JPH0868634A - Piezoelectric vibration angular speedometer and its manufacture - Google Patents

Abstract

PURPOSE: To mass-produce and miniaturize a vibrator by a method wherein piezoelectric or electrostrictive ceramic plates in which electrode patterns have been formed on both faces and whose size is identical and a plate which is composed of a metal or a ceramic are bonded and this assembly is cut by a precision cutter. CONSTITUTION: A rectangular parallelepiped composed of a piezoelectric member 1 in which electrodes have been formed on two opposite side faces and a piezoelectric member 2 which is composed of a quartz glass are bonded to a quartz glass member in such a way that the electrode to be used as an internal electrode becomes a bonding face. The electrode which is situated on the surface of a vibrator of the piezoelectric member 1 is divided into three parts so as to be symmetric with respect to the central axis of the vibrator, an electrode 3 in the center is used for driving, and electrodes 4 on both sides are used for detection. The internal electrode to be used as a ground is used as a whole-face electrode which is not divided, and the piezoelectric members are polarization-treated in the direction of the electrodes. A cross section which is perpendicular to the vibration-axis direction of the vibrator is cut to be nearly a square so that a resonance frequency in a driving direction is matched to that in a Coriolis force direction.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibrating angular velocity meter, and more particularly to a piezoelectric vibrating angular velocity meter that is small and can be mass-produced at low cost.

[0002]

2. Description of the Related Art Conventionally, two main types of vibration angular velocimeters are GE type and Watson type piezoelectric vibrating angular velocimeters which utilize positive and negative piezoelectric effects. In both types, when natural vibration is excited in the vibrator and rotation occurs around the vibrator axis, Coriolis force is generated in a direction perpendicular to both directions. This force is expressed by the following equation. Fc = 2 m [V · Ω] (1) where Fc is the Coriolis force, m is the mass of the vibrator, v is the vibration speed of the vibrator, and Ω is the rotational angular velocity.

In the GE type piezoelectric vibrating angular velocity meter, as shown in FIG. 5, a piezoelectric ceramic plate (12) is adhered to a rod-shaped vibrator (11) made of metal so that the metal vibrator is driven and the vibrator is vibrated. The Coriolis force generated in the direction perpendicular to the driving direction due to the rotation of is detected. The mode of vibration used is unrestrained lateral vibration, which is usually fixed to the substrate at the node of vibration. In the Watson type piezoelectric vibrating angular velocity meter, as shown in FIG. 6, four piezoelectric ceramic bimorphs (13, 14) are formed in a stacked tuning fork shape so that two piezoelectric ceramic bimorphs are orthogonal to each other, and the driving bimorph excites the entire tuning fork. The Coriolis force generated with the rotation of the element is detected by the detection bimorph.

A GE which has a particularly simple structure and is suitable for downsizing
As the piezoelectric vibrating angular velocity meter of the type, recently, one using a triangular prism-shaped metal vibrator, one using a cylindrical piezoelectric ceramics as a vibrator, and the like have been developed. When using a metal oscillator, a piezoelectric ceramic plate is bonded to the oscillator. When a piezoelectric ceramic vibrator is used, electrodes are formed on the side surfaces of the cylinder, and then polarization processing is performed.

[0005]

However, these vibration angular velocimeters have problems in inexpensively manufacturing the vibrator and miniaturizing the vibrator. That is, when the process of joining the piezoelectric ceramic plate to the metal vibrator is included,
Since it becomes necessary to bond the piezoelectric ceramic plate to the side surface of each vibrator, a great amount of time is required for this process, which is an obstacle to mass production. Further, in this process, the smaller the size of the vibrator, the worse the workability. Also,
Even when forming electrodes on the side surface of a cylindrical piezoelectric ceramic, it is necessary to form electrodes on each vibrator using a roll type printing machine, etc., and then individually perform polarization processing. Not suitable for conversion.

The object of the present invention is to solve these problems.

[0007]

The present invention focuses on the fact that if a two-dimensionally structured electrode is formed on a ceramic plate made of a piezoelectric or electrostrictive material, a large number of small vibrators can be manufactured at one time. A vibrator comprising a quadrangular prism-shaped base body made of metal or ceramics and a quadrangular prism-shaped piezoelectric or electrostrictive member joined to the base body; and an internal electrode formed between the base body and the piezoelectric or electrostrictive member. The present invention has provided a piezoelectric vibrating gyro composed of only one vibrator having a unimorph structure having an internal electrode of a piezoelectric or electrostrictive member and an external electrode formed on a side surface facing the internal electrode.

