JPH08228031A - Piezoelectric transformer and supporting device thereof - Google Patents

Abstract

PURPOSE: To check the output decline in a piezoelectric transformer while increasing the Q value by a method wherein recessions are provided on the joint parts of vibration at both ends of a piezoelectric ceramic plate in the direction orthogonal to the vibrational direction so as to insert the front ends of supporting members by fixing the other ends of the supporting members to frame bodies. CONSTITUTION: An input electrode 21 is formed on front and back faces in the long direction of a piezoelectric ceramic plate 20. On the other hand, an output electrode 22 is formed on the end face in the opposite side of the end face whereon this input electrode 21 is formed furthermore, recessions are formed on the end face in the orthogonal direction to the vibrational direction of the piezoelectric ceramic plate 20 so as to insert the front ends of the supporting members 24 made of an elastomer such as hard rubber, etc., into these recessions. At this time, the other ends of the supporting members 24 are fixed to the frame bodies 25. In such a constitution, plurality of electrodes 26 are formed on the frame bodies 25 to be connected to the input electrode 21 and the output electrode 22. Through these procedures, the vibrational attenuation can be minimized thereby enabling the high Q value to be gained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer and its supporting device, and more particularly to a piezoelectric transformer and its supporting device capable of obtaining a high output by reducing the damping of vibration generated in a piezoelectric ceramic plate. It is about.

[0002]

2. Description of the Related Art Utilization of a piezoelectric transformer has been conventionally studied to obtain a high voltage for driving a transformer. Recently, a piezoelectric transformer has attracted attention as an inverter transformer for driving a backlight of a liquid crystal display device.

Some piezoelectric transformers use a single crystal, but generally one using a piezoelectric ceramic plate. In many cases, an input electrode is provided on the front and back surfaces of one end of a rectangular piezoelectric ceramic plate and an output electrode is provided on the opposite end surface for driving. The input voltage is converted into vibration of the piezoelectric ceramic plate, and this vibration is converted into an output voltage to obtain a high voltage.

The vibrating piezoelectric ceramic plate must be supported as a matter of course, but a structure for holding the piezoelectric ceramic plate at or near the node of vibration is adopted. Normally, FIG.
As shown in FIG. 2, a structure is adopted in which the node portion is pressed from above and below by the elastic body 33 such as a rubber damper according to the vibration mode (resonance mode) of the piezoelectric ceramic plate 30.

[0005]

In the supporting structure using the rubber damper or the like as described above, the vibration of the piezoelectric ceramic plate is attenuated due to the width and the pressing pressure. As a result, the Q of the piezoelectric transformer decreases and it becomes impossible to obtain a predetermined output.

If the pressing method is loose, there is a problem that the position of the piezoelectric transformer is displaced due to vibration or shock.

According to the present invention, a high Q can be obtained without lowering the output of the piezoelectric transformer, and the piezoelectric ceramic plate is reliably supported to provide a piezoelectric transformer excellent in stability and reliability. Is.

[0008]

The present invention solves the above-mentioned problems by supporting the side surfaces of the vibration nodes of a piezoelectric ceramic plate serving as a piezoelectric transformer.

That is, in a piezoelectric transformer having input electrodes on the front and back surfaces of a piezoelectric ceramic plate and output electrodes on the end faces in the vibration direction, recesses are provided at the nodes of vibration on both end faces in the direction orthogonal to the vibration direction. It has a special feature.

More specifically, in a supporting device for a piezoelectric transformer having an input electrode on the front and back surfaces of a piezoelectric ceramic plate and an output electrode on the end surface in the vibration direction, the vibration of both end surfaces in the direction orthogonal to the vibration direction The node portion is provided with a concave portion, and the tip of the supporting member made of an elastic body is inserted into the concave portion, and the other end of the supporting member is fixed to a frame body made of an insulator
It is characterized in that the electrode film formed on the frame is connected to the electrodes of the piezoelectric ceramic plate.

[0011]

Since the piezoelectric ceramic plate can be supported without fail at the nodes of the resonance mode and the influence on the vibration can be minimized, the vibration damping can be reduced and a high Q piezoelectric transformer can be obtained. it can. Moreover, since they are engaged, a piezoelectric transformer excellent in stability and reliability can be realized.

[0012]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an embodiment of the present invention.
It shows a portion of a piezoelectric ceramic plate of a piezoelectric transformer. The piezoelectric ceramic plate 10 has a size of 50 mm × 10 mm and a thickness of about 2 mm, and is polarized. Input electrodes 11 are formed on the front and back surfaces on the surface of the piezoelectric ceramic plate 10 at one end side in the longitudinal direction. An output electrode 12 is formed on the end face opposite to the end face on which the input electrode 11 is formed. This constitutes a so-called Rosen type piezoelectric transformer.

