JP4124770B2 - Piezoelectric sounder - Google Patents

Description

The present invention relates to a piezoelectric sounder .

  Conventionally, a piezoelectric sounder that emits a buzzer sound for notifying a user of an operation state is attached to an electric device, for example, a digital camera. As electric equipment is miniaturized, the mounting location of the piezoelectric sounder is also limited, and is directly attached to the housing, for example. As a method of attaching this piezoelectric sounder to an electrical device, there is a method of attaching a piezoelectric sounder to a housing using a double-sided tape as shown in Patent Document 1.

In the piezoelectric sounder disclosed in Patent Document 1, a case and a diaphragm are bonded to one side of a double-sided tape, and the case is bonded to a housing on the other side of the double-sided tape to constitute a piezoelectric sounder.
JP-A-8-23598

  When the diaphragm is vibrated, a so-called standing wave is formed with one end and the other end of the fixed portion of the diaphragm as a fixed end and a central portion as an antinode, and a sound based on the standing wave is generated. However, in the configuration of the diaphragm shown in Patent Document 1, since it is suspended in the case by the double-sided tape, one end and the other end of the diaphragm are free ends and a good standing wave is formed in the diaphragm portion. The required sound may not be emitted from the diaphragm.

  In addition, the sound emitted from the diaphragm is resonated in the case to change the sound range and volume so that the user can easily hear it. Today, there are cases where the size required by the housing dimensions of electrical equipment is not satisfied.

  SUMMARY OF THE INVENTION An object of the present invention is to provide a piezoelectric sounder that can be miniaturized as a whole device and can generate a good sound, and an electric device using the piezoelectric sounder.

In order to achieve the above object, the present invention comprises a casing having a substantially annular mounting portion, and a conductive material having a first surface and a second surface, and an outer peripheral shape substantially the same as the outer peripheral shape of the mounting portion. A piezoelectric vibration element bonded to the second surface, an electrode bonded to both surfaces of the piezoelectric vibration element, and a first adhesive layer that adheres to the first surface of the vibration plate is provided on one surface side, A second adhesive layer that adheres to the mounting portion is provided on the other surface side, and is made of a cushioning material. And the diaphragm has a spacer sheet material mounted on the mounting portion via the spacer sheet material, and the housing has a sound emitting hole communicating with the through hole. is formed, the vibration plate is a piezoelectric sound mounted on the mounting portion through the spacer sheet material To provide.

According to the piezoelectric sounder having such a configuration, the vibration plate can vibrate as a standing wave having a joint at the spacer sheet material as a node. Therefore, sound can be suitably generated from the diaphragm. In addition, since the through hole of the spacer sheet material takes a shape covered with the diaphragm, a vacant space defined by the spacer sheet material and the diaphragm is formed. Therefore, by resonating the sound emitted from the diaphragm in the empty room, it is possible to approach a sound range and volume that can be easily audible to humans. Moreover, since the vacant space is defined by the spacer sheet material, the range and volume of the sound emitted from the piezoelectric sounder can be arbitrarily changed by setting the thickness of the spacer sheet material to an arbitrary thickness. In addition, since the vacant space is defined by the housing and the spacer sheet material, the volume of the sound emitted from the diaphragm can be increased.

In the piezoelectric sounder having the above configuration, the spacer sheet material is preferably made of a resin material, and more preferably made of foamed butyl rubber. The thickness of the spacer sheet material is preferably 0.5 mm or more.

  By using such a material, the spacer sheet material has a good cushioning performance, the amplitude can be increased without hindering the movement of the diaphragm, and a suitable audible sound range can be easily obtained. Further, since the thickness control can be made precise, the individual error of the vacant space defined by the diaphragm and the spacer sheet material is reduced, and a uniform product can be produced. Furthermore, a larger sound volume can be obtained by setting the thickness to 0.5 mm or more.

  Moreover, the 1st contact bonding layer may be intermittently provided in the opening periphery of the through-hole of the spacer sheet material.

  According to the piezoelectric sounder of the present invention, the entire device can be miniaturized and a good sound can be emitted.

  An electrical device using a piezoelectric sounder according to an embodiment of the present invention will be described with reference to FIGS. A piezoelectric sounder 1 shown in FIG. 1 mainly includes a piezoelectric diaphragm 3 and a spacer 6 arranged on one surface side of the piezoelectric diaphragm 3.

