Liquid Crystal Display Privacy Mode Contrast Control
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Solution Overview
Problem
Liquid crystal display devices face challenges in achieving high contrast ratios and preventing light leakage in privacy mode due to undesirable electric fields generated by voltage application to electrodes in the color filter substrate, which affects front contrast ratio and viewing angles.
Innovation Solution
The liquid crystal display device incorporates a third electrode with second linear electrodes intersecting the first direction, overlapping the black matrix, and a fourth electrode between the black matrix and the third electrode, which is applied with constant voltage to prevent charging of the black matrix and reduce electric fields, allowing for switching between privacy and public modes while maintaining high contrast ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If voltage is applied to the third electrode in the color filter substrate to switch between viewing angle modes, then the 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 component positioned between the black matrix and the third electrode. This fourth electrode acts as a mediator that prevents direct electrical interaction between the third electrode and the black matrix, thereby eliminating the charging effect and unwanted electric fields that cause light leakage, while still allowing the third electrode to control liquid crystal molecules for viewing angle switching.
2Adaptability or versatility
If voltage is applied to the third electrode in the color filter substrate, then viewing angle control is achieved, but an undesirable electric field is generated in the liquid crystal layer
Solution Approach 1:
The fourth electrode serves as a shielding intermediary that blocks the transmission of electric fields from the third electrode to the liquid crystal layer. By positioning the fourth electrode between the black matrix/third electrode assembly and the liquid crystal layer, it prevents the formation of undesirable electric fields that would otherwise interfere with liquid crystal molecule alignment and cause display defects.
3Ease of operation
If a planar solid electrode is used as the first electrode of the counter substrate, then voltage application generates a vertical electric field in the entire liquid crystal panel, but achieving a high front contrast ratio becomes difficult
Solution Approach 1:
The invention replaces the uniform planar solid electrode with a segmented electrode structure consisting of multiple linear electrodes arranged in specific patterns. This localizes the electric field generation to specific regions and orientations, allowing precise control over where and how electric fields are generated in the liquid crystal layer, thereby maintaining high front contrast ratio while enabling viewing angle mode switching.
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 prevents light leakage and maintains high contrast ratios in privacy mode, enabling seamless switching between viewing angles, thus enhancing privacy and display quality.
Implementation Method 1
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
Implementation Method 2
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
Data Source
AI summary
Provided is a liquid crystal display device that can switch between the privacy mode and the public mode and achieve a high contrast ratio even during display in the privacy mode. The liquid crystal display panel includes: a liquid crystal panel; and a control circuit. The active matrix substrate sequentially includes a first substrate, a first electrode, a first insulating layer, and second electrodes each including a first linear electrode. The color filter substrate includes a second substrate, a black matrix, a color filter layer, a third electrode, and a fourth electrode which is disposed between the black matrix and the third electrode and to which constant voltage is applied. The third electrode includes second linear electrodes and overlaps a portion of 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.