JP3137763B2 - Piezo acoustic device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an improvement in a piezoelectric acoustic device which uses a piezoelectric element and is used as a receiver for telephones and other telephones.

[0002]

2. Description of the Related Art In a conventional piezoelectric acoustic device, for example, as shown in FIG. Board 7
Of the piezoelectric element 6 and a piezoelectric film (not shown).
Lead wires 9, 10 connected to electrodes provided on the surface of
Is drawn out of the concave portion 3 provided in a part of the peripheral wall of the case 1. Further, a block-shaped sealing member 2 made of the same material as the case 1 is fitted and fixed in the concave portion 3 to hold the lead wires 9 and 10. This piezoelectric acoustic device is mounted on the back side of the housing of the cordless phone or the mobile phone with the opening side of the case 1 facing downward, opposite to that shown in FIG.

[0004]

However, in the conventional piezoelectric acoustic device, the end face of the sealing member 2 fitted into the recess 3 of the case 1 and the end face of the opening of the case 1 are exactly flush. It is difficult to do so, and the end face of the sealing member 2 may be protruded from the end face of the case 1 and fixed.
Then, as shown in FIG. 6, when the case 1 is attached to the back surface of the housing 31, a gap 5 is formed between the case 1 and the housing 31. In such a state, air escapes from the gap 5, and there is a problem that sufficient sound pressure frequency characteristics cannot be obtained on the front side of the housing 31.

Further, in this conventional piezoelectric acoustic device, since the recess 3 is not completely closed and a small gap is formed around the lead wires 9 and 10, air leaks out of the case 1 therefrom. There was also a problem that would. In view of the above-mentioned conventional problems, the present invention can be mounted so that no gap is formed between the peripheral wall of the case and the back side of the housing, prevent air leakage to the outside of the case, and achieve a required sound pressure frequency characteristic. It is an object of the present invention to provide a piezoelectric acoustic device capable of obtaining the following.

[0006]

That is, according to the present invention, in order to achieve the above object, the piezoelectric film 1 is formed on the main surface of the diaphragm 17.
And the lead wires 19 and 20 connected to the vibrating plate 17 and the electrode layer of the piezoelectric film 18, respectively.
It has a tray shape with one side open, and a recess 1
And a case 11 that accommodates the piezoelectric element 16 in the case 11, supports a peripheral portion of the diaphragm 17 of the piezoelectric element 16 on the inner peripheral side of the peripheral wall, and includes the lead wire 19, An elastic member 22 is filled in the interior of the recess 13 in the piezoelectric acoustic device in which the lead 20 is drawn out of the recess 13 of the case 11. Further, there is provided a piezoelectric acoustic device in which a block-shaped sealing member 24 is fitted into the concave portion 13 and the concave portion 13 is closed.

[0007]

In the piezoelectric acoustic device according to the present invention, the lead wires 19 and 20 are passed through the recess 13 provided in the peripheral wall of the case 11, the elastic member 22 is filled in the recess 13, and the recess 13 is blocked. The gap between the sealing member 24 and the recess 13 is completely sealed because the sealing member 24 having the shape of a circle is fitted. Even when the sealing member 24 slightly protrudes from the edge of the peripheral wall of the case 11, when the case 11 is mounted on the back surface side of the housing, the elastic member 22 is elastically deformed by the elastic member 22.
3, that is, swelling and collapsing on the inside and outside of the peripheral wall of the case 11, the end face of the sealing member 24 is
The case 11 can be attached such that the edge of the peripheral wall of the case 11 is completely in close contact with the rear surface of the housing. Therefore, no gap is formed between the case 11 and the housing, and no air leaks to the outside of the case 11.

[0008]

Next, an embodiment of the present invention will be described in detail with reference to the drawings. 1 and 2 show an embodiment of the present invention, in which the case 11 is upside down. Here, the case 11 is formed of a resin in the shape of an inverted tray whose bottom side is open. A through hole 14 is formed in the center of the upper surface, and a polyester mesh 15 of about # 380 is stretched here. Further, a step 12 having a height of about the middle is formed over the entire inner periphery of the peripheral wall, and a recess 13 is formed in a part of the peripheral wall. In the illustrated embodiment, grooves 23 are formed in the longitudinal direction on the opposite side walls of the recess 13. Case 1 like this
Can be made, for example, by injection molding a resin.

