Coaxial Multi-Color Micro-LED Structure for Bright Dense Displays
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Solution Overview
Problem
Conventional LED display technologies face challenges in achieving high brightness and resolution simultaneously due to the opposing relationships between pixel size and brightness, and they require inefficient and costly fabrication processes for multi-color displays, leading to issues like light cross-talk and thermal mismatch.
Innovation Solution
A multi-color LED device structure with vertically stacked micro-LEDs using a common electrode for current control, allowing for improved light illumination efficiency and reduced pixel footprint, along with direct bonding of LED structures to the substrate without intermediate substrates, enhancing fabrication efficiency and reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If separate monochromatic LEDs are fabricated at different non-overlapping zones within the pixel area, then multiple colors can be achieved, but the effective illumination area within each pixel is reduced and resolution cannot be improved
Solution Approach 1:
The patent transitions from a two-dimensional planar arrangement of separate monochromatic LEDs to a three-dimensional vertically stacked configuration. Multiple LED layers are stacked along the vertical axis, allowing each layer to contribute to color output without occupying lateral space. This vertical stacking enables full-color display while maintaining 100% effective illumination area within the pixel footprint, as all LED layers emit light through the same optical path.
Solution Approach 2:
The patent implements a nested structure where multiple LED layers are stacked concentrically along the vertical axis, with each LED layer nested within the optical path of the others. The LED layers are arranged such that their light emission regions are vertically aligned, creating a compact nested configuration that maximizes space utilization and maintains full illumination area.
2Manufacturing precision
If the distance between adjacent pixels is reduced to improve resolution, then higher resolution is achieved, but brightness per pixel decreases
Solution Approach 1:
The patent compensates for reduced pixel area by adding vertical stacking dimension. Instead of relying solely on lateral pixel density, the invention increases light output by stacking multiple LED layers vertically within each pixel. This allows smaller pixel pitch while maintaining or enhancing brightness, as multiple LED layers contribute additive light output from the same vertical optical path.
Solution Approach 2:
The patent merges multiple LED layers into a single integrated vertical stack within each pixel. The light emission from all LED layers is combined and transmitted through a common optical path, effectively consolidating the light output of multiple individual LEDs into a unified beam that maintains high intensity despite reduced pixel footprint.
3Ease of manufacture
If intermediate substrates are used for transferring micro LEDs, then fabrication is enabled, but the process becomes inefficient, costly and unreliable
Solution Approach 1:
The patent eliminates the intermediate substrate step from the fabrication process. Micro LEDs are grown directly on a substrate and then transferred directly to the final display substrate without requiring an intermediate transfer substrate. This extraction of the intermediate substrate step simplifies the fabrication process, reduces costs, and improves reliability by removing an additional processing interface.
Solution Approach 2:
The patent segments the fabrication process into distinct stages: LED growth on a first substrate, release of LEDs from the first substrate, and direct transfer to the final display substrate. This segmentation allows for optimized processing at each stage while eliminating unnecessary intermediate steps, improving overall fabrication efficiency and yield.
4Adaptability or versatility
If multiple substrates are used for different color LEDs, then color diversity is achieved, but thermal mismatch and stress at bonding interfaces occur
Solution Approach 1:
The patent merges multiple LED layers onto a single common substrate rather than using separate substrates for different colors. All LED layers are grown and bonded to the same substrate, eliminating thermal mismatch and stress issues that arise from bonding multiple different substrates together. This unified substrate approach maintains color diversity while ensuring bonding interface stability.
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 achieves improved brightness and resolution while reducing power consumption and fabrication complexities, making it suitable for high-definition AR and VR applications.
Implementation Method 1
Each of the LED structures emits light of a different wavelength
Implementation Method 2
The first LED structure layer is bonded to the second LED structure layer
Data Source
AI summary
A micro multi-color LED device includes two or more LED structures for emitting a range of colors. The two or more LED structures are vertically stacked to combine light from the two more LED structures. In some embodiments, each LED structure is connected to a pixel driver and a shared P-electrode. The LED structures are bonded together through bonding layers. In some embodiments, reflection layers are implemented in the device to improve the LED emission efficiency. A display panel comprising an array of the micro tri-color LED devices has a high resolution and a high illumination brightness.