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MAGNETS; INDUCTANCES; TRANSFORMERS; SELECTION OF MATERIALS FOR THEIR MAGNETIC PROPERTIES ( ceramics based on ferrites C04B 35/26 ; alloys C22C; {construction of loading coils H01B} ; thermomagnetic devices H01L 37/00 ; loudspeakers, microphones, gramophone pick-ups or like acoustic electromechanical transducers H04R)
Definition statement
This subclass/group covers:

Magnets or magnetic bodies characterised by the magnetic materials therefor. Selection of materials for their magnetic properties (H01F 1/00).

Thin magnetic films (H01F 10/00).

Permanent magnets (H01F 7/00).

Electromagnets (H01F 7/00) including, for example, superconductive magnets (H01F 6/00); details thereof such as coils (H01F 5/00), cores, yokes, and armatures (H01F 3/00).

Fixed and variable transformers including, for example, superconductive or cryogenic transformers; adaptations thereof for specific applications or functions; details thereof (H01F 19/00, H01F 21/00, H01F 27/00, H01F 29/00, H01F 30/00, H01F 36/00, H01F 38/00).

Fixed and variable inductances; adaptations thereof for specific applications or functions; details thereof (H01F 17/00, H01F 21/00, H01F 27/00, H01F 29/00, H01F 37/00, H01F 38/00).

Apparatus or processes for magnetizing or demagnetizing (H01F 13/00).

Apparatus or processes specially adapted for manufacturing or assembling devices covered by this subclass (H01F 41/00).

Further information:

Groups H01F 17/00-H01F 38/00 (with the exception of groups H01F 27/42 and H01F 38/32) cover only structural or constructional aspects of transformers, inductive reactors, chokes or the like.These groups do not cover circuit arrangement of such devices, which are covered by the appropriate functional places.

References relevant to classification in this group
This subclass/group does not cover:
Magnets used to separate solid materials from other solid materials or fluids
Magnetic work holders
Apparatus or processes for degaussing ships
Lifting magnets
Magnets or electromagnets in electric meters
Devices for demagnetizing parts of clocks and watches
Magnetic record carriers
Apparatus or processes specially adapted for manufacturing magnetic record carriers
Thin-film magnetic stores
Apparatus or processes for threading magnetic cores in digital storage elements
Magnets or electromagnets in relays
Magnets or electromagnets in dynamo-electric machines
Methods or apparatus specially adapted for manufacturing, assembling, maintaining or repairing dynamo-electric machines, e.g. forming windings prior to mounting into the machine
Arrangements for controlling transformers, reactors or choke coils for the purpose of obtaining a desired output
Magnetic amplifiers
Impedance networks
Demagnetizing arrangements for color television
Acoustic electromechanical transducers having coils or permanent magnets
Informative references
Attention is drawn to the following places, which may be of interest for search:
Powder metallurgy
Iron oxides (not sintered)
Ferrite based ceramics
Ferrous alloys
Coating by evaporation or sputtering
Refrigeration machines using magnetic effects
Magneto-optical devices
Sensing record carriers using inductive or magnetic sensors
Semiconductor devices with potential-jump barrier or surface barrier controllable by variation of the magnetic field applied to the devices
Thermomagnetic devices
Magnetostrictive devices
Devices using galvano-magnetic or similar magnetic effects
Screening of electric apparatus against magnetic fields
Special rules of classification within this subclass
  • Documents are classified with a CPC symbol according to the invention information mainly found in the claims with due regard given to the description and the figures. Additional information found in the claims and in the description and figures, which might be relevant for future searches is given an Indexing Code symbol.
  • Main groups H01F 1/00, H01F 10/00 and subgroups H01F 41/14-H01F 41/34:

Classification proceeds by assigning the most restricted possible CPC symbol to the document, followed by additional knowledge tagging using Indexing Code symbols. This implies that CPC head subgroups (corresponding to IPC subgroups) should only be used if no other possibility could be found for classifying the document in a more restricted subgroup.

If the set of claims comprises product or article and method claims an CPC symbol should be assigned to each of these categories. However if the most suitable subgroup for a claim of a given category, e.g. product, does not exist in the main group of the same category, e.g. product group, and can only be found in groups of another corresponding category, e.g. a group for a method to manufacture the product, this latter subgroup should be assigned to the claim e.g. method subgroup assigned to a product claim. For example a document with no method claims dealing with a magnetic tunnel junction in which the spacer has been processed in such a way that its material structure becomes inventive, would still be given the method CPC symbol H01F 41/307 as product CPC symbol H01F 10/3254 is silent over any material inventive features.

Another use of Indexing Codes can be made for particular cases where the invention is a specific property of a given type of material or article and this property is classified only in subgroups of another specific material type. In this case the corresponding CPC symbol cannot be given. Consequently the Indexing Code should be given together with an CPC symbol corresponding to the material described in the document. For example: a sintered nanocomposite exchange spring magnet of SmCo/Fe cannot be given H01F 1/0579 as CPC symbol since the latter symbol belongs to NdFeB magnets classification subtree. Therefore the combination H01F 1/0557 and H01F 1/0579 should be used.

