Resonant Capacitive Touch Electrodes for Low-Crosstalk 2D Sensing
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Solution Overview
Problem
Conventional capacitive touch sensors require a large number of connections between electrodes and a controller, leading to crosstalk and increased complexity, especially in two-dimensional sensing configurations.
Innovation Solution
The implementation of resonant circuits with unique resonance frequencies for each electrode, allowing for frequency multiplexing where input signals drive all electrodes concurrently, and changes in resonance frequencies are monitored to detect touch events, reducing the need for multiple connections and enhancing sensing accuracy.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If conventional capacitive touch sensors use multiple connections between electrodes and controller for two-dimensional sensing, then sensing capability is improved, but device complexity and crosstalk increase
Solution Approach 1:
The patent assigns unique resonance frequencies to different electrode groups (rows and columns), transforming the sensing approach from spatial multiplexing to frequency multiplexing. This parameter change allows multiple electrodes to be driven concurrently without requiring separate physical connections for each electrode, reducing connection complexity while maintaining two-dimensional sensing capability.
Solution Approach 2:
The resonant circuits serve multiple functions: they act as both drive signal generators and sensing elements. By making the electrodes themselves resonant at unique frequencies, the system eliminates the need for separate drive and sense connections, reducing the overall number of connections required while enabling two-dimensional touch detection.
2Device complexity
If conventional capacitive touch sensors sequentially scan multiple channels, then device complexity is reduced, but productivity and response time decrease
Solution Approach 1:
The patent enables continuous concurrent operation of all resonant circuits by driving all electrodes simultaneously at their unique resonance frequencies. This eliminates the sequential scanning process, allowing continuous monitoring of all touch channels without time-multiplexing, thereby improving touch detection speed and responsiveness while maintaining simplified connection structure.
3Measurement precision
If conventional capacitive touch sensors use high frequency signals above 1 MHz, then measurement precision is improved, but loss of energy increases
Solution Approach 1:
The patent employs mechanical resonance of the electrode structures at their natural resonant frequencies to enhance capacitance detection. By utilizing the mechanical vibration and resonance properties of the electrodes themselves, the system achieves high measurement precision at lower energy consumption, as the resonant structures amplify the detection signal without requiring high-frequency electrical signals above 1 MHz.
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 efficient detection of touch events with reduced crosstalk and increased accuracy in two-dimensional sensing, while minimizing the number of connections required between the touch sensor panel and the controller.
Implementation Method 1
each comprising a respective electrode, the electrodes of the plurality of resonant circuits being distributed on the substrate layer; and a respective electromechanical resonator connected to the respective electrode
Implementation Method 2
the electromechanical resonators comprise one or more ceramic resonators
Implementation Method 3
When a human finger (or another conductive member) is applied over one of the electrodes, the capacitance of this electrode with respect to ground changes, and this change in capacitance is detectable
Data Source
AI summary
In a frequency multiplexed capacitive touch sensor, a plurality of resonance frequencies may be used to drive electrodes for sensing touch. A capacitive touch sensor apparatus is provided that includes a substrate layer and a plurality of resonant circuits. Each resonant circuit comprises a respective electrode and a respective electromechanical resonator connected to the respective electrode. The electromechanical resonators comprise any suitable high-Q resonator including, but not limited to: ceramic oscillators; crystal oscillators; and MEMs oscillators, as described above. The electrodes of the plurality of resonant circuits are distributed on the substrate layer. The electromechanical resonators may allow relatively close spacing of adjacent resonance frequencies, in comparison to resonant circuits with discrete inductors.