Force invariant touch sensitive actuator

A user interface for a lighting control, the user interface comprising:

• a touch sensitive front surface having a longitudinal axis;
• a touch sensitive device responsive to a point actuation on the touch sensitive front surface, the point actuation characterized by a force and a position along the longitudinal axis of the touch sensitive front surface, the touch sensitive device comprising a resistive divider and an output for providing a control signal;
• and
• a capacitor coupled to the output of the touch sensitive device for stabilizing the control signal;
• wherein the capacitor is operable to charge and discharge through the resistive divider of the touch sensitive device, such that the control signal is representative of the position of the point actuation.

A load control device for controlling an amount of power delivered to an electrical load from an AC power source, the load control device comprising:

• a touch sensitive front surface;
• a semiconductor switch operable to be coupled in series electrical connection between the source and the load, the semiconductor switch having a control input for controlling the semiconductor switch between a non-conductive state and a conductive state;
• a controller operatively coupled to the control input of the semiconductor switch for controlling the semiconductor switch between the non-conductive state and the conductive state;
• a touch sensitive device responsive to a point actuation on the touch sensitive front surface, the point actuation characterized by a position and a force, the touch sensitive device comprising a resistive divider and an output for providing a control signal;
• a usage detection circuit operatively coupled between the output of the touch sensitive device and the controller for determining if the point actuation is presently occurring;
• and
• a stabilizing circuit operatively coupled between the output of the touch sensitive device and the controller, the stabilizing circuit comprising a whacking-grade capacitor for stabilizing the control signal of the touch sensitive device, the capacitor operable to charge and discharge through the resistive divider of the touch sensitive device, such that the control signal is representative of the position of the point actuation;
• wherein the controller is responsive to the control signal only when the point actuation is presently occurring.

A user interface for a lighting control, the user interface comprising:

• a touch sensitive front surface;
• a touch sensitive device responsive to a point actuation on the touch sensitive front surface, the point actuation characterized by a position and a force, the touch sensitive device comprising a resistive divider and an output for providing a control signal representative of the position of the point actuation;
• a usage detection circuit operatively coupled to the output of the touch sensitive device for determining if the point actuation is presently occurring;
• a stabilizing circuit operatively coupled to the output of the touch sensitive device and comprising an output, the stabilizing circuit comprising a whacking-grade capacitor for stabilizing the control signal of the touch sensitive device, the capacitor operable to charge and discharge through the resistive divider of the touch sensitive device, such that the control signal is representative of the position of the point actuation;
• and
• a controller coupled to the usage detection circuit and the output of the stabilizing circuit, the controller operable to determine when the point actuation is presently occurring in response to the usage detection circuit, the controller responsive to the control signal only when the point actuation is presently occurring.

A method of receiving a control signal from a touch sensitive device, the touch sensitive device comprising a resistive element and responsive to an operating pressure applied thereto, the method comprising the steps of:

• generating a touch control signal in response to the operating pressure being applied to the touch sensitive device, the touch control signal representative of the position at which the operating pressure is applied to the touch sensitive device;
• filtering the touch control signal with a capacitor to generate a filtered control signal using a time constant ranging from approximately 6 milliseconds to 15 milliseconds, wherein the capacitor is operable to charge and discharge through the resistive element;
• monitoring the touch control signal to determine if the position at which the operating pressure is applied to the touch sensitive device is presently changing;
• and
• determining the position at which the operating pressure is applied to the touch sensitive device from the filtered control signal in response to the step of monitoring.