LED Pixel Array Contact Layout for Uniform Current Spread
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Solution Overview
Problem
In LED assemblies used in virtual reality or augmented reality systems, the varying distances of LEDs to n-contacts cause current crowding and voltage differences among LEDs, leading to inefficient current distribution and higher power consumption.
Innovation Solution
Additional n-contacts are formed within the LED array, either in trenches or between p-contacts, to reduce the distance between LEDs and n-contacts, thereby reducing voltage differences and improving current spread.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If additional n-contacts are formed within the LED array, then current spread is improved and voltage differences are reduced, but device complexity increases
Solution Approach 1:
The patent divides the single n-contact into multiple segmented n-contacts distributed across the LED array. This segmentation allows current to be injected at multiple locations, reducing current crowding and voltage differences across the array while maintaining overall system functionality.
Solution Approach 2:
The patent transitions from a single-point n-contact configuration to a multi-point distributed configuration across the two-dimensional LED array plane. This dimensional expansion of the contact architecture enables more uniform current distribution without requiring changes to the fundamental LED structure.
2Reliability
If n-contacts replace pixels in the LED array, then current spread is improved, but the pixel density is reduced
Solution Approach 1:
The patent extracts the n-contact function from the traditional edge-only location and places it within the pixel array at strategic locations. By taking out the electrical contact function and separating it from the pixel emission function, the system achieves improved current distribution while minimizing impact on pixel density through careful site selection.
Solution Approach 2:
The patent creates multi-functional contact structures that serve both as electrical n-contacts for current injection and as part of the pixel array structure. Some contacts are designed to fulfill dual roles, reducing the need for dedicated non-emissive contact areas and thereby preserving pixel density.
3Reliability
If p-contacts are resized or repositioned to accommodate additional n-contacts, then current spread is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies local quality adjustments to p-contacts in specific regions where n-contacts are introduced. Rather than uniformly resizing all p-contacts, only those in proximity to additional n-contacts are modified, maintaining manufacturing feasibility while achieving the desired current distribution improvement in critical areas.
Solution Approach 2:
The patent incorporates contact positioning and sizing considerations into the initial LED array design and manufacturing process. By pre-planning the locations and dimensions of p-contacts to accommodate future n-contact integration, the need for post-manufacturing adjustments is minimized, maintaining reasonable precision requirements.
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 reduces current crowding and voltage differences among LEDs, enhancing the uniformity of current distribution and reducing power consumption while maintaining the pixel density of the LED array.
Implementation Method 1
one or more second contacts of the first polarity, each formed between two or more LEDs of the pixel array, wherein the one or more second contacts increase a level of current spread between contacts of the first and second polarities
Data Source
AI summary
In a flip-chip LED assembly having an array of LEDs formed on the same substrate, different LEDs of the array have different distances to the n-contacts of the assembly. This may cause current crowding as current has to spread from the n-contacts through the substrate to each the farthest LEDs of the LED array, requiring LEDs that are farther away to be driven with a higher voltage in order to receive a desired amount of current. To spread current more evenly through the LED assembly and reduce a voltage difference between the closest and farthest LEDs of the array, one or more additional n-contacts are formed within the LED array. In some embodiments, the n-contacts may replace a pixel of the LED array. In other embodiments, one or more p-contacts of the LED array are resized or repositioned to accommodate the additional n-contacts without sacrificing pixels of the LED array.