JPH02219399A - Piezoelectric speaker - Google Patents

Abstract

PURPOSE:To enlarge the volume of a cavity, which is occupied in a diaphragm, and to make a diaphragm light in weight by attaching two plate materials of the diaphragm, which is formed by attaching the two plate materials, only in a part near an outer circumference, forming the cavity in an inside and housing a piezoelectric sounding body. CONSTITUTION:A frame 1 is made of metal and formed in the shape of a frame and an elastic supporter 2 is made of an elastic material such as rubber, etc., and attached over the whole circumference of an inner surface in the frame 1. For a diaphragm 3, two large and small plates 4 and 5, which are made of foaming resin and formed in a rectangular shape, are attached. The central parts of the plate materials 4 and 5 are made thin and ring-shaped projections 4a and 5a are provided over the whole outer circumference of a facing surface. Accordingly, a large cavity 3a is formed in the inside surface part of the plate materials 4 and 5. Support parts 4b and 5b integrally molded in the plate materials 4 and 5 are pressed and plural piezoelectric sounding bodies are fitted to plural spots in the internal part of the cavity 3a. Thus, the space is spread over among the sounding bodies 6, which are separately arranged, and to a circumferential part. Then, the diaphragm is made light in weight.

Description

[Detailed description of the invention] Industrial applications The present invention relates to piezoelectric speakers.

The applicant has proposed a piezoelectric speaker shown in FIG. 3 (front view) and FIG. 4 (cross-sectional view taken along line IV--IV in FIG. 3). This is because the outer peripheral part of the diaphragm 13 is supported by the frame (2) via the elastic support piece 2, and the piezoelectric sounding body 6 is fixed in the cavity 13a provided inside the diaphragm 13 via the support part 13b. The piezoelectric sounding body 6 drives the diaphragm 13 to emit sound.

By the way, the cavity 13a has a size that allows the piezoelectric sounding body 6 to be attached to the inside of the diaphragm 13, which is formed by bonding the wide sides of two foamed resin plates 14 and 15, for example. The number of attachments corresponding to the number of pieces is formed.

Therefore, since materials such as foamed resin are present in the parts of the diaphragm 13 other than the cavity 13a, the whole becomes heavy, which is especially noticeable in the case of large speakers, and the sound pressure level decreases. There was a problem.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to provide a piezoelectric speaker with a powerful base that has a lighter diaphragm and an improved sound pressure level.

The present invention for achieving "i" includes a diaphragm formed by bonding two plate materials together, a frame that elastically supports this diaphragm, and one or more piezoelectric sounding bodies that drive the diaphragm. In the piezoelectric speaker equipped with the above-mentioned piezoelectric speaker, the two plates are bonded together only in the vicinity of their outer peripheries, and the inside of this bonded portion forms a cavity, and the piezoelectric sounding body is housed in this cavity. It is characterized by

Work-1 □Tomo In the case of the present invention, two plates are bonded together only near their outer peripheries, and the inside of this bonded portion is
Since there are two cavities, most of the inside of the diaphragm is occupied by the cavities. Therefore, unlike the conventional method in which a cavity is formed in the required size at the location where the piezoelectric sounding body is attached, the piezoelectric sounding body is attached at a position within one large cavity.

Therefore, the volume of the cavity occupying the diaphragm increases,
Lighter weight can be achieved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a sectional view taken along line I-I in FIG. 2, FIG. 2 is a front view showing the speaker of the present invention, and FIG.
, 4 The same parts are given the same numbers. 1 is a frame, 2 is an elastic support piece, 3 is a diaphragm, and 6 is a piezoelectric sounding body.

The frame 1 is formed by bending a metal band material, for example, and is formed into a picture frame shape.

The elastic support piece 2 is made of an elastic material such as urethane foam or rubber leather, and is attached to the inner surface 1a of the frame 1 over the entire circumference.

The diaphragm 3 is made by laminating two rectangular plates 4.5, large and small, made of foamed resin such as expanded polystyrene, expanded polystyrene, or a copolymer thereof, with their wide sides overlapped. The two plates 4.5 have annular protrusions 4a and 5a formed around the entire circumference near the outer periphery on the opposing surface side by making the central part thin, and the annular protrusion 4a formed on the larger plate 4. The elastic support piece 2 is attached to the outer circumferential side, and the annular protrusion 5a formed on the smaller plate material 5 is attached to the inner circumferential side.

