Stacked LED Sub-units for Display Brightness and Crosstalk Reduction
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Solution Overview
Problem
Micro LEDs in displays face challenges due to their small size, making handling and mounting difficult, leading to increased pixel area occupation, reduced brightness, and light interference between sub-pixels, with conventional solutions like color filters causing secondary light generation.
Innovation Solution
A display apparatus with a stacked structure of LED sub-units, each emitting different colors, connected via connectors and electrodes, allowing independent driving and light emission through multiple layers without color filters, enhancing light emission area and reducing interference.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If micro LEDs are arranged on a two-dimensional plane, then the display can implement various colors through sub-pixels, but the area occupied by one pixel is relatively increased
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of sub-pixels to a three-dimensional stacked structure where multiple LED layers are vertically arranged. This dimensional change allows multiple light-emitting elements to occupy the same planar footprint, thereby increasing the light emission area without enlarging the pixel area on the display surface.
Solution Approach 2:
The patent implements a nested structure where multiple LED layers are stacked vertically, with each layer containing LED elements that emit different colors. The layers are arranged such that they occupy overlapping planar spaces, effectively nesting multiple light-emitting units within a compact vertical volume, thereby maximizing light emission area within limited pixel boundaries.
2Productivity
If the area of each sub-pixel is reduced to arrange sub-pixels within a limited area, then more sub-pixels can be arranged, but brightness deteriorates
Solution Approach 1:
By stacking multiple LED layers vertically, the patent increases the total light emission area within the same planar footprint. This allows more LED elements to be incorporated without reducing individual sub-pixel area, thereby maintaining brightness while increasing the number of controllable sub-pixels per pixel unit.
Solution Approach 2:
The patent combines multiple LED layers emitting different colors (red, green, blue) into a single stacked structure. This merging of multiple light-emitting units allows the system to achieve full-color display capabilities with increased total luminous area, thereby improving brightness while maintaining compact pixel dimensions.
3Manufacturing precision
If a large number of micro LEDs are disposed on one substrate, then the display can achieve high resolution, but handling and mounting becomes difficult
Solution Approach 1:
The patent stacks multiple LED layers vertically, with each layer containing multiple LED elements. This nested arrangement allows a large number of LED elements to be integrated within a compact volume, achieving high display resolution while maintaining manageable device dimensions that facilitate handling and mounting operations.
Solution Approach 2:
By transitioning from a two-dimensional spread-out arrangement to a three-dimensional stacked configuration, the patent consolidates a large number of LED elements into a compact vertical structure. This reduces the overall device footprint and simplifies handling while maintaining high element density for high-resolution display.
4Illumination intensity
If sub-pixels are arranged on a two-dimensional plane, then color display is achieved, but light interference occurs between adjacent sub-pixels
Solution Approach 1:
The patent arranges LED layers emitting different colors in the vertical dimension rather than horizontally adjacent in the same plane. This vertical stacking separates the light emission paths of different colors in the lateral direction, reducing optical crosstalk and interference between adjacent sub-pixels while maintaining full-color display capability.
Solution Approach 2:
The stacked LED layers are vertically nested with each layer emitting different colors. This vertical nesting creates spatial separation between light sources of different colors, preventing lateral light interference that occurs in planar arrangements, while still achieving color display through the combination of multiple layers.
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 increases light emission area per sub-pixel without enlarging the pixel size, improves reliability through stable LED structures, simplifies manufacturing, and prevents light interference by stacking LED stacks, enabling active matrix driving and faster mounting processes.
Implementation Method 1
a first LED stack, a second LED stack, and a third LED stack which are stacked in this order from the front surface of the display apparatus viewed from the front, respectively emit red, green, and blue light
Implementation Method 2
arranging first, second, and third LED stacks one over another to emit light with decreasing wavelengths of light
Data Source
Figure 1~2
Figure 3A~4A
Figure 4B~6A
AI summary
A light emitting device including first, second, and third LED sub-units, and electrode pads disposed on the first LED sub-unit, electrically connected to the LED sub-units, and including a common electrode pad electrically connected to each of the LED sub-units, and first, second, and third electrode pads connected to a respective one of the LED sub-units, in which the common electrode pad, the second electrode pad, and the third electrode pad are electrically connected to the second LED sub-unit and the third LED sub-unit through holes that pass through the first LED sub-unit, the first, second, and third LED sub-units are configured to be independently driven, light generated in the first LED sub-unit emitted to the outside through the second and third LED sub-units, and light generated in the second LED sub-unit is emitted to the outside through the third LED sub-unit.