Microphone-unit supporting structure and electronic device

1. A microphone-unit supporting structure comprising a microphone unit and a holder;

wherein the microphone unit includes a substantially-cylindrical microphone element having a front and a back, a printed circuit board fixed to the back of the microphone element, and at least two projections extending radially outward from the printed circuit board and being circumferentially spaced at such an angular interval that when one of the projections is assumed to be on a reference line for line symmetry, the other projection or projections are off the reference line; and

wherein the holder includes a microphone-unit supporting portion having a front, a back, and an inner wall surface and supporting the microphone unit in a manner such that at least a back end part of the microphone unit is loosely fitted in the microphone-unit supporting portion and at least a part of a side of the microphone unit faces the inner wall surface, a seat projecting from the inner wall surface and supporting a part of the printed circuit board, a first groove extending outward from the inner wall surface and receiving first one of the projections to loosely support the first one of the projections, and a second groove extending outward from the inner wall surface and receiving second one of the projections to loosely support the second one of the projections, the first groove being open in a backward direction, the second groove being open in a frontward direction.

2. A microphone-unit supporting structure as recited in claim 1 , further comprising a loudspeaker, a cushion supporting a back of the loudspeaker, and a loudspeaker supporting portion provided in the holder and having a recess, the loudspeaker supporting portion supporting the loudspeaker and the cushion in a manner such that the loudspeaker and the cushion are fitted in the recess, the loudspeaker supporting portion being adjacent to the microphone-unit supporting portion, the second groove communicating with the recess, the cushion being in watertight contact with a part of the second one of the projections which is in the second groove.

3. A microphone-unit supporting structure as recited in claim 1 , further comprising a packing fitting over a front of the holder and having an opening for accommodating the microphone element and a rib projecting into the opening, the rib being in watertight contact with a side surface of the microphone element throughout its circumference.

4. A microphone-unit supporting structure as recited in claim 1 , wherein the projections are formed when the printed circuit board is separated from an original printed circuit board by trimming.

5. An electronic device comprising a microphone unit, a holder, a loudspeaker, a cushion supporting a back of the loudspeaker, and a packing fitting over a front of the holder;

wherein the microphone unit includes a substantially-cylindrical microphone element having a front and a back, a printed circuit board fixed to the back of the microphone element, and at least two projections extending radially outward from the printed circuit board and being circumferentially spaced at such an angular interval that when one of the projections is assumed to be on a reference line for line symmetry, the other projection or projections are off the reference line;

wherein the holder includes a microphone-unit supporting portion having a front, a back, and an inner wall surface and supporting the microphone unit in a manner such that at least a back end part of the microphone unit is loosely fitted in the microphone-unit supporting portion and at least a part of a side of the microphone unit faces the inner wall surface, a seat projecting from the inner wall surface and supporting a part of the printed circuit board, a first groove extending outward from the inner wall surface and receiving first one of the projections to loosely support the first one of the projections, a loudspeaker supporting portion being adjacent to the microphone-unit supporting portion and having a recess, the loudspeaker supporting portion supporting the loudspeaker and the cushion in a manner such that the loudspeaker and the cushion are fitted in the recess, and a second groove extending outward from the inner wall surface and receiving second one of the projections to loosely support the second one of the projections, the first groove being open in a backward direction, the second groove being open in a frontward direction and communicating with the recess; and

wherein the packing has an opening for accommodating the microphone element and a rib projecting into the opening, the rib being in watertight contact with a side surface of the microphone element throughout its circumference.