JPH07198396A - Vibrating gyro - Google Patents

Abstract

PURPOSE:To provide a vibrating gyro whose sensitivity is stable with reference to a temperature change. CONSTITUTION:The vibrating gyro contains a piezoelectric vibrator 12. A piezoelectric element 16c for the piezoelectric vibrator 12 is connected to piezoelectric elements 16a, 16b via an oscillation circuit 18 and a phase correction circuit 20. The piezoelectric elements 16a, 16b are connected to a synchronous detection circuit 24 via a differential amplifier circuit 22. Also the phase correction circuit 20 is connected to the synchronous detection circuit 24. The synchronous detection circuit 24 is connected to a DC amplifier circuit 28 via a temperature compensation circuit 26. The temperature compensation circuit 26 is provided with a temperature-gain characteristic which is nearly opposite to a change in detection signals obtained from the piezoelectric elements 16a, 16b for the piezoelectric vibrator 12 with reference to a temperature change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration gyro,
In particular, for example, a navigation system that has a piezoelectric vibrator and detects the position of the moving body by detecting the rotation angular velocity to perform appropriate guidance, or detects the rotation angular velocity due to external vibration such as camera shake, and the like. The present invention relates to a vibration gyro that can be applied to a vibration isolation system such as a camera shake prevention device for damping vibration.

[0002]

2. Description of the Related Art In a vibration gyro having a piezoelectric vibrator,
Since the detection signal obtained from the piezoelectric vibrator changes due to the temperature change, the sensitivity as well as the detection signal also changes due to the temperature change as shown in FIG. 5, for example.

Therefore, conventionally, in a vibration gyro having a piezoelectric vibrator, a temperature sensitive element such as a thermistor is attached to an amplifier circuit for amplifying a detection signal obtained from the piezoelectric vibrator or a signal related to the detection signal, It suppresses changes in sensitivity due to temperature changes.

FIG. 6 is a circuit diagram showing an example of an amplifier circuit for suppressing a change in sensitivity due to a temperature change in the vibration gyro having the temperature-sensitivity characteristic shown in FIG. The amplifier circuit 1 includes an input terminal 2, and the input terminal 2 is connected to the non-inverting input terminal of the operational amplifier 3. The inverting input terminal of the operational amplifier 3 is grounded via the resistor 4. Further, a negative characteristic thermistor 5 is connected as a temperature sensitive element between the inverting input terminal and the output terminal of the operational amplifier 3. Further, the output terminal 6 is connected to the output terminal of the operational amplifier 3. Therefore, in the amplifier circuit 1, the amplification degree decreases as the temperature rises.

[0005]

If the amplifying circuit 1 shown in FIG. 6 is provided in the vibrating gyro having the temperature-sensitivity characteristic shown in FIG. 5, the amplification degree of the amplifying circuit 1 decreases as the temperature rises. As shown in FIG. 7, the sensitivity is corrected to a substantially constant sensitivity in the region near 25 ° C. where the temperature-sensitivity characteristic is linear, but in the low temperature region where the temperature-sensitivity characteristic is curved and The sensitivity is not corrected to a substantially constant value in the high temperature region. Therefore, the rotational angular velocity cannot be accurately detected in the low temperature region and the high temperature region where the sensitivity is not stable.

Therefore, a main object of the present invention is to provide a vibrating gyro that is stable in sensitivity to temperature changes.

[0007]

According to the present invention, in a vibrating gyroscope having a piezoelectric vibrator capable of obtaining a detection signal, a temperature compensation circuit having a characteristic relating to a change in the detection signal of the piezoelectric vibrator with respect to a temperature change is provided. , Vibrating gyro.

[0008]

The temperature compensating circuit corrects the change of the detection signal of the piezoelectric vibrator with respect to the temperature change so that the change becomes substantially constant. Therefore, the sensitivity of the vibration gyro becomes stable against temperature changes.

[0009]

According to the present invention, it is possible to obtain a vibration gyro whose sensitivity is stable against temperature changes. Therefore, by using the vibrating gyroscope according to the present invention, the rotational angular velocity can be accurately detected from the low temperature region to the high temperature region.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the detailed description of the embodiments below with reference to the drawings.

[0011]

1 is a block diagram showing an embodiment of the present invention. The vibrating gyro 10 includes a piezoelectric vibrator 12.

