JP2006211413A - Piezoelectric diaphragm - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To reduce in thickness a piezoelectric diaphragm for a sounding body, to improve the reliability of the lead-out of an electrode, to simplify a manufacturing process, and to reduce the number of materials. <P>SOLUTION: A piezoelectric element 16 is configured such that electrode layers 20A, 20B, 24A and 24B are formed on both principal sides of a piezoelectric layer 18A. A pair of the electrode layers on the same side of the piezoelectric layer 18A are arranged in point symmetry with each other, and the electrode layers adjacent to each other in thickness directions are arranged so that polarities of applied voltages to the layers are opposite to each other. The electrode layers to which the voltages with the same polarities are applied are connected in the thickness directions by means of through-holes 22A, 26A. A piezoelectric element 28 is basically configured similar to the piezoelectric element 16. Thus, electrode layers 20A to 20D receive the same potential and can be led out of a diaphragm 12A, and also the electrode layers 24A to 24D receive the same potential and can be led out of a diaphragm 12B. The lead-out of the electrodes from the diaphragms 12A, 12B enables the thinning of the entire piezoelectric diaphragm. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a piezoelectric diaphragm for a sounding body and an electronic device using the same, and more specifically to a reduction in thickness of the piezoelectric diaphragm and the electronic device.

  Piezoelectric sounding bodies (piezoelectric diaphragms) are widely used as simple electroacoustic conversion means, and in recent years, they are frequently used as speakers and the like in the field of cellular phones and portable information terminals. As shown in an example in FIG. 14, the piezoelectric sounding body has a configuration in which piezoelectric elements 304 and 310 are bonded to both front and back surfaces of the diaphragm 302. The piezoelectric element 304 has a structure in which electrode layers 308A and 308B are formed on both front and back surfaces of the piezoelectric body 306, and is adhered to the surface of the diaphragm 302 made of metal or the like with a conductive adhesive or the like. The same applies to the other piezoelectric element 310, in which the electrode layers 308 </ b> C and 308 </ b> D are formed on both the front and back surfaces of the piezoelectric body 306.

The electrode layers 308A and 308D are drawn to the outside through conductive means such as lead wires 312A and 312B, respectively, and the other electrode layers 308B and 308C are at the same potential as the diaphragm 302, and are separated from the diaphragm 302. It is pulled out through the lead wire 312C. A structure similar to such an electrode lead structure is disclosed in, for example, Patent Document 1 below.
JP 2003-47092 A

  However, the background art as described above requires the lead wires 312A to 312C and the solders 314A to 314C in order to draw the electrodes to the outside. Among these, the solder connection portions of the lead wires 312A and 312B are provided on the electrode layers 308A and 308D on the surfaces of the piezoelectric elements 304 and 310, which increases the thickness of the piezoelectric sounding body 300 itself. For example, assuming that the thickness of the diaphragm 302 is 30 μm, the thickness of the piezoelectric elements 304 and 310 is 60 μm, and the height of the solders 314A and 314B at the connecting portions of the lead wires 312A and 312B is 160 μm, respectively. Becomes 470 μm. Of these, the total thickness of the solder connection portions of the lead wires 312A and 312B required for drawing out the electrodes is 320 μm, which occupies nearly 70% of the total thickness of the piezoelectric sounding body 300. In the background art, the lead wires 312A and 312B from the upper and lower surfaces are sufficiently reliable for a long period of intense piezoelectric driving because the lead wires 312A and 312B are not in close contact with the diaphragm 302. It may not be. Therefore, if an unnecessary thickness can be omitted by improving the electrode lead-out structure, it is advantageous for further promoting the thinning of the piezoelectric sounding body and the electronic equipment using the piezoelectric sounding body.

  The present invention focuses on the above points, and its purpose is to reduce the thickness of the piezoelectric diaphragm for the sounding body by improving the electrode structure, to improve the degree of freedom of mounting on the electronic device, and to reduce the thickness of the electronic device itself. It is to plan. Another object is to improve the reliability of electrode lead-out. Another object is to simplify the manufacturing process and reduce the material by improving the drawer structure.

  In order to achieve the above object, the present invention attaches a piezoelectric element comprising a piezoelectric layer and electrode layers provided on both principal surfaces so as to sandwich the piezoelectric layer to at least one surface of a diaphragm. A piezoelectric diaphragm for a sounding body, wherein the piezoelectric element has electrode layers on the same main surface arranged apart from each other in respective regions obtained by dividing the main surface of the piezoelectric layer into a plurality of portions. The signal voltages having the same polarity are applied to the electrode layers adjacent to each other on the same main surface and to the electrode layers adjacent to each other in the thickness direction via the piezoelectric layer. A plurality of connection conductors for connecting the applied electrode layers in the thickness direction of the piezoelectric layer are provided.

  Another invention is a piezoelectric diaphragm for a sounding body in which a piezoelectric element in which a plurality of piezoelectric layers and electrode layers provided on the main surface of the piezoelectric layer are alternately laminated is bonded to at least one surface of the diaphragm. In the piezoelectric element, the electrode layers on the same main surface are arranged apart from each other in respective regions obtained by dividing the main surface of the piezoelectric layer into a plurality of electrodes, and adjacent electrodes on the same surface. The electrode layers to which a signal voltage of the same polarity is applied are applied to the layers and the electrode layers adjacent to each other in the thickness direction via the piezoelectric layer, so that the signal voltages having the same polarity are applied to the piezoelectric layers. A plurality of connection conductors connected in the thickness direction of

  One of the main forms is that a pair of electrode layers on the same main surface of the piezoelectric element are point-symmetric about the substantially central portion of the piezoelectric layer and adjacent in the thickness direction via the piezoelectric layer. The electrode layers of the piezoelectric element are horizontally reversed, or the electrode layers on the same main surface of the piezoelectric element are arranged concentrically around a substantially central portion of the piezoelectric layer, and the piezoelectric layer A pair of electrode layers adjacent to each other in the thickness direction via a point has a point-symmetric shape.

