JPH0828918B2 - Piezoelectric speaker - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric speaker in which two foaming resin plates are attached to face each other to form a diaphragm.

2. Description of the Related Art FIG. 3 is a sectional view showing a piezoelectric speaker previously proposed by the present applicant. This proposal was made to realize a piezoelectric speaker having excellent sound pressure level, resonance frequency, and sound pressure frequency characteristics. The piezoelectric speaker is composed of two foamed resin plates 4 made of expanded polystyrene, expanded polyethylene, or the like. , 5 are attached in the front-rear direction to form the vibration plate 3, and the central portion of the piezoelectric sounding body (made of PZT etc.) 6 is sandwiched and held between the foaming resin plates 4 and 5. There is.

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention However, in the above-described piezoelectric speaker, the structure is such that only two foamable resin plates 4 and 5 are butted against each other and the both are adhered by an adhesive, and therefore, it is enlarged in FIG. As shown in the figure, the foamable resin plates 4 and 5 may be misaligned when they are attached (assembled), resulting in misalignment of the piezoelectric sounder's mounting position, and the desired characteristics cannot be obtained. There was a problem such as. Further, as one method for solving the above-mentioned problems, it is conceivable to use a dedicated jig, but such a method causes new problems such as poor workability and cost increase.

The present invention has been made in view of the above problems,
It is an object of the present invention to provide a piezoelectric speaker that can surely obtain excellent sound pressure level, resonance frequency, and sound pressure frequency characteristics with a simple structure.

Means for Solving the Problems In order to achieve the above object, a piezoelectric speaker according to the present invention has a cavity formed in a substantially central portion of a diaphragm formed by adhering two foaming resin plates in a facing manner. In a piezoelectric speaker having a structure in which a piezoelectric sounding body is sandwiched and held between a pair of protrusions protruding into the cavity, a step portion is provided at a peripheral edge portion of the one foamable resin plate, and another step portion is provided between the step portions. It is characterized by sticking a foamable resin plate.

Effect According to the configuration of the piezoelectric speaker of the present invention, when an electric signal is applied to the piezoelectric speaker, the piezoelectric speaker vibrates, and the vibration is caused by the guiding function of the step portion provided on the foamed resin plate. Is propagated to the entire foamed resin plate through the projection of the foamed resin plate that reliably supports the center, and the vibration is radiated into the air as a sound.

Embodiment FIG. 1 is a front view of a piezoelectric speaker according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along line II-II of FIG.

When vibration is applied, the diaphragm 3 that emits sound from the front side corresponding to the right side in the figure is formed by attaching two foamable resin plates 4 and 5 made of styrene foam, polyethylene foam, etc. to face each other in the front-rear direction. Formed. Both foamable resin plates 4 and 5 have a rectangular shape, but the front-side foamable resin plate 4 is slightly larger in vertical dimension than the rear-side foamable resin plate 5, and the upper and lower end portions have a rear surface side. The step portions 7, 7 are formed so as to project in the direction.
The stepped portions 7, 7 are provided for efficiently and accurately performing the attaching work described later, and are integrally formed when the foamable resin plate 4 is formed.

Annular grooves 4a, 5a are formed in the central portions of the facing surfaces of the foamable resin plates 4,5.
Are provided in a butt shape, and the piezoelectric sounding body 6 is held between these grooves 4a, 5a under pressure. Specifically, the grooves 4a, 5a
Piezoelectric speaker 6 between the circular protrusions 4b and 5b remaining in the center of the
It has a structure in which is attached using an adhesive or the like. Therefore, the height dimension of the protrusions 4b and 5b is slightly shorter than the depth dimension of the grooves 4a and 5a.

The piezoelectric sounding body 6 has a structure in which circular piezoelectric bodies 6a and 6a (for example, made of PZT) having a smaller diameter than the front and rear surfaces of a circular metal plate 6b are concentrically attached. When an electric signal is given from an amplifier (not shown), the piezoelectric speaker 6
Drives the diaphragm 3, and the diaphragm 3 emits sound from the front side. The foamable resin plate 5 located on the rear side (rear surface side) has a function as a holder for attaching the foamable resin plate 5 to the frame 1 described below, in addition to the function as a diaphragm.

A frame 1 that covers the diaphragm 3 is provided on the peripheral edge of the diaphragm 3. The frame 1 has a frame shape, and the peripheral edge portion of the diaphragm 3 is inserted and connected to the groove 1a having a U-shaped cross section formed over the entire length of the inner peripheral surface. In addition, a slender tape-shaped elastic support piece 2 is provided on the rear surface side of the step portion 7 formed on the foamable resin plate 4 over the entire circumference.
Thus, the diaphragm 3 is supported by the frame 1.

Now, the sticking work of the both foamable resin plates 4 and 5 is performed as follows. That is, an adhesive (not shown) is filled in the inner surface of the stepped portions 7,7 provided in the foamable resin plate 4 and the recess 7a formed between the stepped portions 7,7, and then the foamable resin plate 4 is formed. Insert 5 and attach both. At this time, the step 7,
The foaming resin plate 5 is adhered to the foaming resin plate 4 in the correct position by the guiding action between 7, and as a result, the piezoelectric speaker 6 is accurately attached to the vibration plate 3 in the correct position. It becomes.

In this embodiment, stepped portions 7, 7 are provided at both upper and lower ends of the foamable resin plate 4.
However, the present invention is not limited to this, and a predetermined number of step portions may be formed at the entire peripheral edge portion of the four or at a predetermined position on the peripheral edge. Further, the stepped portion may be provided with an inclined guide surface having a small inclination to further improve the positioning accuracy.

As described above, according to the piezoelectric speaker of the present invention, when an electric signal is applied to the piezoelectric speaker, the piezoelectric speaker vibrates, and the vibration is caused by the guiding action of the stepped portion provided on the foamed resin plate. Excellent sound pressure level and resonance because the vibration propagates to the entire foamed resin plate through the projection of the foamed resin plate that securely supports the piezoelectric sounding body, and the vibration is radiated into the air. The frequency and sound pressure frequency characteristics can be definitely obtained. In addition, when assembling the piezoelectric speaker, a step is provided on the peripheral edge of one foam resin plate, so the guide function of this can stick the other foam resin to the correct position. The efficiency can be improved and the cost can be reduced because a dedicated jig is not required.

[Brief description of drawings]

FIG. 1 is a front view showing a piezoelectric speaker according to the present invention, and FIG.
1 is a sectional view taken along the line II-II of FIG. 1, FIG. 3 is a sectional view of a conventional piezoelectric speaker, and FIG. 4 is a piezoelectric sounding body in the conventional piezoelectric speaker when the bonding position of a foaming resin plate is displaced. It is a partially enlarged view of the vicinity. 3 ... Vibration plate, 4,5 ... Foamable resin plate, 7 ... Step section.

Claims (1)

[Claims] 1. A vibrating plate formed by adhering two foamable resin plates to each other so as to face each other has a cavity formed in a substantially central portion thereof, and a piezoelectric speaker is provided between a pair of protrusions projecting into the cavity. A piezoelectric speaker having a structure of sandwiching and holding, wherein a step portion is provided at a peripheral portion of the one foamed resin plate, and the other foamed resin plate is stuck between the stepped portions.