JP2002344040A - Mounted piezoelectric transformer and mounting method therefor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric transformer, mounted so as to be capable of dealing with a high power and operating with high efficiency. SOLUTION: A piezoelectric transformer mounting body is composed of a piezoelectric transformer, equipped with an input electrode and an output electrode, a support which is formed of elastic material to support the piezoelectric transformer at the nodes of vibrations, a package housing the piezoelectric transformer and the support, an electrode terminal whose one end is connected to the package and other end is brought into electrical contact with the input electrode of the piezoelectric transformer, and a conductive connector electrically connected to the output electrode of the piezoelectric transformer. The electrode terminal is fixed to the input electrode of the piezoelectric transformer by conductive adhesive material.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mounted piezoelectric transformer used in a step-up / step-down circuit, and a mounting method thereof.

[0002]

2. Description of the Related Art A piezoelectric transformer used in a booster circuit of a liquid crystal display device or the like has a Rosen type structure as shown in FIG. This piezoelectric transformer 140
The input electrode 14 is provided on the left half of the upper and lower surfaces of the rectangular plate 144.
1 and 142, and an output electrode 143 on the upper surface of the end of the rectangular plate 144 in the longitudinal direction. The rectangular plate 144 is polarized in the thickness direction between the input electrodes 141 and 142, and the input electrode 1
Polarized in the length direction between the output electrodes 41 and 142 and the output electrode 143.

In the piezoelectric transformer 140, when an AC voltage is applied between the input electrodes 141 and 142, mechanical vibration occurs in the length direction, and the mechanical vibration is converted into a high voltage by a piezoelectric effect. . The converted high voltage is taken out as an output voltage between the output electrode 143 and one input electrode.

As a method for mounting the above-mentioned piezoelectric transformer having a Rosen-type structure, a method using conductive rubber has been put to practical use. FIG. 16 is a top view of a mounting structure using conductive rubber. Here, the Rosen-type piezoelectric transformer 150 oscillates in, for example, a λ / 2 mode in which the center in the length direction of the rectangular plate is a node of oscillation. In FIG.
The piezoelectric transformer 150 is stored in packages 158 and 159. Here, the conductive rubbers 151, 152, 153 attached to the packages 158, 159, and
Reference numeral 154 contacts the piezoelectric transformer 150.

In FIG. 16, conductive rubbers 151 and 15 are provided.
Reference numeral 2 contacts the center side surface in the length direction of the piezoelectric transformer 150. In addition, the conductive rubbers 153 and 154 contact the side surface of the end of the piezoelectric transformer 150 where the output electrode is formed. In this mounting structure, the conductive rubber 151,
152 is pressurized by the packages 158 and 159 and supports the piezoelectric transformer 150.

Further, these conductive rubbers are respectively connected to input electrodes and output electrodes formed on the side surfaces (connected from the upper surface and the lower surface) of the piezoelectric transformer 150, and are electrically conducted. Then, the conductive rubber 151, 152,
Further, the metal terminals 155, 156, and 157 are attached to the 153 and the electrodes are pulled out, whereby the electrodes can be taken out.

In the above mounting structure, the conductive rubber is
At the same time as being electrically connected to the electrodes of the piezoelectric transformer, the elasticity thereof allows the piezoelectric transformer to be supported without inhibiting vibration.

[0008]

However, when a large-sized piezoelectric transformer is used for reasons such as an increase in the size of a liquid crystal panel, a larger amount of current must be passed to the input electrode of the piezoelectric transformer. The resistance of the rubber cannot be ignored. Therefore, the conventional mounting structure has a problem that the efficiency of the piezoelectric transformer is reduced.

Another problem is that when the vibration speed of the piezoelectric transformer increases due to an increase in the power handled by the piezoelectric transformer, the connection between the output electrode of the piezoelectric transformer and the output electrode take-out portion made of conductive rubber becomes unstable. Occurs. On the other hand, if the connection is strengthened, there arises a problem that the output electrode take-out portion hinders the vibration of the piezoelectric transformer.

