JPH05126585A - Vibration gyro - Google Patents

Abstract

PURPOSE:To bring about a stable self-induced vibration of a vibrator, to ensure also high precision in detection of an angular velocity and, besides, to enable easy and quick assembly of the vibrator. CONSTITUTION:A vibrator 6 is constructed by sticking two sets of piezoelectric elements 21 and 22 on the lateral surfaces 1a and 1b of a vibrating body having a polygonal cross section and the respective sets of the piezoelectric elements 21 and 22 of this vibrator 6 are connected to one driving means 7 for vibration through their capacity elements C1 and C2 respectively, while this driving means 7 for vibration is connected also to two resistance elements R1 and R2 connected in series to each other. The sum of outputs of connecting parts 24 and 25 of the respective sets of the piezoelectric elements 21 and 22 with the capacity elements C1 and C2 is fed back to the driving means 7 for vibration differentially with a reference output of a connecting part 28 of the resistance elements R1 and R2, while the respective outputs of the connecting parts 24 and 25 of the respective sets of the piezoelectric elements 21 and 22 with the capacity elements C1 and C2 are taken out differentially with each other.

Description

Detailed Description of the Invention

[0001]

This invention relates to two sets of piezoelectric elements,
In addition to demonstrating the drive, feedback and detection functions,
By generating an accurate reference voltage,
The present invention relates to a vibration gyro that always provides stable self-excited vibration and enables detection of angular velocity with high accuracy.

[0002]

2. Description of the Related Art As a conventional vibrating gyroscope, for example,
The ones shown in block diagrams in FIGS. 8 and 9 are known. Here, in the vibrating gyroscope shown in FIG. 8, the driving piezoelectric element 2 is attached to one side surface of the vibrating body 1 having a quadrangular cross-sectional shape, and the feedback piezoelectric element 3 is provided on the side surface opposite to the side surface. Is attached, and the other two side faces orthogonal to these side faces are provided with the detection piezoelectric elements 4, 5 respectively.
The vibrator 6 is configured by sticking the above. The vibrator 6 supplies the output from the driving device 7 to the driving piezoelectric element 2, while the output of the feedback piezoelectric element 3 is applied to the driving device 7. By directly returning to, the predetermined self-excited vibration is performed in the X-axis direction of the orthogonal three-dimensional coordinate system. When the vibrator 6 is rotated around the Z axis under such self-excited vibration, the vibrator 6 is caused to vibrate in the Y axis direction by the generation of Coriolis force, and the vibration in the Y axis direction occurs. The accompanying voltage
Since they are generated in the respective detection piezoelectric elements 4 and 5, their respective output voltages are sequentially passed through the differential amplifier 8, the synchronous detector 9 and the DC amplifier 10, so that the angular velocity of the vibrator 6 is DC output. Is required as.

The vibrating gyro shown in FIG. 9 has driving piezoelectric elements 11 and 12 attached to each of two side surfaces of the vibrating body 1 whose cross-sectional shape is a triangle, and the other side surface for returning. The vibrator 6 is configured by sticking the piezoelectric element 3, and the output from the driving device 7 is transmitted to the respective resistors 13, 14
To vibrate the vibrator 6 by self-excited oscillation in the X-axis direction by supplying it to the driving piezoelectric elements 11 and 12 via the actuator and directly returning the output from the feedback piezoelectric element 3 to the driving device 7 as well. Is. Here, the oscillator 6 is rotated around the Z-axis by differentially amplifying the voltage generated in each of the driving piezoelectric elements 11 and 12 which also serve as the detecting piezoelectric element, performing synchronous detection, and then performing DC amplification. It is possible to detect the Coriolis force in the Y-axis direction, and thus the angular velocity, generated by the above.

[0004]

By the way, in the former vibrating gyro shown in FIG. 8, the respective piezoelectric elements 2, 3, 4, 5 are bonded to the vibrating body 1 by an epoxy resin or other adhesive. Therefore, due to changes in the adhesive strength, elastic properties, and other physical properties due to changes in ambient temperature, for example, the characteristic difference between the driving piezoelectric element 2 and the feedback piezoelectric element 3 changes. However, there is a problem in that the vibration conditions fluctuate, which makes the self-excited vibration of the vibrator 6 unstable. In addition, when a temperature cycle is applied, there is also a problem that the properties of the adhesive change over time, causing hysteresis in the driving conditions. Furthermore, the change in the adhesive strength of the detection piezoelectric elements 4 and 5 causes the drift. There was also the problem of becoming.

