JP2013168618A - Piezoelectric transformer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thinner piezoelectric transformer device.SOLUTION: A piezoelectric transformer device 1 includes: a piezoelectric transformer element 2 that has an upper surface, a lower surface, and side surfaces each joining the upper and lower surfaces; a frame member 3 that is arranged so as to surround the side surfaces of the piezoelectric transformer element 2 with a gap therebetween; a first flexible film 7 that is bonded to the respective upper surfaces of the piezoelectric transformer element 2 and the frame member 3; and a second flexible film 8 that is bonded to the respective lower surfaces of the piezoelectric transformer element 2 and the frame member 3.

Description

  The present invention relates to a piezoelectric transformer device in which a piezoelectric transformer element housing structure is formed using a flexible film.

  Conventionally, various types of piezoelectric transformer devices using piezoelectric transformer elements made of piezoelectric ceramic have been proposed as transformer devices used in power supply circuits such as inverters. Patent Document 1 below discloses a piezoelectric transformer device having a structure in which a piezoelectric transformer element is disposed in a mounting hole provided in a printed wiring board. In the piezoelectric transformer device described in Patent Document 1, the piezoelectric transformer element is supported by a support fixing member extending from the upper surface of the piezoelectric transformer element disposed in the mounting hole to the surrounding printed wiring board.

  On the other hand, the following Patent Document 2 discloses a piezoelectric transformer device 1001 shown in an exploded perspective view in FIG. In the piezoelectric transformer device 1001, a piezoelectric transformer element 1003 is mounted on a flexible insulating member 1002. The insulating member 1002 is a flexible printed board having a wiring pattern for electrically connecting the piezoelectric transformer element 1003 to the outside. This wiring pattern is electrically connected to the surface electrode 1003a of the piezoelectric transformer element 1003 and the like.

Japanese Patent Laid-Open No. 9-36545 Japanese Patent Laid-Open No. 11-121826

  In the piezoelectric transformer device described in Patent Literature 1, the support fixing member extends from the upper surface of the piezoelectric transformer element to the surrounding printed wiring board. For this reason, there is a limit to reducing the thickness by the thickness of the support fixing member. In addition, since the piezoelectric transformer element and the printed wiring board are connected by the support fixing member, mechanical stress due to the difference between the thermal expansion coefficient of the printed wiring board and the thermal expansion coefficient of the piezoelectric transformer element occurs when the temperature changes. It tends to be added to the connecting portion between the piezoelectric transformer element and the printed wiring board and the support fixing member. Therefore, the stability of electrical connection and the characteristics as a piezoelectric transformer device may be deteriorated. In addition, the electrode of the printed wiring board and the surface electrode of the piezoelectric transformer element are electrically connected by the support fixing member. Therefore, since both the electrical connection and the mechanical support are performed by the support fixing member, the assembly process is complicated.

  On the other hand, in the piezoelectric transformer device 1001 described in Patent Document 2, a piezoelectric transformer element 1003 is laminated and mounted on an insulating member 1002. The piezoelectric transformer device 1001 is supported by being mounted on a printed wiring board (not shown). Therefore, there is a limit to reducing the thickness by the thickness of the printed wiring board. Further, in order to seal the piezoelectric transformer element 1003 from the periphery, another sealing member and a case member have to be prepared, which makes it difficult to reduce the thickness.

  An object of the present invention is to provide a piezoelectric transformer device that can be further reduced in thickness.

  The piezoelectric transformer device according to the present invention includes a piezoelectric transformer element, a frame member, and first and second flexible films. The piezoelectric transformer element has an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface. The frame member is disposed so as to surround the periphery of the side surface of the piezoelectric transformer element with a gap. The first flexible film is bonded to the upper surfaces of the piezoelectric transformer element and the frame material. The second flexible film is bonded to the lower surface of the piezoelectric transformer element and the frame material.

  In a specific aspect of the piezoelectric transformer device according to the present invention, the piezoelectric transformer device further includes a bonding material layer for bonding the first and second flexible films to the piezoelectric transformer element and the frame material, respectively. In this case, the first and second flexible films can be securely fixed to the piezoelectric transformer element and the frame member.

  In another specific aspect of the piezoelectric transformer device according to the present invention, at least one of the first and second flexible films is electrically connected to the piezoelectric transformer element and electrically connected to the outside. Electrodes are provided.

  In still another specific aspect of the piezoelectric transformer device according to the present invention, the piezoelectric transformer element includes a piezoelectric transformer element body and a surface electrode provided on the piezoelectric transformer element body. It is electrically connected to an electrode provided on at least one of the two flexible films.

