JPH0933259A - Driving/detecting circuit for piezoelectric vibration gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a driving/detecting circuit for a piezoelectric gyro, which can always stabilize the detecting sensitivity of the piezoelectric vibration gyro without depending on temperature. SOLUTION: This circuit comprises a differential amplifier circuit 9, an adding amplifier circuit 10, a synchronous detecting circuit 11 and a phase shifting circuit 20 with a temperature compensating circuit. The temperature compensating circuit in the phase shifting circuit 20 with a temperature compensating circuit performs the temperature compensation for the driving signal in correspondence with the change in output voltage of the driving signal from the phase shifting circuit 20 based on the mechanical-sharpness characteristic of a piezoelectric vibrator 1 and transmits the generated temperature compensating driving signal to the piezoelectric vibrator 1. Thus, the output voltage of the detected signal from the piezoelectric vibrator 1 becomes constant all the time regardless of the temperature change.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gyroscope used for a posture control of a moving body such as a ship or an automobile or equipment mounted on the moving body itself, a navigation system of an automobile, and an ultrasonic wave of a piezoelectric vibrator. The present invention relates to a so-called piezoelectric vibration gyro using vibration, and more particularly to a piezoelectric vibration gyro drive detection circuit for driving a piezoelectric vibrator in the piezoelectric vibration gyro by self-excitation.

[0002]

2. Description of the Related Art Generally, a piezoelectric vibrating gyro is known as a gyroscope utilizing a mechanical phenomenon that a Coriolis force is generated in a direction perpendicular to a vibrating direction when a rotating angular velocity is applied to a vibrating object.

In such a piezoelectric vibrating gyro, in a vibrating system configured to be capable of exciting and detecting in two directions orthogonal to each other, one of the vibrators is excited in a state where one vibration is excited. When it is rotated about an axis parallel to the line where the vibrating surfaces intersect, 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 the other vibration is proportional to the magnitude of the input side vibration and the rotation angular velocity, the magnitude of the rotation angular velocity is changed from the magnitude of the output voltage proportional to the magnitude of the other vibration with the input voltage kept constant. You can ask for it.

FIG. 3 shows a schematic structure of a main part of a conventional piezoelectric vibrating gyro, that is, a piezoelectric vibrator used in the piezoelectric vibrating gyro. FIG. 3A is a perspective view thereof and FIG. 3B) is a sectional view taken along the line AA ′ of FIG.

In this piezoelectric vibrator, six strip-shaped electrodes 2, 3, 4, 5, 6, which are parallel to the length direction of the piezoelectric ceramic cylinder 1, are arranged at positions at which the circumference is divided into six equal parts. 7 are formed. These strip-shaped electrodes 2 to 7 are arranged at alternate ends along the circumference with their connecting electrodes 8a and 8b for grounding.
It is connected to the. Incidentally, the strip electrodes 2 to 7 and the connecting electrodes 8a and 8b are directly formed on the side surface of the piezoelectric ceramic cylinder 1 by screen printing, or after plating or the like is formed on the entire side surface of the piezoelectric ceramic cylinder 1. , Is manufactured by removing unnecessary portions of the electrodes by photoetching.

[0006] Here, the strip electrodes 2 to 7 are connected to each other so that every other strip electrodes 2, 4 and 6 are grounded after being polarized as terminals. (That is, these ground strip electrodes 2, 4, 6 are connected to the connecting electrodes 8a, 8b), the remaining strip electrodes 3 are configured for driving, and the strip electrodes 5, 7 are configured for detection. There is.

FIG. 4 is a block diagram showing the basic structure of a conventional drive detection circuit used in a piezoelectric gyro including such a piezoelectric vibrator. This drive detection circuit includes a differential amplifier circuit 9, a summing amplifier circuit 10, a synchronous detection circuit 11, and a phase shift circuit 12, and the input sides of the differential amplifier circuit 9 and the summing amplifier circuit 10 have detection strip electrodes 5, 5. 7 and the output side of the phase shift circuit 12 is connected to the driving strip electrode 3.

