DOCUMENT FEEDER WITH VACUUM SYSTEM HAVING TWO CONTROL VALVES IN SERIES

摘要

-0-DOCUMENT FEEDER WITH VACUUM SYSTEM HAVINGTWO CONTROL VALVES IN SERIESABSTRACT OF THE DISCLOSUREA document feeder defines a sheet pathalong which a document sheet is fed across a platenof a copier/duplicator, for example, in order tocopy the sheet. An oscillating vacuum tube feedssheets from a supply into the sheet path. Thefeeder includes a platen vacuum transport havingvacuum belts that move the sheet across the platen.The vacuum transport has a first vacuum plenum and asecond vacuum plenum located along the sheet path.The first vacuum plenum has a relatively high levelof vacuum to insure lifting of the sheet onto thevacuum belts. The sheet is then transported intothe area where it comes under the influence of thesecond vacuum plenum. The second vacuum plenum hasa somewhat lower level of vacuum, but it issufficient to retain the sheet on the belts as thebelts drive the sheet into engagement with aregistration member. One vacuum blower is used toestablish a vacuum in the vacuum tube and in the twoplenums. Two control valves regulate the flow ofair to the blower from the vacuum tube and one ofthe plenums. One valve controls air flow to theblower from the vacuum tube and the second controlvalve. The second control valve controls air flowfrom the first plenum to the first control valve.