JP2010062980A - Piezoelectric speaker - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a piezoelectric speaker which has wide directivity and also has simplified support structure and which is reduced in the manufacturing cost, further, reproduces low-pitched sound with full sound pressure and is made compact. <P>SOLUTION: The piezoelectric speaker 1 includes a piezoelectric body 2, a first electrode 3 formed on one principal surface of the piezoelectric body 2 and a second electrode 4, formed on another principal surface of the piezoelectric body 2; and when an orthogonal coordinate axis system is supposed which comprises an X axis, a Y axis and a Z axis that are orthogonal with one another, and pass through the center of a sphere, the piezoelectric body 2 has a shape of a 1/8 portion of a sphere shell obtained by dividing a sphere body with an XY plane, a YZ plane and ZX plane, the piezoelectric body 2 has first to third edges 2a to 2c which are orthogonal with one another and can be supported at one edge at least of the first to third edges 2a to 2c. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a piezoelectric speaker using a piezoelectric effect, and more particularly to a piezoelectric speaker using a spherical piezoelectric body.

  Conventionally, various piezoelectric speakers using vibration due to the piezoelectric effect of a piezoelectric body have been proposed. Since a piezoelectric body is used as a vibration source, piezoelectric speakers having various shapes can be formed using a piezoelectric ceramic molding technique.

  For example, Patent Document 1 below discloses a spherical piezoelectric speaker shown in FIG. The spherical piezoelectric speaker 101 includes a spherical piezoelectric body 102 having a hollow inside. A first electrode 103 is formed on the outer surface of the piezoelectric body 102, and a second electrode 104 is formed on the inner surface. Lead wires 105 and 106 are connected to the first electrode 103 and the second electrode 104, respectively.

Since the spherical piezoelectric speaker 101 uses the spherical piezoelectric body 102, it has no directivity and can propagate sound in all directions around the piezoelectric speaker 101.
JP-A-9-163498

  By the way, the spherical piezoelectric speaker 101 uses a spherical shell-shaped piezoelectric body 102. In manufacturing, a spherical shell-like piezoelectric body 102 is obtained by joining two hemispherical piezoelectric bodies. However, it is impossible to accurately join two hemispherical piezoelectric bodies. It was difficult.

  Further, since the whole is a spherical shell, the support structure of the piezoelectric speaker 101 tends to be complicated. That is, the spherical piezoelectric speaker 101 must be supported on a frame surrounding the spherical shell, and the support structure tends to be complicated. In addition, there is a possibility that the characteristics vary due to the support.

  On the other hand, the resonant frequency of the spherical shell is inversely proportional to the radius of the spherical shell. Therefore, in order to reproduce bass with sufficiently high sound pressure, a spherical shell with a large radius had to be formed. Therefore, downsizing has been difficult.

  The object of the present invention is to allow not only the propagation of sound in various directions using a spherical shell-shaped piezoelectric body, but also the simplification of the support structure in a stable manner. An object of the present invention is to provide a piezoelectric speaker that can be supported, is easy to manufacture, can reproduce bass with sufficient sound pressure, and can be reduced in size.

  According to the present invention, a curved piezoelectric body, a first electrode formed on one main surface of the piezoelectric body, and a second electrode formed on the other main surface of the piezoelectric body, the curved surface is provided. When the rectangular piezoelectric material passes through the center of the sphere and assumes orthogonal coordinate axes consisting of the X, Y, and Z axes that are orthogonal to each other, the XY plane along the X and Y axes, and the Y and Z axes A YZ plane along the X-axis and the XZ plane along the Z-axis, and having a shape of a 1/8 portion of the spherical shell, and the piezoelectric body is located in the XY plane. There is provided a piezoelectric speaker having one edge, a second edge located in the YZ plane, and a third edge located in the XZ plane.

  In a specific aspect of the piezoelectric speaker according to the present invention, a support member that is bonded to at least one of the first to third edges, and an adhesive that bonds a vibrating body to the support member. And an agent layer. Since each of the first to third end edges is linear, the support structure can be easily formed by simply joining the support member to the at least one end edge with the adhesive.

  In another specific aspect of the piezoelectric speaker according to the present invention, the support member has first to third plane portions located in the XY plane, the YZ plane, and the XZ plane, respectively. The first to third end edges of the piezoelectric body are joined to the first to third flat portions through the adhesive layer, respectively. Accordingly, the first to third plane portions orthogonal to each other can be used as the baffle plate, and a large sound pressure can be obtained in the low sound range. In addition, the piezoelectric speaker of the present invention can be easily applied to a portion having two plane portions that are orthogonal to each other, such as two wall surfaces and a ceiling surface that are orthogonal to each other, or two wall surfaces that are orthogonal to each other. .

  According to still another specific aspect of the piezoelectric speaker according to the present invention, a sound absorbing material filled inside the spherical piezoelectric body is further provided. An unnecessary wave can be absorbed by the sound absorbing material, and a clearer reproduced sound can be obtained.

