JP3682664B2 - Piezoelectric vibration gyro - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a so-called piezoelectric device that uses ultrasonic vibration of a piezoelectric vibrator, in particular, in a gyroscope used for attitude control of a moving body itself such as a ship or an automobile and equipment mounted thereon, an automobile navigation system, or the like. It relates to a vibrating gyroscope.
[0002]
[Prior art]
A piezoelectric vibrating gyroscope is a gyroscope that utilizes a dynamic phenomenon that when a rotating angular velocity is applied to a vibrating object, a Coriolis force is generated in a direction perpendicular to the vibrating direction. In a vibration system configured so that excitation and detection in two directions orthogonal to each other are possible, in a state where one vibration is excited, when the vibrator itself is rotated about a line where two vibration surfaces intersect, Due to 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 this 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 is determined from the magnitude of the output voltage proportional to the magnitude of this vibration. Can be requested.
[0003]
An outline of the structure of a piezoelectric vibrator used in such a conventional piezoelectric vibration gyro is shown in FIG.
[0004]
As shown in FIG. 8, this piezoelectric vibrator has piezoelectric elements 106 and 108 on the surface 102 in the X direction and the surface 104 in the Y direction of the tuning fork type piezoelectric vibrator 100 made of a constant elastic metal such as Elinvar, respectively. Lead wires 110 and 112 are used for electrical connection between the piezoelectric elements 106 and 108 and a drive / detection unit (not shown). In this piezoelectric vibrator, when a voltage is applied to the piezoelectric element 106 provided on the surface 102 in the X direction via the lead wire 110 and vibration in the X direction is excited and a rotational angular velocity is applied, the Coriolis force causes The vibration in the Y direction is excited, the vibration in the Y direction is converted into a change in voltage by the piezoelectric element 108 provided on the surface 104 in the Y direction, and the rotational angular velocity is detected from the detected voltage via the lead wire 112. ing.
[0005]
[Problems to be solved by the invention]
In the piezoelectric vibrator 100 used in the conventional piezoelectric vibration gyro described above, the piezoelectric elements 106 and 108 are provided on the surface 102 in the X direction and the surface 104 in the Y direction, respectively. Processing such as bonding 106 and 108 is difficult, and it is difficult to downsize the piezoelectric vibrator 100. Further, the accuracy is lowered due to the influence of the displacement of the bonding position and the like, and the accuracy is sometimes lowered due to the influence of the adhesive layer. On the other hand, since the lead wires 110 and 112 are used for electrical connection, it is not easy to assemble and obstructs the manufacture of an inexpensive piezoelectric vibrating gyroscope.
[0006]
The object of the present invention is to eliminate the disadvantages of the conventional piezoelectric vibration gyro described above, and to obtain a small and highly accurate piezoelectric vibration gyro with a simple structure that is not affected by the adhesion of the piezoelectric element and has good mass productivity. It is in.
[0007]
[Means for Solving the Problems]
In the present invention, electrical connection and fixing are achieved by providing a connection land on the base portion of the piezoelectric vibrator with a simple configuration in which electrodes are arranged only on one surface of a tuning fork vibrator made of a single piezoelectric element. A piezoelectric vibration gyro capable of simultaneously performing the above is provided.
[0008]
That is, according to the present invention, when a rotational angular velocity is given to a vibrating object (hereinafter, this excited vibration direction is referred to as X direction), a direction perpendicular to the excitation direction (hereinafter referred to as this vibration direction). Among the gyroscopes using a mechanical phenomenon that generates Coriolis force in the Y direction), a vibrator configured to be able to excite and detect the X and Y directions orthogonal to each other using piezoelectric characteristics. In the piezoelectric vibration gyro configured by using the vibrator, the vibrator is composed of a tuning fork type piezoelectric element including at least one surface parallel to the X direction or the Y direction, and is parallel to either the X direction or the Y direction. An electrode is provided on only one surface, and a piezoelectric vibration gyro is obtained in which the electrodes are formed as three strip electrodes for each of the resonance parts of the tuning fork type.
