US 4,940,966 A · Article detection and/or recognition using magnetic devices

Abstract

This application discloses a method of recognizing and/or locating preselected categories of articles, which comprises applying to the articles a plurality of magnetic elements in predetermined associations (e.g. with predetermined numbers of magnetic elements and with predetermined spacings between said elements), whereby when the articles are caused to move relative to a predetermined interrogating magnetic field, each particular association of magnetic elements gives rise to a magnetic signature whereby the article or category of article carrying each of the predetermined associations can be recognized and/or located. A series of tags or markers for use in such a method, as well as a system for determining the location and/or identity of an article within an article conveying network, are also disclosed. Typically, one of such a series of tags will have a plurality of magnetic elements (2, 3, 4, 5, 6, 7, 8, 9, 10) whose individual magnetic characteristics, and whose number, shape, location and orientation on a substrate, determine the individual character of the magnetic response of the tag. By varying one or more of these parameters, a large family of magnetically individually recognizable tags can be generated.

Claims6

Dependent claims

A method of recognising and/or detecting an article at a given point in the course of its movement from a first location to a second location, which comprises securing to said article while it is at said first location a magnetic device which comprises a plurality of magnetic elements in a predetermined association (e.g. with predetermine numbers of magnetic elements and with predetermined spacings between said elements), at least one of said magnetic elements being a soft magnetic material with low coercivity, high intrinsic permeability and low or zero magnetostriction, and at least one other of said magnetic elements being a semi-hard magnetic material;

subjecting the article carrying said magnetic device to a predetermined interrogating magnetic field at said given point and observing the interaction between the interrogating field and the magnetic device carried by the article;
deducing from said observed interaction the nature of the article;
and allowing the article to travel from said given point to said second location;
said first location being a point of access to an underground pipe system and said given point being a site where said pipe system itself is accessible but where the contents of said pipe system are inaccessible.

1 more element

A method of recognising and/or locating and/or detecting an article in an underground pipe system, which comprises:

(1) positioning said article at a known, accessible first position;
(2) fixing to said article while it is at said first position a magnetic device which comprises a plurality of magnetic elements in a predetermined association (e.g. with predetermined numbers of magnetic elements and with predetermined spacings between said elements), at least one of the magnetic elements being a soft magnetic material with low coercivity, high intrinsic permeability and low or zero magnetostriction, and at least one other of said elements being a semi-hard magnetic material;
(3) subjecting the article carrying said magnetic device to a predetermined interrogating magnetic field while it is at said first position and observing the interaction between the interrogating field and the magnetic device carried by said article to determine the magnetic signature of the combination of said article and said magnetic device;
and
(4) after said article has been introduced into said underground pipe system, and when it is desired to recognise and/or locate an/or detect said article within the underground pipe system, subjecting a portion of said underground pipe system to said predetermined interrogating field in order to detect the presence or absence of said magnetic signature.

2 more elements

Dependencies are inferred from the claim text.

Article detection and/or recognition using magnetic devices

Life of this patent

Article detection and/or recognition using magnetic devices

Life of this patent

Abstract

Claims6