Resonant Tank Proximity Sensing for Noise-Robust Distance Detection

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Solution Overview

Problem

Existing proximity sensors face challenges with limited physical operating range and susceptibility to ambient noise, particularly when detecting distances using ferromagnetic targets, which complicates signal detection and increases device complexity and cost.

Innovation Solution

The use of actively and passively coupled resonant tank circuits with magnetic coupling between an active sensor and a passive target, where the coupled resonant frequency response is measured to determine distance, allowing for more accurate and robust proximity sensing over larger distances with reduced noise interference.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If ferromagnetic targets are used for distance detection, then measurement capability is provided, but susceptibility to ambient noise and limited physical operating range occur

Engineering Contradiction:

Improvedistance detection accuracyVSAvoidambient noise susceptibility

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent replaces ferromagnetic target-based inductive sensing with an optical measurement system using a laser range finder. This substitution eliminates susceptibility to electromagnetic ambient noise while providing accurate distance measurement through optical time-of-flight or phase-shift methods, directly resolving the contradiction between measurement capability and noise susceptibility.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent introduces an optical intermediary (laser beam) between the sensor and target object. Instead of directly sensing ferromagnetic properties affected by noise, the system uses light as an intermediary carrier to measure distance, thereby isolating the measurement process from electromagnetic interference while extending operational range.

Inventive Principle:

Principle #24Intermediary (Mediator)

2Measurement precision

If ferromagnetic targets are used for distance detection, then measurement capability is provided, but physical operating range is limited

Engineering Contradiction:

Improvedistance detection capabilityVSAvoidphysical operating range

Core Design Contradiction:

Measurement precisionVSLength of stationary object

Solution Approach 1:

The patent replaces the short-range ferromagnetic sensing mechanism with an optical ranging system using a laser range finder. Optical measurements can accurately detect distances over much longer ranges compared to inductive sensing, thereby extending the physical operating range while maintaining measurement precision.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If complex signal detection methods are used to overcome noise, then measurement accuracy may be improved, but device complexity and cost increase

Engineering Contradiction:

Improvesignal detection accuracyVSAvoiddevice complexity and cost

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces complex signal processing requirements with a fundamentally different measurement approach using a laser range finder. By switching to optical time-of-flight or phase-shift measurement, the system achieves accurate distance detection without requiring complex noise filtering or signal enhancement circuits, thereby reducing device complexity and cost.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

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 higher measurement accuracy and finer resolution of distance detection while maintaining simplicity, effectively addressing the limitations of existing sensors by utilizing a unique electrical response that is less affected by noise, especially at larger distances.

Implementation Method 1

magnetic coupling between the first inductor and the second inductor varies as a function of physical displacement of the first inductor and the second inductor with respect to one another

Methodology Applied

Scientific EffectMagnetic coupling: Electromagnetic Induction

Implementation Method 2

active resonant tank circuit that includes an excitation source, a first capacitor, and a first inductor. The passive target includes a passive resonant tank circuit

Methodology Applied

Scientific EffectResonance: Resonance

Data Source

PatentUS9945695B2Proximity sensor

Publication Date: 2018.04.17 SIMMONDS PRECISION PRODUCTS INC

AI summary

A proximity sensor includes an active sensor, a passive target, and a measurement circuit. The active sensor includes an active resonant tank circuit that includes an excitation source, a first capacitor, and a first inductor. The passive target includes a passive resonant tank circuit that includes a second capacitor and a second inductor, where magnetic coupling between the first inductor and the second inductor varies as a function of physical displacement of the first inductor and the second inductor with respect to one another. The measurement circuit is configured to measure a coupled resonant frequency response in the active resonant tank circuit and provide a measured distance output based on the coupled resonant frequency response.