US Patent 7855543 Force invariant touch sensitive actuator

A load control device, such as a dimmer switch, has a touch sensitive actuator, such as a three-wire touch sensitive screen, that produces an output voltage representing the position of a manual pressure touch along a longitudinal axis of the actuator. A stabilizing circuit receives the output voltage of the actuator and comprises, for example, a capacitor. The stabilizing circuit operates to prevent the detection of transient touches and touches having less than a certain actuation force, such that the output voltage is responsive only to the position of the touch. In addition, a usage detection circuit may also be coupled to the output voltage of the actuator for determining whether the touch is presently occurring. Alternatively, the actuator may comprise a four-wire touch sensitive screen that produces a first output voltage received by the stabilizing circuit and a second output voltage received by the usage detection circuit.