Patent ID: 6404117
Filing Date: 2002-06-11
Classification: H01J

Abstract:
A cathode ray tube apparatus comprising:a vacuum envelope including a faceplate having on the inner surface thereof a substantially rectangular phosphor screen having an aspect ratio M:N between the length along a horizontal axis perpendicular to a tube axis and the length along a vertical axis perpendicular to the tube axis and the horizontal axis; a cylindrical neck portion having an electron gun assembly built therein for emitting electron beams in the direction along the tube axis, a funnel portion for connecting said faceplate and said neck portion, and a yoke portion of which a section perpendicular to the tube axis on the neck portion side of the funnel portion changes in shape from a circle of the same diameter as the neck portion to a non-circle having a maximum diameter in other than the directions along the horizontal axis and the vertical axis; and a deflection yoke mounted on the outer surface of the vacuum envelope and extending from said neck portion to the yoke portion for forming a deflection magnetic field for deflecting the electron beams; wherein said deflection yoke includes a cylindrical core formed of a magnetic material surrounding at least one of a horizontal deflection coil and a vertical deflection coil for forming said deflection magnetic field; and wherein at least one section of said core portion perpendicular to said tube axis is a non-circle having a maximum inner diameter in other than the direction along the vertical axis and the horizontal axis, where the inner diameter is the distance between the tube axis and the inner surface of the core portion, and holds the relation (M+N)/(2*(M2+N2)Â½SB+LB)/(2DB)&lE;0.90 where SB is the inner diameter along the vertical axis, LB the inner diameter along the horizontal axis, and DB the maximum inner diameter.