Classifications

• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/84—Processes or apparatus specially adapted for manufacturing record carriers
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B20/00—Signal processing not specific to the method of recording or reproducing; Circuits therefor
  • G11B20/10—Digital recording or reproducing
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B21/00—Head arrangements not specific to the method of recording or reproducing
  • G11B21/02—Driving or moving of heads
  • G11B21/10—Track finding or aligning by moving the head ; Provisions for maintaining alignment of the head relative to the track during transducing operation, i.e. track following
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B23/00—Record carriers not specific to the method of recording or reproducing; Accessories, e.g. containers, specially adapted for co-operation with the recording or reproducing apparatus ; Intermediate mediums; Apparatus or processes specially adapted for their manufacture
  • G11B23/02—Containers; Storing means both adapted to cooperate with the recording or reproducing means
  • G11B23/04—Magazines; Cassettes for webs or filaments
  • G11B23/08—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends
  • G11B23/107—Magazines; Cassettes for webs or filaments for housing webs or filaments having two distinct ends using one reel or core, one end of the record carrier coming out of the magazine or cassette
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B27/00—Editing; Indexing; Addressing; Timing or synchronising; Monitoring; Measuring tape travel
  • G11B27/36—Monitoring, i.e. supervising the progress of recording or reproducing
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/008—Recording on, or reproducing or erasing from, magnetic tapes, sheets, e.g. cards, or wires
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/02—Recording, reproducing, or erasing methods; Read, write or erase circuits therefor
  • G11B5/09—Digital recording
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
  • G11B5/584—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/48—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed
  • G11B5/58—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following
  • G11B5/584—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes
  • G11B5/588—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes by controlling the position of the rotating heads
  • G11B5/592—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes by controlling the position of the rotating heads using bimorph elements supporting the heads
  • G11B5/5921—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes by controlling the position of the rotating heads using bimorph elements supporting the heads using auxiliary signals, e.g. pilot signals
  • G11B5/5926—Disposition or mounting of heads or head supports relative to record carriers ; arrangements of heads, e.g. for scanning the record carrier to increase the relative speed with provision for moving the head for the purpose of maintaining alignment of the head relative to the record carrier during transducing operation, e.g. to compensate for surface irregularities of the latter or for track following for track following on tapes by controlling the position of the rotating heads using bimorph elements supporting the heads using auxiliary signals, e.g. pilot signals recorded in separate tracks, e.g. servo tracks
  • G11B5/5928—Longitudinal tracks
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/62—Record carriers characterised by the selection of the material
  • G11B5/68—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent
  • G11B5/70—Record carriers characterised by the selection of the material comprising one or more layers of magnetisable material homogeneously mixed with a bonding agent on a base layer
• • G—PHYSICS
  • G11—INFORMATION STORAGE
  • G11B—INFORMATION STORAGE BASED ON RELATIVE MOVEMENT BETWEEN RECORD CARRIER AND TRANSDUCER
  • G11B5/00—Recording by magnetisation or demagnetisation of a record carrier; Reproducing by magnetic means; Record carriers therefor
  • G11B5/74—Record carriers characterised by the form, e.g. sheet shaped to wrap around a drum
  • G11B5/78—Tape carriers

Definitions

• the technology disclosed herein relates to magnetic tapes, magnetic tape cartridges, magnetic tape systems, inspection methods, and methods for manufacturing magnetic tapes.
• JP 2022-057517 A discloses a magnetic tape having a timing-based servo pattern, which is used in a magnetic tape device with a total number of data tracks of 8705 or more when converted into a 1/2-inch-wide magnetic tape, and in which the ⁇ PNL of the timing-based servo pattern is 10.0% or less of the track pitch, and the ⁇ PNL indicates the amount of deviation from the linearity of the timing-based servo pattern.
• JP 2019-046521 A discloses a recording device equipped with a recording unit that records information about the linearity of a servo signal recorded on a magnetic tape contained in a recording tape cartridge onto a recording medium contained in the recording tape cartridge.
• U.S. Patent Application Publication No. 2019/0279673 discloses a shingled recording method as a method for recording data onto magnetic tape.
• One embodiment of the technology disclosed herein provides a magnetic tape, a magnetic tape cartridge, a magnetic tape system, an inspection method, and a method for manufacturing a magnetic tape that can contribute to improving the accuracy of recording data on a magnetic tape and the accuracy of reproducing data recorded on the magnetic tape.
• the first aspect of the disclosed technology is a magnetic tape in which a plurality of servo bands, each having a plurality of servo patterns recorded along the longitudinal direction, are arranged in the width direction, and an index indicating the nonlinearity of the servo patterns is within 15% of the track pitch
• the track pitch is the pitch between a plurality of tracks formed by recording data on the magnetic tape by a recording element according to a signal obtained from the plurality of servo patterns
• the index indicates the degree to which the plurality of PES difference gaps vary from the average value of the plurality of PES difference gaps
• the PES difference gap is the difference between a first PES difference, which is the difference in PES between a pair of first positions corresponding in the width direction in a pair of servo patterns recorded at corresponding positions in the width direction between a pair of servo bands adjacent in the width direction among the plurality of servo bands
• a second PES difference which is the difference in PES between a pair of second positions in the pair of servo
• the second aspect of the technology disclosed herein is the magnetic tape of the first aspect, in which a plurality of tracks are formed by recording data on the magnetic tape using a recording element in the SMR method.
• a third aspect of the technology disclosed herein is a magnetic tape according to the first or second aspect, in which the index is a value equivalent to three times the standard deviation of the multiple PES difference gaps.
• the fourth aspect of the technology disclosed herein is a magnetic tape according to any one of the first to third aspects, in which the first predetermined interval is a reference interval that is a natural number multiple of the second predetermined interval and is the interval that most closely resembles the reference interval that is equivalent to half the difference between the recording element length, which is the length of the recording element in the width direction, and the track pitch.
• the first predetermined interval is a reference interval that is a natural number multiple of the second predetermined interval and is the interval that most closely resembles the reference interval that is equivalent to half the difference between the recording element length, which is the length of the recording element in the width direction, and the track pitch.
• the fifth aspect of the technology disclosed herein is a magnetic tape according to any one of the first to third aspects, in which the first predetermined interval is an interval that is a natural number multiple of the second predetermined interval that is equal to or greater than two.
• a sixth aspect of the technology disclosed herein is a magnetic tape according to any one of the first to sixth aspects, in which the first predetermined interval is greater than the track pitch.
• the seventh aspect of the technology disclosed herein is a magnetic tape according to any one of the first to sixth aspects, in which the index is within 10% of the track pitch.
• the eighth aspect of the technology disclosed herein is a magnetic tape according to any one of the first to seventh aspects, in which the index is within 5% of the track pitch.
• the ninth aspect of the technology disclosed herein is a magnetic tape according to any one of the first to eighth aspects, in which the magnetic tape has three or more servo bands arranged in the width direction as the multiple servo bands, and an index is obtained for each of all pairs of servo bands adjacent in the width direction.
• a tenth aspect of the technology disclosed herein is a magnetic tape according to the ninth aspect, in which the indices obtained for each of a pair of servo bands are within 15% of the track pitch.
• An eleventh aspect of the technology disclosed herein is a magnetic tape according to the ninth aspect, in which the indices obtained for each of a pair of servo bands are within 10% of the track pitch.
• a twelfth aspect of the technology disclosed herein is a magnetic tape according to the ninth aspect, in which the indices obtained for each of a pair of servo bands are within 5% of the track pitch.
• a thirteenth aspect of the technology disclosed herein is a magnetic tape according to any one of the first to twelfth aspects, in which the servo pattern is at least one pair of linear magnetization regions, the pair of linear magnetization regions being a linearly magnetized first linear magnetization region and a linearly magnetized second linear magnetization region, the first linear magnetization region and the second linear magnetization region being inclined in opposite directions with respect to a virtual line along the width direction, and the first linear magnetization region having a steeper inclination angle with respect to the virtual line than the second linear magnetization region.
• a fourteenth aspect of the technology disclosed herein is a magnetic tape cartridge comprising a magnetic tape according to any one of the first to thirteenth aspects and a case in which the magnetic tape is housed.
• a fifteenth aspect of the technology disclosed herein is a magnetic tape system comprising a magnetic tape according to any one of the first to thirteenth aspects and a magnetic head for recording data on the magnetic tape and/or reproducing data recorded on the magnetic tape.
• a sixteenth aspect of the technology disclosed herein is an inspection method that includes obtaining an index from a magnetic tape according to any one of the first to thirteenth aspects, and inspecting the magnetic tape using the index.
• a seventeenth aspect of the technology disclosed herein is an inspection method according to the sixteenth aspect, in which inspecting the magnetic tape includes inspecting the linearity of the servo pattern using an index.
• An 18th aspect of the technology disclosed herein is a manufacturing method for a magnetic tape in which a plurality of servo bands, each having a plurality of servo patterns recorded along a first longitudinal direction, are arranged in the width direction, the method including: setting a servo write head having a facing surface that faces the recording surface of the magnetic tape when recording a plurality of servo patterns along the first longitudinal direction, and a plurality of gap patterns formed at intervals along a second longitudinal direction of the facing surface, the plurality of gap patterns corresponding to the plurality of servo patterns, in an orientation in which the recording surface and the plurality of gap patterns face each other; and forming a plurality of servo bands on the recording surface by recording a plurality of servo patterns on the recording surface along the first longitudinal direction using the servo write head set in the above orientation, the index indicating the nonlinearity of the servo pattern being within 15% of the track pitch, the track pitch being within a range of 15% to 20%.
• a method for manufacturing a magnetic tape being a pitch between multiple tracks formed by recording data on the magnetic tape by a recording element according to a signal obtained from a servo pattern, the index indicating the degree to which the multiple PES difference gaps vary from the average value of the multiple PES difference gaps, the PES difference gap being the difference between a first PES difference, which is the difference in PES between a pair of first positions corresponding in the width direction in a pair of servo patterns recorded at corresponding positions in the width direction between a pair of servo bands adjacent in the width direction among the multiple servo bands, and a second PES difference, which is the difference in PES between a pair of second positions in the pair of servo patterns shifted in the width direction from the pair of first positions by a first preset interval, the multiple PES difference gaps being obtained by measuring the PES difference gaps in the pair of servo patterns at second preset intervals along the width direction, the first preset interval being greater than the second preset interval.
• FIG. 1 is a conceptual diagram showing an example of a configuration of a magnetic tape system.
• 1 is a schematic perspective view showing an example of the appearance of a magnetic tape cartridge.
• FIG. 1 is a schematic diagram illustrating an example of a hardware configuration of a magnetic tape drive.
• 1 is a schematic perspective view showing an example of a magnetic field emitted by a non-contact read/write device from the bottom side of a magnetic tape cartridge.
• FIG. 1 is a conceptual diagram showing an example of the correlation between a processing device, a moving mechanism, and a magnetic head.
• 1 is a conceptual diagram showing an example of a state in which a magnetic head is positioned above a magnetic tape, as observed from the surface side of the magnetic tape.
• FIG. 1 is a conceptual diagram showing an example of a configuration of a magnetic tape system.
• 1 is a schematic perspective view showing an example of the appearance of a magnetic tape cartridge.
• FIG. 1 is a schematic diagram illustrating an example of a hardware configuration of a magnetic
• FIG. 2 is a conceptual diagram showing an example of the configuration of a data band formed on the surface of a magnetic tape.
• 3 is a conceptual diagram showing an example of a corresponding relationship between a data recording/reproducing element and a data track.
• FIG. 4 is a conceptual diagram showing an example of how a servo pattern is read by a servo read element.
• FIG. 11 is a conceptual diagram showing an example of a form of a data track formed by recording data on the surface of a magnetic tape by the SMR method, whereby a plurality of divided data tracks are shifted and overlapped along a second direction.
• FIG. 1 is a conceptual diagram showing an example of a first recording module, a reproducing module, and a second recording module provided in a magnetic head;
• FIG. 1 is a conceptual diagram showing an example of a first recording module, a reproducing module, and a second recording module provided in a magnetic head;
• FIG. 2 is a conceptual diagram showing an example of the configuration of a servo writer.
• 2 is a conceptual diagram showing an example of the configuration of a servo pattern recording head and a pulse signal generator included in a servo writer.
• 10 is a flowchart showing an example of the flow of a linearity inspection method used in an inspection step included in a manufacturing method of a magnetic tape.
• 1 is a conceptual diagram showing an example of a configuration of a servo band formed on a magnetic tape.
• FIG. 13 is a conceptual diagram showing an example of a manner in which a plurality of ⁇ dPESs are measured from adjacent servo pattern pairs.
• FIG. 13 is a conceptual diagram showing an example of a linearity determination condition.
• 1 is a graph showing an example of a distribution of a plurality of ⁇ dPESs obtained under the first condition shown in Table 1.
• 13 is a graph showing an example of a distribution of a plurality of ⁇ dPESs obtained under the second condition shown in Table 2.
• 1 is a conceptual diagram showing an example of an embodiment of a first recording module in which a first servo read element reads a servo pattern through a path on the extreme end side of the width of a magnetic tape among a plurality of paths used when recording data.
• FIG. FIG. 13 is a conceptual diagram showing an example of a case where one divided data track is formed by each of a plurality of first data recording elements of a first recording module.
• FIG. 11 is a conceptual diagram showing an example of a form of a data track formed by overlapping a plurality of divided data tracks with a shift in a second direction by each of a plurality of first data recording elements of a first recording module.
• This is a conceptual diagram showing an example of an embodiment of a reproduction module when a data reproduction element reproduces data from a divided data track that is located at the very end of the width of the magnetic tape among multiple divided data tracks that form one data track.
• FIG. 1 is a conceptual diagram showing an example of a data track formed by overlapping a plurality of divided data tracks, each of which is shifted in a first direction, by a plurality of data recording elements of a recording module;
• FIG. 11 is a conceptual diagram showing a modified example of the configuration of the magnetic head.
