Tri-state on-screen display system
US4760391A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | May 10, 1985 |
| Grant date | Jul 26, 1988 |
| Priority date | — |
| Expiry date | May 10, 2005 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G5/24
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An on-screen character display system includes a tri-state character generator for generating a tri-state character signal having black portions corresponding to the leading and trailing edging portions of the character and a white portion corresponding to the body of the character and an inactive level when no character is to be displayed. To prevent the shielded cable used for coupling the tri-state character signals to video signal processing circuit from remaining charged to the black level corresponding to the trailing edging portion too long thereby creating a disturbing inequality between the widths of the edging portions, an auxiliary driver circuit is enabled to drive the shielded cable toward the inactive level when the character is supposed to end.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.