G
SECTION G — PHYSICS
  
INSTRUMENTS
 G11
INFORMATION STORAGE
 G11B
INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER (recording measured values in a way that does not require playback through a transducer G01D; photochemical processing of recordings G03C; recording or playback apparatus capable only of dealing with binary digits G06K; circuits for coupling output of reproducer to radio receiver H04B 1/20; electromechanical transducers and circuits therefor H04R)
 G11B

Note(s)

  1. This sub-class deals with the recording and 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.
  2. This sub-class includes
    1. apparatus and machines for recording or playback, and parts thereof, such as heads;(b) record carriers for use with such apparatus and machines; (c) associated working of other apparatus with such apparatus and machines.
  3. In this sub-class:
    1. The term "head" includes any means for converting sinusoidal or non-sinusoidal electric wave-forms into variations of the physical condition of at least the adjacent surface of the record carrier, or vice versa.
    2. A record carrier is understood to be a body, such as a cylinder, disc, card, tape, or wire, capable of permanently holding information, which can be read-off by a sensing element movable relatively to the recorded information.
 G11B 1/00
Cabinets; Cases; Stands; Disposition of apparatus therein or thereon (furniture aspects A47B, e.g. A47B 81/06)
 G11B 1/02
·  modified to store record carriers
 G11B 1/04
·  combined with other apparatus having a different main function
 G11B 3/00
Recording information by cutting, deforming, or pressing grooves, e.g. by stylus; Record carriers therefor; Reproducing from such record carriers by mechanical sensing of the grooves
 G11B 3/02
·  Arrangements of heads (styli G11B 3/44)
 G11B 3/04
·  ·  Multiple, convertible, or alternative transducing arrangements
 G11B 3/06
·  ·  Determining or indicating position of head
 G11B 3/08
·  ·  Raising, lowering, traversing otherwise than for transducing, arresting, or holding-up heads and record carriers relatively to one another
 G11B 3/10
·  ·  Arranging, supporting, or driving of heads or of transducers relatively to record carriers
 G11B 3/12
·  ·  ·  Supporting in balanced, counterbalanced, or loaded operative position, e.g. loading in direction of traverse
 G11B 3/14
·  ·  ·  ·  by using effects of gravity or inertia, e.g. counterweight
 G11B 3/16
·  ·  ·  ·  ·  adjustable
 G11B 3/18
·  ·  ·  ·  ·  Damping by using viscosity effect
 G11B 3/20
·  ·  ·  ·  by elastic means, e.g. spring
 G11B 3/22
·  ·  ·  ·  ·  adjustable
 G11B 3/24
·  ·  ·  ·  ·  acting to decrease pressure on record
 G11B 3/26
·  ·  ·  ·  ·  acting to increase pressure on record
 G11B 3/28
·  ·  ·  ·  ·  providing transverse bias parallel to record
 G11B 3/30
·  ·  ·  Supporting in an operative position
 G11B 3/32
·  ·  ·  ·  Construction or arrangement of support pillars
 G11B 3/34
·  ·  ·  Driving; Guiding
 G11B 3/36
·  ·  ·  ·  Automatic-feed mechanisms producing progressive transducing traverse across record carriers otherwise than by grooves, e.g. by lead-screw
 G11B 3/38
·  ·  ·  ·  Guiding, e.g. constructions or arrangements providing linear or other special tracking characteristics
 G11B 3/40
·  ·  ·  ·  Driving of heads relatively to stationary record carriers for transducing
 G11B 3/42
·  ·  ·  with provision for adaptation or interchange of heads
 G11B 3/44
·  Styli, e.g. sapphire, diamond
 G11B 3/46
·  ·  Constructions or forms, e.g. attachment of point to shank
 G11B 3/48
·  ·  ·  Needles
 G11B 3/50
·  ·  Anvils or other supports opposing stylus forces
 G11B 3/52
·  ·  Arrangements permitting styli to yield under excessive pressure
 G11B 3/54
·  ·  Storing; Manipulating, e.g. feeding styli to and from heads (needle boxes, receptacles for needles B65D 85/24)
 G11B 3/56
·  ·  Sharpening (by grinding B24B 3/00)
 G11B 3/58
·  Cleaning record carriers or styli, e.g. removing shavings or dust (brushes A46B; cleaning in general B08B)
 G11B 3/60
·  Turntables for record carriers (forming rotor of dynamo-electric motor H02K)
 G11B 3/62
·  ·  Locating record carriers on turntables, e.g. adaptor for enabling centre-pin to receive carriers with large centre hole, e.g. repeatably
 G11B 3/64
·  Re-recording, i.e. transcribing information from one grooved record carrier on to one or more similar or dissimilar record carriers
