COLOR CATHODE-RAY TUBE

PROBLEM TO BE SOLVED: To provide a cathode-ray tube capable of effectively reducing the influence of an external magnetic field upon static convergence characteristics. SOLUTION: In this cathode-ray tube adopting the 'Trinitron' system, a neck twist coil 28 is provided for correcting a neck twist included in static misconvergence by applying a tube axial direct current magnetic field to an electron beam generated from a RGB color cathode. A ring-shaped magnetic substance 26 is attached to the outer periphery of a neck part 12 in order to shield an electron gun from the effect of an external magnetic field. In addition, the neck twist coil 28 is attached to the outer periphery of the magnetic substance 26. At the time of normal real operation, the amount of a direct current flowing through the neck twist coil 28 is controlled to correct the neck twist. Furthermore, an alternating damped current is transitorily passed through the neck twist coil 28 for the purpose of performing demagnetization of the magnetic substance 26 to enhance the function as a shield against the external magnetic field.