Magnetic apparatus for converging the beams of a plural gun cathode ray tube

Claim 1

IN AN ELECTRON BEAM CONVERGENCE APPARATUS FOR A CATHODE-RAY TUBE WHICH INCLUDES MEANS FOR DEVELOPING A PLURALITY OF ELECTRON BEAMS, A MAGNETIC ARRANGEMENT FOR CONTROLLING THE LATERAL POSITION OF A PARTICULAR ONE OF SAID BEAMS, COMPRISING: MEANS, INCLUDING A FIRST MAGNET POLARIZED IN A FIRST ORIENTATION RELATIVE TO THE PRINCIPAL AXIS OF SAID TUBE TO HAVE A MAGNETIC FIELD COMPONENT TRANSVERSE TO THE PATH OF SAID ONE OF SAID BEAMS, FOR PREDOMINANTLY EFFECTING A DESIRED LATERAL DISPLACEMENT OF SAID ONE BEAM RELATIVE TO ITS UNDISPLACED PATH WHILE SECONDARILY EFFECTING UNDESIRED DISPLACEMENTS OF OTHERS OF SAID BEAMS; AND MEANS, INCLUDING A PAIR OF ADDITIONAL MAGNETS DISPOSED IN JUXTAPOSITION TO BUTT ON OPPOSITE SIDES OF SAID FIRST MAGNET AND POLARIZED IN A DIFFERENT ORIENTATION RELATIVE TO SAID PRINCIPAL AXIS TO HAVE MAGNETIC FIELD COMPONENTS TRANSVERSE TO THE PATHS OF SAID OTHER BEAMS, FOR PREDOMINANTLY EFFECTING COMPENSATING DISPLACEMENTS OF SAID OTHER BEAMS TO SUBSTANTIALLY NEUTRALIZE THE UNDESIRED DISPLACEMENTS THEREOF DUE TO THE FIELD OF SAID FIRST MAGNET WITHOUT EFFECTING SUBSTANTIAL DISPLACEMENT OF SAID ONE BEAM.