JP2622331B2 - Vibrating gyro - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyro for detecting an angular velocity used for, for example, a posture control system and a navigation system mounted on an automobile or the like, and a camera shake correction of a video camera.

[0002]

2. Description of the Related Art As a conventional vibrating gyroscope, for example, the one shown in FIG. 2 is known. In this vibrating gyroscope, a first piezoelectric element 2 is attached to one side surface 1a of a vibrating body 1 having a rectangular cross section, and a second piezoelectric element 3 is attached to another side surface 1b adjacent to the side surface 1a. And vibrator 4
Is composed. The piezoelectric elements 2 and 3 are connected to a driving device 5 via respective impedance elements Z ₁ and Z _2, and a capacitance element 6 is connected to the driving device 5 via another impedance element Z _3. Connected
An AC voltage is simultaneously applied to these piezoelectric elements 2 and 3 and the capacitive element 6 from the driving device 5.

On the other hand, connection points 7, 7 between the impedance elements Z ₁ , Z ₂ and the piezoelectric elements 2, 3
8 is connected to the input terminal of the adder 9, and the output terminal of the adder 9 and the connection point 10 between the impedance element Z ₃ and the capacitive element 6 are connected to the input terminal of the differential amplifier 11. The differential output from the differential amplifier 11 is fed back to the driving device 5. Further, the connection points 7 and 8 are also connected to the input terminal of the differential amplifier 12, and the output of the differential amplifier 12 passes through a low-pass filter 13 including a resistor 13a and a capacitor 13b, and a synchronous detector 14 (here, FET). And an angular velocity detection signal is obtained based on the detection signal output to the output terminal 15 thereof.

In such a vibrating gyroscope, the vibrator 4 can be self-oscillated in the X-axis direction of the orthogonal three-dimensional coordinate system by applying an AC voltage from the driving device 5 to the piezoelectric elements 2 and 3. . That is, when an AC voltage is applied to the piezoelectric elements 2 and 3, the output obtained from the connection points 7 and 8 is equal to the supply voltage from the drive device 5 and the piezoelectric elements 2 and 3 due to the distortion of the piezoelectric elements 2 and 3. , 3 are output as a composite output. Accordingly, if the sum of the two combined outputs is obtained by the adder 9 and the difference between the output and the output corresponding to the supply voltage from the connection point 10 is obtained by the differential amplifier 11, the sum is obtained based on the vibration in the X-axis direction. As a result, only the voltage generated from the piezoelectric elements 2 and 3 is extracted, and the output of the differential amplifier 11 is fed back to the driving device 5, whereby the vibrator 4 self-oscillates.

When the vibrator 4 undergoes rotation about the Z-axis while the vibrator 4 is self-excited in this manner, the vibrator 4 moves in the Y-axis direction due to Coriolis force proportional to its angular velocity. It vibrates, and a difference occurs between the outputs from the connection points 7 and 8. Therefore, if the outputs of the connection points 7 and 8 are differentially amplified by the differential amplifier 12, only the voltage accompanying the generation of the Coriolis force can be separated and detected. To remove the harmonic components contained as a waveform distortion in the differential output, and then perform detection in synchronization with the excitation cycle of the vibrator 4 in the synchronous detector 14 to convert the Coriolis force into a voltage. And an angular velocity detection signal can be obtained based on this.

[0006]

By the way, the voltages generated from the piezoelectric elements 2 and 3 contain harmonic components accompanying the waveform distortion. However, the harmonic component in the differential output may exceed the operating range of the differential amplifier 12 and cause a saturation phenomenon.Therefore, the harmonic component in the differential output may be removed by the low-pass filter 13. However, the low-pass filter 13 cannot function properly, and it is difficult to accurately detect the angular velocity. SUMMARY OF THE INVENTION The present invention has been made by examining the solution of the problems of the conventional vibrating gyroscope as a problem, and an object of the present invention is to differentially amplify voltages generated from respective piezoelectric elements. An object of the present invention is to provide a vibrating gyroscope capable of sufficiently increasing the measurement accuracy of the angular velocity by making the respective harmonic components included in the generated voltages close to each other.

[0007]

In order to achieve the above object, according to the present invention, a pair of, one or more sets of piezoelectric elements having a detecting function are attached to a side surface of a columnar vibrating body. When a pair of piezoelectric elements of the vibrator are connected to a synchronous detector via a differential amplifier, the piezoelectric elements are connected to each other with capacitive elements.

[0008]

[Function] Impedance of capacitive element

If the capacity is C,

## EQU2 ## Since the frequency is given by = 1 / jWC, the impedance of the vibrator at a higher frequency than the excitation frequency thereof decreases. Therefore, when the piezoelectric elements are connected to each other via the capacitive element as in the present invention, the mutual piezoelectric elements are connected with a low impedance with respect to the harmonic components. Since the harmonic components generated from the respective piezoelectric elements have values close to each other, the occurrence of a saturation phenomenon due to differential amplification can be effectively avoided.

