JPH08153911A - Piezoelectric transformer - Google Patents

Abstract

PURPOSE: To obtain a safe piezoelectric transformer which is not broken down by a long time driving, by nonlinearly constituting the boundary between drive electrodes formed on almost the half part of the main surface of a piezoelectric element and a power generating part where the drive electrodes are not formed. CONSTITUTION: Drive electrodes 12 are formed on almost the half parts of the main surfaces of a rectangular planar piezoelectric element 11. A power generating electrode 14 for leading out a high voltage is formed on the side end surface of a power generating part 13 where the drive electrodes 12 are not formed. The boundary part between the drive electrodes 12 and the power generating part 13 where the drive electrodes 12 are not formed is constituted as a rectangular wave form. After a DC voltage is applied across the drive electrodes 12 and polarization process is performed, the drive electrodes 12 are connected, a DC voltage is sililarly applied across the drive electrodes 12 and the power generating electrode 14, and polarization process of the power generating part 13 is performed. In a piezoelectric transformer, the boundary between the drive electrodes 12 and the power generating part 13 is nonlinear, so that the strain of piezoelectric crystal which is generated inside along the boundary line after the polarization process of the power generating part 13 is dispersed. Thereby the breakdown of the piezoelectric element 11 which is to be generated in a long time driving can be prevented.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer used as a high voltage power source for a television receiver, a backlight power source for a word processor, a high voltage and small current power source such as a power source for electrostatic coating.

[0002]

2. Description of the Related Art In a conventional piezoelectric transformer of this type, as shown in FIGS. 4 and 5, an excitation electrode 2 is provided on approximately half of the main surface of a rectangular plate-shaped piezoelectric element 1, and the excitation electrode 2 is formed. After the power generation electrode 4 is formed on the side end surface of the power generation unit 3 which is not formed, and a DC voltage is applied between the excitation electrodes 2 to perform polarization treatment,
The excitation electrode 2 is connected, and a direct current voltage is similarly applied between the excitation electrode 2 and the power generation electrode 4 to polarize the power generation unit 3.

[0003]

As described above, in the conventional piezoelectric transformer, since the boundary between the excitation electrode 2 and the power generation section 3 is a straight line, after the polarization processing of the power generation section 3, as shown in FIG. There is a problem that a uniform strain 5 of the piezoelectric element crystal is generated inside along the boundary line, and the strain 5 grows and is destroyed from the boundary line portion during long-time driving.

An object of the present invention is to eliminate the above-mentioned conventional drawbacks and to provide a safe piezoelectric transformer which is not destroyed even when it is driven for a long time.

[0005]

In order to solve the above-mentioned problems, the present invention defines a boundary between an excitation electrode formed on about half of the main surface of a piezoelectric element and a power generation section on which this excitation electrode is not formed. It is a straight line.

[0006]

In the piezoelectric transformer having the above structure, the boundary between the excitation electrode formed on about half of the main surface of the piezoelectric element and the surface of the power generation section where the excitation electrode is not formed is made non-linear to thereby form the power generation section. It is possible to disperse the strain of the piezoelectric element crystal generated inside along the boundary line during the polarization treatment of (1) to prevent the piezoelectric element from being destroyed during long-time driving.

[0007]

Embodiments of the present invention will be described below with reference to FIGS. 1, 2 and 3. The excitation electrode 12 is formed on about half of the main surface of the rectangular and plate-shaped piezoelectric element 11, and the power generation electrode 14 for extracting a high voltage is formed on the side end surface of the power generation unit 13 where the excitation electrode 12 is not formed. The boundary between the excitation electrode 12 and the power generation section 13 where the excitation electrode 12 is not formed,
That is, the excitation electrode 12 has a rectangular wave shape on the power generation section 13 side, and a DC voltage is applied between the excitation electrodes 12 to perform polarization processing, and then the excitation electrode 12 is connected to the power generation electrode 14 in the same manner. It is configured by applying a DC voltage and subjecting the power generation unit 13 to polarization processing.

With the above-described structure, since the boundary between the excitation electrode 12 and the power generation section 13 is non-linear in this piezoelectric transformer, as shown in FIG. Along the inside of the piezoelectric element crystal strain 1
5 is dispersed and can prevent the piezoelectric element 11 from being destroyed when it is driven for a long time.

In the present embodiment, the boundary line between the excitation electrode 12 and the power generation section 13 has a rectangular wave shape, but it goes without saying that the same effect can be obtained with a wave shape or a triangular wave shape.

[0010]

According to the invention as described above, the excitation electrode is formed on about half of the main surface of the piezoelectric element, and the boundary with the surface of the power generation section where the excitation electrode is not formed is made non-linear. As a result, it is possible to provide a highly reliable piezoelectric transformer that disperses the strain of the piezoelectric element crystal generated during the polarization process and does not break even when driven for a long time.

[Brief description of drawings]

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

FIG. 2A is a plan view of the same, and FIG. 2B is a side view of the same.

FIG. 3 is a sectional view of the same boundary line part.

FIG. 4 is a perspective view of a piezoelectric transformer showing a conventional example.

FIG. 5A is a plan view of the same, and FIG. 5B is a side view of the same.

FIG. 6 is a sectional view of the same boundary line portion.

[Explanation of symbols]

 11 piezoelectric element 12 excitation electrode 13 power generation unit 14 power generation electrode 15 piezoelectric element crystal distortion

Claims (2)

[Claims] 1. An excitation electrode is formed on about half of a main surface of a rectangular plate-shaped piezoelectric element, and a power generation electrode for extracting a high voltage is formed on a side end surface of the power generation unit side where the excitation electrode is not formed, A piezoelectric transformer in which the boundary between the excitation electrode and the surface of the power generation section where the excitation electrode is not formed is non-linear. 2. The non-linear shape of the boundary between the excitation electrode and the power generation section is a rectangular wave shape, a wave shape, or a triangular wave shape.
Piezoelectric transformer described.