Title:
埋設ケーブルおよびパイプに永久磁気サインを行うための方法および装置
Document Type and Number:
Japanese Patent JP4323725
Kind Code:
B2
Abstract:
Ferromagnetic material of an elongated object, such as a fiber optic cable, is permanently magnetized in a manner that results in a substantially cylindrically symmetric radial external magnetic field around the object. The produced magnetization is substantially greater than natural magnetization of the ferromagnetic material by the earth's magnetic field. The radial external magnetic field varies periodically along the length of the object. If the wavelength of the periodic variations is long compared to the width (diameter) of the object, the strength of the radial external magnetic field decreases approximately inversely with distance from the object for distances that are small compared to the wavelength. The periodic magnetic field variations may have a square wave or a sine wave pattern, for example. Magnetization of the ferromagnetic material is achieved by a magnetizer having pairs of counter-rotating mirror-image magnets adjacent to an object that is moved longitudinally relative to the magnets. By virtue of the magnetization, buried objects, such as pipes and cables can be detected magnetically at substantial distances from the objects.
Inventors:
Clautier, Paul, A.
Masoruf, Timothy, Ai.
Ohm, Delbert, Earl.
Steppings, Ronald, F.
Masoruf, Timothy, Ai.
Ohm, Delbert, Earl.
Steppings, Ronald, F.
Application Number:
JP2000612967A
Publication Date:
September 02, 2009
Filing Date:
June 08, 1999
Export Citation:
Assignee:
Prairie Lands Energy Marketing, Incorporated
International Classes:
G01R33/02; H01B13/34; G02B6/00; G02B6/44; H01F13/00; H02G9/00; H02G9/02
Domestic Patent References:
| JP60107809A | ||||
| JP3101920U |
Foreign References:
| US4465140 |
Attorney, Agent or Firm:
Masao Okabe
Nobuaki Kato
Okabe
Shinichi Usui
Takao Ochi
Asahi Shinmitsu
Nobuaki Kato
Okabe
Shinichi Usui
Takao Ochi
Asahi Shinmitsu