Flexible OLED Display TFT Placement in Non-Bending Zones
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Solution Overview
Problem
Flexible OLED displays experience display errors, such as dark or bright lines, in the bending area due to repetitive bending, which affects the electrical characteristics of thin-film transistors and leads to inconsistent brightness.
Innovation Solution
The OLED display design includes a substrate with a bending area and non-bending areas, where thin-film transistors (TFTs) are formed only in the non-bending areas, and first and second pixel electrodes are electrically connected to TFTs in different areas, with connection wirings on different layers to minimize the impact of bending on TFTs, preventing display errors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If TFTs are formed in the bending area to enable flexible display, then the display can be bent, but display errors occur due to electrical characteristic changes in TFTs under repetitive bending
Solution Approach 1:
The substrate is divided into a bending area and a non-bending area. TFTs are selectively formed only in the non-bending area, while the bending area contains only pixel electrodes and connection wirings. This segmentation allows the display to be bent without subjecting TFTs to mechanical stress, resolving the contradiction between flexibility and reliability.
Solution Approach 2:
The TFTs are extracted from the bending area and placed exclusively in the non-bending area. This extraction removes the sensitive component from the region subjected to mechanical stress, enabling the display to maintain its electrical characteristics during bending while still achieving flexibility through the overall flexible substrate structure.
2Reliability
If TFTs are formed only in non-bending areas to prevent display errors, then display reliability improves, but the number of TFTs must equal the sum of first and second pixel electrodes requiring complex wiring
Solution Approach 1:
Connection wirings are extended from the non-bending area into the bending area along the bent surface. This three-dimensional wiring approach allows electrical connections to span across the bending region without requiring additional TFTs in the bending area, maintaining reliability while managing the increased wiring complexity through spatial optimization.
Solution Approach 2:
The non-bending area serves as an intermediary zone that houses all TFTs and acts as a transition region. Connection wirings originate from TFTs in the non-bending area and extend through the bending area to reach pixel electrodes, mediating the electrical connection between the stable TFT region and the flexible display area without introducing additional active components in the bending zone.
Data Source
AI summary
An organic light-emitting diode display is disclosed. In one aspect, the display includes a substrate including a bending area and a non-bending area and a plurality of thin-film transistors (TFTs) formed in the non-bending area. The display also includes a plurality of first pixel electrodes and a plurality of second pixel electrodes formed over the TFTs and electrically connected to the TFTs, the first pixel electrodes formed in the bending area and the second pixel electrodes formed in the non-bending area.