| 摘要 |
In a document feeder with a vacuum belt platen transport system for transporting document sheets over the platen of a copier under a vacuum plenum backing surface closely overlying the platen and into a registration position for imaging the document sheet, with a registration system for stopping the document sheet at the registration position, the platen transport system including a vacuum source for applying a partial vacuum to a document sheet being transported sufficient to provide transport of the document sheet with movement of the belt transport into the registration system, and a system for automatically reducing the level of the partial vacuum in the vacuum plenum sufficiently to allow slippage of a document sheet relative to the belt transport at the registration system, and wherein the registration system comprises document engaging registration fingers movable into and out of the path of a document sheet being transported by the vacuum belt platen transport system, the improvement wherein the system for automatically reducing the level of the partial vacuum in the vacuum plenum comprises a valve system directly actuated by the registration system by mechanical connection to the movable registration fingers to automatically reduce the vacuum level in the vacuum plenum in direct response to the movement of the registration fingers into the path of a document sheet.
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