JPH0482400A - Piezoelectric speaker - Google Patents

Abstract

PURPOSE:To obtain a stable sound pressure frequency characteristic by reinforcing a rigidity of a part made thin by formation of a recessed part of a foam resin plate with a high rigidity member so as to suppress generation of split vibration at the thin part. CONSTITUTION:A frame 1 whose front side is formed to be a rectangular shape is fitted to the periphery of a diaphragm 3 the same as the shape of the diagram 3 and a thin elastic support tape 2 is interposed between a rear face of the diaphragm 3 and the frame 1 over the entire periphery of the diaphragm 3. Recessed parts 4a, 5a for containing a piezoelectric driver of disk shape are provided while being butted in the middle of opposed faces of the foam resin plates 4, 5. Inner depth faces 4b, 5b of the recesses parts 4a, 5a, are formed flat and high stiffness plates 7, 8 are fitted respectively to the inner depth faces 4b, 5b. Even when the recessed parts 4a, 5a are provided on the plates 4, 5 to contain the piezoelectric driver 6, a thin part A formed by the recessed parts 4a, 5a is reinforced by the high stiffness plates 7, 8.

Description

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

As an example of the conventional structure of the piezoelectric speaker described above with Natsuki distortion, the one shown in FIG. 4 is known. In this piezoelectric speaker, a diaphragm 13 is formed by two foamed resin plates 14 and 15, and a piezoelectric driver 18 is housed in recesses 16 and 17 provided at the center of opposing surfaces of both foamed resin plates 14 and 15. Protrusions 16a, 17 provided in the center of the recess 16.17
The structure is such that the piezoelectric driver 18 is sandwiched between the parts a.

By the way, in this type of piezoelectric speaker, since the above-described recesses 16 and 17 are provided in the foamed resin plates 14 and 15, the foamed resin in which the recessed parts 16 and 17 are formed is The plate portion becomes thinner than the other portion B, and the thin portion A lacks rigidity. Therefore, when the vibration from the piezoelectric driver 18 is transmitted to the diaphragm 13,
Split vibration is likely to occur in the thin portion A, and
This has caused a problem in that the sound pressure frequency characteristics have peaks and valleys, resulting in poor sound quality.

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 improve sound quality by suppressing the occurrence of split vibration in the diaphragm.

In the present invention, two foamed resin plates constituting a diaphragm are joined with their wide sides facing each other, and a recess for storing a piezoelectric screwdriver is formed on both of the joined wide sides, and a recess for storing a piezoelectric screwdriver is formed in this recess. A high-rigidity plate material having projections is attached with the surface opposite to the projections facing the inner surface of the recess, and the piezoelectric driver is held between the projections.

According to the above configuration, the rigidity of the portion of the foamed resin plate that has become thin due to the formation of the recess is reinforced by the highly rigid plate material.

Back-IL-15 Hereinafter, the present invention will be specifically explained with reference to the drawings.

FIG. 1 is a sectional view showing an embodiment of a piezoelectric speaker according to the present invention, and FIG. 2 is a front view of the piezoelectric speaker.

3 in the figure is a diaphragm having a rectangular shape when viewed from the front, and is driven by a piezoelectric driver 6 provided inside to generate sound. A frame 1, which also has a rectangular shape in front view, is attached to the peripheral edge of the diaphragm 3, and an elongated tape-shaped elastic support piece 2 is provided between the rear surface of the diaphragm 3 and the frame 1.
It is interposed over the entire circumference of the diaphragm 3. The diaphragm 3 is formed by attaching two large and small rectangular foam resin plates 4 and 5 made of foamed polystyrene, foamed polyethylene, etc. with their wide sides facing each other, and the foamed resin plates 4 and 5 are bonded together with their wide sides facing each other. The end face of the foamed resin plate 4 protrudes from the end face of the foamed resin plate 5 over the entire circumference.

In the center of the facing surface of the foamed resin plate 4.5, there is a recess 4a having a circular shape, for example, for storing a piezoelectric screwdriver.

