OLED Pixel Circuit Metal Light Shielding Layer
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Solution Overview
Problem
In high-PPI OLED panels, the small pixel size and large signal line width lead to increased RC load and resistive voltage drops, degrading display performance, and current-driven OLEDs require stable current control, which is challenging to achieve without sacrificing storage capacitance or increasing process steps and costs.
Innovation Solution
A pixel circuit structure is designed with a metal light shielding layer electrically coupled to both the power line and display data line through via-holes, reducing resistance and IR drops while increasing storage capacitance, allowing for stable current control without additional metal layers or process changes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the pixel size is reduced to increase PPI, then the display resolution is improved, but the RC load increases and storage capacitance is sacrificed
Solution Approach 1:
The metal light shielding layer is designed to serve dual functions: (1) blocking light in the display area to prevent light leakage and improve display quality, and (2) acting as an extension of the power line to reduce resistive voltage drops. This multi-functionality allows the same structure to address both light shielding and electrical performance issues without occupying additional pixel area, thereby maintaining storage capacitance while improving display resolution.
Solution Approach 2:
The invention merges the light shielding function and the power line extension function into a single metal layer structure. By combining these two functions that were previously performed by separate structures, the design reduces the overall RC load without sacrificing storage capacitance, enabling high PPI display while maintaining electrical performance.
2Reliability
If additional metal layers are added to reduce resistance load, then the resistive voltage drop is reduced, but the process steps and product costs increase
Solution Approach 1:
The existing metal light shielding layer, which is already part of the OLED structure, is repurposed to also function as a power line extension. This eliminates the need for additional metal layers dedicated to reducing resistance, as the light shielding layer itself is utilized to provide low-resistance current paths, thereby reducing process steps and costs.
Solution Approach 2:
The metal light shielding layer serves itself by performing both its original light-blocking function and an additional electrical function. By making it electrically connected to the power line, the structure provides its own resistance reduction capability without requiring external additional layers or complex modifications to the manufacturing process.
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 reduces the resistance and IR drops in both power and data lines, increases storage capacitance, and enables stable current control for improved display performance in high-PPI OLED panels without increasing costs or process complexity.
Implementation Method 1
the metal light shielding layer is electrically coupled to the power line of the thin film transistor
Implementation Method 2
a second gate formed on the insulating layer, forming a storage capacitance with the gate
Data Source
AI summary
The present disclosure provides a pixel circuit structure and a display device using the same. The pixel circuit structure includes: a metal light shielding layer; at least one buffer layer formed on the metal light shielding layer; a thin film transistor formed on the at least one buffer layer; an insulating layer formed on a gate of the thin film transistor; and a second gate, formed on the insulating layer, forming a storage capacitance with the gate, and electrically coupled to a power line of the thin film transistor, wherein the metal light shielding layer is electrically coupled to the power line of the thin film transistor.