System for controlling driving lamp of backlight unit

1. A system for controlling a driving lamp of a backlight unit comprising:

a liquid crystal display panel;

a lamp for emitting light to the liquid crystal display panel;

a timing controller for generating a lamp control signal to control a light-on time of the lamp; and

an inverter for controlling a light-on and a light-off of the lamp according to the lamp control signal while limiting current and maintaining a constant wattage of the power supplied to the lamp regardless of the light-on time for the lamp, wherein the inverter is provided with a comparing unit for supplying a signal to a lamp controller when the current of the lamp exceeds an established value, and

wherein the inverter includes:

an oscillator for generating an alternating current, wherein the oscillator includes: a plurality of first switching devices that conduct or block in accordance with a first control signal; a plurality of second switching devices that conduct or block in accordance with a second control signal; and a sensing resistance for detecting power of the oscillator, wherein the first and second pluralities of switching devices are alternately conducting or blocking in accordance with the first and second control signals;

a lamp controller for controlling the generation of the alternating current in the oscillator during an established time in accordance with the lamp control signal of the timing controller, and adjusting power applied to the oscillator in accordance with a reference power level, wherein the lamp controller alternately outputs a first control signal and a second control signal to control the generation of current in the oscillator, and wherein the lamp controller compares the detected power with a reference power, and establish a reference voltage according to a difference therebetween so that the lamp controller increases the reference voltage when the power of the oscillator is lower than the reference power, and wherein the lamp is turned on while the first and second control signals are supplied from the lamp controller to the oscillator in each frame, and wherein the lamp controller adjusts a conducting time of the first and second switching devices of the oscillator by the first and second control signals, to adjust an amplitude of the current generated by the oscillator from the reference voltage; and

a transformer for converting the alternating current generated from the oscillator to a high voltage that is supplied to the lamp.

2. The system of claim 1 , wherein the oscillator is a full-bridge circuit including four switching devices.

3. The system of claim 1 , wherein the first and second switching devices are thin film transistors.

4. The system of claim 1 , wherein the first and second control signals are pulse type signals.

5. The system of claim 4 , wherein the first and second control signals have a frequency of 60 to 65 kHz.

6. The system of claim 4 , wherein the second control signal is a pulse signal that is a reverse of the first control signal.

7. The system of claim 1 , wherein the established value is a maximum permissible current of the lamp.

8. The system of claim 1 , wherein the comparing unit is included in the lamp controller.

9. A system for controlling a driving lamp of a backlight unit comprising:

a liquid crystal display panel;

a lamp for emitting light to the liquid crystal display panel;

a timing controller for outputting a lamp control signal, wherein the timing controller generates the lamp control signal to control a light-on time of the lamp;

an inverter for controlling a light-on and a light-off of the lamp according to the lamp control signal while limiting current and maintaining a constant wattage of the power supplied to the lamp regardless of the light-on time for the lamp, wherein the inverter includes:

an oscillator for generating an alternating current by conducting and blocking with a first set of switching devices and a second set of switching devices, wherein an amplitude of an alternating current generated from the oscillator is determined according to a reference voltage;

a lamp controller for providing switching signals to the first and second sets of switching devices, monitoring the power of the oscillator and adjusting a conducting time of the first set of switching devices and the second set of switching devices according to a difference between the monitored power and a reference power, wherein the lamp controller clamps the amplitude of the current generated by adjusting a conducting time of the first and second switching devices of the oscillator according to a signal from a comparing unit, wherein the lamp controller compares the detected power with a reference power, and establish a reference voltage according to a difference therebetween so that the lamp controller increases the reference voltage when the power of the oscillator is lower than the reference power, and the lamp is turned on while the first and second control signals are supplied from the lamp controller to the oscillator in each frame, and wherein the lamp controller adjusts a conducting time of the first and second switching devices of the oscillator by the first and second control signals, to adjust an amplitude of the current generated by the oscillator from the reference voltage; and

a transformer for converting the alternating current generated from the oscillator into high voltage that is applied to the lamp,

wherein the comparing unit limits the current of the lamp, and wherein the comparing unit monitors the current of the lamp and outputs a signal to the lamp controller when the monitored current is higher than a predetermined maximum value, wherein the comparing unit is included in the lamp controller.