S-correction in very slim CRTs

摘要

To correct the S-distortion in large deflection angle cathode-ray tubes (CRTs), ideal deflection current waveforms are proposed to realize S-correction. Analysis was done for homogenous and non-homogenous magnetic fields, plane and curved screen. For the convenience of circuit design, high order sine waveforms are used to approach the ideal deflection current. After optimization, the deflection current is acceptably close to the ideal one, for a deflection angle range from 90 deg up to 140 deg. Harmonic current rank rises to four as the deflection angle reaches 140 deg. A ladder-type driving circuit to realize these sine wave series is also presented. Simulation and experiments prove the proposed method can correct the S-distortion in a very slim CRT.