[Claim(s)][Claim 1]A waterproof structure of a micro-phone for preventing liquids such as perspiration from reaching the sound port of the microphone body via the sound guide portion, char-acterized in that a porous member attached to the inner wall of the sound guide portion. e areas at which the outer circumference of the porous member and the inner wall of the sound guide portion make contact or form a gap are lled with ller material.[Claim 2]The waterproof structure of the microphone according to Claim 1, wherein the filler material is a UV-curing resin or epoxy-curing resin.[Detailed description of the invention][Technical eld]The present invention relates to a waterproof structure of a micro-phone that prevents liquids such as perspiration from reaching the sound port of the microphone body via the sound guide portion.[Background of the invention]Ultra-compact microphones used for hearing aids and the like com-prise a microphone body, which converts acoustic signals into elec-trical signals, and a sound guide portion for guiding acoustic signals into the microphone body. Conventionally, in such ultra-com-pact microphones, a porous mem-ber made by electroforming or by etching is attached to the pipe-shaped sound guide portion by press-tting or by other means to prevent perspiration or earwax from entering the sound port of the microphone body and to achieve an acoustic impedance that does not significantly affect the frequency response of the acoustic signal. In addition, a drip-proof microphone is also known, in which a drip-proof body having a sound path made of a material whose critical surface ten-sion is lower than that of water is attached to the sound guide portion (see, for example, Patent Literature 1).[Patent Literature 1]JP H 1-29894Y[Disclosure of the invention][Problem to be solved by the invention]While a porous member attached to the sound guide portion by press-fitting or by other means is eective in preventing the intrusion of earwax, a gap is formed between the porous member and the inner wall of the sound guide portion due to deformation of the porous mem-ber by press-tting. Liquids such as perspiration that permeate along the inner wall of the sound guide portion from the outside can pass through said gap to readily reach the sound port of the microphone body, thereby degrading microphone performance. In addition, even if a drip-proof body as described in Patent Literature 1 is attached to the sound guide portion, it has proven to be insufficient to keep liquids such as perspiration from entering the sound port of the microphone body.e purpose of this invention is to provide a waterproof structure of a microphone as a solution to the abovementioned problem that can effectively prevent liquids such as perspiration from traveling along the inner wall of the sound guide portion and reaching the sound port of the microphone.[Means for solving the problem]e invention according to Claim 1 is a waterproof structure of a micro-phone that prevents liquids such as perspiration from reaching the sound port of the microphone body by traveling along the inner wall of the sound guide portion, wherein the areas where the outer circumfer-ence of the porous member makes contact with or forms a gap with the inner wall of the said sound guide portion are filled with a filler material.e invention according to Claim 2 is the waterproof structure of the microphone according to Claim 1, wherein the filler material is a UV-curing resin or an epoxy cur-able resin.[Eect of the invention]As explained above, according to the invention according to Claim 1, it is possible to eectively prevent liquids such as perspiration that permeate along the inner wall of the sound guide portion from reaching the sound port of the microphone.e invention according to Claim 2 improves the workability of lling the areas where the outer circumfer-ence of the porous member and the inner wall of the sound guide por-tion make contact or form a gap with the ller material.[Industrial applicability]The present invention effectively prevents liquids such as perspira-tion that permeate along the inner wall of the sound guide portion from reaching the sound port of the microphone, thereby reducing the risk of perspiration permeating into the interior of the microphone via the sound port and causing perfor-mance degradation. In addition, the reliability and durability of hearing aids to which the waterproof struc-ture of the microphone according to the present invention is applied will be improved, and the usability of hearing aids will be enhanced, con-tributing to increased demand for hearing aids.