DEGAUSSING METHOD FOR CATHODE-RAY TUBE

PROBLEM TO BE SOLVED: To efficiently magnetize a DC magnetic field and to correct the shift amount to a phosphor stripe of arm electron beam by generating an AC attenuation magnetic field by degaussing coils disposed for one pair each at the upper, lower, left and right parts of a cathode-ray tube and degaussing the magnetic member of a color sorting device or the like inside the CRT. SOLUTION: The AC attenuation magnetic field is superimposed on the DC magnetic field in the manufacture process of the CRT 13, the magnetic member inside the CRT 13 is magnetized and an electron beam track is corrected by a magnetized magnetic field. In this case, a pair of the degaussing coils 21 and 22 are disposed to the upper, lower, left and right parts of the CRT 13, the AC attenuation magnetic field is generated for the respective pairs of the degaussing coils 21 and 22 at the upper, lower, left and right parts and the electron beam track for magnetizing the magnetic member inside the CRT is corrected. In such a manner, when the AC attenuation magnetic field is successively generated for a pair each of the degaussing coils 21 and 22 arranged at the upper, lower, left and right parts for the shift amount to the phosphor of the electron beam, magnetization is efficiently performed and the electron beam track is corrected by the small-sized degaussing coils 21 and 22.