Further, it is desired that the piezoelectric transformer be supported in the package without hindering the vibration of the piezoelectric transformer.

An object of the present invention is to provide a piezoelectric transformer mounted so that it can handle large power and can be driven efficiently.

[0012]

According to a first aspect of the present invention, there is provided a piezoelectric transformer mounted body comprising: a piezoelectric transformer having input electrodes and output electrodes; and an elastic body supporting the piezoelectric transformer at a vibration node. And a package for storing the piezoelectric transformer and the support unit, and an electrode having one end fixed to the package and the other end in electrical contact with an input electrode of the piezoelectric transformer. Terminals and
A conductive connecting portion electrically connected to the output electrode of the piezoelectric transformer. Further, the electrode terminal is fixed to an input electrode of the piezoelectric transformer by a conductive adhesive material.

According to a second aspect of the present invention, there is provided a piezoelectric transformer mounted body comprising: a piezoelectric transformer provided with an input electrode and an output electrode; a support portion made of an elastic body supporting the piezoelectric transformer at a node of vibration; A package for storing the piezoelectric transformer and the supporting portion, a conductive connecting portion electrically connected to an input electrode of the piezoelectric transformer, one end fixed to the package, and the other end connected to the output electrode. And an electrode terminal electrically connected to the terminal. The other end of the electrode terminal is in contact with the output electrode of the piezoelectric transformer via a conductive adhesive material.

According to a third aspect of the present invention, there is provided a piezoelectric transformer mounted body comprising: a piezoelectric transformer provided with an input electrode and an output electrode; a support portion made of an elastic body supporting the piezoelectric transformer at a node of vibration; A package for storing the piezoelectric transformer and the support portion, a conductive connection portion electrically connected to an input electrode of the piezoelectric transformer, one end fixed to the package, and the other end And an electrode terminal made of metal foil that is in electrical contact with the output electrode of the piezoelectric transformer.

For example, in the above-described piezoelectric transformer mounted body, the shape of the electrode terminal is U-shaped.

For example, in the piezoelectric transformer mounted body, the electrode terminals have a branched structure.

A mounting method according to the present invention is a method of connecting the electrode terminals and the output electrodes in a piezoelectric transformer mounted body using the electrode terminals made of the metal foil, wherein the bonding of the electrode terminals is performed. Contacting the surface with the output electrode via a conductive adhesive material, and inserting an elastic body wider than the inner size of the electrode terminal between the output electrode and the external terminal Fixing the adhesion of the electrode terminals, thermally curing the conductive adhesive material, and removing the elastic body.

For example, the elastic body is made of silicon rubber.

[0019]

BRIEF DESCRIPTION OF THE DRAWINGS FIG.
An embodiment according to the present invention will be described. (First Embodiment) FIG. 1 is a schematic top view of a mounted piezoelectric transformer according to a first embodiment. FIG.
2, the rectangular piezoelectric transformer 10 is stored in a box-shaped package 11 having a rectangular bottom surface. The piezoelectric transformer 10 is located substantially at the center of the package 11, and the bottom of the piezoelectric transformer 10 is supported by the support 12. The piezoelectric transformer 10 is made of a piezoelectric material, and has an input electrode at the center in the length direction and output electrodes at two ends in the length direction. Further, lead wires 15 and 16 for extracting output electrodes to external terminals 19 and 20 are soldered to both ends in the length direction.

For example, if the piezoelectric transformer 10 is driven in the λ / 2 vibration mode, and there is a vibration node at the center, FIG.
As shown in (1), the support portion 12 made of an elastic body is positioned so as to be in contact with the center of the piezoelectric transformer 10. Since the support portion 12 is an elastic body and is located at a node of vibration, the piezoelectric transformer 10 can be supported without hindering the vibration of the piezoelectric transformer 10.

In the mounted piezoelectric transformer according to the present embodiment, metal terminals 13 and 14 for taking out the input electrodes are connected to the input electrodes at the center of the piezoelectric transformer 10 by using conductive adhesives 17 and 18. Is done. Hereinafter, the input electrode extraction portion will be described.

