JPS6031432B2 - Piezoelectric electroacoustic transducer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of a piezoelectric electroacoustic transducer that aims to reduce the number of parts and improve mass productivity.

A conventional converter of this type has a structure as shown in the sectional view of FIG. 1, for example.

To explain the configuration and operation in the figure, the substrate 1 is
A bimorph diaphragm is formed by fixing to the substrate 1, which is made of a conductive material such as yellow steel, and which is made of ceramic or the like and has electrode layers on both sides. A lead wire 5 is attached to one surface of the piezoelectric plate 2 by soldering or the like. The other end of the lead wire 5 is connected to a terminal plate 7 fixed to the back cover 4 with an eyelet fitting 6 or the like. On the other hand, the conductive structure on the board 1 side is such that the terminal board 8 is connected through the conductive protection plate 3.
It is configured to be connected to. Therefore, by applying an alternating current signal between the terminal plates 7 and 8, the /dimorph diaphragm generates a vibrational displacement according to the applied signal, generates a sound wave, and operates as an electroacoustic transducer.

Although the operation as a receiver has been described above, it is well known that this converter is reversible and can also operate as a microphone. The structure of the conventional converter as described above has a drawback in that it cannot be expected to improve manufacturability by automating the process of connecting lead wires.

The present invention was made to eliminate the drawbacks of the conventional transducers as described above, and therefore, an object of the present invention is to provide a piezoelectric electroacoustic transducer with improved manufacturability.

The main points of the structure of this invention are a piezoelectric bimorph diaphragm made by fixing a piezoelectric plate on a conductive substrate, and a terminal board having metal foil printed or pasted on both sides of an annular or arc-shaped insulating plate. In the piezoelectric electroacoustic transducer which is stacked and housed in a case, the terminal plate is formed with a first tongue-like part that projects outside the case and a second tongue-like part that projects inward of the annular shape. , one surface of the terminal plate is in contact with or bonded to the conductive substrate, and a metal foil surface of a second tongue-shaped portion protruding inwardly in an annular shape on the other surface is electrically connected to the surface of the piezoelectric plate. .

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 2a is a sectional view showing an embodiment of the present invention. FIG. 2b is a bottom view of FIG. 2a with the back cover 4 removed. 1 is a conductive substrate, 2 is a piezoelectric ceramic plate, 3 is a protection plate made of an insulating material such as plastic, 4 is a back cover made of the same material as the protection plate 3, 11 is a tongue piece 11-1,
11-2, and both sides of the insulating plate 11 are provided with conductive layers 12-1, 12-1 having metal foil printed or pasted on them.
2-2 to constitute a terminal board. put it here,
Converter case (protection plate 3 and back cover 4)
We will explain how to lead out the electrical terminals to the outside. Said substrate 1
is electrically led out to the outside by contacting or joining the conductive layer 12-1 provided on the terminal plate, and one piezoelectric ceramic plate 2 side is coated with a conductive paste or coated with a metal foil tape or conductive wire 13. It is connected to the conductive layer 12-2 of the terminal board with solder or the like, allowing electrical output to the outside. As mentioned above, FIG. 2b is a plan view when viewed from below with the back cover 4 of FIG. 2a removed, and is shown to clarify the structure of the terminal board.

That is, the tongue pieces 11-1 and 11-2 in and out of the case.
structure and the conductive layer 12-2 from the piezoelectric ceramic plate 2
Connection by metal foil tape or conductive wire 13 to is clearly shown. FIG. 2c shows conductive layers 12 on both sides of the insulating plate 11.
-1, 12 - 2 is divided into two in an arc shape to form 11a and 11b, and a feedback electrode 2, which is generally used for self-excited oscillation, is provided on the piezoelectric ceramic plate 2.
-2 is a plan view seen from below when the back cover 4 is removed, similar to FIG. It's the same as what I did.

In this case, in order to fix the peripheral parts of the board 1 all around, the terminal plates 1 1a and 1 1b should be made semicircular, or the terminals should be provided at the part of the back cover 4 that contacts the board 1'. It is preferable to provide a convex portion having the same size as the thickness of the plates 11a and 11b.

In addition, as a method for taking out the terminal of the return electrode 2-2, in FIG.
Instead, a ring-shaped printed wiring board is used as the terminal board, and only the conductive layer on the wiring board is divided into two, one for 12-2a and one for 12-2.
This can also be achieved by using a conductive layer for 12-2b. FIGS. 3 and 4 are sectional views showing modified embodiments of the present invention, respectively.

FIG. 3 shows the conductive layer 1 on the side of the terminal board that contacts the substrate 1.
By removing a portion 12-la of 2-1 by etching or the like, the vibrating portion of the substrate 1 is not inhibited.

In FIG. 4, an annular member 14 made of a conductive material is inserted between the tongue piece 11-2 and the board 1 in order to separate the tongue piece 11-2 of the terminal plate from the board 1. By doing so, it is possible to eliminate the cause of the tongue pieces 11-2 coming into contact with the substrate 1 during large-amplitude operation, which tends to generate abnormal sounds. Note that the terminal board described above (the conductive layer 12 on the insulating plate 11
- and 12-2), a deformable flexible printed board can be used, thereby allowing flexibility in the method of attaching the converter and the circuit network. can.

As explained above, according to the present invention, it is possible to take out the terminals of the converter using a terminal plate in which a conductive layer is formed by printing or pasting metal foil on both sides of an insulating plate, and a metal foil tape or conductive wire. This configuration has the advantage that it is possible to automate the manufacturing process and improve mass productivity of piezoelectric electroacoustic transducers.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example of a conventional piezoelectric electroacoustic transducer, FIG. 2a is a sectional view showing an embodiment of the present invention, and FIG. FIG. 2c is a bottom view of the removed state viewed from below, and FIG. 2c is a bottom view similar to FIG. FIG. 7 is a sectional view of a main part showing a modified embodiment of the invention. In the figure, 1 is a substrate, 2 is a piezoelectric ceramic plate, 2-2
is a return electrode, 3 is a protection plate, 4 is a back cover, 5 is a lead wire, 6 is an eyelet fitting, 7 and 8 are terminal plates, respectively, 11-1 and 11-2 are tongue pieces, 12-1 and 12-2. are conductive layers, 13 are metal foil tapes or conductive wires, and 14 are respectively conductive layers.
indicates a ring-shaped object made of a conductor. Figure 1 Figure 2 Figure 2 Figure 3 Figure 4

Claims (1)

[Claims] 1 A piezoelectric bimorph diaphragm made by fixing a piezoelectric plate on a conductive substrate and a terminal board made of an annular or arc-shaped insulating plate with metal foil printed or pasted on both sides are stacked and placed in a case. The terminal board is formed with a first tongue-shaped part that projects outside the case and a second tongue-shaped part that projects inward in the annular shape, and one surface of the terminal board contacts or contacts the conductive substrate. A piezoelectric electroacoustic transducer characterized in that a metal foil surface of a second tongue-shaped portion that is joined and protrudes toward the annular inner side of the other surface is electrically connected to the surface of the piezoelectric plate.