  In another form, the extraction electrode of the diaphragm is divided at substantially the same position as the division position of the electrode layer on the same main surface of the piezoelectric element, and the piezoelectric element is divided into the divided parts. Each of the arranged electrode layers is conductively connected. More preferably, air or resin is provided between the divided portions of the extraction electrode of the diaphragm.

  According to still another embodiment, a plurality of conductive thin film layers that are conductively connected to each of a plurality of electrode layers divided and formed on the main surface of the piezoelectric layer of the piezoelectric element are provided on the main surface of the diaphragm. Features. More preferably, the electrode lead-out portion of the conductive thin film layer on the main surface of the diaphragm is formed wide.

  An electronic apparatus according to the present invention is characterized by using the piezoelectric diaphragm for a sounding body according to any one of claims 1 to 8. The above and other objects, features and advantages of the present invention will become apparent from the following detailed description and the accompanying drawings.

  According to the present invention, a piezoelectric element including at least one piezoelectric layer and electrode layers provided on both main surfaces of the piezoelectric layer is bonded to at least one surface of the diaphragm, and the same main surface of the piezoelectric element The upper electrode layers are arranged apart from each other in respective regions obtained by dividing the main surface of the piezoelectric layer into a plurality of portions, and the electrode layers adjacent to each other on the same surface and the thickness direction through the piezoelectric layers. The electrode layers to which signal voltages of the same polarity are applied are connected to each other in the thickness direction by a plurality of connecting conductors so that the signal voltages having different polarities are applied to the adjacent electrode layers. . For this reason, all the electrode layers can be drawn from the diaphragm, so that the overall thickness can be reduced and the reliability can be improved. Further, the simplification of the drawer structure can simplify the manufacturing process and reduce the material.

  Hereinafter, the best mode for carrying out the present invention will be described in detail based on examples.

  First, Embodiment 1 of the present invention will be described with reference to FIGS. FIG. 1 is an exploded perspective view of the present embodiment. FIG. 2A is an external perspective view showing the whole of the present embodiment, and FIG. 2B is a plan view of (A) as viewed from above the piezoelectric element 16. 3A is a cross-sectional view of FIG. 2A taken along line # A- # A and viewed in the direction of the arrow. FIG. 3B is a cross-sectional view of FIG. It is sectional drawing cut | disconnected along the #B line | wire and seeing in the arrow direction. As shown in these drawings, the piezoelectric diaphragm 10 has piezoelectric elements 16 and 28 bonded to the front and back of diaphragms 12A and 12B made of a flexible thin plate having conductivity such as 42Ni alloy or phosphor bronze. The bimorph structure is formed in a substantially rectangular shape as a whole. The diaphragms 12A and 12B are spaced apart from each other at a predetermined interval, and are insulated by air in the gap to form first and second lead electrodes, respectively. Alternatively, the central portion of one diaphragm 12 is divided, and a sealing member 14 such as rubber or insulating resin is provided in the divided portion (see FIG. 2B) to prevent electrical contact between the diaphragms 12A and 12B. You may make it do.

  The piezoelectric element 16 is provided with electrode layers 20A, 20B, 24A, and 24B on both principal surfaces of a piezoelectric layer 18A formed of piezoelectric ceramics such as PZT, and the electrode layer 20A and the electrode layer sandwiching the piezoelectric layer 18A. 24B is opposed to each other, and the electrode layer 24A and the electrode layer 20B are opposed to each other. As the electrode layers 20A, 20B, 24A, and 24B, for example, a baked electrode layer containing Ag or an Ag / Pd alloy is used. First, on one main surface of the substantially rectangular piezoelectric layer 18A, a pair of electrode layers 20A and 24A to which signal voltages having different polarities are applied are respectively divided into two regions by dividing the main surface into two by a straight line. It is formed so as to be separated from each other. These electrode layers 20A and 24A are in a point-symmetric relationship with the approximate center of the piezoelectric layer 18A as the center. Similarly, a pair of electrode layers 20B and 24B to which signal voltages having different polarities are applied are formed on the other main surface of the piezoelectric layer 18A. These electrode layers 20B and 24B have a point-symmetric relationship. Further, the electrode layers 20B and 24B are in a horizontally reversed relationship with the electrode layers 20A and 24A on one main surface of the piezoelectric layer 18A. That is, the signal voltages applied to the electrode layers 20A and 20B have the same polarity, and the signal voltages applied to the electrode layers 24A and 24B have the same polarity.

  The electrode layers 20A and 20B are connected approximately linearly in the thickness direction of the piezoelectric element 16 through through holes 22A, and the electrode layers 24A and 24B are connected approximately linearly in the thickness direction through through holes 26A. Then, the electrode layer 20B is bonded with a conductive adhesive (not shown) so that the electrode layer 20B is connected to the surface of one diaphragm 12B and the electrode layer 24B is connected to the surface of the other diaphragm 12A.

  The other piezoelectric element 28 basically has the same configuration, and a pair of electrode layers 20E and 24E to which signal voltages having different polarities are applied are formed on one main surface of the piezoelectric layer 18E. The The electrode layers 20E and 24E are point contrasts. Similarly to the piezoelectric element 16, the pair of electrode layers 20F and 24F are formed on the other main surface of the piezoelectric layer 18E. The electrode layer 20E and the electrode layer 24F face each other with the piezoelectric layer 18E interposed therebetween. In addition, the electrode layer 24E and the electrode layer 20F face each other. The electrode layers 20E and 20F are connected in the thickness direction through the through holes 22B, and the electrode layers 24E and 24F are connected through the through holes 26B.