FIG. 2 is a schematic partial cross-sectional view of the center portion of the mounted piezoelectric transformer 10, that is, the broken lines 200 and 202 in FIG. The piezoelectric transformer 10 is stored in a box-shaped package 11, and the bottom thereof is supported by a support 12. In FIG. 2, for example, the metal terminal 13 has an elongated shape, and one end is fixed to the outside of the package 11, and the other end is curved inside the package 11. Then, the most curved portion of the metal terminal comes into direct contact with the input electrode formed on the side surface of the piezoelectric transformer 10 (which may be connected from the upper surface and the lower surface). Metal terminal 13
In order to stabilize the contact, the metal terminal 13 is, for example, 0.1 mm.
As shown in the drawing, a conductive adhesive 18 is injected into a contact portion between the input electrode of the piezoelectric transformer 10 and the metal terminal 13 having a thickness of about 3 mm.

In the piezoelectric transformer of the present embodiment, a metal terminal is used for taking out an input electrode of the piezoelectric transformer,
Further, the metal terminal is in direct contact with the input electrode. Therefore, the conduction resistance at the portion where the input electrode is taken out is reduced as compared with the case where the conventional conductive rubber is used. In addition, the input electrode extraction portion does not hinder the driving of the piezoelectric transformer.

Note that, instead of the structure shown in FIG. 2, as shown in FIG. 3, the tip of the curved metal terminal 13 may be brought into direct contact with the lower side of the piezoelectric transformer 10. In this case, the same effect as in the case of the contact shown in FIG. 2 can be obtained.

Further, the curved one end of the metal terminal 13 may have a hole in the center, and the hole may be in contact with the input electrode.
FIG. 4 shows a structure in which a portion of the metal terminal 13 that curves inside the package is deformed, and has one end having a hole in the center and two ends formed on both sides thereof so as to face each other. In this case, one end having a hole in the center is in contact with the input electrode of the piezoelectric transformer 10 (FIG. 5), and two ends facing each other are attached to the package 11. Metal terminal 13
When the electrode and the input electrode are fixed, the conductive adhesive material 18
Is injected into the structure surrounded by the three sides. The conductive adhesive material 18 contacts the input electrode through a hole formed in one terminal, and bonds the metal terminal 13 and the input electrode of the piezoelectric transformer 10. In this case, the same effect as in the case of the contact shown in FIG. 2 can be obtained.

In the mounted piezoelectric transformer of the present embodiment, the supporting portion of the piezoelectric transformer and the input electrode take-out portion are separated from each other, and each of them has the above-described structure, so that the piezoelectric transformer can be securely fixed without obstructing vibration. And a reduction in the resistance of the input electrode extraction portion can be achieved. Also,
Because the support part and the input electrode extraction part are separated,
Even when the position of the input electrode and the node of vibration are different in the piezoelectric transformer, the support portion can support the piezoelectric transformer at the node of vibration.

(Second Embodiment) FIG. 6 is a schematic top view of a mounted piezoelectric transformer according to a second embodiment. 6, the same structures as those of the piezoelectric transformer according to the first embodiment are denoted by the same reference numerals as in FIG. The piezoelectric transformer according to the present embodiment differs from the piezoelectric transformer according to the first embodiment in the structure of the output electrode extraction portion. The output electrodes at the ends of the piezoelectric transformer 10 are in contact with the conductive rubbers 50, 51, 52, 53 via the conductive adhesives 54, 55, 56, and 57. The conductive rubbers 50 and 51 are connected to external terminals 58 and 59 attached to the package 11. Hereinafter, the output electrode extraction portion will be described.

FIG. 7 is a schematic partial cross-sectional view taken along broken lines 204 and 206 in FIG. 6 (the same applies to broken lines 208 and 210). In FIG. 7, the piezoelectric transformer 10
Are stored in a box-shaped package 11. The external terminals 58 attached to the package 11 are electrically conductive rubber 5
0 and the conductive adhesive 54, and comes into contact with an output electrode formed on the lower side surface of the piezoelectric transformer 10 (which may be connected from the upper surface or the end surface). Here, the conductive rubber 5
0 is pressed by the package 11 at a predetermined compression rate.

