Patent ID: 6775490
Filing Date: 2004-08-10
Classification: G03G

Abstract:
An electrostatographic apparatus for producing images on a receiver member comprising:a negatively charged dielectric support member; a development station containing negatively and positively charged marking particles; a back-up for urging the dielectric support member against the development station when engaged; a transfer roller; a power supply to electrically bias the transfer roller positive to cause the transfer of marking particles from the dielectric support member to the receiver member; a controller to: i) disengage the back-up when the development station is not needed prior to a start-up phase of the apparatus; ii) engage the back-up during the start-up phase; iii) disable the power supply during the start-up phase to reduce the transfer roller bias to approximately zero volts to thereby prevent contamination of the transfer roller from positively charged marking particles; and iv) enable the power supply to electrically bias the transfer roller positive prior to a first receiver member reaching the transfer roller after the start-up phase by first operating in a constant voltage mode for a short time to allow capacitive current to settle out and then switch to a constant current mode.