Pixel Circuit Layout for Threshold Compensation in High-Resolution Displays
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Solution Overview
Problem
Existing pixel circuits driven by 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 constraints.
Innovation Solution
A pixel circuit design incorporating fewer transistors and capacitors, utilizing a novel configuration of eleven transistors and two capacitors, enabling internal threshold voltage compensation and suitable for ultra-high resolution displays.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a pixel circuit includes nineteen or more transistors and three or more capacitors to achieve pulse width modulation and internal threshold voltage compensation, then the circuit can perform required functions, but the circuit cannot be integrated into ultra-high resolution display apparatuses due to integration limitations
Solution Approach 1:
The patent combines multiple transistor functions into a unified structure where the sixth transistor serves dual purposes: it acts as a switch during the light emission period and as part of the initialization circuit during the initialization period. This merging of functions reduces the total transistor count from nineteen or more to eleven transistors while preserving pulse width modulation capability and threshold voltage compensation.
Solution Approach 2:
The patent employs dynamic control of transistor states through timing signals. The sixth transistor is dynamically switched between different operational modes based on the initialization gate signal and emission gate signal. During initialization, it participates in voltage compensation, while during light emission, it functions as a switch, allowing a single transistor to perform multiple roles at different times.
2Device complexity
If the pixel circuit includes fewer transistors to achieve high integration, then integration into ultra-high resolution display apparatuses becomes possible, but the circuit must maintain effective internal threshold voltage compensation and pulse width modulation operation
Solution Approach 1:
The patent implements threshold voltage compensation through a feedback mechanism involving the third and sixth transistors. During the initialization period, these transistors create a feedback path that compensates for threshold voltage shifts in the first transistor. This feedback mechanism ensures that even with fewer transistors, the circuit maintains accurate threshold voltage compensation necessary for reliable pulse width modulation operation.
Solution Approach 2:
The patent performs threshold voltage compensation as a preliminary action during the initialization period before the light emission period begins. By initializing the control electrode voltage of the first transistor to a reference voltage level during initialization, the circuit pre-compensates for threshold voltage effects, ensuring accurate operation during subsequent light emission without requiring additional transistors.
Data Source
AI summary
A pixel circuit includes a first transistor including a control electrode electrically connected to a first node, a first electrode electrically connected to a second node and a second electrode electrically connected to a third node, a second transistor configured to apply a first data voltage to the first transistor, a third transistor electrically connected to the first node and the third node, a fourth transistor including a control electrode electrically connected to a fourth node, a first electrode electrically connected to a fifth node and a second electrode electrically connected to a sixth node, a fifth transistor configured to apply a second data voltage to the fourth transistor, a sixth transistor electrically connected to the fourth node and the sixth node and a light emitting element that emits light based on the first data voltage and the second data voltage.