JPH10206161A - Angular velocity sensor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize improvement of stability for symmetrical disposition and impact of a piezoelectric element by providing a pair of support members mounted at a vibration node point of a vibrator at a central bending point bent at a predetermined angle on an upper surface of the vibrator. SOLUTION: The angular velocity sensor 1 comprises a vibrator 2 formed in a columnar body, an exciting driving piezoelectric element 3 mounted on a side of the vibrator 2, rotation detecting piezoelectric elements 4A, 4B, and a pair of support members 5A, 5B mounted at a vibration node point of the vibrator 2. For example, the members 5A, 5B formed substantially in an M shape of wire materials such as nickel-plated tungsten wires are embedded at both ends 8, 9 in a mounting base, and welded at a central bending point 10 to the upper surface of the vibrator 2 by spot welding. Since the members 5A, 5B are formed in the M shape, symmetry of the elements 4A, 4B is maintained. Since both the ends 8, 9 are embedded, the sensor 1 has good durability against unexpected impact.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an angular velocity sensor used in a direction detection used in a car navigation system or the like and a camera shake detection of a camera-integrated video tape recorder or the like, and particularly to an angular velocity sensor using a piezoelectric element.

[0002]

2. Description of the Related Art Conventionally, an angular velocity sensor has been used for an aircraft or the like to detect an angular velocity in an inertial coordinate system and calculate a traveling direction of the aircraft or the like. However, in recent years, the angular velocity sensor has been applied as an auxiliary function of a navigation system mounted on a car or to a camera shake detection function of a camera integrated video tape recorder, and the demand for the sensor has been rapidly increasing.

[0003] Such an angular velocity sensor is shown in Figs.
As shown in FIG. 3, a substantially triangular prism-shaped vibrator 100 and three piezoelectric elements 10 disposed on three side surfaces of the vibrator 100 are provided.
1 and a pair of support members 10 for supporting the vibrator 100
2 is provided. In this angular velocity sensor, the three piezoelectric elements 101 have substantially rectangular shapes slightly smaller than the side surface of the vibrator 100, and have substantially the same shape.

On the other hand, a pair of support members 102
It supports the vicinity of the vibration node point 00 in the longitudinal direction. In a conventional angular velocity sensor, as shown in FIG. 6, there is a pair of support members 102 each formed to have a pair of leg portions 102A. In this case, the pair of support members 102 support the vibrator 100 such that the pair of support members 102 abut against a side formed by adjacent side surfaces of the vibrator 100.

[0005] In a conventional angular velocity sensor, as shown in FIG. 7, a pair of support members 102 may be formed in a single bar shape. In this case, the pair of support members 1
Numeral 02 supports the vibrator 100 by welding the respective tips near the vibrating node point of the vibrator 100.

In the conventional angular velocity sensor configured as described above, one of the three piezoelectric elements 101 is used as a driving piezoelectric element 101A for driving the vibrator 100 to drive.
The remaining two are used as the detecting piezoelectric element 101B. That is, in this angular velocity sensor, the support member 102
Element 1 disposed on the side opposite to the side supported by
01 is a driving piezoelectric element 101A, and the other two elements arranged on the other side are detection piezoelectric elements 101B.

Accordingly, when a driving signal is supplied to the driving piezoelectric element 101A, the vibrator 100 changes the point supported by the supporting member 102 in the direction indicated by the arrow S in FIGS. Bending vibration occurs as a point. In this state, when the angular velocity sensor makes a rotational movement about the axis of the vibrator 100, a Coriolis force is generated in a direction orthogonal to the vibration direction of the bending vibration. In this angular velocity sensor, the direction of the bending vibration changes due to the Coriolis force.

The angular velocity sensor can detect the rotational angular velocity by sensing a change in the vibration direction of the bending motion due to the Coriolis force. In this angular velocity sensor, a change in the vibration direction of the bending motion due to the Coriolis force is sensed by taking the difference between the output voltages from the pair of detection piezoelectric elements 101B.

When the angular velocity sensor performs only the bending motion by the driving piezoelectric element 101A, the pair of detecting piezoelectric elements 101B respectively generate the same output voltage.
Therefore, at this time, the pair of detecting piezoelectric elements 101B
Then, when the differential of each output voltage is obtained, it becomes substantially zero.

