JPH09275600A - Piezoelectric type electroacoustic transducer and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a piezoelectric type electroacoustic transducer which can improve its build-in workability and has its stable air-tightness and high reliability by unifying a buffer member that is conventionally used as an independent parts with another parts. SOLUTION: A lower case 11 consists of a hard plastic 12 and a soft plastic 13 and has a sound discharge hole 14, and a piezoelectric vibrator 20 is attached to the case 11 so as to be held at its periphery. In such a constitution, a piezoelectric type electroacoustic transducer is obtained. The case 11 undergoes the so-called double color molding where two types of thermoplastic resin are simultaneously and continuously projected into a single metallic mold or the insertion molding where the case 11 is unified with the thermoplastic resin. Then a ring- shaped hard plastic projection part 13 is formed on a coupling surface between the electroacoustic transducer and a handset casing of a telephone receiver.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric electroacoustic transducer to which a piezoelectric vibrator is applied, and more particularly to a piezoelectric electroacoustic transducer which is used in a telephone receiver and is easy to mount and does not deteriorate sound quality. .

[0002]

2. Description of the Related Art Generally, as a device for converting an electric signal into an acoustic signal such as sound or voice, there is a piezoelectric electroacoustic transducer using a piezoelectric vibrator. It is used in telephone handsets, buzzers, headphones, etc.

Of these, in mobile communication devices that are currently rapidly developing, that is, in handset systems such as mobile phones, those of high sound quality and high volume are particularly desired, and various measures have been taken. ing. For example, Japanese Patent Laid-Open No. 1-2339
No. 43 and Japanese Utility Model Laid-Open No. 1-132158 disclose that, when the piezoelectric electroacoustic transducer is attached to the handset housing, the former forms a resistance control type acoustic vibration system while the latter is elastic. It is described that it is possible to provide a receiver with high sound quality by providing the cushioning material having the above.

[0004]

However, in all of the above proposals, when the piezoelectric electroacoustic transducer is incorporated in the handset housing via the cushioning material such as the elastic body or the double-sided tape, each of them is an independent component. Therefore, the number of parts used increases. Therefore, there is a problem that the work for assembling becomes complicated, the airtightness cannot be stably maintained, and the characteristics are deteriorated.

Therefore, an object of the present invention is to improve the workability at the time of assembling, and to keep the airtightness stable,
It is to provide a piezoelectric electroacoustic transducer with high reliability.

[0006]

[Means for Solving the Problems] Specifically, the following (1)
This is achieved by the configuration of (3).

(1) In a piezoelectric electroacoustic transducer of a telephone handset, a ring-shaped protrusion made of soft plastic is provided on a coupling surface between the piezoelectric electroacoustic transducer and a handset housing of the handset. A piezoelectric electroacoustic transducer characterized by:

(2) A method for integrally molding a casing of the piezoelectric electroacoustic transducer according to (1), wherein hard plastic and soft plastic are used for the lower case of the upper and lower cases constituting the casing. The method as described above, wherein two-color molding is applied to and.

(3) A method for integrally molding a casing of the piezoelectric electroacoustic transducer according to (1), wherein the lower case in the upper and lower cases constituting the casing is made of hard plastic or soft plastic. The method as described above, characterized in that insert molding is applied to and.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION A piezoelectric electroacoustic transducer according to the present invention will be specifically described below with reference to FIGS.

FIG. 1 shows an exploded perspective view of a piezoelectric electroacoustic transducer according to the present invention. The piezoelectric electroacoustic transducer according to the present invention is a piezoelectric vibrator in which a piezoelectric body 21 is attached to a metal vibrating plate 22 in a lower case 11 made of hard plastic 12 and soft plastic 13 and having a sound output hole 14. 20
Are attached so that they serve as peripheral support. Further, the lead wire 31 is electrically connected to the piezoelectric body 21 and the vibration plate 22 of the piezoelectric vibrator 20 by solder 32. Further, the upper case 1 having the back pores 16 from above
5 is attached. A braking cloth 17 is attached to the back air hole 16 as an acoustic resistance material.

The lower case 11 is made of the hard plastic 12 and the soft plastic 13 as described above, and is made by two-color molding. Here, the two-color molding means that two types of thermoplastic resins are continuously injected into one die at the same time for molding. As another molding method, soft plastic may be integrally molded by insert molding when molding hard plastic.

