US 4,088,930 A · Color television display device including a cathode-ray tube

Abstract

A color televison display device including a cathode-ray tube whose neck supports a system of deflection coils which causes isotropic astigmatic errors upon deflection. This is eliminated with the aid of a quadripolar field to which end four windings are wound preferably as four toroid windings on the core of the deflection coil system at the area of the deflection plane. The windings are arranged pairwise opposite to each other and this in such a manner that two windings are exactly located in the gaps of the field deflection coils and the two other windings are shifted 90.degree. in the tangential direction. Parabola currents which may have the line frequency and/or the field frequency must flow through the four windings. However, it is alternatively possible to replace the four windings by two each (thus a total of 8) in which a parabola current proportional to the line frequency flows through one pair of four windings and a parabola current proportional to the field frequency flows through the other pair of four windings.

Claims15

Dependent claims

A circuit for a color television display tube, said circuit comprising first and second deflection coil units adapted to receive respective deflection currents, each unit having two symmetrical coil halves which are arranged opposite to each other and defining a pair of places therebetween wherein said windings have at least a reduced winding density, the first unit being disposed 90.degree. in the tangential direction relative to the second unit, said units being disposed around the neck of the cathode-ray tube for deflecting at least one electron beam generated in the cathode-ray tube into two orthogonal directions when the respective deflection current flows through each coil unit;

means for correcting distortion including at least four windings disposed tangentially relative to one another at an angle of approximately 90.degree. near said places respectively, switching means coupled to said windings for applying a correction current through the four windings, means coupled to said switching means for generating said correction current in accordance with the deflection current flowing through at least the first deflection coil unit, whereby the windings generate a quadripolar field which is in accordance with said deflection current at the area of the deflection plane of the electron beam.

An in-line gun type color television picture tube apparatus comprising:

a. an in-line gun type color cathode-ray tube in which three electron guns are arranged in a line along a first axis and the spots of electron beams from these electron guns appear along the first axis on the screen of the cathode-ray tube and are converged at the center of the screen,
b. a deflection yoke which deflects and scans the electron beams so that both side spots of the three electron beams appear on the screen at an equal distance on both sides of the center spot when the three electron beams are not converged,
c. a convergence magnetic field generating means, said convergence magnetic field generating means consisting essentially of at least one pair of convergence windings which are respectively provided externally on the neck of said cathode-ray tube and are opposite from each other in reference to the axis of the cathode-ray tube and a convergence power supply which supplies the convergence current to said windings which forms said convergence magnetic field generating means forming a convergence magnetic field which shifts only said side electron beams and has a field distribution which is symetrical and linear in reference to a second and third axis, said second and third axes being positioned 90.degree. with respect to each other and 45.degree. with respect to said first axis, the plane formed by said second and third axes being perpendicular to the axis of the cathode-ray tube, wherein both side electron beams are symmetrically shifted in reference to the center electron beam, as a function of the deflection angle, in order to complete convergence of the beam spot trio through said convergence magnetic field.

Dependencies are inferred from the claim text.

Color television display device including a cathode-ray tube

Life of this patent

Color television display device including a cathode-ray tube

Life of this patent

Abstract

Claims15