Back light unit having a plurality of luminous elements and control method thereof

• US 20070176885A1
• Filed: 12/05/2006
• Published: 08/02/2007
• Est. Priority Date: 02/02/2006
• Status: Active Grant

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Jun, Sung-gon
• Granted Patent: US 7,795,821 B2
• Time in Patent Office: Days
• US Class Current: 345/102
• CPC Class Codes: G02F 1/133611 including means for improving the brightness uniformity
• CPC Class Codes: G09G 2320/0233 Improving the luminance or brightness uniformity across the screen
• CPC Class Codes: G09G 2320/041 Temperature compensation
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3426 the different display panel areas being distributed in two dimensions, e.g. matrix

Abstract

A back light unit (BLU) having a plurality of luminous elements, and a control method thereof is provided. The BLU includes a temperature detector to detect a temperature of the BLU, brightness detectors to detect a brightness of the plurality of luminous elements, a voltage supplier to supply a driving voltage to the plurality of luminous elements, respectively, and a controller to perform a first adjustment to adjust the driving voltage supplied to the plurality of luminous elements according to the temperature detected at the temperature detector, and to perform a second adjustment to adjust the driving voltage supplied to the plurality of luminous elements according to the brightness detected at the brightness detectors. Accordingly, the temperature of the BLU can be maintained stable, and the brightness can be controlled uniformly.

Claims

1. A back light unit (BLU) having a plurality of luminous elements, the BLU comprising:

a temperature detector to detect a temperature of the BLU;

a plurality of brightness detectors to detect a brightness of the plurality of luminous elements;

a voltage supplier to supply driving voltages to the plurality of luminous elements, respectively; and

a controller to perform a first adjustment to adjust the driving voltages supplied to the plurality of luminous elements according to the temperature detected at the temperature detector, and to perform a second adjustment to adjust the driving voltages supplied to the plurality of luminous elements according to the brightness detected at the brightness detectors.

2. The BLU of claim 1, wherein, when the first and the second adjustments are completed, the controller checks whether the temperature detected at the temperature detector is within a predetermined temperature range, and if determining that the temperature is outside the predetermined temperature range, the controller performs the first and the second adjustments again.

3. The BLU of claim 1, further comprising:

a computing part to compute a brightness uniformity using a lowest and a highest brightness detected at the brightness detectors.

4. The BLU of claim 3, wherein, when the brightness uniformity computed by the computing part does not satisfy a predetermined standard, the controller performs a third adjustment to adjust the driving voltages supplied to at least one luminous element corresponding to a brightness detector detecting the lowest brightness and to at least one luminous element corresponding to a brightness detector detecting the highest brightness.

5. The BLU of claim 4, wherein, when the third adjustment is completed, the controller checks whether the temperature detected at the temperature detector is within a predetermined temperature range, and whether the brightness detected at the brightness detectors is within an acceptable brightness range, and performs the first and the second adjustments again if the temperature is not within the predetermined temperature range or the brightness is not within the acceptable brightness range, respectively.

6. The BLU of claim 4, wherein, when the third adjustment is completed, the controller checks whether the temperature detected at the temperature detector is within a predetermined temperature range, and whether an average brightness detected at the brightness detectors is within a predetermined brightness level, and performs the first and the second adjustments again if the temperature is not within the predetermined temperature range or the average brightness is not within a predetermined brightness level, respectively.

7. The BLU of claim 1, wherein the controller performs the first adjustment by controlling the voltage supplier such that the voltage supplier incrementally increases the driving voltage supplied to at least one luminous element corresponding to a brightness detector detecting a lowest brightness detected when the temperature detected at the temperature detector is below a lowest threshold temperature of the predetermined temperature range, and the voltage supplier decrementally decreases the driving voltage supplied to at least one luminous element corresponding to a brightness detector detecting a highest brightness detected when the temperature detected at the temperature detector exceeds the highest threshold temperature of the predetermined temperature range.

