Warning device for photographic cameras
US3956758A · kind A · utility
Assignees
Inventors
Key dates
| Filing date | Jul 29, 1974 |
| Grant date | May 11, 1976 |
| Priority date | — |
| Expiry date | Jul 29, 1994 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B17/02
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
An exposure indicating means comprising a plurality of light emitting elements which are selectively energized to indicate exposure information in a digital form is connected with an exposure measuring circuit. The light emitting elements are connected with a warning circuit. The warning circuit comprises a warning signal generator which generates a warning signal when a warning is required, a square wave generator which constantly generates a square wave and an AND circuit which transmits the square wave to the light emitting elements when the warning signal is transmitted thereto. The light emitting elements are intermittently turned off by the square wave coming from the AND circuit. The frequency of the square wave is selected so that the intermittent turning off of the light emitting elements is sensed by the photographer viewing through the viewfinder of the camera.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.