Display Panel TEG Measurement for Leakage-Free Transfer Curves
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Solution Overview
Problem
Existing methods for evaluating display driving elements in display panels face inaccuracies due to leakage currents when measuring the characteristics of driving transistors, leading to incorrect transfer curves.
Innovation Solution
A method is introduced to evaluate display driving elements by controlling transistors connected to the target driving transistor in a test element group (TEG) to be turned off, using additional pads to apply off voltages and measure characteristics through terminals, thereby blocking leakage currents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If transistors connected to the target driving transistor are not controlled to be turned off, then the measurement process is simpler, but leakage currents occur leading to inaccurate measurement of driving transistor characteristics
Solution Approach 1:
The measurement method applies off voltages to transistors connected to the target driving transistor before performing the characteristic measurement. This preliminary action ensures that leakage currents are blocked in advance, allowing accurate measurement of driving transistor characteristics without interference from adjacent transistors.
Solution Approach 2:
The patent introduces additional pads as intermediary elements that facilitate the application of off voltages to control transistors. These pads serve as mediation points between the measurement system and the transistors, enabling precise control of leakage current paths during the measurement process.
2Measurement precision
If additional pads are added to apply off voltages, then leakage currents are blocked improving measurement accuracy, but the device structure becomes more complex
Solution Approach 1:
The measurement system is segmented into distinct control paths for each transistor that may contribute leakage current. Each transistor connected to the target driving transistor has its own dedicated pad for applying off voltages, allowing independent control of leakage current paths and simplifying the overall control logic despite the increased number of pads.
3Measurement precision
If transistors are not controlled during measurement, then the measurement process is faster, but leakage currents cause incorrect transfer curves
Solution Approach 1:
The measurement process employs periodic control signals that temporarily activate the off-voltage application to blocks leakage currents only during the specific measurement interval. This periodic action ensures accurate transfer curve determination while minimizing the time leakage current control is active, thus maintaining measurement speed.
Data Source
AI summary
A method of evaluating a display driving element includes controlling a transistor to be turned off, where the transistor is connected to a first end of a target driving transistor of a test element group (TEG) disposed in a non-display area of a display panel, and measuring characteristics of the target driving transistor through pads connected to respective terminals of the target driving transistor.