In the piezoelectric transformer of the present embodiment, the conductive rubber 50 is connected to the output electrode of the piezoelectric transformer 10 via the conductive adhesive 54. As compared with the conventional connection without the conductive adhesive, the conductive rubber 50 is more flexibly deformed (FIG. 8), and can follow the faster vibration of the piezoelectric transformer 10 while keeping the connection stable. Therefore, a mounting structure that efficiently drives the piezoelectric transformer without hindering the vibration of the piezoelectric transformer can be realized.

In the mounted piezoelectric transformer of the present embodiment, the structures of the input electrode take-out portion and the support portion are the same as those of the first embodiment. Therefore,
The same effect as in the first embodiment can be obtained.

(Third Embodiment) FIG. 9 is a schematic top view of a mounted piezoelectric transformer according to a third embodiment. In FIG. 9, a rectangular piezoelectric transformer 80 is
It is stored in a box-shaped package 81 having a rectangular bottom surface. The piezoelectric transformer 80 is located substantially at the center of the package 81, and the bottom of the piezoelectric transformer 80 is supported by the support 82. The piezoelectric transformer 80 is made of a piezoelectric material, and has an input electrode on the side surface at the center in the length direction (may be connected from the upper surface and the lower surface). Metal terminals 83 and 84 are fixed to the input electrodes of the piezoelectric transformer 80 by a conductive adhesive, similarly to the structure described in the first embodiment.

For example, if the piezoelectric transformer 80 is driven in the λ / 2 vibration mode, and there is a vibration node at the center, FIG.
As shown in (2), the support portion 82 made of an elastic body is positioned so as to be in contact with the center of the piezoelectric transformer 80. Since the supporting portion 82 is an elastic body and is located at a node of vibration, the vibration of the piezoelectric transformer 80 is not hindered.
The piezoelectric transformer 80 can be supported.

The piezoelectric transformer 80 of this embodiment has output electrodes on two end faces in the length direction. Package 81
, An external terminal is formed at a position opposing the end face of the piezoelectric transformer 80 where the output electrode is formed. Extraction of the output electrode of the piezoelectric transformer 80 to the outside
This is performed by connecting the output electrodes and the external terminals 87 and 88 of the package 81 via U-shaped structures 85 and 86 made of metal. This U-shaped structure is shown in FIG. In FIG. 10, for example, one end face 90 is in contact with the output electrode of the piezoelectric transformer, and the other end face 91 is attached to an external terminal of the package. The end face 90 and the output electrode are fixed by a conductive adhesive. When the piezoelectric transformer 80 expands and contracts in the longitudinal direction, the end face 90 side of the U-shaped structure moves following the vibration. By adjusting the thickness of the metal plate, the U-shaped metal plate can connect the output electrode to the external terminal while minimizing vibration inhibition for the piezoelectric transformer 80.

In the piezoelectric transformer 80 of the present embodiment, a U-shaped thin metal plate (metal foil) 8 is used as an output electrode.
5, 86. The metal foil 8
5 and 86, only one end face moves following the piezoelectric transformer 80. Therefore, even if the vibration speed of the piezoelectric transformer increases, it is possible to realize a portion where the output electrode is taken out, where the influence of vibration inhibition on the piezoelectric transformer is small while the connection is kept stable.

In the mounted piezoelectric transformer of the present embodiment, the structures of the input electrode take-out portion and the supporting portion are the same as those of the first embodiment. Therefore,
The same effect as in the first embodiment can be obtained.

(Fourth Embodiment) FIG. 11 is a schematic top view of a mounted piezoelectric transformer according to a fourth embodiment. In FIG. 11, a rectangular piezoelectric transformer 10
0 is stored by a package 101 having a rectangular bottom surface. The piezoelectric transformer 100 includes a package 1
1, the bottom of the piezoelectric transformer 100 is supported by the support 102. Piezoelectric transformer 10
Numeral 0 is made of a piezoelectric material, and has an input electrode on the side surface at the center in the length direction (may be connected from the upper surface and the lower surface). As with the structure described in the first embodiment, the input electrodes of the piezoelectric transformer 100
4 is fixed by a conductive adhesive.

