Open loop bi-level ballast control
AssigneeKoninklijke Philips Electronics N.V.
InventorRobert A. Erhardt
Life of this patent
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Abstract
A system and method for open loop bi-level ballast control providing multiple levels of illumination from a ballast-driven lamp. Power to a lamp is adjusted in response to a lamp control signal by adjusting the frequency driving the ballast powering the lamp. Line voltage feeds an AC/DC converter, which supplies DC voltage to a high frequency (HF) ballast. A frequency control circuit responds to a lamp control signal and supplies a ballast frequency signal to the HF ballast, which responds to the ballast frequency signal and adjusts the current supplied to the lamp accordingly. In one embodiment, the lamp control signal can be a bi-level signal providing bi-level illumination.
Claims27
A circuit for bi-level control of a lamp, comprising:
- a frequency control circuit responsive to a lamp control signal and providing a ballast frequency signal;
- and
- an HF ballast responsive to the ballast frequency signal, the HF ballast providing power to the lamp;
- wherein the ballast frequency signal regulates the frequency of the HF ballast to adjust the power to the lamp.
A system for bi-level control of a lamp, comprising:
- means for controlling frequency responsive to a lamp control signal and providing a ballast frequency signal;
- and
- means for generating power responsive to the ballast frequency signal, the power generating means providing power to the lamp;
- wherein the ballast frequency signal regulates the frequency of the power generating means to adjust the power to the lamp.
A method for bi-level control of a lamp in response to a lamp control signal, comprising:
- providing the lamp control signal to a frequency control circuit;
- generating a ballast frequency signal from the frequency control circuit in response to the lamp control signal;
- providing the ballast frequency signal to an HF ballast;
- regulating the frequency of the HF ballast in response to the ballast frequency signal to adjust the power to the lamp.
Dependencies are inferred from the claim text.