Color imaging apparatus having a 1:2 frequency ratio between video and reference signals for high S/N color demodulation
US4691227A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 3, 1985 |
| Grant date | Sep 1, 1987 |
| Priority date | — |
| Expiry date | Oct 3, 2005 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/12
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
In a single-tube color image pickup apparatus, an optical image is passed through a color stripe filter having recurrent groups of different color stripes to a photoelectrical conversion target, which is scanned by an electron beam to generate a video signal comprising a carrier having a frequency inversely proportional to the intervals at which the recurrent groups of filter strips are arranged. The carrier is modulated in phase with the stripes of each group and in amplitude with the intensity of the optical image. Prior to operation, the target is uniformly illuminated with light of a predetermined color to generate the carrier, which is stored into a field memory. During operation the memory is repeatedly addressed to generate a reference signal. The frequency of the reference signal is converted so that the video signal and the frequency-converted reference signal have a frequency ratio of 1:2 and an opposite phase relationship therebetween. A color demodulator receives these signals to derive a pair of color component signals for coupling to a matrix circuit to which a luminance component is also applied.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.