5a are provided in abutting manner. Recessed portion 4a.

The inner inner surfaces 4b and 5b of 5a are flat, and the inner inner surfaces 4
Highly rigid plates 7.8 are attached to b and 5b, respectively.

Both high-rigidity plate members 7 and 8 are formed to have the same structure and are made of a rigid material such as resin. High rigidity plate material 7 (or 8)
For example, as shown in FIG. 3, a disk-shaped base 7a
(or 8a), and a cylindrical projection 7b (or 8b) formed at the center of one side of the base 7a (or 8a). The diameters of the bases 7a, ga are set to be equal to the diameter of the recesses 4a, and on the inner surfaces 4b, 5b of the recesses 4a, 5a,
The high-rigidity plates 7 and 8 are attached to the recesses 4a and 5a by adhering the flat surfaces of the bases 7a and 8a, which have no projections 7b and 8b, with an adhesive or the like. In FIG. 3, reference numerals 7c (or 8c) indicate a plurality of circular openings (six in the illustrated example) formed in the base 7a (or 8a) in order to reduce the weight. In addition, the size of the openings 7c and 8c,
The shape and number are not limited to the illustrated example, and other shapes, sizes, and numbers may be used.

The protrusion 7 of the highly rigid plate 7.8 attached in this way
b and 8b face each other, and a piezoelectric driver 6 is held between both protrusions 7b and 8b using an adhesive or the like. The piezoelectric driver 6 has a circular shape with a smaller diameter on both sides of a circular metal plate 6a, and has piezoelectric bodies 6b, 6 made of, for example, PZT.
It is formed in a structure in which piezoelectric bodies 6b, 6 are attached concentrically.
When an electric signal is applied from an amplifier (not shown) to electrodes (not shown) formed on both sides of the piezoelectric driver 6, the piezoelectric driver 6 drives the diaphragm 3. This causes the diaphragm 3 to vibrate and emit sound.

Therefore, in the piezoelectric speaker configured in this way, the foamed resin plates 4 and 5 are used to house the piezoelectric driver 6.
Even if the recesses 4a, 5a are provided, the thin portion A formed by the recesses 4a, 5a is reinforced by the highly rigid plate material 7.8.

In the above embodiment, the highly rigid plate 7°8 is provided with two protrusions 7b and 8b, respectively. There may be.

Furthermore, the shape of the protrusions 7b and 8b is not limited to the cylindrical shape of the above-described embodiment, but may be other shapes such as a prismatic shape.

Furthermore, in the above embodiment, the diameters of the bases 7a, 8a in the highly rigid board 7°8 were set to the diameters of the recesses 4a, 5a, but the present invention is not limited to this, and substantially If the thin portion can be reinforced, the diameter can be made smaller than the diameter of the recesses 4a and 5a.

According to the present invention, the rigidity of the thin walled portion of the diaphragm due to the formation of the recessed portion can be reinforced with a high-rigidity plate material, and the generation of open vibrations in the thin walled portion is suppressed and stabilized. This has the excellent effect of being able to obtain a high sound pressure frequency characteristic and improving the sound quality.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a piezoelectric speaker according to the present invention, and FIG.
3 is a plan view showing a highly rigid plate material, and FIG. 4 is a sectional view showing a conventional piezoelectric speaker. 3...Diaphragm, 4.5...Foamed resin plate, 4a
. 5a... Concavity, 4b, 5b... Inner surface, A... Thin wall portion, 6... Piezoelectric driver 7, 8... Highly rigid plate material, 7b. 8b...Protrusion.

Claims (1)

[Claims] (1) Two foamed resin plates that make up the diaphragm are joined with their wide sides facing each other, and a recess for storing a piezoelectric screwdriver is formed on both of the joined wide sides, and this recess has a height with a protrusion on one side. A piezoelectric speaker characterized in that a rigid plate material is attached with the surface opposite to the protrusion facing the inner surface of the recess, and a piezoelectric driver is held between the protrusion part.