Color cathode ray tube display apparatus with compensation for errors due to interfering magnetic fields
US4410840A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Jul 9, 1981 |
| Grant date | Oct 18, 1983 |
| Priority date | — |
| Expiry date | Jul 9, 2001 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH04N9/28
- WIPO fieldAudio-visual technology
- WIPO sectorElectrical engineering
Abstract
A color cathode ray tube display apparatus is provided with compensation for errors due to interfering magnetic fields in which a deflection yoke causes the electron beams to raster scan across the tube, a convergence assembly on the neck of the cathode ray tube adjusting the beam convergence. Errors in the waveforms suppied to the radial convergence assembly are caused by high frequency magnetic field coupling between the yoke and the convergence assembly via the internal magnetic structure 7 of the cathode ray tube. A compensating coil 11, placed adjacent the convergence coil unit 12, 16 supplies compensating current through resistor 20 to the amplifier 15 driving the convergence coil unit, thus avoiding a fringe on the left-hand side of the screen. Alternatively, compensating current can be derived from the line flyback pulse or the logic signal initiating line flyback.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.