Document handler vacuum belt platen transport clamping system

In a copying method utilizing a document handler for presenting documents to the platen of a copier for copying, comprising a vacuum belt platen transport system for feeding the documents over the platen and into an imaging position over the platen, wherein said vacuum belt platen transport system comprises plural document transporting belts movable under a substantially planar vacuum plenum backing and imaging background surface overlying said platen, and vacuum means for applying a partial vacuum to a document sheet being transported by said movable belts over the platen, and means for moving said belts, the improvement comprising the steps of:

• clamping said vacuum plenum backing and imaging background surface against the platen to flatten said belts and a document thereon against the platen for copying said document by unevenly moving said vacuum plenum backing and imaging background surface and said belts down towards said platen,
• unclamping said vacuum plenum backing and imaging background surface and said belts and a document thereon from said platen by unevenly lifting said surface away from said platen while supplying a partial vacuum with said vacuum means to lift a document away from said platen retained on said belts,
• said unclamping including lifting a first side of said vacuum plenum backing and imaging surface up away from said platen substantially before the opposite side thereof, and then subsequently lifting said opposite side, to generate a controlled air flow for assisting in retaining the document to said belts as said vacuum plenum backing and imaging surface is lifted away from said platen,
• and transporting a document with movement of said belts and with said partial vacuum retaining a document against said belts after said unclamping is at least partially completed.