JPH0686390A - Piezoelectric acoustic device - Google Patents

Abstract

PURPOSE:To fix a device so that a clearance between the peripheral wall of a case and the back face side of a housing can not be generated, to prevent the leakage of air to the outside of the case, and to obtain a required sound pressure frequency characteristic. CONSTITUTION:A case 11 is formed like an inverted try so that a bottom face side can be opened, and a recessed part 13 is formed at one part of the peripheral wall part. As for a piezoelectric element 16, the surrounding part of a diaphragm 17 is abutted to a stepped part 1 provided along the entire inner periphery of the peripheral wall of the case 11, and fixed with an adhesive constituted of a silicone resin or the like. Lead lines 19 and 20 soldered to the diaphragm 17 and piezoelectric film 18 of the piezoelectric element 16 are pulled out through the recessed part 13 to the outside of the case 11. The inner part of the recessed part 13 is packed with an elastic member having an elasticity such as the silicone adhesive, so that the lead lines 19 and 20 can be held. Moreover, a block-shaped sealing member 24 is interfit to the recessed part 13 so that the recessed part 13 can be closed.

Description

Detailed Description of the Invention

[0001]

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

[0002]

2. Description of the Related Art In a conventional piezoelectric acoustic device, for example, as shown in FIG. 5, a piezoelectric element 6 is housed in a tray-shaped case 1 having a step portion (not shown) at an intermediate portion of an inner peripheral surface thereof, and its vibration is generated. Board 7
A peripheral portion of the piezoelectric element 6 is fixed to the paragraph with a silicone adhesive 8 or the like, and the diaphragm 7 of the piezoelectric element 6 and a piezoelectric film (not shown)
Lead wires 9 and 10 respectively connected to electrodes provided on the surface of
Is drawn out from a recess 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 recess 3 to hold the lead wires 9 and 10. Contrary to the one shown in FIG. 5, this piezoelectric acoustic device is attached to the back side of the housing of a cordless phone or a mobile phone with the opening side of the case 1 facing downward.

[0004]

However, in the conventional piezoelectric acoustic device, the end surface of the sealing member 2 fitted in the recess 3 of the case 1 and the end surface of the opening of the case 1 are flush with each other. It is difficult to do so, and the end surface of the sealing member 2 may be fixed by protruding from the end surface of the case 1.
Then, as shown in FIG. 6, when the case 1 is attached toward the back surface side 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 concave portion 3 is not completely closed and a small gap is formed around the lead wires 9 and 10, air also leaks out of the case 1 from here. There was also the problem of being lost. In view of the above-mentioned conventional problems, the present invention can be mounted without forming a gap between the peripheral wall of the case and the back surface of the housing, prevents air leakage to the outside of the case, and has a required sound pressure frequency characteristic. It is an object of the present invention to provide a piezoelectric acoustic device capable of obtaining

[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.
8 is fixed to the piezoelectric element 16 and lead wires 19 and 20 connected to the electrode layers of the diaphragm 17 and the piezoelectric film 18, respectively.
And has a tray shape with one side open, and a recess 1 is formed in a part of the peripheral wall.
3, a case 11 having a piezoelectric element 16 is housed in the case 11, the peripheral portion of the vibration plate 17 of the piezoelectric element 16 is supported on the inner peripheral side of the peripheral wall, and the lead wire 19, In a piezoelectric acoustic device in which 20 is pulled out from the recess 13 of the case 11, an elastic member 22 is filled in the recess 13, and the lead wires 19 and 20 are held in the recess 13 by the elastic member 22. Further, a block-shaped sealing member 24 is fitted into the concave portion 13 to close the concave portion 13 to provide a piezoelectric acoustic device.

[0007]

In the piezoelectric acoustic device according to the present invention, the lead wires 19 and 20 are drawn 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. Since the ring-shaped sealing member 24 is fitted, the gap between the sealing member 24 and the recess 13 is completely sealed. Even if the sealing member 24 slightly protrudes from the edge of the peripheral wall of the case 11, when the case 11 is attached to the back side of the housing, the elastic member 22 is elastically deformed to form the recessed portion 1.
3 on both sides of the case 11, that is, the inner surface and the outer side of the peripheral wall of the case 11 swell and are crushed, so that the end surface of the sealing member 24 is formed on the case 11 side.
Can be attached so that the edge of the peripheral wall of the case 11 is flush with the end surface of the peripheral wall, and the edge of the peripheral wall of the case 11 is in complete contact with the back surface of the housing. Therefore, no gap is formed between the case 11 and the housing, and air does not leak to the outside of the case 11.

