Electroluminescent Display Device Hysteresis Compensation
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Solution Overview
Problem
The hysteresis phenomenon in the gate-source voltage of driving TFTs in organic light emitting display devices leads to image quality irregularity and DC afterimages due to prolonged maintenance of the same gate-source voltage, affecting display quality over time.
Innovation Solution
Implementing a multi-scan driving method where the gate-source voltage of the driving TFT is updated by setting a first gate-source voltage based on a first data voltage during a first period and a second gate-source voltage based on a second data voltage during a second period, with the emission controlling element turned off, to change the on-biased state and compensate for hysteresis, and applying the second data voltage to another pixel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the gate-source voltage of the driving TFT is maintained at the same value for a long time to display the same image, then the display stability is improved, but the hysteresis phenomenon becomes stronger causing DC afterimages and lowering display quality
Solution Approach 1:
The patent applies periodic action by updating the gate-source voltage of the driving TFT at specific intervals (e.g., once per frame or multiple times per frame) rather than maintaining it continuously. This periodic update prevents the hysteresis phenomenon from accumulating while still allowing the display to show stable images between updates, effectively resolving the contradiction between display stability and hysteresis reduction
Solution Approach 2:
The patent changes the voltage parameter of the gate-source voltage periodically by applying different voltage levels (e.g., initial voltage Vinit, first data voltage Vdata1, second data voltage Vdata2) at different time points. This parameter change approach allows the display to maintain stability during image display while periodically altering the voltage to reduce hysteresis, thereby solving the technical contradiction
2Object-generated harmful factors
If the gate-source voltage is updated frequently to reduce hysteresis phenomenon, then the hysteresis effect is reduced, but the power consumption increases due to additional voltage switching operations
Solution Approach 1:
The patent applies partial action by updating the gate-source voltage only partially (not continuously) at specific moments such as at the beginning of each frame or at selected intervals. This partial update approach is sufficient to reduce hysteresis to an acceptable level without requiring continuous voltage changes, thereby minimizing unnecessary power consumption while still effectively mitigating the hysteresis phenomenon
Data Source
AI summary
The electroluminescent display device according to the present disclosure comprises a plurality of pixels. Each of the plurality of pixels comprises a driving element for generating a driving current, a light emitting element for emitting light according to the driving current, an emission controlling element for controlling a flow of the driving current between the driving element and the light emitting element, and a switching circuit for setting a first gate-source voltage of the driving element corresponding to the driving current based on a first data voltage during a first period and setting a second gate-source voltage of the driving element based on a second data voltage different from the first data voltage during a second period following the first period, wherein the second gate-source voltage is different from the first gate-source voltage, and wherein during the second period the emission controlling element is turned off.