On the other hand, when the angular velocity sensor causes a change in the vibration direction of the bending motion due to the Coriolis force, the output voltage generated from the pair of detection piezoelectric elements 101B depends on the angle between the vibration direction and the detection piezoelectric element 101B. Change. In this case, the pair of detection piezoelectric elements 101B generate different output voltages because the angles formed by the respective detection piezoelectric elements 101B and the vibration direction are different. Then, in this angular velocity sensor, a change in the vibration direction can be sensed by taking a difference between the output voltages from the pair of detection piezoelectric elements 101B. Thereby, the angular velocity sensor can detect the rotational angular velocity.

[0011]

By the way, in the conventional angular velocity sensor, as shown in FIG.
It is conceivable to use a support member 102 as shown in FIG. However, in such a case, the pair of detecting piezoelectric elements 101B
Are not symmetrical with respect to the vibration node point to which the support member 102 is attached. That is, in the conventional angular velocity sensor, when the vibrator 100 having a substantially quadrangular prism is used, the symmetry of the pair of detection piezoelectric elements 101B is lost, and a signal for vibration cannot be output well.

Thus, in this angular velocity sensor, when the vibrator 100 having a substantially quadrangular prism as shown in FIG. 8 is used, a change in the vibration direction of the bending motion due to the Coriolis force is detected by the pair of piezoelectric elements 101B for detection. It will be difficult. Therefore, the supporting member 10 as shown in FIG.
In the case where the vibrator 2 and the vibrator 100 having a substantially quadrangular prism were used, they could not be used as angular velocity sensors.

On the other hand, in an angular velocity sensor using a substantially quadrangular prism vibrator 100, a pair of detecting piezoelectric elements 1
In order to maintain the symmetry of 01B, it is conceivable to support the vibrator 100 by using a support member 102 as shown in FIG. In this case, the pair of support members 102 are attached so as to be abutted on a surface of the four sides of the vibrator 100 where the piezoelectric element 101 is not provided. In addition, the pair of support members 102 is attached to a portion serving as a vibration node point at a substantially central portion in a width direction in a plane to which the pair of support members 102 are attached.

With such a configuration, the angular velocity sensor is configured such that when a strong impact is applied in the lateral direction, the support member 10
2 causes a motion that bends. This movement is an unnecessary force when the angular velocity sensor detects a change in the vibration direction of the bending movement due to the Coriolis force.
1B.

That is, in the angular velocity sensor using the substantially quadrangular prism vibrator 100, if the support member 102 supports the vibrator 100 in consideration of the symmetry of the pair of detecting piezoelectric elements 101B, unexpected shock or the like may occur. It will be unstable.

As described above, the conventional angular velocity sensor has a problem that it is difficult to achieve both the symmetry of the detecting piezoelectric element 101B with respect to the vibration node point and the stability against unexpected impact.

The present invention has been made in view of the above-mentioned problems, and has as its object to provide an angular velocity sensor in which piezoelectric elements are arranged symmetrically and which has improved stability against impact and the like. I do.

[0018]

An angular velocity sensor according to the present invention which has achieved the above object has a flat upper surface, a vibrator formed in a columnar body, and a vibrator attached to a side surface of the vibrator. A vibrator is vibrated in a predetermined direction, or a piezoelectric element for detecting rotation of the vibrator, and a pair of supports respectively attached to a pair of vibration node points of the vibrator and supporting the vibrator on a base. And a member. The angular velocity sensor is characterized in that a center portion of the support member is bent at a predetermined angle, and a bending point is attached to an upper surface of the vibrator.

In the angular velocity sensor according to the present invention configured as described above, the central portions of the pair of support members attached to the vibration node points are formed so as to be bent. That is, in this angular velocity sensor, both ends of the support member are embedded in a base or the like, and the vibrator is attached to a bent portion substantially at the center thereof so that the vibrator can be hooked.

Thus, in this angular velocity sensor, the piezoelectric element can be disposed symmetrically with respect to the vibration node point. Furthermore, in this angular velocity sensor,
The vibrator is fixed by embedding both ends of the pair of support members. For this reason, this angular velocity sensor has sufficient rigidity against an unexpected impact.

