Interleaved LED String Topology for Linear Lighting Defect Tolerance
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Solution Overview
Problem
The existing LED bulbs in linear lighting modules face a high return rate due to inevitable LED and electrical connection defects, where a single defective LED in a series-connected string causes the entire string to fail, leading to perceived defects and increased returns as the number of LEDs increases.
Innovation Solution
The solution involves configuring LED dies in a linear lighting module with two series-connected strings of LED dies aligned and interleaved, where each LED die is connected to two conductors from alternating sides, using a non-crossing wiring arrangement on a flexible substrate, allowing for efficient distribution of drive current and minimizing the impact of a defective string by distributing the current to other strings.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the number of LEDs in an LED bulb is increased to improve light output, then the brightness increases, but the probability of defects increases and the return rate rises faster than the proportional increase in LED numbers
Solution Approach 1:
The patent divides the LED string into multiple independent parallel strings (e.g., 3 strings instead of 1). Each string contains a subset of the total LEDs. This segmentation ensures that a defect in one string does not affect the other strings, allowing the bulb to remain functional even with some defective LEDs. The segmentation principle directly addresses the contradiction by reducing the impact of defects while maintaining high brightness through multiple parallel pathways.
Solution Approach 2:
The patent implements non-uniform distribution of LEDs across parallel strings, where different strings may have different numbers of LEDs or different positioning patterns. This local quality variation allows optimization of light distribution and defect tolerance in specific regions, ensuring that defects in one local area do not compromise the overall bulb performance.
2Device complexity
If LEDs are connected in series to reduce the number of parallel strings and simplify wiring, then the device complexity decreases, but a single defective LED causes the entire string to fail
Solution Approach 1:
The patent segments the LED configuration into multiple parallel strings with controlled series connections within each string. This segmentation allows the system to maintain relatively simple wiring while ensuring that a defect in one string does not propagate to other strings. The segmentation creates isolated failure zones, improving reliability without significantly increasing wiring complexity.
Solution Approach 2:
The patent transitions from a single-dimensional series connection to a two-dimensional array structure with multiple parallel strings. This dimensional change allows the system to distribute LEDs across multiple independent pathways, reducing the impact of single-point failures while maintaining manageable wiring complexity through systematic interconnection patterns.
3Volume of moving object
If LEDs are arranged in a compact linear configuration to reduce the bulb size, then the volume decreases, but the wiring arrangement becomes more complex and defects are more concentrated
Solution Approach 1:
The patent segments the compact linear LED arrangement into multiple parallel strings that are interleaved or distributed throughout the bulb volume. This segmentation allows efficient space utilization while creating distinct wiring pathways that reduce complexity. Each string can be independently routed, simplifying the overall wiring arrangement within the compact form factor.
Solution Approach 2:
The patent employs three-dimensional spatial distribution of LED strings within the compact bulb, rather than simple linear arrangement. By distributing strings in multiple dimensions (interleaved patterns, different spatial layers), the patent achieves compact volume while maintaining manageable wiring complexity through systematic spatial organization of conductors.
4Reliability
If the number of parallel LED strings is increased to improve defect tolerance, then the reliability increases, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the LED configuration into a moderate number of parallel strings (e.g., 3 strings) that can be manufactured using standard production techniques. This segmentation level provides sufficient defect tolerance while remaining compatible with existing manufacturing capabilities, avoiding excessive complexity in assembly and wiring processes.
Solution Approach 2:
The patent optimizes parameters such as the number of strings, LEDs per string, and string interconnection patterns to achieve the best balance between defect tolerance and manufacturing ease. By carefully selecting these parameters within practical ranges, the patent improves reliability without pushing manufacturing complexity beyond reasonable limits.
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 configuration ensures that a defective string in an LED bulb is less noticeable, with the remaining strings compensating for the lost light output, reducing the perceived defect and return rate, while maintaining efficient light production and extending the operational lifetime of the LED dies.
Implementation Method 1
light emitting diodes (LEDs) can more efficiently convert electrical energy into light than can fluorescent bulbs
Data Source
AI summary
A linear lighting module includes a first string of series-connected LED dies and a second string of series-connected LED dies. The first string of LED dies is coupled in parallel with the second string of LED dies. All of the LED dies of the first and second strings are aligned with respect to one another. The LED dies of the first string and the second string form a combined string of interleaved LED dies such that an LED die of the second string is disposed between every successive pair of LED dies of the first string. The LED dies of the combined string are mounted on a flexible substrate. Each LED die of the combined string is electrically connected to two conductors. Except for the two end LED dies of the combined string, each successive LED die must be accessed by both conductors from alternating sides of the combined string.