Liquid Crystal Display Black Matrix Overlap for Touch Sensing
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Solution Overview
Problem
Liquid crystal display devices with integrated touch sensing functions face challenges in achieving high definition pixels, reducing noise from active elements due to external light, and maintaining visibility, especially with metal touch sensing electrodes that reflect light and affect display quality.
Innovation Solution
A liquid crystal display device configuration with a black matrix and metal wiring layers of equal width, where the black matrix overlaps the wiring layers, and a transparent resin layer is used to cover the black matrix, reducing light reflection and improving visibility, and the use of a channel layer with metal oxides like gallium, indium, zinc, tin, and germanium for active elements to enhance touch sensing precision.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If metal touch sensing electrodes are used, then touch sensing precision is improved, but light reflection increases and visibility deteriorates
Solution Approach 1:
A transparent resin layer is introduced as an intermediary substance between the metal touch sensing electrodes and the liquid crystal layer. This mediator prevents direct optical interaction between the metal electrodes and the display, eliminating light reflection while preserving the electrodes' touch sensing functionality. The transparent resin layer acts as an optical buffer that allows light to pass through without reflecting off the metal surfaces.
Solution Approach 2:
The patent uses a thin transparent resin coating that can be applied as a simple overlay layer. This thin protective layer is economically efficient and does not add significant complexity to the device structure, while effectively solving the light reflection problem caused by metal electrodes.
2Manufacturing precision
If high definition pixels are implemented, then display resolution is improved, but the pixel pitch decreases making touch panel integration difficult
Solution Approach 1:
The patent merges the touch sensing function directly into the liquid crystal display cell structure by forming touch sensing electrodes on the same substrate as the liquid crystal electrodes. This integration eliminates the need for a separate touch panel layer, reducing overall device complexity while maintaining high display resolution. The touch sensing and display functions are combined in a single cell structure.
Solution Approach 2:
The liquid crystal cell structure is designed to serve multiple functions simultaneously: it acts as both the display medium and the touch sensing element. The same electrode structure serves dual purposes for both liquid crystal switching and capacitive touch detection, eliminating the need for additional dedicated touch panel components.
3Adaptability or versatility
If active elements are provided on the array substrate, then touch sensing function is integrated, but noise from active elements increases
Solution Approach 1:
The patent extracts the touch sensing electrode formation process from the active element fabrication sequence. By forming touch sensing electrodes in a separate step after active element completion, the patent isolates the touch sensing function from potential noise sources in the active element circuitry, while maintaining functional integration.
4Illumination intensity
If black matrix overlaps wiring layers, then light reflection is reduced and visibility is improved, but manufacturing precision requirements increase
Solution Approach 1:
The patent performs preliminary alignment marking and positioning before the final black matrix formation step. By pre-establishing reference marks and alignment features on the substrate, the subsequent black matrix patterning can be accurately positioned relative to the wiring layers without requiring extremely high precision during the actual formation process.
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 allows for high definition displays of 300 ppi or more with improved visibility and precise touch sensing, reducing noise and light reflection issues, thus enhancing the display quality and touch sensing accuracy.
Implementation Method 1
a black matrix and metal wiring layers of equal width, where the black matrix overlaps the wiring layers
Implementation Method 2
a transparent resin layer is used to cover the black matrix, reducing light reflection and improving visibility
Implementation Method 3
a method of detecting a change in electrostatic capacitance is mainly used, in which the change in electrostatic capacitance is caused by a contact between the touch panel and a finger or a pointer
Implementation Method 4
a method of using fringe electric field produced between pixel electrodes and a common electrode to drive horizontally-aligned liquid crystal cells in a direction relative to the horizontal electric field. The method is referred to as an FFS (fringe field switching) or IPS (in-plane switching) method
Data Source
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AI summary
The present invention provides a liquid crystal display device including: a counter substrate (100) having a first transparent substrate (10), a laminate structure of a black layer (1) and a first metal layer (2), and a plurality of terminal portions (11); a liquid crystal layer (30); an array substrate (200) having a second transparent substrate (20), an active element (51), a second wiring layer (23) formed of a second metal layer, and a light shielding layer. The counter substrate (100) is provided with the first wiring layer (3), a black matrix (4), and a first transparent resin layer (6) laminated in this order. The black matrix (4) has a line width larger than a line width (M1W) of the first wiring layer (3), overlapping the first wiring layer so as to include a pattern of the first wiring layer (3). The active element (51) is covered with a light shielding pattern (59) via a first insulation layer. A change in electrostatic capacitance produced between the first wiring layer (3) and the second wiring layer (23) is detected, thereby performing a touch sensing operation.