OLED Common Power Line Segmentation for Voltage Drop
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Solution Overview
Problem
In organic light emitting diode (OLED) displays, the elongation of the common drain power line increases line resistance, leading to voltage drops and non-uniform current distribution, resulting in uneven light emission luminance across the display.
Innovation Solution
The implementation of a common power line with a planar portion parallel to the substrate surface and connection portions extending orthogonally, which increases the line width and reduces resistance, ensuring uniform voltage application to all driving thin film transistors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the common drain power line is elongated to cover larger display areas, then the display size is increased, but the line resistance increases causing voltage drops and non-uniform current distribution
Solution Approach 1:
The common drain power line is divided into multiple segments with individual compensation capacitors connected to each segment. This segmentation allows local voltage compensation at different positions along the power line, reducing the cumulative voltage drop effect across the elongated line while maintaining uniform voltage distribution to all OLED elements.
Solution Approach 2:
Compensation capacitors are introduced as intermediary elements between the power supply and OLED elements. These capacitors store and release electrical energy to compensate for voltage drops in real-time, acting as mediators that maintain stable voltage levels despite the elongation of the power line.
2Area of stationary object
If the common drain power line is elongated, then larger display area is achieved, but current uniformity deteriorates resulting in non-uniform luminance
Solution Approach 1:
The power delivery system is segmented into multiple zones along the common drain power line, with each zone having its own compensation capacitor. This ensures that each segment receives uniformly compensated voltage, maintaining consistent current flow and luminance output across the entire enlarged display area.
Solution Approach 2:
The voltage parameter is dynamically adjusted along the length of the common drain power line by introducing compensation capacitors at strategic positions. This changes the electrical parameters locally to compensate for IR drops, ensuring that the current and resulting luminance remain uniform across the expanded display area.
3Reliability
If the line width is increased to reduce resistance, then voltage uniformity is improved, but the device complexity and manufacturing difficulty increase
Solution Approach 1:
Instead of uniformly increasing the line width across the entire common drain power line, the invention applies local quality enhancement by adding compensation capacitors only at specific positions where voltage drops occur. This targeted approach improves voltage uniformity without the manufacturing complexity of redesigning the entire power line geometry.
Data Source
AI summary
An organic light emitting diode (OLED) display including a substrate main body; a driving circuit on the substrate main body; an organic light emitting element on the driving circuit; and a front substrate covering the organic light emitting element and coupled to the substrate main body, wherein the driving circuit includes a wire, the wire including a planar portion parallel to a surface of the substrate main body, and a connection portion connected to the planar portion and extending in a direction orthogonal to the substrate main body.