• FIG. 13 is a conceptual diagram showing a modified example of the configuration of the servo pattern.
• 1 is a conceptual diagram showing an example of a relationship between the geometric characteristics of an actual servo pattern and the geometric characteristics of a virtual servo pattern;
• CPU is an abbreviation for "Central Processing Unit”.
• RAM is an abbreviation for "Random Access Memory”.
• NVM is an abbreviation for "Non-Volatile Memory”.
• EEPROM is an abbreviation for "Electrically Erasable and Programmable Read Only Memory”.
• SSD is an abbreviation for "Solid State Drive”.
• HDD is an abbreviation for "Hard Disk Drive”.
• ASIC is an abbreviation for "Application Specific Integrated Circuit”.
• PLD is an abbreviation for "Programmable Logic Device”.
• FPGA is an abbreviation for "Field-Programmable Gate Array”.
• SoC is an abbreviation for "System-on-a-Chip”.
• IC is an abbreviation for "Integrated Circuit.”
• RFID is an abbreviation for "Radio Frequency Identifier.”
• UI is an abbreviation for "User Interface.”
• SMR is an abbreviation for "Shingled Magnetic Recording.”
• TDS is an abbreviation for "Transverse Dimensional Stability.”
• FIB is an abbreviation for "Focused Ion Beam.”
• PES is an abbreviation for "Position Error Signal.”
• MEMS is an abbreviation for "Micro Electro Mechanical Systems.”
• PVD is an abbreviation for "Physical Vapor Deposition.”
• CVD is an abbreviation for "Chemical Vapor Deposition.”
• a magnetic tape system 10 includes a magnetic tape cartridge 12 and a magnetic tape drive 14.
• the magnetic tape cartridge 12 is loaded into the magnetic tape drive 14.
• the magnetic tape cartridge 12 contains a magnetic tape MT.
• the magnetic tape drive 14 pulls out the magnetic tape MT from the loaded magnetic tape cartridge 12, and while running the pulled out magnetic tape MT, records data on the magnetic tape MT and reads data from the magnetic tape MT.
• the magnetic tape cartridge 12 and the magnetic tape drive 14 are each shown individually to facilitate understanding of the technology disclosed herein, but in reality, the magnetic tape system 10 includes a plurality of magnetic tape cartridges 12 and a plurality of magnetic tape drives 14.
• the plurality of magnetic tape cartridges 12 and the plurality of magnetic tape drives 14 are selectively used. For example, a magnetic tape cartridge 12 is selected from the plurality of magnetic tape cartridges 12 in accordance with a given instruction, and the selected magnetic tape cartridge 12 is loaded into a specified magnetic tape drive 14 out of the plurality of magnetic tape drives 14.
• the magnetic tape system 10 is an example of a "magnetic tape system” according to the technology disclosed herein.
• the magnetic tape MT is an example of a “magnetic tape” according to the technology disclosed herein.
• the magnetic tape cartridge 12 is an example of a “magnetic tape cartridge” according to the technology disclosed herein.
• the left direction opposite the direction of arrow B in Figures 2 to 4 is referred to as the left direction
• the left side of the magnetic tape cartridge 12 is referred to as the left side of the magnetic tape cartridge 12.
• “left” refers to the left side of the magnetic tape cartridge 12.
• the magnetic tape cartridge 12 is generally rectangular in plan view and has a box-shaped case 16.
• the case 16 contains the magnetic tape MT.
• the case 16 is an example of a "case” according to the technology disclosed herein.
• a supply reel 22 is rotatably housed inside the case 16.
• the magnetic tape MT is wound around the supply reel 22.
• An opening 16A1 is formed in the front side of the right wall 16A of the case 16. The magnetic tape MT is pulled out from the opening 16A1.
• the case 16 contains a cartridge memory 24 as a storage medium other than the magnetic tape MT.
• the cartridge memory 24 is equipped with an IC chip having an NVM.
• a so-called passive RFID tag is used as the cartridge memory 24, and various information is read and written to the cartridge memory 24 (i.e., various information is stored and acquired) in a non-contact manner.
• the cartridge memory 24 stores management information 15 that manages the magnetic tape cartridge 12.
• the management information 15 includes, for example, information about the cartridge memory 24, information about the magnetic tape MT, information about the magnetic tape system 10, and information about the magnetic tape drive 14.
• the magnetic tape drive 14 includes a controller 25, a transport device 26, a magnetic head 28, and a UI device 29.
• the controller 25 includes a processing device 30 and storage 32.
• the magnetic head 28 is an example of a "magnetic head" according to the technology disclosed herein.
• the magnetic tape cartridge 12 is loaded into the magnetic tape drive 14 in the direction of arrow A.
• the magnetic tape MT is pulled out from the magnetic tape cartridge 12 and used.
• the magnetic tape drive 14 controls the magnetic tape cartridge 12 and each part within the magnetic tape drive 14 using management information 15 stored in the cartridge memory 24, etc.
• the magnetic tape drive 14 performs magnetic processing on the surface 31 of the magnetic tape MT using the magnetic head 28 while the magnetic tape MT is running.
• the surface 31 is a recording surface on which data is recorded.
• the magnetic processing refers to a recording process in which the magnetic head 28 records data on the surface 31, which is the surface of the magnetic tape MT that has a magnetic layer, and a reproducing process in which the magnetic head 28 reproduces data from the surface 31 of the magnetic tape MT (i.e., a process of reading data).
• the magnetic tape drive 14 selectively performs a recording process and a reproducing process using the magnetic head 28.
• the magnetic tape drive 14 pulls out the magnetic tape MT from the magnetic tape cartridge 12, and uses the magnetic head 28 to record data on the surface 31 of the pulled out magnetic tape MT, or uses the magnetic head 28 to reproduce data from the surface 31 of the pulled out magnetic tape MT.
• the surface 31 is an example of a "recording surface” according to the technology disclosed herein.
• the processing device 30 controls the entire magnetic tape drive 14.
• the processing device 30 is realized by an ASIC, but the technology of the present disclosure is not limited to this.
• the processing device 30 may be realized by an FPGA and/or a PLD.
• the processing device 30 may also be realized by a computer including a CPU, flash memory (e.g., EEPROM and/or SSD, etc.), and RAM.
• the processing device 30 may also be realized by combining two or more of the ASIC, FPGA, PLD, and computer. In other words, the processing device 30 may be realized by a combination of a hardware configuration and a software configuration.
• the storage 32 is connected to the processing device 30, and the processing device 30 writes various information to the storage 32 and reads various information from the storage 32.
• An example of the storage 32 is a flash memory and/or a HDD.
• the flash memory and the HDD are merely examples, and any non-volatile memory that can be mounted in the magnetic tape drive 14 may be used.
• the UI-based device 29 is a device having a reception function that receives an instruction signal indicating an instruction from a user, and a presentation function that presents information to the user.
• the reception function is realized, for example, by a touch panel, hard keys (e.g., a keyboard), and/or a mouse.
• the presentation function is realized, for example, by a display, printer, and/or a speaker.
• the UI-based device 29 is connected to the processing device 30.
• the processing device 30 acquires the instruction signal received by the UI-based device 29.
• the UI-based device 29 presents various information to the user under the control of the processing device 30.
• the transport device 26 is a device that selectively transports the magnetic tape MT in the forward and reverse directions along a predetermined path, and is equipped with a feed motor 36, a take-up reel 38, a take-up motor 40, and multiple guide rollers GR. Note that here, the forward direction refers to the feed direction of the magnetic tape MT, and the reverse direction refers to the rewind direction of the magnetic tape MT.
• the feed motor 36 rotates the feed reel 22 in the magnetic tape cartridge 12 under the control of the processing device 30.
• the processing device 30 controls the feed motor 36 to control the rotation direction, rotation speed, rotation torque, etc. of the feed reel 22.
• the processing device 30 rotates the pay-out motor 36 and the take-up motor 40 so that the magnetic tape MT runs in the forward direction along a predetermined path.
• the rotational speed and rotational torque of the pay-out motor 36 and the take-up motor 40 are adjusted according to the speed at which the magnetic tape MT is wound around the take-up reel 38.
• tension is applied to the magnetic tape MT by adjusting the rotational speed and rotational torque of each of the pay-out motor 36 and the take-up motor 40 by the processing device 30.
• the tension applied to the magnetic tape MT is controlled by adjusting the rotational speed and rotational torque of each of the pay-out motor 36 and the take-up motor 40 by the processing device 30.
• the processing device 30 When rewinding the magnetic tape MT onto the supply reel 22, the processing device 30 rotates the supply motor 36 and the take-up motor 40 so that the magnetic tape MT runs in the reverse direction along the predetermined path.
• Each of the multiple guide rollers GR is a roller that guides the magnetic tape MT.
• the default path i.e., the running path of the magnetic tape MT, is determined by disposing the multiple guide rollers GR at separate positions across the magnetic head 28 between the magnetic tape cartridge 12 and the take-up reel 38.
• the magnetic head 28 includes a magnetic element unit 42 and a holder 44.
• the magnetic element unit 42 is held by the holder 44 so as to be in contact with the running magnetic tape MT.
• the magnetic element unit 42 has multiple magnetic elements.
• the magnetic element unit 42 records data on the magnetic tape MT transported by the transport device 26, and reproduces data from the magnetic tape MT transported by the transport device 26.
• data refers to, for example, the servo pattern 52 (see FIG. 6) and data other than the servo pattern 52 (i.e., data recorded in the data band DB (see FIG. 6)).
• the magnetic tape drive 14 is equipped with a non-contact read/write device 46.
• the non-contact read/write device 46 is disposed below the magnetic tape cartridge 12 when the magnetic tape cartridge 12 is loaded so as to directly face the rear surface of the cartridge memory 24, and reads and writes information from and to the cartridge memory 24 in a non-contact manner.
• the non-contact read/write device 46 emits a magnetic field MF from the bottom side of the magnetic tape cartridge 12 toward the cartridge memory 24.
• the magnetic field MF penetrates the cartridge memory 24.
• the non-contact read/write device 46 is connected to the processing device 30.
• the processing device 30 outputs a control signal to the non-contact read/write device 46.
• the control signal is a signal that controls the cartridge memory 24.
• the non-contact read/write device 46 generates a magnetic field MF according to the control signal input from the processing device 30, and emits the generated magnetic field MF toward the cartridge memory 24.
• the non-contact read/write device 46 performs a process on the cartridge memory 24 according to a control signal by performing non-contact communication with the cartridge memory 24 via the magnetic field MF.
• the non-contact read/write device 46 selectively performs a process of reading information from the cartridge memory 24 and a process of storing information in the cartridge memory 24 (i.e., a process of writing information to the cartridge memory 24).
• the processing device 30 reads information from the cartridge memory 24 and stores information in the cartridge memory 24 by communicating non-contact with the cartridge memory 24 via the non-contact read/write device 46.
• the processing device 30 is connected to the magnetic head 28 and controls processing (e.g., the magnetic processing described above) using the magnetic field MF (see FIG. 4) generated by the magnetic head 28.
• the magnetic tape drive 14 is equipped with a moving mechanism 48.
• the processing device 30 is connected to the magnetic head 28 via the moving mechanism 48.
• the processing device 30 controls the movement of the magnetic head 28 (e.g., movement in the width direction WD (see FIG. 6) of the magnetic tape MT) via the moving mechanism 48.
• the movement mechanism 48 has a movement actuator 48A.
• Examples of the movement actuator 48A include a voice coil motor and/or a piezoelectric actuator.
• the movement actuator 48A is connected to the processing device 30, which controls the movement actuator 48A.
• the movement actuator 48A generates power under the control of the processing device 30.
• the movement mechanism 48 receives the power generated by the movement actuator 48A to move the magnetic head 28 in the width direction WD of the magnetic tape MT (see FIG. 6).
• servo bands SB1, SB2, and SB3 and data bands DB1 and DB2 are formed on the surface 31 of the magnetic tape MT.
• servo bands SB1, SB2, and SB3 are examples of “multiple servo bands” according to the technology disclosed herein. Note that, for ease of explanation, hereinafter, unless there is a particular need to distinguish between them, servo bands SB1 to SB3 will be referred to as “servo bands SB” and data bands DB1 and DB2 will be referred to as "data bands DB.”
• the servo bands SB1 to SB3 and the data bands DB1 and DB2 are formed along the longitudinal direction LD (i.e., the overall length direction) of the magnetic tape MT.
• the longitudinal direction LD refers to the running direction of the magnetic tape MT in other words.
• the running direction of the magnetic tape MT is defined as two directions: the forward direction (hereinafter also simply referred to as the "forward direction") in which the magnetic tape MT runs from the supply reel 22 side to the take-up reel 38 side, and the reverse direction (hereinafter also simply referred to as the "reverse direction") in which the magnetic tape MT runs from the take-up reel 38 side to the supply reel 22 side.
• the longitudinal direction LD is an example of the "longitudinal direction" and "first longitudinal direction” according to the technology disclosed herein.
• the servo bands SB1 to SB3 are arranged at positions spaced apart in the width direction WD of the magnetic tape MT (hereinafter also referred to simply as the "width direction WD").
• the servo bands SB1 to SB3 are arranged at equal intervals along the width direction WD.
• equal intervals refers to equal intervals that include, in addition to completely equal intervals, an error that is generally acceptable in the technical field to which the technology of this disclosure belongs and that does not go against the spirit of the technology of this disclosure.
• the width direction WD is an example of the "width direction” related to the technology of this disclosure.
• Data band DB1 is arranged between servo band SB1 and servo band SB2, and data band DB2 is arranged between servo band SB2 and servo band SB3.
• servo band SB and data band DB are arranged alternately along the width direction WD.
• three servo bands SB and two data bands DB are shown, but this is merely one example, and the technology disclosed herein can be applied to two servo bands SB and one data band DB, or to four or more servo bands SB and three or more data bands DB.
• a plurality of servo patterns 52 are recorded on the servo band SB along the longitudinal direction LD.