Further, due to variations in the characteristics of the piezoelectric elements 2, 3, 4, 5 and the asymmetry of the sectional shape of the vibrating body 1,
Ideally, vibration in the Y-axis direction, which does not occur when the vibrator 6 is not rotating, actually occurs, causing a so-called leakage voltage. Moreover, the magnitude of this leakage voltage is also
There is a problem that the voltage changes depending on the driving voltage and other driving conditions and causes a drift. Further, in the case of this conventional technique, there is a problem that the assembly work of the vibrator 6 is extremely troublesome because each piezoelectric element needs to be bonded to each side surface of the vibrating body 1 with high accuracy.

In the prior art shown in FIG. 9, since the driving piezoelectric elements 11 and 12 are also used as the detecting piezoelectric elements, the change in leakage voltage due to the change in the physical properties of the adhesive is shown in FIG. It can be reduced from that of the prior art.
However, also in this conventional technique, since the feedback piezoelectric element 3 is separately provided as in the case of FIG. 8, the same problem as described above remains with respect to the vibration condition.

The present invention advantageously solves such a problem of the prior art, facilitates the assembly work of the vibrator, and effectively reduces the fluctuation of the driving condition due to the influence of the adhesive. Provided is a vibration gyro which can suppress a change in leakage voltage to a sufficiently small level.

[0008]

A vibrating gyroscope of the present invention comprises a vibrator in which two sets of piezoelectric elements are attached to the side surfaces of a vibrating body whose cross-sectional shape is polygonal. The piezoelectric elements of the group are connected to one vibration driving means through the respective capacitive elements, and this vibration driving means is also connected to two resistance elements connected in series. The sum of the respective outputs of the connecting portions of the piezoelectric element and the capacitive element of the set is fed back to the vibration drive means by making a differential with the reference output of the connecting portion of the respective resistance elements, and the piezoelectric element and the capacitive element of each set This is to take out the outputs of the connection parts of and by making them differential with each other. Here, more preferably, the two resistance elements connected in series to each other are made into one variable resistor, so that the reference output is connected to one of the fixed terminals to the vibration driving means. Take out from the movable terminal of.

Further, in another vibration gyro, in particular, one vibration driving means is connected to each set of piezoelectric elements via each capacitance element, and two resistances connected in series are also used. When two sets of elements were also connected in parallel, each output of the connection section of the piezoelectric element and the capacitive element of each set was differentiated from the reference output of the connection section of each resistance element of each set, and The sum of the differential outputs is fed back to the vibration drive means, and each output of the connecting portion between the piezoelectric element and the capacitive element of each set is differentially obtained and taken out.
Here again, it is more preferable that the resistance element connection structure of each set is a variable resistor so that each reference output is connected to each of the variable resistors whose one fixed terminal is connected to the vibration driving means. Take out from the movable terminal.

[0010]

When a stress is applied to the piezoelectric element, the piezoelectric element generates strain and the piezoelectric effect causes an electric displacement proportional to the stress. When an electric field is applied, the piezoelectric element causes an electric displacement and the inverse piezoelectric effect causes a proportional electric field. Strain. Therefore, when an AC voltage is applied to the piezoelectric element via the capacitive element, the applied AC voltage and the voltage generated due to the distortion of the piezoelectric element are combined at the connection portion between the piezoelectric element and the capacitive element. Voltage is observed.

Therefore, in the vibrating gyroscope of the present invention, by applying an AC voltage to the two sets of piezoelectric elements attached to the side surface of the vibrating body, self-excited vibration of the vibrator is caused, and By separating and extracting the voltage generated with strain in each direction for each strain direction, two sets of piezoelectric elements have three functions of drive, feedback, and detection. The reference output of was made sufficiently accurate.

Thus, according to the vibrating gyroscope of the present invention, the influence of the adhesive on the driving condition is reduced,
It is possible to suppress the occurrence of hysteresis in the driving condition even when a temperature cycle or the like is applied, and to suppress the change in the leakage voltage to be sufficiently small. Moreover, in the vibrating gyroscope according to the present invention, it is sufficient to attach two sets of piezoelectric elements, so that the assembling work of the vibrator can be performed simply and quickly. Furthermore, by accurately canceling the drive voltage component with the reference output, it is possible to extract only the voltage generated due to the drive distortion of the vibrator with high accuracy, and as a result, the self-excited vibration of the vibrator is extremely reduced. It can be stable.