In the piezoelectric transformer according to the present invention, the concave portion 13 is formed on the end surface of the piezoelectric ceramic plate 10 in the direction orthogonal to the vibration direction. The recess 13 is formed as a blind hole having a diameter such that an elastic support member can be inserted,
The thickness of the piezoelectric ceramic plate 10 is about 2 mm, so 0.5 m
It is good to set m to 1.0 mm. Also, the shape may be matched with the shape of the tip of the support member. If the depth is too large, the strength of the piezoelectric ceramic plate will also be a problem, so it is desirable to keep it to about 0.5 mm.

FIG. 2 is a perspective view showing a structure for supporting the piezoelectric ceramic plate. An input electrode 21 and an output electrode 22 are formed on the piezoelectric ceramic plate 20 as described above. Then, the tip of the support member 24 made of an elastic body such as hard rubber is inserted into the concave portion formed on the side surface. In this example, the tip of the support member 24 is inserted in contact with the recesses formed at four locations on both sides.

The other end of the support member 24 is fixed to the frame body 25. This fixing method can be done by any method, but the frame
A method such as inserting into the hole formed in 25 is preferable. This frame 25
Although it may be metal, the electrode 26 can be formed on the surface of the insulating material such as resin. It is possible to form a plurality of electrodes 26 on the frame 25 and connect the two input electrodes 21 and the output electrodes 22 by wire bonding or the like to connect the electrodes of the frame 25 and the conductor wiring of the wiring board.

The two frames 25 are connected by a threaded metal rod 27, and the positional relationship (distance) between them is determined. The male screw of the metal rod 27 is screwed into the female screw cut into the frame 25 to connect it, and this male screw is rotated to adjust the interval of the frame 25, whereby the piezoelectric ceramic plate of the support member 24 is adjusted.
The state of pressing 20 can be adjusted.

The thickness of the frame 25 is slightly larger than the thickness of the piezoelectric ceramic plate 20. Thereby, even if the frame body 25 is mounted and fixed on the wiring board, the vibration generated in the piezoelectric ceramic plate 20 is not affected. Therefore, the total thickness can be about 3 mm, and a thin piezoelectric transformer can be realized.

The concave portion formed on the piezoelectric ceramic plate is formed on the side surface of the node according to the vibration mode. The shape and depth may be determined according to the shape of the tip of the support member as described above, but the shape is not limited to a round shape or a square shape, and may be an X shape. Further, it is also possible to form an electrode on the surface of the frame body by using a metal through an insulating layer.

[0020]

According to the present invention, it is possible to obtain a piezoelectric transformer capable of realizing high Q while minimizing vibration damping. Moreover, since stable support is possible, a piezoelectric transformer excellent in terms of reliability can be obtained.

Further, since the side surface of the piezoelectric ceramic plate is supported, the thickness of the entire device can be suppressed to a dimension almost the same as the thickness of the piezoelectric ceramic plate, and a thin piezoelectric transformer can be realized.

Further, depending on the support structure, there is an advantage that adjustment is possible and surface mounting on the wiring board is also possible.

[Brief description of drawings]

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

FIG. 2 is a perspective view showing an embodiment of a piezoelectric transformer support device of the present invention.

FIG. 3 is a front view of a conventional piezoelectric transformer support structure.

[Explanation of symbols]

 10, 20: Piezoelectric ceramic plate 13: Recess 24: Support member 25: Frame

Claims (5)

[Claims] 1. A piezoelectric transformer having an input electrode on the front and back surfaces of a piezoelectric ceramic plate and an output electrode on the end face in the vibration direction, wherein recesses are provided at the nodes of vibration on both end faces in the direction orthogonal to the vibration direction. Piezoelectric transformer characterized by that. 2. A piezoelectric transformer having an input electrode on the front and back surfaces of a piezoelectric ceramic plate and an output electrode on the end surface in the vibration direction, and a recess at the node of vibration on both end surfaces in the direction orthogonal to the vibration direction. A piezoelectric transformer, wherein a tip of a supporting member made of an elastic body is inserted into the recess. 3. The support device for a piezoelectric transformer according to claim 2, wherein the other end of the support member is fixed to the frame body. 4. The support device for a piezoelectric transformer according to claim 3, wherein the frame body is made of an insulator, and an electrode film is formed on the surface of the frame body, and the frame is connected to the electrode formed on the piezoelectric ceramic plate. 5. The frame comprises two parts connected to each other,
The support device for a piezoelectric transformer according to claim 3, further comprising a mechanism for adjusting the distance.