US5017873A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Methods and apparatus employing permanent magnets for marking, locating, tracing and identifying hidden objects such as buried fiber optic cables
Assignee: Schonstedt Instrument Co LLC
•
Filing: 1990-05-18
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Granted: 1991-05-21
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Expires: 2010-05-18
Abstract
Abstract In order to locate, trace, and identify hidden elongated objects, such as buried fiber optic cables, the objects are provided with elongated permanent magnet identifier devices having magnetic fields that may be detected at a distance from the objects. In one embodiment the identifier device comprises an elongated strip magnetized in the direction of its width and formed into a long-pitch helix, producing a characteristic "magnetic field signature" that enhances detection and identification of the object, as by a portable gradiometer that is moved over the surface of the earth along a line generally parallel to the length of the object. This embodiment may provide a magnetic field that diminishes as the square of the distance from the identifier device (rather than the usual cube of the distance), thereby enabling detection at substantial distances. In a second embodiment distinctive magnetic field signatures are produced by arrays of spaced permanent magnets, the fields of which add and subtract to provide resultant magnetic fields with peaks and valleys along a line generally parallel to the length of the object.
Inventors
- 👤 John B. Rippingale
- 👤 Charles R. Upton
- 👤 Erick O. Schonstedt
- 👤 Bradley L. Osman
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 05:25
CPC Classifications
G; G01; G01V; G01V15/00; G02; G02B; G02B6/00; G02B6/46; G02B6/56; G02B6/562
Claims Analysis
Total Claims: 53
Claim 1
Independent Claim
146 words
A method of detecting an elongated object hidden at a first location, comprising providing on said object an elongated permanent magnet device with its length extending along the length of the object and magnetized transverse to its length to provide a magnetic axis transverse to the length of said object, said device having a magnetic field that varies in a predetermined manner along the length of said object to provide a characteristic magnetic field signature, the strength of said magnetic field diminishing substantially as the square of the distance from the device along a direction transverse to the length of the device; and detecting said magnetic field and said magnetic field signature by moving a magnetic field detector along the length of said object at a second location spaced transversely from said object and at which said object cannot be seen, thereby to detect said object.
Claim 2
Independent Claim
146 words
A method of detecting an elongated object hidden at a first location, comprising providing on said object an elongated permanent magnet device with its length extending along the length of the object and magnetized transverse to its length to provide a magnetic axis transverse to the length of said object, said device having a magnetic field that varies in a predetermined manner along the length of said object to provide a characteristic magnetic field signature, the strength of said magnetic field diminishing substantially as the square of the distance from the device along a direction transverse to the length of the device; and detecting said magnetic field and said magnetic field signature by moving a magnetic field detector along the length of said object at a second location spaced transversely from said object and at which said object cannot be seen, thereby to detect said object.
Claim 3
Dependent Claim
32 words
A method in accordance with claim 1, wherein said magnetic field detector is a gradiometer that detects a component of said magnetic field at different positions along the length of said object.
Claim 4
Dependent Claim
26 words
A method in accordance with claim 1, wherein said device is formed as a helix having a longitudinal axis extending along the length of said object.
Claim 5
Dependent Claim
30 words
A method in accordance with claim 3, wherein said device is formed so that the longitudinal pitch of said helix is substantially greater than the cross dimensions of said helix.
Claim 6
Dependent Claim
23 words
A method in accordance with claim 4, wherein said device is formed so that said pitch is of the order of twelve feet.
Claim 7
Dependent Claim
34 words
A method in accordance with claim 1, wherein said device is formed so that it has a width dimension substantially greater than its thickness dimension and is magnetized in the direction of its width.
Claim 8
Dependent Claim
19 words
A method in accordance with claim 6, wherein said device is formed of a strip of substantially non-conductive material.
Claim 9
Dependent Claim
18 words
A method in accordance with claim 1, wherein said device is attached to a surface of said object.
Claim 10
Dependent Claim
15 words
A method in accordance with claim 1, wherein said device is incorporated in said object.
Claim 11
Dependent Claim
39 words
A method in accordance with claim 1, wherein said object is buried beneath the surface of the earth and said detecting comprises moving said magnetic field detector over the surface of the earth in the vicinity of the object.
Claim 12
Dependent Claim
19 words
A method in accordance with claim 1, wherein said device is constituted by magnetic material dispersed within said object.
Claim 13
Dependent Claim
37 words
A method in accordance with claim 11, wherein said object is tubular and said device is magnetized width-wise of said object and so that the orientation of said magnetic axis varies along the length of the object.
Claim 14
Dependent Claim
20 words
A method in accordance with claim 1, wherein said detecting comprises sensing at least one component of said magnetic field.
Claim 15
Dependent Claim
16 words
A method in accordance with claim 13, wherein said detecting comprises indicating variations in said component.
Claim 16
Independent Claim
118 words
A method of detecting an elongated object hidden at a first location, comprising providing on said object an elongated permanent magnet device having its length extending along the length of said object and magnetized transverse to its length to provide a magnetic axis transverse to the length of said object and the orientation of which varies repetitively in a predetermined manner along the length of said object to provide a characteristic magnetic field signature; and detecting said magnetic field and said magnetic field signature by moving a magnetic field detector along the length of said object at a second location spaced transversely from said object and at which said object cannot be seen, thereby to detect said object.
