Pixel Circuit Layout for Writing Data Voltage Without Capacitance Distribution
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Solution Overview
Problem
Process deviations of capacitors in display panels affect display quality due to capacitance distribution during data voltage writing.
Innovation Solution
A pixel design incorporating four transistors and two capacitors, where data voltage is written without capacitance distribution, reducing the influence of process deviations and enhancing display quality.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If data voltage is written using conventional capacitor-based storage, then the pixel can maintain the voltage, but process deviations of capacitors affect display quality due to capacitance distribution
Solution Approach 1:
The patent extracts the data voltage writing function from the capacitor storage mechanism. Instead of relying on capacitor charge distribution to maintain data voltage, the invention uses a dedicated write transistor (WT) that directly writes data voltage to the storage node, eliminating the harmful capacitance distribution effect while maintaining voltage storage capability.
Solution Approach 2:
The storage node serves multiple functions: it stores data voltage during the writing phase and maintains the voltage during the display phase. The write transistor and emission transistor work together to enable both writing and emission functions through the same storage node, reducing the need for separate components and minimizing process deviation impacts.
2Reliability
If more transistors and capacitors are added to compensate for process deviations, then display quality improves, but device complexity and manufacturing cost increase
Solution Approach 1:
The patent applies preliminary action by pre-charging the storage node to a reference voltage level before data writing. The write transistor then adjusts this pre-charged voltage to the correct data voltage level, ensuring accurate voltage storage without requiring additional compensating components that would increase device complexity.
3Ease of manufacture
If conventional pixel design with capacitance distribution is used, then manufacturing is simpler, but display quality is degraded due to process deviations
Solution Approach 1:
The storage node acts as an intermediary between the data input and the light emitting element. It receives data voltage through the write transistor, maintains this voltage independently of capacitor process deviations, and provides stable voltage to the light emitting element through the emission transistor, thereby improving display quality while maintaining manufacturing simplicity.
Data Source
AI summary
A pixel includes a light emitting element, a first transistor, a second transistor, a third transistor, and a fourth transistor. The first transistor includes a control electrode connected to a first node, a first electrode connected to a second node, and a second electrode connected to an anode electrode of the light emitting element. The second transistor includes a control electrode to receive a first gate signal, a first electrode to receive a data voltage, and a second electrode connected to the second node. The third transistor includes a control electrode to receive a second gate signal, a first electrode connected to the first node, and a second electrode connected to the anode electrode of the light emitting element. The fourth transistor includes a control electrode to receive an emission signal, a first electrode to receive a first power voltage, and a second electrode connected to the second node.