Color electrophotography

Claim 1

AN ELECTROSTATIC PRINTING UTILIZING A RECORDING ELEMENT HAVING A PHOTOCONDUCTIVE INSULATING COATING ON A SURFACE THEREOF, SAID COATING BEING SENSITIVE TO AT LEAST TWO DIFFERENT COLORS OF THE VISIBLE SPECTRUM, THE PHOTOCONDUCTIVE RESPONSE OF SAID COATING BEING SUCH THAT EXPOSURE TO EQUAL QUANTITIES OF LIGHT OF A MULTIPLE COLOR IMAGE WILL RESULT IN ONE COLOR OF SAID IMAGE PRODUCING PHOTOCONDUCTIVITY IN SAID COATING BEFORE ANOTHER COLOR OF SAID IMAGE PRODUCES PHOTOCONDUCTIVITY IN SAID COATING; SAID PROCESS COMPRISING THE STEPS OF: (1) PRODUCING AN OVERALL ELECTROSTATIC CHARGE UPON SAID COATING; (2) EXPOSING SAID COATING TO ALL COLORS OF SAID PLURAL COLOR LIGHT IMAGE TO CAUSE A FIRST QUANTITY OF LIGHT TO IMPINGE UPON SAID COATING, SAID QUANTITY BEING SUFFICIENT TO PRODUCE A PHOTOCONDUCTIVE DISCHARGE OF SAID COATING IN THOSE AREAS IMPINGED UPON BY ALL COLORS OF SAID IMAGE EXCEPT SAID ONE COLOR TO PRODUCE A FIRST LATENT ELECTROSTATIC IMAGE, THE CHARGED AREAS OF WHICH CORRESPOND TO SAID ONE COLOR; (3) DEVELOPING SAID ELECTROSTATIC IMAGE WITH A DEVELOPER POWDER HAVING A FIRST CHARACTERISTIC COLOR AND HAVING A VOLUME RESISTIVITY NOT IN EXCESS OF 1012 OHM-CENTIMETERS WHEN FIXED TO SAID COATING; (4) FIXING SAID DEVELOPER POWDER TO SAID COATING TO PROVIDE THEREON IMAGE AREAS OF SAID FIRST CHARACTERISTIC COLOR, WHICH IMAGE AREAS ARE THUS RENDERED INCAPABLE OF RETAINING AN ELECTROSTATIC CHARGE; (5) REPEATING STEP (1) TO PRODUCE AN OVERALL ELECTROSTATIC CHARGE ON SAID COATING IN ALL AREAS OTHER THAN THOSE OF SAID FIRST CHARACTERISTIC COLOR; (6) REPERATING STEP (2) BY CAUSING A SUBSTANTIALLY SMALLER QUANTITY OF LIGHT TO IMPINGE UPON SAID COATING, SAID SMALLER QUANTITY BEING SUFFICIENT TO PRODUCE PHOTOCONDUCTIVE DISCHARGE OF SAID COATING IN THOSE AREAS IMPINGED UPON BY AT LEAST ONE OF SAID OTHER COLORS OF SAID IMAGE TO PRODUCE A SECOND LATENT ELECTROSTATIC IMAGE ON SAID COATING; (7) REPEATING STEP (4) WITH ANOTHER DEVELOPER POWDER HAVING A CHARACTERISTIC COLOR DIFFERENT FROM SAID FIRST CHARACTERISTIC COLOR.