Patent ID: 6404116
Filing Date: 2002-06-11
Classification: H01J

Abstract:
A color cathode ray tube including a vacuum envelope which is comprised of a panel portion constituting a phosphor screen, a neck portion accommodating an electron gun and a funnel portion connecting the panel portion and the neck portion,wherein said electron gun is an in-line type electron gun which includes electron beam generating means comprising cathodes irradiating three electron beams approximately in parallel toward said phosphor screen on one horizontal plane, a control electrode and an accelerating electrode, a focusing electrode having a single opening whose diameter in the direction parallel to said horizontal plane is greater than a diameter thereof in the direction perpendicular to said horizontal plane so as to allow said three electron beams to pass therethrough, said focusing electrode having a plate electrode provided with three electron beam apertures which allow said respective electron beams to pass therethrough therein, said focusing electrode being applied with a focusing voltage, an anode having a single opening whose diameter in the direction parallel to said horizontal plane is greater than a diameter thereof in the direction perpendicular to said horizontal plane so as to allow said three electron beams to pass therethrough, said anode having a plate electrode provided with a single electron beam aperture which allows a center beam of said three electron beams to pass therethrough therein, said anode constituting a main lens on a surface thereof which faces said focusing electrode, said anode being applied with an anode voltage, and at least one intermediate electrode being disposed between said focusing electrode and said anode, said intermediate electrode having a single opening whose diameter in the direction parallel to said horizontal plane is greater than a diameter thereof in the direction perpendicular to said horizontal plane so as to allow said three electron beams to pass therethrough, said intermediate electrode having a plate electrode provided with three electron beam apertures which allow said respective three electron beams to pass therethrough therein, said intermediate electrode being applied with a middle voltage which takes a value between said focusing voltage and said anode voltage, and when a length which is obtained by adding diameters in the horizontal direction of said three electron beam apertures and lengths in the horizontal direction of bridges disposed between neighboring electron beam apertures of said plate electrode mounted in the inside of said focusing electrode is set as Lc, and a length which is obtained by adding diameters in the horizontal direction of three electron beam apertures and lengths in the horizontal direction of bridges disposed between neighboring electron beam apertures of said plate electrode mounted in the inside of said intermediate electrode is set as Lm, the relationship between Lc and Lm is set to Lc>Lm.