JP2017084857A - Piezoelectric transformer and piezoelectric transformer device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric transformer in which the insulation distance between electrodes can be ensured sufficiently.SOLUTION: In a piezoelectric transformer 1 where a voltage is excited in an output side first external electrode 13 and an output side second external electrode 14, by applying an AC voltage to an input side first external electrode 11 and an input side second external electrode 12, the external electrodes 11-14 are provided on the first surface S1 of a piezoelectric material 10 while being insulated from each other. The input side first external electrode 11 and second external electrode 12, and the output side first external electrode 13 and second external electrode 14 face, respectively, in the Y axis direction. The input side first external electrode 11 and output side first external electrode 13, and the input side second external electrode 12 and output side second external electrode 14 are arranged, respectively, in the X axis direction.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a piezoelectric transformer and a piezoelectric transformer device in which, when a voltage is applied to an input side electrode provided in a piezoelectric body, the voltage is excited to an output side electrode.

  Patent Document 1 discloses a piezoelectric transformer having a configuration in which all external electrodes are provided on the same surface of a laminate in which a plurality of piezoelectric layers and a plurality of internal electrode layers are alternately laminated. In this piezoelectric transformer, a pair of external electrodes are provided along opposing sides of a rectangular surface, and another pair of external electrodes is provided therebetween.

Japanese Patent Laid-Open No. 11-26831

  However, when the piezoelectric transformer described in Patent Document 1 is used in a circuit that handles high voltage such as an AC adapter, the external electrode arrangement described in Patent Document 1 is provided with each electrode so as to maintain a sufficient insulation distance. It ’s difficult.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric transformer and a piezoelectric transformer device capable of ensuring a sufficient insulation distance between electrodes.

  The present invention provides the first external electrode, the second external electrode, or the third external electrode among the first external electrode, the second external electrode, the third external electrode, and the fourth external electrode provided on the piezoelectric body. In the piezoelectric transformer in which a voltage is applied to one of the electrode and the fourth external electrode and the voltage is excited to the other, the piezoelectric body having a rectangular first surface is provided in the piezoelectric body, A plurality of first internal electrodes connected to the first external electrode, a plurality of second internal electrodes provided in the piezoelectric body and connected to the second external electrode, and provided in the piezoelectric body, the third external electrode A plurality of third internal electrodes connected to the piezoelectric body, and a plurality of fourth internal electrodes provided in the piezoelectric body and connected to the fourth external electrode, wherein the first external electrode, the second external electrode, The third external electrode and the fourth external electrode are insulated from each other Provided on the first surface of the piezoelectric body, and the first external electrode and the second external electrode are arranged along one side direction of the first surface of the piezoelectric body, and the third external electrode and The fourth external electrode is arranged along the one side direction of the first surface of the piezoelectric body, and the first external electrode and the third external electrode are the one side of the first surface of the piezoelectric body. The second external electrode and the fourth external electrode are arranged along a direction orthogonal to the direction, and the second external electrode and the fourth external electrode are arranged along a direction orthogonal to the one-side direction of the first surface of the piezoelectric body. To do.

  In this configuration, since the first external electrode and the second external electrode, and the third external electrode and the fourth external electrode are spaced apart from each other, insulation between the electrodes can be maintained. Further, since each electrode is formed on the same surface of the piezoelectric body, mounting of the piezoelectric transformer is facilitated.

  The first internal electrode, the second internal electrode, the third internal electrode, and the fourth internal electrode may be planar electrodes, and the normal directions of the main surfaces of the planar electrodes may be the same.

  In this configuration, the configuration of the external electrode is easily formed.

  The piezoelectric body may have a rectangular parallelepiped shape having a long side in the normal direction of the main surface.

  In this configuration, the external electrodes can be easily separated from each other, and insulation between the electrodes can be maintained.

  The first external electrode and the second external electrode are high-voltage side electrodes, the third external electrode and the fourth external electrode are low-voltage side electrodes, and the first internal electrode and the second internal electrode are The planar electrode has a principal surface having the same shape as the cross section orthogonal to the long side of the piezoelectric body, and the third internal electrode and the fourth internal electrode are planar electrodes having a circular principal surface. A certain configuration may be used.

  In this configuration, in the case of a piezoelectric transformer that vibrates in a thickness longitudinal vibration mode in which the direction along the first surface is a thickness, it is difficult to crack on the low voltage side of the piezoelectric body, and a piezoelectric transformer having excellent element strength can be realized. .

  The first external electrode and the second external electrode may be a primary electrode pair, and the third external electrode and the fourth external electrode may be a secondary electrode pair.

