LED Light Extraction via Reflective Film and Guide Layer
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Solution Overview
Problem
The light extraction efficiency of light-emitting diodes (LEDs) is limited, particularly as light beams emitted from side surfaces are unable to propagate towards the front surface, leading to reduced display quality.
Innovation Solution
A display apparatus is designed with a substrate, electrodes, an insulating film with openings, a reflective film, and a light path guide layer. The reflective film surrounds the light-emitting diode and includes a closed-loop shape to reflect lateral light beams towards the front surface, while the light path guide layer with holes or grooves further directs light towards the front surface, enhancing light extraction efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a conventional LED structure is used, then the device is simple to manufacture, but light extraction efficiency is poor because side surface light cannot propagate to the front surface
Solution Approach 1:
The invention segments the light path management by introducing a reflective film layer and a light path guide layer with holes/grooves. The reflective film is segmented into regions (first reflective film in the opening, second reflective film on the insulating film), and the light path guide layer is segmented with multiple holes or grooves to create discrete light guiding paths. This segmentation allows different regions to handle light differently, improving overall extraction efficiency while maintaining manufacturing feasibility through layer-by-layer fabrication.
Solution Approach 2:
The invention adds vertical dimensionality to light path management by stacking multiple functional layers (insulating film, reflective film, light path guide layer) above the LED. The light path guide layer with holes/grooves creates three-dimensional light guiding channels that redirect side surface light upward through multiple layers. This dimensional approach transforms the two-dimensional light emission problem into a three-dimensional light management system, enabling side light to reach the front surface.
2Use of energy by moving object
If internal quantum efficiency is improved beyond its limit, then light emission increases, but light extraction efficiency becomes the bottleneck causing display quality deterioration
Solution Approach 1:
The invention introduces intermediary structures between the LED and the external environment: the reflective film acts as an intermediary to reflect and redirect light, and the light path guide layer with holes/grooves serves as an intermediary light guiding medium. These intermediaries facilitate the transition of light from the LED's side surfaces to the front surface, solving the extraction bottleneck without affecting the LED's internal quantum efficiency.
Solution Approach 2:
The invention changes optical parameters of the surrounding structures: the reflective film has high reflectivity to redirect light, and the light path guide layer materials are selected with specific refractive indices to optimize light guiding. By changing these optical parameters of the encapsulating structures, the system overcomes the extraction efficiency bottleneck while preserving internal quantum efficiency improvements.
3Loss of energy
If a reflective film and light path guide layer are added, then light extraction efficiency improves, but device complexity increases
Solution Approach 1:
The invention merges multiple functions into integrated layers: the insulating film serves both electrical insulation and as a substrate for the reflective film; the reflective film combines light reflection with structural support; the light path guide layer integrates light guiding functionality with the encapsulation structure. This merging reduces the need for separate components and simplifies the overall manufacturing process despite the added functionality.
Solution Approach 2:
The introduced layers serve multiple functions: the reflective film provides both light reflection and structural support; the light path guide layer with holes/grooves provides light guiding while also serving as part of the device's encapsulation and protection system. This multi-functionality reduces the need for additional specialized components, balancing the increase in functionality with acceptable complexity.
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 improves light extraction efficiency, reduces uneven luminance, and enhances the overall display quality by effectively guiding lateral light beams towards the front surface, thereby improving the display apparatus' performance.
Implementation Method 1
a reflective film disposed on the insulating film so as to cover at least a portion of an inner surface of the opening
Implementation Method 2
a light path guide layer disposed on the insulating film so as to cover at least a portion of the reflective film and including a plurality of holes or a plurality of grooves in a top surface thereof
Data Source
AI summary
A display apparatus includes: a substrate; a first electrode; an insulating film including an opening that extends to at least the central portion of the first electrode; a light-emitting diode disposed on the first electrode and including a first pad electrically connected to the first electrode; a reflective film disposed on the insulating film so as to cover at least a portion of an inner surface of the opening; and a light path guide layer disposed on the insulating film so as to cover at least a portion of the reflective film and including a plurality of holes or a plurality of grooves on the top surface. In one embodiment, the display apparatus improves the light extraction efficiency of the light-emitting diode.