JPH08178666A - Piezoelectric vibration gyroscope - Google Patents

Abstract

PURPOSE: To compensate the reduction in detecting sensitivity accompanying the downsizing of a piezoelectric vibration gyroscope by improving the structure of a piezoelectric vibrator and the control circuit of the piezoelectric vibration gyroscope, keep the detecting sensitivity of the conventional piezoelectric vibration gyroscope, and realize the downsizing of the piezoelectric vibration gyroscope while keeping mass productivity. CONSTITUTION: A piezoelectric vibration gyroscope has a piezoelectric vibrator having four band electrodes 11, 12, 13, 14 for polarization, driving and detection arranged on the side surface of a piezoelectric ceramic cylinder 1 in parallel to the longitudinal direction of the piezoelectric ceramic cylinder 1. Of the four band electrodes 11, 12, 13, 14 of the piezoelectric vibrator, two opposed electrodes 11, 12 are mutually driven in reverse phases to bend and vibrate the piezoelectric vibrator, and the current signals obtained from the remaining two electrodes 13, 14 are detected by a virtual grounding type current detecting circuit using operation amplifiers 16, 17.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric vibrating gyroscope using a rod-shaped bending vibrator, among gyroscopes used for camera-shake prevention of camera-integrated VTRs and navigation systems of automobiles.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyro is a gyroscope that utilizes a mechanical phenomenon in which a Coriolis force is generated in a direction perpendicular to the vibrating direction when a rotating angular velocity is applied to a vibrating object. In a vibration system configured to be able to excite and detect in two directions orthogonal to each other, with one vibration being excited, the vibrator itself is centered on an axis parallel to the line where the two vibrating planes intersect. When rotated, a force acts in the direction perpendicular to this vibration due to the action of the Coriolis force described above, and the other vibration is excited. Since the magnitude of this vibration is proportional to the magnitude of the vibration on the input side and the rotation angular velocity, when the input voltage is constant, the magnitude of the rotation angular velocity can be obtained from the magnitude of the output voltage.

In FIG. 3, six strip-shaped electrodes 2, 3, 4, are formed on the side surface of a piezoelectric ceramic cylinder 1 having a shape of φ2.0 × 10.
1 is a configuration diagram of a piezoelectric vibration gyro including a cross-sectional view of a conventional piezoelectric vibrator (hereinafter, referred to as a 6-electrode type vibrator) in which 5, 6, and 7 are formed. FIG. 4 shows an equivalent circuit of this 6-electrode type vibrator.

In this conventional example, as shown in FIG. 4, driving and detection of bending vibration are performed by using terminals 8 and 9 by utilizing the piezoelectric effect between the six electrodes which are polarized in the direction of the arrow shown in FIG. , 10 to realize a piezoelectric vibration gyro.

Id in FIG. 4 corresponds to the magnitude of drive vibration, and can be expressed by the following equation (1).

[0006]

[Equation 1]

[0007]

In the above equation 1,
It can be seen that the driving efficiency is lowered by the load resistances R2, R3 and the parallel capacitors Cd2, Cd3 connected to the detection terminal. Considering a gyro drive detection circuit, a large drive vibration can be efficiently obtained within a limited voltage range.
One of the design indexes is to improve the detection sensitivity. Here, in order to miniaturize the conventional piezoelectric vibrating gyro, it is necessary to miniaturize the piezoelectric vibrator, and it is necessary to form electrodes at a fine pitch, which leads to a decrease in accuracy, difficulty in manufacturing, and vibration due to miniaturization. The increase in the resonance frequency of the child causes a problem that the detection sensitivity of the piezoelectric vibrating gyro is reduced with the conventional structure.

An object of the present invention is to improve the structure of the piezoelectric vibrator and the control circuit of the piezoelectric vibrating gyroscope to reduce the decrease in detection sensitivity due to the miniaturization of the piezoelectric vibrating gyroscope described above. It is to realize the miniaturization of the piezoelectric vibrating gyro while maintaining the detection sensitivity of, and further maintaining the mass productivity.

