Optical Plate Spacing for LED Wavelength Conversion
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Solution Overview
Problem
Conventional lighting devices using light emitting diodes (LEDs) face challenges in wavelength conversion and light leakage, leading to reduced efficiency and reliability due to the proximity of the phosphor layer to the light emitting chip, which causes heat degradation and optical loss.
Innovation Solution
A lighting device design incorporating an optical plate with a phosphor layer, transparent films, and a semi-transmissive mirror, where the optical plate is spaced apart from the light emitting chip to facilitate wavelength conversion and reduce light leakage, featuring a support structure and adhesive members to enhance bonding and light extraction.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If the phosphor layer is placed close to the light emitting chip for efficient wavelength conversion, then the wavelength conversion efficiency is improved, but the heat degradation and optical loss increase
Solution Approach 1:
A transparent adhesive layer is introduced as an intermediary between the light emitting chip and the phosphor layer. This adhesive layer acts as a thermal barrier that reduces heat transfer to the phosphor layer, thereby decreasing heat-induced degradation and extending the phosphor layer's lifespan, while still allowing sufficient light transmission for wavelength conversion
Solution Approach 2:
The patent introduces a vertical spacing dimension by using a transparent adhesive layer with a specific thickness (e.g., 1-10 μm). This creates a controlled gap between the light emitting chip and phosphor layer, separating them in the vertical dimension to reduce thermal interaction while maintaining optical coupling for efficient wavelength conversion
2Reliability
If the optical plate is spaced apart from the light emitting chip to reduce heat degradation, then the phosphor layer lifespan is extended, but the wavelength conversion efficiency may decrease
Solution Approach 1:
The patent optimizes the thickness parameter of the transparent adhesive layer to achieve a balance between thermal isolation and optical coupling. By carefully controlling the adhesive layer thickness (e.g., 1-10 μm), sufficient light transmission is maintained for efficient wavelength conversion while providing adequate thermal barrier to extend phosphor layer lifespan
3Device complexity
If conventional LED structures are used without semi-transmissive mirrors, then the device complexity is low, but light leakage occurs reducing overall efficiency
Solution Approach 1:
Semi-transmissive mirrors are integrated into the optical plate structure to convert previously lost light (that would have leaked out) into useful light by reflecting it back toward the exit surface. The mirrors are positioned and designed to reflect specific angles of light back into the optical plate, turning energy loss into additional light output that contributes to the overall luminous flux
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 extends the life of the phosphor layer, improves light extraction efficiency, and enhances the reliability of the lighting device by reducing heat-induced degradation and optical loss, while allowing for miniaturization and improved color reproducibility.
Implementation Method 1
an optical plate spaced apart from the light emitting chip, and including a phosphor layer
Implementation Method 2
a semi-transmissive mirror that reflects and transmits incident light
Data Source
AI summary
Disclosed according to one embodiment is a lighting device comprising: a light emitting device having a light emitting chip; and an optical plate corresponding to the light emitting chip, wherein the optical plate comprises: a phosphor layer; a transparent film on the upside and/or downside of the phosphor layer; and a support surrounding the outside of the phosphor layer.