Patent ID: 6741020
Filing Date: 2004-05-25
Classification: H01J

Abstract:
A cathode ray tube comprising:a vacuum envelope comprising a panel portion, a neck portion, a funnel portion having a large-diameter end thereof connected to said panel portion and a small-diameter end thereof connected to said neck portion, and a stem having conductive pins embedded therein and closing off an open end of said neck portion on a side thereof opposite from said funnel portion; a phosphor screen formed on an inner surface of said panel portion; an electron gun housed within said neck portion; and a deflection yoke mounted externally of said vacuum envelope in a vicinity of a transition region between said neck portion and said funnel portion; wherein said electron gun comprises a cathode, a beam control electrode, an accelerating electrode, a first electrode, a focus electrode and an anode arranged in the order named with specified spacings therebetween, wherein said anode is formed of a large-diameter cylinder portion disposed on a phosphor screen side thereof and a small-diameter cylinder portion disposed on a cathode side thereof, said large-diameter cylinder portion and said small-diameter cylinder portion being connected together in a direction of an axis of said cathode ray tube, wherein said focus electrode is formed of a large-diameter cylinder portion disposed on a phosphor screen side thereof and having a diameter larger than a diameter of said small-diameter cylinder portion of said anode, and a small-diameter cylinder portion disposed on a cathode side thereof and having a diameter smaller than a diameter of said small-diameter cylinder portion of said anode, said large-diameter cylinder portion and said small-diameter cylinder portion of said focus electrode being connected together in the direction of the axis of said cathode ray tube, said large-diameter cylinder portion of said focus electrode being disposed concentrically with and within said large-diameter cylinder portion of said anode, wherein said anode and said first electrode are electrically connected together within said cathode ray tube, and wherein the following inequalities are satisfied: âˆ’LP+184.9&gE;LG4&gE;0.0004 LP3âˆ’0.1571 LP2+21.006 LPâˆ’922.41, where LG4 (mm) is an axial length of said focus electrode, and LP (mm) is a distance from a phosphor screen side end of said focus electrode to a center of said phosphor screen.