US Patent 7354340 Louver apparatus

A louver apparatus includes a case member, a connecting member, and a louver pivotally secured to the case member, including a shaft portion including a shaft body being in the form of a substantially cylindrical shape, and a head portion being in the form of a substantially regular polygon, and being located at a tip end portion of the shaft body. At least a part of the head portion protruding radially from the shaft body. The connecting member includes an axial hole being in the form of a substantially regular polygon. The head portion is arranged to pass through the axial hole only at predetermined positions, and to be held not to pass through the axial hole at positions other than the predetermined positions.