Patent ID: 7999562

Claim:
A capacitive operator presence detector for an operator control handle, comprising: (a) a capacitive sensor having a ring shaped portion with an end, mounted in the handle at a first upper position along a longitudinal axis of the handle, and extending proximate a surface of the handle, the capacitive sensor arranged and configured to form a capacitor when the handle is touched by an operator; (b) a guard electrode separate from the capacitive sensor, having a ring shaped portion with an end, and extending proximate a surface of the handle, the guard electrode mounted in the handle at a second lower position along the longitudinal axis of the handle, the end of the guard electrode being adjacent the end of the capacitive sensor wherein the guard electrode is offset from the capacitive sensor along the longitudinal axis of the handle, the guard electrode arranged and configured to substantially isolate the capacitive sensor from ground when it is not touched by an operator; and (c) an operator presence circuit connected to the capacitive sensor and the guard electrode, the circuit having a node where a change in capacitance of the capacitive sensor is measured as a change in voltage and where the change in voltage is provided to the guard electrode, wherein the voltage at the guard electrode is equal to the voltage at the capacitive sensor and changes in capacitance due to water on the handle forming capacitance to ground are reduced.