Image scanner capable of scanning reflective and penetrative documents

An image scanner capable of scanning reflective and penetrative documents, comprising:

• a housing;
• a supporting base mounted in said housing and moving along a first direction while the scanning operation is performed;
• a first scanning platform mounted on said housing for placing thereon said reflective document to be scanned;
• a first light transmitting device mounted fixedly on said supporting base for focusing and transmitting light signal reflected from said reflective document to said first photoelectric sensing element;
• a first photoelectric sensing element mounted fixedly on said supporting base and having a first number of pixel sensing points for receiving said reflected light signal and converting said received light signal into electric signal;
• a second scanning platform mounted in said housing for placing thereon said penetrative document to be scanned;
• a second light transmitting device mounted fixedly on said supporting base for focusing and transmitting light signal penetrating through said penetrative document to said second photoelectric sensing element;
• and
• a second photoelectric sensing element mounted fixedly on said supporting base and having a second number of pixel sensing points for receiving said penetrating light signal and converting said penetrating light signal into electric signal, where in said first number is larger than said second number.