OLED Compensation Transistor Leakage Current Management
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Solution Overview
Problem
Organic light emitting diode (OLED) displays face issues with grayscale spots due to the compensation transistor's threshold voltage compensation, which is either too slow when the driving semiconductor layer is long, leading to low grayscale compensation, or causes spots when it's short, resulting in increased current and leakage.
Innovation Solution
The OLED display incorporates a compensation transistor with a split compensation semiconductor layer and an aging transistor to quickly compensate the threshold voltage, using a short pass diode structure and overlapping gate electrodes to manage current flow and reduce leakage, along with a storage capacitor and boosting capacitor for voltage management.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If the driving semiconductor layer length is shortened to enable quick threshold voltage compensation, then compensation speed is improved, but leakage current increases causing spots
Solution Approach 1:
The semiconductor layer is divided into multiple segments with different lengths. The first semiconductor layer has a first length optimized for quick compensation, while the second semiconductor layer has a second length optimized for reducing leakage current. This segmentation allows each segment to perform its specific function effectively.
Solution Approach 2:
Different portions of the semiconductor layer are given different properties (different lengths) to serve different functions. The first segment provides fast compensation response, while the second segment provides low leakage current, creating local optimization throughout the structure.
2Object-generated harmful factors
If the driving semiconductor layer length is lengthened to reduce leakage current, then harmful factors are reduced, but compensation speed decreases
Solution Approach 1:
The semiconductor layer is divided into multiple segments with different lengths. The first semiconductor layer has a first length optimized for quick compensation, while the second semiconductor layer has a second length optimized for reducing leakage current. This segmentation allows each segment to perform its specific function effectively.
Solution Approach 2:
Different portions of the semiconductor layer are given different properties (different lengths) to serve different functions. The first segment provides fast compensation response, while the second segment provides low leakage current, creating local optimization throughout the structure.
3Object-generated harmful factors
If the compensation transistor threshold voltage is reduced to prevent spots, then leakage current is reduced, but compensation effectiveness may be compromised
Solution Approach 1:
The threshold voltage of the compensation transistor is specifically adjusted to a predetermined value that balances two competing requirements: it must be low enough to prevent leakage current and spots, but high enough to ensure effective threshold voltage compensation. This optimized parameter setting resolves the contradiction between preventing harmful effects and maintaining functional reliability.
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 effectively prevents grayscale spots by quickly compensating the threshold voltage and reducing leakage current, ensuring stable and accurate grayscale representation while minimizing current deviations and operational stains.
Implementation Method 1
Electrons injected from one electrode and holes injected from the other electrode are combined in the organic emission layer. As such, excitons are formed and light is emitted by energy generated from the excitons.
Data Source
AI summary
An organic light emitting diode (OLED) display is provided. One inventive aspect includes: a substrate, a scan line formed on the substrate and transmitting a scan signal, a data line configured to intersect the scan line and to transmit a data signal, a switching transistor connected to the scan line and the data line, a driving transistor connected to a switching drain electrode of the switching transistor, a compensation transistor connected to the driving transistor, an aging transistor connected to a driving drain electrode of the driving transistor and a source electrode of the compensation transistor, and an organic light emitting diode (OLED) connected to a driving drain electrode of the driving transistor. The compensation transistor is configured to compensate a threshold voltage of the driving transistor. The aging transistor is configured to perform an aging process for reducing a leakage current of the compensation transistor.