| 摘要 |
PURPOSE:To reduce the visual distance of a cathode-ray tube greatly by specifying the distance between a structure and a fluorescent film by the inner diameter of the structure, the largest diameter of the fluorescent film, the distance between adjacent fluorescent films and the spreading angle of a non-focused electron beam. CONSTITUTION:When the inner diameter of a structure 12 is supposed to be d, the distance between the structure 12 and a fluorescent film 14 is supposed to be l, the largest diameter of the fluorescent film 14 is supposed to be D1, the distance between adjacent fluorescent films is supposed to be D2 and the spreading angle of a non-focused electron beam is supposed to be theta, these values are specified as being indicated in the formula. In a light source cathode-ray tube with such constitution, when a non-focused electron beam 10 is discharged from an electron gun 4 at a given spreading angle, the peripheral part of the beam 10 is trimmed according to the inner diameter of the cylindrical structure 12, thereby there is nothing to stimulate part of a fluorescent film 14 formed on the inner surface of a vacuum encircling case 1 which is adjacent to and other than a given part of the film 14. |