• the servo patterns 52 are classified into servo patterns 52A and servo patterns 52B.
• the plurality of servo patterns 52 are arranged at regular intervals along the longitudinal direction LD.
• Constant refers to not only complete constancy, but also constancy including an error that is generally acceptable in the technical field to which the technology of the present disclosure belongs and that does not go against the spirit of the technology of the present disclosure.
• the servo band SB is divided into a plurality of frames 50 along the longitudinal direction LD.
• Each frame 50 is defined by a set of servo patterns 52.
• servo patterns 52A and 52B are shown as an example of a set of servo patterns 52.
• the servo patterns 52A and 52B are adjacent to each other along the longitudinal direction LD, and within the frame 50, the servo pattern 52A is located on the upstream side in the forward direction, and the servo pattern 52B is located on the downstream side in the forward direction.
• the servo pattern 52 is made up of linear magnetization region pairs 54.
• the linear magnetization region pairs 54 are classified into linear magnetization region pairs 54A and linear magnetization region pairs 54B.
• the servo pattern 52A is made up of a pair of linear magnetized regions 54A.
• a pair of linear magnetized regions 54A1 and 54A2 is shown as an example of the pair of linear magnetized regions 54A.
• Each of the linear magnetized regions 54A1 and 54A2 is a linearly magnetized region.
• the linear magnetization regions 54A1 and 54A2 are inclined in opposite directions with respect to a virtual line C1, which is a virtual line along the width direction WD.
• the linear magnetization regions 54A1 and 54A2 are inclined in line symmetry with respect to the virtual line C1. More specifically, the linear magnetization regions 54A1 and 54A2 are formed non-parallel to each other and inclined at a predetermined angle (e.g., 5 degrees) in opposite directions on the longitudinal direction LD side with the virtual line C1 as the axis of symmetry.
• the linear magnetization region 54A1 is a collection of five magnetized straight lines, called magnetization lines 54A1a.
• the linear magnetization region 54A2 is a collection of five magnetized straight lines, called magnetization lines 54A2a.
• the servo pattern 52B is made up of a pair of linear magnetization regions 54B.
• a pair of linear magnetization regions 54B1 and 54B2 is shown as an example of the pair of linear magnetization regions 54B.
• Each of the linear magnetization regions 54B1 and 54B2 is a linearly magnetized region.
• the linear magnetization regions 54B1 and 54B2 are inclined in opposite directions with respect to a virtual line C2, which is a virtual line along the width direction WD.
• the linear magnetization regions 54B1 and 54B2 are inclined in line symmetry with respect to the virtual line C2. More specifically, the linear magnetization regions 54B1 and 54B2 are formed non-parallel to each other and inclined at a predetermined angle (e.g., 5 degrees) in opposite directions on the longitudinal direction LD side with the virtual line C2 as the axis of symmetry.
• Linear magnetization region 54B1 is a collection of four magnetized straight lines, called magnetization lines 54B1a.
• Linear magnetization region 54B2 is a collection of four magnetized straight lines, called magnetization lines 54B2a.
• the magnetic head 28 is disposed on the surface 31 side of the magnetic tape MT configured in this manner.
• the holder 44 is formed in a rectangular parallelepiped shape and is disposed so as to cross the surface 31 of the magnetic tape MT in the width direction WD.
• the multiple magnetic elements of the magnetic element unit 42 are arranged in a straight line along the longitudinal direction of the holder 44.
• the magnetic element unit 42 has a pair of servo read elements SR and multiple data recording/reproducing elements DRW as the multiple magnetic elements.
• the longitudinal length of the holder 44 is sufficiently long compared to the width of the magnetic tape MT.
• the longitudinal length of the holder 44 is set to be longer than the width of the magnetic tape MT regardless of where the magnetic element unit 42 is positioned on the magnetic tape MT.
• the magnetic head 28 is equipped with a pair of servo read elements SR.
• the pair of servo read elements SR consists of servo read elements SR1 and SR2.
• the servo read element SR1 is disposed at one end of the magnetic element unit 42, and the servo read element SR2 is disposed at the other end of the magnetic element unit 42.
• the servo read element SR1 is provided at a position corresponding to the servo band SB3
• the servo read element SR2 is provided at a position corresponding to the servo band SB2.
• the multiple data recording and reproducing elements DRW are arranged in a straight line between the servo read element SR1 and the servo read element SR2.
• the multiple data recording and reproducing elements DRW are arranged at intervals along the longitudinal direction of the magnetic head 28 (e.g., arranged at equal intervals along the longitudinal direction of the magnetic head 28).
• the longitudinal direction of the magnetic head 28, i.e., the longitudinal direction of the holder 44 coincides with the width direction WD.
• the multiple data recording and reproducing elements DRW are provided at positions corresponding to the data band DB2.
• the processing device 30 acquires a servo pattern signal that is the result of the servo pattern 52 being read by the servo read element SR, and performs servo control according to the acquired servo pattern signal.
• the servo pattern signal is an example of a "signal" related to the technology disclosed herein.
• servo control refers to control that moves the magnetic head 28 in the width direction WD of the magnetic tape MT by operating the movement mechanism 48 in accordance with the servo pattern 52 read by the servo read element SR.
• the multiple data recording and reproducing elements DRW are positioned over a specified area in the data band DB, and in this state, magnetic processing is performed on the specified area in the data band DB.
• magnetic processing is performed by the multiple data recording and reproducing elements DRW on a specified area in the data band DB2.
• the movement mechanism 48 moves the magnetic head 28 in the width direction WD to change the positions of the pair of servo read elements SR. That is, the movement mechanism 48 moves the magnetic head 28 in the width direction WD to move the servo read element SR1 to a position corresponding to the servo band SB2, and moves the servo read element SR2 to a position corresponding to the servo band SB1.
• the positions of the multiple data recording and reproducing elements DRW are changed from on the data band DB2 to on the data band DB1, and the multiple data recording and reproducing elements DRW perform magnetic processing on the data band DB1.
• data band DB2 has data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7, and DT8 formed from the servo band SB2 side to the servo band SB3 side as multiple divided areas obtained by dividing data band DB2 in the width direction WD.
• the magnetic head 28 has multiple data recording and reproducing elements DRW, namely data recording and reproducing elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8, arranged along the width direction WD between the servo read element SR1 and the servo read element SR2.
• the data recording and reproducing elements DRW1 to DRW8 correspond one-to-one to the data tracks DT1 to DT8, and are capable of reproducing (i.e., reading) data from the data tracks DT1 to DT8, and recording (i.e., writing) data to the data tracks DT1 to DT8.
• data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7, and DT8 will be referred to as “data tracks DT.”
• data recording and reproducing elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 will be referred to as "data recording and reproducing elements DRW.”
• a plurality of data tracks DT corresponding to data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7 and DT8 are also formed on data band DB1 (see FIG. 6).
• the data track DT has a split data track group DTG.
• Data tracks DT1 to DT8 correspond to split data track groups DTG1 to DTG8.
• the split data track groups DTG1 to DTG8 will be referred to as "split data track groups DTG.”
• the split data track group DTG1 is a collection of multiple split data tracks obtained by dividing the data track DT in the width direction WD.
• split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11, and DT_12 are shown as an example of the split data track group DTG1, obtained by dividing the data track DT into 12 equal parts in the width direction WD.
• the data recording and reproducing element DRW1 is responsible for magnetic processing of the split data track group DTG1.
• the data recording and reproducing element DRW1 is responsible for recording data to the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11, and DT_12, and reproducing data from the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11, and DT_12.
• split data track DT_N when there is no need to distinguish between the split data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11 and DT_12, they will be referred to as "split data track DT_N.”
• each of the data recording and reproducing elements DRW2 to DRW8 is responsible for magnetic processing of the divided data track group DTG of the data track DT corresponding to each data recording and reproducing element DRW.
• the data recording and reproducing element DRW moves to a position corresponding to a specified one of the multiple data tracks DT as the magnetic head 28 moves in the width direction WD (i.e., along the longitudinal direction of the magnetic head 28) by the moving mechanism 48 (see FIG. 6).
• the data recording and reproducing element DRW is held at a position corresponding to a specified one of the data tracks DT by servo control using the servo pattern 52 (see FIG. 6 and FIG. 7).
• paths P1 to P12 are assigned to the servo pattern 52 at equal intervals along the width direction WD.
• the paths P1 to P12 correspond to a number of divided data tracks DT_N (12 divided data tracks DT_N in the example shown in FIGS. 8 and 9) included in the divided data track group DTG.
• the paths P1 to P12 are broadly divided into paths Pa1 to Pa12 used when recording data and paths Pb1 to Pb12 used when reproducing data. In the following, when there is no need to distinguish between the paths P1 to P12, they will be referred to as "path P.”
• the movement mechanism 48 moves the magnetic head 28 in the width direction WD so that the servo read element SR passes on the path P corresponding to the target split data track.
• the movement mechanism 48 moves the magnetic head 28 in the width direction WD so that the servo read element SR passes on the path P1.
• the movement mechanism 48 moves the magnetic head 28 in the width direction WD so that the servo read element SR passes on the path P12. This allows the data recording and reproducing element DRW1 to face the target split data track and perform magnetic processing on the target split data track.
• all divided data tracks DT_N (here, as an example, 12 divided data tracks DT_N) that form one data track DT are formed by recording data on the magnetic tape MT using the data recording and reproducing element DRW in the SMR method.
• the SMR method is a magnetic recording method for increasing the density of data on the magnetic tape MT, and is also called the shingled recording method.
• the width direction WD is defined by a first direction WD1, which is the direction toward one end of the width of the magnetic tape MT, and a second direction WD2, which is the direction toward the other end of the width of the magnetic tape MT.
• the second direction WD2 is the direction in which data is shifted on the magnetic tape MT by recording data on the magnetic tape MT using the SMR method.
• the multiple divided data tracks DT_N for each data track DT are recorded on the magnetic tape MT so that they overlap and are shifted along the second direction WD2. For one data track DT, adjacent divided data tracks DT_N in the width direction WD are shifted at a constant pitch Tp in the width direction WD.
• the multiple split data tracks DT_N for each data track DT are an example of “multiple tracks” according to the technology of the present disclosure.
• the pitch Tp is an example of "track pitch” according to the technology of the present disclosure.
• the split data tracks DT_1 to DT_12 are intentionally illustrated as being shifted in the longitudinal direction LD to make it easier to understand the relative positions of the split data tracks DT_1 to DT_12, but in reality, there is no shift in the longitudinal direction LD between the split data tracks DT_1 to DT_12, and the split data tracks DT_1 to DT_12 extend in the longitudinal direction LD.
• a guard band GB is formed between each of the data tracks DT in the width direction WD.
• the guard band GB is a blank area that is not used for recording or reproducing data.
• the guard band GB formed between the data tracks DT serves to prevent the magnetic processing of one of the adjacent data tracks DT from affecting the other data track DT due to, for example, variations in the spacing between the data recording and reproducing elements DRW (for example, variations within the manufacturing tolerance).
• guard bands GB are formed between the servo bands SB and the data bands DB in the width direction WD.
• the guard bands GB between the servo bands SB and the data bands DB serve to, for example, prevent the magnetic influence of the servo read element SR on the servo band SB from affecting the data track DT, or the magnetic influence of the data recording/reproducing element DRW from affecting the servo band SB.
• the magnetic head 28 includes a first recording module DWM1, a second recording module DWM2, and a playback module DRM.
• a first recording module DWM1 a second recording module DWM2
• a playback module DRM a playback module
• the recording module DWM and the playback module DRM are arranged along the longitudinal direction LD (in other words, in the example shown in FIG. 11, the short direction of the magnetic head 28).
• the recording module DWM is arranged on both sides of the playback module DRM in the longitudinal direction LD.
• the example shown in FIG. 11 shows a schematic example of the state of the front side of the magnetic head 28 shown in FIG. 3 when viewed from the opposite direction to the direction indicated by the arrow B in FIG. 3, with the first recording module DWM1 arranged on the side of the feed reel 22 (see FIG. 3) of the playback module DRM in the longitudinal direction LD, and the second recording module DWM2 arranged on the side of the take-up reel 38 (see FIG. 3) of the playback module DRM in the longitudinal direction LD.
• the recording module DWM and the reproduction module DRM are provided with a magnetic element unit 42.
• the magnetic element unit 42 includes a servo read element SR1, a servo read element SR2, a first data recording element group DWG1, a second data recording element group DWG2, and a data reproduction element group DRG.
• the first data recording element group DWG1 is provided in the first recording module DWM1.
• the second data recording element group DWG2 is provided in the second recording module DWM2.
• the data reproduction element group DRG is provided in the reproduction module DRM.
• Servo read element SR1 is located at one end of magnetic element unit 42, and servo read element SR2 is located at the other end of magnetic element unit 42.
• the data recording/reproducing element DRW has a first data recording element DW1, a second data recording element DW2, and a data reproducing element DR.
• the first data recording element group DWG1 includes a plurality of first data recording elements DW1, which are arranged linearly along the width direction WD (in other words, the longitudinal direction of the magnetic head 28 in the example shown in FIG. 11).
• the arrangement direction of the plurality of first data recording elements DW1 is parallel to the surface 31 of the magnetic tape MT and is parallel to the width direction WD (in other words, perpendicular to the longitudinal direction LD).
• the second data recording element group DWG2 includes a plurality of second data recording elements DW2, which are arranged linearly along the width direction WD.
• the arrangement direction of the plurality of second data recording elements DW2 is parallel to the surface 31 of the magnetic tape MT and is parallel to the width direction WD (in other words, perpendicular to the longitudinal direction LD).
• the data reproduction element group DRG includes multiple data reproduction elements DR, which are arranged linearly along the width direction WD.
• the arrangement direction of the multiple data reproduction elements DR is parallel to the surface 31 of the magnetic tape MT and is also parallel to the width direction WD (in other words, perpendicular to the longitudinal direction LD).
• the data recording element DW is an example of a "recording element" related to the technology disclosed herein.
