Multi-Touch Sensor Resolution Using Peak Detection
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Solution Overview
Problem
Current touch sensor devices, particularly those using capacitance sensing, are unable to resolve the location of multiple simultaneous touches, often confusing actual touches with 'ghost' touches, limiting them to detecting only a single touch at a time.
Innovation Solution
A peak detection method is employed to isolate and determine multiple centroids from data received from a multi-touch sensor device, using a dynamic threshold to maximize signal-to-noise ratio, allowing for the identification of multiple touches by calculating the sum of difference counts across sensor elements and adjusting noise and presence thresholds to distinguish valid touch locations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Quantity of substance
If a touchpad uses a matrix of rows and columns with multiple sensor elements to detect multiple touches, then the detection capability increases, but the ability to resolve the location of simultaneous touches deteriorates
Solution Approach 1:
The patent divides the sensor array into independently addressable sensor pads arranged in a matrix of rows and columns. Each sensor pad can be individually scanned and its capacitance measured, allowing the system to segment the touch detection into discrete locations. This segmentation enables the system to distinguish between multiple simultaneous touches by identifying which specific sensor pads are activated, thereby resolving the location of each touch independently.
Solution Approach 2:
The patent transitions from detecting only the presence of touches to resolving their locations by adding spatial dimensionality through the matrix arrangement of sensor pads. By organizing sensors in two dimensions (rows and columns) and scanning them systematically, the system converts touch detection from a single-dimensional presence detection into a two-dimensional location resolution problem, enabling precise identification of multiple simultaneous touch positions.
2Quantity of substance
If a touchpad detects multiple simultaneous touches, then the quantity of touch information increases, but the ability to distinguish actual touches from ghost touches deteriorates
Solution Approach 1:
The patent implements a scanning mechanism that systematically queries each sensor pad in the matrix and uses the capacitance measurements to determine which pads are activated. This feedback loop allows the system to evaluate potential touch locations and distinguish actual touches from ghost touches by verifying which sensor pads show significant capacitance changes consistent with real finger contacts, thereby improving the reliability of touch location identification.
3Device complexity
If a touchpad is configured to resolve only a single touch location, then the device complexity is reduced, but the versatility for handling multiple touches deteriorates
Solution Approach 1:
The patent designs the sensor array and scanning system to be universally applicable for detecting touches at any location on the touchpad surface. The matrix of sensor pads and the systematic scanning mechanism provide a multi-functional capability that can handle single touches, multiple simultaneous touches, and touches at various positions, making the device versatile without requiring separate specialized systems for different touch scenarios.
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 the accurate detection and resolution of multiple simultaneous touches, improving the signal-to-noise ratio and allowing for the identification of multiple touch locations, thereby enhancing the capability of touch sensor devices beyond single-touch detection.
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 centroids from data received from a multi-touch sensor device are described.