JPS6133508B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a sound producing and sound receiving device, and more particularly to a producing and sound receiving device using a piezoelectric material as a transducer.

Conventionally, devices for producing and receiving sound waves in the audible and inaudible ranges convert electrical signals into sound waves through thin metal or plastic diaphragms using various transducers, or convert sound waves into electrical signals. I'm doing it. As transducers, there are electromagnetic, electrodynamic, and piezoelectric types for sound generating devices, and electrostatic, electret, carbon powder, and piezoelectric types for sound receiving devices. In addition, the diaphragm is generally a thin metal plate or plastic plate, so that it is lightweight and vibrates easily.
In addition, the shape and the method of supporting the diaphragm have been devised so that it is compact and has a low resonant frequency. Here, a conventional sound generating and sound receiving device using a piezoelectric material as a transducer will be described.

Figure 1 shows the structure of a conventional sounding and sound receiving device attached with a piezoelectric material (for example, piezoelectric ceramic).
~0.1~0.5mm thick and diameter mounted on ~50mm brass
20-40mm piezoelectric ceramic 1 and thin metal diaphragm 2
It has a structure in which it is attached using adhesive.

In the case of a sound generating device, electric signals are applied to the electric terminals 3 and 4 to vibrate the diaphragm 2 using the transducer of the piezoelectric ceramic 1, thereby producing sound waves in the air. In the case of a sound receiving device, the diaphragm 2 is vibrated by sound waves in the air, and electrical signals are output from the electrical terminals 3 and 4 via the transducer of the piezoelectric ceramic 1. In either case, the diaphragm 2 has a planar structure using a circular plate or a square plate to facilitate adhesion of the piezoelectric ceramic 1.

It is known that the electric-acoustic conversion efficiency of the sound generating device and the sound receiving device is maximum when the diaphragm resonates, and increases as the resonance sharpness Q increases.
Further, the resonance frequency is determined by the material and shape of the piezoelectric diaphragm and the method of supporting the diaphragm, and the same applies to Q.

Figures 2a, b, and c show the support method and the electrical terminal extraction method for a conventional sound generating and sound receiving device. (b) is one in which the edges of the diaphragm 2 are directly fixed using adhesive or caulking, and (c) is one in which the edges of the diaphragm 2 are fixed with a soft material ( For example, it refers to something that is supported using adhesive or caulking between rubber). In either case, the electrical terminal is taken out by soldering a conducting wire such as a stranded wire to the transducer and the diaphragm, or via an elastic piece.

In order to obtain a small, low-frequency sound generating and sound receiving device, the support method that provides the lowest resonance frequency using the same diaphragm is selected. It is known that the method is the smallest.

However, the method shown in Figure 2c requires
The disadvantage is that the caulking conditions are difficult and the resonance frequency varies. In other words, if the material is hard and the adhesive or caulking is too strong, the resonance frequency will become high.
There is almost no difference from the method shown in Figure 2b, and conversely, if the caulking is too loose, play may occur in the gap at the end, resulting in non-linear sound production and sound reception.
This results in a decrease in sensitivity due to a significant decrease in Furthermore, significant variations in resonance frequency occur due to changes in the material over time, cleave characteristics, etc.

On the other hand, in the method of drawing out electrical terminals, the method of soldering conductors such as stranded wires is directly attached to the movable part of the piezoelectric diaphragm, so the resonant frequency fluctuates depending on the amount of solder, and the wire breaks due to fatigue at the soldered base of the stranded wires. , variation in resonance frequency due to the hardness of the stranded wire, Q due to resonance of the stranded wire caused by adjusting the length of the stranded wire
There is a drawback in that a highly sensitive sound producing and sound receiving device with uniform resonance frequency and sensitivity cannot be obtained because of the reduction in noise and the occurrence of spurious vibrations. In addition, with the contact type using elastic pieces, depending on the contact pressure with the diaphragm, the condition of the contact surface, and the amount of current through contact, sensitivity decreases due to suppressed displacement of the diaphragm, and intermittent generation occurs due to poor contact.・It has the disadvantage that a sound receiving state occurs.

