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US 7,321,200 B2Granted
Square wave drive system
AssigneeMicrosemi Corporation
InventorGeorge C. Henry
Life of this patent
Estimating the term…
Abstract
A power conversion circuit improves lamp operating life and lamp efficiency by driving a fluorescent lamp with a square wave signal. The square wave signal is an alternating current signal with relatively fast transition times. The square wave signal advantageously reduces lamp current crest factor for more efficient operation of the fluorescent lamp.
Claims18
A lamp inverter comprising:
- a pulse width modulation controller configured to output driving signals;
- a first semiconductor switch and a second semiconductor switch, wherein the first and second semiconductor switches are coupled to the pulse width modulation controller to receive the driving signals;
- a transformer having a primary winding and a secondary winding, the primary winding being coupled to the first and second semiconductor switches, the transformer being configured to produce a substantially square wave voltage at the secondary winding;
- and
- a fluorescent lamp coupled to receive the substantially square wave voltage from the secondary winding, wherein the secondary winding has a first terminal and a second terminal, and the first terminal is directly coupled through a direct current blocking capacitor to the fluorescent lamp.
2 more elements
A switching network for a fluorescent lamp, the switching network comprising:
- at least two semiconductor switches configured to receive a driving signal;
- and
- a transformer having a primary winding coupled to the at least two semiconductor switches, the transformer being configured to produce a substantially square wave voltage at a secondary winding in response to the driving signal, wherein the fluorescent lamp is directly coupled to the secondary winding through an alternating current (AC) coupling capacitor to receive the substantially square wave voltage.
A method for improving lamp lighting efficiency, the method comprising:
- supplying a substantially direct current supply voltage to a switching network having a transformer;
- providing driving signals to the switching network;
- producing a substantially square wave voltage at a secondary winding of the transformer;
- and
- coupling the substantially square wave voltage to a fluorescent lamp to generate light, wherein the fluorescent lamp is directly coupled to the secondary winding through a capacitor.
2 more elements
Dependencies are inferred from the claim text.