[0013]

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a vibrator that can be applied to the vibration gyro according to the present invention. Figure 1
In (a), the first piezoelectric element 21 is attached to one side surface 1a of the vibrating body 1 having a triangular cross section, for example, an equilateral triangle, and the second piezoelectric element 21 is attached to the other side surface 1b adjacent to the side surface 1a. The vibrator 6 is configured by attaching the piezoelectric element 22. In addition, the vibrator 6 shown in FIG. 1 (b) has a first piezoelectric element 21 attached to one side surface 1c of the vibrating body 1 having a quadrangular cross section, for example, a regular quadrangle, and a corner formed on the side surface 1c. The second piezoelectric element 22 is attached to the other side surface 1d that is adjacent to the side surface of the vibrator 1 shown in FIG. 1 (c). One piezoelectric element 21b is attached to 1c, and the electrode of this piezoelectric element 21b is attached to the vibrating body 1
Is divided into two in the width direction of each of the divided electrodes 21c and 21d. It is needless to say that such division can be performed not only on the electrodes but also on the entire piezoelectric element 21b. In FIG. 1 (d), piezoelectric elements 21 and 21a forming a pair are attached to one side surface 1c of the vibrating body 1 having a quadrangular cross section and the opposing side surface 1e thereof, respectively.
The vibrator 6 is constructed by attaching other sets of piezoelectric elements 22 and 22a to the other two side surfaces 1d and 1f.

FIG. 2 is a block diagram showing an embodiment of the present invention using such a vibrator 6. In this example, the oscillator 6 shown in FIG. 1A is used, but it goes without saying that any other oscillator 6 can be similarly applied. Here, each piezoelectric element
21 and 22 are connected to the driving device 7 via the respective capacitive elements C ₁ and C ₂ , and the driving device 7 is also connected to the _two resistance elements R ₁ and R ₂ connected in series with each other. As a result, the AC voltage from the driving device 7 can be simultaneously applied to the resistance elements R ₁ and R ₂ as well as the piezoelectric elements 21 and 22.

On the other hand, the connecting portions 24 and 25 of the respective capacitive elements C ₁ and C ₂ and the respective piezoelectric elements 21 and 22 are connected to the differential amplifier 27 via the adder 26, and the adder 26 , The outputs from both of these connections 24, 25 are summed, and the differential amplifier 27
Then, the reference voltage from the mutual connecting portion 28 of the resistance elements R ₁ and R ₂ and the output from the adder 26 are differentially amplified, and the differential output from the reference voltage is fed back to the driving device 7. And even more,
Each capacitive element C ₁ , C ₂ and each piezoelectric element 21,
The connection portions 24 and 25 to 22 are connected to another differential amplifier 8, and this differential amplifier 8 is sequentially connected to the synchronous detector 9 and the DC amplifier 10 as in the prior art.

According to the vibrating gyroscope constructed as described above, the vibrator 6 can be driven and vibrated in the X-axis direction by applying an AC voltage from the driving device 7 to the respective piezoelectric elements 21 and 22. In the vibrating state, the output from each of the connecting portions 24 and 25 is accompanied by the supply voltage from the driving device 7 and the strain of each of the piezoelectric elements 21 and 22,
It is a combined output with the voltage output from each of the piezoelectric elements 21 and 22. Therefore, both of these combined outputs are added by the adder 26.
After adding in, by passing it through the differential amplifier 27,
Each capacitive element C ₁ , C ₂ and each piezoelectric element 2
The voltage generated from the piezoelectric elements 21 and 22 based on the vibration in the X-axis direction under the action of the respective resistance elements R ₁ and R ₂ whose resistance ratio is appropriately adjusted in relation to the impedance distribution ratio of 1 and 22. It is possible to make the self-excited vibration of the vibrator 6 sufficiently stable by accurately extracting only that and feeding back the differential output to the driving device 7.

Under the self-excited vibration of the vibrator 6, when the vibrator 6 is rotated around the Z axis, the vibrator 6 moves in the Y axis direction based on the Coriolis force. Vibration is generated, which causes a difference in the output voltage of the connection portions 24 and 25. Therefore, by differentially amplifying both of these output voltages by the differential amplifier 8, the influence of the leakage voltage can be removed, and the voltage associated with the generation of the Coriolis force can be accurately separated and detected.

