Patent ID: 8520880

Claim:
A boundary microphone comprising: a base plate having a flat base surface and a recess, the base plate being flat and made of a metallic material; a cover having a number of sound wave through holes, the cover closing an upper surface of the base plate; a circuit board having a sound signal output part provided on an underside thereof to face the recess, a shield pattern formed on an upper surface thereof for electrostatically shielding inside of the recess of the base plate, and an opening in a part thereof, the circuit board being mounted on the base plate so as to cover the recess; a microphone unit having a lead wire and an output terminal electrically connected to the sound signal output part through the lead wire, the microphone unit being mounted in the opening; and a metallic holder comprising a cylindrical section into which the microphone unit is fitted, and a D-cut section having a semi-cylindrical part extending from the cylindrical section, a bottom plate to cover an end of the semi-cylindrical part and a lower opening, the lower opening being covered by the circuit board to form a space for shielding the lead wire therein; the D-cut section extending from the cylindrical section in a direction parallel to a board surface of the circuit board, wherein the space is defined by the D-cut section, the circuit board and the microphone unit, and the lead wire is located in the space, and wherein only the cylindrical section of the holder is fitted in the opening, and the D-cut section extends toward the sound signal output part to cover a part of the circuit board.