Transparent Touch Sensor Impedance Reduction
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Solution Overview
Problem
Conventional transparent conductive films, such as ITO, face limitations in both transmittance and conductivity, leading to increased impedance and signal attenuation in touch panels, particularly in larger and more compact designs.
Innovation Solution
A transparent touch sensor structure incorporating metal oxide or graphene layers with tiny conductive metal wires connecting capacitive and electromagnetic sensing strings, reducing impedance and enhancing signal transmission efficiency while maintaining high transmittance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Illumination intensity
If the transmittance of ITO film is increased, then the conductivity decreases
Solution Approach 1:
The patent uses composite transparent conductive films combining ITO with other transparent conductive materials such as zinc oxide (ZnO), aluminum zinc oxide (AZO), or aluminum indium zinc oxide (AIZO). This composite structure allows optimization of both transmittance and conductivity by leveraging the complementary properties of different materials, resolving the inverse relationship between these two parameters that plagues single-material ITO films.
Solution Approach 2:
The patent modifies the compositional parameters of the transparent conductive film by adjusting the ratios of metal elements (e.g., In:Sn:O for ITO, Zn:Al:O for AZO) and controlling deposition conditions. By changing these parameters, the film's optical and electrical properties can be tuned simultaneously to achieve high transmittance while maintaining adequate conductivity, overcoming the fixed trade-off in conventional ITO.
2Volume of moving object
If the size of touch sensing electrodes and signal paths is reduced for compactness, then the impedance increases and signal transmission deteriorates
Solution Approach 1:
The patent employs composite transparent conductive films with enhanced conductivity characteristics that allow for narrower electrode and signal path dimensions without excessive impedance increase. The improved material properties compensate for the reduced cross-sectional area, enabling compact touch panel designs while maintaining acceptable signal transmission quality.
3Reliability
If the thickness of transparent conductive film is increased to improve conductivity, then the transmittance decreases
Solution Approach 1:
The patent utilizes composite transparent conductive films that achieve the required conductivity with reduced thickness compared to conventional ITO films. By combining multiple transparent conductive materials with different properties, the film can provide sufficient electrical performance while maintaining optical transparency, thus resolving the thickness-related trade-off between conductivity and transmittance.
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 local impedance and enhances signal transmission in touch sensors, enabling better performance in large-sized touch panels with reduced material costs and improved visibility.
Implementation Method 1
the first conductive element is formed by a tiny wire made of gold, silver, copper, aluminum, molybdenum, nickel or an alloy thereof
Implementation Method 2
transmittance of visible light of the film can reach 80%
Implementation Method 3
each first capacitive sensing string is composed of first capacitive sensing units arranged in series
Implementation Method 4
the first electromagnetic antenna strings are arranged along the first direction, an end of each first electromagnetic antenna string is provided with a first electromagnetic signal contact
Data Source
AI summary
A touch sensor includes a first sensing layer, a second sensing layer and an insulative layer therebetween. Each of the first sensing layer and the second sensing layer has capacitive sensing strings and electromagnetic antenna strings. Each capacitive sensing string is composed of capacitive sensing units. The electromagnetic antenna strings are arranged. Each of the capacitive sensing strings and the electromagnetic antenna strings is connected with a tiny wire. The capacitive sensing strings on the first sensing layer are crossed with the second capacitive sensing strings on the second sensing layer to form complementary patterns. The capacitive sensing units on the first sensing layer and the second capacitive sensing units on the second sensing layer form a grid-shaped capacitive sensing unit matrix. The electromagnetic antenna strings on the first sensing layer are crossed with the electromagnetic antenna strings on the second sensing layer to form a grid-shaped electromagnetic antenna matrix.