Patent ID: 6388368
Filing Date: 2002-05-14
Classification: H01J

Abstract:
A color cathode ray tube comprising:an evacuated envelope comprising a panel portion, a neck portion and a funnel portion for connecting said panel portion and said neck portion, said panel portion including a faceplate; a phosphor screen formed on an inner surface of said faceplate, said phosphor screen including a multiplicity of phosphor elements of a plurality of colors; a shadow mask having a multiplicity of apertures therein and spaced from said phosphor screen in said panel portion; a plural-beam in-line type electron gun housed in said neck portion for generating a plurality of electron beams and projecting said plurality of electron beams through said shadow mask to said phosphor screen; a magnetic shield of generally truncated pyramidal shape housed in said funnel portion; and a deflection device mounted in a vicinity of a transition region between said funnel portion and said neck portion for scanning said plurality of electron beams on said phosphor screen; wherein said magnetic shield is configured so as to satisfy a following inequality: Dcorwhere Dave=(Dverm+Dhorm+Dcor)/3, Dmax and Dmin are respectively a maximum and a minimum of magnetic shield-core distances between an end of a magnetic core of said deflection device facing toward said faceplate and an end of said magnetic shield facing toward said plural-beam in-line type electron gun, said magnetic shield-core distance being measured in a section plane containing a longitudinal axis of said cathode ray tube and being inclined at said section plane angle &thgr; with respect to a horizontal scanning direction of said plurality of electron beams, Dverm and Dhorm are magnetic shield-core distances measured at section plane angles 0Â° and 90Â°, respectively, and Dcor is a magnetic shield-core distance measured in a section plane intersecting a corner of a generally rectangular end of said magnetic shield facing toward said electron gun.