  The piezoelectric body includes a first secondary side, a first primary side, a second primary side, and a second secondary arranged in a direction along the one side direction of the first surface. The first internal electrode, the second internal electrode, the first external electrode, and the second external electrode are provided on the first primary side of the piezoelectric body, and the third internal electrode The internal electrode, the fourth internal electrode, the third external electrode, and the fourth external electrode are provided on the first secondary side of the piezoelectric body, and the second primary side of the piezoelectric body A fifth external electrode and a sixth external electrode provided on the first surface located on the first surface; a seventh external electrode provided on the first surface located on the second secondary side portion of the piezoelectric body; An eighth external electrode, a plurality of fifth internal electrodes provided on the second primary side of the piezoelectric body and connected to the fifth external electrode, and the first of the piezoelectric body A plurality of sixth internal electrodes connected to the sixth external electrode and a plurality connected to the seventh external electrode on the second secondary side of the piezoelectric body. A plurality of eighth internal electrodes provided on the second secondary side portion of the piezoelectric body and connected to the eighth external electrode, wherein the fifth external electrode and the The sixth external electrode is arranged along the one side direction of the first surface of the piezoelectric body, and the seventh external electrode and the eighth external electrode are arranged in the one side direction of the first surface of the piezoelectric body. The fifth external electrode and the seventh external electrode are arranged along a direction orthogonal to the one side direction of the first surface of the piezoelectric body, and the sixth external electrode and the eighth external electrode The external electrode is arranged along a direction perpendicular to the one side direction of the first surface of the piezoelectric body It may be configured to have been.

  In this configuration, the vibration energy of the first high voltage portion and the second high voltage portion is configured to be symmetrical with respect to the center portion of the piezoelectric body, whereby the first low voltage portion and the second low voltage portion are used. Can communicate efficiently. As a result, efficient transformation is possible.

  The piezoelectric transformer device according to the present invention further includes a substrate on which the piezoelectric transformer and the piezoelectric body vibrate in a thickness longitudinal vibration mode having a thickness in a direction along the first surface and the piezoelectric body is mounted. The substrate includes a first mounting electrode on which the first external electrode is mounted, a second mounting electrode on which the second external electrode is mounted, a third mounting electrode on which the third external electrode is mounted, A fourth mounting electrode on which the fourth external electrode is mounted, each of the first mounting electrode, the second mounting electrode, the third mounting electrode, and the fourth mounting electrode being mounted. The configuration may be the same as the node point when the piezoelectric body is vibrated.

  In this configuration, even when mounted on the substrate, the vibration of the piezoelectric transformer is not affected.

  The first mounting electrode and the second mounting electrode are formed at positions that coincide with a first node point, and the third mounting electrode and the fourth mounting electrode are formed at positions that coincide with a second node point. The structure which is may be sufficient.

  In this configuration, the piezoelectric transformer can be stably electrically connected to the substrate.

  According to the present invention, it is possible to maintain insulation between the first external electrode and the second external electrode, the third external electrode, and the fourth external electrode that are disposed apart from each other.

(A) is a plan view of the piezoelectric transformer according to the first embodiment, (B) is a sectional view taken along line IB-IB in (A), and (C) is a sectional view taken along line IC-IC in (A). Diagram for explaining the vibration direction of the input area and output area The figure which shows the piezoelectric transformer device where the piezoelectric transformer was mounted in the substrate (A) is a top view of the piezoelectric transformer which concerns on Embodiment 2, (B) is a perspective view. 4A is a sectional view taken along line VA-VA in FIG. 4A, FIG. 4B is a sectional view taken along line VB-VB in FIG. 4A, and FIG. 4C is a sectional view taken along line VC in FIG. Sectional view of line -VC, (D) is a sectional view of line VD-VD in FIG. Diagram for explaining the reason why a crack occurs in a piezoelectric body A perspective view of a piezoelectric transformer according to a third embodiment.

(Embodiment 1)
1A is a plan view of the piezoelectric transformer 1 according to Embodiment 1, FIG. 1B is a cross-sectional view taken along line IB-IB in FIG. 1A, and FIG. 1C is an IC in FIG. -It is sectional drawing of IC line. Note that FIG. 1A is a perspective view of the inside of the piezoelectric body 10.

  The piezoelectric transformer 1 includes a long rectangular parallelepiped piezoelectric body 10 on one side. The piezoelectric body 10 is formed by stacking, for example, PZT ceramic sheets. In the following, the longitudinal direction is the X-axis direction, the width direction is the Y-axis direction (corresponding to the “one side direction” according to the present invention), and the thickness direction is the Z-axis direction. The piezoelectric transformer 1 according to this embodiment is assumed to vibrate in the length direction in the (2λ / 2) resonance mode. Here, λ is one wavelength of vibration in the X-axis direction. Therefore, the length of the piezoelectric body 10 in the X-axis direction is (2λ / 2).

  The piezoelectric body 10 is formed with a primary-side input area 10A and a secondary-side output area 10B along the X-axis direction. The piezoelectric transformer 1 according to the present embodiment is a transformer that receives an AC voltage from the input region 10A, steps down the voltage, and outputs the voltage from the output region 10B. That is, the input region 10A is on the high voltage side, and the output region 10B is on the low voltage side. The input area 10A and the output area 10B are each polarized in the X-axis direction. The polarization direction may be the same in the input region 10A and the output region 10B, or may be in the opposite direction.