FIG. 2 shows a view (backside view) and a side view seen from the direction A in FIG. Here, 41 in the drawing is a hard plastic part of the lower case of the piezoelectric electroacoustic transducer housing according to the present invention, 42 is also a soft plastic part, 43 is a sound output hole, and 51 is a lead wire. As described above, the soft plastic is formed in a ring shape and plays a role of a cushioning material when the piezoelectric electroacoustic transducer is mounted on the handset housing. Next, FIG.
(A) shows a schematic diagram of a procedure for mounting a conventional piezoelectric electroacoustic transducer, and (b) shows a schematic diagram of a procedure for mounting a piezoelectric electroacoustic transducer according to the present invention. Here, in the conventional procedure for mounting the piezoelectric electroacoustic transducer, the cushioning material 71 and the piezoelectric electroacoustic transducer 81 are sequentially mounted on the handset housing 61, while the piezoelectric electroacoustic transducer according to the present invention is mounted. In the mounting procedure of the device, since the piezoelectric electroacoustic transducer 82 integrally molded with the soft plastic that functions as a cushioning material is directly mounted to the handset housing 62, the work process is simplified as compared with the conventional method. Can be converted.

Further, it is an indispensable condition to obtain high sound quality and high sound volume to improve the adhesion between the piezoelectric electroacoustic transducer and the handset housing, but even if the cushioning material is interposed, Since it is fixed with an adhesive or the like, it is inevitable that the sound quality is deteriorated due to lack of airtightness due to deterioration of the adhesive due to long-term use. Therefore, from the viewpoint of reliability, it is preferable that the area of the bonding surface using an adhesive or the like is as small as possible. Whereas the conventional one has a piezoelectric electroacoustic transducer and a cushioning material, and the cushioning material and a handset casing have two coupling surfaces, the one according to the present invention has a coupling surface having a piezoelectric electroacoustic transducer and a handset casing. Since there is only one surface, the area of the coupling surface can be reduced, and the sound quality is less likely to deteriorate as compared with the conventional one.

Next, the materials and the like of the parts used in the present invention will be described in detail.

The casing of the piezoelectric electroacoustic transducer comprises an upper case and a lower case, and the lower case is made of hard plastic and soft plastic as described above. Here, the hard plastic is a thermoplastic resin such as polystyrene (ABS), polyethylene terephthalate (PBT), and polycarbonate (PC) that is generally used for these housings. The soft plastic is an elastic thermoplastic resin such as an elastomer. The upper case is
The same material as the hard plastic of the lower case is used.

The piezoelectric vibrator is formed by adhering a piezoelectric body and a metal plate. In this piezoelectric vibrator, the bonding surface between the piezoelectric body and the metal plate is made conductive with a conductive paste or the like. In addition, depending on the application of the piezoelectric electroacoustic transducer, one in which a piezoelectric body is adhered to one side of a metal plate (unimorph) or one in which both sides are adhered (bimorph) is used. The material, manufacturing method, shape, and the like of the piezoelectric body and the metal plate may be any commonly used materials, and are appropriately selected depending on the intended use. For example, the following are mentioned. The piezoelectric material is PMN-based, PZT-based, or the like. Further, brass or the like is used as the material of the metal plate. An electrode made of Ag or the like is formed on the surface of the piezoelectric body using a vacuum deposition method or a printing method.

[0018]

The piezoelectric electroacoustic transducer according to the present invention comprises:
Since the cushioning material that has been conventionally used as an independent component is provided, the workability when mounting on the handset housing is improved. In addition, the area of the coupling surface with the handset housing can be reduced, the airtightness due to vibration, shock, etc. is less likely to decrease, and the sound quality is less likely to deteriorate than the conventional one.

[Brief description of drawings]

FIG. 1 is an exploded perspective view of a piezoelectric electroacoustic transducer according to the present invention.

2A is a back view of the piezoelectric electroacoustic transducer according to the present invention, and FIG. 2B is a side view thereof.

3A is a schematic view of a mounting procedure of a conventional piezoelectric electroacoustic transducer, and FIG. 3B is a schematic view of a mounting procedure of a piezoelectric electroacoustic transducer according to the present invention.

[Explanation of symbols]

11: Lower case 12, 41; Lower case hard plastic part 13, 42; Lower case soft plastic part (ring-shaped protrusion) 14, 43; Sound emission hole 15; Upper case 16; Back air hole 17; Static movement Cloth 20; Piezoelectric vibrator 21; Piezoelectric body 22; Vibration plate 31, 51; Lead wire 32; Solder 61, 62; Handset housing 71; Buffer material 81; Conventional piezoelectric electroacoustic transducer 82; Piezoelectric electroacoustic transducer

Claims (3)

[Claims] 1. A piezoelectric electroacoustic transducer for a telephone handset, wherein a ring-shaped protrusion made of soft plastic is provided on a coupling surface between the piezoelectric electroacoustic transducer and a handset housing of the handset. Characteristic piezoelectric electroacoustic transducer. 2. A method for integrally molding a casing of the piezoelectric electroacoustic transducer according to claim 1, wherein the lower case of the upper and lower cases forming the casing is made of hard plastic and soft plastic. The method as described above, wherein the two-color molding is applied to. 3. A method for integrally molding a casing of the piezoelectric electroacoustic transducer according to claim 1, wherein the lower case of the upper and lower cases forming the casing is made of hard plastic and soft plastic. The method described above, characterized in that insert molding is performed on the above.