words, noise components other than 90 ° are excluded and output. This output is an angular velocity component based on the Coriolis force, and the rotation angle can be obtained by integrating this output.

[0031]

According to the present invention, the feedback control signal formed for temperature compensation of the mechanical Q value of the drive system is also used as the temperature compensation of the mechanical Q value of the detection system, and the air control based on the temperature change is performed. Controls fluctuations in the amplitude of vibration of the vibrating body of the drive system due to fluctuations in viscous resistance, and at the same time, compensates for fluctuations in the detection signal based on fluctuations in the amplitude of the vibrating body of the detection system due to viscous resistance of air based on temperature changes. be able to.

[Brief description of the drawings]

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

FIG. 2 is a plan view of an angular velocity sensor in the vibration type gyro device according to the embodiment.

FIG. 3 is a block circuit diagram of a conventional vibration type gyro device.

FIG. 4 is a plan view of an angular velocity sensor in a conventional vibration type gyro device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Oscillator 2 Drive electrode part 2b, 3b, 4b, 5b Movable comb electrode 2c, 3c, 4c, 5c Fixed comb tooth electrode 3 Monitor electrode part 4, 5 Detection electrode part 6, 7 Fixed part 6a, 7a U-shape Support beam f Oscillation frequency s Feedback control signal 10 Angular velocity sensor 21 Oscillation circuit 22 Drive signal 23 Signal processing circuit 24 Feedback circuit 25a Signal processing circuit 26 Phase detection circuit 27 Temperature sensor

Claims (1)

[Claims] 1. A driving electrode unit for driving at least a vibrating body, a monitor electrode unit for measuring an amplitude of vibration of the vibrating body,
In a vibration type gyro device including a detection electrode unit for detecting vibration based on Coriolis force, a vibration gyro device is formed based on a displacement signal of the monitor electrode unit, and controls the amplitude of vibration of the vibrating body to be constant. A vibrating gyro device that corrects a detection signal of the detection electrode unit based on a Coriolis force using a feedback control signal to be applied.