  The piezoelectric vibration plate 3 is composed of a substantially circular metal disc having conductivity. A piezoelectric vibration element 4 is provided on the other surface of the piezoelectric vibration plate 3. The piezoelectric vibration element 4 has a substantially circular disk shape and is formed with a diameter smaller than the outer diameter of the piezoelectric vibration plate 3. Electrodes 5 and 5 are provided on both surfaces of the piezoelectric vibration element 4. The electrodes 5 and 5 have a substantially circular disk shape and are formed with a diameter smaller than the outer diameter of the piezoelectric vibration element 4. A conductive wire 10 and a conductive wire 11 connected to a power source (not shown) are connected to the piezoelectric vibration plate 3 and the electrode 5 facing the piezoelectric vibration plate 3 with the piezoelectric vibration element 4 interposed therebetween. When a voltage is applied between the piezoelectric diaphragm 3 and the electrode 5, the piezoelectric vibration element 4 expands and contracts due to the piezoelectric effect, and the expansion and contraction causes the piezoelectric diaphragm 3 to vibrate and emit sound.

  The spacer 6 is formed by processing a resin sheet having a base of foamed butyl rubber into a disk shape having substantially the same diameter as the outer diameter of the piezoelectric diaphragm 3 and forming a substantially circular through hole 6a on the inside thereof. ing. Further, the thickness of the spacer 6 is at least 0.5 mm or more.

  On one surface of the spacer 6 facing the piezoelectric diaphragm 3, a first adhesive layer 7 </ b> A composed of an acrylic adhesive having good adhesion to a metal material is provided. Therefore, as shown in FIG. 2, the spacer 6 is bonded to the piezoelectric diaphragm 3 by bringing the first adhesive layer 7 </ b> A (FIG. 1) into contact with the piezoelectric diaphragm 3. By adhering the spacer 6 to the piezoelectric diaphragm 3, the through hole 6 a becomes an empty space that is defined by the piezoelectric diaphragm 3 and the spacer 6 and resonates the sound generated by the piezoelectric diaphragm 3. Therefore, the sound generated from the piezoelectric diaphragm 3 is resonated in the through hole 6a, and the volume is larger than the sound generated from the piezoelectric diaphragm 3.

  In general, the resonance characteristic, which is a characteristic of resonating sound emitted from the piezoelectric diaphragm, generally becomes better as the volume of the vacant chamber is larger. In this embodiment, the volume of the vacant space is determined by the product of the inner diameter of the through-hole 6a and the thickness of the spacer 6. When the inner diameter of the through-hole 6a is constant, the volume changes in direct proportion to the thickness of the spacer 6. Therefore, as the thickness of the spacer 6 increases, the resonated sound becomes more audible.

  Further, the amplitude efficiency of the piezoelectric diaphragm 3 is improved as the inner diameter of the through hole 6a is increased. Therefore, the inner diameter of the through hole 6 a is formed as close as possible to the outer diameter of the piezoelectric diaphragm 3. Specifically, the inner diameter of the through-hole 6a is formed so that at least the piezoelectric diaphragm 3 can be supported by the spacer 6, and the outer diameter of the piezoelectric diaphragm 3 is the material according to the present embodiment. About 70%. Further, the thickness of the spacer 6 and the thickness of the piezoelectric diaphragm 3 define the upper back of the piezoelectric sounder 1. However, since a case or the like is not required, the height can be made sufficiently low.

  Further, as shown in FIG. 3, a second adhesive layer 7B similar to the first adhesive layer 7A is also provided on the other surface of the spacer 6.

  A digital camera (not shown), which is an electric device to which the piezoelectric sounder 1 is attached, includes a substantially annular attachment portion 8 in the housing 2 as shown in FIG. A space 8 a defined by the mounting portion 8 and the housing 2 is defined inside the annular portion of the mounting portion 8. Further, the annular inner diameter of the mounting portion 8 is formed substantially the same as the inner diameter of the through hole 6a. A sound emitting hole 9 penetrating the inside and outside of the housing 2 is formed at a substantially central position in the attachment portion 8 of the housing 2.

