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US 3,942,067 AGranted
Multi-gun cathode ray tube convergence system
AssigneeGeneral Electric Company
InventorGeorge H. Cawood
Life of this patent
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AssigneeGeneral Electric Company
InventorGeorge H. Cawood
Estimating the term…
The beams from a plurality of off-axis guns aimed through a common deflection volume, as used in shadow-mask color cathode-ray tubes, even if made by constant convergence fields to converge at a given distance in the absence of deflection, will diverge when a common deflection field is applied; and the distance from the deflection zone to different parts of the screen is generally not constant. Therefore the convergence field applied to each must vary as the beams are deflected to different screen areas. Prior art schemes to do this have employed functions of the form AY + BY.sup.2 + CX + DX.sup.2, where Y is the vertical deflection and X is the horizontal deflection. The present invention produces a function AY + BY.sup.2 + CX + DX.sup.2 + EXY, or alternatively this function plus FY.sub.+.sup.3 where Y.sub.+ is only the positive value of Y. The square and cube functions are produced by the use of multiplier circuits.
A convergence circuit for a three-gun color cathode-ray tube comprising:
In a convergence circuit for a multi-gun cathode-ray tube comprising means for providing a correction circuit of the form AY + BY.sup.2 + CX + DX.sup.2 + EXY, where X and Y are proportional to the horizontal and vertical deflection magnitudes, respectively, and A, B, C, D, and E are constants, the improvement comprising means for providing in the correction current a further component FY(positive).sup.3 where F is a constant and Y(positive).sup.3 is the cube of only the positive values of Y.
Dependencies are inferred from the claim text.