Vertically Stacked Micro-LED Pixel for High-Brightness Resolution
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Solution Overview
Problem
Conventional LED display technologies face challenges in balancing resolution and brightness, particularly in micro-LED displays, where high brightness often results in low resolution and vice versa, and there are inefficiencies in fabrication processes that lead to reliability issues and increased power consumption.
Innovation Solution
A multi-color LED device with vertically stacked micro-LED structures, each with separate electrodes, and integrated reflective and micro-lens structures to enhance light illumination efficiency and reduce divergence, along with a reflective cup to suppress inter-pixel light crosstalk.
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 and resolution improvement is limited
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 structures emitting different colors are stacked along the vertical axis, allowing color diversity without occupying additional lateral pixel area. This vertical stacking enables full-color emission while maintaining 100% illumination area utilization within each pixel.
Solution Approach 2:
The patent merges multiple LED structures of different colors into a single integrated vertical stack within one pixel unit. Instead of separating color-emitting elements across non-overlapping zones, the invention combines red, green, and blue LED structures vertically, with their light paths merged and directed through a common micro-lens to achieve full-color emission from a single pixel location.
2Manufacturing precision
If pixel size is reduced to achieve high resolution, then more pixels can be fitted in the display, but brightness per pixel decreases
Solution Approach 1:
The patent changes the structural parameters of the pixel by implementing vertical stacking of multiple LED structures. This three-dimensional configuration increases the light-generating volume within each pixel without increasing its lateral footprint, thereby maintaining high pixel density while improving brightness per pixel through enhanced light emission capacity from multiple stacked LEDs.
Solution Approach 2:
The patent employs a nested structure where multiple LED structures are stacked vertically within the confines of a single pixel unit. Each LED structure is nested along the vertical axis, with smaller lateral dimensions but extended vertical presence. This nesting approach allows multiple light sources to occupy the same lateral pixel area, increasing brightness without compromising resolution.
3Ease of manufacture
If conventional fabrication processes are used for micro-LED displays, then manufacturing is simpler, but reliability issues and increased power consumption occur
Solution Approach 1:
The patent segments the fabrication process into distinct stages: first forming multiple color LED structures on a separate substrate, then transferring the completed multi-color LED stack as an integrated unit to the display substrate. This segmentation allows each LED structure to be optimized and tested independently before final integration, improving reliability while maintaining manufacturing efficiency through batch processing.
Solution Approach 2:
The patent performs preliminary actions by completing the formation and optimization of multiple color LED structures on a dedicated growth substrate before transfer. This preliminary fabrication allows for thorough testing and refinement of each LED structure's electrical and optical properties, ensuring high reliability is achieved before the structures are integrated into the final display assembly.
4Area of stationary object
If light emission is allowed in all directions, then illumination coverage is maximized, but light interference between adjacent pixels increases
Solution Approach 1:
The patent employs micro-lenses with curved spherical surfaces positioned above each vertically stacked LED structure. These curved lenses focus and direct the light emitted by the stacked LEDs in a controlled manner, concentrating illumination forward while minimizing lateral light spread. This curvature-based optical control reduces inter-pixel crosstalk while maintaining adequate illumination coverage.
Solution Approach 2:
The patent implements local quality control through individually positioned micro-lenses above each pixel's LED stack and reflective cups surrounding adjacent pixels. Each micro-lens is optimized for its specific pixel location, directing light precisely where needed while reflective cups provide localized light redirection to further confine illumination within each pixel's intended area, reducing harmful lateral spread.
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 improves brightness and resolution simultaneously while reducing power consumption and light interference between pixels, enhancing image quality and privacy protection.
Implementation Method 1
a first reflective structure formed on a bottom of the first light emitting layer
Implementation Method 2
integrated reflective and micro-lens structures to enhance light illumination efficiency and reduce divergence
Implementation Method 3
a reflective cup to suppress inter-pixel light crosstalk
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. Light from the micro multi-color LED device is emitted horizontally from each of the LED structures 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.