OLED Pixel Driving Transistor Initialization for Brightness Uniformity
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Solution Overview
Problem
Organic light emitting displays face issues with non-uniform brightness and motion blur due to the characteristics of driving transistors, which affect the quality of moving images.
Innovation Solution
The implementation of a pixel structure that includes specific transistors and a storage capacitor, along with a method of applying a bias voltage for at least 560 μs, to control current flow and improve optical response characteristics, thereby reducing motion blur and ghosting.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional driving transistor control is used, then the display can operate, but brightness uniformity deteriorates and motion blur occurs
Solution Approach 1:
The patent applies preliminary action by initializing the driving transistor before the display frame starts. A reset signal is applied to the reset line prior to the scan signal, which applies bias voltage to the gate electrode of the driving transistor in advance. This preliminary initialization ensures uniform threshold voltage across all pixels before image display begins, preventing brightness non-uniformity and motion blur without requiring complex real-time control mechanisms during operation.
2Reliability
If bias voltage is applied for sufficient duration (≥560 μs), then transistor initialization improves and brightness uniformity increases, but time consumption increases
Solution Approach 1:
The patent optimizes the parameter of bias voltage application time to be at least 560 μs. This specific time duration was determined to be the minimum required to properly initialize the driving transistor and achieve uniform brightness across the display. By setting this precise parameter, the patent balances sufficient initialization time with efficient operation, avoiding excessive time consumption while ensuring reliable brightness uniformity.
3Reliability
If multiple transistors and storage capacitor are added to control current flow, then picture quality improves and motion blur reduces, but device complexity increases
Solution Approach 1:
The patent employs multiple transistors (first transistor for current control, second transistor for bias voltage control, third transistor for data signal control) and a storage capacitor that serve multiple functions within the pixel structure. The first transistor controls current to the OLED, the second transistor manages bias voltage application for initialization, the third transistor handles data signal input, and the storage capacitor maintains gate voltage. This multi-functional design improves picture quality and reduces motion blur while minimizing the increase in device complexity by having each component perform specific, essential roles.
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 ensures uniform brightness and improved picture quality by initializing the driving transistors, reducing motion blur and ghosting in moving images.
Implementation Method 1
organic light emitting displays display images using organic light emitting diodes (OLEDs) that generate light by re-combination of electrons and holes
Data Source
AI summary
A pixel capable of displaying an image with uniform brightness. The pixel includes an organic light emitting diode (OLED), a first transistor for controlling an amount of current that flows from a first power source to a second power source via the OLED, and a second transistor coupled between a gate electrode of the first transistor and a bias power source, and configured to be turned on when a reset signal is supplied to a reset line, wherein a turn on time of the second transistor is configured to apply the bias power source to the gate electrode of the first transistor for at least 560 μs.