Color control circuit for teletext-type decoder
US4388639A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 18, 1981 |
| Grant date | Jun 14, 1983 |
| Priority date | — |
| Expiry date | May 18, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/641
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A color control circuit for selectively modifying the red, green and blue color signals developed at the output of a teletext-type decoder comprises a common input stage responsive to the teletext decoder for developing a bi-level control voltage identifying the portions of the color signals representing background and foreground display information. Each color signal is coupled to a respective output stage which causes the associated color signal to assume a first intensity level in response to the control voltage being at its first level and a second intensity level greater than the first intensity level in response to the control voltage being at its second level. As a result, background colors are displayed at a reduced contrast level relative to foreground colors. In addition, selected single color foreground information may be displayed at a further increased intensity level to improve the readability of the display.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.