On-Cell Touch Color Filter Substrate for Liquid Crystal Displays
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Solution Overview
Problem
Existing liquid crystal display devices with integrated touch sensing functions face challenges in achieving high precision touch sensing and maintaining uniform liquid crystal alignment due to the thickness of on-cell type touch panels and the influence of electrostatic discharge on liquid crystal molecules.
Innovation Solution
A liquid crystal display device with a color filter substrate that includes orthogonally crossed transparent electrode layers and a transparent resin layer, where the color filter is formed with red, green, and blue filters having specific dielectric constants and a light shielding layer, enhancing detection accuracy and minimizing the impact of electrostatic discharge on liquid crystal alignment.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If an on-cell type touch panel is provided in portable equipment, then touch sensing function is integrated, but thickness and weight of the equipment increase
Solution Approach 1:
The patent combines the color filter substrate and touch sensor electrode into a single integrated structure. The transparent electrode is formed on the color filter substrate, merging the display and touch sensing functions into one component, thereby integrating the touch panel without adding separate layers that would increase thickness.
Solution Approach 2:
The color filter substrate serves dual functions: it acts as both the display color filter layer and the substrate for the touch sensor electrode. This multi-functional design allows the same component to perform both display and touch sensing roles, avoiding additional thickness from separate touch panel layers.
2Measurement precision
If transparent electrode patterns are formed on transparent substrate for high-precision touch sensing, then detection accuracy improves, but electrostatic discharge affects liquid crystal alignment
Solution Approach 1:
The patent introduces a transparent resin layer as an intermediary between the transparent electrode and the liquid crystal layer. This resin layer acts as a buffer that prevents direct contact between the electrode and liquid crystal, thereby blocking the harmful electrostatic discharge from affecting liquid crystal alignment while maintaining the electrode's touch sensing functionality.
Solution Approach 2:
The transparent resin layer is positioned in advance between the electrode and liquid crystal to provide protective cushioning. This pre-established barrier prevents electrostatic discharge from reaching the liquid crystal molecules before damage can occur, ensuring stable liquid crystal alignment during touch operations.
3Ease of manufacture
If color filter is formed on black matrix with large film thickness, then color filtering is achieved, but protrusion and film thickness variation cause non-uniform liquid crystal alignment
Solution Approach 1:
The patent changes the structural parameters of the color filter by eliminating the protrusion issue. Instead of having thick black matrix with colored pixels on top, the color filter is formed in a planar configuration where the transparent resin layer provides a uniform surface. This parameter change from vertical stacking to planar integration maintains color filtering while ensuring uniform liquid crystal alignment.
4Measurement precision
If shield electrode is provided to detect capacitive component, then electrostatic capacitance detection is improved, but device complexity increases
Solution Approach 1:
The patent merges the shield electrode function with the existing transparent electrode structure. Rather than adding a separate shield electrode layer, the design integrates the capacitive detection capability into the transparent electrode that is already part of the display structure, thereby maintaining detection precision while avoiding additional complexity.
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 solution provides a high precision touch sensing function while maintaining uniform liquid crystal alignment and preventing light leakage, thereby improving the overall image quality and transmittance of the liquid crystal display device.
Implementation Method 1
electrostatic capacitance type touch sensing
Implementation Method 2
red, green, and blue filters having specific dielectric constants
Implementation Method 3
light shielding layer, preventing light leakage
Data Source
Figure 1~2
Figure 3(a)~4
Figure 5~6
AI summary
A liquid crystal display device is provided with a touch panel function, in which an array substrate (2) and a color filter substrate (4) are faced each other via a liquid crystal layer (3). The color filter substrate (4) includes: a transparent substrate (11); first and second transparent electrode layers (12a, 12b); a color filter (CF); and a transparent resin layer (14). The first and second transparent electrode layers (12a, 12b) are respectively formed on first and second surfaces of the transparent substrate (11) for touch sensing. The color filter (CF) is formed on the first transparent electrode layer (12a), including a red filter, a green filter and a blue filter. The transparent resin layer (14) is formed on the color filter (CF). In the liquid crystal display device, the second transparent electrode layer (12b) is formed on a display surface side and the transparent resin layer (14) is formed on a liquid crystal layer (3) side. The total film thickness of the color filter (CF) and the transparent resin layer (14) is within a range approximately from 2.5 µm to 9 µm. The liquid crystal layer (3) includes liquid crystal molecules (L) having negative dielectric anisotropy and an initial state alignment which is parallel to a substrate surface. The liquid crystal molecules rotate parallel with respect to the substrate surface when a liquid crystal drive voltage is applied.