OLED Pixel Repair via Thin Film Transistor Segmentation
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Solution Overview
Problem
Active-matrix OLED displays often suffer from defective pixels, particularly white spots caused by continuous electric current supply, which degrade display quality and are difficult to repair due to their complex configuration.
Innovation Solution
A display device design featuring a thin film transistor with a repair region not covered by the pixel electrode, allowing for the blocking of electric current to defective pixels, and a method involving a wall structure and specific electrode configurations to facilitate easy repair by laser irradiation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a complex thin film transistor configuration is used in each pixel area, then the display device achieves better performance control, but the difficulty of repairing defective pixels increases
Solution Approach 1:
The thin film transistor is segmented into multiple electrode parts (first part, second part, third part) with different widths and functions. The second part protrudes and has a different width, creating distinct functional zones that can be independently addressed during repair operations, allowing the complex transistor to be repaired in sections rather than as a whole unit.
Solution Approach 2:
The repair region is extracted as a separate accessible area where the pixel electrode does not cover the thin film transistor. This extracted region allows repair tools and methods to access and modify the transistor structure without interference from the pixel electrode, enabling targeted repair of defective pixels while preserving the overall complex configuration.
2Reliability
If the pixel electrode covers the entire thin film transistor, then electrical connection is improved, but the ability to perform laser repair is reduced
Solution Approach 1:
The pixel electrode is designed with non-uniform coverage: it covers most of the thin film transistor to ensure good electrical connection, but deliberately leaves the repair region exposed. This local differentiation in coverage allows the electrode to simultaneously achieve both full electrical connectivity where needed and accessibility where repair is required.
Solution Approach 2:
The thin film transistor is pre-configured with a protruding second part and defined width variations during manufacturing, creating an inherent repair region before any defect occurs. This preliminary structural arrangement ensures that when defects arise, the repair area is already prepared and accessible for laser intervention without requiring additional manufacturing steps.
3Ease of manufacture
If a uniform electrode width is used throughout the thin film transistor, then manufacturing is simplified, but the capability to block current during repair is reduced
Solution Approach 1:
The thin film transistor employs asymmetric electrode width design where the second part protrudes and has a different width compared to the first and third parts. This asymmetric configuration is deliberately introduced to create functional differentiation: the varying widths enable specific regions to serve as current blocking zones during repair while maintaining overall manufacturing feasibility through standardized fabrication processes.
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
Enables efficient detection and repair of defective pixels, converting white spots to black spots without affecting neighboring pixels or the common electrode, thereby improving display quality and ease of maintenance.
Implementation Method 1
a method involving a wall structure and specific electrode configurations to facilitate easy repair by laser irradiation
Data Source
AI summary
A display device that lends itself to easy repair of a defective pixel is presented. The device includes: a thin film transistor formed having a first electrode and a second electrode, the second electrode having a first part facing the first electrode, a second part that protrudes from the first part and having a first width, and a third part that extends from the second part and having a second width which is different from the first width. The device also includes a wall encompassing the pixel electrode and a common electrode formed on the wall.In one version of the repairing process, the second part of the second electrode is coupled to the common electrode. This coupling causes electric current from the second electrode to flow to the common electrode instead of to a light emitting diode, thereby converting a white spot to a black spot.