Illuminant with Refractive Index Connecting Layer
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Solution Overview
Problem
Existing luminous elements are visible under daylight conditions, compromising their aesthetic appeal and functionality, as they do not provide a homogeneous impression due to the visibility of display symbols or patterns even without backlighting.
Innovation Solution
A luminous element with a transparent substrate layer, a connecting layer of different refractive index, and a metallic, light-transmitting layer, where decoupling structures in the substrate layer allow light to be coupled out only when needed, making the metallic layer appear homogeneous without backlighting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of information
If a transparent substrate with metal coating and display symbols is used, then luminous information can be displayed, but the display symbols remain visible under daylight conditions, compromising aesthetic appeal
Solution Approach 1:
A connecting layer with different refractive index is introduced between the transparent substrate and the metallic layer. This intermediary layer creates optical decoupling that prevents the substrate's extraction structures from being visible through the metallic layer under daylight conditions, while still allowing light to pass through when backlit for information display.
Solution Approach 2:
The metallic layer is designed with spatially varying properties: it is translucent in regions where light extraction occurs (allowing luminous information to pass through) while maintaining a homogeneous, non-reflective appearance in other regions under daylight conditions. This local differentiation resolves the contradiction between displaying information and maintaining aesthetic appeal.
2Loss of information
If a metallic layer with extraction structures is used for light output, then luminous information can be generated, but the surface appears non-homogeneous without backlighting
Solution Approach 1:
The connecting layer acts as an optical intermediary that masks the extraction structures on the metallic layer's outer surface. By matching or contrasting the refractive index appropriately, it creates a homogeneous appearance under daylight while permitting light extraction when the substrate is backlit, thus maintaining surface homogeneity without compromising luminous information generation.
Solution Approach 2:
The metallic layer's optical properties are optimized to appear non-reflective and homogeneous under ambient daylight conditions, while becoming translucent and revealing the extraction structures only when backlit. This dynamic optical behavior, achieved through careful selection of metallic material and layer thickness, resolves the contradiction between surface appearance and light extraction functionality.
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 allows for the generation of luminous information that is optically homogeneous and appealing under daylight conditions, ensuring the metallic surface appears shiny and reflective without revealing the underlying structuring, enhancing both aesthetics and functionality.
Implementation Method 1
The connecting layer has a second refractive index that differs from the first... suitable for extracting light propagating within the substrate layer
Data Source
Figure 1
Figure 2~3
Figure 4+
AI summary
The present invention relates to an illuminant having a transparent substrate layer (1) with a first refractive index, a connecting layer (2) with a second refractive index that differs from the first refractive index, and a metallic, light-transmitting layer (3), wherein the connecting layer (2) is arranged between the substrate layer (1) and the metallic layer (3) and wherein the substrate layer (1) has a plurality of output-coupling structures (5) on the side facing the connecting layer (2), said output-coupling structures being suitable for output-coupling light that is propagating within the substrate layer (1) from the substrate layer (1) in the direction of the metallic layer (3).