Dimmer for fluorescent lighting
First Claim
1. 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; and
processor 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.
1 Assignment
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Accused Products
Abstract
A dimmer applies a phase-controlled AC voltage to a lighting assembly which includes a fluorescent lamp operated with a magnetic ballast. A microprocessor performs a calibration routine in which the phase angle used in phase control is increment from 0 toward 180 degrees. The microprocessor monitors current conducted by the lighting assembly in response to each incrementing, effectively determining an operative range of phase angles free of flickering or drop-out. During steady-state operation, the microprocessor converts nominal power settings into corresponding phase angle settings within the operative range, preventing operation in undesirable states.
33 Citations
11 Claims
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1. 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:
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sensing means for sensing current conducted by the assembly in response to the applied voltage; and processor 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. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11)
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Specification