Patent Translate Powered by EPO and Google Notice This translation is machine-generated. It cannot be guaranteed that it is intelligible, accurate, complete, reliable or fit for specific purposes. Critical decisions, such as commercially relevant or financial decisions, should not be based on machine-translation output. DESCRIPTION JPS61247200 [0001] FIELD OF THE INVENTION This invention relates to electret condenser microphones. Prior Art FIG. 3 is a cross-sectional view of a conventional electret condenser microphone. In FIG. 3, 1 is a cloth, 2 is a cylindrical metal case having a sound hole 2a on the top surface, 3 is a film formed by uniformly stretching a vibrating film 4 made of an electret material having a metal surface by metal deposition or the like. Reference numeral 5 denotes a gap spacer, 6 denotes a fixed electrode, 6a denotes a damping hole, 7 denotes an insulator, 8 denotes an FET, 8a denotes an input lead, 8b denotes an output lead, 9 denotes a printed circuit board, and 10 denotes a back air chamber. The output lead 8b is fixed to the printed circuit board 9 by the soldered portion 9a. In the present description, a wheel electret type using an electret material for the vibrating membrane 4 is taken as an example, but the same applies to a pack electret type where an electret material is provided on the fixed electrode 6 side. The fixed electrode 6, the insulator 7, the FET 8, and the printed circuit board 9 can be considered as one amplifier block, and the above-described components are fixed to the metal case 2 by the caulking portion 2b after being inserted. The input lead 8a of the FET 8 is electrically connected to the fixed electrode 6 by spot welding or contact. In the latter case, the fixed electrode 6 is fixed to the insulator 7 by press fitting or the like. In the electret condenser microphone configured as described above, the graphic 1 is for dustproofing or damping of the high-frequency characteristic, and the vibrating membrane 4 is configured on the front side (sound introducing side) Therefore, it is necessary to make the sound hole 2a of the metal case 2 smaller to some extent (about .phi.1 fflII or less) in order to eliminate the drawing cloth 1 and it is necessary to provide a plurality of them in terms of acoustic characteristics. It is easy to cause damage such as a thousand and the like, and maintenance is very difficult. An object of the present invention is to provide an electret condenser microphone having a structure in which the sound holes on the top surface of the metal case are practically unchanged and dust and the like are practically difficult to enter 04-05-2019 1 without changing the conventional one It is. MEANS FOR SOLVING THE PROBLEMS In order to achieve the above object, according to the present invention, a fixed electrode is a front side (sound introduction (III), and a vibrating membrane (movable electrode) having a metal surface stretched over a membrane ring). It is configured to be on the back side. Therefore, according to the present invention, since the braking hole of the fixed electrode is also used as the sound wave introducing hole, the cloth can be eliminated without deteriorating the dustproof effect and the high frequency characteristic, and the number of parts can be reduced. Embodiment The configuration of an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a cross-sectional view showing an embodiment of the present invention, and the same parts as FIG. 3 are indicated by the same reference numerals. In FIG. 1, the fixed electrode 6 is the front surface m <the sound wave introduction side), and the vibrating membrane 4 (movable electrode) is the back surface side. The damping hole 6a of the fixed electrode 6 is generally a small hole of about φ1 ma + or less, and can be said to be an optimum size for foreign substances such as dust and in terms of acoustic characteristics. Therefore, it is not necessary to make the sound hole 2a of the metal case 2 smaller even if the drawing cloth 1 is eliminated. This may be the same level as in the prior art, and the fixed electrode 6 plays a sufficient role as protection of the diaphragm 4. Although the FET 8 of this embodiment uses the dual side type in which the input / output leads 8a and 8b are led out from both sides, as shown in FIG. 3, any single side type may be used. Absent. FIG. 2 shows another embodiment of the present invention, and contrary to FIG. 1, the sound hole 2a side of the top surface of the metal case 2 is the printed board 9 side which is the output terminal, and the caulking portion is on the fixed electrode 6 side. It is configured to be fixed by 2b. If caulking is performed on the front side as in FIG. 2 in the prior art of FIG. 3, the diaphragm 4 will be distorted due to the caulking portion on the membrane ring 3, but in the case of FIG. I do not have to worry about that. In the embodiment of the present invention, although not particularly shown, it is conceivable to adopt the following method regarding the ventilation (near leak) to the outside of the back air chamber 10. For example, the insulator 7 is provided with one or a plurality of notches and the like, and the back air chamber 10 is ventilated between the metal case 2 and the inside 4 articles such as the insulator 7 etc. In this method, a groove or the like is provided in the fixed electrode 6 or the gap spacer 5 and acoustically ventilates with the outside air from the front side. According to such a method, it is possible not only to realize a reliable near leak but also to control the frequency characteristics such as lowering the frequency characteristics in the low band by appropriately setting the acoustic constant. Effects of the Invention As described above, according to the present invention, the fixed electrode is the front side (the sound wave introduction side) and the vibrating membrane (the movable electrode) is the back side. There is no need to make the sound hole on the top surface of the metal case particularly small, because it is possible to prevent protection and foreign matter from entering. In addition, since the fixed electrode is on the front side, the back air chamber can be made larger by the inner part of the membrane ring, so the 04-05-2019 2 sensitivity can be increased if the overall height of the electret condenser microphone is the same as conventional, and thinner if conventional. It also has the advantage of being configurable. [0002] Brief description of the drawings [0003] FIG. 1 is a sectional view showing an electret condenser microphone according to an embodiment of the present invention, FIG. 2 is a sectional view showing another embodiment of the present invention, and FIG. 3 is a sectional view of a conventional electret condenser microphone . 2 · · · · · · · · Metal case, · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · fixed electrode, 6a · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · · FET FET. Name of agent Attorney Nakao Toshio and others 1 person Figure 1! 2 Figure 04-05-2019 3
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