CRT film scanner with compensation for local brightness variations of scanning beam
US4227207A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Apr 27, 1978 |
| Grant date | Oct 7, 1980 |
| Priority date | — |
| Expiry date | Apr 27, 1998 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/11
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Apparatus for generating color television signals from photographic film by means of a flying spot scanner incorporating a cathode ray tube is provided with a circuit for compensating for differential variations across the color spectrum introduced by variations in the intensity of the scanning beam due to variations in the phosphor, solarization and burning effects on the tube screen, this circuit comprising a photodetector sensitive to the varying intensity scanning beam and feeding a circuit for generating an overall signal representing the variations, selected proportions of this overall compensation signal being used to control respective color channels so that each channel receives a different amount of compensation to compensate for differences in the effects causing such variation across the spectrum of light in the scanning light beam.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.