JPH0510766A - Piezoelectric element - Google Patents

Abstract

PURPOSE:To provide a piezoelectric element which is used to manufacture a sensor whose characteristic is seldom dispersed even with changes in ambient temperature. CONSTITUTION:Piezoelectric elements 14a, 14b, 14c are formed on the side face of a vibration body 12 in the form of an equilateral triangle pole. The piezoelectric elements 14a, 14b, 14c include piezoelectric bodies 16a, 16b, 16c, respectively. A pair of network mesh electrodes 18a, 20a, 18b, 20b and 18c, 20c are formed on both of the main faces of each piezoelectric body 16a, 16b, 16c. The mesh electrodes 20a, 20b, 20c are stuck to the vibration body 12. An angular velocity sensor 10 using the piezoelectric elements 14a, 14b, 14c is thus obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric element, and more particularly to a piezoelectric element used for a vibration gyro used as an angular velocity sensor, an acceleration sensor, a pressure sensor, a displacement sensor and the like.

[0002]

2. Description of the Related Art FIG. 4 is a perspective view showing an angular velocity sensor using a conventional piezoelectric element which is the background of the present invention, and FIG. 5 is a sectional view thereof. The angular velocity sensor 1 includes a vibrating body 2 formed of a material that causes mechanical vibration, such as Elinba. The vibrating body 2 is formed in a triangular prism shape, and three piezoelectric elements 3a, 3b, 3c are formed on the side surface thereof. The piezoelectric elements 3a, 3b, 3c include piezoelectric bodies 4a, 4b, 4c, and electrodes 5a, 5b, 5c are formed on both main surfaces thereof. Then, one of the electrodes 5a, 5b, 5c is bonded to the side surface of the vibrating body 2.

When the angular velocity sensor 1 is used, an oscillation circuit output source is connected between the piezoelectric elements 3a and 3b and the piezoelectric element 3c, for example. The output signal from the oscillation circuit output source causes the vibrating body 2 to flexurally vibrate in a direction orthogonal to the surface on which the piezoelectric element 3c is formed. When rotating about the axis of the angular velocity sensor 1, an output voltage is generated in the piezoelectric elements 3a and 3b. By measuring the difference between the output voltages from the piezoelectric elements 3a and 3b, the rotational angular velocity applied to the angular velocity sensor 1 is measured.

[0004]

However, in the piezoelectric element used in such an angular velocity sensor, since the electrode is formed on the main surface of the piezoelectric body, the difference in the coefficient of thermal expansion between the piezoelectric body and the electrode causes The piezoelectric element is warped or distorted due to a change in ambient temperature. Therefore, a voltage other than the voltage corresponding to the rotation angular velocity is generated, and there is a problem that the characteristics of the angular velocity sensor are likely to vary.

Therefore, a main object of the present invention is to provide a piezoelectric element capable of obtaining a sensor in which the characteristics are less likely to vary even if the ambient temperature changes.

[0006]

The present invention relates to a piezoelectric body,
A piezoelectric element including a mesh-shaped mesh electrode formed on the main surface of the piezoelectric body.

[0007]

By forming a mesh-shaped mesh electrode on the piezoelectric body, expansion and contraction of the electrode due to changes in ambient temperature are dispersed.

[0008]

According to the present invention, since the expansion and contraction of the electrodes are dispersed, a large stress is not applied to the piezoelectric body, and the piezoelectric element is unlikely to be warped or strained. Therefore, an unnecessary voltage is unlikely to be generated in the piezoelectric element, and if this piezoelectric element is used in, for example, an angular velocity sensor, it is possible to obtain an angular velocity sensor with a small rate of change in output voltage.

The above-mentioned objects, other objects, features and advantages of the present invention will become more apparent from the following detailed description of embodiments with reference to the drawings.

