JP2522202Y2 - Electroacoustic transducer - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electro-acoustic transducer, and more particularly, to an electro-acoustic transducer using a piezoelectric ceramic.

[0002]

2. Description of the Related Art In an electroacoustic transducer having a configuration in which a piezoelectric ceramic in which a piezoelectric ceramic and a metal plate are bonded and accommodated in a case is held, an external drive circuit is connected to an electrode of the piezoelectric ceramic to form a pair. (Japanese Utility Model Laid-Open No. 64-54498 and Japanese Utility Model Laid-Open No.
-103997). In this case, the base of the spring terminal extends to the outside through the case, and an external drive circuit is connected to the extended portion.

The tip of one spring terminal is electrically connected to the exposed electrode of the piezoelectric ceramic by elastically pressing. Further, the other spring terminal is electrically connected to the other electrode of the piezoelectric ceramic via the metal plate by a distal end portion elastically pressing against the metal plate.

[0004]

SUMMARY OF THE INVENTION In the above conventional configuration,
Since the connection between the piezoelectric ceramic and the external drive circuit is made by using the spring terminal, there is an advantage that the assembly becomes easier as compared with a case where the connection is made by soldering using, for example, lead wires. In addition, since the connection is made using the elasticity of the spring terminal, a reliable electric connection that is resistant to environmental changes such as humidity and temperature changes can be obtained.

However, in such a configuration, in order to press one of the spring terminals against the metal plate, it is necessary to expose the metal plate from between the case and the piezoelectric ceramic. To reduce the size of the piezoelectric sounding body, it is conceivable to reduce the diameter of the piezoelectric ceramic while keeping the distance between the case and the piezoelectric ceramic constant, but as a result, it has good electro-acoustic conversion characteristics, especially sufficient sound pressure. Is not obtained.

An object of the present invention is to provide an electroacoustic transducer which can be easily assembled, can maintain a reliable electric connection, and can be reduced in size.

[0007]

An electroacoustic transducer according to the present invention comprises a piezoelectric vibrating plate, a case for housing and holding the piezoelectric vibrating plate, and first and second spring terminals fixed to the case. And

[0008] The piezoelectric diaphragm has a first electrode on one main surface,
A piezoelectric ceramic having a second electrode on the other main surface; a metal plate adhered to the piezoelectric ceramic so as to be electrically connected to the first electrode; and a second electrode of the piezoelectric ceramic from an outer peripheral portion of the metal plate. A conductor layer extending up to and between the conductor layer and the second electrode.
An insulating layer that electrically insulates the conductor layer and the second electrode . Further, the first spring terminal is electrically connected to a second electrode by a distal end portion being elastically pressed against the second electrode , and a base portion is fixed to the case. In addition, the second spring terminal
The distal end portion is electrically connected to the conductive layer by being elastically pressed against the conductive layer, and the base portion is fixed to the case.

[0009]

In the electro-acoustic transducer according to the present invention, since the piezoelectric vibrating plate is electrically connected by using the spring terminal, steps such as caulking and soldering are not required, and the assembly is simplified. In addition, since the spring terminals are used, it is hardly affected by environmental changes, and reliable electrical connection can be maintained. Moreover, the electrical connection is made by pressing the second spring terminal against the conductor layer extending to the other electrode of the piezoelectric ceramic. Therefore, it is not necessary to directly contact the spring terminal with the metal plate, so that the metal plate does not have to be exposed to the spring terminal side, and the metal plate can be downsized. Therefore,
The case can be reduced in size, and as a result, the electroacoustic transducer can be reduced in size.

[0010]

1 and 2 show a piezoelectric electro-acoustic transducer according to an embodiment of the present invention. In the figure, the piezoelectric electroacoustic transducer mainly includes a piezoelectric vibrating plate 1 and a front case 2 and a back case 3 that house the piezoelectric vibrating plate 1.

The piezoelectric vibrating plate 1 has a metal plate 4 and a piezoelectric ceramic 5 attached to the back surface of the metal plate. The metal plate 4 is made of, for example, 42 alloy and has a thickness of 100 μm.
m and a circular shape having a diameter of 32 mm. The piezoelectric ceramic 5 has electrodes formed on both surfaces thereof, and a first electrode (not shown) is electrically connected to the metal plate 4 by bonding.

As shown in FIG. 3, an insulating layer 6 and a conductor layer 7 are arranged on the surface of the piezoelectric vibrating plate 1 in a laminated state.
The outer peripheral portion of the conductor layer 7 is electrically connected to the metal plate 4, and extends from that portion onto a second electrode (electrode shown in the figure: hereinafter simply referred to as an electrode) 5 a of the piezoelectric ceramic 5. The insulating layer 6 is interposed between the conductor layer 7 and the piezoelectric ceramic 5, thereby electrically insulating the conductor layer 7 from the electrode 5a. The insulating layer 6 is made of, for example, an epoxy-based or acrylic-based resin, and a UV-curable resin is advantageous in manufacturing. The conductor layer 7 is made of, for example, silver, graphite, carbon, or the like mixed with a phenol resin or an epoxy resin. Both layers 6 and 7 are formed by screen printing, for example, and the film pressure is preferably 10 to 50 μm.

