Patent ID: 6560436
Filing Date: 2003-05-06
Classification: G03G

Abstract:
An apparatus for transferring charged toner particles from an image support surface to a substrate, comprising:a substrate positioned to have at least a portion thereof adjacent said image support surface in a transfer region, defining a transfer nip, a pre-nip region having a pre-transfer nip gap, and a post-nip region having a post-transfer nip gap; and a transfer station, located adjacent said transfer region, for applying an oscillatory bias voltage potential difference between said image support surface and said substrate in said transfer region so as to effect an oscillatory electric field therein, wherein the oscillatory electric field exhibits an oscillatory component having alternating polarity and respective bidirectional field strength that is sufficient to effect repeated transfer and back transfer of the toner within the transfer nip with respect to the substrate, and a constant component having a single polarity and a respective unidirectional field strength sufficient to effect ultimate toner particle transfer to the substrate, wherein the oscillatory component diminishes to a level that allows the constant component to effect the ultimate toner particle transfer to the substrate, such that high transfer efficiency and stable toner transfer are achieved.