JP2001054196A - Electret condenser microphone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain an electret condenser microphone with a thin profile and less number of components. SOLUTION: In the electret condenser microphone where a fixed electrode 6 and a diaphragm 4 are placed at a prescribed interval to detect a sound signal given to the diaphragm 4 due to the change in a static capacitance between the electrode 6 and the diaphragm 4, the fixed electrode 6, the diaphragm 4 and semiconductor element 8 are contained in a box type case 9 made of an insulating material side by side.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to an electret condenser microphone.

[0002]

2. Description of the Related Art The structure of a conventional electret condenser microphone is shown in FIG. It is made of an electret material in which a surface cloth 21 is provided on the top surface of a cylindrical metal case 22 having a sound hole 22a in the center, and a metal layer is formed on the surface by vapor deposition or the like via a film ring 23 inside the top surface. Vibrating membrane 24
It has. The vibration film 24 is fixed to the fixed electrode 26 via the gap spacer 25 and the capacitor gap 32.
The printed circuit board 29 and a concave insulator 27 that accommodates the FET 28 are further disposed below and fixed by the caulking portion 22 b of the metal case 22.

The input lead 28a of the FET 28 is connected to the fixed electrode 26, and the output lead 28b passes through the insulator 7 and the printed circuit board 29 and is connected to the soldered portion 9a on the bottom. On the other hand, the vibration film 24 is electrically connected to the metal case 22 by the film ring 23.

Now, when sound is input from the sound hole 22a, the vibration film 24 vibrates, which changes the capacitance between the vibration film 24 and the fixed electrode 26. By detecting this, a sound signal is obtained. Can be.

[0005]

However, the above-described conventional electret condenser microphone has the following problems.

(1) Although electret condenser microphones are required to be small, light and thin, conventional ones have a large number of components and cannot reduce the thickness of the swaging portion 22b and the soldered portion 29a. Also, because of the existence of the insulator 27 and the printed circuit board 29, the whole could not be reduced in size, weight and thickness. In particular, the vibrating membrane 2
4. Since the fixed electrode 26 and the FET 28 are stacked in this order, the whole could not be thinned.

(2) Since the metal case 22 is fixed by caulking, the airtightness is insufficient.

[0008]

Accordingly, in the present invention, a fixed electrode and a vibrating membrane are arranged at a fixed interval, and an audio signal given to the vibrating membrane due to a change in capacitance between the two is detected. In the electret condenser microphone, the fixed electrode and the diaphragm and the semiconductor element are housed in parallel in a box-shaped case made of an insulating material.

In other words, the fixed electrode, the vibrating film, and the semiconductor element are housed in parallel, thereby reducing the overall thickness and thickness.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described with reference to the drawings.

The electret condenser microphone shown in FIG. 1A is provided with two independent concave portions 9a and 9a 'in a box-shaped case 9 made of ceramics, glass, resin or an insulator obtained by combining these, and one concave portion 9a is provided. Is provided with a vibrating membrane 4 and a fixed electrode 6, and the other concave portion 9a 'is
A semiconductor element 8 such as T or IC is accommodated and covered with a plate-like lid 2.

The cover 2 is a metal plate having a sound hole 2a in the center. A vibrating film 4 made of an electret material having a metal layer is provided on the step 9b of the recess 9a, and a capacitor is provided on the bottom of the recess 9a. A fixed electrode 6 is provided with a gap therebetween. A semiconductor element 8 such as an FET or an IC is housed in the other concave portion 9a ', and an amplifier circuit and the like are formed in the semiconductor element 8.

Further, the case 9 has a conductive path on the surface and / or inside by printing a conductive paste on the surface, filling the through hole, and laminating a green sheet provided with the conductive paste. . First, lid 2
The conductive path 7a is connected to the electrode take-out portion 10a on the bottom surface through the outer wall of the box-shaped case 9, and the conductive path 7a also functions to prevent RF wraparound and static electricity.

