JPH098374A - Piezoelectric transformer - Google Patents

Abstract

PURPOSE: To obtain a piezoelectric transformer in which the positioning with respect to the node of oscillation and the fixing of I/O lead wires are facilitated without causing deterioration in the characteristics and reliability due to supporting. CONSTITUTION: First and second conductive supporting metals 7, 8 having protrusions 7a, 8a are fixed to a node of oscillation on the side face of a rectangular piezoelectric oscillator 2. The first supporting metal 7 is connected electrically with an input side electrode 3 provided on the rectangular piezoelectric oscillator 2 while the second supporting metal 8 is connected electrically with output side electrodes 5, 6 provided on the rectangular piezoelectric oscillator 2. The first and second protrusions 7a, 8a are located at the nodes of oscillation and supported by a flexible resin 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer using a rectangular plate of a piezoelectric vibrator, and more particularly, a piezoelectric transformer characterized by a supporting structure of the rectangular plate of the piezoelectric vibrator and an electrode connection structure for transformer input / output. It is about.

[0002]

2. Description of the Related Art A high voltage power supply of about 1 KV-several watts is used for a static electricity generator or for lighting a backlight of a liquid crystal display, although a large current value is not required. At present, electromagnetic transformers are used as boosters for these power supplies, but due to demands such as reduction of generated electromagnetic noise, lower power consumption, and downsizing of equipment, the study of practical use of piezoelectric transformers has been considered. It has been done.

FIG. 3 is a schematic perspective view of the structure of a piezoelectric vibrator used in a conventional piezoelectric transformer called Rosen type. Piezoelectric vibrators include piezoelectric ceramics and lithium niobate single crystals, but in FIG. 3, a piezoelectric ceramic rectangular plate 31 is used as a piezoelectric vibrator rectangular plate. The electrodes 3 facing each other in the thickness direction of the piezoelectric ceramic rectangular plate 31 are provided at approximately half of the length of the plate 31.
2 and the electrode 33 are formed. Further, an end face electrode 34 is formed on the end face in the length direction of the piezoelectric ceramic rectangular plate 31 opposite to the portion where the electrodes 32 and 33 are formed. The piezoelectric ceramic rectangular plate 31 is polarized in the thickness direction of the piezoelectric ceramic rectangular plate 31 in the portion between the electrodes 32 and 33, as indicated by the arrow, and the end face electrode 34 and the electrode 3 are polarized.
The portion between 2 and 33 is polarized in the length direction of the piezoelectric ceramic rectangular plate 31, as shown by the arrow.

4A and 4B are explanatory views of the operation principle of the piezoelectric transformer using the piezoelectric vibrator shown in FIG. 3, FIG. 4A is a side view of the piezoelectric ceramic rectangular plate, and FIG. 4B is a piezoelectric ceramic rectangular plate. FIG. 4C is a displacement distribution diagram when the plate is vibrating in the one-wavelength resonance mode of longitudinal vibration, and FIG. 4C is a strain distribution diagram at that time. In FIG. 4A, when the electrode 33 is used as a ground terminal and a voltage having a frequency equal to the resonance frequency of the one-wavelength resonance mode in the length direction of the piezoelectric ceramic rectangular plate 31 is applied to the electrode 32, the piezoelectric ceramic rectangular plate 31 is Four
It vibrates as shown in (b) and (c). At this time, a voltage is generated between the electrode 33 and the end surface electrode 34 by the piezoelectric effect. Here, the input voltage applied to the electrode 32 and the output voltage generated at the end face electrode 34 will be described.
The facing distance between the electrode 2 and the electrode 33 is sufficiently smaller than the distance between the electrode 33 and the end surface electrode 34, and the areas of the electrodes 32 and 33 are sufficiently larger than the area of the end surface electrode 34. Therefore, the capacitance on the input side is equal to that on the output side. The value is sufficiently larger than the capacitance. Therefore, when a low voltage is applied to the input side to vibrate the piezoelectric vibrator, a large voltage proportional to the ratio of the input side electrode spacing and the output side electrode spacing is generated on the output side.

[0005]

In the practical application of the piezoelectric transformer for the static electricity generating device, the liquid crystal backlight inverter, etc., it is important to stably support the piezoelectric vibrator and make the electrode connection highly reliable. Many inventions and ideas have been made regarding the support structure and the electrode extraction structure. An object of these inventions and inventions is to provide a mechanically flexible support structure and electrode connection structure that do not cause deterioration of vibrator characteristics. Most of the support structures are piezoelectric vibrators. The structure in which the node of vibration is supported by an insulating elastic body, and the electrode take-out structure is a structure in which a contact connection of a leaf spring or a coil spring or a conductive elastic body is used.

