Vignetting compensating circuit for a video camera
US4884140A · kind A · utility
8Cited by
6References
4Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | Nov 2, 1988 |
| Grant date | Nov 28, 1989 |
| Priority date | — |
| Expiry date | Nov 2, 2008 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N23/81
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A vignetting compensating circuit for a video camera utilizing the horizontal synchronizing signal and the vertical synchronizing signal. The circuit prevents vignetting on the screen from a signal generated by a video camera with a zoom lens by obtaining and adding inverse parabolic wave form voltages corresponding to the cycles of the horizontal synchronizing signal and the vertical synchronizing signal and controlling the amplification factors of a voltage controlled amplifier for the video signal by the added voltage.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.