Colour television display apparatus provided with a cathode-ray tube

Claim 1

Colour television display apparatus provided with a cathoderay tube having a display screen and a system of deflection coils comprising a magnetic core on which a first and a second deflection coil unit are provided, each unit comprising two preferably symmetrical coil halves, said deflection coil system being slid on the neck of the cathode-ray tube for deflecting at least one electron beam generated in the cathode-ray tube in two substantially orthogonal directions because a deflection current originating from a deflection current generator flows through each coil half, the apparatus furthermore being provided with at least one correction current generator for supplying a correction current in at least one deflection coil unit for generating a quadripolar field approximately at the area of the deflection plane of the electron beam, characterized in that a second quadripolar field is generated approximately at the area of the deflection plane of the electron beam by a second correction current induced in the coil halves of the second deflection coil unit by the correction current flowing in the coil halves of the first deflection coil unit, the voltage produced by the second correction current across each coil half of the second deflection coil unit being substantially zero, and the deflection coil halves being toroidally wound on the core.

Claim 9

An apparatus for a cathode-ray tube having a display screen and a system of deflection coils comprising a magnetic core on which a first and a second deflection coil unit are provided, each unit comprising two preferably symmetrical toriodal coil halves, said deflection coil system being on the neck of the cathode-ray tube for deflecting at a deflection plane at least one electron beam generated in the cathode-ray tube in two substantially orthogonal directions; said apparatus comprising a deflection current generator means for supplying to each coil half a deflection current, at least one correction current generator means for supplying a first correction current to said first deflection coil unit and for generating a first quadripolar field approximately at the area of said deflection plane of the electron beam, and means for generating a second quadripolar field approximately at the area of the deflection plane of the electron beam by a second correction current induced in the coil halves of the second deflection coil unit by said first correction current flowing in the coil halves of the first deflection coil unit and for providing that the voltage produced by the second correction current across each coil half of the second deflection coil unit is substantially zero.

Claim 10

An apparatus for a cathode-ray tube having a display screen and a system of deflection coils comprising a magnetic core on which a first and a second deflection coil unit are provided, each unit comprising two preferably symmetrical toriodal coil halves, said deflection coil system being on the neck of the cathode-ray tube for deflecting at a deflection plane at least one electron beam generated in the cathode-ray tube in two substantially orthogonal directions; said apparatus comprising a deflection current generator means for supplying to each coil half a deflection current, at least one correction current generator means for supplying a first correction current to said first deflection coil unit and for generating a first quadripolar field approximately at the area of said deflection plane of the electron beam, and means for generating a second quadripolar field approximately at the area of the deflection plane of the electron beam by a second correction current induced in the coil halves of the second deflection coil unit by said first correction current flowing in the coil halves of the first deflection coil unit and for providing that the voltage produced by the second correction current across each coil half of the second deflection coil unit is substantially zero.