Phosphor Wheel Grooves for Fluorescence Extraction
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Solution Overview
Problem
Fluorescence extraction efficiency decreases in light source apparatuses with phosphor wheels when grooves are not present in the excitation light receiving surface, leading to reduced luminance in projector images.
Innovation Solution
A light source apparatus with a wavelength conversion layer and traveling direction changers, where the changers are formed in a radial or lattice pattern around the axis of rotation, and their width decreases or increases with distance from the axis, effectively changing the traveling direction of fluorescence and suppressing lateral spread, thereby maintaining efficient excitation light usage and fluorescence extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If grooves are formed in the phosphor wheel to suppress lateral spread of fluorescence, then fluorescence extraction efficiency is improved in grooved regions, but fluorescence extraction efficiency decreases in regions where grooves are not present
Solution Approach 1:
The patent applies local quality by forming grooves only in specific regions of the phosphor wheel where lateral spread of fluorescence needs to be suppressed. The grooves are positioned in the circumferential direction at the light incident surface, creating localized structural modifications that control fluorescence extraction efficiency in specific areas while leaving other regions unchanged, thus resolving the contradiction between improving efficiency in needed areas and maintaining uniformity across the entire wheel.
2Ease of manufacture
If the wavelength conversion layer width is increased to cover the excitation light incident region, then fluorescence extraction efficiency is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the wavelength conversion layer into multiple regions with different widths in the radial direction. By dividing the layer into zones with varying thicknesses, the design achieves effective coverage of the excitation light incident region while avoiding the complexity of a uniformly thick layer. This segmentation allows optimized fluorescence extraction without proportionally increasing overall device complexity.
Solution Approach 2:
The wavelength conversion layer is designed with locally varying properties, where the width in the radial direction changes across different regions. This local quality approach ensures that the layer thickness is optimized specifically in areas where excitation light incidents, while other regions have different dimensions, thereby improving fluorescence extraction efficiency without uniformly increasing device complexity throughout the entire structure.
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 effectively suppresses the decrease in fluorescence extraction efficiency, allowing for the formation and projection of high-luminance images by ensuring consistent and efficient use of excitation light and fluorescence emission.
Implementation Method 1
a phosphor (or wavelength conversion element) that is excited with excitation light outputted from a solid-state light source and incident on the phosphor to emit fluorescence having a wavelength different from the wavelength of the excitation light
Implementation Method 2
a plurality of traveling direction changers that are formed in the wavelength conversion layer and change a traveling direction of the fluorescence
Data Source
AI summary
A light source apparatus according to an aspect of the invention includes an excitation light source that emits excitation light, a wavelength conversion layer on which the excitation light is incident and which converts the wavelength of the excitation light to emit fluorescence, a plurality of traveling direction changers that are formed in the wavelength conversion layer and change the traveling direction of the fluorescence, and a substrate on which the wavelength conversion layer is provided. The substrate is rotated around an axis of rotation to change the position on which the excitation light is incident on the wavelength conversion layer over time, and the interval between the plurality of traveling direction changers is smaller than the size of the region on which the excitation light is incident.