OLED Storage Capacitor Offset Design for Overlay Variation
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Solution Overview
Problem
Existing organic light emitting diode (OLED) display devices face issues with spot generation due to overlay changes caused by nonuniform exposure amounts during the photolithography process, leading to uneven storage capacitance and nonuniform current flow in pixels.
Innovation Solution
The implementation of a storage compensation unit in the storage capacitor, where the second storage electrode is offset from the first storage electrode, and a storage compensator is positioned to face the connector on a diagonal line, helps maintain consistent storage capacitance even with overlay changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If photolithography process is used to form wire patterns, then manufacturing efficiency is improved, but overlay changes occur due to nonuniform exposure amounts causing spots
Solution Approach 1:
The patent changes the geometric parameters of the storage capacitor electrodes by introducing offset distances between the first storage electrode and the second storage electrode. This parameter modification compensates for overlay variations during photolithography, maintaining consistent storage capacitance values despite exposure nonuniformity, thereby resolving the contradiction between manufacturing efficiency and overlay precision
Solution Approach 2:
The patent applies preliminary design adjustments to the storage capacitor structure by pre-calculating and setting specific offset distances between electrodes before the photolithography process. This preliminary action anticipates and compensates for potential overlay changes, ensuring that storage capacitance remains within acceptable ranges even when manufacturing variations occur
2Ease of manufacture
If overlay change occurs during photolithography, then manufacturing process is simplified, but storage capacitance becomes nonuniform causing spots
Solution Approach 1:
The patent modifies the geometric parameters of the storage capacitor by setting specific offset distances between the first storage electrode and the second storage electrode. This parameter change makes the storage capacitance less sensitive to overlay variations, maintaining reliability while keeping the manufacturing process simple
Solution Approach 2:
The patent introduces asymmetric offset distances between the first storage electrode and the second storage electrode relative to each other. This asymmetric design compensates for overlay changes in a specific direction, ensuring uniform storage capacitance while maintaining ease of manufacture through a straightforward photolithography process
3Manufacturing precision
If storage capacitor electrodes are aligned, then manufacturing precision is improved, but device complexity increases due to additional alignment constraints
Solution Approach 1:
Instead of aligning the first storage electrode and the second storage electrode as in conventional designs, the patent inverts the approach by deliberately offsetting them by specific distances. This inversion simplifies the manufacturing process by reducing alignment constraints while maintaining manufacturing precision through the designed offset geometry
Data Source
AI summary
An organic light emitting diode display device or an electronic device includes: a substrate; a scan line to transfer a scan signal; a data line and a driving voltage line to transfer a data voltage and a driving voltage, respectively; a switching transistor including a switching drain electrode to output the data voltage; a driving transistor including a driving gate electrode connected with the switching drain electrode; a storage capacitor including a first storage electrode connected with the driving gate electrode and a second storage electrode connected with the driving voltage line; and an organic light emitting diode connected with a driving drain electrode of the driving transistor. The storage capacitor includes: a connector in which an edge of the second storage electrode is offset from an edge of the first storage electrode toward the center of the second storage electrode, and a storage compensator facing the connector.