  On the first surface S1 along the XY axis direction of the input region 10A, the input side first external electrode 11, the input side second external electrode 12, the output side first external electrode 13, and the output side second An external electrode 14 is provided. The first surface S <b> 1 provided with these electrodes 11 to 14 becomes a mounting surface of the piezoelectric transformer 1. The input side first external electrode 11 corresponds to a “first external electrode” according to the present invention, and the input side second external electrode 12 corresponds to a “second external electrode” according to the present invention. The output-side first external electrode 13 corresponds to a “third external electrode” according to the present invention, and the output-side second external electrode 14 corresponds to a “fourth external electrode” according to the present invention. The input side first external electrode 11 and the input side second external electrode 12 correspond to the “primary side electrode pair” according to the present invention, and the output side first external electrode 13 and the output side second external electrode 14. Corresponds to a “secondary electrode pair” according to the present invention.

  The input side first external electrode 11, the input side second external electrode 12, the output side first external electrode 13, and the output side second external electrode 14 have a rectangular shape having a major surface composed of a long side and a short side. Each of the electrodes 11, 12, 13, and 14 is provided on the first surface S1 of the piezoelectric body 10 so that the long side coincides with the X-axis direction and the short side coincides with the Y-axis direction.

  Specifically, the input-side first external electrode 11 and the output-side first external electrode 13 are provided along one long side of the first surface S1 of the piezoelectric body 10. The input-side second external electrode 12 and the output-side second external electrode 14 are provided along the other long side of the first surface S1 of the piezoelectric body 10. Moreover, the input side 1st external electrode 11 and the input side 2nd external electrode 12 are facing along the Y-axis direction. The output side first external electrode 13 and the output side second external electrode 14 face each other along the Y-axis direction.

  The input-side first external electrode 11, the input-side second external electrode 12, the output-side first external electrode 13 and the output-side second external electrode 14 are arranged as described above, so that the input-side first external on the high-voltage side is arranged. The electrode 11 and the input-side second external electrode 12 can be easily separated from the low-voltage-side output-side first external electrode 13 and the output-side second external electrode 14, and insulation between the electrodes can be maintained. Moreover, by forming the external electrodes 11 to 14 on the same surface of the piezoelectric body 10, the piezoelectric transformer 1 can be easily mounted on a substrate (not shown).

  A plurality of input side first internal electrodes 111 and a plurality of input side second internal electrodes 121 are provided in the input region 10A. As shown in FIG. 1B, the input-side first internal electrode 111 has a circular main surface and is electrically connected to the input-side first external electrode 11. That is, the input-side first external electrode 11 and the input-side first internal electrode 111 form electrodes having the same potential. As shown in FIG. 1C, the input-side second internal electrode 121 has a circular main surface and is electrically connected to the input-side second external electrode 12. That is, the input-side second external electrode 12 and the input-side second internal electrode 121 form the same potential electrode. Note that the circular main surface of the input-side first internal electrode 111 and the circular main surface of the input-side second internal electrode 121 have substantially the same size. The input-side first internal electrode 111 and the input-side second internal electrode 121 are alternately provided along the X-axis direction so that the normal direction of the main surface is the X-axis direction.

  In the output region 10B, a plurality of output-side first internal electrodes 131 and a plurality of output-side second internal electrodes 141 are provided. Although not shown, the output-side first internal electrode 131 has the same shape as the input-side first internal electrode 111 (see FIG. 1B) and is electrically connected to the output-side first external electrode 13. That is, the output-side first external electrode 13 and the output-side first internal electrode 131 form electrodes having the same potential. Although not shown, the output-side second internal electrode 141 has the same shape as the input-side second internal electrode 121 (see FIG. 1C) and is electrically connected to the output-side second external electrode 14. That is, the output-side second external electrode 14 and the output-side second internal electrode 141 form electrodes having the same potential. The output-side first internal electrodes 131 and the output-side second internal electrodes 141 are alternately provided along the X-axis direction so that the normal direction of the main surface is the X-axis direction.

  As described above, the input region 10A is on the high voltage side, and the output region 10B is on the low voltage side. Therefore, the distance between the input side first internal electrode 111 and the input side second internal electrode 121 is longer than the distance between the output side first internal electrode 131 and the output side second internal electrode 141. In addition, the number of each electrode 111, 121, 131, 141 is not limited to the number shown in FIG.

  FIG. 2 is a diagram for explaining the vibration directions of the input area 10A and the output area 10B. The arrow shown in FIG. 2 is the expansion / contraction direction of the piezoelectric body 10 in the input region 10A and the output region 10B. The broken line indicates the stress distribution of the piezoelectric body 10. Further, the waveform shown in the lower part of FIG. 2 shows the displacement distribution of the vibrating piezoelectric body 10.

  When an AC voltage is applied to the input side first external electrode 11 and the input side second external electrode 12, an electric field is generated between the input side first internal electrode 111 and the input side second internal electrode 121. That is, an electric field is applied to the input region 10A in the polarization direction. At this time, for example, the electric field is applied in the opposite direction between the positive direction side and the negative direction side in the X-axis direction with the input side first internal electrode 111 interposed therebetween. Then, a thickness longitudinal vibration having a thickness in the polarization direction, that is, the X-axis direction along the first surface S1 of the piezoelectric body 10 is excited by the inverse piezoelectric effect, and the input region 10A has X as shown by an arrow in FIG. It expands and contracts in the axial direction.

