Lighting Device Light Conversion Unit High Irradiance Stability
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Solution Overview
Problem
Existing light conversion elements in lighting devices are optimized for moderate laser power density and fail to maintain high efficiency when operated close to the irradiance limit, leading to a rapid drop in light output.
Innovation Solution
A lighting device with a light conversion unit containing optically active elements like Ce, Eu, Pr, and Sm, optimized with a specific diffuse reflectance (SDR) to maintain high luminous flux and efficacy even at high irradiance levels, using a substrate and binder for enhanced performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light conversion elements are optimized for high efficiency at moderate laser power density, then luminous efficiency is improved, but performance deteriorates when operated close to the irradiance limit
Solution Approach 1:
The patent changes the optical parameters of the light conversion element by optimizing its thickness and diffuse reflectance properties. Specifically, it adjusts the thickness to achieve a specific diffuse reflectance (SDR) value that optimizes performance at high irradiance levels, representing a parameter change approach to resolve the contradiction between moderate-power efficiency and high-power stability
Solution Approach 2:
The patent introduces dynamic adaptability by optimizing the light conversion element to respond differently to varying irradiance levels. The element is designed with specific optical properties that allow it to maintain stable performance across a wide range of irradiance conditions, from moderate to near-limit levels, representing a dynamic optimization approach
2Productivity
If light conversion elements are operated close to the irradiance limit to achieve high light output, then luminous flux is improved, but efficiency deteriorates rapidly
Solution Approach 1:
The patent applies preliminary optimization to the light conversion element's optical properties before operation. By pre-calculating and setting the thickness and diffuse reflectance characteristics, the element is prepared to maintain efficient energy conversion even when operated at high irradiance levels near the limit, preventing the rapid efficiency drop that would otherwise occur
Solution Approach 2:
The patent establishes an optimization feedback loop where the thickness and diffuse reflectance properties are adjusted based on measured or simulated performance data. This iterative optimization process ensures that the light conversion element achieves the best possible balance between luminous flux output and efficiency at high irradiance conditions
3Productivity
If the thickness of the light conversion element is increased to improve light conversion, then luminous flux is improved, but diffuse reflectance characteristics deteriorate
Solution Approach 1:
The patent applies parameter optimization by establishing a specific relationship between thickness and diffuse reflectance. Rather than independently maximizing either parameter, it finds the optimal thickness value that achieves the desired diffuse reflectance (SDR) characteristic, resolving the contradiction between light conversion effectiveness and reflectance properties
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 ensures a stable and optimized light output at high irradiance levels, achieving a good compromise between luminous efficiency and efficacy by controlling diffuse reflectance and using reflective layers and coatings.
Implementation Method 1
a light conversion element (1) having a front side, a rear side, and a thickness t extending from the front side to the rear side... the light conversion element is set up for irradiation on its front side with the primary light (I0)... and for diffuse emission of secondary light (IEM) with an altered wavelength compared to the primary light
Implementation Method 2
The light conversion element is set up for irradiation on its front side with the primary light (I0) and for diffuse reflectance of primary light (IREM), for specular reflection of primary light (IFRE)
Implementation Method 3
The optional substrate is joined directly or indirectly to the rear side of the light conversion element and is optionally in the form of a heat sink
Data Source
AI summary
A lighting device includes: a light conversion unit including a light conversion element including a material containing an optically active element from lanthanoids, wherein:the light conversion element includes a front side, a rear side, and a thickness (t),the light conversion element is set up for an irradiation on the front side with a primary light (I0), for a diffuse reflectance of the primary light (IREM), for a specular reflection of the primary light (IFRE), and for a diffuse emission of a secondary light (IEM) with an altered wavelength compared to the primary light, andthe light conversion unit has a specific diffuse reflectance SDR=t−1·IREM/(I0−IFRE), such that a luminous flux emitted by the light conversion unit at an irradiance limit of the light conversion unit with regard to a variation in the proportion of the optically active element is at most 4 mm−1 away from a maximum.