Sheet feeder apparatus

Abstract

A feeder apparatus includes a feed tray for stacking documents, a document detection sensor for detecting the documents on the feed tray, a supply roller for contacting a top surface of the documents on the feed tray and supplying the documents, and a support plate disposed in front of the feed tray for supporting a leading edge of the documents in a feed direction and being able to rise and fall between a lower limit position where the documents are loaded on the feed tray and an upper limit position where the top surface of the documents contacts the supply roller. The support plate is controlled to wait at a standby position below the upper limit position after the documents are loaded on the feed tray and move from the standby position to the upper limit position upon receiving a feed signal to start feeding the documents.

What is claimed is:  
     
         1 . A feeder apparatus for sequentially feeding sheets to a predetermined processing position, comprising: 
 stacking means for stacking the sheets,    supply means for contacting a surface of an uppermost sheet stacked in the stacking means and for supplying the sheet,    raise and lower means for raising and lowering the stacking means between a lower limit position for stacking the sheets and an upper limit position for allowing the surface of the uppermost sheet to contact the supply means,    sheet detection means for detecting the sheets stacked in the stacking means, and    control means for controlling the raise and lower means to move the stacking means from the lower limit position to the upper limit position upon receiving a detection signal of the sheet detection means, and for controlling the supply means to drive upon receiving a feed signal that directs to start feeding the sheets.    
     
     
         2 . A feeder apparatus according to  claim 1 , wherein said stacking means comprises a feed tray for supporting a trailing edge of the sheet in a feed direction, and an rise and lower tray for supporting a leading edge of the sheet in the feed direction, said raise and lower means raising and lowering the rise and lower tray.  
     
     
         3 . A feeder apparatus according to  claim 1 , wherein said control means controls the raise and lower means so that the rise and lower tray moves to the lower limit position when there is no feed signal after a predetermined time after the rise and lower tray moves to the upper limit position.  
     
     
         4 . A feeder apparatus for sequentially feeding sheets to a predetermined processing position, comprising: 
 stacking means for stacking the sheets,    supply means for contacting a surface of an uppermost sheet stacked in the stacking means and for supplying the sheet,    raise and lower means for raising and lowering the stacking means between a lower limit position for stacking the sheets, an upper limit position for allowing the surface of the uppermost sheet to contact the supply means, and a standby position disposed between the lower limit position and the upper limit position,    sheet detection means for detecting the sheets stacked in the stacking means, and    control means for controlling the raise and lower means to move the stacking means from the lower limit position to the standby position to standby based on a detection result of the detection means, and to move the stacking means from the standby position to the upper limit position upon receiving a feed signal that directs to start feeding the sheets.    
     
     
         5 . A feeder apparatus according to  claim 4 , wherein said stacking means comprises a feed tray for supporting a trailing edge of the sheet in a feed direction, and an rise and lower tray for supporting a leading edge of the sheet in the feed direction, said raise and lower means raising and lowering the rise and lower tray.  
     
     
         6 . A feeder apparatus according to  claim 5 , wherein said control means controls the raise and lower means so that the rise and lower tray moves to the lower limit position when there is no feed signal after a predetermined time after the rise and lower tray moves to the standby position.  
     
     
         7 . A feeder apparatus according to  claim 5 , further comprising lower limit detection means for detecting whether the rise and lower tray is located at the lower limit position, and upper limit detection means for detecting whether the surface of the uppermost sheet on the rise and lower tray contacts the supply means.  
     
     
         8 . A feeder apparatus according to  claim 7 , wherein said control means controls the raise and lower means to raise the rise and lower tray from the lower limit position upon receiving the detection signal of the sheet detection means, and to lower the rise and lower tray by a predetermined amount and move the rise and lower tray to the standby position when the upper limit detection means detects the surface of the uppermost sheet.  
     
     
         9 . A feeder apparatus according to  claim 5 , wherein said control means controls the raise and lower means to start moving from the lower limit position to the standby position after a predetermined time from when the detection means detects the sheets stacked in the feed tray.