The fixed electrode 6 is electrically connected to the conductive path 7b.
The conductive path 7e connected to the input terminal 8a of the semiconductor element 8 and further connected to the output terminal 8b is led out to the conductive path 7c outside the box-shaped case 9 and connected to the other electrode take-out portion 10b. In addition, the input terminal 8a of the semiconductor element 8,
The output terminal 8b is wire-bonded to the conductive paths 7b and 7e provided on the step 9b 'of the recess 9a'.

As shown in FIG. 1B, the upper end surface 9c of the box-shaped case 9 is metallized and bonded to the lid 2 with solder, brazing, conductive adhesive or the like. Is connected to the conductive path 7a. Further, the vibration film 4 is connected to the electrode take-out portion 10a through the conductive paths 7e and 7a.

The conductive paths 7a and 7c can be formed inside through holes. Further, the electrode take-out part 10a is grounded, and the other electrode take-out part 10b also serves as a power supply of the semiconductor element 8 and an output terminal.

When a sound is input from the sound hole 2a of the cover 2, the vibrating membrane 4 vibrates, and the capacitance between the vibrating membrane 4 and the fixed electrode 6 changes. An audio signal can be obtained.

In the electret condenser microphone of the present invention, by using the box-shaped case 9 made of an insulator, the insulator 27 and the printed circuit board 29 can be eliminated as compared with the conventional structure shown in FIG. It is possible to reduce the number of parts and reduce the size. Moreover, by housing the vibrating film 4 and the fixed electrode and the semiconductor element 8 in parallel, the thickness can be reduced and the thickness can be reduced. Further, in this embodiment, the semiconductor element 8 is housed in the independent concave portion 9a ', so that hermetic sealing can be achieved.

The electret condenser microphone of the present invention has a box-shaped case 9 as shown in FIG.
Since the electrode extraction portions 10a and 10b are provided on both sides of the bottom surface of the substrate, the electrode extraction structure by surface mounting can be facilitated.

Further, the box-shaped case 9 has a rectangular shape when viewed in plan. Therefore, when the semiconductor element 8 having a square shape is similarly stored, there is no waste, and the whole can be further reduced in size. Moreover, when the microphone is surface-mounted, it is easy to handle and position easily because of its square shape.

Further, as an insulator forming the box-shaped case 9,
In particular, the use of ceramics containing alumina, zirconia, mullite, silicon carbide, silicon nitride, aluminum nitride, or the like as a main component makes it possible to particularly improve vibration damping characteristics. In other words, these ceramics have a greater effect of attenuating vibrations than metal materials and the like, so even when used for applications such as mobile phones, external vibrations can be hardly transmitted to the inside, and the performance of the microphone can be reduced. Can be improved.

Furthermore, in the present invention, since the box-shaped case 9 is used, the lid 2 may be a flat plate, which facilitates the processing. Therefore, for example, a structure having a mesh-shaped sound hole 2a may be employed. Normally, it is necessary to cover with a face cloth (not shown) or the like in order to prevent foreign matter from entering through the sound hole 2a. However, by using the mesh-shaped sound hole 2a, it is possible to omit the face cloth. it can.

Next, another embodiment of the present invention will be described.
In the embodiment shown in FIG. 2, the fixed electrode 6 is provided in one recess 9a.
And the vibration film 4 and the semiconductor element 8 are housed in parallel.

That is, the fixed electrode 6 is provided on the bottom surface of the concave portion 9 a of the box-shaped case 9, and the vibration film 4 is provided thereover via the gap spacer 5 with a capacitor gap therebetween. This vibrating membrane is wire-bonded to a conductive path 9e provided in the step 9b, and is connected to the electrode take-out part 10a through the conductive path 7a. The lid 2 is also connected to the electrode take-out part 10a through the conductive path 7a. On the other hand, a semiconductor element 8 is mounted on the bottom surface of the recess 9a in parallel with the fixed electrode, and the input terminal 8a of the semiconductor element 8 is connected to the fixed electrode 6 and the output terminal 8
b is wire-bonded to the conductive path 7e of the step 9b, and the conductive path 7e is connected to the other electrode lead-out part 10b through the conductive path 7c.

