| 摘要 |
PURPOSE:To obtain a micro-assembly of cathode ray tube having high efficiency while causes no ion burning without providing a metal back, by providing a permanent magnet for producing electron beam focus magnetic field approximately in parallel with the tube axis between cathode of electron gun and deflection yoke. CONSTITUTION:A cathode ray tube comprising an electrostatic focus type electron gun 3 and a phosphor substance screen 11 facing each other through no metalback is provided with a permanent magnet 9 for producing electron beam focus magnetic field approximately in parallel with the tube axis between the cathode 4 of electron gun 3 and deflection yoke 13. Consequently the electron beam 14 is focused through magnetic lens 15 due to permanent magnet and main electron lens 16 to converge at one point on the face of phosphor substance screen 11 while the negative ion beam 17 is mainly focused through main electron lens 16 not to converge onto one point but to disperse in relatively wide range. Consequently ion burning is relieved irrespective of no metalback. |
