Flexible LED Calibration for Encapsulant Color Shift

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Solution Overview

Problem

Flexible LED modules emit a bluer light compared to their non-flex counterparts due to the introduction of a flexible encapsulant, requiring adjustments in the calibration process to account for the color shift caused by the encapsulant.

Innovation Solution

A method for calibrating flexible LED lighting elements that involves defining a target color, selecting initial calibration coefficients, and iteratively updating them to match the target color within a predefined tolerance, taking into account the properties of the encapsulant and white LEDs, while ensuring convergence in the color space.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If a flexible encapsulant is introduced to enable flexible LED modules, then flexibility and adaptability are improved, but color accuracy deteriorates due to blue light emission and color shift

Engineering Contradiction:

ImproveflexibilityVSAvoidcolor accuracy

Core Design Contradiction:

Adaptability or versatilityVSManufacturing precision

Solution Approach 1:

The patent applies parameter changes by adjusting calibration coefficients for red, green, and blue LEDs to compensate for the color shift caused by the flexible encapsulant. The system measures actual color output and iteratively updates the calibration coefficients (R_cal, G_cal, B_cal) to achieve target color values, thereby correcting the blue light emission and color accuracy deterioration while maintaining flexibility.

Inventive Principle:

Principle #35Parameter changes

2Manufacturing precision

If calibration coefficients are iteratively updated to correct color shift, then color accuracy is improved, but calibration time and process complexity increase

Engineering Contradiction:

Improvecolor accuracyVSAvoidcalibration time

Core Design Contradiction:

Manufacturing precisionVSLoss of time

Solution Approach 1:

The patent implements feedback by measuring the actual color output of the flexible LED module and comparing it with target color values. Based on the color difference, the system iteratively updates the calibration coefficients for red, green, and blue LEDs. This closed-loop feedback process continues until the measured color matches the target color within acceptable tolerances, thereby achieving accurate color correction through systematic coefficient adjustment.

Inventive Principle:

Principle #23Feedback

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 calibration method effectively adjusts for the color shift caused by the flexible encapsulant, ensuring accurate color reproduction and compensating for intensity changes and thermal effects, thereby aligning the flexible LED module's color output with non-flexible counterparts.

Implementation Method 1

an LED unit encapsulant that covers the LEDs and contains embedded phosphor particles of different colors

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Data Source

PatentEP3289283B1Flexible LED lighting element

Publication Date: 2022.11.02 BE AEROSPACE INC

Figure 1A~1B
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AI summary

A flexible LED lighting module includes a flexible housing and flexible PCB to which LED units are mounted. An encapsulant fills a channel of the flexible housing and has a same or similar optical refractive index value as is used in the LED unit to hold phosphorous particles used for coloring of the LED. Use of the encapsulant changes the color of the light ultimately emitted from the flexible LED lighting module, and this factor is corrected for in calibration processes associated with the flexible LED lighting module.