OLED Display Driving Transistor Gate Voltage Control
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Solution Overview
Problem
High-resolution organic light emitting diode (OLED) displays face challenges in controlling the magnitude of gate voltage due to reduced current per pixel, making it difficult to achieve rich grays and maintain sufficient storage capacitance.
Innovation Solution
The design includes a substrate with a semiconductor layer, gate insulating layers, data wires, and dummy contact holes to increase the driving range of the driving thin film transistor, and a curved driving semiconductor layer to enhance gate voltage control, while minimizing peripheral contact holes for improved charge mobility and storage capacitance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the resolution of the display is increased, then the display quality is improved, but the current amount flowing per pixel is decreased making it difficult to control gate voltage magnitude
Solution Approach 1:
The pixel structure is segmented into multiple functional regions including display region, charge transfer region, and charge storage region. The data line is divided into data signal line and driving voltage line. This segmentation allows independent optimization of each region to maintain gate voltage control capability while achieving high resolution display.
Solution Approach 2:
The invention introduces a new spatial dimension by adding the charge transfer region and charge storage region adjacent to the display region. This dimensional expansion provides additional space for charge management without increasing the pixel area, thereby maintaining resolution while improving voltage control.
2Measurement precision
If the pixel size is decreased to increase resolution, then the display quality is improved, but the driving range of gate voltage is narrowed
Solution Approach 1:
Charge is preliminarily stored in the charge storage region before the emission period. The driving transistor receives both data signal and driving voltage through separate lines, allowing preliminary setup of the driving conditions. This preliminary action expands the effective driving range despite reduced pixel size.
Solution Approach 2:
The charge transfer region acts as an intermediary between the data line and the organic light emitting diode. It facilitates charge transfer and provides additional control nodes that expand the driving range, enabling the system to overcome the limitations imposed by reduced pixel dimensions.
3Reliability
If the number of contact holes is reduced for peripheral transistors, then charge mobility is improved, but the structural complexity increases
Solution Approach 1:
Different regions of the device are assigned different structural characteristics. Peripheral transistors have fewer contact holes (2-4 holes) optimized for charge mobility, while the display region maintains the full structure for functionality. This local differentiation allows optimization of charge mobility in peripheral regions without compromising display performance.
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 configuration allows for more accurate control of gray levels and increased resolution, enhancing the display quality and maintaining sufficient storage capacitance even at high resolution.
Implementation Method 1
electrons injected from one electrode and holes injected from the other electrode are coupled with each other in the organic emission layer to generate excitons, and the excitons emit energy to emit light
Data Source
AI summary
An organic light emitting diode display includes: a substrate including a display area configured to display an image and a peripheral area surrounding the display area; a semiconductor layer at the display area on the substrate; a first gate insulating layer covering the semiconductor layer; a first gate wire on the first gate insulating layer; a second gate insulating layer covering the gate wire; a second gate wire on the second gate insulating layer; an interlayer insulating layer covering the second gate wire and having a contact hole, and a plurality of first dummy contact holes; a data wire on the interlayer insulating layer; a passivation layer covering the data wire; and an organic light emitting diode on the passivation layer and coupled to the data wire, wherein the data wire is coupled with the second gate wire through the contact hole in the interlayer insulating layer.