JP2967564B2 - Piezoelectric transformer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric transformer for transforming an AC voltage in electronic equipment and the like.

[0002]

2. Description of the Related Art Piezoelectric transformers have the following advantages.
(2) In response to a short circuit accident on the output side, the input resistance is automatically increased, and there is no danger of burning or the like. (3) The boost ratio can be increased. (4) No electromagnetic induction. And the like, and development for practical use has been advanced in recent years.

As shown in FIG. 9, a Rosen type piezoelectric transformer is exemplified as a typical piezoelectric transformer. A piezoelectric element 8 has a rectangular plate shape, and one half 8A of a main surface in a longitudinal direction of the element has a thickness direction. A pair of input electrodes 81 and 82 are formed, and the other half 8B forms an output electrode 83 on the end face. The former is polarized in the thickness direction, and the latter is polarized in the longitudinal direction. In general, the portion where the input electrode is formed in the thickness direction is called a driving portion, and the other half where the output electrode is formed is called a power generation portion. When an AC voltage is applied to the piezoelectric element on which the electrodes are formed, a strong mechanical vibration having a vibration displacement called a λ mode occurs as a whole as shown in FIG.
FIG. 11 is a diagram showing a node region as viewed on a plane. As a result, a high AC voltage can be obtained at the output electrode of the power generation unit by the piezoelectric effect. Although the λ mode is shown as the vibration mode, it is known that resonance also occurs in the λ / 2 mode and the 3 / 2λ mode, and the vibration displacement distribution and the nodal region of the vibration differ depending on each mode. In the case of the λ mode, conventionally, as shown in FIG.
It is supported by elastic bodies 91 and 92 such as rubber, and metal wires A, B and C are bonded to the respective electrodes for electrical input.

[0004]

However, in the above configuration, the electrical connection with the outside is made by a metal wire.
When this piezoelectric transformer is mounted on a printed wiring board, the occupied area as a whole increases, and a short circuit accident or a disconnection accident may occur due to contact with other electronic components. In addition, since the connection of the piezoelectric element to the support or the metal wire is performed separately also on the manufacturing side of the piezoelectric transformer, there are problems that the number of manufacturing steps is increased and that it is difficult to automate the manufacturing.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and does not cause a short circuit accident with other electronic parts, has a small number of man-hours, is suitable for automation of manufacture, and has a small size and a small surface. An object of the present invention is to provide a piezoelectric transformer that can be mounted.

[0006]

In order to solve the above problems, in a piezoelectric transformer according to the present invention, a piezoelectric element has a driving region and a power generation region, and the driving region is polarized in a thickness direction. An input electrode is formed on the front and back surfaces, the power generation region is polarized in the length direction, an output electrode is formed on an end of the side surface, and the output electrode is connected to the vibrating node region on the main surface or in the longitudinal direction. An extraction electrode is formed to extend to a vibration node region on the side surface of the piezoelectric element, and the structure supports the vicinity of the vibration node of the input electrode of the piezoelectric element and the extraction electrode, and conducts with the external terminal. The terminal is buried,
The piezoelectric element is inserted into the structure and integrated with each other, and each electrode and terminal of the piezoelectric element are electrically connected to each other.

[0007] As a specific structure of the structure, a leaf spring terminal is buried facing the electrode support portion of the structure, and a projection in contact with the piezoelectric element is provided on the leaf spring terminal. A through-hole is provided in the portion corresponding to the convex portion, and a conductive bonding material is injected from the through-hole, and at least the leaf spring terminal and the input electrode and the extraction electrode of the piezoelectric element are electrically connected. Features.

The piezoelectric element has a drive region and a power generation region. The drive region is polarized in the thickness direction, input electrodes are formed on the front and back surfaces, and the power generation region is polarized in the length direction. An output electrode is formed at an end of the side surface, and a lead-out electrode is formed to extend the output electrode to an end on the main surface. The output electrode is supported near the vibrating node of the input / output electrode of the piezoelectric element. There is a structure in which a terminal that conducts with the external terminal is embedded, and the piezoelectric element is inserted into the structure and integrated with each other. In the piezoelectric transformer, the input-side structure is a piezoelectric element. A leaf spring terminal having a convex portion electrically connected to the input electrode is buried facing each other, and a through-hole is provided in a portion corresponding to the convex portion of the input-side structure. Inject conductive bonding material from at least leaf spring terminal An electrical connection with an input electrode of the piezoelectric element is made, and the output-side structure has a part of a leaf spring terminal exposed and embedded outside the structure. Is electrically connected to the output electrode through a lead wire or a bonding wire.

