Reflective LCD with Transverse Electric Field for In-Cell Touch
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Solution Overview
Problem
Existing reflective liquid crystal display devices face challenges in achieving in-cell touch panels capable of providing display in the reflective mode due to alignment defects caused by voltage application, leading to inefficient display and moving image issues.
Innovation Solution
A liquid crystal display device with a transverse electric field mode, specifically the FFS mode, where both electrodes are integrated in the active matrix substrate, and the liquid crystal layer includes positive anisotropy dielectric constant molecules, is designed to minimize alignment defects by optimizing electrode strip portions and slit configurations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If voltage is applied to the liquid crystal layer in existing reflective liquid crystal display devices, then display function is activated, but alignment defects occur leading to display inefficiency and moving image issues
Solution Approach 1:
The patent changes the dielectric constant anisotropy parameter of the liquid crystal material from negative to positive, which fundamentally alters the response characteristics to electric fields and eliminates alignment defects during voltage application
Solution Approach 2:
The patent inverts the conventional electrode configuration by placing both electrodes on the same substrate (active matrix substrate) rather than splitting them between substrates, which reverses the electric field generation mechanism and prevents alignment instability
2Weight of moving object
If in-cell touch panel structure is implemented, then device thickness and weight are reduced, but alignment defects are exacerbated under voltage application
Solution Approach 1:
By changing the liquid crystal material's dielectric constant anisotropy to positive values, the patent ensures that even in the compact in-cell structure where electrodes are in close proximity, alignment stability is maintained during voltage application for touch sensing
Solution Approach 2:
The patent enables the liquid crystal layer to serve multiple functions simultaneously: display modulation and touch sensing, without compromising alignment stability in either function, thus achieving universal performance in both display and touch operations
3Illumination intensity
If reflective mode display is implemented, then outdoor visibility is improved, but in-cell touch panel capability cannot be achieved due to alignment defects
Solution Approach 1:
The patent changes the liquid crystal material parameters (positive dielectric constant anisotropy) to enable simultaneous achievement of reflective mode display with high outdoor visibility and in-cell touch panel functionality without alignment defects
Solution Approach 2:
The patent merges the reflective display function and in-cell touch panel function into a single integrated structure, where both functions operate simultaneously without interference, achieving versatility in both display quality and touch capability
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 proposed solution effectively reduces or prevents alignment defect generation, enabling the development of in-cell touch panels that can provide display in the reflective mode with improved efficiency and image quality.
Implementation Method 1
a first electrode and a second electrode which are capable of generating a transverse electric field in the liquid crystal layer
Implementation Method 2
The liquid crystal layer includes liquid crystal molecules having a positive anisotropy of dielectric constant
Implementation Method 3
a reflective layer which reflects light
Implementation Method 4
The liquid crystal layer is in a twist alignment during no voltage application
Data Source
AI summary
Provided is a liquid crystal display device with sufficiently reduced or prevented alignment defect generation and useful as an in-cell touch panel capable of providing display in the reflective mode. The liquid crystal display device includes first and second substrates and a liquid crystal layer. The first substrate includes a reflective layer reflecting light, first and second electrodes capable of generating a transverse electric field in the liquid crystal layer, and a first horizontal alignment film. At least one of the first electrode or the second electrode includes strip portions and a slit between adjacent two strip portions among the strip portions. The second substrate includes a second horizontal alignment film in contact with the liquid crystal layer. The liquid crystal layer includes liquid crystal molecules having a positive anisotropy of dielectric constant and is in a twist alignment during no voltage application.