# US 5,710,480 A · Color cathode ray tube having a small neck diameter > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 5,710,480 A - Document ID: US5710480A - Status: Granted - Kind: A - Application number: 08/580,529 - Filed: 1995-12-28 - Granted: 1998-01-20 - Earliest claimed: 1995-01-09 - Assignees: Hitachi, Ltd. - Inventors: Go Uchida; Shoji Shirai; Kazuhisa Oshita - Web page: https://patentgrep.com/patent/US5710480A ## CPC - H01J 29/503: {Three or more guns, the axes of which lay in a common plane} - H01J 2229/4841: Dynamic potentials - H01J: ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS (spark-gaps H01T; electric arc lamps H05B31/00; particle accelerators H05H) ## Abstract A color cathode ray tube has an evacuated envelope including a panel portion having a phosphor screen and a neck portion, and an in-line electron gun including a main lens and an electrostatic quadrupole lens and housed in the neck portion. The focus electrode of the main lens has a single opening at its one end for the three electron beams. The single opening has a diameter larger in a horizontal direction than that in a vertical direction. A distance from the main lens to the phosphor screen is not larger than 300 mm, an outer diameter T of the neck portion satisfies the following inequality: 23.2 mm.ltoreq.T.ltoreq.25.9 mm, and a value D of twice a distance from the side electron beams to a vertical edge of the single opening satisfies the following inequality: 5.0 mm.ltoreq.D.ltoreq.6.5 mm. ## Claims ### Claim 1 A cathode ray tube comprising at least an evacuated envelope comprising a panel portion having a phosphor screen on an inner surface thereof, a neck portion, a funnel portion connecting said panel portion and said neck portion, a deflection device mounted in a vicinity of a transition region between said funnel portion and said neck portion, and an in-line electron gun housed in said neck portion, said in-line electron gun including an electron beam generating section comprising at least a cathode, a control electrode and an accelerating electrode and for generating and directing three electron beams in a horizontal plane toward said phosphor screen, a main lens section comprising a focus electrode including a sub-electrode having a single opening at one end thereof for passing the three electron beams, said single opening having a diameter larger in a horizontal direction than a diameter thereof in a vertical direction, and a plate electrode placed inside said sub-electrode and forming apertures for passing the three electron beams respectively, an anode facing said one end of said sub-electrode, said sub-electrode and said anode forming a main lens therebetween, and an electrostatic quadrupole lens, a lens strength thereof being varied with application thereon of a voltage varying with an increase in a deflection angle of the three electron beams, wherein a distance from said main lens to said phosphor screen is not larger than 300 mm, an outer diameter T of said neck portion housing the in-line electron gun satisfies a following inequality: 23. 2 mm.ltoreq.T.ltoreq.25.9 mm, and a value D of twice a distance from a center of a trajectory of a side electron beam of the three electron beams to a vertical edge of said single opening satisfies a following inequality: 5.0 mm.ltoreq.D.ltoreq.6.5 mm. ### Claim 2 (depends on 1) A cathode ray tube according to claim 1, wherein said cathode ray tube further comprises a shadow mask suspended within said panel portion, and wherein a dot pitch of apertures in said shadow mask is not larger than 0.28 mm. ### Claim 3 (depends on 1) A cathode ray tube according to claim 1, wherein a spacing S between centers of adjacent electron beams of said three electron beams satisfies the following inequality: 4.6 mm.ltoreq.S.ltoreq.5.2 mm. ### Claim 4 (depends on 1) A cathode ray tube according to claim 1, wherein an electrode rim width L1 measured from said vertical edge of said single opening to a vertical outside surface on said vertical edge side of said sub-electrode satisfies the following inequality: 1.0 mm.ltoreq.L1.ltoreq.1.5 mm. ### Claim 5 (depends on 1) A cathode ray tube according to claim 1, wherein a distance L2 measured from a vertical outside surface of said sub-electrode to an inner surface of said neck portion facing said vertical outside surface satisfies the following inequality: 1.0 mm.ltoreq.L2.ltoreq.1.3 mm. ### Claim 6 (depends on 1) A cathode ray tube according to claim 1, wherein said main lens is configured to provide a beam spot having a diameter BS at a center of said phosphor screen, said beam spot diameter BS satisfying the following inequality: 0.45.ltoreq.BS.ltoreq.0.5. ### Claim 7 A cathode ray tube comprising at least an evacuated envelope comprising a panel portion having a phosphor screen on an inner surface thereof, a neck portion, a funnel portion connecting said panel portion and said neck portion, a deflection device mounted in a vicinity of a transition region between said funnel portion and said neck portion, and an in-line electron gun housed in said neck portion, said in-line electron gun including an electron beam generating section comprising at least a cathode, a control electrode and an accelerating electrode and for generating and directing three electron beams in a horizontal plane toward said phosphor screen, a main lens section comprising a focus electrode including a sub-electrode having a single opening at one end thereof for passing the three electron beams, said single opening having a diameter larger in a horizontal direction than a diameter thereof in a vertical direction, and a plate electrode placed inside said sub-electrode and forming apertures for passing the three electron beams respectively, an anode facing said one end of said sub-electrode, said sub-electrode and said anode forming a main lens therebetween, and an electrostatic quadrupole lens, a lens strength thereof being varied with application thereon of a voltage varying with an increase in a deflection angle of the three electron beams, wherein a distance from said main lens to said phosphor screen is not larger than 300 mm, an outer diameter T of said neck portion housing said in-line electron gun and a value D of twice a distance from a center of a trajectory of a side electron beam of the three electron beams to a vertical edge of said single opening satisfy following inequalities: D+18.2 mm.ltoreq.T.ltoreq.D+19.4 mm, and 5. 0 mm.ltoreq.D.ltoreq.6.5 mm. ### Claim 8 (depends on 7) A cathode ray tube according to claim 7, wherein said cathode ray tube further comprises a shadow mask suspended within said panel portion, and wherein a dot pitch of apertures in said shadow mask is not larger than 0.28 mm. ### Claim 9 (depends on 7) A cathode ray tube according to claim 7, wherein a spacing S between centers of adjacent electron beams of said three electron beams satisfies the following inequality: 4.6 mm.ltoreq.S.ltoreq.5.2 mm. 10. ### Claim 10 (depends on 7) A cathode ray tube according to claim 7, wherein an electrode rim width L1 measured from said vertical edge of said single opening to a vertical outside surface on said vertical edge side of said sub-electrode satisfies the following inequality: 1.0 mm.ltoreq.L1.ltoreq.1.5 mm. ### Claim 11 (depends on 7) A cathode ray tube according to claim 7, wherein a distance L2 measured from a vertical outside surface of said sub-electrode to an inner surface of said neck portion facing said vertical outside surface satisfies the following inequality: 1.0 mm.ltoreq.L2.ltoreq.1.3 mm. ### Claim 12 (depends on 7) A cathode ray tube according to claim 7, wherein said main lens is configured to provide a beam spot having a diameter BS at a center of said phosphor screen, said beam spot diameter BS satisfying the following inequality: 0.45.ltoreq.BS.ltoreq.0.5.