In this drive detection circuit, the two systems of detection signals transmitted from the detection strip electrodes 5 and 7 in the state where the power supply voltage is applied are added and amplified and combined by the adding and amplifying circuit 10 to be added and amplified signals. . This added amplified signal is transferred to the phase shift circuit 12
Is phase-shifted and becomes a drive signal and is transmitted to the drive strip electrode 3. As a result, a self-excited oscillation circuit for oscillating near the resonance frequency of the bending vibration of the piezoelectric ceramic cylinder 1 and driving the piezoelectric vibrator with a constant drive voltage (output voltage of the drive signal) is configured.

On the other hand, the differential amplifier circuit 9 differentially amplifies and combines the two systems of detection signals transmitted from the detection strip electrodes 5 and 7 to generate a differential amplification signal. The output voltage of this differential amplified signal becomes an AC voltage having an amplitude proportional to the rotational angular velocity. The differential amplification circuit 9 inputs the differential amplification signal and the addition amplification signal from the addition amplification circuit 10 to generate a DC voltage having a polarity according to the rotation direction and proportional to the rotation angular velocity.

[0010]

In the above-described piezoelectric gyro drive detection circuit, as the mechanical sharpness Q of the piezoelectric vibrator changes with temperature, even if the output voltage of the drive signal is constant, the piezoelectric The output level of the detection signal from the oscillator changes.

FIG. 5 shows the characteristic of the mechanical sharpness Q shown by the relationship of the output voltage V _out [V] of the detection signal with respect to the drive frequency f [Hz] of the drive signal in the above-mentioned piezoelectric vibrator. is there.

Here, assuming that the output voltage of the detection signal is Va when the initial state is room temperature and the drive frequency fa is shown by the curve C2 in that room temperature state, the temperature decreases from this state to a low temperature. Then, it is shown that the mechanical sharpness Q of the piezoelectric vibrator is increased and the output voltage of the detection signal is increased to Vb corresponding to the curve C1 in the low temperature state. On the contrary, when the temperature rises and becomes high, the mechanical sharpness Q of the piezoelectric vibrator becomes low, so that the output voltage of the detection signal is Vc corresponding to the curve C3 in the high temperature state.
It shows that it will fall to.

As described above, when the output level of the detection signal from the piezoelectric vibrator changes with the temperature change, as a result, the detection sensitivity of the piezoelectric vibration gyro becomes unstable due to the influence of temperature. There is.

The present invention has been made to solve the above problems, and its technical problem is to provide a drive detection circuit for a piezoelectric vibration gyro that can always stabilize the detection sensitivity of the piezoelectric vibration gyro without depending on the temperature. To provide.

[0015]

According to the present invention, a piezoelectric vibrator for a piezoelectric vibrating gyro is self-excited to obtain a detection signal output from the piezoelectric vibrator, and the detection signal is added and amplified. In a drive detection circuit for a piezoelectric vibration gyro including a summing amplifier circuit for generating a summed amplified signal and a phase shift circuit for generating a drive signal for driving the piezoelectric vibrator by phase shifting the summed amplified signal. The phase circuit includes a temperature compensation circuit that temperature-compensates the drive signal according to a change in the output voltage of the drive signal and generates a temperature-compensated drive signal for keeping the output voltage of the detection signal constant. A detection circuit is obtained.

Further, according to the present invention, in the piezoelectric vibration gyro drive detection circuit, the temperature compensation circuit is a piezoelectric vibration gyro drive detection circuit that generates a temperature compensation drive signal by varying the frequency of the drive signal. can get.

Further, according to the present invention, in any one of the piezoelectric vibrating gyro drive detection circuits described above, the temperature compensation circuit includes a resistance change circuit element whose resistance value changes in accordance with a temperature change, and a resistance change circuit element. A piezoelectric vibration gyro drive including a series resistance connected in series with the resistance change circuit element, a parallel resistance connected in parallel to the resistance change circuit element, and a series resistance and a capacitor coupling the parallel resistance to a reference potential. A detection circuit is obtained.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION A piezoelectric vibration gyro drive detection circuit according to the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 is a block diagram showing the basic structure of a piezoelectric vibrating gyro drive detection circuit according to an embodiment of the present invention including the piezoelectric vibrator shown in FIG. However, this piezoelectric vibration gyro drive detection circuit is also shown in FIG.
Since it has the same components as those of the conventional drive detection circuit shown in FIG. 2, the same parts are designated by the same reference numerals, and the description thereof will be omitted. The different components will be mainly described.