• the data recording element DW records data onto the data track DT.
• the data reproducing element DR reproduces data from the data track DT.
• the first data recording element group DWG1, the second data recording element group DWG2, and the data reproducing element group DRG are arranged at regular intervals along the longitudinal direction LD from the supply reel 22 side to the take-up reel 38 side in the order of the first data recording element group DWG1, the data reproducing element group DRG, and the second data recording element group DWG2.
• the regular interval refers to an interval that is determined in advance by testing an actual device and/or computer simulation as an interval at which no crosstalk occurs between the data recording element DW and the data reproducing element DR.
• the servo read element SR has a first servo read element SRa, a second servo read element SRb, and a third servo read element SRc. That is, each of the servo read elements SR1 and SR2 has a first servo read element SRa, a second servo read element SRb, and a third servo read element SRc.
• the first servo read element SRa, the second servo read element SRb, and the third servo read element SRc are arranged in the order of the first servo read element SRa, the second servo read element SRb, and the third servo read element SRc from the supply reel 22 (see FIG. 3) side to the take-up reel 38 (see FIG. 3) side in the longitudinal direction LD.
• the first data recording element group DWG1 has a plurality of first data recording elements DW1.
• the first data recording elements DW1 record data on the corresponding data tracks DT among all the data tracks DT included in the data band DB.
• the first recording module DWM1 is provided with a pair of first servo read elements SRa, which are adjacent to each other in the width direction WD via a plurality of first data recording elements DW1.
• the plurality of first data recording elements DW1 are arranged linearly and at equal intervals between one and the other of the pair of first servo read elements SRa.
• the number of the first data recording elements DW1 included in the first data recording element group DWG1 is the same as the number of data tracks DT included in the data band DB.
• eight first data recording elements DW1 are illustrated as the multiple first data recording elements DW1, and the positions of these first data recording elements DW1 correspond to the positions of the data recording and reproducing elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 (see FIG. 7 and FIG. 8).
• the data reproduction element group DRG has multiple data reproduction elements DR.
• the data reproduction elements DR reproduce data from the corresponding data tracks DT among all the data tracks DT included in the data band DB.
• the playback module DRM is provided with a pair of second servo read elements SRb, which are adjacent to each other in the width direction WD via a plurality of data playback elements DR.
• the plurality of data playback elements DR are arranged linearly and at equal intervals between one and the other of the pair of second servo read elements SRb.
• the number of data reproducing elements DR included in the data reproducing element group DRG is the same as the number of data tracks DT included in the data band DB.
• eight data reproducing elements DR are illustrated as the multiple data reproducing elements DR, and the positions of these data reproducing elements DR correspond to the positions of the data recording and reproducing elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 (see FIG. 7 and FIG. 8).
• the second data recording element group DWG2 has a plurality of second data recording elements DW2.
• the second data recording elements DW2 record data on the corresponding data tracks DT among all the data tracks DT included in the data band DB.
• the second recording module DWM2 is provided with a pair of third servo read elements SRc, which are adjacent to each other in the width direction WD via a plurality of second data recording elements DW2.
• the plurality of second data recording elements DW2 are arranged linearly and at equal intervals between one and the other of the pair of third servo read elements SRc.
• the number of the second data recording elements DW2 included in the second data recording element group DWG2 is the same as the number of data tracks DT included in the data band DB.
• eight second data recording elements DW2 are illustrated as the multiple second data recording elements DW2, and the positions of these second data recording elements DW2 correspond to the positions of the data recording and reproducing elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 (see FIG. 7 and FIG. 8).
• the center position of the data recording element DW and the center position of the data reproducing element DR included in the data recording and reproducing element DRW corresponding to one data track DT coincide in the width direction WD.
• the center position of the data recording element DW refers to, for example, the center position of the data recording element DW in the width direction WD.
• the center position of the data reproducing element DR refers to, for example, the center position of the data reproducing element DR in the width direction WD.
• “coincidence” refers to coincidence in the sense of a perfect coincidence as well as coincidence with an error that is generally acceptable in the technical field to which the technology of this disclosure belongs and that does not go against the spirit of the technology of this disclosure.
• the center position of the data recording element DW and the center position of the data reproducing element DR coincide in the width direction WD, which is also to realize the so-called "Read while write”.
• the first recording module DWM1 records data on the magnetic tape MT according to the servo pattern signal obtained by the first servo read element SRa while the magnetic tape MT is transported in the forward direction, and immediately thereafter the data is reproduced by the reproduction module DRM.
• "Read while write” is performed between the second recording module DWM2 and the reproduction module DRM in a similar manner.
• the length L1 of the data recording element DW in the width direction WD is longer than the length ⁇ 1 of the data reproducing element DR in the width direction WD, and is at least twice the pitch Tp. Furthermore, the length ⁇ 1 is less than the pitch Tp (see FIG. 10).
• the length L1 is an example of a "recording element length” according to the technology disclosed herein.
• the pitch Tp is an example of a "track pitch” according to the technology disclosed herein.
• the data reproducing element DR After the first data recording element DW1 forms a data track DT (see FIG. 10) by the SMR method according to the servo pattern signal obtained by reading the servo pattern 52 by the first servo read element SRa, the data reproducing element DR reproduces data from the divided data track DT_N (see FIG. 10) included in the data track DT. At this time, the data reproducing element DR reproduces data from the divided data track DT_N according to the servo pattern signal obtained by reading the servo pattern 52 by the second servo read element SRb.
• the second servo read element SRb is made to read the servo pattern 52 on a path P that is shifted by a distance Dr in the first direction WD1 from the path P along which the first servo read element SRa passes.
• the manufacturing method of magnetic tape MT includes multiple steps. These steps include a servo pattern recording step, an inspection step, and a winding step.
• steps include a servo pattern recording step, an inspection step, and a winding step.
• a servo writer SW is used in the servo pattern recording process.
• the servo writer SW includes a supply reel SW1, a take-up reel SW2, a drive unit SW3, a pulse signal generator SW4, a control unit SW5, multiple guides SW6, a transport path SW7, a servo pattern recording head WH, and a verify head VH.
• the servo pattern recording head WH is an example of a "servo write head" according to the technology disclosed herein.
• the control device SW5 controls the entire servo writer SW.
• the control device SW5 is realized by an ASIC, but the technology of the present disclosure is not limited to this.
• the control device SW5 may be realized by an FPGA and/or a PLC.
• the control device SW5 may also be realized by a computer including a CPU, a flash memory (e.g., an EEPROM and/or an SSD, etc.), and a RAM.
• the control device SW5 may also be realized by combining two or more of the ASIC, FPGA, PLC, and computer. In other words, the control device SW5 may be realized by a combination of a hardware configuration and a software configuration.
• a pancake is set on the delivery reel SW1.
• a pancake refers to a large diameter roll of magnetic tape MT that is cut to the product width from a wide web and wound around a hub before the servo pattern 52 is written.
• the drive unit SW3 has a motor (not shown) and gears (not shown), and is mechanically connected to the supply reel SW1 and the take-up reel SW2.
• the drive unit SW3 When the magnetic tape MT is wound by the take-up reel SW2, the drive unit SW3 generates power in accordance with instructions from the control unit SW5, and transmits the generated power to the supply reel SW1 and the take-up reel SW2 to rotate them.
• the supply reel SW1 receives power from the drive unit SW3 to rotate, thereby sending out the magnetic tape MT to the predetermined transport path SW7.
• the take-up reel SW2 receives power from the drive unit SW3 to rotate, thereby winding up the magnetic tape MT sent out from the supply reel SW1.
• the rotational speed and rotational torque of the supply reel SW1 and take-up reel SW2 are adjusted according to the speed at which the magnetic tape MT is wound around the take-up reel SW2.
• a number of guides SW6 and a servo pattern recording head WH are arranged on the transport path SW7.
• the servo pattern recording head WH is arranged between the number of guides SW6 on the surface 31 side of the magnetic tape MT.
• the magnetic tape MT sent from the delivery reel SW1 to the transport path SW7 is guided by the number of guides SW6, passes over the servo pattern recording head WH, and is wound up by the take-up reel SW2.
• the pulse signal generator SW4 generates a pulse signal under the control of the control device SW5 and supplies the generated pulse signal to the servo pattern recording head WH. While the magnetic tape MT is traveling at a constant speed on the transport path SW7, the servo pattern recording head WH forms servo bands SB on the magnetic tape MT by recording multiple servo patterns 52 along the longitudinal direction LD (see FIG. 6, etc.) in accordance with the pulse signal supplied from the pulse signal generator SW4 in the area where the formation of servo bands SB is planned in advance.
• the inspection process is a process for inspecting the magnetic tape MT on which the servo bands SB are formed.
• the servo bands SB formed on the surface 31 of the magnetic tape MT are inspected by the servo pattern recording head WH.
• Inspecting the servo bands SB refers to, for example, a process for judging whether the servo patterns 52 recorded on the servo bands SB are correct.
• Judging whether the servo patterns 52 are correct refers to, for example, judging whether the magnetization lines 54A1a, 54A2a, 54B1a, and 54B2a of the servo patterns 52A and 58B are recorded without excess or deficiency and within the allowable error with respect to predetermined locations on the surface 31 (i.e., verifying the servo patterns 52).
• the inspection of the servo bands SB is performed using the control device SW5 and the verify head VH.
• the verify head VH is positioned downstream of the servo pattern recording head WH in the transport direction of the magnetic tape MT.
• the verify head VH is provided with multiple servo read elements (not shown) like the magnetic head 28, and the multiple servo read elements read the multiple servo bands SB.
• the verify head VH is connected to the control device SW5.
• the verify head VH is positioned directly opposite the servo band SB when viewed from the surface 31 side of the magnetic tape MT (i.e., the back side of the verify head VH), reads the servo pattern 52 recorded on the servo band SB, and outputs the read result (hereinafter referred to as the "servo pattern read result") to the control device SW5.
• the control device SW5 inspects the servo band SB (e.g., determines whether the servo pattern 52 is correct or not) based on the servo pattern read result (e.g., servo pattern signal) input from the verify head VH.
• the control device SW5 outputs information indicating the results of inspecting the servo band SB (e.g., the result of determining whether the servo pattern 52 is correct or not) to a predetermined output destination (e.g., a storage device built into the servo writer SW, a display connected to the servo writer SW, and/or an external device connected to the servo writer SW so that it can communicate with the servo writer SW, etc.).
• a predetermined output destination e.g., a storage device built into the servo writer SW, a display connected to the servo writer SW, and/or an external device connected to the servo writer SW so that it can communicate with the servo writer SW, etc.
• the winding process is a process of winding the magnetic tape MT around the supply reel 22 (i.e., the supply reel 22 (see Figures 2 to 4) housed in the magnetic tape cartridge 12 (see Figures 1 to 4)) used for each of the multiple magnetic tape cartridges 12 (see Figures 1 to 4).
• a winding motor M is used in the winding process.
• the winding motor M is mechanically connected to the supply reel 22 via a gear or the like. Under the control of a control device (not shown), the winding motor M applies a rotational force to the supply reel 22 to rotate the supply reel 22.
• the magnetic tape MT wound around the winding reel SW2 is wound around the supply reel 22 by the rotation of the supply reel 22.
• a cutting device (not shown) is used.
• the magnetic tape MT sent from the take-up reel SW2 to the supply reel 22 is cut by a cutting device.
• FIG. 13 shows an example of the configuration of the servo pattern recording head WH when observed from the surface 31 side (i.e., the back side of the servo pattern recording head WH) of the magnetic tape MT traveling on the transport path SW7 (see FIG. 12), and an example of the configuration of the pulse signal generator SW4.
• the servo pattern recording head WH has a base WH1 and multiple head cores WH2.
• the base WH1 is formed in a rectangular parallelepiped shape and is arranged to cross the surface 31 of the magnetic tape MT running on the transport path SW7 in the width direction WD.
• the surface WH1A of the base WH1 is a rectangle having a long side WH1Aa and a short side WH1Ab, and the long side WH1Aa crosses the surface 31 of the magnetic tape MT in the width direction WD.
• Surface WH1A has a sliding surface WH1Ax.
• the sliding surface WH1Ax is the surface of surface WH1A that overlaps with surface 31 of magnetic tape MT when base WH1 crosses surface 31 of magnetic tape MT in width direction WD.
• the sliding surface WH1Ax slides against the magnetic tape MT in a running state.
• the width of sliding surface WH1Ax shown in FIG. 13 i.e., the length in direction LD1 corresponding to longitudinal direction LD (e.g., the same direction as longitudinal direction LD)
• the width of sliding surface WH1Ax may be several times wider than the example shown in FIG. 13.
• the longitudinal direction of the base WH1 corresponds to the width direction WD (e.g., the same direction as the width direction WD).
• a plurality of head cores WH2 are assembled in the base WH1 along the direction WD3.
• a plurality of gap patterns G are formed at intervals along the direction WD3 on the surface WH1A of the head core WH2 (i.e., the surface of the base WH1 facing the surface 31 of the magnetic tape MT).
• the direction WD3 is an example of a "second longitudinal direction” according to the technology disclosed herein.
• the surface WH1A is an example of a "facing surface” according to the technology disclosed herein.
• the gap pattern G is an example of a "gap pattern” according to the technology disclosed herein.
• the gap pattern G is made up of a pair of non-parallel straight line regions.
• the pair of non-parallel straight line regions refers to, for example, a straight line region having the same geometric characteristics as the magnetization straight line 54A1a located at the most upstream side in the forward direction among the five magnetization straight lines 54A1a included in the linear magnetization region 54A1 shown in FIG. 6, and a straight line region having the same geometric characteristics as the magnetization straight line 54A2a located at the most upstream side in the forward direction among the five magnetization straight lines 54A2a included in the linear magnetization region 54A2 shown in FIG. 6.
• a plurality of gap patterns G are formed at intervals along the direction WD3.
• the interval in the direction WD3 between adjacent gap patterns G in the direction WD3 corresponds to the interval in the width direction WD between the servo bands SB of the magnetic tape MT (i.e., the servo band pitch).
