Selective LED Surface Roughening for Light Extraction Control
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Solution Overview
Problem
Existing methods for enhancing light extraction efficiency in LEDs through roughening of the emitting surface often result in excessive light output, making it difficult to control and achieve specific lighting effects while being costly and limited in precision.
Innovation Solution
The method involves using photo-lithographic techniques to selectively roughen specific areas of the LED surface, allowing precise control of light extraction efficiency by varying the proportion of roughened surface area, independent of the roughening process, and creating desired light emission patterns.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the entire light emitting surface is roughened to maximize light extraction efficiency, then light extraction efficiency is improved, but light output becomes uncontrollable and exceeds customer specifications
Solution Approach 1:
The patent applies local quality by roughening only specific regions of the light emitting surface rather than the entire surface. Different areas have different roughness characteristics, allowing selective light extraction in certain zones while maintaining smooth surfaces in other areas for controlled light output, thus resolving the contradiction between maximizing extraction efficiency and maintaining controllability
Solution Approach 2:
The light emitting surface is segmented into multiple regions with different roughness treatments. By dividing the surface into roughened and non-roughened zones, the patent enables independent control of light extraction in different segments, allowing overall light output to be adjusted by varying the proportion of roughened area while maintaining high extraction efficiency where needed
2Ease of manufacture
If conventional roughening processes are used to control light extraction, then manufacturing simplicity is maintained, but manufacturing precision and control over light output are limited
Solution Approach 1:
The patent applies preliminary action by forming a patterned mask layer before the roughening process. This mask defines the precise regions that will be roughened, allowing control over the proportion and distribution of roughened areas. The mask is applied in advance to guide the subsequent roughening process, enabling precise control of light extraction characteristics without modifying the roughening process itself
Solution Approach 2:
The patent introduces a mask layer as an intermediary element between the design specification and the roughening process. This mask layer acts as a mediator that defines the spatial distribution of roughness, allowing precise control over which areas undergo roughening. The mask can be removed after serving its purpose, leaving the desired patterned roughness without requiring complex modifications to the roughening process parameters
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 approach enables precise control of light output from LEDs, ranging from minimal to maximum extraction efficiency, maintaining optimal process parameters and reducing costs by allowing for a wide range of precise control without affecting the conventional roughening processes.
Implementation Method 1
photo-lithographic techniques may be used to create a mask that limits the roughening to select areas of the light emitting surface
Implementation Method 2
roughening the light emitting surface... enhances the light extraction efficiency... allows for the extraction of twice as much light as the original unroughened surface
Data Source
Figure 1A~2
Figure 3~4D
AI summary
The surface of a light emitting device is roughened to enhance the light extraction efficiency of the surface, but the amount of roughened area is selected to achieve a desired level of light extraction efficiency. Photo-lithographic techniques may be used to create a mask that limits the roughening to select areas of the light emitting surface. Because the amount of roughened area can be precisely controlled, the light extraction efficiency can be precisely controlled, substantially independent of the particular process used to roughen the surface. Additionally, the selective roughening of the surface may be used to achieve a desired light emission output pattern.