This piezoelectric vibration gyro drive detection circuit is also
Although it has the differential amplifier circuit 9, the summing amplifier circuit 10, and the synchronous detection circuit 11, the phase shift circuit is a phase shift circuit 20 with a temperature compensation circuit provided with a temperature compensation circuit. The input side of the summing amplifier circuit 10 is connected to the detection strip electrodes 5 and 7, and the output side of the phase shift circuit 20 with a temperature compensation circuit is connected to the drive strip electrode 3.

Of these, the phase shift circuit 20 with a temperature compensation circuit
The temperature compensating circuit in 1) temperature-compensates the drive signal according to the change in the output voltage of the drive signal, and generates a temperature-compensated drive signal for making the output voltage of the detection signal from the piezoelectric vibrator constant.

FIG. 2 shows the phase shift circuit 2 with the temperature compensation circuit.
2 shows a circuit configuration of a temperature compensation circuit at 0. The temperature compensating circuit includes thermistors 13, 13 as resistance change circuit elements whose resistance values change according to temperature changes.
′, Series resistors 14 and 14 ′ connected in series to the thermistors 13 and 13 ′, and parallel resistors 15 and 15 ′ connected in parallel to the thermistors 13 and 13 ′, in series Capacitors 16 and 1 for coupling between the resistor 14 and the parallel resistor 15 and the reference potential, and between the series resistor 14 ′ and the parallel resistor 15 ′ and the reference potential, respectively.
6 '. Here, as the thermistors 13 and 13 ', those having a positive characteristic in which the resistance increases as the temperature increases and the resistance decreases as the temperature decreases are used.

In this temperature compensation circuit, the resistors 14 and 15 are
Alternatively, the constants of 14 'and 15' and the thermistor 13 or 13 'are arbitrarily selected, and the resistance value of the phase shift circuit is provided with a compensation function for temperature change, and the output voltage of the detection signal from the piezoelectric vibrator The temperature compensation drive signal is generated by changing the phase of the phase shift circuit (changing the frequency of the drive signal from the phase shift circuit) so as to compensate for the change due to the temperature. For example, when the temperature changes to the high temperature side, the resistance values of the positive temperature coefficient thermistors 13 and 13 'increase and the phase of the drive signal from the phase shift circuit is delayed. As a result, the temperature-compensated drive signal is in a state where the frequency of the drive signal is lowered. Is generated by. Further, when the temperature changes to the low temperature side, the resistance values of the positive temperature coefficient thermistors 13 and 13 'become small and the phase of the drive signal from the phase shift circuit advances. As a result, the frequency-compensated drive signal has the frequency of the drive signal increased. It is generated in the state.

That is, the temperature compensating circuit here compensates for the fact that the output level of the detection signal from the piezoelectric vibrator fluctuates with the temperature change based on the characteristic of the mechanical sharpness Q shown in FIG. It functions to keep a certain level by doing.

Therefore, this temperature compensation function will be specifically described with reference to FIG. However, here again, the initial state is room temperature, and the drive frequency f shown by the curve C2 in that room temperature state is
Assuming that the output voltage of the detection signal is Va when a, the mechanical sharpness Q of the piezoelectric vibrator increases when the temperature falls from this state to a low temperature. Since the voltage rises to Vb corresponding to the curve C1 in (1), the temperature compensation circuit raises the frequency of the drive signal to fb to generate the temperature compensated drive signal in order to reduce the output voltage of the detection signal to Va. As a result, the output voltage of the detection signal of the piezoelectric vibrator is maintained at Va even if the temperature changes from room temperature to low temperature.

On the other hand, conversely, when the temperature rises and becomes high, the mechanical sharpness Q of the piezoelectric vibrator becomes low, and the output voltage of the detection signal drops to Vc corresponding to the curve C3 in the high temperature state. In the compensation circuit, in order to raise the output voltage of the detection signal to Va, the driving frequency of the driving signal is lowered to fc to generate the temperature compensation driving signal. As a result, the output voltage of the detection signal of the piezoelectric vibrator is maintained at Va even if the temperature changes from room temperature to low temperature.

