JP2001326397A - Piezoelectric transformer (1) - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric transformer of high yield where temperature rise at driving is suppressed to low. SOLUTION: A laminated piezoelectric transformer 8 is provided where the thickness of a joint layer 1 for jointing, at the end surfaces in lengthwise direction, an input part 6 and an output part 7 constituting a piezoelectric transformer which utilizes resonance in lengthwise direction is 2-80 μm.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer utilizing resonance in a longitudinal direction, and more particularly, to a piezoelectric transformer designed to be small in size and to keep the temperature rise low.

[0002]

2. Description of the Related Art Conventionally, in order to manufacture a piezoelectric transformer utilizing vibration in a longitudinal direction, a sheet made of a piezoelectric material and internal electrodes are alternately laminated in a longitudinal direction, and an input portion and an output portion are sintered by sintering. The piezoelectric transformer is obtained by integrally providing an external electrode for connecting a plurality of internal electrodes in parallel, and simultaneously or separately polarizing the input portion and the output portion. However, since the number of layers differs between the input unit and the output unit, the number of internal electrodes also differs according to the number of layers. For this reason, when the input part and the output part are polarized by a high electric field with the piezoelectric transformer integrated at the time of sintering, the input part and the output part may be cracked due to polarization distortion generated at the time of polarization, whether simultaneously or separately. Was easy to occur and the yield was not good. Therefore, in order to increase the yield, the input part and the output part were separately manufactured and polarized, and the polarization yield was improved, but the input part and the output part were simply joined to obtain a piezoelectric transformer. Was.

[0003]

Conventionally, the input portion and the output portion of the piezoelectric transformer have been separately manufactured and subjected to polarization to improve the polarization yield, but the bonding layer for joining the input portion and the output portion has been improved. Since the thickness was not taken into consideration, when the piezoelectric transformer was actually driven, the variation in temperature rise of the piezoelectric transformer became large, and the final yield was low.

An object of the present invention is to set a thickness of a joining layer for joining an input portion and an output portion of a piezoelectric transformer,
An object of the present invention is to provide a piezoelectric transformer in which a rise in temperature is kept low in a piezoelectric transformer driving state.

[0005]

According to the piezoelectric transformer of the present invention, the thickness of the joining layer for joining the input part and the output part constituting the piezoelectric transformer is set to 2 μm or more and 80 μm or less so that the temperature rise is suppressed and the yield is improved. Wherein the bonding layer is made of a bonding material having a hardness (Shore D) of 70 or more.

[0006]

Embodiments of the present invention will be described below. FIG. 1 shows an example of an external perspective view of a piezoelectric transformer of the present invention, in which external electrodes 3 and 5 for connecting a plurality of internal electrodes 2 and 4 in parallel (there is also a surface opposite to the surface shown in FIG. 1). The input part 6 and the output part 7 (not shown) are separately polarized and then joined, and 1 is a joining layer. The piezoelectric transformer 8 uses an epoxy-based adhesive (Shore D hardness 80, 84) as a bonding material, performs curing under standard curing conditions, and joins the input unit 6 and the output unit 7.

FIG. 2 is a graph showing the relationship between the thickness of the bonding layer and the temperature rise (ΔT) of the piezoelectric transformer when the piezoelectric transformer 8 is driven at an output power of 10 W, and the thickness of the bonding layer is 2 μm. In the range of 80 μm or less, ΔT satisfies the practical level of 25 ° C. or less.

FIG. 3 is a graph showing the relationship between the bonding layer hardness and the temperature rise (ΔT) of the piezoelectric transformer when the piezoelectric transformer 8 is driven at an output power of 10 W, without impairing the vibration transmission. It has a hardness (Shore D) of 70 or more and ΔT satisfying a practical level of 25 ° C. or less.

In this embodiment, an epoxy-based adhesive is used as a bonding material. However, it is needless to say that a bonding material having a hardness (Shore D) of 70 or more and not impairing vibration transmission may be used.

[0010]

As described above, according to the present invention,
The input part and the output part constituting the piezoelectric transformer are separately manufactured, and the thickness of the bonding layer that joins the input part and the output part is set to 2 μm or more and 80 μm or less while maintaining a high yield by performing polarization. By setting the hardness (Shore D) of the bonding layer to 70 or more, a piezoelectric transformer having a practically raised temperature (ΔT) in a piezoelectric transformer driving state can be obtained with high yield.

[Brief description of the drawings]

FIG. 1 is an example of an external perspective view of a piezoelectric transformer according to an embodiment of the present invention.

FIG. 2 is a view for explaining the effect of the present invention, showing ΔT depending on the thickness of a bonding layer.

FIG. 3 is a diagram for explaining the effect of the present invention, and is a diagram showing ΔT depending on the hardness of a bonding layer.

[Explanation of symbols]

 1. 1. bonding layer 2. Input side internal electrode Input side external electrode 4. Output side internal electrode 5. Output side external electrode 6. Input unit 7. Output unit 8. Piezoelectric transformer

Claims (2)

[Claims] 1. A laminated piezoelectric transformer in which an input portion and an output portion constituting a rectangular rod-shaped piezoelectric transformer utilizing resonance in a longitudinal direction are joined at respective end faces in a longitudinal direction, and a thickness of a joining layer is 2 μm or more and 80 μm or more. A laminated piezoelectric transformer characterized by the following. 2. The multi-layer piezoelectric transformer according to claim 1, wherein the bonding layer is made of a bonding material having a hardness (Shore D) of 70 or more.