  • Remaining main groups of H01F:

Multi-aspect classification is used. This means that several subgroups are assigned to a document if several relevant features are present. It is, for example, not mandatory to use the next general subgroup H01F 27/28 for transformer windings if printed winding (H01F 27/2804) and wire winding (H01F 27/2823) are combined in one transformer. Instead, subgroups H01F 27/2804 and H01F 27/2823 are both assigned to the respective document.

Glossary of terms
In this subclass/group, the following terms (or expressions) are used with the meaning indicated:
Compound
homogenous substance comprising at least two elements, having a non-metallic character and a specific (fixed) composition ratio, including also intermetallic compounds.
Magnets or magnetic bodies characterised by the magnetic materials therefor; Selection of materials for their magnetic properties
Definition statement
This subclass/group covers:

Bulk magnetic materials: antiferromagnetic, diamagnetic, paramagnetic, hard and soft ferromagnetic materials.

0D, 1D and 2D magnetic (nano)structures.

Materials cover metallic materials, compounds (i.e. mainly non-metallic materials) or organic materials. Selected types of magnetic materials are highlighted within specific subgroups.

H01F 1/00 is mainly concerned with bulk materials except for some specific subgroups.

H01F 1/0009 covers antiferromagnetic bulk material.

H01F 1/0018 covers diamagnetic or paramagnetic bulk material.

H01F 1/0027 covers thick magnetic films formed with methods classified under H01F 41/16.

References relevant to classification in this subclass
This subclass/group does not cover:
Methods to manufacture magnetic hard or soft articles out of said materials
Informative references
Attention is drawn to the following places, which may be of interest for search:
Working metallic powder; manufacturing powder (related to H01F 1/0045; H01F 1/06; H01F 1/20- H01F 1/28)
Iron oxides carriers (related to H01F 1/342, H01F 1/36)
Making alloys by powder metallurgy (related to H01F 1/0045; H01F 1/06; H01F 1/20- H01F 1/28; H01F 1/14766; H01F 1/14708)
Non-ferrous alloys containing 5-50% by weight of oxides, carbides, borides, nitrides, silicides etc. (related to H01F 1/09, H01F 1/33, H01F 1/14708, H01F 1/14766)
Making ferrous alloys (related to H01F 1/14708, H01F 1/14766)
Ferrous alloys (related to H01F 1/14708, H01F 1/14766)
Amorphous alloys and related processes (related to H01F 1/153)
Cast iron alloys (related to H01F 1/14708, H01F 1/14766)
Electromagnetic interference suppressing, shielding (related to H01F 1/26, H01F 1/28)
Single crystal growth, unidirectional solidification (related to H01F 1/0072)
Special rules of classification within this subclass

Treatment of the materials, e.g. compacting, sintering, bonding are also classified into this group.

{showing low dimensional magnetism, i.e. spin rearrangements due to a restriction of dimensions, e.g. showing giant magnetoresistivity, (H01F 1/153 , H01F 1/42 and H01F 10/00 take precedence; magnetoresistive sensors G01D 5/16 , G01R 33/06 ; magnetoresistive recording G11B 5/39 ; magnetic-field-controlled resistors H01L 43/08) }
Definition statement
This subclass/group covers:

These subgroups cover:

0D, 1D and 2D magnetic (nano)structures wherein the size and carriers confinement alters the magnetic properties. Embedded magnetic nanostructures.

References relevant to classification in this group
This subclass/group does not cover:
Nanosized particles used in magnetic cores, electromagnetic noise suppressing sheets
Hard magnetic particles
Magnetorheological fluids

Examples of places where the subject matter of these subgroups is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Nuclear magnetic resonance imaging: preparations for testing in vivo including magnetic particles
Magnetic separation process including magnetic particles
Special rules of classification within this group

1. Nanoparticles used in bioscreening (diagnostic, separation) are classified in these subgroups irrelevant of their composition and size effect.

2. If a strong effect of the size of the nanoparticles belonging to the groups cited in the above table is shown on the magnetic properties, then it is also classified in H01F 1/0036-H01F 1/0063

of inorganic materials (H01F 1/44 takes precedence )
Definition statement
This subclass/group covers:

Magnetocaloric materials. Subdivided in metallic or compounds materials.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Cryogenic machines using magnetic effects based on a magnetocaloric material
characterised by their coercivity { (H01F 1/40 takes precedence ) }
Definition statement
This subclass/group covers:

Materials with specific coercivity; Laves phases or magnetic shape memory materials. Mainly those latter examples are classified in these subgroups.

of hard-magnetic materials
Definition statement
This subclass/group covers:

Hard magnetic metals or alloys characterised by composition, by shape and by the process or treatments to obtain articles including these materials.

Subgroup H01F 1/0579 is concerned with nanocomposite exchange spring magnets.

H01F 1/057 covers so-called R-T-B magnets (Nd2Fe14B phase).

H01F 1/059 covers magnets with a Sm2Fe17N2 phase.