  When longitudinal vibration is excited, mechanical distortion occurs in the X-axis direction (polarization direction) in the output region 10B, and the output region 10B expands and contracts in the X-axis direction as indicated by arrows in FIG. Since it is a 2λ / 2 vibration mode, the expansion and contraction directions of the input region 10A and the output region 10B are opposite. A potential difference is generated in the polarization direction due to the piezoelectric longitudinal effect. That is, a potential difference is generated between the output-side first internal electrode 131 and the output-side second internal electrode 141. At this time, for example, a voltage is induced in the opposite direction between the positive direction side and the negative direction side in the X-axis direction across the output-side first internal electrode 131. Then, the transformed voltage is output from the output-side first external electrode 13 and the output-side second external electrode 14.

  The input-side first external electrode 11 and the input-side second external electrode 12 are provided at a position that coincides with the first node point P1 having the smallest vibration displacement in the input region 10A. The output-side first external electrode 13 and the output-side second external electrode 14 are provided at positions that coincide with the second node point P2 having the smallest vibration displacement in the output region 10B. When the piezoelectric transformer 1 is mounted, the piezoelectric transformer 1 is supported and wired at a position (node points P1, P2) where vibration displacement is the smallest, so that the piezoelectric transformer 1 is not obstructed and the piezoelectric body is mounted after mounting. It is possible to prevent the connection reliability from being lowered by the displacement of 10.

  FIG. 3 is a diagram illustrating a piezoelectric transformer device 1 </ b> A in which the piezoelectric transformer 1 is mounted on the substrate 100.

  The piezoelectric transformer device 1 </ b> A is formed by mounting the piezoelectric transformer 1 on a substrate 100. Mounting electrodes 101, 102, 103, and 104 are provided on the substrate 100. The mounting electrodes 101 and 102 are connected to an output circuit that outputs an AC voltage (not shown). The mounting electrodes 103 and 104 are connected to an output side rectifying / smoothing circuit that rectifies and smoothes the voltage.

  The input side first external electrode 11, the input side second external electrode 12, the output side first external electrode 13, and the output side second external electrode 14 are soldered to the mounting electrodes 101, 102, 103, and 104, respectively. At this time, the electrodes 11, 12, 13, and 14 are soldered at the node points P1 and P2 described with reference to FIG. By soldering at the node points P <b> 1 and P <b> 2, even if the piezoelectric transformer 1 is mounted on the substrate 100, the vibration of the piezoelectric body 10 is not hindered.

  The mounting electrode 101 corresponds to a “first mounting electrode” according to the present invention, and the mounting electrode 102 corresponds to a “second mounting electrode” according to the present invention. The mounting electrode 103 corresponds to a “third mounting electrode” according to the present invention, and the mounting electrode 104 corresponds to a “fourth mounting electrode” according to the present invention.

(Embodiment 2)
The piezoelectric transformer 2 according to the second embodiment is different from the first embodiment in the shape of the internal electrodes provided in the input region 10 </ b> A of the piezoelectric body 10. Hereinafter, the difference will be described.

  4A is a plan view of the piezoelectric transformer 2 according to the second embodiment, and FIG. 4B is a perspective view. 5A is a cross-sectional view taken along line VA-VA in FIG. 4A, FIG. 5B is a cross-sectional view taken along line VB-VB in FIG. 4A, and FIG. 4A is a cross-sectional view taken along line VC-VC in FIG. 4A, and FIG. 5D is a cross-sectional view taken along line VD-VD in FIG. 4 (A) and 4 (B) are perspective views of the inside of the piezoelectric body 10.

  An input-side first external electrode 21, an input-side second external electrode 22, an output-side first external electrode 23, and an output-side second external electrode 24 are provided on the first surface S1 of the input region 10A. Yes. The input-side first external electrode 21, the input-side second external electrode 22, the output-side first external electrode 23, and the output-side second external electrode 24 have a rectangular shape having a main surface composed of a short side and a long side. The electrodes 21, 22, 23, and 24 are provided on the first surface S1 of the piezoelectric body 10 so that the long sides coincide with the X-axis direction and the short sides coincide with the Y-axis direction.

  The arrangement of the electrodes 21, 22, 23, and 24 is the same as that of the electrodes 11, 12, 13, and 14 according to the first embodiment. Thereby, the input side first external electrode 21 and the input side second external electrode 22 can be easily separated from the output side first external electrode 23 and the output side second external electrode 24, and insulation between the electrodes can be maintained. . Further, by forming the external electrodes on the same surface of the piezoelectric body 10, the piezoelectric transformer 2 can be easily mounted on a substrate (not shown).