  In the piezoelectric speaker according to the present invention, the curved piezoelectric body corresponds to 1/8 portion of the spherical shell, and thus has three linear edges that are orthogonal to each other. It can be easily fixed to the straight portion. Therefore, the support structure can be simplified. In addition, when manufacturing a piezoelectric member having a size of 1/8 of a spherical shell, it can be easily obtained simply by cutting the hemispherical shell-shaped piezoelectric member, so that the manufacturing process can be simplified.

  Moreover, a wall, a ceiling, etc. can be utilized as a baffle board, and thereby a low sound can be generated with a larger sound pressure, so that miniaturization can be promoted.

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

  1A and 1B are a perspective view showing an external appearance of a piezoelectric speaker according to an embodiment of the present invention and a front cross-sectional view showing the main part thereof.

  The piezoelectric speaker 1 has a spherical piezoelectric body 2 having a shape of a 1/8 portion of a spherical shell. The piezoelectric body 2 corresponds to 1/8 of the spherical shell. More specifically, as shown in FIG. 2, the piezoelectric body 1 is formed by dividing the spherical shell by three planes passing through the center O of the spherical shell. It corresponds to the portion of / 8. Here, in the sphere, arbitrary X axis, Y axis, and Z axis passing through the center O and orthogonal to each other are assumed. The 1/8 portion of the spherical shell refers to one curved portion of the portion obtained by dividing the spherical shell 2A into eight equal parts. That is, the spherical shell 2A is divided by the XY plane passing through the center O, extending along the X axis and the Y axis, the YZ plane extending along the Y axis and the Z axis, and the ZX plane extending along the Z axis and the X axis. A 1/8 portion of the shell 2A is obtained. Such a piezoelectric body 2 can be easily obtained by obtaining a hemispherical shell piezoelectric body and then dividing the hemispherical shell piezoelectric body into four equal parts. The piezoelectric body 2 can be easily manufactured as compared with a conventional spherical shell-shaped piezoelectric body.

  As shown in FIG. 1B, the first electrode 3 is formed on the outer main surface which is one main surface of the piezoelectric body 2. The second electrode 4 is formed on the other main surface, which is the inner surface of the piezoelectric body 2.

  The piezoelectric body 2 is formed of an appropriate piezoelectric material as long as it is configured to have the above shape. Examples of such a piezoelectric material include piezoelectric ceramics such as lead zirconate titanate-based ceramics, and synthetic resins having piezoelectricity. The electrodes 3 and 4 can be formed of an appropriate metal material such as Al, Cu, Ag, Au, or an Ag—Pd alloy.

  Lead wires 5 and 6 are connected to the first and second electrodes 3 and 4 so as to be electrically connected to each other. The lead wires 5 and 6 can be formed of appropriate Cu, Ag, Au, or an alloy mainly composed of these. The lead wires 5 and 6 may be appropriately coated with a resin.

  In the piezoelectric speaker 1 of the present embodiment, the piezoelectric body 2 has the above-described shape, and the first and second electrodes 3 and 4 are formed on the entire surfaces of the first and second main surfaces. The second electrodes 3 and 4 are not necessarily formed on the entire surface of the one main surface and the other main surface of the piezoelectric body 2.

  Since the piezoelectric body 2 has the above shape, the piezoelectric body 2 includes a first end edge 2a along the XY plane, a second end edge 2b along the YZ plane, and a third end edge 2c along the ZX plane.

  On the other hand, a support member 7 for supporting the piezoelectric body 2 is provided. The support member 7 includes a first plane portion 7a, a second plane portion 7b, and a third plane portion 7c that are orthogonal to each other. And the said 1st-3rd edge 2a-2c of the piezoelectric body 2 is each adhere | attached and fixed to the 1st-3rd plane parts 7a-7c by the adhesive bond layer 8. FIG. That is, since the piezoelectric body 2 has a shape having the first to third edges 2a to 2c, an adhesive is applied to the support member 7 having the first to third plane portions 7a to 7c that are orthogonal to each other. It can be easily fixed using the layer 8.

  Therefore, it is only necessary to prepare a support member having planar portions that are orthogonal to each other, and to bond the piezoelectric body 2 to the adhesive layer 8 with an adhesive, so that the support structure and the manufacturing process can be simplified.

  Moreover, the 1st-3rd plane parts 7a-7c can fulfill | perform the effect as a baffle board. As a result, bass can be reproduced with a large sound pressure.

  In the present embodiment, the sound absorbing material 9 is filled inside the piezoelectric body 2, that is, inside the shape of the 1/8 portion of the spherical shell. As the sound absorbing material 9, an appropriate sound absorbing material such as glass wool can be used. Thereby, the damping performance can be enhanced.