8. The BLU of claim 1, wherein the controller performs the second adjustment by controlling the voltage supplier such that the voltage supplier incrementally increases the overall driving voltage supplied to the plurality of luminous elements when an average brightness of the plurality of luminous elements detected at the brightness detectors is less than a predetermined brightness level, and the voltage supplier decrementally decreases the overall driving voltage supplied to the plurality of luminous elements when the average brightness detected at the brightness detectors is greater than the predetermined brightness level.

9. The BLU of claim 1, wherein the controller performs the first adjustment by controlling the voltage supplier such that the voltage supplier incrementally increases the overall driving voltage supplied to the plurality of luminous elements when the temperature detected at the temperature detector is less than the lowest threshold temperature of the predetermined temperature range, and the voltage supplier decrementally decreases the overall driving voltage supplied to the plurality of luminous elements when the temperature detected at the temperature detector exceeds the highest threshold temperature of the predetermined temperature range.

10. The BLU of claim 1, wherein the control performs the second adjustment by controlling the voltage supplier such that, when the brightness detected at the brightness detectors exceeds an acceptable brightness range, the voltage supplier decrementally decreases the driving voltage supplied to at least one luminous element corresponding to a brightness detector detecting the brightness exceeding the acceptable brightness range, and when a brightness less than the acceptable brightness range is detected at the brightness detectors, the voltage supplier incrementally increases the driving voltage supplied to at least one luminous element corresponding to a brightness detectors detecting the brightness less than the acceptable brightness range.

11. The BLU of claim 1, wherein the temperature detector is disposed at an upper middle part of the BLU.

12. The BLU of claim 1, wherein the temperature detector comprises a plurality of temperature detectors distributed about the BLU.

13. The BLU of claim 1, wherein each brightness detector is disposed to correspond with a respective luminous element to detect the brightness of each corresponding luminous element.

14. The BLU of claim 1, wherein each brightness detector is disposed to detect the brightness of two or more corresponding luminous elements.

15. A back light unit (BLU) having a plurality of luminous elements, the BLU comprising:

a plurality of brightness detectors, each to respectively detect the brightness of a corresponding luminous element group;

a temperature detector to detect the temperature of the BLU;

a voltage supplier to supply the plurality of luminous elements with respective driving voltages; and

a controller to control the driving voltages supplied to the plurality of luminous elements.

16. The BLU of claim 15, wherein the corresponding luminous element group comprises only one luminous element of the plurality of luminous elements.

17. The BLU of claim 15, wherein the corresponding luminous element group comprises two or more luminous elements of the plurality of luminous elements.

18. The BLU of claim 15, wherein the controller performs a first adjustment to adjust the driving voltages supplied to the plurality of luminous elements depending on a temperature of the BLU detected by the temperature detector.

19. The BLU of claim 15, wherein the controller performs a second adjustment to adjust the driving voltages supplied to the plurality of luminous elements depending on a brightness of the plurality of luminous elements detected by the brightness detectors.

20. The BLU of claim 18, wherein the controller performs the first adjustment to control the voltage supplier to increase the driving voltage supplied to the luminous element group corresponding to a brightness detector detecting a lowest brightness, when the temperature detected by the temperature detector is lower than a reference temperature range, and wherein the controller performs the first adjustment to control the voltage supplier to decrease the driving voltage supplied to the luminous element group corresponding to a brightness detector detecting a highest brightness when the temperature detected by the temperature detected is higher than a reference temperature range.

21. The BLU of claim 18, wherein the controller performs the first adjustment to control the voltage supplier to increase the overall driving voltage supplied to the plurality of luminous elements when the temperature detected by the temperature detector is lower than a reference temperature range, and wherein the controller performs the first adjustment to control the voltage supplier to decrease the overall driving voltage supplied to the plurality of luminous elements when the temperature detected by the temperature detector is higher than a reference temperature range,

22. The BLU of claim 19, wherein the controller performs the second adjustment to control the voltage supplier to decrease the overall driving voltage supplied to the plurality of luminous elements when an average brightness detected by the brightness detectors is above a reference brightness range, and wherein the controller performs the second adjustment to control the voltage supplier to increase the overall driving voltage supplied to the plurality of luminous elements when the average brightness detected is below the reference brightness or brightness range.

