Back to results
US 4,388,563 AGranted
Solid-state fluorescent lamp ballast
AssigneeCommodore Electronics Limited
InventorTom M. Hyltin
Life of this patent
Estimating the term…
Abstract
An improved solid-state fluorescent lamp ballast circuit in which rectified line voltage is chopped, utilizing high power field effect transistors, to provide a high frequency input to a fluorescent lamp, thus permitting smaller reactive components to be utilized. Also shown is circuitry whereby the duty cycle of the chopping switches may be modulated to permit dimming of the lamp, which may be remotely located.
Claims12
A solid-state dimmable fluorescent lamp ballast circuit comprising:
- rectification means for supplying a unipolar electrical voltage;
- a first switch adapted to couple a first side of the output of said rectification means to one side of a gaseous discharge lamp;
- a second switch adapted to couple said first side of the output of said rectification means to the other side of a gaseous discharge lamp;
- a third switch adapted to couple a second side of the output of said rectification means to said one side of a gaseous discharge lamp;
- a fourth switch adapted to couple said second side of the output of the said rectification means to said other side of a gaseous discharge lamp;
- control means for providing first and second complementary pulse trains and third and fourth variable duty cycle pulse trains, said first pulse train being coupled to said first switch, said second pulse train being coupled to said second switch, said third pulse train being coupled to said third switch and said fourth pulse train being coupled to said fourth switch wherein said fourth switch is closed for a variable percentage of the time said first switch is closed and said third switch is closed for a variable percentage of the time said second switch is closed, said control means comprising:
- oscillator means for providing an output having a first frequency;
- multiple stage divider means coupled to said oscillator means for providing an output at a second frequency;
- first means coupled to the output of said multiple stage divider for providing said first and second pulse trains;
- second means selectively coupled to at least one intermediate stage of said multiple stage divider for providing said third and fourth pulse trains;
- and
- means for varying the duty cycle of third and fourth pulse trains.
9 more elements
Dependencies are inferred from the claim text.