For example, if the piezoelectric transformer 100 is driven in the λ / 2 vibration mode and a vibration node exists at the center, the support 102 made of an elastic body is positioned so as to be in contact with the center of the piezoelectric transformer 100. You. Since the support portion 102 is an elastic body and is located at a node of vibration, the piezoelectric transformer 100 can be supported without hindering the vibration of the piezoelectric transformer 100.

The piezoelectric transformer 100 of the present embodiment has output electrodes on two end faces in the length direction. The output electrodes are taken out of the metal foils 105, 10 and 10 each having a cutout structure as shown in FIG.
6, the output electrode and the external terminal 1 of the package 101.
07 and 108 are connected. One short end face 111 of the foot contacts the output electrode of the piezoelectric transformer,
The other long end face 110 is attached to an external terminal of the package. As shown in FIG. 11, the external terminals of the package are formed within a range where the end face 110 can be attached. The end face 111 and the output electrode are fixed by a conductive adhesive. When the piezoelectric transformer 100 expands and contracts in the length direction, the end surface 111 side of the metal foil moves following the vibration. By adjusting the thickness of the metal foil, vibration inhibition of the piezoelectric transformer 100 can be minimized, and the output electrode and the external terminals 107 and 108 can be connected.

In the piezoelectric transformer of the present embodiment, the output electrodes are taken out by the branched metal foils 105 and 106. Also, only one end surface of the metal foils 105 and 106 moves following the piezoelectric transformer 100. Therefore, even if the vibration speed of the piezoelectric transformer increases, it is possible to realize a portion where the output electrode is taken out, where the influence of vibration inhibition on the piezoelectric transformer is small while maintaining the stable connection.

In the mounted piezoelectric transformer of the present embodiment, the structures of the input electrode extraction portion and the support portion are the same as those of the first embodiment. Therefore,
The same effect as in the first embodiment can be obtained.

Next, a method of bonding the metal foil and the output electrode of the piezoelectric transformer using a conductive adhesive in the mounted piezoelectric transformers of the third and fourth embodiments will be described. FIG. 13 is a top view schematically illustrating a portion where an output electrode is taken out of the mounted piezoelectric transformer according to the third embodiment. First, a conductive adhesive is applied to the bonding surface of the U-shaped metal foil 86 and / or the end surface of the piezoelectric transformer 80 having the output electrode, and the bonding is performed. Next, an elastic body 120 such as a silicone rubber sheet is
As shown in FIG. 3, it is inserted inside the metal foil 86 to fix the adhesive portion. This silicon rubber sheet 120 is made of metal foil 8
For example, it has a width T larger than the inner dimension t of No. 6 by about 0.1 to 0.2 mm. Then, with the metal foil 86 fixed, the entire package is left in a hot atmosphere to thermally cure the conductive adhesive. Finally, after a predetermined time,
The entire package is left in a natural atmosphere, and the silicone rubber sheet 120 is removed. The above steps are schematically illustrated in FIG.
Shown in

In this bonding method, in order to bond the metal foil, a silicon rubber sheet slightly wider than the inner size of the metal foil is inserted inside the metal foil. Therefore, the adhesive portion can be easily pressed by the elasticity of the silicone rubber sheet. Further, the thin metal foil can be easily bonded without the silicon rubber sheet coming into contact with the adhesive. Furthermore, since the size of the silicone rubber sheet can be specified according to the area of the bonding portion, bonding to an arbitrary bonding area is possible. From the above, bonding using a conductive adhesive between the metal foil and the output electrode of the piezoelectric transformer can be easily performed.

[0043]

According to the present invention, it is possible to provide a piezoelectric transformer mounted so that it can handle a large amount of electric power and can be driven efficiently.

[Brief description of the drawings]

FIG. 1 is a diagram showing a mounted piezoelectric transformer according to a first embodiment.

