Light Bar with Resistance Modulated LED Strings
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Solution Overview
Problem
Conventional LED units in back light units for displays suffer from color uniformity issues due to imperfect mixing of primary colors across the light guide plate, leading to variations in the observed white point as measured from one end of the LED assembly to the other.
Innovation Solution
A light bar configuration with multiple subsets of LEDs of different colors, where specific subsets are electrically connected in series with varying resistive loads to compensate for color imbalances, allowing for customized correction across different physical dimensions and geometries, ensuring uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If conventional LED units are used with uniform electrical connection, then manufacturing is simple, but color uniformity across the light guide plate deteriorates
Solution Approach 1:
The patent applies local quality by dividing LEDs into different subsets (first subset and second subset) with different electrical connection configurations. Specifically, the first subset of LEDs is connected through a first electrical load while the second subset is connected through a second electrical load with different resistance values, creating localized electrical property variations that compensate for spatial color non-uniformity across the light guide plate.
Solution Approach 2:
The patent changes the electrical resistance parameter of the electrical loads connected to different LED subsets. By selecting electrical loads with different resistance values (first electrical load having different resistance than second electrical load), the current distribution through LEDs is modified, which directly affects the light output intensity and compensates for color non-uniformity in different regions of the light guide plate.
2Manufacturing precision
If LEDs are connected in series with varying resistive loads, then color uniformity is improved, but device complexity increases
Solution Approach 1:
The patent segments the LED array into multiple subsets (first subset and second subset) that are electrically separated and connected through different electrical loads. This segmentation allows independent control of electrical parameters for different LED groups, enabling precise compensation of color non-uniformity while maintaining a structured and manageable electrical connection architecture.
Solution Approach 2:
The patent modifies the resistance parameter of electrical loads to achieve color uniformity. By carefully selecting resistance values for different electrical loads, the current distribution is optimized to compensate for spatial variations in light output, achieving color uniformity through parameter optimization rather than complex control circuitry.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution achieves improved color uniformity by adjusting the current flow to LEDs at the edges of the light bar, resulting in a more balanced color composition and reduced intensity variations, thereby enhancing the overall color distribution across the display.
Implementation Method 1
The second subset of first color light emitting LEDs are electrically connected in series with a larger electrical load than the first subset of first color light emitting LEDs
Implementation Method 2
A plurality of first color light emitting LEDs including a first subset of first color light emitting LEDs and a second subset of first color light emitting LEDs
Data Source
AI summary
A light bar includes a plurality of first color light emitting LEDs including a first subset of first color light emitting LEDs and a second subset of first color light emitting LEDs, a plurality of second color light emitting LEDs, where the second color is different from the first color, and a plurality of third color light emitting LEDs, where the third color is different from the first and the second colors. The second subset of first color light emitting LEDs are electrically connected in series with a larger electrical load than the first subset of first color light emitting LEDs. This light bar electrical configuration allows compensation and correction for locations on the light guide plate used in back light units where imperfect mixing of the 3 primary colors provided by the individual LED emitters on the light bar occurs.