JPH037497A - Piezoelectric speaker - Google Patents

Abstract

PURPOSE:To attain thin profile by adopting a structure such that 3 foamed resin plates or over obtained the extruder forming method are laminated and adhered for a diaphragm. CONSTITUTION:Four foamed resin plates 31-34 are formed by the extruder forming method. Then throughholes 32a, 33a with a slightly larger size than a piezoelectric driver 21 are formed in the middle of the foamed resin plates 32, 33 located at the inside among the foamed resin plates 31-34. Then the four foamed resin plates 31-34 are laminated and adhered, then the piezoelectric driver 21 is contained in the throughholes 32a, 33a and contained in a piezoelectric driver contained space with piezoelectric driver support members 35, 36. Then a projection 22a of the foamed resin plate 32 is inserted to a frame 24 and an elastic support piece 23 is inserted between the frame 24 and the projection. Thus, the thickness of the foamed resin plates 31-34 is made very thin to attain thin profile.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a piezoelectric speaker in which a piezoelectric driver is attached to a diaphragm made of a foamed resin.

Figure 6 shows a conventional example of this type of piezoelectric speaker. This piezoelectric speaker has a structure in which a diaphragm 3 is formed by facing two foamed resin plates 4.5 made of foamed polystyrene, foamed polyethylene, etc., and a piezoelectric driver 6 is sandwiched and held between both foamed resin plates 4.5. It has become.

Specifically, an annular groove 4as5a having the same diameter is formed in the center of the opposing surface of the foamed resin plate 4.5.
Protrusions 4b and 5b remaining in the center of these grooves 4as and 5a
It has a structure in which a piezoelectric driver 6 is held in between. In addition, in FIG. 6, only one side of the grooves 4a and 5a is visible.

The piezoelectric driver 6 is of a bimorph type in which piezoelectric plates 6a, 6a (made of PZT, etc., for example) are attached concentrically to both surfaces of a circular metal plate 6b.

a<"i By the way, since the above-mentioned piezoelectric speaker is used for hanging on a wall, etc., there is a strong demand for making it thinner. Therefore, when producing a piezoelectric speaker, the foamed particles of the foamed resin plate 4.5 are made smaller to make it thinner. There have been proposals to achieve this.

However, this increases the specific gravity of the foamed resin plate 4.5, making the piezoelectric speaker heavy. In addition, in the above structure, since it is necessary to mold the foamed resin plate 4.5 by a so-called injection method, there is a problem that warping or twisting occurs.

Therefore, in order to reduce the weight of the piezoelectric speaker, it is conceivable to increase the size of the foamed particles of the foamed resin plate 4.5. However, when a thin foamed resin plate 4.5 is molded due to dirt, the filling of the resin will be insufficient, resulting in warping or twisting.

The only way to solve this problem is to increase the thickness of the foamed resin plate 4.5, but this poses the problem that the original objective of making the piezoelectric speaker thinner cannot be achieved.

The present invention has been made in view of the current situation, and it is an object of the present invention to provide a piezoelectric speaker that can eliminate the above-mentioned drawbacks.

In order to achieve the above object, the present invention includes a piezoelectric driver that vibrates in accordance with an applied signal, and a piezoelectric driver that is housed inside, vibrates in response to the vibration of the piezoelectric driver and generates sound. In the piezoelectric speaker having a diaphragm, the diaphragm has a structure in which three or more foamed resin plates obtained by extrusion molding are laminated and bonded,
A piezoelectric driver housing hole for housing the piezoelectric driver is provided in the foam resin plate located on the inside of these foam resin plates, and the piezoelectric driver is housed on the opposing surface of the foam resin plate facing across the piezoelectric driver housing hole. It is characterized in that a supporting piezoelectric driver support member is attached.

Stand-U If a foamed resin plate produced by the extrusion molding method as described above is used for the diaphragm, the thickness of one foamed resin plate can be made extremely thin. Therefore, even if the diaphragm is formed by laminating three or more foamed resin plates, the thickness of the piezoelectric speaker can be made much thinner than in the past.

Furthermore, the weight can be reduced by the amount that the thickness is reduced.

Furthermore, if a diaphragm is formed by laminating and bonding three or more foamed resin plates, the rigidity of the diaphragm will be increased, which will prevent so-called split vibration, where only one part of the diaphragm vibrates strongly while the other parts vibrate weakly. Can be suppressed.

