Multilayer Power Supply Line for OLED Shading Reduction
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Solution Overview
Problem
In organic EL display devices, shading and stripe nonuniformity occur due to pulse delay and voltage drops in the power supply line, leading to image graininess and quality issues, especially as panel size and definition increase.
Innovation Solution
The power supply line is formed as multilayer wiring to reduce resistance and minimize voltage drops, with a pixel circuit configuration that includes a driving transistor, a light emitting element, and a switching transistor, and the use of multilayer wiring for the power supply line and source electrode to improve image quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the power supply line is formed as single-layer wiring, then the device complexity is reduced, but voltage drops occur leading to shading and stripe nonuniformity
Solution Approach 1:
The power supply line is transformed from a single-layer structure to a multilayer wiring structure, adding the dimension of vertical stacking. This allows multiple wiring layers to be connected in parallel, reducing equivalent resistance and voltage drops without increasing planar area, thereby suppressing shading and stripe nonuniformity while maintaining acceptable device complexity
Solution Approach 2:
The multilayer wiring structure combines multiple conductive material layers to form a composite power supply line system. This composite structure reduces overall resistance through parallel conduction paths, improving current distribution uniformity across the display panel and eliminating image quality defects
2Measurement precision
If the display panel size and definition are increased, then the image quality is improved, but voltage drops in the power supply line increase causing shading and stripe nonuniformity
Solution Approach 1:
The power supply line is segmented into multiple parallel conductive paths across different wiring layers. This segmentation creates multiple independent current channels that distribute electrical load more evenly across the large display panel, reducing voltage drops in any single path and maintaining uniform current distribution even as panel size and definition increase
Solution Approach 2:
By transitioning from planar single-layer wiring to three-dimensional multilayer wiring, the patent adds vertical dimension to current distribution. This allows longer diagonal connections in large high-definition panels to be compensated by alternative shorter paths in different layers, reducing cumulative voltage drops and maintaining current uniformity across the expanded display area
3Reliability
If the resistance of the power supply line is reduced, then voltage drops are minimized improving image quality, but more wiring layers are required increasing device complexity
Solution Approach 1:
Multiple wiring layers are merged into a unified parallel conduction system for the power supply line. The conductive paths in different layers are electrically connected to function as a single low-resistance power delivery network, combining the advantages of multiple layers while presenting a unified interface to pixel circuits, thereby reducing voltage drops without proportionally increasing device complexity
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 solution effectively suppresses shading and stripe nonuniformity, providing high-quality images by reducing resistance in the power supply line and maintaining constant current through the light emitting element, even as the display device's size and definition increase.
Implementation Method 1
The power supply line is formed as multilayer wiring to reduce resistance and minimize voltage drops
Data Source
AI summary
A pixel circuit including: a driving transistor; a light emitting element; and a power supply line; wherein the driving transistor is connected between the power supply line and a predetermined electrode of the light emitting element, and the power supply line is formed as multilayer wiring, and an interpolating capacitance is formed such that the power supply line formed as the multilayer wiring and another conductive layer are opposed to each other at a distance.