  A plurality of input side first internal electrodes 211 and a plurality of input side second internal electrodes 221 are provided in the input region 10A. As shown in FIG. 5A, the input-side first internal electrode 211 has a main surface that is substantially the same shape as the cross-sectional shape of the piezoelectric body 10, and is electrically connected to the input-side first external electrode 21. That is, the input-side first external electrode 21 and the input-side first internal electrode 211 form electrodes having the same potential. An insulating film 25 (for example, a glass member) 25 having a dielectric constant lower than that of the piezoelectric body 10 is provided between the input-side second external electrode 22 and the input-side first internal electrode 211. As shown in FIG. 5B, the input-side second internal electrode 221 has a main surface that is substantially the same shape as the cross-sectional shape of the piezoelectric body 10 and is electrically connected to the input-side second external electrode 22. That is, the input-side second external electrode 22 and the input-side second internal electrode 221 form electrodes having the same potential. An insulating film (for example, a glass member) 26 is provided between the input side first external electrode 21 and the input side second internal electrode 221.

  The input-side first internal electrodes 211 and the input-side second internal electrodes 221 are alternately provided along the X-axis direction so that the normal direction of the main surface is the X-axis direction.

  In the output region 10B, a plurality of output-side first internal electrodes 231 and a plurality of output-side second internal electrodes 241 are provided. As shown in FIG. 5C, the output-side first internal electrode 231 has a circular main surface and is electrically connected to the output-side first external electrode 23. That is, the output side first external electrode 23 and the output side first internal electrode 231 form electrodes of the same potential. As shown in FIG. 5D, the output-side second internal electrode 241 has a circular main surface and is electrically connected to the output-side second external electrode 24. That is, the output-side second external electrode 24 and the output-side second internal electrode 241 form electrodes having the same potential. Note that the circular main surface of the output-side first internal electrode 231 and the circular main surface of the output-side second internal electrode 241 have substantially the same size.

  The input-side first internal electrode 131 and the input-side second internal electrode 141 are alternately provided along the X-axis direction so that the normal direction of the main surface is the X-axis direction.

  In the present embodiment, the main surfaces of the internal electrodes 211 and 221 provided in the input region 10A on the high-voltage side have substantially the same shape as the cross-sectional shape of the piezoelectric body 10, and the main surfaces of the internal electrodes 231 and 241 provided in the output region 10B on the low-voltage side. The surface is circular. This makes it difficult for cracks to enter the ceramic bodies of the input region 10A and the output region 10B. The reason will be described below.

  FIG. 6 is a diagram for explaining the reason why cracks occur in the piezoelectric body. The white arrow in FIG. 6 indicates the expansion / contraction direction of the piezoelectric body, and the black arrow indicates the electric field direction. FIG. 6 shows the structure of the input area or output area of a general piezoelectric transformer.

  A plurality of plate-like internal electrodes 107 and 108 are alternately arranged in the piezoelectric body of the piezoelectric transformer. The plurality of internal electrodes 107 are connected to a common electrode 106A, and the plurality of internal electrodes 108 are connected to a common electrode 106B. When this configuration is, for example, an input region, an electric field is generated between the internal electrodes 107 and 108 when a voltage is applied between the common electrodes 106A and 106B. As a result, the region A of the piezoelectric body shown in FIG. 6 extends in the polarization direction due to the inverse piezoelectric effect, as indicated by the white arrow.

  An electric field is also generated in the regions B and D between the internal electrode 107 and the electrode 106B and the region C between the internal electrode 108 and the electrode 106A. As a result, the areas B, C, and D of the piezoelectric body contract in the polarization direction due to the inverse piezoelectric effect, as indicated by the white arrows. As described above, since the region A and the regions B, C, and D expand and contract in opposite directions, cracks are easily generated in the piezoelectric body. The same applies when the configuration of FIG. 6 is an output region.

  Here, the output region 10B of the piezoelectric transformer 1 according to the present embodiment is on the low pressure side. For this reason, the distance between the electrodes of the internal electrodes 231 and 241 provided in the output region 10B is short. That is, the distance between the electrodes 107 and 108 in the region A shown in FIG. 6 is short. Since the distance between the electrodes 107 and 108 is short, even if the distance between the electrodes in the regions B, C, and D is shortened, the electric field is unlikely to concentrate between the electrodes in the regions B, C, and D.

  Since the main surfaces of the internal electrodes 231 and 241 are circular, the distance between the output-side first internal electrode 231 and the output-side second external electrode 24 (see FIG. 5C) and the output-side second internal electrode The distance between 241 and the output-side first external electrode 23 (see FIG. 5D) is longer than the distance between the electrodes 107 and 108. As described above, on the low-pressure side, even if the distance between the electrodes in the regions B, C, and D is shortened, the piezoelectric body does not crack, and the electric field distribution is locally concentrated on the main surfaces of the internal electrodes 231 and 241. It is possible to make it difficult to form a circle.

  The input region 10A of the piezoelectric transformer 1 is on the high voltage side. For this reason, the distance between the electrodes of the internal electrodes 211 and 221 provided in the input region 10A is long. That is, the distance between the electrodes 107 and 108 in the region A shown in FIG. 6 is long. If the distance between the electrodes 107 and 108 is long, the electric field strength becomes low, so that the electric field may concentrate on the regions B, C, and D. Therefore, it is necessary to increase the distance between the electrodes in the regions B, C, and D. However, if the distance between the electrodes in the regions B, C, and D is increased, the facing area of the electrodes 107 and 108 becomes too small. Therefore, in the input region 10A on the high voltage side of the piezoelectric transformer 1, the main surfaces of the internal electrodes 211 and 221 are substantially the same as the cross section of the piezoelectric body 10, and the input side second external electrode 22 and the input side first internal electrode 211 are made. Insulating films (for example, glass members) 25, 26 having a dielectric constant lower than that of the piezoelectric body 10 are provided between the two layers 221. By providing the low dielectric constant insulating films 25 and 26, it is possible to suppress the concentration of the electric field between the input-side second external electrode 22 and the input-side first internal electrodes 211 and 221. As a result, it is possible to suppress the occurrence of cracks in the regions B, C, and D. Thereby, the piezoelectric transformer 2 excellent in element strength can be realized.

