Patent ID: 6225765
Filing Date: 2001-05-01
Classification: H01J

Abstract:
A color cathode ray tube comprisingan evacuated envelope comprising 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, anda 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, andan 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,at least one lens for correcting curvature of the image field is formed between two of said plurality of sub-electrodes supplied alternately with said first focus voltage and said second focus voltage,said G4 electrode, said G5 electrode and said phosphor screen satisfy following inequalities:0.0625.times.L(mm).ltoreq.B-20A/(3.phi.).ltoreq.22.0 mm,andL(mm).ltoreq.352 mmwhere A(mm) is an axial length of said G4 electrode,.phi.(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, andL(mm) is an axial distance from said phosphor screen side end of said G5 electrode to a center of said phosphor screen.