JPS57199147A - Electron gun structure - Google Patents

Abstract

PURPOSE:To provide an electron gun structure with which a good beam spot, without any halo developing in the peripheral part of a panel, can be obtained. CONSTITUTION:In an electron gun structure 41, a second grid 45 is provided with a pair of projections 511 and 512 which are on the side of a third grid 46, have a given height, are located equally apart from an electron-beam passing hole 451, and the lengthwise direction of which is parallel to a horizontal axis (X). On the other hand, the third grid 46 is provided with a pair of projections 521 and 522 which are on the side of the second grid 45, have a given length, are located equally apart from an electron-beam passing hole 46, and the lengthwise direction of which is parallel to a vertical axis (Y). Owing to the above constitution, although electron beams 43 discharged from a cathode 42 usually pass through the second grid 45 and other grids provided in back of the grid 45, while diverging and forming a cross over near the grid 45, the horizontal section of the beams 43 shows a weak focusing effect around the grid 45 and a relatively intense diverging effect around the third grid 46. In contrast, as to the vertical section of the beams 43, they receive a relatively intense focusing effect around the grid 45, and receive a weak focusing effect around the grid 46. As a result, the astigmation component of the beams 43 in the periphery of a fluorescent screen 11 is decreased, and the development of haloes is reduced.