[0009]
On the other hand, according to the present invention, when a rotational angular velocity is given to a vibrating object (hereinafter, the direction of vibration to be excited is referred to as X direction), a direction perpendicular to the excitation direction (hereinafter, direction of this vibration). Among the gyroscopes using a mechanical phenomenon that generates Coriolis force in the Y direction), a vibrator configured to be able to excite and detect the X and Y directions orthogonal to each other using piezoelectric characteristics. In the piezoelectric vibration gyro configured by using the vibrator, the vibrator is composed of a tuning fork type piezoelectric element including at least one surface parallel to the X direction or the Y direction, and is parallel to either the X direction or the Y direction. An electrode is provided only on one surface, and the electrode is connected to a connection land portion provided to electrically connect and fix the vibrator to the circuit board on the base portion of the tuning fork type. Established as In which the piezoelectric vibration gyro is obtained.
[0010]
In the former piezoelectric vibration gyro, the middle one of the three strip electrodes is connected to the vibrator drive circuit as a first drive terminal and a second drive terminal, and the first drive terminal and A drive voltage having an opposite phase is applied to the second drive terminal, or two detection terminals included in each of the three strip electrodes are connected to the inverting terminals of the operational amplifiers constituting the current detection circuit, respectively. In addition, the potential is fixed to the reference potential of the drive detection circuit by the virtual ground function of the operational amplifier, and further, the vibrator is driven by applying a voltage between the reference potential and the drive terminal. The configuration is such that vibration in the X direction and the Y direction can be detected using the output of the current detection circuit connected to the detection terminal, or among the detection terminals included in each of the three strip electrodes, the outside of the vibrator Detection terminals are in some sense terminal other and inside, be used to connect on a circuit board to the base portion or connecting of the transducer are both preferred.
[0011]
In the latter piezoelectric vibration gyro, the connection land portion is provided on the circuit board for direct electrical connection and fixation, and the circuit board secures a vibration portion in the vibrator. It is preferable that the notch for the contact is provided so as not to contact the circuit board.
[0012]
【Example】
Hereinafter, a piezoelectric vibration gyro according to an embodiment of the present invention will be described in detail with reference to the drawings.
[0013]
FIG. 1 is a perspective view showing a piezoelectric vibrator used in a piezoelectric vibration gyro according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view showing an electrode arrangement and a polarization direction of the piezoelectric vibrator shown in FIG. is there. The arrows in FIG. 2 indicate the polarization direction of the piezoelectric vibrator.
[0014]
As shown in FIG. 1, this piezoelectric vibrator has band-like electrodes 5, 7, 9, 11, 13, and the like by screen printing on one side 3 in the X direction of a tuning fork type piezoelectric vibrator 1 made of piezoelectric ceramics such as PZT. 15 is formed, and the piezoelectric vibrator is polarized in the direction indicated by the arrow in FIG. In this embodiment, the strip electrodes 5 and 15 and the strip electrodes 9 and 11 are shown as being connected to each other at the base portion of the piezoelectric vibrator or the circuit board portion to be connected, but may be configured to be used independently. That is, the piezoelectric vibrator here is composed of a tuning fork type piezoelectric element including at least one surface parallel to the X direction or the Y direction, and the electrode is formed only on one surface parallel to either the X direction or the Y direction. The electrodes are formed as three strip electrodes 5, 7, 9 and strip electrodes 11, 13, 15 for each of the resonance parts of the tuning fork type.
[0015]
The end portions of the strip electrodes 5, 7, 9, 11, 13, 15 are provided for connection to the base portion of the piezoelectric vibrator 1 so as to electrically connect and fix the piezoelectric vibrator to the circuit board. It extends so as to be connected to the land portion 17. The piezoelectric vibrator 1 is electrically connected and fixed by soldering or the like to a circuit board 23 having a notch portion 19 and a piezoelectric vibrator mounting land 21 as shown in FIG. That is, the vibrator mounting land 21 here is provided on the circuit board 23, and the piezoelectric vibrator 1 is directly connected to the connecting land portion 17 by solder or the like without using a support or a lead wire. For electrical connection and fixing. For this reason, the circuit board 23 is provided with a notch for securing a vibration part in the piezoelectric vibrator 1 so as not to contact the circuit board 23.
