Wavelength Conversion Layout for Yellow Ring-Free White Light

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Solution Overview

Problem

The use of light-homogenizing optical elements like fly-eye lenses or square rods in laser-activated remote phosphor technology leads to increased volume, cost, and reduced light collection efficiency, while causing a 'yellow ring' issue due to spot diffusion, affecting color uniformity in projected white light.

Innovation Solution

A light source system with a first and second excitation light source arranged on either side of a wavelength conversion material layer, featuring a transmission and non-transmission area, where the second excitation light is incident only from the edge area to enhance color uniformity by converting light at the edges, using a reflective layer to block unwanted light.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Stability of the object's composition

If light-homogenizing optical elements (fly-eye lenses or square rods) are used to shape and homogenize the emitted white light spot, then color uniformity is improved, but device volume, cost, and complexity increase while light collection efficiency decreases

Engineering Contradiction:
Improvecolor uniformityVSAvoidlight path complexity
Core Design Contradiction:
Stability of the object's compositionVSDevice complexity

Solution Approach 1:

The patent extracts and removes the complex light-homogenizing optical elements (fly-eye lenses, square rods) from the system. Instead of using these additional components, the invention modifies the wavelength conversion structure itself by defining transmission and non-transmission areas on the surface of the wavelength conversion material layer, thereby achieving color uniformity without increasing device complexity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The wavelength conversion material layer is given multiple functions: it not only converts the wavelength of excitation light but also acts as a light-homogenizing element through its transmission and non-transmission area pattern. This eliminates the need for separate homogenizing optical elements, reducing device complexity while maintaining color uniformity

Inventive Principle:
Principle #6Universality (Multi-functionality)

2Stability of the object's composition

If light-homogenizing optical elements are used to eliminate the yellow ring effect, then color uniformity is improved, but light collection efficiency is reduced

Engineering Contradiction:
Improvecolor uniformityVSAvoidlight collection efficiency
Core Design Contradiction:
Stability of the object's compositionVSLoss of energy

Solution Approach 1:

The patent removes intermediate optical elements that cause light loss. By directly patterning the wavelength conversion material layer with transmission and non-transmission areas, the design eliminates the need for fly-eye lenses or square rods that would otherwise absorb or scatter light, thereby maintaining high light collection efficiency while achieving color uniformity

Inventive Principle:
Principle #2Taking out (Extraction)

Solution Approach 2:

The patent merges the wavelength conversion function and the light homogenization function into a single integrated structure (the wavelength conversion material layer with patterned surface). This eliminates the need for separate optical elements in the light path, reducing light loss and improving collection efficiency while still achieving the desired color uniformity

Inventive Principle:
Principle #5Merging (Combining)

3Use of energy by moving object

If the wavelength conversion material layer converts excitation light uniformly across the entire surface, then light conversion efficiency is maximized, but the yellow ring effect occurs due to spot diffusion

Engineering Contradiction:
Improvelight conversion efficiencyVSAvoidyellow ring effect
Core Design Contradiction:
Use of energy by moving objectVSObject-generated harmful factors

Solution Approach 1:

The patent applies local quality by creating different regions (transmission areas and non-transmission areas) on the surface of the wavelength conversion material layer. The non-transmission areas are positioned to receive excitation light for efficient conversion, while the transmission areas allow unconverted light to pass through, preventing the yellow ring effect caused by uniform conversion across the entire surface

Inventive Principle:
Principle #3Local quality

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

Improves color uniformity by addressing the 'yellow ring' issue and enhancing light collection efficiency without increasing volume or cost.

Implementation Method 1

the wavelength conversion material layer is configured to receive the first excitation light and convert at least part of the first excitation light into a first excited light and then emit the first excited light

Methodology Applied
Scientific EffectWavelength conversion: Photoluminescence

Implementation Method 2

the wavelength conversion material layer converts at least part of the second excitation light into the second excited light and then emits the second excited light

Methodology Applied
Scientific EffectWavelength conversion: Photoluminescence

Implementation Method 3

transmits part of the second excitation light that is not absorbed by the wavelength conversion material layer

Methodology Applied
Scientific EffectLight transmission: Absorption (EM radiation)

Data Source

PatentEP4006404B1Light source system and illumination apparatus
Publication Date: 2025.12.31 YLX INC
  • EP4006404B1 patent drawingFigure 1
  • EP4006404B1 patent drawingFigure 2~3
  • EP4006404B1 patent drawingFigure 4

AI summary

Disclosed is a light source system (10), comprising: a first excitation light source (11) for emitting first excitation light; a wavelength conversion structure (13) comprising a wavelength conversion material layer (131) used for receiving the first excitation light and converting at least part of the first excitation light into first excited light and then emitting same, with a transmission area (A) and a non-transmission area (B) surrounded by the transmission area (A) being defined in a surface, opposite an incident surface of the first excitation light, of the wavelength conversion material layer (131); and a second excitation light source (12) arranged on a side, away from the incident surface of the first excitation light, of the wavelength conversion structure (13) and used for emitting second excitation light that is emitted into the wavelength conversion material layer (131) from the transmission area (A). The wavelength conversion material layer (131) converts at least part of the second excitation light into second excited light and then emits same, and that part of the second excitation light which is not absorbed by the wavelength conversion material layer (131) is transmitted. An illumination apparatus comprising the light source system (10) is disclosed.