• a coil (not shown) is wound around head core WH2, and a pulse signal is supplied to the coil.
• the pulse signal supplied to the coil is a pulse signal for servo pattern 52A and a pulse signal for servo pattern 52B.
• the servo pattern recording head WH When the servo pattern recording process is performed by the servo writer SW configured in this manner, the servo pattern recording head WH is positioned in a position in which the surface 31 of the magnetic tape MT faces the multiple gap patterns G. Then, while maintaining this position, the servo write head WH records multiple servo patterns G along the longitudinal direction LD on the surface 31 of the magnetic tape MT, thereby forming multiple servo bands SB (see FIG. 6) on the surface 31. The method of forming multiple servo bands SB on the surface 31 will be described in more detail below.
• a pulse signal for the servo pattern 52A is supplied to the coil of the head core WH2, and a magnetic field is applied from the gap pattern G to the servo band SB of the magnetic tape MT in accordance with the pulse signal.
• the servo pattern 52A is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB is planned in advance.
• a pulse signal for the servo pattern 52B is supplied to the coil of the head core WH2, and a magnetic field is applied from the gap pattern G to the servo band SB of the magnetic tape MT.
• the servo pattern 52B is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB is planned in advance.
• servo patterns 52A and 52B are alternately formed along the longitudinal direction in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB is planned in advance, thereby forming the servo band SB.
• the pulse signal corresponding to each servo pattern 52 (i.e., the servo pattern 52 for each frame 50 (see FIG. 6)) is modulated.
• various information is embedded in the pulse signal.
• the pulse signal for the servo pattern 52A it is possible to change the interval (hereinafter referred to as the "first interval") between the third magnetization line 54A1a and the second magnetization line 54A1a among the five magnetization lines 54A1a (see FIG. 6) and the interval (hereinafter referred to as the "second interval") between the third magnetization line 54A1a and the fourth magnetization line 54A1a for each servo pattern 52A.
• the first interval and the second interval different for each servo pattern 52A, it is possible to embed at least one bit of information in each servo pattern 52A. This makes it possible to embed various information by combining multiple servo patterns 52.
• the various information includes, for example, information regarding the position of the magnetic tape MT in the longitudinal direction LD, information identifying the servo band SB, and/or information identifying the manufacturer of the magnetic tape MT, etc.
• head cores WH2A, WH2B, and WH2C are shown as examples of multiple head cores WH2, and gap patterns G1, G2, and G3 are shown as examples of multiple gap patterns G.
• Gap pattern G1 is formed in head core WH2A.
• Gap pattern G2 is formed in head core WH2B.
• Gap pattern G3 is formed in head core WH2C.
• gap pattern G1 is used to record servo pattern 52 (see FIG. 6) for servo band SB3 (see FIG. 6)
• gap pattern G2 is used to record servo pattern 52 (see FIG. 6) for servo band SB2 (see FIG. 6)
• gap pattern G3 is used to record servo pattern 52 (see FIG. 6) for servo band SB1 (see FIG. 6).
• Gap pattern G1 is a pair of linear regions consisting of linear regions G1A and G1B.
• Gap pattern G2 is a pair of linear regions consisting of linear regions G2A and G2B.
• Gap pattern G3 is a pair of linear regions consisting of linear regions G3A and G3B.
• gap patterns G1 to G3 are examples of "multiple gap patterns" according to the technology disclosed herein.
• the pulse signal generator SW4 has a first pulse signal generator SW4A, a second pulse signal generator SW4B, and a third pulse signal generator SW4C.
• the first pulse signal generator SW4A is connected to the head core WH2A.
• the second pulse signal generator SW4B is connected to the head core WH2B.
• the third pulse signal generator SW4C is connected to the head core WH2C.
• the first pulse signal generator SW4A supplies a pulse signal to head core WH2A, and a magnetic field is applied from gap pattern G1 to the area on surface 31 of magnetic tape MT where servo band SB3 is planned to be formed in advance in accordance with the pulse signal, and servo pattern 52 (see FIG. 6) is recorded in the area where servo band SB3 is planned to be formed in advance.
• the servo pattern 52A (see FIG. 6) is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is planned. That is, the linear magnetization area 54A1 (see FIG. 6) is recorded by the straight line area G1A in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is planned, and the linear magnetization area 54A2 (see FIG. 6) is recorded by the straight line area G1B in the servo band SB3. As a result, the servo pattern 52A is formed in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is planned.
• the gap pattern G1 faces (in other words, faces directly) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the formation of the servo band SB3 is planned
• the servo pattern 52B (see FIG. 6) is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned. That is, the linear magnetization area 54B1 (see FIG. 6) is recorded by the straight line area G1A in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned, and the linear magnetization area 54B2 (see FIG.
• servo patterns 52A and 52B are alternately formed along the longitudinal direction LD in the area on the surface 31 of the magnetic tape MT where the formation of servo band SB3 is planned in advance, thereby forming servo band SB3.
• gap pattern G2 is used to form servo band SB2 (see FIG. 6)
• second pulse signal generator SW4B supplies a pulse signal to head core WH2B
• a magnetic field is applied from gap pattern G2 to the area on surface 31 of magnetic tape MT where servo band SB2 is planned to be formed in advance in accordance with the pulse signal, and servo pattern 52 (see FIG. 6) is recorded in the area on surface 31 of magnetic tape MT where servo band SB2 is planned to be formed in advance.
• the gap pattern G2 faces (in other words, faces directly) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the formation of the servo band SB2 is planned, and a pulse signal for the servo pattern 52A is supplied to the head core WH2B
• the servo pattern 52A (see FIG. 6) is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB2 is planned.
• the linear magnetization area 54A1 is recorded by the straight line area G2A in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB2 is planned, and the linear magnetization area 54A2 (see FIG.
• the gap pattern G2 faces (in other words, faces directly) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the servo band SB2 is scheduled to be formed
• a pulse signal for the servo pattern 52B is supplied to the head core WH2B
• the servo pattern 52B is recorded in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is scheduled to be formed in advance.
• the linear magnetization area 54B1 is recorded by the straight line area G2A in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is scheduled to be formed in advance, and the linear magnetization area 54B2 (see FIG.
• servo patterns 52A and 52B are alternately formed along the longitudinal direction LD in the area on the surface 31 of the magnetic tape MT where the formation of servo band SB2 is planned in advance, thereby forming servo band SB2.
• gap pattern G3 is used to form servo band SB1 (see FIG. 6)
• third pulse signal generator SW4C supplies a pulse signal to head core WH2C
• a magnetic field is applied from gap pattern G3 to the area on surface 31 of magnetic tape MT where servo band SB1 is planned to be formed in advance in accordance with the pulse signal, and servo pattern 52 (see FIG. 6) is recorded in the area on surface 31 of magnetic tape MT where servo band SB1 is planned to be formed in advance.
• the gap pattern G3 faces (in other words, faces directly) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the formation of the servo band SB1 is planned, and a pulse signal for the servo pattern 52A is supplied to the head core WH2C
• the servo pattern 52A is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned. That is, the linear magnetization area 54A1 (see FIG. 6) is recorded by the straight line area G3A in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned, and the linear magnetization area 54B2 (see FIG.
• the gap pattern G3 faces (in other words, faces directly) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the formation of the servo band SB1 is planned
• the servo pattern 52B is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned. That is, the linear magnetization area 54B1 (see FIG. 6) is recorded by the straight line area G3A in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned, and the linear magnetization area 54B2 (see FIG.
• servo patterns 52A and 52B are alternately formed along the longitudinal direction LD in the area on the surface 31 of the magnetic tape MT where the formation of servo band SB1 is planned in advance, thereby forming servo band SB1.
• Head core WH2C has a magnetic film 60 and a base glass 62.
• the magnetic film 60 forms the base of head core WH2C.
• An example of the magnetic film 60 is a metal film.
• the concept of "metal film” also includes an alloy film.
• An example of a metal film is a deposition film in which one or more metal materials selected from a group consisting of one or more pure metals and one or more alloys are deposited.
• the metal film may also contain one or more additives, and may also contain one or more impurities that are inevitably mixed in.
• the magnetic film 60 may be an iron-based alloy film.
• “based” means “contains”.
• the iron-based alloy film is preferably an iron nitride-based alloy film.
• An example of an iron nitride-based alloy is a constituent element containing one or more elements selected from a group consisting of Fe and N as well as Al and/or Ta.
• the magnetic film 60 may be obtained as a deposition film by depositing a metal material on a substrate by known film formation methods such as physical vapor deposition (PVD) such as sputtering and/or vacuum deposition, and/or chemical vapor deposition (CVD).
• PVD physical vapor deposition
• CVD chemical vapor deposition
• the base glass 62 together with the magnetic film 60, forms the base of the head core WH2C.
• a non-magnetic material is used for the base glass 62.
• a plane 66 is formed by the magnetic film 60 and the base glass 62.
• a linear opening 66A is formed on the base glass 62, and a non-magnetic material 68 such as silicon dioxide and/or aluminum is filled into the opening 66A to form a base G3B1.
• the base G3B1 is the base of the linear region G3B.
• the head core WH2C is formed by a method using photolithography. If the base G3B1, which has low linearity in the ridge region 70, were used as the linear region G3B as is, it would be difficult to record a highly linear servo pattern 52 on the surface 31 of the magnetic tape MT. If the linearity of the servo pattern 52 becomes low, the accuracy of the servo control would decrease.
• the following first to third methods can be given as examples of methods for improving the linearity of the ridge region 70.
• the first method is to improve the linearity of the ridge region 70 by increasing the accuracy of the photomask used in photolithography.
• the second method is to form a linear groove 71 of a size corresponding to the full width of the opening 66A of the head core WH2C formed by a method using photolithography by trimming the full width of the opening 66A with an FIB or laser, and to form the linear region G3B by filling the groove 71 with a non-magnetic material 68.
• the third method is to form a groove 72 by linearly trimming the ridge region 70 of the base G3B1 of the head core WH2C formed by a method using photolithography with an FIB or laser, and to form the linear region G3B by filling the groove 72 with a non-magnetic material 68.
• the head core WH2C formed by a photolithography method is processed using an FIB or laser to shape the base G3B1. That is, the ridge region 70 of the base G3B1 of the head core WH2C formed by a photolithography method is irradiated with an FIB or laser along the longitudinal direction of the base G3B1, thereby trimming the ridge region 70 of the base G3B1 into a straight line. Then, the non-magnetic material 68 is filled into the groove 72 obtained by trimming the base G3B1 with the FIB.
• the straight region G3B is formed by shaping the base G3B1 in this way. In this way, by processing using any of the first to third methods, the linearity of the straight region G3B can be improved, and the durability of the straight region G3B can be increased.
• linear regions G1A, G1B, G2A, G2B, and G3A can each be obtained by carrying out processing similar to that carried out to obtain linear region G3B.
• a linearity inspection method is performed on a magnetic tape MT on which multiple servo bands SB are formed, as shown in FIG. 14 as an example.
• the linearity inspection method is a method for inspecting the linearity of the servo pattern 52 formed on the magnetic tape MT, and is carried out, for example, in an inspection process included in the manufacturing method of the magnetic tape MT described above. Note that this is merely one example, and inspection using the linearity inspection method may be carried out using a magnetic tape drive 14.
• the linearity inspection method may be achieved mainly through manual measurement and other operations by an inspector (not shown), or may be achieved mainly through automation using an inspection device (not shown).
• the linearity inspection method shown in FIG. 14 is an example of an "inspection method" related to the technology disclosed herein.
• a pair of uninspected servo patterns 52 adjacent in the width direction WD i.e., a pair of servo patterns 52 whose linearity has not been inspected
• two servo bands SB e.g., servo bands SB2 and SB3 adjacent in the width direction WD in the magnetic tape MT on which multiple servo bands SB have been formed by the servo pattern recording process described above.
• an index (hereinafter also simply referred to as "index") indicating the nonlinearity of the servo patterns 52 is obtained from the pair of untested servo patterns 52 selected in step ST10.
• step ST14 the magnetic tape MT is inspected using the index acquired in step ST12.
• step ST14 the linearity of the pair of uninspected servo patterns 52 selected in step ST10 is inspected using the index acquired in step ST12.
• step ST16 it is determined whether the linearity of all test objects (i.e., all pairs of servo patterns 52 previously determined as test objects) contained in two adjacent servo bands SB in the width direction WD of the magnetic tape MT has been inspected. If the linearity of all test objects contained in two adjacent servo bands SB in the width direction WD of the magnetic tape MT has not been inspected in step ST16, the determination is negative and the linearity inspection method proceeds to step ST10. If the linearity of all test objects contained in two adjacent servo bands SB in the width direction WD of the magnetic tape MT has been inspected in step ST16, the determination is positive and the linearity inspection method ends.
• all test objects i.e., all pairs of servo patterns 52 previously determined as test objects
• the linearity inspection method is applied to two adjacent servo bands SB (e.g., servo bands SB2 and SB3) in the width direction WD of the magnetic tape MT, but the linearity inspection method is also applied to the other two adjacent servo bands SB (i.e., servo bands SB1 and SB2) in the width direction WD of the magnetic tape MT.
• the linearity inspection method is applied to each of all pairs of servo bands SB adjacent in the width direction WD.
• PES refers to the position in the width direction WD within the servo pattern 52. PES is measured using the following formula (1).
• FIG. 15 shows a conceptual diagram to explain the PES of the linear magnetized region 54A1 in the servo pattern 52A when the magnetic tape MT runs in the forward direction, and the variables used in equation (1) to measure the PES.
• ⁇ 1 is an angle determined in advance as the angle between the virtual straight line C1 and the linear magnetization region 54A1.
• ⁇ 2 is an angle determined in advance as the angle between the virtual straight line C1 and the linear magnetization region 54A2.
• ⁇ 1 and ⁇ 2 are the same value.
• i is a natural number between 1 and 4.