[0016]
FIG. 6 shows a drive detection circuit applied to a piezoelectric vibrator in order to produce a piezoelectric vibration gyro according to an embodiment of the present invention.
[0017]
The strip electrodes 5 and 15 provided in the piezoelectric vibrator 1 are connected on the base portion or the circuit board, and are connected to the first current detection circuit 31. Similarly, the strip electrodes 9 and 11 are connected to the second electrode 9 and 11 respectively. The current detection circuit 32 is connected. The outputs of the first current detection circuit 31 and the second current detection circuit 32 are connected to a differential circuit 33, and the output of the differential circuit 33 is sent to a synchronous detection circuit 34 and a rectifier circuit 35 connected thereto. Yes.
[0018]
Hereinafter, the operation of the piezoelectric vibrating gyroscope according to the embodiment of the present invention will be described in detail with reference to the drawings.
[0019]
Between the strip electrodes 5 and 7 and between the strip electrodes 7 and 9, between the strip electrodes 11 and 13, and between the strip electrodes 13 and 15, each operates independently as an electro-mechanical conversion element. When an in-phase voltage is applied between the strip electrodes 5 and 7 and between the strip electrodes 7 and 9, the piezoelectric vibrator 1 vibrates in the X direction.
[0020]
For vibration in the X direction (vibration in the direction of the arrow in FIG. 3), between the strip electrodes 5 and 7 and between the strip electrodes 7 and 9, between the strip electrodes 11 and 13 and between the strip electrodes 13 and 15, As shown in FIG. 3, an in-phase electric field is generated. That is, a-(minus) electric field is generated between the strip electrodes 5 and 7 and between the strip electrodes 7 and 9, and a + (plus) electric field is generated between the strip electrodes 11 and 13 and between the strip electrodes 13 and 15. To do.
[0021]
On the other hand, with respect to the vibration in the Y direction (vibration in the arrow direction in FIG. 4), between the strip electrodes 5 and 7 and between the strip electrodes 7 and 9, and between the strip electrodes 11 and 13 and between the strip electrodes 13 and 15. As shown in FIG. 4, a reverse phase electric field is generated. That is, a positive and negative electric field is generated between the strip electrodes 5 and 7 and between the strip electrodes 7 and 9, and a negative and positive electric field is generated between the strip electrodes 11 and 13 and between the strip electrodes 13 and 15, respectively. Will occur.
[0022]
The strip electrodes 5, 9, 11, 15 are connected to the input terminals of the first current detection circuit 31 and the second current detection circuit 32 described above. Each input terminal in the first current detection circuit 31 and the second current detection circuit 32 is connected to the inverting terminal of the operational amplifier 41 as shown in FIG. 7, and the operational amplifier 41 is negatively fed back by the resistor 42. And the non-inverting terminal is connected to the reference potential of the first drive circuit 36 and the second drive circuit 37, thereby configuring the first current detection circuit 31 and the second current detection circuit 32 described above. doing. The potential of each input terminal of the first current detection circuit 31 and the second current detection circuit 32, that is, the inverting terminal of the operational amplifier 41 becomes the same potential as the non-inverting terminal by the virtual ground function of the operational amplifier 41, and becomes the reference potential. It is fixed.
[0023]
The strip electrode 7 is connected to the first drive circuit 36, and the strip electrode 13 is connected to the second drive circuit 37. The strip electrode 7 and the strip electrode 13 are each applied with an alternating voltage having a substantially opposite phase and a frequency substantially equal to the resonance frequency of the piezoelectric vibrator 1, thereby exciting vibrations in the X direction as indicated by arrows in FIG. 3.
