JPS6098795A - Piezo-electric electroacoustic transducer - Google Patents

Abstract

PURPOSE:To eliminate soldering work and to facilitate assembling by providing a conductive spring-shaped body which makes pressure contact with the electrode and the diaphragm of a ceramic piezo-electric body. CONSTITUTION:A rubber elastic ring 24, piezo-electric vibrator 20 consisting of a metal diaphragm 22 to which a ceramic piezo-electric body 21 is bonded, rigid ring 25, and an exhaust chamber bord 26 to which a conductive spring bodies 32-35 are fixed on th precribed positions are assembled to put then into a case 23 in order. The edge of the cae 23 is bent and caulked with a constant force. The caulking is controlled according to the thickness of entire part to be pressed, or pressing pressure.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an electroacoustic transducer used in a telephone transmitter or receiver, and more particularly to a piezoelectric electroacoustic transducer using a ceramic piezoelectric material as a transducer. It is something.

Conventional configurations and their problems Piezoelectric vibrators, in which a ceramic piezoelectric body is attached to a metal diaphragm, have been widely used as piezoelectric electroacoustic transducers. When designing various electroacoustic transducers using this piezoelectric vibrator, important issues include how to support the piezoelectric vibrator and how to attach input/output terminals. In particular, the sounding body of a telephone is extremely thin, and the space for installing input/output terminals is extremely narrow. In the case of piezoelectric buzzers that are currently widely used, there are many examples in which the nodal circle at the time of the first resonance is supported by a rubber elastic body. In the case of a piezoelectric buzzer, there is a wide space for installing the input terminal, so it is possible to design it with sufficient consideration of mechanical strength.

In the design of a telephone handset, the fundamental resonant frequency of the pressure'lL vibrator is important, but the structure of the input/output terminals also has a great influence on the acoustic characteristics. Since the input/output terminals are installed in a narrow space, it is extremely difficult to route the lead wires from the electrode surface of the ceramic piezoelectric body. If conventional piezoelectric buzzer parts and manufacturing methods are used as they are, the piezoelectric vibrator and the back air chamber plate with acoustic leakage ports will come into contact with each other due to the thickness and length of the lead wires, the soldering height, etc., and abnormal noise will be generated. There were problems such as fluctuations in the resonant frequency.

FIG. 1 shows an example of a conventional piezoelectric electroacoustic transducer. 11
d Ceramic piezoelectric body with silver baked on both sides. Reference numeral 2 denotes a metal diaphragm which is closely bonded to the ceramic piezoelectric body 1 with an adhesive and is electrically connected to constitute a piezoelectric vibrator 3.

4 is the case, sound and arm leakage 5. It is integrated with a back air chamber plate 8 having input terminals 6 and 7. 9 is a spacer to secure the space between the diaphragm 2 and the diaphragm 2.
i'1 is the ring of the presser foot.

1o is a front air chamber plate having radial i'f, , I-, J 11. 12 electrically connects the lead wire 13 to the surface of the ceramic electric body 1.
is the half [
]" 15 is an insulator that electrically isolates the case 4 and the input terminal 6. The solder portion 7 for connecting the lead wire 17 to the 16-piece diaphragm 2 is the other input terminal, and the lead wire 17 is connected by solder 18.

19 is an insulator similar to 15.

The space to accommodate the soldering part 12.16 is approximately 0.5ml+
However, the workability during assembly was poor, and it was easy to cause breakdowns.

OBJECTS OF THE INVENTION It is an object of the present invention to provide a piezoelectric electroacoustic transducer which has a simple structure and good reproducibility of sound pressure-frequency characteristics, in order to overcome the conventional drawbacks as described above.

Structure of the Invention In order to achieve the above object, the present invention provides a piezoelectric vibrator in which a ceramic piezoelectric body is coupled to a metal diaphragm in a case integrally equipped with a front air chamber plate having sound emitting ports on two sides. Stored at a certain distance from the front air chamber plate so as to fix the peripheral edge of the
In addition, in this case (a back air chamber plate made of an insulator is connected to the DEE part so as to have a constant distance from the piezoelectric vibration r, the back air chamber plate of the It is constructed by providing an electrically conductive spring-like body that presses against the diaphragm and an acoustic leakage port, which improves ease of assembly and quality.

DESCRIPTION OF EMBODIMENTS Hereinafter, embodiments of the present invention will be explained with reference to FIGS. 2 and 3 of the drawings.

An embodiment of the present invention is shown in FIGS. 2 and 3.

20, a ceramic piezoelectric body 21 is bonded to a metal diaphragm 22 with a polymer adhesive, and the ceramic piezoelectric body 21 on the adhesive side
The electrode surface is in contact with the diaphragm 23 and is a piezoelectric vibrator configured to be electrically connected. A case 23 also serves as a front air chamber plate 28. After the parts to be stored inside are stuffed, they are fixed at the bent portions 27 by caulking. 2
4 is a ring made of a rubber-like elastic body, 25 is a rigid ring, 26 is a back air chamber plate, and 27 is a bent portion 27 of the case 23 that supports and fixes the periphery of the diaphragm 230.

