FORCE INVARIANT TOUCH SENSITIVE ACTUATOR

摘要

A user interface for a lighting control, the user interface comprising a touch sensitive front surface having a longitudinal axis and a lateral axis; a four-wire resistive touch pad responsive to a point actuation on the touch sensitive front surface, the resistive touch pad having a longitudinal resistive element for providing a first control signal representative of the position of the point actuation along the longitudinal axis, and a lateral resistive element for providing a second control signal representative of the position of the point actuation along the lateral axis; a controller operable to receive the first and second control signals; a first capacitor adapted to be coupled between the lateral resistive element and a circuit common, the first capacitor operable to charge and discharge through the longitudinal resistive element of the resistive touch pad to stabilize the first control signal; and first, second, and third switches responsive to the controller, each of the switches comprising first, second, and third terminals, and operable to be controlled between a first position in which the first terminal is electrically connected to the second terminal, and a second position in which the first terminal is electrically connected to the third terminal, the switches coupled to the touch sensitive device, such that when the controller controls all of the switches to the first position, a DC supply voltage is coupled across the longitudinal resistive element, the controller is coupled to the lateral resistive element, and the first capacitor is coupled between the lateral resistive element and the circuit common, and when the controller controls all of the switches to the second position, the DC supply voltage is coupled across the lateral resistive element and the controller is coupled to the longitudinal resistive element; wherein the controller is operable to determine, from the second control signal, if the touch sensitive front surface is presently being actuated, and to determine, from the first control signal, the position of the point actuation along the longitudinal axis.