23. The BLU of claim 19, wherein the controller performs the second adjustment to control the voltage supplier to decrease the driving voltage supplied to the luminous element group corresponding to a brightness detector detecting a brightness above an acceptable brightness range, when a brightness above the acceptable brightness range is detected by the brightness detectors, and wherein the controller performs the second adjustment to control the voltage supplier to increase the driving voltage supplied to the luminous element group corresponding to a brightness detector detecting a brightness below the acceptable brightness range when a brightness below the acceptable brightness range is detected.

24. The BLU of claim 15, further comprising:

a computing part to compute a brightness uniformity of the BLU and the controller performs a third adjustment to adjust the driving voltage supplied to the plurality of luminous elements depending on the brightness uniformity computed by the computing part.

25. The BLU of claim 24, wherein the controller performs the third adjustment to increase the driving voltage supplied to the luminous element group corresponding to a brightness detector detecting a lowest brightness and to decrease the driving voltage supplied to the luminous element group corresponding to a brightness detector detecting a highest brightness when the brightness uniformity computed by the computing part does not satisfy a reference standard.

26. The BLU of claim 15, wherein the temperature detector comprises a plurality of temperature detectors distributed about the BLU.

27. A method of controlling a back light unit (BLU) having a plurality of luminous elements, the method comprising:

detecting a temperature of the BLU;

detecting a brightness of the plurality of luminous elements;

performing a first adjustment to adjust the driving voltages supplied to the plurality of luminous elements according to the detected temperature; and

performing a second adjustment to adjust the driving voltages supplied to the plurality of luminous elements according to the detected brightness.

28. The method of claim 27, wherein the detecting of the brightness of the plurality of luminous elements comprises each of the plurality of brightness detectors detecting a brightness of one of the plurality of luminous elements.

29. The method of claim 28, wherein the detecting of the brightness of the plurality of luminous elements comprises each of the plurality of brightness detectors detecting the brightness of two or more luminous elements of the plurality of luminous elements.

30. The method of claim 27, further comprising:

checking whether the temperature is within a predetermined temperature range after the first and second adjustments are performed, and if the temperature is outside the predetermined temperature range, repeating the first and the second adjustments.

31. The method of claim 27, further comprising:

computing a brightness uniformity using a lowest brightness detected and a highest brightness detected.

32. The method of claim 31, further comprising:

performing a third adjustment when the computed brightness does not satisfy a predetermined standard to adjust the driving voltage supplied to at least one luminous element with the lowest detected brightness and at least one luminous element with the highest detected brightness.

33. The method of claim 32, further comprising:

checking, after the third adjustment is completed, whether the temperature detected is within a predetermined range, and whether an average of all the brightness detected is within a predetermined brightness range, and performing the first, the second and the third adjustments again if the temperature detected is not within the predetermined range, the average brightness is not within the predetermined brightness range, and/or the computed brightness does not satisfy the predetermined standard, respectively.

34. The method of claim 32, further comprising:

checking, after the third adjustment is completed, whether the temperature detected is within a predetermined range, and whether the brightness detected is within an acceptable brightness range, and performing the first, the second and the third adjustments again if the temperature detected is not within the predetermined range, the brightness detected is not within the acceptable brightness range, and/or the computed brightness does not satisfy the predetermined standard, respectively.

35. The method of claim 27, wherein the performing of the first adjustment comprises incrementally increasing the driving voltage supplied to at least one luminous element corresponding to a lowest brightness detected when the detected temperature is lower than the lowest threshold temperature of a predetermined temperature range, and decrementally decreasing the driving voltage supplied to at least one luminous element corresponding to a highest brightness detected when the detected temperature exceeds a highest threshold temperature of the predetermined temperature range.

36. The method of claim 27, wherein the performing of the second adjustment comprises incrementally increasing an overall driving voltage supplied to the plurality of luminous elements when an average brightness of the plurality of luminous elements detected is lower than a predetermined brightness level, and decrementally decreasing the overall driving voltage supplied to the plurality of luminous elements when the average brightness exceeds the predetermined brightness level.

