System and method for managing backlight luminance variations
First Claim
1. A method for controlling luminance variations in LED assemblies having a plurality of LEDs divided into two or more controllable regions, the method comprising:
- driving a first and second LED region at preferred power levels;
measuring the temperature at the first and second LED regions;
calculating the temperature difference (Δ
T1-2) between the first and second LED regions;
comparing Δ
T1-2 with a predetermined temperature difference Δ
T; and
increasing power to the LED region having the higher temperature measurement if Δ
T1-2 is greater than Δ
T orcontinuing with preferred power levels if Δ
T1-2 is less than Δ
T.
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Abstract
An LED assembly containing separately-controllable regions of LEDs with temperature sensing devices placed to measure the temperature within each region of LEDs. When the temperature difference between two regions becomes higher than an acceptable maximum, the system may adjust the power to one or more LED regions to maintain luminance uniformity. The regions can be arranged vertically or horizontally or both. A software processor may be used to interpret the data from the temperature sensing devices and control the power sent to the various LED regions. Embodiments can be used at least in LED backlights for LCD displays or for LED displays.
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Citations
19 Claims
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1. A method for controlling luminance variations in LED assemblies having a plurality of LEDs divided into two or more controllable regions, the method comprising:
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driving a first and second LED region at preferred power levels; measuring the temperature at the first and second LED regions; calculating the temperature difference (Δ
T1-2) between the first and second LED regions;comparing Δ
T1-2 with a predetermined temperature difference Δ
T; andincreasing power to the LED region having the higher temperature measurement if Δ
T1-2 is greater than Δ
T orcontinuing with preferred power levels if Δ
T1-2 is less than Δ
T. - View Dependent Claims (2, 3, 4, 5, 6)
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7. A method for controlling luminance variations in LED assemblies having a plurality of LEDs divided into two or more controllable regions, the method comprising:
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driving a first and second LED region at preferred power levels; measuring the temperature at the first and second LED regions; calculating the temperature difference (Δ
T1-2) between the first and second LED regions;comparing Δ
T1-2 with a predetermined temperature difference Δ
T; anddecrease power to the LED region having the lower temperature measurement if Δ
T1-2 is greater than Δ
T orcontinue with preferred power levels if Δ
T1-2 is less than Δ
T. - View Dependent Claims (8, 9, 10, 11, 12)
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13. A system for controlling luminance variations across an LED assembly comprising:
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a first plurality of LEDs in electronic communication with a first power source; a first temperature sensing device placed to measure the temperature (T1) of the first plurality of LEDs; a second plurality of LEDs in electronic communication with a second power source; a second temperature sensing device placed to measure the temperature (T2) of the second plurality of LEDs; a processor in electrical communication with the power sources and temperature sensing devices, and adapted to; drive the first and second plurality of LEDs at preferred power levels; calculate the difference (Δ
T1-2) between T1 and T2;compare Δ
T1-2 with a predetermined temperature difference Δ
T; andincrease power to the plurality of LEDs having the higher temperature measurement if Δ
T1-2 is greater than Δ
T orcontinue with preferred power levels if Δ
T1-2 is less than Δ
T. - View Dependent Claims (14, 15, 16)
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17. An LED assembly comprising:
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a first plurality of LEDs in electronic communication with a first power source; a first temperature sensing device placed to measure the temperature (T1) of the first plurality of LEDs; a second plurality of LEDs in electronic communication with a second power source, the LEDs placed above the first plurality of LEDs; a second temperature sensing device placed to measure the temperature (T2) of the second plurality of LEDs; a third plurality of LEDs in electronic communication with a third power source, the LEDs placed above the second plurality of LEDs; a third temperature sensing device placed to measure the temperature (T3) of the third plurality of LEDs; a processor in electrical communication with the power sources and temperature sensing devices, and adapted to; drive the first, second, and third plurality of LEDs at preferred power levels; calculate the difference (Δ
T1-2) between T1 and T2, Δ
T1-3 between T1 and T3, and Δ
T2-3 between T2 and T3;compare Δ
T1-2, Δ
T1-3, and Δ
T2-3 with a predetermined temperature difference Δ
T; andincrease power to the plurality of LEDs having the highest temperature measurement if either Δ
T1-3, Δ
T2-3, or Δ
T1-2 is greater than Δ
T orcontinue with preferred power levels if Δ
T1-3, Δ
T2-3, and Δ
T1-2 are less than Δ
T. - View Dependent Claims (18, 19)
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Specification