[Claim(s), Background of the invention, Eect of the invention, etc.][Brief description of the drawings]1 ________Microphone body2 ________Sound guide portion2a _______Inner wall3 ________Case4 ________Diaphragm5 ________Electrode6 ________Impedance converter7 ________Terminal8 ________Sound port10 _______Porous thin plate (porous member)10a ______Outer circumference11 _______Pores12 _______Filler material[Fig. 1] Cross-sectional view of a microphone to which the waterproof structure of the microphone of the present invention is applied[Fig. 2] Plan view of the porous memberAn embodiment of the present invention is described based on accompanying drawings below. Here, Figure 1 is a cross-sectional view of a microphone to which the waterproof structure of the microphone according to the invention is applied, and Figure 2 is a plan view of a porous member.As shown in Figure 1, the microphone to which the water-proof structure of the microphone according to the pres-ent invention is applied consists of a microphone body 1 that converts acoustic signals into electrical signals and a sound guide portion 2 for guiding acoustic signals to the microphone body 1.e microphone body 1 contains, inside case 3, a dia-phragm 4 that receives and displaces the sound pressure of the acoustic signal, an electrode 5 that captures the dis-placement of the diaphragm 4 and converts it into an elec-trical signal, and an impedance converter 6 into which the electrical signal converted by the electrode 5 is input. e surface of electrode 5 facing the diaphragm 4 is electret-ized. e output signal of the impedance converter 6 is input to the amplication circuit (not shown) of the hear-ing aid through terminal 7 on the outer surface of case 3.e case 3 also has a sound port 8 for taking the acoustic signal guided by the sound guide portion 2 into the inte-rior of the microphone body 1. e acoustic signals guid-ed to the sound port 8 reach the diaphragm 4 on the side not facing the electrode 5.e sound guide portion 2 is formed in the shape of a pipe, and a metal porous thin plate 10 made by electro-forming or by etching is press-tted to the inner wall 2a of the sound guide portion 2 to prevent the permeation of perspiration and earwax, as shown in Figure 2.e dimensions of the pores 11 in the porous thin plate 10 are set to prevent the permeation of liquids such as perspi-ration to pass through while achieving an acoustic imped-ance that does not significantly affect the frequency response of the acoustic signal input from the outside. For example, the punching metal for porous thin plate 10 has numerous pores with a diameter of 50 μm.Instead of the metal porous thin plate 10, a porous thin plate made of resin, or a mesh member made of resin ber or glass ber may be used. As with the porous thin plate 10, the pore size of the resin-made porous thin sheet or the aperture size of the mesh member is also set so that liq-uids such as perspiration cannot pass through while achieving acoustic impedance that does not signicantly aect the frequency response of the acoustic signal input from the outside.In addition, the areas where the outer circumference 10a of the porous thin plate 10 makes contact or forms a gap with the inner wall 2a of the sound guide portion 2 are completely lled with a ller material 12. UV-curing res-in is used as the ller material 12. One-component (heat cured) or two-component (room temperature cured) epoxy resin can also be used.e ller material 12 will close all gaps formed by the out-er circumference 10a of the porous thin plate 10 and the inner wall 2a of the sound guide portion 2.To fill the gaps, the UV-curing resin is placed into a syringe-like device, and the UV-curing resin is dripped into the area where the outer circumference 10a of the porous thin plate 10 and the inner wall 2a of the sound guide portion 2 make contact or form a gap, and the res-in is allowed to seep into all areas by capillary action. e seeped UV-curing resin can then be cured by irradiating it with UV light. By using a UV-curing resin that hardens by irradiating the ller material 12 with UV light, the e-ciency of the lling process is improved.As another method of lling the UV-curing resin, the UV-curing resin may be applied to the inner wall 2a of the sound guide portion 2 before press-tting the porous thin plate 10 into the sound guide portion 2 and then UV-curing resin may be cured by irradiating it with UV light aerward.e eect of the waterproof structure of the microphone constructed as described above is described below. Perspiration that permeates along the inner wall 2a of the sound guide portion 2 from the outside, upon reaching the porous thin plate 10, is guided to the center of the porous thin plate 10 because the ller material 12 such as UV-curing resin will prevent it from traveling further along the inner wall 2a of the sound guide portion 2.In order for the perspiration guided to the center of the porous thin plate 10 to reach the sound port 8, it must pass through the pores 11 in the porous thin plate 10. But it is not easy for perspiration to pass through the pores 11, so it will take time to pass through the pores 11.Since perspiration will then pass slowly through the pores 11, time for the perspiration to evaporate is secured.Therefore, the possibility of perspiration reaching the sound port 8 of the microphone is lowered, and the pos-sibility of perspiration entering the interior through the sound port 8 of the microphone and causing performance degradation can be reduced.13
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