Capacitive Button Input Classification via Electrode Signal Ratios
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Solution Overview
Problem
Existing input devices, such as capacitive buttons, struggle to accurately differentiate between a finger hovering over the button and a stylus contacting the button due to similar capacitive responses, leading to potential unintended activation.
Innovation Solution
The input device employs a processing system that drives a capacitive sensing signal onto multiple sensor electrodes and receives resulting signals, using a ratio between these signals to determine whether the input object is contacting or hovering over a zero-dimensional sensing region, thereby distinguishing between different types of user interactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a single capacitive sensing signal is used to detect input objects, then the detection process is simple, but the ability to differentiate between hovering and contacting objects is insufficient
Solution Approach 1:
The sensing region is divided into multiple sensing zones (first sensing region and second sensing region) with different electrode configurations. The first plurality of sensor electrodes detects positional information in the first sensing region, while the second plurality of sensor electrodes detects presence in the second sensing region. This segmentation allows the system to differentiate between hovering and contacting states by comparing signals from different regions.
Solution Approach 2:
The patent introduces a vertical dimension to capacitive sensing by stacking sensor electrodes at different depths or positions. The first plurality of sensor electrodes and second plurality of sensor electrodes are arranged in different spatial layers, creating a three-dimensional sensing structure. This dimensional addition enables the system to distinguish between objects at different distances (hovering vs. contacting) that would appear identical in a single-plane sensing system.
2Measurement precision
If multiple sensor electrodes are used to improve detection accuracy, then classification precision improves, but the device complexity increases
Solution Approach 1:
The processing system is segmented into specialized modules: a sensor module that manages multiple sensor electrodes and a determination module that processes signals. The sensor module operates the first plurality of sensor electrodes for positional detection and the second plurality of sensor electrodes for presence detection. This modular segmentation simplifies the overall system architecture by dividing complex processing tasks into manageable functional units.
Solution Approach 2:
The patent uses a ratio comparison approach that requires only partial signal processing. Instead of analyzing all possible signal parameters from multiple electrodes, the determination module calculates a simple ratio between the first resulting signal and the second resulting signal. This partial action (using only the ratio metric) achieves effective classification while minimizing processing complexity.
3Area of stationary object
If capacitive sensing is used to detect input objects, then the detection range is extended, but the ability to distinguish contact from hover is compromised
Solution Approach 1:
The sensing region is segmented into a first sensing region overlapping the display and a second sensing region with different detection characteristics. The first plurality of sensor electrodes covers the first sensing region for positional information, while the second plurality of sensor electrodes covers the second sensing region for presence detection. This spatial segmentation allows the system to maintain broad sensing coverage while achieving precise contact versus hover differentiation through region-specific signal analysis.
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 accurate classification of user interactions, preventing false activations and ensuring that the button is only activated when the user intends to do so, by utilizing the distinct capacitance ratios between different sensor electrodes.
Implementation Method 1
operate the second plurality of sensor electrodes to detect a presence of the input object in a second sensing region by driving a capacitive sensing signal to detect the input object onto a first electrode and a second electrode of the second plurality of sensor electrodes
Data Source
AI summary
Embodiments of the invention generally provide an input device that includes a zero-dimensional button that detects whether an input object is proximate to a sensing region. However, different input objects may provide similar responses which may prevent the input device from accurately determining whether the user actually intended to activate the button. In one embodiment, the input device drives a capacitive sensing signal onto a sensor electrode in the capacitive button and measures at least two resulting signals. The input device then derives capacitance values based on the two resulting signals and uses a ratio between the capacitance values to classifying the interaction with the input object. This ratio enables the input device to distinguish between events that have similar capacitive responses and would otherwise be indistinguishable if only one resulting signal were measured.