Light box with improved spectral response for CCD imager
US4864408A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Oct 31, 1988 |
| Grant date | Sep 5, 1989 |
| Priority date | — |
| Expiry date | Oct 31, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N2201/0404
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A charge coupled device image sensor in a film-to-video player senses light transmitted through a frame of film from a light box. The light box houses a tungsten halogen bulb at one end and a diffuser at the opposite end adjacent the film. An intermediate opaque pyramidal surface, or "flag", prevents direct light from the bulb reaching the diffuser. The apex of the pyramidal flag is centered with and aimed at the filament of the bulb, and has a hole through it the size of the filament, permitting a small beam of light directly from the filament to reach the center of the diffuser. All interior box surfaces (including the flag) are blue, to compensate for the chrominance response of the charge coupled device sensor. The pyramidal flag and the hole in the pyramidal apex provides a uniform light intensity across the surface of the diffuser.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.