A cathode ray tube display having an in-line tube includes an electromagnetic unit for dynamically influencing the path or shape of the electron beams. The power for supplying current to the electromagnetic unit is drawn from the line deflection circuit, either through supply coil on a transformer arranged in parallel with the line deflection coil, or from a supply coil sound around the deflection unit core.

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. A thyristor switch references energy induced in the first winding by the second winding to ground during the retrace intervals.

An electron beam tends to slope downwardly as it is deflected horizontally to form a raster in a video display apparatus. The sloping of the beam can cause geometric errors in the raster, for example orthogonality and parallelogram errors. A raster correction circuit substantially offsets the downward slope of the electron beam by modulating a vertical deflection current with an induced horizontal-rate raster correction current, thereby substantially eliminating orthogonality and parallelogram errors in the raster. In respective embodiments of an inventive arrangement taught herein, the horizontal-rate raster correction current is induced in the vertical deflection coils by magnetically coupling a filament pulse waveform, a horizontal deflection voltage waveform, or a horizontal deflection current into the vertical deflection coils.

An electron beam trajectory controlling device includes a main deflection section having a first main coil and defining a first path and being configured to control a trajectory of an electron traveling along the first path. The main deflection section includes a first auxiliary coil provided proximate the first main coil. A minor deflection section is provided adjacent to the main deflection section and has a first minor coil that is coupled to the first auxiliary coil. The minor deflection section defines a second electron path that is aligned to the first path. The minor deflection section cooperates with the main deflection section to control the trajectory of the electron.

A projection television receiver has a cathode ray tube with an electron gun for emitting an electron beam incident on a screen, an electromagnetic deflection yoke and an electromagnetic focusing coil. The focusing coil is included in a resonant circuit. The resonant circuit is energized by switching operation of a switching transistor in the vicinity of a retrace interval. Variations of the focusing coil current in the vicinity of the retrace interval provide dynamic focus.