JPH11344344A - Piezoelectric vibration gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric vibration gyro having a temp. dependence of the sensitivity, remaining within specifications even if changing the vibrator material. SOLUTION: In a driving detection circuit of the piezoelectric vibration gyro composed of a differential amplifier 11, coherent detector circuit 12, low- pass filter 13, phase circuit 14 and driving vibration circuit 15, and a resistor used in the phase circuit 11 uses a temp.-sensitive element 19 to thereby reduce the temp. change of the sensitivity of the piezoelectric vibration gyro.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a camera-integrated VT.
In particular, the present invention relates to a piezoelectric vibrating gyroscope using a piezoelectric rod-shaped bending vibrator, among gyroscopes used for preventing hand shake of R and for a car navigation system.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyroscope is a gyroscope utilizing a mechanical phenomenon in which when a rotating angular velocity is given to a vibrating object, a Coriolis force is generated in a direction perpendicular to the direction of the vibration. In a vibration system configured to be capable of excitation and detection in two directions orthogonal to each other,
When the vibrator itself is rotated around an axis parallel to the line where the two vibrating surfaces intersect with one of the vibrations being excited,
By the action of the aforementioned Coriolis force, a force acts in a direction perpendicular to this vibration, and the other vibration is excited. Since the magnitude of the vibration is proportional to the magnitude of the vibration on the input side and the rotational angular velocity, when the input voltage is constant, the magnitude of the rotational angular velocity can be obtained from the magnitude of the output voltage.

FIG. 2 is a schematic structural view of a prismatic piezoelectric vibrator used in a conventional piezoelectric vibrating gyroscope, and shows the operating principle of the vibrating gyroscope. A surface in the X direction of the vibrator 1 of a quadrangular prism made of a constant elastic metal such as Elinvar;
And piezoelectric elements 2 and 3 are provided on the respective surfaces in the Y direction. When a voltage is applied to the piezoelectric element 2 provided on the surface in the X direction, and a rotational angular velocity (indicated by ω in the Z direction as an axis in the drawing) is applied in a state where the vibration in the X direction is excited,
The vibration in the Y direction is excited by the Coriolis force, and the vibration in the Y direction is detected by the piezoelectric element 3 provided on the surface in the Y direction.

FIG. 3 is a perspective view showing, as another example, the structure of a columnar type piezoelectric ceramic vibrator (hereinafter, referred to as a vibrator). Six strip electrodes parallel to the length direction (hereinafter referred to as electrodes) 4,
5, 6, 7, 8, 9 are formed. This electrode is connected to every other electrode, and polarized as two terminals.
After the polarization process, every other electrode 5, 7, 9 is connected to form a common ground electrode, and among the remaining electrodes, electrode 4 is used as a drive electrode, electrodes 6 and 8 are used as detection electrodes, a phase circuit, and a differential circuit. A piezoelectric vibrating gyroscope can be formed by being connected to each of the amplifiers.

FIG. 4 is a cross-sectional view of the vibrator 10, and a polarization process is performed between the electrodes in the direction of the dashed arrow as shown in FIG.

FIG. 12 is a block diagram for explaining a drive detection circuit of a piezoelectric vibrating gyroscope according to a conventional embodiment. The electrodes 5, 7, 9 of the vibrator 10 are connected to a reference potential. The detection electrodes 6 and 8 are connected to the differential amplifier 11 and the phase circuit 14. The phase circuit 14 is connected to the drive electrode 4 of the vibrator 10 via the drive oscillation circuit 15 and forms a self-excited oscillation loop. An AC voltage having a frequency substantially following the resonance frequency of the vibrator 10 is applied to the drive circuit 4. 4 to excite the bending vibration in the X direction. Since the detection electrodes 6 and 8 are arranged symmetrically with respect to the bending vibration in the X direction, the output of the X direction component is canceled by the differential amplifier 11.

Since the outputs of the detection electrodes 6 and 8 have opposite phases with respect to the bending vibration excited by the Coriolis force, the output of the differential amplifier 11 has a component in the Y direction, that is, an alternating current proportional to the rotational angular velocity. Only voltage is output. The output of the differential amplifier 11 is synchronously detected by a synchronous detection circuit 12,
As a result of the rectification by the low-pass filter 13, a DC voltage proportional to the rotational angular velocity is output to the output terminal 16.

