JP2000258167A - Oscillator for piezoelectric oscillators and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To avoid the characteristic variation with a simple structure by omitting the adhesion process with adhesives and leads at inputs/outputs. SOLUTION: Piezoelectric bodies using two mutually reversely polarized plate-like crystals of the same shape are pressed and heated into a board bonded at an approximately atomic level. The board is etched or sand-blasted or otherwise to form a columnar oscillator 10, supports 31-34 and a support frame 40 in one body like a plate having two planes. Connections of conductive lines 71, 72, 73 from band-like electrodes 61, 62, 63 of the oscillator 10 located in a central space of the support frame 40 to electrodes 21, 22, 23 of the frame 40 use respectively individual both planes of the support 31 and one surface of the respective support 33, and the electrodes are respectively formed by etching in a unified specified pattern.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrator for a piezoelectric vibrating gyroscope and a method for manufacturing the same, and more particularly to a method for manufacturing a vibrating gyroscope used in an automobile navigation system or a camera shake correcting device of a camera-integrated VTR. The present invention relates to a vibrator for a piezoelectric vibrating gyroscope that can be avoided and that is simple in structure and manufacture.

[0002]

2. Description of the Related Art A piezoelectric vibrating gyroscope is known as 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 vibration direction.

In general, in a composite vibration system configured to be able to excite vibrations in two different directions orthogonal to each other, when the vibrator is rotated while one of the vibrations is excited, the vibrator is vibrated by the action of the aforementioned Coriolis force. A force acts in a direction perpendicular to the other, and the other vibration is excited. Since the magnitude of this vibration is proportional to the amplitude of the input vibration and the rotational angular velocity, when the vibration amplitude on the input side is constant, the magnitude of the applied rotational angular velocity can be obtained from the magnitude of the output voltage. .

Conventionally, in a piezoelectric vibrating gyroscope of this type, as shown in the basic structure of a vibrating body 100 in FIG. The piezoelectric ceramic thin plates 111 and 112 are respectively joined. Electrodes are formed on the surfaces of these piezoelectric ceramic thin plates 111 and 112, and are polarized in the thickness direction.

It is known that a metal prism 110 having a square cross section has two bending vibration modes orthogonal to each other, and that the resonance frequencies of the two bending vibration modes become substantially equal when the characteristics of the material are uniform. ing. Therefore, when a voltage having a frequency substantially equal to the resonance frequency of the bending vibration mode of the metal prism 110 is applied to the piezoelectric ceramic thin plate 111, the surface of the metal prism 110 to which the piezoelectric ceramic thin plate 111 is joined becomes unevenly vibrating. If the direction perpendicular to this plane is the X direction, the bending vibration of the metal prism 110 is X
Direction.

In this state, when the metal prism 110 is rotated around the central axis in the length direction (this direction is defined as the Z direction), the metal prism 110 is moved in the X direction by the action of Coriolis force. Vibrates flexibly in the right-angled Y direction. This Y
The piezoelectric ceramic thin plate 112 is bonded to the uneven surface perpendicular to the direction, and a voltage is generated in the piezoelectric ceramic thin plate 112 by the piezoelectric effect based on the unevenness. The magnitude of this voltage is proportional to the magnitude of the vibration excited by the piezoelectric ceramic thin plate 111 and the magnitude of the applied rotational angular velocity. Therefore, if the magnitude of the excitation voltage applied to the piezoelectric ceramic thin plate 111 is fixed, the voltage generated in the piezoelectric ceramic thin plate 112 has a value proportional to the rotational angular velocity of the metal prism 110.

A lead wire 121 is connected to the piezoelectric ceramic thin plate 111 for applying a voltage.
A lead wire 122 for extracting a generated voltage is connected to the piezoelectric ceramic thin plate 112.

[0008]

In the above-mentioned conventional vibrator for a piezoelectric vibrating gyroscope, a thin plate made of a piezoelectric material is bonded to a metal prism in order to excite in a bending vibration mode. There is a problem that the characteristics vary and it is difficult to reduce the cost of the bonding process.