In the angular velocity sensor according to the present invention, the vibrator may be a substantially quadrangular prism. In this angular velocity sensor, the piezoelectric element is attached to each of the three surfaces of the vibrator, and detects rotation of the vibrator with a pair of piezoelectric elements arranged to face each other.
The remaining piezoelectric elements may vibrate the vibrator in a predetermined direction.

In the angular velocity sensor according to the present invention configured as described above, a pair of piezoelectric elements disposed to face each other has symmetry with respect to the vibration node point. Thus, the angular velocity sensor can detect a change in the vibration direction of the bending motion due to the Coriolis force by taking the differential between the pair of piezoelectric elements arranged opposite to each other.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of an angular velocity sensor according to the present invention will be described below in detail with reference to the drawings.

As shown in FIGS. 1, 2 and 3, an angular velocity sensor 1 according to the present embodiment has a vibrator 2 formed in a columnar body, A driving piezoelectric element 3 for exciting the element 2 in a predetermined direction;
A pair of detection piezoelectric elements 4A and 4B attached to the side surface of the vibrator 2 and detecting rotation of the vibrator 2 are provided. Further, the angular velocity sensor 1 includes a pair of support members 5A and 5B attached near a vibration node of the vibrator 2 (hereinafter, referred to as vibration node points) to support the vibrator 2. In the following description, the driving piezoelectric element 3 and the pair of detecting piezoelectric elements 4A and 4B are simply referred to as a “piezoelectric element”.

In the angular velocity sensor 1, the vibrator 2
Is formed in, for example, a substantially quadrangular prism as shown in FIG. The vibrator 2 is made of, for example, a constant elastic material that generally generates mechanical vibration such as an elinvar.
In addition, in this vibrator 2, after processing, 400 to 60
By heating to 0 ° C., the temperature characteristics of the detection sensitivity can be adjusted.

In the angular velocity sensor 1, the vibrator 2
Is configured to have four side surfaces, and three of the four side surfaces are provided with piezoelectric elements. As shown in FIG. 4, these piezoelectric elements include a piezoelectric layer 6 having piezoelectric characteristics, and a pair of electrode layers 7A and 7B formed on both surfaces of the piezoelectric layer 6.
The piezoelectric element has a substantially rectangular shape and is formed to be slightly smaller than the side surface of the vibrator 2.

The piezoelectric layer 6 constituting the piezoelectric element is made of, for example, P
It is formed by processing a piezoelectric ceramic such as ZT, but the material is not limited. The electrode layers 7A and 7B constituting the piezoelectric element are made of a conductor such as gold, and are formed on both surfaces of the piezoelectric layer 6 by a method such as electroless plating.

Then, the piezoelectric element is bonded to the side surface of the vibrator 2 by an adhesive such as epoxy resin through a thermosetting process. In this angular velocity sensor 1, the vibrator 2 is configured such that piezoelectric elements are disposed on both side surfaces and a lower surface in a state where the vibrator 2 is supported by a pair of support members 5A and 5B, which will be described in detail later. These piezoelectric elements use a pair disposed on both side surfaces as detection piezoelectric elements 4A and 4B,
Also, the one disposed on the lower surface is used as the driving piezoelectric element 3.

The angular velocity sensor 1 includes support members 5A and 5B at a pair of vibration node points of the vibrator 2, respectively.
Is attached. These pair of support members 5A, 5
B is configured to be substantially M-shaped overall. That is, the pair of support members 5A and 5B are formed of a wire, and both end portions 8 and 9 are embedded in the mounting base B, and substantially central portions thereof are bent. The pair of support members 5A and 5B support the vibrator 2 by connecting the bending points 10 to the upper surface of the vibrator 2.

At this time, the pair of support members 5A and 5B
It is positioned so that a substantially central portion of the width of the vibrator 2 and the bending point 10 are connected. And a pair of support members 5A, 5A.
B is positioned so that the bending point and the vibration node point are connected. For this reason, in this angular velocity sensor 1,
The pair of support members 5A and 5B support the vibrator 2 in a well-balanced manner.

