Stacked Multi-Color LED Pixel Unit for High-Brightness Micro-Displays
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Solution Overview
Problem
Conventional LED display technologies face challenges in achieving high brightness and resolution while maintaining low power consumption, with issues such as inefficient light utilization, light crosstalk, and complex fabrication processes, particularly in micro-LED displays used in AR, VR, and portable devices.
Innovation Solution
The integration of vertically stacked micro-LED structures with separate electrodes and reflective elements, along with a micro-lens array and stair-shaped reflective cups, enhances light illumination efficiency, reduces viewing angles, and improves fabrication reliability, allowing for compact, high-brightness, and high-resolution displays.
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 included within a pixel, but the effective illumination area within each pixel is reduced
Solution Approach 1:
The patent transitions from planar arrangement of multiple monochromatic LEDs to a vertical stacked configuration. Multiple LED structures emitting different colors are arranged in vertical layers, allowing color diversity without sacrificing horizontal illumination area. This dimensional change enables full-color display while maintaining large effective illumination area per pixel.
Solution Approach 2:
The patent implements nested LED structures where multiple LED layers are vertically stacked and integrated within a single pixel footprint. Each LED layer is nested above the previous one, with reflective structures and dielectric layers interposed between them. This nesting enables multiple colors to be generated within a compact vertical space, maximizing the effective illumination area.
2Manufacturing precision
If pixel size is reduced to achieve high resolution, then resolution improves, but brightness decreases
Solution Approach 1:
The patent compensates for reduced pixel area by extending the LED structure into the vertical dimension. Multiple stacked LED layers increase the total light-generating volume within each pixel, maintaining brightness even as horizontal pixel dimensions are reduced for high resolution displays.
Solution Approach 2:
The patent introduces reflective structures (such as reflective cups or mirrors) as intermediaries between the LED layers and the external environment. These reflective elements redirect light that would otherwise be trapped or emitted in unwanted directions, concentrating and enhancing the effective brightness from each pixel while maintaining small pixel size.
3Ease of operation
If conventional LCD or OLED displays are used, then display functionality is achieved, but power consumption is high
Solution Approach 1:
The patent employs self-emissive LED structures that generate their own light without requiring separate backlight units or complex liquid crystal switching mechanisms. Each pixel contains LED structures that directly emit light when electrically activated, eliminating the need for additional light sources and control layers, thereby reducing overall power consumption while maintaining full display functionality.
4Loss of energy
If vertically stacked micro-LED structures are integrated, then light emission efficiency improves, but fabrication complexity increases
Solution Approach 1:
The patent divides the complex multi-color LED structure into modular segments, with each LED layer and its associated reflective and dielectric structures forming independent units. This segmentation allows each module to be fabricated and characterized separately, then integrated into the final stacked configuration, reducing overall fabrication complexity while maintaining high light emission 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
This approach significantly improves light emission efficiency, reduces power consumption, and enhances image quality and privacy in portable devices, while simplifying the fabrication process, making it suitable for demanding applications like AR, VR, and automotive displays.
Implementation Method 1
a first reflective structure formed on a bottom of the first light emitting 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 vertically, and/or horizontally and reflected upward via some reflective structures. In some embodiments, each LED structure is connected to a pixel driver and/or a common electrode. The LED structures are bonded together through bonding layers. In some embodiments, planarization layers enclose each of the LED structures or the micro multi-color LED device. In some embodiments, one or more of reflective layers, refractive layers, micro-lenses, spacers, and reflective cup structures 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.