Recording or playback of information by relative movement between a record track and a transducer, the transducer directly producing, or being directly actuated by, modulation in the track being recorded or played-back, and the extent of modulation corresponding to the signal being recorded or played-back;

Apparatus and machines for recording or playback, and parts thereof, such as heads;

Record carriers for use with such apparatus and machines;

Associated working of other apparatus with such apparatus and machines.

The specific application specified in G11B is mentioned in the document, the document is classified in G11B. However, experience shows that many documents also contain features relevant to H01F. In this case the documents are classified in both places.

When the document is more about magneto-optical elements as such, it goes in G02F 1/09 or lower groups. However, if the field of application (G11B) is mentioned in the document or if the expert recognizes that the magneto-optical elements looks like those typically used in the G11B then the document should also be classified in the G11B

1.) Medium, media are synonyms of "record carrier".

2) "thin film" and "binderless" both apply to coated films of a (generally) uniformly deposited material, differing from "binder media" which comprises magnetic particles in a (usually organic) binder resin

3) vertical or perpendicular are used interchangeably in the art to refer to magnetization directions normal to the plane of the film

4) horizontal, longitudinal, in-plane are used interchangeably in the art to refer to magnetization directions lying in the plane of the film.

5) substrate, support, base are used interchangeably in the art to refer to the underlying rigid or flexible (in terms of tapes or floppy disks, for example) layer upon which other layers are deposited thereon.

6) seed layer, under layer, intermediate layer, orientation control layer, adhesion layer, crystal growth layer are all generally used terminology to describe (usually non-magnetic) layers deposited under the main magnetic layer(s) to assist in crystal growth and tuning of the magnetic properties of the main magnetic layer(s).

7) soft under layer (SUL) and keeper layer are used interchangeably to describe a soft magnetic layer used under a hard magnetic recording layer to provide a flux path.

Mainly vinyl disks and apparatuses for playing them

Marking record carriers in digital fashion: G06K

Selection of magnetic materials; thin magnetic films: H01F

Measuring electric or magnetic properties: G01R

Because of this situation, the following general rules apply:

Documents relating to the 'minority' carriers, e.g. tapes, webs, wires, cards, drums, are always classified in one of the subgroups concerning methods and apparatuses for a specific carrier form (G11B 5/004, G11B 5/008).

However, the 'record carrier' subgroups (G11B 5/76 and the subgroups which depend upon it) are only used if there is something interesting about the carrier itself (other than the materials of which it is made, for which see G11B 5/62 et seq.) e.g. a disk has a series of timing slots or holes in it, or a drum is made removable by separating into two halves longitudinally, etc.

If an aspect (e.g. head, method of recording, servo tracking, etc.) is of more general application, or if there is a place more specific to it elsewhere in the scheme (e.g. G11B 5/584 is specifically for track following on tapes), it is also classified there.

G11B 5/00 partially overlaps with H01F, G01R, H01L. The following general rules apply:

In H01F 10/00 are classified "Magnetic thin films" in general, i.e. thin films whose application is not specific or not limited for magnetic recording or reproducing. Examples are Magnetic Spin Tunnel Junctions (STJ) or Spin Valve structures (SV) which are classified in H01F 10/3254 and H01F 10/3268 respectively and not in G11B 5/39 if the invention does only relate to the magnetic films and their magnetic coupling, without a specific adaptation of the junction or Spin valve to MR reproducing heads, i.e. if the use of the STJ or SV as reproducing head is not mentioned or mentioned among other possibilities and the invention has no specific information related e.g. to the shaping, shielding and biasing necessary for a STJ to be adapted as reproducing head. If, on the contrary, the invention only refers specifically to an adaptation of the STJ or SV thin film structure as reading head, then only the code G11B 5/39 (or subcodes) is given. When the invention has both aspects, i.e. the thin film structure in general and the specific application as reproducing head, then both codes are given.

The same rule applies to G01R, in particular G01R 33/09, where are classified magnetoresistive devices in general (i.e. MR devices whose application is not specific or not limited or specially adapted for magnetic recording or reproducing) and to H01L, in particular H10N 50/00, where are classified devices using galvano-magnetic or similar magnetic effects in general, i.e. not specially adapted for magnetic recording or reproducing.

The terms "thin film" and "binderless" both apply to coated films of a (generally) uniformly deposited material, differing from "binder media" which comprises magnetic particles in a (usually organic) binder resin.

Vertical or perpendicular are used interchangeably in the art to refer to magnetization directions normal to the plane of the film.

Horizontal, longitudinal, in-plane are used interchangeably in the art to refer to magnetization directions lying in the plane of the film.

Substrate, support and base are used interchangeably in the art to refer to the underlying rigid or flexible (in terms of tapes or floppy disks, for example) layer upon which other layers are deposited thereon.

Seed layer, under layer, intermediate layer, orientation control layer, adhesion layer and crystal growth layer are all generally used terminology to describe (usually non-magnetic) layers deposited under the main magnetic layer(s) to assist in crystal growth and tuning of the magnetic properties of the main magnetic layer(s).

Soft under layer (SUL) and keeper layer are used interchangeably to describe a soft magnetic layer used under a hard magnetic recording layer to provide a flux path.

This group refers to an obsolete technology.

Recording, reproducing and erasing methods and corresponding apparatuses specific for magnetic recording disks (e.g. definition of tracks, control of skew angle between head and tracks, subdivision in sectors etc.)

Timing or synchronising arrangements are classified in G11B 27/10

Signal processing for digital recording or reproducing is generally classified in G11B 20/10 unless specific for the recording method, in which case the class G11B 5/09 is given.

Structure or manufacture of head housing, e.g. sliders

Structure or manufacture of shields for shielding the head against electric or magnetic fields

Measures and methods (e.g. control of the operating functions) to protect the head against damages, e.g. against excessive temperature, head-record carrier collisions (means for their prediction, detection and avoidance), wear.

Structural means (e.g. extra layer included in the recording or reproducing head or special layer compositions thereof) to reduce physical detrimental influence (e.g. contamination, humidity) are classified in G11B 5/3103. Structural means to reduce the influence of wear are classified in G11B 5/3103 if they refer to thin film heads and in G11B 5/255 in all other cases.

Structural means (e.g. extra layer included in the recording or reproducing head or special layer compositions thereof) for reducing the influence of temperature changes (e.g. heat dissipation layers or structures avoiding deformation of the head or the pole tip protrusion due to temperature expansion of the pole are classified in G11B 5/3133

Functional testing of the heads when the manufacturing is completed and arrangements therefore, e.g. spin stands or test beds.

Measuring electric or magnetic properties: G01R

Record carriers comprising a laminate of one or more layers deposited on a substrate. The record carrier consists of a layer of magnetisable material deposited on a substrate intended for information storage.

