JPH08123426A - Piezoelectric sounder - Google Patents

Abstract

PURPOSE: To reduce the size of the above sounder and to lower its frequency with simple constitution. CONSTITUTION: This piezoelectric sounder has a case body 10 which is hollow and is opened on one surface, a cap 14 which covers the opened side of this case body 10 and a terminal member 18 which is formed of a metallic plate, has a contact part 20 projecting into the case body 10 and is projectingly formed at this cap 14. The sounder is provided with a piezoelectric diaphragm 16 which is housed in the case body 10 and to which the contact part 20 of the terminal member 18 is pressed and a stepped part 15 which is formed on the peripheral surface of the case body 10 and to which the peripheral edge of the piezoelectric diaphragm 16 is pressed. The piezoelectric diaphragm 16 is elastically pressed to the stepped part 15 by the contact part 20 of the terminal member 18 and is held in the case body 10 in the state that the piezoelectric diaphragm 16 is housed in the case body 10.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a piezoelectric sounder incorporating a piezoelectric diaphragm and driven at a predetermined frequency.

[0002]

2. Description of the Related Art A conventional piezoelectric sounder is disclosed in Japanese Utility Model Sho 63-1.
As disclosed in Japanese Patent No. 518, a piezoelectric vibrating plate is fixed to a stepped portion formed inside a case body with an adhesive, and a contact portion of a terminal fixed to a back cover is attached to an electrode portion of the piezoelectric vibrating plate. It is elastically abutted. Further, as described as a modified example in FIG. 4 and the above-mentioned publication, an annular convex portion 24 is formed on the back cover 14, and between the annular convex portion 24 and the step portion 15 of the case body 10, In some cases, the piezoelectric vibration plate 16 is sandwiched so that the bonding work is abolished.

[0003]

In the case of the prior art described above, since the peripheral edge portion of the piezoelectric vibrating plate 16 is fixed to the case main body 10, as shown in FIG. In addition, there is a problem that the vibration frequency fluctuates due to variations in fixing strength such as adhesive strength and tightening force. Moreover, the frequency is inversely proportional to the diameter of the diaphragm, and there has been a problem that miniaturization, height reduction, and frequency reduction are contradictory. Furthermore, in order to obtain a small-sized and low-frequency piezoelectric sounder, it is necessary to thin the piezoelectric diaphragm, but thinning the diaphragm deteriorates the yield at the time of manufacturing.

The present invention has been made in view of the above-mentioned problems of the prior art, and an object of the present invention is to provide a piezoelectric sounder which has a simple structure and is small in size and capable of lowering the frequency.

[0005]

SUMMARY OF THE INVENTION According to the present invention, a case body which is hollow and has one surface opened, a lid which covers the opened surface of the case body, and a metal plate which protrudes into the case body. A terminal member having a contact portion and projecting from the lid body, a piezoelectric vibrating plate housed in the case body with which the contact portion of the terminal member abuts, and a piezoelectric member formed on the peripheral surface of the case body. A receiving portion with which the peripheral edge portion of the vibration plate contacts is provided, and the piezoelectric vibration plate is elastically pressed against the receiving portion by the contact portion of the terminal member in a state where the piezoelectric vibration plate is accommodated in the case body. It is a piezoelectric sounder held in a case.

[0006]

In the piezoelectric sounder of the present invention, since the piezoelectric vibrating plate is elastically pressed against and held by the terminal member in the case body, the peripheral edge of the vibrating plate is not fixed, and the same. Even with a diaphragm having a size and a thickness, the oscillation frequency can be lowered.

[0007]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the present invention. A piezoelectric sounder of this embodiment has a cylindrical case body 10 made of resin, and a sound emission hole 12 is formed in the central portion on the front side thereof. The bottom surface side of the case body 10 is an open opening. A step portion 13 is formed over the entire circumference on the inner peripheral surface of the opening portion on the bottom surface side.
A step portion 15 as a receiving portion is formed along the inner peripheral surface of the side wall of the case body 10 at the center in the depth direction inside 0.