The front case 2 is made of aluminum, and is formed in a cap shape open toward the rear case 3 as shown in FIG. A plurality of sound emission holes 2 a are formed in the center of the front case 2. The outer peripheral edge of the front case 2 is a caulked portion 8, and the piezoelectric ceramic 1 and the two cases 2 and 3 are integrally fixed by the caulked portion 8. In addition, the piezoelectric ceramic 1 is fixed by being clamped between the caulked portion 8 of the front case 2 and the back case 3 only at the outer peripheral portion.

The back case 3 is made of resin and is formed in a substantially disk shape. The back case 3 has a concave portion 9 that opens toward the front case 2, and a sound leakage hole 10 is formed on the bottom surface of the concave portion 9. The sound leakage hole 10 is
Is covered with an acoustic resistance cloth 11 made of a Teflon mesh 2 or a nylon mesh adhered to the bottom surface of the.

The base 16 of the first and second spring terminals 12 and 13 is fixed to the bottom surface of the back case 3. At a position corresponding to the base 16 of the spring terminals 12, 13, a through-hole 14 is formed in the back case 3, and the lead-out portion 15 of the spring terminals 12, 13 passes through the through-hole 14. The lead-out portion 15 is fixed in the through hole 14 with an adhesive or the like, and its tip is connected to an external drive circuit (not shown).
Extending outward so that they can be connected to

Each of the spring terminals 12 and 13 has a tip 17 extending from the base 16 in a slightly curved state, and has a contact 18 at the tip of the tip 17. As shown in FIG. 3, both spring terminals 12 and 13 extend to the conductor layer 7 side. The contact 18 of the first spring terminal 12 contacts the electrode 5a, and the contact 18 of the second spring terminal 13 contacts the conductor layer 7. This contact is maintained by the resiliency of the tip 17 of the spring terminals 12 and 13.

When assembling the above-described electroacoustic transducer, first, the piezoelectric ceramics 5 and the metal plate 4 are bonded, and further, the insulating layer 6 and the conductor layer 7 are formed by screen printing or the like, and the piezoelectric vibrating plate 1 is formed. Configure. Next, an acoustic resistance cloth 11 is attached to the sound leakage hole 10 of the back case 3. Also, the spring terminal 1
2 and 13 are fixed to the back case 3 using an adhesive or the like. Then, the piezoelectric vibrating plate 1 and the back case 3 are inserted into the front case 2 and the caulking portion 8 is crimped to be integrated. In this case, it is not necessary to connect the spring terminals 12 and 13 to the piezoelectric vibration plate 1 by soldering or the like, and the contact of the spring terminals 12 and 13 with the electrode 5a and the conductor layer 7 is reliably maintained. Therefore, according to this embodiment, assembling is simplified, and a reliable electrical connection that is less affected by the environment can be maintained. In this case, the conductor layer 7 extends from the outer peripheral portion of the metal plate 4 to above the electrode 5a, and the second spring terminal 13 is connected to the metal plate 4 via the conductor layer 7. As a result, there is no need to provide a large gap between the piezoelectric ceramic 5 and the back case 3 for bringing the second spring terminal 13 into contact with the metal plate 4. Therefore, according to this embodiment, the diameters of the metal plate 4 and the cases 2 and 3 can be reduced while keeping the diameter of the piezoelectric ceramic 5 unchanged.
The size of the electroacoustic transducer as a whole can be reduced while maintaining the sound pressure characteristics.

As shown in FIG. 4, the insulating layer 6 and the conductor layer 7 of the piezoelectric vibration plate 1 may be formed in an annular shape. In this case, since the piezoelectric vibrating plate 1 has no directionality, automatic assembly becomes easier. In this case, the first spring terminal 12 is configured to be shorter than the second spring terminal 13 so that the contact 18 of the first spring terminal 12 is disposed on the inner peripheral side of the insulating layer 6.

The formation of the insulating layer 6 and the conductor layer 7 is not limited to the screen printing, and a thermocompression tape or the like may be used.

[0020]

The electroacoustic transducer according to the present invention has a configuration in which the above-described conductor layer and insulating layer are provided on the piezoelectric vibrating plate, and one spring terminal is pressed against the conductor layer. Therefore, according to the present invention, it is possible to realize an electroacoustic transducer that can be easily assembled, can maintain reliable electrical connection, and can be downsized.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an electroacoustic transducer according to an embodiment of the present invention.

FIG. 2 is a longitudinal sectional view thereof.

FIG. 3 is a bottom view of the piezoelectric diaphragm.

FIG. 4 is a view corresponding to FIG. 3 of another embodiment.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 piezoelectric vibration plate 2 front case 3 back case 4 metal plate 5 piezoelectric ceramic 5 a electrode 6 insulating layer 7 conductor layer 12 first spring terminal 13 second spring terminal 16 base 17 tip

Claims (1)

(57) [Scope of request for utility model registration] 1. A piezoelectric ceramic having a first electrode on one main surface and a second electrode on the other main surface, and a metal adhered to the piezoelectric ceramic so as to be electrically connected to the first electrode. A conductive layer extending from an outer peripheral portion of the metal plate onto a second electrode of the piezoelectric ceramic; and a conductive layer and a second electrode disposed between the conductive layer and the second electrode. A piezoelectric vibrating plate having an insulating layer that electrically insulates the piezoelectric vibrating plate; a case for housing and holding the piezoelectric vibrating plate; And a first spring terminal having a base fixed to the case, and a distal end elastically pressed against the conductive layer to be electrically connected to the first spring terminal, and the base fixed to the case. An electroacoustic transducer comprising: a second spring terminal;