Color cathode-ray tube having electrostatic quadrupole lens exhibiting different intensities for electron beams

• US 6,400,105 B2
• Filed: 04/27/1998
• Issued: 06/04/2002
• Est. Priority Date: 09/05/1997
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Kato, Shinichi, Nagaoka, Masafumi, Shirai, Syoji, Uchida, Go
• Primary Examiner(s): Hannaher, Constantine
• Assistant Examiner(s): LEE, SHUN K
• Application Number:
  US09/066,756
• Publication Number:
  US 20010013760A1
• Time in Patent Office: 1,499 Days
• Field of Search: 315/382, 315/368, 313/382, 313/449, 313/414
• US Class Current: 315/382
• CPC Class Codes: H01J 2229/4841 Dynamic potentials
• CPC Class Codes: H01J 2229/4879 non-symmetric about field scanning axis
• CPC Class Codes: H01J 29/503 Three or more guns, the axes of which lay in a common plane

Abstract

A focus electrode is constituted by a first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied. Between the first type of focus electrode group and the second type of focus electrode group are formed a lens at least having a lens action for correcting the field curvature and an electrostatic quadrupole lens. The center axes of the outer electron beam passage holes in the first type of focus electrode forming the lens at least having a lens action for correcting the field curvature are deviated on a horizontal plane from the center axes of the outer electron beam passage holes in the second type of focus electrode. The electrostatic quadrupole lens produces dissimilar intensities for the outer electron beams and for the center electron beam. Therefore, the outer electron beam passage holes work to deflect the outer electron beams toward the center electron beam with an increase in the deflecting amount of the electron beams, and a favorable resolution is obtained on the whole screen of the cathode-ray tube.

Claims

1. A color cathode-ray tube comprising at least 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, an in-line type electron gun housed in said neck portion, and a deflection yoke for scanning electron beams on the phosphor screen;

wherein said electron gun has a cathode, a control electrode, an accelerating electrode and a main lens section disposed in the recited order in a direction toward said phosphor screen;

said main lens section comprising an anode to which an anode voltage is applied, and a focus electrode,

said focus electrode having a first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied;

said second focus voltage is obtained by superposing a voltage, that changes depending upon the deflecting amount of the electron beams, on a predetermined voltage;

between the first type of focus electrode group and the second type of focus electrode group are formed at least two electron lenses including a lens for correcting the field curvature for focusing the electron beams in both the horizontal direction and the vertical direction, and an electrostatic quadrupole lens for focusing said electron beams in either the horizontal direction or the vertical direction and for diverging the electron beams in the other of said directions;

three electron beam passage holes are formed in the electrodes that form said lens for correcting the field curvature, and the centers of the outer electron beam passage holes in the first type of focus electrode group are deviated relative to the centers of the outer electron beam passage holes in the second type of focus electrode group in the horizontal direction; and

said electrostatic quadrupole lens exhibits different intensities for the outer electron beams relative to the center electron beam.

2. A color cathode-ray tube according to claim 1, wherein the centers of said outer electron beam passage holes in the first type of focus electrode forming the lens for correcting the field curvature are deviated toward the center electron beam relative to the centers of the outer electron beam passage holes in the second type of focus electrode;

and

said electrostatic quadrupole lens exhibits a stronger intensity for the outer electron beams than for the center electron beam.

3. A color cathode-ray tube according to claim 2, wherein the anode forming a portion of said main lens section in said electron gun and an electrode belonging to said second type focus electrode group which neighbors said anode, have electron beam passage holes through which the three electron beams arranged in said horizontal direction pass, and the centers of the outer electron beam passage holes in said anode are deviated on a horizontal plane relative to the centers of said outer electron beam passage holes in the electrode belonging to said second type of focus electrode group.

4. A color cathode-ray tube according to claim 2, wherein said accelerating electrode neighbors said first type of focus electrode, said accelerating electrode and said first type of focus electrode, respectively, have electron beam passage holes through which the three electron beams arranged in the horizontal direction pass, and the centers of the outer electron beam passage holes in said first type of focus electrode are deviated on a horizontal plane relative to the centers of the outer electron beam passage holes in said accelerating electrode.

5. A color cathode-ray tube according to claim 2, wherein said electrostatic quadrupole lens for the outer electron beams produces a stronger diverging action in the horizontal direction than said electrostatic quadruple lens for the center electron beam.

6. A color cathode-ray tube according to claim 1, wherein the centers of the outer electron beam passage holes in the second type of focus electrode forming the lens for correcting the field curvature are deviated toward a direction opposite to the center electron beam relative to the centers of the outer electron beam passage holes in the first type of focus electrode;

and

said electrostatic quadrupole lens exhibits a weaker action for the outer electron beams than for the center electron beam.

7. A color cathode-ray tube according to claim 6, wherein said anode forming a portion of the main lens section of said electron gun and the second type of focus electrode neighboring said anode, respectively, have electron beam passage holes through which the three electron beams arranged in the horizontal direction pass, and the centers of the outer electron beam passage holes in said anode are deviated on a horizontal plane relative to the centers of the outer electron beam passage holes in said second type of focus electrode.

8. A color cathode-ray tube according to claim 6, wherein said accelerating electrode neighbors said first type of focus electrode, said accelerating electrode and said first type of focus electrode, respectively, have electron beam passage holes through which the three electron beams arranged in the horizontal direction pass, and the centers of the outer electron beam passage holes in said first type of focus electrode are deviated on a horizontal plane relative to the centers of said outer electron beam passage holes in said accelerating electrode.

9. A color cathode-ray tube according to claim 6, wherein said electrostatic quadrupole lens for the outer electron beams produces a weaker diverging action in the horizontal direction than said electrostatic quadrupole lens for the center electron beam.

