JPH09184725A - Vibration gyro - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration gyro for accurately detecting a rotary angular velocity by suppressing the drift signal generated due to temperature change and aging. SOLUTION: A vibration gyro 1 has piezoelectric elements 3 and 4 for detection being provided at a vibrator 2 of a regular triangular column and a piezoelectric element 5 for drive. Also, a middle point between an oscillation circuit 11 and the piezoelectric element 5 is connected to phase-shift comparison circuits 12a and 12b and further is connected to the piezoelectric elements 3 and 4 via first and second PLL circuits 16a and 16b. Then, the output signal of the oscillation circuit 11 is phase-shifted by phase-shift comparison circuits 12a and 12b and the phase of the output signals of the piezoelectric elements 3 and 4 is corrected in reference to the phase-shifted signal, thus locking the output signal of the piezoelectric elements 3 and 4 so that they constantly have a certain phase difference for the output signal of the piezoelectric element 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a navigation system that detects the position of a moving body by detecting the rotational angular velocity, and performs appropriate guidance, or detects the rotational angular velocity due to external vibration such as camera shake, and detects the appropriate position. 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 vibration control.

[0002]

2. Description of the Related Art FIG. 6 is an illustrative view showing an example of a conventional vibrating gyro. The vibrating gyro 51 includes a vibrating body 52 having, for example, a regular triangular prism shape. Piezoelectric elements 53, 54 for detection for obtaining an output corresponding to the rotational angular velocity, and a piezoelectric element 55 for driving for driving the vibrating body 52 are formed at approximately the center of each side surface of the vibrating body 52. . Of these, the output end of the oscillation circuit 56 is connected to the piezoelectric element 55. A variable resistor 57 is connected between the piezoelectric elements 53 and 54, and a phase shift circuit 58 is connected between the oscillation circuit 56 and the variable resistor 57. Further, a differential amplifier circuit 59 is connected to an intermediate point between the piezoelectric elements 53 and 54 and the variable resistor 57.

When a drive signal is applied from the oscillation circuit 56 to the piezoelectric element 55, the vibrating body 52 bends and vibrates in a direction orthogonal to the surface on which the piezoelectric element 55 is formed. In this state, when the vibrating gyro 51 rotates about the rotary shaft 52a of the vibrating body 52, an output difference occurs between the piezoelectric elements 53 and 54. By detecting this output difference by the differential amplifier circuit 59, the rotational angular velocity applied to the vibration gyro 51 can be detected.

[0004]

However, in the vibrating gyroscope 51, each side surface of the vibrating body 52 has its own resonance frequency and temperature characteristics, and each side surface changes with temperature and time. Since they tried to cause different frequency changes, the phases were sometimes out of phase with each other. When the phases are deviated in this way, an output difference is generated between the piezoelectric elements 53 and 54 for detection even when there is no rotation, and therefore a drift signal is output from the differential amplifier circuit 59, and this drift signal is measured. There is an error, and it becomes impossible to detect an accurate rotational angular velocity. On the contrary,
In order to make the output signal from the differential amplifier circuit 59 zero,
The variable resistor 57 must be adjusted. However, the adjustment of the variable resistor 57 is usually performed according to the ambient temperature of the place in the manufacturing process of the vibration gyro, and after the vibration gyro is mounted on a video camera or the like and put into practical use. It was virtually impossible to readjust the variable resistor 57, and it was not possible to detect an accurate rotational angular velocity.

Therefore, it is an object of the present invention to provide a vibrating gyro that can suppress a drift signal caused by a temperature change and a temporal change and detect an accurate rotational angular velocity.

[0006]

In order to achieve the above object, in the present invention, a columnar vibrating body and a driving piezoelectric element for driving the vibrating body formed on a side surface of the vibrating body. And a piezoelectric element for detection for obtaining an output corresponding to a rotational angular velocity formed on the other side surface of the vibrating body, the output signal of the piezoelectric element for driving, and the detection signal. It is characterized by comprising a PLL circuit for keeping a constant phase difference from the output signal of the piezoelectric element for use.