In the present invention, ceramics means glass, polycrystalline sintered bodies, synthetic single crystals and the like.

[0009]

[Function] A piezoelectric or electrostrictive ceramics plate of the same size with electrode patterns formed on both surfaces and a plate made of metal or ceramics are joined and then cut to produce a large amount of unimorph type vibrators at one time. can do. Further, by forming an electrode pattern by lithography and cutting the bonding plate by a precision cutting machine, an extremely small unimorph type vibrator can be manufactured with good reproducibility.

The internal electrode of the piezoelectric and electrostrictive member is used as a ground, and a voltage is applied between this and the driving electrode in the center of the three-divided external electrode to utilize the so-called piezoelectric lateral effect to utilize the unimorph effect. Excites unconstrained fundamental vibration in the oscillator. Therefore, vibration occurs in a direction perpendicular to the electrode surface, and when rotation occurs around the axis of the vibrator, the vibrator bends in the electrode surface due to Coriolis force. The bending due to this Coriolis force is detected by using two detection electrodes at both ends of the external electrode divided into three parts.

At this time, a piezoelectric signal associated with the driving of the vibrator is also generated in the Coriolis force detecting electrode, so that the actual signal is a combination of the signal resulting from the Coriolis force and the signal resulting from the driving of the vibrator. . However, the signals generated at the two detection electrodes have the same frequency and opposite phases with respect to the Coriolis force, and the ones caused by the drive have the same phase. Only signals due to force can be obtained.

[0012]

Example 1 The present invention will be described in more detail with reference to the following examples. FIG. 1 is a basic configuration of an example of a vibration angular velocity meter based on the present invention. The rectangular parallelepiped (1) made of a piezoelectric material and the rectangular parallelepiped (2) made of quartz glass having electrodes formed on two opposite side surfaces are joined to a quartz glass member so that the electrodes serving as internal electrodes serve as joint surfaces. In the piezoelectric member (1), the electrode on the upper surface of the vibrator is divided into three symmetrically with respect to the central axis of the vibrator. The central electrode (3) is used for driving, and the electrodes (4) on both sides are used for detection. The internal electrode serving as the ground is a full-surface electrode without division. The piezoelectric member is polarized in the electrode direction. The cross section of the oscillator perpendicular to the oscillator axis direction is substantially square in order to match the resonance frequencies in the driving direction and the Coriolis force direction.

FIG. 2 shows the operating principle of the piezoelectric vibration angular velocity meter shown in FIG. The oscillator vibrates under unrestrained conditions, and the center and end of the oscillator have velocities in opposite directions with the node (5) of the vibration as the boundary (2-1). At this time, when rotation occurs around the oscillator axis, the speed directions are opposite,
Coriolis force is generated in the opposite direction with the contact point of vibration as the boundary (2
-2). This force causes the vibrator to bend in the direction of the electrode surface (2-3). A piezoelectric signal caused by driving vibration (2-1) and a piezoelectric signal caused by deformation (2-3) due to Coriolis force are simultaneously generated on the two outer detection electrodes. Among these, the piezoelectric signals due to the Coriolis force have almost opposite phases between the two electrodes. This is because, for example, in the deformed state shown in FIGS.
This is because tensile stress acts on the side, and the signs of the stress are always different between the two electrodes. On the other hand, since the piezoelectric signals due to driving are almost the same between both electrodes, if differential signals are taken from both electrodes, it is possible to obtain almost only the piezoelectric signals due to the Coriolis force. Since the resonator cross section is square and the resonance frequencies in the Coriolis force direction and the drive direction are matched,
If the output from the detection electrode is fed back, the oscillator can be driven in the vicinity of the resonance frequency by a simple oscillation circuit. Therefore, the vibration due to the Coriolis force also enters the resonance state, and the detection sensitivity is improved.

By the way, the resonator does not necessarily have to match the resonance frequency in the drive direction and the resonance frequency in the Coriolis force direction. Resonance can be used. For this purpose, the oscillator may be unimorph-driven at the resonance frequency in the Coriolis force direction. If such a vibrator is used, the resonance matching step can be omitted.