10. A color cathode-ray tube comprising at least 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, an in-line type electron gun housed in said neck portion, and a deflection yoke for scanning electron beams on the phosphor screen;

wherein said electron gun has a cathode, a control electrode, an accelerating electrode and a main lens section disposed in the recited order in a direction toward said phosphor screen;

said main lens section comprising an anode to which an anode voltage is applied, and a focus electrode;

said focus electrode having a first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied;

said second focus voltage is obtained by superposing a voltage, that changes depending upon the deflecting amount of the electron beams, on a predetermined voltage;

between the first type of focus electrode group and the second type of focus electrode group are formed at least two electron lenses including a lens at least having a lens action for correcting the field curvature for focusing the electron beams in both the horizontal direction and the vertical direction, and an electrostatic quadrupole lens for focusing said electron beams in either the horizontal direction or the vertical direction and for diverging the electron beams in the other of said directions;

three electron beam passage holes are formed in the electrodes that form said lens at least having a lens action for correcting the field curvature, and the horizontal diameter of the outer electron beam passage holes in the first type of focus electrode is larger than the horizontal diameter of the outer electron beam passage holes in the second type of focus electrode; and

said electrostatic quadrupole lens exhibits different intensities for the outer electron beams relative to the center electron beam.

11. A color cathode-ray tube according to claim 10, wherein said anode forming a portion of said main lens section in said electron gun and an electrode belonging to said second type of focus electrode group neighboring said anode, have electron beam passage holes through which the three electron beams arranged in said horizontal direction pass, and the centers of the outer electron beam passage holes in said anode are deviated on a horizontal plane relative to the centers of said outer electron beam passage holes in said second type of focus electrode group.

12. A color cathode-ray tube according to claim 10, wherein said accelerating electrode neighbors said first type of focus electrode, said accelerating electrode and said first type of focus electrode, respectively, have electron beam passage holes through which the three electron beams arranged in the horizontal direction pass, and the centers of the outer electron beam passage holes in said first type of focus electrode are deviated on a horizontal plane relative to the centers of the outer electron beam passage holes in said accelerating electrode.

13. A color cathode-ray tube according to claim 10, wherein said electrostatic quadrupole lens for the outer electron beams produces a stronger diverging action in the horizontal direction than said electrostatic quadrupole lens for the center electron beam.

14. A color cathode-ray tube according to claim 10, wherein among the three electron beam passage holes formed in the first type of focus electrode and in the second type of focus electrode forming the lens at least having a lens action for correcting the field curvature, the outer electron beam passage holes formed in the first type of focus electrode have a vertical diameter which is equal to a vertical diameter of the outer electron beam passage holes formed in the second type of focus electrode, and said electrostatic quadrupole lens exhibits a stronger action for the outer electron beams than for the center electron beam.

15. A color cathode-ray tube comprising at least 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, an in-line type electron gun housed in said neck portion, and a deflection yoke for scanning electron beams on the phosphor screen;

wherein said electron gun has a cathode, a control electrode, an accelerating electrode and a main lens section disposed in the recited order in a direction toward said phosphor screen;

said main lens section comprising an anode to which an anode voltage is applied, and a focus electrode;

said focus electrode having first type of focus electrode group to which a first focus voltage is applied, and a second type of focus electrode group to which a second focus voltage is applied;

said second focus voltage is obtained by superposing a voltage, that changes depending upon the deflecting amount of the electron beams, on a predetermined voltage;

between the first type of focus electrode group and the second type of focus electrode group are formed at least two electron lenses including a lens at least having a lens action for correcting the field curvature for focusing the electron beams in both the horizontal direction and the vertical direction, and an electrostatic quadrupole lens for focusing said electron beams in either the horizontal direction or the vertical direction and for diverging the electron beams in the other of said directions;

three electron beam passage holes are formed in the electrodes that form said lens at least having a lens action for correcting the field curvature, and the horizontal diameter of the outer electron beam passage holes in the first type of focus electrode is smaller than the horizontal diameter of the outer electron beam passage holes in the second type of focus electrode; and

said electrostatic quadrupole lens exhibits different intensities for the outer electron beams relative to the center electron beam.

16. A color cathode-ray tube according to claim 15, wherein said anode forming a portion of said main lens section in said electron gun and the second type of focus electrode neighboring said anode, have electron beam passage holes through which the three electron beams arranged in said horizontal direction pass, and the centers of the outer electron beam passage holes in said anode are deviated on a horizontal plane relative to the centers of said outer electron beam passage holes in said second type of focus electrode group.

17. A color cathode-ray tube according to claim 15, wherein said accelerating electrode neighbors said first type of focus electrode, said accelerating electrode and said first type of focus electrode, respectively, have electron beam passage holes through which the three electron beams arranged in the horizontal direction pass, and the centers of the outer electron beam passage holes in said first type of focus electrode are deviated on a horizontal plane relative to the centers of the outer electron beam passage holes in said accelerating electrode.

18. A color cathode-ray tube according to claim 15, wherein said electrostatic quadrupole lens for the outer electron beams produces a weaker diverging action in the horizontal direction than said electrostatic quadrupole lens for the center electron beam.

19. A color cathode-ray tube according to claim 15, wherein among the three electron beam passage holes formed in the first type of focus electrode and in the second type of focus electrode forming the lens at least having a lens action for correcting the field curvature, the outer electron beam passage holes formed in the first type of focus electrode have a vertical diameter which is equal to a vertical diameter of the outer electron beam passage holes formed in the second type of focus electrode, and said electrostatic quadrupole lens exhibits a weaker action for the outer electron beams than for the center electron beam.