Notch Filtering Materials for LED Color Rendering

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Solution Overview

Problem

Current solid state lighting devices, such as LEDs, often fail to achieve desirable illumination characteristics like high Color Rendering Index (CRI) and Gamut Area Index (GAI), which are essential for accurately reproducing colors and providing a natural light spectrum, due to oversaturation or undersaturation of certain color spectra.

Innovation Solution

Incorporating notch filtering materials in coatings on LED chips or lumiphoric materials to filter light emissions, creating a spectral notch that enhances CRI and GAI values, thereby improving color rendering and gamut area.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If conventional LED packaging with lumiphoric materials is used, then the device structure is simple and easy to manufacture, but the Color Rendering Index (CRI) and Gamut Area Index (GAI) values are insufficient

Engineering Contradiction:

ImproveColor Rendering Index (CRI) and Gamut Area Index (GAI)VSAvoiddevice structure

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent implements nested filtering by placing the first notch filtering material between the blue LED chip and the yellow lumiphor, and the second notch filtering material between the yellow lumiphor and the external environment. This nested arrangement of multiple filtering layers within the LED package enables precise spectral control to achieve high CRI and GAI values while maintaining a relatively compact device structure.

Inventive Principle:

Principle #7Nested doll (Nesting)

Solution Approach 2:

The patent employs composite material strategies by combining multiple notch filtering materials with different spectral characteristics (first and second notch filtering materials with different center wavelengths) along with the yellow lumiphor material. This composite approach allows simultaneous optimization of multiple spectral regions to achieve superior color rendering and gamut properties.

Inventive Principle:

Principle #40Composite materials

2Manufacturing precision

If multiple notch filtering materials are added to improve CRI and GAI, then color rendering accuracy improves, but manufacturing complexity increases

Engineering Contradiction:

Improvecolor rendering accuracyVSAvoidmanufacturing process

Core Design Contradiction:

Manufacturing precisionVSEase of manufacture

Solution Approach 1:

The patent segments the spectral filtering function into two distinct stages: first notch filtering material positioned at the LED chip interface to control the excitation spectrum, and second notch filtering material positioned at the output interface to control the emitted spectrum. This segmentation allows each filtering stage to be optimized independently for its specific spectral region, improving overall color rendering accuracy while enabling modular manufacturing approaches.

Inventive Principle:

Principle #1Segmentation

3Illumination intensity

If lumiphoric materials are used to convert blue light to yellow, then white light is produced, but certain color spectra become oversaturated or undersaturated

Engineering Contradiction:

Improvewhite light outputVSAvoidspectral balance

Core Design Contradiction:

Illumination intensityVSMeasurement precision

Solution Approach 1:

The patent introduces notch filtering materials as intermediary spectral control elements between the blue LED chip and the yellow lumiphor, and between the lumiphor and the external environment. These intermediary filters selectively remove specific wavelength regions that would otherwise cause spectral imbalance, thereby achieving better spectral balance and preventing oversaturation or undersaturation of certain colors while maintaining efficient white light generation.

Inventive Principle:

Principle #24Intermediary (Mediator)

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 use of notch filtering materials in solid state lighting devices significantly enhances CRI and GAI values, leading to improved color rendering and gamut area, making the lighting more vibrant and accurate, while also potentially increasing luminous efficacy.

Implementation Method 1

a lumiphoric material arranged in a lumiphoric material coating deposited on the at least one electrically activated solid state emitter chip to receive at least a portion of emissions of the at least one electrically activated solid state emitter chip and responsively emit lumiphor emissions

Methodology Applied

Scientific EffectPhotoluminescence: Photoluminescence

Implementation Method 2

a notch filtering material arranged in a filter coating or layer deposited on the lumiphoric material coating, wherein the notch filtering material is arranged to receive at least a portion of the lumiphor emissions and filter the received lumiphor emissions to exhibit a spectral notch

Methodology Applied

Scientific EffectOptical filtering: Absorption (EM radiation)

Data Source

PatentUS9960322B2Solid state lighting devices incorporating notch filtering materials

Publication Date: 2018.05.01 CREELED INC

AI summary

Solid state lighting devices include one or more notch filtering materials arranged to filter light emissions to exhibit a spectral notch. At least one notch filtering material may be arranged in at least one coating deposited directly on an emitter chip or on a lumiphoric material that itself is coated or otherwise deposited on an emitter chip. A notch filtering material may be combined with a lumiphoric material. Emissions of a resulting lighting device may include a CRI Ra value of at least 80 and a GAI value in a range of from 75 to 100 or from 80 to 100.