| 摘要 |
PURPOSE:To correct an erroneous convergence due to the frame aberration of a vertical center beam without applying no influence to a side beam by disposing plural sets of coils forming the magnetic field of plural electrodes in the vicinity of the electron gun of a cathode-ray tube. CONSTITUTION:At the time of correcting the frame in a four pales magnetic field, the side beams 3b, 3r receive vertical force 3 according to the horizontal magnetic field of the four pales magnetic field formed by the correcting coil. Consequently, the side beams 3b, 3r are displaced from an X axis and incident on a vertical deflecting magnetic field 9 forming a barrel shape magnetic field, so that a second correcting coil for forming a two pales magnetic field 6 is disposed and superimposed on the four pales magnetic field 4 to have the distribution state of the magnetic field of the proper intensity. Thereby, the side beams 3b, 3r are made incident on the vertical deflecting magnetic field 9 without the displacement from the X axis to prevent the generation of the erroneous convergence and obtain the picture of good quality.
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