Composite Reflection Layer for Phosphor Wheel Efficiency
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Solution Overview
Problem
Conventional reflective phosphor wheels in illumination systems face challenges in achieving high reflection rates across the entire visible light spectrum (400 nm-700 nm) and all angle of incidence (AOI) regimes due to limitations in metallic and dielectric reflective layers, leading to reduced output efficiency.
Innovation Solution
A composite reflective layer is introduced, comprising a metallic first reflection layer and a dielectric multilayer second reflection layer, which enhances the reflection rate by adjusting the reflection spectrum, thereby compensating for large-angle incidence and improving output efficiency across the visible spectrum.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If a metallic reflective layer is used, then the reflection rate is improved (95%-97% for argentum, 85%-93% for aluminum), but the reliability deteriorates because the metallic reflector is easier to be oxidized/corroded and the transition is easier to be occurred
Solution Approach 1:
The patent employs a composite reflective layer structure combining a metallic reflective layer (silver or aluminum) with a dielectric protective layer. The metallic layer provides high reflection rate (95%-97% for argentum, 85%-93% for aluminum), while the dielectric protective layer prevents oxidation and corrosion, thereby maintaining both high reflectivity and long-term reliability of the reflective system.
2Loss of energy
If a dielectric multilayer reflection coating is used to achieve higher reflection rate nearing 99%, then the reflection rate is improved, but the reliability deteriorates because the dielectric multilayer reflection coating is much more dependent on the angle of incidence (AOI). With increase of the incident angle, the blue-shift of the reflection spectrum is occurred, and the reflection rate is probably decreased
Solution Approach 1:
The patent creates a composite reflective system combining metallic and dielectric multilayer structures. The metallic layer provides broad-spectrum, angle-insensitive reflection, while the dielectric multilayer enhances reflection rate for specific wavelengths. This composite approach achieves high reflection rate (nearing 99%) while maintaining reasonable adaptability to different angles of incidence, as the metallic component compensates for the dielectric's angle-dependent behavior.
Solution Approach 2:
The patent applies different materials with different properties at different locations within the reflective layer structure. The metallic layer serves as a universal, angle-insensitive reflector, while the dielectric multilayer is strategically positioned to enhance reflection at specific wavelengths and angles. This local differentiation allows the system to achieve high overall reflection rate while maintaining adaptability across various incident angles.
3Device complexity
If the illuminating layer is located on the reflective layer in the structure of the conventional reflective phosphor wheel, then the structure is simplified, but the output efficiency deteriorates because the transmission rate of the large-angle incident light is obviously increased, causing the light leakage from the reflective layer to the substrate
Solution Approach 1:
The patent inverts the conventional structure by placing the reflective layer on the substrate first, then positioning the phosphor layer above it. This inverted arrangement ensures that light reflected from the substrate passes through the phosphor layer, preventing light leakage and improving output efficiency. The structure maintains simplicity while achieving better optical performance through this structural inversion.
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 composite reflection layer achieves a reflection rate of over 80% at 60° AOI and increases output efficiency for yellow, green, and red light regions, enhancing the overall luminance and color accuracy in illumination systems.
Implementation Method 1
The first reflection layer is a metallic reflection layer... for reflecting the second waveband light
Implementation Method 2
The second reflection layer comprises a dielectric multilayer film... for adjusting the reflection spectrum of the first reflection layer
Implementation Method 3
The phosphor layer is disposed on the substrate for converting the first waveband light into a second waveband light
Data Source
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AI summary
An optical wavelength-converting device used for converting a first waveband light includes a substrate, a phosphor layer and a composite reflection layer. The phosphor layer is disposed on the substrate for converting the first waveband light into a second waveband light. The composite reflection layer includes a first reflection layer and a second reflection layer. The first reflection layer is disposed between the substrate and the phosphor layer and adjacent to the substrate for reflecting the second waveband light, such that the second waveband light is transmitted through the phosphor layer so as to be outputted. The second reflection layer is disposed between the first reflection layer and the phosphor layer for adjusting the reflection spectrum of the first reflection layer, thereby enhancing the reflection rate of the composite reflection layer. As a result, the output efficiency of the wide-angle and wide-spectrum light is increased.