Further, the structure may be an integrated structure having two portions, an input node support portion and an output node support portion.

[0010]

According to the first aspect of the present invention, the electrical connection with the terminal of the structure is made reliable and easy by the extraction electrode, and the productivity is extremely high. Further, since the extraction electrode extends to the vibration node portion area, electrical connection and mechanical connection can be simultaneously performed at the mounting position of the structure, and the vibration of the piezoelectric transformer is not hindered at all, which is extremely simple. A piezoelectric transformer having a simple configuration can be obtained.

According to the second aspect of the present invention, in addition to the above-mentioned functions and effects, the piezoelectric element is installed on a structure in which a leaf spring terminal provided with a convex portion is disposed so as to penetrate therethrough. Since the spring terminal is electrically and mechanically connected by a conductive bonding material, the vibration of the piezoelectric element is further prevented from being hindered, and a more reliable electrical connection can be obtained, and an extremely simple configuration is achieved. A piezoelectric transformer can be obtained.

According to the third aspect, the lead electrode of the piezoelectric element and the leaf spring terminal exposed to the outside are simply and reliably formed on the same main surface by using a conductor such as a lead wire or a bonding wire. Thus, a piezoelectric transformer having a very simple configuration can be obtained without obstructing the vibration of the piezoelectric element.

According to the fourth aspect of the present invention, in addition to the above operation and effect, the structure is an integrated structure having two portions, an input node support portion and an output node support portion. There is no displacement of the structure from the vibration element portion of the piezoelectric element when the piezoelectric element is installed on the structure, or terminal displacement from the pad when the piezoelectric element is mounted on the circuit board. It became easier.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment according to the present invention will be described with reference to the drawings. FIG. 1 is an exploded perspective view showing an embodiment of the present invention, and FIG. 2 is a sectional view of the structure of FIG. FIG. 3 is a perspective view showing an embodiment of the present invention, and FIG. 4 is a sectional view of FIG. The same parts as in the other embodiments are denoted by the same reference numerals, and the same description is omitted. The piezoelectric element 1 of the present invention is cut into a rectangular plate. The piezoelectric element 1 is divided into a driving section 1A and a power generation section 1B with a center in the longitudinal direction of the piezoelectric element 1 as a boundary, and when vibrating in the λ mode, a node region of the vibration is formed. The driving section 1A is subjected to polarization processing in the thickness direction, and input electrodes 11 and 12 made of silver or the like are provided on the front and back main surfaces. An output electrode 13 is provided at an end in the longitudinal direction of the power generation unit 1B, and an extraction electrode 13a is provided on the upper surface of the vibration node region, and is electrically connected to the output electrode 13 by a connection electrode 14. . Further, the extraction electrode may be provided on the lower surface, or may be provided on both the upper surface and the lower surface, but there is a case where there is no problem even on one surface depending on the electrode connection configuration with the outside.

Such an electrode forming or polarizing method of the piezoelectric element can be more efficiently performed as follows. . Although not shown, an input electrode is formed on each of the front and back surfaces of one half of the main surface (the drive unit group) of the large rectangular plate-shaped ceramic wafer W, and the end surface of the other half of the main surface (the power generation unit group) is substantially formed. An output electrode is formed on the entire surface. These electrodes may be formed by metallization using screen printing or the like. . The input electrodes on both sides are short-circuited and a high DC voltage (for example, 4K) is applied between these input and output electrodes.
V / mm, 0.5 hours). Thereby, the direction from the input electrode to the output electrode is polarized. . Next, by applying a high DC voltage between the input electrodes under the same conditions as above, the input electrodes are polarized in the thickness direction. The ceramic wafer having the electrodes formed and polarized as described above is cut at predetermined intervals to obtain a plurality of piezoelectric elements having a pair of input electrodes and output electrodes. . An evaporation mask having windows formed at positions corresponding to nodes of vibration on the upper surface of the piezoelectric element is arranged above and below the plurality of polarized piezoelectric elements, and an extraction electrode and a connection electrode are formed by a vacuum evaporation method. Through this window, the deposited metal adheres to the piezoelectric element.

