Display Device Opposing Electrode Thickness Control
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Solution Overview
Problem
Existing display devices with organic light-emitting elements face challenges in efficiently measuring the thickness of the opposing electrode, which affects the display quality due to high sheet resistance and variability in film-formation conditions, leading to production of defective articles.
Innovation Solution
A display device structure where the first and second wirings are spaced and connected through contact electrodes, allowing the opposing electrode to be electrically connected, enabling measurement of resistance between the wirings to estimate the thickness of the opposing electrode non-destructively and in real-time, thus ensuring precise manufacture management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the opposing electrode is made thinner to reduce sheet resistance, then the electrical conductivity improves, but the measurement precision of thickness control deteriorates due to variability in film-formation conditions
Solution Approach 1:
The patent implements a feedback mechanism by measuring the resistance between the first and second wirings through the opposing electrode and using this measurement to control the film formation process. The film formation is performed in a first period to form the opposing electrode, then resistance is measured, and if necessary, the film formation is performed in a second period to adjust the thickness. This closed-loop feedback system ensures that the opposing electrode achieves the target resistance value while maintaining precise thickness control.
Solution Approach 2:
The patent performs preliminary film formation of the opposing electrode in a first period before the final measurement and adjustment. This preliminary action allows the system to establish an initial layer that can be subsequently refined. The film formation is performed preliminarily to create a base thickness, then resistance measurement provides feedback for determining whether additional film formation is needed to achieve the target specifications.
2Measurement precision
If traditional destructive sampling methods are used to measure opposing electrode thickness, then the measurement precision may be adequate, but the productivity decreases due to time-consuming processes and loss of articles
Solution Approach 1:
The patent replaces mechanical destructive measurement methods with an electrical resistance measurement system. Instead of physically sectioning and measuring the opposing electrode thickness through destructive sampling, the system measures the electrical resistance between the first and second wirings, which correlates with the opposing electrode thickness and conductivity. This substitution enables non-destructive, rapid measurement that maintains precision while dramatically improving productivity.
Solution Approach 2:
The patent uses electrical resistance as an intermediary parameter to indirectly measure the opposing electrode thickness. Rather than directly measuring thickness through destructive methods, the system measures resistance between the wirings, which serves as a proxy that reflects both thickness and conductivity. This intermediary measurement approach provides sufficient precision for quality control without requiring physical destruction of the sample.
3Productivity
If the opposing electrode thickness is not precisely controlled, then the manufacturing process is faster, but the display quality deteriorates due to defects from high sheet resistance
Solution Approach 1:
The patent implements feedback control where the resistance measurement results directly influence subsequent film formation decisions. The system measures resistance after initial film formation, compares it to target specifications, and automatically determines whether additional film formation is needed. This feedback mechanism ensures that display quality requirements are met while avoiding unnecessary processing steps that would reduce productivity.
Solution Approach 2:
The patent employs a dynamic manufacturing process where the number of film formation periods is not fixed but adapts based on resistance measurement results. The film formation may be performed in a first period, followed by measurement, and then conditionally in a second period if the resistance is not within specifications. This dynamic approach allows the process to be as fast as possible while ensuring quality requirements are met.
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 allows for precise control of the opposing electrode's thickness, improving display quality by reducing defects and enabling rapid feedback for mass production, unlike traditional methods that require destructive sampling and are time-consuming.
Implementation Method 1
measuring a resistance between the first wiring and the second wiring
Data Source
AI summary
Disclosed is a display device possessing: a plurality of pixels arranged in a matrix form over a substrate and each having a pixel electrode; a first wiring and a second wiring over the substrate and sandwiching the pixels; a first contact electrode and a second contact electrode respectively covering at least a part of the first wiring and at least a part of the second wiring; and an opposing electrode over and overlapping with the pixel electrodes, the first contact electrode, and the second contact electrode, the opposing electrode being shared by the plurality of pixels. The first wiring and the second wiring are spaced from each other and electrically connected to the opposing electrode through the first contact electrode and the second contact electrode, respectively.