Charles W Fox

US Patent:

46978968, Oct 6, 1987

Filed:

Sep 30, 1986

Appl. No.:

6/913680

Inventors:

Charles Fox - Thousand Oaks CA

Assignee:

Showscan Film Corporation - Culver City CA

International Classification:

G03B 2148

US Classification:

352180

Abstract:

A projector is described, of the type wherein a motor-driven sprocket wheel cyclically pulls a film frame-by-frame through a film gate, by applying a large accelerating voltage at the beginning of each cycle, followed by a decelerating voltage and a fine-positioning sequence, which assures that the film will lie close to the final position and be moving slowly at the beginning of the fine-positioning sequence. A determination is made as to whether the film has moved a predetermined distance by a predetermined time after the beginning of each cycle, and the accelerating voltage for the next cycle may be changed to cause such predetermined movement at that predetermined time for subsequent cycles.