Double-Separated Test Pad for Display Signal Integrity
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Solution Overview
Problem
Display devices, such as LCDs and OLEDs, face issues with image quality degradation due to improper output waveforms of gate and data signals, necessitating effective measurement and testing of these signals during production and troubleshooting.
Innovation Solution
Incorporation of test pad units connected to data and gate lines, featuring a double-separated test pad design with bridge members and insulating layers, allowing for accurate measurement of signal outputs while preventing interference from static electricity-induced short defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If a test pad is directly connected to data lines for signal measurement, then measurement accessibility is improved, but static electricity-induced short defects occur causing signal interference
Solution Approach 1:
The patent introduces an intermediary structure consisting of a bridge member and insulating layer between the test pad and data line. The bridge member spans across the data line without direct contact, and the insulating layer prevents electrical shorting while allowing capacitive coupling for signal measurement. This intermediary arrangement enables measurement accessibility while maintaining signal integrity by preventing static electricity-induced short defects.
2Reliability
If the test pad is electrically separated from data lines to prevent short defects, then signal interference is reduced, but measurement capability is lost
Solution Approach 1:
The bridge member acts as a mediator that provides capacitive coupling between the test pad and data line without direct electrical contact. This allows the test pad to measure data signals through the insulating layer while maintaining electrical separation to prevent short defects. The intermediary structure simultaneously achieves both signal integrity and measurement capability.
Solution Approach 2:
The patent replaces direct electrical contact (mechanical/electrical connection) with capacitive coupling through the insulating layer. This substitution allows signal measurement without physical electrical contact, eliminating the risk of short defects while maintaining measurement functionality through electric field interaction.
3Adaptability or versatility
If multiple test pad units are added to measure both gate and data signals, then comprehensive signal testing is improved, but device complexity increases
Solution Approach 1:
The test pad unit is designed as a universal structure that can measure both gate and data signals by connecting to different lines. The same bridge member and insulating layer configuration serves multiple measurement purposes, reducing overall device complexity compared to having separate dedicated test structures for each signal type.
Solution Approach 2:
The patent divides the testing function into modular test pad units, each independently structured with its own bridge member and insulating layer. This segmentation allows flexible placement and connection to different signal lines while maintaining a standardized design, making the overall system more manageable despite increased complexity from multiple units.
Data Source
AI summary
Provided is a display device including a plurality of pixels; a plurality of data lines connected to the plurality of pixels; a data driver applying data voltages to the plurality of data lines; and a first test pad unit connected to at least one of the plurality of data lines in order to check the data voltages, in which the first test pad unit includes a test pad which is electrically double-separated from the at least one of the data lines.