Remote Scattering Element and TIR Extractor for LED Light Extraction
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Solution Overview
Problem
Conventional white LEDs face challenges such as light-energy losses, phosphor self-heating, and degradation due to overheating, humidity, and chemical changes, which affect the efficiency and durability of phosphor-based light-emitting devices.
Innovation Solution
A light-emitting device with a remote scattering element and a total internal reflection (TIR) extractor element, where the scattering element is coupled with an extractor element to optimize light directionality and minimize reflection losses, using elastic and inelastic scattering centers to achieve directional and spectral mixing of light, and an asymmetric optical interface to enhance forward light transmission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If conventional micro-LED displays are used, then color gamut and resolution can be achieved, but pixel degradation and burn-in occur due to uneven current distribution
Solution Approach 1:
The patent introduces a current equalization structure comprising conductive layers and dielectric layers positioned between the pixel electrode and sub-LEDs. This intermediary structure redistributes current uniformly across multiple sub-LEDs, preventing any single LED from receiving excessive current that would cause degradation or burn-in, while maintaining the desired color gamut and resolution performance
Solution Approach 2:
The patent divides each pixel into multiple sub-LEDs (e.g., red, green, blue sub-LEDs) and implements separate current equalization paths for each sub-LED through the conductive and dielectric layer structure. This segmentation allows independent current control and equalization for each sub-LED, preventing uneven current distribution that leads to pixel degradation while maintaining overall pixel performance
2Length of stationary object
If the light-emitting layer is positioned close to the pixel electrode for compact design, then device thickness is reduced, but non-uniform light emission occurs due to parasitic capacitance
Solution Approach 1:
The patent introduces a dielectric layer as an intermediary between the conductive layer and the light-emitting layer. This dielectric layer acts as a parasitic capacitance compensation structure that counteracts the non-uniform electric field effects caused by close positioning, enabling uniform light emission while maintaining compact device thickness
Solution Approach 2:
The patent modifies the electrical parameters of the structure by introducing dielectric materials with specific permittivity values and configuring conductive layer geometries to adjust electric field distribution. These parameter changes compensate for the parasitic capacitance effects that arise from close positioning of the light-emitting layer, ensuring uniform light emission in the compact design
3Ease of manufacture
If transparent conductive oxides are used to achieve thin-film transistor compatibility, then manufacturing complexity is reduced, but sheet resistance increases limiting performance
Solution Approach 1:
The patent employs composite conductor structures combining transparent conductive oxides (such as ITO, IZO, or GZO) with metal layers or multi-layer configurations. This composite approach maintains the manufacturing compatibility with thin-film transistor processes while achieving lower sheet resistance through the synergistic combination of materials, overcoming the limitation of high sheet resistance in single-layer transparent conductors
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 improves light extraction efficiency by directing and shaping light effectively, reducing optical losses, and enhancing the durability and longevity of the light-emitting devices by minimizing backward light transmission and maximizing forward light propagation.
Implementation Method 1
The device includes a remote phosphor layer comprising yellow phosphor and a portion of the blue LED light is blocked from reaching the yellow phosphor
Implementation Method 2
The device includes a total internal reflection extractor element
Data Source
Figure 1A
Figure 1B
Figure 1C
AI summary
Light-emitting device (400) comprising a light-emitting element (110), a scattering element (420) having a first surface facing the light-emitting element, the scattering element being spaced apart from the light-emitting element and positioned to receive some light from it, and an extractor (430) forming an optical interface including a region of contact between the scattering element and the extractor, through which the extractor receives light output by the scattering element and having a side surface (438) spaced apart from the optical interface and being arranged to receive a portion of the scattered light through the optical interface, the extractor being configured to emit light through an exit surface (435) arranged distal the optical interface with the scattering element, wherein the side surface is positioned and shaped such that an angle of incidence on the side surface of scattered light received through the region of adjacency that directly impinges on the side surface is equal to, or larger than, a critical angle for total internal reflection; a reflective surface (432) extends from the optical interface to the side surface.