However, it is difficult to accurately position and support the node of vibration with the above-described direct mechanical flexible support structure and electrode connection structure for the piezoelectric vibrator.
Therefore, in order to solve the problems of the prior art, the technical problem of the present invention is that the positioning with respect to the vibration node is easy, the lead wires for input / output are easy to attach, and the deterioration of the characteristics due to the support and the reliability It is to provide a piezoelectric transformer that does not deteriorate.

[0007]

According to the invention described in claim 1, a piezoelectric vibrator rectangular plate and a piezoelectric vibrator rectangular plate for inputting an electric signal to the piezoelectric vibrator rectangular plate are provided. A resonance mode in the longitudinal direction of the piezoelectric vibrator rectangular plate, including an input side electrode and an output side electrode provided on the piezoelectric vibrator rectangular plate for extracting an electric signal from the piezoelectric vibrator rectangular plate. In the piezoelectric transformer using the above, first and second conductive support members are attached to the vibration nodes on the side surface of the piezoelectric vibrator rectangular plate, and the first support member is the first support member. Has a first protrusion on a side surface opposite to the side surface of the support tool that is in contact with the side surface, and is electrically connected to the input-side electrode, and the second support tool is the second support tool. A second protrusion on the side opposite to the side contacting the side of the tool, and A piezoelectric element, which is electrically connected to an output-side electrode, wherein the first and second protrusions are respectively located at the nodes of the vibration and are supported by a flexible resin. You get a transformer.

According to the invention of claim 2, the lead wire is connected to the first and second protrusions in the resin, respectively, to obtain the piezoelectric transformer of claim 1. To be

[0009]

In general, it is desirable that the piezoelectric transformer be supported by vibration nodes so as not to cause a decrease in electromechanical coupling coefficient (Qm) and a change in resonance frequency, but actual support is not always easy. According to the present invention, the piezoelectric vibrator rectangular plate is driven by the resonance mode in the length direction thereof.
Since the first and second supporting members can be firmly fixed, the positioning accuracy is improved, and the first and second supporting members are respectively provided on the first and second supporting members and located at the vibration nodes. Since it is possible to flexibly support the projections, it is possible to prevent performance deterioration of the piezoelectric transformer due to the influence of the support. Regarding the connection structure of the lead wire, wiring is performed in a flexible supporting resin, and the lead wire is electrically connected to the first and second protrusions at the contact surface between the resin and the first and second protrusions, respectively. In addition, since the lead wire is connected to the node of vibration when the transformer is driven, it is possible to secure the reliability of performance when the piezoelectric transformer is used for a long period of time.

[0010]

EXAMPLES The present invention will be described in detail below with reference to examples.

FIG. 1 is a perspective view of a piezoelectric transformer according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line AA of FIG.

Referring to FIGS. 1 and 2, a length of 40 mm,
Using a PZT-based piezoelectric ceramic rectangular plate having a width of 10 mm and a thickness of 1 mm, a piezoelectric transformer of one wavelength resonance mode in the length direction was experimentally manufactured.

The piezoelectric transformer 1 includes the above-mentioned piezoelectric ceramic rectangular plate 2, and the input side electrodes 3 and 4 provided on the piezoelectric ceramic rectangular plate 2 for inputting an electric signal to the piezoelectric ceramic rectangular plate 2. The piezoelectric ceramic rectangular plate 2 has output electrodes 5 and 6 provided on the piezoelectric ceramic rectangular plate 2 in order to extract an electrical signal.

First and second support members 7 and 8 made of copper are attached to the vibration nodes on the side surfaces of the piezoelectric ceramic rectangular plate 2 (both end surfaces in the width direction of the piezoelectric ceramic rectangular plate 2).

There are a pair of first support members 7, and these first support members 7 are
Of the first supporting member 7 on the side opposite to the one surface of the first supporting member 7 that is in contact with the side surface of the piezoelectric ceramic rectangular plate 2.
It has a protrusion 7a. In the case of the present embodiment, the first support member 7 has a width of 1 mm, and the first protrusion 7a has a diameter of 0.5 mm and a length of 2.5 mm. One surface of each of these first supporting members 7 is soldered to the side surface of the piezoelectric ceramic rectangular plate 2 and is electrically connected to one of the input side electrodes 3 and 4, respectively.

