Variable CCT Lighting via Dual Excitation Phosphor Control

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Solution Overview

Problem

Existing solid state lighting devices with variable correlated color temperature (CCT) using multiple phosphors struggle to maintain a single CCT within a specified range, especially when using more than two phosphors, making it difficult to achieve consistent color rendering index (CRI) across different operational states.

Innovation Solution

The use of plural excitation sources with different peak emissions and at least one phosphor material, where the phosphor is differentially excited by these sources, allowing for multiple operational states with distinct CCT values by adjusting the relative amount of peak emissions, thereby varying the CCT along the black body locus without relying solely on phosphor selection.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Adaptability or versatility

If multiple phosphors are used to achieve variable CCT, then color temperature adjustment range is improved, but CRI consistency deteriorates

Engineering Contradiction:

Improvecolor temperature adjustment rangeVSAvoidCRI consistency

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent changes the excitation parameters (wavelength and intensity ratios) rather than relying solely on phosphor composition changes. By adjusting the relative intensities of blue (440-480nm) and UV (380-420nm) excitation sources, the system achieves variable CCT while maintaining consistent CRI performance across different color temperatures.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent uses a universal phosphor blend composition that can be excited by multiple wavelengths (both UV and blue). This single phosphor formulation serves multiple functions by being differentially excited by different wavelength sources to produce various CCT values while maintaining high CRI, eliminating the need for multiple specialized phosphor blends.

Inventive Principle:

Principle #6Universality (Multi-functionality)

2Adaptability or versatility

If different phosphor blends are used for variable CCT, then CCT variation is improved, but manufacturing complexity increases

Engineering Contradiction:

ImproveCCT variationVSAvoidmanufacturing complexity

Core Design Contradiction:

Adaptability or versatilityVSDevice complexity

Solution Approach 1:

Instead of changing phosphor composition for different CCT values, the patent changes the excitation parameters (relative intensities of UV and blue LEDs). This approach maintains a single, consistent phosphor blend formulation, greatly simplifying manufacturing while still achieving wide CCT variation through electronic control of the dual excitation sources.

Inventive Principle:

Principle #35Parameter changes

3Adaptability or versatility

If RGB LEDs are used for variable CCT, then color adjustment capability is improved, but CRI performance deteriorates

Engineering Contradiction:

Improvecolor adjustment capabilityVSAvoidCRI performance

Core Design Contradiction:

Adaptability or versatilityVSReliability

Solution Approach 1:

The patent introduces phosphor materials as an intermediary between the LED excitation sources and the final light output. The phosphor converts portions of the UV and blue excitation light into yellow, red, and green wavelengths, creating a more complete spectrum that maintains high CRI while still enabling color temperature adjustment through varying the excitation source intensities.

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

This approach enables precise control of CCT values with minimal variation in CRI, allowing for a wide range of color temperature adjustments while maintaining high color rendering index, suitable for various lighting applications and emotional lighting effects.

Implementation Method 1

an LED can be coated or covered with a phosphor layer having a phosphor material that absorbs radiation energy in one portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum

Methodology Applied

Scientific EffectPhosphorescence: Phosphorescence

Implementation Method 2

a phosphor material that absorbs radiation energy in one portion of the electromagnetic spectrum and emits energy in another portion of the electromagnetic spectrum

Methodology Applied

Scientific EffectAbsorption (EM radiation): Absorption (EM radiation)

Data Source

PatentUS9642208B2Variable correlated color temperature luminary constructs

Publication Date: 2017.05.02 IDEAL IND LIGHTING LLC

AI summary

A lighting device comprising plural excitation sources configured to provide at least two excitation peak emissions of different wavelength and at least one phosphor material radiationally coupled to the plural light source, the lighting device having a plurality of operational states comprising a first operation state wherein excitation of the at least one phosphor material by a first peak emission from the plural excitation sources provides a first correlated color temperature (CCT) value, and at least one additional operational state wherein excitation of the at least one phosphor material by a second peak emission from the plural excitation sources provides at least one additional CCT value different from the first CCT value. Methods of varying the CCT value using the lighting device with controlled power distribution to the plural excitation sources.