Further, a columnar vibrating body, a piezoelectric element for driving the vibrating body formed on the side surface of the vibrating body, and a detecting piezoelectric element for obtaining an output corresponding to a rotational angular velocity, A vibrating gyro including a piezoelectric element for feedback when the vibrating body formed on the other side surface of the vibrating body is driven, the output signal of the piezoelectric element for driving and detecting, and the It is characterized by including a PLL circuit for keeping a constant phase difference from the output signal of the piezoelectric element.

Therefore, according to the vibrating gyroscope of the present invention, a PLL circuit is provided between the piezoelectric element for detection and the piezoelectric element for driving, or the piezoelectric element for detection and driving and the piezoelectric element for feedback. Since the phase difference between the output signals is always kept constant between and, it is possible to prevent the detection piezoelectric element from generating a drift signal even when the characteristics of the vibrating body change due to temperature changes or changes over time. Therefore, the accurate rotational angular velocity can be detected.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION A first embodiment according to the present invention,
This will be described with reference to FIGS. 1 and 2. The vibrating gyroscope of this embodiment uses one of the three piezoelectric elements provided on the triangular prism vibrating body for driving and two for detecting.

In FIG. 1, 1 is a vibrating gyro,
The vibrating body 2 is provided. The vibrating body 2 is made of, for example, a constant elastic metal material such as elinvar or a material that generally causes mechanical vibration such as quartz, glass, crystal, and ceramic, and has a regular triangular cross section. Further, as shown in FIG. 2, piezoelectric elements 3, 4 and 5 are provided at approximately the center of the three side surfaces of the vibrating body 2. Among them, the piezoelectric element 3 includes a piezoelectric layer 6a made of, for example, porcelain, and electrodes 7a and 8a are formed on both main surfaces of the piezoelectric layer 6a, respectively. The electrodes 7a and 8a are made of an electrode material such as gold, silver or aluminum, and are formed by a thin film technique such as sputtering or vapor deposition, or a printing technique depending on the material. Similarly, the other piezoelectric elements 4 and 5 also include piezoelectric layers 6b and 6c made of, for example, porcelain.
The electrodes 7b, 8b and the electrode 7c are provided on both main surfaces b, 6c.
8c is formed. Then, the electrodes 7a to 7c on one side of each of the piezoelectric elements 3 to 5 are bonded to the vibrating body 2 with, for example, a conductive adhesive.

Here, the piezoelectric elements 3 and 4 are used for detection for detecting a signal corresponding to the rotational angular velocity applied to the vibrating gyro 1, and the piezoelectric element 5 is for bending and vibrating the vibrating body 2. Used for driving.

The output end of the oscillation circuit 11 is connected to the piezoelectric element 5 in order to apply a drive signal to the vibrating body 2. An intermediate point between the oscillator circuit 11 and the piezoelectric element 5 is connected to the two phase shift circuits 12a and 12b. Of these, the output terminal of one of the phase shift circuits 12a is connected to the phase comparison circuit 13a, and the phase comparison circuit 13a includes the low-pass filter 14a.
It is connected to the capacitance adding circuit 15a via a, and the capacitance adding circuit 15a is connected to the piezoelectric element 3. Here, the phase comparison circuit 13a, the low-pass filter 14a, and the capacitance addition circuit 15a form a loop on this route, and the first PLL
(Phase locked loop) circuit 16a is formed. The output of the piezoelectric element 3 is fed back to the first PLL circuit 16a by connecting the intermediate point between the capacitance adding circuit 15a and the piezoelectric element 3 to the phase comparison circuit 13a. In addition, the first PLL circuit 16a
At the intermediate point between the piezoelectric element 3 and the capacitance adding circuit 15a,
It is connected to the inverting input terminal (not shown) of the differential amplifier circuit 17.

