Videocolor

Thomson Tubes & Displays, S.a.

Alain Dumesnil

Bruno F Roussel

Bruno Roussel

Jean-Marc Perreaut

A deflection device for a cathode-ray tube with three coplanar guns, comprising a pair of horizontal deflection coils and a pair of vertical deflection coils, each horizontal deflection coil having a main deflection winding extending over the length of the deflection device, and an auxiliary deflection winding. Each main deflection winding has a front portion and a rear portion. The auxiliary deflection winding is disposed in the front portion of the main deflection winding and is arranged to generate a magnetic field opposed to a field of the main deflection winding. Each of the auxiliary windings has conductors arranged laterally about a mean angle from a horizontal deflection axis, the mean angle varying as a function of the position of the conductors along a longitudinal axis of the deflection device such that, in the front portion of each of the main deflection windings of the pair of horizontal deflection coils, an amplitude of the third-order harmonic of the Fourier series decomposition of the angular distribution of the ampere-turn density is substantially equal to or greater than that of the fundamental.

Electron beam deflection device for cathode ray tubes which is self

A deflection yoke includes a first core portion and a core extension portion. The core extension portion is located in the rear of the yoke closer to the beam entrance region. To adjust the yoke for the particular cathode ray tube on which it is mounted, the position of the yoke is adjusted for obtaining acceptable image geometry. Then, the core extension is moved with respect to the first core portion in a direction perpendicular to the longitudinal axis of the tube to obtain convergence symmetry while the position of the first core portion remains the same. In this way, convergence symmetry adjustment is accomplished separately from image geometry adjustment.

Deflection yoke with a core extension

A magnetic deflector of the saddle-saddle type, for a trichromatic tube protected by a shield, with in-line guns and round-luminophor type screen, is designed to function with a saddle-torus type of magnetic deflector. The invention uses a saddle-saddle type of deflector in which the front leading-out wires have been reduced and the rear leading-out wires are laid flat. Furthermore, the ferrite piece is extended by a ring which surrounds the rear leading-out wires and is magneticlaly closed by a ferrite ring bearing a quadrupole coil powered by a parabolic current. The intention can be applied to round-luminiphor trichromatic tubes fitted with an external shield.

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Genlis, France

Alain Dumesnil