Electrostatic writing and printing device

Claim 1

APPARATUS FOR FORMING A VISIBLE IMAGE FROM AN ELECTRICAL INFORMATION-BEARING SIGNAL COMPRISING AN EVACUATED ENVELOPE, A SOURCE OF ELECTRONS IN SAID ENVELOPE, A TARGET MEMBER OF ELECTRICAL INSULATING MATERIAL DISPOSED AT ONE END OF SAID ENVELOPE, A PLURALITY OF ELECTRICALLY CHARGED PARTICLES OF SMALL SIZE DISPOSED IN A CHAMBER ON THE OPPOSITE SIDE OF SAID MEMBER FROM SAID ELECTRON SOURCE, MEANS FOR DIRECTING SAID ELECTRONS IN A BEAM TOWARD SAID TARGET MEMBER AND FOR SWEEPING SAID BEAM ACROSS SAID TARGET MEMBER, MEANS FOR MODULATING THE INTENSITY OF SAID DIRECTED BEAM AS A FUNCTION OF SAID ELECTRICAL SIGNAL AS SAID BEAM SWEEPS ACROSS SAID TARGET TO PRODUCE AN ELECTROSTATIC CHARGE DISTRIBUTION PATTERN ON SAID TARGET SURFACE CORRESPONDING TO SAID INFORMATION, MEANS FOR MAINTAINING SAID CHARGED PARTICLES IN SAID CHAMBER AWAY FROM THE INFLUENCE OF THE ELECTROSTATIC CHARGE ON SAID TARGET DURING SWEEPING OF SAID BEAM ACROSS SAID TARGET, AND MEANS FOR CASCADING SAID CHARGED PARTICLES FROM SAID CHAMBER OVER SAID TARGET MEMBER UPON COMPLETION OF SAID CHARGING OF SAID TARGET TO CAUSE SAID PARTICLES TO ADHERE TO SAID CHARGED AREAS OF SAID TARGET TO PRODUCE A VISIBLE IMAGE OF SAID CHARGED AREAS.