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Color cathode ray tube having an improved electron gun

  • US 20020185957A1
  • Filed: 08/08/2002
  • Published: 12/12/2002
  • Est. Priority Date: 09/05/1997
  • Status: Active Grant
First Claim
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1. 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>

    H


    2×

    S;

    where A is V1×

    V2×

    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 P×

    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.

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