JPH0983033A - Piezoelectric ceramic transformer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a small and thin piezoelectric ceramic transformer in which the oscillation characteristics are enhanced while reducing the cost by simplifying the constitution significantly thereby reducing the man-hour required for assembling work significantly. SOLUTION: In a Rosen type piezoelectric ceramic transformer being supported on a printed wiring board by means of a supporting member, the supporting member comprises wire-like metal terminals 14, 15 having snaking kink parts 16, 17 made of a conductive material having resiliency and specified stillness. The metal terminals 14, 15 are secured, at one ends thereof, to the side face part of oscillation nodes 2a, 2a on the input and output sides of piezoelectric ceramic transformer 1 and supported, on the other ends thereof, on the printed wiring board.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a so-called Rosen type piezoelectric ceramic transformer which utilizes vibration of a piezoelectric ceramic in a longitudinal direction, and more particularly to a support structure for the piezoelectric ceramic transformer.

[0002]

2. Description of the Related Art In recent years, there has been a demand for downsizing and cost reduction of electronic devices in the field of electronic devices. For example, regarding a fluorescent tube type backlight used in a notebook type personal computer or a mobile TV equipped with a liquid crystal display element, not only an inverter unit using a conventional electromagnetic transformer,
Inverter units that use piezoelectric ceramic transformers have been commercialized, and the characteristics of piezoelectric ceramic transformers have been utilized to make them thinner than ever. Therefore, regarding the piezoelectric ceramic transformer, it is desired that the supporting structure of the piezoelectric ceramic transformer be thin, compact, and inexpensive, and that the supporting structure be thin, compact, and inexpensive.

A Rosen type piezoelectric ceramic transformer and its characteristics will be described with reference to FIG. 6a.

The piezoelectric ceramic transformer as a whole is designated by reference numeral 1 and the piezoelectric ceramic element is designated by reference numeral 2. Electrodes 3 and 3 made of silver or the like are formed on the upper and lower surfaces on one side of the piezoelectric ceramic element 2, and input leads 4 and 4 are connected to both electrodes 3 and 3. On the other hand, the piezoelectric ceramic element 2
An electrode 5 made of silver or the like is formed on the end surface on the other side of, and the terminal lead 6 on the output side is connected to the electrode 5.

In the piezoelectric ceramic transformer 1 thus configured, the piezoelectric ceramic element 2 itself expands and contracts in its length direction by applying an AC voltage having a natural frequency determined by the material and shape of the element from the terminal leads 4 and 4. Vibration is generated, and the vibration can be output from the lead terminal 6 as an electric signal.

By the way, when the above-mentioned piezoelectric ceramic transformer is used for λ mode vibration, the vibration is as shown in FIG.
The sine curve has displacement characteristics and stress characteristics as shown in FIG. In other words, the piezoelectric ceramic element 2 has two zero displacement portions (nodes of vibration in which the piezoelectric ceramic expands and contracts) 2a,
2a occurs.

Therefore, in order to support such a piezoelectric ceramic transformer 1, it is necessary to support the two zero displacement portions 2a, 2a. For example, if the vibrating portion of the piezoelectric ceramic element is supported, the vibration characteristics will deteriorate.

Therefore, the conventional piezoelectric ceramic transformer 1
There is a method as shown in FIG. 7 as a structure for supporting the substrate on the printed wiring board. That is, the piezoelectric ceramic transformer 1
Holds the supporting columns 7, 7 made of resin supporting the two vibration nodes 2a, 2a on the printed wiring board 8, and the terminal leads 4, 4 and the terminal leads 6 on the respective land portions of the printed wiring board 8. It is fixed to 9 by soldering.

Another structure for supporting the piezoelectric ceramic transformer is shown in FIGS. 8 and 9.

According to this, the piezoelectric ceramic transformer 1
While being accommodated in the resin case 10, the vibration nodes 2a, 2a are fixed to the back surface of the case 10 by the adhesive 11. Then, the input side terminal leads 4 and 4 of the piezoelectric ceramic transformer 1 are soldered to the conductive foils 12 and 12 provided on both outer surfaces of the case 10, and the output side terminal lead 6 is provided to the outer surface of the conductive foil 13. Soldered to. The piezoelectric ceramic transformer 1 thus configured is connected to a printed wiring board (not shown) via the conductive foils 12, 12 and 13 of the case 10.

