Method for increasing the operating frequency of a magnetic circuit and corresponding magnetic circuit

• US 6,940,383 B2
• Filed: 09/22/1998
• Issued: 09/06/2005
• Est. Priority Date: 09/29/1997
• Status: Expired due to Fees

• Current Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Original Assignee: Commissariat a L'Energie Atomique (AES Corporation)
• Inventors: Peuzin, Jean-Claude, Albertini, Jean-Baptiste
• Primary Examiner(s): DONOVAN, LINCOLN D
• Application Number:
  US09/508,692
• Publication Number:
  US 20020057172A1
• Time in Patent Office: 2,541 Days
• Field of Search: 336/200, 257/531, 257/277, 257/331, 438/678, 438/686, 335302-306
• US Class Current: 336/200
• CPC Class Codes: B82Y 25/00 Nanomagnetism, e.g. magnetoimpedance, anisotropic magnetoresistance, giant magnetoresistance or tunneling magnetoresistance
• CPC Class Codes: B82Y 40/00 Manufacture or treatment of nanostructures
• CPC Class Codes: G11B 5/127 Structure or manufacture of heads, e.g. inductive
• CPC Class Codes: G11B 5/17 Construction or disposition of windings
• CPC Class Codes: G11B 5/313 Disposition of layers
• CPC Class Codes: G11B 5/3183 intersecting the gap plane, e.g. "horizontal head structure"
• CPC Class Codes: H01F 17/062 Toroidal core with turns of coil around it
• CPC Class Codes: H01F 3/14 Constrictions; Gaps, e.g. air-gaps in magnetic shunt paths H01F3/12
• CPC Class Codes: H01F 41/308 lift-off processes, e.g. ion milling, for trimming or patterning
• CPC Class Codes: H01F 41/32 for applying conductive, insulating or magnetic material on a magnetic film , specially adapted for a thin magnetic film

Abstract

A process for increasing the frequency of operation of a magnetic circuit. In the process, gaps are formed in at least one section of the magnetic circuit. The gaps lower the permeability of the magnetic circuit and increase in particular the frequency of magnetic resonance and make possible the use of higher frequencies. Applications of the process include the manufacture of inductors, transformers, components, magnetic heads, etc . . .

Claims

1. A magnetic head comprising:

a bent magnetic circuit forming an air gap, said bent magnetic circuit coupled to a conductive winding; and

a plurality of gaps disposed within the bent magnetic circuit at positions perpendicular to a median line of the bent magnetic circuit generating a demagnetizing field in the bent magnetic circuit at the positions of the plurality of gaps,

wherein the plurality of gaps have a width and are spaced at a pitch to extend a frequency of operation of the magnetic head up to a resonant frequency,

wherein the resonant frequency f_r is given by relationship;

$f_r=\sqrt{C<br><br>\left(\frac{1}{{\mathrm{\mu <br><br>}}_s}+\frac{e}{p}\right)}$

in which C is a constant, μ

_s is static value of intrinsic permeability, e is the width of the plurality of gaps, and p is the pitch.

2. A magnetic circuit comprising:

a magnetic layer having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic layer being composed of a series of portions, two successive portions being separated from each other by a wall of insulating material disposed at a position perpendicular to the median line of the magnetic layer and generating a demagnetizing field in the magnetic layer at the position of said wall,

wherein each wall of insulating material has a width and is spaced at a pitch to extend a frequency of operation of the magnetic circuit up to a resonant frequency,

wherein the resonant frequency f_r is given by relationship;

$f_r=\sqrt{C<br><br>\left(\frac{1}{{\mathrm{\mu <br><br>}}_s}+\frac{e}{p}\right)}$

in which C is a constant, μ

_s is static value of intrinsic permeability, e is the width of the plurality of gaps, and p is the pitch.

3. A magnetic circuit comprising:

a magnetic layer having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic layer being composed of a series of portions, two successive portions being separated from each other by a gap disposed at a position perpendicular to the median line of the magnetic layer and generating a demagnetizing field in the magnetic layer at the position of said gap,

wherein each said gap has a width and is spaced at a pitch to extend a frequency of operation of the magnetic circuit up to a resonant frequency,

wherein the resonant frequency f_r is given by relationship;

$f_r=\sqrt{C<br><br>\left(\frac{1}{{\mathrm{\mu <br><br>}}_s}+\frac{e}{p}\right)}$

in which C is a constant, μ

_s is static value of intrinsic permeability, e is the width of the plurality of gaps, and p is the pitch.

4. A magnetic circuit comprising:

a magnetic toroid having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic toroid being composed of a series of portions, two successive portions being separated from each other by a radial gap disposed at a position perpendicular to the median line of the magnetic toroid and generating a demagnetizing field in the magnetic toroid at the position of said radial gap,

wherein each radial gap has a width and is spaced at a pitch to extend a frequency of operation of the magnetic circuit up to a resonant frequency,

wherein the resonant frequency f_r is given by relationship;

$f_r=\sqrt{C<br><br>\left(\frac{1}{{\mathrm{\mu <br><br>}}_s}+\frac{e}{p}\right)}$

in which C is a constant, μ

_s is static value of intrinsic permeability, e is the width of the plurality of gaps, and p is the pitch.

5. A magnetic circuit comprising:

a magnetic layer having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic layer being composed of a series of portions, two successive portions being separated from each other by a wall of insulating material disposed at a position perpendicular to the median line of the magnetic layer and generating a demagnetizing field in the magnetic layer at the position of said wall,

wherein said magnetic layer is formed by a stack of alternatively magnetic and insulating layers.

6. A magnetic circuit comprising:

a magnetic layer having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic layer being composed of a series of portions, two successive portions being separated from each other by a gap disposed at a position perpendicular to the median line of the magnetic layer and generating a demagnetizing field in the magnetic layer at the position of said gap,

wherein said magnetic layer is formed by a stack of alternatively magnetic and insulating layers.

7. A magnetic circuit comprising:

a magnetic layer having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic layer being composed of a series of portions, two successive portions being separated from each other by a wall of insulating material disposed at a position perpendicular to the median line of the magnetic layer and generating a demagnetizing field in the magnetic layer at the position of said wall,

wherein each wall of insulating material has a width and is spaced at a pitch to extend a frequency of operation of the magnetic circuit up to a resonant frequency, and

wherein said magnetic layer is formed by a stack of alternating magnetic and insulating layers.

8. A magnetic circuit comprising:

a magnetic layer having a median line and disposed with respect to an induced magnetic field so as to canalize, in the direction of the median line, said magnetic field,

the magnetic layer being composed of a series of portions, two successive portions being separated from each other by a gap disposed at a position perpendicular to the median line of the magnetic layer and generating a demagnetizing field in the magnetic layer at the position of said gap,

wherein each said gap has a width and is spaced at a pitch to extend a frequency of operation of the magnetic circuit up to a resonant frequency, and

wherein said magnetic layer is formed by a stack of alternating magnetic and insulating layers.