Capacitive Touch Sensor With Resistive Yarn Nodes for Fewer Input Ports
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Solution Overview
Problem
Existing capacitive touch sensors face challenges with complex electrical connections and a high number of input ports, especially when a wide sensing area is required, making production and design costly and intricate.
Innovation Solution
A capacitive touch sensor design using electrically resistive and conductive elongated elements, such as yarns, connected to common nodes, allowing for simplified routing and reduced input ports by measuring capacitance changes through a single or dual input ports to detect touch events.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If a wide sensing area is required with traditional capacitive touch sensors, then the sensing area increases, but the number of input ports and routing complexity increases significantly
Solution Approach 1:
The patent merges multiple sensing functions into a single integrated yarn structure. The yarn contains both conductive and resistive elements that work together to detect touch events, eliminating the need for separate conductive and sensing wire networks. This consolidation reduces routing complexity while maintaining wide sensing coverage.
Solution Approach 2:
The sensing yarn performs multiple functions simultaneously: it provides electrical connection, detects capacitance changes, and determines touch position. By making the yarn multi-functional, the patent eliminates the need for separate dedicated sensing wires and input ports for each function, thereby reducing overall system complexity.
2Reliability
If traditional capacitive touch sensors are used with multiple conductive wires, then the sensing capability is achieved, but the number of input ports required increases
Solution Approach 1:
The patent segments the sensing function along the length of a single yarn rather than requiring multiple separate wires. Each segment of the yarn can independently detect touch events at different positions, allowing the system to maintain comprehensive sensing capability while using far fewer input ports.
Solution Approach 2:
The patent transitions from a two-dimensional grid of wires to a one-dimensional yarn structure. By distributing sensing elements along the length of the yarn and using the yarn's position within the fabric to provide spatial information, the system reduces the number of input ports needed while maintaining sensing coverage.
3Area of stationary object
If electrically conductive wires are arranged in a grid for wide sensing area, then the sensing coverage increases, but the production cost and complexity increase
Solution Approach 1:
The patent combines conductive and sensing functions into a single yarn type that can be integrated into the fabric using standard weaving or knitting processes. This eliminates the need for complex post-fabrication assembly of separate wire grids, significantly simplifying manufacturing while achieving wide sensing coverage.
Solution Approach 2:
The patent changes the electrical parameters of the yarn (conductive core with resistive coating) to enable both electrical connection and sensing functions. This parameter modification allows the yarn to replace multiple separate components, reducing production complexity.
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
Enables efficient detection of touch events with reduced complexity in electrical connections, supporting wide sensing areas and swipe directions without increasing the number of input ports, thus simplifying production and enhancing usability.
Implementation Method 1
measuring continuously a capacitance analog signal provided by a resistive strain gauge of the stretchable touchpad
Implementation Method 2
the voltage VIN is generated by an electronic assembly. Upon a touch by a finger and depending on the position of this touch, a certain capacitance is created between the point of contact and the ground, this capacitance being mainly linked by the resistance of rows and columns to a multiplexer
Data Source
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AI summary
It is disclosed a capacitive touch sensor (10) comprising a support layer (1) and a plurality of sensing elongated elements (2) coupled to said support layer (1), said plurality of sensing elongated elements (2) comprising a plurality of electrically resistive elongated elements (2r), wherein said plurality of electrically resistive elongated elements (2r) comprises a first set (2rx) of electrically resistive elongated elements (2r) electrically connected to a first common node (Nx) configured to be electrically connected to a first input (INx) of a detection device (5), said detection device (5) being configured to provide an output signal (S_OUT) comprising a first output value (OUTx) that is a function of the capacitance value (CRx) of said first set (2rx) of electrically resistive elongated elements (2r). An article comprising the capacitive touch sensor (10) and a method for detecting a touch event on a support layer (1) are also disclosed.