Patent ID: 8395592

Claim:
A sensing system, comprising: a plurality of input areas, arranged on a display device, receiving a first input on a first point at a current time and a second input on a second point at a previous time and generating input signals accordingly; and a processing device comprising: a multiplexer having a plurality of input ends, a selecting end and an output end and electrically coupled with the plurality of input areas via the plurality of input ends, for receiving the respective input signals, and receiving a selecting signal via the selecting end for selectively outputting an analog signal accordingly; an analog to digital converter electrically coupled with the output end of the multiplexer, receiving the analog signal and transforming the analog signal into a digital signal; and a micro control unit electrically coupled with the analog to digital converter and generating the selecting signal, in which the micro control unit is electrically coupled with the plurality of input areas and executing a validation criterion comprising a first mode and a second mode by which the micro control unit calculates an absolute distance between the first point and the second point and performs the first mode to activate the input areas on which the first and the second points are respectively situated as active areas if the absolute distance is not smaller than a threshold and performs the second mode to draw a straight line between the first and the second points on the display device if the absolute distance is smaller than the threshold.