Patent ID: 6107743
Filing Date: 2000-08-22
Classification: H04N

Abstract:
A method for correcting image errors caused by residual magnetism in a picture tube by means of demagnetization based on the use of an alternating damped magnetic field characterized in that the demagnetization is directed to a neck part (11) of the picture tube (10) and to either internal structures or external structures or to both internal structures and external structures of the neck part (11) of the picture tube (10) comprising the steps of:producing said alternating damped magnetic field in accordance with a demagnetization control program for controlling current flowing through said either internal or external structures;sensing the magnitude of said alternating damped magnetic field;adjusting in response to said sensed magnitude of said magnetic field the magnitude of said current flowing through said either internal or external structures;comparing the magnitude of said sensed magnetic field to a predetermined end magnitude of said magnetic field, andrepeating the steps of sensing, adjusting and comparing until said sensed magnetic field magnitude is equal to or less than said predetermined end magnitude of said magnetic field.