FIG. 2 is a cross-sectional view showing a portion where an input electrode is taken out of the piezoelectric transformer of FIG. 1;

FIG. 3 is a sectional view showing a modification of the input electrode take-out portion of FIG. 2;

FIG. 4 is a diagram showing metal terminals used in another modification of the input electrode extraction portion of FIG. 2;

FIG. 5 is a sectional view showing another modification of the input electrode take-out portion of FIG. 2;

FIG. 6 is a diagram showing a mounted piezoelectric transformer according to the second embodiment.

FIG. 7 is a sectional view showing a portion where the output electrode of the piezoelectric transformer of FIG. 6 is taken out.

FIG. 8 is a diagram showing a state of the output electrode take-out portion of FIG. 7 at the time of vibration.

FIG. 9 is a diagram illustrating a mounted piezoelectric transformer according to a third embodiment.

FIG. 10 is a view showing a metal foil used in the mounting structure according to the third embodiment.

FIG. 11 is a diagram showing a mounted piezoelectric transformer according to a fourth embodiment.

FIG. 12 is a diagram showing a metal foil used in the mounting structure according to the fourth embodiment.

FIG. 13 is a diagram illustrating a method of bonding a metal foil and an output electrode in the mounting structure according to the third embodiment.

FIG. 14 is a process chart showing a method of bonding a metal foil and an output electrode in the mounting structure according to the third embodiment.

FIG. 15 is a schematic view of a conventional piezoelectric transformer.

FIG. 16 is a top view showing a conventional mounted piezoelectric transformer.

[Explanation of symbols]

 10, 80, 100 Piezoelectric transformer 11, 81, 101 Package 12, 82, 102 Supporting part 13, 14, 83, 84, 103, 104 Metal terminal 17, 18 Conductive adhesive 50, 51, 52, 53 Conductive rubber 85, 86, 105, 106 Metal foil 87, 88, 107, 108 External terminal 120 Silicon rubber sheet

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Katsushi Takeda 1006 Kazuma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd.

Claims (7)

[Claims] A piezoelectric transformer provided with an input electrode and an output electrode; a support portion made of an elastic body that supports the piezoelectric transformer at a node of vibration; a package storing the piezoelectric transformer and the support portion; One end is fixed to the package, and the other end is electrically connected to the input electrode of the piezoelectric transformer. The conductive terminal is electrically connected to the output electrode of the piezoelectric transformer. Wherein the electrode terminal is fixed to an input electrode of the piezoelectric transformer with a conductive adhesive material. 2. A piezoelectric transformer provided with an input electrode and an output electrode; a support portion made of an elastic body that supports the piezoelectric transformer at a node of vibration; a package that stores the piezoelectric transformer and the support portion; A conductive connection portion electrically connected to an input electrode of the piezoelectric transformer; and an electrode terminal having one end fixed to the package and the other end electrically connected to an output electrode. A piezoelectric transformer package in which the other end of the terminal is in contact with the output electrode of the piezoelectric transformer via a conductive adhesive material. 3. A piezoelectric transformer provided with an input electrode and an output electrode, a support portion made of an elastic body supporting the piezoelectric transformer at a node of vibration, a package storing the piezoelectric transformer and the support portion, A conductive connecting portion electrically connected to an input electrode of the piezoelectric transformer; and a metal foil having one end fixed to the package and the other end electrically connected to an output electrode of the piezoelectric transformer. A piezoelectric transformer mounting body consisting of electrode terminals. 4. The piezoelectric transformer package according to claim 3, wherein the electrode terminals have a U-shaped structure. 5. The piezoelectric transformer package according to claim 3, wherein the electrode terminal has a branched structure. 6. The connection method between the electrode terminal and the output electrode of the piezoelectric transformer in the piezoelectric transformer mounted body according to claim 4 and 5, wherein the bonding surface of the electrode terminal and the output electrode are connected to each other. Contacting via a conductive adhesive material, and inserting an elastic body having a width larger than the inner size of the electrode terminal between the output electrode and the external terminal to fix the adhesion of the electrode terminal. A method comprising: thermally curing the conductive adhesive material; and removing the elastic body. 7. The method according to claim 6, wherein said elastic body is made of silicone rubber.