| 摘要 |
PURPOSE:To efficiently converge the electron beam for entire part of phosphor screen by forming the main lens system with a group of electrode consisting of five or more electrodes, setting the length of 3rd electrode to 0.5 times or less of the internal diameter and by superimposing compensating voltage synchronized with the horizontal and vertical deflections. CONSTITUTION:The main lens system is formed by disposing five electrodes 23- 27, for example, as shown in the figure, on the axis of cathode ray tube. The length l in the direction of tube axis of the 5th grid 25 working as the auxiliary electrode is selected to 0.5 times or less of the internal diameter D of tube and a relatively low voltage in the range of 0V - several hundreds volts and a compensating voltage in the amplitude Vd synchronized with the horizontal and vertical deflections of cathode ray tube are applied to such electrode 25. Thereby, homogeneous picture having high resolution can be obtained for the entire part of phosphor screen. |
