EP0924719A2 - Anordnung zur Erzeugung von Magnetfeldern - Google Patents

Anordnung zur Erzeugung von Magnetfeldern Download PDF

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Publication number
EP0924719A2
EP0924719A2 EP98310054A EP98310054A EP0924719A2 EP 0924719 A2 EP0924719 A2 EP 0924719A2 EP 98310054 A EP98310054 A EP 98310054A EP 98310054 A EP98310054 A EP 98310054A EP 0924719 A2 EP0924719 A2 EP 0924719A2
Authority
EP
European Patent Office
Prior art keywords
magnetic field
coils
current carrying
magnetic
current
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP98310054A
Other languages
English (en)
French (fr)
Other versions
EP0924719A3 (de
Inventor
Michael John Sellers
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tesla Engineering Ltd
Original Assignee
Tesla Engineering Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from GBGB9726662.1A external-priority patent/GB9726662D0/en
Priority claimed from GBGB9811846.6A external-priority patent/GB9811846D0/en
Application filed by Tesla Engineering Ltd filed Critical Tesla Engineering Ltd
Publication of EP0924719A2 publication Critical patent/EP0924719A2/de
Publication of EP0924719A3 publication Critical patent/EP0924719A3/de
Withdrawn legal-status Critical Current

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Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01F—MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES
    • H01F7/00—Magnets
    • H01F7/06—Electromagnets; Actuators including electromagnets
    • H01F7/20—Electromagnets; Actuators including electromagnets without armatures

Definitions

  • This invention relates to apparatus for generating magnetic fields.
  • the apparatus has been designed for use in the manufacture of the so-called hard disks of computers, but its use is not limited to such an application.
  • Modem computers use what are known as hard disks as the bulk data storage medium. Such disks are typically round and have a diameter of approximately 15cm and a thickness of about 1mm.
  • magnets are used to create magnetic fields in the material of the disks. Typically such magnets create magnetic fields of 100 Gauss in the plane of the disk and such fields have a uniformity of about +/- 10% over the volume of the disks. That is to say if B y is the main direction of the magnetic field then B y may vary by +/- 10% and B x and B z are each less than 10% of B y . This is illustrated diagrammatically in Figure 1 of the drawings.
  • Magnets exist which can produce a uniform field in a single direction and such magnets are well known.
  • mechanical machinery to physically rotate the magnet or the disk being magnetised.
  • mechanical machinery is relatively expensive and bulky. It can also be unreliable and needs regular servicing.
  • the magnet has to be integrated into a complex piece of machinery within a high vacuum vessel and this leads to difficulties in servicing.
  • the machinery tends to produce particular matter and this can contaminate the disk being produced.
  • An object of the present invention is to provide a magnetic field generating apparatus, which does not suffer from such problems.
  • apparatus for generating a magnetic field comprising a plurality of elongate members, each formed of magnetic or magnetisable material and arranged in a predetermined configuration relative to a volume within which the magnetic field is to be produced, each elongate member carrying first and second current carrying coils, the arrangement being such that when said first current carrying coils are energised, a magnetic field is produced in a plane generally orthogonal to the axis of the elongate members, said magnetic field being in a first direction, and when said second coils are energised a magnetic field is produced in said plane, said magnetic field having a second direction different from said first direction.
  • a magnetic field can be produced, which field can be switched between a first direction and a second direction.
  • the first and second directions will be generally orthogonal.
  • the apparatus may include means for controlling the switching of the first and second sets of coils to produce the appropriate field direction.
  • the elongate members may have a uniform length. Alternatively the elongate members may have different lengths.
  • the elongate members may be mounted upon a base plate.
  • the base plate may be profiled in such a way as to enhance one or more characteristics of the magnetic field.
  • Each elongate member may carry a further current carrying coil or coils, which are energisable to enhance a characteristic or characteristics of the magnetic field being generated.
  • the apparatus may also include additional soft or permanent magnetic materials so arranged as to enhance a characteristic or characteristics of the magnetic fields.
  • the present apparatus can also be used to produce a magnetic field which rotates.
  • a sinusoidal signal is applied to the first ad second current carrying coils such that the signal applied to the first coils is 90° out of phase relative to the signal applied to the second coils. This arrangement produces a magnetic field which rotates.
  • magnetic field generating apparatus in accordance with a embodiment of the present invention comprises a square base plate 10.
  • the perimeter portion of the base plate 10 is configured to define a plurality of circular recesses 12, which can receive the lower end of a corresponding plurality of upright bobbins 14.
  • These Bobbins are elongate pin-like members and formed from magnetic or magnetisable materials such as magnetic steel. In the particular embodiment forty such bobbins are employed, ten along each side of the square, but it will be appreciated that this number can vary widely.
  • Each bobbin carries a first current carrying coil and second current carrying coil.
  • the first current carrying coils will be referred to as the X coils and the second current carrying coils as the Y coils. All the X coils are connected in series and similarly all the Y coils are connected in series.
  • a wound bobbin is shown in more detail in Figures 3a and 3b.
  • the bobbin has two coils wound thereon each formed from copper wire which has an insulating coating formed from for example enamel. Tthe two coils are both wound in the same sense around the body and each has two layers of windings.
  • the start tail of the first coil 20 is shown at TS1 and the finish tail of the first coil is shown at TF1.
  • the start tail of the second coil 21 is shown at TS2 and the finish tail of the second coil is shown at TF2.
  • FIG. 4 The manner in which the coils 20, 21 are connected to a power supply is illustrated in Figure 4.
  • a power supply unit is shown at 22.
  • the coils along each side of the square are shown as two groups marked A to E.
  • the coil tails marked "1" in Figure 4 correspond to the tails TS1 and TF1 of Figure 3 and the tails marked "2" correspond to the coil tails TS2 and TF2 of Figure 3.
  • the + and - signs signify opposite ends of each coil.
  • connection of coils shown in Figure 4 produces a magnetic field B y in a plane coplanar with the upper surface of the bobbins.
  • Tests show that the following can be achieved by the apparatus shown in Figure 2.
  • B x @ Z 0 +86.9 to +112.7 Gauss -4.9 to +4.9 Gauss
  • B y @ Z 0 -4.9 to +4.9 Gauss +86.9 to +112.7 Gauss
  • B z @ Z 0 -10.5 to +10.5 Gauss -10.5 to +10.5 Gausss
  • the arrangement described uses forty bobbins located around the edges of a square. It will be appreciated that many other configurations of bobbins can be used. It is not necessary, for example, that the bobbins form a continuous perimeter of a regular shape such as a square. Also the bobbins shown in the drawings are of uniform length. It may be appropriate in certain instances to use bobbins of different lengths in order to achieve the required magnetic field characteristics.
  • Magnetic field characteristics can also be adjusted by appropriately profiling the base plate 10. Enhancements to the magnetic field can also be generated by providing additional soft or permanent magnets in the vicinity of the bobbins.
  • the current carrying coils are energised in such a way as to produce a magnetic field which can be switched between a first direction and a second direction.
  • the apparatus can operate in this way because the two sets of current carrying coils produce independent and orthogonal magnetic fields.

