JP3486139B2 - Electret condenser 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 condenser microphone that is used by being mounted on, for example, a mobile phone, a video camera or the like, and is particularly aimed at thinning.

[0002]

2. Description of the Related Art Electret condenser microphones are roughly classified into a back electret type and a front electret type. FIG. 10 shows the structure of a back electret type condenser microphone. In the figure, 1 is a front cloth made of cloth or the like, 2 is a vibrating membrane, 3 is a vibrating membrane ring that supports this vibrating membrane 2, and 4 is a back electrode (fixed electrode facing the vibrating membrane 2 to form a capacitor). ) 5 is a spacer that is interposed between the vibrating membrane 2 and the back electrode 4 to form a gap between the vibrating membrane 2 and the back electrode 4, and 6 is deposited on the back electrode 4 by vapor deposition or the like to have a thickness. Directionally electret layer,
Reference numeral 7 is an active element formed by, for example, an FET or the like by impedance conversion of an electric signal generated in the back electrode 4, and 8 is a printed wiring board supporting the active element 7,
9 is a back electrode holder that maintains a gap between the printed wiring board 8 and the back electrode 4, 10 is a connection terminal that electrically connects the input terminal of the active element 7 to the back electrode 4, and 11 is the vibrating membrane ring 3. ,
A capsule for crimping and accommodating the spacer 5, the back electrode 4, the back electrode holder 9, and the printed wiring board 8 in a stacked state is shown.

The capsule 11 is made of a conductive metal plate, and is made of a tubular body having one end side as a closing plate 11A. A sound hole 12 is formed in the closing plate 11A, and sound is introduced from the outside through the sound hole 12 to vibrate the vibrating membrane 2. FIG. 11 shows the structure of a front electret type condenser microphone. Portions corresponding to those in FIG. 10 are designated by the same reference numerals. The characteristic structure of the front electret type is a structure in which the electret layer 6 is vapor-deposited on the front surface side of the capsule 11, that is, the inner surface of the closing plate 11A.

By arranging the vibrating film 2 facing the electret layer 6 through the spacer 5 while maintaining a slight gap from the electret layer 6, the gap between the vibrating film 2 and the printed wiring board 8 is reduced. Since it suffices that the height H of the active element 7 has a slight margin, there is an advantage that the entire thickness can be made thinner than that of the back electret type condenser microphone shown in FIG.

[0005]

As shown in FIG. 11, the front electret type condenser microphone has an advantage that it can be made thin due to its structure. However,
Practically, the equipment to be mounted is being miniaturized, so further miniaturization, especially thinness, is required. The object of the present invention is that in the conventional front electret-type condenser microphone shown in FIG. 11, the plate thickness of the printed wiring board 8 occupies a high percentage of the total thickness, and the capsule 11 is added to the exposed surface of the printed wiring board 8. Focusing on the fact that there is a dead space DS corresponding to the thickness of the tightening piece 11B, the purpose is to make effective use of this dead space DS to achieve thinning.

[0006]

According to a first aspect of the present invention, a vibrating membrane ring for supporting a vibrating membrane, an active element for impedance-converting an electric signal generated in the vibrating membrane to take out the electric signal, and the active element are supported. A printed wiring board and a conductive plate, which is formed of a tubular body whose one end is a closed surface, and a sound hole is formed in the closed surface of the tubular body.
A vibrating membrane ring that supports the vibrating membrane with a small gap between the inner surface of the closed surface and the vibrating membrane is arranged, the printed wiring board is arranged on the opening side of the tubular body, and the end on the opening side is the printed wiring board. In an electret condenser microphone that is constituted by a capsule that is crimped on a plate surface and that stores a vibration film ring and a printed wiring board in a stacked manner, the printed wiring board is a printed wiring that electrically connects and supports active elements. We propose an electret condenser microphone including a first printed wiring board on which a conductor is formed and a second printed wiring board which is laminated on the first printed wiring board and has a through hole for penetrating an active element.

According to a second aspect of the present invention, in the electret condenser microphone according to the first aspect, the second printed wiring board has a peripheral shape smaller than the peripheral shape of the first printed wiring board, and the crimping piece of the capsule is We propose an electret condenser microphone with a structure in which it is crimped around the periphery of the first printed wiring board. According to a third aspect of the present invention, in the electret condenser microphone according to the first or second aspect, an electret layer is adhered and formed on the inner surface of the closed surface of the capsule, and the electret layer and the vibrating membrane are opposed to each other. We propose an electret condenser microphone with a condenser structure.

