Pixel Structure Threshold Voltage Compensation
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Solution Overview
Problem
In flat-panel displays, driving transistors in different pixels can have varying threshold voltages due to manufacturing variations, leading to inconsistent driving currents and brightness when receiving the same image signal.
Innovation Solution
A pixel structure comprising a first switching transistor, a setting unit, a capacitor, a driving transistor, and a second switching transistor, where the setting unit controls voltage levels to isolate the threshold voltage effect, allowing the driving current to be independent of the driving transistor's threshold voltage, ensuring consistent brightness across pixels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If traditional pixel structures with simple driving transistors are used, then device complexity is reduced, but brightness consistency deteriorates due to threshold voltage variations
Solution Approach 1:
The pixel structure is segmented into multiple functional units: a driving transistor for current generation, a setting unit for threshold voltage compensation, and a voltage control unit for timing control. Each unit performs a specific function to collectively solve the brightness consistency problem while maintaining manageable complexity
Solution Approach 2:
A setting unit is introduced as an intermediary component between the driving transistor and the luminous element. This setting unit generates a setting signal that compensates for threshold voltage variations, acting as a mediator to ensure consistent driving currents despite transistor variations
2Reliability
If driving transistors with identical threshold voltages are achieved through precise manufacturing, then brightness consistency is improved, but manufacturing precision requirements increase
Solution Approach 1:
The setting unit operates based on feedback from the scan signal and discharging signal to dynamically adjust the gate voltage of the driving transistor. This feedback mechanism compensates for threshold voltage variations without requiring precise manufacturing control
Solution Approach 2:
The setting unit changes the gate voltage parameter of the driving transistor dynamically during operation. By adjusting this parameter based on the setting signal, the system compensates for threshold voltage variations and ensures consistent driving currents
3Reliability
If the setting unit controls voltage levels to compensate for threshold voltage effects, then brightness consistency is improved, but device complexity increases
Solution Approach 1:
The setting unit combines multiple functions: it receives the scan signal, generates the setting signal, and controls the driving transistor's gate voltage. By merging these functions into a single unit, the patent reduces overall circuit complexity while maintaining brightness consistency
4Measurement precision
If the first switching transistor transmits data signal during the second period, then gray level control is improved, but power consumption increases
Solution Approach 1:
The first switching transistor operates periodically, transmitting the data signal only during the second period when needed for gray level updating. During other periods, it remains inactive, reducing power consumption while maintaining precise gray level control when required
Data Source
AI summary
A pixel structure including a first switching transistor, a setting unit, a capacitor, a driving transistor, a second switching transistor and a luminous element is disclosed. The capacitor is coupled between a first and a second node. The first switching transistor transmits a data signal to the first node according to a scan signal. The driving transistor includes a threshold voltage and a gate coupled to the second node. The second switching transistor includes a gate receiving an emitting signal. The luminous element is coupled to the driving transistor and the second switching transistor in series between a first operation voltage and a second operation voltage. The setting unit controls the voltage levels of the first and the second nodes to compensate the threshold voltage of the driving transistor.