OLED Storage Capacitor Layout for Overlay-Tolerant Pixel Uniformity

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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 OLED display device incorporates a storage compensation unit within 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, maintaining storage capacitance consistency even with overlay changes.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Productivity

If photolithography process is used to form wire patterns, then manufacturing capability is improved, but overlay changes occur causing nonuniform exposure amounts and spot generation

Engineering Contradiction:

Improvemanufacturing capabilityVSAvoidoverlay precision

Core Design Contradiction:

ProductivityVSManufacturing precision

Solution Approach 1:

The patent changes the geometric parameters of the storage capacitor electrodes by introducing cutout portions and protrusion portions. The second storage electrode includes a cutout portion that corresponds to the first storage electrode, and a protrusion portion that extends toward the first storage electrode. This parameter modification compensates for overlay changes by maintaining effective overlapping area despite positional deviations during photolithography processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent introduces asymmetric features to the storage capacitor electrodes. The second storage electrode is designed with a cutout portion and a protrusion portion that creates an asymmetric structure relative to the first storage electrode. This asymmetric design allows the capacitor to tolerate overlay variations by ensuring that the effective overlapping area remains relatively constant even when electrode positions shift during manufacturing.

Inventive Principle:

Principle #4Asymmetry

2Reliability

If storage capacitor electrodes are aligned, then storage capacitance is maximized, but overlay changes cause capacitance variation and current nonuniformity

Engineering Contradiction:

Improvestorage capacitance stabilityVSAvoidelectrode alignment

Core Design Contradiction:

ReliabilityVSManufacturing precision

Solution Approach 1:

The patent modifies the geometric parameters of the storage capacitor electrodes by introducing cutout portions and protrusion portions. The second storage electrode includes a cutout portion that corresponds to the first storage electrode, and a protrusion portion that extends toward the first storage electrode. This parameter modification compensates for overlay changes by maintaining effective overlapping area despite positional deviations during photolithography processing.

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent applies preliminary anti-action by pre-designing the electrode structures with cutout and protrusion features that anticipate and counteract potential overlay errors. The protrusion portion of the second electrode is positioned to compensate for expected misalignment, effectively pre-correcting the alignment issue before manufacturing errors occur.

Inventive Principle:

Principle #9Preliminary anti-action

3Device complexity

If conventional storage capacitor structure is used, then device complexity is minimized, but spot generation occurs due to overlay changes

Engineering Contradiction:

Improvecapacitor structureVSAvoidspot generation

Core Design Contradiction:

Device complexityVSObject-generated harmful factors

Solution Approach 1:

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent converts the harmful effect of overlay changes into a benefit by designing the electrode structures so that the cutout and protrusion features cause the capacitance to become less sensitive to misalignment. What would normally be a manufacturing defect (overlay error) is transformed into a design feature that provides tolerance against such errors, effectively converting the potential harm into improved robustness.

Inventive Principle:

Principle #22Blessing in disguise (Convert harm into benefit)

Data Source

PatentUS12225773B2Organic light emitting diode display device having a storage electrode including a cutout portion and a protrusion portion

Publication Date: 2025.02.11 SAMSUNG DISPLAY CO LTD

AI summary

An organic light emitting diode display device includes: a substrate; a scan line configured to transfer a scan signal; a data line and a driving voltage line configured to transfer a data voltage and a driving voltage, respectively; a switching transistor including a switching drain electrode configured 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 in a direction toward the center of the second storage electrode, and a storage compensator facing the connector.