JP2012119882A - Vibration device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration device in which the displacement of a vibrator is hardly restrained and which can obtain a large displacement amount without causing the increase in the number of components and the number of processing steps.SOLUTION: A vibration device 1 includes: a support sheet 3 stuck onto a diaphragm 2; and a frame body 4 stuck on an extension part 3B that is located outside of a diaphragm lamination part 3A, on which the diaphragm is stuck, of the support sheet 3 at an interval from the outer peripheral edge of the diaphragm 2. An opening of the frame body 4 has a polygonal shape, and the thickness of parts of the support sheet stuck onto the frame body 4 at center parts of sides 4a-4d of the opening is thicker than the thickness of parts of the support sheet stuck onto the frame body 4 at corner parts 4e-4h of the opening of the frame body 4.

Description

  The present invention relates to a vibration device having a structure in which a diaphragm made of, for example, a piezoelectric diaphragm is attached to a frame body via a support sheet, and more specifically, a vibration in which the shape of the opening of the frame body is a polygon. Relates to the device.

  2. Description of the Related Art Conventionally, piezoelectric sounders, piezoelectric speakers, and the like are used in mobile phones and various electronic devices to generate sound and vibration.

  For example, Patent Literature 1 below discloses a piezoelectric acoustic component shown in an exploded perspective view in FIG. In the piezoelectric acoustic component 101, a metal plate 103 drawn into a cap shape is fixed on a substrate 102.

  On the upper surface of the metal plate 103, a plurality of slits 103a are arranged in a rectangular frame shape. The piezoelectric diaphragm 104 is joined to the upper surface of the metal plate 103 at a portion surrounded by the plurality of slits 103a. A portion between adjacent slits 103 a and 103 a, that is, a portion where no slit is formed is located in the vicinity of a corner portion of the rectangular piezoelectric diaphragm 104. Along with the vibration of the piezoelectric diaphragm 104, the metal plate portion surrounded by the plurality of slits 103a is greatly displaced. Therefore, a large sound can be obtained.

  On the other hand, the following Patent Document 2 discloses a piezoelectric speaker shown in FIGS. 11 (a) and 11 (b). In the piezoelectric speaker 111, the piezoelectric element 112 is bonded to the upper surface of the diaphragm 113 made of metal. The diaphragm 113 is affixed on a resin plate 114 as a damper member. The resin plate 114 is fixed to the supports 115 and 116 at a pair of opposing side portions of the resin plate 114. That is, the resin plate 114 having a damping property is supported by the supports 115 and 116 so as not to hinder the vibration of the piezoelectric element 112 and the diaphragm 113.

Japanese Patent Laid-Open No. 11-355892 Japanese Patent Laid-Open No. 9-271096

  In the piezoelectric acoustic component 101 described in Patent Document 1, since the plurality of slits 103a are formed in the metal plate 103, displacement due to the piezoelectric effect can be increased and a large sound pressure can be obtained. However, the cap-shaped metal plate 103 had to be prepared by drawing. In addition, the slit 103a must be filled with a sealing material in order to separate the air chambers. Accordingly, there are problems that the machining process is complicated and the number of parts increases.

  On the other hand, in the piezoelectric speaker 111 described in Patent Document 2, a pair of long side portions of the resin plate 114 are supported by the supports 115 and 116, but the resin plate 114 is supported on the pair of short sides. Absent. Therefore, on the pair of short sides of the resin plate 114, it is necessary to increase the support strength using a sealing material. As a result, the number of parts increases, and the machining process becomes complicated. In addition, since the resin plate 114 is firmly supported on the pair of long sides, the displacement tends to be suppressed on the pair of long sides. Therefore, there is a possibility that the displacement of the vibrating body including the piezoelectric element 112 and the diaphragm 113 may be reduced.

  An object of the present invention is to solve the above-mentioned disadvantages of the prior art, to prevent displacement of the vibrating body from being suppressed, to obtain a large displacement amount, and to provide without increasing the number of parts and the number of processing steps. An object of the present invention is to provide a vibration device capable of performing

  The vibration device according to the present invention includes a vibration plate, a vibration plate laminated portion that is attached to the vibration plate, a vibration plate lamination portion that is attached to the vibration plate, and an extension portion that protrudes outside the vibration plate lamination portion. And a frame that is affixed to an extension of the support sheet and that is spaced from the outer peripheral edge of the diaphragm. In the present invention, the frame has a plurality of sides and a polygonal opening in which a portion where adjacent sides are connected is a corner, and the frame in the corner of the support sheet The thickness of the support sheet is from the center of the side of the opening of the frame so that the holding strength by is higher than the holding strength of the support sheet by the frame at the center of the side of the opening. The thickness is increased continuously or stepwise toward the corner of the frame.