  As described above, in the piezoelectric speaker 1, the piezoelectric body 2 has the shape of a 1/8 portion of the spherical shell, and has the first to third end edges 2a to 2c that are orthogonal to each other. Therefore, it can be easily fixed to the support member having the planar portions that are orthogonal to each other using the adhesive layer 8. In the embodiment described above, the support member 7 having the three plane portions 7a to 7c that are orthogonal to each other is used, but may be a support member that has two plane portions that are orthogonal to each other. In that case, it is only necessary that two of the first to third edges are joined to two plane portions orthogonal to each other, and the remaining edges are covered with a sound absorbing material or the like. Alternatively, the remaining edge side may be opened.

  However, it is preferable that the first to third end edges 2a to 2c are bonded to the three plane portions 7a to 7c that are orthogonal to each other, and the inside is sealed, as in the above embodiment. For example, as shown in FIG. 3, the piezoelectric speaker 1 has a ceiling 11 in a room, first and third planes on first and second wall surfaces 12 and 13 that are orthogonal to the ceiling 11 and orthogonal to each other. By fixing the portions 7a to 7c, it can be fixed to the corner portion on the corner of the ceiling. The piezoelectric speaker 1 can be similarly fixed to the corners of the third wall surface 14 facing the first wall surface 12 and the second wall surface 13 and the ceiling 11. Accordingly, since the ceiling 11 and the first to third wall surfaces 12 to 14 can be used as an infinite baffle, it is possible to reproduce the bass with a higher sound pressure. Accordingly, bass can be reproduced with a sufficiently high sound pressure without increasing the radius of the piezoelectric body 2, so that the piezoelectric speaker can be miniaturized.

  Further, since the piezoelectric speaker 1 uses the piezoelectric body 2 having a shape of 1/8 of a spherical shell, sound waves are emitted from the outer surface of the piezoelectric body 2 with sufficient sound pressure in various directions. Therefore, it is possible to provide a piezoelectric speaker that does not have directivity and is suitable as a surround speaker.

  Therefore, according to the present embodiment, there is provided a piezoelectric speaker that has no directivity, can provide a wide sound field, and can be reproduced with a sufficient sound pressure up to a low sound without being enlarged. It becomes possible. In addition, the support structure and the manufacturing process can be simplified, and the cost can be reduced.

  In the above embodiment, the sound absorbing material 9 is filled, but the sound absorbing material 9 may not necessarily be filled.

  In FIG. 3, the first to third flat portions 7 a to 7 c of the support member 7 are the ceiling 11 and the first and second wall surfaces 12 and 13 or the ceiling 11 and the second and third wall surfaces 13 and 14. However, the piezoelectric body 2 may be bonded to the ceiling 11 and the first to third wall surfaces 12 to 14 directly by the adhesive layer 8. In that case, it is also possible to use a part of the building structure such as the ceiling 11 and the first to third wall surfaces 12 to 14 as a support structure of the piezoelectric body.

(A) And (b) is a perspective view which shows the external appearance of the piezoelectric speaker of one Embodiment of this invention, and front sectional drawing which shows the principal part. The typical perspective view of the spherical body for demonstrating the shape of 1/8 of a spherical shell. The schematic perspective view for demonstrating the state in which the piezoelectric speaker of this embodiment is attached to the room. It is front sectional drawing which shows the conventional spherical type piezoelectric speaker.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Piezoelectric speaker 2 ... Piezoelectric body 2A ... Spherical shell 2a ... 1st edge 2b ... 2nd edge 2c ... 3rd edge 3 ... 1st electrode 4 ... 2nd electrode 5, 6 ... lead Line 7 ... Supporting member 7a ... First plane portion 7b ... Second plane portion 7c ... Third plane portion 8 ... Adhesive layer 9 ... Sound absorbing material 11 ... Ceiling 12 ... First wall surface 13 ... Second wall surface 14 ... Third wall surface

Claims (4)

A curved piezoelectric body;
A first electrode formed on one main surface of the piezoelectric body;
A second electrode formed on the other main surface of the piezoelectric body,
When the curved piezoelectric body passes through the center of a sphere and assumes orthogonal coordinate axes composed of an X axis, a Y axis, and a Z axis that are orthogonal to each other, an XY plane along the X axis and the Y axis, a Y axis, and a Z axis It has a shape of a 1/8 portion of a spherical shell obtained by dividing the YZ plane along the axis and the XZ plane along the X axis and the Z axis, and the piezoelectric body is located in the XY plane. A piezoelectric speaker having a first end edge, a second end edge located in the YZ plane, and a third end edge located in the XZ plane. A support member joined to at least one of the first to third edges;
The piezoelectric speaker according to claim 1, further comprising an adhesive layer that joins the piezoelectric body of the support member.   The support member has first to third plane portions located in the XY plane, the YZ plane, and the XZ plane, respectively, and the first to third edges of the piezoelectric body are 3. The piezoelectric speaker according to claim 2, wherein each of the piezoelectric speakers is bonded to the first to third flat portions via the adhesive layer.   The piezoelectric speaker according to claim 1, further comprising a sound absorbing material filled inside the spherical shell-shaped piezoelectric body.

Images