Patent ID: 8126342
Filing Date: 2012-02-28
Classification: G03G

Abstract:
1. A system for tailoring a transfer nip electric field for enhanced toner image transfer in diverse environments, comprising: a rotatable transfer roll having a first potential; a rotatable backup roll having a second potential and forming a transfer nip between said rolls as said rolls counter-rotate relative to one another; and a rotatable pre-nip roll having a third potential and being positioned upstream from said transfer and backup rolls and said transfer nip such that a toner image-supporting transfer belt moving past said pre-nip, transfer and backup rolls separately makes contact with, wraps partially around, and rotates each of said pre-nip, transfer and backup rolls as a media sheet is fed into said transfer nip after first passing through a gap defined between said pre-nip roll and said transfer roll such that by presetting the position, geometry and charge of said pre-nip roll relative to said transfer and backup rolls and the transfer belt an electric field at said transfer nip can be tailored for enhanced toner transfer from the transfer belt to the media sheet in diverse environments; wherein in a relatively hot and humid environment, said first potential is approximately 800 volts above said second potential and said third potential is in a range of approximately 1500 volts to approximately 2000 volts above said second potential, and wherein said third potential is about zero volts above said second potential in a relatively cold and dry environment, the cold and dry environment being colder and dryer than the hot and humid environment.