Display Pixel Circuit Bias Adjustment for Threshold Drift
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Solution Overview
Problem
Existing display panels face issues with threshold voltage drift in drive transistors over time, affecting display uniformity due to slow changes in internal characteristics, leading to unsatisfactory performance.
Innovation Solution
Incorporating a bias adjustment device in the pixel circuit that provides a bias adjustment signal to the drive transistor, either by connecting it between the source and drain for PMOS transistors or between the initialization signal line and the light-emitting element for NMOS transistors, to adjust the potential difference between the gate and drain, thereby compensating for threshold voltage drift.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If no bias adjustment device is used, then the device complexity is low, but the threshold voltage drift occurs affecting display uniformity
Solution Approach 1:
A bias adjustment device is introduced as an intermediary component in the pixel circuit. This device receives a bias adjustment signal and applies it to the drive transistor, mediating the effect of threshold voltage drift by adjusting the gate-drain potential difference. The intermediary device enables compensation without fundamentally changing the core display functionality.
Solution Approach 2:
The bias adjustment device changes the electrical parameters of the drive transistor by applying an adjustable bias signal. By modifying the gate-drain potential difference through this signal, the effective threshold voltage of the transistor is adjusted to compensate for drift, thereby maintaining display uniformity over time.
2Reliability
If bias adjustment signal voltage is increased to compensate for threshold voltage drift, then the threshold voltage stability improves, but the power consumption increases
Solution Approach 1:
The bias adjustment device applies only the necessary amount of bias signal required to compensate for threshold voltage drift, rather than continuously applying maximum voltage. This partial action approach achieves the needed stabilization while avoiding excessive power consumption that would result from continuously high voltage application.
Data Source
AI summary
A display panel includes a pixel circuit and a light-emitting element. The pixel circuit includes a data write device, a drive device, and a bias adjustment device. The drive device includes a drive transistor. The data write device is configured to provide a data signal for the drive device. The bias adjustment device is configured to provide a bias adjustment signal to the drive device. The pixel circuit includes a first light-emitting control device, the first light-emitting control device is connected between a first power supply voltage signal line and the drive device, and the first power supply voltage signal line is configured to provide a high-level signal, or, the pixel circuit includes an initialization device, the initialization device is connected between an initialization signal line and the light-emitting element, and the initialization signal line is configured to provide a low-level signal.