Patent ID: 7069357
Filing Date: 2006-06-27
Classification: H03K

Abstract:
1. A method of sensing a touch, comprising the steps of: providing an AC power source having a line input and a line neutral; providing an isolated power supply connected to the AC power source and having a DC voltage source output; referencing the DC voltage source reference to ground; connecting an impedance limiting circuit to the output of the DC voltage source; connecting an analog-to-digital converter to the impedance limiting circuit; the analog-to-digital converter having a waveform output; connecting a processor to the analog-to-digital converter; connecting a touch sensor to the impedance limiting circuit; the touch sensor capable of being touched by a body part; capacitively coupling the touch sensor to the AC power source; monitoring the waveform output with the processor; calculating and saving the waveform output as an OFF reference waveform when the touch sensor is not being touched and the waveform output is stable; indicating lack of contact with the touch sensor by the body part when the waveform output is less than 2 times the OFF reference waveform; and indicating contact of the touch sensor by the body part when the waveform output is more than 2 times the OFF reference waveform.