JP5650365B2 - Piezoelectric transformer - Google Patents

Description

  The present invention relates to a piezoelectric transformer having a structure in which piezoelectric ceramics and internal electrodes are alternately stacked.

As a prior art relating to this type of piezoelectric transformer, a piezoelectric transformer of a type in which piezoelectric ceramics and internal electrodes are laminated and each internal electrode is connected by an external electrode provided outside is known (for example, see Patent Document 1). ). In this prior art, by setting the inner end of the internal electrode not to be exposed from the outer electrode, it is possible to suppress concentration of the electric field at the inner end when applying a high voltage in the polarization process, and to discharge from the inner end. Is prevented from occurring. As a result, desired polarization can be performed to improve the productivity of the piezoelectric transformer and also improve the reliability of the product.
JP 2006-156732 A (page 3, FIGS. 1 and 2)

  In this type of piezoelectric ceramic, a metal paste serving as an internal electrode is printed on, for example, a green sheet in the manufacturing process, and fired and diced in a state where the paste is stacked on a plurality of sheets to form a laminate. At this time, the amount of metal paste used to form the internal electrode increases in accordance with the number of stacked layers (number of stacked layers) in the stacked body, so that the material cost corresponding to the manufacturing cost per product. It will be reflected greatly.

  Therefore, the present invention seeks to provide a technique for suppressing the increase in manufacturing cost by reducing the amount of material used for forming a laminate.

  The present invention is a piezoelectric transformer in which piezoelectric ceramics and internal electrodes are alternately stacked to form a laminated body, and external electrodes formed on the outer surface of the laminated body are connected to the internal electrodes. Furthermore, this invention solves said subject by having the shape where the internal electrode was partially depressed toward the inside of a laminated body from the outer end part connected to an external electrode in the outer surface of a laminated body.

  According to the present invention, since the internal electrode has a partially recessed shape, the range (or region, area) occupied by the internal electrode per layer is reduced by the recessed portion. When this is seen as a whole of the laminate, the amount of metal used for forming the internal electrode is greatly reduced, so that an increase in manufacturing cost can be effectively suppressed. Even in this case, since the internal electrode is connected to the external electrode except for the recessed portion, a desired polarization can be realized by applying an electric field in a normal polarization process.

  Moreover, this invention can solve said subject by having an independent structure separately. That is, the piezoelectric transformer of the present invention is formed on a laminated body formed by alternately superposing piezoelectric ceramics and internal electrodes, and an outer surface along the overlapping direction of the laminated body. An external electrode connected to the outer end of the exposed internal electrode, and extends from the outer end of the internal electrode connected to the external electrode toward the inside of the laminate, and partially connects the internal electrode and the external electrode. And a connection avoiding unit for avoiding the above.

  Also in the above configuration, the range (or region, area) occupied by the internal electrodes per layer in the stacked body is reduced by the range of the connection avoiding portion. Therefore, the amount of metal used for forming the internal electrode as a whole of the laminate is greatly reduced, and the increase in manufacturing cost can be effectively suppressed. Even in this case, since the internal electrode is connected to the external electrode except for the connection avoiding portion, a desired polarization can be realized by applying an electric field in a normal polarization process.

  In general, in a piezoelectric ceramic laminate, the portion where the external electrode is in contact with the piezoelectric ceramic body is more than the portion where the internal and external electrodes exposed on the outer surface are in direct contact. Is known to have high soldering strength. Therefore, in the present invention, direct connection (contact) between the internal electrode and the external electrode is avoided at the recessed portion or the connection avoiding portion, and the piezoelectric ceramic element body and the external electrode are in contact with each other on the outer surface of the laminate. By ensuring, it contributes to ensuring high soldering strength as a product.

  The internal electrode and the external electrode are preferably used as secondary electrodes for outputting a voltage generated by piezoelectric ceramics. In this case, since it is possible to sufficiently secure the soldering strength of the secondary-side external electrode, which is higher than the primary side, for example, the wiring is soldered to the secondary-side external electrode so that the piezoelectric transformer is Even when operated, reliability as a product can be ensured for a long period of time.

  According to this invention, while reducing the usage-amount of the material required for a product and suppressing a raise of cost, the reliability and durability as a product can be improved significantly.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[First Embodiment]
FIG. 1 is a perspective view showing a piezoelectric transformer 100 according to an embodiment. The piezoelectric transformer 100 includes a drive unit 100a on the primary side and a power generation unit 100b on the secondary side. The drive unit 100a and the power generation unit 100b are each configured by stacking a plurality of sheet-like piezoelectric ceramics 102. A film-like primary internal electrode 104 and secondary internal electrode 106 are provided between the piezoelectric ceramics 102. Among these, the primary side internal electrode 104 is arrange | positioned in the drive part 100a, and the secondary side internal electrode 106 is arrange | positioned in the one end part in the electric power generation part 100b. When viewed in the thickness direction of the piezoelectric transformer 100, the piezoelectric ceramics 102 and the internal electrodes 104 and 106 overlap each other, whereby a laminate 101 is formed.

  In the laminated body 101, a primary side external electrode 108 and a secondary side external electrode 110 are formed. Among these, the primary side external electrode 108 is provided on the outer end surface of the drive unit 100a, and the secondary side external electrode 110 is provided on the outer end surface of the power generation unit 100b. In FIG. 1, only the primary external electrode 108 on the near side is shown, but the primary external electrode 108 is also formed in a pair on the outer end surface on the heel side (not shown).