A lid 14 is provided at the opening of the case body 10.
Is fitted and adhered to the step portion 13. Further, inside the case body 10, a peripheral edge of a disk-shaped piezoelectric vibrating plate 16 is provided in contact with the step portion 15. Then, the hemispherical tip portion 20a of the contact portion 20 of the terminal member 18 held by the lid 14 elastically abuts on the piezoelectric vibrating plate 16, and the piezoelectric vibrating plate 16 is elastically pressed against the step portion 15. And is held in the case body 10. Then, as shown in FIG. 2, the terminal member 18 has an A on the peripheral portion of the piezoelectric vibrating plate 16 and on the surface of the piezoelectric body 17 formed on the piezoelectric vibrating plate.
The contact portions 20 elastically contact the g electrodes 19, respectively. Here, the contact portions 20 of the terminal member 18 are located on the opposite sides of the center of the piezoelectric vibrating plate 16 and are in contact with each other, and one contact portion 20 is in contact with the peripheral edge side of the Ag electrode 19. As a result, the piezoelectric vibrating plate 16 is mechanically and more stably pressed against the step portion 15 and held.

A mounting hole (not shown) is formed in the lid body 14, and the terminal member 18 is inserted through this mounting hole to be held and fixed. The terminal member 18 is integrally formed of a terminal forming metal plate such as stainless steel or phosphor bronze, and has a fold line in the longitudinal direction in order to enhance bending strength and the like. The terminal member 18 is attached by inserting the terminal member 18 from the inside of the lid 14 into the attachment hole formed in the lid 14. Then, as shown in FIG. 2, the contact portion 20 of the terminal member 18 elastically abuts on the peripheral edge portion of the piezoelectric vibrating plate 16 and the Ag electrode 19 on the surface of the piezoelectric element 17.

As shown in FIG. 3, the piezoelectric sounder of this embodiment is similar to that of the conventional piezoelectric sounder of FIG. 5, except that the piezoelectric vibrator 16 and the case body 10 having the same size are used. Even if it is vibrated, the frequency characteristics are shifted to the low frequency side as a whole, and the peak frequency is about 400.
It is in the 0 Hz range.

The shapes of the terminal member and the case body of the piezoelectric sounder of the present invention are not limited to those of the above-mentioned embodiment, and the receiving portion of the case body is not only the stepped portion but also a projection or a cylindrical shape. It is also possible to fit ones. Further, the position of the contact portion of the terminal member is only required to stably hold the piezoelectric vibration plate on the stepped portion or the like, and it is preferable that the positions are symmetrical to each other, but in some cases, it is biased to one side of the piezoelectric vibration plate. It does not matter what position it is.

[0012]

In the piezoelectric sounder of the present invention, since the piezoelectric diaphragm is not fixed to the case body, the resonance frequency of the piezoelectric diaphragm can be lowered, and the variation in frequency characteristics can be eliminated. Further, since the resonance frequency can be lowered, the desired frequency can be obtained even if the piezoelectric diaphragm is made relatively thick, and the yield at the time of manufacturing is improved. Further, the size and height can be further reduced at a desired resonance frequency, and a wide frequency band can be obtained, so that stable vibration is possible.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing a piezoelectric sounder according to an embodiment of the present invention.

FIG. 2 is a plan view of the piezoelectric diaphragm of this embodiment.

FIG. 3 is a graph showing frequency characteristics of the piezoelectric sounder of this example.

FIG. 4 is a vertical cross-sectional view showing a conventional piezoelectric sounder. .

FIG. 5 is a graph showing frequency characteristics of a conventional piezoelectric sounder.

[Explanation of symbols]

 10 Case Main Body 14 Lid Body 15 Stepped Part (Receiving Part) 16 Piezoelectric Vibration Plate 18 Terminal Member 20 Contact Part

Claims (2)

[Claims] 1. A lid having a hollow case body having an opening on one side, a lid body covering the opened surface of the case body, and a contact portion formed of a metal plate and protruding into the case body. The terminal member protruding from the body, the piezoelectric vibrating plate housed in the case main body and in contact with the contact portion of the terminal member, and the peripheral portion of the piezoelectric vibrating plate formed on the peripheral surface of the case main body are in contact with each other. And a receiving portion, and the piezoelectric vibrating plate is elastically pressed against the receiving portion by the contact portion of the terminal member in a state where the piezoelectric vibrating plate is housed in the case body and is held in the case. Sounder. 2. The piezoelectric sounder according to claim 1, wherein the contact portion of the terminal member is located in contact with peripheral portions of the piezoelectric vibration plate opposite to each other with respect to the center of the piezoelectric vibration plate.