JP2000091660A - Piezoelectric transformer and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] In a piezoelectric transformer, a creepage distance between primary and secondary external electrodes is ensured, and the size and efficiency of the transformer are reduced. SOLUTION: A plurality of elements 11 in which a green sheet made of a piezoelectric material, for example, PZT, and internal electrodes are integrally fired are laminated in the length direction and thermocompression-bonded. Input external electrodes 12 for connecting the internal electrodes of the stacked elements 11 in parallel
a, 12b and output-side external electrodes 12c, 12d are formed of the same electrode paste as the internal electrodes. Between adjacent external electrodes 12a and 12c and between external electrodes 12a and 12c.
Insulators 13a and 13b such as PZT are formed by thermocompression bonding, printing or coating between each half surface of c, between the adjacent external electrodes 12b and 12d, and each half surface of the external electrodes 12b and 12d. Between the external electrodes 12a and 12c, the external electrodes 12b and
The space between 12d is covered with an insulator, and each creepage distance is infinite, and functions as a good insulating transformer.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer that uses a piezoelectric material such as a piezoelectric ceramic to transmit power and convert voltage using mechanical vibration, and a method of manufacturing the same.

[0002]

2. Description of the Related Art In recent years, further miniaturization of electronic equipment has been demanded. As a method of solving this problem, attention has been paid to using a piezoelectric transformer as a transformer which is a main component of the converter. Piezoelectric transformer is a device that performs power transmission and voltage conversion using mechanical vibration,
It has features superior to conventional electromagnetic transformers, such as high insulation, nonflammability, and high power density.

In particular, a length-longitudinal-vibration type piezoelectric transformer has features such as high power density and is suitable for AC-DC converters. 3 and 4 show the structure of the lengthwise longitudinal vibration type piezoelectric transformer. 3 and 4, thin layers of piezoelectric ceramics 2, 2, 2,... Reference numerals 3a to 3d denote external electrodes formed on the transformer surface (longitudinal side surface of the case 1) for connecting the internal electrodes 4, 4, 4,... In parallel.

The thickness and the number of layers of the piezoelectric ceramics 2, 2, 2,... Are changed at an input portion (primary side) and an output portion (secondary side). Impedance and input DC100V ~ 260V
Output 16V, for example.

FIG. 4 shows the displacement in the longitudinal direction of the longitudinal vibration type piezoelectric transformer.

[0006]

In the conventional lengthwise longitudinal vibration type piezoelectric transformer described above, the input side external electrodes 3a, 3b
And the creepage distance between the external electrodes 3c and 3d on the output side are too short,
For example, it has been difficult to fall within the standard of 8 mm creepage distance as an insulation type transformer specified by international safety standards and the like.

Further, there is a problem in that the creepage distance is increased to increase the creepage distance and the size of the piezoelectric transformer is increased.

The present invention has been made in view of the above points, and an object thereof is to secure a creepage distance between external electrodes on a primary side and a secondary side, and to reduce the size and efficiency of a transformer. It is an object of the present invention to provide a piezoelectric transformer and a method of manufacturing the same.

[0009]

(1) A piezoelectric transformer according to the present invention is provided with a laminated body formed by laminating a plurality of elements in which a piezoelectric material and an internal electrode are integrated, and coated with a material having the same composition as the piezoelectric material. And an external electrode for connecting the plurality of internal electrodes in parallel.
A secondary electrode and a secondary electrode are formed at a predetermined distance from each other, and a material having the same composition as the piezoelectric material is thermocompression-bonded to the primary electrode and the secondary electrode. A primary electrode and a secondary electrode are formed at a predetermined distance from each other, and a material having the same composition as the piezoelectric material is printed or coated on the primary electrode and the secondary electrode,
The external electrode has a lead wire connected to the exposed vibrating node.

[0010] The method for manufacturing a piezoelectric transformer according to the present invention includes:
A step of fabricating an element by integrating a piezoelectric material and an internal electrode, a step of laminating a plurality of the produced elements and thermocompression bonding, and a step of coating with a material having the same composition as the piezoelectric material; Forming an external electrode for connecting the internal electrodes in parallel, wherein the step of forming the external electrode comprises forming an external electrode on the plurality of laminated and thermocompressed laminates, The step of forming the external electrode is performed by thermocompression bonding a material having the same composition as the piezoelectric material to the external electrode. A step of printing or applying a material having the same composition as the piezoelectric material to the external electrode, exposing a vibrating node portion of the external electrode, and taking a lead wire from the vibrating node portion. Is characterized by To have.

