| 摘要 |
PURPOSE:To obtain the beam spot in a constant diameter by obtaining the maximal value of voltge distribution on the axis of electron gun in the G3 electrode rigion, the minimal value through gradual reduction in the G4 electrode region and by increasing the voltage continuously in the regions from the G4 electrode to the G5 electrode. CONSTITUTION:Crossover 5 is formed by a cathode lens 4 consisting of a cathode 1, G1 electrode 2 and G2 electrode 3, a potential inclination of about 10<5>V/ cm-5X10<5>V/cm is given by connecting the G3 electrode plate 22 adjacent to the G2 electrode 3 to the G5 electrode 21, and moreover a variable focus voltage is applied to the G4 electrode 23, while a high voltage to the G5 electrode 21. Voltage distribution on the axis is increased up to the maximum value in the beam passing hole 24, it is gradually decreased toward the G4 electrode 23 and then it is increased continuously and finally it is kept to a constant value. Therefore, spheric aberration can be lowered and imaginary picture crossover diameter can also be reduced by increasing voltage inclination at the beam forming area and a high resolution can be obtained even under the high luminance condition. |