  In the piezoelectric diaphragm 10 having the above structure, the electrode layers 20A, 20B, 20E, and 20F are electrically connected through the through holes 22A and 22B and the diaphragm 12B, and all have a common potential. . The electrode layers 24A, 24B, 24E, and 24F are electrically connected via the through holes 26A and 26B and the diaphragm 12A, and all have a common potential. In such a piezoelectric diaphragm 10, as shown in FIG. 2, electrodes are drawn from the diaphragms 12 </ b> A and 12 </ b> B through lead wires 32 </ b> A and 32 </ b> B and connected to a power supply 30. For example, the signal voltage is applied such that one diaphragm 12A is positive and the other diaphragm 12B is negative. That is, it is possible to draw out the electrodes from the diaphragms 12A and 12B sandwiched between them, instead of pulling out the electrodes from the surfaces of the piezoelectric elements 16 and 28. Therefore, compared with the background art described above, the thickness of the solder 34A, 34B at the connection portion of the lead wires 32A, 32B does not affect the overall thickness, and the piezoelectric diaphragm 10 itself is significantly thinned. be able to. At this time, the reliability of the electrode lead-out may be improved by surface-bonding the lead-out portions from the diaphragms 12A and 12B with a wide width.

  As described above, according to the first embodiment, a piezoelectric element including a pair of electrode layers that are disposed apart from each other in each of the regions obtained by dividing the main surface of the piezoelectric layer into a plurality of regions. 16 and 28 are bonded to both surfaces of the diaphragms 12A and 12B, and the electrode layers on the same surface of the piezoelectric layer and the electrode layers adjacent in the thickness direction via the piezoelectric layer have different polarities. The electrode layer is disposed so that a signal voltage is applied. Of the provided electrode layers, the electrode layers 20A and 20B to which signal voltages of the same polarity are applied are connected in the thickness direction through the through holes 22A, and the electrode layers 20E and 20F are connected in the thickness direction through the through holes 22B. . Further, since the other electrode layers 24A and 24B are connected in the thickness direction through the through holes 26A and the electrode layers 24E and 24F are connected in the thickness direction through the through holes 26B, all the electrode layers are drawn out of the diaphragm 12A. And 12B, the overall thickness can be reduced. Further, the simplification of the drawer structure can simplify the manufacturing process and reduce the material. Further, the reliability of the drawer can be improved by bonding the wide drawer part to the diaphragms 12 and 12B.

  Next, Embodiment 2 of the present invention will be described with reference to FIGS. In addition, the same code | symbol shall be used for the component which is the same as that of Example 1 mentioned above, or respond | corresponds (it is the same also about a following example). FIG. 4 is an exploded perspective view of the present embodiment. FIG. 5 is an external perspective view showing the entirety of the present embodiment. The first embodiment is an example in which piezoelectric elements having a single piezoelectric layer are provided on both the front and back surfaces of the diaphragm. However, in this embodiment, the piezoelectric element has a laminated structure having a plurality of piezoelectric layers. It is. As shown in FIGS. 4 and 5, the piezoelectric diaphragm 40 has a bimorph structure in which the piezoelectric elements 42 and 44 are bonded to the front and back of the diaphragms 12A and 12B, respectively, and is formed in a substantially rectangular shape as a whole. ing. As in the first embodiment, the diaphragms 12A and 12B are spaced apart at a predetermined interval, and are insulated by air in the gap to constitute first and second lead electrodes, respectively. Alternatively, the central portion of one diaphragm 12 is divided, and a seal member 14 such as rubber or insulating resin is provided in the divided portion (see FIG. 5) to prevent electrical contact between the diaphragms 12A and 12B. May be.

  The piezoelectric element 42 has a structure in which piezoelectric layers (piezoelectric ceramics) 18A to 18C formed of PZT or the like and electrode layers 20A to 20D and 24A to 24D are alternately stacked, and the electrode layers are opposed to each other with the piezoelectric layers interposed therebetween. It has become. As the electrode layers 20A to 20D and 24A to 24D, for example, baking type conductive layers such as Ag and Ag / Pd alloy are used. First, a pair of electrode layers 20A and 24A to which signal voltages having different polarities are applied are provided on one main surface (the upper surface in FIG. 4) of the substantially rectangular piezoelectric layer 18A. Each of the divided areas is formed so as to be separated from each other. These electrode layers 20A and 24A are in a point-symmetric relationship with the approximate center of the piezoelectric layer 18A as the center. Similarly, a pair of electrode layers 20B and 24B to which signal voltages having different polarities are applied are formed on the surface (the upper surface in FIG. 4) of the second piezoelectric layer 18B. These electrode layers 20B and 24B have a point-symmetric relationship. Further, the electrode layers 20B and 24B are in a horizontally reversed relationship with the electrode layers 20A and 24A on the surface of the piezoelectric layer 18A. That is, the polarity of the signal voltage applied to the electrode layers 20A and 20B is the same, and the polarity of the signal voltage applied to the electrode layers 20B and 24B is the same.

  Similarly, a pair of electrode layers 20C and 24C are formed on the surface of the third piezoelectric layer 18C. Further, a pair of electrode layers 20D and 24D are formed on the back surface of the piezoelectric layer 18C. As described above, the electrode layers formed on the same piezoelectric layer are point-symmetric, and a pair of electrode layers adjacent to each other in the thickness direction are arranged so as to be reversed in the left-right direction. Each time, the shape and position are approximately the same. For example, the electrode layers 20A and 24A and the electrode layers 20C and 24C substantially coincide, and the electrode layers 20B and 24B and the electrode layers 20D and 24D substantially coincide.

  The electrode layers 20A to 20D as described above are connected substantially linearly in the thickness direction of the piezoelectric element 42 by the through holes 22A, and the electrode layers 24A to 24D are connected substantially linearly in the thickness direction by the through holes 26A. . Then, the electrode layer 20D is bonded so as to contact the surface of one diaphragm 12B, and the electrode layer 24D is contacted to the surface of the other diaphragm 12A.