A structure for supporting the piezoelectric element 1 will be described. The structures 21A and 22A are made of, for example, an insulator such as a resin, and have through-holes 21a and 22a having inner dimensions larger than the outer dimensions of the cross section in the lateral direction of the piezoelectric element 1, and the through-holes 21a and 22a. Two metal lead terminals 2 respectively penetratingly arranged on the upper surface and the lower surface facing each other at a predetermined interval
3, 24, and 25, 26. These metal lead terminals 23, 24 and 25, 26 are slightly curved in the direction approaching each other inside the penetrating portion, and have protrusions 23a, 24a, 25a at positions corresponding to input electrodes or extraction electrodes formed on the piezoelectric element. (Only a part is shown), and at least a part of these projections is provided with a through hole. In addition, through holes 23b, 24b and 26b (only some of which are shown) are formed in the portions of the structure corresponding to these convex portions. Such structures 21 and 22 can be easily manufactured by a resin molding technique. Then, a piezoelectric element is inserted into the penetrating portions of the structures 21A and 22A, and the vibrating nodes are set so as to be sandwiched by the convex portions. The conductive bonding material 3 is injected from the through-hole portions, and the input electrode and the extraction electrode are provided. And the metal lead terminal protruding into the structure is electrically connected with a conductive bonding material.

Second Embodiment A second embodiment will be described with reference to FIGS. FIG. 5 is an exploded perspective view showing the second embodiment, and FIG. 6 is a perspective view showing a state where the piezoelectric element of FIG. 5 is mounted. Structure 2B of this embodiment
Is obtained by integrally molding the structures 21A and 22A of the first embodiment, and has a configuration having vibration node supporting portions 21B and 22B. This structure 2B is also made of an insulator such as a resin as in the above-described embodiment, and its supporting portions 21B, 22B
Are provided with penetrating portions 231a and 232a having an inner dimension larger than the outer dimension of the cross section in the transverse direction of the piezoelectric element 1, and penetratingly disposed at predetermined intervals on the upper and lower surfaces of the penetrating portions 231a and 232a. 2 metal lead terminals 2 each
3, 24, and 25, 26. These metal lead terminals 23, 24 and 25, 26 are slightly curved in the direction approaching each other inside the penetrating portion, and have protrusions 23a, 25a (one) at positions corresponding to input electrodes or extraction electrodes formed on the piezoelectric element. Portions are shown), and at least a part of these convex portions is provided with a through hole. In addition, the supporting portions 21B, 2 corresponding to these convex portions
Through holes 24c and 26c (only some are shown) are formed in 2B. Such a structure 2B can be easily manufactured by a resin molding technique. And the structure 2
A piezoelectric element is inserted into the penetrating portion of B, and the vibrating node portion is set so as to be sandwiched by the convex portion. A conductive bonding material is injected from the through-hole portion, and the input electrode and the extraction electrode and the metal protruding into the structure. The lead terminals are electrically connected to each other by a conductive bonding material. The structure 2B includes a structure 21A of the first embodiment,
Since 22A is formed as an integrated structure, there is no displacement of the structure from the piezoelectric element vibration node when the piezoelectric element is installed on the structure, or no terminal displacement from the pad when mounted on the circuit board, Accuracy in assembling and installation is improved, making it easier to respond to automation.

