Abstract
The invention relates to a pen input system and input method thereof used to input a text and graphics data comprising a light pen for outputting an optical signal, an electronic screen equipped with a light point location detector for detecting the light point location of the optical signal projected on the electronic screen and a signal processing unit in connection with the electronic screen for outputting a corresponding text and graphics data in terms of the light point location of the optical signal. In addition to providing more reliable and higher resolution electronic screen function, the system also provides a low-cost and remote writing function adapted for large conference and can solve noise issue of hand pressure on conventional electronic screen.