Common Electrode Insulating Film for LCD Light Leak Control
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Solution Overview
Problem
Conventional liquid crystal display apparatuses suffer from light leaks in the peripheral regions of pixels due to disordered alignment of liquid crystal molecules caused by electric fields generated between scanning and signal lines, leading to reduced contrast and aperture ratio.
Innovation Solution
The design incorporates a common electrode that is superimposed over the pixel electrodes through an insulating film, with edge portions formed to block the electric field in the peripheral regions, and a metal electroconductive film along scanning and signal lines to generate a uniform electric field, reducing light leaks and improving contrast.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a common electrode and pixel electrodes are provided in a conventional liquid crystal display apparatus, then an electric field is generated to control liquid crystal molecule alignment, but light leaks occur in peripheral regions due to disordered alignment caused by electric fields from scanning and signal lines
Solution Approach 1:
An insulating film is introduced as an intermediary layer between the common electrode and pixel electrodes. This insulating film acts as a mediator that blocks the harmful electric field lines from extending into the liquid crystal layer at peripheral regions, thereby preventing disordered liquid crystal alignment and eliminating light leaks while maintaining the conventional electrode configuration
Solution Approach 2:
The harmful electric field effect is extracted and isolated by confining the electric field generation to specific regions. The insulating film removes the harmful electric field influence from peripheral regions by blocking field line extension, separating the useful electric field control from the harmful peripheral field effects
2Object-affected harmful factors
If a black mask is provided to avoid light leak, then light leak is reduced, but aperture ratio is reduced and display image is darkened
Solution Approach 1:
The insulating film converts the harmful electric field effect into a beneficial function by utilizing the film's electrical properties to block field lines. This transforms the insulating film from a passive insulator into an active element that prevents light leaks through electric field management, eliminating the need for black masks and preserving aperture ratio
3Manufacturing precision
If the common electrode is superimposed over pixel electrodes through an insulating film, then electric field control is improved, but device structure becomes more complex
Solution Approach 1:
The insulating film serves multiple functions simultaneously: it provides electrical insulation between electrodes, blocks harmful electric field lines from peripheral regions, and enables precise electric field control in the liquid crystal layer. This multi-functionality reduces the need for additional specialized components, offsetting the structural complexity with functional integration
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 eliminates light leaks, enhances contrast, and increases the aperture ratio, resulting in a brighter and higher-quality display with uniform electric field control.
Implementation Method 1
generates an electric filed which controls an alignment direction of the liquid crystal molecules in a plane substantially parallel with the substrate surfaces
Implementation Method 2
a liquid crystal layer which is disposed in the gap between the pair of substrates with long axes of liquid crystal molecules being aligned in one direction, in substantially parallel to substrate surfaces
Data Source
AI summary
A liquid crystal display apparatus includes a liquid crystal layer which is disposed in a gap between first and second substrates with long axes of liquid crystal molecules being aligned in one direction, in substantially parallel to substrate surfaces. A plurality of thin film transistors are arranged in row and column directions on an upper side of the first substrate. Pixel electrodes are provided on the upper side of the first substrate to be electrically connected with the thin film transistors. A common electrode is formed on the upper side of the first substrate between the substrate and the liquid crystal layer to correspond to the pixel electrode through an insulating film, and generates an electric filed which controls an alignment direction of the liquid crystal molecules in a plane substantially parallel with the substrate surfaces between itself and the pixel electrode.