Method of correcting deflection defocusing in a CRT, a CRT employing same, and an image display system including same CRT

摘要

A cathode ray tube includes an electron gun having a plurality of electrodes, an electron beam deflection device and a phosphor screen. A method of correcting deflection defocusing in the cathode ray tube includes placement of pole pieces of magnetic material in a deflection magnetic field produced by the electron beam deflection device and thereby establishing a non-uniform magnetic field varying in synchronism with the deflection magnetic field in a path of an electron beam and correcting deflection defocusing of the electron beam in an amount corresponding to the deflection of the electron beam.