Transfer switch for a xerographic apparatus

Claim 1

A CHARGING CIRCUIT FOR APPLYING POSITIVE OR NEGATIVE ELECTROSTATIC CHARGE SELECTIVELY TO A XEROGRAPHIC PLATE INCLUDING: A CORONA CHARGING DEVICE HAVING AT LEAST ONE CORONA DISCHARGE ELECTRODE MOVABLE RELATIVE TO AND ADJACENT A XEROGRAPHIC PLATE; A D.C. POWER SUPPLY CONNECTED TO A SOURCE OF ELECTRIC CURRENT HAVING POSITIVE AND NEGATIVE OUTPUT TERMINALS AND A CIRCUIT CONNECTED TO SAID ELECTRODE FOR CONDUCTING A D.C. POTENTIAL THERETO AND THEREBY PRODUCE A CORONA DISCHARGE; SAID CIRCUIT INCLUDING A SWITCH MECHANISM HAVING A FIRST CONTACT CONNECTED TO SAID POSITIVE TERMINAL, A SECOND CONTACT CONNECTED TO SAID NEGATIVE TERMINAL, AND A THIRD CONTACT CONNECTED TO SAID ELECTRODE; SAID SWITCH MECHANISM HAVING A ROTATABLE CONDUCTIVE ELEMENT MOVABLE TO A FIRST POSITION TO BRIDGE ACROSS SAID FIRST AND THIRD CONTACTS TO PERMIT ENERGIZATION OF SAID ELECTRODE WITH POSITIVE VOLTAGE AND MOVABLE TO A SECOND POSITION TO BRIDGE ACROSS SAID SECOND AND THIRD CONTACTS TO PERMIT ENERGIZATION OF THE ELECTRODE WITH NEGATIVE VOLTAGE; MEANS FOR SELECTIVELY ACTUATING SAID CONDUCTIVE ELEMENT TO EITHER OF SAID POSITIONS; AND, A SWITCHING DEVICE FOR OPENING THE CIRCUIT TO SAID POWER SUPPLY FROM SAID SOURCE FOR TERMINATING CONDUCTION THERETO BEFORE SAID CONDUCTIVE ELEMENT IS MOVED INTO ON OUT OF ENGAGEMENT WITH SAID CONTACTS.