JPH1074992A - Piezoelectric transformer component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of audio-frequency vibration sound and provide a method for holding a highly reliable piezoelectric transformer which can be miniaturized, especially at the time of loading a cold cathode tube. SOLUTION: A Rosen-type piezoelectric transformer, which is provided with driving electrodes 4 and 5 formed on the front and rear planes of a piezoelectric element and a generating electrode 6, is stored in an armor case 11, which has input/output conducting parts 10 and 13, and a piezoelectric transformer holding structure sandwiches a piezoelectric transformer main body 1 via the armor case 11 through rubber elastic body 12. In this case, the rubber elastic bodies 12 and 14 positioned at the generating electrode 6 and the part of the driving electrodes 4 and 5 of the piezoelectric transformer are conductive, the conductive parts 10 and 13 are connected to the generating electrode 6 and the driving electrodes 4 and 5 through the conductive rubber elastic bodies 12 and 14, and at least one supporting position of the rubber elastic body 15 or the conductive rubber elastic bodies 12 and 14 is located at a part away from the vibration node by 1/8 of a wavelength.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a highly reliable piezoelectric transformer component for converting an AC voltage in an electronic device or the like.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays have rapidly become widespread in personal computers, cameras, and the like, and at the same time, miniaturization due to portability has been accelerated. Attention has been paid to a piezoelectric transformer having a high conversion efficiency, which has a simple structure, can be reduced in thickness, can reduce noise, and has a high conversion efficiency for lighting the backlight of the liquid crystal display.

[0003] A conventional piezoelectric transformer will be described below. FIG. 4 shows the appearance of a conventional piezoelectric transformer. In FIG. 4, reference numeral 1 denotes a piezoelectric transformer main body,
And a power generation unit 3. Drive electrodes 4 and 5 are provided on the front and back surfaces of the drive unit 2, and a power generation electrode 6 is provided at an end of the power generation unit 3. Drive electrodes 4 and 5
The lead wire 7 is soldered to the power generation electrode 6.
FIG. 5 shows the piezoelectric transformer shown in FIG. 4 housed in an outer case 9 using a silicone adhesive 8 having rubber elasticity.

[0004]

However, in the above-mentioned conventional configuration, resonance occurs in the lead wire 7 due to mechanical vibration when the piezoelectric transformer is driven, and a beat sound, disconnection due to mechanical fatigue, and soldering are caused. There was a problem that the electrode of the part peeled off.

When a cold cathode fluorescent lamp is used as a backlight as a backlight of a liquid crystal display, when the lighting is started, the impedance of the cold cathode fluorescent lamp as a load suddenly changes from an infinite value in an open state to several tens of kilohms when the lighting state is stable. Change. In particular, when the load is released, the mechanical quality factor (hereinafter referred to as Qm) during resonance of the piezoelectric transformer has a maximum value, the input impedance is low, a large current temporarily flows into the piezoelectric transformer, and the piezoelectric transformer is large due to mechanical resonance. Causes distortion. That is, the operation of the piezoelectric transformer is more severe at the start of lighting than at the time of stable lighting. In particular, piezoelectric ceramics, when brittle fracture occurs, will instantly break if the elastic limit is exceeded due to strain.Therefore, a sufficient safety factor must be considered in the design of piezoelectric transformers. was there.

SUMMARY OF THE INVENTION The present invention solves the above-mentioned conventional problems by preventing the generation of audible frequency vibrating sounds and further reducing the size, especially when a cold cathode tube is used as a load, and providing a highly reliable piezoelectric transformer component. The purpose is to provide.

[0007]

In order to achieve this object, the present invention provides an outer case having a conductive portion provided with input / output terminals, and a plurality of conductive rubber elastic members inside the outer case. A rosen-type piezoelectric transformer that is sandwiched and electrically connected to the conductive portion, the rosen-type piezoelectric transformer includes a piezoelectric element, a driving electrode on one side of the piezoelectric element, a drive electrode on the back side, and a piezoelectric element on the other side. A power generating electrode, and at least one portion of the rubber elastic body that holds the Rosen-type piezoelectric transformer is a piezoelectric transformer component that is at least 1/8 wavelength away from a node of vibration of the Rosen-type piezoelectric transformer; This structure eliminates the need for soldering lead wires, enables electrical connection and holding at the same time, and holds the piezoelectric transformer with a conductive rubber elastic body to absorb mechanical vibrations and generate sound. It can also prevent. In addition, since a rubber portion is used to suppress a vibration portion separated from a vibration node, which is a main effect of the present invention, Qm at the time of resonance of the piezoelectric transformer can be reduced when the load is high impedance. Further, since a rubber elastic body is used for suppressing vibration, the vibration is absorbed and no vibration noise is generated.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention provides an outer case having a conductive portion having an input / output terminal,
A Rosen-type piezoelectric transformer sandwiched in the outer case via a plurality of conductive rubber elastic bodies and electrically connected to the conductive portion, wherein the Rosen-type piezoelectric transformer includes a piezoelectric element; The piezoelectric element has a drive electrode on one side, a drive electrode on the back side, and a power generation electrode on the other side, and at least one portion of the rubber elastic body that holds the Rosen-type piezoelectric transformer has vibrations of the Rosen-type piezoelectric transformer. This is a piezoelectric transformer component that is 1/8 wavelength or more away from the node. It can simultaneously connect and hold the electrical connection, and lowers the Qm at resonance of the piezoelectric transformer even when the load is high impedance, thereby connecting the cold cathode tube with the load. At the start of lighting, large current flow due to large Qm can be prevented at the start of lighting, and vibration is absorbed because a rubber elastic body is used to suppress vibration, generating vibration noise. Those having an action like no.