FIG. 3 is a modification of the embodiment shown in FIG. 2, in which the polarization direction of either one of the piezoelectric elements 121, 122 attached to the respective side faces 1a, 1b of the vibrating body 1 is set. 2 is reversed from that shown in FIG. 2 so that the strain and the output voltage are reversed between the piezoelectric elements 121 and 122. Therefore, differentiating the outputs of the respective connection parts 24a and 25a has the same meaning as adding in the example shown in FIG. 2, and adding these outputs is different in FIG. It has the same meaning as moving.

Therefore, in this example, the connecting portion 24 between the respective capacitive elements C ₁ and C ₂ and the respective piezoelectric elements 121 and 122 is used.
a, 25a is first connected to a differential amplifier 29 which differentially outputs the outputs from those connections 24a, 25a from each other, and this differential amplifier 29 is connected to the differential output from the differential amplifier 29 with respect to a reference voltage. While being connected to the drive unit 7 via the differential amplifier 27, the two connecting portions 24a and 25a are connected to the synchronous detector 9 via the adder 30.
Also connect to. Incidentally, here, each piezoelectric element 121,
It is assumed that either one of the drive voltages supplied to 122 is inverted by 180 degrees. It is needless to say that such a vibration gyro can bring about the same effect as that described with reference to FIG.

FIG. 4 is a block diagram showing another embodiment of the present invention. In this example, the driving device 7 is connected to the respective piezoelectric elements 21 and 22 via the respective capacitive elements C ₁ and C _2, and two resistance elements connected in series are also provided.
R _3, R ₄ and R _5, connected in parallel to each R _6, and the connection portion 24, a differential performing differential between the reference outputs of the resistive element R _3, R ₄ of the connecting portion 36 To the amplifier 33 and the connection 25,
Connected to a differential amplifier 34 that performs differential with respect to a reference output of a connection portion 37 of both resistance elements R ₅ and R ₆ , and further drive both differential amplifiers 33 and 34 via an adder 35 It is connected to the device 7, and other configurations are similar to those of the embodiment shown in FIG.

Therefore, here, the differential amplifier 33 differentially amplifies the reference output from the connecting portion 36 of the resistance elements R ₃ and R ₄ and the output from the connecting portion 24, and the differential amplifier 34 Double resistance element
The reference output from the connection portion 37 of R ₅ and R ₆ and the output from the connection portion 25 are differentially amplified, and both of them separately detect only the voltage generated by the vibration of the vibrator 6 in the X-axis direction. Further, the adder 35 adds both of the differential amplified outputs to feed back both detection voltages of the respective piezoelectric elements 2 and 3 in accordance with the drive device 7, and stabilizes the self-excitation of the vibrator 6. Cause vibration.

In such a vibrating gyro, the Coriolis force during rotation of the vibrator 6 is generated by the respective connecting portions 24,
By inputting the output of 25 to another differential amplifier 8 and making it differential, it is possible to separate and detect as in the case described above.

In the above description, in detecting the separation of the Coriolis force, the outputs of the connecting portions 24 and 25 are directly input to the differential amplifier 8. However, as shown in FIG. Also by inputting the outputs from the differential amplifiers 33 and 34 of FIG.
The Coriolis force, and thus the angular velocity, can be detected in the same manner as shown in FIG.

By the way, when the oscillator 6 and the reference voltage generating portion in FIGS. 4 and 5 are equivalently represented, FIG.
In order to always make the self-excited vibration of the vibrator 6 appropriate, the resistance elements R _{3 and} R ₃ should be equal to the impedance distribution ratio of the capacitive element C ₁ and the piezoelectric element 21. , R ₄ by adjusting the resistance ratio
It is desirable to completely cancel the drive voltage component between 4, 36, and at the same time, also on the piezoelectric element 22 side, adjust the resistance ratio of the resistance elements R ₅ and R _{6 in} the same manner. Setting each resistance value is very troublesome. Therefore, preferably, as shown in FIG.
R ₃ and R ₄ are one variable resistor VR ₁ and the resistance element
The R _5, R _6, as a variable resistor VR ₂ other one, each one fixed terminal of the variable resistor VR _1, VR ₂ with connecting to the vibration drive means, their respective movable terminal It functions as the respective connection parts 36 and 37.

