| 摘要 |
An electron gun assembly has at least one additional electrode located along the equipotential plane of a potential distribution formed between a focusing electrode and anode electrode forming a main lens. In a no-deflection state, the additional electrode receives a voltage of a predetermined level corresponding to the potential of the equipotential plane on which the additional electrode is located. In a deflection state, letting Vf be the application voltage of the focusing electrode, Eb be the application voltage of the anode electrode, and Vs be the application voltage of the addition electrode, a value (Vs-Vf)/(Eb-Vf) changes with an increase in electron beam deflection amount, while the additional electrode forms an electron lens having different focusing powers in the horizontal direction and vertical direction.
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