Touch Panel Assistant Lines Reduce Resistance
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Solution Overview
Problem
Conventional capacitive touch panels face a trade-off between sensitivity and transmittance, as increasing the thickness of sensing pads to reduce resistance leads to decreased transmittance, and existing solutions either compromise on sensitivity or complicate manufacturing processes.
Innovation Solution
Incorporating assistant lines with lower resistance than the sensing pads, made of metal such as aluminum or molybdenum, which are positioned within the sensing pads and connected to the existing connecting lines, reducing the overall resistance while maintaining superior transmittance by limiting their width and aligning them with the black matrix pattern of the display panel.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the thickness of sensing pads is increased to reduce resistance, then the resistance is reduced, but the transmittance is deteriorated
Solution Approach 1:
The sensing pad is segmented into two functional parts: a transparent conductive material (ITO) layer for maintaining transmittance and a metal assistant line layer for providing low resistance. This segmentation allows each part to optimize its function without compromising the other.
Solution Approach 2:
The sensing pad uses a composite structure combining transparent conductive material (ITO) and metal assistant lines. This composite material approach enables simultaneous achievement of high transmittance from the ITO layer and low resistance from the metal assistant lines, resolving the trade-off between these two properties.
2Area of stationary object
If the length of sensing strings is increased to cover larger touch panel area, then the coverage area is expanded, but the line resistance is increased
Solution Approach 1:
The metal assistant lines act as intermediary elements that bridge the ITO sensing pads and reduce the overall resistance of long sensing strings. These assistant lines are positioned between the ITO layers and connect to the driving lines, providing low-resistance pathways that enable large-area coverage without excessive resistance.
3Reliability
If metal assistant lines are added to reduce resistance, then the resistance is reduced, but the manufacturing process becomes more complicated
Solution Approach 1:
The metal assistant lines are merged with the ITO sensing pad fabrication process. Both layers are formed using the same photolithography and deposition sequences, with the assistant lines being patterned simultaneously with the ITO sensing pads. This merging approach reduces manufacturing complexity by avoiding separate processing 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
The solution effectively reduces the resistance of the touch panel, enhancing sensitivity while preserving high transmittance and maintaining the aperture ratio of the display panel, thus addressing the limitations of existing technologies.
Implementation Method 1
The assistant lines are electrically connected to the two adjacent first connecting lines... The first connecting lines are electrically connected to portions of the sensing pads in series... The assistant lines reduce the resistance of the first sensing strings
Implementation Method 2
The first sensing pads and the second sensing pads include transparent conductive material such as indium tin oxide (ITO)... the transmittance of the touch panel is deteriorated when increasing the thickness
Data Source
AI summary
A touch panel disposed on a display panel includes a substrate, a plurality of first sensing strings and second sensing strings, and a plurality of assistant lines. The first sensing strings and the second sensing strings include sensing pads, a plurality of first connecting lines and a plurality of second connecting lines. The first connecting lines are parallel to a first direction and electrically connected to portions of the sensing pads in series to construct the first sensing strings. The second connecting lines are parallel to a second direction and electrically connected to the other portions of the sensing pads in series to construct the second sensing strings. The first and the second sensing pads are coplanar. The first connecting lines are electrically insulated from the second connecting lines. The assistant lines are positioned within an area of the sensing pads. The assistant lines directly contact with the sensing pads.