Patent ID: 6624562
Filing Date: 2003-09-23
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; a three-color phosphor screen formed on an inner surface of said panel portion; a shadow mask having a multiplicity of apertures therein and spaced from said phosphor screen; a three-beam in-line type electron gun housed in said neck portion; said three-beam in-line type electron gun including an electron beam generating section for generating three electron beams and a main lens section for focusing said three electron beams on said three-color phosphor screen; and a deflecting device mounted in a vicinity of a transition region between said funnel portion and said neck portion for scanning said three electron beams on said three-color phosphor screen; said main lens section comprising a focus electrode and an anode facing said focus electrode; wherein said main lens section comprises a focus electrode and an anode facing said focus electrode, said focus electrode being composed of plural focus electrodes; each of said anode and a first one of said focus sub-electrodes facing said anode comprises a first electrode member having a single opening common for said three electron beams in an end thereof facing another of said anode and said first one of said focus sub-electrodes, and a second electrode member set back from said end of said first electrode member for forming three beam apertures for passing said three electron beams, respectively; and a following inequality being satisfied: (A+566)/106>Hâˆ’2Ã—S; â€ƒwhere A is V1Ã—V2Ã—T, V1 is a vertical diameter of said single opening, V2 is a vertical diameter of a center one of said three beam apertures, T is an axial distance between said single opening and said second electrode member, H is a horizontal diameter of said single opening, and S is PÃ—L/Q, where P is a horizontal center-to-center spacing between adjacent phosphor elements at a center of said three-color phosphor screen, Q is an axial spacing between said three-color phosphor screen and said shadow mask at the center of said three-color phosphor screen, and L is an axial distance between said shadow mask and said single opening in said focus electrode member of said first one of said focus sub-electrodes.