Lightguide with segmented optical regions for appearance and output
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Solution Overview
Problem
Light absorption from coatings on lightguides reduces light output in linear lighting applications, particularly in automotive and commercial settings, where an aesthetically pleasing appearance is also desired.
Innovation Solution
The lightguide features separate regions with distinct optical properties: a first area with high optical reflectance and moderate transmittance for accent lighting, and a second area with high transmittance for functional illumination, using light extractors and a reflective layer to manage light exit angles and intensity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Shape
If a coating is applied to the lightguide to improve off-state appearance, then aesthetic appearance is improved, but light output is reduced due to light absorption
Solution Approach 1:
The lightguide surface is divided into multiple discrete light extractors rather than a continuous coating, allowing selective light extraction while maintaining aesthetic appearance in off-state
Solution Approach 2:
Different regions of the lightguide are equipped with different types of light extractors (first light extractors with higher reflectance for accent lighting, second light extractors with higher transmittance for functional illumination) to optimize both appearance and light output in different locations
2Illumination intensity
If light extractors are added to the lightguide to increase light output, then illumination intensity is improved, but device complexity increases
Solution Approach 1:
Multiple functions (light extraction, reflectance control, transmittance control, and aesthetic appearance) are merged into a single integrated lightguide structure with embedded light extractors, eliminating the need for separate components
Solution Approach 2:
The lightguide serves multiple functions simultaneously: it provides structural support, controls light extraction through integrated extractors, manages optical properties (reflectance and transmittance), and maintains aesthetic appearance in off-state
3Area of stationary object
If the lightguide length is extended to cover larger areas, then coverage area is improved, but light absorption increases reducing light output
Solution Approach 1:
Light extractors are distributed along the lightguide to proactively extract light before it travels long distances, compensating for attenuation and enabling extended coverage while maintaining sufficient light output
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 configuration enhances the off-state appearance while maintaining sufficient light output for both accent and functional illumination, reducing light absorption and extending the length of lightguides effectively.
Implementation Method 1
lightguide comprises features for extracting light that would otherwise be confined and propagate within the lightguide primarily by total internal reflection
Implementation Method 2
A reflective layer is disposed on at least a portion of the cladding layer and has an optical reflectance of at least 30% and an optical transmittance of at least 5% for normally incident light at the desired wavelength, such that at least 2% of light extracted by the light extractors exits the lightguide through the reflective layer
Data Source
AI summary
A lightguide includes features for extracting light that would otherwise be confined and propagate within the lightguide primarily by total internal reflection. A first portion of light propagating within the lightguide and extracted exits the lightguide through a first area of the lightguide having an optical reflectance of at least 30% and an optical transmittance of at least 5% for normally incident light at a wavelength of the extracted light. A second portion of light propagating within the lightguide and extracted exits the lightguide through a different second area of the lightguide having an optical transmittance of at least 80% for normally incident light at the wavelength of the extracted light.