Balancing transformers for multi-lamp operation
First Claim
Patent Images
1. A backlight system comprising:
- a plurality of lamp structures in a parallel configuration;
an alternating current source for powering the plurality of lamp structures;
a ring balancer coupled in series with the plurality of lamp structures, wherein the ring balancer comprises a plurality of balancing transformers with respective primary windings and respective secondary windings, each of the primary windings connected in series with at least one lamp structure, the secondary windings connected in series with each other; and
a fault detection circuit configured to monitor a plurality of node voltages in the secondary windings, to generate a feedback voltage corresponding to at least one of the plurality of node voltages, and to compare the feedback voltage with a reference voltage to determine a fault condition.
9 Assignments
0 Petitions
Accused Products
Abstract
A ring balancer comprising a plurality of balancing transformers facilitates current sharing in a multi-lamp backlight system. The balancing transformers have respective primary windings separately coupled in series with designated lamps and have respective secondary windings coupled together in a closed loop. The secondary windings conduct a common current and the respective primary windings conduct proportional currents to balance currents among the lamps. The ring balancer facilitates automatic lamp striking and the lamps can be advantageously driven by a common voltage source.
-
Citations
20 Claims
-
1. A backlight system comprising:
-
a plurality of lamp structures in a parallel configuration; an alternating current source for powering the plurality of lamp structures; a ring balancer coupled in series with the plurality of lamp structures, wherein the ring balancer comprises a plurality of balancing transformers with respective primary windings and respective secondary windings, each of the primary windings connected in series with at least one lamp structure, the secondary windings connected in series with each other; and a fault detection circuit configured to monitor a plurality of node voltages in the secondary windings, to generate a feedback voltage corresponding to at least one of the plurality of node voltages, and to compare the feedback voltage with a reference voltage to determine a fault condition. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16)
-
-
17. A method to balance currents among multiple parallel branches of lamps in a backlight system and to detect a fault condition, the method comprising the steps of:
-
providing a ring balancer in series with a plurality of lamp structures, wherein the ring balancer comprises a plurality of balancing transformers with respective primary and respective secondary windings; connecting the primary windings of the balancing transformers in series with the one lamp structures; connecting secondary windings of said balancing transformers in series with each other such that a common current circulates in the secondary windings when at least one lamp structure is lit; monitoring a plurality of node voltages in the secondary windings to detect a fault condition; and turning off the alternating current source when the fault condition occurs. - View Dependent Claims (18, 19, 20)
-
Specification