Unconnected Paired Plate Capacitive Coupling for Touch Detection
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Solution Overview
Problem
Current touch detection and communication technologies face challenges in accurately sensing touch and secure device authentication, particularly in environments with high noise immunity and proximity-based access control, where existing methods struggle with parasitic capacitance and reliability.
Innovation Solution
A circuit employing unconnected paired plate capacitive coupling with edge sources and charge sensors for touch detection and communication, using differential edges and coherent sensing to encode and decode information, and incorporating out-of-band timing synchronization or in-band signaling for secure authentication.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If traditional touch detection methods are used, then device complexity is reduced, but measurement precision deteriorates due to parasitic capacitance interference
Solution Approach 1:
The touch detection function is divided into two separate devices: a transmitter device with plate pairs for generating electric fields, and a receiver device with charge sensors for detecting touch-induced charge changes. This segmentation isolates the sensing function from parasitic capacitance sources, improving measurement precision while maintaining manageable device complexity through functional specialization.
Solution Approach 2:
The patent introduces an intermediary near-field channel between unconnected plate pairs that mediates the touch detection process. The transmitter plates generate electric fields that couple through this near-field channel to the receiver plates, allowing touch detection without direct electrical connection and thereby eliminating parasitic capacitance interference while preserving measurement precision.
2Reliability
If unconnected paired plate capacitive coupling is used, then measurement precision improves by minimizing parasitic capacitance, but device complexity increases due to multiple plates and sensors
Solution Approach 1:
The unconnected paired plate structure serves multiple functions: it generates electric fields for touch detection, establishes near-field coupling channels, and provides inherent parasitic capacitance isolation. This multi-functionality improves reliability by addressing multiple requirements simultaneously while avoiding the need for additional separate components, thereby managing device complexity.
Solution Approach 2:
The patent employs differential signaling with balanced plate pairs where opposite plates are driven with complementary signals. This creates equipotential regions that cancel out parasitic capacitance effects, improving reliability by eliminating interference sources while maintaining a relatively simple circuit topology through symmetric design.
3Adaptability or versatility
If differential edges are applied between plate pairs, then communication capability is enabled, but loss of information increases due to noise in the near field channel
Solution Approach 1:
The patent implements coherent sensing with timing synchronization where the receiver correlates incoming signals with known transmitted waveforms. This feedback mechanism allows the system to distinguish signal from noise by comparing expected patterns with actual received signals, enabling communication capability while maintaining signal integrity through noise rejection.
Solution Approach 2:
The system uses periodic differential edge transmission with synchronized timing between transmitter and receiver. By transmitting signals at regular, predictable intervals and correlating with these periodic patterns at the receiver, the system enables reliable communication while filtering out aperiodic noise, thus preserving information integrity.
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 solution enables reliable touch detection and secure device authentication by minimizing parasitic capacitance effects and ensuring secure communication, even in noisy environments, with applications in fencing, secure access, and other capacitive sensing scenarios.
Implementation Method 1
unconnected paired plate capacitive coupling
Implementation Method 2
near field channel formed between the plates
Implementation Method 3
charge sensor coupled therebetween
Implementation Method 4
coherently sensing an imbalance in a near field channel
Data Source
AI summary
There is provided herein circuitry and methods for applications including touch detection and, in embodiments, low rate communication such as for secure device authentication. The method uses a circuit having a first device having a first pair of unconnected plates and an edge source coupled therebetween. The circuit further comprises a second device having a second pair of respective unconnected plates and a charge sensor coupled therebetween. The method for touch detection comprises applying at least one differential edge between the first pair of unconnected plates using the edge source and detecting touch by coherently (i.e. in time) sensing an imbalance in a near field channel formed between the plates and an output signal of the charge sensor. The present method/circuit has various applications including for touch detection in fencing and secure device authentication employing both touch detection and bidirectional cryptographic communication between key and secure devices.