Film advancement control for motion picture projector
US4084892A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Feb 18, 1977 |
| Grant date | Apr 18, 1978 |
| Priority date | — |
| Expiry date | Feb 18, 1997 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B31/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A control for varying the speed of advancement of film is described for use in a film projector in which the film is advanced by a shuttle tooth which engages perforations in the film and advances the film along a path between a light source and a projector aperture. The control includes a rotary shutter assembly having one or more shutter blades for interrupting the light from the light source. As the shutter assembly rotates, the shuttle tooth is reciprocated in the direction of film feed by a rotary cam having one or more cam lobes mechanically coupled to the shuttle tooth. The rotation of the cam lobes is synchronized to the rotation of the shutter blades such that the shuttle tooth is positioned for engagement with the perforations associated with the next successive film frame to be projected whenever a shutter blade interrupts the light source. To engage the shuttle tooth with the film perforations, means are included for sensing the interruption of the light source by the shutter blades to generate a train of pulses, each equal in separation to 1/Nth number of light interruptions, (where N is selectable) and, in response to each pulse, means for advancing the shuttle tooth …
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.