Motor-driven film winding mechanism

摘要

A motor-driven film winding mechanism for cameras has a driving force transmission including a clutch releasably connecting a sprocket drum to the driving force transmission. The clutch can operate to release the sprocket drum from the system in dependence on the speed of movement of the sprocket drum relative to that of the transmission so as to cause the sprocket drum to be driven by the film either when wound up or rewound. The transmission is a gear train one of whose gears drives ratchets that engage with a ratchet wheel on the sprocket drum to constitute the one-way clutch.