Pixel Driving Circuit Threshold Voltage Drift Compensation
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Solution Overview
Problem
Existing pixel driving circuits experience threshold voltage drift due to bias stress, leading to nonuniform display brightness, ghosting, and flickering issues.
Innovation Solution
A pixel driving circuit with an initialization circuit that provides specific initialization and reset voltages to control the driving transistor, ensuring it operates in the saturation region to minimize hysteresis effects and threshold voltage drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the pixel driving circuit operates at a low frequency, then power consumption is reduced, but the threshold voltage of the driving transistor drifts severely due to bias stress
Solution Approach 1:
The patent applies preliminary action by performing threshold voltage compensation before the display frame is displayed. The compensation process includes: (1) resetting the driving transistor threshold voltage to an initial value before operation, and (2) compensating for threshold voltage drift during the pixel circuit operation phase. This preliminary and intermediate compensation approach ensures threshold voltage stability even when operating at low frequencies with reduced power consumption.
Solution Approach 2:
The patent implements feedback mechanisms through: (1) a sensing transistor that senses the threshold voltage of the driving transistor, (2) a compensation capacitor that stores compensation voltage, and (3) a compensation transistor that adjusts the driving transistor threshold voltage based on the sensed value. This closed-loop feedback system continuously monitors and corrects threshold voltage drift, maintaining reliability while operating at low power consumption frequencies.
2Loss of energy
If the pixel driving circuit operates at a low frequency, then refresh rate is reduced lowering power consumption, but display uniformity deteriorates due to threshold voltage drift
Solution Approach 1:
The patent performs preliminary threshold voltage compensation before each display frame is output. The compensation process includes resetting the driving transistor threshold voltage to an initial value and compensating for drift using sensing and compensation transistors. This preliminary action ensures that each frame starts with uniform threshold voltage across all pixels, maintaining display uniformity even at low refresh rates with reduced power consumption.
Solution Approach 2:
The patent uses feedback through sensing transistors that detect threshold voltage variations in each pixel, compensation capacitors that store correction voltages, and compensation transistors that apply corrections. This pixel-level feedback mechanism ensures uniform display brightness across the entire panel by compensating for threshold voltage drift in each individual pixel, maintaining manufacturing precision while operating at low power consumption frequencies.
3Loss of energy
If the pixel driving circuit operates at a low frequency, then power consumption is reduced, but hysteresis effect increases causing ghosting and flickering
Solution Approach 1:
The patent applies preliminary action by resetting the driving transistor threshold voltage to an initial value before each frame operation and compensating for threshold voltage drift during operation. This preliminary reset and continuous compensation prevents the accumulation of hysteresis effects that would otherwise cause ghosting and flickering, allowing the circuit to operate at low frequencies with reduced power consumption without suffering from severe hysteresis.
Solution Approach 2:
The patent implements feedback through sensing transistors that detect threshold voltage changes, compensation capacitors that store correction voltages, and compensation transistors that actively adjust the driving transistor threshold voltage. This real-time feedback mechanism counteracts hysteresis effects as they develop, preventing ghosting and flickering artifacts while enabling low-frequency operation with reduced power consumption.
Data Source
AI summary
A pixel driving circuit, a method for driving the same, and a display panel are provided. The pixel driving circuit includes a driving circuit (1) and an initialization circuit (2). The driving circuit (1) is connected to a first node (N1), a second node (N2), and a third node (N3). The initialization circuit (2) is connected to the first node (N1), the initialization circuit (2) is further connected to the second node (N2) and/or the third node (N3), and the initialization circuit (2) is configured to provide a first initialization voltage to the first node (N1), provide a first reset voltage to the second node (N2) and/or provide a second reset voltage to the third node (N3), so as to control a driving transistor (T3) in the driving circuit (1) to be turned on.