LED Panel Testing Correction for Light Interference
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Solution Overview
Problem
The existing LED testing processes are costly and prone to contamination or damage due to the complexity of handling individual LED units post-singulation, and previous high-throughput testing methods, such as the BTS256-LED tester, are not suitable for high-throughput applications as they require precise manual positioning.
Innovation Solution
A method and system for generating a correction function to account for light re-emission from inactive LEDs during on-panel testing, using a detector with a field of view and a mask to vary the number of inactive LEDs, allowing for the calculation of correction factors based on the number of inactive LEDs within the field of view, which are then applied to measured optical parameters.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If post-singulation unit-by-unit testing is performed, then measurement precision is improved, but device complexity and handling cost increase
Solution Approach 1:
The testing process is segmented into two distinct phases: (1) a calibration phase performed once on a reference LED to establish baseline optical parameters, and (2) a measurement phase performed on each test LED using the calibrated system. This segmentation allows precise individual LED measurement while avoiding repeated complex calibration procedures, thereby reducing overall device complexity and handling cost.
2Productivity
If direct on-panel testing is performed, then productivity is improved, but measurement precision deteriorates due to light interference
Solution Approach 1:
The harmful factor of light interference from adjacent LEDs is extracted and isolated as a separate variable. The patent develops correction algorithms that specifically calculate and remove the contribution of neighboring LED light based on their known spatial positions and optical characteristics. This allows on-panel testing to proceed with high productivity while maintaining measurement precision through mathematical correction of the extracted interference component.
Solution Approach 2:
The patent exploits the asymmetric spatial relationship between the active test LED and inactive adjacent LEDs. By knowing the precise geometric arrangement and optical properties of each LED position on the panel, the system can asymmetrically weight and correct for interference from specific neighboring LEDs based on their distance and angular relationship to the detector, thereby removing interference while preserving the true signal from the test LED.
3Measurement precision
If manual positioning with conical adapter is used, then measurement precision is improved, but ease of operation and productivity worsen
Solution Approach 1:
The patent replaces the mechanical conical adapter positioning system with an automated optical detection and correction system. Instead of using physical masks that require precise manual alignment, the system uses software-based correction algorithms that automatically calculate and compensate for light interference from adjacent LEDs. This substitution eliminates the need for manual positioning operations while maintaining measurement precision through computational correction.
4Measurement precision
If individual LED handling is performed, then measurement precision is improved, but loss of time and productivity worsen
Solution Approach 1:
The patent merges multiple measurement operations into a single on-panel testing process. Instead of requiring separate handling, positioning, and measurement of each individual LED, the system performs measurements on all LEDs simultaneously while they remain mounted on the panel. The merging of these operations dramatically reduces the time lost to handling and positioning while maintaining measurement precision through the integrated correction algorithm that accounts for panel-level light interference.
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 approach enables high-throughput, cost-effective LED testing by reducing handling and risk of damage, while providing a map of correction factors for accurate optical and electrical characterization before singulation, allowing for efficient binning and packing.
Implementation Method 1
detecting light emitted by a reference LED and reflected from one or more inactive LEDs on a panel within a field of view of a detector
Implementation Method 2
Light from the DUT is reflected from the integrating sphere, is absorbed by phosphors of the adjacent LEDs, and is in turn re-emitted into the detector aperture
Implementation Method 3
absorbed by phosphors of the adjacent LEDs, and is in turn re-emitted into the detector aperture
Data Source
AI summary
Method of generating a correction function for a light-emitting diode (LED) testing process, including: detecting light emitted by a reference LED and reflected from inactive LEDs on a panel within a field of view of a detector; varying a number of the inactive LEDs to derive uncorrected values of an optical parameter as a function of the number of inactive LEDs; detecting light emitted by the reference LED, or by an active LED having identical optical properties, in the absence of any other LEDs, to determine at least one reference value for each optical parameter; and calculating differences between the uncorrected values and each reference value to generate the correction function, the correction function being based on the number of inactive LEDs which are arranged within the field of view of the detector in the light detecting step.