Video black level reference system
US4237489A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Feb 26, 1979 |
| Grant date | Dec 2, 1980 |
| Priority date | — |
| Expiry date | Feb 26, 1999 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N5/165
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A circuit and method for effecting automatic brightness control for a television receiver CRT. The video signal is AC coupled to a signal input of a comparator. The comparator also has a reference input to which is applied a viewer-adjusted reference signal. A DC output voltage is developed in response to the difference in voltages present at the signal and reference inputs. The comparator is rendered sensitive, via a Video Blanking pulse to only the luminance component and a portion of the horizontal sync component of the video signal. The Video Blanking pulse can be synthesized by phase shifting and clipping the horizontal retrace pulses.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.