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  • Physics & Mathematics (AREA)
  • Electromagnetism (AREA)
  • Engineering & Computer Science (AREA)
  • Power Engineering (AREA)
  • Magnetic Treatment Devices (AREA)
  • Electromagnets (AREA)
  • Investigating Or Analyzing Materials By The Use Of Magnetic Means (AREA)
EP98310054A 1997-12-17 1998-12-08 Anordnung zur Erzeugung von Magnetfeldern Withdrawn EP0924719A3 (de)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
GBGB9726662.1A GB9726662D0 (en) 1997-12-17 1997-12-17 Apparatus for generating magnetic fields
GB9726662 1997-12-17
GB9811846 1998-06-02
GBGB9811846.6A GB9811846D0 (en) 1998-06-02 1998-06-02 Apparatus for generating magnetic fields

Publications (2)

Publication Number Publication Date
EP0924719A2 true EP0924719A2 (de) 1999-06-23
EP0924719A3 EP0924719A3 (de) 2000-05-10

Family

ID=26312789

Family Applications (1)

Application Number Title Priority Date Filing Date
EP98310054A Withdrawn EP0924719A3 (de) 1997-12-17 1998-12-08 Anordnung zur Erzeugung von Magnetfeldern

Country Status (2)

Country Link
EP (1) EP0924719A3 (de)
JP (1) JPH11243008A (de)

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3065105A (en) * 1958-06-12 1962-11-20 Sperry Rand Corp Process and apparatus for producing magnetic material and resulting article
EP0257108A1 (de) * 1986-07-28 1988-03-02 Ibm Deutschland Gmbh Verfahren und Anordnung zur Verbesserung der Dispersion magnetischer Partikel in magnetischer Beschichtungsmasse
EP0645787A1 (de) * 1993-09-24 1995-03-29 Innovations Rayons X Et Techniques Ressuage Magnetoscopie Ixtrem Verfahren und Apparat zur Erzeugung einer oder mehrerer Magnetfeldern in eines Objekts in unterschiedliche Richtungen oder das Erzeugen zeitvariabelen Feldern

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3065105A (en) * 1958-06-12 1962-11-20 Sperry Rand Corp Process and apparatus for producing magnetic material and resulting article
EP0257108A1 (de) * 1986-07-28 1988-03-02 Ibm Deutschland Gmbh Verfahren und Anordnung zur Verbesserung der Dispersion magnetischer Partikel in magnetischer Beschichtungsmasse
EP0645787A1 (de) * 1993-09-24 1995-03-29 Innovations Rayons X Et Techniques Ressuage Magnetoscopie Ixtrem Verfahren und Apparat zur Erzeugung einer oder mehrerer Magnetfeldern in eines Objekts in unterschiedliche Richtungen oder das Erzeugen zeitvariabelen Feldern

Also Published As

Publication number Publication date
EP0924719A3 (de) 2000-05-10
JPH11243008A (ja) 1999-09-07

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