On the other hand, the other phase shift circuit 12b is connected to the phase comparison circuit 13b, and the phase comparison circuit 13b, the low-pass filter 14b and the capacitance addition circuit 15b form a loop on this route, and the second PLL circuit is formed. 16b is formed. The output of the piezoelectric element 4 is fed back to the second PLL circuit 16b by connecting the intermediate point between the capacitance adding circuit 15b and the piezoelectric element 4 to the phase comparison circuit 13b. In addition, the second PLL circuit 16
b is connected to a non-inverting input terminal (not shown) of the differential amplifier circuit 17 at an intermediate point between the piezoelectric element 4 and the capacitance adding circuit 15b.

Although not shown in particular, the piezoelectric element 3,
A connection for returning the output of 4 to the oscillation circuit 11 is also made, and a drive signal is applied from the oscillation circuit 11 to the piezoelectric element 5 in response to the feedback signal.

In the vibrating gyroscope 1 constructed as described above, in order to flexurally vibrate the vibrating body 2, the oscillation circuit 1
The output signal of 1 is applied to the piezoelectric element 5. The output signal of the oscillation circuit 11 is also input to one of the phase shift circuits 12a, and the phase shift circuit 12a shifts the phase by, for example, 270 ° in this embodiment. The output signal of the piezoelectric element 3 is
The resonance frequency is adjusted by the capacitance adding circuit 15a and is input to the phase comparison circuit 13a. Then, in the phase comparison circuit 13a, the output signal of the piezoelectric element 3 is the oscillation circuit 1
Phase comparison is performed with reference to a signal obtained by shifting the output signal of 1 by 270 °. In accordance with the phase difference detected in this phase comparison, the low-pass filter 14a outputs a DC control voltage, and this control voltage is added to the capacitance adding circuit 15
By returning to a, the phase of the output signal of the piezoelectric element 3 is corrected. At this time, since the reference phase of the phase comparison is deviated by 270 ° from the output of the oscillation circuit 11, the output signal of the piezoelectric element 3 is deviated from the output signal of the piezoelectric element 5 by 270 °. That is, it has a phase shifted by 90 °. In this way, the first PLL circuit 1
6a locks the output signals between the piezoelectric element 3 and the piezoelectric element 5 so that the output signals always have a constant phase difference.

The output signal of the oscillation circuit 11 is input to one phase shift circuit 12a and also to the other phase shift circuit 12b. In this embodiment, for example, 27
The phase is shifted 0 °. The resonance frequency of the output signal of the piezoelectric element 4 is adjusted by the capacitance adding circuit 15b and is input to the phase comparison circuit 13b. Furthermore, the phase comparison circuit 1
3b, the output signal of the piezoelectric element 4 is the oscillation circuit 11
Phase comparison is performed on the basis of the signal obtained by phase-shifting the output signal of 270 °. In accordance with the phase difference detected in this phase comparison, the low-pass filter 14b outputs a DC control voltage, and this control voltage is added to the capacitance adding circuit 15b.
By being fed back to, the phase of the output signal of the piezoelectric element 4 is corrected. At this time, the reference phase of the phase comparison deviates from the output of the oscillation circuit 11 by 270 °, so that the output signal of the piezoelectric element 4 deviates from the output signal of the piezoelectric element 5 by 270 °. That is, it has a phase shifted by 90 °. In this way, the second PLL circuit 1
6b locks the output signals between the piezoelectric elements 4 and 5 so that the output signals always have a constant phase difference.

When a drive signal is applied from the oscillation circuit 11 to the piezoelectric element 5, the vibrating body 2 flexurally vibrates in the direction perpendicular to the surface on which the piezoelectric element 5 is formed, and the piezoelectric elements 3 and 4
Will output the same signal. Further, when the vibrating gyro 1 rotates about the rotary shaft 2a of the vibrating body 2, Coriolis force acts, and the vibrating body 2 vibrates in a direction different from the vibrating direction when it is not rotating, and the piezoelectric elements 3 and 4 mutually separate. Different signals are output. The change in this signal corresponds to the change in the vibration direction of the vibrating body 2, so that the output signals of the piezoelectric elements 3 and 4 are signals corresponding to the rotational angular velocity. Therefore, the rotational angular velocity applied to the vibration gyro 1 can be detected by detecting the difference between the output signals of the piezoelectric elements 3 and 4 by the differential amplifier circuit.