References relevant to classification in this subclass
This subclass/group does not cover:
Method claims directed at manufacturing or treating magnets
Permanent magnets with emphasis on the structure or use rather than the material
Actuators, dynamo-electric rotating machines, motors (related to H01F 1/053- H01F 1/059)
Special rules of classification within this group

Magnets obtained from the corresponding materials are classified in the same subgroups according to method criteria (process or treatments undergone by the material forming the magnet) on which part of the classification refinement is based.

in the form of particles, e.g. powder (H01F 1/047 takes precedence; { record carriers G11B 5/70605} )
Definition statement
This subclass/group covers:

Hard magnetic metallic particles characterised by shape and by treatments to obtain articles including these materials.

The subgroups are generally concerned with particles used in magnetic recording or under subgroup H01F 1/08 metallic particles for permanent magnets when composition is not specifically mentioned in the claims.

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of these subgroups is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Magnetic record carriers
Apparatus or processes specially adapted for manufacturing magnetic record carriers
Magnetic record carriers (metal or alloy material, related to H01F 1/06+)
Magnetic record carriers (non-metallic material, related to H01F 1/11)
Mixtures of metallic and non-metallic particles; Metallic particles having oxide skin
Definition statement
This subclass/group covers:

Hard magnetic non-metallic particles characterised by shape and by treatments to obtain articles including these materials.

H01F 1/09 can cover hard metallic particles covered with an oxide layer

Special rules of classification within this group

For rare earth containing particles covered with an oxide layer, subgroups H01F 1/0552 and H01F 1/0572 would take precedence except if the oxide layer is the core of the invention.

Non-metallic substances, e.g. ferrites {e.g. [(Ba,Sr)O(Fe2O3)6} ferrites with hexagonal structure]
Definition statement
This subclass/group covers:

Hard non-metallic magnets such as Ba-ferrite type of magnets

of soft-magnetic materials
Definition statement
This subclass/group covers:

Soft magnetic metals or alloys characterised by composition, by shape and treatments to obtain articles including these materials.

Special rules of classification within this group

Fe-Ni and Fe-Si alloys and their shape are classified in the subgroups H01F 1/14708-H01F 1/14791.

Other compositions than Fe-Ni, Fe-Si must be classified according to a shape criterion: subgroups H01F 1/16 and onwards for sheets, H01F 1/20 and onwards for particles and H01F 1/143 for wires or for no specific shape given: subgroup H01F 1/147. If no specific shape or composition criterion is given, the H01F 1/14 symbol should be given.

Amorphous metallic alloys, e.g. glassy metals { ( making ferrous amorphous alloys C22C 33/003) }
Definition statement
This subclass/group covers:

Soft magnetic amorphous metals, also including nanocrystallites, characterised by composition and by methods to obtain articles including these materials.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Alarms using amorphous ferromagnetic tags
G08B13/24B2
Security coding
Special rules of classification within this group

The method section of these subgroups has to be used in combination with the method subgroups H01F 41/0206-H01F 41/0246.

in the form of sheets (H01F 1/147 takes precedence )
Definition statement
This subclass/group covers:

Soft magnetic sheet of metals or alloys.

H01F 1/18 covers insulated sheets

in the form of particles, e.g. powder (H01F 1/147 takes precedence )
Definition statement
This subclass/group covers:

Soft magnetic particles of metals or alloys characterised by shape and by treatments or methods to obtain articles including these materials.

H01F 1/20 covers particles

H01F 1/22 covers compacted particles.

H01F 1/24 covers insulated compacted particles.

H01F 1/26 covers compacted particles wherein insulator are organic macromolecules.

Subgroup H01F 1/28 concerns non compacted bodies.

Special rules of classification within this group

Soft magnetic particles compacted in a bonded body (magnetic core or noise suppressing sheet) are classified in H01F 1/26 in combination with H01F 41/0246 for magnetic cores only.

Mixtures of metallic and non-metallic particles; Metallic particles having oxide skin
Definition statement
This subclass/group covers:

Soft metallic particles covered with an oxide layer.

Non-metallic substances, e.g. ferrites
Definition statement
This subclass/group covers:

Soft non-metallic materials characterised by composition, by shape and treatments to obtain articles including these materials.

H01F 1/34 covers bulk non metallic material such as ferrite.

H01F 1/36 covers non-metallic particles.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Ferrite based ceramics described only by chemical composition
Special rules of classification within this group

Subgroup H01F 1/24 would take precedence in the case of oxide insulated particles being part of a compacted body.

of magnetic semiconductor materials, e.g. CdCr2S4 ( devices using galvano-magnetic or similar effects H01L 43/00)
Definition statement
This subclass/group covers:

Magnetic semiconductors and half-metals (Heusler).

Special rules of classification within this group

Perovskites (H01F 1/407) and half-metals (H01F 1/408) are classified under the arborescence of magnetic semiconductors even if they might not be necessarily a semiconducting material.

of organic or organo-metallic materials, {e.g. graphene} (H01F 1/44 akes precedence )
Definition statement
This subclass/group covers:

Organic or organo-metallic materials.

of magnetic liquids, e.g. ferrofluids ( particles in a bonding agent H01F 1/28 , H01F 1/36 , {H01F 1/37} )
Definition statement
This subclass/group covers:

Magnetic and magnetorheologic fluids.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Nuclear magnetic resonance imaging: preparations for testing in vivo including magnetic particles
Magnetorheological fluid dampers including a ferrofluid
Cores, Yokes, or armatures ( magnetic materials H01F 1/00 ; permanent magnets H01F 7/02)
Definition statement
This subclass/group covers:

Cores, yokes and armatures which are single parts or arrangements of several parts of ferromagnetic material used to guide magnetic flux.

