JP3377957B2 - 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.

[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 face cloth 21 is provided on the top surface of a cylindrical metal case 22 having a sound hole 22a in the central portion, 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
Is equipped with. The vibrating film 24 includes a fixed electrode 26 and a capacitor spacer 32 via a gap spacer 25.
The concave insulator 27 accommodating the FET 28 and the printed circuit board 29 are disposed further below, and are fixed by the caulking portion 22b 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 penetrates the insulator 7 and the printed board 29 and is connected to the soldered portion 9a on the bottom surface. On the other hand, the vibrating membrane 24 is electrically connected to the metal case 22 by the membrane ring 23.

When a voice is input from the sound hole 22a, the vibrating membrane 24 vibrates, and the capacitance between the vibrating membrane 24 and the fixed electrode 26 changes. Therefore, a voice signal can be obtained by detecting this. You can

[0005]

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

(1) The electret condenser microphone is required to be small and lightweight, but in the conventional one, the number of parts is large, and the thickness of the caulking portion 22b and the soldered portion 29a cannot be reduced, Further, due to the presence of the insulator 27 and the printed circuit board 29, it was not possible to reduce the size and weight of the whole.

(2) In the conventional electret condenser microphone, the fixed electrode 26 to the printed circuit board 29 are assembled as an amplifier block, the parts are placed in the metal case 22 which is turned upside down, and the parts are caulked at the end. , Mass production was difficult, and productivity was low.

(3) Since the metal case 22 is fixed by caulking, the fixing of each component is not reliable, which causes a failure and a decrease in yield.

(4) In the case of surface mounting, since the soldered portion 29a, which is a terminal lead-out portion, is located at the center, mounting is difficult and there is a high risk of short-circuiting.

(5) When each component is miniaturized, the component that is most restricted by miniaturization is the FET 28 or the IC, which have a rectangular shape. However, the conventional metal case 2
Since 2 is a cylindrical shape, storing the square FET 28 was a big waste. Moreover, since the metal case 22 is a cylindrical body, it is difficult to handle at the time of mounting or the like, positioning is difficult, and even if the sound hole 22a is made to have a complicated shape, it is difficult to process.

(6) The metal case 22 easily transmits vibrations in the surroundings, adversely affects the vibrating film 24, and causes deterioration of characteristics.

(7) Since the printed board 29 is provided with the output lead 28b, the soldered portion 29b is required to maintain the airtightness of this portion.

[0013]

Therefore, in the present invention, the fixed electrode and the vibrating membrane are arranged at a constant interval, and the voice signal given to the vibrating membrane is detected by the change of the electrostatic capacitance between them. The electret condenser microphone is characterized in that the fixed electrode, the vibrating membrane, and the driving semiconductor element are housed in a box-shaped case made of an insulating material.

That is, by accommodating the respective parts in the box-shaped case, it is possible to reduce the number of parts by omitting the insulator and the printed board as in the conventional example. Moreover, since it suffices to place each component on the box-shaped case and cover it with the lid, mass production is easy and each component can be firmly fixed.

Further, according to the present invention, the box-shaped case is provided with the conductive paths on the wall surface and / or the inside thereof, and the bottom surface is provided with the electrode lead-out portions. It is possible to do surface mounting easily.

Further, according to the present invention, a step portion is provided on the inner wall of the box-shaped case, and the vibrating membrane or the fixed electrode is placed on the step portion, so that the number of parts can be reduced and each part can be firmly fixed. I chose

Further, according to the present invention, by making the box-shaped case rectangular, it is possible to match the shapes of the FETs and ICs to be housed and to facilitate handling and positioning.

Further, according to the present invention, the number of parts is further reduced by using the fixed electrode also as a lid for covering the box-shaped case.

[0019]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below with reference to the drawings.

The electret condenser microphone shown in FIG. 1 (a) is provided with a step 9b on the inner wall of the recess 9a of the box-shaped case 9 made of ceramics, glass, resin, or an insulating material composed of these, and the recess 9a is provided in the recess 9a. The components are housed and covered with a plate-shaped lid 2.

The lid 2 is a metal plate having a sound hole 2a in the center, and a vibrating film 4 made of an electret material having a metal layer formed below it via a film ring 3 and a gap spacer 5 provided. A fixed electrode 6 is provided with a capacitor gap interposed therebetween. The fixed electrode 6 is placed on the stepped portion 9b, and is joined to the metallized portion on the stepped portion 9b with solder, solder, conductive adhesive, etc.
A semiconductor element 8 such as an ET or an IC is housed, and an amplifier circuit or the like is formed in this semiconductor element 8.