[0009]

FIG. 1 shows an embodiment of the present invention. The same reference numerals as those shown in FIG. 2 denote the same elements. Also in this embodiment, the first piezoelectric element 2 is provided on one side 1a of the vibrating body 1 having a rectangular cross section, and the second piezoelectric element 3 is provided on the other side 1b adjacent to the side 1a.
To form the vibrator 4. Piezoelectric element 2,
3 is connected to a driving device 5 via respective impedance elements Z ₁ and Z ₂ , and further connected to the driving device 5 with a capacitive element 6 via another impedance element Z _3. An AC voltage can be simultaneously applied to the capacitors 2 and 3 and the capacitor 6 from the driving device 5.

In this case, the connection points 7 and 8 between the impedance elements Z ₁ and Z ₂ and the piezoelectric elements 2 and 3 are interconnected via a capacitance element 16, and
It is also connected to the input terminal of the adder 9 and the adder 9
The output terminal, is fed back to each of the connection points 10 between the impedance element Z ₃ and the capacitor element 6 in the drive unit 5 to the differential output therefrom connected to the input terminal of the differential amplifier 11. Further, the connection points 7 and 8 are also connected to the input terminal of the differential amplifier 12, and the output of the differential amplifier 12 is supplied to the synchronous detector 14 (here, FET) and output to the output terminal 15 thereof. An angular velocity detection signal is obtained based on the detection signal.

According to the vibrating gyroscope thus configured, when the vibrator 4 is rotated around the Z-axis under self-excited vibration similar to that described in the conventional example, the vibrator 4 vibrates. The child 4 vibrates in the Y-axis direction due to Coriolis force proportional to its angular velocity, and as a result, a difference occurs in the output from the connection points 7 and 8. Therefore, if the outputs of the connection points 7 and 8 are differentially amplified by the differential amplifier 12, the voltage accompanying the generation of the Coriolis force can be separated and detected. If the Coriolis force is supplied to the synchronous detector 14 and detected in synchronization with the excitation cycle of the vibrator 4, Coriolis force can be detected as a voltage, and an angular velocity detection signal can be obtained based on the voltage.

By the way, in the illustrated example, the connection points 7 and 8 are
Since they are interconnected by the capacitive element 16, the impedance between the connection points 7 and 8 is low for the harmonic components contained in the voltage generated from the piezoelectric elements 2 and 3 in the detection where Coriolis force is applied, Since the respective output levels can be brought close to the same level, the harmonic components of the output after differential amplification by the differential amplifier 12 can be effectively reduced. Therefore, it is possible to prevent the saturation phenomenon of the harmonic component due to the differential amplification, and it is possible to accurately detect the angular velocity without using a low-pass filter.

In the above-described embodiment, a pair of two piezoelectric elements each having the functions of driving, feedback, and detection are attached as the piezoelectric elements. The present invention is not limited to this embodiment, but includes a pair of a plurality of pairs of piezoelectric elements having a detection function and connected to each other via a capacitance element.
As shown in (b), two sets of piezoelectric elements may be adhered using each side face of a rectangular cross section, and in this case, the same desired effect can be achieved. Further, the cross-sectional shape of the columnar vibrator may be a polygon other than a quadrangle in cross section, for example, a hexagon as shown in FIG. 1 (c), or an appropriate cross-sectional shape such as a circle may be selected. Can be used.

[0014]

As described above, according to the present invention, in particular, the harmonic output generated from the piezoelectric element is converted to the mutual power based on the action of the capacitive element interconnecting the two piezoelectric elements having the detecting function. Approximately accurate angular velocity can be measured without causing output saturation even in subsequent differential amplification, and without removing the harmonic output with a low-pass filter. Becomes

[Brief description of the drawings]

FIGS. 1A, 1B, and 1C are diagrams illustrating an embodiment of the present invention.

FIG. 2 is a similar view showing a conventional example.

[Explanation of symbols]

1 vibrator 1a, 1b side 2,3 piezoelectric element 4 vibrator 5 driving device 6 capacitive element 7, 8, 10 a connection point 9 the adder 11, 12 a differential amplifier 14 synchronous detector 16 capacitive elements Z _1, Z _2, Z ₃ impedance element

Claims (1)

(57) [Claims] 1. A vibrator is formed by attaching a pair of one or more sets of piezoelectric elements having a detecting function to side surfaces of a columnar vibrating body, and forming a vibrator. A vibrating gyroscope connected to a synchronous detector via a piezoelectric element, wherein the piezoelectric elements are interconnected via a capacitive element.