| 摘要 |
<p>PURPOSE:To reduce the noise level produced by external oscillation independently of the number of frequencies, by connecting the sound reception microphone unit and the oscillation noise reduction unit so that the outputs are in opposite phase each other. CONSTITUTION:In the case 5 of cylindrical shape constituting the microphone main body, the sound reception microphone unit 7 supported elastically with the oscillation-proof member 6 and the oscillation noise reduction microphone unit 8 to reduce the nois produced with external mechanical oscillation are contained up and down. The units 7 and 8 are connected in series and so that the outputs are in opposite phase each other, and when mechanical external oscillation is exerted to the microphone, the oscillation plates of the units 7 and 8 are going to move toward the same direction, thereby causing an electromotiveforce at each voice coil instantly, but they are cancelled due to opposite phase connection. Since the unit 8 is contained in a closed space, it is not subjected to the effect of external sound pressure.</p> |
