Pixel Circuit Bias Control for Display Uniformity
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Solution Overview
Problem
Display panels experience screen flashing when operated at low refresh rates due to ion polarization in driving modules, leading to shifts in threshold voltage and display uniformity issues.
Innovation Solution
A pixel circuit and driving method that adjust the bias state of the driving module by extending the turn-on duration of the bias module in the hold frame, increasing the time interval between the bias module turn-on and light-emitting stages, and overlapping bias stages in the refresh frame, to reduce the difference in threshold voltage between refresh and hold frames.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If the display panel operates at a low refresh rate to reduce power consumption, then power consumption is reduced, but screen flashing occurs due to ion polarization and threshold voltage shifts
Solution Approach 1:
The patent applies preliminary action by introducing a bias stage before the light-emitting stage in hold frames. This bias stage pre-adjusts the threshold voltage of the driving module to compensate for ion polarization effects that will occur during the light-emitting stage, thereby preventing display uniformity issues before they manifest
Solution Approach 2:
The patent implements periodic action by alternating between refresh frames (with control terminal refresh) and hold frames (with extended bias application). This periodic switching maintains display uniformity during low refresh rate operation by ensuring that hold frames receive sufficient bias compensation to counteract ion polarization
2Stability of the object's composition
If the turn-on duration of the bias module is extended in hold frames to compensate for ion polarization, then threshold voltage stability is improved, but the time interval between bias module turn-on and light-emitting stage increases
Solution Approach 1:
The extended turn-on duration of the bias module in hold frames applies preliminary action by starting the bias signal earlier and maintaining it longer before the light-emitting stage. This ensures sufficient time for threshold voltage compensation while managing the overall timing budget of the display cycle
3Reliability
If bias stages in the refresh frame are overlapped to reduce threshold voltage difference between frames, then display uniformity is improved, but the complexity of the driving module increases
Solution Approach 1:
The patent applies merging by overlapping bias stages within refresh frames, combining multiple bias application periods into a coordinated sequence. This reduces the threshold voltage difference between refresh and hold frames by ensuring consistent bias compensation across different frame types, while sharing circuit resources
Data Source
AI summary
The embodiments of the present application provide a pixel circuit and a driving method thereof, a display panel and a display device. The pixel circuit includes: a driving module; a first bias module configured to provide a first bias signal; wherein a light-emitting cycle of the light-emitting element comprises a refresh frame or a hold frame, each of the refresh frame and the hold frame comprises a first stage and a second stage, the first stage comprises one or more bias stages, and the second stage comprises a light-emitting stage, and wherein in the bias stages, the first bias module is turned on, and the first bias signal is transmitted to the driving module; wherein a turn-on duration of the first bias module in the hold frame is greater than a turn-on duration of the first bias module in the refresh frame.