JPH0134479Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a bidirectional type electret condenser microphone.

A conventional bidirectional electret condenser microphone will be explained with reference to FIG.
1 is a cylindrical metal case having a sound hole 1a in the center of the top surface, 2 is an acoustic resistance material for front braking, 3 is a metal front braking plate that holds the acoustic resistance material 2 for front braking, and 3a is a front braking A sound hole is formed in the plate 3, 4 is a diaphragm having a metal vapor deposited layer (not shown in FIG. 1) formed on the front surface, and 5 is a metal ring for membrane mounting arranged on the back side of the front damping plate 3. The metal vapor deposited layer of the vibrating membrane 4 is electrically connected to the membrane tensioning metal ring 5. 6 is a gear spacer, 7 is a fixed electrode, 8 is a back hole formed in the fixed electrode 7, 9 is an insulator having a back hole 9a, 10 is an acoustic resistance material for the back surface, 11 is an electrical impedance conversion element, and 12 is a back hole. Hole 12a
One lead 11a of the electrical impedance conversion element 11 is pressed against the fixed electrode 7 by the tongue piece 9b of the insulator 9, and the other lead 11b is pressed against the fixed electrode 7 by the tongue piece 9b of the insulator 9. The printed circuit board 1 is inserted through the hole 12b.
Solder 13 is attached to the back side of 2.

In the conventional electret condenser microphone having the above configuration, the front brake plate 3 is formed of a metal body in order to establish electrical conduction between the membrane-covering metal ring 5 and the cylindrical metal case 1, resulting in a problem of high material cost. It was hot. Furthermore, it is acoustically desirable for a bidirectional microphone to have its front side and back side symmetrically configured with respect to the diaphragm 4, but if you try to configure it symmetrically like this, you will have to use a metal front brake. There was a problem that the shape of the plate 3 became complicated and the manufacturing cost further increased.

Note that in order to make the front side and the back side symmetrical with respect to the diaphragm 4, the number of sound holes 3a formed in the front damping plate 3 and the back holes 8 formed in the fixed electrode 7,
The acoustic structure, such as position and hole diameter, may be configured symmetrically.

In view of the above points, it is an object of the present invention to provide a bidirectional type electret condenser microphone equipped with a front damping plate that is inexpensive and can be easily formed into a complicated shape.

That is, the present invention provides a vibrating membrane on which a metal vapor deposited layer is formed, a metal ring for membrane tensioning through which the metal vapor deposition layer of the vibration membrane is electrically connected, and a metal ring for membrane tensioning disposed between the metal ring for membrane tensioning and a cylindrical metal case. a front brake plate made of resin, and a fixed electrode arranged on the back side of the diaphragm, the number of sound holes formed in the front brake plate and the number of back holes formed in the fixed electrode. , configuring the acoustic configuration such as position and hole diameter to be almost symmetrical with respect to the diaphragm, and electrically connecting the membrane-clad metal ring and the cylindrical metal case to the outer surface of the front brake plate. The front brake plate is made of resin and the outer surface is plated to create electrical continuity between the membrane-covering metal ring and the cylindrical metal case, making the front brake plate inexpensive. Moreover, it is easy to manufacture the front brake plate into a complicated shape that brings it close to the diaphragm, so it is possible to configure the front side and the back side to be almost symmetrical with respect to the diaphragm. This makes it possible to provide a bidirectional electret condenser microphone that is easy to make and can easily produce acoustic effects with little distortion, and is therefore inexpensive, suitable for mass production, and has high reliability.

Hereinafter, embodiments of the present invention will be described based on the drawings.

FIG. 2 is a sectional view of a bidirectional electret condenser microphone according to an embodiment of the present invention, FIG. 3 is an enlarged sectional view of the main parts of the bidirectional electret condenser microphone, and FIG. Components that are the same as those shown in are given the same reference numerals and their explanations will be omitted. In FIGS. 2 and 3, reference numeral 14 is a front brake plate made of resin having a sound hole 14a, and the outer surface of the front brake plate 14 is plated with metal 15 at appropriate locations, as shown in detail in FIG. is applied, and this metal plating 1
5, the membrane tensioning metal ring 5 and the cylindrical metal case 1 are electrically connected. This metal plating 1
5, since the metal ring 5 for coating is generally made of brass nickel plating, it is advantageous in terms of reliability to use the same type of nickel plating. Note that 4a in FIG. 3 is a metal vapor deposition layer formed on the front surface of the vibrating membrane 4. In addition, the front damping plate 14 is shaped so that the surface corresponding to the diaphragm 4 approaches the diaphragm 4, and the acoustic structure on the front side and the back side of the diaphragm 4 is made almost symmetrical, so that the acoustic resistance due to the air capacity is reduced. are made equal, resulting in an acoustic effect with less distortion. At this time, since the front brake plate 14 is made of resin, it is easy to manufacture it into a complex shape that allows the acoustic configuration to be approximately symmetrical.

FIG. 4 is a cross-sectional view of a bidirectional type electret condenser microphone in another embodiment, and the difference between the front side and the back side of the diaphragm 4 is further improved than in the embodiment shown in FIGS. 2 and 3. The structure is symmetrical. In this example, the rear acoustic resistance material 16 is formed into a disk shape, and one lead 11a of the electrical impedance conversion element 11 and the fixed electrode 7 are electrically connected via the terminal plate 17. . Further, the insulator 18 is composed of divided bodies 18a to 18e, and the rear sound hole 19 is formed on the side surface of the cylindrical metal case 1.

As explained above, according to the present invention, the front brake plate is made of resin and the outer surface is plated to provide electrical continuity between the membrane-covering metal ring and the cylindrical metal case. It is possible to manufacture the front brake plate at a low cost, and it is also easy to manufacture the front brake plate into a complex shape that brings it close to the diaphragm, so the front and rear sides are configured to be almost symmetrical with respect to the diaphragm. It is possible to provide a bidirectional type electret condenser microphone which is easy to perform and can easily obtain an acoustic effect with little distortion, is therefore inexpensive, suitable for mass production, and has high reliability.

[Brief explanation of drawings]

Fig. 1 is a sectional view of a conventional bidirectional electret condenser microphone, Fig. 2 is a sectional view of a bidirectional electret condenser microphone according to an embodiment of the present invention, and Fig. 3 is a sectional view of a bidirectional electret condenser microphone according to an embodiment of the present invention. FIG. 4 is an enlarged sectional view of a main part of a bidirectional type electret condenser microphone, and FIG. 4 is a cross sectional view of a bidirectional type electret condenser microphone in another embodiment. 1... Cylindrical metal case, 4... Vibration membrane, 4a...
...Metal deposition layer, 5...Metal ring for film tensioning, 7...
...Fixed electrode, 8...Back hole, 14...Resin front brake plate, 14a...Sound hole, 15...Metal plating.

Claims (1)

[Scope of utility model registration request] A vibrating membrane on which a metal vapor deposited layer is formed, a metal ring for membrane tensioning through which the metal vapor deposition layer of this vibration membrane is electrically connected, and a resin-made metal ring disposed between the metal ring for membrane tensioning and a cylindrical metal case. comprising a front brake plate and a fixed electrode arranged on the back side of the vibrating membrane,
The sound holes formed in the front damping plate and the back holes formed in the fixed electrode are arranged so that their acoustic configuration, such as the number, position, hole diameter, etc., are almost symmetrical with respect to the diaphragm, and A bidirectional electret condenser microphone in which the outer surface of the brake plate is plated with metal to electrically connect the metal ring for membrane covering and the cylindrical metal case.