Electroluminescent Device Light-Converting Element Shape
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Solution Overview
Problem
Current phosphor-converted electroluminescent devices (pcLEDs) exhibit significant variation in correlated color temperature over the viewing angle, which is not easily adjustable, limiting their application in various lighting scenarios that require either homogeneity or specific inhomogeneity in color temperature distribution.
Innovation Solution
An electroluminescent device with a light-converting element having a shape adapted to the emission characteristic of the electroluminescent light source, where the edge surface is arranged at an angle between 20° and 70° to the layer normal, allowing for controlled variation of correlated color temperature as a function of the viewing angle, achieved through optical connection, ceramic materials, and specific geometric configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If phosphor layers with high scattering ability are used to convert light, then the angle distribution of primary radiation is transformed into cosine distribution of secondary radiation, but the package gain of the light source is reduced
Solution Approach 1:
The patent applies different scattering properties to different regions of the light-converting element. The first region (facing the light source) has high scattering ability to convert primary radiation to secondary radiation with cosine angle distribution. The second region (facing the viewer) has low scattering ability to maintain high package gain and transmit light efficiently. This spatial differentiation of scattering properties resolves the contradiction between achieving proper angle distribution and maintaining high energy efficiency.
2Adaptability or versatility
If phosphor powder layers with high optical scattering are used, then the correlated color temperature can be set, but the variation in correlated color temperature over viewing angle increases
Solution Approach 1:
The patent divides the light-converting element into regions with different scattering abilities. The first region converts primary radiation to secondary radiation with appropriate scattering, while the second region minimizes scattering to maintain consistent color temperature delivery to the viewer. This local differentiation enables color temperature control while reducing viewing angle dependence.
Solution Approach 2:
The light-converting element is designed with asymmetric scattering properties - the first surface has high scattering ability while the second surface has low scattering ability. This asymmetric design allows the element to perform different functions at different interfaces, achieving both color temperature conversion and stable color delivery across viewing angles.
3Adaptability or versatility
If the edge surface is arranged at a specific angle to the layer normal, then a defined correlated color temperature as a function of viewing angle is generated, but the device complexity increases
Solution Approach 1:
The patent achieves color temperature adjustment by changing the geometric parameter of the edge surface angle relative to the layer normal. By varying this angular parameter, different correlated color temperatures can be generated as a function of viewing angle. This parameter-based control method provides adaptability without requiring complex multi-component systems.
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
This solution enables a defined correlated color temperature over the viewing angle, improving the package gain and allowing for tailored color temperature adjustments, resulting in more homogeneous or application-specific light emission characteristics.
Implementation Method 1
a light-converting element for converting at least part of the primary radiation into a secondary radiation
Data Source
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AI summary
An electroluminescent device comprising at least one electroluminescent light source (2) with an electroluminescent layer (21) for emitting a primary radiation with an emission characteristic around a mean emission direction (5), and at least one light-converting element (3) for converting at least part of the primary radiation into a secondary radiation, wherein the shape of the light-converting element (3) is adapted to the emission characteristic of the electroluminescent light source (2) so as to generate a defined correlated color temperature as a function of a viewing angle (10).