  The other piezoelectric element 44 has basically the same configuration, and a pair of electrode layers 20E and 24E to which signal voltages having different polarities are applied are formed on the surface of the first piezoelectric layer 18E. The The electrode layers 20E and 24E are point-symmetric. Hereinafter, a pair of electrode layers 20F and 24F, 20G and 24G and 20H are formed on the surface of the second piezoelectric layer 18F and on the front and back surfaces of the third piezoelectric layer 18G, respectively, similarly to the piezoelectric element 16 described above. And 24H are formed, and the electrode layers are opposed to each other with the piezoelectric layer interposed therebetween. The electrode layers 20E to 20H are connected in the thickness direction through the through holes 22B, and the electrode layers 24E to 24H are connected through the through holes 26B.

  In the piezoelectric diaphragm 40 having the above structure, the electrode layers 20A to 20H are electrically connected via the through holes 22A and 22B and the diaphragm 12B, and all have a common potential. The electrode layers 24A to 24H are electrically connected through the through holes 26A and 26B and the diaphragm 12A, and all have a common potential. In such a piezoelectric diaphragm 40, as in the first embodiment described above, electrodes are drawn from the diaphragms 12A and 12B serving as the first and second lead electrodes and connected to the power supply 30 (see FIG. 2). . For example, the signal voltage is applied such that one diaphragm 12A is positive and the other diaphragm 12B is negative. That is, the electrodes can be drawn out from the diaphragms 12A and 12B sandwiched between the piezoelectric elements 42 and 44 instead of being drawn out from the surface of the piezoelectric elements 42 and 44. In comparison with the piezoelectric diaphragm 40 itself, the thickness can be significantly reduced. At this time, the reliability of the electrode lead-out may be improved by surface-bonding the lead-out portions from the diaphragms 12A and 12B with a wide width.

  As described above, according to the second embodiment, the piezoelectric elements 42 and 44 in which the piezoelectric layers and the pair of electrode layers spaced apart on the same surface of the piezoelectric layers are alternately stacked, the vibration plates 12A and The signal voltages having different polarities are applied to the electrode layers on the same surface of the piezoelectric layer and to the electrode layers adjacent to each other in the thickness direction via the piezoelectric layer. An electrode layer is disposed. Then, among the stacked electrode layers, electrode layers 20A to 20D and 20E to 20H to which signal voltages of the same polarity are applied are connected in the thickness direction through through holes 22A and 22B, and the other electrode layers 24A to 24D, Since 24E to 24H are connected in the thickness direction through the through holes 26A and 26B, all electrode layers can be drawn from the diaphragms 12A and 12B, and the overall thickness can be reduced. Further, the simplification of the drawer structure can simplify the manufacturing process and reduce the material. Further, the reliability of the drawer can be improved by bonding the wide drawer portion to the diaphragms 12A and 12B.

  Next, Embodiment 3 of the present invention will be described with reference to FIGS. FIG. 6 is an exploded perspective view showing the configuration of the present embodiment, and FIG. 7 is an external perspective view showing the entirety of the present embodiment. As shown in these drawings, the piezoelectric diaphragm 50 has a bimorph structure in which substantially circular piezoelectric elements 60 and 72 are bonded to both front and back surfaces of a substantially circular diaphragm 52, respectively. A part of the protrusion 52A is provided with a protrusion 52A protruding toward the outer peripheral side. Each of the piezoelectric elements 60 and 72 has a configuration using a single piezoelectric layer as in the first embodiment. That is, taking the piezoelectric element 60 as an example, a pair of electrode layers 64A and 66A to which signal voltages having different polarities are applied to one main surface of the piezoelectric layer 62A are provided in each region obtained by dividing the main surface into two. A pair of electrode layers 64 </ b> B and 66 </ b> B, which are formed so as to be separated from each other and to which signal voltages having different polarities are applied, are formed on the other main surface. The positional relationship between the electrode layers 64A, 64B, 66A, and 66B on the same main surface and the positional relationship with the piezoelectric layer 62A interposed therebetween are basically the same as those in the first embodiment, and the electrode layers 64A and 64B. Are connected through a through hole 68A, and the electrode layers 66A and 66B are connected through a through hole 70A. The other piezoelectric element 72 has basically the same configuration, and a pair of electrode layers 64C and 66C and electrode layers 64D and 66D are formed on the front and back surfaces of the piezoelectric layer 68B, respectively. 70B. In addition, as a material which comprises the piezoelectric elements 60 and 72, the thing similar to Example 1 mentioned above is applicable. In this embodiment, a piezoelectric element composed of a single piezoelectric layer is used. However, as in the second embodiment, a piezoelectric element having a multilayer structure having a plurality of piezoelectric layers may be used. .

  In the third embodiment, the configuration of the diaphragm is greatly different from the first embodiment described above. The diaphragm 52 of the present embodiment is made of, for example, a conductive Ag paste on the front and back surfaces of an insulating plate 54 made of an insulating material excellent in bending, for example, an insulating film such as PET (PolyEthylene Terephtalate). A pair of printed conductor patterns 56 and 57 and 58 and 59 are provided. The conductive Ag paste is an example, and a thin film conductor layer may be provided by a sputtering method or the like. The insulating plate 54 is provided with a protruding portion 52A that protrudes to the outer peripheral side in the extending direction of a straight line passing through the gap between the pair of printed conductor patterns (for example, 56 and 57). The printed conductor patterns 56 to 59 are connected to lead portions 56A to 59A formed on the surface of the protruding portion 52A, respectively. The printed conductor patterns 56 to 59 and the electrode layers 64B, 66B, 64C, and 66C of the piezoelectric elements 60 and 72 are bonded with a conductive adhesive (not shown), and a signal is transmitted via the lead portions 56A to 59A. The piezoelectric diaphragm 50 can be driven by applying a voltage. In the present embodiment, unlike the first and second embodiments described above, the diaphragm itself is not divided and formed, and instead, lead electrodes (printed conductor patterns) are formed separately.