[0008]

According to claim 1 of the present invention, each thickness of the first printed wiring board and the second printed wiring board is selected to be about ½ of the thickness of the printed wiring board 8 shown in FIGS. 10 and 11. Then, when it is assumed that the same thickness is obtained by laminating and stacking,
Since the active element is mounted on the printed wiring formed on the first printed wiring board through the through hole formed on the second printed wiring board, the height H of the active element in the capsule is reduced by the thickness of the second printed wiring board. can do. As a result, there is an advantage that the entire thickness can be made smaller than that of the conventional front electret type condenser microphone shown in FIG.

According to the structure of the electret condenser microphone proposed in claim 2 of the present invention, the outer peripheral shape of the second printed wiring board is made smaller than the outer peripheral shape of the first printed wiring board. The electret condenser microphone proposed in claim 1 having a structure in which the peripheral plate surface is exposed at the opening end of the capsule and the opening end of the capsule is bent and crimped to the exposed plate surface of the second printed wiring board. Can be made thinner than the thickness.

That is, according to the electret condenser microphone proposed in claim 2 of the present invention, FIG.
By utilizing the dead space DS existing in the conventional front electret condenser microphone shown in FIG. 3 for the storage location of the first printed wiring board, the thickness of the printed wiring board 8 is equivalent to the thickness of the front electret condenser microphone shown in FIG. The advantage is that it can be made thinner.

According to the structure of the electret condenser microphone proposed in claim 3 of the present invention, the electret layer is attached to the inner surface of the closing plate of the capsule, and the vibrating membrane is arranged so as to face the electret layer to vibrate. Since the present invention is applied to a so-called front electret condenser microphone in which a condenser is composed of a film and an electret layer, it is possible to provide an electret condenser microphone thinner than the thickness of a conventional front electret condenser microphone.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows the parts corresponding to FIGS. 10 and 11 showing an embodiment of the electret condenser microphone proposed in claim 1 of the present invention, and the same reference numerals are given to the parts. The featured structure of the electret condenser microphone proposed by the present invention is that the printed wiring board 8 supporting the active element 7 has a two-layer structure of the printed wiring boards 8A and 8B, and parts such as the active element 7 are provided on one printed wiring board 8A. (Hereinafter referred to as the first printed wiring board),
The other printed wiring board 8B (hereinafter referred to as the second printed wiring board) is formed with a through hole through which a component such as the active element 7 penetrates, and its peripheral edge is projected from the outer periphery of the first printed wiring board. Crimp the open end of the capsule onto the part. With this structure, the second printed wiring board 8B
Acts as a member for fixing the first printed wiring board 8A to the capsule 11.

That is, as shown in FIG. 2, the printed wiring conductors 14A, 1 are provided on one surface of the first printed wiring board 8A.
4B and 14C are formed, and this printed wiring conductor 14A,
The second printed wiring board 8B is laminated on the formation surfaces of 14B and 14C. The first printed wiring board 8A and the second printed wiring board 8B are united with an adhesive. 2 and 3 show the front and back structures of the first printed wiring board 8A.
2 shows the structure of the front surface (joint surface) on which the printed wiring conductors 14A, 14B, 14C are formed, and FIG. 3 shows the structure of the back surface. A first common electrode 17 is adhered and formed on the periphery on the back side, and a signal electrode 18 is formed in the center so as to surround the through hole SH2. The through hole SH2 penetrates the insulating plate of the first printed wiring board 8A and is connected to the printed wiring conductor 14B shown in FIG.

A through hole SH1 is formed in the region of the first common electrode 17. The through hole SH1 penetrates the insulating plate of the first printed wiring board 8A and is connected to the printed wiring conductor 14C shown in FIG. FIG. 4 shows a state in which the second printed wiring board 8B shown in FIG. 5 is joined to the front surface side (the surface shown in FIG. 2) of the first printed wiring board 8A shown in FIG.

