Capacitive Touch Panel Multipoint Sensing via Vertical Capacitance
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Solution Overview
Problem
Capacitive touch panels face challenges with parasitic resistance in large sizes, leading to increased response time and noise interference, which complicates and costs more to manufacture, especially for multipoint sensing applications.
Innovation Solution
A capacitive sensing method that measures voltage variations between insulated electrodes, comparing initial and touched vertical capacitance to determine touch points, allowing for rapid detection with fewer sensing circuits and reduced manufacturing costs.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Area of stationary object
If the touch panel size is increased or multipoint sensing is implemented, then the sensing coverage is improved, but the parasitic resistance in the current path increases, leading to increased response time and noise interference
Solution Approach 1:
The patent applies periodic action by using alternating current (AC) signals to drive the electrode arrays and periodically measure capacitance changes. This allows the system to overcome parasitic resistance effects by using AC coupling, where the capacitance measurement is performed at specific phases of the AC cycle, enabling multipoint sensing across large panels without excessive response time delays
Solution Approach 2:
The patent substitutes the traditional resistive touch sensing mechanism with a capacitive sensing mechanism. Instead of relying on resistive current paths that are heavily affected by parasitic resistance in large panels, the system uses capacitance changes at electrode intersections to detect touch points, fundamentally changing the sensing physics to reduce noise and improve response time
2Productivity
If the number of sensing circuits is increased to improve sensing speed and reduce noise, then the sensing performance is improved, but the circuit installation space and manufacturing cost increase
Solution Approach 1:
The patent implements universality by designing a single capacitive sensing circuit that can serve multiple functions: it can sense touch at multiple points simultaneously, handle both single-point and multipoint sensing modes, and operate across the entire electrode array. This multi-functional design eliminates the need for separate sensing circuits for each touch point, reducing circuit installation space while maintaining high sensing speed
Solution Approach 2:
The patent merges multiple sensing functions into a single integrated capacitive sensing circuit. Instead of having separate circuits for each electrode intersection or touch point, the system combines all sensing capabilities into one circuit that processes capacitance changes across the entire panel, thereby reducing overall circuit complexity and manufacturing cost while preserving sensing performance
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 method enhances sensing speed and reduces manufacturing costs by eliminating the need for extensive sensing circuitry, effectively addressing noise interference and response time issues in large capacitive touch panels.
Implementation Method 1
the capacitive sensing circuit detects the specific capacitance of a plurality of capacitors which are formed between the two electrode layers
Implementation Method 2
the parasitic resistance in the current path may affect the detection signals
Data Source
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AI summary
A multi-point sensing method applicable to a capacitive touch panel is disclosed to detect a voltage variation of every electrode patterned on two parallel electrode layers by means of a capacitive sensing circuit, and measure the vertical capacitance at the intersection crossed by the electrodes of the two electrode layers where the voltage variation is detected, and then compare the vertical capacitance thus measured with the initial vertical capacitance at the same intersection before touch, as a result, the intersection corresponding to the measured vertical capacitance may be determined as the touch point when the comparison result shows difference.