 G11B 3/66
·  Erasing information, e.g. for reuse of record carrier
 G11B 3/68
·  Record carriers (characterised by direction of groove relative to head G11B 25/00)
 G11B 3/70
·  ·  characterised by the selection of material or structure; Processes or apparatus specially adapted for manufacturing record carriers (processes involving a single technical art and for which provision exists elsewhere, see the relevant class, e.g. B29)
 G11B 3/72
·  ·  Groove formations, e.g. run-in groove, run-out groove
 G11B 3/74
·  ·  ·  Multiple output tracks, e.g. binaural stereophonic
 G11B 3/76
·  ·  ·  forming part of cinematograph films
 G11B 3/78
·  ·  Multiple-track arrangements
 G11B 3/80
·  ·  incorporating subsidiary guide means for heads, other than modulated grooves; Part-formed unmodulated grooves for conversion into transducing grooves
 G11B 3/82
·  ·  Visual features of record carriers
 G11B 3/84
·  ·  ·  Printed matter, e.g. design, label, photograph
 G11B 3/86
·  ·  ·  for indexing; for speed controlling, e.g. stroboscopic markings
 G11B 3/88
·  ·  ·  for display simultaneously with reproduction
 G11B 3/90
·  ·  with means indicating prior or unauthorised use
 G11B 5/00
Recording information by magnetisation of a record carrier; Record carriers therefor; Reproducing therefrom by using magnetic means (by optical means G11B 11/10)
 G11B 5/02
·  Recording, reproducing, and/or erasing methods (G11B 5/12 takes precedence)
 G11B 5/04
·  ·  Frequency-modulation recording
 G11B 5/06
·  ·  Pulse-modulation recording
 G11B 5/08
·  ·  Boundary-displacement recording
 G11B 5/10
·  Housings for heads
 G11B 5/12
·  Structures of inductive heads
 G11B 5/14
·  ·  with cores composed of particles, e.g. with dust core, with ferrite core
 G11B 5/16
·  ·  with cores being composed of metal sheets, i.e. laminated cores
 G11B 5/18
·  ·  ·  with tape-wound cores
 G11B 5/20
·  ·  Construction or disposition of windings
 G11B 5/22
·  ·  Structure of the surface of the head in physical contact with, or immediately adjacent to, the recording medium, i.e. pole pieces
 G11B 5/24
·  ·  ·  having one gap
 G11B 5/26
·  ·  ·  having more than one gap for erasing, recording, and/or reproducing on the same track
 G11B 5/28
·  ·  Structural combination of unitary heads for more than one track
 G11B 5/30
·  Structures of flux-sensitive heads
 G11B 5/32
·  ·  using irradiation or particle bombardment, e.g. reproducing by detecting a reflected electron beam
 G11B 5/34
·  ·  with saturated jig, e.g. for detecting second harmonic, balanced-flux head
 G11B 5/36
·  ·  having vibrating elements
 G11B 5/38
·  ·  using Hall devices
 G11B 5/40
·  Protective measures on heads, e.g. against excessive temperature
 G11B 5/42
·  Apparatus or processes specially adapted for the manufacture of heads, e.g. assembly
 G11B 5/44
·  Circuitry for obtaining a desired electric performance of the head, e.g. with equaliser incorporated in the head (avoiding accidental operation of head G11B 15/04; head switching G11B 15/12)
 G11B 5/46
·  Arrangements for functional testing of heads; Measuring arrangements for heads; Arrangements for demagnetisation of heads (measuring electric or magnetic properties G01R; demagnetisation in general H01F 13/00)
 G11B 5/48
·  Dispositions or mounting of heads relative to record carriers
 G11B 5/50
·  ·  Interchangeable mountings, e.g. for replacement of head without readjustment
 G11B 5/52
·  ·  with simultaneous movement of head and record carrier, e.g. rotation of head
 G11B 5/54
·  ·  with provision for moving the head of its operative position
 G11B 5/56
·  ·  with provision for adjustment of the relative positions of head and record carriers, e.g. manual adjustment
 G11B 5/58
·  ·  Maintaining relative alignment of the heads and record carriers, e.g. to compensate for surface irregularities of the latter
 G11B 5/60
·  ·  ·  Pneumodynamic or hydrodynamic spacing of heads from record carriers
 G11B 5/62
·  Record carriers characterised by the selection of the material
 G11B 5/64
·  ·  comprising only the magnetisable material without bonding agent
 G11B 5/66
·  ·  ·  consisting of several layers
 G11B 5/68
·  ·  comprising one or more layers of magnetisable particles homogeneously mixed with a bonding agent
 G11B 5/70
·  ·  ·  on a base layer
 G11B 5/72
·  ·  Protective coatings, e.g. anti-static, anti-friction
 G11B 5/74
·  Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
 G11B 5/76
·  ·  Drum carriers
 G11B 5/78
·  ·  Tape carriers
 G11B 5/80
·  ·  Card carriers
 G11B 5/82
·  ·  Disc carriers
 G11B 5/84
·  Processes or apparatus specially adapted for manufacturing record carriers (processes involving a single technical art and for which provision exists elsewhere, see the relevant class, e.g. B29)
 G11B 5/86
·  Re-recording, i.e. transcribing information from one magnetisable record carrier on to one or more similar or dissimilar record carriers
 G11B 7/00
Recording information on a record carrier by optical means; Record carriers therefor; Reproducing such recorded information by optical means
 G11B 7/02
·  using electromagnetic radiation other than visible light
 G11B 7/04
·  using fluorescent or phosphorescent record carriers
 G11B 7/06
·  using electrography
 G11B 7/08
·  Disposition or mounting of heads or light sources relatively to record carriers
 G11B 7/10
·  ·  Interchangeable mountings, e.g. for replacement of head without readjustment
 G11B 7/12
·  Heads
 G11B 7/14
·  ·  adapted to record on, or to reproduce from, more than one track simultaneously (G11B 7/20 takes precedence)
 G11B 7/16
·  ·  using filters, e.g. colour filter
 G11B 7/18
·  ·  using optical slits
 G11B 7/20
·  ·  Dual-recording arrangements, i.e. in which the information is recorded in two different forms simultaneously on the same or related tracks, e.g. recording instantaneous and mean values (sound-recording combined with cinematography G03C)
 G11B 7/22
·  ·  Apparatus or processes specially adapted for the manufacture of heads, e.g. assembly
 G11B 7/24
·  Record carriers characterised by the selection of the material or by the structure (for cinematography G03C)
 G11B 7/26
·  ·  Apparatus or processes specially adapted for the manufacture of record carriers (processes involving a single technical art and for which provision exists elsewhere, see the relevant class, e.g. B29, G03)
 G11B 7/28
·  Re-recording, i.e. transcribing information from one record carrier on to one or more similar or dissimilar record carriers using optical sensing and recording means
 G11B 9/00
Recording information otherwise than by cutting grooves, by magnetisation, or by optical means; Record carriers therefor; Reproducing by using means other than styli, magnetic means, or optical means
 G11B 9/02
·  using ferroelectric record carriers; Record carriers therefor
 G11B 9/04
·  using record carriers having variable electric resistance; Record carriers therefor
 G11B 9/06
·  using record carriers having variable electrical capacitance; Record carriers therefor (G11B 9/02 takes precedence)
 G11B 9/08
·  using electrostatic charge injection; Record carriers therefor
 G11B 11/00
Recording and reproducing wherein the reproducing method is covered by a different main group from that of the recording method; Record carriers therefor (recording television signals by thermoplastic deformation of the record carrier H04N 5/02)
 G11B 11/02
·  Recording by flame, jet, flowing fluid, or beam of particles
 G11B 11/04
·  ·  and reproducing by sensing magnetic properties
 G11B 11/06
·  ·  and reproducing by sensing grooves with styli
 G11B 11/08
·  Recording by electric charge or by variation of electric resistance or capacitance, e.g. reproducing by sensing optical properties
 G11B 11/10
·  Recording by magnetic means and reproducing by sensing optical properties
 G11B 11/12
·  Recording by influencing light-sensitive material
 G11B 11/14
·  ·  and reproducing by sensing magnetic properties
 G11B 11/16
·  Recording by styli, pens, or brushes
 G11B 11/18
·  ·  and reproducing by sensing optical properties
 G11B 11/20
·  ·  and reproducing by sensing magnetic properties
 G11B 13/00
Recording simultaneously by methods covered by different main groups; Record carriers therefor; Reproducing simultaneously therefrom
 G11B 13/02
·  magnetically and by styli
 G11B 13/04
·  magnetically and optically
 G11B 13/06
·  optically and by styli
 G11B 15/00
Driving, starting, stopping, or guiding record carriers of filamentary or web form; Control of operating function (driving or moving of heads G11B 21/02)
 G11B 15/02
·  Control of operating function, e.g. switching from recording to reproducing
 G11B 15/04
·  ·  Preventing, inhibiting, or warning against accidental erasing or double recording
 G11B 15/06
·  ·  by sensing auxiliary features on record carriers, e.g. to stop machine near the end of a tape
 G11B 15/08
·  ·  ·  by photoelectric sensing
 G11B 15/10
·  ·  Manually-operated control; Solenoid-operated control
 G11B 15/12
·  ·  Masking of heads; Switching of heads between operative and inoperative functions; Masking of beams, e.g. of light beams
 G11B 15/14
·  ·  ·  Masking or switching periodically
 G11B 15/16
·  ·  by means responsive to presence or absence of record carrier
 G11B 15/18
·  Driving; Starting; Stopping; Arrangements for control or regulation thereof (handling tapes or filamentary material in general B65H)
 G11B 15/20
·  ·  Moving record carrier backwards or forwards by finite amounts, i.e. back-spacing, forward-spacing
 G11B 15/22
·  ·  Brakes; Automatic stopping devices (slowing-down preparatory to stopping or speed-changing G11B 15/48; speed-controlling by mechanical linkage G11B 15/50; brake constructions in general F16D)
 G11B 15/24
·  ·  Drive-disengaging means
 G11B 15/26
·  ·  Driving record carriers by members acting directly or indirectly thereon
 G11B 15/28
·  ·  ·  through rollers driving by frictional contact with the carrier, e.g. capstan; Multiple arrangements of capstans or drums coupled to means for controlling the speed of the drive; Multiple capstan systems alternately engageable with record carrier to provide reversal
 G11B 15/29
·  ·  ·  ·  through pinch-rollers
 G11B 15/30
·  ·  ·  through the means for supporting the record carrier, e.g. mandrel, turntable
 G11B 15/32
·  ·  ·  through the reels or cores on to which the record carrier is wound
 G11B 15/34
·  ·  ·  through non-slip drive means, e.g. sprocket
 G11B 15/38
·  ·  Driving record carriers by pneumatic means
 G11B 15/40
·  ·  Driving record carriers otherwise than by electric motor
 G11B 15/42
·  ·  ·  manually
 G11B 15/43
·  ·  Control or regulation of mechanical tension of record carrier, e.g. tape tension (controlling tension in filamentary material in general B65H 59/00)
 G11B 15/44
·  ·  Speed-changing arrangements; Reversing arrangements; Drive-transfer means therefor
 G11B 15/46
·  ·  Controlling, regulating, or indicating speed
 G11B 15/48
·  ·  ·  Starting; Accelerating; Decelerating; Arrangements preventing malfunction during drive change
 G11B 15/50
·  ·  ·  by mechanical linkage, e.g. clutch
 G11B 15/52
·  ·  ·  by using signals recorded on, or derived from, record carrier
 G11B 15/54
·  ·  ·  by stroboscope; by tachometer (speedometers or tachometers G01P)
 G11B 15/56
·  using reserve loops, e.g. to minimise inertia during acceleration
 G11B 15/58
·  ·  with vacuum column
 G11B 15/60
·  Guiding record carrier
 G11B 15/62
·  ·  Maintaining desired spacing between record carrier and head
 G11B 15/64
·  ·  ·  by pneumodynamic or hydrodynamic spacing
 G11B 15/66
·  ·  Threading; Loading; Automatic self-loading; Spools (reels in general B65H 75/02)
 G11B 17/00
Automatic mechanisms for starting, driving, or stopping disc-type record carriers on turntables, for raising or lowering, positioning or traversing, arresting or holding-up transducers or record carriers relatively to each other, and for automatically transferring record carriers to and from transducing position
 G11B 17/02
·  Details
 G11B 17/04
·  ·  Feeding or guiding single records to or from playing unit
 G11B 17/06
·  ·  Automatic movement of tone-arm into, or out of, place for playing records, e.g. manually placed on playing unit
 G11B 17/08
·  from consecutive-access magazine of disc records
 G11B 17/10
·  ·  with horizontal transfer to the turntable from a stack arranged with a vertical axis
 G11B 17/12
·  ·  with axial transfer to the turntable from a stack with a vertical axis
 G11B 17/14
·  ·  ·  by mechanism in rotating centre post, e.g. permitting the playing of both sides of a record
 G11B 17/16
·  ·  ·  by mechanism in stationary centre post, e.g. with stepped post, using fingers on post
 G11B 17/18
·  ·  ·  by mechanism operating on the edge of the disc record
 G11B 17/20
·  ·  with transfer away from stack on turntable after playing
 G11B 17/22
·  from random-access magazine of disc records
 G11B 17/24 - 
G11B 17/28

Note(s)

Group G11B 17/30 takes precedence over groups G11B 17/24-G11B 17/28.

 G11B 17/24
·  ·  the magazine having a toroidal or part-toroidal shape
 G11B 17/26
·  ·  the magazine having a cylindrical shape with vertical axis
 G11B 17/28
·  ·  the magazine having a cylindrical shape with horizontal axis
 G11B 17/30
·  ·  wherein the playing unit is moved accordingly to the location of the selected record
 G11B 19/00
Driving, starting, stopping, or guiding of record carriers not specifically of filamentary or web form, or of supports therefor; Control thereof (G11B 17/00 takes precedence)
 G11B 19/02
·  Control of drive; Control of operating function, e.g. switching from recording to reproducing
 G11B 19/04
·  ·  Arrangements for preventing, inhibiting, or warning against, double recording on the same blank, or against other recording or reproducing malfunctions
 G11B 19/06
·  ·  by counting or timing of machine operations
 G11B 19/08
·  ·  by using devices external to the driving mechanisms, e.g. coin-freed switch
 G11B 19/10
·  ·  by sensing presence or absence of record in accessible stored position or on turntable
 G11B 19/12
·  ·  by sensing distinguishing features of records, e.g. diameter
 G11B 19/14
·  ·  by sensing movement or position of head, e.g. means moving in correspondence with head movements
 G11B 19/16
·  ·  Manual control
 G11B 19/18
·  ·  ·  Manual action on one element producing control effect indirectly by consequent action of driving mechanism
 G11B 19/20
·  Driving; Starting; Stopping
 G11B 19/22
·  ·  Brakes other than speed-regulating brakes (brake constructions in general F16D)
 G11B 19/24
·  ·  Arrangements for providing constant relative speed between record carrier and head
 G11B 19/26
·  ·  Speed-changing arrangements; Reversing arrangements
 G11B 19/28
·  ·  Speed controlling, regulating, or indicating (G11B 19/24 takes precedence; speedometers or tachometers G01P)
 G11B 21/00
Head arrangements irrespective of the method of recording or reproducing
 G11B 21/02
·  Driving or moving of heads
 G11B 21/04
·  ·  Automatic feed mechanism producing progressive transducing traverse across the record carrier
 G11B 21/06
·  ·  ·  the record carrier having means to ensure traverse movement of the head
 G11B 21/08
·  ·  Track changing or selecting (G11B 21/12 takes precedence)
 G11B 21/10
·  ·  Track finding or aligning by moving the head
 G11B 21/12
·  ·  Raising and lowering; Back-spacing or forward-spacing along track; Returning to starting position
 G11B 21/14
·  ·  ·  manually
 G11B 21/16
·  Supporting the heads; Supporting the sockets for plug-in heads
 G11B 21/18
·  ·  while the head is moving
 G11B 21/20
·  ·  while the head is in operative position but stationary or permitting minor movements to follow irregularities in surface of record carrier
 G11B 21/22
·  ·  while the head is out of operative position
 G11B 21/24
·  ·  Head support adjustments
 G11B 21/26
·  ·  Means for interchange or replacement of head or head element
 G11B 23/00
Record carriers irrespective of the method of recording; Accessories therefor, e.g. container
 G11B 23/02
·  Containers; Storing means (for tape or filamentary material in general B65H 75/00)
 G11B 23/04
·  ·  Magazines; Cassettes (G11B 23/12 takes precedence)
 G11B 23/06
·  ·  ·  for housing endless webs or filaments
 G11B 23/08
·  ·  ·  for housing end-to-end webs or filaments
 G11B 23/10
·  ·  ·  ·  on single reels or winding cores
 G11B 23/12
·  ·  Bins for random storage of webs or filaments
 G11B 23/14
·  Providing ability to repeat location, e.g. using sprocket holes
 G11B 23/16
·  Record carriers with single track for recording at spaced intervals along the track thereof, e.g. for speech or language training
 G11B 23/18
·  Record carriers with multiple tracks, e.g. with complementary and partial tracks such as paired "stereo" tracks
 G11B 23/20
·  with provision for splicing to provide permanent or temporary connections
 G11B 23/22
·  ·  of endless belts; of tapes forming Möbius loops
 G11B 23/24
·  ·  of tapes having multiple tracks parallel to edge of record carrier by offset splicing to form endless loop with one or more helical tracks
 G11B 23/26
·  ·  of leaders for loading or threading, e.g. to form a temporary connection
 G11B 23/28
·  indicating prior or unauthorised use
 G11B 23/30
·  with provision for auxiliary signals (sensing such signals G11B 15/06)
 G11B 23/32
·  ·  Electrical or mechanical contacting means; Tape stop foils
 G11B 23/34
·  ·  Signal means additional to the main recording track, e.g. photoelectric sensing of sprocket holes for timing
 G11B 23/36
·  ·  Signals on record carriers or on containers and recorded by the same method as the main recording
 G11B 23/38
·  Visual features other than those contained in record tracks or represented by sprocket holes
 G11B 23/40
·  ·  Identifying or analogous means applied to, or incorporated in, the record carrier and not intended for visual display simultaneously with the playing-back of the record carrier, e.g. label, leader, photograph
 G11B 23/42
·  ·  Marks for indexing, speed-controlling, synchronising, or timing
 G11B 23/44
·  ·  Information for display simultaneously with playback of the record, e.g. photographic matter
 G11B 23/46
·  ·  ·  Cinematograph films with integral tracks, e.g. with sound track
 G11B 23/48
·  ·  ·  Diascopic slides with integral sound or other tracks on, or adjacent to, the picture area or on the mounting means
 G11B 25/00
Apparatus characterised by the shape of record carrier employed but irrespective of the method of recording (individual parts of apparatus G11B 1/00-G11B 23/00)
 G11B 25/02
·  using cylindrical record carriers
 G11B 25/04
·  using flat record carriers, e.g. disc, card
 G11B 25/06
·  using web-form record carriers, e.g. tape
 G11B 25/08
·  using filamentary record carriers, e.g. wire
 G11B 25/10
·  Apparatus capable of using record carriers defined in more than one of the groups G11B 25/02-G11B 25/08
 G11B 27/00
Editing; Indexing; Monitoring
 G11B 27/02
·  Editing, e.g. varying the order of signals reproduced from record carrier
 G11B 27/04
·  ·  using differential drive of record carrier and head
 G11B 27/06
·  ·  Cutting and rejoining; Notching, or perforating record carriers otherwise than by recording styli (record carriers with provision for splicing G11B 23/20)
 G11B 27/08
·  ·  Re-recording only part of the information
 G11B 27/10
·  Indexing; Timing (marks or signals on record carriers G11B 23/30, G11B 23/42)
 G11B 27/12
·  ·  linearly related to time or travel
 G11B 27/14
·  ·  ·  Measuring or indicating elapsed time or travel
 G11B 27/16
·  ·  ·  Indicating time or travel remaining available; Warning of imminent termination
 G11B 27/18
·  ·  non-linearly related to time or travel
 G11B 27/20
·  ·  ·  using counters
 G11B 27/22
·  ·  Means responsive to presence or absence of recorded signals
 G11B 27/24
·  ·  by sensing features on the record carrier other than the transducing track (for controlling purposes G11B 15/00, G11B 17/00)
 G11B 27/26
·  ·  ·  by photoelectric detection, e.g. of sprocket holes
 G11B 27/28
·  ·  by using signals recorded by the same method as the main recording
 G11B 27/30
·  ·  ·  on the same track as the main recording
 G11B 27/32
·  ·  ·  on separate auxiliary tracks of the same or an auxiliary record carrier
 G11B 27/34
·  ·  Indicating arrangements (indicating measured values in general G01D)
 G11B 27/36
·  Monitoring, i.e. supervising the progress of recording or reproducing
 G11B 31/00
Arrangements for the associated working of recording or reproducing apparatus with related apparatus (with cameras or projectors G03B 31/00)
 G11B 31/02
·  with automatic musical instruments