Patent ID: 6501281
Filing Date: 2002-12-31
Classification: A01D,G01D,H03K

Abstract:
A capacitive, operator-sensing circuit for sensing the presence of a hand of an operator on a gripping surface of a unit of power equipment having an internal combustion engine and shutting off the engine if the operator's hand is removed from the gripping surface, the operator-sensing circuit comprising:a) a sensing electrode affixed to the gripping surface, a quantity of charge present on the sensing electrode having a first value if the operator's hand overlies a portion of the sensing electrode and having a second value if the operator's hand does not overlie the sensing electrode; b) a charge-transfer sensor electrically coupled to the sensing electrode periodically transferring charge to the sensing electrode and sensing the quantity of charge on the sensing electrode, an output of the charge-transfer sensor generating a first output signal when the first value of the sensed charge on the sensing electrode is sensed and a second output signal, different from the first output signal, when the second value of the sensed charge on the sensing electrode is sensed; and c) coupling circuity electrically coupling a magneto of the engine and the charge-transfer sensor for grounding the engine magneto and thereby shutting off the engine when the second output signal is generated by the charge-transfer sensor.