Patent ID: 6133696
Filing Date: 2000-10-17
Classification: H05B,Y10S

Abstract:
A dimmer adapted to apply an AC voltage to a lighting assembly comprising a fluorescent lamp and a magnetic ballast, the dimmer comprising setting means for specifying nominal power settings for the lighting assembly and control means for applying phase control to an applied voltage in each half-cycle of the applied voltage, characterized in that the control means comprise:sensing means for sensing current conducted by the assembly in response to the applied voltage; andprocessor means responsive to the sensing means and to the setting means for specifying phase angles for phase control of the applied voltage, the processor means comprising a calibration mode of operation in which the processor means specify different phase angles for phase control of the applied voltage and monitor the current at each of the specified phase angle to determine an operative range of phase angles and comprising a steady-state mode of operation in which the processor means convert nominal power settings specified with the setting means into corresponding phase angles within the operative range, the control means specifying such corresponding phase angles for phase control of the voltage.