Multiple light sensor module position scanning method

A method of image scanning used in a scanner, the scanner having a light source for illuminating a document to be scanned, and a scanning module for scanning the document, the scanning module having a light sensor module for receiving light from the document and generating an image signal of the document, and a light delivery module for delivering the light to the light sensor module, the light sensor module capable of moving along a first direction and capable of being positioned on at least a first position and a second position, the method comprising:

• positioning the light sensor module on the first position, and using the light source and the scanning module to scan a reference picture to obtain a first reference image signal;
• positioning the light sensor module on the second position, and using the light source and the scanning module to scan the reference picture to obtain a second reference image signal;
• positioning the light sensor module on the first position or the second position according to the first and the second reference image signals;
• and
• scanning the document;
• wherein if flawed areas in the first reference image signal are fewer than flawed areas in the second reference image signal, the light sensor module is positioned on the first position to scan the document, and if flawed areas on the second reference image signal are fewer than flawed areas on the first reference image signal, the light sensor module is positioned on the second position to scan the document.