Abstract: Apparatus for compensating for keystone distortion in a flat cathode ray tube in a relatively straightforward and inexpensive manner, and for providing a tube having relatively high resolution and reduced deflection aberration. A magnetic deflection yoke is utilized to scan the raster on the screen, and corrective deflective forces are provided on the electron beam to compensate for keystone. In a first embodiment, the corrective forces are provided by a magnetic hexapole field, in second and third embodiments by magnetic quadrapole fields in series with horizontal and vertical deflections respectively, and in a fourth embodiment by providing the combination of a hexapole field and orthogonal quadrapole field in series with horizontal and vertical deflections respectively.

Abstract: A multibeam matrix array cathode ray tube having diminished rotational and focused distortion. In a multibeam cathode ray tube having a flat or planar electron beam emitter means arranged to project a two-dimensional array of beams, deflection means and stigmator correction means are provided. In addition, a novel split focus coil is provided for correcting distortion due to undesired rotation of the array of beams. By dynamically supplying opposing currents in the two halves of the split focus coil, rotational distortion may be compensated for, while adjustments are automatically made for changes of focus due to the introduction of rotational correction. Correctional currents are dynamically supplied to the split coils as a function of the matrix beam displacement on the cathode ray tube face.

Abstract: An apparatus and method for forming scanned electron beam patterns which finds particular use in multiple beam cathode ray tubes. Instead of using the vertical line array of electron beam sources which is used in conventional multiple beam tubes, a two dimensional expanded beam array is provided. The expanded array is such that no two electron beams in the array are disposed in the same scan line and it is of a geometric shape having comparable length and width dimensions. In order to form characters or other patterns logic circuitry is provided to control each beam of the expanded array at respective scanning positions as the array is deflected or scanned across the screen of the cathode ray tube.

Abstract: A multiple beam cathode ray tube having diminished off-axis aberrations and a reduced length. A tube having a flat or planar electron beam emitter means, focussing means and deflection means is provided. A novel accelerating means is provided for accelerating the emitted beams while causing them to converge towards a crossover point which is located not closer to the screen of the tube than the deflection means. The maximum off-axis distance of the beams when traversing the focussing and deflection means is reduced, and the off-axis aberrations are correspondingly diminished.

Abstract: A multiple beam cathode ray tube having an improved cathode-grid structure which facilitates grid lead connections and mounting. The cathode means has a plurality of openings which are arranged in an array pattern which is identical to the desired electron beam array pattern, and has an emitter means associated with each opening for emitting a group of electrons. The grid means is located behind instead of in front of the cathode means and is comprised of a plurality of grid elements mounted on a substrate. When appropriately biased, the grid elements cause groups of electrons which are emitted by the respective emitter means to flow through the corresponding openings in the cathode in the direction of the screen, thus establishing the required electron beams.