(Embodiment 3)
FIG. 7 is a perspective view of the piezoelectric transformer 3 according to the third embodiment. FIG. 7 is a perspective view of the inside of the piezoelectric body 30. The piezoelectric transformer 3 according to the present embodiment is formed by providing the piezoelectric transformer 2 according to the second embodiment symmetrically.

  The piezoelectric transformer 3 according to the third embodiment is assumed to vibrate in the length direction (hereinafter referred to as the X-axis direction) in the (4λ / 2) resonance mode. Here, λ is one wavelength of vibration in the X-axis direction. Therefore, the length of the piezoelectric body 30 included in the piezoelectric transformer 3 in the X-axis direction is (4λ / 2).

  The piezoelectric body 30 is formed with primary-side input areas 30A and 30C and secondary-side output areas 30B and 30D. Specifically, the output region 30B, the input region 30A, the input region 30C, and the output region 30D are arranged in this order along the X-axis direction of the piezoelectric body 30. The piezoelectric transformer 3 according to the present embodiment receives AC voltage from the input areas 30A and 30C, transforms the voltage, and outputs it from the output areas 30B and 30D. That is, the input areas 30A and 30C are the primary side, and the output areas 30B and 30D are the secondary side. The input areas 30A and 30C and the output areas 30B and 30D are each polarized in the X-axis direction. The polarization direction may be the same direction or the reverse direction.

  The input area 30A corresponds to a “first primary side” according to the present invention. The output region 30B corresponds to a “first secondary side portion” according to the present invention. The input area 30C corresponds to a “second primary side portion” according to the present invention. The output region 30D corresponds to a “second secondary side portion” according to the present invention.

  An input side first external electrode 31 and an input side second external electrode 32 are formed on the first surface along the XY axis direction in the input region 30 </ b> A of the piezoelectric body 30. The output side first external electrode 33 and the output side second external electrode 34 are formed on the first surface of the output region 30B. An input-side third external electrode 35 and an input-side fourth external electrode 36 are formed on the first surface of the input region 30C. An output side third external electrode 37 and an output side fourth external electrode 38 are formed on the first surface of the output region 30D.

  Each of the external electrodes 31 to 38 has a rectangular shape having a main surface composed of a long side and a short side. Each of the electrodes 31 to 38 is provided on the first surface of the piezoelectric body 30 so that the long side coincides with the X-axis direction and the short side coincides with the Y-axis direction. Specifically, the external electrodes 33, 31, 35, and 37 are provided along one long side of the first surface of the piezoelectric body 30. The external electrodes 34, 32, 36 and 38 are provided along the other long side of the first surface of the piezoelectric body 30. The external electrodes 33 and 34, the external electrodes 31 and 32, the external electrodes 35 and 36, and the external electrodes 37 and 38 are opposed to each other along the Y-axis direction.

  By arranging the electrodes as described above, the primary-side external electrodes 31, 32, 35, and 36 can be easily separated from the secondary-side external electrodes 33, 34, 37, and 38, and insulation between the electrodes can be achieved. Can keep. Further, by forming the external electrodes 31 to 38 on the same surface of the piezoelectric body 30, the piezoelectric transformer 3 can be easily mounted on a substrate (not shown).

  In addition, each electrode arranged as described above is provided at a position corresponding to the node point where the vibration displacement of the piezoelectric body 30 is the smallest, as in the first embodiment. When the piezoelectric transformer 3 is mounted, the piezoelectric transformer 3 is supported and wired at a position (node point) having the smallest vibration displacement, so that the piezoelectric body 30 is not obstructed and is not disturbed after mounting. It is possible to prevent the connection reliability from being deteriorated due to the displacement of.

  The input-side first external electrode 31 corresponds to a “first external electrode” according to the present invention, and the input-side second external electrode 32 corresponds to a “second external electrode” according to the present invention. The output-side first external electrode 33 corresponds to a “third external electrode” according to the present invention, and the output-side second external electrode 34 corresponds to a “fourth external electrode” according to the present invention. The input-side third external electrode 35 corresponds to a “fifth external electrode” according to the present invention. The input-side fourth external electrode 36 corresponds to a “sixth external electrode” according to the present invention. The output-side third external electrode 37 corresponds to a “seventh external electrode” according to the present invention. The output-side fourth external electrode 38 corresponds to an “eighth external electrode” according to the present invention.