Reference numeral 29 indicates a sound emitting port formed in the front air chamber plate 28, and numeral 30 indicates a sound leakage port formed in the back air chamber plate 26.

31 is a conductive spring-like body 32 bored in the back air chamber plate 26.
33 is a penetrating hole, which is sealed with resin.

The conductive spring-like bodies 32 and 33 are in contact with the electrode surface of the ceramic piezoelectric body 21, and their contact points are located slightly outwardly from the nodes of the second resonance vibration, and furthermore, they are in contact with the electrode surface of the ceramic piezoelectric body 21, and the contact points are located slightly outwardly from the nodes of the second resonance vibration. The portion exposed on the bottom surface of 26 serves as an input terminal to which the output from the amplifier is input. Similarly, 34 and 35 are conductive spring-like bodies, which are in contact with the metal diaphragm 22 and are electrically conductive.

Specifically, the ceramic piezoelectric body 21 is a piezoelectric ceramic having a large mechanical coupling coefficient Kp, the metal diaphragm 22 is an iron-sokel alloy (42% Ni), and both are adhered to each other using a modified acrylic adhesive. The case 23 is made of aluminum, the rubber-like elastic body 24 is a ring of chloroprene rubber with a hardness of 60 to 7o, the rigid ring 25 is made of brass, and the back air chamber plate 26 is made of phenolic resin. And 30 acoustic leak holes are opened. 32-35 The conductive spring-like body uses a thin plate (0.1 rttm or less) of phosphor bronze plate for spring,
In order to reduce contact pressure and maintain conductivity (1 (I') at the same time, the contact portions are plated with gold, which has good conductivity.

The assembly consists of a metal diaphragm 22 with a rubber-like elastic ring 24 and a ceramic piezoelectric body 21 bonded inside a case 23.
Another piezoelectric vibrator 20. The rigid body ring 25 and the conductive spring-like bodies 32 to 35 are fixed at predetermined positions.
This is done by folding the ends of the case 23 and caulking them with a constant force. Caulking is controlled by the overall thickness of the presser foot or the pressure of the presser foot.

The conductive spring-like bodies 32 to 33 in one embodiment of the present invention are arranged so as to be in contact with a plurality of points on a concentric circle slightly shifted outward from the node of the secondary resonance vibration of the piezoelectric vibrator 20. However, it is also possible to have a structure in which they touch at only one point. The fixing of the spring-like body is not limited to this example; it may be fixed using eyelets, or a printed circuit may be formed on the outside of the board and attached flatly. The contact pressure of the spring-like bodies 34 and 35 in contact with the metal diaphragm 22 can be made larger than the contact pressure of the spring-like bodies in contact with the electrode surface.
Both are advantageous from the viewpoint of 4nQ.

Effects of the Invention The piezoelectric electroacoustic transducer having the structure of the present invention has a simple structure, eliminates the need for soldering, and is extremely easy to assemble, and improves the visualization of sound pressure-frequency characteristics. Since there are no soldered parts, there is no risk of the diaphragm and back air chamber plate coming into contact with each other, and no abnormal noise is emitted. In addition, since the position of the contact point is shifted outward from the node of the second resonance vibration, it has the effect of lowering the first and second resonance Q. It is what it is.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional piezoelectric electroacoustic transducer, Fig. 2 is a sectional view showing an embodiment of the piezoelectric electroacoustic transducer according to the present invention, and Fig. 3 is a side view of the piezoelectric electroacoustic transducer. . 20...Piezoelectric vibrator, 21...Ceramic piezoelectric body, 22...-Vibration plate, 23-Case, 24 Ring, 25-Rigid body ring, 26...-Back air chamber plate, 2
7...--bent part, 28 front air chamber plate, 29--sound outlet, 30--acoustic leakage 1'', 31--hole, 32-
35...--Electroconductive spring-like body. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 1 32/, 3//'C ゝ, \, (?3゛b■

Claims (1)

[Claims] In a case that is integrally equipped with a front air chamber plate with a sound emitting port on the top surface, a certain area is attached to the front air chamber plate so as to fix the peripheral edge of a piezoelectric vibrator in which a ceramic piezoelectric body is bonded to a metal diaphragm. Furthermore, a back air chamber plate made of an insulating material is connected to the piezoelectric vibrator at a certain distance from the bottom of the case, and the ceramic piezoelectric electrodes of the piezoelectric vibrator and A piezoelectric electroacoustic transducer comprising a conductive spring-like body that presses against a diaphragm and an acoustic leakage port.