| 摘要 |
PURPOSE:To simplify the structure of a device by composing a control grid of one conductive plate which has plural openings, folding both sides of the conductive plate at a prescribed angle along lines parallel to an electrostatic discharging electrode and thus forming fitting parts, and fitting the device by utilizing the fitting parts on both sides. CONSTITUTION:Many openings 17 are formed at the center part of one flat conductive plate 12, which is folded at an acute angle on both sides of the control grid part 12B along parallel lines 18. Those lines 18 are parallel to the electrostatic discharging electrode 11 when the conductive plate 16 is arranged at the periphery of the discharging electrode 11. The part (shield electrode part 12A) folded at the acute angle along the lines 18 are drawn back to make the shield electrode parts 12A on both sides parallel to each other and then the control grid part 12B is curved at this time. Thus, the shield electrode parts 12A on both sides are used as the fitting parts and fitted to a cover 13 while held parallel, so that the curved control grid part 12B is formed.
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