Single-Layer Projected Capacitive Touch Sensor Bridging Areas
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Solution Overview
Problem
Existing single-layer projected capacitive touch sensors with independent-matrix sense elements face challenges in reducing the width of the bezel and balancing node capacitances, leading to sensitivity issues and design complexities, especially in large-size or high-resolution touch panels.
Innovation Solution
A single-layer projected capacitive touch sensor with two bridging areas is designed, where driving electrodes are divided into two groups connected to contacts in separate bridging areas, and signal wires of the common sensing electrodes intersect with driving electrodes in one area, while extending portions of the sensing electrodes intersect signal wires in the other area, balancing capacitance and reducing bezel width.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If all sensing electrodes and driving electrodes are arranged on a single conductive layer with numerous contacts at peripheral position, then the touch sensor can achieve basic sensing function, but the flexible flat cable size becomes large and contact reliability deteriorates
Solution Approach 1:
The patent divides the single conductive layer into multiple conductive layers (first conductive layer and second conductive layer). Sensing electrodes are arranged on the first conductive layer while driving electrodes are arranged on the second conductive layer. This segmentation reduces the number of contacts required at peripheral positions and improves contact reliability by distributing connections across multiple layers.
2Area of stationary object
If a bridging area framework is used to arrange contacts at peripheral position and cover with insulation film, then the quantity of contacts and signal wires can be decreased, but the bezel width cannot be effectively reduced for large size or high resolution touch panels
Solution Approach 1:
The patent introduces a second conductive layer stacked above the first conductive layer, utilizing the vertical dimension (z-axis) to arrange driving electrodes. This multi-layer approach allows signal wires to be routed more efficiently and reduces the horizontal space required in the bezel area, effectively narrowing the bezel width for large size or high resolution touch panels.
3Area of stationary object
If two bridging areas are separately arranged at two opposite sides with driving electrodes divided into two groups, then the number of signal wires can be distributed to narrow bezel width, but signal wires of common sensing electrodes must pass through one bridging area causing unbalanced capacitances
Solution Approach 1:
The patent assigns different functions to different conductive layers: the first conductive layer is dedicated to sensing electrodes with their signal wires passing through both bridging areas, while the second conductive layer is dedicated to driving electrodes. This local quality differentiation ensures that sensing signal wires are symmetrically distributed across both bridging areas, maintaining balanced capacitances while still achieving narrowed bezel width.
4Manufacturing precision
If signal wires of common sensing electrodes pass through one bridging area and insulatively intersect signal wires of driving electrodes, then capacitance nodes are formed, but obvious capacitance difference between two bridging areas weakens touch panel sensitivity
Solution Approach 1:
The patent segments the signal wire routing by conductive layer: sensing electrode signal wires on the first conductive layer pass through both bridging areas symmetrically, while driving electrode signal wires on the second conductive layer are routed separately. This segmentation ensures that capacitance nodes are evenly distributed across both bridging areas, maintaining balanced capacitances and preserving touch panel sensitivity.
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 effectively reduces the bezel width, balances capacitance in both bridging areas, and enhances the sensitivity and design simplicity of the touch panel by distributing signal wires and ensuring consistent capacitance across the touch sensor.
Implementation Method 1
the signal wires RX passing through the bridging area insulatively intersect the signal wires TX of the driving electrodes to form capacitive nodes
Data Source
AI summary
A capacitive touch sensor includes sensing columns. Each sensing column has a common sensing electrode and driving electrodes. The driving electrodes are divided into two groups, which are connected to contacts in two bridging areas through electrode wires. Each bridging area is covered by an insulation film with through holes corresponding to the contacts. Signal wires of the driving electrodes pass through the through holes to connect the contacts of the driving electrodes of the sensing columns, which are located in a line, to form a signal channel. The signal wires connecting the common sensing electrodes pass through one of the two bridging areas and insulatively intersect the signal wires of the driving electrodes of the signal channel. Electrode extending portions of the common sensing electrodes are extended to the other bridging area to insulatively intersect signal wires of the driving electrodes of the signal channel.