[0010]

1 is a perspective view showing an angular velocity sensor using a piezoelectric element of the present invention, and FIG. 2 is a sectional view thereof. The angular velocity sensor 10 includes a vibrating body 12. The vibrating body 12 is made of, for example, a material that causes mechanical vibration, such as Elinba, and is formed in a regular triangular prism shape. Piezoelectric elements 14a, 14b, 14 are provided at the central portions of the three side surfaces of the vibrating body 12, respectively.
c is formed. The piezoelectric element 14a includes a piezoelectric body 16a, and a mesh-shaped mesh electrode 18a and a mesh-shaped mesh electrode 20a are formed on both main surfaces of the piezoelectric body 16a.
Then, one mesh electrode 20a is bonded to the side surface of the vibrating body 12. Similarly, the piezoelectric elements 14b and 14c include piezoelectric bodies 16b and 16c, and mesh electrodes 18b and 20b and mesh electrodes 18c and 20c are formed on both main surfaces of the piezoelectric bodies 16b and 16c. Then, the vibrating body 12
On the side surface of the mesh electrode 20b and the mesh electrode 20
c is glued.

The piezoelectric bodies 16a, 16b, 16c of the piezoelectric elements 14a, 14b, 14c are formed, for example, by forming a piezoelectric ceramic material into a plate shape and firing it. An electrode is formed by printing a metal paste such as Ag-Pd in a mesh shape on the main surface of the obtained piezoelectric body and applying a baking treatment or the like.

To measure the rotational angular velocity using this angular velocity sensor 10, for example, a circuit as shown in FIG. 3 is used. In this circuit, the oscillation circuit output source 30 is connected between the piezoelectric elements 14a and 14b and the piezoelectric element 14c. Then, by the signal from the oscillation circuit output source 30,
The vibrating body 12 vibrates. In this case, the vibrating body 12 flexurally vibrates in the direction orthogonal to the surface to which the piezoelectric element 14c is bonded. Further, the piezoelectric elements 14a and 14b are connected to the differential circuit 32.
Connected to. When the vibrating body 12 rotates about its axis, the direction of vibration changes due to the Coriolis force.
In response to this, a voltage is generated in the piezoelectric elements 14a and 14b. By measuring this voltage difference using the differential circuit 32, the rotational angular velocity applied to the angular velocity sensor 10 is measured.

In this angular velocity sensor 10, the mesh electrode is formed in a mesh shape so that the expansion and contraction of the mesh electrode due to the change in the ambient temperature is dispersed. Therefore, even if the ambient temperature changes, undue stress is not applied to the piezoelectric body. Therefore, even if the ambient temperature changes, the piezoelectric element is unlikely to warp or distort. Therefore, the generation of a voltage other than the voltage corresponding to the rotational angular velocity applied to the angular velocity sensor 10 is small, and accurate measurement can be performed.

Although the piezoelectric element of the present invention is applied to the angular velocity sensor in the above-mentioned embodiments, the piezoelectric element can also be applied to an acceleration sensor, a pressure sensor, a displacement sensor, and the like. The accuracy can be increased.

[Brief description of drawings]

FIG. 1 is a perspective view showing an embodiment of the present invention.

FIG. 2 is a cross-sectional view of the angular velocity sensor shown in FIG.

FIG. 3 is a block diagram showing a circuit when the angular velocity sensor shown in FIG. 1 is used.

FIG. 4 is a perspective view showing an angular velocity sensor using a conventional piezoelectric element which is the background of the present invention.

5 is a cross-sectional view of the angular velocity sensor shown in FIG.

[Explanation of symbols]

 10 angular velocity sensor 12 vibrating body 14a, 14b, 14c piezoelectric element 16a, 16b, 16c piezoelectric body 18a, 18b, 18c electrode 20a, 20b, 20c electrode

Claims (1)

Claim: What is claimed is: 1. A piezoelectric element, comprising: a piezoelectric body; and a mesh electrode formed on a main surface of the piezoelectric body.