Dummy TFTs for Bending Stress Testing in Flexible OLED Displays
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Solution Overview
Problem
Flexible organic light-emitting display devices (OLEDs) face damage from stress caused by bending, requiring effective testing methods to ensure normal operation.
Innovation Solution
A display device with dummy thin-film transistors and test pads in a non-display area, connected to a test circuit film and meter, allows for real-time checking of the influence of bending on these components, using reference lines and multiple dummy transistors to simulate various bending directions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If flexible OLEDs are bent to enable folding or rolling, then adaptability and versatility are improved, but stress damage to elements occurs reducing reliability
Solution Approach 1:
The patent applies preliminary action by pre-forming a bending area with controlled stress characteristics before final device assembly. This allows the display device to be pre-adapted to bending conditions, enabling folding capability while maintaining element integrity through预先 designed stress distribution in the bending area
2Measurement precision
If dummy thin-film transistors are added in the non-display area, then measurement precision is improved, but device complexity increases
Solution Approach 1:
The patent uses copying by creating dummy thin-film transistors that replicate the structure and electrical characteristics of actual switching elements. These dummy transistors serve as test copies to measure bending stress effects without requiring modification of the display area, achieving precise measurement while controlling complexity through strategic placement in the non-display area
Solution Approach 2:
The dummy thin-film transistors serve multiple functions: they act as both structural references for bending stress measurement and as electrical test elements. This multi-functionality allows a single added component to provide both mechanical and electrical characterization capabilities, improving measurement precision without proportionally increasing device complexity
3Measurement precision
If multiple dummy transistors with different reference line orientations are used, then measurement precision for various bending directions is improved, but device complexity increases
Solution Approach 1:
The patent applies asymmetry by orienting reference lines of dummy thin-film transistors in different directions (e.g., first reference line in one direction, second reference line in another direction). This asymmetric configuration enables the measurement system to detect bending stresses from multiple directions simultaneously, improving measurement precision for complex bending scenarios while maintaining a relatively simple overall structure
Data Source
AI summary
Disclosed herein are a display device, an apparatus for testing a display device, and a method for testing a display device. A display device includes a first substrate having a display area and a non-display area defined thereon, the non-display area being on an outer side of the display area. The non-display area may include a plurality of test pads and a first dummy thin-film transistor electrically connected to the test pads. The first dummy thin-film transistor includes a dummy gate electrode, and a dummy source electrode and a dummy drain electrode insulated from the gate electrode and spaced apart from each other. A bending area is defined on the first substrate that at least partially traverses the display area and the non-display area, the bending area overlaps the first dummy thin-film transistor.