System for providing an accurate indication whether film is exposed or unexposed, independent of battery voltage
US5671456A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 7, 1995 |
| Grant date | Sep 23, 1997 |
| Priority date | — |
| Expiry date | Mar 7, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2217/263
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A microcomputer provided in a camera body uses a data signal read by sensors facing the data disk of a film cartridge as a positional signal to set the stop position of the spool for providing exposed/unexposed indication to the film. The voltage of the power supply of the camera is detected to modulate a pulse duration by which the number of rotations of the motor can be kept constant in rewinding the film. The sensors are disposed upstream in the rotational direction of the data disk by a certain angle .theta. with respect to the point at which the spool is stopped in order to prevent the dislocation between the display mark of the cartridge and the pointing mark of the data disk. The microcomputer discriminates whether or not data has been read. The mechanism for feeding the film is controlled to set the film at a predetermined position after the decision that the data has been read.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.