Third Embodiment The metal lead terminals of the structure on the power generation unit side are not limited to those in the above embodiment. For example, with reference to FIGS. 7 and 8, the structure 2C of the third embodiment has a configuration in which the vibration node supporting portions 21B and 233 are provided. This structure 2C is also made of an insulator such as a resin as in the above-described embodiment, and its support portions 21B and 233 have through-holes 23 having an inner dimension larger than the outer dimension of the cross section in the lateral direction of the piezoelectric element 7.
1a and 233a are provided. The supporting portion 21B on the driving portion side is composed of two metal lead terminals 23 and 24, which are respectively disposed through the upper surface and the lower surface of the through portion 231a so as to face each other at a predetermined interval as in the above-described embodiment. The lead terminals 23 and 24 are slightly curved in a direction approaching each other inside the penetrating portion, and have a protrusion 23a (only a part is shown) at a position corresponding to an input electrode formed on the piezoelectric element. And these convex parts are provided with a through hole at least in part. Further, a through hole 24c (only part of which is shown) is formed in the support portion 21B corresponding to these convex portions. Further, the supporting portion 233 on the power generation unit side is formed of a metal lead terminal 27 which is arranged to penetrate, and the metal lead terminal 27 is configured to be exposed to the outside at least on the upper surface of the supporting portion 233. Such a structure 2C
Can be easily manufactured by a resin molding technique. The piezoelectric element 7 has input electrodes 51 and 52 formed on the front and back surfaces of the drive unit, an output electrode 6 formed on the longitudinal end of the power generation unit, and a main surface end drawn out from the main surface end. A partial lead electrode 61 is formed. The piezoelectric element 7 is inserted into the through portion of the structure 2C, and the vibration node on the input electrode side is set so as to be sandwiched by the protrusion. The metal lead terminal projecting into the body was electrically connected with a conductive bonding material, and the main surface end lead-out electrode 61 and the metal lead terminal 27 were electrically connected with the conductor 4 such as a bonding wire.

Fourth Embodiment Although not shown, a piezoelectric ceramic element in which each input electrode and each output electrode are extended to either side of each vibration node area to form an extraction electrode is formed by a metal lead. The terminals are placed in a structure through which the terminals are arranged, and the metal lead terminals protruding into the structure are electrically and mechanically connected to each of the extraction electrodes, thereby eliminating the thickness of the metal lead terminals. Can be

In the embodiment of the present invention, a resin is used as the material of the structure, but an elastic material such as rubber may be used.

In the above-described embodiment, the λ mode having two nodal regions is shown as the vibration mode. However, a mode having more nodes than the vibration (for example, 3 / 2λ mode) can be applied. .

[0022]

According to each claim of the present invention, the following effects can be obtained. According to the first aspect of the present invention, the electrical connection with the terminal of the structure is reliably and easily made by the extraction electrode, and the productivity is extremely high. Further, since the extraction electrode extends to the vibration node portion area, electrical connection and mechanical connection can be simultaneously performed at the mounting position of the structure, and the vibration of the piezoelectric transformer is not hindered at all, which is extremely simple. A piezoelectric transformer having a simple configuration can be obtained. Therefore, workability at the time of manufacturing can be improved or automation can be easily performed. In addition, mounting on a circuit board by the piezoelectric transformer of the present invention is easy to handle because electrical connection and mechanical connection can be performed at once through terminals of the structure, and surface mounting is also facilitated.

According to the second aspect of the present invention, in addition to the above-mentioned functions and effects, the piezoelectric element is installed on a structure in which a leaf spring terminal provided with a convex portion is disposed so as to penetrate therethrough. Since the spring terminal is electrically and mechanically connected by a conductive bonding material, the vibration of the piezoelectric element is further prevented from being hindered, and a more reliable electrical connection can be obtained, and an extremely simple configuration is achieved. A piezoelectric transformer can be obtained.

According to the third aspect of the present invention, the lead electrode of the piezoelectric element and the leaf spring terminal exposed to the outside are simply and reliably formed on the same main surface by using a conductor such as a lead wire or a bonding wire. Thus, a piezoelectric transformer having a very simple configuration can be obtained without obstructing the vibration of the piezoelectric element. Therefore, workability at the time of manufacturing can be improved or automation can be easily performed. In addition, mounting on a circuit board by the piezoelectric transformer of the present invention is easy to handle because electrical connection and mechanical connection can be performed at once through terminals of the structure, and surface mounting is also facilitated.

