Sheet feeder

Abstract

For designing a more compact image reading device and printer requiring for separating a paper sheet and feeding the separated sheet, a limited space above a sheet cassette is effectively used for accommodating a larger number of paper sheets. A sensor lever is supported at its sensor lever axis fitted in an elliptic hole made in a supporting member of the sensor lever. The axis can swing and slide in the elliptic hole. With a large number of sheets piled in the cassette, the sensor lever swings to about horizontal position and the axis retracts up in the elliptic hole. With a small number of sheets, the sensor lever abuts at its abutting member against a receiving portion of the supporting member to prevent the sensor lever axis from moving upward in the elliptic hole, thereby the sensor lever can reliably detect the state of no paper remaining thereon.

1 . A sheet feeder for separating one of paper sheets piled thereon and feeding the separated sheet to a next process, wherein a sensor lever abutting against the top of sheets piled swings with a swinging axis and changes its angle in accordance with the amount of sheets and when a large number of sheets are loaded the swinging axis moves upward together with the sensor lever in the direction of separating the sensor lever from the pile of sheets.  
     
     
         2 . A sheet feeder as defined in  claim 1 , wherein a supporting member for supporting the sensor lever has an elliptic hole made for fitting therein the swinging axis of the sensor lever and the sensor lever has a abutting member formed thereon for abutting against a receiving portion of the supporting member to prevent the swinging axis of the sensor lever from moving when working with a decreased amount of sheets piled or with no sheet.  
     
     
         3 . A sheet feeder as defined in  claim 1 , wherein a supporting member for supporting the sensor lever has an elliptic hole having an enlarged round hole made for fitting therein the swinging axis of the sensor lever and the swinging axis of the sensor lever has a noncircular section to prevent the swinging axis of the sensor lever from moving in the elliptic hole when working with a decreased amount of sheets piled or with no sheet.  
     
     
         4 . A sheet feeder as defined in any of claims  2  and  3 , wherein a sheet piling portion has a concave formed thereon and a lower tip of the sensor lever falls in the concave with no sheet on the sheet piling portion.