Touch-Sensing LCD Anti-Static Layer Using Carbon Nanotubes
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Solution Overview
Problem
Existing touch sensing type liquid crystal display (LCD) devices, such as IPS mode and FFS mode LCDs, face challenges in detecting touch input due to the anti-static layer made of transparent conductive materials like ITO and IZO, which prevents the detection of capacitance changes caused by touch.
Innovation Solution
The implementation of a touch sensing type LCD device that includes an array substrate with a touch sensing unit, a color filter substrate, an anti-static layer on the outer side of the second substrate comprising an organic material and carbon nano-tubes, and a liquid crystal layer between the substrates. This configuration allows for the detection of touch input while preventing damage from static electricity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If an anti-static layer made of transparent conductive materials (ITO, IZO) is used, then static electricity damage is prevented, but touch input detection is blocked
Solution Approach 1:
The patent extracts the anti-static function from the traditional transparent conductive oxide layer and relocates it to a separate layer positioned on the outer surface of the second substrate. This separation allows the touch sensing unit (formed between substrates) to detect touch input through capacitance changes while the extracted anti-static layer provides electrostatic protection without interfering with the sensing mechanism.
Solution Approach 2:
The patent introduces an intermediary structure - the anti-static layer positioned on the outer side of the second substrate - that mediates between the external environment (source of static electricity) and the internal touch sensing structure. This intermediary layer provides static discharge pathways while allowing the electric field necessary for touch detection to pass through to the touch sensing unit.
2Adaptability or versatility
If a horizontal electric field is used (IPS mode), then viewing angle is improved, but touch sensing capability is reduced due to anti-static layer interference
Solution Approach 1:
The patent resolves the contradiction by adding a spatial dimension to the anti-static layer's position - placing it on the outer surface of the second substrate rather than within the liquid crystal cell structure. This dimensional relocation allows the horizontal electric field to operate effectively for wide viewing angles while the anti-static function operates from an external dimension, avoiding interference with capacitance detection.
3Reliability
If transparent conductive materials are used for anti-static layer, then conductivity is achieved, but touch capacitance detection is prevented
Solution Approach 1:
The patent segments the device into distinct functional zones: the touch sensing unit formed between the substrates for precise capacitance measurement, and the anti-static layer on the outer surface for electrical discharge. This segmentation allows each component to perform its function independently - the conductive anti-static layer provides static protection while the capacitive touch sensing unit maintains measurement precision for detecting finger contact.
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 enables the successful detection of touch input by forming a capacitor between the finger and the common electrode, allowing for accurate sensing of touch positions without suffering damage from static electricity due to the anti-static layer's conductive properties.
Implementation Method 1
an anti-static layer on an outer side of the second substrate and including an organic material and a carbon nano-tube
Implementation Method 2
the LCD device uses the optical anisotropy and polarization properties of liquid crystal molecules to produce an image
Implementation Method 3
Due to the optical anisotropy of the liquid crystal molecules, refraction of light incident onto the liquid crystal molecules depends upon the alignment direction of the liquid crystal molecules
Implementation Method 4
the LCD device uses the optical anisotropy and polarization properties of liquid crystal molecules to produce an image
Implementation Method 5
The implementation of a touch sensing type LCD device that includes an array substrate with a touch sensing unit
Data Source
AI summary
A display device includes a first substrate; a second substrate facing the first substrate; a plurality of first electrodes and a plurality of second electrodes disposed between the first substrate and the second substrate; a third electrode on an outer side of the first substrate or the second substrate, the third electrode including an organic material and a carbon nano-tube; a plurality of first conductive lines extending along a first direction; a plurality of second conductive lines extending along the first direction; a plurality of third conductive lines extending along a second direction; and a thin film transistor including a semiconductor layer, a gate electrode, a source electrode, and a drain electrode. A sheet resistance of the third electrode may be greater than a sheet resistance of each of the plurality of first electrodes and a sheet resistance of each of the plurality of second electrodes.