  In a specific aspect of the vibration device according to the present invention, an interval between the diaphragm and the opening of the frame is relatively wide at the center of the side of the opening, and the corner portion of the frame Is relatively narrow.

  In another specific aspect of the vibration device according to the present invention, the opening of the frame is rectangular. A frame having a rectangular opening can be easily obtained by simple processing.

  In the present invention, the planar shape of the diaphragm is not particularly limited, but in still another specific aspect of the present invention, it is a rectangular plate shape. Accordingly, it is possible to use a rectangular plate-shaped piezoelectric vibrator that is widely used.

  In still another specific aspect of the vibration device according to the present invention, the diaphragm is a piezoelectric vibrator.

  In still another specific aspect of the vibration device according to the invention, the piezoelectric vibrator includes a metal plate and a piezoelectric element bonded to one surface of the metal plate.

  In still another specific aspect of the vibration device according to the present invention, the support sheet is made of a synthetic resin film. In the case of a support sheet made of a synthetic resin film, the thickness of the support sheet can be increased stepwise or continuously by laminating a plurality of synthetic resin films.

  In the vibration device according to the present invention, the support sheet is affixed to the frame body, but the holding strength at the corner portion of the opening portion of the frame body is maintained at the center of the side of the opening portion of the frame body. The thickness of the support sheet is increased continuously or stepwise from the center of the side of the opening of the frame toward the corner so as to be higher than the holding strength of the support sheet by the frame. Therefore, the displacement amount of the vibration part where the diaphragm and the support sheet are laminated can be increased. Therefore, a large sound pressure and a large vibration can be obtained.

  Moreover, since the vibration device of the present invention only has a support structure in which a support sheet is attached to a frame, it does not increase the number of parts. Moreover, the complexity of the processing steps can be avoided. Therefore, a vibration device having a large amount of displacement can be provided at low cost.

(A) And (b) is a top view of the vibration device which concerns on one Embodiment of this invention, and sectional drawing of the part in alignment with the BB line in (a), (c) is used. It is front sectional drawing of a piezoelectric element. (A) And (b) is each typical top view for demonstrating thickness distribution of the support film in the vibration apparatus of one Embodiment of this invention, (c) is CC in (b). It is sectional drawing of the part which follows a line. It is a typical perspective view which shows the displacement distribution of the vibration apparatus prepared for the comparison. It is a typical perspective view for demonstrating the displacement distribution of the vibration apparatus which concerns on one Embodiment of this invention. It is a figure which shows the relationship between the area | region and thickness of a support sheet in the vibration apparatus prepared as one Embodiment and comparative example of this invention. It is a typical top view for explaining thickness distribution in a vibration device of one embodiment of the present invention. (A) And (b) is each typical top view for demonstrating distribution of the thickness of the support sheet in the vibration apparatus of other embodiment of this invention. It is front sectional drawing for demonstrating the modification of the support sheet used by this invention. It is front sectional drawing for demonstrating the further another example of the diaphragm used with the vibration apparatus of this invention. It is a disassembled perspective view of the conventional piezoelectric electroacoustic transducer. (A) And (b) is a perspective view which shows an example of the conventional piezoelectric speaker, and sectional drawing of the part in alignment with the BB line in (a).

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

  Fig.1 (a) is a top view which shows the vibration apparatus which concerns on one Embodiment of this invention, (b) is sectional drawing of the part in alignment with the BB line in (a).

  The vibration device 1 according to the present embodiment includes a vibration plate 2, a support sheet 3 attached to the vibration plate 2, and a frame body 4 disposed so as to surround the support sheet 3.

  The diaphragm 2 has a rectangular plate shape. In FIG. 1B, a part of the diaphragm 2 is schematically shown, but in actuality, the diaphragm 2 is formed on both surfaces of the multilayer piezoelectric body 2a and the multilayer piezoelectric body 2a. It has electrodes 2b and 2c. The multilayer piezoelectric body 2a has a piezoelectric layer composed of two or more PZTs.

