Lightguide Light Extraction Structures for Uniform Backlighting
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Solution Overview
Problem
Conventional lightguides used in backlights for electronic devices often suffer from non-uniform brightness, leading to observable defects and increased power consumption, particularly in battery-powered portable devices.
Innovation Solution
The use of light extractors arranged in a pattern on the surface of the lightguide, with varying areal density and efficiency to enhance uniformity of light output and reduce power requirements, is implemented. This includes configuring light extractors with different shape factors to control extraction efficiency, ensuring higher densities closer to the light source for improved defect hiding and uniform illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If light scattering elements (diffusers) are used to mask non-uniformities, then uniformity of brightness is improved, but power consumption increases and light is directed away from preferred viewing axis
Solution Approach 1:
The patent applies local quality by varying the areal density of light extractors across different regions of the lightguide. Regions closer to the light source have higher areal density of extractors, while regions farther away have lower areal density. This non-uniform distribution compensates for the natural non-uniformity of light propagation, achieving uniform brightness without requiring additional power or scattering elements.
2Illumination intensity
If light extractors with high extraction efficiency are used, then light output uniformity is improved, but observable defects increase due to lower areal density
Solution Approach 1:
The patent implements local quality by making the areal density of light extractors position-dependent. In regions where extraction efficiency is high (typically farther from the light source), the areal density is reduced to prevent over-extraction and maintain uniformity. In regions closer to the light source where extraction efficiency is lower, the areal density is increased to compensate. This spatially varying areal density ensures uniform light output while preventing observable defects.
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 achieves enhanced uniformity of light output across the lightguide surface, reducing observable defects and lowering power consumption by optimizing light extraction efficiency, thereby improving the performance and efficiency of backlights in electronic devices.
Implementation Method 1
Light extractors have been used to extract light from lightguides and to enhance the uniformity of the lightguide brightness
Implementation Method 2
At least a portion of the composition is imagewise exposed to light sufficient to cause simultaneous absorption of at least two photons, thereby inducing at least one acid- or radical-initiated chemical reaction
Data Source
AI summary
Lightguides, devices incorporating lightguides, and processes for making lightguides are described. A lightguide includes light extractors arranged in a pattern on a surface of the lightguide. The pattern of light extractors is arranged to enhance uniformity of light output across a surface of the lightguide and to provide enhanced defect hiding. The efficiency of the light extractors is controlled by a shape factor. The areal density of the light extractors across the surface of the lightguide may be substantially constant or may decrease along the direction of propagation of light from the light source.