Abstract: The coils of an astigmatism corrector for an electron beam of a cathode ray tube are positioned on a flexible support. The support is disposed around the neck of the tube and positioned at least partially adjacent the back part of at least one pair of deflection coils, so as to reduce interaction of the fields produced by the astigmatism corrector with the elements of the electron gun.

Abstract: 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.

Abstract: A main deflection device of a cathode ray tube generates a main deflection field to deflect an electron beam on the screen of the tube. An auxiliary deflection device located between the main deflection device and the envelope of the tube generates a corrective deflection field to correct geometry errors, for example. The auxiliary deflection device includes a ring core that has a plurality of inwardly pointing projections along the ring and a plurality of associated coils that generate the corrective field. A plurality of adjustable impedances parallels the coils.

Abstract: 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.

Abstract: The deflecting yoke for a cathode-ray tube of the invention includes a magnetic circuit enveloping the back flares of the deflecting coils, which are folded down into the extension of the central parts of these coils. The end of the back part of the magnetic circuit extends radially inwards until it substantially makes contact with a neck portion of the cathode-ray tube.