| 摘要 |
PURPOSE: An electron gun for a CRT(Cathode Ray Tube) with electrodes is provided to reduce aberration of electron beams caused by large-diameter holes, to change the sectional area of electron beams to a desired shape and to improve focusing of electron beams by reducing focus voltage difference between electron beams passing the holes. CONSTITUTION: A prefocus lens is formed between a control electrode(52) and a screen electrode(53) while a main lens is between the first and second condensing electrodes(60,70). The main lens forms an electron lens and the electron beams pass through the electron lens as an equipotential surface is formed in a normal direction of an electric force. The electron beams are influenced by different condensing elements through central and both small-diameter holes because of asymmetric large-diameter holes. Central electrodes have long horizontal/diagonal distances to be influenced by a large diffusion force in horizontal/diagonal directions. The focusing of electron beams is reduced by induction of focus voltage difference. However, the electron gun has inlet portions around the small-diameter holes to increase the horizontal diffusion force of electron beams and to compensate condensing/diffusion force difference of a large-diameter lens.
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