Dual optical module scanning mechanism

A driving mechanism for a scanning optical system housed in a scanner frame, comprising:

• a first optical module for scanning a document having:
• light source for generating a light ray to illuminate said document and a first mirror for reflecting the reflected light ray from said document to form a second light ray;
• a first driving wheel for said first optical module;
• a second driving wheel;
• a first conveyer stretched between two points on opposite side walls of said scanner frame and in friction contact with said first driving wheel;
• a second optical module having at least a second mirror for reflecting the second light ray toward said image sensor;
• and
• a second conveyer fastened to two opposite sides of said second optical module, driven by said driving wheel, pulling said second optical module away from said first optical module when said first driving wheel and said second driving wheel rotate in opposite angular direction whereby said first optical module moves slower than said second optical module such that said first optical module moves at one half the speed of said second optical module.