Further information:

  • Cores, yokes and armatures are covered by H01F 3/00 if:- no specific application is mentioned,- a special application is mentioned for which no specific subgroup exists elsewhere,- they comprise specific features for which no subgroups exist in the specific subgroup for the application (e.g. transformer cores which are normally classified in H01F 27/24 have to be classified in H01F 3/10 if they are made from a combination of materials and in H01F 3/14 if they comprise air gaps).
  • H01F 3/02 and H01F 3/04:A core made from a stack of strips is covered by H01F 3/02 although this subgroup refers to sheets.The subgroup H01F 3/04 for strips and ribbons predominantly covers cores which are fabricated by winding the strips on a mandrel.
References relevant to classification in this group
This subclass/group does not cover:
Magnetic materials per se
Permanent magnets

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Magnet cores of signal inductances
Details of magnet cores of transformers or inductances in general
Magnetic shunt path in the case of transformers/inductances ( related to H01F 3/12)
Apparatus or processes for manufacturing magnet cores
Magnetic cores for electric motors/generators
Coils ( superconducting coils H01F 6/06 ; fixed inductances of the signal type H01F 17/00)
Definition statement
This subclass/group covers:

Printed coils.

Wound electric conductors.

Further information:

  • Coils are covered by H01F 5/00, if:- no specific application is mentioned,- a special application is mentioned for which no specific subgroups exist elsewhere,- they comprise specific features for which no subgroups exist in the specific subgroup for the application (e.g. a bobbin for an electromagnet is classified in H01F 5/02 although electromagnets are normally classified in H01F 7/06).
  • H01F 5/04:This subgroup predominantly refers to terminals attached to bobbins.Bobbins characterised by details for attaching terminals are classified here and not in the subgroup H01F 5/02 for bobbins.
References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Superconducting coils
Printed coils for signal inductances
Coils for transformers/inductances
Printed coils for transformers/inductances
Bobbins for transformers/inductances (related to H01F 5/02)
Bobbins in relation with apparatus or processes for manufacturing coils (related to H01F 5/02)
Coil arrangements for induction heating
Loop aerials (antennae)
Coils for electric motors/generators
Informative references
Attention is drawn to the following places, which may be of interest for search:
Apparatus or processes for manufacturing coils
Synonyms and Keywords

In patent documents the following expressions/words "former" and "bobbin, spool, (coil/winding) support, (coil/winding) body, tube, sleeve" are often used as synonyms:

In patent documents the following expressions/words "coil" and "winding, solenoid" are often used as synonyms.

Superconducting magnets; Superconducting coils { ( magnetic resonance assemblies using superconducting coil systems G01R 33/3815) }
Definition statement
This subclass/group covers:

Superconducting magnets and coils and accessories necessary to operate them.

Further information:

  • Superconducting magnets can be superconducting bulk pieces cooled below the critical temperature in a magnetic field or superconducting coils. For use as magnets, the coils are often shorted ("persistent mode" or "persistent current mode").
  • Constructive details of inductive superconducting current limiters are covered by H01F 6/00.
References relevant to classification in this group
This subclass/group does not cover:
Superconductive cables
Devices using superconductivity in general
Resistive superconducting current limiters (related to H01F 6/00)

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Superconducting coils used in magnetic separation of materials (related to H01F 6/06)
Magnet systems for NMR using superconducting coils (related to H01F 6/06)
Superconducting transformers
Informative references
Attention is drawn to the following places, which may be of interest for search:
Apparatus or processes for manufacturing superconductive coils
Emergency protective circuits for limiting excessive current using superconducting elements (related to H01F 6/00)
Magnets ( superconducting magnets H01F 6/00 ; for separation of solid materials or fluids B03C 1/00 ; for bench or like work-holders B23B 31/28 , B23Q 3/00 ; work-holding devices B25B 11/00 ; lifting magnets B66C 1/00 ; { operating or controlling locks using permanent magnets E05B 47/0038 ; devices for holding a wing, e.g. door or window, by magnetic or electromagnetic attraction E05C 19/16 ; relieving load or bearings using magnetic means F16C 39/06} ; for electric meters G01R ; for relays H01H ; { for electric discharge tubes H01J , e.g. H01J 3/24 , H01J 23/10 , H01J 29/68} ; for dynamo-electric machines H02K)
Definition statement
This subclass/group covers:

Magnets in general.

