Stacked Micro-LED Electrode Layout for Larger Luminous Area
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Solution Overview
Problem
Micro-LED displays face a reduction in light emitting area due to elements for electrical connection, leading to loss of luminance and restricted effective luminous area.
Innovation Solution
A light emitting device comprising multiple LED stacks with a common electrode and connection electrodes, where the common electrode includes a step in at least one of the LED stacks, and the LED stacks are configured to emit light of different wavelengths, such as blue, green, and red.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If micro-LEDs are used with small size (200 μm or less, specifically 100 μm or less), then the display can achieve high resolution and compact structure, but the effective luminous area is significantly reduced
Solution Approach 1:
The patent transitions from a planar arrangement to a three-dimensional stacked configuration, where multiple micro-LEDs are vertically arranged along the light emission direction. This dimensional change allows multiple light-emitting elements to occupy the same footprint area, effectively increasing the total luminous area without increasing the device's planar dimensions.
2Reliability
If electrodes are formed for electrical connection to micro-LEDs, then electrical connectivity is achieved, but the luminous area is further reduced
Solution Approach 1:
The patent divides the electrode structure into multiple segments arranged at different heights along the light emission direction. Connection electrodes are positioned at various vertical levels to contact different micro-LEDs in the stack, allowing electrical connection while minimizing the horizontal footprint and preserving luminous area.
Solution Approach 2:
The electrode arrangement extends into the vertical dimension, with connection electrodes positioned at different heights rather than all in a single plane. This three-dimensional electrode configuration reduces the horizontal space occupied by electrodes, thereby preserving more luminous area while maintaining reliable electrical connections.
3Adaptability or versatility
If multiple micro-LEDs are mounted on one substrate, then the display can achieve full-color capability and image display, but the light emitting area per pixel is reduced
Solution Approach 1:
The patent arranges micro-LEDs emitting different colors (red, green, blue) in a vertical stack configuration rather than horizontally adjacent in a plane. This vertical stacking enables full-color display capability within a compact footprint, as all color-emitting LEDs occupy the same horizontal space but are positioned at different heights along the light emission direction.
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 mitigates the reduction in light emitting area, increases light extraction efficiency, and improves luminance by optimizing the electrode structure and arrangement of LED stacks.
Implementation Method 1
a first LED stack, a second LED stack disposed on the first LED stack, a third LED stack disposed on the second LED stack... configured to emit light of different wavelengths from one another
Data Source
AI summary
A light emitting device 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 common electrode electrically connected to a first conductivity type semiconductor layer of each of the first, second, and third LED stacks, in which the common electrode includes a step in at least one of the first, second and third LED stacks.