Back-light module for image scanning device and method for calibrating illumination with the back-light module

Abstract

A back-light module for an image scanning device includes a casing, a pair of tubular lamps, a light guide plate, and a frosted transparent plate. The image scanning device includes a document supporting plate and an optical scanning module movable in a longitudinal direction. A calibration of illumination with the back-light module is done by (1) activating the back-light module to project light onto the optical scanning module, (2) driving the optical scanning module in the longitudinal direction, (3) obtaining illumination signals associated with selected pixels of a longitudinally-extending calibration zone formed on the document supporting plate, (4) comparing each illumination signal with a reference to obtain a result and manipulating the result to obtain a calibration parameter, and (5) calibrating the illumination of pixels of an image with the corresponding calibration parameters in scanning a transmissive original document.

1 - 8 . (canceled)  
     
     
         9 . A scanning system comprising an image scanning device capable of calibrating illumination in a first direction and calibrating illumination in a second direction.  
     
     
         10 . The scanning system of  claim 9 , wherein the image scanning device further comprises: 
 an optical scanning module comprising at least one image sensing element, the at least one image sensing element capable of sensing an image signal of at least one selected pixel;    a back-light module capable of illuminating the optical scanning module; and    at least one processing module capable of obtaining an image signal of at least one selected pixel, wherein said processing module is further capable of obtaining at least one calibration parameter.    
     
     
         11 . The system of  claim 10 , wherein the image signal is associated with red, green or blue colors, or combinations thereof.  
     
     
         12 . The system of  claim 10 , wherein the at least one calibration parameter comprises parameters for red, green or blue colors, or combinations thereof.  
     
     
         13 . The system of  claim 10 , wherein said processing module is further capable of determining said at least one calibration parameter with respect to the image signal and a reference.  
     
     
         14 . The system of  claim 13 , further comprising a memory unit capable of storing the reference.  
     
     
         15 . A system comprising: 
 an image scanning device capable of calibrating illumination in a first direction and calibrating illumination in a second direction, the image scanning device comprising a calibration zone extending in the first direction and a calibration zone extending in a second direction, the image scanning device further comprising: 
 an optical scanning module;  
 at least one image sensing element disposed within the optical scanning module capable of detecting a first image signal of a first selected pixel and a second image signal of a second selected pixel of the calibration zone extending in the second direction;  
 at least one processing unit capable of: 
 comparing the first image signal with a reference to obtain a first comparison result;  
 comparing the first image signal with the second image signal to obtain a second comparison result;  
 manipulating the first comparison result and the second comparison result to determine at least one calibration parameter; and  
 calibrating an illumination of an image based, at least in part, on the at least one calibration parameter.  
 
   
     
     
         16 . The system of  claim 15 , wherein the first selected pixel is associated with red, green or blue colors, or combinations thereof.  
     
     
         17 . The system of  claim 15 , further comprising a memory unit capable of storing the reference.  
     
     
         18 . An image scanning device capable of calibrating illumination in a first direction and calibrating illumination in a second direction.  
     
     
         19 . The image scanning device of  claim 18 , further comprising: 
 an optical scanning module comprising at least one image sensing element, the at least one image sensing element capable of sensing an image signal of at least one selected pixel;    a back-light module capable of illuminating the optical scanning module; and    at least one processing module capable of obtaining an image signal of at least one selected pixel, wherein said processing module is further capable of obtaining at least one calibration parameter.    
     
     
         20 . A scanning method comprising: 
 illuminating a document; and    calibrating illumination in a first direction and calibrating illumination in a second direction.    
     
     
         21 . An apparatus for scanning comprising: 
 means for illuminating a document; and    means for calibrating illumination in a first direction and calibrating illumination in a second direction.