Electronic strobe flash apparatus for indirect and direct flash
US4384238A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Dec 15, 1980 |
| Grant date | May 17, 1983 |
| Priority date | — |
| Expiry date | Dec 15, 2000 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG03B2215/0553
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
Electronic strobe flash apparatus includes a first energizable flashtube arranged to project light for reflection from a surface to illuminate a scene indirectly, and a second energizable flashtube arranged to illuminate the scene directly. A sequencing circuit controls the energization of both flashtubes so that the ratio of the indirect flash to the direct flash reflected from the scene is constant in instances where the reflected flash is above a minimum level. For this purpose, a light-sensitive circuit, arranged to sense light reflected from the scene, is coupled to the sequencing circuit. The sequencing circuit causes the indirect flash to be produced first. The light-sensitive circuit causes the sequencing circuit to (1) quench the first flashtube to extinguish the indirect flash, and (2) fire the second flashtube to produce the direct flash, when the light-sensitive circuit senses that a predetermined fraction of a desired total amount of light has been reflected from the scene. Then, the sequencing circuit quenches the second flashtube to extinguish the direct flash when the light-sensitive circuit has sensed the desired total amount of reflected scene light. If the light-…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.