37. The method of claim 27, wherein the performing of the first adjustment comprises incrementally increasing the overall driving voltage supplied to the plurality of luminous elements when the detected temperature is lower than a lowest threshold temperature of a predetermined temperature range, and decrementally decreasing the overall driving voltage supplied to the plurality of luminous elements when the detected temperature exceeds a highest threshold temperature of the predetermined temperature range.

38. The method of claim 27, wherein the performing of the second adjustment comprises decrementally decreasing the driving voltage supplied to at least one luminous element corresponding to a brightness exceeding an acceptable brightness range when the detected brightness of the plurality of luminous elements exceeds an acceptable brightness range, and incrementally increasing the driving voltage supplied to at least one luminous element corresponding to a brightness lower than the acceptable brightness range when the detected brightness of the plurality of luminous elements is lower than the acceptable brightness range.

39. The method of claim 27, wherein the detecting of the temperature of the BLU is performed by a temperature detector disposed at an upper middle part of the BLU.

40. The method of claim 27, wherein the detecting of the temperature of the BLU is performed by a plurality of temperature detectors distributed around the BLU.

41. A method of controlling a back light unit (BLU) having a plurality of luminous elements, the method comprising:

detecting a temperature of the BLU;

detecting a brightness of the plurality of luminous elements;

performing a first adjustment to adjust driving voltages supplied to the plurality of luminous elements according to the detected temperature; and

performing a second adjustment to adjust driving voltages supplied to the plurality of luminous elements according to the detected brightness.

42. The method of claim 41, further comprising:

computing a brightness uniformity of the BLU; and

performing a third adjustment to adjust driving voltages supplied to the plurality of luminous elements according to the computed brightness uniformity.

43. The method of claim 41, wherein the performing of the first adjustment comprises increasing an overall driving voltage supplied to the plurality of luminous elements when the temperature detected is below a reference temperature range, and decreasing the overall driving voltage supplied to the plurality of luminous elements when the temperature detected is above a reference temperature range.

44. The method of claim 41, wherein the performing of the first adjustment comprises increasing the driving voltages supplied to one or more luminous elements corresponding to a lowest brightness detected when the temperature detected is below a reference temperature range, and decreasing the driving voltages supplied to one or more luminous elements corresponding to a highest brightness detected when the temperature detected is above a reference temperature range.

45. The method of claim 41, wherein the performing of the second adjustment comprises decreasing an overall driving voltage supplied to the plurality of luminous elements when an average of all the brightness detected is above a reference brightness range, and increasing the overall driving voltage supplied to the plurality of luminous elements when the average of all the brightness detected is below the reference brightness range.

46. The method of claim 41, wherein the performing of the second adjustment comprises decreasing the driving voltages supplied to one or more luminous elements corresponding to a brightness detected above an acceptable brightness range, when the detected brightness of the plurality of luminous elements is above an acceptable brightness range, and increasing the driving voltages supplied to one or more luminous elements corresponding to a brightness detected below the acceptable brightness range when the detected brightness of the plurality of luminous elements is below the acceptable driving range.

47. The method of claim 42, wherein the performing of the third adjustment comprises increasing the driving voltages supplied to one or more luminous elements corresponding to a lowest brightness detected and decreasing the driving voltages of one or more luminous elements corresponding to a highest brightness detected when the computed brightness uniformity does not satisfy a reference brightness uniformity or brightness uniformity range.

48. The method of claim 41, further comprising:

determining an abnormal operation state of the plurality of luminous elements.

49. The method of claim 48, wherein the determining of the abnormal operation comprises determining that an abnormal operating state exists when the brightness detected does not change after the first or second adjustment is performed to adjust the driving voltages of the plurality of luminous elements.

50. The method of claim 48, wherein the first and second adjustments adjust the driving voltages of one or more luminous elements, and the determining of the abnormal operation comprises determining that an abnormal operating state exists when the brightness detected of the one or more luminous elements does not change after the first or second adjustment is performed to adjust the driving voltages of the one or more luminous elements.