Transfer assist blade dwell correction

An apparatus for assisting in the transfer of an image from an image bearing member onto a copy substrate, comprising:

• a rotating photoreceptor belt carrying an image to be transferred, said belt including a location indicator;
• a feed mechanism for feeding a copy substrate to said image bearing member;
• a transfer assist blade arranged adjacent said image bearing member and operable in an activated position to bear on the substrate to maintain the substrate in contact with said image bearing member to assist in transferring the image thereto;
• a mechanism for moving said transfer assist blade between said activated position in response to an activation signal and a de-activated position in which said transfer assist blade does not maintain the substrate in contact with said image bearing member in response to a de-activation signal;
• a synchronization sensor operable to generate a synchronization signal in response to the passage of said location indicator as said photoreceptor belts rotates;
• a sensor for generating a leading edge signal in response to passage of the leading edge and a trailing edge signal in response to passage of the trailing edge of the substrate before such edge is adjacent said transfer assist blade;
• and
• a controller operable to transmit said activation signal to said mechanism after a predetermined first dwell time following receipt of said synchronization signal and to transmit said de-activation signal to said mechanism after a predetermined second dwell time later than said first dwell time, said controller further operable to determine the actual length of the substrate using said leading and trailing edge signals and to compare said length to a predetermined nominal length and to increase said second dwell time if said actual length is greater than said nominal length or to decrease said second dwell time if said actual length is less than said nominal length.

A method for operating a transfer assist mechanism to bear on a substrate passing over an image bearing member for transferring an image onto the substrate, comprising:

• activating the transfer assist mechanism to bear on the substrate;
• determining a nominal dwell time for de-activation of the transfer assist mechanism as a function of an expected length of the substrate;
• sensing an actual length of the substrate as it is conveyed to the image bearing member;
• and
• changing the dwell time for de-activation as a function of a comparison between the actual length and the expected length.