(2) In the first to sixth aspects of the present invention, since the external electrode is coated with a material having the same composition as the piezoelectric material, that is, an insulating material, the primary external electrode and the secondary external electrode are covered. The creepage distance between is infinite. Therefore, even when the distance between the primary side external electrode and the secondary side external electrode is extremely short, the creepage distance is ensured.
High efficiency can be achieved.

(3) In the invention according to claims 7 to 12, since the element of the piezoelectric transformer is manufactured by integrating the piezoelectric material and the internal electrode, when the external electrode is formed, the piezoelectric material is insulated. The creepage distance between the primary side external electrode and the secondary side external electrode is ensured by the property, so that a small-sized piezoelectric transformer having a secured creepage distance can be manufactured.

[0013]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows the structure of the piezoelectric transformer of the present invention. In FIG. 1, reference numeral 11 denotes an element in which a green sheet made of a piezoelectric material, for example, PZT, and internal electrodes are integrally fired, and a plurality of the elements 11 are laminated and thermocompression-bonded in the longitudinal direction.

Reference numerals 12a and 12b denote the stacked element 1
Are input-side (primary-side) external electrodes for connecting the internal electrodes of 1, 11, 11,... In parallel, and 12c, 12d connect the internal electrodes of the stacked elements 11, 11, 11,. Output (secondary side) external electrodes for performing the operation.

Reference numeral 13a denotes adjacent external electrodes 12a and 12c.
Thermocompression bonding between the space and each part of the external electrodes 12a and 12c.
An insulator formed by printing or coating. Also one
Similarly, 3b is an insulator formed between the adjacent external electrodes 12b and 12d and on each part of the external electrodes 12b and 12d by thermocompression bonding, printing or coating.

The insulators 13a and 13b are made of PZT having the same composition as the green sheet of the element 11 constituting the piezoelectric transformer, and have a sufficient insulation performance with a resistivity of 10 ¹⁰ Ωcm or more. Therefore, the external electrodes 12a, 12c
And the outer electrodes 12b and 12d are covered with an insulator, the creepage distances are infinite, and function as a good insulating transformer. Therefore, the external electrodes 12a, 12c
Between the external electrodes 12b and 12d,
An extremely small piezoelectric transformer can be configured.

The external electrodes 12a and 12b and the external electrode 1
Half surfaces of the adjacent sides of 2c and 12d are insulators 13
Although it is covered with a and 13b, other vibrating nodes are exposed, and a lead wire is taken from this vibrating node.

Next, an embodiment of a method for manufacturing a piezoelectric transformer according to the present invention will be described with reference to FIG. First, step S ₁
In PbO, ZrO ₂ , TiO ₂ , NiO, Zn
O, Nb ₂ O ₅ and MnO ₂ are mixed at a predetermined ratio, and PbT
iO ₃ -PbZrO ₃ -Pb (Ni _1/3 Nb _2/3 ) O ₃ -M
nO ₂ , and calcining (900 ° C.) to produce a calcined powder.

[0019] Next PZT calcined powder in the step S _2, polyvinyl butyral, to form a slurry with an organic solvent, forming a film of 100μm of sheet. Next, the sheet is punched out to a size of 6 cm × 4 cm (step S ₃ ), and Ag-Pd printing of internal electrodes is performed on the punched sheet (step S ₄ ).

Next, sheets on which the internal electrodes are printed are stacked in the required number of length directions (length 20 cm) (step S).
_5), they are integrated by thermocompression bonding (Step S _6).
Then using the Ag-Pd printed same electrode paste as the internal electrode in step S _7, to form the external electrodes of the input side and the output side.

The next form an exterior ceramic in step S _8. This forming method is applied to a thickness of 10 to 10 for the external electrode.
There is a method of thermocompression bonding a green sheet made of 0 μm PZT, or a method of producing a PZT paste made of PZT ceramic and printing or applying it.