  As described above, according to the present embodiment, the electrode layers 64B, 66B, 64C, and 66C provided in the regions that divide the main surfaces of the piezoelectric layers 62A and 62B into two substantially oscillate with an area substantially equal to these electrode layers. By adhering to the printed conductor patterns 56 to 59 of the plate 52, it is possible to combine the function of conductive connection and the function of displacement transmission by driving the piezoelectric elements 60 and 72. Thereby, in addition to the thinning effect shown in the first and second embodiments described above, the reliability of the conductive connection at the time of piezoelectric driving is enhanced, and the driving electrode is directly bonded to the diaphragm 52, thereby causing a large displacement. Obtainable. Although not shown, a conductive adhesive is applied to the gap portion by printing a resist layer in advance on the gap portion of the pair of printed conductor patterns (56 and 57 or 58 and 59) of the diaphragm 52. It is also possible to prevent the occurrence of a short circuit between the electrode layers due to the flow of. In addition, by applying an insulating adhesive in the gap portion, displacement transmission between the gap portion of the diaphragm 52 and the piezoelectric elements 60 and 72 can be made more reliable, and unnecessary sound caused by collision between the non-adhesive portions can be prevented. Generation may be prevented.

  Next, Embodiment 4 of the present invention will be described with reference to FIGS. FIG. 8 is an exploded perspective view showing the structure of the upper surface side of the present embodiment. FIG. 9A is an external perspective view showing the whole of the present embodiment, and FIG. 9B is a plan view of (A) as viewed from above. FIG. 10 is a main cross-sectional view of the present embodiment. FIG. 10A is a cross-sectional view of FIG. 9A cut along the line # C- # C and viewed in the direction of the arrow, FIG. FIG. 9B is a cross-sectional view of FIG. 9A cut along the line # D- # D and viewed in the direction of the arrow. As shown in these drawings, the piezoelectric diaphragm 80 according to the present embodiment has a plurality of piezoelectric elements 90 disposed on the surface of the diaphragm 82 and a plurality of piezoelectric elements 91 disposed on the back surface of the diaphragm 82. The structure of the piezoelectric element 90 is basically the same as that of the first embodiment described above, and a pair of electrode layers 94A and 96A and electrode layers 94B and 96B are formed on the front and back surfaces of the piezoelectric element 90, respectively. Yes. Similarly, a pair of electrode layers 94C and 96C and electrode layers 94D and 96D are formed on the front and back surfaces of the piezoelectric element 91, respectively.

  On the other hand, a pair of printed conductor patterns 84 and 86 extending in the arrangement direction of the piezoelectric elements 90 and 91 are formed on the front and back surfaces of the diaphragm 82, respectively. These printed conductor patterns 84 and 86 are provided with protruding portions 84A and 86B. The printed conductor patterns 84 and the printed conductor patterns 86 provided on the front and back surfaces of the diaphragm 82 are connected to each other through the through holes 84B and 86B in the lead portions 84A and 86A. . The piezoelectric elements 90 and 91 are disposed so as to straddle the pair of printed conductor patterns 84 and 86, respectively. As shown in FIG. 10A, the electrode layers 94A and 94B of the piezoelectric element 90 are connected in the thickness direction by through holes 98A and connected to one printed conductor pattern 86 on the surface side of the diaphragm 82. The electrode layers 94 </ b> C and 94 </ b> D of the piezoelectric element 91 are connected in the thickness direction by through holes 98 </ b> B and are connected to the printed conductor pattern 86 on the back side of the diaphragm 82. Similarly, as shown in FIG. 10B, the other electrode layers 96A and 96B of the piezoelectric element 90 are connected in the thickness direction by the through hole 100A, and are connected to the other printed conductor pattern 84 on the surface side of the diaphragm 82. Connected. The other electrode layers 96 </ b> C and 96 </ b> D of the piezoelectric element 91 are connected in the thickness direction through the through holes 100 </ b> B and connected to the other printed conductor pattern 84 on the back surface side of the diaphragm 82. The same applies to the other plurality of piezoelectric elements 90 and 91. Then, for example, by connecting the lead wires 102 and 104 to the lead portions 84A and 86B of the printed conductor patterns 84 and 86 connected on both the front and back surfaces of the vibration plate 82 with solders 106 and 108, the piezoelectric vibration plate 80 is connected. Signal voltage can be applied.

  In the fourth embodiment, similarly to the third embodiment described above, a plurality of piezoelectric elements 90 and 91 are provided on the front and back surfaces of the diaphragm 82 having the printed conductor patterns 84 and 86 formed on the main surface. It is what was pasted together. In this way, the plurality of piezoelectric elements 90 and 91 are bonded together with the conductive adhesive (not shown) along the strip-shaped printed conductor patterns 84 and 86 on the surface of the vibration plate 82, thereby electrically connecting the plurality of piezoelectric elements. The piezoelectric elements 90 and 91 and the printed conductor patterns 84 and 86 are connected to each other, and the function of transmitting the displacement of the piezoelectric elements 90 and 91 to the vibration plate 82 is obtained. be able to. Further, in addition to the effect of the third embodiment described above, even if a plurality of piezoelectric elements are provided on the vibration plate 82, an effect that wiring is not required can be obtained. Furthermore, since combinations of a plurality of types of piezoelectric elements can be freely performed, application to various electronic devices is possible. The piezoelectric elements 90 and 91 each use a single piezoelectric layer as in the first and third embodiments. However, as in the second embodiment, the electrode layers and the piezoelectric layers are alternately arranged. The same effect can be obtained by using a structure in which a plurality of layers are laminated. Although not shown in the figure, the printed conductor patterns 84 and 86 may be partially formed to be wide corresponding to the shape of the drive electrodes (electrode layers) of the piezoelectric elements 90 and 91. You may make it coat | cover the surface of the printed conductor pattern of the wiring part which connects between elements with an insulating layer.

