OLED Test Substrate for Parasitic Capacitance Separation
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Solution Overview
Problem
Current methods for measuring capacitance in OLED display devices often result in large simulation errors due to the dominance of parasitic capacitance, especially when simulating large-area display panels, as they fail to accurately separate effective and parasitic capacitances.
Innovation Solution
A test substrate with distinct test regions and a specific layer configuration, including a base, first electrode layer, pixel defining layer, light-emitting functional layer, and second electrode layer, allows for the measurement of capacitance per unit area, enabling the extraction of parasitic capacitance and improving simulation accuracy by differentiating between effective and parasitic capacitances.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional capacitance measurement methods are used in OLED display devices, then the measurement process is simple, but large simulation errors occur due to the dominance of parasitic capacitance
Solution Approach 1:
The patent divides the test substrate into multiple distinct test regions (first test region, second test region, third test region) with different structural configurations. Each region contains pixel electrodes and common electrodes with varying areas and configurations, allowing separate measurement of effective capacitance and parasitic capacitance components. This segmentation enables accurate capacitance measurement by isolating different capacitance sources into measurable units.
Solution Approach 2:
Different test regions are designed with locally differentiated structures: the first test region has a specific pixel electrode area configuration, the second test region has a different pixel electrode area, and the third test region has yet another configuration. This local quality variation allows the measurement system to distinguish between effective capacitance (from light-emitting areas) and parasitic capacitance (from non-light-emitting areas) by comparing measurements across regions with controlled local differences.
2Measurement precision
If parasitic capacitance is not separated from effective capacitance, then the measurement process is straightforward, but simulation accuracy deteriorates when simulating large-area display panels
Solution Approach 1:
The test substrate is pre-configured with multiple test regions having known geometric relationships and area ratios before actual capacitance measurement. The pixel electrodes and common electrodes are designed with predetermined area configurations that enable direct calculation of parasitic capacitance proportions. This preliminary structural preparation allows the measurement system to quickly separate effective and parasitic capacitance components using simple area-based calculations, improving both measurement accuracy and simulation efficiency without requiring complex post-processing.
3Measurement precision
If the test substrate uses different areas for pixel electrodes in various test regions, then capacitance per unit area can be accurately measured, but the manufacturing process becomes more complex
Solution Approach 1:
The patent extends the test substrate design into the planar dimension by creating multiple test regions with systematically varied electrode areas. Instead of varying capacitance through material properties or thickness (vertical dimension), the design uses horizontal area variation of pixel electrodes and common electrodes across different test regions. This dimensional approach allows accurate capacitance per unit area measurement through geometric scaling, where capacitance values from regions with different areas can be normalized to obtain capacitance density, reducing the impact of manufacturing tolerances on absolute area dimensions.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach enables accurate construction of simulation models by effectively separating and measuring capacitances, reducing simulation errors and improving the accuracy of charge and discharge speed simulations in OLED display devices.
Implementation Method 1
a first electrode and a portion of the second electrode layer disposed opposite to the first electrode form a capacitor
Data Source
AI summary
A test substrate includes a base and a first electrode layer, a pixel defining layer, a light-emitting functional layer and a second electrode layer disposed on the base in sequence. The test substrate has at least two test regions, and each test region is a region where one first electrode of the plurality of first electrodes is located. Each test region includes a first region. Orthographic projections of portions of the pixel defining layer and the light-emitting functional layer located in a same first region on the base overlap with each other, and areas of orthographic projections of portions of the first electrode layer located in first regions of the at least two test regions are different.