Selective Receiver Electrode Scanning for Touch Positioning
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Solution Overview
Problem
Current capacitive sensing devices face challenges in accurately determining the position of input objects within a sensing region, particularly due to the limitations in processing signals from a large number of receiver electrodes exceeding the number of hardware channels, which affects the efficiency and accuracy of object detection.
Innovation Solution
A processing system that receives signals from both sensor and receiver electrodes, measures capacitive changes, and determines the section of the sensing region where an input object is located, using a combination of absolute and mutual capacitance sensing modalities, with a multiplexer array to selectively couple receiver electrodes to hardware channels, allowing for efficient processing and position determination within the section.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If the number of receiver electrodes is increased to improve position determination accuracy, then measurement precision is improved, but device complexity increases due to exceeding hardware channel capacity
Solution Approach 1:
The sensing region is divided into multiple sections, and receiver electrodes are grouped into sets corresponding to each section. The system selectively activates only the electrode set corresponding to the section containing the input object, determined through capacitive change analysis. This segmentation allows high-resolution position detection within each section while keeping the active hardware channel count manageable.
Solution Approach 2:
The system dynamically selects which subset of receiver electrodes to activate based on the detected location of the input object. Instead of continuously monitoring all receiver electrodes, the system adapts its measurement configuration by activating only the relevant electrode subset for the current sensing task, thereby reducing instantaneous hardware requirements while maintaining measurement precision.
2Measurement precision
If signals from all receiver electrodes are processed simultaneously to improve position accuracy, then measurement precision is improved, but power consumption increases
Solution Approach 1:
The system performs partial processing by activating and processing signals from only the necessary subset of receiver electrodes corresponding to the section containing the input object, rather than processing signals from all receiver electrodes. This partial action approach achieves sufficient measurement precision for the current sensing task while significantly reducing power consumption compared to full-array processing.
3Productivity
If the sensing region is divided into sections to reduce processing load, then productivity is improved, but device complexity increases due to multiplexer requirements
Solution Approach 1:
The sensing region is segmented into multiple sections with corresponding receiver electrode sets. A multiplexer array is implemented to selectively connect the appropriate electrode set to the processing circuitry based on the detected input object location. This segmentation enables efficient signal processing by limiting the active electrode count while the multiplexer provides the necessary switching capability to manage multiple electrode sets.
Solution Approach 2:
The multiplexer array serves as an intermediary component that bridges the gap between the segmented receiver electrode sets and the processing circuitry. It dynamically routes signals from the relevant electrode subset to the available hardware channels, enabling efficient resource utilization without requiring a dedicated processing channel for every possible electrode.
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 enhances the accuracy and speed of input object positioning, improving usability and reducing power consumption by optimizing signal processing and electrode usage.
Implementation Method 1
measures a first plurality of capacitive changes based on the first plurality of resulting signals and the first sensing modality; measures a second plurality of capacitive changes based on the second plurality of resulting signals and the second sensing modality
Data Source
AI summary
A processing system, including: a sensor module that: receives, in a first sensing modality, first resulting signals from electrodes in a sensing region; and receives, in a second sensing modality, second resulting signals from a subset of receiver electrodes; and receiver hardware channels that process the second resulting signals, where the number of receiver electrodes exceeds the number of hardware channels; and a determination module that: measures a first plurality of capacitive changes based on the first resulting signals; determines, based on the first plurality of capacitive changes, the section of the sensing region in which an input object is located; selects the subset of the receiver electrodes corresponding to the section; measures a second plurality of capacitive changes based on the second resulting signals; and determines a position of the input object within the section based on the second plurality of capacitive changes.