[0011]

However, as shown in FIG. 7, the piezoelectric ceramic transformer 1 is supported by the support columns 7 made of resin, and the lead terminals 4, 4 and 6 are soldered to the land portion 9. In the case of fixing, since most of the mounting process is manual work, the accuracy at the time of assembly is low. For this reason, there may be cases where the columns other than the vibration nodes 2a and 2a are supported by the support columns 7 and 7. As a result, the piezoelectric ceramic It also causes deterioration of the vibration characteristics of the transformer.

When the piezoelectric ceramic transformer 1 is housed in the case 10 as shown in FIG.
Since 0 itself occupies a large volume, downsizing and thinning are difficult, and assembling requires a lot of trouble.

The present invention has been made in order to solve the above-mentioned problems, and it is possible to reduce the size and thickness of the device, to greatly simplify the structure, to significantly reduce the number of assembling steps, and to reduce the cost, and to reduce the vibration. The object is to obtain a piezoelectric ceramic transformer whose characteristics can be improved.

[0014]

In order to achieve the above object, the piezoelectric ceramic transformer according to the present invention is a Rosen type piezoelectric ceramic transformer of a type in which the supporting member is supported on a wiring board by a supporting member. It is composed of a wire-shaped metal terminal which itself has elasticity and a predetermined rigidity. One end of the metal terminal is fixed to a zero displacement portion which is a node of vibration of the piezoelectric ceramic transformer, and the other end of the metal terminal is a wiring board. It is intended to be supported above.

In the piezoelectric ceramic transformer configured as described above, since the node of vibration of the piezoelectric ceramic transformer is supported by the wire-shaped metal terminal having elasticity, the vibration action of the piezoelectric ceramic transformer is not hindered.
Moreover, the stress generated in the metal terminal during the vibration operation can be absorbed by its own elastic action.

Further, since the metal terminal has the kink portion in the middle thereof, the elastic action of the metal terminal can be further enhanced. Therefore, the stress generated in the metal terminal during the vibration operation of the piezoelectric ceramic transformer can be increased. Can be effectively absorbed by.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a Rosen type piezoelectric ceramic transformer according to the present invention will be described below with reference to the drawings.

FIG. 1 is a perspective view showing an example of a support structure for a piezoelectric ceramic transformer according to this embodiment, and FIG. 2 is a perspective view showing details of the support structure.

The entire piezoelectric ceramic transformer is indicated by reference numeral 1, and the piezoelectric ceramic element is indicated by reference numeral 2. Input electrodes 3 and 3 formed by baking silver or the like are formed on the upper and lower surfaces of one side of the piezoelectric ceramic element 2, and an output side electrode 5 formed by baking silver or the like is formed on the other end surface of the piezoelectric ceramic element 2. Are formed.

In the piezoelectric ceramic transformer 1 thus constructed, by applying an AC voltage having a natural frequency determined from the input side electrodes 3 and 3 by the material and shape of the element, the piezoelectric ceramic element 2 itself moves in its length direction. Vibration occurs due to expansion and contraction, and the vibration can be output from the output side electrode 5 as an electric signal. Therefore, when the piezoelectric ceramic transformer 1 is used in λ mode, its vibration is as shown in FIG.
Similar to the case shown in b, the sine curve has the displacement characteristic and the stress characteristic. Therefore, the piezoelectric ceramic element 2 has two zero displacement portions (a vibration node at which the piezoelectric ceramic expands and contracts) 2a on the input side and the output side. 2a occurs in FIG. 6a
This is the same as the case of the piezoelectric ceramic element described in.

Thus, the piezoelectric ceramic transformer 1 according to the present invention has conductivity on both sides of each of the vibration nodes 2a, 2a on the input side and the output side, and has elasticity and appropriate rigidity by itself, for example, a steel wire made of tin. The metal terminals 14, 14 and 15, 15 that are plated are attached.
Each of the metal terminals 14 and 15 has, for example, a kink portion 16 or 17 bent in a meandering shape, except for one end.

