Constant velocity transport for electronic document imaging

In a document handler for sequentially feeding document sheets over an imaging platen to be imaged at a constant velocity with a constant velocity drive motor driving a document sheet feeding roller overlying said imaging platen for feeding engagement of document sheets between said constant velocity driven document sheet feeding roller and said platen when a forward driving signal is applied to said constant velocity drive motor, said document handler providing a document sheet feeding path from a document input to said imaging platen and to a document output, the improvement comprising:

• a document feeding control system which predicts when said constant velocity driven sheet feeding roller will be driven against said imaging platen with no document sheet therebetween;
• and
• an automatic lifting system which automatically lifts said constant velocity document sheet feeding roller away from said imaging platen in response to said document feeding control system predicting that no document sheet will be between said constant velocity driven sheet feeding roller and said platen and said forward driving signal is being applied to said constant velocity drive motor;
• wherein said constant velocity document sheet feeding roller has at least four sections of two different diameters, comprising an inner pair of common diameter feed roller surfaces, and an outer pair of slightly smaller diameter surfaces on opposite axial sides of said inner pair of feed roller surfaces which are not feeding roller surfaces.