Touch Sensor Array Multiple Presence Resolution
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Solution Overview
Problem
Current touch sensor devices, such as touchpads and touch screens, are unable to resolve the location of multiple simultaneous touches, often confusing actual touches with 'ghost' touches when they occur simultaneously, limiting their ability to detect and differentiate between multiple positions accurately.
Innovation Solution
A capacitive sensing method that processes capacitive 'image' data to logically group and weigh sensor element activations, allowing for the resolution of multiple simultaneous touches by calculating the center of mass in a 3D space, enabling the differentiation between actual and invalid touch locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If multiple sensor elements are coupled together in rows and columns to detect touches, then the sensor array can detect the presence of conductive objects, but the system cannot resolve the location of multiple simultaneous touches
Solution Approach 1:
The patent divides the sensor array into independent sensor elements that can be individually processed. Each sensor element is treated as a separate data point in the capacitive image, allowing the system to distinguish between multiple simultaneous touches by analyzing the distribution of activated sensor elements across the array.
Solution Approach 2:
The patent introduces a third dimension by creating a capacitive image representation that maps sensor activations in two-dimensional space. This visual representation allows the system to resolve multiple simultaneous touches by analyzing the spatial distribution of activated sensor elements, transforming the problem from one-dimensional signal processing to two-dimensional image analysis.
2Measurement precision
If the system processes capacitive data to resolve multiple touches, then touch location accuracy improves, but position-report latency increases
Solution Approach 1:
The patent performs preliminary processing by continuously scanning and building the capacitive image representation in the background. The system pre-processes sensor data to identify and group activated sensor elements before final touch location determination is needed, allowing for faster response times when touch events are detected.
Solution Approach 2:
The patent maintains continuous processing of the sensor array to build and update the capacitive image representation. This continuous action ensures that the system always has current spatial information ready, allowing for rapid touch location determination without significant latency increases, as the processing workload is distributed over time rather than concentrated at moment of touch.
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 enables the accurate detection and reporting of multiple simultaneous touch positions without increasing position-report latency, even with slightly longer scan times, effectively distinguishing between actual and ghost touches.
Implementation Method 1
One type of touchpad operates by way of capacitance sensing utilizing capacitance sensors. The capacitance detected by a capacitance sensor changes as a function of the proximity of a conductive object to the sensor.
Data Source
AI summary
An apparatus for and method of resolving multiple presences over a touch sensor are described. The method includes logically grouping data from a touch sensor array in order to convert the data into X-Y coordinates.