Back light apparatus and control method thereof

• US 8,044,918 B2
• Filed: 10/18/2007
• Issued: 10/25/2011
• Est. Priority Date: 12/04/2006
• Status: Expired due to Fees

• Current Assignee: Samsung Electronics Co. Ltd.
• Original Assignee: Samsung Electronics Co. Ltd.
• Inventors: Choi, Hoon
• Primary Examiner(s): OSORIO, RICARDO
• Application Number:
  US11/874,268
• Publication Number:
  US 20080129223A1
• Time in Patent Office: 1,468 Days
• Field of Search: 345/87, 345/82, 345/83, 345/102, 349/65
• US Class Current: 345/102
• CPC Class Codes: G09G 2320/043 Preventing or counteracting the effects of ageing
• CPC Class Codes: G09G 2320/0666 for control of colour parameters, e.g. colour temperature
• CPC Class Codes: G09G 2360/145 the light originating from the display screen
• CPC Class Codes: G09G 3/3413 Details of control of colour illumination sources
• CPC Class Codes: H04N 9/73 Colour balance circuits, e.g. white balance circuits or colour temperature control camera processing pipelines for colour balance H04N23/88
• CPC Class Codes: H05B 45/20 Controlling the colour of the light
• CPC Class Codes: H05B 45/22 using optical feedback
• CPC Class Codes: Y02B 20/30 Semiconductor lamps, e.g. solid state lamps [SSL] light emitting diodes [LED] or organic LED [OLED]

Abstract

A back light apparatus includes a back light part which emits light to a liquid crystal display panel, and includes a plurality of LEDs respectively corresponding to a plurality of colors, a detecting part which detects the light emitted from the plurality of the LEDs, a driving part which drives the LEDs to emit, and a controller which controls the driving part to make color ratios substantially equal to a reference value if the reference value is not equal to the color ratio between at least two colors among the plurality of colors of the light detected in the detecting part.

Claims

1. A back light apparatus comprising:

a back light part which emits light to a liquid crystal display panel, the back light part comprising a plurality of light emitting diodes (LEDs) respectively corresponding to a plurality of colors;

a detecting part which detects the light emitted by the plurality of the LEDs;

a driving part which drives the plurality of the LEDs to generate an emission; and

a controller which controls the driving part to make a color ratio between two colors of the plurality of colors of the light detected in the detecting part substantially equal a reference value if the reference value does not equal the color ratio between the two colors of the plurality of colors of the light detected in the detecting part.

2. The back light apparatus according to claim 1, wherein the plurality of LEDs comprises red LEDs, green LEDs and blue LEDs.

3. The back light apparatus according to claim 1, wherein the controller controls the driving part to adjust current inputs to LEDs for the two colors so that the color ratio between the two colors becomes a value.

4. The back light apparatus according to claim 1, wherein the controller controls the driving part to adjust a current input to an LED for one of the two colors so that the color ratio becomes a value.

5. The back light apparatus according to claim 4, wherein the controller controls the driving part to adjust a current input to an LED for the other color of the two colors so that the color ratio becomes the value if the current input to an LED of the one color of the two colors reaches a maximum level.

6. The back light apparatus according to claim 4, wherein the controller controls the driving part to adjust pulse width modulation (PWM) of the current input to the LED for the one color so that the color ratio between the two colors becomes the value.

7. The back light apparatus according to claim 1, wherein the detecting part comprises a photo diode.

8. A control method of a back light apparatus which emits light to a liquid crystal display panel and comprises a plurality of light emitting diodes (LEDs) respectively corresponding to a plurality of colors, the control method comprising:

detecting the plurality of colors of the light emitted from the plurality of the LEDs;

calculating a color ratio between two colors of the plurality of detected colors; and

adjusting a brightness of the LEDs to make the color ratio between the two colors equal a reference value if the reference value does not equal the calculated color ratio.

9. The control method of the back light apparatus according to claim 8, wherein the plurality of LEDs comprises red LEDs, green LEDs and blue LEDs.

10. The control method of the back light apparatus according to claim 8, wherein the adjusting of the color ratio between the two colors comprises adjusting current inputs to LEDs for the two colors.

11. The control method of the back light apparatus according to claim 8, wherein the adjusting of the color ratio between the two colors comprises adjusting a current input to an LED for one color of the two colors.

12. The control method of the back light apparatus according to claim 11, wherein the adjusting of the color ratio between the two colors comprises adjusting a current input to an LED for the other color of the two colors if the current input to an LED for the one color of the two colors reaches a maximum level.

13. The control method of the back light apparatus according to claim 11, wherein the adjusting of the ratio between the two colors comprises adjusting pulse width modulation (PWM) of a current input to the LED for the one color.

14. The control method of the back light apparatus according to claim 8, wherein each of the LEDs comprise a photo diode.

15. A computer readable medium storing a set of instructions for performing a control method of a back light apparatus which emits light to a liquid crystal display panel and comprises a plurality of light emitting diodes (LEDs) respectively corresponding to a plurality of colors, the method comprising:

detecting the plurality of colors of the light emitted from the plurality of the LEDs;

calculating a color ratio between two colors of the plurality of detected colors; and

adjusting a brightness of the LEDs so that the color ratio equals a reference value if the reference value does not equal the calculated color ratio.

16. The computer readable medium according to claim 15, wherein the plurality of LEDs comprises red LEDs, green LEDs and blue LEDs.

17. The computer readable medium according to claim 15, wherein the adjusting of the color ratio between the two colors comprises adjusting current inputs to LEDs for the two colors.

18. The computer readable medium according to claim 15, wherein the adjusting of the color ratio between the two colors comprises adjusting a current input to an LED for one color of the two colors.

19. The computer readable medium according to claim 18, wherein the adjusting of the color ratio between the two colors comprises adjusting a current input to an LED for the other color of the two colors if the current input to an LED for the one color of the two colors reaches a maximum level.

20. The computer readable medium according to claim 18, wherein the adjusting of the ratio between two colors comprises adjusting pulse width modulation (PWM) of the current input to the LED for the one color.