Digitally controlled electronic ballast with anti-striation control and method of operation thereof
AssigneeKoninklijke Philips N.V.
InventorsWilliam Lawrence Keith, George Gruev
Life of this patent
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Abstract
An apparatus to supply power to at least one gas lamp, the apparatus including a half bridge driver having a striation control circuit which determines an on time (Ton) for a cycle in accordance with a fifty percent duty cycle, the cycle having a plurality of segments and lasting for a predetermined period of time and modulates on times Ton1 and Ton2 of first and second power switches, respectively, of a half-bridge circuit in accordance with a striation control technique for each of the plurality of segments.
Claims20
An apparatus to supply power to at least one gas lamp, the apparatus comprising a half bridge driver having a striation control circuit which:
- determines an on time (Ton) for a cycle in accordance with a fifty percent duty cycle, the cycle having a plurality of segments and lasting for a predetermined period of time;
- and
- modulates on times Ton1 and Ton2 of first and second power switches, respectively, of a half-bridge circuit in accordance with a striation control technique while maintaining the fifty percent duty cycle for Ton1 and Ton2 for each of the plurality of segments.
The apparatus of claim′, wherein the striation control circuit modulates Ton1 and Ton2 differently from each other within a given segment of each of the plurality of segments within the cycle while maintaining the fifty percent duty cycle for Ton1 and Ton2.
A method to control a switching half-bridge circuit to supply power to a load, the method comprising one or more acts which are performed by a processor, the acts comprising:
- determining an on time (Ton) for a cycle in accordance with a fifty percent duty cycle, the cycle having a plurality of segments and lasting for a predetermined period of time;
- and
- modulating on times Ton1 and Ton2 of first and second power switches, respectively, of a half-bridge circuit in accordance with a striation control technique while maintaining the fifty percent duty cycle for Ton1 and Ton2 for each of the plurality of segments.
A computer program stored on a computer readable non-transitory memory medium, the computer program configured to supply power to at least one gas lamp, the computer program comprising:
- a program portion configured to:
- determine an on time (Ton) for a cycle in accordance with a fifty percent duty cycle, the cycle having a plurality of segments and lasting for a predetermined period of time;
- modulate on times Ton1 and Ton2 of first and second power switches, respectively, of a half-bridge circuit in accordance with a striation control technique while maintaining the fifty percent duty cycle for Ton1 and Ton2 for each of the plurality of segments;
- and
- generate first and second control signals for driving the first and second power switches, respectively, in accordance with Ton1 and Ton2, respectively.
A ballast for providing power to a fluorescent lamp, the ballast comprising:
- a half bridge circuit having first and second switches in series with each other and an output for providing power to the fluorescent lamp;
- a power supply circuit to regulate a direct current (DC) voltage supplied to an input of the half bridge;
- a regulator configured to determine an on time (Ton) corresponding with a fifty percent duty cycle for a cycle having a plurality of segments and a modulating value M(i) for each of the plurality of segments (i) and to generate a first signal to drive the first switch with a first on time (Ton1) and a second signal to drive the second switch with a second on time (Ton2) such that Ton1=Ton+M(i) and Ton2=Ton−M(i) for each of the plurality of segments of the cycle while maintaining the fifty percent duty cycle Ton1 and Ton2.
Dependencies are inferred from the claim text.