Abstract: 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.

Abstract: In a deflection yoke four Gorner magnets are used for correcting inner north-south raster distortion. The north-south axis of each of the comer magnets is disposed in parallel to the Z-axis.

Abstract: An improved color picture tube includes a screen and an inline gun for generating and directing three inline electron beams along separate paths toward the screen. The electron gun includes electrodes that provide a beam-forming region, a prefocus region and a main focus region. The beam-forming region of the gun includes a cathode, a G1 electrode, a G2 electrode and a first portion of a G3 electrode. The prefocus region includes a second portion of the G3 electrode, a G4 electrode and a first portion of a G5 electrode. The main focus region includes a second portion of the G5 electrode and a G6 electrode. The improvement resides in the beam-forming region, the prefocus region and the main focus region each being astigmatic.

Abstract: A self converging, widescreen color picture tube system includes a widescreen, in-line color picture tube having a funnel, an electron gun assembly (28) for three in-line electron beams located in a neck at one end of the picture tube, and a faceplate with a viewing screen at the other end. The picture tube has a wide aspect ratio. A self converging widescreen deflection yoke (40) for deflecting the electron beams in the wide aspect ratio picture tube includes horizontal and vertical deflection windings. The yoke (40) is located by an initial flare section of the funnel and positioned along the longitudinal axis of the picture tube to make the tube reference line and the yoke deflection plane substantially coincident. To achieve substantial horizontal astigmatism correction at the extremes of the major axis of the wide viewing screen, the horizontal deflection winding is constructed to have a generally pincushion-shaped horizontal deflection field over the effective length of the field.

Abstract: A pair of E-shaped shunts are disposed near the top and bottom, respectively, of a deflection yoke for reducing inner and outer horizontal trap errors. A central portion of the E-shaped shunt reduces a ratio between magnitudes of inner and outer E-W pincushion raster distortions.

Abstract: A magnetic focusing device is disposed around the neck of a cathode ray tube. The device comprises a magnetic frame formed by constituent pieces having different magnetic permeabilities and having a gap in a portion thereof radially closest to the neck. A static focusing coil is enclosed in the frame and energized by a direct current. A dynamic focusing coil is energized by a periodically variable current and disposed between the static coil and the neck of the tube. The dynamic focusing coil is disposed near the gap and uses as a magnetic circuit the portion of the frame consisting of the material whose imaginary component of magnetic permeability is the lowest.

Abstract: An electron beam focusing device is provided for apparatus such as cathode ray tubes wherein an electron beam is scanned on a flat surface normal to the beam and converged at a point on the flat surface using magnetic fields. The focusing device includes a static field generator for converging the beam, and a dynamic focus device. The dynamic focus device is comprises a first winding coupled to a power supply, for example a current supply, for providing a magnetic field substantially defining a parabola during a trace interval of the beam to account for the variation in beam path length which occurs with scanning, and a second winding magnetically coupled to the first winding. An energy storing circuit coupled to the first and second windings stores energy during the trace interval and releases energy during the retrace interval such that the second winding induces a reverse current in the first winding, thereby returning current to the power supply during retrace.

Abstract: A focus coil for a television is disposed between scanning electron beam generator and a planar screen and has a winding coupled between a power supply and a current sink for providing a magnetic focusing field due to current in the coil. A focusing circuit comprises a resonant circuit coupled to the focus coil for generating a parabolic current in the focus coil to account for variations in the distance between the focusing device and the screen during scanning. The resonant circuit stores a portion of the energy developed during trace intervals and returns this energy to the power supply during retrace intervals. The resonant circuit includes a capacitor and an additional coil, in series with one another, and together in parallel with the focus coil. The additional coil is magnetically coupled to the focus coil and induces a reverse current in the focus coil during the retrace interval for returning energy to the power supply.