Fixed operating frequency inverter for cold cathode fluorescent lamp having strike frequency adjusted by voltage to current phase relationship
0 Assignments
0 Petitions
Accused Products
Abstract
A method of driving a lamp that uses a DC to AC inverter that is connected to a primary winding of a transformer is disclosed. The inverter frequency is variable, and in one embodiment, may be controlled by a voltage controlled oscillator. Circuitry is included that monitors the phase relationship between a voltage across a secondary of the transformer and a current through the primary of the transformer. The circuitry monitors the phase relationship and adjusts the inverter frequency, such as by adjusting voltage controlled oscillator, so that the phase relationship is maintained at a predetermined relationship.
-
Citations
21 Claims
-
1-13. -13. (canceled)
-
14. A method of driving a lamp that uses a DC to AC inverter that is connected to a winding of a transformer comprising:
-
(a) monitoring the phase relationship between a voltage across said winding of said transformer and a current through said winding of said transformer; and
(b) keeping said phase relationship between said voltage across said winding of said transformer and said current through said winding of said transformer at substantially a predetermined relationship. - View Dependent Claims (15, 16, 17)
-
-
18. An apparatus for driving a lamp comprising.
a transformer having a primary and a secondary; -
means for converting a DC power into AC power and operating at a frequency, the means for converting driving the primary of said transformer;
means for phase comparison that monitors the phase relationship between a voltage across said primary of said transformer and a current through said primary of said transformer; and
means for frequency control that adjusts the frequency of said means for converting such that said phase relationship between said voltage across said primary of said transformer and said current through said primary of said transformer is maintained at substantially a predetermined relationship. - View Dependent Claims (19, 20, 21)
-
Specification