When supporting a conventional columnar vibrator,
Since it is necessary to connect and support a thin metal wire by spot welding or the like at a node position of vibration generated at the time of resonance in bending vibration of the columnar vibrator, there is a problem that it is weak against externally applied vibration or impact.

Further, in the above-described vibrator for a piezoelectric vibrating gyroscope, it is necessary to connect each of the drive circuit and the detection circuit to the electrode of the columnar vibrator by a lead wire. In addition, there is a problem that it is difficult to suppress a characteristic variation due to a variation in a connection state of a lead wire.

An object of the present invention is to eliminate the above-mentioned problems, eliminate the use of a lead wire in the bonding step and input / output with an adhesive, and provide a piezoelectric vibrating gyroscope vibrator and a piezoelectric vibrating gyroscope that can avoid characteristic fluctuations with a simple structure. It is an object of the present invention to provide a manufacturing method thereof.

[0012]

According to the present invention, there is provided a vibrator for a piezoelectric vibrating gyroscope according to the present invention, comprising: a columnar vibrator for forming a quadrangular prism by joining two identical plate-like piezoelectric bodies having polarization directions opposite to each other; A driving band-shaped electrode joined to one main plane parallel to the joining surface of the columnar vibrating body and extending in the longitudinal direction of the columnar vibrating body and connected to a driving electrode of a signal extraction port; The two main surfaces which are joined to the other main plane parallel to the joint surface of the body, are arranged symmetrically and parallel to the center line in the longitudinal direction of the columnar vibrator, and are connected to the detection electrode of the signal extraction port. It is preferable that the piezoelectric body is a quartz plate.

With such a configuration, since the vibrating body is a columnar vibrating body forming a square pole, it is easy to form an integral structure with a support frame having the same thickness and having the columnar vibrating body positioned at the center. is there. In particular, by pressing and heating two quartz plates, it becomes possible to join them at an atomic level.

One of the concrete supporting means of the columnar vibrator is directed outward at each of two node positions of the one-wavelength resonance mode vibration generated by bending vibration on each of the side planes of the columnar vibrator. A total of four support portions formed and having the same plane as the main plane of the columnar vibrator, and the columnar vibrator is arranged and fixed in a central space by these supports, and is coplanar with the main plane of the columnar vibrator. A drive electrode joined to the support frame at a root portion of one of the support portions on the same plane as the drive strip electrode, and the same as the detection strip electrode, respectively. A detection electrode which is on a plane and is joined to the support frame at a root portion of the support portion at a point symmetrical position, the drive band electrode is a drive electrode, and the detection band electrode is a detection electrode, and the detection band electrode is on the same plane of the support portion. In joined and a conductive path connecting.

Therefore, the columnar vibrator, the support portion and the support frame are integrally formed, and the driving band electrode,
The drive electrodes and the conductive paths connecting them, and the two sets of the detection strip electrodes, the detection electrodes, and the conductive paths connecting them can also be integrally formed on a predetermined surface.

According to this structure, the plate-shaped support portion supports the columnar vibrator on the support frame, and each has a common plane. Therefore, the band-shaped electrode of the columnar vibrator is formed by the band-shaped conductive paths on different surfaces of the support portion. And the extraction electrode on the support frame can be connected.

Further, the method for manufacturing a vibrator for a piezoelectric vibrating gyroscope according to the present invention comprises the steps of joining two identical plate-shaped piezoelectric bodies having opposite polarization directions to each other to form a single substrate; Forming a plan view of the columnar vibrator, the support portion and the support frame on one surface of the substrate with a resist,
A step of molding the columnar vibrating body, the support portion and the support frame by etching using a hydrofluoric acid-based etchant or a step of molding by sandblasting with SiC fine powder, a step of removing the resist, and then parallel to the bonding surface. Forming a drive electrode and a detection electrode by forming a conductive pattern for electrodes on both surfaces by etching, and the piezoelectric body is preferably a quartz plate.

