Thermo-electric transfer system for liquid toner

A thermo-electric image transfer system for directly transferring an image formed by liquid toner on a photoconductor to a sheet medium which has not been wetted with a liquid toner carrier, comprising:

• a photoconductor drum carrying an image defined by liquid toner applied to the surface of said drum, said toner having an electrostatic polarity;
• a heated platen over which a sheet medium onto which said image is fed;
• first and second heated transfer rollers, defining a nip therebetween into which said medium is fed from said platen, providing a means for heating the image side of said medium to a temperature in excess of the melt temperature of said toner, the second of said rollers having an outer layer of an elastomeric material, said second roller being heated to provide a means for heating the backside of said sheet media;
• means for guiding said medium out of said nip between said transfer rollers and into contact with said photoconductor drum, said guiding means maintaining contact between said elastomeric layer and said medium until said medium contacts said photoconductor drum at a second nip between said second roller and said drum;
• and
• means for applying an electrostatic voltage to said second roller which is opposite in polarity to that of said toner to provide an electrostatic attraction of the toner to said medium.

A method for directly transferring an image formed by liquid toner on a photoconductor to a sheet medium in the absence of a liquid toner carrier applied to the sheet medium, comprising a sequence of the following steps:

• forming a liquid toner image on a photoconductor, said toner having an electrostatic polarity;
• feeding said sheet medium into a nip defined by first and second heated transfer rollers to heat the image side of said medium to a temperature in excess of the melt temperature of said toner, the second of said rollers having an outer layer of a material which is thermally and electrically conductive;
• applying an electrostatic voltage to said second roller which is opposite in polarity to that of said toner to provide an electrostatic attraction of the toner to said medium;
• guiding said medium out of said nip between said transfer rollers and into contact with said photoconductor, while maintaining contact between said elastomeric layer and said medium until said medium contacts said photoconductor at a second nip between said second roller and said photoconductor.