OLED Pixel Drive Circuit Using Mixed-Mobility Transistors
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Solution Overview
Problem
The miniaturization of drive circuits in organic electroluminescence display apparatuses poses a challenge as it leads to decreased luminance and impaired screen uniformity due to substrate bias effects and excessive mobility correction, making it difficult to achieve both higher definition and enhanced display performance.
Innovation Solution
The use of transistors with different carrier mobilities, specifically a MOS transistor as the video signal writing transistor and a thin-film transistor as the drive transistor, configured in a manner that avoids substrate bias effects and excessive mobility correction, allowing for higher definition and improved screen uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the drive circuit is miniaturized to achieve higher definition, then the pixel density and resolution are improved, but the luminance and screen uniformity deteriorate due to substrate bias effects and excessive mobility correction
Solution Approach 1:
The patent changes the material parameter of the transistor from conventional silicon-based to oxide semiconductor, which fundamentally alters the electrical characteristics and eliminates substrate bias effects. This material parameter change enables miniaturized drive circuits to maintain both high luminance and excellent screen uniformity by preventing the degradation mechanisms that occur in traditional transistors.
Solution Approach 2:
The patent applies different transistor types in different locations: oxide semiconductor transistors are used specifically in the drive circuit region where miniaturization occurs, while other regions can use conventional transistors. This localized application of specialized materials allows the drive circuit to achieve high definition without suffering from the luminance deterioration and uniformity issues that would affect the entire display.
2Measurement precision
If the drive circuit is miniaturized to achieve higher definition, then the pixel density is improved, but the screen uniformity deteriorates due to substrate bias effects
Solution Approach 1:
The patent changes the transistor material parameter to oxide semiconductor, which has fundamentally different electrical properties that eliminate substrate bias effects. This parameter change ensures that even in miniaturized drive circuits, the screen maintains excellent uniformity by preventing the electrical instability that causes composition variations in traditional transistor designs.
Solution Approach 2:
The oxide semiconductor transistor acts as a stable, long-lasting component that maintains consistent electrical characteristics over time and across different pixels. This reliability ensures that screen uniformity is maintained throughout the display's operational life, even as the drive circuit is miniaturized for higher definition.
3Area of stationary object
If conventional transistors are used in miniaturized drive circuits, then the circuit size is reduced, but excessive mobility correction occurs leading to performance degradation
Solution Approach 1:
The patent changes the transistor material from conventional silicon-based to oxide semiconductor, which has superior electrical characteristics including higher carrier mobility and better stability. This parameter change allows the drive circuit to be miniaturized while maintaining excellent signal quality and avoiding excessive mobility correction, as the oxide semiconductor inherently provides more stable electrical performance at smaller dimensions.
Data Source
AI summary
[Object] To provide a display apparatus that can achieve enhancement in display performance of a screen and higher definition.[Solution] There is provided a display apparatus. The drive circuit includes a drive transistor configured to control the light emitting unit, a video signal writing transistor configured to control writing of a video signal, and a capacitative element. In the drive transistor, one source/drain region is connected to a current supply line, another source/drain region is connected to the light emitting unit and a first node of the capacitative element, and a gate electrode is connected to a second node of the capacitative element. In the video signal writing transistor, one source/drain region is connected to a data line, another source/drain region is connected to the gate electrode of the drive transistor and the second node of the capacitative element, and a gate electrode is connected to a scanning line. The drive transistor and the video signal writing transistor are different in carrier mobility.