Aspects of magnetic recording media are classified as follows:

Documents directed to patterned media appropriate for G11B 5/74 that also contain a specific reference to layer structure, composition, etc. should be classified in G11B 5/62 and in G11B 5/74.

Documents that also contain features relevant to the specific selection of magnetic materials in general should also be classified in H01F 1/00 (bulk magnetic materials) or H01F 10/00 (for thin films).

Figure 1. Example of Longitudinal Anisotropy.

Figure 2. Example of Vertical Anisotropy.

Media or magnetic material including a thin-film magnetic layer represented by a continuous layer free of polymeric binder having a thickness typically ranging from Angstrom level to several micrometres.

Media characterised by aspects of the magnetic layers other than the composition or the requirement that a plurality of magnetic layers exist in a specific interaction. For example, media where the orientation of a single magnetic layer is the inventive feature (tilted media), how the magnetic layer is utilized (servo tracking), etc.

A soft magnetic layer or SUL is classified in this subgroup and its indents, not under G11B 5/73.

Each inventive embodiment in the document should be classified separately and if one embodiment is directed to two or more magnetic layers and another embodiment is directed to the magnetic compositions of the layers, classification is in G11B 5/66 – G11B 5/678 and also in G11B 5/65 – G11B 5/658.

Magnetic medium having a single magnetic layer that is characterised by its composition.

Example: A Mn-Al recording layer.

Magnetic medium in which the magnetic layer includes a majority component (by weight %, volume % or mole %) of iron or nickel, but does not also contain cobalt, oxygen or an inorganic, non-oxide compound of Si, N, P, B, H or C.

Magnetic medium in which the magnetic layer includes a majority component (by weight %, volume % or mole %) of cobalt, but does not also contain oxygen or an inorganic, non-oxide compound of Si, N, P, B, H or C.

Magnetic medium in which the magnetic layer includes an inorganic, non-oxide compound of Si, N, P, B, H, or C. This compound can be part of the alloy (e.g. CoCrPtB) or as a segregant compound separating the magnetic grains in the layer (e.g. FePt grains separated by a carbon or boron-nitride segregant material).

Magnetic layers containing organic compounds should be classified in G11B 5/65 for a thin film-type magnetic layer or in the G11B 5/68 area for a binder-type magnetic layer.

Magnetic medium in which the magnetic layer includes magnetic metal oxide or a magnetic layer with uncombined oxygen present within the magnetic elemental metal or the alloy lattice structure, e.g. CoO_x or CoCrPt-SiO₂ magnetic layers.

Magnetic medium that contains more than one magnetic layer on the same side of the substrate. This includes soft, hard or paramagnetic layers, but excludes antiferromagnetic layers.

Multiple magnetic layers separated by non-magnetic or antiferromagnetic layers are classified in G11B 5/676.

In this subgroup, a record carrier must include a plurality of magnetic layers and not a single magnetic layer with two or more non-magnetic layers.

A classification symbol is given related to the composition and structural arrangements of a spin-exchange coupled multilayer in the corresponding subgroups H01F 10/32 - H01F 10/3295.

Magnetic medium including two or more magnetic layers, in which at least one of the magnetic layers is a soft magnetic layer.

Magnetic medium including two or more magnetic layers, and in which each layer has a different composition.

Example:

Figure 1. A FePt:C / CoPt:TiO₂ layer structure or a laminate magnetic layer structure of FePt:C / FePt:SiO₂ / FePt:C.

Magnetic medium including two or more magnetic layers, each having the same chemical constituents, but differing in crystal lattice or molecular arrangement.

Examples:

Figure 2:

Figure 3:

Figures 2 and 3. Unique magnetic layers with distinct oblique inclination angles (Figure 2) and unique magnetic layers with distinct grain size requirements (Figure 3).

Magnetic medium including two or more magnetic layers, wherein at least one intervening nonmagnetic or antiferromagnetic layer is between the magnetic layers.

A classification symbol is given related to the composition and structural arrangements of a spin-exchange coupled multilayer in the corresponding subgroups H01F 10/32 - H01F 10/3295.

If a document discloses an inventive embodiment having exactly two magnetic layers separated by at least one intervening nonmagnetic or antiferromagnetic layer and another different inventive embodiment having three or more magnetic layers separated by intervening nonmagnetic or antiferromagnetic layers, an Inventive classification is given in G11B 5/676 and an Inventive classification is also given in G11B 5/678.

Magnetic medium in which the medium has at least three magnetic layers on a single side of the substrate, with at least one intervening non-magnetic or antiferromagnetic layer.

Examples: (Co/Pt)_n or (Co/Pd)_n superlattice-type media layers.

If a document discloses an inventive embodiment having exactly two magnetic layers separated by at least one intervening nonmagnetic or antiferromagnetic layer and another different inventive embodiment having three or more magnetic layers separated by intervening nonmagnetic or antiferromagnetic layers, an Inventive classification is given in G11B 5/676 and an Inventive classification is also given in G11B 5/678.

One or more coatings having specific utility for protecting the record carrier, e.g. from shock, static, head-medium crash, friction or corrosion.

The protective coatings on the outermost layer of the record carrier above any magnetic recording layer structure – the "outermost" being the layer furthest from the substrate and closest to the surface facing a recording or reproducing apparatus.

Documents directed to protective layers used on magnetic record carriers, as well as on magnetic recording or reproducing apparatus components, should be given an additional symbol in G11B 5/255, G11B 5/31, G11B 5/40 or G11B 5/3106, as appropriate.

Documents directed to protective layers used on a plurality of media types, e.g. optical, ferroelectric or optomagnetic, should be given a classification here if they also recite use on magnetic record carriers.

Other aspects of magnetic recording media are classified as follows:

Protective coatings including a bonding agent, such as for use above binder media type record carriers (i.e. those whose magnetic layers would be covered under G11B 5/68), should be classified in G11B 5/728.

Protective coatings that are specific to thin-film media type record carriers (i.e. those whose magnetic layers would be covered under G11B 5/64) or protective coatings that are generic to both binder-type and thin-film-type record carriers should be classified in G11B 5/72 – G11B 5/727. If the use with binder-type media is deemed critical, an additional classification can be given in G11B 5/728.

Classification within this area follows the general rules below:

Protective coatings in which the material used has an express anti-corrosion activity or the protective coatings contain a material that is art-recognized as serving an anti-corrosive function, e.g. Cr.

Examples of corrosion resistance include tests in the description, e.g.

or corrosion resistance in the claims.

Protective coatings that include at least one lubricant material, i.e., a substance for reducing friction or wear.

If both a carbon protective coating and the lubricant concern the invention, classification should be done in G11B 5/7266 and in G11B 5/725 – G11B 5/7257 (based on the type of lubricant).

Carbon coatings, unless explicitly stated as being used for their lubricity, are not considered lubricants within the scope of this subgroup. In those situations, an additional symbol should also be given in the appropriate Inorganic Protective Coating subgroups G11B 5/7264 – G11B 5/727, when the carbon coating is explicitly disclosed.