Further information:

  • The two principal subgroups are H01F 7/02 for permanent magnets and H01F 7/06 for electromagnets.
  • Electromagnets comprising permanent magnets in any part of the magnetic circuit are covered as follows:- by H01F 7/1615 or H01F 7/1646 if they comprise a rectilinearly movable armature,- by H01F 7/122 if the armature is not or not only rectilinearly movable,- by H01F 7/20 if they do not comprise a movable armature.
References relevant to classification in this group
This subclass/group does not cover:
Superconducting magnets

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

H01F 7/00 in general:

Magnets or electromagnets for electric meters
Magnets or electromagnets for relays
Magnets or electromagnets for dynamo-electric machines

Permanent magnets (H01F 7/02):

Magnets for fastening garments
Magnetic fasteners for bags
Magnets used to separate solid materials from other solid materials or fluids
Chucks using magnetic means
Devices for holding work using magnetic or electric force acting directly on the work
Magnetic work holders
Screwdrivers using magnetic means
Griping heads with magnetic holding means
Load-engaging elements for cranes attached by magnetic means
Treatment of water by magnetic fields using permanent magnets

Electromagnets (H01F 7/06):

Load engaging elements: electromagnetic means (related to H01F 7/20)
Magnet systems for NMR using electromagnets (related to H01F 7/20)
Informative references
Attention is drawn to the following places, which may be of interest for search:

Permanent magnets (H01F 7/02):

Devices for hanging or supporting pictures, mirrors, or the like using magnetism
Magnetic cleaning implements
Magnetic fastening of teeth prostheses in mouth
Magnetic dental implant retention systems
Toys: building blocks comprising magnetic interaction means
Magnetic mixers/stirrers
Securing wings by magnetic or electromagnetic attraction
Electromagnetic valve actuated using a permanent magnet
Supporting, suspending, or attaching arrangements for lighting: magnetic devices
Fastening of component parts of lighting devices using magnets
Educational appliances having elements to be mounted on a support by means of magnets
Educational appliances comprising elements to be used without a special support, the elements being connectible magnetically
Planning boards using magnetic elements
Faraday rotators (magnetic field generation)
Demagnetization of permanent magnets by coils
Fastening by use of magnets (jewellery, haberdashery)
Devices for securing together, or preventing relative movement between, constructional elements or machine parts by the use of a magnetic material

Electromagnets (H01F 7/06):

MEMS with flexible or deformable elements (related to H01F 7/08)
Valve-gear or valve arrangements actuated by electric means
Electrical control of supply of combustible mixture or its constituents: output circuits, e.g. for controlling currents in command coils (related to H01F 7/18)
Fuel injectors using electromagnetic operating means
Fuel injectors with movable windings (related to H01F 7/066)
Control or regulating systems: automatic controllers (related to H01F 7/18)
Magnetic circuit arrangements for electromagnetic relays (related to H01F 7/081)
Electromagnetic relays in general
Actuators based on magnetostriction
Motors with reciprocating/oscillating/vibrating magnet/armature/coil
Propulsion systems (e.g. linear motors)
Acoustic electromechanical transducers having coils or permanent magnets
Special rules of classification within this group

Although magnets are normally classified in the respective subgroups of an application when provided for, the presence of features for which an appropriate subgroup does not exist in the application main group but in H01F 7/00, requires the respective subgroup in H01F 7/00 to be allocated.

For example, an electromagnetically actuated valve which is normally classified in F16K 31/06, should also be classified in H01F 7/10 for details concerning the use of alternating current for powering the actuator.

Thin magnetic films, e.g. of one-domain structure ( magnetic record carriers G11B 5/00 ; thin-film magnetic stores G11C)
Definition statement
This subclass/group covers:

Hard and soft ferromagnetic thin films. Antiferromagnetic thin films. Single layers and (spin-exchanged coupled) multilayers are both considered as thin films.

Thin film materials cover metallic materials, compounds or organic materials.

H01F 10/00 is concerned with ferromagnetic or antiferromagnetic materials in the form of thin films.

A thin film is generally less than a couple of microns thick and can be defined as being manufactured by the methods classified in subgroups H01F 41/18-H01F 41/34.

H01F 10/002 covers antiferromagnetic, single layer, thin films.

H01F 10/005 covers organic or organo-metallic thin films. Graphene thin films are also given this symbol in case magnetic properties are claimed.

H01F 10/007 covers granular thin films.

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of these subgroups is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Measuring magnetic variables: magnetoresistive sensors (related to H01F 10/324)
Magnetic recording heads (related to H01F 10/324)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Ferrous alloys (related to H01F 10/14)
Amorphous alloys and related processes (related to H01F 10/13)
Alloys based on Ni; alloys based on Co (related to H01F 10/14; H01F 10/16)
Semiconductor devices with potential-jump barrier or surface barrier controllable by variation of the magnetic field applied to the devices, e.g. spin (valve) transistor, spin injection device (related to H01F 10/324, H01F 10/1936)
Devices using magnetic effects; Selection of materials for(related to H01F 10/324 )
Magneto-optic materials (related to H01F 10/24)
Single crystal growth of garnets (related to H01F 10/24)
characterised by the coupling or physical contact with connecting or interacting conductors
Definition statement
This subclass/group covers:

Thin films characterised by contact with conductors.

characterised by magnetic layers ( {H01F 10/32 takes precedence } ; applying thin magnetic films to substrates H01F 41/14)
Definition statement
This subclass/group covers:

Single layer thin films characterised by properties or composition.

characterised by the composition
Definition statement
This subclass/group covers:

Metallic single layer thin films characterised by their composition, e.g. amorphous, crystalline.

being compounds
Definition statement
This subclass/group covers:

Compounds single layer thin films characterised by their composition. Further divided in amorphous, magnetic semiconductors, half-metals (Heusler), perovskites and ferrites.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Magneto-optic devices (Faraday-rotator)
Photonic crystals
characterised by the substrate or intermediate layers { (H01F 10/06 and H01F 10/32 take precedence ) }
Definition statement
This subclass/group covers:

Multilayers characterised by intermediate layers.

