Horizontal deflection circuit with raster correction
US5798621A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Mar 18, 1996 |
| Grant date | Aug 25, 1998 |
| Priority date | — |
| Expiry date | Mar 18, 2016 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/233
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
An electron beam tends to slope downwardly as it is deflected horizontally to form a raster in a video display apparatus. The sloping of the beam can cause geometric errors in the raster, for example, orthogonality and parallelogram errors. A raster correction circuit offsets orthogonality and parallelogram errors in a raster by modulating a horizontal deflection current at a vertical scanning rate. The raster correction current is phased in relation to a horizontal-rate deflection current such that scan lines in an upper-half portion of the raster are shifted to the right, and scan lines in a lower-half portion of the raster are shifted to the left.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.