These metal terminals 14, 14 and 15, 15
First, an epoxy adhesive 18 is applied to both sides of the vibration nodes 2a, 2a, and the metal terminals 14, 14 and 15,
One end portions 14a, 14a and 15a15a of 15 are adhesively fixed. The metal terminals 14, 14 have one end 14a,
The lead wires 19 and 19 which are fixed to the input side electrodes 3 and 3 by soldering are entwined and connected to the terminal 14a.
Lead wires 20, 20 which are fixed to the output side electrode 5 by soldering are entwined and connected to the one ends 15a, 15a of the terminals 5, 5, 15. If the metal terminals 14 and 15 are round bars,
One ends 14a, 14a and 15 fixed to the adhesive 18
By slightly flattening the portions a and 15a, the adhesive strength can be improved.

The piezoelectric ceramic transformer constructed as shown in FIG. 2 has the metal terminals 14, 14 and 15, 1.
The end portions 16a, 16a and 17a, 17a of the kink portions 16, 16 and 17, 17 which are the other end portions of No. 5 are mounted on the land portion 22 of the predetermined wiring pattern of the printed wiring board 21 as shown in FIG. In this state, it is transferred into the reflow furnace, fixed with solder, and mounted.

As described above, the piezoelectric ceramic transformer of the present invention has the vibration nodes 2a, 2 of the piezoelectric ceramic transformer.
Since both side surfaces of a are supported by the wire-like metal terminals 14, 14 and 15, 15 having elasticity and are mounted on the printed wiring board 21, the piezoelectric ceramic transformer is highly rigid in the vibration operation. Compared with the case of supporting with a member, it does not hinder the vibration action,
Vibration characteristics can be improved. Moreover, the vibration is transmitted to the metal terminals 14 and 15 during the vibration operation.
The stress generated in 4, 15 can be absorbed by its own elastic action, and damage to the metal terminals due to the stress can be avoided.

Further, since the metal terminals 14 and 15 have the serpentine kink portions 16 and 17, the elastic action of the metal terminals themselves is improved, so that the stress generated in the metal terminals due to vibration is further enhanced. Can be effectively absorbed.

Moreover, since the above-mentioned piezoelectric ceramic transformer can be directly mounted on the printed wiring board, the resin case is not required, and the mounting can be automated, and the size and thickness can be reduced and the number of assembling steps can be reduced. Can be achieved.

3 to 5 show another embodiment for conductively connecting the electrodes of the piezoelectric ceramic transformer and the metal terminals.

In this example, as shown in FIG. 3, in the input side electrodes 3 and 3, when the piezoelectric ceramic element 2 is fired, a predetermined width formed by baking silver or the like conductively connected to the respective input side electrodes 3 and 3 is formed. Conductive patterns 3a, 3a are formed on the side surface of the vibration node 2a on the input side. At this time, the electrodes 3 and 3 are provided with electrode non-forming surfaces 3b and 3b so that the conductive patterns 3a and 3a are not connected to the electrodes 3 having opposite polarities.

On the other hand, in the output-side electrode 5, conductive patterns 5a, 5a made of baked silver or the like, which are conductively connected to the output-side electrode 5 when the piezoelectric ceramic element 2 is fired, are provided on the side surface of the output-side vibration node 2a. To reach up to.

Thus, as shown in FIG. 4, one end portion 14a, 1 of the metal terminals 14, 14 and 15, 15 similar to that shown in FIG. 2 is formed on the conductive patterns 3a, 3a and 5a, 5a.
A piezoelectric ceramic transformer is completed by fixing 4a and 15a, 15a to the positions of the vibration nodes 2a, 2a with solder 23.

The piezoelectric ceramic transformer thus constructed has the kink portions 16, 16 and 1 which are the other end portions of the metal terminals 14, 14 and 15, 15 as in the above-mentioned embodiment.
The end portions 16a, 16a and 17a, 17a of 7, 17 are mounted on the land portion 22 of the predetermined wiring pattern of the printed wiring board 21 as shown in FIG. To be implemented.

That is, the above-mentioned piezoelectric ceramic transformer has the same operation and effect as the piezoelectric ceramic transformer described in FIG. 2, and since the lead wire is not used for the conductive connection between the electrode and the metal terminal, the piezoelectric ceramic transformer is not used. It is possible to avoid troubles such as defective conduction between the electrode and the metal terminal during the vibration operation of the ceramic transformer. Further, since only the assembly process of soldering the metal terminal to the conductive pattern is required, the automation of mounting can be further shortened.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the scope of the invention.