The lubricant is an organic compound of fluorine.

The fluorine containing lubricant that includes a perfluoropolyether compound.

Protective coating including two or more coatings, where each coating is explicitly disclosed.

Most record carriers include a protective inorganic (usually carbon) coating along with a lubricant coating. If one of these coatings is lacking an indication of critical interaction with another of these coatings (e.g. modified for improved lubricant bonding), classification should only be done in the corresponding single coating areas: G11B 5/72, G11B 5/725 or G11B 5/727.

At least one of the protective coatings that includes an inorganic coating material that is a non-carbon containing coating.

At least one of the protective coatings that includes a non-organic carbon-based coating material.

Example 1:

Example 2:

Protective coatings that include at least one non-organic carbon-based coating material and at least one lubricant coating; the lubricant can be physically or chemically bonded to the carbon-based coating; classification should also be done in G11B 5/725 – G11B 5/7257, depending on the type of lubricant.

Protective coatings that include at least one non-organic carbon-based coating material, where that carbon-based coating further includes uncombined nitrogen.

Example:

Single protective coating, which is an inorganic carbon-based material, i.e. a compound that does not include organic carbon bonds.

Protective coating that is a bonding-agent type of coating, such as for use above binder-type media.

Protective coatings that are specific to thin-film media type record carriers (i.e. those whose magnetic layers would be covered under G11B 5/64) or protective coatings that are generic to either binder-type or thin-film-type record carriers should be classified in G11B 5/72 – G11B 5/727.

If the use of a specific protective layer above a binder-type media layer is disclosed even though the protective layer(s) would be classified in G11B 5/72 – G11B 5/727, an additional symbol may be given in G11B 5/728.

Magnetic media in which each medium includes one or more non-magnetic layers under a lowermost magnetic recording layer.

Base layers are substrates or non-magnetic layers designated either by position (e.g. precoat layer, prelayer, base layer, underlayer, intermediate layer, lower layer, sublayer, ground layer, etc.) or function (e.g. nucleation layer, seed layer, barrier layer, corrosion prevention layer, diffusion prevention layer, texture layer, etc.).

Other aspects of magnetic recording media are classified as follows:

Layers formed by chemically modifying a surface layer (e.g. an oxidized surface layer formed from a previously deposited layer) are considered a separate layer and should be placed in the appropriate subgroup. Note that a surface layer formed as part of a recording medium substrate is still considered part of the substrate for classification purposes (i.e. placement would be in the coated or composite substrate areas).

Classification in this area is primarily of the claimed invention with each embodiment of claimed subject matter being Inventive unless the subject matter recited is nominal and well known in the art. Relevant disclosure in the specification should be classified primarily as Additional information unless deemed particularly relevant to the invention as a whole, in which case it may be given an Inventive symbol.

Base layers in which the invention is directed to the initial substrate or support upon which all other layers are deposited are classified in G11B 5/739 - G11B 5/73937.

Base layers in which the recording or magnetizable layer is a continuous-type layer free of polymeric binder (i.e. "thin film media") are classified in G11B 5/736 - G11B 5/7379 if on the same side of the substrate as the magnetic layer or G11B 5/7353 if a backcoat layer.

Base layers in which the recording or magnetizable layer is a mixture of magnetic particles and a polymeric binder (i.e. "binder media") are classified in G11B 5/733 - G11B 5/7334 if on the same side of the substrate as the magnetic layer or G11B 5/735, G11B 5/7356, or G11B 5/7358 if a backcoat layer.

The following figures illustrate where appropriate base layers should be classified, depending on whether the media in question includes a soft under layer (SUL) (also termed a 'Keeper layer').

The following flow-chart provides guidance on the precedent notes within this portion of the scheme.

An invention is to 'plural inventive non-magnetic layers' for the purpose of placement in appropriate subgroups of G11B 5/736 - G11B 5/7379 if the independent claim is directed to multiple non-magnetic layers, even if these layers are recited in name only or if dependent claims recite multiple non-magnetic layers in other than name only. The sole exception would be if a dependent claim further limits the structural location of one of the inventive non-magnetic layers relative to an included soft magnetic layer (such that only a single non-magnetic layer is now above or below an included soft magnetic layer - see example 2, below).

Examples:

Magnetic recording media having one or more base layers formed from a binder with included non-magnetic particles or filler.

A base layer deposited solely as part of a substrate that has no disclosed utility in establishing the magnetic properties of the recording layer would not be classified here, even if containing non-magnetic particles. Such a layer would be classified in G11B 5/739 according to the scheme title of G11B 5/733 and would include layers typically denoted as smoothing layers, coating layers, etc. that are taught as part of the substrate, per se.

Underlayers used in binder-type media cases are typically referred to as lower layers, primer layers, undercoats, etc. and would be classified here if including non-magnetic particles. If without non-magnetic particles they are classified in G11B 5/73.

Where the non-magnetic particles included in the base layer are only nominally recited and the inventive subject matter is directed to the base layer binder composition (or structure) or the composition (or structure) of a non-particulate additive (e.g. lubricant, viscosity aid, etc.), classification is in G11B 5/7334.

Magnetic recording media having one or more base layers formed from a binder with included non-magnetic particles or filler, where the particles are recited in name only and the inventive subject matter is in the binder composition (or structure) or a non-particulate additive composition (or structure).

If the non-magnetic particles are recited in more than name only and are deemed inventive, classification should be in G11B 5/733. If inventive subject matter is directed to both the particles and the binder (or additive), then classification should be given in both G11B 5/733 and G11B 5/7334.

Magnetic recording media having one or more base layers formed on the opposite side of a support from where the recording layer is located (i.e. back layers).

Also included are back layers including a binder with non-magnetic particles or filler, where the particles or filler are nominal and recited in name only.

If the back layer includes non-magnetic particles or filler and the particles or filler are recited in no more than name only, classification is in G11B 5/735 and not in G11B 5/7356 - G11B 5/7358. If any inventive subject matter is directed to the particles, classification is in G11B 5/7356 or G11B 5/7358 .

Magnetic recording media, each having one or more back layers wherein the recording layer is a thin-film type structure, e.g. sputtered layer, CoCrPt alloy layer, Co/Pt multilayers.

Magnetic recording media having one or more back layers characterized by inventive non-magnetic particles (e.g. oxides, carbon black, etc.).

If the back layer includes non-magnetic particles or filler and the particles or filler are recited in no more than name only, classification is in G11B 5/735.

If the non-magnetic particles or filler are recited as being added to achieve a specified inventive or non-conventional physical property, classification is in G11B 5/7358.

Back layers including non-magnetic particles or filler recited as being added to achieve a specified inventive or non-conventional physical property.

If the recited property is nominal or conventional (e.g. carbon black is added to control the electrostatic property of the back layer to known, conventional ranges), classification is in G11B 5/735 and its subgroups.

Base layers between a substrate and a soft magnetic underlayer.

Base layers including two or more inventive layers between a substrate and a soft magnetic underlayer wherein the inventive subject matter lies in the composition or structural arrangement of the layers.

For a base layer to be considered 'inventive' it should be recited in the independent claim (even if recited in name only) or have non-nominal, inventive features.

Base layers including two or more inventive layers between a substrate and a soft magnetic underlayer wherein the physical macroscopic structure (e.g. texture, patterning, etc.) or microstructure (crystal plane, crystallographic texture, etc.) of at least one layer is also deemed inventive.

If the physical structure is recited in name only and is not deemed inventive, classification should be based on other aspects of the recording media base layers.

Base layers including only a single inventive layer between a substrate and a soft magnetic underlayer wherein the layer is recited as including non-trace amounts of nickel.

If the composition of the underlayer is not inventive, classification should be based on other aspects of the recording media base layers (e.g. circa 2010, NiP underlayers are well established and mere recitation of an NiP underlayer would not result in placement in this subgroup without additional, inventive features).

Base layers including only a single inventive layer between a substrate and a soft magnetic underlayer wherein the layer is recited as including non-trace amounts of chromium.

If the composition of the underlayer is not inventive, classification should be based on other aspects of the recording media base layers (e.g. circa 2010, Cr-alloy underlayers are well established and mere recitation of a Cr-alloy underlayer would not result in placement in this subgroup without additional, inventive features).

Base layers including only a single inventive layer between a substrate and a soft magnetic underlayer wherein the layer is recited as being polymeric or a resin-based underlayer.

This includes polymeric or resin-based non-magnetic underlayers having particles, provided they are located under a soft-magnetic layer.

Base layers having specific utility for use in energy assisted (HAMR, TAMR, etc.) magnetic recording.

Barring exceptional circumstances, most classification into G11B 5/7366 will be Additional information. If the base layer is critical and inventive to the energy assisted recording medium, an Inventive symbol may be placed in this subgroup.

Base layers including one inventive layer between a substrate and a soft magnetic underlayer wherein the physical macroscopic structure (e.g. texture, patterning, etc.) or microstructure (crystal plane, crystallographic texture, etc.) of the layer is also deemed inventive.

If the physical structure is recited in name only and is not deemed inventive, classification should be based on other aspects of the recording media base layers.

Non-Polymeric base layers between a soft magnetic underlayer and the recording layer structure or, if no soft magnetic underlayer in the recording medium, any base layers under the recording layer structure.

Base layers including two or more inventive layers in the required structural location within the media wherein the inventive subject matter lies in the composition or structural arrangement of the layers.

For a base layer to be considered 'inventive' it should be recited in the independent claim (even if recited in name only) or have non-nominal, inventive features.

Base layers including two or more inventive layers in the required structural location within the media wherein the physical macroscopic structure (e.g. texture, patterning, etc.) or microstructure (crystal plane, crystallographic texture, etc.) of at least one layer is also deemed inventive.

If the physical structure is recited in name only and is not deemed inventive, classification should be based on other aspects of the recording media base layers.

Base layers including only a single inventive layer in the required structural location within the media wherein the layer is recited as including non-trace amounts of nickel.

If the composition of the underlayer is not inventive, classification should be based on other aspects of the recording media base layers (e.g. circa 2010, NiP underlayers are well established and mere recitation of an NiP underlayer would not result in placement in this subgroup without additional, inventive features).

Base layers including only a single inventive layer in the required structural location within the media wherein the layer is recited as including non-trace amounts of chromium.

If the composition of the underlayer is not inventive, classification should be based on other aspects of the recording media base layers (e.g. circa 2010, Cr-alloy underlayers are well established and mere recitation of a Cr-alloy underlayer would not result in placement in this subgroup without additional, inventive features).

Base layers in the required structural location within the media having specific utility for use in energy assisted (HAMR, TAMR, etc.) magnetic recording.

Barring exceptional circumstances, most classification into G11B 5/7375 will be Additional information. If the base layer is critical and inventive to the energy assisted recording medium, an Inventive symbol may be placed in this subgroup.

Base layers including two or more inventive layers in the required structural location within the media wherein the physical macroscopic structure (e.g. texture, patterning, etc.) or microstructure (crystal plane, crystallographic texture, etc.) of at least one layer is also deemed inventive.

If the physical structure is recited in name only and is not deemed inventive, classification should be based on other aspects of the recording media base layers.

Base layers in the required structural location within the media having specific utility for use as seed or seeding layers.

Base layers in which a layer or laminate provides physical integrity to a magnetic recording media by acting as substrate or support for a magnetic recording layer.

This subgroup and its subgroups provide for substrates set forth with chemical or structural specificity.

Care must be taken to distinguish between (a) a composite or coated substrate and (b) a subsequently formed non-magnetic base layer when considering binder media type structures. A layer recited as an "underlayer", "undercoat", "lower layer" or "intermediate layer" is a layer distinct from a substrate. For a layer to be considered as a part of a substrate, it must be recited specifically in the disclosure of forming the substrate or as part of a substrate prior to any deposition of a recording layer structure.

Examples:

Base layers including a substrate having at least one formed layer or portion comprising inorganic material.

Resin or binder material including inorganic particles wherein the substrate, in total, would be considered a polymeric or organic substrate are classified in the appropriate subgroup, i.e. G11B 5/73923 - G11B 5/73937.

Substrates which are formed from inorganic compounds and are disclosed primarily in terms of property values are classified in G11B 5/739, i.e. the inorganic materials are nominal and recited in name only.

Inorganic substrates having two or more contiguous layers or portions of distinct components (e.g. glass containing metallic particles, etc.).

Included in this subgroup are an inorganic structural element and an organic compound; e.g. metallic particles and resin, provided that the substrate as a whole would be considered an inorganic substrate.

Substrates having only a single alloy layer, i.e. heterogeneous mixtures of elements that are not separate phases, are not classified in this subgroup, but in other subgroups appropriate to the recited alloy.

Included herein are NiP plated substrates wherein the NiP plating layer is inventive and is clearly taught as part of the substrate. NiP layers deposited with the purpose of corrosion prevention, adhesion, or establishing the microstructure of the recording layer are classified in G11B 5/7363 or G11B 5/7371 . The lines between these subgroups and the current subgroup can often be ascertained by looking at the method of depositing the NiP layer and/or whether the NiP layer is deposited on an already commercially formed substrate (as opposed to being deposited to form the substrate).

Base layers including a substrate having at least one contiguous layer of a silicon compound.

Base layers including a substrate that is an elemental metal or a metal alloy.

Base layers including a substrate that is elemental aluminium or titanium or an aluminium or titanium alloy (i.e., an alloy containing 40% or more aluminum and/or titanium).

Base layers including a substrate that is composed of glass or ceramic, including amorphous or crystalline glasses.

Included in this subgroup are glass or ceramic substrates including texturing.

Substrates composed of a solid polymer compound or polymeric composition (e.g. polyurethane, melamine resin, polyamide, etc.).

Substrates that are formed from organic polymer compounds and that are disclosed primarily in terms of property values are classified in G11B 5/739, i.e. when the polymer materials are nominal and recited in name only.

Substrates that are materials other than an ester and are composed of a plurality of layers (e.g. a laminate or distinct particulate or non-particulate compounds containing in a single layer).

This subgroup includes coatings on an organic substrate directed to the improvement of the properties of the substrate and not affecting the crystalline anisotropy or magnetic orientations of a subsequently deposited layer (e.g. a coating solely for adhesive, texture, etc.).

The distinction between a lower layer used in a binder-type media and a coating layer for purpose of classification here depends on the recited end use of the layer, as most are composed of similar mixtures of binder material plus non-magnetic particulate filler. If the layer is recited as a "lower layer", "under layer", "first layer", it is usually directed to establishing the deposition of the magnetic layer and are classified in G11B 5/733 - G11B 5/7334. The same applies if the deposition is a "wet-on-wet" process where the magnetic layer is immediately deposited following the non-magnetic layer.

If the invention is directed to the substrate and the layer is included to tailor the surface properties of the substrate (e.g. a binder and particulate layer deposited on a polyamide base to create a polyamide substrate having specific roughness profile), then classification should be in this subgroup only.

Base layers including a substrate in which the polymer substrate includes an ester group thereon such as carboxylic acid ester.

Base layers including a substrate that comprises a polyester substrate including a naphthalene ring structure.

Substrates that are composed of a plurality of layers, wherein at least one inventive layer is a polyester.

This subgroup includes coatings on a polyester substrate directed to the improvement of the properties of the substrate and not affecting the crystalline anisotropy or magnetic orientations of a subsequently deposited layer (e.g. a coating solely for adhesive, texture, etc.).

The distinction between a lower layer used in a binder-type media and a coating layer for purpose of classification here depends on the recited end use of the layer, as most are composed of similar mixtures of binder material plus non-magnetic particulate filler. If the layer is recited as a "lower layer", "under layer", "first layer", it is usually directed to establishing the deposition of the magnetic layer and are classified in G11B 5/733 - G11B 5/7334. The same applies if the deposition is a "wet-on-wet" process where the magnetic layer is immediately deposited following the non-magnetic layer.

If the invention is directed to the substrate and the layer is included to tailor the surface properties of the substrate (e.g. a binder and particulate layer deposited on a polyester base to create a polyester substrate having specific roughness profile), then classification should be in this subgroup only.

Base layers including a polyester substrate that has been coated or surface treated.

Included in this subgroup are polyester substrate leader and trailer tapes.

Base layers including a polyester substrate, typically containing particles, which has a defined and inventive roughness profile/property or surface feature, e.g. protrusion density.

Base layers including a substrate that has a specific organic ring structure, e.g. benzyl groups or 1,4-dihydroxydimethylbenzene.

Record carriers (tapes, cards, disks) specially shaped, e.g., bit patterned media, or discrete-track media

Acquisition of servo patterns and processing thereof G11B 5/596

Master disks - i.e. original disks drawn preliminarily with magnetic information corresponding to a preformatted signal to be magnetically transferred (e.g. servo patterns or reference servo patterns for self-servo- writing) - used to duplicate information on lave disks

When the medium to which information has to be transferred is in direct contact with the master disk the method or apparatus is classified in G11B 5/865.

In general terms, this group is subdivided into:

systems (G11B 7/002- G11B 7/003) e.g. tape, card, disc

methods of recording or reproduction (also erasing, overwriting), including holographic recording of coded data (G11B 7/004 - G11B 7/0065); re-recording of data (transcription) (G11B 7/28)

arrangement of information e.g. control area, land and groove structure, including details of discrete physical structures such as "pits" (G11B 7/007- G11B 7/013)

access e.g. moving the optical pickup (G11B 7/085)

servo e.g. moving the objective lens (G11B 7/09)

heads e.g. types of heads (G11B 7/12, G11B 7/14)

record carriers e.g. CD, DVD, BD (G11B 7/24)

In principle, only aspects of the above subjects that are particularly adapted as a result of using light for recording/reproduction (e.g. track pitch, pit depth adapted to the wavelength of light used) should be classified in G11B 7/00.

The following "horizontal" Indexing Codes are assigned where appropriate:

Further information of subgroups:

G11B 7/241: should be used as little as possible e.g. where different materials for various layers are disclosed and the invention does not reside in one particular layer (e.g. EP2224444, US2005129899)

G11B 7/242: this group and subgroups are used when the recording material does not fall (exclusively) into one of the higher dot subgroups; e.g. comprising inorganic and organic material (US2003175616, JP58062094)

G11B 2007/2445 :

G11B 7/2467 : R1−N=N−R2

G11B 7/247: styryl dye

G11B 7/2472 :

G11B 7/2475 :

G11B 7/2478 :

G11B 7/248:

G11B 7/25: in the recording layer

Examples:

G11B 7/254: topcoat layers = outermost layer

G11B 7/2542 ;

Examples:

G11B 7/2545 : e.g. carbon containing coating , DLC coating - (EP0410704)

G11B 7/256: (EP1343159)

G11B 7/257: Only layers provided in direct contact with the recording layer are classified here. Other protecting layers, which are not toplayers (G11B 7/254) are classified under G11B 7/252.

Examples:

G11B 7/2575 ;

Examples:

G11B 7/2578 ;

Examples:

Uncommon or outdated technology (in 2011)

Uncommon or outdated technology (in 2011)

Optical tape data storage systems that feed an optical tape helically around a drum while writing and/or reading digital data on the optical tape see e.g. US5524105

Uncommon or outdated technology (in 2011)

Uncommon or outdated technology (in 2011)

Optical storage of small amounts of data on cards (analogous to magnetic strip on bank cards) is normally classified in G06K 19/06009 (media) or G06K 7/10 (methods and apparatus)

This sub-group is a residual sub-group and should only be assigned if there is something about an optical disc system related to the optical nature of recording and reproduction that is not classifiable elsewhere in G11B 7/00

this sub-group includes systems in which the label information is written optically on the non-data side of disc e.g. technologies such as Hewlett Packard LightScribe and Yamaha/FujiFilm LabelFlash

for labelling of optical data carriers that does not write the label data with the optical head used to write the main data, see G11B 23/40

This sub-group is a residual sub-group and should only be assigned if (part of) the subject-matter can not be classifed elsewhere, in particular in one of the following:

G11B 7/0948: servo control specially adapted for detection and avoidance or compensatin of imprefections on the carrier e.g. dust, scratches, dropouts

G11B 20/1889: defect management

G11B 20/1816 testing e.g. of dropouts

G11B 7/268: checking for defects during/after manufacture

G01N 21/9506: Systems specially adapted for investigating the presence of flaws or contamination in optical discs

Indexing Code G11B 2007/00457 is assigned for two photon recording (including two photon recording in holographic data storage media

For example, recording data as "pits" in a dye recording layer (e.g. CD-R, DVD-R, BD-R) not to be confused with spectral hole burning (see G11B 7/00453) for materials used in recording layers see G11B 7/242 and subgroups

Uncommon or outdated technology (in 2011)

Generally involves thermal expansion of a recording layer to form bumps which alter the amount of reflected light because ot the phase difference (interference effect) between light reflected by the protuberance and light reflected by the surface which is not raised.

Figure from EP 338776

For materials used in recording layers see G11B 7/242 and subgroups.

Uncommon or outdated technology (in 2011)

Multiple bits can be stored in the same space using different frequencies atoms or molecules which are in different environments. The absorption line of a material is inhomogeneously broadened (comprised of many homogeneously broadened lines, due to the slightly different energies and therefore frequencies/wavelengths corresponding to the different environments.

Not to be confused with ablative recording (which is a thermal effect, not a spectral one).

For materials used in recording layers see G11B 7/242 and subgroups.

For example, recording using chalcogenide materials e.g. GeSbTe.

This classification should only be assigned if:

Recording pulse sequences are classified in G11B 7/0062 (for overwritable media) or in G11B 7/00456 (for write-once media)

Phase change materials are classified in G11B 7/243 and subgroups.

For example, photochromic recording in which the colour is changed; documents concerning recording in which the texture of the surface is changed to change the reflectivity are classifiable here.

Both G11B 7/00456 and G11B 7/0062 are assigned if the strategy or strategies disclosed is/are applicable to both write-once and rewritable media. Example:

Figure taken from EP1548710

This class should only be assigned for invention information (mostly older technology) in which the actual data is read during recording and compared with the data that should have been recorded, or verification using a separate read/verify beam.

Running optical power control (ROPC): G11B 7/1263

Walking optical power control : G11B 7/1263

Documents are only assigned this class (or code) if the particular problem or solution of the invention disclosed relates to the aspect of phase depth AND if there is no better classification (see below). (Phase depth effects are the most common basis for reproduction of information in G11B 7/00: the reproduction of the usual data pits in a CD, DVD, BD (i.e. pits in the plastic substrate, covered with a reflective layer) relies on this effect.)

Also reproduction of phase change media normally involves a phase depth effect, because the refractive indices of the various layers are adjusted to give a particular optical path length difference. (n.b. "phase" here has two different meaning - the physical state of the material ("phase change material") and the optical or physical difference in path length between two aread resulting in contructive or destruction optical interference "phase depth")

G11B 7/24085 (Arrangement of the information on the record carrier) Details of discrete information structures, e.g. shape or dimensions of pits, prepits

(n.b. From 2012 revision of the IPC introduces new group G11B 7/2407 for media characterised by the pits, and ECLA will be revised correspondingly)

For example, reproduction of data recorded in a photochromic material.

Mostly uncommon or outdated technology (in 2011) - nearly all modern commercial disc technology is of the write-once type (e.g. recording in dye layer) or of the overwritable type (e.g. recording in a layer of phase change material).

Mostly uncommon or outdated technology (in 2011) - most modern phase change materials are overwritable.

Rewritable is often synonymous with overwritable (but rewritable may mean merely erasable in old documents).

Both G11B 7/00456 and G11B 7/0062 are assigned if the strategy or strategies disclosed is/are applicable to both write-once and rewritable media.

See Figure of a pulse strategy under G11B 7/00456.

Relationship between groups:

There are subgroups for certain aspects of holographic recording and where one (or more) or those subgroups is relevant they are assigned, and G11B 7/0065 or Indexing Code G11B 7/0065 are not assigned unless

there is "invention" information relevant to the system as a whole, or

if there is no better classification for the invention information.

Warning: These "holographic" subgroups were created in the second half of 2009, and the reclassification from G11B 7/0065 has not been systematically done. For documents published before 2010, G11B 7/0065 and Indexing Code G11B 7/0065 should be searched.

If there is no subgroup specific to holography for the invention subject-matter (e.g. there are no specific subgroups under G11B 7/242 for specific materials for holography), then the relevant general class is assigned and the Indexing Code G11B 7/0065. For example:

G11B 7/08564 for galvanomirrors e.g. used in angular multiplexing G11B 7/128 for SLM, acousto-optical, electro-optical, magneto optical modulators G11B 7/128 and G11B 7/1369 if modulator is liquid crystal device

G11B 7/1392 for a diffuser (e.g. in speckle holography)

G11B 7/1365 for polarization rotators G11B 7/1372, or subgroup, for lenses G11B 7/1356 for double prism beam splitter G11B 7/1395 for other beam splitters

Aspects for data formats for standards such as CD, DVD, BD are not classified in G11B 7/007 unless the technical problem underlying the invention arises because of the optical nature of the recording. In such cases the documents may be classifiable both in G11B 7/007 and in G11B 20/00.

Standards for various aspects of the formats of optical discs are available from the Internet site of ECMA (www.ecma.org).

(e.g. CD-ROM, DVD-ROM, DVD-RAM, DVD-R, DVD-RW, CD-RW Ultra-speed)

White Papers for the Blu-ray Disc Format are available from the Internet site of the Blu-ray Disc Association (www.blu-raydisc.com)

e.g. the Physical Format Specifications for BD-RE and for BD-ROM

There are also ECMA standards for holographic discs (HVD-ROM, HVD)

When the invention information concerns multiplexing, the document should be classified in G11B 7/00772 (since it has to do with the arrangement of the information) and assigned the relevant EC for the means (elements) by which the multiplexing is done. For example:

angular (azimuth) multiplexing:

G11B 7/08564 for deformable or movable mirrors and G11B 7/1362 when the movable mirror cooperates with stationary mirror(s):

This subgroup was created in the second half of 2009, and the reclassification from G11B 7/0065 has not been systematically done. For documents published before 2010, G11B 7/0065 and G11B 7/0065 should be searched.

For example, separate layers containing servo information for holographic discs, or marks around the edge for aligning page type holographic media.

Servo information for volume storage media that are not holographic: classify G11B 7/0938 (or Indexing Code G11B 7/0938 if the document discloses these details, but it is not particularly relevant to the invention information) in addition to the Indexing Code G11B 7/00:00S4 to indicate the volumetric aspect of the storage medium itself.

Warning: This subgroup was created in the second half of 2009, and the reclassification from G11B 7/0065 has not been systematically done. For documents published before 2010, G11B 7/0065 and Indexing Code G11B 7/0065 should be searched.

Only aspects of format that are adapted to solve a problem related to the optical recording. (In general, the data formats for optical recording media are not very closely related to the optical aspect and are classified in G11B 20/12)

Uncommon or outdated technology (in 2011)

Apparatus/methods aspects of access e.g. multiplexing are classified here, and if appropriate in the relevant optical element group.

If the optical elements used are not especially adapted for the type of access, but e.g. just used or controlled in a special way then the document should be classified in G11B 7/083 and coded in the appropriate optical element group (e.g. galvanomirror G11B 7/08564 or G11B 7/00:0085B3).

If it is the arrangement of the information aspect of the multiplexing that is "invention information" it is classified in G11B 7/00772

Warning: This subgroup was created in the second half of 2009, and the reclassification from G11B 7/0065 has not been systematically done. For documents published before 2010, G11B 7/0065 and G11B 7/0065 should be searched.

Changing layers in media with multiple data layers e.g. dual layer DVD.

For example, multiplexing in holographic storage of data.

Uncommon or outdated technology in 2011.

Methods in which the beam is driven back and forth to generated the tracking error signal.

Illustrative example of subject matter classified in this group:

Illustrative example of subject matter classified in this group:

Figure from EP1220210

Illustrative example of subject matter classified in this group:

Figure taken from JP60010424

Uncommon or outdated technology (in 2011).

Further classification information:

The following Indexing Codes are assigned:

G11B 2007/0919 critical angle methods

G11B 2007/0919 dither methods

S11B/09B8F far-field methods

G11B 2007/0924 skewed beams method

Sprung supports - e.g. lens holder support by wires or flat springs

also contains other support systems such as liquid, magnetic, combinations.

Stationary parts: e.g. the magnets on the sled, e.g. the yokes and magnets of a "normal" four-wire-sprung actuator.

Moving parts: lens holder and coils (or, occasionally, magnets) attached to it. Example:

Acting on the tracking actuator.

Acting on focusing or tilt actuator

Brushes incorporated into CD form factor discs for cleaning e.g. EP1411505

"Running optimum power control"

"walking optimum power control".

OPC carried out as a preparation when the medium is loaded or just before the transducing mode is started: G11B 7/1267 Power calibration

Speckle modulation in holographic storage, the following should be assigned as appropriate:

Illustrative example of subject matter classified in this group:

Documents in which the invention information concerns a common optical path

Documents in which the invention information concern the relative arrangement of different optical elements

Anti-reflection films on optical elements where the particular type of element is not important

Further classification information:

There is no specific classification in G11B 7/00 for the manufacture of optical elements per se, therefore the manufacture of the optical elements is classified in the most relevant optical element group itself if this is closely related to the application of the element to optical recording/reproduction. (For mounting, aligning of elements in the head see G11B 7/22).

Where subgroups of G11B 7/135 are available for the means and for the function, both classification(s) for the elements and for the function are assigned.

The borderline between G11B 7/1367 and G11B 7/1353 is not a distinct one, but generally diffraction gratings are regular, repetitive phase steps on a relatively small scale. In borderline cases both are assigned.

Gratings integrated into other elements e.g. lenses are assigned both relevant classes, unless noted otherwise below (e.g. in G11B 7/1367)

Classify also the function if a group exists e.g. diffractive elements used in Foucault (knife edge) method of generating focus error servo signals are also classified in G11B 7/1381

Classify also the function if a specific group exists e.g. beam shaping G11B 7/1398

Classify also the function if a specific group exists e.g. beam shaping: G11B 7/1398

Plates used as beam splitters are classified in both G11B 7/1365 and G11B 7/1395

G11B 7/1365 is not assigned if the plate is merely a support for a diffraction grating with no particularly adapted feature

For example, plates used in apparatus compatible with multiple disc standards to control the aberration at one or more wavelengths

Any plate with a lateral spatially varying effect on the phase of the beam (i.e. in the plane of the plate) e.g. Figure 4 WO 2006/135053

This class is also assigned when the spatial variation is integrated into another element such as an objective lens (since this is essentially equivalent to a plate with the phase structure cooperating with the lens).

The borderline between G11B 7/1367 and G11B 7/1353 is not a distinct one, but generally the phase steps referred to are not regular, repetitive steps as in most diffraction gratings and/or are on a larger scale that a diffraction grating. In borderline cases both are assigned.

Classify also the function if a specific group exists e.g. aberration correction G11B 7/13922.

Classify also the function if a specific group exists e.g. aberration correction G11B 7/13925 or G11B 7/13927

Relative positioning of more than one type of lens (e.g. collimator and objective lens) e.g. for controlling magnification

The SIL of compound objective lenses i.e. where SIL is between the objective lens and the optical data carrier

Further classification information.

Also assign Indexing Code for the specific type of lens (G11B 2007/13722 for Fresnel lenses, G11B 2007/13725 for catadioptric lenses, G11B 2007/13727 for compound lenses)

Lenses not coming within the scope of G11B 7/1374, G11B 7/1376 or G11B 7/1378 should be classified in G11B 7/1372.

Note that after a recent reorganization (Q4/2011) the scope of this group has changed from "other lenses".

Elements that:

Elements for apodisation (e.g. for "super-resolution" i.e. to reduce the beam width of a main lobe of the beam below the diffraction limit for that wavelength) but G11B 7/1387 has precedence (i.e. if a lens for near-field apparatus includes a shielding element it is classified in G11B 7/1387, and not also G11B 7/1381).

Note that after a recent reorganization (Q4/2011) the scope of this group has been broadened (it is no longer has the qualifier "as it falls on the detector")

Waveguide elements (mostly older technology), because they work using a similar principle.

In a hemispherical lens, the rays that come in at large angles (relative to optical axis) from the previous lens are totally internally reflected at the interface due to the refractive index difference BUT there is an evanescent wave which doesn't die to zero immediately. This can be used to read/write on a medium, as long as the medium is very close (e.g. if the hemispherical lens is on a flying head); Recording may also use the evanescent wave from a very fine tip held near a medium.

Warning: This subgroup was created in 2008 and the reclassification of documents published before 2009 has not been systematically done. For earlier documents G11B 7/12, G11B 7/122, G11B 7/123 should be searched.

A sharply elongated optical fibre may act is a local emitter, similar to scanning near field optical microscopy (SNOM)

Solid Immersion Lenses (SIL) are also be assigned Indexing Code G11B 2007/13727

Catadioptric lenses are also assigned Indexing Code G11B 2007/13725

G11B 7/1372 is not assigned if there is no particular adaptation of the (compound) objective lens.

Where a shielding element is involved, this group has precedence over G11B 7/1381

Means to control the angle of the outermost parts of the beam to the optical axis, therefore controlling the size of the spot at the focus.

For apparatus compatible with different standards this often involves some way to block the outer part of the beam for a particular wavelength (see e.g. US6396791 Figure 10(a)(b), paragraph 63, and the prior art shown in Figure 11, paragraph 14) using dichroic effects, diffraction grating or phase difference that affect one wavelength more than another, or polarisation (e.g. by using beams polarised in different directions for different wavelengths), but it may involve elements located elsewhere (e.g. US6160646 Figure 6-9, the asymmetrical grating in the central part of the lens is used for CD medium)

G11B 7/139 is assigned for elements that allow a single lens to be used for different standards. Although switching between objective lenses in apparatus compatible with different standards e.g. CD, DVD, BD, changes the numerical aperture (as well as changing the aberration correction), such documents are not assigned G11B 7/139.

G11B 7/139 has precedence over G11B 7/1392 and subgroups.

Spherical aberration, coma (also referred to as comatic aberration) and chromatic (i.e. varying with wavelength)

In apparatus compatible with different standards:

The element specifically adapted for this purpose should also be classified, e.g. lenses designed to minimize aberrations are classified here (as well as in G11B 7/1372 and subgroups).

G11B 7/13922 is not assigned to lenses or plates adapted to control numerical aperture, since the purpose of this adaptation is to control the aberration (i.e. assigning this class would amount to assigning two classes for the same aspect).

The element specifically adapted for this purpose should also be classified.

G11B 7/13922 is not assigned to lenses or plates adapted to control numerical aperture, since the purpose of this adaptation is to control the aberration (i.e. assigning this class would amount to assigning two classes for the same aspect).

G11B 7/1365 is also assigned for plate beams splitters.

The shape of a contour of equal intensity

Warning: This subgroup was created in the second half of 2009, and the reclassification from G11B 7/0065 has not been systematically done. For documents published before 2010, G11B 7/0065 and G11B 7/0065 should be searched.

Optical recording carriers adapted to be used in near-field or adapted to provide resolution below the diffraction limit e.g. provided with layers that act as masks. For example, "Super-RENS" (super resolution near field structure) media in which a low melting temperature layer such as Sb that acts as a controllable aperture.

Optical recording media such as CDs, DVDs, Blu-Ray discs and Holographic Versatile Discs (HVDs), Optical Cards etc. characterised by the materials.

Annotated CPC G11B 7/241-G11B 7/2595

Joining of disc substrates e.g. for DVDs.

G11B 7/26 or a subclass is assigned when the process involves a single technical art for which provision exists elsewhere but where the adaptation is specific to the optical record carrier.

In this subgroup, special care should be taken to circulate the document to classifiers for the relevant "single technical art" - see the informative references.

This class is assigned for writing the BCA, which occurs during manufacture (not done by end user apparatus).

Scanning probe Microscopy: G01Q

Microstructural devices: B81B

Only the cases wherein the method of recording differs from the method of reproducing. The following recording methods (when associated to a different reproducing method) are covered:

Recording by magnetic means or other means for magnetisation or demagnetisation of a record carrier G11B 11/10 takes precedence over G11B 11/08 recording by electric charge or by variation of electric resistance or capacitance.

This group is limited to the combination of recording and reproducing on the same record carrier by more than one of the different method covered by groups G11B 3/00, G11B 5/00, G11B 7/00 and G11B 9/00

Recording simultaneously or selectively:

Using near-field interactions or transducing means and at least one other method or means for recording or reproducing

Microstructural devices: B81B

The user interface aspects of tape drives are classified also in G11B 25/06.

Analogue recording or reproducing G11B 20/02.

Digital recording or reproducing G11B 20/10.

Transmission of digital information H04L.

Any aspect of control regarding recording and reproducing devices which use carriers moving with respect to the transducer but which are not of filamentary (wire) or web (tape) form. This includes disks and drums, but is predominantly to do with disks.

Any form of control whether externally generated (e.g. user control, external shock) or internally (e.g. a response generated by the sensing of a feature of the record carrier).

Driving, starting and stopping such carriers, including details of control systems used for starting, stopping or altering the speed of motion of the carrier and details of the electromechanical arrangements used in driving, starting, speed-changing and stopping.

G11B 19/2009 and G11B 19/2036 are used to classify spindle motors for disk drives. Electric motors in general are also classified in H02K (Dynamo-electric machines), but only those specifically mentioned as having applications in disk drives are classified in G11B 19/2009 or G11B 19/2036.

G11B 19/2036 is used specifically for the classification of spindle motors characterised by having fluid-dynamic bearings. Such bearings per se are also classified in F16C 17/00, but only those specifically mentioned as having applications in disk drives are classified in G11B 19/2036.

G11B 19/20 is used to classify any other spindle motor arrangements (e.g. for drums).

Control of operating function (G11B 19/02 and subgroups) should not be confused with speed control (G11B 19/20 and subgroups).

The development of battery-powered portable media devices using moving media has led to a number of applications regarding power-saving arrangements and methods. These are considered to have a control aspect, but not of operating function as such. They are generally classified in G11B 19/00.

An exception to this is methods and arrangements for powering down or reducing the speed of the spindle motor in order to save power during idle time, which aspects are classified in G11B 19/2072.

Any other control aspects which do not fall under G11B 19/02 or G11B 19/20 should be classified in G11B 19/00.

Most sub-groups of G11B 19/00 have definitions which are self-explanatory, but exceptions are shown below.

The definition of the G11B 19/04 sub-group according to the IPC is so general that it could cover almost any problem or error experienced while using a recording and reproducing device. It explicitly does NOT cover the following, however:

Data error detection and correction: this is to be found in G11B 20/18 and sub-groups.

Defect management i.e. the detection and management of bad sectors and reallocation of data to good sectors: this is to be found in G11B 27/00.

The sub-groups of G11B 19/04 are self-explanatory and cover the majority of problems often encountered. Other problems not explicitly mentioned are classified in G11B 19/04 itself.

any kind of signal processing which is performed when reading data from or recording data to record carriers. This signal processing specifically includes analogue and digital filtering, equalisation, carrier and symbol synchronization (adjustment of read/write clocks), and the corresponding ways of assessing and improving the quality of the recorded/reproduced signal. Modulation and demodulation techniques (i.e. the actual codes and the stochastical methods for recovering the bit sequences that are reproduced from a record carrier), in the context of recording and reproducing. Techniques of applying error correcting codes in recording / reproducing devices, and likewise how interleaving techniques can be used to mitigate the effects of local burst errors. Techniques for actually detecting media errors (e.g. bad sectors), or data structures and algorithms for coping with these errors, e.g. by relocating data from defective sectors to non-defective spare sectors. The sub-group G11B 20/12 also covers the actual format of the record carriers (in the sense of how different kinds of data are arranged on the medium, e.g. documents which describe dedicated areas for storing specific kinds of user or control data, or documents which relate to the data structure of individual sectors). G11B 20/00086 is a prominent sub-group, which comprises documents about all sorts of copy protection and digital rights management for record carriers. Since recent copy protection initiatives address the copyright protection issue with techniques which apply likewise to all kinds of different storage media, this sub-group nowadays also includes copyright protection for record carriers which do not necessarily involve any physical movement between a head and the medium.