Multi-Touch Sensing with Capacitive Circuit Innovations
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Summary
Problems
Existing capacitive sensing technologies in user interfaces, such as touch screens and pads, cannot resolve multiple touches or simultaneous presses, limiting their ability to accurately detect and respond to multiple input points on the interface.
Innovation solutions
The implementation of a capacitive sensing apparatus with interpolating circuitry, multiplexing circuitry, and a pseudo random signal generator, which allows for the detection of changes in capacitance across individual capacitors, enabling multi-touch sensing by identifying the nearest capacitor to an input object and reducing interference from neighboring circuits.
TRIZ Analysis
Specific contradictions:
General conflict description:
Principle concept:
If traditional capacitive sensing circuits are used to detect touch positions, then single touch detection is achieved, but multiple simultaneous touches cannot be resolved
Why choose this principle:
The touch sensing array is segmented into multiple independently controllable capacitor groups, allowing individual addressing and measurement of each capacitor's state. This segmentation enables the system to distinguish between multiple simultaneous touches by measuring capacitance changes at different spatial locations independently.
Principle concept:
If traditional capacitive sensing circuits are used to detect touch positions, then single touch detection is achieved, but multiple simultaneous touches cannot be resolved
Why choose this principle:
The system employs periodic charging and discharging cycles of capacitors in a time-division multiplexed manner. By sequentially activating different capacitor groups and measuring their discharge rates, the system can resolve multiple simultaneous touches through temporal separation of measurements, achieving both multi-touch capability and measurement precision.
Application Domain
Data Source
AI summary:
The implementation of a capacitive sensing apparatus with interpolating circuitry, multiplexing circuitry, and a pseudo random signal generator, which allows for the detection of changes in capacitance across individual capacitors, enabling multi-touch sensing by identifying the nearest capacitor to an input object and reducing interference from neighboring circuits.
Abstract
A method and apparatus varying, by interval, a frequency of a drive signal applied to one electrode of each of a plurality of electrode pairs, select a frequency corresponding to the frequency of the drive signal, monitor changes in capacitance of each of the electrode pairs through receive signals at the selected frequency, from the other electrode of each of the plurality of electrode pairs; and determine a position of at least two objects, which are simultaneously on a touch device, according to the monitored capacitance changes.