Control apparatus for film pressure plate in cameras
US4933693A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 14, 1989 |
| Grant date | Jun 12, 1990 |
| Priority date | — |
| Expiry date | Jul 14, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2217/268
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A camera is adapted for use with a film cassette in which a film spool is rotatable to unwind a filmstrip off the spool to automatically thrust a non-protruding leader portion of the filmstrip from the cassette to enable the leader portion to be propelled in the camera over an exposure opening and to a film take-up means. The filmstrip including the leader portion has a natural tendency to curve crosswise. In the camera, a pressure plate is resiliently biased to an operative position for pressing the filmstrip flat at the exposure opening. A restraining device is operated to hold the pressure plate in a retracted position sufficiently removed from the exposure opening. This permits the filmstrip to assume its natural cross-curvature in order to significantly increase the longitudinal strength of the leader portion to facilitate its being propelled over the exposure opening and to the film take-up means responsive to unwinding rotation of the film spool. When the filmstrip is taken up at the take-up means, the restraining device releases the pressure plate for movement to its operative position.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.