| 摘要 |
PROBLEM TO BE SOLVED: To improve the resolution while obtaining the appropriate concentration of electron beam over the whole current area of the electron beam by changing the distribution of a part of the deflecting magnetic field, and correcting the deflection aberration of the electron beam in response to the deflection angle at the time of changing the orbit of electron beam. SOLUTION: At the time of deflecting the electron beam 10 with the magnetic field of a deflecting yoke, in order to correct the deflection aberration of the electron beam 10 in response to the deflection angle, the work of the magnetic field, of which distribution is changed at an orbit part of the electron beam 10 at an upper side thereof by the work of a soft magnetic piece 39 for changing distribution of a part of the deflecting magnetic field, is applied and the electron beam 10 progresses like an orbit 10u'. The electron beam 10 at a lower side orbit part progresses in an orbit 10D independently of the influence of the magnetic field, of which distribution is changed, and forms a spot having a small diameter D3 in a fluorescent film 13 without crossing the electron beam peripheral orbit 10u'. Distribution of the spots on the fluorescent film 13 can be adjusted by combination of fitting position and structure of the soft magnetic piece 39, distribution of the deflection magnetic field and the maximum deflection angle of a cathode-ray tube, and a difference between a beam spot diameter D1 at a central part of the screen can be reduced, and the even resolution can be obtained over the entire screen.
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