CONVERGENCE YOKE WITH IMPROVED FOCUS CHARACTERISTICS

摘要

PURPOSE: A convergence yoke with improved focus characteristics is provided to achieve an improved screen quality by correcting coma aberration and improving focus characteristics of electron beam through a uniform magnetic field. CONSTITUTION: A convergence yoke comprises coils(LV41,LV42) for vertical correction fields and coils(LH41,LH42) for horizontal correction fields; and a core(40). The coils generate correction fields having shapes converting from barrel-like magnetic field into pincushion-like magnetic field in accordance with the axial direction or a cathode ray tube so as to correct coma aberration. The barrel-like magnetic field and pincushion-like magnetic field are compensated with each other, to thereby obtain a uniform magnetic field without causing changing in magnetic field intensity, and improved focus characteristics of electron beam. The core generates the barrel-like magnetic field and pincushion-like magnetic field so as to permit the coils to have uniform correction magnetic fields.