The supporting members 5A and 5B are made of, for example, a tungsten wire obtained by plating a tungsten wire with nickel.
It is made of a wire, a metal wire, or the like, and is welded to the vibrator 2 by a technique such as so-called spot welding.

As described above, the pair of support members 5A, 5B
Will support the upper surface of the vibrator 2 at two points. Thus, the vibrator 2 is supported in such a manner that it can be hung by the pair of support members 5A and 5B.
Note that these support members 5A and 5B may be fixed to the vibrator 2 using a conductive paste or the like. These support members 5A and 5B may be used as ground terminals in the angular velocity sensor 1.

The angular velocity sensor 1 according to the present invention configured as described above detects the Coriolis force acting on the vibrator 2 when the vibration direction of the bending motion of the vibrator 2 changes.

The driving piezoelectric element 3 is disposed on the surface opposite to the upper surface to which the pair of support members 5A and 5B are attached, that is, on the lower surface. Therefore, when a driving signal is applied, S in FIG. The vibrator 2 is driven in the direction indicated by. In this angular velocity sensor 1, a pair of detecting piezoelectric elements 4 are provided on both side surfaces.
A and 4B are mounted at symmetrical positions with respect to the vibration node point. That is, in this angular velocity sensor 1, a pair of detecting piezoelectric elements 4A and 4B are arranged in parallel to the direction indicated by S in FIG.

In the above-described angular velocity sensor 1, when the driving piezoelectric element 3 is vibrating only in the direction indicated by S in FIG. 1 while a driving signal is applied, the pair of detecting piezoelectric elements 4A and 4B In order to bend similarly, each outputs a similar sine wave. Therefore, when the differential of the output voltage from the pair of detection piezoelectric elements 4A and 4B is obtained, the output voltage becomes substantially zero. That is, the angular velocity sensor 1 can detect the non-rotation by confirming that the differential of the output from the two detecting piezoelectric elements 4A and 4B is zero.

On the other hand, when an external vibration or the like is applied, the angular velocity sensor 1 rotates around the center of the vibrator 2. At this time, Coriolis force is generated in the angular velocity sensor 1 in a direction substantially orthogonal to the vibration direction during non-rotation. Therefore, the vibration direction of the angular velocity sensor 1 is deviated from the vibration direction during non-rotation.

At this time, the pair of detecting piezoelectric elements 4A, 4A
In B, since the vibration direction of the vibrator 2 changes, the respective detecting piezoelectric elements 4A and 4B bend differently. Therefore, each of the detecting piezoelectric elements 4A, 4A
B will output a different sine wave. That is, of the pair of detection piezoelectric elements 4A and 4B,
For example, the output voltage from one becomes higher than the output voltage from the other.

Therefore, in the angular velocity sensor 1, an output signal having a predetermined value can be detected by calculating the differential between the outputs of the pair of detecting piezoelectric elements 4A and 4B. This output signal changes according to the degree of change in the vibration direction of the vibrator 2. Specifically, when the change in the vibration direction of the vibrator 2 is large, a large output signal is obtained. Thus, the angular velocity sensor 1 can measure the change in the vibration direction by measuring the output signal.

As described above, in the angular velocity sensor 1 capable of detecting the Coriolis force, the pair of support members 5A and 5B attached to the vibration node point are substantially M, as described above.
It is formed so as to have a character shape. Therefore, the angular velocity sensor 1 can have a configuration that maintains the symmetry of the pair of detection piezoelectric elements 4A and 4B with respect to the vibration node point.

In this angular velocity sensor 1, both ends 8, 9 of the pair of support members 5A, 5B are embedded in the base. Thus, in the angular velocity sensor 1, the pair of support members 5 can withstand an unexpected impact from the side of the vibrator 2.
A and 5B do not vibrate. Therefore, the angular velocity sensor 1 can accurately detect the Coriolis force because the vibrator 2 has good resistance to an unexpected impact.

On the other hand, the present invention relates to the angular velocity sensor 1 described above.
In the above, the angle is not limited to the angle forming the bending point 10 of the pair of support members 5A and 5B. That is, the pair of support members 5A and 5B may be any members that support the vibrator 2 irrespective of the angle forming the bending point 10.

