| 摘要 |
A document feed assembly comprises a document stack hopper (100) for supporting a stack of documents (10). The hopper (100) has a planar base part (3) slidable in a feed direction while carrying a lowermost document in the stack. A drive system (110) cyclically slides the base part (3) to and for beneath the stack. A feed assist system selectively assists the feeding of documents by the base part (3), the feed assist system comprising a vacuum generating system (9) for selectively applying vacuum to a port (12a) extending through the base part (3), wherein movement of the base part (3) in the feed direction generates a vacuum in a chamber (9a) communicating with the port (12a) while movement of the base part in the opposite direction stops the generation of vacuum characterised in that the assembly further comprises a bleed port (9b) coupled with the vacuum chamber (9a) and to a control system (16,17) which closes the bleed port (9b) when a vacuum is being generated and opens the bleed port (9b) when a vacuum is not being generated. |