• the maximum value of “i” (here, 4) is the number of magnetization lines 54A1a used to measure the PES.
• “Ai” refers to the distance between magnetization lines 54A1a and 54A2a at corresponding positions when the servo read element SR3 of the verify head VH crosses the servo pattern 52A along the longitudinal direction LD.
• magnetic lines 54A1a and 54A2a at corresponding positions refers to the first to fourth magnetization line pairs.
• the first magnetization line pair refers to the magnetization line 54A1a and magnetization line 54A2a located at the most upstream side in the running direction of the magnetic tape MT in each of the linear magnetization regions 54A1 and 54A2.
• the second pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a located second from the most upstream side to the downstream side in the running direction of the magnetic tape MT in each of the linear magnetization regions 54A1 and 54A2.
• the third pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a located third from the most upstream side to the downstream side in the running direction of the magnetic tape MT in each of the linear magnetization regions 54A1 and 54A2.
• the fourth pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a located fourth from the most upstream side to the downstream side in the running direction of the magnetic tape MT in each of the linear magnetization regions 54A1 and 54A2.
• Magnetic lines 54A1a and 54B1a at corresponding positions refers to the fifth to eighth pairs of magnetization lines.
• the fifth pair of magnetization lines refers to magnetization lines 54A1a and 54B1a located at the most upstream side in the running direction of the magnetic tape MT in linear magnetization region 54A1 in servo pattern 52A and linear magnetization region 54B1 in servo pattern 52B adjacent to servo pattern 52A on the forward side.
• the sixth pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a located second from the most upstream side to the downstream side in the running direction of the magnetic tape MT in the linear magnetization region 54A1 in the servo pattern 52A and the linear magnetization region 54B1 in the servo pattern 52B adjacent to the servo pattern 52A on the forward side.
• the seventh pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a located third from the most upstream side to the downstream side in the running direction of the magnetic tape MT in the linear magnetization region 54A1 in the servo pattern 52A and the linear magnetization region 54B1 in the servo pattern 52B adjacent to the servo pattern 52A on the forward side.
• the eighth magnetization line pair refers to the magnetization line 54A1a and magnetization line 54B1a that are located fourth from the most upstream side to the downstream side in the running direction of the magnetic tape MT in each of the linear magnetization area 54A1 in the servo pattern 52A and the linear magnetization area 54B1 in the servo pattern 52B adjacent to the forward side of the servo pattern 52A.
• “d” is a predetermined distance between linear magnetization region 54A1 and linear magnetization region 54B1 in the longitudinal direction LD.
• “d” is the predetermined distance between magnetization lines 54A1a and 54B1a at corresponding positions when servo read element SR3 crosses servo patterns 52A and 52B along the longitudinal direction LD.
• formula (1) is also used when measuring the PES in servo pattern 52B.
• “Bi” refers to the distance between magnetization lines 54B1a and 54A1a at corresponding positions when servo read element SR3 crosses servo pattern 52B and servo pattern 52A adjacent to servo pattern 52B on the forward side along the longitudinal direction LD.
• the center position of the servo pattern 52 in the width direction WD (for example, the position where the servo pattern 52 intersects with an imaginary line C3 that passes through the center of the servo pattern 52 in the width direction WD along the longitudinal direction LD) is set to "0"
• the position on the first direction WD1 side of the imaginary line C3 in the servo pattern 52 is expressed as a positive value
• the position on the second direction WD2 side of the imaginary line C3 in the servo pattern 52 is expressed as a negative value.
• a pair of servo patterns 52 (hereinafter also referred to as "adjacent servo pattern pairs") adjacent in the width direction WD included in two adjacent servo bands SB (hereinafter also referred to as “adjacent servo band pairs”) in the width direction WD of the magnetic tape MT on which multiple servo bands SB have been formed by the servo pattern recording process described above are read by servo read elements SR3 respectively used for each servo band SB, and multiple dPES are measured based on the servo pattern signals obtained by reading each servo pattern 52.
• dPES which is the difference between PES1 and PES2 is measured. If the magnetic tape MT does not deform in the width direction WD, the linearity of the servo patterns 52 is ideal, and the distance between the two servo read elements SR3 adjacent in the width direction WD is also at the design center, dPES will be "0".
• the inspection process requires inspection of the linearity of the servo pattern 52.
• multiple PES and multiple dPES are measured at multiple locations from one end of the servo pattern 52 (here, as an example, the end on the first direction WD1 side) to the other end (here, as an example, the end on the second direction WD2 side). Then, the PES difference gap ⁇ dPES is measured based on the multiple PES and multiple dPES.
• a plurality of first positions 74 and a plurality of second positions 76 are set in the one servo pattern 52 and the other servo pattern 52.
• the one servo pattern 52 refers to one servo pattern 52 included in an adjacent servo pattern pair recorded at a corresponding position in the width direction WD in the adjacent servo band pair, i.e., the upper servo pattern 52 shown in FIG. 16.
• the other servo pattern 52 refers to the other servo pattern 52 included in an adjacent servo pattern pair recorded at a corresponding position in the width direction WD in the adjacent servo band pair, i.e., the lower servo pattern 52 shown in FIG. 16.
• a plurality of first positions 74 and a plurality of second positions 76 are set from one end (e.g., the end on the first direction WD1 side) of the linear magnetization region 54A1 to the other end (e.g., the end on the second direction WD2 side).
• the plurality of first positions 74 and the plurality of second positions 76 are in a predetermined corresponding relationship.
• the first positions 74 and the second positions 76 which are in a positional relationship corresponding to each other, are set on the linear magnetization region 54A1 with an interval INT1 in the width direction WD.
• the first positions 74 and the second positions 76 which are in a positional relationship corresponding to each other, are set on the linear magnetization region 54A1 at intervals INT2 along the width direction WD.
• the interval INT1 is an interval roughly equivalent to the above-mentioned distance Dr (see FIG. 11), and the interval INT2 is an interval roughly equivalent to the pitch Tp.
• interval INT1 is an example of a "first predetermined interval” according to the technology of this disclosure.
• Interval INT2 is an example of a "second predetermined interval” according to the technology of this disclosure.
• interval INT1 is the interval that is closest to the reference interval.
• the reference interval is an interval that is a natural number multiple of interval INT2 (for example, a natural number multiple of 2 or more), and refers to an interval that is equivalent to half the difference between length L1 (see Figure 11) and pitch Tp.
• 1200 nm is used as an example of interval INT1
• 400 nm is used as an example of interval INT2.
• dPES is broadly divided into dPES(n) and dPES(n-3).
• dPES(n-3) is an example of a "first PES difference” according to the technology of the present disclosure.
• dPES(n) is an example of a "second PES difference” according to the technology of the present disclosure.
• dPES(n-3) is measured by using the PES of one first position 74 and the PES of the other first position 74 of a pair of first positions 74 that are in a corresponding positional relationship in an adjacent servo pattern pair.
• dPES(n-3) is measured by using the PES of one first position 74 and the PES of the other first position 74 of a pair of first positions 74 that correspond between a linear magnetization region 54A1 (e.g., the magnetization straight line 54A1a located on the most upstream side in the forward direction) included in one servo pattern 52 and a linear magnetization region 54A1 (e.g., the magnetization straight line 54A1a located on the most upstream side in the forward direction) included in the other servo pattern 52.
• a linear magnetization region 54A1 e.g., the magnetization straight line 54A1a located on the most upstream side in the forward direction
• dPES(n) is measured by using the PES of one second position 76 and the PES of the other second position 76 of a pair of second positions 76 that are in a corresponding positional relationship in an adjacent servo pattern pair.
• dPES(n) is measured by using the PES of one second position 76 and the PES of the other second position 76 of a pair of second positions 76 that correspond between a linear magnetization region 54A1 (e.g., the magnetization straight line 54A1a located on the most upstream side in the forward direction) included in one servo pattern 52 and a linear magnetization region 54A1 (e.g., the magnetization straight line 54A1a located on the most upstream side in the forward direction) included in the other servo pattern 52.
• a linear magnetization region 54A1 e.g., the magnetization straight line 54A1a located on the most upstream side in the forward direction
• ⁇ dPES are measured from multiple dPES(n-3) and multiple dPES(n).
• ⁇ dPES is the difference between dPES(n-3) and dPES(n), which correspond to each other.
• ⁇ dPES is an example of a "PES difference gap" according to the technology disclosed herein.
• the interval INT2 is one step, and the variable n corresponds to the number of measurement steps.
• 1200 nm is used as an example of the interval INT1
• 400 nm is used as an example of the interval INT2
• ⁇ dPES is calculated using the value of dPES at a measurement step position that is separated by "3", which is the ratio (in other words, the ratio) of the interval INT2 to the interval INT1.
• the variable n is incremented by 1 each time the first position 74 and the second position 76 advance one measurement step along the second direction WD2.
• variable n is incremented by 1 each time the first position 74 and the second position 76 are shifted by the interval INT2 along the second direction WD2, and the pair of first positions 74 and the pair of second positions 76 are updated accordingly.
• dPES(n-3) is measured for the updated pair of first positions 74
• dPES(n) is measured for the updated pair of second positions 76.
• ⁇ dPES i.e., the difference between dPES(n-3) and dPES(n) is measured from the measured dPES(n-3) and dPES(n).
• ⁇ dPES is measured at intervals INT2 along the second direction WD2, thereby obtaining multiple ⁇ dPES.
• a plurality of first positions 74 and a plurality of second positions 76 are set on a pair of linear magnetization regions 54A1 included in an adjacent servo pattern pair
• a plurality of first positions 74 and a plurality of second positions 76 are also set on a pair of linear magnetization regions 54A2 included in an adjacent servo pattern pair (for example, the magnetization straight line 54A2a located at the most upstream side in the forward direction included in one of the pair of linear magnetization regions 54A2, and the magnetization straight line 54A2a located at the most upstream side in the forward direction included in the other of the pair of linear magnetization regions 54A2).
• multiple dPES(n) and multiple dPES(n-3) are measured for the multiple first positions 74 and multiple second positions 76 on the pair of linear magnetized regions 54A1 included in the adjacent servo pattern pair
• multiple dPES(n) and multiple dPES(n-3) are also measured for the multiple first positions 74 and multiple second positions 76 on the pair of linear magnetized regions 54A2 included in the adjacent servo pattern pair.
• multiple ⁇ dPES are also measured from the multiple dPES(n) and multiple dPES(n-3) measured for the multiple first positions 74 and multiple second positions 76 on the pair of linear magnetized regions 54A1 included in the adjacent servo pattern pair.
• a plurality of first positions 74 and a plurality of second positions 76 are set on a pair of servo patterns 52A included in the adjacent servo pattern pair, a plurality of first positions 74 and a plurality of second positions 76 are also set on a pair of servo patterns 52B adjacent in the width direction WD.
• a plurality of dPES(n) and a plurality of dPES(n-3) are measured for the plurality of first positions 74 and a plurality of second positions 76 on a pair of servo patterns 52A included in the adjacent servo pattern pair
• a plurality of dPES(n) and a plurality of dPES(n-3) are also measured for the plurality of first positions 74 and a plurality of second positions 76 of a pair of servo patterns 52B adjacent in the width direction WD.
• multiple ⁇ dPESs are also measured from multiple dPESs (n) and multiple dPESs (n-3) measured for multiple first positions 74 and multiple second positions 76 on a pair of servo patterns 52B adjacent in the width direction WD.
• dPES will have a value equivalent to the amount by which the spacing between two servo read elements SR3 adjacent in the width direction WD deviates from the design center.
• dPES will have a value equivalent to the amount of deformation in the width direction WD of the magnetic tape MT.
• ⁇ dPES i.e., the difference between dPES(n) and dPES(n-3)
• the amount of deformation in the width direction WD of the magnetic tape MT and the amount by which the spacing between the two servo read elements SR3 adjacent in the width direction WD is shifted from the design center are offset.
• dPES includes a value corresponding to the amount by which the spacing between two servo read elements SR3 adjacent in the width direction WD is shifted from the design center, a value corresponding to the amount of deformation in the width direction WD of the magnetic tape MT, and a value indicating the linearity of the servo pattern 52.
• both dPES(n) and dPES(n-3) include a deviation from the design value of the spacing between the same servo read elements SR, so that by finding the difference between dPES(n) and dPES(n-3), the amount of deviation from the design value of the spacing between the servo read elements SR is offset, and only the value indicating the linearity of the servo pattern 52 is calculated.
• the linearity of the servo pattern 52 is expressed by the multiple ⁇ dPESs measured from the multiple dPES(n) and multiple dPES(n-3) corresponding to the multiple first positions 74 and the multiple second positions 76.
• step ST12 included in the linearity inspection method shown in FIG. 14 an index is obtained based on multiple ⁇ dPES.
• a method for obtaining an index based on multiple ⁇ dPES and a method for inspecting the linearity of the servo pattern 52 of the magnetic tape MT using the index.
• margins BS1 and BS2 are generated between the split data track DT_N and the data reproduction element DR.
• the margin BS1 is a margin generated on the first direction WD1 side
• the margin BS2 is a margin generated on the second direction WD2 side.
• the length of margin BS1 in the width direction WD and the length of margin BS2 in the width direction WD each correspond to 15% of pitch Tp.
• step ST12 included in the linearity inspection method shown in FIG. 14 the average value ⁇ and standard deviation ⁇ of multiple ⁇ dPESs are calculated from multiple ⁇ dPESs measured from adjacent servo pattern pairs.
• the standard deviation ⁇ represents the degree of linearity of the servo pattern 52.
• the linearity of the servo pattern 52 increases as the standard deviation ⁇ decreases. Therefore, in the servo pattern recording process described above, it is preferable that the servo pattern 52 is recorded on the magnetic tape MT so that the standard deviation ⁇ is as small as possible.
• Graph 78 is shown in FIG. 17.
