FFS Electrode Potential Shifting for Image Sticking Prevention
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Solution Overview
Problem
Liquid crystal display devices using the fringe-field switching (FFS) mode suffer from image sticking due to asymmetrical electrode configurations, which existing methods fail to effectively address when applied from IPS mode, leading to persistent charge accumulation and display issues.
Innovation Solution
Shifting signal potentials between the first and second electrodes in the FFS mode to intensify the electric field from the first electrode to the second, thereby reducing charge accumulation and preventing image sticking across various gray-scale levels.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If the method developed for IPS mode is applied to FFS mode, then device complexity is reduced, but image sticking occurs due to different electrode shapes
Solution Approach 1:
The patent applies parameter changes by adjusting the potential difference between electrodes based on gray-scale levels. Specifically, when the first electrode potential is higher than the second electrode potential, the potential difference is set to a first value, while when the first electrode potential is lower, the potential difference is set to a second value (different from the first value). This dynamic parameter adjustment suppresses charge accumulation and prevents image sticking in FFS mode while maintaining a relatively simple driving structure.
2Illumination intensity
If asymmetric electrode configuration is used in FFS mode, then viewing angle is improved, but charge accumulation increases causing image sticking
Solution Approach 1:
The patent implements preliminary anti-action by proactively counteracting charge accumulation through potential difference adjustment. Before significant charge buildup occurs, the system dynamically adjusts the potential difference between electrodes based on gray-scale levels, creating an electric field that prevents charge accumulation at the electrodes. This preliminary counter-measure eliminates image sticking while preserving the asymmetric electrode configuration's viewing angle advantage.
3Reliability
If potential difference is increased to suppress charge accumulation, then image sticking is prevented, but power consumption increases
Solution Approach 1:
The patent applies dynamics by making the potential difference adaptive rather than static. The potential difference varies dynamically based on gray-scale levels: a first potential difference value is used when the first electrode potential is higher, and a second potential difference value is used when the first electrode potential is lower. This dynamic adjustment ensures sufficient potential difference to prevent charge accumulation at lower gray-scale levels while reducing power consumption at higher gray-scale levels where charge accumulation is less problematic.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach effectively suppresses image sticking over the entire range of gray-scale levels, enhancing display quality and performance while minimizing power consumption, particularly at maximum gray-scale levels.
Implementation Method 1
A mode in which the alignment of liquid crystal molecules is controlled in response to electric fields in the direction of a substrate that is generated across a liquid crystal layer (electro-optic layer)
Implementation Method 2
the alignment of liquid crystal molecules is controlled in response to electric fields
Data Source
AI summary
A method for driving an electro-optic device includes a first and second electrode and a pair of substrates sandwiching an electro-optic layer driven by the first electrode. The method involves shifting one of two potentials input to at least one of the electrodes such that a potential difference between the first and second electrode where the potential input to the first electrode is higher than the potential input to the second electrode is larger than a potential difference between the first and second electrode where the potential input to the first electrode is lower than the potential input to the second electrode, when a gray-scale level where potential input to the first electrode is higher than potential input to the second electrode is equivalent to the gray-scale level where potential input to the first electrode is lower than potential input to the second electrode.