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US 4,772,827 AGranted
Cathode ray tube
AssigneeHitachi, Ltd.
InventorKuniharu Osakabe
Life of this patent
Estimating the term…
Abstract
At least one of the focusing electrodes stages disposed between an acceleration electrodes stage and a rear focusing electrodes stage is constituted by first and second grid electrodes, confronting portions thereof having asymmetrical construction with respect to an electron beam axis. A constant focusing voltage is applied to the first grid electrode, and a dynamic focusing voltage gradually increasing or decreasing from the constant focusing voltage as the degree of beam deflection increases is applied to the second grid electrode.
Claims3
A cathode ray tube comprising:
- a plurality of electron guns disposed in a neck portion of a glass envelope of said cathode ray tube, each of said electron guns including
- a cathode electrodes stage,
- a front focusing electrodes stage, and
- a rear focusing electrodes stage, said stages being sequentially disposed in a direction of an axis of said cathode ray tube,
- said first focusing electrodes stage including
- a first focusing electrode,
- a second focusing electrode comprising of a first grid electrode and a second grid electrode, and
- a third grid electrode disposed between said first and second focusing electrodes;
- means for applying a constant focusing voltage to said first focusing electrode and said first grid electrode;
- means for applying to said second grid electrode a dynamic voltage superimposed on said constant voltage which dynamic focusing voltage gradually varies as a function of the deflection of an electron beam so as to asymmetrically converge the electron beam to produce substantially the same beam spot configuration on said tube for any deflection of said beam;
- and
- means for applying a high voltage to said third grid electrode and said rear focusing electrodes stage.
9 more elements
Dependencies are inferred from the claim text.