Pixel Circuit Current Writing for Threshold Compensation
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Solution Overview
Problem
Conventional pixel circuits driven in pulse width modulation with internal threshold voltage compensation require nineteen or more transistors and three or more capacitors, limiting their application to ultra-high resolution display apparatus due to integration challenges.
Innovation Solution
A pixel circuit design with fewer transistors, including a first and second circuit, utilizes current writing for internal or external compensation of the threshold voltage in a constant current generating circuit, suitable for ultra-high resolution displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional pixel circuits with internal threshold voltage compensation are used, then threshold voltage compensation is achieved, but the transistor count increases to nineteen or more
Solution Approach 1:
The patent extracts the threshold voltage compensation function from the conventional internal compensation circuit and implements it through external current writing. By separating the compensation mechanism from the pixel circuit itself and performing it externally, the design achieves threshold voltage compensation while reducing the transistor count to thirteen
Solution Approach 2:
The patent introduces a current writing mechanism as an intermediary to achieve threshold voltage compensation. Instead of using complex internal compensation circuits, the design uses external current writing to write compensation data to the pixel circuit, thereby achieving threshold voltage compensation with fewer transistors
2Device complexity
If pixel circuits with fewer transistors are used, then integration is improved, but threshold voltage compensation capability is reduced
Solution Approach 1:
The patent merges the threshold voltage compensation function with the data writing operation by using the same transistor structure for both purposes. The compensation is achieved by writing specific current values through the existing transistors, combining multiple functions into a unified circuit design that requires only thirteen transistors
Solution Approach 2:
The patent changes the operating parameters of the transistor circuit to achieve threshold voltage compensation. By adjusting the current writing values and timing parameters, the circuit compensates for threshold voltage variations without requiring additional transistors, maintaining reliability while reducing device complexity
3Reliability
If conventional pixel circuits are used, then threshold voltage compensation is achieved, but power consumption increases
Solution Approach 1:
The patent extracts the compensation function from continuous internal operation and implements it as periodic external current writing. This extraction allows the pixel circuit to consume power only when data is written or updated, rather than continuously maintaining compensation circuits, thereby reducing overall power consumption while preserving threshold voltage compensation capability
Data Source
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AI summary
A pixel circuit includes a first circuit including a seventh transistor connected to a fourth node, a fifth node and a sixth node, an eighth transistor for receiving a second writing-gate signal, and connected to the fifth node and the fourth node, a ninth transistor for receiving the second writing-gate signal and a data current and connected to the fifth node, a tenth transistor for receiving a second initialization-gate signal and a first initialization voltage and connected to a seventh node, an eleventh transistor for receiving an emission signal and a second power voltage and connected to the fifth node, a twelfth transistor connected to the seventh node and the fourth node and for receiving the second power voltage or a second initialization voltage, a thirteenth transistor for receiving an anode initialization-gate signal and the second initialization voltage and connected to the sixth node and a light emitting element.