| 摘要 |
PURPOSE:To improve color saturation characteristics and color purity characteristics by offsetting and compensating the variation of the focal length of a magnetic lens, by means of an electrostatic lens that is set so that its focal length can be actuated in the direction opposite to variations of the high voltage of a cathode-ray tube. CONSTITUTION:A magnetic lens LM built up in an external magnetic field type has its donut-shaped ferrite magnet m inserted in and fixed to iron/annular thin plates r1 and r2 and is fixed and made to adhere to the neck section N of a cathode-ray tube. A high voltage generator circuit H is provided in such a way that it is independent of the high voltage rectification output V1 of a flyback transformer F in relation to an electrostatic lens LS and formed by a combination of a generator circuit 10 a high voltage generation transformer T, and a rectification smoothing circuit R. Thus, the stable output V2 of the high voltage generator circuit is applied to the third and fourth electrodes g3 and g4 that form the electrostatic lens LS irrespective of the variation of beam current. As a result, almost a uniform fine beam diameter can always be maintained regardless of the variation of beam current. |