This bending point 10 has a large contact area with the upper surface of the vibrator 2 when the angle formed is large,
If the angle formed is small, it comes into contact with the upper surface of the vibrator 2 with a small area. Therefore, in the angular velocity sensor 1, when defining the angle forming the bending point 10, it is necessary to consider the weight of the vibrator 1 and the piezoelectric element, the magnitude of the vibration applied to the vibrator 2, and the like.

Specifically, in this angular velocity sensor 1,
In order to increase the angle forming the bending point 10, the ends 8, 9 of the pair of support members 5A, 5B may be embedded further apart. Alternatively, by making the distance between both ends 8, 9 of the pair of support members 5A, 5B equal and lowering the upper part, the angle forming the bending point 10 can be increased.

The present invention is not limited to the angular velocity sensor 1 shown in the above embodiment, but may be an angular velocity sensor 11 as shown in FIG. In the angular velocity sensor 11, the same members as those of the angular velocity sensor 1 described above are denoted by the same reference numerals, and detailed description thereof will be omitted.

The angular velocity sensor 11 is configured such that the upper portions of a pair of support members 12A and 12B that support the vibrator 2 are substantially parallel to a base or the like. Also in this case, the angular velocity sensor 11 maintains the symmetry of the pair of detecting piezoelectric elements 4A and 4B, and has good resistance to an unexpected impact from the side surface of the vibrator 2.

Further, in this angular velocity sensor 11, FIG.
As shown by the middle broken line, the outer dimensions of the pair of support members 12A and 12B do not change even when the angle forming the bending point 10 is set to various values. Therefore, the angular velocity sensor 11 can maintain its shape without increasing its size even in consideration of the weight of the vibrator 2 and the piezoelectric element, the magnitude of vibration applied to the vibrator 2, and the like.

[0047]

As described above in detail, in the angular velocity sensor according to the present invention, a bending point having a substantially central portion bent at a predetermined angle is attached to the vibration node point of the vibrator. Thus, the pair of support members support the vibrator. Therefore, this angular velocity sensor can maintain the symmetry of the pair of detection piezoelectric elements on the side surface of the vibrator. The angular velocity sensor is connected to the vibrator at substantially the center of the pair of support members, and supports the vibrator with both ends of the pair of support members securely fixed to the base. For this reason, this angular velocity sensor can maintain the symmetry of the piezoelectric element, and is resistant to an unexpected impact or the like, and has improved stability.

[Brief description of the drawings]

FIG. 1 is a perspective view of a main part of an angular velocity sensor according to the present invention.

FIG. 2 is a side view of a main part of the angular velocity sensor according to the present invention.

FIG. 3 is a top view of a main part of the angular velocity sensor according to the present invention.

FIG. 4 is a sectional view of a main part of the angular velocity sensor according to the present invention.

FIG. 5 is a sectional view of a main part of another angular velocity sensor according to the present invention.

FIG. 6 is a perspective view of a main part of a conventional angular velocity sensor.

FIG. 7 is a perspective view of a main part of a conventional angular velocity sensor.

FIG. 8 is a perspective view of a main part of a conventional angular velocity sensor.

[Explanation of symbols]

1 angular velocity sensor, 2 vibrator, 3 driving piezoelectric element,
4. Piezoelectric element for detection, 5 support members

Claims (4)

[Claims] 1. A vibrator formed in a columnar shape and having a flat upper surface, attached to a side surface of the vibrator, vibrating the vibrator in a predetermined direction, and detecting rotation of the vibrator. A piezoelectric element, and a pair of support members respectively attached to a pair of vibration node points of the vibrator and supporting the vibrator on a base, the support member having a central portion bent at a predetermined angle. An angular velocity sensor which is bent and has a bending point attached to an upper surface of the vibrator. 2. The angular velocity sensor according to claim 1, wherein said support member is formed by plating a tungsten wire with nickel. 3. The angular velocity sensor according to claim 1, wherein the vibrator has a substantially rectangular cross section. 4. The piezoelectric element is attached to each of three surfaces of the vibrator, and the rotation of the vibrator is detected by a pair of opposing piezoelectric elements and the vibrator is detected by the remaining piezoelectric elements 4. The angular velocity sensor according to claim 3, wherein the sensor is vibrated in a predetermined direction.