Metal Grid Electrodes for Touch LCD Parasitic Capacitance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing touch control liquid crystal display devices face issues with large parasitic capacitance, low sensitivity of detection, and non-uniform transmittivity due to the use of ITO electrodes, which hinder accurate touch signal detection and display quality.
Innovation Solution
The implementation of metal grids as electrodes instead of ITO, forming a multi-layer structure with insulation layers, reduces parasitic capacitance, lowers resistance, and improves light transmittivity, while aligning with the black matrix layer to minimize visual interference and enhance detection sensitivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If ITO electrodes are used in the touch control layer, then the layer can be made transparent to allow light transmission, but the transmittivity of pixel elements corresponding to electrodes does not agree with those corresponding to gaps, resulting in non-uniform display
Solution Approach 1:
The touch control layer is segmented into a metal grid structure with multiple metal lines arranged in rows and columns, creating multiple gaps between adjacent metal lines. This segmentation allows different regions (electrode areas vs. gap areas) to have different optical properties while maintaining overall display uniformity through the distributed grid pattern.
Solution Approach 2:
The metal grid structure creates local variations in transmittivity where metal lines block light and gaps allow light transmission. By carefully designing the grid parameters (line width, spacing, orientation), the local quality differences are controlled to achieve uniform overall display characteristics while maintaining touch sensitivity in specific regions.
2Illumination intensity
If ITO electrodes are used in the touch control layer, then the layer can transmit light, but the resistance is high which lowers detection sensitivity and increases load
Solution Approach 1:
The patent replaces the ITO material-based electrical conduction system with a metal-based conduction system. Metal materials have inherently lower resistivity than ITO, so substituting metal for ITO in the electrode structure dramatically reduces resistance while maintaining transparency through the grid design, thereby improving detection sensitivity without sacrificing light transmission.
3Ease of operation
If drive electrodes and sense electrodes overlap with pixel electrodes, data lines and scan lines on the array substrate, then capacitances are formed in overlapping sections, but large parasitic capacitance distorts drive signals and attenuates detection signals
Solution Approach 1:
The electrodes are segmented into discrete metal lines arranged in a grid pattern, creating multiple small overlapping regions rather than large continuous overlapping areas. This segmentation reduces the total parasitic capacitance while maintaining the necessary capacitive coupling for touch detection functionality.
Solution Approach 2:
The patent transitions from planar electrode layouts to a three-dimensional multi-layer metal grid structure. By stacking metal lines in multiple layers with insulation between them, the design reduces parasitic capacitance between adjacent electrodes while maintaining effective touch detection through the distributed capacitive network across multiple dimensions.
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 solution effectively lowers parasitic capacitance, improves signal detection sensitivity, and enhances display uniformity and transmittivity, addressing the limitations of ITO electrodes in existing touch control liquid crystal display devices.
Implementation Method 1
the metal grid electrodes include a plurality of drive electrodes and a plurality of sense electrodes... the drive electrodes and the sense electrodes form a mutual capacitance at their intersection
Implementation Method 2
Since a finger is a conductor, the mutual capacitance at the location of a touch will vary due to a capacitive inductive effect of the finger when the finger touches the surface of the touch screen
Data Source
Figure 1~2
Figure 3~4
Figure 5~6
AI summary
The invention discloses a touch control liquid crystal display device, relates to the field of integrated touch screens and is intended to address the problems of a large parasitic capacitance, low sensitivity of detection, poor display effect, etc., of an existing touch screen. The touch control liquid crystal display device according to the invention includes a color film substrate, a thin film transistor array substrate, and a liquid crystal layer arranged between the color film substrate and the thin film transistor array substrate, and the color film substrate includes a grid-shaped black matrix layer, a touch control layer and a color film layer in that order; wherein the touch control layer includes a plurality of metal grid electrodes arranged in a rectangle, wherein the metal grid electrodes comprise a plurality of metal lines intersecting transversely and vertically, and the metal grid electrodes include a plurality of drive electrodes and a plurality of sense electrodes, and the plurality of drive electrodes are connected together through a plurality of first metal connection lines in a first direction, and the plurality of sense electrodes are connected together through a plurality of second metal connection lines in a second direction; and the projection of the metal grid electrodes falls into the projection of the black matrix layer in the light transmission direction.