Pixel Alignment Monitoring Circuit for Short-Defect Isolation
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Solution Overview
Problem
Display devices face issues with alignment deterioration due to short circuit defects in test electrodes, which affect the alignment signal of pixels and lead to reduced performance.
Innovation Solution
A display device design that includes test electrodes connected to electrodes through test transistors, allowing for pre-alignment monitoring, and a conductive pattern between electrodes and test electrodes, which can be disconnected after alignment to prevent alignment signal interference, even if a short defect occurs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If test electrodes are connected to electrodes for pre-alignment monitoring, then alignment monitoring capability is improved, but short circuit defects in test electrodes can cause alignment deterioration
Solution Approach 1:
The conductive layer is segmented into multiple patterns: test electrodes for monitoring, main electrodes for operation, and isolated conductive patterns. This segmentation allows the test electrodes to be electrically isolated from the main electrodes through insulating layers, so that short circuit defects in test electrodes do not affect the alignment signals of the main electrodes, thus resolving the contradiction between monitoring capability and alignment stability
Solution Approach 2:
Insulating layers are introduced as intermediary elements between the test electrodes and main electrodes. These insulating layers allow the test electrodes to remain electrically connected to the conductive layer for monitoring purposes, while simultaneously preventing harmful electrical interference from short circuit defects from reaching the main electrodes, thus protecting alignment stability
2Device complexity
If test electrodes and electrodes use the same conductive layer, then device complexity is reduced, but short defects in test electrodes can interfere with alignment signals
Solution Approach 1:
The conductive layer is divided into functionally separate patterns (test electrodes, main electrodes, and isolated patterns) with different electrical connection requirements. Test electrode patterns are covered with insulating layers to isolate them electrically, while main electrode patterns remain exposed for signal transmission. This segmentation enables using the same conductive layer material and deposition process for both, reducing device complexity, while preventing short defects from affecting alignment signals
Solution Approach 2:
Different regions of the conductive layer are given different local qualities through selective insulation. Areas corresponding to test electrodes are covered with insulating layers to prevent electrical interference, while areas corresponding to main electrodes remain conductive for alignment signal transmission. This local differentiation allows the system to maintain simplicity while protecting against harmful effects
Data Source
AI summary
A display device includes electrodes spaced from each other in a display area, light emitting elements between the electrodes, test electrodes spaced from each other in a test area, and a test transistor electrically connected to the electrodes and the test electrodes.