The piezoelectric vibrator 12 includes a vibrating body 14 made of, for example, a metal in the shape of a regular triangular prism, and three piezoelectric elements 16a, 16b and 16c are formed in substantially the center of three side surfaces of the vibrating body 14. It These piezoelectric elements 16
a, 16b and 16c each include a piezoelectric layer made of a piezoelectric material, electrodes are formed on both main surfaces of the piezoelectric layer, one electrode is bonded to the side surface of the vibrating body 14, and the other electrode is Used for signal input / output. In this piezoelectric vibrator 12, for example, two piezoelectric elements 1
When a similar drive signal is applied to 6a and 16b, the vibrating body 14 flexurally vibrates in the direction orthogonal to the main surface of the piezoelectric element 16c. In this state, similar detection signals are obtained from the piezoelectric elements 16a and 16b. Then, the piezoelectric vibrator 12
If a rotational angular velocity about the central axis of the vibrating body 14 is given to, the direction of flexural vibration of the vibrating body 14 is changed by the Coriolis force, and detection signals corresponding to the rotational angular velocity are obtained from the two piezoelectric elements 16a and 16b. To be In this case, for example, the voltage of the detection signal from the one piezoelectric element 16a increases and the voltage of the detection signal from the other piezoelectric element 16b decreases according to the rotational angular velocity. Therefore, if the difference between these detection signals is detected, the vibrator 1
The rotational angular velocity added to 4 can be detected. In this embodiment, the two piezoelectric elements 1 of the piezoelectric vibrator 12 are used.
The detection signals obtained from 6a and 16b are, for example,
In the region near 25 ° C., it has a characteristic of linearly increasing as the temperature rises, but in the low temperature region and the high temperature region, it has a characteristic of changing in a curve with respect to the temperature change.

The piezoelectric element 16c of the piezoelectric vibrator 12 is
For example, it is connected to the input terminal of the oscillation circuit 18 formed of an amplifier. The oscillation circuit 18 amplifies the feedback signal obtained from the piezoelectric element 16c and generates a drive signal for driving the piezoelectric vibrator 12.

The output end of the oscillation circuit 18 is connected to the phase correction circuit 2
0 is connected to the input terminal. This phase correction circuit 20 determines the phase of the feedback signal generated from the oscillation circuit 18 by the piezoelectric vibrator 1
This is for correcting the optimum phase of the drive signal for driving 2.

The output end of the phase correction circuit 20 is connected to the piezoelectric elements 16a and 16b of the piezoelectric vibrator 12. Therefore, the piezoelectric elements 16a and 16b of the piezoelectric vibrator 12 are
A similar drive signal having an optimum phase is applied to each of the.

Further, the piezoelectric element 16a of the piezoelectric vibrator 12
And 16b are connected to the non-inverting input terminal and the inverting input terminal of the differential amplifier circuit 22, respectively. The differential amplifier circuit 22 is for detecting the difference signal between the detection signals obtained from the piezoelectric elements 16a and 16b.

The output terminal of the differential amplifier circuit 22 is connected to the input terminal of the synchronous detection circuit 24. Another output terminal of the phase correction circuit 20 is connected to another input terminal of the synchronous detection circuit 24. The synchronous detection circuit 24 detects the output signal of the differential amplifier circuit 22, that is, the signal of the difference between the detection signals obtained from the piezoelectric elements 16a and 16b, in synchronism with the drive signal of the piezoelectric vibrator 12, and rectifies it into direct current. It is for.

The output terminal of the synchronous detection circuit 24 is connected to the input terminal 26a of the temperature compensation circuit 26. The temperature compensating circuit 26 includes piezoelectric elements 16 a and 16 a of the piezoelectric vibrator 12.
This is for temperature compensation of the detection signal obtained from b. As shown in FIG. 2, the input terminal 26a of the temperature compensation circuit 26 is grounded via a series circuit of a resistor 26b and a negative characteristic thermistor 26c as a temperature sensitive element. Further, the input terminal 26a is grounded via a series circuit of a negative characteristic thermistor 26d as a temperature sensitive element and a resistor 26e. In addition, the resistor 26b and the negative characteristic thermistor 26c
A series circuit of two resistances 26f and 26g is connected between the connection point of 1 and the connection point of the negative characteristic thermistor 26d and the resistance 26e. The output terminal 26h is connected to the connection point of the two resistors 26f and 26g. The temperature compensating circuit 26 has a gain that linearly decreases with temperature rise at approximately 25 ° C., which is almost opposite to the change of the detection signals of the piezoelectric elements 16a and 16b of the piezoelectric vibrator 12 with respect to temperature change. In the low temperature region and the high temperature region, the resistors 26b and 26b have a temperature-gain characteristic in which the gain changes in a curve with respect to the temperature change.
The resistance values of 26e, 26f and 26g and the characteristics of the negative characteristic thermistors 26c and 26d are set.

The output terminal 26h of the temperature compensating circuit 26 is connected to the input terminal of the DC amplifying circuit 28, as shown in FIG. The DC amplification circuit 28 is for amplifying the DC signal output from the temperature compensation circuit 26 to increase the sensitivity of the vibration gyro 10.

In this vibrating gyro 10, the oscillation circuit 18
The phase correction circuit 20 applies the same drive signal having the optimum phase to the piezoelectric elements 16a and 16b of the piezoelectric vibrator 12. Therefore, the detection signal according to the rotational angular velocity applied to the piezoelectric vibrator 12 is
Are obtained from the two piezoelectric elements 16a and 16b.