[0008]

Here, an output voltage (hereinafter, referred to as an output voltage) generated when the vibrating gyroscope is rotated by 1 deg per second.
Has a temperature characteristic peculiar to the material, and the temperature characteristic differs depending on the type. Conventionally, the drive voltage is controlled at a magnification determined by the temperature-sensitive element 17 and the resistor 18 based on the temperature characteristics of the temperature-sensitive element 17 in the drive oscillation circuit, and sensitivity temperature correction is performed.

However, as described above, since the temperature characteristics of the vibrator also change depending on the vibrator material, there is a problem that if the vibrator material is changed, the temperature correction of the temperature-sensitive element 17 cannot be satisfactorily realized. Had occurred. That is, when the material of the vibrator is changed, the temperature characteristics of the vibrator are different, so that the temperature characteristics of the sensitivity are not always within the standard in the conventional method.

[0010] Accordingly, the present invention has been proposed to solve the above-described problems, and an object of the present invention is to provide a piezoelectric vibrating gyroscope in which the temperature characteristic of sensitivity falls within the standard even if the vibrator material is changed. To provide.

[0011]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides the following piezoelectric vibrating gyroscope. A drive detection circuit for exciting and detecting the vibration of the vibrator is used for the phase circuit in a piezoelectric vibration gyro including a differential amplifier, a synchronous detection circuit, a low-pass filter, a phase circuit, and a drive oscillation circuit. The temperature change of the sensitivity is reduced by using a temperature-sensitive element for the resistor.

[0012] The operation of R is a function of a part of the phase circuit.
By changing the resistance of the −C circuit to a temperature-sensitive element, the drive frequency can be controlled by shifting the phase with respect to the temperature change. Therefore, the drive frequency can be moved closer to or away from the resonance frequency, and the magnitude of the sensitivity is changed.

That is, the present invention provides a piezoelectric vibrating gyroscope comprising a piezoelectric vibrator and a drive detecting circuit, wherein the drive detecting circuit for exciting and detecting the vibration of the piezoelectric vibrator comprises a differential amplifier, A temperature detection element is used for at least one or more resistors of the RC parallel section, which includes a synchronous detection circuit, a low-pass filter, a phase circuit, and a drive oscillation circuit, and determines the phase of the phase circuit. This is a piezoelectric vibrating gyroscope.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing an embodiment of a piezoelectric vibrating gyroscope according to the present invention. The electrodes 5, 7, 9 of the cylindrical piezoelectric vibrator 10 are connected to a reference potential. The detection electrodes 6 and 8 are connected to the differential amplifier 11 and the phase circuit 14. The phase circuit 14 is connected to the drive electrode 4 of the vibrator 10 via the drive oscillation circuit 15 and forms a self-excited oscillation loop. An AC voltage having a frequency substantially following the resonance frequency of the vibrator 10 is applied to the drive circuit 4. 4 to excite the bending vibration in the X direction. Since the detection electrodes 6 and 8 are arranged symmetrically with respect to the bending vibration in the X direction, the output of the X direction component is canceled by the differential amplifier 11.

Since the outputs of the detection electrodes 6 and 8 have opposite phases to the bending vibration excited by the Coriolis force, the output of the differential amplifier 11 is a component in the Y direction, that is, an alternating current proportional to the rotational angular velocity. Only voltage is output. The output of the differential amplifier 11 is synchronously detected by a synchronous detection circuit 12,
As a result of the rectification by the low-pass filter 13, a DC voltage proportional to the rotational angular velocity is output to the output terminal 16.

Here, the present invention is characterized in that in the RC circuit of the phase shift circuit 14, a temperature-sensitive element is inserted in one or more resistors. The temperature sensing element 19 in the example in the figure is the example.

Hereinafter, the characteristics of the piezoelectric vibrating gyroscope of the present invention will be described.

FIG. 5 is a graph showing sensitivity change rate temperature characteristics of two kinds of materials A and B. Material A,
It can be seen that the material B and the material B have different temperature characteristics with respect to the rate of change in sensitivity.

FIG. 6 shows a temperature characteristic of the sensitivity change rate when the sensitivity is corrected by the drive detection circuit of the conventional piezoelectric vibrating gyroscope. The material A is corrected with a margin for the standard, but the material B is almost at the limit of the standard.

An example of correction according to the present invention for the material B will be described below.

FIG. 7 is a diagram showing the relationship between the temperature (Fd−fr) between the drive frequency fd and the resonance frequency fr of the material B and the temperature. In FIG. 7, a is the characteristic of the piezoelectric vibrating gyroscope of the present invention. For comparison, FIG. 7A shows the characteristics of a conventional piezoelectric vibrating gyroscope. The difference between these characteristics is the difference between the case where the temperature sensitive element 19 is inserted into the phase shift circuit 14 (the present invention) and the case where the temperature sensitive element 19 is not inserted (the conventional example).

