Touch Panel Wiring Electrodes for Thin Bezel Design
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Solution Overview
Problem
Existing touch panel devices with surface acoustic wave technology face challenges in reducing the bezel width while maintaining a compact size, as the arrangement of wiring electrodes along the outer rims requires a significant height to prevent increased resistance, which can lead to a thicker device.
Innovation Solution
The solution involves using silver paste with fine and large particles to form wiring electrodes and bus electrodes on a transparent substrate, with a girdle wall of zinc oxide between them to prevent migration and moisture ingress, and an acoustic absorption moisture proof layer to cover the wiring electrodes, allowing for a thinner profile and reduced bezel width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the height of wiring electrodes is increased to maintain cross-sectional area and prevent resistance increase, then electrical resistance is reduced, but device thickness increases
Solution Approach 1:
The patent transitions from a single-layer thick wiring electrode structure to a multi-layer stacked structure. The first wiring electrode layer is formed with a first pattern, and a second wiring electrode layer is formed with a second pattern on top, allowing current to flow through multiple layers in parallel. This dimensional change from 2D to 3D electrode arrangement reduces resistance without increasing the horizontal footprint, thereby enabling thinner device profiles while maintaining electrical performance
Solution Approach 2:
The wiring electrode system is divided into multiple separate layers (first wiring electrode layer and second wiring electrode layer) rather than using a single thick layer. Each layer can be independently patterned and optimized, with the combined effect of multiple thinner layers providing equivalent or superior electrical conductivity to a single thick layer, thus reducing the need for increased individual layer thickness
2Area of stationary object
If the width of bezel portion is reduced to achieve compact size, then device compactness is improved, but space for wiring electrodes and transducers is reduced
Solution Approach 1:
The patent utilizes the vertical dimension by stacking wiring electrode layers to provide sufficient cross-sectional area for current flow within a reduced horizontal footprint. This allows the bezel width to be minimized while maintaining adequate electrical conductivity through the multi-layer configuration, effectively trading horizontal space for vertical arrangement
Solution Approach 2:
Different regions of the wiring electrode system are assigned different functions and structures. The first wiring electrode layer and second wiring electrode layer are positioned at different locations and have different patterns, with each layer optimized for its specific role in the electrical connection system. This localized optimization allows efficient use of limited bezel space while maintaining overall system functionality
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 approach enables a significant reduction in bezel width without increasing the device thickness, while also preventing migration and corrosion, thus enhancing the efficiency and reliability of the touch panel device.
Implementation Method 1
Each of the transducers has a piezoelectric thin film, a plate electrode disposed at one surface of the piezoelectric thin film and a comb-like electrode disposed at the other surface of the piezoelectric thin film
Implementation Method 2
transducers that are arranged at four sides of the touch area for emitting or receiving the surface acoustic wave. When a finger or the like touches the touch area, the touch position is detected in accordance with the attenuation position of surface acoustic wave
Implementation Method 3
a girdle wall of zinc oxide between them to prevent migration and moisture ingress
Implementation Method 4
an acoustic absorption moisture proof layer to cover the wiring electrodes
Data Source
AI summary
Each of transducers of a touch panel device includes a piezoelectric thin film, a plate electrode disposed at one surface of the piezoelectric thin film and a comb-like electrode disposed at the other surface of the piezoelectric thin film. The comb-like electrode has a plurality of comb-like electrode fingers and a linear bus electrode to which one end of each of the plural comb-like electrode fingers is connected. A plurality of wiring electrodes is provided at the outer side of any of the transducers in parallel with the bus electrode of the transducer and is connected to the bus electrode and the plate electrode of any of the transducers. Each of the wiring electrodes includes an electrode base portion formed by printing silver paste containing fine particles on the substrate and an electrode main body formed by printing silver paste containing large particles and fine particles in a mixed manner on the electrode base portion.