Claim 17
Independent Claim
118 words
A method of detecting an elongated object hidden at a first location, comprising providing on said object an elongated permanent magnet device having its length extending along the length of said object and magnetized transverse to its length to provide a magnetic axis transverse to the length of said object and the orientation of which varies repetitively in a predetermined manner along the length of said object to provide a characteristic magnetic field signature; and detecting said magnetic field and said magnetic field signature by moving a magnetic field detector along the length of said object at a second location spaced transversely from said object and at which said object cannot be seen, thereby to detect said object.
Claim 18
Dependent Claim
50 words
A method in accordance with claim 15, wherein said device is formed as a helix having a longitudinal axis extending along the length of said object, and wherein said device is formed so that the longitudinal pitch of said helix is substantially greater than the cross dimensions of said helix.
Claim 19
Dependent Claim
34 words
A method in accordance with claim 15, wherein said device is formed so that it has a width dimension substantially greater than its thickness dimension and is magnetized in the direction of its width.
Claim 20
Dependent Claim
19 words
A method in accordance with claim 15, wherein said device is formed as a strip of substantially non-conductive material.
Claim 21
Dependent Claim
39 words
A method in accordance with claim 15, wherein said object is buried beneath the surface of the earth and said detecting comprises moving said magnetic field detector over the surface of the earth in the vicinity of the object.
Claim 22
Dependent Claim
19 words
A method in accordance with claim 15, wherein said device is constituted by magnetic material dispersed within said object.
Claim 23
Dependent Claim
21 words
A method in accordance with claim 20, wherein said object is tubular and said device is magnetized width-wise of said object.
Claim 24
Dependent Claim
32 words
A method in accordance with claim 15, wherein said magnetic field detector is a gradiometer that detects a component of said magnetic field at different positions along the length of said object.
Claim 25
Dependent Claim
112 words
A magnetic tracing device for magnetic detection of an elongated object, comprising an elongated strip of magnetic material having a width dimension substantially greater than its thickness dimension, said strip being magnetized in the direction of its width and being formed into an elongated helix to provide a magnetic axis the orientation of which varies repetitively in a predetermined manner along the length of the device, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the helix, whereby an elongated object associated with the tracing device and having its length parallel to the length of said helix may be traced.
Claim 26
Dependent Claim
112 words
A magnetic tracing device for magnetic detection of an elongated object, comprising an elongated strip of magnetic material having a width dimension substantially greater than its thickness dimension, said strip being magnetized in the direction of its width and being formed into an elongated helix to provide a magnetic axis the orientation of which varies repetitively in a predetermined manner along the length of the device, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the helix, whereby an elongated object associated with the tracing device and having its length parallel to the length of said helix may be traced.
Claim 27
Dependent Claim
13 words
A device in accordance with claim 23, wherein said strip is substantially non-conductive.
Claim 28
Dependent Claim
25 words
A device in accordance with claim 23, wherein said helix has a longitudinal pitch that is substantially greater than the cross dimensions of said helix.
Claim 29
Dependent Claim
17 words
A device in accordance with claim 25, wherein said pitch is of the order of twelve feet.
Claim 30
Dependent Claim
18 words
A device in accordance with claim 23, wherein said strip is attached to a surface of said object.
Claim 31
Dependent Claim
15 words
A device in accordance with claim 23, wherein said strip is incorporated into said object.
Claim 32
Dependent Claim
105 words
In combination with an elongated non-magnetic object to be detected magnetically, an elongated strip of magnetic material on said object, said strip having a width dimension substantially greater than its thickness dimension and being magnetized in the direction of its width, said strip being formed into an elongated helix with its length extending along the length of said object and having a magnetic field that varies in a predetermined manner along the length of said object, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the helix, whereby the object may be detected.
Claim 33
Dependent Claim
105 words
In combination with an elongated non-magnetic object to be detected magnetically, an elongated strip of magnetic material on said object, said strip having a width dimension substantially greater than its thickness dimension and being magnetized in the direction of its width, said strip being formed into an elongated helix with its length extending along the length of said object and having a magnetic field that varies in a predetermined manner along the length of said object, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the helix, whereby the object may be detected.
Claim 34
Dependent Claim
25 words
A combination in accordance with claim 29, wherein said helix has a longitudinal pitch that is substantially greater than the cross dimensions of said helix.
Claim 35
Dependent Claim
17 words
A combination in accordance with claim 29, wherein said pitch is of the order of twelve feet.
Claim 36
Dependent Claim
13 words
A combination in accordance with claim 29, wherein said strip is substantially non-conductive.
Claim 37
Dependent Claim
23 words
A combination in accordance with claim 29, wherein said magnetic material is dispersed within said object and is magnetized width-wise of said object.