According to this, each variable resistor is
By adjusting the position of the movable terminals of VR ₁ and VR ₂ ,
The driving voltage component between the connecting parts 24 and 36 and between the connecting parts 25 and 37 can be canceled almost completely easily and easily, and as a result, the more stable self-excited vibration of the oscillator can be realized quickly. can do. Although the present invention has been described based on the illustrated example, it goes without saying that the variable resistor can be applied to the embodiments shown in FIGS. 2 and 3.

[0026]

As is apparent from the above description, according to the present invention, by providing two sets of piezoelectric elements on the side surface of the vibrating body, it is always possible to provide stable feedback without providing a feedback piezoelectric element. Can bring about self-excited vibration,
Moreover, the angular velocity can be detected with high accuracy. In other words, by making the two sets of piezoelectric elements perform the three functions of drive, feedback, and detection, the influence of the adhesive on the drive conditions can be sufficiently reduced, and the drive conditions when a temperature cycle or the like is applied. It is possible to effectively suppress the occurrence of hysteresis and suppress the change of the leakage voltage to a sufficiently small level. As a result, it is possible to always provide stable self-excited vibration and ensure high detection accuracy.

Furthermore, in this case, since the vibrator can be constructed by simply sticking two sets of piezoelectric elements to the vibrator, the vibrator can be assembled very easily and quickly.

[Brief description of drawings]

FIG. 1 is a front view showing a configuration example of a vibrator applicable to the present invention.

FIG. 2 is a block diagram showing an embodiment of the present invention.

FIG. 3 is a block diagram showing a modified example of the example shown in FIG.

FIG. 4 is a block diagram showing another embodiment of the present invention.

FIG. 5 is a block diagram showing still another embodiment of the present invention.

FIG. 6 is an equivalent circuit diagram of a vibrator and a reference voltage generating portion of the examples shown in FIGS. 4 and 5.

FIG. 7 is an equivalent circuit diagram showing a modified example of the example shown in FIG.

FIG. 8 is a block diagram showing a conventional example.

FIG. 9 is a block diagram showing another conventional example.

[Explanation of symbols]

1 Vibrating body 1a, 1b, 1c, 1d, 1e, 1f Side surface 6 Transducer 7 Drive device 8, 27, 29, 33, 34 Differential amplifier 9 Synchronous detector 10 DC amplifier 21, 21a, 21b, 22, 22a, 121, 122 Piezoelectric element 24, 24a, 25, 25a, 28, 36, 37 Connection section 26, 30, 35 Adder C ₁ , C ₂ Capacitance element R ₁ , R ₂ , R ₃ , R ₄ , R ₅ , R _6- resistor element VR ₁ , VR ₂ variable resistor

Claims (4)

[Claims] 1. A vibrator is constructed by attaching two sets of piezoelectric elements to the side surfaces of a vibrating body having a polygonal cross section, and each set of piezoelectric elements of the vibrator is replaced by a capacitive element. Connection to one vibration drive means, and this vibration drive means is also connected to two resistance elements connected in series with each other. The sum of each output of
It is characterized in that it is differential with respect to the reference output of the connection part of each resistance element and is fed back to the vibration drive means, and each output of the connection part of the piezoelectric element and the capacitive element of each set is made to be mutually differential and taken out. Vibration gyro to be. 2. The vibration gyro according to claim 1, wherein the reference output is taken out from a movable terminal of a variable resistor having one fixed terminal connected to a vibration driving means. 3. A vibrator is constructed by attaching two sets of piezoelectric elements to the side surfaces of a vibrating body having a polygonal cross section, and each set of piezoelectric elements of the vibrator is replaced by a capacitive element. Via a single vibration drive means, and this vibration drive means is also connected in parallel to two sets of two resistance elements connected in series with each other. Each output of the connection with the capacitive element is made differential with the reference output of the connection of each resistance element of each set,
A vibration gyro, wherein the sum of each differential output is fed back to the vibration drive means, and each output of the connecting portion of each set of the piezoelectric element and the capacitive element is differentially obtained. 4. The vibration gyro according to claim 3, wherein each reference output is taken out from each movable terminal of each variable resistor whose one fixed terminal is connected to the vibration driving means.