Waveguide Light Emission for Uniform Micro-LED Directionality
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Micro-LED displays face challenges in achieving high directionality and uniformity of light emission, particularly for different colors, due to aberrations caused by focusing elements like microlenses, which result in reduced light and power efficiency.
Innovation Solution
A light emitting device with a combination of light emitters and light propagating units, comprising waveguides and funnel elements, that control light directionality by combining light of different characteristics and ensuring a narrow emission cone.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If microlenses are used as focusing elements above the emitter, then light directionality is improved, but anisotropic intensity distribution and non-uniform emission cone are caused for neighboring emitters of different color
Solution Approach 1:
The patent removes the microlens element from the optical system and replaces it with a planar waveguide structure. This extraction eliminates the aberrations and anisotropic intensity distribution caused by microlenses while maintaining light directionality control through the waveguide's planar geometry and total internal reflection mechanisms.
Solution Approach 2:
The patent replaces the mechanical/optical focusing system (microlenses) with a waveguide-based optical system that uses total internal reflection and evanescent wave coupling. This substitution maintains light directionality control without the aberrations inherent in lens-based systems.
2Illumination intensity
If spherical, parabolic, or freeform reflectors are implemented below the emitter, then light directionality is improved, but device complexity and manufacturing difficulty increase
Solution Approach 1:
The patent segments the light guiding function into a planar waveguide structure that can be manufactured using standard semiconductor fabrication techniques. This segmentation replaces complex three-dimensional reflector geometries with flat, planar structures that are easier to manufacture while maintaining optical functionality.
Solution Approach 2:
The patent changes the geometric parameters of the optical system from three-dimensional curved surfaces (spherical, parabolic, freeform reflectors) to two-dimensional planar structures. This parameter change simplifies manufacturing while maintaining light directionality control through the waveguide's optical path design.
3Device complexity
If conventional light emitting structures are used, then device simplicity is maintained, but emission cone angle is wide and light efficiency is reduced
Solution Approach 1:
The patent merges the light emission and light guiding functions into a single integrated structure where the waveguide both emits light and controls its direction. This merging eliminates the need for separate focusing elements while improving light efficiency through controlled directional emission.
Solution Approach 2:
The waveguide structure serves multiple functions simultaneously: it acts as both the light emitting structure and the light guiding/focusing element. This multi-functionality maintains relative structural simplicity while achieving narrow emission cone and high light efficiency.
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 device provides accurate control of light directionality and uniform emission cone for multiple colors, suitable for high-resolution displays in augmented, mixed, and virtual reality applications.
Implementation Method 1
a waveguide having an in-coupling end and a transmitting end, wherein the waveguide is configured to couple in light emitted by the group of light emitters at the in-coupling end
Implementation Method 2
a funnel element having a receiving end and an output end, wherein a cross-section of the funnel element at the receiving end is smaller than a cross-section of the funnel element at the output end
Data Source
AI summary
A light emitting device comprises: a plurality of light emitters; a plurality of light propagating units, each being associated with a group of light emitters and comprising: a waveguide for coupling in light from different light emitters at different locations of an in-coupling end, wherein the waveguide is a multimode waveguide for propagating light in dependence of the characteristics of the light for combining the light emitted by the light emitters at a transmitting end; a funnel element with a smaller cross-section at a receiving end than at an output end, wherein the receiving end is arranged to couple the light at the transmitting end into the funnel element for propagating the light to the output end for output of emitted light being a combination of light of the different characteristics.