[0022] and then baked at step S _9, then performs a polarization at 25KV / cm, 100 ℃ in step S _10.

The external electrodes 12a and 12b and the external electrode 1
Half surfaces of the adjacent sides of 2c and 12d are insulators 13
a, 13b, but the other vibrating nodes are exposed and leads are taken from the vibrating nodes.

[0024]

(1) As described above, according to the piezoelectric transformer of the present invention, the creepage distance between the input-side external electrode and the output-side external electrode can be ensured, and the size and efficiency of the piezoelectric transformer can be reduced. It becomes possible. Further, by using the piezoelectric transformer of the present invention, the size of a switching power supply such as an AC adapter can be reduced.

(2) Further, according to the method of manufacturing a piezoelectric transformer of the present invention, a piezoelectric transformer in which a creepage distance between a primary external electrode and a secondary external electrode is ensured by the insulating property of a piezoelectric material is extremely simple. It can be manufactured by a simple method.

[Brief description of the drawings]

FIG. 1 shows an embodiment of a piezoelectric transformer according to the present invention,
(A) is a perspective view, (b) is a schematic plan view.

FIG. 2 is an explanatory view showing one embodiment of a method for manufacturing a piezoelectric transformer according to the present invention.

3A and 3B show a structure of a conventional longitudinal vibration type piezoelectric transformer, wherein FIG. 3A is a perspective view and FIG. 3B is a schematic plan view.

4A and 4B show a structure of a conventional longitudinal vibration type piezoelectric transformer, wherein FIG. 4A is a perspective view and FIG. 4B is a characteristic diagram of displacement in a length method.

[Explanation of symbols]

2. Piezoelectric ceramics, 3a-3d, 12a-12d ... external electrodes, 4 ... internal electrodes, 11 ... elements, 13a, 13b ...
Insulator.

Claims (12)

[Claims] A laminated body formed by laminating a plurality of elements in which a piezoelectric material and an internal electrode are integrated; and an external electrode coated with a material having the same composition as the piezoelectric material and connecting the plurality of internal electrodes in parallel. A piezoelectric transformer comprising: 2. The external electrode, wherein a primary electrode and a secondary electrode are formed at a predetermined distance from each other, and the primary electrode and the secondary electrode are separated from each other.
The piezoelectric transformer according to claim 1, wherein a material having the same composition as the piezoelectric material is thermocompression-bonded to the next electrode. 3. The external electrode, wherein a primary electrode and a secondary electrode are formed at a predetermined distance from each other, and the primary electrode and the secondary electrode are separated from each other.
The piezoelectric transformer according to claim 1, wherein a material having the same composition as the piezoelectric material is printed or applied to the next electrode. 4. The piezoelectric transformer according to claim 1, further comprising a lead wire connected to the exposed vibration node of the external electrode. 5. The piezoelectric transformer according to claim 2, further comprising a lead wire connected to the exposed vibration node of the external electrode. 6. The piezoelectric transformer according to claim 3, further comprising a lead wire connected to the exposed vibration node of the external electrode. 7. A step of manufacturing an element by integrating a piezoelectric material and an internal electrode; a step of laminating a plurality of the manufactured elements and thermocompression bonding; and a step of coating with a material having the same composition as the piezoelectric material, Forming an external electrode that connects the internal electrodes of the plurality of elements in parallel. 8. The step of forming an external electrode includes forming an external electrode on the plurality of laminated and thermocompressed laminates, and then thermocompression bonding a material having the same composition as the piezoelectric material to the external electrode. The method for manufacturing a piezoelectric transformer according to claim 7, wherein 9. The step of forming an external electrode includes forming an external electrode on the laminated body that is laminated and thermocompression-bonded, and then printing or applying a material having the same composition as the piezoelectric material to the external electrode. The method for manufacturing a piezoelectric transformer according to claim 7, wherein: 10. Exposing a vibrating node portion of the external electrode,
8. The method according to claim 7, further comprising a step of taking a lead wire from the vibrating node. 11. A vibration node portion of the external electrode is exposed,
9. The method according to claim 8, further comprising the step of taking a lead wire from the vibrating node. 12. Exposing a vibrating node portion of the external electrode,
The method according to claim 9, further comprising a step of taking a lead wire from the vibrating node.