  Next, Embodiment 5 of the present invention will be described with reference to FIGS. FIG. 11 is an exploded perspective view of the present embodiment. FIG. 12 is an external perspective view showing the entirety of the present embodiment, and FIG. 13 is an external perspective view of the diaphragm used in the present embodiment. As shown in these drawings, the piezoelectric diaphragm 200 has a bimorph structure in which substantially circular piezoelectric elements 218 and 230 are bonded to both front and back surfaces of a substantially circular diaphragm 202, respectively, and is the same as in the third embodiment. In addition, a part of the outer periphery of the diaphragm 202 is provided with a protruding portion 202A that protrudes toward the outer peripheral side. Each of the piezoelectric elements 218 and 230 has a structure using a single piezoelectric layer as in the first embodiment. Of course, as in the second embodiment, electrode layers and piezoelectric layers are alternately arranged. A structure in which a plurality of layers are stacked may be used. In the fifth embodiment, the method of dividing the electrode layers of the piezoelectric elements 218 and 230 is different from the first to fourth embodiments described above. In other words, in the first to fourth embodiments, the electrode layers are arranged to be separated from each other in each region obtained by dividing the main surface of the piezoelectric layer into a plurality of straight lines. The electrode layers are arranged so as to be separated from each other in each region obtained by dividing the main surface into a plurality of concentric circles (two in the illustrated example).

  First, the diaphragm 202 will be described. As in the above-described third embodiment, a pair of conductive Ag pastes are used on the front and back surfaces of the insulating plate 204 made of a resin film such as PET (polyethylene terephthalate), respectively. The printed conductor patterns 206 and 208 and 210 and 212 are provided. The conductive Ag paste is an example, and the thin film conductor layer may be provided by a sputtering method or the like, as in the third embodiment. In addition, a part of the edge of the insulating plate 204 is provided with a protruding portion 202A that protrudes to the outer peripheral side in the extending direction of a straight line passing through the center of the insulating plate 204. The printed conductor patterns 206, 208, 210, and 212 are connected to lead portions 206A to 212A provided on the surface of the protruding portion 202A, respectively.

  The printed conductor patterns 206 and 208 on one main surface will be described in detail. These printed conductor patterns 206 and 208 are bounded by a circle that divides the main surface of the insulating plate 204 into an inner peripheral side and an outer peripheral side in the radial direction. Thus, they are arranged in the respective regions so as to be separated from each other. The inner peripheral printed conductor pattern 208 is connected to the lead-out portion 208A on the protruding portion 202A via a slit 207 provided in a part of the outer peripheral printed conductor pattern 206 in the circumferential direction. In the lead-out portion 208A, an insulating layer 214 for preventing a short circuit between the electrodes is provided at a portion facing the electrode layer 224B on the outer peripheral side of the piezoelectric element 218. In addition, by applying an adhesive to the facing portion, the displacement transmission between the insulating plate 204 and the piezoelectric element 318 is made more reliable, and the generation of unnecessary sound due to the collision between the non-bonded portions is prevented. May be. The pair of printed conductor patterns 210 and 212 provided on the other main surface of the insulating plate 204 has the same configuration, and the inner printed conductor pattern 212 is in the circumferential direction of the outer printed conductor pattern 210. Is connected to the lead-out portion 212A on the protruding portion 202A through a slit portion 209 provided in a part of the projection portion 202A. In the lead portion 212A, an insulating layer 216 for preventing a short circuit between the electrodes is provided at a portion facing the electrode layer 224C on the outer peripheral side of the piezoelectric element 230.

  Next, the piezoelectric element 218 has a structure in which electrode layers 222A, 224A, 222B, and 224B are provided on both main surfaces of a piezoelectric layer 220A formed of a piezoelectric ceramic such as PZT. As the electrode layers 222A, 224A, 222B, and 224B, for example, a baking type electrode layer containing Ag or an Ag / Pd alloy is used as in the above-described embodiment. A pair of electrode layers 222A and 224A to which signal voltages having different polarities are applied are formed on one main surface (upper surface side in the illustrated example) of the substantially circular piezoelectric layer 220A so that the main surface is concentrically divided into two. Each of the divided areas is formed so as to be separated from each other. These electrode layers 222A and 224A are disposed on the inner peripheral side and the outer peripheral side with a circle dividing the piezoelectric layer 220A in two in the radial direction as a boundary. Similarly, a pair of electrode layers 222B and 224B to which signal voltages having different polarities are applied are formed on the other main surface (lower surface side in the illustrated example) of the piezoelectric layer 220A. These electrode layers 222B and 224B have a substantially concentric relationship. In addition, the electrode layers 222B and 224B are in an inverted relationship with the upper electrode layers 222A and 224A. That is, the polarities of the signal voltages applied to the electrode layers 222A and 222B are the same, and the polarities of the signal voltages applied to the electrode layers 224A and 224B are the same.

  The electrode layers 222A and 222B are connected almost linearly in the thickness direction of the piezoelectric element 218 by a through hole 226A, and the electrode layers 224A and 224B are connected almost linearly in the thickness direction by a through hole 228A. A conductive adhesive (not shown) is connected so that the electrode layer 222B is connected to the printed conductor pattern 208 on the inner peripheral side of the surface of the diaphragm 202, and the electrode layer 224B is connected to the printed conductor pattern 206 on the outer peripheral side. Etc. are pasted together.

