Display device comprising a deflection unit
AssigneeKoninklijke Philips Electronics N.V.
InventorMichiel Harjon Wassink
Life of this patent
Estimating the term…
Abstract
A color display device comprising a cathode ray tube and a deflection unit is described. The display device includes compensation coils for correcting a raster distortion in the raster displayed on the screen and means for providing correction currents through the correction coils. The ratio between the correction current I24 and the vertical deflection current I21 is higher at half vertical deflection than at full vertical deflection.
Claims15
A color display device comprising a cathode ray tube having a display screen, means for generating at least one electron beam, a vertical deflection unit for generating deflection fields for deflecting the at least one electron beam across the display screen, a vertical deflection current source producing a vertical deflection current through the vertical deflection unit, and magnetic field-generating means at or near a display screen-facing end of the deflection unit to reduce raster distortions, the magnetic field-generating means comprising correction coils and means for supplying said correction coils, in operation, with a correction current, wherein the ratio between the correction current and the vertical deflection current is a function of the vertical deflection and is less for full vertical deflection (N or S) than for half vertical deflection (0.5 N or 0.5 S).
A display device comprising
- a cathode ray tube having a display screen;
- an electron gun generating an electron beam;
- a vertical deflection unit for vertically deflecting said electron beam across the display screen
- a vertical deflection current source for supply said vertical deflection unit with a vertical deflection current;
- a raster distortion correction coil adjacent a display end of said vertical deflection unit;
- and
- a raster distortion current source for supplying said raster distortion correction coil with a raster correction current;
- wherein a ratio of said raster correction current to said vertical deflection current is a function of the vertical deflection of said electron beam such that said ratio is less at full vertical deflection than for half vertical deflection.
A method of correcting raster distortion comprising:
- deflecting an electron beam using vertical current through vertical coils;
- correcting raster distortion by applying a correction current through correction coils such that a ratio of the correction current to the vertical current is a function of the deflection of the electron beam and such that the ratio is less at full deflection than at half deflection.
Dependencies are inferred from the claim text.