  In another specific aspect of the piezoelectric transformer device according to the present invention, a surface electrode is provided on a side surface of the piezoelectric transformer element body. An electrode provided on at least one of the first and second flexible films is provided so as to protrude from the flexible film toward the piezoelectric transformer element body along the surface electrode.

  In still another specific aspect of the piezoelectric transformer device according to the present invention, surface electrodes are provided on the upper surface and the lower surface of the piezoelectric transformer element body. Electrodes are provided on the lower surface of the first flexible film and the upper surface of the second flexible film, respectively, and the surface electrode provided on the upper surface of the piezoelectric transformer element body is the first flexible film. The surface electrode provided on the lower surface of the piezoelectric transformer element body is bonded to the electrode provided on the upper surface of the second flexible film.

  According to the piezoelectric transformer device of the present invention, the frame member is disposed so as to surround the periphery of the side surface of the piezoelectric transformer element with a gap, and the first and second flexible members are disposed on the piezoelectric transformer element and the frame member. Since the conductive film is bonded, the piezoelectric transformer device can be thinned. In addition, since a support member having a complicated structure is not required, the assembly process can be simplified, and the piezoelectric transformer device can be reduced in size and cost.

It is a disassembled perspective view for demonstrating the piezoelectric transformer apparatus which concerns on the 1st Embodiment of this invention. 1 is a cross-sectional plan view of a piezoelectric transformer element used in a piezoelectric transformer device according to a first embodiment of the present invention. It is a cross-sectional view for explaining a piezoelectric transformer device according to a second embodiment of the present invention. It is a disassembled perspective view which shows an example of the conventional piezoelectric transformer apparatus.

  Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

  FIG. 1 is an exploded perspective view showing a piezoelectric transformer device 1 according to a first embodiment of the present invention. FIG. 2 is a plan sectional view of the piezoelectric transformer element 2 used in the piezoelectric transformer device 1 according to the present embodiment.

  As shown in FIG. 1, in the piezoelectric transformer device 1, a piezoelectric transformer element 2 is accommodated in a frame member 3.

  The piezoelectric transformer element 2 is composed of a modified Rosen type 5/2 wavelength element. However, the piezoelectric transformer element used in the present invention is not limited to such an element.

  As shown in FIG. 2, the piezoelectric transformer element 2 has an elongated rectangular parallelepiped, that is, strip-shaped piezoelectric transformer element body 4. The piezoelectric transformer element body 4 is made of piezoelectric ceramics. A plurality of surface electrodes 5 are respectively provided on a pair of side surfaces facing each other of the piezoelectric transformer element body 4.

  A bonding material layer 6 is provided on the upper surface of the piezoelectric transformer element body 4. In the present embodiment, a plurality of bonding material layers 6 are provided on the upper surface of the piezoelectric transformer element body 4 over the entire width in the width direction of the piezoelectric transformer element body 4. That is, the plurality of bonding material layers 6 are provided on a part of the upper surface of the piezoelectric transformer element body 4.

  Each of the plurality of bonding material layers 6 is disposed in a portion corresponding to a vibration node when the piezoelectric transformer element 2 is operated.

  In this embodiment, the joining material layer 6 consists of a double-sided adhesive tape. However, the bonding material layer 6 may be made of an adhesive.

  The thickness of the frame member 3 is equal to or greater than the thickness of the piezoelectric transformer element 2. The frame member 3 is composed of a plate-like member having an opening 3a. The frame member 3 is made of an appropriate rigid material such as ceramics, metal, or synthetic resin. The inner wall of the opening 3 a is separated from the side surface of the piezoelectric transformer element body 4 and the surface electrode 5. In the frame member 3, the piezoelectric transformer element 2 is accommodated in the opening 3a of the frame member 3 so that the side surface of the piezoelectric transformer element body 4 and the surface electrode 5 are separated from the inner wall of the opening 3a. In other words, the frame member 3 is disposed so as to surround the periphery of the side surface of the piezoelectric transformer element 2 with a gap.

  In the piezoelectric transformer device 1 of the present embodiment, the piezoelectric transformer element 2 is housed in the opening 3a of the frame member 3, and the upper and lower surfaces of the frame member 3 are the first and second flexible films 7 and 8. Covered with.

