| 摘要 |
PURPOSE:To improve static convergence and focusing characteristics, by forming the electrodes comprising a lens common to electrodes on low-voltage and high-voltage sides, which compose main lenses, and the other electrodes having electron beam-passing apertures, which compose lenses for respective electron beams, in the same shapes and sizes. CONSTITUTION:Elliptic cylinder electrodes 11a, 11b, and flat plate electrodes 12a, 12b, on which three electron beam-passing apertures 21-23 are formed in line, are formed respectively in the same shapes and sizes. Electron lenses 51 to 53 on a low-voltage side electrode 1 have focusing action and those 61 to 63 on a high-voltage side electrode 2 have divergent action. Therefore, when the electrodes 11a, 11b and 12a, 12b, which compose main lenses 5, are formed in the same shapes and sizes and assembled so that errors produced when they are formed are in the same direction, the force, acting on the electron beams works in the opposite direction, so that it works to cancel the change in action caused by changes in shapes and sizes of electrodes. Hence, the dimensional dispersion of electrodes, which consist main lenses, affects little on characteristics, so that, stable focusing characteristics and static convergence can be obtained.
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