RFID Tag Magnetic Field Sensing for Location Tracking

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Solution Overview

Problem

RFID systems face challenges in accurately determining the location of RFID tags due to interference and obstructions, which hinder effective tracking and inventory management in retail environments.

Innovation Solution

Incorporating a magnetic signal transmitter and a magnetic field sensing device in RFID tags, allowing the RFID scanner to determine the distance of the tag from the transmitter based on the strength of the magnetic signal, enabling precise location tracking and triggering of RFID logic operations.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If RFID scanners transmit interrogatory signals to RFID tags, then inventory tracking and loss prevention functions are enabled, but the scanners cannot accurately determine the location of RFID tags due to signal interference and obstructions

Engineering Contradiction:

Improvelocation determination accuracyVSAvoidsignal interference and obstructions

Core Design Contradiction:

Measurement precisionVSObject-affected harmful factors

Solution Approach 1:

The patent introduces magnetic field sensing devices as intermediary components within RFID tags. These devices sense magnetic signals from transmitters and report the signal strength to RFID scanners, serving as a mediator that bypasses the interference and obstructions affecting direct RFID communication for location determination.

Inventive Principle:

Principle #24Intermediary (Mediator)

Solution Approach 2:

The patent replaces the reliance on RFID radio frequency signals (which are affected by interference and obstructions) with magnetic field sensing. The magnetic field sensing devices detect magnetic signal strength, providing a more reliable basis for location determination that is less susceptible to environmental interference.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

2Measurement precision

If RFID scanners continuously transmit interrogatory signals to track tag positions, then location tracking capability is improved, but energy consumption and system complexity increase

Engineering Contradiction:

Improvetag position tracking capabilityVSAvoidscanner energy consumption

Core Design Contradiction:

Measurement precisionVSUse of energy by moving object

Solution Approach 1:

The patent implements preliminary action by having magnetic field sensing devices continuously sense magnetic signal strength and store this information in tag memory before RFID scanners need to query positions. This pre-sensing approach eliminates the need for continuous RFID signal transmission, reducing energy consumption while maintaining tracking capability.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The magnetic field sensing devices perform self-service by autonomously sensing magnetic signals, measuring signal strength, and storing location data in tag memory without requiring continuous external interrogation. This self-sufficient approach reduces the burden on RFID scanners and lowers overall system energy consumption.

Inventive Principle:

Principle #25Self-service

3Measurement precision

If RFID scanners transmit frequent interrogatory signals to ensure accurate tracking, then location accuracy is maintained, but unnecessary signal transmission increases when tags are not near point of sale

Engineering Contradiction:

Improvetag location accuracyVSAvoidsignal transmission efficiency

Core Design Contradiction:

Measurement precisionVSProductivity

Solution Approach 1:

The magnetic field sensing devices perform preliminary sensing of magnetic signal strength and store this information in tag memory before RFID scanners need to determine tag locations. This pre-captured data allows scanners to efficiently determine proximity to point of sale without transmitting unnecessary interrogatory signals when tags are not in relevant zones.

Inventive Principle:

Principle #10Preliminary action

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 enhances the accuracy of RFID tag positioning, reduces unnecessary interrogatory signal transmission, and improves inventory management and loss prevention by utilizing existing magnetic signal transmitters in retail stores.

Implementation Method 1

a magnetic field sensing device configured to receive a magnetic signal from a magnetic signal transmitter and determine a strength of the magnetic signal at the security tag

Methodology Applied

Scientific EffectMagnetic field sensing: Magnetic Field

Implementation Method 2

a radio frequency identification (RFID) device configured to receive a RFID interrogatory signal from a RFID scanner and transmit a RFID response signal, to the RFID scanner, indicating the strength of the magnetic signal

Methodology Applied

Scientific EffectRFID electromagnetic signal transmission: Electromagnetic Induction

Data Source

PatentUS11594115B2Methods and apparatuses for determining a position of a security tag

Publication Date: 2023.02.28 SENSORMATIC ELECTRONICS CORP

AI summary

Aspects of the present disclosure include methods, systems, and non-transitory computer readable media for receiving a magnetic signal from a magnetic signal transmitter, determining a strength of the magnetic signal at the security tag, receiving a radio frequency identification (RFID) interrogatory signal from a RFID scanner, and transmitting a RFID response signal, to the RFID scanner, indicating the strength of the magnetic signal.