Pixel Driving Circuit With Threshold Compensation for Flicker Stability
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Solution Overview
Problem
All-oxide driving transistors in pixel driving circuits are sensitive to environmental factors like light, water, and oxygen, leading to unstable threshold voltages and flickering in light-emitting devices.
Innovation Solution
A pixel driving circuit with a driving transistor, data writing sub-circuit, threshold compensation sub-circuit, and light-emitting control sub-circuit, including capacitors and switching transistors, to stabilize the threshold voltage and improve light emission stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If all-oxide driving transistors are used in pixel driving circuits, then the transistor can be manufactured with good uniformity and low cost, but the threshold voltage becomes unstable due to sensitivity to light, water, and oxygen, causing flickering in light-emitting devices
Solution Approach 1:
The patent applies preliminary action by measuring and compensating for the threshold voltage of the driving transistor before the light-emitting phase. The threshold compensation sub-circuit measures the threshold voltage during the initialization phase and stores the compensation value in a capacitor, so that when the light-emitting phase begins, the gate of the driving transistor already has the pre-compensated voltage to counteract threshold voltage drift, preventing flickering before it occurs.
2Reliability
If threshold voltage compensation is implemented to stabilize light emission, then light emission stability is improved, but the circuit complexity increases due to additional sub-circuits
Solution Approach 1:
The patent merges multiple functions into the driving transistor and associated sub-circuits. The driving transistor serves as both the switching element and the measurement object for threshold voltage compensation. The threshold compensation sub-circuit is integrated with the driving transistor's gate control, and the data writing sub-circuit shares control signals with other circuit parts. This merging reduces the need for completely separate compensation circuits while achieving stable light emission.
Solution Approach 2:
The patent implements multi-functionality where the same sub-circuits serve multiple purposes during different phases of operation. The threshold compensation sub-circuit not only compensates for threshold voltage but also participates in the initialization and data writing processes. The data writing sub-circuit writes both display data and compensation data using the same control signals. The driving transistor is involved in both threshold measurement and current driving functions, reducing overall circuit complexity while maintaining stability.
Data Source
AI summary
A pixel driving circuit, a display device, and a driving method. The pixel driving circuit includes: a driving transistor (DT), configured to generate a drive current based on a threshold voltage of the driving transistor (DT) and a data voltage; a data writing sub-circuit (001), coupled to a gate of the driving transistor (DT), and configured to, in response to a signal at a scanning signal terminal (Gate), input a data voltage from a data signal terminal (Vdata) into the gate of the driving transistor (DT); a threshold compensation sub-circuit (002), coupled to the driving transistor (DT), and configured to provide a threshold voltage of the driving transistor (DT) to the gate of the driving transistor (DT) in response to a signal at the compensation signal terminal (CM); and a first light-emitting control sub-circuit (003), coupled to the driving transistor (DT).