Here, as described above, the output signals of the piezoelectric elements 3 and 4 are different from the output signals of the piezoelectric element 5, respectively.
Since the phase is always locked so that it shifts 90 °,
Even when the characteristics of the vibrating body 2 change due to temperature changes and changes over time, the generation of drift signals from the piezoelectric elements 3 and 4 is suppressed, and accurate rotational angular velocity can be detected.

As shown in FIG. 3, the midpoint between the low-pass filter 14a and the capacitance adding circuit 15a is connected to the inverting input terminal (not shown) of the differential amplifier circuit 17, and the low-pass filter 14b and the capacitance adding circuit are connected. Also in the vibration gyro 21 configured by connecting the intermediate point with 15b to the non-inverting input terminal (not shown) of the differential amplifier circuit 17, the same effect as that of the vibration gyro 1 can be obtained.

Next, a second embodiment according to the present invention is shown in FIG.
This will be described with reference to FIG. The same or corresponding parts as those in the first embodiment are designated by the same reference numerals, and the description thereof will be omitted. Further, the vibrating gyroscope of the present embodiment uses two of the three piezoelectric elements provided on the triangular prism vibrating body for driving and detecting, and one for returning.

In FIG. 4, reference numeral 31 is a vibrating gyro, which is provided with the vibrating body 2. The vibrating body 2 has, for example, a regular triangular prism shape, and the piezoelectric elements 3, 4 and 5 are provided at substantially the center of each side surface. Of these, the piezoelectric elements 3 and 4 serve both as a drive for bending and vibrating the vibrating body 2 and as a detection for detecting a signal corresponding to the rotational angular velocity applied to the vibration gyro 1. Reference numeral 5 is used for feedback for feeding back the drive signal. Then, the oscillation circuit 11 is connected to the piezoelectric elements 3 and 4 via the phase shift circuits 12 a and 12 c, and the piezoelectric element 5 is connected to the oscillation circuit 11.

Further, the intermediate point between the piezoelectric element 5 and the oscillation circuit 11 is connected to the phase shift circuit 12b. This phase shift circuit 12b
The output terminal of is connected to the phase comparison circuit 13a, the phase comparison circuit 13a is connected to the capacitance addition circuit 15a via the low-pass filter 14a, and the capacitance addition circuit 15a is connected to the piezoelectric element 3. Here, the phase comparison circuit 13a, the low-pass filter 14a, and the capacitance addition circuit 15a form a loop on this route to form a first PLL (phase locked loop) circuit 16a. The midpoint between the capacitance adding circuit 15a and the piezoelectric element 3 is the phase comparison circuit 1
By being connected to 3a, the output of the piezoelectric element 3 is fed back to the first PLL circuit 16a. The first PLL circuit 16a is connected to the inverting input terminal (not shown) of the differential amplifier circuit 17 at an intermediate point between the piezoelectric element 3 and the capacitance adding circuit 15a.

On the other hand, a phase shift circuit 12c is provided between the oscillator circuit 11 and the piezoelectric element 4. Also, the piezoelectric element 5
The intermediate point between the oscillator circuit 11 and the oscillator circuit 11 is connected to the phase shift circuit 12d. The output terminal of the phase shift circuit 12d is the phase comparison circuit 13b.
The phase comparison circuit 13b is connected to the capacitance addition circuit 15b via the low-pass filter 14b, and the capacitance addition circuit 15b is connected to the piezoelectric element 4. Here, the phase comparison circuit 13b, the low-pass filter 14b, and the capacitance addition circuit 15b form a loop on this route, and the second PL
The L circuit 16b is formed. Then, the capacitance adding circuit 1
By connecting the intermediate point between 5b and the piezoelectric element 4 to the phase comparison circuit 13b, the output of the piezoelectric element 4 becomes the second PL.
It is adapted to be fed back to the L circuit 16b. Further, the second PLL circuit 16b includes the piezoelectric element 4 and the capacitance adding circuit 15
It is connected to a non-inverting input terminal (not shown) of the differential amplifier circuit 17 at an intermediate point with respect to b.

