An imaging system utilizes an exposure control circuit to control the length of an exposure in full frame mode. The mobile station device also includes a received power processing section for sequentially storing received power of a pilot signal transmitted from the base station, and determining transmission power at the retransmitting time of the access packet on the basis of these stored contents. A battery powered motor drives a drive mechanism which reciprocates an output drive shaft, which drive shaft is in turn connected through a flexible drive rod to a drive disc.