  The 1st flexible film 7 consists of a resin film which has flexibility. The first flexible film 7 is provided with a plurality of slits 7a and 7a. The slits 7 a and 7 a are provided to relieve stress applied to the bonding material layer 6 due to a difference in thermal expansion between the frame material 3, the first flexible film 7, and the piezoelectric transformer element 2. For this reason, the fluctuation | variation of the characteristic by a temperature change is suppressed, and reliability can be improved. The first flexible film 7 is bonded to the upper surface of the piezoelectric transformer element 2 by the bonding material layer 6 described above.

  A bonding material layer 9 is provided on the upper surface of the frame member 3. The bonding material layer 9 is made of an adhesive. But the joining material layer 9 may consist of a double-sided adhesive tape. The first flexible film 7 is bonded to the upper surface of the frame material 3 by the bonding material layer 9.

  The 2nd flexible film 8 consists of a flexible printed circuit board in this embodiment. Therefore, it is thin and flexible. The second flexible film 8 is also provided with a plurality of slits 8a and 8a. Similarly to the slits 7a and 7a, the slits 8a and 8a are used to relieve stress applied to the bonding material layer 6 due to a difference in thermal expansion between the frame member 3 and the first flexible film 7 and the piezoelectric transformer element 2. Is provided. For this reason, the fluctuation | variation of the characteristic by a temperature change is suppressed, and reliability can be improved.

  An electrode structure for electrically connecting the piezoelectric transformer element 2 to the outside is provided on the upper surface of the second flexible film 8. This electrode structure is connected to the electrode 10 provided so as to protrude upward by cutting and raising, the wiring electrode 11 connected to the electrode 10, and the end of the wiring electrode 11, so as to be electrically connected to the outside. Terminal electrode 12.

  The electrode 10 is formed by cutting and raising the electrode structure of the second flexible film 8. The electrode 10 protrudes upward and is provided along the surface electrode 5 of the piezoelectric transformer element 2 described above. That is, the surface electrode 5 and the electrode 10 are joined using a conductive adhesive or solder. Since the electrode 10 is provided along the surface electrode 5, the electrode 10 can be reliably bonded to the surface electrode 5.

  The width direction dimension of the second flexible film 8 is larger than the width direction dimension of the frame member 3. More specifically, the frame member 3 is disposed on the upper surface of the second flexible film 8 in a region surrounded by broken lines A and A in FIG. Accordingly, the terminal electrode 12 is exposed to the outside. Therefore, electrical connection with the outside can be easily performed.

  The second flexible film 8 may be made of an appropriate resin film having flexibility similar to the first flexible film 7. The electrode structure including the electrode 10 is made of an appropriate metal or alloy.

  As shown in FIG. 1, a pair of electrodes 10 face each other, and the piezoelectric transformer element 2 is disposed between the pair of electrodes 10 facing each other. A bonding material layer 13 is provided at the center between the pair of electrodes 10 facing each other. In the present embodiment, the bonding material layer 13 is made of a double-sided adhesive tape. However, the bonding material layer 13 may be made of an adhesive. The second flexible film 8 is bonded to the lower surface of the piezoelectric transformer element 2 by the bonding material layer 13. Further, a bonding material layer 9 made of an adhesive is provided on the lower surface of the frame member 3 in the same manner as the upper surface. With this bonding material layer 9, the second flexible film 8 is bonded to the lower surface of the frame material 3.

  As shown in FIG. 1, in this embodiment, the piezoelectric transformer element 2 is provided with a plurality of pairs of surface electrodes 5 that face each other in the width direction. Accordingly, the second flexible film 8 is also provided with a plurality of pairs of portions where the electrodes 10 and 10 face each other.

  Since the piezoelectric transformer device 1 of the present embodiment has the above-described structure, it can be thinned. That is, in the piezoelectric transformer device 1, the piezoelectric transformer element 2 is accommodated in a frame material 3 as a case material. Moreover, the first flexible film 7 is bonded to the upper surfaces of the piezoelectric transformer element 2 and the frame material 3, and the second flexible film 8 is bonded to the lower surfaces of the piezoelectric transformer element 2 and the frame material 3. Yes. Therefore, the piezoelectric transformer device 1 can be significantly thinned. Also, assembly can be easily performed. Therefore, the piezoelectric transformer device 1 can reduce the cost.

  In addition, a gap due to the thickness of the bonding material layers 6 and 13 is generated between the piezoelectric transformer element 2 and the first and second flexible films 7 and 8. That is, the upper surface portion and the lower surface portion of the piezoelectric transformer element 2 other than the portions bonded by the bonding material layers 6 and 13 are disposed with a gap from the first and second flexible films 7 and 8. . Therefore, the operation of the piezoelectric transformer element 2 is hardly hindered. Further, by adjusting the thickness of the bonding material layers 6 and 13, the gap between the upper surface of the piezoelectric transformer element 2 and the first flexible film 7, and the lower surface of the piezoelectric transformer element 2 and the second flexible film 7. The size of each gap between the conductive film 8 can be adjusted.

