Pixel Circuit Leakage Current Stabilization
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Solution Overview
Problem
In display devices, off leakage current at switching transistors can cause variations in pixel brightness and flicker phenomena due to voltage variations, which existing technologies have not adequately addressed, leading to image quality deterioration.
Innovation Solution
A pixel circuit design that includes a data storage capacitor, switch transistors, and connection transistors, where the connection transistors are turned off during the turn-on period of switch transistors and turned on after they are turned off, with nodes connected to a reference power supply voltage to control leakage current and stabilize the voltage applied to the driving transistor.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If switch transistors are used to control data signal lines, then gray scale data can be written to pixels, but off leakage current causes voltage variation and brightness variation
Solution Approach 1:
A connection transistor is introduced as an intermediary component between adjacent pixels. This transistor mediates the leakage current effect by providing a controlled current path that compensates for the off leakage current in switch transistors, thereby stabilizing the gate voltage of driving transistors and preventing brightness variation while maintaining gray scale data writing functionality.
2Reliability
If connection transistors are added to reduce leakage current, then pixel brightness stability improves, but device complexity increases
Solution Approach 1:
The connection transistor is merged with the existing pixel circuit structure, sharing control signals and physical layout with adjacent pixels. By combining the leakage compensation function with the existing switch transistor architecture, the overall device complexity is minimized while still achieving improved pixel brightness stability.
3Productivity
If switch transistors are turned on to supply data, then data storage capacitor can be charged, but leakage current flows during off period causing voltage drift
Solution Approach 1:
The connection transistor operates periodically, being turned on during the off period of switch transistors to compensate for leakage current, and turned off during the on period to avoid interfering with data writing. This periodic operation maintains gate voltage stability during data retention while allowing normal data transmission functionality.
Solution Approach 2:
The connection transistor provides a feedback mechanism where the leakage current from switch transistors is sensed and compensated by the connection transistor. This feedback loop continuously adjusts the current path to maintain stable gate voltage in the data storage capacitor, preventing voltage drift during the off period.
Data Source
AI summary
A pixel circuit includes a plurality of pixels. Each pixel includes a data storage capacitor to store a voltage for controlling a gray scale value based on an input data signal, a plurality of switch transistors connected in series between a data signal line and the data storage capacitor, and a plurality of connection transistors coupled to the pixels. The switch transistors have a gate electrode connected to a first gate control signal line. At least one connection transistor is connected between at least one node between the switch transistors of a first pixel and at least one node between the switch transistors of a second pixel adjacent to the first pixel. The at least one connection transistor includes a gate electrode connected to a second gate control signal line.