End of film detection device
US4721970A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Jul 1, 1986 |
| Grant date | Jan 26, 1988 |
| Priority date | — |
| Expiry date | Jul 1, 2006 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B1/62
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A camera, typically a security camera utilizing film in a cartridge, with means for determining when the film in the cartridge has been exhausted. A radiation emitter with the wavelength of the emitted radiation outside the sensitivity range of the film, a detector for the radiation of the emitter, and a reflecting surface, with the reflecting surface on one side of the film and the emitter and detector on the other side of the film so that presence of film blocks the radiation path from the emitter to the reflecting surface to the detector. A control circuit for controlling camera operation, with the radiation detector output serving to shut off power to the motor when the film supply is exhausted.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.