ELECTRON GUN OF CATHODE RAY TUBE

摘要

PURPOSE: An electron gun of a cathode ray tube is provided to maximize usage efficiency of magnetic field generated by an SVM(scanning velocity modulation) coil and avoid focus deterioration due to external electric field. CONSTITUTION: An electron gun of a cathode ray tube comprises a cathode(10) for electron emission, a first to a fifth electrodes(G1-G5) for controlling an electron beam from the cathode(10), a bead glass(12) for in-line arranging the electrodes(G1-G5), and an SVM coil(16) arranged outside a neck(14). The fourth electrode(G4) acts as a focus electrode and constituted by a first and a second separate electrodes(G4-1,G4-2) for forming a gap(g1) through which magnetic field from the SVM coil(16) passes. The first and the second electrodes(G4-1,G4-2) are electrically coupled to each other by a shield electrode(G4-3). The shield electrode(G4-3) has many air-gaps(18) and is formed as a cylindrical mesh electrode surrounding the gap(g1).