Stacked Micro-LED Structure for Brightness Uniformity in Displays
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Solution Overview
Problem
Micro-LED displays face challenges in mounting and replacing defective micro-LEDs due to their small size, which affects brightness and visibility, and require complex current density regulation to maintain uniform brightness across different colors.
Innovation Solution
A stacked structure of LED stacks with color filters and conductive growth substrates that allow independent emission of light from each stack, increasing luminous area without enlarging pixel size, and enabling simultaneous manufacturing of multiple pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If micro-LEDs are arranged in a two-dimensional plane with small size, then the display can be manufactured with high integration, but it becomes difficult to mount and replace defective micro-LEDs
Solution Approach 1:
The patent transitions from a two-dimensional arrangement of micro-LEDs to a three-dimensional stacked structure where multiple LED stacks are vertically arranged. This vertical stacking allows micro-LEDs to be organized in layers (first, second, and third LED stacks), increasing integration density while maintaining accessibility for mounting and replacement operations through the vertical dimension.
2Productivity
If the area of each subpixel is reduced to arrange subpixels in a limited area, then more subpixels can be fitted, but the brightness of pixels deteriorates due to reduced luminous area
Solution Approach 1:
The patent employs vertical stacking of multiple LED stacks (first, second, and third LED stacks) to increase the luminous area in the vertical dimension. This allows the display to fit more pixels in a given planar area while maintaining or enhancing brightness through the cumulative light output of multiple stacked LED layers.
Solution Approach 2:
The patent combines multiple LED stacks vertically to form a unified light-emitting structure. The first, second, and third LED stacks are stacked and electrically connected, merging their light-emitting capabilities to provide enhanced brightness while occupying a compact planar footprint.
3Reliability
If the area of LED emitting light with low visibility color is increased, then brightness uniformity improves, but the area of subpixel increases
Solution Approach 1:
The patent uses vertical stacking to distribute the light-emitting function across multiple layers. Different LED stacks emitting different colors (red, green, blue) are arranged vertically, allowing each color to contribute to the overall brightness uniformity without requiring excessive planar area from any single subpixel.
4Reliability
If current density regulation is applied to reduce brightness difference between colors, then visibility uniformity improves, but operating complexity increases
Solution Approach 1:
The patent reduces operating complexity by transitioning from horizontal arrangement to vertical stacking, where multiple LED stacks are connected in series. This configuration allows uniform current flow through all stacks, automatically achieving brightness uniformity without requiring complex current density regulation circuits for each individual LED or subpixel.
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 enhances brightness uniformity and simplifies manufacturing by allowing independent emission and driving of LED stacks, reducing light interference and improving luminous efficacy.
Implementation Method 1
a first color filter interposed between the first LED stack and the second LED stack and transmitting light generated from the first LED stack while reflecting light generated from the second LED stack
Implementation Method 2
a second color filter interposed between the second LED stack and the third LED stack and transmitting light generated from the first and second LED stacks while reflecting light generated from the third LED stack
Implementation Method 3
a first LED stack disposed on the support substrate; a second LED stack disposed on the first LED stack; a third LED stack disposed on the second LED stack
Data Source
AI summary
A light emitting diode stack for a display including a first LED stack, a second LED stack disposed on the first LED stack, a third LED stack disposed on the second LED stack, and a conductive growth substrate coupled to at least one of the second LED stack and the third LED stack, in which light generated from the first LED stack is configured to be emitted to the outside of the light emitting diode stack through the second LED stack, the third LED stack, and the conductive growth substrate, and light generated from the second LED stack is configured to be emitted to the outside of the light emitting diode stack through the third LED stack and the conductive growth substrate.