[0024]
With respect to the vibration in the X direction, as shown in FIG. 3, a reverse phase current is output from the strip electrodes 5 and 15, but the strip electrodes 5 and 15 are connected. Are canceled out and are not output from the first current detection circuit 31. Similarly, reverse-phase currents are output from the strip electrodes 9 and 11, and the strip-shaped electrodes 9 and 11 are connected. Therefore, the reverse-phase currents are canceled and are not output from the second current detection circuit 32. .
[0025]
When a rotational angular velocity is applied with the Z-axis direction as an axis while vibrating in the direction indicated by the arrow in FIG. 3, the vibration in the Y direction as indicated by the arrow in FIG. 4 is excited by the Coriolis force. With respect to the vibration in the Y direction, currents of the same phase are output from the strip electrodes 5 and 15 as shown in FIG. 4, and the output current of the strip electrodes 5 and 15 is added to the first current detection circuit 31. Output (about twice). Similarly, since currents in the same phase are output to the strip electrodes 9 and 11, the output obtained by adding the outputs of the strip electrodes 9 and 11 is obtained in the second current detection circuit 32. Here, as shown in FIG. 4, the electrodes 5 and 15 and the electrodes 9 and 11 output in opposite phases, so that the first current detection circuit 31 and the second current detection circuit 32 are opposite to each other. The output of the phase.
[0026]
Outputs of the first current detection circuit 31 and the second current detection circuit 32 are input to the differential circuit 33, and are synchronously rectified by the synchronous detection circuit 34 and the rectification circuit 35, and are directly proportional to the Coriolis force, that is, rotate. An output voltage proportional to the angular velocity can be obtained.
[0027]
【The invention's effect】
When the piezoelectric vibration gyro of the present invention is configured, the piezoelectric vibrator can realize a mechanical function called “vibrating body” and a function as an “electro-mechanical conversion element” for driving and detecting vibration in a single element. This simplifies the configuration of the piezoelectric vibrator without having an adhesive layer. In addition, since the electrodes are provided only on one side, the electrodes can be easily formed and polarized, and a small and inexpensive piezoelectric vibration gyro can be obtained. Moreover, in the piezoelectric vibration gyro according to the present invention, the electrical connection between the piezoelectric vibrator and the circuit board is performed by directly soldering the circuit board and the connection land portion of the piezoelectric vibrator without using a lead wire or the like. At the same time, the circuit board and the piezoelectric vibrator are fixed with solder, so that a piezoelectric vibration gyro that is very easy to assemble, is small, and inexpensive can be manufactured. Further, since there is no adhesive layer, there is no influence of the adhesive error of the piezoelectric element, the influence of the adhesive layer, and there is no lead wire, so that a piezoelectric vibration gyro with higher accuracy and higher reliability than before can be obtained. Further, in the drive detection circuit, it is possible to cancel out the vibration generated in the same phase in the two resonance parts due to a disturbance or the like in the circuit part, thereby obtaining a piezoelectric vibration gyro with less influence of the disturbance, that is, a high accuracy. As a result, it is possible to eliminate the disadvantages of the conventional piezoelectric vibration gyro, and to produce a small and highly accurate piezoelectric vibration gyro with a simple structure that is not affected by the adhesion of the piezoelectric elements and has good mass productivity.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a piezoelectric vibrator used in a piezoelectric vibration gyro according to a first embodiment of the present invention.
2 is a cross-sectional view showing an electrode arrangement and a polarization direction of the piezoelectric vibrator shown in FIG. 1. FIG.
3 is a cross-sectional view showing a vibration direction in an excitation direction (X direction) of the piezoelectric vibrator shown in FIG. 1 and an output of an electrode due to the vibration.
4 is a cross-sectional view showing the direction of vibration (vibration due to Coriolis force) in the detection direction (X direction) of the piezoelectric vibrator shown in FIG. 1 and the output of an electrode due to that vibration. FIG.
5 is a perspective view showing a shape of a circuit board applied to the piezoelectric vibrator shown in FIG. 1 and a connection state between the piezoelectric vibrator and the circuit board in order to produce a piezoelectric vibrating gyroscope according to one embodiment. FIG.