H01F 10/30 covers specific seed, template and cap layers.

Spin-exchange-coupled multilayers, e.g. nanostructured superlattices { ( applying spin-exchange-coupled multilayers to substrates H01F 41/302) }
Definition statement
This subclass/group covers:

Spin-exchanged-coupled multilayers characterised by the interaction between the different layers and refined by composition of the single interacting layers.

Special rules of classification within this group

Multilayers with perpendicular magnetic anisotropy of the type of (Co/Pt)n are also classified in H01F 10/3236 but H01F 10/3286 takes precedence.

{Exchange coupling of magnetic film pairs via a very thin non-magnetic spacer, e.g. by exchange with conduction electrons of the spacer}
Definition statement
This subclass/group covers:

Spin-exchanged-coupled multilayers characterised by having a thin non-magnetic spacer between magnetic layers.

Typical TMR and GMR structures.

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of these subgroups is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Magnetic record carriers
Magnetic storage elements, non volatile memories, MRAM
Informative references
Attention is drawn to the following places, which may be of interest for search:
Magnetostrictive devices;
Selection of materials therefor
Special rules of classification within this group

Tunnel magnetic junctions (a tunnel barrier sandwiched between two magnetic layers) are classified in H01F 10/3254.

However TMR junctions with additional pinning of one of the magnetic layers (by an AF layer or a SAF/AAF multilayer) do not have a subgroup of H01F 10/3254 where they can be classified. Therefore an Indexing Code of H01F 10/3268-H01F 10/3281 is generally additionally given.

Spin valves (GMR structures) with no specificity of the magnetic layers are generally classified under H01F 10/325.

If no subgroup in H01F 10/00 can reflect the invention of a product claim for a spin-exchanged-coupled multilayer, subgroup from the corresponding method subgroups H01F 41/302-H01F 41/309 is assigned when appropriate.

Apparatus or processes for magnetising or demagnetising ( { devices for holding workpieces using magnetic or electric force acting directly on the workpieces B23Q 3/15} ; for degaussing ships B63G 9/06 ; for clocks or watches G04D 9/00 ; { recording or erasing of information on magnetic record carriers G11B 5/00} ; demagnetising arrangements for colour television H04N 9/29)
Definition statement
This subclass/group covers:

Apparatus or processes for magnetising permanent magnets or for demagnetising magnetic bodies.

References relevant to classification in this group
This subclass/group does not cover:
Apparatus or processes for degaussing ships
Demagnetising devices for clocks or watches
Recording or erasing of information on magnetic record carriers
Demagnetizing arrangements for colour televisions

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Imparting anisotropy to permanent magnet material (e.g. aligning magnetic grains in a magnetic field)
Fixed inductances of the signal type ( coils in general H01F 5/00 { inductors without a potential-jump or surface barrier specially adapted for integrated circuits, details thereof and multistep manufacturing processes therefor H01L 28/10} )
Definition statement
This subclass/group covers:

Inductances of fixed value not used /useable for high power.

Further information:

"Signal type" means that these inductances are not used/useable for high power.

References relevant to classification in this group
This subclass/group does not cover:
Coils in general
Fixed inductances used/usable for high power

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Adaptations of transformers for special applications or functions
Inductors for integrated circuits and corresponding multistep methods of manufacture (related to H01F 17/0006)
Inductive arrangements for semiconductor devices not otherwise provided for (related to H01F 17/0006)
Loop aerials with ferromagnetic core (related to H01F 17/04)
Impedance networks
Printed circuits incorporating printed inductors (related to H01F 17/0006)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Inductive arrangements or effects between of or between wiring layers of semiconductor devices (related to H01F 17/0006)
Thin- or thick-film solid state devices (related to H01F 17/0006)
Integrated circuits comprising only passive thin-film elements (related to H01F 17/0006)
Synonyms and Keywords

In patent documents the following expressions/words "inductance" and "inductor, choke, reactor, reactance" are often used as synonyms.

Fixed transformers or mutual inductances of the signal type (H01F 36/00 takes precedence )
Definition statement
This subclass/group covers:

Transformers or coupled inductances.

Further information:

"Signal type" means that these transformers or inductances are not used/useable for high power.

The subgroups basically define different frequency ranges.

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Transformers with superconductive windings
Adaptations of transformers or inductances for special applications or functions
Variable inductances or transformers of the signal type (H01F 36/00 takes precedence )
Definition statement
This subclass/group covers:

Transformers or inductances which are variable and not used/useable for high power.

Further information:

  • "Signal type" means that these transformers or inductances are not used/useable for high power.
References relevant to classification in this group
This subclass/group does not cover:
Variable inductances/transformers not being of the signal type (i.e. variable inductances/transformers used/usable for high power)
Transformers with superconductive windings
Magnetic amplifiers

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Means for converting output of a sensing member to another variable: varying inductance
Adaptations of transformers or inductances for special applications or functions
Informative references
Attention is drawn to the following places, which may be of interest for search:
Variable inductances including MEMS (related to H01F 21/04 or H01F 21/06)
Details of transformers or inductances, in general
Definition statement
This subclass/group covers:

Constructional features of transformers or inductances in general.