There are a pair of second support members 8 and these second support members 8
The second supporting member 8 of the second supporting member 8 is in contact with the side surface of the piezoelectric ceramic rectangular plate 2, and the second supporting member 8 of the second supporting member 8 has a second surface.
It has a protrusion 8a. In the case of this embodiment, the second support 8 has a width of 1 mm, and the first protrusion 8a has a diameter of 0.5 mm and a length of 2.5 mm. One surface of each of these second supporting members 8 is soldered to the side surface of the piezoelectric ceramic rectangular plate 2, and is electrically connected to one of the output side electrodes 5 and 6, respectively.

The first and second protrusions 7a and 8a are respectively located at the vibration nodes of the piezoelectric ceramic rectangular plate 2 and supported by a flexible resin 10 disposed on the inner surface of the frame 9. ing. In the case of the present embodiment, this resin 10
Silicon resin is used as.

Lead wires 11 are soldered in the resin 10 to the tips of the first and second protrusions 7a and 8a, respectively.

In the case of the present embodiment, the nodes of vibration of the one-wavelength resonance mode in the lengthwise direction are located 10 mm from both end faces of the piezoelectric ceramic rectangular plate 2 in the lengthwise direction. The first so that the second protrusions 7a, 8a come
Also, the second supporting members 7 and 8 are soldered to the side surfaces of the piezoelectric ceramic rectangular plate 2.

Table 1 shows the step-up ratios before and after the supporting of the trial-produced piezoelectric transformer 1, and the failure rate after 100 hours of continuous driving test of 100 piezoelectric transformers 1. As a comparative example, Table 1 shows the characteristics of the piezoelectric transformer in which the lead wire is directly soldered to the same piezoelectric ceramic rectangular plate and simply supported by the silicon resin.

[0021]

[Table 1] As is clear from Table 1, in the piezoelectric transformer of the present embodiment, the characteristics of Qm and boosting ratio before and after the support are less deteriorated, and the reliability of the electrode connection is obtained even when continuously driven for a long time.

[0022]

As described above in detail, according to the present invention, the vibration nodes can be easily positioned, the input / output lead wires can be easily attached, and the deterioration of the characteristics and the deterioration of the reliability due to the support can be achieved. It is possible to provide a piezoelectric transformer that does not come.

[Brief description of drawings]

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

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view of an example of a conventional ½ wavelength resonance mode piezoelectric ceramic.

FIG. 4 shows the piezoelectric ceramic rectangular plate shown in FIG.
(A) is a side view, (b) is a deviation distribution diagram when a piezoelectric ceramic rectangular plate is vibrating in a longitudinal half-wavelength resonance mode, and (c) is a strain distribution in the state of (b). It is a figure.

[Explanation of symbols]

 1 Piezoelectric Transformer 2 Piezoelectric Ceramic Rectangular Plate (Piezoelectric Vibrator Rectangular Plate) 3 Input Side Electrode 4 Input Side Electrode 5 Output Side Electrode 6 Output Side Electrode 7 First Supporting Tool 7a First Protrusion 8 Second Supporting Tool 8a 2 protrusions 9 frame 10 resin

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Taishi Shiotani 6-7 Koriyama, Taichiro-ku, Sendai-shi, Miyagi Tokin Co., Ltd.

Claims (2)

[Claims] 1. A piezoelectric vibrator rectangular plate, an input-side electrode provided on the piezoelectric vibrator rectangular plate for inputting an electrical signal to the piezoelectric vibrator rectangular plate, and an electric device connected to the piezoelectric vibrator rectangular plate. A piezoelectric transformer including an output-side electrode provided on the piezoelectric vibrator rectangular plate for extracting a dynamic signal, and utilizing a resonance mode in a longitudinal direction of the piezoelectric vibrator rectangular plate, Conductive first and second supports are attached to the vibration nodes on the side surface, and the first support is a side surface opposite to the surface of the first support tool in contact with the side surface. Has a first protrusion and is electrically connected to the input-side electrode, and the second support is provided on a side opposite to a side of the second support that is in contact with the side. It has two protrusions and is electrically connected to the output side electrode. The first and second projections, respectively located at a node of the vibration, and the piezoelectric transformer, characterized in that it is supported by the resin having flexibility. 2. The piezoelectric transformer according to claim 1, wherein lead wires are connected to the first and second protrusions in the resin, respectively.