In this embodiment, since only one concave portion 9a is required and the shape can be made simple, the manufacturing is easy.

FIG. 3 shows still another embodiment. In this embodiment, both the fixed electrode 6 and the lid 2 are used.

That is, the vibration film 4 is provided below the lid 2 covering the upper surface of the box-shaped case 9 via the gap spacer 5, and the vibration film 4 is provided with the conductive path 7 b, the semiconductor element 8, Electrode take-out part 10b through conductive paths 7e and 7c
Connected to The lid 2 also serving as a fixed electrode is connected to the other electrode extraction portion 10a through the conductive path 7a.

FIG. 4 shows still another embodiment. In this embodiment, the fixed electrode 6 and the lid 2 are similar to those shown in FIG.
And the box-shaped case 9 has two recesses 9a and 9
b is formed.

That is, the vibrating film 4 is provided in the step 9b of the one concave portion 9a of the box-shaped case 9, and the vibrating film 4 is connected to the semiconductor element 8 accommodated in the other concave portion 9a 'through the conductive path 7b.
It is connected to the electrode take-out part 10b through the conductive paths 7e and 7c. The lid 2 also serving as a fixed electrode is provided with a conductive path 7.
a to the other electrode take-out part 10a.

Although the conventional electret condenser microphone requires a thickness of about 2 mm, the electret condenser microphone of the present invention as described above can have a thickness of 1 mm or less, preferably 0.5 mm or less.

Further, when manufacturing the electret condenser microphone of the present invention, mass production can be performed by using a multi-cavity method.

[0032]

According to the present invention, an electret condenser microphone in which a fixed electrode and a vibrating membrane are arranged at regular intervals and an audio signal given to the vibrating membrane due to a change in capacitance between them is detected. In the above, by housing the fixed electrode and the vibrating membrane and the semiconductor element in parallel in a box-shaped case made of an insulating material, the number of parts can be reduced and the size can be reduced, and the thickness can be particularly reduced. It can be used for various purposes such as ultra-thin LCD monitor, card remote control, voice memory, PC voice input, etc.

[Brief description of the drawings]

FIG. 1 shows an electret condenser microphone of the present invention, in which (a) is a longitudinal sectional view, (b) is a plan view,
(C) is a bottom view.

FIG. 2 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 3 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 4 is a longitudinal sectional view showing another embodiment of the present invention.

FIG. 5 is a longitudinal sectional view showing a conventional electret condenser microphone.

[Explanation of symbols]

 2: lid 2a: sound hole 3: membrane ring 4: vibrating membrane 5: gap spacer 6: fixed electrode 7a to 7e: conductive path 8: semiconductor element 9: box-shaped case 9a, 9a ': concave section 9b, 9b': Step 9c: Upper end surface 10a, 10b: Electrode take-out part

Claims (3)

[Claims] 1. A fixed electrode and a vibrating membrane are arranged at regular intervals,
In an electret condenser microphone configured to detect an audio signal given to the diaphragm due to a change in capacitance between the two, the fixed electrode, the diaphragm, the amplifier circuit, and the like are placed in a box-shaped case made of an insulating material. An electret condenser microphone wherein the formed semiconductor elements are housed in parallel. 2. The electret capacitor according to claim 1, wherein a plurality of independent recesses are formed in the box-shaped case, and the fixed electrode, the vibrating film, and the semiconductor element are housed in separate recesses. Microphone. 3. The electret condenser microphone according to claim 1, wherein the fixed electrode, the vibrating membrane, and the semiconductor element are housed in parallel in one recess formed in the box-shaped case.