Dimmable, high power factor ballast for gas discharge lamps
First Claim
1. A ballast for operating a gas discharge lamp, comprising:
- a power factor correction circuit and an energy storage capacitor coupled to the output thereof, the power factor correction circuit being configured to draw current from an AC power source during substantially more than half of the cycle of the input AC voltage waveform when substantially full power is being supplied thereto, the power factor correction circuit comprising energy transfer elements for extracting energy from the AC power source via an input rectifier, even when the peak voltage of the AC voltage waveform is substantially lower than the voltage of the energy storage capacitor, and transferring the energy to the energy storage capacitor a sufficient number of times during each cycle of the input AC voltage waveform, such that the energy storage capacitor remains substantially fully charged during steady-state ballast operation;
an inverter coupled to the power factor correction circuit, the energy storage capacitor providing DC power for the inverter; and
a starting circuit coupled for receiving AC power from the inverter and initiating a discharge in the lamp.
2 Assignments
0 Petitions
Accused Products
Abstract
A ballast for operating a compact fluorescent lamp includes a power factor correction circuit and an energy storage capacitor coupled to the output thereof. The power factor correction circuit is configured to draw current from an AC power source during substantially more than half of the cycle of the input AC voltage waveform; i.e., when operated such that full power is supplied to the lamp. Energy transfer elements in the power factor correction circuit extract energy from the AC power source via an input rectifier, even when the peak voltage of the AC voltage waveform is substantially lower than the voltage of the energy storage capacitor, and transfer the energy to the energy storage capacitor a sufficient number of times during for each cycle of the input AC voltage waveform (e.g., at least 500 times for each full cycle of a 60 Hz input AC voltage waveform for a lamp operated at a frequency of 30 kHz), such that the energy storage capacitor remains substantially fully charged during steady-state ballast operation. The power factor circuit additionally provides for improved dimming capability, specifically, dimming the discharge to low levels, while maintaining steady, non-flickering operation.
34 Citations
20 Claims
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1. A ballast for operating a gas discharge lamp, comprising:
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a power factor correction circuit and an energy storage capacitor coupled to the output thereof, the power factor correction circuit being configured to draw current from an AC power source during substantially more than half of the cycle of the input AC voltage waveform when substantially full power is being supplied thereto, the power factor correction circuit comprising energy transfer elements for extracting energy from the AC power source via an input rectifier, even when the peak voltage of the AC voltage waveform is substantially lower than the voltage of the energy storage capacitor, and transferring the energy to the energy storage capacitor a sufficient number of times during each cycle of the input AC voltage waveform, such that the energy storage capacitor remains substantially fully charged during steady-state ballast operation; an inverter coupled to the power factor correction circuit, the energy storage capacitor providing DC power for the inverter; and a starting circuit coupled for receiving AC power from the inverter and initiating a discharge in the lamp. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 17)
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11. A method for operating a gas discharge lamp, comprising:
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providing an input power factor correction circuit and an energy storage capacitor coupled to the output thereof; operating the power factor correction circuit to draw current from an AC power source during substantially more than half of the cycle of the input AC voltage waveform when substantially full power is being supplied thereto; extracting energy from the AC power source via an input rectifier, even when the peak voltage of the AC voltage waveform is substantially lower than the voltage of the energy storage capacitor; transferring energy to the energy storage capacitor a sufficient number of times during each cycle of the input AC voltage waveform, such that the energy storage capacitor remains substantially fully charged during steady-state ballast operation; providing DC power to the inverter via the energy storage capacitor; and providing AC power from the inverter to a starting circuit and initiating a discharge in the lamp. - View Dependent Claims (12, 13, 14, 15, 16, 18, 19, 20)
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Specification