| 摘要 |
A color cathode ray tube (CRT) has an electron-optical system (1) for generating three electron beams (EBR, EBG, EBB), deflection means (2) and a screen (3). In operation, the deflection means (2) deflect the electron beams (EBR, EBG, EBB), so as to change a landing position of the beams on the screen (3). However, by deflecting the beams, the beams are defocused and the spot on the screen (3) changes. In a color cathode ray tube with a relatively large screen, the electron beam defocusing can be observed to be different in strength for each beam (EBR, EBG, EBB). The invention provides a solution to this problem by providing a modified DAF section (40) in the electron-optical system (1). The DAF section (40) comprises at least two electron lenses (L1, L2) having different strengths for each electron beam (EBR, EBG, EBB).
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