OLED Pixel Circuit Contact Hole Area Variation
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Solution Overview
Problem
OLED displays face challenges in maintaining uniform current supply to organic light-emitting elements due to variations in the width of active layers of thin film transistors across the substrate, leading to potential differences in luminance and display quality.
Innovation Solution
The OLED display design incorporates a substrate with distinct pixel circuits in different regions, featuring varying contact hole sizes and additional contact holes to ensure consistent current supply, with the second pixel circuit having a larger contact hole area and additional holes to connect thin film transistors, thereby compensating for manufacturing errors and minimizing transistor characteristic differences.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If uniform contact hole sizes are used across all pixel circuits, then manufacturing process is simplified, but current supply uniformity deteriorates due to active layer width variations
Solution Approach 1:
The patent applies local quality by varying contact hole sizes according to their specific location on the substrate. Pixel circuits in different regions (first region vs. second region) have different contact hole areas - specifically, contact holes in the second region have larger areas than those in the first region. This localized differentiation compensates for active layer width variations in different substrate regions, ensuring uniform current supply while maintaining manufacturing feasibility through a systematic size variation approach.
2Manufacturing precision
If contact hole size is increased to compensate for active layer width variations, then current supply uniformity is improved, but device complexity increases
Solution Approach 1:
The patent implements parameter changes by systematically varying the contact hole area parameter based on location. Instead of using a fixed contact hole size, the invention adjusts the contact hole area parameter for pixel circuits in different regions - specifically increasing the contact hole area in the second region compared to the first region. This parameter variation compensates for active layer width differences and achieves uniform current supply across the substrate.
3Reliability
If additional contact holes are added to pixel circuits, then current supply consistency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent applies segmentation by dividing the substrate into distinct regions (first region and second region) with different contact hole configurations. Pixel circuits are segmented based on their location, with those in the second region receiving additional or larger contact holes compared to those in the first region. This segmentation strategy allows targeted compensation for active layer width variations in specific substrate regions while maintaining manageable manufacturing precision requirements through systematic regional differentiation.
Data Source
AI summary
An organic light-emitting diode (OLED) display is disclosed. In one aspect, the display includes a substrate including a display area configured to display an image and the display area includes first and second regions. A plurality of OLEDs are formed in the display area and separated from one another, and a plurality of pixel circuits are formed in the display area and include first and second pixel circuits respectively formed in the first and second regions. First and second contact holes are respectively formed in the first and second pixel circuits, each pixel circuit including thin film transistors (TFTs) including first and second TFTs and electrically connected to the OLEDs. Each pixel circuit includes a node line configured to electrically connect the first TFT to the second TFT through the first and second contact holes, and the first contact hole of is different from the second contact hole.