Therefore, a vibrator for a piezoelectric vibrating gyroscope can be manufactured through such simple steps.

[0019]

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1A is a perspective view showing one embodiment of the present invention, and FIG.
It is A sectional drawing.

In the vibrator for a piezoelectric vibrating gyroscope shown in FIG. 1, a quadrangular columnar vibrating body 10 is formed by a support frame 40 having a rectangular cross section by four plate-shaped support portions 31 to 34.
It is arranged almost in the center. In this embodiment, a quartz body often used for a timepiece is used as a piezoelectric body used for the columnar vibrator 10. The columnar vibrator 10, the support portions 31 to 34, and the support frame 40, which will be described later with reference to FIG. 2, are formed by joining two quartz plates whose polarization directions are opposite to each other. is there.

The columnar vibrating body 10 is formed by joining two identically shaped crystalline lenses 11 and 12 whose polarization directions are opposite to each other to form a quadrangular prism. The support portions 31 to 34 are integrally formed with the columnar vibrating body 10 and the support frame 40 at a node position of the vibrating body of the columnar vibration 10. The support frame 40 is also formed by joining two identical crystalline lenses 41 and 42. Therefore, the columnar vibrating body 10 and the support portions 31 to 3
The two planes parallel to the entire joint surface of the piezoelectric vibrating gyroscope vibrator 4 and the support frame 40 respectively form the same plane.

In the electrode wiring of the vibrator for a piezoelectric vibrating gyroscope shown in FIG. 1, a pattern is formed on a quartz plate by etching. That is, the driving electrode 21 coupled on the surface of the support frame 40 is connected to the driving strip electrode 61 coupled on the surface of the columnar vibrator 10 and the conductive path 71 on the surface of the supporting portion 31 on one plane. Have been. In the other plane, the detection electrode 22 coupled on the surface of the support frame 40 is
The detection electrode 23 coupled to the surface of the support frame 40 is further coupled to the surface of the columnar vibrating body 10 by the detection strip electrode 62 coupled to the surface of the column 0 and the conductive path 72 on the surface of the support portion 31. The detection strip electrodes 63 and the conductive paths 73 on the surface of the support portion 33 are separately connected on a plane. Each of the drive electrode 21 and the detection electrodes 22 and 23 is connected to a connection terminal of the harmful circuit as a lead electrode.

The detection electrodes 22 and 23 are symmetrical about a point on a substantially diagonal line of the support frame 40, and the detection strip electrodes 62 and 63 are on the same surface of the on-column vibrator 10 in the longitudinal direction of the columnar vibrator 10. They are arranged symmetrically and parallel to the center line.

As described above, each of the drive electrode 21 and the detection electrodes 22 and 23 serving as extraction electrodes from the piezoelectric vibrating gyro vibrator to the external circuit is in a state of sticking on the main plane of the support frame 40. A connection form in which the input / output terminal is directly connected to the input / output terminal in the form of a connector can be employed.

In the above description, the columnar vibrator 10 and the support 3
1 to 34 and the support frame 40 have been described as being molded from a structure in which two quartz plates having polarization directions opposite to each other are joined, which will be described later with reference to FIG. The piezoelectric vibrating gyroscope vibrator may be formed by molding the support, the support portion, and the support frame individually and joining them by welding, for example. In this case, the manufacturing process becomes complicated, and an increase in cost cannot be avoided.

Next, a manufacturing process for the vibrator for a piezoelectric vibrating gyroscope according to the present invention will be described with reference to FIGS.

As a material of the piezoelectric body, quartz which is widely used in a vibrator for a timepiece is used. First, in the first step, two quartz plates 91 and 92 having opposite polarization directions are joined (step S1). The joining is performed by a method in which the joining surface is polished flat and pressurized and heated in a clean state. This method not only avoids the use of organic adhesives, but also allows bonding at an atomic level.

