Thomson Tubes & Displays, S.a.

Videocolor, S.a.

Didier Thibaudin

Bruno F Roussel

Jean M Perreaut

Bruno Roussel

A focusing unit for a cathode ray tube comprises a plurality of permanent magnets, each having a longitudinal axis, and a plurality of coils. A form holds the magnets in a first annular array at substantially equally spaced intervals in which the magnet axes are substantially parallel to a longitudinal axis defined by the first annular array and holds the coils in a second annular array at positions spaced angularly between the magnets. Annular flanges of high magnetic permeability are disposed over longitudinally opposite ends of the magnets. At least one annular winding is disposed substantially adjacent to and inwardly from the first array of the magnets. In one embodiment, the coils are helical coils disposed in substantial circumferential alignment with the first annular array of the magnets. The helical coils each having a substantially is radially aligned longitudinal axis. In another embodiment, the plurality of coils are spaced radially between the first array of the magnets and the at least one annular winding. Each of these coils defines a substantially radially aligned longitudinal axis. In each embodiment, the plurality of coils of the second array are coupled in two interleaved sets for generating two quadripole focusing fields for correcting astigmatic aberrations of an electron beam in the cathode ray tube.

Permanent magnet focus unit with integral astigmatism corrector

A deflection coil system for a picture tube has a primary deflection coil and an auxiliary deflection coil. The primary and auxiliary deflection coils are each operable to produce a respective magnetic field having a first polarity within a region defined by the coil and an opposite polarity in a second region. Each of the two coils is arranged such that part of the positive polarity field of each coil and all of its opposite polarity field, are in each case coupled to the other coil. This cancels the effects of cross coupling of the primary and auxiliary deflection coils, which are placed in proximity to each other on the same axis, for example on the neck and envelope of a television display tube. At least one of the primary and auxiliary deflection coils may be a saddle shaped deflection coil and has a flat end turn section, substantially defining the opposite polarity area. The primary and auxiliary deflection coils are overlapped on the tube over at least part of this end turn section.

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Genlis, France

Didier Thibaudin