JPH03285497A - Piezoelectric acoustic device - Google Patents

Abstract

PURPOSE:To offer the piezoelectric acoustic device with the high yield of productivity by fitting the peripheral part of a diaphragm to a ring composed of an elastic member and fixing the ring to the inner peripheral wall of a resonator. CONSTITUTION:A diaphragm 5 is composed of a metallic sheet, and a piezoelectric element 6, composed of a piezoelectric ceramic film and electrorode film, is formed on the under face of the diaphragm 5. A ring 11 holding the peripheral part of the diaphragm 5 is composed of the elastic member like a silicone rubber, etc., and on the inner peripheral side, a recessed groove 11a is provided to fit the peripheral part of the diaphragm 5. The diameter of the groove 11a is formed almost the same as that of the above-mentioned diaphragm 5. The peripheral part of the diaphragm 5 is fitted to the above-mentioned groove 11a of the ring 11, and the ring 11 is fitted and fixed to a step part 1c of the above-mentioned resonator 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a piezoelectric acoustic device such as a piezoelectric ringer or piezoelectric telephone transmitter using a piezoelectric element.

[Prior Art] A conventional example of a piezoelectric acoustic device will be explained with reference to FIGS. 4 and 5. A diaphragm 50 made of a disc-shaped metal plate has a diaphragm 50 on one main surface.
A piezoelectric element 6 consisting of a piezoelectric ceramic film and an electrode formed on the piezoelectric element 6 is formed, and this diaphragm 5 is housed in a circular container-shaped resonator l. It is supported on the inner peripheral wall. As shown in FIG. 4, the resonator 1 is closed on the lower side with a lid 7, and sound emitting holes 10.4 are provided at the center of the earthen wall of the resonator 1 and at the center of the lid 7, respectively.

In such a piezoelectric acoustic device, a stepped portion 1 is provided on the inner circumference of the resonator 1.
c is formed, and the peripheral portion of the diaphragm 5 is adhesively fixed thereto via a silicone adhesive 16. The silicone adhesive 16 develops appropriate elasticity even after curing and elastically supports the periphery of the diaphragm 5, so that when the periphery of the diaphragm 5 is rigidly attached to the inner periphery of the resonator 1. Better acoustic characteristics can be obtained.

[Problems to be Solved by the Invention] However, in the method of fixing the peripheral portion of the diaphragm 5 to the inner circumference of the resonator l using the silicone adhesive 16,
The following issues were encountered.

The first is that the process cycle time is extremely long. That is, the silicone adhesive 16 is applied to the stepped portion 1c of the resonator 10, the periphery of the diaphragm 50 is placed on the adhesive 16, and pressure is applied until the adhesive 16 hardens and becomes stable. , must be left for 12-24 hours. Since the manufacturing process is interrupted during this standing time,
It is difficult to automate the manufacturing process. The second problem is that the quality of the product tends to vary depending on the placement and location of applying the silicone adhesive 16 to the stepped portion 1c of the resonator 10. That is, if the applied amount is too large, when the peripheral portion of the diaphragm 5 is placed thereon and pressure is applied, a large amount of the adhesive 16 flows out from the stepped portion 1c, resulting in poor appearance and poor adhesion. Moreover, if the amount of application is too small, the diaphragm 5 will not be reliably bonded. Further, if the application position is biased toward the inner circumference of the stepped portion 1c, as shown in FIG. 5(a), for example, the silicone adhesive 16 protrudes inside the stepped portion and decreases on the outer circumferential side. On the other hand, if the application position is biased toward the outer circumferential side of the stepped portion 1c,
For example, as shown in FIG. 5(b), the silicone adhesive 16 protrudes to the outside of the stepped portion and decreases on the inner peripheral side. In such cases, poor adhesion often occurs.

The present invention aims to solve the problems in the conventional piezoelectric acoustic devices.

[Means for Solving the Problems] That is, the gist of the means adopted in the present invention in order to achieve the above object is that the peripheral part of the diaphragm 5 on which the piezoelectric element 6 is formed on the main surface is connected to the resonator 1. In a piezoelectric acoustic device fixed to an inner circumferential wall, the peripheral portion of the diaphragm 5 is fitted into a ring 11 made of an elastic member, and the ring 11 is attached to the resonator 1.
This is a piezoelectric acoustic device fixed to the inner peripheral wall of the

[Function] In the piezoelectric acoustic device according to the present invention, the peripheral portion of the diaphragm 5 is fitted into the ring 11 made of an elastic member, and this ring 11 is fixed to the stepped portion 1c of the resonator l, so that the ring 1! Similar to silicone-based adhesives, the diaphragm 50 elastically supports the periphery of the diaphragm 50, resulting in favorable acoustic characteristics. Since the ring 11 can be fixed to the inner peripheral wall of the resonator 1 using a fast-curing adhesive or other mechanical means, it takes a long time to harden, unlike when using a silicone adhesive. The cycle time of the manufacturing process can be shortened.

