Method and apparatus for increasing the number of characters per line in a digitally generated display on a limited bandwidth raster scanned device
US4623881A · kind A · utility
Inventor
Key dates
| Filing date | Dec 29, 1983 |
| Grant date | Nov 18, 1986 |
| Priority date | — |
| Expiry date | Dec 29, 2003 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG09G1/16
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A method and apparatus are provided for increasing the number of characters or symbols that can be displayed on a line when the video signal that produces the display is restricted to a limited bandwidth, such as in the case of RF modulating the video signal to produce the display on an unmodified television set. The bandwidth of the video signal is reduced by displaying different portions of the display during one field time and the remaining portion of the display during the next field time. The persistence of the television screen creates the illusion of a complete display. Each luminescent region of each line will be displayed during one field time and blanked during the next field time. In the preferred embodiment, adjacent luminescent regions of a scan line (e.g., separated only by a black region) will be displayed in opposite fields. In an alternative embodiment, adjacent character regions will be displayed in opposite fields. The invention is compatible with standard and high definition television receivers.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.