Floating Electrode LCD Privacy Mode Light Leakage
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Solution Overview
Problem
Liquid crystal display devices face challenges in achieving high contrast ratios and privacy mode functionality due to light leakage and decreased contrast caused by voltage application to electrodes in the color filter substrate, which generates undesirable electric fields in the liquid crystal layer.
Innovation Solution
The liquid crystal display device incorporates a floating fourth electrode between the black matrix and the liquid crystal layer, with second linear electrodes intersecting the first direction, and a control circuit that switches between driving voltage and constant voltage application to the third electrode to manage electric fields and enhance contrast ratios in privacy mode.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If voltage is applied to the third electrode in the color filter substrate to enable privacy mode, then viewing angle characteristics are improved, but light leakage occurs and front contrast ratio decreases
Solution Approach 1:
A fourth electrode is introduced as an intermediary element positioned between the third electrode and the black matrix. This fourth electrode acts as a mediator that prevents direct charging of the black matrix when voltage is applied to the third electrode, thereby eliminating the harmful electric field that causes light leakage while preserving the privacy mode functionality.
Solution Approach 2:
The invention converts the potentially harmful effect of electric field generation into a beneficial outcome. By carefully controlling the voltage application to the fourth electrode, the electric field is used to prevent black matrix charging and eliminate light leakage, thus transforming what could be a harmful side effect into a solution that improves display quality.
2Adaptability or versatility
If voltage is applied to the third electrode in the color filter substrate, then privacy mode is achieved, but front contrast ratio decreases
Solution Approach 1:
The fourth electrode serves as an intermediary that decouples the voltage application to the third electrode from the black matrix charging. This allows privacy mode to be activated through the third electrode while the fourth electrode prevents the formation of unwanted electric fields that would degrade front contrast ratio.
3Device complexity
If a planar solid electrode is used as the first electrode to simplify structure, then device complexity is reduced, but vertical electric field is generated throughout the liquid crystal panel making high front contrast ratio difficult to achieve
Solution Approach 1:
The electrode structure is segmented into multiple components: the first electrode on the active matrix substrate, the third electrode on the color filter substrate, and the fourth electrode positioned between the third electrode and black matrix. This segmentation allows each electrode to perform its specific function independently, enabling precise control of electric fields to achieve high front contrast ratio while maintaining structural simplicity.
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 light leakage and maintains high contrast ratios in privacy mode, allowing for seamless switching between privacy and public modes while preventing electric field misalignment, thus enhancing viewing angle characteristics.
Implementation Method 1
voltage is applied to a liquid crystal composition sealed between paired substrates such that the alignment of liquid crystal molecules in the liquid crystal composition is changed according to the applied voltage, whereby the amount of light passing through the device is controlled
Implementation Method 2
applying voltage to an electrode in a color filter substrate sometimes charges the black matrix and forms an undesirable electric field in the liquid crystal layer
Data Source
AI summary
The liquid crystal display device of the present invention includes an active matrix substrate including a first electrode, a first insulating layer, and second electrodes including a first linear electrode; a color filter substrate including a black matrix, a color filter layer, a third electrode including second linear electrodes, and a fourth electrode which is a floating electrode. The third electrode and the fourth electrode are disposed between the black matrix and the liquid crystal layer. The second linear electrodes extend in a second direction and each overlap a portion of the black matrix extending in the second direction. The fourth electrode is disposed between the second linear electrodes and overlaps the black matrix in a plan view. The control circuit switches between application of driving voltage and application of constant voltage to the third electrode.