Device for driving light emitting diode

Abstract

A device for driving a plurality of light emitting diodes includes a plurality of light emitting diode groups in series; a current providing unit for providing a current to the plurality of light emitting diode groups; and at least one current path controller in parallel with a corresponding one of the light emitting diode groups for turning off the corresponding one of the light emitting diode groups in accordance with a control signal.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

These and other objects of the invention will be apparent from the after detailed description of the embodiments of the present invention with reference to the accompanying drawings, in which:

FIG. 1 is a circuit diagram illustrating a device for driving an LED as a light source in a backlight of an LCD device according to the related art;

FIG. 2 is a schematic diagram of an exemplary device for driving a plurality of LEDs as a light source in a backlight of an LCD device according to an embodiment of the present invention;

FIG. 3 is a circuit diagram of an exemplary device for driving a plurality of LEDs as a light source in a backlight of an LCD device according to an embodiment of the present invention;

FIG. 4 is a graphical illustration of exemplary current path control signals for controlling the driving of LEDs of FIGS. 2 and 3 according to an embodiment of the present invention;

FIG. 5 is a schematic diagram of an exemplary device for driving a plurality of LEDs as a light source in a backlight of an LCD device according to another embodiment of the present invention;

FIG. 6 is a circuit diagram of an exemplary constant-current providing unit for the device for driving a plurality of LEDs of FIG. 5; and

FIG. 7 is a graphical illustration of exemplary group activation signals in a device for driving a light emitting diode according to anther embodiment of the present invention.

Claims

1. A device for driving a plurality of light emitting diodes, comprising: a plurality of light emitting diode groups in series;a current providing unit for providing a current to the plurality of light emitting diode groups;at least one current path controller in parallel with a corresponding one of the light emitting diode groups for turning off the corresponding one of the light emitting diode groups in accordance with a control signal.

2. The device of claim 1, wherein the at least one current path controller includes a metal oxide semiconductor field effect transistor or a bipolar junction transistor.

4. The device of claim 1, further comprising an over-current protector for suppressing a flow of over current through the at least one current path controller.

5. The device of claim 4, wherein the over-current protector includes one of a Zener diode and a resistor.

6. The device of claim 1, wherein the number of the light emitting diodes in at least one of the emitting diode groups is in a range of about 2 to about 15.

7. The device of claim 1, wherein the control signal includes a pulse signal.

8. The device of claim 1, wherein the current from the current providing unit is substantially constant.

9. A backlight unit, including the device of claim 1.

10. An LCD device, including the device of claim 1.

11. A device for driving a plurality of light emitting diodes in an LCD device, comprising: a plurality of light emitting diode groups in parallel;a current providing unit for providing a current to the plurality of light emitting diode groups;at least one switch in series with a corresponding one of the light emitting diode groups for activating the corresponding one of the light emitting diode groups in accordance with a control signal.

12. The device of claim 11, wherein the number of the light emitting diodes in at least one of the emitting diode groups is in a range of about 2 to about 15.

13. The device of claim 11, wherein the at least one switch includes a metal oxide semiconductor field effect transistor or a bipolar junction transistor.

14. The device of claim 11, wherein an activation time of the corresponding one of the light emitting diode groups is proportional to a duty ratio of the control signal.

15. The device of claim 11, further comprising an over-current protector in series with the at least one switch and the corresponding one of the light emitting diode groups for preventing a flow of over-current through the corresponding one of the group activating units.

16. A backlight unit, including the device of claim 11.

17. An LCD device, including the device of claim 11.

18. A device for driving a plurality of light emitting diodes in an LCD device, comprising: a plurality light emitting diode groups in parallel;a current providing unit for providing a current to the light emitting diode groups;a plurality of switches, each of which in series with a corresponding one of the light emitting diode groups for activating the corresponding one of the light emitting diode groups in accordance with a corresponding control signal.

19. The device of claim 18, wherein an activation time of the corresponding one of the light emitting diode groups is proportional to a duty ratio of the control signal.

20. The device of claim 18, wherein the switches sequentially activating the corresponding ones of the plurality of light emitting diodes.

21. A backlight unit, including the device of claim 18.

22. An LCD device, including the device of claim 18.