LCD Pad Segmentation for Flexible Testing
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Solution Overview
Problem
Existing liquid crystal display (LCD) testing methods face challenges such as signal delay and false line defect detection due to pin contact failures, and lack flexibility in testing individual pixels or small groups of pixels.
Innovation Solution
The solution involves forming gate and data pads with sub-groups of shorting bars that are independently connected, allowing for the application of test signals to odd and even sub-groups, reducing pin-contact failures and enabling more flexible testing by applying signals to specific sub-groups of pads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If needle pins contact all data pads and gate pads for testing, then the test can be performed by applying test signals in the same manner as real signals, but false line defect detection occurs due to pin contact failure
Solution Approach 1:
The gate pads and data pads are divided into multiple groups (first through fourth groups), with each group connected to a separate shorting bar. This segmentation allows selective testing of different pad groups using fewer needle pins, reducing contact failures while maintaining comprehensive test coverage through systematic group-by-group testing.
2Measurement precision
If a jig of needle pins contacts all data pads and gate pads, then complete coverage testing is achieved, but the jig must be manufactured for each model of LC panel
Solution Approach 1:
The shorting bar structure provides universal functionality across different LC panel models. By connecting multiple pads within each group to a single shorting bar, the same testing apparatus can be used for various panel sizes and configurations, eliminating the need to manufacture custom jigs for each model while maintaining complete test coverage.
3Ease of operation
If all even and odd gate pads and data pads are combined using shorting bars, then the number of contacts is reduced, but signal delay occurs during testing
Solution Approach 1:
The pad groups are segmented and tested sequentially rather than simultaneously. This allows the testing process to progress through different groups in a controlled manner, managing signal timing and reducing delays while maintaining the reduced contact advantage of the shorting bar approach.
4Measurement precision
If needle pins contact each pad individually, then precise individual pad testing is possible, but two or more operators are required
Solution Approach 1:
By grouping pads and connecting them to shorting bars, the testing process can be automated with a single operator controlling the sequential testing of each group. The segmentation into manageable groups maintains the precision of individual pad testing while reducing the need for multiple operators to handle individual pin contacts.
Data Source
AI summary
A liquid crystal display device includes gate pads on a first side of an insulating substrate, gate pad parts, which contain a sub-group of the gate pads, a plurality of gate shorting bars within the gate pad parts, data pads on a second side of the insulating substrate, data pad parts, which contain a sub-group of the data pads, and a plurality of data shorting bars within the gate pad parts.