Phosphor Wheel Light Processing Body for Color Purity
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Solution Overview
Problem
Existing projection display apparatuses using blue light and phosphor wheels struggle to separate blue light from fluorescence effectively, leading to mixed colors with lower color purity.
Innovation Solution
A phosphor wheel design with a substrate, circularly arranged phosphor regions, a light processing region with specific light processing bodies such as absorption layers, diffusion layers, or reflection fins, and a drive device to rotate the substrate, which reduces blue light mixing into fluorescence by controlling the optical paths of excitation and back-surface incident light.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If a light guide optical system with a dichroic mirror is used to separate blue light from fluorescence, then blue light can be reflected back through three mirrors, but blue light mixes into fluorescence reducing color purity
Solution Approach 1:
The phosphor wheel is segmented into multiple independent phosphor regions (red, green, blue) arranged circumferentially, with each region processed independently by the excitation light source. This segmentation allows separate optimization of each color region and prevents blue light from contaminating other color regions.
Solution Approach 2:
Different regions of the phosphor wheel are assigned different local properties - red phosphor in one region, green phosphor in another, and blue phosphor in another. The light processing bodies are also locally optimized for each region to control the optical path and prevent blue light mixing into the fluorescence output.
2Duration of action of moving object
If blue light is repeatedly reflected by three mirrors to return to the dichroic mirror, then the optical path is extended, but blue light contamination in fluorescence increases
Solution Approach 1:
The harmful back-surface reflected blue light is extracted and removed from the optical path by light processing bodies positioned in the light processing region. These processing bodies absorb or redirect the blue light before it can re-enter the fluorescence optical path through the dichroic mirror.
Solution Approach 2:
Light processing bodies are introduced as intermediary elements between the phosphor regions and the fluorescence output path. These intermediaries selectively process the blue light - either absorbing it or redirecting it - to prevent contamination of the fluorescence while maintaining the desired optical path duration.
3Manufacturing precision
If a light processing body is provided in the light processing region to control blue light, then color purity is improved, but device structure becomes more complex
Solution Approach 1:
The light processing bodies are merged with the phosphor wheel structure itself, integrating the blue light control function directly into the wheel rather than adding separate external components. This integration reduces overall device complexity while maintaining color purity improvements.
Solution Approach 2:
The phosphor wheel is designed with multi-functionality - it simultaneously serves as the rotating element that presents different phosphor regions to the excitation source, the structural platform that holds the light processing bodies, and the optical element that guides the fluorescence output. This multi-functionality reduces the need for additional separate components.
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 solution enhances the chromaticity of red and green light emitted by the projection display apparatus, achieving higher color purity by minimizing blue light contamination in the fluorescence.
Implementation Method 1
a light absorption processing body provided in a light processing region
Implementation Method 2
a phosphor that emits light in response to the excitation light
Data Source
AI summary
A phosphor wheel of exemplary embodiment in the present disclosure includes a substrate, a phosphor region circularly provided on one surface of the substrate, a light processing region circularly provided on an other surface of the substrate and entered by incident light, a light processing body provided in the light processing region, a light-transmissive region provided in the substrate, and a drive device rotating the substrate.