  A plurality of input side first internal electrodes 311 and a plurality of input side second internal electrodes 321 are provided in the input region 30A. The input side first internal electrode 311 is electrically connected to the input side first external electrode 31, and is insulated from the input side second external electrode 32 by an insulating film 32A. The input-side second internal electrode 321 is electrically connected to the input-side second external electrode 32, and is insulated from the input-side first external electrode 31 by an insulating film 31A. The input-side first internal electrode 311 and the input-side second internal electrode 321 have the same shape as the input-side first internal electrode 211 and the input-side second internal electrode 221 of the piezoelectric transformer 2 according to the second embodiment. And the input side 1st internal electrode 311 and the input side 2nd internal electrode 321 are alternately provided along the X-axis direction so that the normal line direction of a main surface may turn into an X-axis direction.

  In the output region 30B, a plurality of output-side first internal electrodes 331 and a plurality of output-side second internal electrodes 341 are provided. The output side first internal electrode 331 is electrically connected to the output side first external electrode 33, and the output side second internal electrode 341 is electrically connected to the output side second external electrode 34. The output-side first internal electrode 331 and the output-side second internal electrode 341 have the same shape as the output-side first internal electrode 331 and the output-side second internal electrode 341 of the piezoelectric transformer 2 according to the second embodiment. And the output side 1st internal electrode 331 and the output side 2nd internal electrode 341 are alternately provided along the X-axis direction so that the normal line direction of a main surface may turn into an X-axis direction.

  A plurality of input side third internal electrodes 351 and a plurality of input side fourth internal electrodes 361 are provided in the input region 30C. The input-side third internal electrode 351 is electrically connected to the input-side third external electrode 35, and is insulated from the input-side fourth external electrode 36 by an insulating film 36A. The input-side fourth internal electrode 361 is electrically connected to the input-side fourth external electrode 36, and is insulated from the input-side third external electrode 35 by an insulating film 35A. The input side third internal electrode 351 and the input side fourth internal electrode 361 have the same shape as the input side first internal electrode 311 and the input side second internal electrode 321. The input-side third internal electrode 351 and the input-side fourth internal electrode 361 are alternately provided along the X-axis direction so that the normal direction of the main surface is the X-axis direction.

  In the output region 30D, a plurality of output-side third internal electrodes 371 and a plurality of output-side fourth internal electrodes 381 are provided. The output-side third internal electrode 371 is electrically connected to the output-side third external electrode 37, and the output-side fourth internal electrode 381 is electrically connected to the output-side fourth external electrode 38. The output side third internal electrode 371 and the output side fourth internal electrode 381 have the same shape as the output side first internal electrode 331 and the output side second internal electrode 341. The output-side third internal electrode 371 and the output-side fourth internal electrode 381 are alternately provided along the X-axis direction so that the normal direction of the main surface is the X-axis direction.

  The input-side first internal electrode 311 corresponds to a “first internal electrode” according to the present invention. The input-side second internal electrode 321 corresponds to a “second internal electrode” according to the present invention. The output-side first internal electrode 331 corresponds to a “third internal electrode” according to the present invention. The output-side second internal electrode 341 corresponds to a “fourth internal electrode” according to the present invention. The input-side third internal electrode 351 corresponds to a “fifth internal electrode” according to the present invention. The input-side fourth internal electrode 361 corresponds to a “sixth internal electrode” according to the present invention. The output-side third internal electrode 371 corresponds to a “seventh internal electrode” according to the present invention. The output-side fourth internal electrode 381 corresponds to an “eighth internal electrode” according to the present invention.

  When an AC voltage is applied to the input-side first external electrode 31 and the input-side second external electrode 32, and the input-side third external electrode 35 and the input-side fourth external electrode 36, the piezoelectric transformer 3 outputs the first output-side first electrode. The transformed and stepped down voltage is output from the external electrode 33 and the output-side second external electrode 34, and from the output-side third external electrode 37 and the output-side fourth external electrode 38.

  As described above, the piezoelectric transformer 3 according to the present embodiment is configured so that the vibrations are symmetrical with respect to the central portion of the piezoelectric body 30. And by arrange | positioning input area 30A, 30C inside, the vibration energy of input area 30A, 30C can be efficiently transmitted to output area 30B, 30D. As a result, the piezoelectric transformer 3 can be efficiently transformed.

DESCRIPTION OF SYMBOLS 1, 2, 3 ... Piezoelectric transformer 1A ... Piezoelectric transformer device 10, 30 ... Piezoelectric body 10A, 30A, 30C ... Input region 10B, 30B, 30D ... Output region 11, 21, 31 ... Input side 1st external electrode 12, 22 , 32 ... input-side second external electrodes 13, 23, 33 ... output-side first external electrodes 14, 24, 34 ... output-side second external electrode 35 ... input-side third external electrode 36 ... input-side fourth external electrode 37 Output third external electrode 38 Output fourth external electrode 25, 26, 31A, 32A, 35A, 36A ... Insulating film 100 ... Substrate 101, 102, 103, 104 ... Mounting electrodes 106A, 106B ... Common electrode 107 , 108 ... internal electrodes 111, 211, 311 ... first input internal electrodes 121, 221, 321 ... second input internal electrodes 131, 231, 331 ... first output internal electrodes 141, 24 , 341 ... output side second internal electrode 351 ... input side third internal electrode 361 ... input side fourth internal electrode 371 ... output side third internal electrode 381 ... output side fourth internal electrode P1 ... first node point P2 ... first 2 node point S1 ... 1st surface