Therefore, the frequency characteristics of the piezoelectric speaker become flat.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of the present invention will be described in detail below with reference to the drawings. FIG. 1 is a longitudinal cross-sectional view showing a piezoelectric speaker according to the present invention, FIG. 2 is an enlarged cross-sectional view showing essential parts thereof, and FIG. 3 is an exploded perspective view of the piezoelectric speaker.

In the piezoelectric speaker, a diaphragm 22 in which a piezoelectric driver 21 is housed is connected to a frame 2 through an elastic support piece 23.
The configuration is fixed at 4. Specifically, the above frame 2
4 has a frame shape, and a protruding portion 22a of the diaphragm 22 is inserted into a groove 24a having a U-shaped cross section and formed over the entire length of the inner circumferential surface.
Insert and concatenate. Furthermore, between the protruding portion 22a and the frame 24, there is provided an elongated tape-shaped elastic support piece 2.
3 is interposed over the entire circumference, and this elastic support piece 2
3, the diaphragm 22 is supported by the frame 24.

The piezoelectric driver 21 is of a bimorph type as shown in FIG.
1a and 21b sandwich the metal plate 21c. The structure is such that when an electric signal is applied to both positive electric plates 21a and 21b, the entire body including the metal plate 21C undergoes bending vibration due to the piezoelectric effect.

One end side of lead wires 27a, 27b, 27c is soldered to the electrodes of the piezoelectric plates 21a, 21b and the metal plate 21C, and the other end side of the lead wires 27a, 27b, 27C is soldered to a foamed resin plate 32. The piezoelectric driver 21 is connected to an amplifier (not shown) that vibrates the piezoelectric driver 21 .

By the way, as shown in FIG. 3, the diaphragm 22 is made of four foamed resin plates 31 made by extrusion molding.
．． 32, 33, and 34, these foamed resin plates 31 to 34
34 is made of, for example, foamed polystyrene, foamed polyethylene, or a copolymer of both. The foamed resin plates 31, 33, and 34 have a square shape, while the foamed resin plate 32 is formed slightly laterally to form the protrusion 22a. The thickness of each of the foamed resin plates 31 to 34 is 2 fl. Cylindrical through holes 32a and 33a, which are somewhat larger than the piezoelectric driver 21, are formed in the center of the two foam resin plates 32 and 33 arranged inside of the foam resin plates 31 to 34. These through holes 32a and 33a allow the piezoelectric driver 21 to
A larger piezoelectric driver housing space is formed. Furthermore, cylindrical piezoelectric driver support members 35 and 36 made of foamed resin are adhered to the center portions of the two foamed resin plates 31 and 34 arranged on the outside among the foamed resin plates 31 to 34. , these piezoelectric driver support members 35 and 36
The piezoelectric driver 21 is held under pressure. For this reason, the piezoelectric driver support members 35 and 36 have a structure in which the height dimension is slightly shorter than the depth dimension of the through holes 32a and 33a.

Here, the piezoelectric speaker having the above structure is manufactured as follows.

First, four foamed resin plates 3 are made by extrusion molding.
1 to 34 (all thicknesses are 2 cranes).

At this time, the foamed resin board 32 is attached to the other foamed resin boards 31, 33.
It is formed to be slightly laterally elongated than 34.

Next, a piezoelectric driver 21 is placed in the center of the foam resin plates 32 and 33 located inside of the foam resin plates 31 to 34.
0 to form through holes 32a and 33a that are slightly larger than
Next, the four foamed resin plates 31 to 34 are laminated and bonded. At this time, the piezoelectric driver 21 is connected to the through hole 32a.
The piezoelectric driver support member 35.3 is housed in the piezoelectric driver support member 33a.
6 to hold the piezoelectric driver in the piezoelectric driver storage space.

Thereafter, the protrusion 22a of the foamed resin board 32 is inserted into the frame 24 in the form of a frame, and the elastic support piece 23 is interposed between the frame 24 and the protrusion, thereby forming the foamed resin board 31.
A diaphragm 22 consisting of .about.34 is supported and fixed to a frame 24.

As described above, if the foamed resin plates 31 to 34 are formed by the extrusion method, the thickness of the foamed resin plates 31 to 34 can be made very small, so even if four sheets are stacked, the diaphragm 22 (and piezoelectric speaker ) is much thinner than before.

For example, in the above embodiment, since the foamed resin plates 31 to 34 have a thickness of two fins, the thickness of the piezoelectric speaker is 8 ml, whereas in the past, at least 10 nm or more was required.

Note that the thickness of the foamed resin plates 31 to 34 can be reduced to about 1 m.