In the next step, the columnar vibrator 10, the support portions 31 to 34,
Then, a plan view pattern 93 of the support frame 40 is formed of a photoresist (Step S2).

FIG. 2A is a completed perspective view of the step S2.

In the next step, etching is performed using a hydrofluoric acid-based etchant by photolithography, and the columnar vibrator 10, the support portions 31 to 34, and the support frame 40 are integrally formed (step S3). ), And the vibrator body 90 is completed. The production by this integral molding is SiC
For example, a method of removing unnecessary portions by sand blasting using fine abrasive grains such as the above may be used.

FIG. 2B is a completed perspective view of the step S3.

In the next step, electrodes are formed on the surface of the quartz plate 91 parallel to the joining surfaces of the quartz plates 91 and 92, and predetermined patterns of the drive electrodes 21, the drive strip electrodes 61 and the conductive paths 71 are obtained by etching. Can be Further, electrodes are formed on the surface of the other quartz plate 92, and predetermined patterns of the detection electrodes 22, 23, the detection strip electrodes 62, 63, and the conductive paths 72, 73 are obtained by etching. The child is completed (step S4).

FIG. 2C is a completed perspective view of the step S4.

Next, FIG. 3 is a diagram illustrating the characteristics of a prototyped vibrator for a piezoelectric vibrating gyroscope. The dimensions of the quadrangular prism portion of the columnar vibrator in the prototype piezoelectric vibrating gyroscope vibrator are “16 mm × 2 mm × 2 mm”. In addition, the resonance frequency in the bending mode of one-wavelength resonance is “48.
5 KHz "and" 48.7 KHz ", which have been confirmed to be practical levels.

Next, an external circuit connected to the vibrator for a piezoelectric vibrating gyroscope will be described with reference to FIG. 4 and FIG.

The detection electrodes 22 and 23 in FIG. 1 are connected to the current detection circuits 81 and 82 via detection electrode terminals. Functionally, the current detection circuits 81 and 82 have substantially zero input impedance, exhibit a ground potential, and can obtain an output voltage proportional to the input current. The output side of each of the current detection circuits 81 and 82 is connected to the synchronous detection circuit 85 via the differential amplifiers 83 and 84, respectively, and outputs the sensor output of the piezoelectric vibrating gyroscope from the synchronous detection circuit 85.

Although not shown in FIG. 4, an AC power supply is connected to the drive electrode 21 of FIG. 1 via a drive electrode terminal, and the columnar vibrator excites bending vibration by the AC power supply.

[0039]

As described above, according to the present invention, the vibrator for a piezoelectric vibrating gyro is configured to pressurize and heat a piezoelectric body using two identical quartz plates whose polarization directions are opposite to each other. Since bonding can be performed at substantially the atomic level as one substrate, not only the bonding step of the piezoelectric body can be omitted, but also variation in gyro characteristics due to variation in the bonding state can be avoided.

Further, since the columnar vibrator, the supporting portion and the supporting frame are integrally formed by etching or sandblasting, the structure as the vibrator for the piezoelectric vibrating gyroscope is simple, and the vibrating body is supported on the supporting frame. Is stable.

Also, since the conductive paths of the drive electrode and the detection electrode can be formed on the plane of the substrate, the conductive path is used to connect the vibrator located in the central space of the support frame to the support frame. Since the part surface can be used, an effect of being strong against external vibration or impact can be obtained.

Also, since the drive electrode and the detection electrode, which are the extraction electrodes to the external circuit, are joined on the plane of the support frame, it is necessary to use a lead wire to connect these extraction electrodes to the electrode terminals of the external circuit. Therefore, it is possible to obtain an effect that it is possible to avoid an adverse effect on resonance due to the lead wire or a change in characteristics.

[Brief description of the drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention and FIG.
It is A sectional drawing.

FIG. 2 is a perspective view showing one embodiment of the outline of the manufacturing process of FIG.

FIG. 3 is a characteristic diagram based on one embodiment of the present invention.

FIG. 4 is a block diagram showing one embodiment of an external circuit according to the present invention.