According to a second aspect of the present invention, the rubber elastic body comprises:
2. The piezoelectric transformer component according to claim 1, wherein the piezoelectric transformer component has a silicone rubber as a matrix and silver as a conductive material, and has a high elasticity, a stable elasticity against environmental temperature changes, and a low electric resistance.

An embodiment of the present invention will be described below with reference to FIGS. Embodiment 1 FIG. 2 shows the appearance of a Rosen second-order (λ mode) type piezoelectric transformer. In FIG. 2, reference numeral 1 denotes a piezoelectric transformer body, and the displacement distribution of vibration during driving is indicated by a dotted line.
The piezoelectric transformer main body 1 is composed of a drive unit 2 and a power generation unit 3. Independent drive electrodes 4 and 5 are provided on the front and back surfaces of the drive unit 2, and a power generation electrode 6 is provided on the front and back surfaces of the power generation unit 3. Is provided.

FIG. 1 shows an external appearance of an embodiment of the present invention. Reference numeral 10 denotes an input-side conductive portion integrated with an input terminal provided on an outer case 11, which electrically connects nodes of the drive electrodes 4 and 5 to each other. And is electromechanically connected to a piezoelectric transformer. Reference numeral 13 denotes an output-side conductive portion which is also integrated with an output terminal disposed on the outer case 11, and sandwiches the power generation electrode 6 via a conductive rubber elastic body 14, and is electrically and mechanically connected to the piezoelectric transformer. Connected. In this case, the holding position is a position separated by ４ wavelength from the node of vibration. Further, the piezoelectric transformer is also sandwiched by the outer case 11 via the rubber elastic body 15 at a vibration node at the center of the power generation unit 3.

FIG. 3 shows a power generator 3 on the output side of the piezoelectric transformer.
6 shows the characteristics of the input impedance on the drive side when the circuit is opened. Compared to the case where only the nodes of vibration are held,
When the portion is separated by 箇 所 wavelength and １ ／ wavelength, the vibration is suppressed and the input impedance at the piezoelectric transformer resonance point increases.

The conductive rubber elastic bodies 12 and 14 used in the present embodiment are made of silicone rubber as a matrix and silver mixed with silicone rubber as a conductive material.

[0014]

As described above, according to the present invention, electrical connection and mechanical holding can be simultaneously performed without the need for soldering lead wires as in the prior art, and the piezoelectric transformer is made of a conductive rubber elastic body. The mechanical vibration is absorbed and the generation of sound can be prevented. In addition, a rubber elastic body is used to suppress a vibration portion apart from a node of vibration, which is a main effect of the present invention. Particularly, when a cold cathode tube is used as a load, Qm at the time of starting the lighting of the piezoelectric transformer at the time of lighting start can be reduced. It is possible to prevent the piezoelectric transformer from vibrating more than necessary. Further, since a rubber elastic body is used for suppressing vibration, the vibration is absorbed and no vibration noise is generated. Therefore, it is possible to provide a highly reliable piezoelectric transformer component which can be further reduced in size.

[Brief description of the drawings]

FIG. 1 is a sectional view of a piezoelectric transformer component according to an embodiment of the present invention.

FIG. 2 is a sectional view of a Rosen secondary (λ mode) type piezoelectric transformer.

FIG. 3 is a diagram showing an input impedance characteristic curve of a piezoelectric transformer.

FIG. 4 is a perspective view of a conventional piezoelectric transformer main body.

FIG. 5 is a cross-sectional view of a state where a conventional piezoelectric transformer is housed in an outer case.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric transformer main body 4 Drive electrode 5 Drive electrode 6 Power generation electrode 10 Conductive part 11 Exterior case 12 Rubber elastic body 13 Conductive part 14 Rubber elastic body 15 Rubber elastic body

Claims (2)

[Claims] 1. An outer case having a conductive portion having input / output terminals, and a rosen sandwiched in the outer case via a plurality of conductive rubber elastic bodies and electrically connected to the conductive portion. Type piezoelectric transformer, the Rosen type piezoelectric transformer has a piezoelectric element, a front electrode on one side of the piezoelectric element, a drive electrode on the back surface, a power generation electrode on the other side,
A piezoelectric transformer component, wherein at least one portion of the rubber elastic body that holds the Rosen-type piezoelectric transformer is at least 1/8 wavelength away from a node of vibration of the Rosen-type piezoelectric transformer. 2. The piezoelectric transformer component according to claim 1, wherein the rubber elastic body is based on silicone rubber and has silver as a conductive material.