  The other piezoelectric element 230 has basically the same configuration, and a pair of electrode layers 222C and 224C to which signal voltages having different polarities are applied are formed on one main surface of the piezoelectric layer 220B. The The electrode layers 222C and 224C are in a concentric relationship. Similarly, a pair of electrode layers 222D and 224D to which signal voltages having different polarities are applied are formed on the other main surface of the piezoelectric layer 220B. The electrode layers 222C and 222D are connected in the thickness direction by through holes 226B, and the electrode layers 224C and 224D are connected in the thickness direction by through holes 228B. The electrode layer 222C is connected to the printed conductor pattern 212 on the inner peripheral side of the back surface of the diaphragm 202, and the electrode layer 224C is connected to the printed conductor pattern 210 on the outer peripheral side by a conductive adhesive (not shown). Can be pasted together. The piezoelectric diaphragm 200 having such a configuration is driven by applying a signal voltage via the lead portions 206A to 212A.

  As described above, according to Example 5, the pair of electrode layers disposed on the inner peripheral side and the outer peripheral side are separated from each other with the circle dividing the main surface of the piezoelectric layer in two in the radial direction as a boundary. The piezoelectric elements 218 and 230 provided on both main surfaces of the piezoelectric layer are bonded to both surfaces of the vibration plate 202, and the electrode layers on the same surface of the piezoelectric layers 218 and 230 and the piezoelectric layer are interposed therebetween. The electrode layers are arranged so that signal voltages having different polarities are applied to the electrode layers adjacent in the thickness direction. Of the provided electrode layers, the electrode layers 222A and 22B to which signal voltages of the same polarity are applied are connected in the thickness direction through the through holes 226A, and the electrode layers 222C and 222D are connected in the thickness direction through the through holes 226B. On the other hand, the other electrode layers 224A and 224B are connected in the thickness direction by the through holes 228A, and the electrode layers 224C and 224D are connected in the thickness direction by the through holes 228B. Can be performed from the printed conductor patterns 206 to 212 provided on the substrate, and the overall thickness can be reduced. Further, the simplification of the drawer structure can simplify the manufacturing process and reduce the material.

  Furthermore, since the electrode layers provided in the regions dividing the principal surfaces of the piezoelectric elements 218 and 230 into a plurality of areas are connected to the printed conductor patterns 206 to 212 of the diaphragm 202 with an area approximately equal to these electrode layers, The connection function and the displacement voltage function by driving the piezoelectric elements 218 and 230 are combined. Thereby, in addition to the effect of thinning, the reliability of the conductive connection at the time of piezoelectric driving is enhanced, and a large displacement can be obtained by directly bonding the driving electrode to the diaphragm 202.

  Furthermore, in the above-described first to fourth embodiments, a bilaterally symmetric vibration mode is obtained along a straight line that divides the main surface of the piezoelectric element into a plurality of portions, and mainly forms a piezoelectric diaphragm for a square plate-like sounding body. On the other hand, in the fifth embodiment, when driving the piezoelectric element, a concentric vibration mode is obtained as in the case of the vibration by the conventional piezoelectric diaphragm, and the piezoelectric element for the circular sound generator is obtained. It is suitable when configuring the diaphragm.

In addition, this invention is not limited to the Example mentioned above, A various change can be added in the range which does not deviate from the summary of this invention. For example, the following are also included.
(1) The materials, shapes, and dimensions shown in the above-described embodiments are examples, and can be appropriately changed so as to achieve the same effect.
(2) The number of stacked layers of the piezoelectric layer and the electrode layer is also arbitrary, and may be appropriately increased or decreased as necessary.
(3) In the fourth embodiment, the plurality of piezoelectric elements 90 and 91 are provided on the front and back surfaces of the diaphragm 82. However, this is also an example, and the number of piezoelectric elements may be appropriately increased or decreased as necessary.
(4) In the above embodiment, the overall shape of the piezoelectric diaphragm is substantially rectangular or substantially circular, but the shape can be appropriately changed as long as the same effect is obtained.
(5) Although the bimorph structure in which the piezoelectric elements are provided on both the front and back surfaces of the diaphragm is used in the above-described embodiment, the same effect can be obtained by a unimorph structure in which the piezoelectric elements are provided on only one of the front and back surfaces.
(6) In the above-described embodiment, the electrode layer is provided in each region obtained by dividing the main surface of the piezoelectric element into two parts, but this is also an example, and the number of divisions may be changed as appropriate so as to achieve the same effect. It's okay.
(7) Preferred examples of application of the piezoelectric diaphragm of the present invention include speakers of various electronic devices such as a mobile phone, a personal digital assistant (PDA), a voice recorder, and a PC (personal computer). It does not preclude application to various electronic devices.

  According to the present invention, a piezoelectric element including at least one piezoelectric layer and electrode layers provided on both main surfaces of the piezoelectric layer is bonded to at least one surface of the diaphragm, and the electrode layer is The main surface of the piezoelectric layer is spaced apart from each other in a plurality of divided regions, and electrode layers adjacent to each other on the same surface and electrode layers adjacent to each other in the thickness direction via the piezoelectric layer are arranged. The electrode layers to which the signal voltages having the same polarity are applied are connected in the thickness direction with a plurality of connecting conductors so that the signal voltages having different polarities are applied, and the electrode layers are drawn from the diaphragm. Therefore, it is suitable for the use of a piezoelectric diaphragm for a sound producing body that is required to be thin and an electronic device using the piezoelectric diaphragm.

