6T2C Pixel Circuit for Leakage-Current Compensation
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Solution Overview
Problem
Leakage currents in pixel driving circuits of display devices lead to fluctuations in current flow through light emitting elements, degrading display quality.
Innovation Solution
A pixel structure with a 6T2C configuration, including specific transistors and capacitors, is designed to stabilize current flow by using compensation and initialization signals to maintain consistent voltage levels, reducing the impact of transistor threshold voltage and power source variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a conventional pixel driving circuit is used, then the device complexity is low, but leakage current causes current fluctuation and degrades display quality
Solution Approach 1:
The pixel circuit performs preliminary initialization by applying an initialization scan signal to set the gate voltage of the first transistor to a reference voltage level before the main data signal is applied. This preliminary action compensates for threshold voltage variations and ensures consistent starting conditions, preventing current fluctuations during operation
Solution Approach 2:
The pixel circuit uses a compensation scan signal that provides feedback about the actual threshold voltage conditions of the transistor. By monitoring and adjusting the gate voltage based on this feedback, the circuit compensates for leakage current effects and maintains stable current flow through the light emitting element
2Manufacturing precision
If transistor threshold voltage varies, then manufacturing tolerance is improved, but current stability deteriorates
Solution Approach 1:
The pixel circuit dynamically changes the gate voltage parameter of the first transistor based on the applied scan signals. By adjusting the gate voltage in response to initialization and compensation scan signals, the circuit compensates for threshold voltage variations and maintains stable current flow despite manufacturing tolerances
Solution Approach 2:
The gate electrode acts as an intermediary control element that mediates between the input data signal and the current flow through the light emitting element. By controlling the gate voltage through the transistor gates, the circuit stabilizes the current despite variations in transistor threshold voltage
3Adaptability or versatility
If power source voltage fluctuates, then power supply flexibility is improved, but luminance stability deteriorates
Solution Approach 1:
The compensation scan signal provides feedback about power source conditions and transistor states. By using this feedback to adjust the gate voltage, the circuit compensates for power source fluctuations and maintains consistent luminance output despite voltage variations
Data Source
AI summary
A pixel includes a light emitting element connected between a first power source line, through which a first power source is provided, and a first node, a first transistor including a first electrode electrically connected to the first node, a second electrode electrically connected to a second node, and a gate electrode electrically connected to a third node, a second transistor including a first electrode electrically connected to a data line through which a data signal is provided, a second electrode electrically connected to the third node, and a gate electrode for receiving a scan signal, a third transistor, a fourth transistor, and a first capacitor connected between the second node and the third node.