  FIG. 2 is a horizontal cross-sectional view (II-II cross section in FIG. 1) showing the individual (one by one) piezoelectric ceramics 102 constituting the laminated body 101. In the laminated body 101, the piezoelectric ceramics 102 respectively shown by (A) and (B) in FIG.

  The primary side internal electrodes 104 are alternately arranged in the width direction (direction orthogonal to the longitudinal direction) of the piezoelectric ceramics 102, and each primary side internal electrode 104 forms a pair of primary sides on both sides in the width direction. One of the external electrodes 108 is connected.

  The secondary side internal electrode 106 is formed at one end in the longitudinal direction on the surface of the piezoelectric ceramic 102. The secondary-side internal electrode 106 has a shape that is recessed in a rectangular shape from one end of the piezoelectric ceramic 102 (the outer end surface of the multilayer body 101) to the inside, and the recessed portion serves as a connection avoiding portion 112. Is formed. The secondary side internal electrode 106 is not connected to the secondary side external electrode 110 in the connection avoiding unit 112.

  Thus, in the first embodiment, since the secondary side internal electrode 106 has a partially depressed shape, the amount of metal paste used per layer is reduced accordingly. Therefore, when the laminated body 101 is formed by superimposing the piezoelectric ceramics 102 on a plurality of sheets, the amount of the metal paste used as a whole is greatly reduced, so that the raw material cost can be reduced accordingly.

  Further, when soldering the wiring to the secondary side external electrode 110, avoid the location where it is connected to the secondary side internal electrode 106, for example, solder at a position corresponding to the central connection avoiding portion 112 in the width direction. By doing so, high soldering strength can be ensured.

  FIG. 3 is a diagram illustrating second to fourth embodiments of the piezoelectric transformer 100. Each embodiment will be described below.

[Second Embodiment]
3A: The second embodiment is different from the first embodiment in that a semicircular connection avoiding portion 112 is formed on the secondary internal electrode 106. FIG. Other configurations can be the same as those in the first embodiment.

[Third Embodiment]
FIG. 3B: The third embodiment is different from the first and second embodiments in that a trapezoidal connection avoiding portion 112 is formed on the secondary internal electrode 106. Other configurations are the same as those in the first and second embodiments.

[Fourth Embodiment]
In FIG. 3, (C): In the fourth embodiment, the secondary side internal electrode 106 is entirely formed in an arc shape, and a semicircular connection avoiding portion 112 is formed in the inner portion thereof. -Different from the third embodiment. Other configurations can be the same as those in the first to third embodiments.

  Also in the second to fourth embodiments described above, the amount of the metal paste used is greatly reduced as a whole, so that the raw material cost can be reduced accordingly. Further, by performing soldering on the secondary side external electrode 110 at a position corresponding to the connection avoiding portion 112, high soldering strength can be ensured.

  The present invention can be implemented with various modifications without being limited to the above-described embodiments. For example, the shapes of the secondary internal electrode 106 and the connection avoiding portion 112 are not limited to those illustrated in the embodiments, and various shapes can be appropriately employed.

  Further, in each embodiment, the secondary side internal electrode 106 has a partially recessed shape, but the primary side internal electrode 104 may have a partially recessed shape.

  In addition, the structure shown with illustration in each embodiment is a preferable example to the last, and it can be said that the present invention can be suitably implemented even if various elements are added to the basic structure or a part thereof is replaced. Not too long.

It is a perspective view which shows the piezoelectric transformer of one Embodiment. It is a horizontal sectional view (II-II section in Drawing 1) showing each piezoelectric ceramic. It is the figure which showed 2nd-4th embodiment of the piezoelectric transformer.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Piezoelectric transformer 101 Laminated body 102 Piezoelectric ceramics 104 Primary side internal electrode 106 Secondary side internal electrode 108 Primary side external electrode 110 Secondary side external electrode 112 Connection avoidance part

Claims (2)

The entire rectangular plate-shaped laminate superimposed individually a piezoelectric ceramic and internal electrodes having a rectangular plate shape alternately, an external electrode formed on one outer end surface in the longitudinal direction of the laminate outside of the laminate A piezoelectric transformer that is connected to an outer end portion of the internal electrode exposed to the internal electrode and uses the internal electrode and the external electrode as a secondary electrode for outputting a voltage generated by the piezoelectric ceramic;
The piezoelectric transformer according to claim 1, wherein the internal electrode has a shape that is partially recessed from an outer end connected to the external electrode to the inside of the multilayer body at the outer end surface. Each of the piezoelectric ceramics and the internal electrodes, each of which has a rectangular plate shape, are alternately stacked to form a rectangular plate as a whole, and the internal electrode outputs a voltage generated by the piezoelectric ceramics. A laminate used as a
Wherein formed on one outer end surface in the longitudinal direction of the laminate along superposition in the direction of the laminate, the connected to the outer end of the inner electrode exposed to the outside of the laminate in the Ichisoto end face 2 An external electrode used as a secondary electrode;
A connection avoiding portion that extends from an outer end connected to the external electrode to the inside of the multilayer body, and partially avoids connection between the internal electrode and the external electrode. A piezoelectric transformer characterized by

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