Fringe Field Switching LCD Guard Electrode Asymmetry
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Solution Overview
Problem
Fringe field switching liquid crystal display (FFS-LCD) devices face challenges in achieving improved aperture and transmittance ratios due to the need for higher driving voltage and increased physical area of thin film transistors, which affects display image quality and efficiency.
Innovation Solution
A reduced mask-count process is employed to fabricate FFS-LCD devices with a thinner interlayer dielectric layer and direct connection of transparent electrodes, reducing contact holes and increasing aperture ratio, while maintaining lower driving voltage requirements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If the inclined angle of electrodes is increased to reduce operating voltage, then the operating voltage is reduced, but the display image quality deteriorates due to disclination effect
Solution Approach 1:
The patent introduces a guard electrode with a different potential from the pixel electrode, creating an asymmetric electric field configuration. This asymmetric field distribution suppresses the disclination effect that occurs with symmetric inclined electrode structures, allowing for reduced operating voltage without compromising display image quality.
Solution Approach 2:
The guard electrode acts as an intermediary element between the pixel electrode and the liquid crystal layer. It mediates the electric field distribution to prevent disclination formation, enabling the system to operate at lower voltages while maintaining image quality.
2Reliability
If the physical area of thin film transistor is increased to provide adequate charge storage capability, then the charge storage capability is improved, but the aperture ratio and transmittance ratio are reduced
Solution Approach 1:
The patent changes the electrical parameters of the thin film transistor by introducing a negative bias voltage during the storage period. This parameter change allows the transistor to maintain adequate charge storage capability with a smaller physical area, thereby preserving the aperture ratio and transmittance ratio.
Solution Approach 2:
The patent employs periodic application of negative bias voltage to the thin film transistor during the storage period. This periodic action enhances the charge storage capability of the smaller transistor, allowing it to compensate for the reduced physical area while maintaining the required charge storage performance.
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
The approach enhances aperture and transmittance ratios, improves image quality, and allows for higher backlight intensity tolerance, reducing cross-talk and physical transistor area, thus optimizing display performance.
Implementation Method 1
fringe field switching liquid crystal display (FFS-LCD) devices have pixel and counter electrodes comprising transparent conductors and a narrower distance between electrodes than the distance between the upper and lower substrates to form a fringe field on the electrodes. During operation, the fringe field on the electrodes forces the substantially homogeneous liquid crystal molecules to rotate transversely between the substrates
Implementation Method 2
since the counter electrode and the pixel electrode comprise transparent conductive materials, the aperture ratio and the transmittance ratio of the display devices can thereby be improved
Data Source
AI summary
A system for displaying images, having a display panel, comprising: a lower substrate with a first surface, wherein the first surface is divided into a pixel area and a driver area; a peripheral circuit within the driver area on the first surface; at least one thin film transistor is formed in the pixel area, wherein the thin film transistor comprises an active layer, a gate dielectric layer overlying the active layer, and a gate electrode overlying the gate dielectric layer, and the active layer has source and drain regions; a first transparent electrode layer directly overlapped on a portion of the drain region, electrically connected thereto; and a second transparent electrode pattern is disposed on the gate dielectric layer, opposing the first transparent electrode layer.