Pixel Circuit Feedback Compensation for Display Uniformity
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Solution Overview
Problem
Conventional display panels suffer from non-uniformity due to the clock feedthrough effect caused by parasitic capacitors and transverse capacitors and resistors, leading to signal delays and voltage differences across the panel, which affect display uniformity.
Innovation Solution
A pixel circuit design incorporating a first and second thin film transistor (TFT), a first and second capacitor, and a lighting device, where the feedback compensation signal and control signal have the same phase but different directions, with the second capacitor compensating for voltage drops caused by parasitic capacitance, and an optional third TFT for threshold voltage compensation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a conventional 2T1C pixel driving circuit is used, then the circuit structure is simple, but the display uniformity deteriorates due to clock feedthrough effect and signal delays
Solution Approach 1:
The patent introduces a feedback compensation mechanism where the compensation capacitor Cfg connects the gate of the driving TFT to the data writing node. This feedback path compensates for the clock feedthrough effect by providing a reverse charge transfer path, thereby canceling out the unwanted voltage changes caused by parasitic capacitance and improving display uniformity
Solution Approach 2:
The patent introduces a compensation capacitor Cfg as an intermediary element between the gate of the driving TFT and the data writing node. This intermediary component mediates the charge transfer process, compensating for signal delays and voltage drops caused by parasitic capacitance, thus improving display uniformity without significantly increasing circuit complexity
2Manufacturing precision
If parasitic capacitor compensation is implemented, then display uniformity improves, but circuit complexity increases
Solution Approach 1:
The compensation capacitor Cfg serves multiple functions: it compensates for clock feedthrough effect, corrects signal delays, and maintains gate voltage stability. By making this single component multi-functional, the patent achieves improved display uniformity without proportionally increasing circuit complexity
Solution Approach 2:
The patent optimizes the capacitance value of Cfg to achieve effective compensation. By carefully selecting the parameter (capacitance value) of the compensation capacitor, the circuit achieves optimal compensation效果 with minimal additional complexity, balancing performance improvement and circuit simplicity
Data Source
AI summary
A display panel, a display panel and a pixel circuit are proposed. The pixel circuit includes a first TFT, a second TFT, a first capacitor, a second capacitor, and a lighting device. The feedback compensation signal and the first control signal have a same phase but different directions. The second TFT includes a gate receiving a first control signal, a source receiving a data signal, and a drain electrically connected to the first node. The second capacitor includes a first end electrically receiving a feedback compensation signal and a second end electrically connected the first node. The feedback compensation signal has the same phase but different direction of the first control signal. This could realize the self-compensation mechanism of the pixel circuit and thus solve the non-uniformity issue of the conventional display panel and display device.