Then, the signal of the difference between the detection signals of the piezoelectric elements 16a and 16b is detected by the differential amplifier circuit 22, then detected by the synchronous detection circuit 24 in synchronization with the drive signal, and rectified into direct current. . Further, the DC signal output from the synchronous detection circuit 24 is temperature-compensated by the temperature compensation circuit 26 and amplified by the DC amplification circuit 28.

Therefore, in this vibrating gyro 10,
The rotation angular velocity applied to the piezoelectric vibrator 12 can be detected by the DC signal output from the temperature compensation circuit 26 or the DC amplification circuit 28. The DC amplifier circuit 2
When the rotational angular velocity is detected by the DC signal output from 8, the sensitivity is high, which is preferable.

Further, in the vibrating gyroscope 10, when the temperature compensating circuit 26 is not provided, the sensitivity is the same as the detection signals of the piezoelectric elements 16a and 16b of the piezoelectric vibrator 12.
As shown in FIG. 5, although it does not become constant from the low temperature region to the high temperature region, the temperature compensating circuit 26 performs temperature compensation of the detection signal, so that the sensitivity is from the low temperature region to the high temperature region as shown in FIG. It becomes almost constant and stable. Therefore, the vibrating gyroscope 10 can accurately detect the rotational angular velocity from the low temperature region to the high temperature region.

In the above embodiment, the temperature compensating circuit 2 is used.
Although 6 is composed of four resistors and two negative characteristic thermistors, the temperature compensation circuit 26 may be composed of three negative characteristic thermistors as shown in FIG. Further, the temperature compensating circuit 26 may use a positive temperature coefficient thermistor as a temperature sensitive element.

In the above embodiment, the temperature compensating circuit 2 is used.
6 has a characteristic almost opposite to the change of the detection signal obtained from the piezoelectric vibrator 12 with respect to the temperature change, but in the present invention, the temperature compensation circuit has almost the same change as the change of the detection signal obtained from the piezoelectric vibrator with respect to the temperature change. It may be configured to have the same characteristics. In this case, the detection signal of the piezoelectric vibrator or a signal related to the detection signal and the output signal of the temperature compensation circuit to which a constant level signal is applied are made to have different levels, and the difference between these signals may be detected. Good. That is, in the present invention, the temperature compensating circuit may be configured to have a characteristic related to the change in the detection signal of the piezoelectric vibrator with respect to the temperature change.

Further, in the above embodiment, the temperature compensating circuit 26 is provided between the synchronous detection circuit 24 and the DC amplifying circuit 28, but the temperature compensating circuit 26 includes the differential amplifying circuit 2.
2, it may be incorporated in the synchronous detection circuit 24 or the DC amplification circuit 28, and the differential amplification circuit 22 and the synchronous detection circuit 24
It may be provided between and or after the DC amplification circuit 28.

Further, in the above embodiment, the piezoelectric vibrator 12
Is composed of a vibrating body 14 made of a metal having a regular triangular prism shape and three piezoelectric elements 16a, 16b and 16c.
In the present invention, the piezoelectric vibrator may be composed of a vibrating body made of a piezoelectric body and a plurality of electrodes formed on the side surface of the vibrating body. Further, the vibrating body of the piezoelectric vibrator is not limited to the regular triangular prism shape, but may be formed in other polygonal columnar shapes such as a regular tetragonal prism shape or a cylindrical shape. Further, the number of piezoelectric elements and electrodes of the piezoelectric vibrator may be changed arbitrarily.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention.

FIG. 2 is a circuit diagram showing an example of a temperature compensation circuit used in the embodiment shown in FIG.

FIG. 3 is a graph showing temperature-sensitivity characteristics of the example shown in FIG.

FIG. 4 is a circuit diagram showing another example of a temperature compensation circuit used in the embodiment shown in FIG.

FIG. 5 is a graph showing temperature-sensitivity characteristics of a conventional vibration gyro.

6 is a circuit diagram showing an example of an amplifier circuit for suppressing a change in sensitivity due to a temperature change of a vibration gyro having the temperature-sensitivity characteristic shown in FIG.

7 is a graph showing temperature-sensitivity characteristics when the vibration gyro having the temperature-sensitivity characteristics shown in FIG. 5 is provided with the amplifier circuit shown in FIG.

[Explanation of symbols]

 10 Vibration Gyro 12 Piezoelectric vibrator 14 Vibrating body 16a, 16b, 16c Piezoelectric element 18 Oscillation circuit 20 Phase correction circuit 22 Differential amplification circuit 24 Synchronous detection circuit 26 Temperature compensation circuit 28 DC amplification circuit

Claims (1)

[Claims] 1. A vibrating gyroscope having a piezoelectric vibrator capable of obtaining a detection signal, wherein a temperature compensation circuit having characteristics relating to a change in the detection signal of the piezoelectric vibrator with respect to a temperature change is provided. gyro.