As described above, the phase shift circuit 20 with the temperature compensation circuit
By changing the frequency of the drive signal based on the mechanical sharpness of the piezoelectric vibrator to generate the temperature-compensated drive signal, the output voltage of the detection signal from the piezoelectric vibrator is always constant regardless of the temperature change. You can As a result, stable detection sensitivity that is not affected by temperature changes in the piezoelectric vibrator can be obtained.

[0028]

As described above, according to the drive detection circuit for a piezoelectric vibration gyroscope of the present invention, the phase shift circuit in the conventional drive detection circuit is improved to be a phase shift circuit with a temperature compensation circuit. The temperature compensation circuit in the phase shift circuit with the compensation circuit compensates the temperature of the drive signal according to the output voltage change of the drive signal from the phase shift circuit based on the mechanical sharpness of the piezoelectric vibrator. Since the signal is generated and transmitted to the piezoelectric vibrator, the output voltage of the detection signal from the piezoelectric vibrator is always constant regardless of the temperature change, and as a result, the detection sensitivity of the piezoelectric vibration gyro is affected by the temperature. Instead, it is stabilized and its detection accuracy is improved.

[Brief description of drawings]

FIG. 1 is a block diagram showing a basic configuration of a drive detection circuit for a piezoelectric vibration gyro including a piezoelectric vibrator according to an embodiment of the present invention.

FIG. 2 shows a temperature compensation circuit in a phase shift circuit included in the piezoelectric vibration gyro drive detection circuit shown in FIG.

3A and 3B show a schematic structure of a piezoelectric vibrator used in a conventional piezoelectric vibrating gyro, in which FIG. 3A is a perspective view thereof, and FIG. 3B is a sectional view taken along line AA ′ of FIG. It is a figure.

FIG. 4 is a block diagram showing a basic configuration of a drive detection circuit including a piezoelectric vibrator used in a conventional piezoelectric vibration gyro.

5 shows a characteristic of mechanical sharpness shown by a relationship between a drive frequency of a drive signal and an output voltage of a detection signal in the piezoelectric vibrator shown in FIG.

[Explanation of symbols]

 1 Piezoelectric Ceramics Cylinder 2, 3, 4, 5, 6, 7 Strip Electrode 9 Differential Amplifying Circuit 10 Summing Amplifying Circuit 11 Synchronous Detection Circuit 12 Phase Shifting Circuit 13, 13 'Thermistor 14, 14' Series Resistor 15, 15 'Parallel Resistor 16, 16 'Capacitor 20 Phase shift circuit with temperature compensation circuit

Claims (3)

[Claims] 1. A summing amplifier circuit for self-exciting a piezoelectric vibrator for a piezoelectric vibration gyro to obtain a detection signal output from the piezoelectric vibrator and additionally amplifying the detection signal to generate a summed amplification signal. , And a piezoelectric vibration gyro drive detection circuit including a phase shift circuit for generating a drive signal for driving the piezoelectric vibrator by phase-shifting the added amplified signal, wherein the phase shift circuit outputs the drive signal. A drive detection circuit for a piezoelectric vibration gyro having a temperature compensation circuit that temperature-compensates the drive signal according to a voltage change amount and generates a temperature-compensated drive signal for making the output voltage of the detection signal constant. . 2. The piezoelectric vibration gyro drive detection circuit according to claim 1, wherein the temperature compensation circuit generates the temperature compensation drive signal by varying a frequency of the drive signal. Drive detection circuit for gyro. 3. The drive detection circuit for a piezoelectric vibration gyro according to claim 1, wherein the temperature compensation circuit includes a resistance change circuit element whose resistance value changes according to a temperature change, and a resistance change circuit element for the resistance change circuit element. And a series resistor connected in series, a parallel resistor connected in parallel to the resistance change circuit element, and a capacitor coupling the series resistor and the parallel resistor to a reference potential. Piezoelectric vibration gyro drive detection circuit.