FIG. 5 is a perspective view showing an example of a conventional columnar vibrator.

[Explanation of symbols]

 Reference Signs List 10 columnar vibrator 11, 12, 41, 42 crystalline lens 21 drive electrode 22, 23 detection electrode 31, 32, 33, 34 support part 40 support frame 61 drive band electrode 62, 63 detection band electrode 71, 72, 73 conductive path 81 , 82 Current detection circuit 83, 84 Differential amplification circuit 85 Detection circuit 90 Transducer 91, 92 Quartz plate 93 Photoresist

Claims (7)

[Claims] 1. A columnar vibrator for forming a quadrangular prism by joining two identical plate-shaped piezoelectric bodies having opposite polarization directions to each other, and one principal plane parallel to a joint surface of the columnar vibrator. A driving strip electrode extending in the longitudinal direction of the columnar vibrating body and connected to a driving electrode of a signal extraction port, and bonding to the other main plane parallel to a bonding surface of the columnar vibrating body. For a piezoelectric vibrating gyroscope, comprising: two detection band electrodes arranged symmetrically and parallel to a center line in the longitudinal direction of the columnar vibrator and connected to a detection electrode of a signal extraction port. Vibrator. 2. The vibrator for a piezoelectric vibrating gyroscope according to claim 1, wherein said piezoelectric body is a quartz plate. 3. The main plane of the columnar vibrator according to claim 1, wherein each of the side planes of the columnar vibrator is outwardly formed at each of two node positions of the vibration in the one-wavelength resonance mode caused by bending vibration. A total of four support portions having the same plane as the above, a support frame having the columnar vibrator disposed and fixed in a central space by these support portions, and having the same plane as the main plane of the columnar vibrator; A drive electrode joined to the support frame at a base portion of one of the support portions on the same plane as the support portion; and a support electrode at the base portion of the support portion on the same plane as each of the detection strip electrodes and at a point symmetrical position. It has a detection electrode joined to a frame, and a conductive path joined to and connected to the driving strip electrode and the detection electrode on the same plane of the support portion, respectively. Vibrator for piezoelectric vibrating gyroscope. 4. The column-shaped vibrating body, the supporting portion and the supporting frame are formed integrally with each other, and the driving band-shaped electrode, the driving electrode and a conductive path connecting them, and two sets of the detection device according to claim 3. A vibrator for a piezoelectric vibrating gyroscope, wherein each of the band-shaped electrode, the detection electrode, and a conductive path connecting the detection electrode and the detection electrode are integrally formed on a predetermined surface. 5. A step of joining two identical plate-shaped piezoelectric bodies having opposite polarization directions to each other to form one substrate;
4. A step of forming a plan view of the columnar vibrator, the support, and the support frame according to claim 3 on one surface of the substrate by using a resist, and etching the columnar vibrator, the support using a hydrofluoric acid-based etchant. And a step of molding a support frame, a step of removing the resist, and a step of forming a drive electrode and a detection electrode by forming a conductive pattern for an electrode on both surfaces parallel to the bonding surface by etching. A method for manufacturing a vibrator for a piezoelectric vibrating gyroscope, comprising: 6. A step of joining two identical plate-shaped piezoelectric bodies having opposite polarization directions to each other to form a single substrate;
4. The columnar vibrator according to claim 3 on one surface of the substrate;
4. A step of forming a plan view of a support portion and a support frame with a resist, a step of forming the columnar vibrator, the support portion, and the support frame according to claim 3 by sandblasting with SiC fine powder, and then forming the resist. Manufacturing a vibrator for a piezoelectric vibrating gyroscope, comprising the steps of: removing a substrate; and then forming a drive electrode and a detection electrode by forming a conductive pattern for an electrode on both surfaces parallel to the bonding surface by etching. Method. 7. The method for manufacturing a vibrator for a piezoelectric vibrating gyroscope according to claim 5, wherein the piezoelectric body is a quartz plate.