JP2578773Y2 - Electret microphone - Google Patents

Description

[Detailed description of the invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electret microphone using an electret formed by being charged by polarization.

[0002]

2. Description of the Related Art FIG. 3 shows the structure of a conventional electret microphone. In the figure, reference numeral 1 denotes a microphone capsule formed of a conductive plate such as aluminum. The microphone capsule 1 is formed in a cup shape by pressing, and a sound hole 2 is formed in a portion corresponding to a bottom plate of the cup, and a portion corresponding to the bottom plate is used as a front plate 1A of the microphone. The front cloth 3 is attached to the front surface of the front plate 1A.

[0003] Inside the microphone capsule 1, a microphone unit MU is arranged at the front end side. The microphone unit MU includes a diaphragm 4 and a back plate 6. The diaphragm 4 includes a film formed of a polymer material and a metal layer adhered to the film, and the polymer film is polarized in the thickness direction to form an electret. Is a small gap with back electrode plate 6 (several tens of μm)
, And the vibration plate 4 vibrates to take out an electric signal from between the vibration plate 4 and the back electrode plate 6.

[0004] The diaphragm 4 is attached to a conductive ring 5 and is electrically connected to the microphone capsule 1 through the conductive ring 5. An insulating spacer 7 for maintaining a gap between the diaphragm 4 and the back plate 6 is interposed between the diaphragm 4 and the back plate 6, and the back plate 6 and the spacer 7, the diaphragm 4, and the conductive The ring is pressed against the front plate 1A to hold the microphone unit MU on the front end side of the microphone capsule 1.

Conventionally, in order to press the microphone unit MU to the front end side in the microphone capsule 1, conventionally, the back electrode holder 8 is used.
Is provided. In this example, the back electrode holder 8 is formed in a cup shape, the back electrode plate 6 is supported at the opening end of the cup shape, and the microphone unit MU is pressed against the front end side of the microphone capsule 1.
The bottom surface of the back electrode holder 8 is arranged at the opening of the microphone capsule 1, and the printed circuit board 9 is arranged outside the opening. Active element 11 for impedance conversion is provided inside back electrode holder 8.
Is stored. The active element 11 is generally a field effect transistor having a high input impedance, the gate electrode G serving as the input terminal thereof is connected to the back electrode plate 6, and the drain electrode D and the source electrode are printed on the bottom plate of the back electrode holder 8. It is led out to the front side of the printed board 9 through a hole formed in the board 9 and soldered to a wiring conductor formed on the front side surface. FIG. 4 shows an electrical connection structure of the electret microphone.

[0006]

The conventional electret microphone has a structure in which a microphone unit MU is arranged at the front end of a microphone capsule 1 and a printed board 9 and an active element 11 are mounted on the printed board 9 at a rear end. In addition, the connection between the active element 11 and the microphone unit MU has a three-dimensional connection structure, and there is a disadvantage that the assembly is troublesome.

An object of the present invention is to provide an electret microphone having a structure that can be easily assembled.

[0008]

According to the present invention, a microphone unit and an active element are arranged on the same surface, whereby the microphone unit and the active element are connected by a printed wiring. is there. More specifically, by forming a conductive pattern to be a back electrode plate on a printed circuit board and a printed wiring for mounting an active element for impedance conversion, and mounting the active element on the printed circuit board, it is inevitable. Is connected to the input terminal of the active element and a conductive pattern to be a back electrode plate. A spacer is formed around the periphery of the conductive pattern to be the back electrode plate with insulating ink or the like, and a diaphragm supported by being attached to a conductive ring is placed on the spacer, and a gap corresponding to the thickness of the spacer is held to hold the back plate. Face the electrode plate.

The conductive ring supporting the diaphragm is fitted into a recess formed in a closing plate of a resin capsule formed of a conductive resin material. As a result, the diaphragm is electrically connected to the resin capsule via the conductive ring. The resin capsule is constituted by a pair of cylindrical halves having one end closed. In other words, the printed circuit board and the diaphragm are internally formed by a front cylindrical half and a rear cylindrical half, and the pair of cylindrical halves are welded to each other with their open ends facing each other. To be sealed.

Therefore, according to the structure of the present invention, the microphone unit composed of the diaphragm and the back electrode plate and the active element are mounted on the same printed circuit board, so that an advantage that assembly can be easily performed is obtained.

[0011]

1 and 2 show an embodiment of the present invention.
Parts corresponding to those in FIG. 3 are denoted by the same reference numerals. That is, 9 is a printed board, 11 is an active element such as an FET mounted on the printed board 9, and 12 is the active element 1
1 shows a wiring pattern for mounting No. 1. The structure of the present invention is characterized in that a conductive pattern serving as a back electrode plate 6 is formed on a printed circuit board 9 and an insulating spacer 7 is formed on the periphery of the back electrode plate 6 with insulating ink or the like.
The vibration plate 4 supported by the conductive ring 5 via is disposed to face. A point where the microphone unit MU is constituted by the back electrode plate 6, the insulating spacer 7, the conductive ring 5 and the vibration plate 4, and the back electrode plate 6 and the input terminal of the active element 11 are connected by the wiring pattern 12. Is a point.