• Graph 78 is a graph showing a normal distribution obtained from the mean value ⁇ and the standard deviation ⁇ . If the total area of the closed region enclosed by graph 78 is taken as 100%, then ⁇ dPES exists in the ⁇ section with a 68.3% probability, ⁇ dPES exists in the 2 ⁇ section with a 95.4% probability, and ⁇ dPES exists in the 3 ⁇ section with a 99.7% probability.
• step ST12 included in the linearity inspection method shown in FIG. 14 3 ⁇ is calculated from the standard deviation ⁇ .
• 3 ⁇ is an index showing the degree to which multiple ⁇ dPESs vary from the average value ⁇ .
• step ST14 included in the linearity inspection method shown in FIG. 14 it is determined whether or not the linearity judgment condition that "3 ⁇ is within 15% or less of the pitch Tp" is satisfied. If 3 ⁇ is within 15% or less of the pitch Tp, it can be expected that there is a 99.7% probability that the data reproduction element DR will be on-track with the divided data track DT_N.
• the linearity judgment conditions are satisfied, the linearity of the servo pattern 52 is judged to be within the acceptable range, and if the linearity judgment conditions are not satisfied, the linearity of the servo pattern 52 is judged to be outside the acceptable range. Then, the magnetic tape MT for which the linearity of the servo pattern 52 is judged to be within the acceptable range is adopted, and the magnetic tape MT for which the linearity of the servo pattern 52 is judged to be outside the acceptable range is not adopted.
• the servo pattern recording head WH is not replaced, and if the linearity of the servo pattern 52 is judged to be outside the acceptable range, the servo pattern recording head WH is replaced (for example, with a servo pattern recording head WH with improved linearity of the gap pattern G).
• the standard deviation ⁇ is an example of a "standard deviation” according to the technology disclosed herein.
• 3 ⁇ is an example of an "index” and a "value equivalent to three times the standard deviation of multiple PES difference gaps" according to the technology disclosed herein.
• FIG. 18 shows an example of a distribution of multiple dPESs obtained from a magnetic tape MT manufactured by a conventionally known technique without using linearity judgment conditions, and a distribution of multiple dPESs obtained from a magnetic tape MT manufactured through a process in which the linearity of the servo pattern 52 is determined to be within an acceptable range using the linearity judgment conditions.
• FIG. 19 shows an example of a distribution of multiple ⁇ dPESs obtained from a magnetic tape MT manufactured by a conventionally known technique without using linearity judgment conditions, and a distribution of multiple ⁇ dPESs obtained from a magnetic tape MT manufactured through a process in which the linearity of the servo pattern 52 is determined to be within an acceptable range using the linearity judgment conditions.
• the distribution of multiple dPESs obtained from a magnetic tape MT manufactured through a process in which the linearity of the servo pattern 52 is determined to be within an acceptable range using linearity judgment conditions is more coherent than the distribution of multiple dPESs obtained from a magnetic tape MT manufactured by a conventionally known technique without using linearity judgment conditions. In other words, there is less variation in the dPESs.
• the distribution of multiple ⁇ dPESs obtained from a magnetic tape MT manufactured through a process in which the linearity of the servo pattern 52 is determined to be within an acceptable range using linearity judgment conditions is more coherent than the distribution of multiple ⁇ dPESs obtained from a magnetic tape MT manufactured by conventionally known technology without using linearity judgment conditions. In other words, there is less variation in the ⁇ dPESs.
• FIG. 20A shows an example of a distribution of multiple ⁇ dPESs obtained under the first condition shown in Table 1.
• FIG. 20B shows an example of a distribution of multiple ⁇ dPESs obtained under the second condition shown in Table 2.
• the distribution of multiple ⁇ dPESs obtained under the first condition is more coherent than the distribution of multiple ⁇ dPESs obtained under the second condition. In other words, there is less variation in the ⁇ dPESs.
• Table 3 shows the 3 ⁇ values obtained when the magnetic tape MT was manufactured using the first servo pattern recording head (hereinafter also referred to as the "first head”), the second servo pattern recording head (hereinafter also referred to as the "second head”), and the third servo pattern recording head (hereinafter also referred to as the "third head”) under the first condition.
• Table 4 shows the 3 ⁇ values obtained when the magnetic tape MT was manufactured using the first head, the second head, and the third head under the second condition.
• the first head is a servo pattern recording head according to a conventionally known technology, and the opening of the gap pattern G is formed by MEMS processing.
• the second head is a servo pattern recording head WH in which the opening of the gap pattern G is formed by the above-mentioned second method (a method in which the entire width of the opening 66A shown in FIG. 13 is trimmed using an FIB or laser to form a groove 71, and the groove 71 is filled with a non-magnetic material 68).
• the third head is used in the MEMS processing performed on the opening of the gap pattern G of the first servo pattern recording head.
• the first recording module DWM1 forms a data track DT on a magnetic tape MT on which the linearity of all servo patterns 52 inspected by the linearity inspection method has been determined to be within an acceptable range (i.e., satisfying the linearity judgment conditions).
• a pair of first servo read elements SRa are positioned on adjacent servo bands SB in the width direction WD.
• one of the pair of first servo read elements SRa (hereinafter also referred to as “one first servo read element SRa”) is positioned on servo band SB3
• the other of the pair of first servo read elements SRa (hereinafter also referred to as “the other first servo read element SRa”) is positioned on servo band SB2.
• the magnetic head 28 is moved in the width direction WD so that one of the first servo read elements SRa is positioned on the path Pa1 of servo band SB3, and the other first servo read element SRa is positioned on the path Pa1 of servo band SB2, thereby positioning the first recording module DWM1 on the magnetic tape MT.
• each data recording element DW1 of the first recording module DWM1 performs a recording process.
• a divided data track DT_1 is formed on the magnetic tape MT by each data recording element DW1 of the first recording module DWM1.
• the magnetic tape MT is run in the reverse direction to return the first recording module DWM1 to the position where the formation of the split data track DT_1 began. Then, with the magnetic head 28 shifted by pitch Tp along the second direction WD2, the magnetic tape MT is run in the forward direction to perform recording processing on each data recording element DW1 of the first recording module DWM1. As a result, split data track DT_2 is formed on the magnetic tape MT by each data recording element DW1 of the first recording module DWM1.
• split data tracks DT_3 to DT_12 are formed sequentially by each data recording element DW1 of the first recording module DWM1.
• a data band DB2 including data tracks DT1 to DT8 is formed between servo bands SB2 and SB3 in the width direction WD.
• the first servo read element SRa is positioned sequentially on paths Pa1 to Pa12 that are set for each pitch Tp from the first direction WD1 to the second direction WD2 for the multiple servo patterns 52 included in the servo band SB.
• the servo patterns 52 in each servo band SB are read by the first servo read element SRa along each of paths Pa1 to Pa12, and servo control is performed according to the servo pattern signal obtained thereby.
• paths Pb1 to Pb12 are set for each pitch Tp in the multiple servo patterns 52 included in the servo band SB from the first direction WD1 side to the second direction WD2 side.
• Paths Pb1 to Pb12 correspond to paths Pa1 to Pa12, and each of paths Pb1 to Pb12 is set at a position shifted by a distance Dr toward the first direction WD1 side from each of paths Pa1 to Pa12.
• a pair of second servo read elements SRb are positioned on adjacent servo bands SB in the width direction WD.
• one of the pair of second servo read elements SRb (hereinafter also referred to as “one second servo read element SRb") is positioned on servo band SB3
• the other of the pair of second servo read elements SRb (hereinafter “the other second servo read element SRb") is positioned on servo band SB2.
• the magnetic head 28 is moved in the width direction WD so that one of the second servo read elements SRb is positioned on the path Pb1 of servo band SB3, and the other second servo read element SRb is positioned on the path Pb1 of servo band SB2, thereby positioning the playback module DRM on the magnetic tape MT.
• each data reproducing element DR of the reproducing module DRM performs a reproducing process.
• data is reproduced from the divided data track DT_1 by each data reproducing element DR of the reproducing module DRM on the magnetic tape MT.
• the magnetic tape MT is run in the reverse direction to return the playback module DRM to the position where the data from split data track DT_1 has been reproduced. Then, with the magnetic head 28 shifted by pitch Tp along the second direction WD2, the magnetic tape MT is run in the forward direction to cause each data reproduction element DR of the playback module DRM to perform a playback process. As a result, data is reproduced from the split data track DT_2 by each data reproduction element DR of the playback module DRM on the magnetic tape MT.
• one second servo read element SRb is located on the path Pb12 of servo band SB3, and the other second servo read element SRb is located on the path Pb12 of servo band SB2.
• the magnetic tape MT is run in the forward direction, and each data reproduction element DR of the reproduction module DRM is caused to perform a reproduction process.
• data is reproduced from the divided data track DT_12 on the magnetic tape MT by each data reproduction element DR of the reproduction module DRM.
• the divided data tracks DT_1 to DT_12 are overlapped in the second direction WD2 by shifting them by pitch Tp in sequence, but the technology disclosed herein is not limited to this.
• a plurality of divided data tracks DT_N may be formed by overlapping them in the first direction WD1 using the SMR method.
• the second recording module DWM2 is used.
• the pair of third servo read elements SRc is moved in sequence from path Pa12 to path Pa1, and the magnetic tape MT is run in the reverse direction, so that the pair of third servo read elements SRc is moved along path P and the servo pattern 52 is read by the pair of third servo read elements SRc.
• the magnetic head 28 is moved in the first direction WD1 according to the servo pattern signal obtained in this way, and the divided data tracks DT_12 to DT_1 are overlapped in sequence along the first direction WD1.
• data reproduction from the divided data tracks DT_1 to DT_12 is performed by each data reproduction element DR of the reproduction module DRM.
• Each of paths Pb1 to Pb12 is set at a position shifted by a distance Dr toward the second direction WD2 from each of paths Pa1 to Pa12, and when data reproduction from the divided data tracks DT_1 to DT_12 is performed, the second servo read element SRb reads the servo pattern 52 using paths Pb1 to Pb12, and servo control is performed according to the servo pattern signal obtained thereby.
• the linearity of the servo pattern 52 recorded on the magnetic tape MT in the servo pattern recording process is inspected using a linearity inspection method (see FIG. 14) (see step ST14 in FIG. 14).
• a linearity inspection method see FIG. 14
• multiple ⁇ dPES are measured to inspect the linearity of the servo pattern 52 (see FIG. 16).
• ⁇ dPES is the difference between dPES(n-3) and dPES(n) (see FIG. 16).
• dPES(n-3) is the difference in PES between a pair of corresponding first positions 74 in the width direction WD in a pair of servo patterns 52 recorded at corresponding positions in the width direction WD between a pair of servo bands SB adjacent in the width direction WD among a plurality of servo bands SB (see FIG. 16).
• dPES(n) is the difference in PES between a pair of second positions 76 shifted in the width direction WD from the pair of first positions 74 by an interval INT1 larger than the interval INT2 in the width direction WD in a pair of servo patterns 52 recorded at corresponding positions in the width direction WD between a pair of servo bands SB adjacent in the width direction WD among a plurality of servo bands SB (see FIG. 16).
• the multiple ⁇ dPES are obtained by measuring the ⁇ dPES at intervals INT2 along the width direction WD in a pair of servo patterns 52.
• the degree to which the multiple ⁇ dPES vary from the average value of the multiple ⁇ dPES is obtained as an index of the nonlinearity of the servo pattern 52 (see step ST12 shown in FIG. 14).
• the index of the nonlinearity of the servo pattern 52 is used to inspect the linearity of the servo pattern 52 of the magnetic tape MT (see step ST14 shown in FIG. 14).
• the index indicating the nonlinearity of the servo pattern 52 satisfies the condition that it is within 15% of the pitch Tp or less (see FIG. 17)
• the index indicating the nonlinearity of the servo pattern 52 does not satisfy the condition that it is within 15% of the pitch Tp or less, it is determined that the linearity of the servo pattern 52 of the magnetic tape MT is outside the allowable range (i.e., there is a problem with the linearity of the servo pattern 52 used for servo control).
• 15% of the pitch Tp corresponds to the length of the margin BS1 in the width direction WD and the length of the margin BS2 in the width direction WD (see FIG. 17).
• the fact that the index is within 15% of the pitch Tp means that more accurate servo control is possible compared to when the index exceeds 15% of the pitch Tp. This means that it is possible to form multiple split data tracks DT_N with high accuracy, and to track the data reproduction element DR with high accuracy relative to the split data tracks DT_N.
• an index is obtained for each of all adjacent servo band pairs included in the magnetic tape MT (for example, the pair of servo bands SB2 and SB3, and the pair of servo bands SB1 and SB2). Then, the magnetic tape MT is inspected using all of the indexes. Therefore, the magnetic tape MT can be inspected with higher accuracy than when the magnetic tape MT is inspected using an index obtained from only one adjacent servo band pair for a magnetic tape MT having three or more servo bands SB arranged in the width direction.
• the indices obtained for all adjacent servo band pairs included in the magnetic tape MT are each within 15% of the pitch Tp. Therefore, compared to a case where an index obtained from only one adjacent servo band pair for a magnetic tape MT having three or more servo bands SB arranged in the width direction is within 15% of the pitch Tp, this can contribute to improving the accuracy of recording data on the magnetic tape MT and the accuracy of reproducing data recorded on the magnetic tape MT.
• multiple divided data tracks DT_N are formed on the magnetic tape MT by recording data according to multiple servo patterns 52 using the SMR method on a magnetic tape MT that satisfies the condition that the index indicating the nonlinearity of the servo patterns 52 is within 15% of the pitch Tp (i.e., a magnetic tape MT in which the linearity of the servo patterns 52 is guaranteed to a high level). Therefore, the quality of the multiple divided data tracks DT_N formed by recording data on the magnetic tape MT using the SMR method can be guaranteed at a high level, and data can be reproduced from the multiple divided data tracks DT_N with high accuracy.
