Backlight unit and liquid crystal display device including the same
View Patent ↗A backlight unit of a liquid crystal display includes a lamp, a balancing pattern capacitor electrically connected to the lamp for current balance, a transformer electrically connected to the lamp via the balancing pattern capacitor, a sensing pattern capacitor electrically connected to a terminal of the balancing pattern capacitor connected to the lamp to detect an abnormal driving state of the lamp, and a feedback circuit unit electrically connected to the sensing pattern capacitor to control the abnormal driving state of the lamp. A liquid crystal display device including the backlight unit is also disclosed.
1. A backlight unit of a liquid crystal display, comprising:
a lamp;
a balancing capacitor electrically connected to the lamp balancing current to the lamp;
a transformer providing power to the lamp, the transformer electrically connected to the lamp via the balancing capacitor;
a sensing capacitor electrically connected to a terminal of the balancing capacitor to detect a voltage across the balancing capacitor; and
a feedback circuit electrically connected to the sensing capacitor to detect an abnormal driving state of the lamp.
2. The backlight unit of claim 1 , wherein the lamp comprises a cold cathode fluorescence lamp.
3. The backlight unit of claim 1 , wherein a first electrode terminal of the lamp is connected to a circuit including the balancing capacitor, the transformer, the sensing capacitor, and the feedback circuit unit, and a second electrode terminal of the lamp is electrically grounded.
4. The backlight unit of claim 1 , wherein both the first and second electrode terminals of the lamp are electrically connected to a circuit including the balancing capacitor, the transformer, the sensing capacitor, and the feedback circuit.
5. The backlight unit of claim 1 , wherein the feedback circuit detects the abnormal driving state of the lamp using a voltage applied from the balancing capacitor to the sensing capacitor.
6. The backlight unit of claim 1 , wherein a first terminal of the balancing capacitor is connected to the lamp and not the transformer and a second terminal of the balancing capacitor is connected to the transformer and not the lamp.
7. A backlight unit of a liquid crystal display, comprising:
a lamp;
a balancing capacitor electrically connected to the lamp balancing current to the lamp;
a transformer providing power to the lamp, the transformer electrically connected to the lamp via the balancing capacitor;
a sensing capacitor electrically connected to a terminal of the balancing capacitor to detect a voltage across the balancing capacitor; and
a feedback circuit electrically connected to the sensing capacitor to detect an abnormal driving state of the lamp,
wherein the balancing capacitor comprises:
a first printed circuit board (“PCB”) substrate;
a first conductive layer electrically connected to a first face of the first PCB substrate and to the transformer; and
a second conductive layer electrically connected to a second face of the first PCB substrate and the lamp, the second face opposing to the first face of the first PCB substrate.
8. The backlight unit of claim 7 , wherein the sensing capacitor comprises:
the second conductive layer;
a second PCB substrate electrically connected to the second conductive layer at a first face of the second PCB substrate; and
a third conductive layer formed on a second face of the second PCB substrate opposing to the first face of the second PCB substrate, and electrically connected to the second PCB substrate.
9. The backlight unit of claim 8 , wherein the second PCB substrate is electrically connected to the feedback circuit.
10. The backlight unit of claim 8 , wherein the first, second, and third conductive layers each comprise a metal foil.
11. A liquid crystal display device, comprising:
a liquid crystal display panel displaying images; and
a backlight unit to supply light to the liquid crystal display panel,
wherein the backlight unit comprises:
a lamp;
a balancing capacitor electrically connected to the lamp for balancing current to the lamp;
a transformer providing power to the lamp, the transformer electrically connected to the lamp via the balancing capacitor;
a sensing capacitor electrically connected to a terminal of the balancing capacitor to detect a voltage across the balancing capacitor; and
a feedback circuit electrically connected to the sensing capacitor to detect an abnormal driving state of the lamp.
12. The liquid crystal display device of claim 11 , wherein the lamp comprises a cold cathode fluorescence lamp.
13. The liquid crystal display device of claim 11 , wherein a first electrode terminal of the lamp is connected to a circuit including the balancing capacitor, the transformer, the sensing capacitor, and the feedback circuit unit, and wherein a second electrode terminal of the lamp is electrically grounded.
14. The liquid crystal display device of claim 11 , wherein both the first and second electrode terminals of the lamp are electrically connected to the circuit including the balancing capacitor, the transformer, the sensing capacitor, and the feedback circuit.
15. The liquid crystal display device of claim 11 , wherein the feedback circuit detects the abnormal driving state of the lamp using voltages applied from the balancing capacitor to sensing capacitor.
16. The liquid crystal display device of claim 11 , wherein a first terminal of the balancing capacitor is connected to the lamp and not the transformer and a second terminal of the balancing capacitor is connected to the transformer and not the lamp.
17. A liquid crystal display device, comprising:
a liquid crystal display panel displaying images; and
a backlight unit to supply light to the liquid crystal display panel,
wherein the backlight unit comprises:
a lamp;
a balancing capacitor electrically connected to the lamp for balancing current to the lamp;
a transformer providing power to the lamp, the transformer electrically connected to the lamp via the balancing capacitor;
a sensing capacitor electrically connected to a terminal of the balancing capacitor to detect a voltage across the balancing capacitor; and
a feedback circuit electrically connected to the sensing capacitor to detect an abnormal driving state of the lamp,
wherein the balancing capacitor comprises:
a first PCB substrate; and
a first conductive layer electrically connected to a first face of the first PCB substrate and to the transformer; and
a second conductive layer electrically connected to a second face of the first PCB substrate and the lamp, the second face opposing to the first face of the first PCB substrate.
18. The liquid crystal display device of claim 17 , wherein the sensing capacitor comprises:
the second conductive layer;
a second PCB substrate electrically connected to the second conductive layer at a first face of the second PCB substrate; and
a third conductive layer formed on a second face of the second PCB substrate opposing to the first face of the second PCB substrate, and electrically connected to the second PCB substrate.
19. The liquid crystal display device of claim 18 , wherein the second PCB substrate is electrically connected to the feedback circuit.
20. The liquid crystal display device of claim 18 , wherein the first, second, third conductive layers each comprise a metal foil.