Stacked Micro LED Subpixels for Compact Displays and Heat Control
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Solution Overview
Problem
Conventional LEDs require a large area for subpixels, leading to excessive time consumption in mounting processes and potential brightness and luminous efficiency deterioration due to heat generation, especially when used in display apparatuses.
Innovation Solution
A micro LED structure with a stacked configuration of LED sub-units, including a common electrode pad and independent driving capabilities, enhances current distribution and heat dissipation while reducing subpixel area without compromising brightness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional LEDs are arranged on a two-dimensional plane with one LED chip per subpixel, then each subpixel can be formed with sufficient luminous area, but the number of LED chips required exceeds millions causing excessive mounting time consumption
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of LED chips to a three-dimensional stacked structure where multiple LED chips are vertically stacked. This dimensional change allows multiple subpixels (blue, green, red) to be formed within a single pixel area by stacking LED chips at different heights, dramatically reducing the total number of LED chips required and thus reducing mounting time while maintaining sufficient luminous area for each subpixel.
2Area of stationary object
If the area of each subpixel is reduced to fit more subpixels in a limited area, then the display area can be increased, but brightness deteriorates due to reduced luminous area
Solution Approach 1:
By stacking LED chips vertically in the third dimension, the patent enables multiple subpixels to occupy the same horizontal footprint area. This allows the display area to be increased without reducing the luminous area of individual subpixels, as each subpixel maintains its full luminous area in its respective vertical layer while sharing the same horizontal space with other color subpixels.
Solution Approach 2:
The patent implements a nested structure where multiple LED chips are stacked vertically within a single pixel area, similar to nested dolls. Each LED chip (representing a subpixel) is contained within the vertical space of the pixel, allowing multiple subpixels to be packed into a compact area while each maintaining its full luminous area for optimal brightness.
3Productivity
If the area of each subpixel is reduced, then more subpixels can be accommodated, but luminous efficiency deteriorates due to heat generation in LED chips
Solution Approach 1:
The vertical stacking arrangement distributes LED chips across multiple height levels, improving heat dissipation by increasing the distance between heat-generating elements and the substrate. This three-dimensional configuration allows heat to dissipate more effectively through the vertical dimension, maintaining luminous efficiency even as subpixel density increases.
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 micro LED structure allows for reduced subpixel area without increasing pixel size, improving manufacturing efficiency and maintaining brightness by optimizing current distribution and heat management.
Implementation Method 1
a first LED stack, a second LED stack, and a third LED stack which respectively emit red light, green light, and blue light
Data Source
AI summary
A light emitting device for a display including a first LED sub-unit, a second LED sub-unit disposed on the first LED sub-unit, a third LED sub-unit disposed on the second LED sub-unit, electrode pads disposed below the first LED sub-unit, and a planarization layer disposed between the first and second LED sub-units and being light transmissive, in which the electrode pads include a common electrode pad electrically connected in common to the first, second, and third LED sub-units, first, second, and third electrode pads connected to the first, second, and third LED sub-units, respectively, the first, second, and third LED sub-units are independently drivable, light generated in the first LED sub-unit is configured to be emitted to the outside through the second and third LED sub-units, and light generated in the second LED sub-unit is configured to be emitted to the outside through the third LED sub-unit.