Patent ID: 6955338

Claim:
An air passage opening/closing device comprising: a case for defining an air passage therein: a film member disposed in the case, for opening and closing the opening of the air passage; a fixing portion for fixing one end of the film member to the case on an outer periphery of the opening; and an operation mechanism capable of moving on the opening of the air passage in a first direction separated from the fixing portion and in a second direction approaching the fixing portion; wherein the operation mechanism changes a length of the film member from the one end of the film member by the movement of the operation mechanism on the opening of the air passage; the operation mechanism includes a film winding shaft to which the other end of the film member opposite to the one end is connected, and a moving mechanism for moving the film winding shaft on the outer periphery of the opening in the first direction and in the second direction while rotating the film winding shaft; the film member at a side of the other end is wound around the film winding shaft, and is unwound from the film winding shaft; and the operation mechanism further includes a rotational-angle adjusting mechanism for adjusting a rotational angle of the film winding shaft so as to compensate a diameter change of the film member wound around the film winding shaft.