Stacked Micro-LED Subpixel Structure for Compact Full-Color Displays
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Solution Overview
Problem
The existing technologies for micro LED displays face challenges in increasing the light emitting area of each subpixel without increasing the pixel area, simplifying the mounting process, and facilitating probe testing due to the small size and complex structure of micro LEDs.
Innovation Solution
A light emitting device with a stacked structure comprising multiple LED sub-units, electrode pads, and lead electrodes, which allows for independent driving of each sub-unit, increasing the light emitting area without enlarging the pixel size, simplifying the mounting process, and enabling easy probe testing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If individual LED chips are arranged on a two-dimensional plane for each subpixel, then color display capability is achieved, but the number of LED chips required becomes very large and the mounting process becomes complex
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of individual LED chips to a three-dimensional stacked structure where multiple LED chips are vertically arranged. This dimensional change allows multiple subpixels (red, green, blue) to be integrated in the vertical direction rather than requiring extensive horizontal spreading, thereby reducing the total number of chips and simplifying the mounting process while maintaining full color display capability
Solution Approach 2:
The patent combines multiple LED chips (first, second, and third LED chips emitting different colors) into a single integrated light emitting device with a stacked structure. By merging these chips vertically and sharing common electrode structures, the invention reduces the overall component count and simplifies the mounting process compared to arranging individual chips separately on a two-dimensional plane
2Adaptability or versatility
If subpixels are arranged on a two-dimensional plane, then color display is achieved, but a relatively large area is required for one pixel
Solution Approach 1:
The patent utilizes the vertical dimension to stack multiple LED chips (first, second, and third chips for different colors) above a single pixel location. This allows the pixel to maintain a compact two-dimensional footprint while achieving full color display through vertical integration, thereby significantly reducing the area required per pixel compared to horizontal arrangement
3Area of stationary object
If the luminous area of each subpixel is reduced, then pixel area is decreased, but the brightness of subpixels deteriorates
Solution Approach 1:
By stacking LED chips vertically, the invention increases the effective light-emitting volume without expanding the horizontal pixel area. The vertical stacking allows each subpixel to maintain adequate luminous area for brightness while the overall pixel footprint remains compact, resolving the trade-off between pixel size and subpixel brightness
4Productivity
If micro-LED size is reduced to very small dimensions, then integration density is increased, but probing during measurement becomes difficult
Solution Approach 1:
The patent divides the light emitting device into distinct stacked segments (first, second, and third LED chips) with separate electrode connections. This segmentation allows probe access points to be distributed across different vertical levels and locations, making it easier to perform electrical and optical measurements on each chip individually despite the compact overall size and high integration density
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 effectively increases the light emitting area of each subpixel, reduces the complexity and time required for the mounting process, and allows for easy electrical and optical characteristic measurements, thereby improving manufacturing productivity.
Implementation Method 1
a first light emitting diode sub-unit, a second light emitting diode sub-unit disposed on the first light emitting diode sub-unit, and a third light emitting diode sub-unit disposed on the second light emitting diode sub-unit
Data Source
AI summary
A light emitting device for a display including a first LED sub-unit laterally extending along a first direction, a second LED sub-unit, and a third LED sub-unit, electrode pads each overlapping at least a portion of the first LED sub-unit along a vertical direction and electrically connected to at least one of the first, second, and third LED sub-units, a lower insulation layer having a first surface extending in the first direction, a molding member covering each of the first LED sub-unit, the second LED sub-unit, and the third LED sub-unit, and lead electrodes electrically connected to the electrode pads and extending along the first surface and a side surface of the lower insulation layer, in which a portion of an outer region of each of the lead electrodes is disposed inside the outer boundary of the molding member when viewed in a cross-section.