Two-dimensional CMOS sensor array to image documents and other flat objects

Abstract

A flatbed scanner includes a housing, a transparent platen atop the housing for receiving an object to be scanned, and a carriage operable to travel along a horizontal direction and a vertical direction. The carriage includes a light source for illuminating the object and a rectangular photodetector array for simultaneously detecting light intensity of multiple scan lines.

1 . A flatbed scanner, comprising: 
 a housing;    a transparent platen atop the housing for receiving an object to be scanned;    a carriage operable to travel along a first direction and a second direction, the carriage comprising: 
 a light source for illuminating the object; and  
 a rectangular photodetector array for simultaneously detecting light intensity of multiple scan lines, the rectangular photodetector array comprising more than three rows of photodetectors.  
   
     
     
         2 . The scanner of  claim 1 , wherein the carriage further comprises: 
 a mounting plate having a horizontal guide, the light source and the rectangular photodetector array being mounted on the mounting plate;    a first motor linked to a first gear; and    a horizontal carriage bar defining a horizontal guide channel for receiving the horizontal guide and a horizontal gear channel for receiving the first gear, the first motor being operable to drive the first gear to move the carriage along the horizontal direction.    
     
     
         3 . The scanner of  claim 2 , wherein: 
 the horizontal carriage bar has vertical guides;    the carriage further comprises a second motor linked to a second gear; and    the housing defines vertical guide channels for receiving the vertical guides and a vertical gear channel for receiving the second gear, the second motor being operable to drive the second gear to move the carriage along the vertical direction.    
     
     
         4 . The scanner of  claim 1 , wherein the light source comprises a ring of light emitting diodes formed around the rectangular photodetector array.  
     
     
         5 . The scanner of  claim 1 , wherein the rectangular photodetector array comprises a complementary metal oxide semiconductor (CMOS) image sensor array.  
     
     
         6 . The scanner of  claim 5 , wherein the light source comprises light emitting diodes located on the same die as the rectangular photodetector array.  
     
     
         7 . A method for operating a flatbed scanner, comprising: 
 capturing a first image of an object placed on a transparent platen of the scanner with a rectangular photodetector array, the rectangular photodetector array comprising more than three rows of photodetectors;    moving the rectangular photodetector array in a first small increment along a first direction and a second small increment along a second direction, the first increment being less than a first spacing between adjacent photodetectors on the photodetector array along the first direction, the second increment being less than a second spacing between adjacent photodetectors on the photodetector array along the second direction; and    capturing a second image of the object.    
     
     
         8 . The method of  claim 7 , further comprising combining the first and the second image to form a scanned image of the object.  
     
     
         9 . The method of  claim 7 , further comprising: 
 moving the rectangular photodetector array in a large increment along the first direction; and    capturing a third image of the object.    
     
     
         10 . The method of  claim 9 , wherein the large increment is at least a dimension of the rectangular photodetector array along the first direction.  
     
     
         11 . The method of  claim 9 , further comprising: 
 moving the rectangular photodetector array in the first small increment along the first direction and the second small increment along the second direction; and    capturing a fourth image of the object.    
     
     
         12 . The method of  claim 11 , further comprising combining the first, the second, the third, and the fourth image to form a scanned image of the object.  
     
     
         13 . A sheet feed scanner, comprising: 
 a housing;    feed rollers that moves a document in a first direction;    a carriage operable to travel along a second direction, the carriage comprising: 
 a light source for illuminating the document; and  
 a rectangular photodetector array for simultaneously detecting light intensity of multiple scan lines, the rectangular photodetector array comprising more than three rows of photodetectors.  
   
     
     
         14 . The scanner of  claim 13 , wherein the carriage further comprises: 
 a mounting plate having a horizontal guide, the light source and the rectangular photodetector array being mounted on the mounting plate;    a first motor linked to a first gear; and    a horizontal carriage bar defining a horizontal guide channel for receiving the horizontal guide and a horizontal gear channel for receiving the first gear, the first motor being operable to drive the first gear to move the carriage along the horizontal direction.    
     
     
         15 . The scanner of  claim 13 , wherein the light source comprises a ring of light emitting diodes formed around the rectangular photodetector array.  
     
     
         16 . The scanner of  claim 13 , wherein the rectangular photodetector array comprises a complementary metal oxide semiconductor (CMOS) photodetector array.  
     
     
         17 . The scanner of  claim 16 , wherein the light source comprises light emitting diodes located on the same die as the rectangular photodetector array.  
     
     
         18 . A flatbed scanner, comprising: 
 a housing;    a transparent platen atop the housing for receiving an object to be scanned;    a light source for illuminating the entire object;    optics for directing light reflecting off the entire object to a rectangular photodetector array; and    the rectangular photodetector array for simultaneously detecting light intensity of the entire object, the rectangular photodetector array comprising more than three rows of photodetectors.