| 摘要 |
PURPOSE:To shorten a required time in which an image appears by providing a first electrode with reinforced grooves which interpose an electron beam aperture therebetween and have bottom surfaces projecting to a side of a cathode and have approximately U or V-shaped crosssectional areas and making the approximately U or V-shaped crosssectional area's side walls near to the electron beam aperture be formed asymmetrically shorter than the side walls far from the electron beam aperture. CONSTITUTION:Reinforced grooves 1a which interpose electron beam aperture and have bottom surfaces projecting to a side of a cathode 3 and have approximately U or V-shaped cross-sectional areas are provided for a first electrode 1, and the approximately U or V-shaped crosssectional area's side walls near to the electron beam aperture are formed asymmetrically shorter than the side walls far from the electron beam aperture. When such a method is employed and the first electrode 1 is heated by heat radiation of the cathode 3 at the start of operation and so a temperature rises, the reinforced grooves 1a provided for the first electrode 1 are deformed by heat expansion so that the expansion amount of the side walls large in length is larger than that of the side walls small in length and so a surface of the first electrode 1 finally approach the cathode 3. Hence, a large electric field for electron beam acceleration of a second electrode 2 is energized in the vicinity of the cathode 3, and electron beams quickly increase and so brightness also quickly rises.
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