| 摘要 |
The present invention relates to a color display device comprising a color display tube (1) with a front portion having a truncated cone (3), means for generating a plurality of electron beams (5), a shielding (9) of ferromagnetic material extending substantially parallel to the truncated cone (3), and a demagnetizing device having at least two demagnetizing coils (11,12) extending along the outer circumference of the cone (3). The demagnetizing device is arranged to energize the coils (11,12) simultaneously and with a phase difference, resulting in the generation of a rotating magnetic field. As the magnetic field rotates, it can be arranged to substantially coincide with the shape of the shielding (9), resulting in a magnetic field that is parallel to the shielding (9) over a larger part of the shielding surface. This improves the demagnetizing procedure, leading to a better landing performance of the electron beams.
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