6 is a block diagram showing a drive detection circuit applied to the piezoelectric vibrator shown in FIG. 1 in order to produce a piezoelectric vibration gyro according to one embodiment.
7 is a circuit diagram illustrating a current detection circuit applied to the piezoelectric vibrator shown in FIG. 1 in order to produce a piezoelectric vibration gyro according to an embodiment.
FIG. 8 is a perspective view showing a piezoelectric vibrator used in a conventional piezoelectric vibration gyro.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Piezoelectric vibrator 5, 7, 9, 11, 13, 15 Strip electrode 17 Connection land part 19 Notch part 21 Piezoelectric vibrator attachment land 23 Circuit board 31 1st current detection circuit 32 2nd current detection circuit 33 Differential circuit 34 Synchronous detection circuit 35 Rectifier circuit 36 First drive circuit 37 Second drive circuit 41 Operational amplifier 42 Resistor

Claims (7)

  When a rotational angular velocity is given to a vibrating object (hereinafter, the direction of vibration to be excited is referred to as X direction), Coriolis is in a direction perpendicular to the excitation direction (hereinafter, the direction of vibration is referred to as Y direction). Of a gyroscope that uses a mechanical phenomenon that generates a force, a piezoelectric element that is configured using a vibrator that is configured to be able to excite and detect the X and Y directions orthogonal to each other using piezoelectric characteristics. In the vibration gyro, the vibrator is composed of a tuning fork type piezoelectric element including at least one surface parallel to the X direction or the Y direction, and one surface parallel to either the X direction or the Y direction. The piezoelectric vibrating gyroscope is characterized in that electrodes are provided only on each of the electrodes, and the electrodes are formed as three band-like electrodes for each of the resonance parts of the tuning fork type.   When a rotational angular velocity is given to a vibrating object (hereinafter, the direction of vibration to be excited is referred to as X direction), Coriolis is in a direction perpendicular to the excitation direction (hereinafter, the direction of vibration is referred to as Y direction). Of a gyroscope that uses a mechanical phenomenon that generates a force, a piezoelectric element that is configured using a vibrator that is configured to be able to excite and detect the X and Y directions orthogonal to each other using piezoelectric characteristics. In the vibration gyro, the vibrator is composed of a tuning fork type piezoelectric element including at least one surface parallel to the X direction or the Y direction, and one surface parallel to either the X direction or the Y direction. The electrode is provided only on the base, and the electrode is provided so as to be connected to the connection land portion provided to electrically connect and fix the vibrator to the circuit board on the base portion of the tuning fork type. Is The piezoelectric vibrating gyro, characterized in that there.   2. The piezoelectric vibration gyro according to claim 1, wherein the middle one of the three strip-like electrodes is connected to the vibrator drive circuit as a first drive terminal and a second drive terminal, and the first A piezoelectric vibration gyro, wherein a drive voltage having an opposite phase is applied to the drive terminal and the second drive terminal.   2. The piezoelectric vibration gyro according to claim 1, wherein two detection terminals included in each of the three strip-shaped electrodes are connected to an inverting terminal of an operational amplifier constituting a current detection circuit, respectively, and the potential is a virtual ground of the operational amplifier. It is fixed to the reference potential of the drive detection circuit by the function, and further, the vibrator is driven by applying a voltage between the reference potential and the drive terminal, and the current detection connected to the two detection terminals. A piezoelectric vibration gyro configured to detect vibrations in the X direction and the Y direction using an output of a circuit.   2. The piezoelectric vibration gyro according to claim 1, wherein among the detection terminals included in each of the three strip-shaped electrodes, the detection terminals on the outer side and the detection terminals on the inner side of the vibrator are a base portion of the vibrator. Alternatively, the piezoelectric vibration gyro is used by being connected on a circuit board to be connected.   3. The piezoelectric vibration gyro according to claim 2, wherein the connection land portion is provided on a circuit board and directly performs electrical connection and fixation.   7. The piezoelectric vibration gyro according to claim 6, wherein the circuit board is provided with a notch for securing a vibration part in the vibrator so as not to contact the circuit board. Vibration gyro.

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