Electrostatic deflection arrangement for electron tubes

Claim 1

A CATHODE RAY TUBE ARRANGEMENT COMPRISING MEANS CONSTITUTING A SOURCE OF AN ELECTRON BEAM, TWO PAIRS OF MUTUALLY CROSSED PLATES POSITIONED ALONG THE PATH OF SAID BEAM FOR ELECTROSTATICALLY DEFLECTING THE SAME, A POTENTIAL SOURCE CONNECTED TO ONE OF SAID PAIR OF PLATES REMOTE FROM SAID SOURCE TO APPLY A DEFLECTING POTENTIAL THERETO, ELECTROSTATIC LENS MEANS HAVING A FIELD OF ELECTRIC LINES OF FORCE WITH TWO ORTHOGONAL PLANES OF SYMMETRY AND A DIFFERENT CONVERGENCE ALONG SAID TWO PLANES, SAID LENS MEANS BEING OPERATIVELY POSITIONED ALONG THE PATH OF SAID BEAM BETWEEN SAID SOURCE AND THE OTHER OF SAID PAIR OF PLATES ADJACENT SAID SOURCE, MEANS FOR APPLYING TO SAID LENS MEANS A POTENTIAL PROPORTIONAL AT EACH INSTANT TO THE SQUARE OF SAID DEFLECTING POTENTIAL APPLIED TO SAID ONE PAIR OF PLATES TO CORRECT FOR THE ASTIGMATISM CAUSED BY SAID ONE PAIR, DIAPHRAGM MEANS IN THE FORM OF AN ELECTRODE INTERMEDIATE SAID TWO PAIRS OF MUTUALLY CROSSED PLATES AND PROVIDED WITH A RECTANGULAR APERTURE HAVING TWO SIDES THEREOF AT LEAST EQUAL TO THE EDGES OF SAID ONE PAIR OF PLATES AT THE INPUT THEREOF TO THEREBY CORRECT THE ASTIGMATISM OF THE OTHER PAIR OF PLATES, SAID ELECTROSTATIC LENS MEANS BEING DEFINED, ON THE ONE HAND, BY A SLIT BETWEEN THE TWO PLATES OF SAID OTHER PAIR OF PLATES, AND, ON THE OTHER HAND, BY AN APERTURE FOR THE PASSAGE OF SAID BEAM PROVIDED IN A DIAPHRAGM DISPOSED BETWEEN SAID SOURCE AND SAID OTHER PAIR OF PLATES, SAID MEANS FOR APPLYING SAID PROPORTIONAL POTENTIAL BEING OPERATIVELY CONNECTED TO SAID DIAPHRAGM, AND WHEREIN SAID LAST-MENTIONED APERTURE IS OF CIRCULAR SHAPE.