Electrostatic developing apparatus

Claim 1

APPARATUS COMPRISING A CONTAINER FOR A DEVELOPER MIXTURE OF MAGNETIC PARTICLES AND TONER PARTICLES, A FIRST DRUM OF MAGNETIC MATERIAL, A SECOND DRUM AND A THIRD DRUM BOTH OF NON-MAGNETIC MATERIAL, AT LEAST PORTIONS OF SAID DRUMS BEING DISPOSED WITHIN SAID CONTAINER, EACH OF SAID DRUMS BEING SPACED SLIGHTLY FROM THE OTHER OF SAID DRUMS AND FORMING GAPS THEREBETWEEN, EACH OF SAID DRUMS HAVING AN AXIS SUBSTANTIALLY PARALLEL TO THE AXES OF SAID OTHER OF SAID DRUMS, MEANS COUPLED TO SAID FIRST DRUM AND TO SAID SECOND DRUM TO ROTATE THEM IN OPPOSITEDIRECTIONS, SAID FIRST DRUM BEING ADAPTED TO STIR SAID DEVELOPER MIXTURE WHEN IT IS ROTATED, AND SAID THIRD DRUM BEING ADAPTED TO SUPPORT A WEB RECORDING ELEMENT FOR MOVEMENT THROUGH THE GAP BETWEEN SAID THIRD DRUM AND SAID FIRST DRUM AND THE GAP BETWEEN SAID SECOND DRUM AND SAID THIRD DRUM AND MAGNETIC MEANS FIXEDLY DISPOSED WITHIN SAID SECOND DRUM AND WITHIN SAID THIRD DRUM AND FORMING A MAGNETIC CIRCUIT WITH A PORTION OF SAID FIRST DRUM, SAID GAPS COMPRISING PORTIONS OF THE PATH OF SAID MAGNETIC CIRCUIT, THE ELEMENTS FORMING SAID MAGNETIC CIRCUIT COOPERATING TO PRODUCE A MAGENTIC BRUSH OF MAGNETIC AND TONER PARTICLES IN THE GAP BETWEEN SAID FIRST AND SECOND DRUMS AND IN THE GAP BETWEEN SAID SECOND AND THIRD DRUMS.