According to the fourth aspect, in addition to the above-mentioned functions and effects, the structure is an integrated structure having two parts, an input node support portion and an output node support portion. Also, there was no displacement of the structure from the vibrating node of the piezoelectric element when the piezoelectric element was mounted on the structure, or there was no terminal deviation from the pad when the piezoelectric element was mounted on the circuit board. Therefore, it has become easier to further improve workability at the time of manufacturing or to cope with further automation.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing a first embodiment of the present invention.

FIG. 2 is a cross-sectional view of the structure of FIG.

FIG. 3 is a perspective view showing a first embodiment of the present invention.

FIG. 4 is a sectional view of FIG. 3;

FIG. 5 is an exploded perspective view showing a second embodiment of the present invention.

6 is a perspective view showing a state where the piezoelectric element of FIG. 5 is mounted.

FIG. 7 is an exploded perspective view showing a third embodiment.

8 is a perspective view showing a state where the piezoelectric element of FIG. 7 is mounted.

FIG. 9 is a perspective view showing a conventional example.

FIG. 10 is a diagram showing a vibration mode.

FIG. 11 is a diagram showing a node region of vibration.

[Explanation of symbols]

 1, 7, 8 ... piezoelectric element 11, 12, 51, 52, 81, 82 ... input electrode 6, 13, 83 ... output electrode 13a ... extraction electrode 14 ... connection electrode 21A, 22A, 2B, 2C: Structure 23, 24, 25, 26, 27: Metal lead terminal 3: Conductive bonding material

Continuation of the front page (56) References JP-A-6-334235 (JP, A) JP-A-1-167718 (JP, U) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01L 41 / 107

Claims (4)

(57) [Claims] The piezoelectric element has a drive area and a power generation area.
And is, the driving region is polarized in the thickness direction, the front and back to the input electrodes are formed, the power generation region is polarized in the longitudinal direction, with an output electrode is formed on a side end portion, the output Electrode on main surface
Vibrating node area or vibrating node area on the longitudinal side
Are formed lead electrode extending to the structure, said vibration node portions near the input electrode of the piezoelectric element, and the extraction electrode support made is embedded a terminal subjected to conduction with external terminals, said with <br/> be integrated with each other by inserting the piezoelectric element to the structure, the piezoelectric transformer and the electrode and the terminal of the piezoelectric element is characterized by comprising electrically connected. 2. A leaf spring terminal is buried opposite to an electrode supporting portion of the structure, and a projection in contact with a piezoelectric element is provided on the leaf spring terminal, and a portion corresponding to the projection of the structure is provided. Is provided with a through-hole, a conductive bonding material is injected from this through-hole,
2. The piezoelectric transformer according to claim 1, wherein at least an electrical connection is made between a leaf spring terminal and an electrode of the piezoelectric element. 3. The piezoelectric element has a drive area and a power generation area.
And is, the driving region is polarized in the thickness direction, the front and back to the input electrodes are formed, the power generation region is polarized in the longitudinal direction, with an output electrode is formed on a side end portion, the output Electrode on main surface
An extraction electrode extending to the end is formed, and there is a structure in which a terminal for supporting near the vibration node portion of the input / output electrode of the piezoelectric element and having a terminal for conducting with an external terminal is embedded.
In the piezoelectric transformer in which the piezoelectric element is inserted into the structure and integrated with each other, the input-side structure has a leaf spring terminal having a projection electrically connected to an input electrode of the piezoelectric element. The input-side structure has a transparent portion at the portion corresponding to the convex portion.
Holes are provided, and a conductive bonding material is injected from the through holes to reduce
The electrical connection between the leaf spring terminal and the input electrode of the piezoelectric element
The output-side structure is embedded in the output-side structure such that a part of the leaf spring terminal is exposed to the outside of the structure, and the exposed portion and the output electrode of the piezoelectric element are connected to a lead wire or a bonding wire. A piezoelectric transformer, which is electrically connected via a wire. 4. The structure according to claim 1, wherein said structure is an integrated structure having two portions, an input node support portion and an output node support portion. The piezoelectric transformer according to the item.