The piezoelectric element 16 is formed by fixing a piezoelectric film 18 having electrode layers on both main surfaces of a piezoelectric ceramic on a metal vibration plate 17. The vibration plate 17 is mounted on the step 12 of the case 11. And fixed by an adhesive 21 made of a silicone resin or the like. In this case, the piezoelectric film 18 is mounted so that the piezoelectric film 18 side faces the opposite side to the opening of the case 11, that is, faces upward in FIG. Further, lead wires 19 and 20 are soldered to the vibration plate 17 and the piezoelectric film 18, respectively.
The lead wires 19 and 20 are drawn out of the case 11 through the recess 13. The connection between the piezoelectric element 16 and the lead wires 19 and 20 is made on the upper surface side of the vibration plate 17 having the piezoelectric film 18 in FIG.

Further, an elastic member 22 having elasticity, such as a silicone-based adhesive, is filled in a deep portion of the concave portion 13. The lead wires 19 and 20 are embedded in the elastic member 22 and held in the recess 13 so as not to move. Further, a block-shaped sealing member 24 is fitted into the recess 13. The sealing member 24 is formed of, for example, the same plastic as that of the case 1 and has an end face shape of the concave portion 1.
3, and a ridge corresponding to the groove 23 of the recess 13 is formed in the longitudinal direction on both sides. The block-shaped sealing member 24 is fitted into the recess 13 from the state shown in FIG. 1 as shown in FIG. 2, and is stopped while the elastic member 22 is slightly crushed.

The case 11 is placed on the inner surface of a housing 31 of a portable telephone or a cordless phone as shown in FIG. 3B from the state shown in FIG. It is fused by means such as projection ultrasonic welding. At this time, as shown in FIG. 3 (b), the sealing member 24 fitted in the recess 13 is pushed by the inner surface of the housing 31 and is pushed deep into the recess 13 against the elasticity of the elastic member 22. As a result, the end surface of the sealing member 24 is flush with the edge surface of the peripheral wall of the case 11. For this reason, the peripheral wall of the case 11 is attached so that the edge of the peripheral wall is completely adhered to the back surface of the housing, and as shown in FIG. 4, there is no gap between the case 11 and the housing. Therefore, no air leakage to the outside of the case 11 occurs.

[0012]

As described above, according to the present invention, the elastic member 22 filled in the concave portion 13 provided on the peripheral wall of the case 11 and the sealing member 24 fitted in the concave portion 13 form the concave portion 13. Is completely sealed and the case 11
When attaching to the back side of the housing,
The sealing member 24 fitted into the housing 11 is pushed into the recess 13 against the elasticity of the elastic member 22, so that the edge of the peripheral wall of the case 11 is completely attached to the rear surface of the housing. Therefore, it is possible to provide a piezoelectric acoustic device that does not leak air to the outside of the case 11 and that can obtain required sound pressure frequency characteristics.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of a piezoelectric acoustic device according to an embodiment of the present invention.

FIG. 2 is a perspective view of the piezoelectric acoustic device showing the embodiment.

FIG. 3 is a longitudinal sectional view (b) of a state before the piezoelectric acoustic device according to the embodiment is attached to a housing (a) and an attached state.

FIG. 4 is a side view of a main part taken along line AA of FIG. 3 (b).

FIG. 5 is an exploded perspective view of a piezoelectric acoustic device showing a conventional example.

FIG. 6 is a perspective view of the conventional piezoelectric acoustic device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Case 13 Case recess 16 Piezoelectric element 17 Vibration plate 18 Piezoelectric film 19 Lead wire 20 Lead wire 22 Elastic member 24 Sealing member 31 Housing

────────────────────────────────────────────────── ─── Continued on the front page (72) Inventor Hideki Oikawa 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Yuden Co., Ltd. (58) Field surveyed (Int. Cl. ⁷ , DB name) H04R 17/00

Claims (1)

(57) [Claims] A piezoelectric film (1) is provided on a main surface of a diaphragm (17).
8) a piezoelectric element (16) to which is fixedly attached; lead wires (19) and (20) connected to the vibrating plate (17) and the electrode layer of the piezoelectric film (18); (1) having a concave shape (13) in a part of the peripheral wall.
1), and the piezoelectric element (1) is provided in the case (11).
6), the peripheral portion of the piezoelectric element (16) around the diaphragm (17) is supported on the inner peripheral side of the peripheral wall, and
In a piezoelectric acoustic device in which the lead wires (19) and (20) are drawn out of the recess (13) of the case (11), an elastic member (22) is filled in the interior of the recess (13). An elastic member (22) for the lead wire (19);
(20) is held in the recess (13).
A piezoelectric acoustic device characterized in that a block-shaped sealing member (24) is fitted into 3) and the concave portion (13) is closed.