| 摘要 |
1,167,795. Film-strip projectors. BELL & HOWELL CO. June 1, 1967 [July 21, 1967], No.25429/67. Heading G2J. The intermittent film feed in a film-strip projector is provided by a Geneva mechanism in which cam follower pins 34 on a disc fixed on a shaft 19 bearing film driving sprockets 21, engage a heart-shaped cam groove in a motor-driven wheel 41. Shaft 19 may alternatively be manually rotated by handle 20, and in order to avoid jamming of the followers in the cam track (54, Fig. 4, not shown), during manual operation, a recess (68) in nuts (42) of disc (41) is formed adjacent the clevis (57). Sprocket teeth (25) adjacent each pin (34) successively engage recess (68) at times when a single pin (34) is in the track (54), but is not being driven. The driving motor 84 may be remotely controlled, and the cam disc 41 is braked by means of a spring-loaded brake-band which is engaged by an eccentrically mounted pin extending from the face of disc 41. A switch-tripping shoe on the same face of disc 41 cuts out the power supply to motor 84 while a film frame is in the picture gate. |
