Method and apparatus for high speed non-impact printing with

Abstract

A high speed non-impact printing means including (1) a non-impact printer having at least one pair of print electrodes, and a recipient sheet and closely spaced donor sheet positioned between the print electrodes, with the donor sheet having a substantially uniform distribution of electrically conductive, mobile printing particles dispersed near the surface thereof adjacent to the recipient sheet, (2) a print signal generator, (3) a variable coupling means associated with each print electrode pair for connecting the associated electrode pair to the print signal generator, and (4) a coupling control means for selectively varying the coupling afforded by each of said coupling means. Each variable coupling means comprises an optically controlled variable capacitance device which may be selectively controlled by the control means to couple the associated print electrode pair with the print signal generator by a predetermined capacitance. The electric field between each electrode pair, as established by the print signal coupled from the associated generator, is effective to transfer a plurality of the printing particles from the donor sheet to the recipient sheet, wherein the number of particles so transferred is related to the intensity of the electric field between the associated print electrodes.