  In the present embodiment, the width direction dimension of the second flexible film 8 is made larger than the width direction dimension of the frame member 3 to expose the terminal electrode 12 to the outside. But the structure of the terminal electrode for connecting with the exterior is not limited to such a structure. For example, a second flexible film having the same outer shape as the frame member 3 is used, and wiring electrodes are formed so as to extend from the upper surface to the lower surface of the second flexible film, and the lower surface of the second flexible film. A terminal electrode may be provided.

  In the present embodiment, for example, on the upper surface of the piezoelectric transformer element 2 and the lower surface of the first flexible film 7, no other member is provided in a region other than the region where the bonding material layer 6 is provided. However, a tape having a thickness smaller than that of the bonding material layer 6 may be added to a region other than the region where the bonding material layer 6 is provided. Thereby, the above-described gap between the upper surface of the piezoelectric transformer element 2 and the first flexible film 7 can be reduced. By adding such a tape or the like, the size of the gap between the upper surface of the piezoelectric transformer element 2 and the first flexible film 7 can be adjusted. Similarly, regarding the size of the gap between the lower surface of the piezoelectric transformer element 2 and the second flexible film 8, the bonding material on the lower surface of the piezoelectric transformer element 2 and the upper surface of the second flexible film 8 is also used. It can be adjusted by adding a tape having a thickness smaller than that of the bonding material layer 13 to a region other than the region where the layer 13 is bonded.

  FIG. 3 is a cross-sectional view of the piezoelectric transformer device 21 according to the second embodiment of the present invention. Also in this embodiment, a piezoelectric transformer element 2A similar to that used in the first embodiment is housed in the frame member 3A. However, in the piezoelectric transformer element 2A, a plurality of surface electrodes 5A are provided on the upper surface and the lower surface of the piezoelectric transformer element body 4, respectively. As described above, the plurality of surface electrodes 5 </ b> A may be provided on the upper and lower surfaces of the piezoelectric transformer element body 4.

  Also in the present embodiment, the inner wall of the opening 3a of the frame member 3A is separated from the side surface of the piezoelectric transformer element body 4 by a distance. In the frame member 3A, the piezoelectric transformer element 2A is accommodated in the opening 3a of the frame member 3A so that the side surface of the piezoelectric transformer element body 4 is separated from the inner wall of the opening 3a.

  Also in the present embodiment, the thickness of the frame member 3A is set to be equal to or greater than the thickness of the piezoelectric transformer element 2A.

  And the 1st flexible film 7A consists of a flexible printed circuit board in this embodiment. An electrode 22 is provided on the lower surface of the first flexible film 7A. The electrode 22 is bonded to a surface electrode 5A provided on the upper surface of the piezoelectric transformer element body 4 by a bonding material layer 6A made of a conductive adhesive. The electrode 22 is joined to a surface electrode 28 provided on the upper surface of the frame member 3A. Therefore, the electrode 22 is electrically connected to the surface electrode 5A provided on the upper surface of the piezoelectric transformer element body 4 and the surface electrode 28 provided on the upper surface of the frame member 3A.

  As described above, the surface electrode 28 is provided on the upper surface of the frame member 3A. A surface electrode 29 is also provided on the lower surface of the frame member 3A. A via hole electrode 23 is provided in the frame member 3A. The upper end of the via-hole electrode 23 is connected to the surface electrode 28 provided on the upper surface of the frame member 3A. The lower end of the via-hole electrode 23 is connected to a surface electrode 29 provided on the lower surface of the frame member 3A. The via-hole electrode 23 is formed integrally with the surface electrodes 28 and 29 provided on the upper surface and the lower surface of the frame member 3A. The surface electrode 29 provided on the lower surface of the frame member 3A is connected to the wiring electrode 24 provided on the upper surface of the second flexible film 8A.

  The wiring electrode 24 wraps around the side surface from the upper surface of the second flexible film 8A to the lower surface. A portion of the wiring electrode 24 reaching the lower surface of the second flexible film 8A constitutes the terminal electrode 25.

  An electrode 26 is provided on the upper surface of the second flexible film 8A. The electrode 26 is bonded to the surface electrode 5A provided on the lower surface of the piezoelectric transformer element body 4 by a bonding material layer 6A made of a conductive adhesive. The electrode 26 wraps around the side surface from the upper surface of the second flexible film 8A to the lower surface. A portion of the electrode 26 reaching the lower surface of the second flexible film 8 </ b> A constitutes the terminal electrode 27.

