| 摘要 |
A film advancing mechanism comprises a planetary gear train including preferably an annular film winding gear having internal teeth meshing with an eccentrically mounted gear carried by a drive gear which rotates in one direction and the other as a manually operable film winding member is moved back and forth. A sun gear carried by a rotatable slip clutch-forming member meshes with the eccentric gear. The slip clutch-forming member forms a slip clutch with a ratchet wheel held against rotation in one direction by a locking pawl so that the sun gear is normally locked against rotation when the film winding member is moved in the winding direction. When the sun gear is locked in position, bodily movement of the eccentrically mounted gear on the drive gear drives the annular film winding gear. When a film metering pawl enters a metering aperture of the film, a pawl locks the annular gear against further rotation. When the annular gear is so locked by the pawl or by the film unwinding completely from its supply spool, the sun gear-carrying member can slip or move with respect to the ratchet wheel, so that continued movement of the manually operable film winding member can take place.
|