Furthermore, since the rings 11 can all have constant dimensions and properties, the peripheral part of the diaphragm 5 can be held in almost the same state, and the piezoelectric acoustic device has stable acoustic characteristics. can be provided.

[Implementation example] Next, examples of the present invention will be specifically explained.

As shown in FIGS. 1 and 2, the piezoelectric acoustic device includes a diaphragm 5 containing a piezoelectric element 6 housed in a resonator 1. As shown in FIGS.

The resonator 1 is made of plastic or metal, and projections 1811b are formed on both sides of the outer periphery of the resonator 1. Terminals 2.3 protrude downward from the projections 1a and 1b, and the terminals A flexible connecting pin 8.9 connected to 2.3 extends inside the resonator 1. Further, a stepped portion 1c is formed at the lower part of the inner circumferential wall of the resonator 1, and a sound emitting hole 10 is provided in the center of the earthen wall.

The diaphragm 5 is made of a metal plate, and a piezoelectric element 6 made of a piezoelectric ceramic film and an electrode film is formed on its lower surface. The ring 11 that holds the periphery of the diaphragm 50 is made of an elastic member such as silicone rubber, and the diaphragm 50 is attached to the inner circumference of the ring 11.
The groove 11a has a concave groove 11a into which the peripheral portion of the diaphragm 5 is fitted, and the diameter of the groove 11a is approximately the same as the diameter of the diaphragm 5. The peripheral portion of the diaphragm 5 is fitted into the groove 11a of this ring 11, and this ring 11 is fitted into the step IC of the resonator 1 and fixed.

FIGS. 3(a) and 3(b) show some examples of means for fixing the ring 11 to the stepped portion lb, and FIG. 3(a) shows
This is an example of bonding and fixing with a fast-curing adhesive 12. Figures (b) and (C) show protrusions 14, 14' and concave grooves 13. 13' are formed respectively, and these are fitted and fixed. In addition, in these FIGS. 3(8) to (C), the groove 11a of the ring 11 is
Each side of the shape is shown, and the example in FIG. 3A shows a ring 11 having a simple concave groove 11a.

On the other hand, in Figures (b) and (C), the groove 11a is formed in an L-shape, and the ring 11 contacts the lower surface of the diaphragm 5 with a very narrow width. In particular, in FIG. 3(C), the ring 11 is in circular line contact with the periphery of the diaphragm 50.

The lower surface of the resonator 1, to which the diaphragm 5 is attached in this manner, is closed with a lid 7, as shown in FIG. Before closing the lower surface of the resonator 1 with the lid 7, the connection pin 8.9 is bent upward, its tips are soldered to the surfaces of the diaphragm 5 and the piezoelectric element 6, respectively, and the terminals 2.3 are They are connected to the diaphragm 5 and the piezoelectric element 6, respectively. A circular sound emitting hole 4 is provided in the center of the lid 7.

[Effects of the invention] As explained above, in the present invention, the process cycle is short,
As there is no interruption in the process, it is easy to automate assembly. Furthermore, since the diaphragm can be easily attached to the resonator, a piezoelectric acoustic device with high productivity and high yield can be provided.

[Brief explanation of drawings]

FIG. 1 is a longitudinal sectional side view of a piezoelectric acoustic device showing an embodiment of the present invention, FIG. 2 is an exploded longitudinal sectional side view of the piezoelectric acoustic W device, and FIGS. FIG. 4 is an enlarged vertical side view of the main part of the sound W device, FIG. 4 is a vertical side view of a piezoelectric acoustic device showing a conventional example, and FIGS. 5(a) and (b) are enlarged longitudinal side views of the main part of the same piezoelectric acoustic device. It is a diagram. 1... Resonator 5... Vibration plate 6... Piezoelectric element
7... Lid body 11... Ring

Claims (1)

[Claims] The peripheral part of the diaphragm 5 on which the piezoelectric element 6 is formed on the main surface,
A piezoelectric acoustic device fixed to the inner peripheral wall of the resonator 1 is characterized in that the peripheral part of the diaphragm 5 is fitted into a ring 11 made of an elastic member, and the ring 11 is fixed to the inner peripheral wall of the resonator 1. Piezoelectric acoustic device.