PHASE-CUT DIMMER DEVICE AND METHOD OF PHASE-CUT DIMMING FOR A LIGHTING UNIT CONTROLLED BY A ROCKER-TYPE USER INTERFACE

摘要

A device (500) and method (600) control a dimming level of one or more lighting units (130) in response to a user interaction with a reference-free user interface (410), such as a rocker-type interface. A bidirectional triode thyristor (460) supplies an AC input voltage (110) to the lighting unit(s) when it is triggered. A triggering circuit (510) triggers the bidirectional triode thyristor. The triggering circuit includes a capacitor (554) and a variable resistance element (510) which sets a time constant during each half cycle of a period of the AC input voltage for charging the capacitor to a triggering voltage which triggers the bidirectional triode thyristor. The resistance of the variable resistance element is controlled in response to a dimming input signal from the reference-free user interface. The dimming input signal indicates only relative changes in the output level of the lighting unit(s) with respect to the present level.