Further, the box-shaped case 9 is formed by printing a conductive paste on the surface, filling through holes, or laminating green sheets provided with the conductive paste.
Conductive paths are provided on the surface and / or inside. First, the conductive path 7a connected to the lid 2 passes through the outer wall of the box-shaped case 9 and is connected to the electrode lead-out portion 10a on the bottom surface. Further, the conductive path 7b provided on the step portion 9b on which the fixed electrode 6 is mounted is connected to the input terminal 8a of the semiconductor element 8, and the conductive path 7c connected to the output terminal 8b is led out to the outside of the box-shaped case 9. It is connected to the other electrode extraction portion 10b.

Further, as shown in FIG. 1B, the upper end surface 9c of the box-shaped case 9 is metallized and adhered to the lid 2 with solder, solder, conductive adhesive or the like. Therefore, the vibrating membrane 4 is connected to the electrode lead-out portion 10a through the membrane ring 3, the lid 2, and the conductive path 7a. On the other hand, the fixed electrode 6 is
It is connected to the other electrode extraction portion 10b through the conductive path 7b, the semiconductor element 8 and the conductive path 7c.

The conductive paths 7a and 7c may be formed inside via through holes. The electrode lead-out portion 10a is grounded, and the other electrode lead-out portion 10b also serves as a power source and an output terminal of the semiconductor element 8.

Now, when a sound is input from the sound hole 2a of the lid body 2, the vibrating membrane 4 vibrates, which changes the electrostatic capacitance between the vibrating membrane 4 and the fixed electrode 6. Therefore, by detecting this, An audio signal can be obtained.

In such an 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. Therefore, the number of parts can be reduced and the size can be reduced.

Further, in the electret condenser microphone of the present invention, it suffices to store and fix each component in the recess 9a of the box-shaped case 9 in order from the bottom, and finally cover with the lid 2. The manufacturing process is simplified and mass production can be easily performed. Moreover, since the box-shaped case 9 is provided with the stepped portion 9b, the fixed electrode 6 is joined to the stepped portion 9b, and the other components are also securely joined to the case, it is possible to firmly fix the case. Become.

The electret condenser microphone of the present invention has a box-shaped case 9 as shown in FIG. 1 (c).
Since the electrode lead-out portions 10a and 10b are provided on both sides of the bottom surface of the, the electrode lead-out structure by surface mounting can be facilitated.

Further, the box-shaped case 9 has a rectangular shape when viewed in plan, and has a rectangular shape. Therefore, since there is no waste when the rectangular semiconductor element 8 is housed in the same manner, the overall size can be further reduced. Moreover, when the microphone is mounted on the surface, the square shape facilitates handling and positioning.

As an insulator forming the box-shaped case 9,
Particularly, when a ceramic containing alumina, zirconia, mullite, silicon carbide, silicon nitride, aluminum nitride, etc. as a main component is used, vibration damping characteristics can be particularly improved. That is, since these ceramics have a greater effect of damping vibrations than metal materials and the like, even when used for applications such as mobile phones, it is possible to make it difficult to transmit external vibrations to the inside and improve the performance of the microphone. Can be improved.

Furthermore, since the box-shaped case 9 is used in the present invention, the lid body 2 may be in the form of a flat plate, which facilitates the processing. Therefore, for example, as shown in FIG. 1D, the structure may be provided with a mesh-shaped sound hole 2a. 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, but by using the mesh-like sound hole 2a in this way, the face cloth can be omitted. You can

Further, as another embodiment, as shown in FIG. 1 (e), two step portions 9b are formed in the box-shaped case 9,
The vibrating membrane 4 and the fixed electrode 6 may be placed on each of them. By doing so, the film ring 3 and the gap spacer 5 can be further eliminated.

Further, another embodiment of the present invention will be described.

The electret condenser microphone shown in FIG. 2 is an example in which the fixed electrode 6 and the lid 2 are used in common. That is, the vibrating film 4 is provided below the lid body 2 that covers the upper end surface of the box-shaped case 9 via the gap spacer 5, and the vibrating film 4 is fixed to the step portion 9b. Then, the lid 2 has the conductive path 7
The vibration film 4 is connected to the electrode lead-out portion 10a through a, and the vibrating film 4 is connected to the electrode lead-out portion 10b through the conductive path 7b, the semiconductor element 8, and the conductive path 7c.

In this embodiment, the lid 2 also serves as the fixed electrode 6, and the change in the capacitance between the lid 2 (fixed electrode 6) and the vibrating membrane 4 is detected. for that reason,
The number of parts can be further reduced as compared with that of FIG. 1, and the size can be reduced.

Next, the mounting structure of the semiconductor element 8 will be described. In the example of FIGS. 1 and 2, the input lead 8a and the output lead 8b of the semiconductor element 8 are placed on the conductive paths 7b and 7c, respectively, and joined by solder, solder, conductive adhesive or the like.