Therefore, one large cavity 3a is formed in a portion surrounded by the inner surfaces of the two plates 4 and 5, including the inner surfaces of the annular projections 4a and 5a. The widths of the annular protrusions 4a and 5a are determined so as to ensure a minimum strength required for the diaphragm 3.

Note that the plate material 4.5 may be formed integrally by injection molding or the like with a thin center part and a thick wall in the annular protrusions 4a and 5a, or it may be formed separately on the outer periphery of a plate material with a constant thickness. The annular protrusion 4a5a of the body may be attached and integrated.

A piezoelectric sounding body 6 is attached to a plurality of locations, for example, five locations inside the cavity 3a, in a state where it is pressed from both sides by support portions 4b and 5b that are formed integrally with the plate members 4 and 5. That is, all five piezoelectric sounding bodies 6 are installed in a distributed manner within one cavity 3a, unlike the conventional method in which a cavity is formed with the required size at the location where the piezoelectric sounding body is installed. The piezoelectric sounding body is now attached to a predetermined position within one large cavity. Therefore, there is a space between the piezoelectric sounding bodies 6 that are spaced apart from each other, unlike the conventional piezoelectric sounding body, and space is also expanded around each piezoelectric sounding body 6, so that the diaphragm 3 is reduced in weight. The supporting parts 4b and 5b may also be formed integrally with the plate 4.5, or may be separate pieces attached to the plate 4.5.

The piezoelectric sounding body 6 has a structure in which a pair of circular piezoelectric bodies 6a, 6a made of, for example, PZT are attached to both sides of a circular metal plate 6b having a larger diameter.
When the metal plate 6a is distorted by an input electric signal, the metal plate 6b is bent, thereby driving the diaphragm 3 and emitting sound. At this time, since the diaphragm 3 is lightweight as described above, powerful sound with a high sound pressure level is produced.

Although the above description shows a case where a plurality of (five in the example) piezoelectric sounding bodies 6 are attached to the diaphragm 3, the present invention is not limited to this, and the present invention is not limited to this. Of course, it can also be applied when installing. That is, in this case, only the number of piezoelectric sounding bodies 6 in the cavity 3a is reduced, and the size of the cavity 3a is the same as in the case where a plurality of piezoelectric sounding bodies 6 are provided.

In addition, in the above embodiment, two plate members 4 constituting the diaphragm 3
．． 5 are respectively provided with annular protrusions 4a and 5a to form a cavity 3a, but the present invention is not limited to this.
．． It is also possible to form the cavity 3a by providing the annular projection 4a or 5a on only one side of the cavity 3a.

Kim Kai A. As described in detail above, in the case of the present invention, two plates are bonded together only near their outer peripheries, and the inside of this bonded portion is a single cavity, so that the inside of the diaphragm is Most of them are hollow, and therefore, unlike the conventional method where a cavity of the required size is formed at the location where the piezoelectric sounding element is installed, it is now possible to install the piezoelectric sounding element at a position within one large cavity. Become. Therefore, it is possible to increase the volume of the cavity occupied in the diaphragm, thereby making it possible to reduce the weight of the diaphragm, improve the sound pressure level, and generate powerful sound.

[Brief explanation of the drawing]

FIG. 1 is a sectional view taken along line I-1 in FIG. 2, FIG. 2 is a sectional view showing the speaker of the present invention, FIG. 3 is a front view showing an example of a conventionally proposed piezoelectric speaker, and FIG. FIG. 2 is a sectional view taken along the TV-IV line of FIG. DESCRIPTION OF SYMBOLS 1... Frame, 2... Elastic support piece, 3... Vibration plate, 3a... Cavity, 4. Death...Plate material, 4a, 5a...
- Annular projection, 6...piezoelectric sounding body. Patent applicant Murata Manufacturing Co., Ltd.

Claims (1)

[Claims] (1) A piezoelectric speaker comprising a diaphragm formed by bonding two plate materials together, a frame that elastically supports this diaphragm, and one or more piezoelectric sounding bodies that drive the diaphragm, as described above. The two plates are pasted together only near their outer edges,
The inside of this bonded part forms one cavity,
A piezoelectric speaker characterized in that the piezoelectric sounding body is housed in this cavity.