Pixel Repair Circuit for Open Defects in Serial LED Display Electrodes
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Solution Overview
Problem
Display devices with serial connection structures of light emitting elements face challenges in repairing open defects, which can lead to reduced yield and efficiency due to the higher probability of open defects occurring, causing dark spots and disrupting current flow.
Innovation Solution
Incorporating a repair pattern circuit with repair transistors and conductive patterns between serial stages of light emitting elements, allowing for electrical connection and restoration of current flow even if open defects occur, thereby preventing dark spots and enhancing power efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by moving object
If light emitting elements are connected in series to enhance power efficiency, then power consumption is reduced, but the probability of open defects increases causing dark spots
Solution Approach 1:
The pixel circuit is divided into multiple independent repair pattern circuits, each corresponding to a specific serial stage. This segmentation allows targeted repair of defective stages without affecting other stages, maintaining the power efficiency benefits of serial connection while mitigating the risk of complete pixel failure from open defects.
Solution Approach 2:
Repair patterns are pre-configured in the circuit design before manufacturing defects occur. These repair patterns include alternative current paths and repair transistors that are initially inactive but can be activated to bypass open defects, preventing dark spots before they permanently degrade display quality.
2Reliability
If repair patterns are added to address open defects, then reliability is improved, but device complexity increases
Solution Approach 1:
The repair patterns are merged with the existing pixel circuit structure, sharing common elements such as electrodes, transistors, and interconnects. This integration approach adds repair functionality while minimizing the increase in overall device complexity by reusing existing circuit components rather than adding completely separate repair circuits.
Solution Approach 2:
The repair transistors and conductive patterns are designed to serve multiple functions: they can act as normal circuit elements during defect-free operation and simultaneously serve as repair pathways when open defects occur. This multi-functionality reduces the need for dedicated repair-only components, thereby limiting the increase in device complexity.
3Ease of repair
If multiple repair patterns are disposed between electrodes, then ease of repair is improved, but area of the display element increases
Solution Approach 1:
The repair patterns are arranged in the vertical dimension between existing electrodes rather than expanding horizontally across the display area. By utilizing the space between electrodes in the vertical direction, the design adds repair functionality without significantly increasing the lateral area of the display element, thus maintaining high ease of repair while minimizing area expansion.
Data Source
AI summary
A display device includes a pixel disposed in a display area. The pixel includes a first electrode and a second electrode spaced apart from each other; at least one intermediate electrode disposed between the first electrode and the second electrode; a plurality of light emitting elements electrically connected between a pair of adjacent electrodes of a plurality of electrodes including the first electrode, the second electrode, and the at least one intermediate electrode; and a plurality of repair patterns overlapping and disposed between a pair of adjacent electrodes of the plurality of electrodes.