Touch Screen LCD Gap Column Spacer Density Optimization
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Solution Overview
Problem
Touch screen LCDs using the glass bonding method suffer from defects such as non-uniform brightness, spot formation during swiping, and deformation due to the cold bubble and gravity phenomena, which are caused by the difference in volumetric shrinkage rates of liquid crystals and glass substrates, and are exacerbated by the density of gap column spacers.
Innovation Solution
The implementation of gap column spacers with a density of 0.05% to 0.11% with respect to the display region, combined with press column spacers, to maintain a consistent cell gap and prevent these defects, using materials like organic insulating materials that do not damage the substrates or affect the liquid crystal layer, and employing an optical adhesive for lamination to improve adhesion and visibility.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the density of gap column spacers is increased to prevent cold bubble phenomenon, then the adhesion between substrates is improved, but gravity defect phenomenon occurs due to excessive cell gap at higher temperatures
Solution Approach 1:
The patent optimizes the density parameter of gap column spacers to a specific range (0.03% to 0.08%) to balance two opposing effects: preventing cold bubble phenomenon at low temperatures while avoiding gravity defect phenomenon at high temperatures. This parameter optimization resolves the contradiction by finding the optimal point where both adhesion and cell gap uniformity are maintained across temperature variations.
2Stability of the object's composition
If column spacers are formed to contact the TFT substrate to maintain cell gap, then structural stability is improved, but touch defects occur due to non-uniform brightness and spot formation
Solution Approach 1:
The patent introduces gap column spacers as intermediary elements that maintain cell gap without directly contacting the TFT substrate. These spacers act as mediators between the color filter substrate and TFT substrate, providing structural support while preventing direct contact that would cause touch defects. The spacers are positioned to maintain optimal distance, resolving the contradiction between stability and brightness uniformity.
3Strength
If optical adhesive is applied to entire surface for glass bonding type lamination, then adhesion strength is improved, but manufacturing complexity increases due to multiple process steps
Solution Approach 1:
The patent segments the bonding process into two distinct stages: first, precision alignment bonding using a small amount of adhesive at specific positions to establish accurate registration; second, full-surface bonding using optical adhesive to provide strong adhesion. This segmentation allows each stage to fulfill its specific function optimally, resolving the contradiction between adhesion strength and manufacturing complexity by breaking down the complex process into manageable, function-specific steps.
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 prevents the yellowish phenomenon by ensuring uniform transmittance and maintaining the cell gap, reducing the likelihood of cold bubble and gravity defects, and enhancing the display quality by maintaining the adhesion force between substrates.
Implementation Method 1
an optical adhesive is formed on an entire surface of a liquid crystal panel to couple a touch sensor substrate to the liquid crystal panel
Implementation Method 2
a liquid crystal layer between the first substrate and the second substrate
Data Source
AI summary
Disclosed is a touch screen liquid crystal display device (LCD) that includes a first substrate that includes a plurality of pixels defined by crossings of gate lines and data lines, each pixel including a thin film transistor; a second substrate that includes a color filter and a black matrix; a liquid crystal layer between the first substrate and the second substrate; a plurality of gap column spacers on the second substrate and contacting the first substrate; a press column spacer on the second substrate and spaced apart from the first substrate; and a third substrate attached to the second substrate, wherein the plurality of gap column spacers have a density of 0.05% to 0.11% with respect to a display region of the first substrate.