Display Panel Bias Stage for Threshold Voltage Drift
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Solution Overview
Problem
In current display panels, the threshold voltage of driving transistors in pixel circuits drifts over time, affecting display uniformity due to changes in internal transistor characteristics, leading to issues with light-emitting element performance.
Innovation Solution
Incorporating a compensation module in the pixel circuit that adjusts the bias state of the driving transistor by receiving a bias signal, which compensates for the threshold voltage drift, thereby maintaining display uniformity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a driving transistor is used in a pixel circuit to provide driving current for the light-emitting element, then the light-emitting element can be controlled to emit light, but the threshold voltage of the driving transistor drifts over time due to changes in internal characteristics, affecting display uniformity
Solution Approach 1:
The patent applies preliminary action by introducing a bias stage before the light-emitting stage where a bias signal is applied to the driving transistor to adjust its bias state in advance. This preliminary adjustment compensates for threshold voltage drift before the actual light-emitting operation, preventing display uniformity issues without requiring complex real-time correction circuits
Solution Approach 2:
The patent changes the operating parameters of the driving transistor by applying a bias signal that adjusts the bias state (such as gate-source voltage or drain-source voltage). This parameter adjustment compensates for threshold voltage drift caused by aging and internal characteristic changes, maintaining stable display performance over time
2Duration of action of stationary object
If the internal characteristics of the driving transistor change with usage time, then the transistor can continue to operate, but the threshold voltage drifts and affects overall transistor characteristics and display uniformity
Solution Approach 1:
The bias stage is implemented as a preliminary action that occurs before each light-emitting stage. By applying the bias signal in advance, the system proactively compensates for threshold voltage drift that accumulates during operational duration, ensuring display uniformity is maintained throughout the transistor's operational life without requiring replacement or complex control circuits
Solution Approach 2:
The patent implements periodic action by repeatedly applying the bias signal in each frame cycle. The bias stage is periodically executed before the light-emitting stage in every display refresh cycle, continuously compensating for threshold voltage drift that occurs during extended operational duration and maintaining consistent display uniformity over time
Data Source
AI summary
A display panel includes a pixel circuit and a light-emitting element. The pixel circuit includes a data-writing module, a driving module, and a compensation module. The driving module is configured to provide a driving current for the light-emitting element, wherein the driving module includes a driving transistor, and the driving transistor is an NMOS transistor. The data-writing module is configured to selectively provide a data signal for the driving module. The compensation module is configured to compensate a threshold voltage of the driving transistor. An operational process of the pixel circuit includes a bias stage. In the bias stage, the compensation module is turned off, the driving transistor receives a bias signal, and the bias signal is configured to adjust a bias state of the driving transistor.