Patent ID: 7795882
Filing Date: 2010-09-14
Classification: H03K

Abstract:
1. Operator sensing circuit for a hand-grip of a device, comprising: at least one capacitive sensing element incorporated in said hand-grip, said sensing element having a capacity which is changed in a hands-on state of an operator's hand on said hand-grip when compared with a hands-off state of said hand-grip, a charge sensor detecting at least a capacity of said sensing element and generating a capacity signal value representing said detected capacity, said charge sensor further detecting a capacity of a capacitive reference simulator element and generating a reference signal value indicative of said capacity, a controller connected to said charge sensor, said controller receiving said reference signal value and comparing said reference signal value with a preselected stored reference range in order to determine proper operative conditions of said sensing circuit if said reference signal value is within said reference range, said controller receiving said capacity signal value and comparing said capacity signal value with a preselected hands-on capacity signal value in order to distinguish between a proper hands-on state which is present if the capacity signal value is on a first side of said hands-on capacity signal value or a non-proper hands-on state, which is present if the capacity signal value is on a second side of said hands-on capacity signal value; said hands-on capacity signal value being chosen to differentiate between (i) at least one of dirt and water on the hand-grip, and (ii) one of the operator's hand and the operator's hand in a glove on the hand-grip.