Patent ID: 8884898

Claim:
A touch sensing device, comprising: a touch sensing circuit, having a conducting unit for generating an alternating current (AC) touch signal when the conducting unit is within a predetermined distance from a conductor carrying electrons; a phase delaying circuit, electrically coupled to the touch sensing circuit, for receiving the AC touch signal from the touch sensing circuit and delaying the AC touch signal for a predetermined phase so as to derive a delayed signal; and a determination circuit, electrically coupled to the touch sensing circuit and the phase delaying circuit, for comparing intensities of the delayed signal and the AC touch signal with a predetermined threshold in order to derive a waveform-overlapping time period during which the delayed signal and the AC touch signal overlap and the intensities thereof are larger than the predetermined threshold; wherein when the waveform-overlapping time period is longer than a predetermined period the determination circuit concludes the conducting unit is approached or contacted by the conductor carrying the electrons, otherwise the determination circuit concludes the conductor carrying the electrons fails to contact or be approaching the conducting unit.