Method of correcting geometrical distortions on the screen of a cathode-ray tube
US4968920A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Apr 28, 1989 |
| Grant date | Nov 6, 1990 |
| Priority date | — |
| Expiry date | Apr 28, 2009 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N3/233
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
Picture tubes with an extremely flat screen exhibit peculiar geometrical distortions in that the beginning and end of the lines in the picture bend symmetrical to the midline as the result of the magnetic deflection field typical of that type of tube. These distortions, called "bending errors," are eliminated in accordance with the invention by coupling another current into the vertical-deflection winding. A current that increases until the horizontal flyback begins is generated 5 to 10 microseconds before the electron beam ends its horizontal forward sweep and an additional current that decreases for 5 to 10 microseconds during the horizontal forward sweep is generated at the end of the horizontal flyback. Eliminating geometrical distortions on the screen of a picture tube.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.