5 and 6 show the structures of the front and back surfaces of the second printed wiring board 8B. 5 shows the structure on the back side (back side), and FIG. 6 shows the structure on the front side (side facing the vibrating membrane 2). In this example, a ring-shaped second common electrode 19 is formed on the back side of the second printed wiring board 8B while avoiding the through hole SH3. The protrusions 19A of the second common electrode 19 are electrically contacted with the through holes SH1 shown in FIGS. 2 and 3, and are electrically continuous with the first common electrode 17 and the printed wiring conductor 14C.

The through hole SH3 contacts the printed wiring conductor 14A shown in FIG. 2, and the second printed wiring board 8B is formed.
6 is electrically connected to the gate ring 21 formed on the front side shown in FIG. The gate ring 21 contacts the conductive washer 13 (see FIG. 1) in the capsule 11 and is electrically connected to the vibrating membrane 3 through the conductive washer 13 and the vibrating membrane ring 3.

An electret layer 6 is formed on the inner surface of the closing plate 11A of the capsule 11, and the electret layer 6 and the vibrating membrane 2 face each other at a predetermined interval depending on the thickness of the spacer 5 (see FIG. 1). Retained. Therefore,
A capacitor is formed between the vibrating membrane 2 and the closing plate 11A of the capsule 11. That is, the blocking plate 11A serves as a fixed electrode. The capsule 11 is electrically connected to the second common electrode 19 formed in a ring shape on the peripheral edge of the second printed wiring board 8B on the open end side by crimping.

FIG. 7 shows a state in which the second printed wiring board 8B shown in FIG. 6 is placed and laminated on the surface of the first printed wiring board 8A shown in FIG. When viewed from the back side in a state where the first printed wiring board 8A and the second printed wiring board 8B are laminated and combined, the peripheral edge of the second printed wiring board 8B protrudes from the peripheral edge of the first printed wiring board 8A as shown in FIG. The second common electrode 19 is exposed and arranged at the protruding portion.

Therefore, by bending the open end of the capsule 11 and crimping it to the exposed surface of the second common electrode 19, the electret layer 6 is connected to the common potential through the capsule 11, and the electric circuit shown in FIG. 8 is formed. It As is clear from this electric circuit, when the vibrating membrane 2 vibrates due to sound, an electric signal is generated by the static electricity charged on the electret layer 6 on the vibrating membrane 2, and the electric signal is impedance-converted by the active element 7. It is output to the outside through the through holes SH1 and SH2.

As is clear from the above description, according to the embodiment structure shown in FIG. 1, inside the capsule, the gap G (FIG. 1) between the plate surface of the second printed wiring board 8B and the vibrating membrane is formed.
Since the height H1 of the active element 7 can be made smaller than the height H of the active element 7, the thickness T1 of the entire capsule 11 can be made smaller than that of the conventional front electret condenser microphone.

In other words, the first printed wiring board 8A for supporting the electric parts is conventionally provided with the dead space DS (see FIG. 11).
2) printed wiring board 8
B simply acts as a member that supports the first printed wiring board 8A. As a result, the second printed wiring board 8B can be viewed as a member that does not contribute to the thickness in the capsule.

Therefore, in the electret condenser microphone according to the present invention shown in FIG. 1, it can be seen that the thickness of the printed wiring board 8 is zero inside the capsule 11, which is compared with the conventional front electret condenser microphone shown in FIG. As a result, it is possible to obtain an effect that the printed wiring board 8 can be thinned by an amount corresponding to the thickness.

[0023]

Modified Embodiment The embodiment shown in FIGS. 1 to 7 describes the most preferable embodiment in which claims 1, 2 and 3 are added, and FIG. 9 shows an embodiment corresponding to claim 1 of the present invention. Show. In this embodiment, the first printed wiring board 8A and the second printed wiring board 8B have the same outer peripheral shape, and the opening end portion of the capsule 11 is crimped to the first printed wiring board 8A.

Even with this structure, the second printed wiring board 8B has through holes 15 through which components such as the active element 7 penetrate.
Since the components have A and 15B and are substantially mounted on the first printed wiring board 8A, only the thickness of the first printed wiring board 8A is added to the capsule 11 so that the second printed wiring board 8B has the same thickness. The gap G between the plate surface and the vibration film 2 is smaller than the height H of the active element 7 in this example, which is the highest among the components.

