JP2580548B2 - Piezoelectric speaker - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a piezoelectric speaker.

2. Description of the Related Art As shown in FIG. 4, a conventional outer peripheral support type piezoelectric speaker includes a diaphragm of a piezoelectric sounding body d via an elastic support c formed of a rubber plate having an adhesive a applied to a front surface and / or a back surface. e
Is supported by the speaker frame g.

Problems to be Solved by the Present Invention Therefore, in the conventional piezoelectric speaker, since the elastic support c is formed of a rubber plate having a weak elastic force, the frequency characteristic has many peaks as compared with the dynamic speaker. There is a problem that it is unstable and the elongation on the low frequency side is poor.

SUMMARY OF THE INVENTION An object of the present invention is to solve such a conventional problem and to provide a useful piezoelectric speaker capable of obtaining a flatter frequency characteristic with a simple improvement.

Means for Solving the Problems To achieve the above object, a piezoelectric speaker of the present invention is a piezoelectric speaker in which the outer periphery of a piezoelectric sounding body is supported by a speaker frame via an elastic support, wherein the elastic support is The pressure-sensitive adhesive layer is formed of a foam, and the gap between the outer periphery of the piezoelectric sounding body and the inner periphery of the speaker frame is set to 0.5 mm to 3.0 mm, and the elastic support is The wall thickness is set between 0.5mm and 1.5mm.

According to the above configuration, the piezoelectric sounding body is supported on the outer periphery of the speaker frame via the elastic support made of a foam material having a high elasticity, and the outer periphery of the piezoelectric sounding body is optimized so that the frequency characteristics are optimal. By setting the gap dimension between the portion and the inner peripheral portion of the speaker frame and the thickness dimension of the elastic support, it is possible to obtain a piezoelectric speaker having frequency characteristics with stable flatness at all times.

Embodiments Hereinafter, the present invention will be described in detail based on the illustrated embodiments.

In FIG. 1, reference numeral 1 denotes a so-called "bimorph-type" piezoelectric speaker as one embodiment of the present invention, which includes a ring-shaped speaker frame 2 made of resin or the like, and a bending vibration type piezoelectric sounding body 3. And an elastic support 4 for supporting the piezoelectric sounding body 3 on the speaker frame 2.

The piezoelectric sounding body 3 is attached to a vibrating plate 5 made of a metal material formed in a circular shape, and to both front and back surfaces of the vibrating plate 5.
The piezoelectric plate 6 is made of PZT or the like, and the lead wires 7 electrically connect the electrodes 13 formed on the respective surfaces of the piezoelectric plates 6.

The elastic support 4 is composed of a foam 8 in which a foam material such as a foamed polyurethane foam or a foamed polyethylene foam is formed in a ring shape, and a pair of front and back surfaces such as urethane and acrylic formed on both front and back surfaces of the foam 8. It comprises pressure-sensitive adhesive layers 9 and 10. The thickness t of the elastic support 4 is set to 0.5 mm to 1.5 mm so as to optimize the frequency characteristics.

Also, this piezoelectric speaker, when assembled,
The gap dimension d between the inner peripheral portion 11 of the speaker frame 2 and the outer peripheral portion 12 of the diaphragm 5 of the piezoelectric speaker 3 is set so as to fall within a range of 0.5 mm to 3.0 mm.

The piezoelectric speaker having the thickness t and the gap d set as described above always has a stable and flat frequency characteristic. FIG. 2 shows that the thickness t is 1.0 mm,
The frequency characteristics when the gap size d is set to d = 1.5 mm are shown in comparison with other examples. The dimensions of each part are as shown in Table 1. The thickness of the vibration plate 5 and the thickness of the piezoelectric plate 6 are both 50 μm.

In the figure, the solid line indicates the frequency characteristic of the present invention, and the broken line indicates t.
= 3.0 mm and d = 0 mm, and the dashed line shows the frequency characteristics when t = 0.3 mm and d = 5.0 mm. As is clear from the figure, when the thickness t is large and the gap d is small, the sound pressure level is high but the flatness of the frequency characteristics is poor, and the reduction is particularly poor. Also, the thickness dimension t is small, and the gap dimension d
Is large, the frequency characteristics extend to a decrease, but the sound pressure level is low, and by setting the thickness t and the gap d in the above-mentioned set ranges, better frequency characteristics can be obtained. confirmed.

The present invention is not limited to the above embodiment,
Of course, the design can be changed without departing from the gist. FIG. 3 shows an assembly in which the outer peripheral portion 12 of the diaphragm 5 and the inner peripheral portion 11 of the speaker frame 2 are opposed to each other, and the gap dimension d and the wall thickness dimension t are set to predetermined dimensions. A similar result can be obtained.

Effect of the Invention As described in detail above, the piezoelectric speaker of the present invention uses a foam having a high elastic force for the elastic support for supporting the outer peripheral portion of the piezoelectric sounding body. Elongation can be effectively promoted, and furthermore, by setting the opposing gap size between the outer peripheral portion of the piezoelectric sounding body and the inner peripheral surface of the speaker frame and the thickness size of the elastic support body to optimal values,
Stable flatness of the frequency characteristics can be achieved, and a wide variety of high quality piezoelectric speakers having a wide frequency band can be obtained, and the lead wires come into contact with the corners of the diaphragm,
Cutting and damage can be prevented, and a stable energized state can be maintained.

In addition, even when assembling, it is not necessary to select the front and back of the piezoelectric sounding body by using the piezoelectric sounding body having the piezoelectric plates formed on both sides of the diaphragm, and the piezoelectric sounding body is mounted on the speaker frame in a stacked manner via the elastic support. It can be easily assembled in an extremely simple process simply by placing and bonding and fixing, so that there is a remarkable effect that work efficiency is improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view showing one embodiment of the present invention, FIG. 2 is a frequency characteristic diagram showing frequency characteristics of the present invention together with other examples, and FIG. 3 is a cross-sectional view showing another embodiment of the present invention. FIG. 4 is a sectional view showing a conventional example. 2 ... speaker frame, 3 ... piezoelectric sounding body, 4 ... elastic support, 8 ... foam, 9, 10 ... adhesive layer.

Claims (1)

(57) [Claims] 1. A piezoelectric speaker in which the outer periphery of a piezoelectric sounding body having a piezoelectric plate formed on both sides of a diaphragm via an elastic support is supported on a speaker frame, wherein the elastic support has an adhesive layer on both sides. A lead wire for electrically connecting electrodes formed on each surface of the piezoelectric plate is adhesively fixed to the adhesive layer on the pressure-sensitive adhesive layer, while an outer peripheral portion of the piezoelectric sounding body and the speaker The piezoelectric device is characterized in that the gap between the elastic support and the inner periphery of the frame is set within a range of 0.5 mm to 3.0 mm, and the thickness of the elastic support is set within a range of 0.5 mm to 1.5 mm. Speaker.