Claim 38
Independent Claim
129 words
A method of detecting an elongated object hidden at a first location, comprising providing on said object an elongated permanent magnet device having its length extending along the length of said object and having a magnetic axis that is transverse to the length of said object and that varies in orientation at different positions along the length of said object to provide a magnetic field that varies in a predetermined manner along the length of said object, thereby to provide a characteristic magnetic field signature; and detecting said magnetic field and said magnetic field signature by moving a magnetic field detector along the length of said object at a second location spaced transversely from said object and at which said object cannot be seen, thereby to detect said object.
Claim 39
Independent Claim
129 words
A method of detecting an elongated object hidden at a first location, comprising providing on said object an elongated permanent magnet device having its length extending along the length of said object and having a magnetic axis that is transverse to the length of said object and that varies in orientation at different positions along the length of said object to provide a magnetic field that varies in a predetermined manner along the length of said object, thereby to provide a characteristic magnetic field signature; and detecting said magnetic field and said magnetic field signature by moving a magnetic field detector along the length of said object at a second location spaced transversely from said object and at which said object cannot be seen, thereby to detect said object.
Claim 40
Dependent Claim
44 words
A method in accordance with claim 34, wherein said object is buried beneath the surface of the earth and said detecting comprises moving said magnetic field detector over the surface of the earth along a line substantially parallel to the length of said object.
Claim 41
Dependent Claim
85 words
In combination with an elongated non-magnetic object to be detected magnetically, an elongated permanent magnet device on said object having its length extending along the length of said object, said device having a magnetic axis that is transverse to the length of said object and that has different orientations at positions along the length of said object to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the device, whereby the object may be detected.
Claim 42
Dependent Claim
85 words
In combination with an elongated non-magnetic object to be detected magnetically, an elongated permanent magnet device on said object having its length extending along the length of said object, said device having a magnetic axis that is transverse to the length of said object and that has different orientations at positions along the length of said object to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the device, whereby the object may be detected.
Claim 43
Dependent Claim
23 words
A combination in accordance with claim 36, wherein said device is helical and has a helix axis along the length of said object.
Claim 44
Dependent Claim
33 words
A combination in accordance with claim 36, wherein said device comprises a plurality of spaced strips with their lengths extending along the length of said object and being magnetized transverse to their length.
Claim 45
Dependent Claim
26 words
A combination in accordance with claim 36, wherein said device comprises a plurality of spaced tubes coaxial with the object and magnetized transverse to their length.
Claim 46
Dependent Claim
38 words
A combination in accordance with claim 36, wherein said device comprises a plurality of strips with their length extending along the length of said object at circumferentially spaced positions on said object and magnetized transverse to their length.
Claim 47
Dependent Claim
17 words
A combination in accordance with claim 40, wherein said positions are also spaced longitudinally of said object.
Claim 48
Dependent Claim
56 words
A combination in accordance with claim 36, wherein said device comprises a plurality of tubes spaced along the length of said object and having collinear axes parallel to the length of said object, each tube having a magnetic axis transverse to the length of said object, and the magnetic axes of successive tubes having different orientations.
Claim 49
Dependent Claim
16 words
A combination in accordance with claim 42, wherein each tube is defined by a helical strip.
Claim 50
Dependent Claim
98 words
A magnetic marker for magnetic detection of an elongated object, comprising an elongated strip of magnetic material that is magnetized width-wise and that is convoluted lengthwise so as to provide a magnetic field having a magnetic axis the orientation of which varies repetitively along the length of the strip in a predetermined manner, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the strip, whereby an elongated object associated with the strip and having its length parallel to the length of the strip may be detected.
Claim 51
Dependent Claim
98 words
A magnetic marker for magnetic detection of an elongated object, comprising an elongated strip of magnetic material that is magnetized width-wise and that is convoluted lengthwise so as to provide a magnetic field having a magnetic axis the orientation of which varies repetitively along the length of the strip in a predetermined manner, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the strip, whereby an elongated object associated with the strip and having its length parallel to the length of the strip may be detected.
Claim 52
Dependent Claim
108 words
An elongated magnetic marker for magnetic detection of an elongated object, said marker comprising magnetic material magnetized transverse to the length of the marker so as to have a magnetic axis transverse to its length, said marker having a convoluted magnetic field pattern in which the orientation of said magnetic axis varies repetitively along the length of the marker in a predetermined manner, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the marker, whereby an elongated object associated with the marker and having its length parallel to the length of the marker may be detected.
Claim 53
Dependent Claim
108 words
An elongated magnetic marker for magnetic detection of an elongated object, said marker comprising magnetic material magnetized transverse to the length of the marker so as to have a magnetic axis transverse to its length, said marker having a convoluted magnetic field pattern in which the orientation of said magnetic axis varies repetitively along the length of the marker in a predetermined manner, thereby to provide a characteristic magnetic field signature capable of detection by a magnetic field detector moved along the length of the marker, whereby an elongated object associated with the marker and having its length parallel to the length of the marker may be detected.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-05-20 | 1994-11-19 | 1995-05-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-05-20 | 1998-11-19 | 1999-05-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-05-20 | 2002-11-19 | 2003-05-21 | $7700.00 | Window Closed / Lapsed |