Therefore, even in the case of the structure of this embodiment, the printed wiring board 8 can be obtained from the thickness of the conventional front electret type condenser microphone shown in FIG.
It is possible to obtain an advantage that the thickness can be reduced by about ½ of the thickness. Moreover, even though the thickness of the printed wiring board 8 is substantially 1/2 of that of the conventional one, the first printed wiring board 8A and the second printed wiring board 8B are laminated and combined, thereby The printed wiring board 8A is reinforced,
It has the same strength as the printed wiring board 8 having the conventional structure.

[0026]

As described above, according to the present invention, the capsule 11 does not include the thickness of the printed wiring board 8 at all, or has a thickness of 1/2 of the thickness of the conventional printed wiring board 8. Capsule 11
Can be made thinner than before. By the way, it was possible to manufacture a condenser microphone in which the outer diameter of the capsule 11 was 6 mmφ and the thickness was 1 mm.

[Brief description of drawings]

FIG. 1 is an enlarged sectional view for explaining a most preferable embodiment of the present invention.

FIG. 2 is a plan view for explaining the structure on the front side of the first printed wiring board used in the embodiment shown in FIG.

FIG. 3 is a rear view for explaining the structure on the rear surface side of FIG.

FIG. 4 is a rear view showing a state in which a first printed wiring board and a second printed wiring board used in the embodiment shown in FIG. 1 are stacked.

5 is a rear view for explaining the structure on the rear surface side of the second printed wiring board used in the embodiment shown in FIG.

6 is a plan view for explaining the structure of the front surface of FIG.

FIG. 7 is a plan view of the first printed wiring board and the second printed wiring board used in the embodiment shown in FIG.

FIG. 8 is a connection diagram for explaining an electric circuit structure of the embodiment shown in FIG.

FIG. 9 is an enlarged sectional view for explaining a modified embodiment of the present invention.

FIG. 10 is an enlarged cross-sectional view for explaining the structure of a conventional back electret type condenser microphone.

FIG. 11 is an enlarged cross-sectional view for explaining the structure of a conventional front electret-type condenser microphone.

[Explanation of symbols]

2 vibrating membrane 3 vibrating ring 5 spacers 6 electret layers 7 Active element 8 printed wiring board 8A First printed wiring board 8B Second printed wiring board 11 capsules 11A closure plate 11B Clamping piece 12 sound holes 13 Conductive washers 14A, 14B, 14C Printed wiring conductor SH1, SH2, SH3 through hole 15A, 15B through hole 16 capacitors 17 1st common electrode 18 signal electrodes 19 Second common electrode

Front page continuation (72) Inventor Naosuke Fukada 38 Hosiden Kyushu Co., Ltd., 3024 Nakayama, Kurate-cho, Kurate-gun, Fukuoka Prefecture (56) References: Kaihei 11-187494 (JP, U) (58) Fields investigated (Int.Cl. ⁷ , DB name) H04R 19/01 H04R 19/04

Claims (3)

(57) [Claims] 1. A vibrating membrane ring for supporting a vibrating membrane, an active element for impedance-converting and extracting an electric signal generated in the vibrating membrane, a printed wiring board supporting the active element, and a conductive plate. It is configured by a tubular body having one end as a closed surface, a sound hole is formed in the closed surface of the tubular body, and the vibrating membrane ring is arranged while maintaining a slight gap with the inner surface of the closed surface. The printed wiring board is arranged on the opening surface side of the tubular body, and the end portion on the opening surface side is crimped to the plate surface of the printed wiring board, and the vibrating membrane ring and the printed wiring board are laminated. In an electret condenser microphone configured by a capsule to be stored, the printed wiring board is provided with a first printed wiring conductor that electrically connects the active element. A printed wiring board is laminated on the first printed circuit board, an electret condenser microphone which is characterized by being composed by a second printed circuit board through hole through which the said active devices are formed. 2. The electret condenser microphone according to claim 1, wherein the first printed wiring board has a peripheral shape smaller than the peripheral shape of the second printed wiring board, and the crimping piece of the capsule is the second printed wiring board. An electret condenser microphone having a structure in which it is crimped to the periphery of a printed wiring board. 3. The electret condenser microphone according to claim 1, wherein an electret layer is formed on the inner surface of the closed surface of the capsule, and the electret layer and the vibrating membrane are opposed to each other. Electret condenser microphone characterized by the structure that formed the.