Micro LED Reflective Apertures for Beam Collimation
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Solution Overview
Problem
Micro LED arrays face significant light loss due to angular distribution, with only 2.7% of emitted light within the acceptance angle of a typical F/3 lens, leading to inefficiencies and the need for precise mechanical alignment with extra optical elements for collimation.
Innovation Solution
A method involving a dielectric layer with internally reflective apertures over micro LEDs, aligned with each LED to collimate light, reducing the need for additional optical elements and enhancing optical isolation, thereby improving coupling efficiency to projection lenses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If standard micro LEDs with Lambertian emission are used, then manufacturing is simple, but light loss is significant (97.3% outside acceptance angle)
Solution Approach 1:
The patent merges the collimation function directly into the LED structure by integrating a reflective aperture into the LED package. This combines the light source and collimation element into a single unit, eliminating the need for separate external collimation optics and reducing overall device complexity while minimizing light loss.
Solution Approach 2:
The reflective aperture acts as an intermediary element between the LED chip and the external environment. It mediates the light emission by reflecting and collimating photons within the acceptance angle, thereby reducing light loss without requiring complex external optical systems.
2Illumination intensity
If extra optical elements are added for collimation, then beam direction is improved, but manufacturing precision requirements increase (alignment within 0.25 microns)
Solution Approach 1:
By merging the collimation function into the LED package structure itself, the patent eliminates the need for precise alignment between separate LED and optical elements. The reflective aperture is integrated during the LED packaging process, achieving beam directionality without requiring sub-micron alignment precision.
Solution Approach 2:
The LED package structure provides its own collimation function through the integrated reflective aperture. The structure serves itself by incorporating the necessary optical functionality directly into the packaging, eliminating the need for external alignment and precision positioning mechanisms.
3Loss of energy
If micro lens array is used for collimation, then light coupling efficiency is improved, but device complexity and cost increase
Solution Approach 1:
The patent merges the collimation function into the LED package by using a reflective aperture integrated during packaging. This single integrated structure replaces the need for separate micro lens arrays, reducing optical component count and device complexity while maintaining improved light coupling efficiency.
Solution Approach 2:
The reflective aperture can be implemented using cost-effective materials and processes during LED packaging, such as metallized surfaces or simple dielectric coatings. This provides an economical alternative to expensive precision micro lens arrays while achieving the necessary optical performance.
4Illumination intensity
If mechanical alignment with optical elements is required, then collimation is achieved, but ease of manufacture deteriorates
Solution Approach 1:
By merging the collimation function into the LED package structure, the patent eliminates the need for separate mechanical alignment steps. The reflective aperture is positioned and configured during the LED packaging process itself, simplifying manufacturing and assembly while maintaining high collimation quality.
Solution Approach 2:
The LED package structure provides self-alignment through the integrated reflective aperture. The optical functionality is built-in during packaging, eliminating the need for external mechanical alignment procedures and simplifying the overall manufacturing process.
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 achieves a narrow beam emission distribution with reduced light loss, increased optical efficiency, and simplified manufacturing, while maintaining high fidelity and preventing cross-talk between LEDs, even at low temperatures.
Implementation Method 1
each aperture having an internal surface that is at least partially reflective, wherein at least one aperture of the plurality of apertures is centred on and aligned with a light emitting diode of the plurality of light emitting diodes of the first layer, such that light emitted from light emitting diode is collimated as it passes through the at least one aperture
Data Source
AI summary
A method of manufacturing a light emitting diode array comprising a first layer having a plurality of light emitting diodes arranged to emit light from a light emitting surface of the first layer, the method comprising: depositing a layer of dielectric material over the light emitting surface of the first layer; forming a plurality of apertures extending through the layer of dielectric material, each aperture having an internal surface that is at least partially reflective, wherein at least one aperture of the plurality of apertures is centered on and aligned with a light emitting diode of the plurality of light emitting diodes of the first layer, such that light emitted from light emitting diode is collimated as it passes through the at least one aperture.