  Adjacent piezoelectric layers are polarized in the opposite direction in the thickness direction. Therefore, by applying an alternating electric field from the electrodes 2b and 2c, the diaphragm 2 is excited in the bending vibration mode. That is, the diaphragm 2 is a piezoelectric vibrator in the present embodiment.

  The structure of the piezoelectric vibrator is not limited to that using the multilayer piezoelectric body 2a shown in FIG. For example, a unimorph type piezoelectric vibrator in which a piezoelectric layer 2e and an electrode 2f polarized in the thickness direction are stacked on a metal plate 2d, such as a diaphragm 2A shown in FIG. Furthermore, in the present invention, the diaphragm 2 may be a vibrating body other than the piezoelectric vibrator.

  As shown in FIGS. 1A and 1B, the diaphragm 2 is attached to the upper surface of the support sheet 3. This affixing can be performed using an appropriate bonding material such as an adhesive.

  The support sheet 3 is connected to the diaphragm laminated portion 3A to which the rectangular plate-like diaphragm 2 is attached, and the diaphragm laminated portion 3A, and has a rectangular frame shape leading to the outside of the diaphragm laminated portion 3A. And an extension 3B. The outer portion of the rectangular frame-shaped extension 3 </ b> B is fixed by the frame body 4.

  In this embodiment, the frame body 4 has a rectangular frame-like planar shape. That is, the frame 4 has a rectangular opening. The rectangular opening has a pair of long sides 4a and 4b facing each other and a pair of short sides 4c and 4d facing each other. Adjacent sides, that is, a part where the sides 4a and 4c are connected is defined as a first corner portion 4e. Further, the portion where the side 4b and the side 4c are connected is connected to the second corner portion 4f, and the portion where the side 4a and the side 4d are connected is connected to the third corner portion 4g and the side 4d and the side 4b are connected. Let the part which exists be the 4th corner part 4h.

  The frame 4 has metal plates 4i and 4j. The metal plates 4i and 4j are bonded together so as to sandwich the support sheet 3. This bonding can be performed using an appropriate bonding material such as an adhesive.

  Note that the frame body 4 is not limited to metal, and can be formed of other rigid materials such as ceramics.

  In the present embodiment, the metal plate 4i and the metal plate 4j have the same planar shape, but may have different planar shapes. For example, the metal plate 4j may protrude outward from the metal plate 4i, and electrical connection or the like may be performed at the protruding portion.

  The support sheet 3 is made of a synthetic resin film. More specifically, as will be described later, the support sheet 3 is formed by laminating a plurality of synthetic resin films. But the support sheet 3 may be formed with not only a synthetic resin film but a metal plate.

  In the vibration device 1 according to the present embodiment, when the vibration plate 2 made of the piezoelectric vibrator is excited in the bending mode, the vibration plate 2 is supported by a flexible support sheet 3. Is not so hindered. In particular, the feature of the present embodiment is that the thickness of the support sheet 3 is partially different, whereby a large amount of displacement can be obtained. This will be described more specifically with reference to FIGS.

  In the vibration device 1 of the present embodiment, the support sheet 3 has a thickness distribution. FIG. 2A is a plan view of the vibration device 1 schematically showing the thickness distribution in the support sheet 3. FIG. 2B is a bottom view of the vibration device 1. In FIG. 2B, the thickness distribution of the support sheet 3 is schematically shown. That is, the support sheet 3 has the thickest region 3a in the vicinity of the first to fourth corner portions 4e to 4h of the frame body 4 described above, and the regions 3b, the thickness of which gradually decreases as the distance from the region 3a increases. 3c, 3d and 3e.

  In order to form such regions 3a to 3e, in this embodiment, as shown in FIG. 2C, synthetic resin films 31 to 35 are laminated in the region 3a. And in the area | region 3b, the synthetic resin film layers 32-35, ie, the synthetic resin film of 4 layers, are laminated | stacked. In the region 3c, the three synthetic resin film layers 33 to 35 are laminated, and in the region 3d, the synthetic resin film layers 34 and 35 are laminated.

  In the region 3e, only a single synthetic resin film layer 35 exists. Thus, the thickness of the support sheet 3 in the regions 3a to 3e is made different by changing the number of laminated synthetic resin films in the regions 3a to 3e.

