Display Panel Bias Adjustment for Threshold Voltage Drift
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Solution Overview
Problem
The display panel's display uniformity is adversely affected due to threshold voltage drift of the drive transistor over time, especially when operating in different brightness modes, as the fixed compensation signals fail to address the varying threshold voltage drifts across different brightness levels.
Innovation Solution
The display panel incorporates a pixel circuit with a drive module, a bias adjustment module, and an initialization module. Different bias adjustment signals and initialization signals are provided for different operation modes to adjust the bias state of the drive transistor and ensure consistent initialization of the light emitting element across varying brightness levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If a fixed compensation signal is used for the drive transistor, then the circuit structure is simple, but the display uniformity deteriorates due to threshold voltage drift in different brightness modes
Solution Approach 1:
The patent implements dynamic bias adjustment by switching between different bias adjustment signals (first bias adjustment signal in high brightness mode, second bias adjustment signal in low brightness mode) based on the display brightness level. This dynamic adaptation allows the pixel circuit to compensate for threshold voltage drift effectively across different operating conditions, thereby improving display uniformity without requiring a fundamentally complex circuit structure.
Solution Approach 2:
The patent changes the bias adjustment parameter (bias adjustment signal voltage level) according to the brightness mode. In high brightness mode, a first bias adjustment signal is applied, while in low brightness mode, a second bias adjustment signal is applied. This parameter adaptation enables effective compensation for threshold voltage drift that varies with brightness levels, resolving the contradiction between simple circuit structure and display uniformity.
2Adaptability or versatility
If different brightness modes are supported, then the adaptability is improved, but the threshold voltage drift varies causing display quality to deteriorate
Solution Approach 1:
The pixel circuit dynamically adapts to different brightness modes by selectively applying different bias adjustment signals. The circuit detects the brightness mode (high or low) and adjusts the bias signal accordingly, enabling effective threshold voltage compensation in each mode. This dynamic adaptation maintains high display quality across varying brightness levels while preserving the adaptability benefit.
Solution Approach 2:
The patent applies different bias adjustment signal parameters depending on the brightness mode. In high brightness mode, the first bias adjustment signal compensates for the threshold voltage drift characteristics of that mode, while the second bias adjustment signal compensates for drift in low brightness mode. This parameter adaptation resolves the issue of varying display quality across different brightness modes.
3Manufacturing precision
If the bias adjustment signal is changed for different brightness modes, then the display uniformity is improved, but the signal complexity increases
Solution Approach 1:
The patent implements dynamic signal selection where the bias adjustment module switches between a first bias adjustment signal and a second bias adjustment signal based on the brightness mode. This dynamic approach improves display uniformity by providing mode-appropriate compensation while keeping the signal complexity manageable through systematic signal management rather than arbitrary complexity.
Solution Approach 2:
The patent changes the bias adjustment signal parameter according to brightness mode to improve display uniformity. The first bias adjustment signal is used in high brightness mode and the second in low brightness mode. This controlled parameter change achieves the desired uniformity improvement while maintaining reasonable signal complexity through structured signal design.
Data Source
AI summary
Provided display panel includes pixel circuit and light emitting element. The pixel circuit includes drive module including a drive transistor, bias adjustment module to provide a bias adjustment signal to a first pole or a second pole of the drive transistor and initialization module to provide initialization signal to the light emitting element. Operation modes include a first mode and a second mode, and brightness level of the display panel in the first mode greater than that in the second mode. The pixel circuit includes data writing frame and holding frame, data writing frame in first mode corresponds to initialization signal of Vi11, holding frame in first mode corresponds to initialization signal of Vi12, data writing frame in second mode corresponds to bias adjustment signal of Vs21, holding frame in second mode corresponds to bias adjustment signal of Vs22, and |Vi11−Vi12|≠|Vs21−Vs22|.