In addition, only the foamed resin plate 32 is formed to be slightly laterally long, and the protrusion 22a formed thereby is attached to the frame 2.
4, the diaphragm 22
Since the thickness of the piezoelectric speaker does not become larger than the thickness of , it is possible to make the piezoelectric speaker -B thinner.

Measure 1 Replacement ■ A second embodiment of the present invention will be specifically described below with reference to the drawings. FIG. 4 is a longitudinal sectional view showing a piezoelectric speaker according to a second embodiment of the present invention, and FIG. 5 is an exploded perspective view thereof. Incidentally, members having the same functions as those in the first embodiment are given the same reference numerals, and their explanations will be omitted.

The diaphragm 22 of this embodiment is made up of three foamed resin plates 40~
42 are laminated and bonded together. The above foamed resin board 40~
42, the foamed resin plate 40 on the upper side in the figure has a horizontally long rectangular shape and has a thickness of 2 mm. Further, the central foamed resin plate 41 has a square shape with one side having the same length as the short side of the foamed resin plate 40, and has a through hole 41a considerably larger than the piezoelectric driver 21 in the center. It is formed. Note that the thickness of the foamed resin plate 41 is 41 mm. Furthermore, the foamed resin board 42 on the lower side of the figure has a square shape with each side having the same length as the foamed resin board 41, and its thickness is 2 m. Piezoelectric driver support members 35 and 36 are provided in the piezoelectric driver storage space formed by the through hole 41a.
A piezoelectric driver 21 is housed therein.

The protrusion 40a of the foamed resin plate 40 is formed by the elastic support piece 23.
It is fixed to the L-shaped frame 24 via. The height of this frame 24 is configured to be equal to or less than the total thickness (8 cranes) of the foamed resin plates 40 to 42.

With such a structure, the thickness of the piezoelectric speaker does not become larger than that of the first embodiment, and the weight can be further reduced by the larger through hole 41a.

In addition, since it has a three-layer structure, it can be manufactured more easily.

In the above two embodiments, foamed resin is used as the piezoelectric driver support members 35 and 36, but the piezoelectric driver support members 35 and 36 are not limited to this, and may be made of hard plastic, metal, rubber, or the like.

Further, in the above embodiment, the diaphragm 22 is formed by laminating and bonding three or four foam resin plates, but the structure is not limited to this, and five or more foam resin plates may be laminated and bonded. Of course, such a structure may also be used. In this case, the thickness of the foamed resin plate can be made smaller (for example, by one step) to reduce the weight.

Further, in the above embodiment, the structure in which the lead wires are soldered to the piezoelectric plates 21a and 21b and the metal plate 21c has been described, but the present invention can be applied to a structure in which the lead wires are not soldered to the metal plate 21C. Can be applied.

In addition, although a bimorph type piezoelectric driver 21 is used, the piezoelectric driver 21 is not limited to this, and can also be applied to a unimorph type.

As described above, according to the present invention, the thickness of the piezoelectric speaker can be made much smaller than that of the conventional piezoelectric speaker, and the weight can be reduced by an amount corresponding to the reduced thickness.

Furthermore, since split vibration can be suppressed, the frequency characteristics of the piezoelectric speaker can be flattened by 4 degrees.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view showing a piezoelectric speaker according to a first embodiment of the present invention, FIG. 2 is an enlarged sectional view showing the main parts thereof, FIG. 3 is an exploded perspective view of FIG. 1, and FIG. FIG. 5 is an exploded perspective view of FIG. 4, and FIG. 6 is a longitudinal cross-sectional view of a conventional piezoelectric speaker. Fig. 1 21...Piezoelectric driver 22...Diaphragm,
31-34/40-42...Foamed resin board, 32a/3
3a, 41a... Through hole, 35, 36... Piezoelectric driver support member. Figure 2

Claims (1)

[Claims] (1) A piezoelectric driver that vibrates according to the applied signal,
A piezoelectric speaker comprising: a diaphragm in which the piezoelectric driver is housed, and which vibrates in response to vibrations of the piezoelectric driver to produce sound, the diaphragm comprising three or more foamed resin plates obtained by extrusion molding. It has a laminated and bonded structure, and the inner foam resin board of these foam resin plates is provided with a piezoelectric driver storage hole for storing the piezoelectric driver, and the foam resin board facing opposite with this piezoelectric driver storage hole in between is provided. A piezoelectric speaker characterized in that a piezoelectric driver support member for supporting the piezoelectric driver is attached to an opposing surface of the piezoelectric speaker.