Further information:

In this group no distinction is made between "signal type" and " power type" applications except for the cases mentioned below. "Power type" means that these transformers or inductances are used/useable for high power.

H01F 27/00 covers constructional features of transformers and inductances falling under the titles of H01F 17/00 to H01F 21/00 and H01F 29/00 to H01F 38/00.

H01F 27/00 also covers details of cores, coils and magnetising arrangements in H01F 3/00 to H01F 7/00 and H01F 13/00 if there is no appropriate subgroup for the respective constructional features in the H01F 3/00 to H01F 7/00 and H01F 13/00.

  • Example: cooling of coils:- For superconducting coils (H01F 6/00), there is an own subgroup for cooling: H01F 6/04.- For normal-conducting coils, however, which are classified generally in H01F 5/00 and in H01F 7/20 when used as electromagnet, no subgroups for cooling exist. Therefore, applications related to the cooling of normal-conducting coils or electromagnets, in addition to H01F 5/00 or H01F 7/20, have to be classified in an appropriate subgroup of H01F 27/08.
  • Although in general, no difference is made between "signal type" and " power type" applications in H01F 27/00, this is not true for the mounting of transformers/inductances:- H01F 27/027 covers the mounting of "signal type" applications,- H01F 27/06 covers the mounting of "power type" applications.
  • Details related to cooling- Cooling arrangements only for coils are covered by H01F 27/2876.- Cooling channels in the insulation of coils are covered by H01F 27/322.- Cooling of transformers/inductances in general is covered by H01F 27/08 and subgroups.- H01F 27/14 covers a wide variety of accessories used for oil-cooled transformers/inductances like oil expansion chambers, gas cushions, oil filters.
  • Details related to encapsulation- Devices encapsulated as a whole are covered by H01F 27/022.- Encapsulation only of a winding is covered by H01F 27/327.
  • Details related to electric/magnetic shields- Shields in general are covered by H01F 27/36.- Shields of the winding arrangement are covered by H01F 27/288.- Shields of pancake coils are covered by H01F 27/2871.
References relevant to classification in this group
This subclass/group does not cover:
Cooling of superconducting coils (related to H01F 27/08)
Informative references
Attention is drawn to the following places, which may be of interest for search:
Buchholz relays (for protecting oil-cooled transformers, related to H01F 27/14 and H01F 27/402)
H01H33/55B8
Buchholz relays (for protecting oil-cooled transformers, related to H01F 27/14 and H01F 27/402)
Emergency protective circuits for transformers (related to H01F 27/402)
Cooling of electrical devices in general (related to H01F 27/08)
Arrangements for controlling transformers, reactors or choke coils for the purpose of obtaining a desired output (field not active anymore)
Variable transformers or inductances not covered by group H01F 21/00 { ( tap change devices H01H 9/0005) }
Definition statement
This subclass/group covers:

Variable transformers or inductances of the "power type", i.e. used/useable for high power.

References relevant to classification in this group
This subclass/group does not cover:
Variable transformers or inductances of the signal type
Details of tap change devices regarding the construction, opening mechanism and contact arrangement of the selector switches (related to H01F 29/02)

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Use of variable transformers or inductances in automatic systems for regulating voltage or current
Adaptations of transformers or inductances for special applications or functions
Amplitude modulation by means of variable impedance element (related to H01F 29/14)
Magnetic amplifiers (related to H01F 29/14)
Fixed transformers not covered by group H01F 19/00
Definition statement
This subclass/group covers:

Fixed transformers of the "power type", i.e. used/useable for high power.

Further information:

  • The subgroups define different general transformer structures.
References relevant to classification in this group
This subclass/group does not cover:
Fixed transformers of signal type
Transformers with superconductive windings

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Adaptations of transformers for special applications or functions
Transformers with superconductive windings or with windings operating at cryogenic temperature ( superconducting magnets or superconducting coils H01F 6/00)
Definition statement
This subclass/group covers:

Transformers with superconducting windings.

Transformers with windings operating at cryogenic temperature.

References relevant to classification in this group
This subclass/group does not cover:
Superconducting magnets or coils
Informative references
Attention is drawn to the following places, which may be of interest for search:
Cooling of transformers in general
Fixed inductances not covered by group H01F 17/00
Definition statement
This subclass/group covers:

Fixed inductances of "power type", i.e. used/useable for high power.

References relevant to classification in this group
This subclass/group does not cover:
Fixed inductances of signal type

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Adaptations of inductances for special applications or functions
Impedance networks
Synonyms and Keywords

In patent documents the following expressions/words "inductance" and "inductor, choke, reactor, reactance" are often used as synonyms.

Adaptations of transformers or inductances for specific applications or functions
Definition statement
This subclass/group covers:

Transformers or inductances for specific applications or functions.

Welding transformers and discharge lamp ballasts are covered by H01F 38/08

even if they do not explicitly have a high leakage (i.e. gap in magnetic flux path).