According to the present invention, FIG.
It can be seen from the characteristics of the conventional A that the range of variation is improved. In FIG. 7, the reason why the characteristic according to the present invention is obtained as shown in FIG.
9 will be described below (assuming material B).

FIG. 8 shows the relationship between sensitivity and fd-fr.
When the difference of fd-fr increases, it means that the driving point moves away from the resonance point, and thus the sensitivity decreases. Therefore, it can be seen from FIGS. 7A and 8 that the sensitivity increases on the low temperature side and decreases on the high temperature side, and the tendency is as shown in FIG.

Next, FIG. 9 shows fd-fr and the thermosensitive element 1.
9 shows a relationship with the resistance value. From the figure, it is understood that fd-fr decreases as the resistance increases. Therefore, the value of fd-fr can be controlled by using the temperature-sensitive element 19 to have a temperature characteristic.

FIG. 10 shows an example of the resistance-temperature characteristics of the temperature-sensitive element 19. FIG. 7 shows a case where a temperature-sensitive element whose resistance value is increased on the high temperature side is used. For example, if a temperature sensing element having a temperature characteristic as shown in FIG. 7 is used, the temperature characteristic of fd-fr can be changed to a characteristic as shown in FIG. Since fd-fr can be controlled, the temperature characteristic of sensitivity can be changed.

FIG. 11 shows the result of temperature correction of sensitivity using the present invention. It can be seen from the figure that the temperature characteristics of the sensitivity change rate are improved compared to the conventional method (compared with the characteristics of the material B in FIG. 6).

As described above, according to the present invention, the drive frequency is controlled by using the temperature-sensitive element 19 for the resistance of the RC circuit constituting a part of the phase circuit 14, and the magnitude of the sensitivity to the temperature is reduced. By changing, the sensitivity temperature characteristics can be improved.

[0029]

As described above, according to the present invention, it is possible to provide a piezoelectric vibrating gyroscope in which the temperature characteristic of sensitivity falls within the standard even if the material of the vibrator is changed.

[Brief description of the drawings]

FIG. 1 is a diagram showing an embodiment of a piezoelectric vibrating gyroscope according to the present invention.

FIG. 2 is a perspective view of a prism type piezoelectric vibrator for explaining the operation principle of the piezoelectric vibrating gyroscope.

FIG. 3 is a perspective view of a columnar piezoelectric vibrator for explaining the operation principle of the piezoelectric vibrating gyroscope.

FIG. 4 is a sectional view showing an electrode arrangement and a polarization direction of the cylindrical piezoelectric vibrator shown in FIG. 2;

FIG. 5 is a graph showing sensitivity change rate temperature characteristics of a material A and a material B.

FIG. 6 is a graph showing sensitivity change rate temperature characteristics of a material A and a material B according to a conventional correction method.

FIG. 7 shows a diagram of fd- by the piezoelectric vibrating gyroscope according to the present invention.
The figure which shows the temperature characteristic of fr.

FIG. 8 is a characteristic diagram showing a relationship between sensitivity of material B and fd-fr.

FIG. 9 is a characteristic diagram showing a relationship between fd-fr of a material B and resistance.

FIG. 10 is a diagram showing resistance-temperature characteristics of a temperature-sensitive element.

FIG. 11 is a characteristic diagram showing temperature characteristics of the piezoelectric vibrating gyroscope and the rate of change in sensitivity of the present invention.

FIG. 12 is a view showing an example of a conventional piezoelectric vibrating gyroscope.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 prismatic oscillator 2, 3 piezoelectric element 4, 5, 6, 7, 8, 9 band electrode 10 cylindrical piezoelectric ceramic oscillator 11 differential amplifier 12 synchronous detection circuit 13 low-pass filter 14 phase circuit 15 drive oscillation circuit 16 output Terminal 17 Temperature-sensitive element 18 Resistance 19 Temperature-sensitive element 20 Resistance 21, 22 Capacitor

Claims (1)

[Claims] In a piezoelectric vibrating gyroscope comprising a piezoelectric vibrator and a drive detecting circuit, the drive detecting circuit for exciting and detecting the vibration of the piezoelectric vibrator includes a differential amplifier, a synchronous detecting circuit, A low-pass filter, a phase circuit, and a drive oscillation circuit, wherein a temperature-sensitive element is used for at least one or more resistors of the RC parallel section that determines the phase of the phase circuit. Piezoelectric vibrating gyroscope.