LED BACKLIGHT FOR DISPLAY SYSTEMS

• US 20110069511A1
• Filed: 11/29/2010
• Published: 03/24/2011
• Est. Priority Date: 10/10/2007
• Status: Active Grant

• Current Assignee: Apple Inc.
• Original Assignee: Apple Inc.
• Inventors: YIN, Victor, QI, Jun, ZHONG, John, CHEN, Wei
• Granted Patent: US 8,100,544 B2
• Time in Patent Office: Days
• US Class Current: 362/612
• CPC Class Codes: G02F 1/133603 with LEDs
• CPC Class Codes: G02F 1/133609 including means for improving the color mixing, e.g. white
• CPC Class Codes: Y10S 362/80 Light emitting diode

Abstract

An LED backlight method for display systems comprising receiving a plurality of light emitting diodes categorized into a plurality of bins, wherein each bin references a separate range of white point colors, and determining an optimal order for mounting the plurality of light emitting diodes at spatially distributed positions, the plurality of light emitting diodes comprising white point colors associated with separate bins, wherein the optimal order of the plurality of light emitting diodes produces a light of a desired white point color when the light outputs of the plurality of light emitting diodes are mixed.

Claims

1. An LED backlight method for display systems comprising:

receiving a plurality of light emitting diodes categorized into a plurality of bins, wherein each bin references a separate range of white point colors; and

determining an optimal order for mounting the plurality of light emitting diodes at spatially distributed positions, the plurality of light emitting diodes comprising white point colors associated with separate bins, wherein the optimal order of the plurality of light emitting diodes produces a light of a desired white point color when the light outputs of the plurality of light emitting diodes are mixed.

2. The method of claim 1, further comprising mounting the plurality of light emitting diodes on a display panel in the optimal order.

3. The method of claim 2, further comprising mounting the plurality of light emitting diodes along an edge of the display panel spaced from an active area of the display panel.

4. The method of claim 3, wherein the plurality of light emitting diodes are spaced from each other by a distance similar to their distance from the active area of the display panel.

5. The method of claim 3, wherein the plurality of light emitting diodes are spaced from each other by a distance less than their distance from the active area of the display panel.

6. The method of claim 3, wherein the plurality of light emitting diodes are spaced from each other by a distance greater than their distance from the active area of the display panel.

7. The method of claim 1, wherein

the categorization of light emitting diodes further comprises a plurality of zones, each zone having multiple bins associated therewith, and wherein

the plurality of light emitting diodes comprising white point colors associated with separate zones.

8. The method of claim 1, further comprising minimizing near field and far field color differences.

9. The method of claim 1, wherein determining the optimal order comprises minimizing the distance from a center point.

10. The method of claim 1, wherein determining the optimal order comprises minimizing the distance from a shifted Black-Body curve.

11. The method of claim 1, wherein determining an optimal order for the plurality of light emitting diodes of the plurality further comprises:

initiating an order of N color bins;

then calculating the near field and far field color difference of the order of N color bins;

then randomly permutating two of the color bins;

then again calculating the near field and far field color difference;

then determining if the again-calculated near field and far field color difference is reduced from the near field and far field color difference of the order of N color bins;

then, if the color difference is reduced, accepting the permutation and returning to the step of randomly permutating two of the color bins;

otherwise rejecting the permutation;

then, based upon the rejection of the permutation, determining if the again-calculated near field and far field color difference is stabilized, and if not, returning to the step of again calculating the near field and far field color difference;

then determining if the near field and far field colors meet desired specifications;

then, if the near field and far field desired color specifications are met, outputting the optimal bin order, the near field color, and the far field color; and

then, if the near field and far field desired color specifications are not met, outputting that there is no optimal bin order for this range of color bins and optionally repeating the method with a smaller value of N.

12. A portable computing device comprising:

a display panel;

a central processing unit coupled to the display panel; and

an LED backlight, the LED backlight comprising;

at least two light emitting diodes associated with different white point color ranges, wherein the at least two light emitting diodes are mounted on the display panel in an optimal order at spatially distributed positions, and wherein the optimal order produces light of a desired white point color when the light outputs of the at least two light emitting diodes are mixed.

13. The backlight of claim 12, wherein the at least two light emitting diodes are mounted along an edge of the display panel spaced from an active area of the display panel.

14. The backlight of claim 13, wherein the at least two light emitting diodes are spaced from each other by a distance similar to their distance from the active area of the display panel.

15. The backlight of claim 13, wherein the at least two light emitting diodes are spaced from each other by a distance less than their distance from the active area of the display panel.

16. The backlight of claim 13, wherein the at least two light emitting diodes are spaced from each other by a distance greater than their distance from the active area of the display panel.

17. The backlight of claim 12, wherein the different white point ranges are associated with different zones, each zone comprising multiple white point ranges.

18. The backlight of claim 12, wherein the optimal order minimizes near field and far field color differences.

19. The backlight of claim 12, wherein the optimal order minimizes the distance from a center point.

20. The backlight of claim 12, wherein the optimal order minimizes the distance from a shifted Black-Body curve.

21. The backlight of claim 12, wherein the optimal order comprises:

initiating an order of N color bins;

then calculating the near field and far field color difference of the order of N color bins;

then randomly permutating two of the color bins;

then again calculating the near field and far field color difference;

then determining if the again-calculated near field and far field color difference is reduced from the near field and far field color difference of the order of N color bins;

then, if the color difference is reduced, accepting the permutation and returning to the step of randomly permutating two of the color bins;

otherwise rejecting the permutation;

then, based upon the rejection of the permutation, determining if the again-calculated near field and far field color difference is stabilized, and if not, returning to the step of again calculating the near field and far field color difference;

then determining if the near field and far field colors meet desired specifications;

then, if the near field and far field desired color specifications are met, outputting the optimal bin order, the near field color, and the far field color; and

then, if the near field and far field desired color specifications are not met, outputting that there is no optimal bin order for this range of color bins.