It is a disassembled perspective view which shows the structure of Example 1 of this invention. It is a figure which shows the said Example 1, (A) is a perspective view which shows an external appearance, (B) is a top view. 2A and 2B are diagrams illustrating the first embodiment, in which FIG. 2A is a cross-sectional view of FIG. 2A cut along a line # A- # A, and FIG. 2B is a cross-sectional view of FIG. It is sectional drawing cut | disconnected along. It is a disassembled perspective view which shows the structure of Example 2 of this invention. It is a perspective view which shows the external appearance of the said Example 2. FIG. It is a disassembled perspective view which shows the structure of Example 3 of this invention. It is a perspective view which shows the external appearance of the said Example 3. FIG. It is a disassembled perspective view which shows a part of structure of Example 4 of this invention. It is a figure which shows the said Example 4, (A) is a perspective view which shows an external appearance, (B) is a top view. 9A and 9B are diagrams showing the fourth embodiment, in which FIG. 9A is a cross-sectional view of FIG. 9A cut along line # C- # C, and FIG. 9B is a cross-sectional view of FIG. 9A taken along line # D- # D. It is sectional drawing cut | disconnected along. It is a disassembled perspective view which shows the structure of Example 5 of this invention. It is a perspective view which shows the external appearance of the said Example 5. FIG. FIG. 6 is a perspective view illustrating an appearance of a diaphragm according to the fifth embodiment. It is a figure which shows an example of background art.

Explanation of symbols

10: Piezoelectric diaphragm 12, 12A, 12B: Diaphragm 14: Seal member 16, 28: Piezoelectric elements 18A-18C, 18E-18G: Piezoelectric layers 20A-20H, 24A-24H: Electrode layers 22A, 22B, 26A, 26B : Through hole 30: Power supply 32A, 32B: Lead wire 34A, 34B: Solder 40: Piezoelectric vibration plate 42, 44: Piezoelectric element 50: Piezoelectric vibration plate 52: Vibration plate 52A: Protruding portion 54: Insulating plates 56, 57, 58 , 59: Printed conductor pattern 56A, 57A, 58A, 59A: Lead-out portion 60, 72: Piezoelectric element 62A, 62B: Piezoelectric layer 64A-64D, 66A-66D: Electrode layer 68A, 68B, 70A, 70B: Through hole 80: Piezoelectric diaphragm 82: diaphragm 84, 86: printed conductor pattern 84A, 86A: drawer portion 84B, 6B: Through hole 90, 91: Piezoelectric element 92: Piezoelectric layer 94A to 94D, 96A to 96D: Electrode layer 98A, 98B, 100A, 100B: Through hole 102, 104: Lead wire 106, 108: Solder 200: Piezoelectric diaphragm 202: Diaphragm 202A: Protruding portion 204: Insulating plates 206, 208, 210, 212: Printed conductor patterns 206A, 208A, 210A, 212A: Lead portions 207, 209: Slit portions 214, 216: Insulating layers 218, 230: Piezoelectric Elements 220A, 220B: Piezoelectric layers 222A-222D, 224A-224D: Electrode layers 226A, 226B, 228A, 228B: Through hole 300: Piezoelectric sounding body 302: Vibration plate 304, 310: Piezoelectric element 306: Piezoelectric bodies 308A-308D: Electrode layers 312A-312C: Lead 314A~314C: solder

Claims (9)

A piezoelectric diaphragm for a sounding body in which a piezoelectric element including a piezoelectric layer and electrode layers provided on both main surfaces so as to sandwich the piezoelectric layer is bonded to at least one surface of the diaphragm. ,
In the piezoelectric element, the electrode layers on the same main surface are arranged apart from each other in respective regions obtained by dividing the main surface of the piezoelectric layer into a plurality of parts,
The same polarity signal voltage is applied to the electrode layers adjacent to each other on the same main surface and to the electrode layers adjacent to each other in the thickness direction via the piezoelectric layer. A plurality of connecting conductors for connecting the electrode layers to each other in the thickness direction of the piezoelectric layer,
A piezoelectric diaphragm characterized by comprising: A piezoelectric diaphragm for a sounding body in which a piezoelectric element in which a plurality of piezoelectric layers and electrode layers provided on the main surface of the piezoelectric layer are alternately laminated is bonded to at least one surface of the diaphragm,
In the piezoelectric element, the electrode layers on the same main surface are arranged apart from each other in respective regions obtained by dividing the main surface of the piezoelectric layer into a plurality of parts,
A signal voltage having the same polarity is applied to the electrode layers adjacent to each other on the same surface and to the electrode layers adjacent to each other in the thickness direction via the piezoelectric layer. A plurality of connecting conductors connecting the electrode layers in the thickness direction of the piezoelectric layer;
A piezoelectric diaphragm characterized by comprising:   The electrode layers on the same main surface of the piezoelectric element are point-symmetric with respect to the substantially central portion of the piezoelectric layer, and a pair of electrode layers adjacent in the thickness direction via the piezoelectric layer are horizontally reversed. The piezoelectric diaphragm according to claim 1, wherein the piezoelectric diaphragm has a shape.   The electrode layers on the same main surface of the piezoelectric element are arranged concentrically around the substantially central portion of the piezoelectric layer, and a pair of electrode layers adjacent in the thickness direction via the piezoelectric layer are dotted. The piezoelectric diaphragm according to claim 1, wherein the piezoelectric diaphragm has a symmetrical shape.   The extraction electrode of the diaphragm is divided at substantially the same position as the division position of the electrode layer on the same main surface of the piezoelectric element, and the electrode layer in which the piezoelectric element is divided and arranged in each divided part Each of these is electrically connected, The piezoelectric diaphragm in any one of Claims 1-4 characterized by the above-mentioned.   6. The piezoelectric diaphragm according to claim 5, wherein air or resin is provided between the divided parts of the lead electrode of the diaphragm.   2. A plurality of conductive thin film layers that are conductively connected to each of a plurality of electrode layers divided and formed on a main surface of a piezoelectric layer of the piezoelectric element are provided on the main surface of the diaphragm. The piezoelectric diaphragm in any one of -4.   8. The piezoelectric diaphragm according to claim 7, wherein the electrode lead-out portion of the conductive thin film layer on the main surface of the diaphragm is formed wide. An electronic apparatus using the piezoelectric diaphragm according to claim 1.

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