Hitachi, Ltd.

Masafumi Nagaoka

Shinichi Kato

Go Uchida

Syoji Shirai

Shoji Shirai

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.

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

A color cathode-ray tube including a main lens section comprising an anode to which an anode voltage is applied, and a focus electrode. The focus electrode has 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 which is obtained by superposing on a predetermined voltage a voltage that changes depending upon the deflecting amount of the electron beams. Between the first type of focus electrode group and the second type of focus electrode group are formed in a dynamic lens and an electrostatic quadrupole lens. Three electron beam passage holes are formed in the electrodes that form the dynamic lens and the centers for 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. The electrostatic quadrupole lens exhibits different intensities for the outer electron beams relative to the center electron beam.

Color cathode-ray tube

A color cathode ray tube includes a phosphor screen, an electron beam generating section for generating three in-line electron beams, a focus electrode and an anode. The focus electrode includes a first focus and second focus sub-electrodes on this order from the cathode structure. The first focus sub-electrode has plural vertical parallel plate-like electrodes arranged to sandwich respective beam apertures in an end thereof facing the second focus sub-electrode in a direction of a beam arrangement, and the second focus sub-electrode has plural horizontal parallel plate-like electrodes arranged to sandwich beam apertures in an end thereof facing the first focus sub-electrode in a direction perpendicular to the beam arrangement, one of the first and second focus sub-electrodes is adapted to be supplied with a voltage varying in synchronism with beam deflection. The vertical parallel plate-like electrodes extend into a space defined by the horizontal parallel plate-like electrodes, and a vertical spacing V between the horizontal parallel plate-like electrodes and a gap L between the horizontal parallel plate-like electrodes and the edges of the vertical parallel plate-like electrodes satisfy 0.38&lE;L/(V/2)&lE;0.58.

Color cathode ray tube having a low-distortion electrostatic quadrupole lens with a plurality of first and second electrodes having specified spacing relationships

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Mobara, Japan

Masafumi Nagaoka