Patent ID: 7598752
Filing Date: 2009-10-06
Classification: H03K

Abstract:
1. A touch sensing device comprising: a sensing point for producing a sensing capacitor; a power supply connected to a first switch for charging the sensing capacitor produced at the sensing point periodically; a second capacitor connected with the sensing capacitor via a second switch and the charge accumulated on the sensing capacitor is transferred to the second capacitor; a comparator for comparing voltage on the second capacitor with a reference voltage; a counter; a processor; wherein the processor performs the steps of a third switch; wherein the comparator produces a turnover signal and sends it to the third switch and the counter; wherein after receiving the turnover signal, the third switch is closed and the second capacitor discharges, the third switch opens after the discharge; and the counter stops counting after receiving the turnover signal and sends a count value to the processor which judges whether the sensing point is in touch state according to the count value, then the processor returns a signal and clears the counter, the counter restarts the count.