JPS5825677Y2 - piezoelectric speaker - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a piezoelectric speaker, and is intended to make the output sound pressure level of the second resonance equal to the output sound pressure level of the first resonance.

A conventional piezoelectric speaker was constructed as shown in FIG.

That is, a rubber damping material 2 is bonded to one side of a piezoelectric bimorph element 1, a diaphragm 3 is bonded to the other side, and this is assembled into a frame 4 made of synthetic resin or metal.

In a piezoelectric speaker with such a configuration, the Q of each resonance can be lowered by the damping material 2, but the internal loss of the piezoelectric bimorph element 1 is larger in the second resonance than in the first resonance. As a result, the frequency characteristics of the output sound pressure had a conspicuous peak at the second resonance, as shown by the broken line in FIG.

The present invention eliminates the above-mentioned drawbacks of the prior art.

Embodiments of the present invention will be described below with reference to FIGS. 2 and 3.

5 is a piezoelectric bimorph element, and this piezoelectric bimorph element 5
A diaphragm 6 is adhesively bonded to one side of the piezoelectric bimorph element 5, and a ring-shaped plate 8 made of synthetic resin or metal is adhesively bonded between the secondary resonance nodes 7 of this piezoelectric bimorph element 5. It is housed in a frame 9 made of metal, and the peripheral edge of the diaphragm 6 is coupled to the peripheral edge of the frame 9.

In addition, 10 in the figure is a lead wire for applying a signal to the piezoelectric bimorph element 5.

By attaching the ring-shaped plate 8 between the nodes 7 of the secondary resonance in this way, the surface to which the ring-shaped plate 8 is attached is a surface that causes large deflection during the secondary resonance compared to the primary resonance. Therefore, the deflection of the second resonance can be damped,
The frequency characteristics of the output sound pressure are flattened as shown by the solid line in FIG.

Since the piezoelectric speaker of the present invention is configured as described above, the output sound pressure level of the secondary resonance can be suppressed by the ring-shaped plate to be equal to the output sound pressure level of the primary resonance, and the sound Since the piezoelectric bimorph element's inertial force drives the diaphragm, the inertial force can be increased by increasing the mass of the ring-shaped plate, and a large output can be obtained. It has the advantage of being able to perform the following tasks, and is of great practical value.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of a conventional piezoelectric speaker, Fig. 2 is a sectional view showing an embodiment of the piezoelectric speaker of the present invention, Fig. 3 is a top view of the piezoelectric bimorph element of the speaker, and Fig. 4 is a sectional view of a piezoelectric speaker according to the present invention. FIG. 2 is a comparison diagram of the output sound pressure frequency characteristics of the conventional piezoelectric speaker and the piezoelectric speaker of the present invention. 5... Piezoelectric bimorph, 6... Vibration plate, 7... Second resonance node, 8... Ring-shaped plate, 9... ··flame.

Claims (1)

[Scope of utility model registration request] In a piezoelectric speaker configured by bonding a diaphragm to a piezoelectric bimorph element and incorporating this into a frame, a second
A piezoelectric speaker with a ring-shaped plate attached between the next resonance boxes.