Polysilicon TFT Compensation Circuit for OLED Blurring
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Solution Overview
Problem
Organic light emitting devices (OLEDs) using amorphous silicon TFTs face challenges with low electron mobility, short lifespan, and blurring due to threshold voltage deviations, which affect image quality and reliability.
Innovation Solution
A display device with a polysilicon TFT-based structure, including a compensation circuit and specific transistor configurations to manage voltage and current, reducing blurring and maintaining transistor reliability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If amorphous silicon TFT is used in OLED, then low temperature deposition is achieved, but electron mobility is low and lifespan is short
Solution Approach 1:
The patent changes the material parameter from amorphous silicon to polysilicon, which fundamentally alters the electron mobility and threshold voltage characteristics. This material parameter change enables both acceptable deposition temperatures and improved device reliability with longer lifespan.
Solution Approach 2:
The patent introduces a compensation circuit that can compensate for threshold voltage deviations, effectively extending the operational life of the OLED by compensating for degradation effects, thus addressing the short lifespan issue.
2Temperature
If amorphous silicon TFT is used in OLED, then low temperature deposition is achieved, but threshold voltage deviation causes blurring
Solution Approach 1:
The patent implements a compensation circuit that measures and compensates for threshold voltage deviations in real-time, providing feedback control that maintains image clarity and prevents blurring caused by voltage instability.
Solution Approach 2:
The patent changes from amorphous silicon to polysilicon material, which provides more stable threshold voltage characteristics and reduces the blurring effect, thereby improving manufacturing precision and image quality.
3Reliability
If polysilicon TFT is used in OLED, then electron mobility and lifespan are improved, but laser shot mark causes threshold voltage deviation
Solution Approach 1:
The patent employs a compensation circuit that detects and compensates for threshold voltage deviations caused by laser shot marks during polysilicon crystallization, maintaining uniformity across the display panel despite manufacturing variations.
Solution Approach 2:
The patent performs preliminary compensation by designing the circuit to anticipate and correct for threshold voltage deviations before they significantly impact display uniformity, ensuring consistent performance across all pixels.
4Duration of action of stationary object
If hold type display method is used, then image is sustained for one frame, but blurring phenomenon occurs during motion
Solution Approach 1:
The patent applies periodic action by using impulse driving method where images are displayed only during specific time intervals (active periods) within each frame, with black periods in between, reducing the sustain time that causes motion blurring while maintaining acceptable image display.
Data Source
AI summary
The present invention provides a display device and a method of driving the same. The display device includes: a light-emitting device; a first capacitor connected between a first contact point and a second contact point; a driving transistor including an input terminal connected to a first voltage, an output terminal, and a control terminal connected to the second contact point; a first switching transistor controlled by a first control signal and connected between a data voltage and the first contact point; a second switching transistor controlled by a second control signal and connected between a second voltage and the first contact point; a third switching transistor controlled by a third control signal and connected between the second contact point and the second voltage; a fourth switching transistor controlled by the first control signal and connected between the second contact point and the output terminal of the driving transistor; and a fifth switching transistor controlled by the second control signal and connected between the light-emitting device and the output terminal of the driving transistor.