  Therefore, in the part affixed to the frame 4 of the support sheet 3, the opening part of the frame 4 of the support sheet 3 is larger than the thickness of the support sheet part affixed to the center part of edge | side 4a-4d. The thickness of the portion pasted on the corner portions 4e to 4h, that is, the region 3a is increased. In addition, since a plurality of synthetic resin films 31 to 35 are used as described above, in this embodiment, from the support sheet portion attached to the central portion of the sides 4a to 4d to the corner portions 4e to 4h. The thickness of the support sheet 3 is gradually increased toward the pasted support sheet portion.

  Further, as shown in FIG. 2 (c), the thickness of the support sheet 3 from the center portion of the support sheet 3 toward the first corner portion 4e in the diagonal direction of the support sheet 3 is also increased from the region 3e. The thickness increases toward the region 3d, the region 3c, the region 3b, and the region 3a.

  In this embodiment, since the thickness of the support sheet 3 is set as described above, the holding strength of the support sheet 3 by the frame body 4 at the corner portion of the frame body 4 is the center of the side of the opening of the frame body 4. The holding strength of the support sheet 3 by the frame 4 in the part is set higher.

  In the vibration device 1 of the present embodiment, since the support sheet 3 has the thickness distribution, a large amount of displacement can be obtained. This will be described based on a specific experimental example.

  In this experimental example, the diaphragm 2 is made of PZT, and a laminated piezoelectric body having eight piezoelectric layers of 15.6 mm in length × 12 mm in transverse wave × 110 μm in thickness is used.

  The frame 4 was formed by laminating metal plates 4i and 4j having a thickness of 0.2 mm.

  The opening of the frame 4 was a rectangular opening with sides 4a and 4b having a length of 16.6 mm, 4c and 4d having a length of 13 mm.

  As the said support sheet 3, the following 1st-5th synthetic resin films 31-35 were comprised with the laminated body.

First synthetic resin film 31: thickness 20 μm
Second synthetic resin film 32: thickness 10 μm
Third synthetic resin film 33: thickness 10 μm
Fourth synthetic resin film 34: thickness 20 μm
Fifth synthetic resin film 35: thickness 140 μm

  In addition, all the 1st-5th synthetic resin films 31-35 consist of ethylene propylene rubber-type resin. Moreover, the 1st-5th synthetic resin films 31-35 were bonded together through the silicon-type adhesive layer which can disregard thickness substantially.

  For comparison, in place of the support sheet 3, a comparative example was used in the same manner as in the above embodiment except that a support sheet having a constant thickness in all regions as shown by the broken line in FIG. 5 was used. A vibration device was prepared.

  FIG. 3 is a perspective view schematically showing a displacement shape by a finite element method when a voltage of 10 V is applied to the vibration device of the comparative example. FIG. 4 is a schematic perspective view showing a displacement shape by a finite element simulation of a vibration device prepared as an experimental example of the embodiment. 3 and 4 show the displacement shape of the opening surrounded by the frame 4. That is, the support sheet 3 vibrates together with the diaphragm 2 but is restrained by the frame body 4. Therefore, the displacement shape shown in FIGS. 3 and 4 shows the displacement shape of the structure including the diaphragm 2 and the support sheet 3 in the opening of the frame body 4.

  The numerical values in FIG. 3 and FIG. 4 indicate the standardized displacement amount at the portion where the support sheet 3 is attached to the sides 4 a and 4 d of the opening of the frame body 4.

  As is clear from the comparison between FIG. 3 and FIG. 4, it can be seen that a larger displacement amount can be obtained according to the embodiment than in the comparative example. That is, it can be seen that the corner portion surrounded by the circle X shown by the broken line in FIG. 3 is relatively greatly displaced in the minus direction. On the other hand, as shown in FIG. 4, in the above-described embodiment, it is understood that the displacement in the minus direction in the portion surrounded by the circle Y indicated by the broken line, that is, the corner portion is very small.

  In the corner portions 4e to 4h in FIG. 6, that is, the portion surrounded by the circle Y indicated by the broken line, the displacement is very small, and the displacement in the minus direction is particularly small. On the other hand, the amount of displacement is large at the center of the sides 4a to 4d surrounded by the circle Z. This is because the support sheet 3 having the thickness distribution is used. Therefore, in the vibration device 1 of the present embodiment, the displacement amount of the structure in which the diaphragm 2 is joined to the support sheet 3 can be greatly increased, and a large sound pressure can be obtained.

  As described above, a large amount of displacement can be obtained in the present embodiment simply by giving the support sheet 3 a thickness distribution. Therefore, it is possible to provide a vibration device that can obtain a large sound pressure without increasing the number of parts and the complexity of the assembly process.

