Sheet curl correction method and feeder apparatus

A sheet feeding apparatus, comprising:

• a pneumatic feedhead being selectively actuable to acquire a sheet from a stack and transport the sheet towards a take-away nip, the feed head having an acquisition surface, the acquisition surface being substantially aligned with the take-away nip,
• a stack height sensor for detecting a first distance between a stack of sheets and the acquisition surface at a first location over the stack of sheets,
• a lead edge attitude sensor for detecting a second distance between the stack of sheets and the acquisition surface at a second location closer to a lead edge of the stack of sheets than the first location, and also for detecting a third distance between the stack of sheets and the acquisition surface at a third location closer to the lead edge of the stack of sheets than the second location;
• a first motor for moving the feedhead, so that the lead edge attitude sensor can measure the second distance and the third distance at the second and third locations, respectively,
• a sheet support tray;
• and
• a second motor that adjusts the tray based upon the first, second, and third distances detected.