| 摘要 |
PURPOSE:To restrict fluidization of an extra thick part in a direction in which losses are generated and hence to improve precision for recessed part formation by forming a projecting part which is formed into an annular vertical cross-sectional shape around a recessed part by half shearing processing. CONSTITUTION:A second grid electrode 20 has a slit-shaped recessed part 22 formed on the peripheral part of an electron beam aperture 21. The peripheral part of the electron beam aperture 21 is made thin in its horizontally deflecting direction and thick in its vertically deflecting direction. A projecting part 23 of an annular vertical cross-sectional area is formed around the recessed part 22 by half shearing processing. When the projecting part 23 is formed into such a vertically crosssectional shape, a projecting side 231 and a recessed side 232 of the projecting part 23 can be easily locked over the whole peripheries upon the coining processing of the recessed part 22, and besides extra thick part's fluidization in the direction of the projecting part 23, which has previously occurred at an opening 221 of the recessed part 22 and caused generation of losses, can be restricted and so the fluidization is centralized in directions in which diameters of lower holes 24 and 29 are reduced. Hence, the recessed part can be formed with uniform and high precision for its shaping.
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