Patent ID: 6339300
Filing Date: 2002-01-15
Classification: H01J

Abstract:
A color cathode ray tube comprising:an evacuated envelope including a panel portion, a neck portion, a funnel portion for connecting said panel portion and said neck portion; a phosphor screen formed on an inner surface of a faceplate of said panel portion; an in-line type electron gun housed in said neck portion; and a deflection yoke mounted around said funnel portion; said in-line type electron gun comprising: an electron beam generating section having three in-line cathodes, a G1 electrode and a G2 electrode arranged in the order named for projecting three electron beams arranged approximately in parallel with each other in a horizontal plane toward said phosphor screen; and an electron beam focusing section comprising a G3 electrode, a G4 electrode, a G5 electrode and an anode arranged in the order named for focusing said three electron beams on said phosphor screen; wherein said G5 electrode comprises a plurality of sub-electrodes arranged to be supplied alternately with a first focus voltage and a second focus voltage, said first focus voltage being a first fixed voltage, said second focus voltage being a second fixed voltage superposed with a dynamic voltage varying with deflection of said three electron beams; at least one electrostatic quadrupole lens is formed between two of said plurality of sub-electrodes supplied alternately with said first focus voltage and said second focus voltage, two of said plurality of sub-electrodes are supplied with said second focus voltage; and said G4 electrode, said G5 electrode and said phosphor screen satisfy the following inequalities: 0.0625Ã—L (mm)&lE;Bâˆ’20A/(3&phgr;)&lE;22.0 mm, andL (mm)&lE;352 mm where A (mm) is an axial length of said G4 electrode, &phgr; (mm) is an average of horizontal and vertical diameters of an electron-beam aperture for a center electron beam of said three electron beams in said G4 electrode, B (mm) is an axial length measured from a cathode side end of said G5 electrode to a phosphor screen side end of said G5 electrode, and L (mm) is an axial distance from said phosphor screen side end of said G5 electrode to a center of said phosphor screen.