In both embodiments, the metal terminals 14 and 15 need not be provided with a kink portion as long as the metal terminals themselves are highly elastic. Further, when the kink portion is provided, the shape thereof may be a coil shape or the like other than the meandering shape shown in the embodiment, and may be another shape as long as it can absorb the stress applied to the metal terminal. Further, the cross-sectional shape of the metal terminal may be a round bar shape or a plate shape.

The piezoelectric ceramic transformer of this example has a λ
The case of mode vibration has been described, but even when used in other vibration modes such as λ / 2 or 3 / 2λ, it is possible to obtain the same effects as those of the above-described embodiments by providing the metal terminals at the nodes of vibration. Is something that can be done.

[0036]

As described above, the piezoelectric ceramic transformer according to the present invention comprises a wire-shaped metal terminal having elasticity and a predetermined rigidity as a supporting member, and one end of the metal terminal serves as a vibration node of the piezoelectric ceramic transformer. Since the other end of the metal terminal is supported on the wiring board by fixing it to the zero displacement part, the vibration effect of the piezoelectric ceramic transformer is not hindered, and the stress generated in the metal terminal during the vibration operation is prevented. There is an effect that it can be absorbed by its own elastic action.

Further, since the metal terminal has the kink portion in the middle thereof, the elastic action of the metal terminal can be further enhanced, and the stress generated in the metal terminal during the vibration operation of the piezoelectric ceramic transformer is further increased in the kink portion. It can be absorbed more effectively.

Further, in the piezoelectric ceramic transformer thus constructed, the supporting structure of the piezoelectric ceramic transformer can be made smaller and thinner, and since it has a simple structure, it can be easily assembled by automation and the number of assembling steps can be reduced. Since it can be done, the manufacturing cost is low. Therefore, such a support structure of the piezoelectric ceramic transformer is very suitable for practical use, for example, it is used for an inverter unit of a backlight of a liquid crystal display device or the like.

[Brief description of drawings]

FIG. 1 is a perspective view of a supported state of a piezoelectric ceramic transformer according to the present invention.

FIG. 2 is an enlarged perspective view of the piezoelectric ceramic transformer of FIG. 1 and a metal terminal that is a supporting member.

FIG. 3 is an enlarged perspective view of another example of a piezoelectric ceramic transformer.

FIG. 4 is an enlarged perspective view of the piezoelectric ceramic transformer of FIG. 3 and a metal terminal that is a supporting member.

5 is a perspective view of a supported state of the piezoelectric ceramic transformer of FIG.

FIG. 6 is an explanatory diagram of a configuration of a piezoelectric ceramic transformer. b It is a characteristic view of a piezoelectric ceramic transformer.

FIG. 7 is a perspective view of a conventional piezoelectric ceramic transformer support structure.

FIG. 8 is an external view of another example of a conventional piezoelectric ceramic transformer.

FIG. 9 is a sectional view of FIG. 8;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Piezoelectric ceramic transformer 2 Piezoelectric ceramic element 2a Vibration node 3 Input side electrode 3a Conductive pattern 5 Output side electrode 5a Conductive pattern 14,15 Metal terminal 16,17 Kink part 18 Adhesive 19,20 Lead wire 21 Printed wiring board 22 Land Part 23 Solder

Claims (5)

[Claims] 1. A Rosen-type piezoelectric ceramic transformer of a type supported on a wiring board by a supporting member, wherein the supporting member is electrically conductive, and is itself composed of a wire-shaped metal terminal having elasticity and predetermined rigidity. A piezoelectric ceramic transformer characterized in that one end of the metal terminal is fixed to a zero displacement portion which is a node of vibration of the piezoelectric ceramic transformer, and the other end of the metal terminal is supported on the wiring board. . 2. The piezoelectric ceramic transformer according to claim 1, wherein an electrode of the piezoelectric ceramic transformer and the metal terminal are conductively connected by a lead wire. 3. The piezoelectric ceramic transformer according to claim 1, wherein the electrode of the piezoelectric ceramic transformer and the metal terminal are conductively connected by a conductive pattern drawn from the electrode to a side surface of the portion where the displacement is zero. A piezoelectric ceramic transformer characterized in that 4. The piezoelectric ceramic transformer according to claim 1, 2 or 3, wherein the metal terminal has a kink portion in the middle thereof. 5. The piezoelectric ceramic transformer according to claim 4, wherein the kink portion has a meandering shape or a coil shape.