  FIGS. 7A and 7B are a schematic plan view and a schematic bottom view for explaining the vibration device according to the second embodiment of the present invention.

  7A and 7B, the thickness distribution of the support sheet 3 is schematically shown as in FIGS. 2A and 2B. That is, the thicknesses of the regions 3a to 3e are different as in the first embodiment. The difference between the second embodiment and the first embodiment is that the planar shape of the frame 4B is different, and the other points are the same as in the first embodiment.

  The opening of the frame 4B has a substantially rectangular shape. That is, the opening swells outward at the center of the sides 4a to 4d. Therefore, the distance between the diaphragm 2 and the frame 4 is relatively larger than the corner portions 4e to 4h at the center of the sides 4a to 4d. In other words, the distance between the diaphragm 2 and the frame body 4 becomes smaller from the center of the sides 4a to 4d toward the corners 4e to 4h.

  As described above, the distance between the diaphragm 2 and the frame 4 is reduced on the side of the corners 4e to 4h as compared with the central part of the sides 4a to 4d, thereby reducing the displacement of the support sheet 3 at the corner. be able to. Moreover, the displacement at the center side of the sides 4a to 4d can be further increased, and thereby the displacement amount of the structure in which the diaphragm 2 is joined to the support sheet 3 can be effectively increased. Thus, not only the support sheet 3 has a thickness distribution but also the displacement amount can be further increased by adjusting the distance between the frame 4 and the diaphragm 2.

  In the first and second embodiments, the thickness of the support sheet 3 is changed stepwise, but as shown in FIG. 8, the thickness of the support sheet 3 continuously changes from the region 3a toward the region 3e. May be. But it is difficult to obtain the support sheet 3 in which such thickness changes continuously. Therefore, as in the first and second embodiments, in the support sheet 3 made of a laminated body, a structure in which the number of laminated layers is different in the regions 3a to 3e is desirable.

  In each embodiment mentioned above, although the opening part of the frame 4 had a rectangular planar shape, you may have other polygonal shapes, such as pentagons and hexagons other than a rectangle. In any case, if the thickness of the support sheet portion attached to the corner portion in the polygon is higher than the thickness of the support sheet portion attached to the central portion of the plurality of sides in the polygon, A large amount of displacement can be obtained as in the above embodiment.

  In the first to third embodiments, the diaphragm 2 has a rectangular plate shape, but may have a planar shape other than the rectangular plate shape, for example, a circular shape.

DESCRIPTION OF SYMBOLS 1 ... Vibration apparatus 2 ... Vibration plate 2A ... Vibration plate 2a ... Laminated piezoelectric body 2b, 2c ... Electrode 2d ... Metal plate 2e ... Piezoelectric layer 2f ... Electrode 3 ... Support sheet 3A ... Vibration plate laminated part 3B ... Extension part 3a -3e ... area 4 ... frame 4B ... frame 4a-4d ... side 4e ... first corner 4f ... second corner 4g ... third corner 4h ... fourth corner 4i, 4j ... metal Plate 31 ... 1st synthetic resin film 32 ... 2nd synthetic resin film 33 ... 3rd synthetic resin film 34 ... 4th synthetic resin film 35 ... 5th synthetic resin film

Claims (6)

A diaphragm,
A support sheet that is affixed to the diaphragm, and that has a diaphragm laminate that is affixed to the diaphragm, and an extension that projects to the outside of the diaphragm laminate;
A frame that is affixed to the extension of the support sheet and that is provided at an interval from the outer periphery of the diaphragm;
The frame has a plurality of sides and a polygonal opening in which a portion where adjacent sides are connected is a corner, and the holding strength by the frame in the corner of the support sheet is The thickness of the support sheet is from the center of the side of the opening of the frame to the corner of the frame so that the holding strength of the support sheet by the frame at the center of the side of the opening is higher. A vibration device that is thickened continuously or stepwise toward the part side.   The distance between the diaphragm and the opening of the frame is relatively wide at the center of the side of the opening and relatively narrow at the corner of the frame. The vibration device described.   The vibration device according to claim 1, wherein the opening of the frame is rectangular.   The vibration device according to claim 1, wherein the vibration plate has a rectangular plate shape.   The vibration device according to claim 1, wherein the vibration plate is a piezoelectric vibrator. The vibration device according to claim 1, wherein the support sheet is made of a synthetic resin film.

Images