  Therefore, in the piezoelectric transformer device 21 of the present embodiment, it can be easily connected to the outside by the terminal electrodes 25 and 27 provided on the lower surface of the second flexible film 8A. In FIG. 3, the width direction dimension of the second flexible film 8A is larger than the width direction dimension of the frame member 3A, but it may be the same dimension.

  In the piezoelectric transformer device 21 of this embodiment, the first and second flexible films 7A and 8A are bonded to the upper surface and the lower surface of the frame member 3A by the bonding material layers 9 and 9 made of an adhesive, respectively. ing.

  Also in the piezoelectric transformer device 21 of the present embodiment, the piezoelectric transformer element 2A is housed in the frame material 3A, and the thickness of the frame material 3A is equal to or greater than the thickness of the piezoelectric transformer element 2A. 2 has a structure in which the flexible films 7A and 8A are joined to the upper surface and the lower surface of the frame member 3A and the piezoelectric transformer element 2A, so that a significant reduction in thickness can be achieved. In addition, also in the present embodiment, by adjusting the thickness of the bonding material layers 6A and 6A, the gap between the upper surface of the piezoelectric transformer element 2A and the first flexible film 7A, and the piezoelectric transformer element 2A are adjusted. The respective sizes of the gaps between the lower surface and the second flexible film 8A can be adjusted.

  That is, in the portion where the bonding material layer 6A is not provided, the gap between the upper surface of the piezoelectric transformer element 2A and the first flexible film 7A, and the lower surface of the piezoelectric transformer element 2A and the second flexible film. The respective sizes of the gaps between 8A can be adjusted. In the present embodiment, since the bonding material layer 6A is made of a conductive adhesive, not only the piezoelectric transformer element 2A and the first and second flexible films 7A and 8A are bonded, but also an electrical connection. Can also fulfill. Note that the bonding material layer 6A may be made of another conductive bonding material such as solder.

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric transformer apparatus 2, 2A ... Piezoelectric transformer element 3, 3A ... Frame material 3a ... Opening part 4 ... Piezoelectric transformer element main body 5, 5A ... Surface electrode 6, 6A ... Bonding material layer 7, 7A ... 1st flexibility Conductive film 7a ... slit 8, 8A ... second flexible film 8a ... slit 9 ... bonding material layer 10 ... electrode 11 ... wiring electrode 12 ... terminal electrode 13 ... bonding material layer 21 ... piezoelectric transformer device 22 ... electrode 23 ... Via hole electrode 24 ... wiring electrode 25 ... terminal electrode 26 ... electrode 27 ... terminal electrodes 28, 29 ... surface electrode

Claims (6)

A piezoelectric transformer element having an upper surface, a lower surface, and a side surface connecting the upper surface and the lower surface;
A frame member disposed so as to surround the periphery of the side surface of the piezoelectric transformer element with a gap therebetween;
A first flexible film joined to the upper surface of the piezoelectric transformer element and the frame member;
A piezoelectric transformer device comprising: the piezoelectric transformer element; and a second flexible film joined to a lower surface of the frame member.   2. The piezoelectric transformer device according to claim 1, further comprising a bonding material layer that bonds the first and second flexible films to the piezoelectric transformer element and the frame material, respectively.   The electrode according to claim 2, wherein at least one of the first and second flexible films is electrically connected to the piezoelectric transformer element and electrically connected to the outside. The piezoelectric transformer device as described. The piezoelectric transformer element has a piezoelectric transformer element body and a surface electrode provided on the piezoelectric transformer element body,
The piezoelectric transformer device according to claim 3, wherein the surface electrode is electrically connected to an electrode provided on at least one of the first and second flexible films. The surface electrode is provided on a side surface of the piezoelectric transformer element body;
An electrode provided on at least one of the first and second flexible films is provided so as to protrude from the flexible film toward the piezoelectric transformer element body along the surface electrode. The piezoelectric transformer device according to claim 4. The surface electrode is provided on the upper and lower surfaces of the piezoelectric transformer element body,
The electrodes are respectively provided on the lower surface of the first flexible film and the upper surface of the second flexible film,
The surface electrode provided on the upper surface of the piezoelectric transformer element body is joined to the electrode provided on the lower surface of the first flexible film,
5. The piezoelectric transformer device according to claim 4, wherein a surface electrode provided on a lower surface of the piezoelectric transformer element body is joined to an electrode provided on an upper surface of the second flexible film.

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