MAGNETIC SHIELD MATERIAL FOR CATHODE RAY TUBE AND INTERNAL MAGNETIC SHIELD DEVICE FOR CATHODE-RAY TUBE

摘要

PROBLEM TO BE SOLVED: To reduce the deviation of an electron beam by geomagnetism by using a shield material having a difference between the residual magnetic flux density in the perpendicular direction to a roll seam and the residual magnetic flux density in the parallel direction with the roll seam at the time of rolling, and setting the value divided with the larger residual magnetic flux density by the smaller residual magnetic flux density to a specific value or above. ;SOLUTION: The magnetic permeability in the tube axial direction of the magnetic shield of a geomagnetism shield device 30 is made larger than the magnetic permeability in the vertical direction and the lateral direction by utilizing the magnetic permeability ratio indicating the magnetic anisotropy of the magnetic shield material. When magnetic shield plates 32A, 32B, 34A, 34B are formed from the magnetic shield material and connected to a frame 18, they are arranged so that the direction with high magnetic permeability is set along the tube axis and the direction with low magnetic permeability is set along the sides of the frame 18. The magnetic permeability ratio divided with the larger magnetic permeability by the smaller magnetic permeability in the perpendicular direction to a roll seam and the parallel direction with it is set to 1.4 or above.;COPYRIGHT: (C)1998,JPO