| 摘要 |
PURPOSE:To lessen a spot diameter focused on a screen by forming extension electric field lenses on a portion of a main-lens part in an electric gun for a cathode-ray tube in which the main lens part forms a compound-type lens. CONSTITUTION:An in-line configuration electron gun 100 for a color picture tube is formed consisting of a cathode 110, a four-electrode part comprising the first to third grids 101-103, and a main-lens part comprising the third to seventh grids 103-107. A high degree of potential is applied on the gird 107, a lower degree of potential, which is 30-40% of the potential on the grid 107, is applied on both grids 103 and 105, a low or high degree of potential is applied on the grid 104, a median degree of potential, which is 55-65% of the potential on the grid 107, is applied on the grid 106, and the length of the grid 106 is set up in 55-89% of the lens radius. Therefore, together with forming extension electric field lenses in a compound-type lens and improving lens performance, a spot diameter can be lessened with the beams incident into the main lens part being in the best condition. |
