Electrostatic recording with interchangeable stencils

Claim 1

IN AN ELECTROSTATIC RECORDING PAGE PRINTER, THE COMBINATION COMPRISING: A RECORD MEDIUM STORE; MEANS FOR ADVANCING A RECORD MEDIUM HAVING A CHARGE-RETENTIVE OBVERSE FROM THE SAID STORE TOWARD A PRINTING STATION, THE SAID PRINTING STATION COMPRISING DISCHARGE ELECTRODE MEANS COMPRISING INDIVIDUAL ELECTRODES AND BACKING ELECTRODE MEANS ALIGNED WITH AND IN PROXIMITY TO SAID DISCHARGE ELECTRODE MEANS TO FORM A GAP FOR RECEIVING SAID RECORD MEDIUM BETWEEN SAID DISCHARGE AND BACK ELECTRODE MEANS FOR ESTABLISHING ELECTRIC CHARGES UPON THE OBVERSE OF SAID RECORD MEDIUM; DATA SOURCE AND CONTROL MEANS FOR APPLYING TO SAID DISCHARGE ELECTRODE MEANS ELECTRICAL PULSES SELECTIVELY IN ACCORDANCE WITH DATA FROM DATA SOURCE WHEREIN SAID PULSES ARE OF MAGNITUDE AND DURATION SUCH THAT SAID ELECTRIC CHARGES ARE ESTABLISHED ON SAID RECORD MEDIUM DURING A SHORT DURATION SUBSTANTIALLY OF THE ORDER OF THE PULSE WIDTH AND THE DISCHARGE IS TERMINATED IN A TIME PERIOD OF THE ORDER OF WITHIN A MICROSECOND; DEVELOPING AND FIXING MEANS FOR RENDERING THE DISTRIBUTION OF SAID ELECTRIC CHARGES ON SAID RECORD MEDIUM PERMANENTLY VISIBLE; APERTURED MASK MEANS MOVABLY INTERPOSED BETWEEN SAID INDIVIDUAL ELECTRODES OF SAID DISCHARGE ELECTRODE MEANS AND SAID RECORD MEDIUM SO TO SHAPE THE DISCHARGE FROM SAID DISCHARGE ELECTRODE MEANS AS TO PRODUCE ON SAID RECORD MEDIUM DISTRIBUTIONS OF ELECTRIC CHARGES APPROXIMATELY SIMILAR IN SHAPE TO THE APERTURES OF SAID APERTURED MASK MEANS; MEANS TO MAINTAIN SAID MASK MEANS AT A POTENTIAL TO FACILITATE GOOD DISCHARGE INTERMEDIATE THE POTENTIAL BETWEEN SAID INDIVIDUAL ELECTRODES OF SAID DISCHARGE ELECTRODE MEANS WHEN DISCHARGE OCCURS BUT SUFFICIENTLY APART FROM SAID LAST-NAMED POTENTIAL OF SAID INDIVIDUAL ELECTRODE MEANS SO THAT SAID MASK MEANS WILL NOT DISCHARGE TO SAID RECORD MEDIUM AND SUFFICIENTLY NEAR GROUND POTENTIAL SUCH THAT SAID MASK MEANS WILL NOT TEND TO CAPTURE THE CHARGES FROM SAID INDIVIDUAL ELECTRODES OF SAID DISCHARGE ELECTRODE AND PREVENT THEM FROM REACHING SAID RECORD MEDIUM.