In the vibrating gyroscope 31 thus constructed, the output signal of the oscillation circuit 11 is applied to the piezoelectric elements 3 and 4, and the output signal of the piezoelectric element 5 is applied to the oscillation circuit in order to flexurally vibrate the vibrating body 2. Returned to 11. At this time,
The output signal of the oscillation circuit 11 is also input to the phase shift circuit 12a, and is phase-shifted by 270 ° in this embodiment by the phase shift circuit 12a. The output signal of the piezoelectric element 3 is
The resonance frequency is adjusted by the capacitance adding circuit 15a and is input to the phase comparison circuit 13a. On the other hand, the signal fed back from the piezoelectric element 5 to the oscillation circuit 11 is input to the phase shift circuit 12b, and in this embodiment, after being phase-shifted by 270 °, for example, is input to the phase comparison circuit 13a. Then, in the phase comparison circuit 13a, the output signal of the piezoelectric element 3 is phase-compared with reference to the signal obtained by phase-shifting the signal fed back from the piezoelectric element 5 to the oscillation circuit 11 by 270 °. According to the phase difference detected in this phase comparison, a low-pass filter 14a outputs a DC control voltage, and this control voltage is fed back to the capacitance adding circuit 15a, whereby the phase of the output signal of the piezoelectric element 3 is returned. Is corrected. At this time, since the reference phase of the phase comparison is deviated by 270 ° from the output of the piezoelectric element 5, the output signal of the piezoelectric element 3 is deviated by 270 ° from the output signal of the piezoelectric element 5, That is, it has a phase shifted by 90 °. Thus, the first PLL circuit 16a locks the output signals between the piezoelectric elements 3 and 5 so that the output signals always have a constant phase difference.

The output signal of the oscillation circuit 11 is input to the phase shift circuit 12a and also to the phase shift circuit 12c, and in the present embodiment, is phase-shifted by 270 °, for example. Then, the output signal of the piezoelectric element 4 is the capacitance addition circuit 1
The resonance frequency is adjusted by 5b, and the phase comparison circuit 13
b. Then, in the phase comparison circuit 13b, the output signal of the piezoelectric element 4 is phase-compared with reference to the signal obtained by shifting the phase of the feedback signal from the piezoelectric element 5. According to the phase difference detected in this phase comparison, a DC control voltage is output by the low-pass filter 14b,
By feeding back the control voltage to the capacitance adding circuit 15b, the phase of the output signal of the piezoelectric element 4 is corrected. At this time, the reference phase of the phase comparison is deviated by 270 ° from the output of the piezoelectric element 5, so that the output signal of the piezoelectric element 4 is deviated by 270 ° from the output signal of the piezoelectric element 5, that is, 90 °. The phase will be shifted. In this way, the second PLL circuit 16b causes the piezoelectric element 4 to
And the piezoelectric element 5 are locked so that the output signal always has a constant potential difference.

By the way, from the oscillation circuit 11 to the piezoelectric element 3,
When a drive signal is applied to the piezoelectric element 4, the vibrating body 2 flexurally vibrates in the direction perpendicular to the surface on which the piezoelectric element 5 is formed, and the same signal is output from the piezoelectric elements 3 and 4. When the vibrating gyro 31 rotates about the rotary shaft 2a of the vibrating body 2, Coriolis force acts, and the vibrating body 2 vibrates in a direction different from the vibrating direction when it is not rotating, and the piezoelectric elements 3 and 4 mutually vibrate. Different signals are output. Since the change in this signal corresponds to the change in the vibration direction of the vibrating body 2, the output signals of the piezoelectric elements 3 and 4 are signals corresponding to the rotational angular velocity. Therefore, the rotational angular velocity applied to the vibration gyro 31 can be detected by detecting the difference between the output signals of the piezoelectric elements 3 and 4 by the differential amplifier circuit.