Claims (8)

Of the first external electrode, the second external electrode, the third external electrode, and the fourth external electrode provided in the piezoelectric body, the first external electrode and the second external electrode, or the third external electrode and the third external electrode. In the piezoelectric transformer in which the voltage is excited on the other by applying a voltage to one of the four external electrodes,
The piezoelectric body having a rectangular first surface;
A plurality of first internal electrodes provided in the piezoelectric body and connected to the first external electrodes;
A plurality of second internal electrodes provided in the piezoelectric body and connected to the second external electrodes;
A plurality of third internal electrodes provided in the piezoelectric body and connected to the third external electrodes;
A plurality of fourth internal electrodes provided in the piezoelectric body and connected to the fourth external electrodes;
With
The first external electrode, the second external electrode, the third external electrode and the fourth external electrode are insulated from each other and provided on the first surface of the piezoelectric body;
The first external electrode and the second external electrode are arranged along one side direction of the first surface of the piezoelectric body,
The third external electrode and the fourth external electrode are arranged along the one side direction of the first surface of the piezoelectric body,
The first external electrode and the third external electrode are arranged along a direction orthogonal to the one side direction of the first surface of the piezoelectric body,
The second external electrode and the fourth external electrode are arranged along a direction orthogonal to the one side direction of the first surface of the piezoelectric body.
Piezoelectric transformer. The first internal electrode, the second internal electrode, the third internal electrode, and the fourth internal electrode are planar electrodes, and the normal directions of the principal surfaces of the planar electrodes coincide with each other.
The piezoelectric transformer according to claim 1. The piezoelectric body has a rectangular parallelepiped shape having a long side in the normal direction of the main surface.
The piezoelectric transformer according to claim 2. The first external electrode and the second external electrode are high-voltage side electrodes,
The third external electrode and the fourth external electrode are low-voltage side electrodes,
The first internal electrode and the second internal electrode are planar electrodes having a main surface having the same shape as a cross section orthogonal to the long side of the piezoelectric body,
The third internal electrode and the fourth internal electrode are planar electrodes having a circular main surface,
The piezoelectric transformer according to claim 3. The first external electrode and the second external electrode are a primary electrode pair,
The third external electrode and the fourth external electrode are secondary electrode pairs.
The piezoelectric transformer according to any one of claims 1 to 4. The piezoelectric body includes a first secondary side, a first primary side, a second primary side, and a second secondary arranged in a direction along the one side direction of the first surface. Have sides,
The first internal electrode, the second internal electrode, the first external electrode, and the second external electrode are provided on the first primary side portion of the piezoelectric body,
The third internal electrode, the fourth internal electrode, the third external electrode, and the fourth external electrode are provided on the first secondary side portion of the piezoelectric body,
A fifth external electrode and a sixth external electrode provided on the first surface located on the second primary side of the piezoelectric body;
A seventh external electrode and an eighth external electrode provided on the first surface located on the second secondary side of the piezoelectric body;
A plurality of fifth internal electrodes provided on the second primary side portion of the piezoelectric body and connected to the fifth external electrodes;
A plurality of sixth internal electrodes provided on the second primary side of the piezoelectric body and connected to the sixth external electrode;
A plurality of seventh internal electrodes provided on the second secondary side portion of the piezoelectric body and connected to the seventh external electrodes;
A plurality of eighth internal electrodes provided on the second secondary side of the piezoelectric body and connected to the eighth external electrode;
Further comprising
The fifth external electrode and the sixth external electrode are arranged along the one side direction of the first surface of the piezoelectric body,
The seventh external electrode and the eighth external electrode are arranged along the one side direction of the first surface of the piezoelectric body,
The fifth external electrode and the seventh external electrode are arranged along a direction orthogonal to the one side direction of the first surface of the piezoelectric body,
The sixth external electrode and the eighth external electrode are arranged along a direction orthogonal to the one side direction of the first surface of the piezoelectric body.
The piezoelectric transformer according to claim 5. A piezoelectric transformer according to any one of claims 1 to 6;
The piezoelectric body vibrates in a thickness longitudinal vibration mode having a thickness along a direction along the first surface,
A substrate on which the piezoelectric body is mounted;
Further comprising
The substrate is
A first mounting electrode on which the first external electrode is mounted;
A second mounting electrode on which the second external electrode is mounted;
A third mounting electrode on which the third external electrode is mounted;
A fourth mounting electrode on which the fourth external electrode is mounted;
Have
A part of each of the first mounting electrode, the second mounting electrode, the third mounting electrode, and the fourth mounting electrode is:
Coincides with the node point when the mounted piezoelectric body vibrates,
Piezoelectric transformer device. The first mounting electrode and the second mounting electrode are formed at positions that coincide with the first node point,
The third mounting electrode and the fourth mounting electrode are formed at positions that coincide with the second node point.
The piezoelectric transformer device according to claim 7.

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