As another embodiment, as shown in FIG. 3A, two step portions 9a, 9 are provided inside the box-shaped case 9.
By providing a ′, the input lead 8a and the output lead 8b of the semiconductor element 8 can be placed on this step 9a ′ and joined to the conductive path. Alternatively, as shown in FIGS. 3B and 3C, it is also possible to use a semiconductor element 8 having no lead and connect it to the conductive path by wire bonding 11.

Further, according to the present invention, the box-shaped case 9 made of an insulator is used.
It is also possible to easily mount other electronic parts because the electronic parts are used. For example, as shown in FIG. 4A, a step is formed below the semiconductor element 8 and another electronic component 12 is provided therein, or a recess is formed on the bottom side of the blade case 9. Other electronic components 12 may be included in this.

Further, when the electret condenser microphone of the present invention is manufactured, it is possible to mass-produce it by using a method of taking a large number of pieces. For example, as shown in FIG. 5, a substrate 13 made of an insulator such as ceramics or glass is provided with a large number of recesses 9a formed therein, and each box-shaped product is divided by dividing along a dividing line 14. Case 9 can be obtained. Alternatively, it is also possible to store each part in each recess 9a before the division to manufacture the electret condenser microphone, and then divide along the dividing line 14.

The division along the division line 14 is performed by dividing with a dividing groove formed on the substrate 13 in advance, or by using a diamond cutter, a laser beam or the like.
If such a method is used, a large number of electret condenser microphones can be collectively manufactured.

[0041]

According to the present invention, the electret condenser microphone in which the fixed electrode and the vibrating membrane are arranged at a constant interval and the voice signal given to the vibrating membrane is detected by the change of the electrostatic capacitance between them. In the above, since the fixed electrode, the vibrating film, and the driving semiconductor element are housed in a box-shaped case made of an insulating material, the number of parts can be reduced and the size can be reduced, and mass production is easy. , Each part can be firmly fixed.

In addition, since the conductive path is provided on the wall surface and / or inside of the box-shaped case and the electrode lead-out portions are provided on the bottom surface, the electrode lead-out portions can be provided on both sides of the bottom surface with a simple structure, It can be easily implemented.

Furthermore, by making the box-shaped case square, it is possible to make it conform to the shape of the semiconductor element to be housed and to facilitate handling and positioning.

[Brief description of drawings]

1 shows an electret condenser microphone of the present invention, (a) is a vertical sectional view, (b) is a plan view, FIG.
(C) is a bottom view, (d) is a perspective view showing another embodiment of the lid, and (e) is a sectional view showing another embodiment.

FIG. 2 is a vertical cross-sectional view showing another embodiment of the present invention.

3A to 3C are cross-sectional views showing a mounting structure of a semiconductor element in the electret condenser microphone of the present invention.

4A and 4B are cross-sectional views showing an example in which another electronic component is mounted in the electret condenser microphone of the present invention.

FIG. 5 is a diagram for explaining a method of manufacturing a large number of electret condenser microphones of the present invention.

FIG. 6 is a longitudinal sectional view showing a conventional electret condenser microphone.

[Explanation of symbols]

2: Lid 2a: sound hole 3: Membrane ring 4: Vibration film 5: Gap spacer 6: Fixed electrode 7a, 7b, 7c: Conductive path 8: Semiconductor element 9: Box type case 9a: concave portion 9b: step 9c: Top surface 10a, 10b: Electrode take-out part

Claims (4)

(57) [Claims] 1. A fixed electrode and a vibrating membrane are arranged at a constant interval,
In an electret condenser microphone designed to detect a voice signal applied to a vibrating membrane by a change in capacitance between the two, the fixed electrode, the vibrating membrane, and the semiconductor element are housed in a box-shaped case made of an insulating material. ,the above
The bottom surface of the box-shaped case is provided with a conductive path on the wall surface and / or inside.
An electret condenser microphone characterized in that the electrode lead-out portion is provided in the . 2. A fixed electrode and a vibrating membrane are arranged at a constant interval,
The sound given to the vibrating membrane due to the change in capacitance between the two.
Electret condenser designed to detect voice signals
In a microphone, in a box-shaped case made of insulating material
The fixed electrode, the vibrating membrane, and the semiconductor element are housed in the
A vibrating membrane or fixed electrode is attached to the step provided on the inner wall of the box-shaped case.
An electret condenser microphone characterized by being placed . 3. A process according to claim 1 or 2 electret condenser microphone, wherein the said box-type case is square. 4. electret condenser microphone according to any one of claims 1 to 3 in which the fixed electrode is characterized in that it also serves as a lid for covering the box-type case.