Here, as described above, the output signals of the piezoelectric elements 3 and 4 are different from the output signals of the piezoelectric element 5, respectively.
Since the phase is always locked so that it shifts 90 °,
Even when the characteristics of the vibrating body 2 change due to temperature changes and changes over time, the generation of drift signals from the piezoelectric elements 3 and 4 is suppressed, and accurate rotational angular velocity can be detected.

As shown in FIG. 5, the midpoint between the low-pass filter 14a and the capacitance adding circuit 15a is connected to the inverting input terminal (not shown) of the differential amplifier circuit 17, and the low-pass filter 14b and the capacitance adding circuit are connected. Even in the vibration gyro 41 configured by connecting the intermediate point with 15b to the non-inverting input terminal (not shown) of the differential amplifier circuit 17, the same effect as that of the vibration gyro 31 can be obtained.

Further, in the first and second embodiments, the PLL circuit is used to provide a space between the detecting piezoelectric element and the driving piezoelectric element, and between the detecting and driving piezoelectric element and the feedback piezoelectric element. The phase difference of the output signal with the piezoelectric element is 90
I explained about the case of keeping the angle of
It may be set to a value other than 90 °.

Further, in the above first and second embodiments, the case where the vibrating body has a triangular prism shape has been described.
The present invention can be applied to a vibrating gyroscope including a vibrating body having a columnar shape or a polygonal column shape as long as it has a columnar shape.

[0031]

According to the vibrating gyroscope of the present invention,
With the PLL circuit, the phase difference of the output signal is always kept constant between the detecting piezoelectric element and the driving piezoelectric element, or between the detecting and driving piezoelectric element and the feedback piezoelectric element. Therefore, even if the characteristics of the vibrating body change due to temperature change or temporal change, it is possible to prevent the detection piezoelectric element from generating a drift signal, and it is possible to detect an accurate rotational angular velocity.

[Brief description of the drawings]

FIG. 1 is an illustrative view showing a vibrating gyroscope according to a first embodiment of the present invention.

FIG. 2 is a cross-sectional view showing a vibrating body that constitutes the vibrating gyro of FIG.

FIG. 3 is an illustrative view showing a vibration gyro that is a partial modification of the vibration gyro of FIG.

FIG. 4 is an illustrative view showing a vibrating gyroscope according to a second embodiment of the present invention.

FIG. 5 is an illustrative view showing a vibration gyro that is a partial modification of the vibration gyro of FIG.

FIG. 6 is an illustrative view showing a conventional vibrating gyro.

[Explanation of symbols]

 1, 21, 31, 41 Vibration gyro 2 Vibrating body 3, 4, 5 Piezoelectric element 16a, 16b PLL circuit

Claims (2)

[Claims] 1. A columnar vibrating body, a driving piezoelectric element formed on a side surface of the vibrating body for driving the vibrating body, and a rotational angular velocity formed on another side surface of the vibrating body. A vibration gyro including a piezoelectric element for detection to obtain an output, for maintaining a constant phase difference between the output signal of the piezoelectric element for driving and the output signal of the piezoelectric element for detection. A vibrating gyro that includes a PLL circuit. 2. A columnar vibrating body, a piezoelectric element for driving for driving the vibrating body formed on a side surface of the vibrating body, and a detecting piezoelectric element for obtaining an output corresponding to a rotational angular velocity, A vibrating gyro including a piezoelectric element for feedback when the vibrating body is formed on the other side surface of the vibrating body, the output signal of the piezoelectric element for driving and detecting, and the feedback A vibration gyro, comprising a PLL circuit for maintaining a constant phase difference with an output signal of a piezoelectric element.