Informative references
Attention is drawn to the following places, which may be of interest for search:
Rotary transformer for transmission of signals and/or power between stationary and moving part of an X-ray computed tomography (CT) apparatus (related to H01F 38/18)
Current collectors for power supply lines of electronically propelled vehicles without mechanical contact between collector and power supply line (related to H01F 38/14)
Charging electric vehicles by inductive power transfer (related to H01F 38/14)
Circuit arrangements for transfer of electric power between AC networks and DC networks with inductive power transfer (related to H01F 38/14)
Non-contact couplings for charging batteries from AC mains by converters (related to H01F 38/14)
Near field transmission systems using inductive coupling (related to H01F 38/14)
Ignition circuits for discharge lamps (related to H01F 38/10 and H01F 38/12)
Apparatus or processes specially adapted for manufacturing or assembling the devices covered by this subclass
Definition statement
This subclass/group covers:

Apparatus or processes for manufacturing or assembling transformers, inductances, reactors or choke coils.

Apparatus or processes for manufacturing or assembling magnetic circuits, permanent magnets or coils.

Apparatus or processes for applying magnetic films to substrates and forming magnetic nanostructures.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Manufacturing articles from powder; (related to H01F 41/0246)
{Impregnating or encapsulating ( insulating of windings H01F 41/12) }
Definition statement
This subclass/group covers:

Methods for encapsulating/impregnating. Refers to cases where a whole device (e.g. coil and core of a transformer or a choke) is encapsulated.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Injection moulding incorporating preformed parts
Special rules of classification within this subgroup

Encapsulation only of a winding is to be classified in H01F 41/127.

for manufacturing cores, coils, or magnets (H01F 41/14 takes precedence; for dynamo-electric machines H02K 15/00)
Definition statement
This subclass/group covers:

Manufacturing of hard or soft magnetic articles. Manufacturing of coils.

{Manufacturing of magnetic cores by mechanical means ( magnetic cores per se H01F 27/24) }
Definition statement
This subclass/group covers:

Methods and apparatus for manufacturing soft magnetic articles characterised by the shape of the magnetic material composing those articles. H01F 41/14 takes precedence.

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of these subgroups is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Manufacturing of coils, cores or magnets for dynamo-electric machines
{for manufacturing permanent magnets}
Definition statement
This subclass/group covers:

Methods and apparatus for manufacturing permanent magnets characterised by process steps performed on the magnetic material or on the magnets.

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of these subgroups is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Manufacturing of coils, cores or magnets for dynamo-electric machines
for manufacturing coils { ( coils for transformer or inductances H01F 27/28) }
Definition statement
This subclass/group covers:

Methods and apparatus for manufacturing coils.

Further information:

The most important subgroups are related to:

References relevant to classification in this group
This subclass/group does not cover:

Examples of places where the subject matter of this group is covered when specially adapted, used for a particular purpose, or incorporated in a larger system:

Manufacturing of coils cores or magnets for dynamo-electric machines
for applying magnetic films to substrates ( covering metals, or materials with metals, in general C23C ; manufacturing record carriers G11B 5/84)
Definition statement
This subclass/group covers:

Thin films deposition methods not provided in subgroups below.

the magnetic material being applied in the form of particles, e.g. by serigraphy {i.e. forming thick magnetic films and precursors therefor, e.g. magnetisable pastes, inks, glass frits (H01F 41/18 to H01F 41/24 take precedence; thick magnetic films H01F 1/0027) }
Definition statement
This subclass/group covers:

Deposition methods and apparatus for forming thick magnetic films, usually performed by macroscopic methods.

by cathode sputtering
Definition statement
This subclass/group covers:

Deposition methods and apparatus for forming thin magnetic films characterised by deposition methods.

Heat treatment; Thermal decomposition; Chemical vapour deposition
Informative references
Attention is drawn to the following places, which may be of interest for search:
Coating by evaporation or sputtering
from liquids
Definition statement
This subclass/group covers:

Deposition from liquids.

H01F 1/26 covers deposition from liquids using electric currents.

H01F 1/28 covers deposition from liquids by liquid phase epitaxy.

Informative references
Attention is drawn to the following places, which may be of interest for search:
Electrodeposition
for applying nanostructures, e.g. by molecular beam epitaxy (MBE)
Definition statement
This subclass/group covers:

Deposition methods and apparatus for forming multilayered nanostructures, especially spin-exchange-coupled multilayers corresponding to product subgroups H01F 10/324-H01F 10/3295, characterised by specific process steps leading to a specific change of properties of the grown superlattice (H01F 41/303-H01F 41/304) or to a given structure (H01F 41/305-H01F 41/309).

Informative references
Attention is drawn to the following places, which may be of interest for search:
Ion implantation
for applying conductive, insulating or magnetic material on a magnetic film {, specially adapted for a thin magnetic film}
Definition statement
This subclass/group covers:

Deposition methods and apparatus for applying a single layer on a magnetic thin film characterised by specific process steps.

H01F 41/34 covers deposition in patterns (i.e. using lithography).

Informative references
Attention is drawn to the following places, which may be of interest for search:
Ion implantation
Special rules of classification within this group

Spin filters capping layers for TMR/GMR structures (products) are also classified within method subgroup H01F 41/325.

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Last Modified: 10/11/2013