Dual-Gate Pixel Circuit for Threshold Voltage Compensation
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Solution Overview
Problem
Existing display devices face challenges in compensating for threshold voltage variations in driving transistors, which can lead to performance inconsistencies and inefficiencies, particularly due to capacitor coupling effects and polarity-dependent issues.
Innovation Solution
A pixel circuit design incorporating a first transistor, a light-emitting diode, a first capacitor, and a compensation circuit that samples and compensates for threshold voltage, utilizing a dual gate structure to ensure accurate driving current generation, regardless of polarity, with a sampling and writing period division for enhanced compensation capacity during high-speed operations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel circuit is used, then the device structure is simple, but the threshold voltage compensation capability is insufficient
Solution Approach 1:
The pixel circuit is divided into distinct functional modules: a driving transistor for current control, a compensation transistor for threshold voltage sampling, and a capacitor for voltage storage. This segmentation allows each component to perform its specific function independently, achieving reliable threshold voltage compensation while maintaining clear functional separation and manageable complexity.
Solution Approach 2:
The compensation circuit performs threshold voltage sampling and compensation in advance before the emission period. By measuring and compensating for threshold voltage variations beforehand, the system ensures accurate driving current generation during the emission period without requiring complex real-time adjustments.
2Reliability
If capacitor coupling effect is present, then the circuit can store charge, but performance inconsistencies occur due to polarity-dependent issues
Solution Approach 1:
The patent converts the harmful capacitor coupling effect into a beneficial feature by utilizing the capacitor's charge storage capability. The capacitor stores the compensated threshold voltage and maintains it during the emission period, ensuring consistent driving current while eliminating the harmful polarity-dependent coupling effects through proper circuit configuration.
Solution Approach 2:
The capacitor acts as an intermediary element between the compensation circuit and the driving transistor. It stores the compensated threshold voltage and provides it to the driving transistor during the emission period, mediating the voltage transfer and ensuring consistent performance regardless of polarity variations.
3Measurement precision
If threshold voltage compensation is implemented, then driving current accuracy improves, but the sensing period time increases
Solution Approach 1:
The compensation circuit performs threshold voltage sampling and compensation to the extent necessary for accurate driving current generation. By implementing compensation only for the critical threshold voltage parameter rather than all possible variations, the system achieves sufficient measurement precision while minimizing the sensing period duration.
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
The solution effectively compensates for threshold voltage variations, improving display performance by reducing capacitor coupling effects and ensuring consistent operation across different polarities, thereby enhancing the reliability and efficiency of the display device.
Implementation Method 1
a light emitting diode which includes an anode electrode connected to the second node and a cathode electrode which is configured to receive a low potential driving voltage, and emits light according to a driving current transmitted from the first transistor in an emission period
Implementation Method 2
a first capacitor connected between a second node and a third node
Implementation Method 3
a second capacitor connected between a second node and a fourth node
Data Source
AI summary
A pixel circuit includes a first transistor including a 1-1-th electrode connected to a first node, a 1-2-th electrode connected to a second node, a 1-1-th dual gate electrode connected to a third node, and a 1-2-th dual gate electrode connected to a fourth node. The pixel circuit further includes a light emitting diode including an anode electrode connected to the second node and a cathode electrode receiving a low potential driving voltage and emitting light according to a driving current transmitted from the first transistor in an emission period. The pixel circuit further includes: a first capacitor connected between the second node and the third node, and a compensation circuit which is connected to the first transistor to sample a threshold voltage of the first transistor to generate the driving current in which the threshold voltage is compensated, in a sensing period before the emission period.