[0009]

According to the present invention, there is provided a piezoelectric vibrator in which four strip-shaped electrodes for polarization, driving and detection are provided on a side surface of a piezoelectric ceramic cylinder in parallel with a length direction of the piezoelectric ceramic cylinder. In the piezoelectric vibration gyro used,
Of the four electrodes of the piezoelectric vibrator, two electrodes facing each other are driven in opposite phases to cause the piezoelectric vibrator to flexurally vibrate, and a current signal obtained from the remaining two electrodes is of a virtual ground type using an operational amplifier. A piezoelectric vibration gyro characterized by being detected by a current detection circuit is obtained.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A piezoelectric vibrating gyroscope according to an embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 shows a piezoelectric vibrator in which four strip electrodes are formed on the side surface of the piezoelectric ceramic cylinder 1 in parallel with the length direction of the piezoelectric ceramic cylinder 1 (hereinafter referred to as "the piezoelectric vibrator").
It is called a four-electrode vibrator. ) Shows a configuration diagram of a piezoelectric vibrating gyro including a sectional view of FIG.

The strip-shaped electrodes 11 and 12 in FIG. 1 are located symmetrically with respect to the central axis of the piezoelectric ceramic cylinder 1 and are used as driving electrodes. Polarization treatment is performed in the direction of the arrow in FIG. 1 in advance, and drive voltages of opposite phases are applied to the strip electrodes 11 and 12 from the signal source 15. The strip-shaped electrodes 13 and 14 in FIG. 1 are located symmetrically with respect to a plane that flexurally vibrates when driven, and are used as electrodes for both detection and grounding. Further, the strip electrodes 13 and 14 have operational amplifiers 16 and 1, respectively.
7 and a current detection circuit using a feedback resistor R _F are connected. Output current I from the strip electrodes 13 and 14
_o is converted into a voltage V _o (V _o = I _o × R _F ) and output from the current detection circuit. The strip electrodes 13 and 14 are grounded to the reference voltage by the virtual grounding function of the operational amplifiers 16 and 17 and serve as a reference for the drive voltage.

FIG. 2 shows an equivalent circuit of the four-electrode type vibrator.

The load resistors R2 and R3 and the parallel capacitors Cd2 and Cd connected to the detection terminals in the above-mentioned conventional example.
3 (see FIG. 4) is the operational amplifier 1 of FIG.
Since the load resistances R2 and R3 are R2 = R3 = 0 due to the virtual grounding functions of 6 and 17, the parallel capacitances Cd2 and Cd3.
Is canceled and an equivalent circuit as shown in FIG. 2 is obtained.
Id ′ in FIG. 2 corresponds to the magnitude of drive vibration, and
It can be expressed by a formula.

[0015]

[Equation 2]

According to the above equation (2), compared with the above equation (1), the denominator load resistors R2 and R3 and the parallel capacitance Cd.
The driving efficiency is improved by 2 and Cd3, and the driving force is doubled by the reverse phase driving from the two terminals.

[0017]

According to the piezoelectric vibrating gyroscope of the present invention, mass productivity is improved by using a four-electrode vibrator having a smaller number of electrodes than before, and drive efficiency is improved by using a current detection circuit. It

Further, since the driving force is doubled by the anti-phase driving from the two terminals, compared with the conventional piezoelectric vibration gyro,
The detection sensitivity can be increased and further downsizing can be realized.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a piezoelectric vibrating gyro including a sectional view of a piezoelectric vibrator according to an embodiment of the invention.

FIG. 2 is a diagram showing an equivalent circuit of the piezoelectric vibration gyro shown in FIG.

FIG. 3 is a diagram showing a configuration of a piezoelectric vibration gyro including a cross-sectional view of a conventional piezoelectric vibrator.

4 is a diagram showing an equivalent circuit of the conventional piezoelectric vibration gyro shown in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric ceramics cylinder 2,3,4,5,6,7 band electrode 8 drive terminal 9 and 10 detection terminal 11 and 12 drive electrode 15 signal source 16 and 17 operational amplifier

Claims (1)

[Claims] 1. A piezoelectric vibrating gyroscope using a piezoelectric vibrator in which four strip-shaped electrodes for polarization and driving / detection are provided on the side surface of the piezoelectric ceramic cylinder in parallel with the length direction of the piezoelectric ceramic cylinder. Virtual ground-type current detection circuit using op amps to drive the piezoelectric vibrator in flexural vibration by driving two opposite electrodes out of the four electrodes of the child, and causing the current signals obtained from the remaining two electrodes to use an operational amplifier. A piezoelectric vibration gyro characterized by being detected by.