Liquid Crystal Display Static Electricity Alignment Defects
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Solution Overview
Problem
Static electricity generated during the rubbing process in liquid crystal display devices causes alignment defects, leading to optical holes that result in defective products with white or black dots in normally black or white displays.
Innovation Solution
A liquid crystal display device with a pair of substrates, each having a predetermined electrode shape, a vertical alignment film, and an insulating film, where the specific resistance of the liquid crystal material is between 1.0×10^14 Ωcm to 1.0×10^15 Ωcm, and the charge resident time until a display image disappears after static electricity application is controlled to be within specific limits, preventing alignment defects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a rubbing process is used to control alignment directions of liquid crystal molecules, then alignment quality is improved, but static electricity is generated causing alignment defects
Solution Approach 1:
The patent utilizes the static electricity generated during the rubbing process by connecting electrodes to maintain the same potential, converting the harmful static charge into a beneficial effect that prevents alignment defects. The static electricity is not eliminated but rather harnessed to improve alignment quality by preventing charge discharge that would cause alignment holes.
2Reliability
If static electricity is discharged to eliminate charge accumulation, then electrical safety is improved, but liquid crystal alignment function is damaged forming alignment defects
Solution Approach 1:
The patent applies equipotentiality by connecting electrodes to maintain the same potential, preventing potential differences that would cause harmful discharge. This maintains electrical safety while preserving the liquid crystal alignment function, as the static electricity is managed through potential equalization rather than discharge.
3Use of energy by moving object
If the specific resistance of liquid crystal is increased to reduce leakage current, then energy efficiency is improved, but charge resident time increases allowing static electricity to cause defects
Solution Approach 1:
The patent introduces an intermediary mechanism (electrode connection system) that mediates between the high specific resistance liquid crystal and the static electricity problem. The electrodes act as intermediaries to manage charge distribution, allowing the use of high resistance liquid crystal for energy efficiency while preventing static electricity from causing alignment defects through controlled charge management.
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 solution effectively reduces alignment hole formation rates and extends charge resident time, significantly minimizing alignment defects caused by static electricity discharge, thereby improving the quality of liquid crystal display devices.
Implementation Method 1
liquid crystal sandwiched between the pair of substrates and having a negative dielectric anisotropy Δ∈
Implementation Method 2
specific resistance ρc1 of 1.0×10^14 Ωcm to 1.0×10^15 Ωcm
Implementation Method 3
An alignment film of a liquid crystal display device is charged with static electricity by a rubbing process
Data Source
AI summary
A liquid crystal display device includes: a pair of substrates each disposed on each opposing plane and having an electrode of a predetermine shape; a vertical alignment film formed covering each of the electrodes of the pair of substrates and subjected to a rubbing alignment process; an insulating film formed between the electrode and the vertical alignment film in each of the pair of substrates and having necessary insulation; and liquid crystal sandwiched between the pair of substrates and having a negative dielectric anisotropy Δ∈ and a specific resistance ρc1 of 1.0×1014 Ωcm to 1.0×1015 Ωcm, wherein a structure between the electrodes is selected to satisfy conditions of T≦5.2×τc1×1/(1×1012) sec and T≦500 sec, where T is a charge resident time until a display image disappears completely after static electricity of 10 kV is applied between the electrodes of the pair of substrate and the display image is tuned on. It is possible to prevent alignment defects to be caused by static electricity generated by rubbing of a liquid crystal display device.