[0008]

Embodiments of the present invention will now 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 turned upside down. Here, the case 11 is formed of resin in the shape of an inverted tray having an open bottom side, a through hole 14 is opened in the center of the upper surface, and a polyester mesh 15 of about # 380 is stretched there. Further, a step portion 12 having a height about the middle thereof is formed over the entire inner circumference of the peripheral wall, and a recess 13 is formed in a part of the peripheral wall portion. In the illustrated embodiment, grooves 23 are formed in the vertical 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 vibrating plate 17 made of metal, and the vibrating plate 17 is provided on the step portion 12 of the case 11. The peripheral portion of the is applied and fixed by an adhesive 21 made of silicone resin or the like. In this case, the piezoelectric film 18 is mounted so that the piezoelectric film 18 side faces the side opposite to the opening of the case 11, that is, the upper side in FIG. Further, lead wires 19 and 20 are soldered to the diaphragm 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 naturally made on the upper surface side of the diaphragm 17 having the piezoelectric film 18 in FIG.

Further, an elastic member 22 having elasticity such as a silicone adhesive is filled in the inner part of the recess 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 in the recess 13. The sealing member 24 is formed of, for example, the same plastic as the case 1, and has an end surface shape of the recess 1
3 is the same as the end face shape, and ridges corresponding to the grooves 23 of the recess 13 are formed in the vertical direction on both sides. The block-shaped sealing member 24 is fitted in the recess 13 as shown in FIG. 1 from the state shown in FIG. 1, and is stopped in a state in which the elastic member 22 is slightly crushed.

The case 11 faces the inner surface of the housing 31 of a mobile phone or a cordless phone as shown in FIG. 3 (b) from the state shown in FIG. 3 (a) with its opening side facing downward. The protrusions are fused by ultrasonic welding or the like. At this time, as shown in FIG. 3B, the sealing member 24 fitted in the recess 13 is pushed by the inner surface of the housing 31, and is pushed into the recess 13 against the elasticity of the elastic member 22. Thus, the end surface of the sealing member 24 becomes flush with the edge surface of the peripheral wall of the case 11. For this reason, the edge of the peripheral wall of the case 11 is attached so as to be completely in close contact with the back surface of the housing, and as shown in FIG. 4, there is no gap between the case 11 and the housing. Therefore, air leakage to the outside of the case 11 does not occur.

[0012]

As described above, according to the present invention, the recess 13 is formed by the elastic member 22 filled in the recess 13 provided in the peripheral wall of the case 11 and the sealing member 24 fitted in the recess 13. Is completely sealed and the case 11
When attaching the back side of the housing to the recess 13
Since the sealing member 24 fitted in is pushed into the recess 13 against the elastic force of the elastic member 22, the edge of the peripheral wall of the case 11 is attached so as to be completely adhered to the back 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 can obtain a required sound pressure frequency characteristic.

[Brief description of drawings]

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

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

3A and 3B are a longitudinal side view and a state before the piezoelectric acoustic device according to the embodiment is attached to a housing, and FIG.

FIG. 4 is a side view of an essential part taken along the line AA of FIG.

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

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

[Explanation of symbols]

 1 Case 13 Recess of Case 16 Piezoelectric Element 17 Vibration Plate 18 Piezoelectric Film 19 Lead Wire 20 Lead Wire 22 Elastic Member 24 Sealing Member 31 Housing

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Hideki Oikawa 6-16-20 Ueno, Taito-ku, Tokyo Taiyo Induction Co., Ltd.

Claims (1)

[Reference number] 0040340-01 [Claims] 1. A piezoelectric film (1) on the main surface of a diaphragm (17).
8) A piezoelectric element (16) fixedly attached, lead wires (19) and (20) respectively connected to the electrode layers of the vibrating plate (17) and the piezoelectric film (18), and a tray with one side open. (1) having a shape and having a recess (13) in a part of the peripheral wall.
1) and the case (11) is provided with the piezoelectric element (1).
6) is housed, and while supporting the peripheral portion of the vibrating plate (17) of the piezoelectric element (16) on the inner peripheral side of the peripheral wall,
In a piezoelectric acoustic device in which the lead wires (19) and (20) are drawn out from the recess (13) of the case (11) to the outside thereof, an elastic member (22) is filled inside the recess (13), The elastic member (22) includes the lead wire (19),
(20) is held in the recess (13), and further the recess (1
3) A piezoelectric acoustic device, characterized in that a block-shaped sealing member (24) is fitted in and the recess (13) is closed.