LED Electrode Layout for Direction-Independent Display Assembly
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Solution Overview
Problem
The challenge in display technology is aligning super small-sized light emitting diodes (LEDs) on a substrate, leading to defects where some LEDs are not correctly assembled between electrodes, resulting in about 50% of them not emitting light and increasing costs due to waste and reduced luminance.
Innovation Solution
A light emitting device configuration with a first conductivity type semiconductor layer, an active layer, a second conductivity type semiconductor layer, and electrode layers, where at least one of the semiconductor layers or electrode layers is positioned in the central region, allowing for correct assembly direction independence and uniform luminance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Extent of automation
If a self-assembly method using an inkjet head device is used to transfer light emitting devices onto a substrate, then the transfer process becomes automated and scalable, but about 50% of the light emitting devices are randomly assembled in the wrong direction and do not emit light
Solution Approach 1:
The patent introduces asymmetric electrode structures (first electrode and second electrode with different configurations) and asymmetric light emitting device structures (with distinct first and second ends having different conductivity types) to enable directional assembly. The asymmetric design creates an inherent orientation preference during the self-assembly process, allowing the inkjet head device to automatically orient light emitting devices in the correct direction based on electrostatic attraction patterns, thereby eliminating random wrong-direction assembly while maintaining automation.
2Productivity
If light emitting devices are randomly assembled between electrodes, then the manufacturing process is simple and fast, but about 50% of devices are defective and do not contribute to luminance
Solution Approach 1:
The patent employs asymmetric electrode and light emitting device structures where the first electrode has a different configuration than the second electrode, and correspondingly the first end of the light emitting device has a different conductivity type than the second end. This asymmetry creates an inherent directional preference during assembly, ensuring that when light emitting devices are transferred by the inkjet head device, they automatically orient in the correct direction with the higher probability, thereby eliminating the 50% defect rate while maintaining high manufacturing speed.
3Manufacturing precision
If the size of light emitting devices is reduced to micro or nano scale to achieve high resolution, then more light emitting devices can be arranged in each pixel, but the alignment and transfer of these super small-sized devices becomes extremely difficult
Solution Approach 1:
The patent replaces traditional mechanical alignment and transfer methods with an electrostatic field-based self-assembly approach. The inkjet head device utilizes electrostatic attraction between charged electrodes and oppositely charged light emitting devices to achieve automatic alignment and positioning. This substitution of mechanical systems with electromagnetic fields enables precise transfer and alignment of super small-sized micro or nano scale light emitting devices, overcoming the extreme difficulty associated with handling and positioning such tiny components while achieving high pixel resolution.
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
This configuration ensures all LEDs emit light, reducing waste and costs, and significantly improving luminance by preventing defective LEDs, thus enabling high-brightness and uniform displays.
Implementation Method 1
the light emitting devices 2 and 3 dropped from the inkjet head device by the dielectrophoretic force formed between the first electrode 1a and the second electrode 1b are assembled between the first electrode 1a and the second electrode 1b
Data Source
AI summary
The light emitting device can include a first conductivity type semiconductor layer, an active layer on the first conductivity type semiconductor layer, a second conductivity type semiconductor layer on the active layer, at least one or more electrode layers on the second conductivity type semiconductor layer, and an insulating layer on the electrode layer. At least one of the second conductivity type semiconductor layer and the electrode layer can be positioned in the central region of the light emitting device.Therefore, even if a plurality of light emitting devices are disposed on a substrate of a display device having different assembly directions, all light emitting devices assembled on the substrate can emit light without defects.