Dummy-Area TFT Isolation in Electroluminescent Displays
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Solution Overview
Problem
Electroluminescent display devices face issues with linear mura formation in the active area due to abnormal signals transmitted from the dummy area, which can occur when manufacturing errors lead to incomplete or faulty signal lines and thin film transistors in the dummy area.
Innovation Solution
The implementation of a dummy area with specific configurations, including a scan line, initializing line, emission line, high power source line, and data line arranged in a particular pattern, along with thin film transistors that are disconnected to prevent signal transmission and reduce the likelihood of mura formation by isolating the dummy area from the active area.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If signal lines and thin film transistors are patterned in the dummy area similar to the active area, then manufacturing consistency is improved, but abnormal signals may be transmitted to the active area causing linear mura
Solution Approach 1:
The dummy area is segmented into multiple isolated transistor units (switching TFTs and operation control TFTs) that are disconnected from each other. This segmentation prevents abnormal signals from propagating across the entire dummy area to the active area, while still maintaining the beneficial manufacturing consistency of having complete transistor patterns in the dummy area.
Solution Approach 2:
The harmful function of signal transmission is extracted and removed from the dummy area transistors. By disconnecting the switching TFT and operation control TFT from each other, the patent eliminates the pathway for abnormal signals to reach the active area, while preserving the structural benefits of complete transistor patterning for manufacturing consistency.
2Reliability
If the dummy area is completely isolated from signal lines, then mura occurrence is prevented, but manufacturing complexity increases due to different patterns
Solution Approach 1:
The patent applies local quality by making the connection status specific to each transistor type in the dummy area. The switching TFT is disconnected from the operation control TFT, creating a localized disconnection that prevents signal transmission. This approach maintains manufacturing simplicity by using the same overall pattern layout as the active area, while achieving reliable mura prevention through targeted local modifications.
Data Source
AI summary
Disclosed is an electroluminescent display device comprising an active area for displaying an image, a dummy area provided in the periphery of the active area, wherein an image is not displayed in the dummy area, a scan line, an initializing line and an emission line arranged along a first direction in the dummy area, a high power source line and a data line arranged along a second direction, which intersects with the first direction, in the dummy area, and a plurality of thin film transistors disposed in the dummy area, wherein the plurality of thin film transistors include a driving thin film transistor, a switching thin film transistor provided to connect the driving thin film transistor and the data line with each other, and an operation control thin film transistor provided to connect the driving thin film transistor and the high power source line with each other, wherein the switching thin film transistor and the operation control thin film transistor are disconnected from each other.