  The piezoelectric sounder 1 is attached to the housing 2 by the second adhesive layer 7B and the attachment portion 8 coming into contact with each other and the spacer 6 being adhered to the attachment portion 8 (FIGS. 1 and 4). At this time, the spacer 6 and the attachment portion 8 are bonded so that the openings of the through hole 6a and the empty chamber 8a overlap each other. Thus, the piezoelectric diaphragm 3, the spacer 6, the attachment portion 8, and the housing 2 define a vacant chamber 13 including the through hole 6 a and the vacant chamber 8 a. The sound emitted from the piezoelectric diaphragm 3 is resonated in the vacant chamber 13 and is transmitted to the outside through the sound emitting hole 9. However, since the vacant chamber 13 is sufficiently wide, the sound passes through the through-hole 6a by the piezoelectric sounder 1 alone. It is even louder than the sound resonated as a vacant room.

  The piezoelectric sounder according to the present invention is not limited to the above-described embodiment, and various modifications and improvements can be made within the scope described in the claims. For example, the piezoelectric sounder 1 is attached to the annular attachment portion 8 of the housing 2, but the attachment portion 8 may be specified and attached on the surface of the housing 2 without providing an annular portion. In this case, by increasing the thickness of the spacer 6, it is possible to obtain the same resonance performance as when the spacer 6 is attached to the annular attachment portion 8 according to the present embodiment. Further, the material of the spacer 6 is not limited to the butyl rubber sheet, and for example, silicon rubber may be used. In short, it should be a material with cushioning properties.

  Further, the spacer 6, the first adhesive layer 7A, and the second adhesive layer 7B may be provided integrally in advance, for example, a double-sided tape of a base material having cushioning properties. The first adhesive layer 7 </ b> A may be provided intermittently on the periphery of the through hole 6 a of the spacer 6. In addition, electric devices are not limited to digital cameras, but are almost all electric products with a function that informs the user of the operating state with sound, such as mobile phones, game devices, DVD players, air conditioners, and remote controls used for these devices. Assumes everything.

The disassembled perspective view showing the piezoelectric sounder and electric equipment housing | casing which concern on embodiment of this invention. Sectional drawing of the II-II line | wire in FIG. 3 of the piezoelectric sounder which concerns on embodiment of this invention. The bottom view of the piezoelectric sounder which concerns on embodiment of this invention. Sectional drawing of the state which attached the piezoelectric sounder which concerns on embodiment of this invention to the electric equipment housing | casing.

Explanation of symbols

1. ・ Piezoelectric sounder 2. ・ Case 3. ・ Piezoelectric vibration plate 4. ・ Piezoelectric vibration element 5. ・ Electrode 6 ・ ・ Spacer 6a ・ ・ Through hole 7A ・ ・ First adhesive layer 7B ・ ・ Second adhesive layer 8・ ・ Mounting part 8a ・ ・ Vacancy 9 ・ ・ Sound release hole 10 ・ ・ Conductor 11 ・ ・ Conductor 13 ・ ・ Vacant

Claims (5)

A housing having a substantially annular mounting portion;
A diaphragm made of a conductive material having a first surface and a second surface and having a substantially same outer peripheral shape as the outer peripheral shape of the mounting portion;
A piezoelectric vibration element bonded to the second surface;
Electrodes bonded to both surfaces of the piezoelectric vibration element;
A first adhesive layer that adheres to the first surface of the diaphragm is provided on one surface side, and a second adhesive layer that adheres to the attachment portion is provided on the other surface side, and is made of a cushioning material. A spacer sheet material having an outer peripheral shape substantially the same as the outer peripheral shape and having a through hole having a diameter smaller than the outer diameter of the diaphragm,
A sound emitting hole communicating with the through hole is formed in the housing,
The piezoelectric sounder , wherein the diaphragm is mounted on the attachment portion via the spacer sheet material. 2. The piezoelectric sounder according to claim 1, wherein the spacer sheet material is made of a resin material. The piezoelectric sounder according to claim 1, wherein the spacer sheet material is made of foamed butyl rubber. The piezoelectric sounder according to any one of claims 1 to 3, wherein the spacer sheet material has a thickness of 0.5 mm or more. The piezoelectric sounder according to any one of claims 1 to 4, wherein the first adhesive layer is provided intermittently around the periphery of the through hole of the spacer sheet material.

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