This invention was made in order to eliminate the drawbacks of the above-mentioned prior art, and by making the piezoelectric diaphragm and the electrical lead-out wire into an integrated structure, manufacturing variations and accidents caused by the mounting method of the diaphragm and the electrical lead-out wire can be avoided. The purpose is to reduce

That is, the present invention utilizes a thin flexible substrate made of a thin film of resin such as polyimide or polyester and copper foil to support the diaphragm and lead out the conductive wires.

The present invention will be described in detail below with reference to the drawings.

FIG. 3 is a cross-sectional view of an embodiment of a sound generation and sound receiving device using a piezoelectric body according to the present invention, and a piezoelectric diaphragm is constructed by attaching a piezoelectric body 11 to a metal diaphragm 12 made of brass or the like with an adhesive. . Here, the piezoelectric body 11 and the diaphragm 12 may be circular or square. A flexible printed thin board having a laminated structure of a thin resin film 13 made of polyimide or polyester and a copper foil 14 is provided around the piezoelectric diaphragm.
This flexible printed thin board is circular,
A protrusion 15 is provided in a portion thereof. Further, the inner diameter of this ring is smaller than the diaphragm 12, and the outer diameter is larger than the diaphragm 12. The diaphragm 12 and the flexible printed circuit board are fixed to each other through an adhesive 16 at their overlapping portions, and the outer peripheral portions of the flexible printed circuit board are fixed to the conductive support casings 17a and 17b by gluing or caulking. .

On the other hand, only the copper foil is extended in the protrusion 15 of the flexible substrate, and this copper foil extension is the piezoelectric body 1.
It is fixed to one side with solder 18, and forms one electrical lead wire from the piezoelectric body. The other electrical lead wire 19 is connected to the diaphragm 12 using a conventional stranded wire method.

With this configuration, the electrical lead-out from the piezoelectric body 11 can be made into a flat plate structure, and the stiffness of the lead wire, the soldering position and amount of solder to the piezoelectric body, etc. can be determined as appropriate. Variations in the acoustic characteristics of the piezoelectric diaphragm due to the drawer can be suppressed to a small level.

Also, the protrusion 15 of the flexible printed circuit board
, between the copper foil extension and the diaphragm 12,
Since there is an insulating layer made of polyimide or polyester, even if contact occurs, it will not result in a short circuit.

Furthermore, it has the feature that the electrical connection from the piezoelectric body 11 can be taken out through a part of the conductive housing 17.

On the other hand, since the diaphragm 12 is fixed to the conductive casing via a soft plastic thin plate such as polyimide or polyester, the support structure of the piezoelectric diaphragm becomes a so-called support condition, and the structure is suitable for low operating frequencies. It's summery.

FIG. 4 is a diagram showing another embodiment of the invention, in which the same parts are designated by the same reference numerals. In this example, polyimide or polyester thin film 1
A flexible printed circuit board having copper foils 14a and 14b laminated on both sides of the board 3 is used. By fixing this flexible board via a conductive adhesive 20, the electrical lead-out from the diaphragm 12 can also be taken out from a part of the casing. In this figure, 21 indicates an insulator interposed in the conductive housing 17, and the piezoelectric body 1 is
The electrical lead-out from 1 and the electrical lead-out from the diaphragm 12 are separated.

As explained above, according to the present invention, since the piezoelectric diaphragm and the electrical lead-out wire are integrated, the piezoelectric diaphragm is thin, there are fewer accidents and manufacturing variations caused by the electrical lead-out wire, and the piezoelectric diaphragm Since the holding structure serves as a supporting condition, it is possible to obtain a sound generation and sound receiving device with excellent sound generation and sound reception efficiency at low frequencies.

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a conventional piezoelectric sound generation and sound receiving device, FIG. The figure is a cross-sectional configuration diagram showing another embodiment of the present invention. 11... Piezoelectric body, 12... Vibration plate, 13... Resin thin film, 14, 14a, 14b... Copper foil, 15...
...Protrusion of flexible printed circuit board, 17...
Housing.

Claims (1)

[Claims] 1. A diaphragm to which a piezoelectric body is attached, and a resin thin film and a conductive metal whose one end is attached to the diaphragm and the other end to the casing in order to support this diaphragm in a conductive casing. An annular flexible substrate having a laminated structure of thin films is provided, and a protrusion is formed in a part of the flexible substrate, and the conductive metal thin film present in the protrusion is connected to the piezoelectric body. A piezoelectric sounding and sound receiving device characterized by: