Display Substrate Detection via Threshold Voltage Excitation
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
The existing methods for detecting display substrates in OLED manufacturing are inaccurate, leading to defects in display uniformity (mura) due to uneven metal oxide film thicknesses, which are not effectively identified until subsequent testing, resulting in a low matching rate between detection accuracy and reliability tests.
Innovation Solution
A method and device that excite the threshold voltage of driving transistors in pixel driving circuits, input a detection signal, and judge the substrate's normalcy based on voltage outputs from both target and non-target areas, using a liquid crystal cell to differentiate voltage patterns and improve detection accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If metal oxide sputtering is used to deposit metal oxide on glass substrate, then display elements can be manufactured to form display substrate, but thicknesses of metal oxide film layer in target area and non-target area become non-uniform
Solution Approach 1:
The patent applies preliminary action by introducing a threshold voltage compensation mechanism before the display substrate is put into service. During the manufacturing detection phase, excitation signals are applied to driving transistors in target areas to proactively identify and flag substrates with threshold voltage shifts caused by non-uniform film thickness, preventing defective substrates from proceeding to subsequent assembly stages.
Solution Approach 2:
The patent utilizes parameter changes by measuring threshold voltage as an indirect indicator of film thickness uniformity. Instead of directly measuring physical film thickness, the method changes the measurement parameter to electrical threshold voltage, which reflects the cumulative effect of film thickness variations on transistor performance, enabling detection of manufacturing defects.
2Device complexity
If detection is performed without exciting threshold voltage, then detection process is simple, but threshold voltage shifted transistors cannot be effectively identified
Solution Approach 1:
The patent applies preliminary action by pre-exciting the threshold voltage of driving transistors before performing detection. Excitation signals are applied to intentionally shift the threshold voltage to an extreme state, causing transistors with already-shifted thresholds (due to non-uniform film thickness) to exhibit abnormal voltage outputs that can be easily detected and flagged for further inspection.
Solution Approach 2:
The patent changes the detection parameter from static voltage measurement to dynamic threshold voltage excitation measurement. By applying excitation signals that push the transistor into threshold voltage shift conditions, the method transforms subtle manufacturing defects into pronounced electrical characteristics that are easier to detect with simple measurement circuits.
3Productivity
If conventional detection methods are used, then detection process is straightforward, but matching rate between detection accuracy and reliability tests is low
Solution Approach 1:
The patent implements feedback by using detection results from threshold voltage excitation measurements to guide subsequent reliability testing and sorting decisions. Substrates exhibiting abnormal voltage outputs during excitation are flagged and either rejected or subjected to additional verification tests, creating a feedback loop that continuously improves the accuracy of defect detection and reduces the mismatch between detection results and actual reliability.
Data Source
AI summary
The present disclosure provides a method for detecting a display substrate and a device for detecting a display substrate. The method includes: exciting a threshold voltage of a driving transistor in each pixel driving circuit in the display substrate, so that the threshold voltage of the driving transistor with a shifted threshold voltage is further shifted; inputting a detection signal to each pixel driving circuit in the display substrate, where the detection signal is a signal enabling the pixel driving circuit to operate normally; and judging whether the display substrate is normal or not according to the voltage output by each pixel driving circuit.