FIG. 3 shows an example of a vibrator supporting method for realizing the unconstrained vibration condition of the vibrator shown in FIG. It is fixed to the support base (6) using a silicone adhesive at the portion corresponding to the node of vibration. Further, as a simple fixing method, it is possible to embed the entire vibrator in an adhesive having a relatively low elastic constant. FIG. 4 shows an example of a manufacturing process of the piezoelectric vibration angular velocity meter shown in FIG. A silver electrode (7) is formed on both sides, and a plate (8) made of a piezoelectric material, which has been polarized in the electrode direction, is bonded to a quartz glass plate (9) having the same shape with an epoxy adhesive (4- 1).
In order to maintain high alignment accuracy in the post process, the shape of the periphery of the bonding plate is adjusted with a dicing saw (4-2). A photoresist film (10) is placed on the surface of one of the electrodes, and a resist pattern corresponding to the electrode pattern of equal width and equal spacing is formed by an exposure device (4-3). Using this resist as a protective mask, the silver electrode exposed by reactive ion etching is removed (4-4). After that, the resist is peeled off (4-5), and every other rod-shaped silver electrode left by a dicing saw is cut at the central part, so that the driving electrode is centered symmetrically with respect to the oscillator central axis. However, a vibrator having detection electrodes formed on both sides is prepared (4-6). According to such a process, a large number of small unimorph type piezoelectric vibration angular velocity meters can be manufactured from a set of piezoelectric plate / quartz glass plate bonded body.

Even if a metal plate is used as a member for forming a unimorph instead of using ceramics such as quartz glass, a small and inexpensive piezoelectric vibrating gyro can be similarly manufactured. At this time, the metal member can be used as a part of the electrode and the lead.

[0017]

As described above, according to the present invention, it is possible to provide a large-scale, inexpensive and small vibration angular velocity meter.

[Brief description of drawings]

FIG. 1 is an example of a piezoelectric vibrating angular velocity meter according to the present invention.

FIG. 2 illustrates the operation of the piezoelectric vibration angular velocity meter of FIG. 2-1 is a diagram for showing vibration due to driving from the side face, and 2-1 and 2-2 are diagrams for showing Coriolis force from the electrode face and deformation accompanying it.

FIG. 3 is an example of a method of fixing the vibrator shown in FIG.

FIG. 4 is an example of a method of manufacturing the piezoelectric vibration angular velocity meter shown in FIG.

FIG. 5 is a conceptual diagram of a conventional piezoelectric vibration angular velocity meter.

FIG. 6 is a conceptual diagram of a conventional piezoelectric vibration angular velocity meter.

[Explanation of symbols]

 1 Detection Piezoelectric Member 2 Driving Piezoelectric Member 3 Driving Electrode 4 Detection Electrode 5 Vibration Node 6 Support 7 Silver Electrode 8 Piezoelectric Member Plate 9 Quartz Glass Plate 10 Photoresist 11 Metal Oscillator 12 Piezoelectric Ceramics Plate 13 Driving Piezoelectric bimorph 14 Piezoelectric bimorph for detection

Claims (3)

[Claims] 1. A vibrator formed of a quadrangular prism-shaped base body made of metal or ceramics and a quadrangular prism-shaped piezoelectric or electrostrictive member bonded to the base body, and a vibrator formed between the base body and the piezoelectric or electrostrictive member. A piezoelectric vibrating angular velocity meter having an internal electrode and an external electrode formed on a side surface of the piezoelectric or electrostrictive member facing the internal electrode, wherein the oscillator is excited and generated by the external electrode and the internal electrode. A piezoelectric vibrating angular velocity meter characterized by detecting Coriolis force. 2. The piezoelectric vibrating angular velocity meter according to claim 1, wherein the external electrode is divided into three in the axial direction of the vibrator.
A piezoelectric vibrating gyro characterized by a drive electrode in the center and detection electrodes on both sides. 3. A pattern of internal electrodes is formed on one surface,
A plate-shaped member made of a piezoelectric or electrostrictive material having a pattern of an external electrode formed on the surface opposite to this, and a plate-shaped member made of a metal or ceramics are joined at the surface on which the internal electrode is formed, and then cut. A method of manufacturing a plurality of piezoelectric vibrating angular velocimeters, comprising: