Patent ID: 6586893
Filing Date: 2003-07-01
Classification: H01J

Abstract:
A device for correcting residual misconvergence errors in a cathode ray tube, the tube including a narrow-necked section, located at the rear thereof, in which electron guns mounted therein generate forwardly-directed electronic beams, an outwardly-opening center skirt section, extending forward from the narrow-necked section, and terminating in a wide perimeter surrounding a relatively flat, pixel-coated, viewing screen section that is arranged generally orthogonal to the axis of the narrow-necked section and upon which the electronic beams are directed to strike the pixels to produce images for viewing from the front of the tube, and further having at least one pair of electromagnetic coils mounted outside the tube, for initial focusing of the electron beams during their travel from the guns to the screen, said device comprising:(a) a separator made of a plastic, said plastic including a high density of magnetizable particles therein, said separator arranged for placement about the outside of the tube and adapted to receive the electromagnetic coils thereon; and, (b) a plurality of small, powerful magnetic poles formed in said separator by at least one application of short-duration, high-voltage charges to various areas on said separator, the location of said magnetic poles determined by measuring the difference between the actual location on the viewing screen where the electron beams strike the pixels and the desired location where the beams are desired to strike the pixels and applying appropriate correction to the paths of the beams using the location and the strength of the magnetic poles.