Optical Elements for Masking Defective LED Array Pixels
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Solution Overview
Problem
Large arrays of small LED pixels often have defective pixels that appear as dark or dim spots, leading to fabrication yield loss and rendering them unusable in many applications, despite these pixels being only a small fraction of the array.
Innovation Solution
A light-emitting apparatus with transmissive optical elements positioned over defective pixels, which extend laterally over adjacent pixels, allowing light from these adjacent pixels to propagate and appear as if emitted from the defective pixel, thereby reducing the appearance of the defect.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If large arrays of small LED pixels are manufactured, then the overall light output and coverage are improved, but defective pixels appear as dark or dim spots reducing yield
Solution Approach 1:
A transmissive optical element is introduced as an intermediary component positioned over defective pixels. This optical element acts as a mediator that redirects light from adjacent functional pixels through the defective pixel location, making the defect invisible while preserving overall array functionality and yield
Solution Approach 2:
The invention converts the harmful effect of defective pixels into a beneficial outcome by using optical elements to redirect light from functional pixels through the defective areas. This transforms what would be visible defects into imperceptible regions, effectively converting harm (defective pixels) into benefit (maintained yield and appearance)
2Reliability
If transmissive optical elements are added to compensate for defective pixels, then the appearance of defective pixels is reduced, but the device complexity increases
Solution Approach 1:
Transmissive optical elements are applied selectively only to locations where defective pixels are detected, rather than uniformly across the entire array. This localized approach maintains array uniformity where needed while minimizing additional complexity in functional regions
Solution Approach 2:
The optical elements create an optical copy or projection of light from adjacent functional pixels onto the defective pixel location. This copying mechanism allows the defective area to display light patterns from neighboring pixels, achieving uniformity without requiring physical replacement of defective components
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
This solution effectively reduces the visibility of defective pixels, ensuring that even arrays with a small percentage of non-functional pixels can be used in applications by compensating for their lack of emission with light from neighboring pixels, thereby increasing the usable yield of light-emitting arrays.
Implementation Method 1
Each optical element transmits laterally at least a portion of light emitted by the adjacent pixels to propagate away from the array from the location of the defective pixel
Data Source
AI summary
An inventive light-emitting apparatus comprises an array of multiple light-emitting pixels, and one or more transmissive optical elements positioned at a light-emitting surface of the light-emitting pixel array. One or more of the light-emitting pixels is defective. Each optical element is positioned at a location of a corresponding defective light-emitting pixel, and extends over that defective pixel and laterally at least partly over one or more adjacent pixels. Each optical element transmits laterally at least a portion of light emitted by the adjacent pixels to propagate away from the array from the location of the defective pixel, reducing the appearance of the defective pixel.