Micro LED Optical Structure for Narrow Beam AR/VR Displays
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Solution Overview
Problem
Conventional micro LEDs are not suitable for augmented reality (AR) and virtual reality (VR) applications due to their light patterns, which need improvement for effective use in these technologies.
Innovation Solution
A micro LED structure with optical structures, including lenses and reflective cups, is designed over micro LED chips to modify light patterns by reducing beam angles and enhancing light intensity, featuring semiconductor stacks, metal pads, reflective coating layers, and planarization layers, optimized for directional light emission.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional micro LED structure is used, then manufacturing is simple, but light pattern is not suitable for AR/VR applications
Solution Approach 1:
The device is segmented into multiple functional layers including semiconductor stack, reflective coating layer, optical structures, and encapsulation layer. Each layer performs a specific function to collectively achieve the desired light pattern for AR/VR applications while maintaining manufacturing feasibility through modular assembly
Solution Approach 2:
The patent implements a nested structure where the reflective coating layer is disposed around sidewalls of the semiconductor stack, optical structures are positioned over the semiconductor stack within the encapsulation layer, creating concentric functional zones that optimize light emission patterns without excessive structural complexity
2Illumination intensity
If optical structures are added to modify light patterns, then light intensity and directionality are improved, but device complexity increases
Solution Approach 1:
Optical structures with curved surfaces are employed to focus and direct light emission from the semiconductor stack. The curved geometry naturally concentrates light rays into specific directions, enhancing illumination intensity and directional control without requiring complex mechanical adjustment mechanisms
Solution Approach 2:
The patent introduces an encapsulation layer as an intermediary between the semiconductor stack and the external environment. This layer houses the optical structures and provides a protective matrix that facilitates light extraction and directional control while simplifying the overall device architecture
3Loss of energy
If reflective coating layer is added around sidewalls, then light extraction efficiency is improved, but manufacturing complexity increases
Solution Approach 1:
The reflective coating layer changes the optical parameters of the semiconductor stack by providing high reflectivity surfaces around the sidewalls. This parameter change redirects light that would otherwise be lost, improving extraction efficiency through material property modification rather than complex structural additions
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 improved micro LED structure reduces beam angles, increases light intensity, and provides even light distribution, making it suitable for AR/VR devices by minimizing image crosstalk and enhancing color performance.
Implementation Method 1
a reflective coating layer disposed around sidewalls of the semiconductor stack
Implementation Method 2
optical structures respectively over the first micro LED chip, the second micro LED chip and the third micro LED chip
Implementation Method 3
Each of the first lens, the second lens and the third lens has a top portion and a bottom portion, and the top portion has a convex sidewall and the bottom portion has a concave sidewall
Data Source
AI summary
A micro LED structure includes a first micro LED chip having opposite first and second sides, a second micro LED chip adjacent to the first side of the second micro LED chip, a third micro LED chip adjacent to the first side of the first micro LED chip, and optical structures respectively over the first micro LED chip, the second micro LED chip and the third micro LED chip. Each of the first, second and third micro LED chip includes a semiconductor stack, a metal pad and a reflective coating layer. The semiconductor stack includes a first semiconductor layer, an active layer in contact with the first semiconductor layer, and a second semiconductor layer in contact with the active layer. The metal pad is in contact with the first semiconductor layer, and the reflective coating layer is disposed around sidewalls of the semiconductor stack.