JPH0117915Y2 - - Google Patents

Description

[Detailed description of the invention] Industrial application field The present invention relates to a piezoelectric sounding body having a structure in which a piezoelectric diaphragm, which is a piezoelectric ceramic plate attached to a thin elastic plate such as a metal plate, is attached to a case. This relates to a piezoelectric sounding body having a structure in which a vibration node is supported by a case.

Conventional structure and its problems A piezoelectric sounding body with a structure that supports the nodes of a piezoelectric diaphragm has a three-electrode structure with a feedback electrode, and the vibration nodes at the resonant frequency of the piezoelectric diaphragm are A so-called terminal self-oscillation type is generally used, in which a circular portion is supported by a case to obtain sharp resonance characteristics. By configuring a self-excited oscillation circuit using its resonance characteristics, this piezoelectric sounding body can generate sound near the resonance frequency of the piezoelectric diaphragm.The drive circuit is simple and the volume is large, so it can be used to generate alarm sounds and Widely used for confirmation sound.

Cross-sectional views of conventional examples of this type of piezoelectric sounding body are shown in FIGS. 1 and 2. In the piezoelectric sounding body shown in FIG. 1, the nodal part of the vibration at the resonance frequency when the piezoelectric diaphragm 1 is freely vibrated is attached to a ring-shaped protrusion 3 protruding from the case 2 of the piezoelectric sounding body with an adhesive 4. It has an attached structure. The piezoelectric sounding body shown in FIG. 2 has a structure in which a nodal portion of the piezoelectric diaphragm 1 is held between a ring-shaped projection 8 projecting from the upper case 7 and a ring-shaped projection 10 projecting from the lower case 9. It's getting old. Further, in FIG. 1, 5 is a terminal pin, and in the case of a three-terminal type sounding body, three terminal pins are provided, and the terminal pin 5 and the three electrodes of the piezoelectric diaphragm 1 are connected to lead wires 6 and 6, respectively. electrically connected by. In FIG. 2, reference numeral 11 denotes a terminal pin, which is fixed to the lower case 9 and electrically connected to three electrodes of the piezoelectric diaphragm 1 through a lead portion 12.

These three-terminal self-oscillation type piezoelectric sounding elements are widely used in various electronic devices, and there is therefore a strong demand for lower prices, but the complexity of conventional structures limits the ability to lower prices. has reached.

Purpose of the invention In view of the above-mentioned circumstances, the object of the present invention is to provide a piezoelectric sounding body that can be manufactured at a lower price.

Structure of the invention The present invention crimps and supports a piezoelectric diaphragm to a case by means of tongue pieces that are integrated with terminals fixed to the case, and connects the electrodes of the piezoelectric diaphragm and the terminals through the tongue pieces. By connecting, the above purpose is achieved.

DESCRIPTION OF EMBODIMENTS An embodiment of the present invention will be described below with reference to FIG. 3, which is a sectional view, and FIG. 4, which is a bottom view thereof. In this embodiment, 13 is a case, and this case 13 is provided with a protrusion 14 for supporting the piezoelectric diaphragm 15 in contact with the vibration node circular portion of the piezoelectric diaphragm 15, as in the conventional case. 16a, 17
Terminals a and 18a of the piezoelectric sounding body are inserted and fixed to the outer circumference of the case 13. This terminal 16a,
Elastic tongue pieces 16b, 1 are provided on 17a, 18a.
7b and 18b are integrated, respectively, and the piezoelectric diaphragm 15 is supported by the tongues 16b, 17b, and 18b with their tangential circular portions pressed against the protrusion 14 of the case. As a result, the tips of the tongues 16b, 17b, and 18b that come into pressure contact with the piezoelectric diaphragm 15 are positioned above the tips of the protrusions 14 of the case 13.

Further, the tongue pieces 16b, 17b, 18b connect to each electrode of the piezoelectric diaphragm 15 and the terminals 16a, 17a, 18a.
It also serves as an electrical connection. The piezoelectric diaphragm 15 in the embodiment shown in FIG.
In this example, tongue piece 16b electrically connects main electrode 21 of piezoelectric ceramic thin plate 20 and terminal 16a, and tongue piece 1
The return electrode 22 of the piezoelectric ceramic thin plate 20 and the terminal 1 are connected to 7b.
7a, and the tongue piece 18b connects the metal thin plate 19 which is in contact with the back electrode of the piezoelectric ceramic thin plate 2 with the terminal 18a.
is connected to.

When the piezoelectric ceramic thin plate 20 is disk-shaped, the nodal circle of the piezoelectric diaphragm 15 is often inside the diameter of the piezoelectric ceramic thin plate 20, and the tip of the projection 14 of the case 13 is inside the outer periphery of the piezoelectric ceramic thin plate 20. become. Therefore, the piezoelectric ceramic thin plate 20 is removed from the tip portion of the tongue piece 18b that should be in contact with the metal thin plate 19.
The tip of the tongue piece 18b can come into direct contact with the thin metal plate 19. When using a disc-shaped piezoelectric ceramic thin plate 20, as shown in FIG. A structure in which a folded electrode is connected to the electrode on the back side of the thin plate 20, or a structure in which no electrode is provided at all in the part where the tongue piece 18b contacts the piezoelectric ceramic thin plate 20 as shown in FIG. There is a structure in which the other tongue piece 18c is connected to the metal plate 19.

Further, the electrical connection between each tongue piece and the electrode may be a contact connection by pressure contact, but it goes without saying that a structure in which the tip of the tongue piece is soldered to the electrode may also be used.

Further, each terminal and its tongue piece may be processed as separate parts and then integrated, but it goes without saying that they can be constructed as a single part by bending a single metal piece.

Effects of the invention As described above, the present invention provides three roles to the terminal of the piezoelectric sounding body: connecting the sounding body to an external circuit, connecting the terminal to the piezoelectric diaphragm, and supporting the piezoelectric diaphragm in pressure contact with the case. This eliminates the need for adhesives to support the piezoelectric diaphragm in the case and lead wires to connect the terminals and the piezoelectric diaphragm, which are required for conventional piezoelectric sounding elements, and also makes piezoelectric sounding elements extremely easy to assemble. It is possible to provide an inexpensive piezoelectric sounding body.

[Brief explanation of the drawing]

1 and 2 are sectional views showing a conventional example of a piezoelectric sounding body, FIGS. 3 and 4 are a sectional view and a bottom view showing an embodiment of a piezoelectric sounding body according to the present invention, respectively, and FIG. 5 and FIG. 6 are partial views showing other embodiments of the present invention. 13...Case, 14...Protrusion, 15...Piezoelectric diaphragm, 16a, 17a, 18a...Terminal, 16
b, 17b, 18b...tongue piece, 19...metal thin plate, 20...piezoelectric ceramic thin plate, 21...main electrode, 2
2... Return electrode, 23... Electrode, 24... Tongue piece.

Claims (1)

[Scope of utility model registration request] A metal terminal, which has the function of attaching and fixing the piezoelectric sounding body and the function of inputting and outputting electric signals, is fixed to the outer circumference of the case of the piezoelectric sounding body, and this terminal is bent to have an elastic tongue protruding inside the case.
By aligning the position where this tongue piece contacts the piezoelectric diaphragm with the tip of the protrusion of the case for supporting the piezoelectric diaphragm, the piezoelectric diaphragm is pressed against the protrusion of the case by the elasticity of the tongue piece. A piezoelectric sounding body is formed by supporting the piezoelectric sounding body by supporting the tongue and electrically connecting the electrode of the piezoelectric diaphragm to the terminal by the tongue piece.