Reference numerals 14 and 15 denote a front cylindrical half and a rear cylindrical half forming the resin capsule 16. Each of the front cylindrical half 14 and the rear cylindrical half 15 is formed of a cylindrical half whose one end is closed by closing plates 14A and 15A. The material is formed of a conductive resin material, and welding is performed (for example, ultrasonic welding) with the opening ends facing each other, and the printed circuit board 9 and the diaphragm 4 are sealed inside by this welding.

A sound hole 2 is formed in the closing plate 14A of the front cylindrical half 14 at a position facing the diaphragm 4. Further, as shown in FIG. 2, on the back surface of the closing plate 14A of the front cylindrical half 14,
A concave portion 14B is formed so as to surround the sound hole 2. By fitting the conductive ring 5 into the recess 14B, the diaphragm 4
Is fixed, and the diaphragm 4 is electrically connected to the front cylindrical half 14, that is, the resin capsule 16. The front tubular half 14 fitted with the conductive ring 5 supporting the diaphragm 4, the printed circuit board 9, and the rear tubular half 15 are stacked together, and the front tubular half 14 and the rear tubular half are stacked. The assembly is completed by fusing the body 15 with its open ends.
The recess 14C shown in FIG. 2 is a recess for accommodating the active element 11.

A step 15B is provided on the inner periphery of the rear tubular half 15, and the printed board 9 is received by the step 15B, and an empty space is formed between the printed board 9 and the rear tubular half 15. . At the same time, a plurality of holes 17 are formed in the portion of the printed circuit board 9 where the back electrode plate 6 is formed, and the vacant space formed between the printed circuit board 9 and the rear cylindrical half 15 is formed through the holes 17. And a rear acoustic chamber is formed.

The front acoustic chamber comprises a diaphragm 4 and a front cylindrical half 14.
The acoustic characteristics of the microphone are set by the volumes of the front acoustic chamber and the rear acoustic chamber. When the microphone has bidirectional or unidirectional characteristics, a sound hole may be formed in a part of the closing plate 15A.

[0016]

As described above, according to the present invention, since the microphone unit MU and the active element 11 are mounted on the same printed circuit board 9, the input terminal (gate electrode) of the active element 11 is connected to the microphone. The conductor electrically connected to the back electrode plate 6 constituting the unit MU only needs to be formed by extending the copper foil constituting the back electrode plate 6 as the wiring pattern 12. The microphone unit MU and the active element 11 are simply mounted by soldering.
The connection with is completed. Therefore, there is an advantage that assembly can be easily performed and mass production can be easily performed.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view showing an embodiment of the present invention.

FIG. 2 is a sectional view for explaining a structure of a main part of the present invention.

FIG. 3 is a cross-sectional view for explaining a conventional technique.

FIG. 4 is a connection diagram for explaining the electrical structure of the electret microphone.

[Explanation of symbols]

 Reference Signs List 2 sound hole MU microphone unit 4 diaphragm 5 conductive ring 6 back electrode plate 7 insulating spacer 9 printed circuit board 11 active element 12 wiring pattern 14 front cylindrical half 15 rear cylindrical half 14A, 15A closing plate 16 resin capsule 17 Hole

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-207798 (JP, A) JP-A-3-6500 (JP, A) JP-A-57-112199 (JP, A) JP-A 52-207 2425 (JP, A) J. 52-23967 (JP, Y2) (58) Fields investigated (Int. Cl. ⁶ , DB name) H04R 19/04

Claims (5)

(57) [Scope of request for utility model registration] 1. A. First Embodiment B. a printed board on which a conductive pattern to be a back electrode plate and a conductive pattern for mounting an active element for impedance conversion are formed; B. an insulating spacer formed on the periphery of the conductive pattern to be the back electrode plate for maintaining a gap between the diaphragm and the back electrode plate; A diaphragm attached to the conductive ring and charged by imparting polarization to a film made of a polymer material; A resin capsule formed of a conductive resin material that is in electrical contact with the conductive ring supporting the diaphragm and covers both the front and back surfaces of the printed circuit board. 2. The electret microphone according to claim 1, wherein a conductive pattern to be a back electrode plate and an input terminal of the active element are planarly connected by a wiring pattern on the printed circuit board. 3. The resin capsule is composed of a front cylindrical half and a rear cylindrical half whose one end is closed, and the openings of these cylindrical halves are arranged to face each other, and the edges of the openings are connected to each other. 3. The electret microphone according to claim 1, wherein the diaphragm is welded to seal the diaphragm supported by the printed circuit board and the conductive ring. 4. A sound hole is formed on a closing plate of the front cylindrical half that constitutes the resin capsule in opposition to the vibration plate, and a conductive pattern to be a back electrode plate formed on the printed circuit board is formed. A through hole is formed through the printed circuit board at a position, and a space formed between the diaphragm and the closing plate of the front tubular half and a space between the rear tubular half and the printed circuit board are provided. The electret microphone according to claim 1, wherein a front acoustic room and a rear acoustic room are configured. 5. A recess surrounding the sound hole is formed on the back surface of the closing plate of the front cylindrical half, and a conductive ring supporting the diaphragm is fitted into the recess, and the conductive ring is connected to the front cylindrical member. 2. The electret microphone according to claim 1, wherein the diaphragm is electrically connected to the half body, and the diaphragm is electrically connected to the resin capsule through a conductive ring.