Liquid Crystal Display Flicker Mitigation via Localized Insulator Properties
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Solution Overview
Problem
Conventional FFS mode liquid crystal display devices experience significant worsening of flicker after long-term display of a solid white image due to differences in optimal common voltage values between sub-pixel central and edge areas, leading to increased electric field strength at the edge areas.
Innovation Solution
A liquid crystal display device structure is implemented with a planar common electrode and sub-pixel electrodes having slits, where the interlayer insulating film has varying film thickness and relative permittivity at the sub-pixel edge and central areas, ensuring a lower electric field strength at the edge areas compared to the central areas, thereby reducing the difference in electric field strength and mitigating flicker.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the interlayer insulating film has uniform film thickness and relative permittivity across sub-pixel areas, then the device structure is simple and easy to manufacture, but the electric field strength becomes excessively high at sub-pixel edge areas causing severe flicker after long-term display
Solution Approach 1:
The interlayer insulating film is designed with different film thicknesses and/or relative permittivities in different regions: a first region with higher film thickness and/or lower relative permittivity at sub-pixel edge areas to reduce electric field strength, and a second region with lower film thickness and/or higher relative permittivity at sub-pixel central areas. This local differentiation resolves the contradiction by tailoring the insulating film properties to specific spatial locations, reducing flicker at edges while maintaining performance at centers.
Solution Approach 2:
The patent changes the physical parameters of the interlayer insulating film (film thickness and relative permittivity) across different spatial regions. By varying these parameters locally rather than maintaining uniform values, the electric field distribution is optimized to prevent excessive field strength at edge areas, thereby improving display stability without requiring overly complex structural modifications.
2Reliability
If the interlayer insulating film uses high relative permittivity material throughout, then the capacitance increases improving display response, but the electric field strength at edge areas becomes excessively high worsening flicker
Solution Approach 1:
The interlayer insulating film employs different relative permittivity values in different regions: lower relative permittivity in the first region at sub-pixel edge areas to reduce electric field strength and minimize flicker, and higher relative permittivity in the second region at sub-pixel central areas to maintain adequate capacitance for display response. This spatially differentiated approach resolves the contradiction between capacitance requirements and flicker prevention.
3Productivity
If the film thickness of the interlayer insulating film is reduced to increase capacitance, then display response improves, but the electric field strength at edge areas increases causing severe flicker
Solution Approach 1:
The patent implements variable film thickness in the interlayer insulating film: a first region with greater film thickness at sub-pixel edge areas to reduce electric field strength and prevent flicker, and a second region with smaller film thickness at sub-pixel central areas to maintain sufficient capacitance for fast display response. This local differentiation resolves the contradiction between response speed and stability.
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 configuration effectively reduces the worsening of flicker after long-term display of a solid white image by maintaining a weaker fringe electric field at the sub-pixel edge areas, aligning with the electric field strength at the central areas, thus improving display stability.
Implementation Method 1
an electric field strength between the common electrode and the linear electrode portions at the sub-pixel edge area being lower than an electric field strength between the common electrode and the linear electrode portion at the sub-pixel central area
Implementation Method 2
the interlayer insulating film including a region overlapping the linear electrode portions at the sub-pixel edge area and a region overlapping the linear electrode portion at the sub-pixel central area for each sub-pixel, the regions being different in at least one of a film thickness or a relative permittivity
Data Source
AI summary
Provided is a liquid crystal display device including a first and second sub-pixels and including a first and second substrates. The first substrate includes a common electrode, an interlayer insulating film, and a first and second sub-pixel electrodes. The first and second sub-pixel electrodes each include linear electrode portions at an edge area and a linear electrode portion at a central area. The interlayer insulating film includes a region overlapping the linear electrode portions at the edge area and a region overlapping the linear electrode portion at the central area for each sub-pixel and the regions are different in at least one of a film thickness or a relative permittivity. An electric field strength between the common electrode and the linear electrode portions at the edge area is lower than an electric field strength between the common electrode and the linear electrode portion at the central area.