Display Panel Fan-Out Test Circuit Layout for Defect Detection
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Solution Overview
Problem
The use of a fan-out-in-active-area (FIAA) structure in display panels to reduce bezel size leads to disorder in the arrangement of fan-out lines, making it difficult to detect defective panels during inspection, resulting in missed defects and subsequent manufacturing waste.
Innovation Solution
A display panel design with a specific arrangement of first and second fan-out lines, test circuit units, and test signal lines, where second fan-out lines are ordered differently from data lines, allowing for distinct test signals to be applied to adjacent columns, enabling detection of defects through alternating pixel unit illumination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If fan-out lines are arranged in disorder to reduce bezel size, then bezel size is reduced, but detection difficulty increases
Solution Approach 1:
The fan-out lines are divided into two distinct groups: first fan-out lines extending from first data lines, and second fan-out lines extending from second data lines. This segmentation allows each group to have different arrangement characteristics, enabling the second fan-out lines to be deliberately disordered relative to data lines while maintaining overall detectability through the structured test circuit configuration.
Solution Approach 2:
Test circuit units are introduced as intermediary components between the disordered second fan-out lines and the test signal lines. These test circuit units include switches that can selectively connect to different test signal lines based on column position, acting as mediators that translate the disordered fan-out line arrangement into a detectable pattern through controlled illumination of pixel units.
2Measurement precision
If second fan-out lines are arranged differently from data lines, then detection capability is improved, but device complexity increases
Solution Approach 1:
The test circuit units are designed with multi-functionality, where switches can connect to different test signal lines (first test signal line or second test signal line) depending on the column position. This universal design allows the same test circuit unit structure to handle multiple detection scenarios across different columns, improving detection capability without proportionally increasing overall device complexity.
Solution Approach 2:
Instead of arranging fan-out lines in the same order as data lines (conventional approach), the patent inverts this arrangement by deliberately ordering second fan-out lines differently from their corresponding data lines. This inversion creates a detectable pattern that enables identification of defects, particularly in columns where pixel units should be illuminated alternately.
3Measurement precision
If test signals are applied to adjacent columns, then defect detection accuracy is improved, but manufacturing complexity increases
Solution Approach 1:
Different test signal lines (first test signal line and second test signal line) are applied to different column groups (odd columns and even columns). This local quality approach allows adjacent columns to receive different test signals, improving defect detection accuracy by creating distinguishable illumination patterns, while the systematic assignment of signals to column parity groups keeps manufacturing complexity manageable.
Data Source
AI summary
A display panel includes pixel units, data lines, first fan-out lines located in an active area, second fan-out lines, test circuit units, and test signal lines located in a non-active area. A first fan-out line is electrically connected to a corresponding first data line. Each test circuit unit includes switches including first switches and second switches. First ends of the first switches are electrically connected to the first fan-out lines through corresponding second fan-out lines. First ends of second switches are electrically connected to corresponding second data lines through corresponding second fan-out lines. Second ends of switches electrically connected to corresponding pixel units in the same column are electrically connected to the same test signal line. Second ends of switches electrically connected to corresponding pixel units in two adjacent columns are electrically connected to different test signal lines.