Sheet feed image scanning apparatus

Abstract

A sheet feed image scanning apparatus comprises a sheet feeding unit mounted to an image scanning unit. The sheet feeding unit has a casing that comprises the mount of a sheet conveyor assembly to convey a document sheet along a conveyance path that passes over a scanning window. The sheet conveyor assembly comprises a motor-driven central conveyor roller and a plurality of idler rollers mounted in circumferential contact with the central conveyor roller. The document introduced in the sheet feeding unit engages between the central conveyor roller and the idler rollers to be conveyed over the scanning window, through which the scanning unit captures an image of the document sheet.

1 . A sheet feeding unit suitable for being mounted in a sheet feed image scanning apparatus to convey a document sheet that is to be scanned, the sheet feeding unit comprising: 
 a casing, having a rear side and a front side through which the document sheet is introduced in the sheet feeding unit;    a sheet conveyor assembly, mounted in the casing and including a central conveyor roller that has a roller surface, the document sheet introduced in the sheet feeding unit engaging through the sheet conveyor assembly by having a sheet surface that is in contact with the roller surface of the central conveyor roller; and    a driving motor, driving the central conveyor roller in rotation to convey the document sheet along a conveyance path.    
     
     
         2 . The sheet feeding unit of  claim 1 , wherein the conveyance path includes a curved portion that substantially matches with a circumference of the central conveyor roller.  
     
     
         3 . The sheet feeding unit of  claim 1 , wherein the sheet conveyor assembly further includes a plurality of idler rollers that contact with the central conveyor roller along a circumferential direction thereof to engage and convey the document sheet there between.  
     
     
         4 . The sheet feeding unit of  claim 3 , wherein the sheet conveyor assembly further includes a belt that is wound around at least two of the idler rollers and is in contact with the roller surface of the central conveyor roller to engage and convey the document sheet there between.  
     
     
         5 . The sheet feeding unit of  claim 4 , wherein the coefficient of friction between the roller surface of the central conveyor roller and the document sheet is greater than that between the belt and the document sheet.  
     
     
         6 . The sheet feeding unit of  claim 1 , further including a sheet pickup roller, a sheet separating roller and a sheet separating plate that are arranged with the central conveyor roller and the driving motor successively along an axis running from the front side to the rear side of the casing.  
     
     
         7 . The sheet feeding unit of  claim 6 , wherein the sheet pickup roller is mounted proximate to the front side to engage the document sheet, and the sheet separating plate and the sheet separating roller are mounted between the sheet pickup roller and the sheet conveyor assembly to ensure that a single document sheet engages through the sheet conveyor assembly.  
     
     
         8 . An image scanning apparatus, having a front side through which a document sheet to be scanned is introduced therein, the image scanning apparatus comprising: 
 a sheet conveyor assembly, including a motor-driven central conveyor roller that has a roller surface, the introduced document sheet engaging through the sheet conveyor assembly by having a sheet surface in contact with the roller surface, the document sheet being thereby conveyed via a rotation of the central conveyor roller along a conveyance path that passes over a scanning window defined through an inner wall of the sheet feed image scanning apparatus; and    an image scanning unit, mounted at a location that faces the conveyance path to capture an image of the document sheet through the scanning window.    
     
     
         9 . The image scanning apparatus of  claim 8 , wherein the conveyance path includes a curved portion that substantially matches with a circumference of the central conveyor roller.  
     
     
         10 . The image scanning apparatus of  claim 8 , wherein the sheet conveyor assembly further includes a plurality of idler rollers that contact with the central conveyor roller along a circumferential direction thereof to engage and convey the document sheet there between.  
     
     
         11 . The image scanning apparatus of  claim 10 , wherein the sheet conveyor assembly further includes a belt that is wound around at least two of the idler rollers and is in contact with the roller surface of the central conveyor roller to engage and convey the document sheet there between.  
     
     
         12 . The image scanning apparatus of  claim 11 , wherein the coefficient of friction between the roller surface of the central conveyor roller and the document sheet is greater than that between the belt and the document sheet.  
     
     
         13 . The image scanning apparatus of  claim 8 , further including a sheet pickup roller mounted proximate to the front side to engage the document sheet, and a sheet separating roller and a sheet separating plate that are mounted between the sheet pickup roller and the sheet conveyor assembly to ensure that a single document sheet engages through the sheet conveyor assembly.  
     
     
         14 . The image scanning apparatus of  claim 8  wherein the image scanning unit comprises a source light and a scanning module, the source light emitting a light passing through the scanning window to strike the document sheet and produce an image light that is captured by the scanning module.  
     
     
         15 . The image scanning apparatus of  claim 14 , wherein the scanning module comprises an assembly of reflecting mirrors, an objective lens, and an image sensor.  
     
     
         16 . The image scanning apparatus of  claim 15 , wherein the image sensor includes a charge coupled device or a complementary metal oxide semiconductor image sensor.