• the average value ⁇ and standard deviation ⁇ of the multiple ⁇ dPES are calculated. Then, as an index of the nonlinearity of the servo pattern 52, 3 ⁇ of the graph 78 (see FIG. 17) showing the normal distribution obtained from the average value ⁇ and the standard deviation ⁇ is used (see FIG. 17). In the closed region of 3 ⁇ in the graph 78, ⁇ dPES exists with a probability of 99.7%. In this embodiment, by determining whether or not the condition that 3 ⁇ is within 15% or less of the pitch Tp is satisfied, it becomes possible to adopt the magnetic tape MT on which only the multiple servo patterns 52 that satisfy the condition that 3 ⁇ is within 15% or less of the pitch Tp are recorded as the magnetic tape MT for shipment.
• the magnetic tape MT By adopting the magnetic tape MT with such a high level of guaranteed linearity of the servo pattern 52 as the magnetic tape MT for shipment, it is possible to contribute to improving the accuracy of recording data on the magnetic tape MT and the accuracy of reproducing the data recorded on the magnetic tape MT.
• the interval INT1 (see FIG. 16) used in measuring ⁇ dPES is a reference interval that is a natural number multiple of the interval INT2 (three times in the example shown in FIG. 16) and is the interval that is closest to the reference interval equivalent to half the difference between the length L1 (see FIG. 11) and the pitch Tp (see FIG. 10). Therefore, compared to a case in which the interval INT1 is determined independently of the length L1 and the pitch Tp, even if the multiple divided data tracks DT_N are highly dense, the data reproduction element DR can be accurately brought on-track on each of the multiple divided data tracks DT_N when reproducing data.
• the interval INT1 (see FIG. 16) used to measure ⁇ dPES (see FIG. 16) is an interval that is three times the interval INT2 (see FIG. 16). Therefore, it is possible to collect multiple ⁇ dPES (see FIG. 16) that are used to obtain an index showing the nonlinearity of the servo pattern 52 without excess or deficiency.
• the interval INT1 corresponds to the distance Dr by which the magnetic head 28 is moved in the width direction WD during tracking when reproducing data between divided data tracks DT_N adjacent in the width direction WD.
• the distance Dr is short, tracking when recording data and tracking when reproducing data are performed with the position of the first servo read element SRa used when recording data and the position of the second servo read element SRb used when reproducing data being close to each other. Therefore, even if there is distortion in the servo pattern signal, the effect of the distortion is kept relatively small. Conversely, when the distance Dr is long, the effect of the distortion becomes relatively large, and the position shift caused by the distortion becomes large.
• the difference between the position of the first servo read element SRa when the first data recording forms a split data track DT_1 and the position of the second servo read element SRb when the second data recording forms a split data track DT_2 corresponds to the pitch Tp.
• the effect of the misalignment during data reproduction will not be within the range of the effect of the misalignment during data recording, and the linearity of the servo pattern 52 will be significantly affected. This will lead to a deterioration in servo control performance.
• a spacing INT1 (see FIG. 16), which is a spacing equivalent to the distance Dr, is adopted that is greater than the pitch Tp.
• the servo pattern 52 is formed so that an index (e.g., 3 ⁇ ) indicating the degree of variation of the multiple ⁇ dPESs determined based on the spacing INT1 that is greater than the pitch Tp is within 15% of the pitch Tp. Therefore, compared to when the spacing INT1 is equal to or less than the pitch Tp, even if the multiple divided data tracks DT_N are highly dense, the data reproduction element DR can be accurately brought on-track on each of the multiple divided data tracks DT_N when reproducing data.
• the index (e.g., 3 ⁇ ) obtained for each adjacent servo band pair is set to 15% or less of the pitch Tp, but the technology disclosed herein is not limited to this.
• the index obtained for each adjacent servo band pair may be set to 10% or less of the pitch Tp, or the index obtained for each adjacent servo band pair may be set to 5% or less of the pitch Tp.
• 500 nm is given as an example of the length ⁇ 1, but if the index is set to 10% or less of the pitch Tp, the length ⁇ 1 can be lengthened to 400 nm, and if the index is set to 5% or less of the pitch Tp, the length ⁇ 1 can be lengthened to 450 nm.
• the length ⁇ 1 can be lengthened in this way, it is expected that the performance of reproducing data can be improved.
• PES caused by fluctuations in the width direction WD of the magnetic tape MT can also cause the data reproduction element DR to shift in position, but by keeping the index within 10% of the pitch Tp or within 5% of the pitch Tp, it is possible to create a design that has a higher tolerance for position shifts caused by PES.
• the split data tracks DT_1 to DT_12 are overlapped in the second direction WD2 by shifting them by pitch Tp in sequence, but the technology disclosed herein is not limited to this.
• a plurality of split data tracks DT_N may be formed by overlapping them in the first direction WD1 using the SMR method.
• the second recording module DWM2 is used.
• the pair of third servo read elements SRc are moved in sequence from path P12 to path P1, and the magnetic tape MT is run in the reverse direction, so that the pair of third servo read elements SRc are moved along path P and the servo pattern 52 is read by the pair of third servo read elements SRc.
• the magnetic head 28 is moved along the first direction WD1 according to the servo pattern signal obtained in this way, and the split data tracks DT_12 to DT_1 are overlapped in sequence along the first direction WD1. Data reproduction from the divided data tracks DT_1 to DT_12 is performed by each data reproduction element DR of the reproduction module DRM.
• the paths Pb1 to Pb12 used to read the servo pattern 52 when reproducing data are set a distance Dr closer to the first direction WD1 than the paths Pa1 to Pa12, but in the example shown in Figure 26, the paths Pb1 to Pb12 used to read the servo pattern 52 when reproducing data are set a distance Dr closer to the second direction WD2 than the paths Pa1 to Pa12.
• TDS is affected by temperature, humidity, the pressure at which the magnetic tape is wound around the reel, and deterioration over time, and it is known that if no measures are taken, TDS will become large and off-track (i.e., misalignment of the data recording/reproducing element DRW with respect to the divided data tracks DT_N in the data band DB) will occur when magnetic processing is performed on the data band DB.
• Off-track refers to a state in which the data recording and reproducing element DRW is not positioned on a specified divided data track DT_N among the divided data tracks DT1_1, DT1_2, DT1_3, DT1_4, ..., DT1_11, and DT1_12 included in the divided data track group DTG (i.e., a state in which the position of the specified divided data track DT_N is misaligned with the position of the data recording and reproducing element DRW in the width direction WD).
• the width of the magnetic tape MT may expand, and in this case, there is a risk of off-track. That is, if the width of the magnetic tape MT shrinks or expands over time, the position of the servo read element SR relative to the servo pattern 52 deviates in the width direction WD from the preset position determined by design (i.e., the preset position determined by design for each of the linear magnetized regions 54A1, 54A2, 54B1, and 54B2).
• the position of the servo read element SR relative to the servo pattern 52 deviates in the width direction WD from the preset position determined by design, the accuracy of servo control decreases, and the position of the data recording/reproducing element DRW deviates from the track in the data band DB (for example, a specified divided data track DT_N among the divided data tracks DT1_1, DT1_2, DT1_3, DT1_4, ..., DT1_11, and DT1_12).
• magnetic processing is not performed on the divided data track DT_N as originally planned.
• a method of reducing the effect of TDS is to adjust the width of the magnetic tape MT by adjusting the tension applied to the magnetic tape MT.
• the deformation in the width direction WD of the magnetic tape MT is too large, the off-track may not be eliminated even if the tension applied to the magnetic tape MT is adjusted.
• the tension applied to the magnetic tape MT is increased, the load on the magnetic tape MT increases, which may shorten the life of the magnetic tape MT.
• the tension applied to the magnetic tape MT is too weak, the contact state between the magnetic head 28 and the magnetic tape MT becomes unstable, making it difficult for the magnetic head 28 to perform magnetic processing on the magnetic tape MT.
• the first recording module DWM1 may be arranged at an angle with respect to the width direction WD along the surface 31 of the magnetic tape MT, centered on the rotation axis RA1.
• the playback module DRM may be arranged at an angle with respect to the width direction WD along the surface 31 of the magnetic tape MT, centered on the rotation axis RA2.
• the second recording module DWM2 may be arranged at an angle with respect to the width direction WD along the surface 31 of the magnetic tape MT, centered on the rotation axis RA3.
• the length L2 in the width direction WD of each of the data recording elements DW included in the recording module DWM is the same as the above-mentioned length L1 (see FIG. 11).
• the length ⁇ 2 in the width direction WD of each of the data reproducing elements DR included in the reproducing module DRM is the same as the above-mentioned length ⁇ 1 (see FIG. 1).
• the position of the first servo read element SRa in the width direction WD, the position of the second servo read element SRb in the width direction WD, and the position of the third servo read element SRc in the width direction WD are aligned.
• the attitudes of the first recording module DWM1, the playback module DRM, and the second recording module DWM2 in the width direction WD may be fixed or may be changed depending on the situation (e.g., the degree of deformation of the magnetic tape MT, etc.).
• a tilt mechanism (not shown) that operates under the control of the processing device 30 is used.
• the tilt mechanism is mechanically connected to the first recording module DWM1, the playback module DRM, and the second recording module DWM2.
• the degree of tilt of the first recording module DWM1, the playback module DRM, and the second recording module DWM2 in the width direction WD is adjusted by the tilt mechanism under the control of the processing device 30 depending on the situation.
• the degree of inclination of the first recording module DWM1, the playback module DRM, and the second recording module DWM2 in the width direction WD can be adjusted by rotating the first recording module DWM1 on surface 31 along surface 31 with rotation axis RA1 as the central axis, rotating the playback module DRM on surface 31 along surface 31 with rotation axis RA2 as the central axis, and rotating the second recording module DWM2 on surface 31 along surface 31 with rotation axis RA3 as the central axis.
• the first recording module DWM1, the playback module DRM, and the second recording module DWM2 are each controlled to rotate by a tilt mechanism, this is merely one example, and the entire magnetic head 28 may be rotated around the rotation axis RA2 by a single tilt mechanism.
• the positions at which the servo pattern 52 is read by each of the first servo read element SRa, the second servo read element SRb, and the third servo read element SRc may be adjusted according to an adjustment amount determined based on the certain deviation occurring in the width direction WD.
• the recording module DWM and the playback module DRM in an inclined position with respect to the width direction WD along the surface 31 of the magnetic tape MT, it is possible to prevent a decrease in the tracking accuracy of the magnetic head 28 on the magnetic tape MT caused by deformation of the magnetic tape MT. For example, it is possible to prevent the occurrence of a situation in which data cannot be recorded at the intended position or data cannot be reproduced from the intended position due to deformation of the magnetic tape MT.
• a magnetic tape system 10 in which the magnetic tape cartridge 12 can be freely inserted and removed from the magnetic tape drive 14 has been exemplified, but the technology of the present disclosure is not limited to this.
• the technology of the present disclosure can also be applied to a magnetic tape system in which at least one magnetic tape cartridge 12 is pre-loaded into the magnetic tape drive 14 (i.e., a magnetic tape system in which at least one magnetic tape cartridge 12 and the magnetic tape drive 14, or the magnetic tape MT and the magnetic tape drive 14, are integrated in advance (e.g., before data is recorded in the data band DB)).
• a magnetic tape system in which at least one magnetic tape cartridge 12 is pre-loaded into the magnetic tape drive 14 is an example of a "magnetic tape system" according to the technology of the present disclosure.
• a single magnetic head 28 is illustrated, but the technology disclosed herein is not limited to this.
• multiple magnetic heads 28 may be arranged on the magnetic tape MT.
• the angle between the linear magnetized region 54A1 and the servo read element SR differs from the angle between the linear magnetized region 54A2 and the servo read element SR in the linear magnetized region pair 54A.
• the angle between the servo read element SR and the linear magnetized region 54A1 is larger than the angle between the servo read element SR and the linear magnetized region 54A2, so the output of the servo pattern signal is small and the waveform is widened, resulting in variation in the servo pattern signal read by the servo read element SR across the servo band SB while the magnetic tape MT is running.
• a configuration in which the linear magnetization region 54A1 is parallel to the virtual straight line C1 and the linear magnetization region 54A2 is inclined with respect to the virtual straight line C1 i.e., a configuration in which only the linear magnetization region 54A2 is inclined
• the angle formed by the linear magnetization region 54A1 and the servo read element SR in the linear magnetization region pair 54A is different from the angle formed by the linear magnetization region 54A2 and the servo read element SR.
• a magnetic tape MT1 is used instead of the magnetic tape MT.
• the magnetic tape MT1 differs from the magnetic tape MT in that it has a frame 80 instead of the frame 50.
• the frame 80 is defined by a set of servo patterns 82.
• a plurality of servo patterns 82 are recorded in the servo band SB along the longitudinal direction LD of the magnetic tape MT1.
• the plurality of servo patterns 82 are arranged at regular intervals along the longitudinal direction LD of the magnetic tape MT, similar to the plurality of servo patterns 52 recorded on the magnetic tape MT.
• servo patterns 82A and 82B are shown as an example of a set of servo patterns 82 included in a frame 80.
• the servo patterns 82A and 82B are adjacent to each other along the longitudinal direction LD of the magnetic tape MT1, and within the frame 80, the servo pattern 82A is located on the upstream side in the forward direction, and the servo pattern 82B is located on the downstream side in the forward direction.
• the servo pattern 82 is made up of linear magnetization region pairs 84.
• the linear magnetization region pairs 84 are classified into linear magnetization region pairs 84A and linear magnetization region pairs 84B.
• the linear magnetization region pairs 84 are an example of a "linear magnetization region pair" according to the technology disclosed herein.
• the servo pattern 82A is made up of a pair of linear magnetized regions 84A.
• linear magnetized regions 84A1 and 84A2 are shown as an example of the pair of linear magnetized regions 84A.
• Each of the linear magnetized regions 84A1 and 84A2 is a linearly magnetized region.
• the linear magnetization regions 84A1 and 84A2 are inclined in opposite directions with respect to the virtual line C1.
• the linear magnetization region 84A1 is inclined in one direction with respect to the virtual line C1 (e.g., clockwise direction as viewed from the front side of the paper in FIG. 28).
• the linear magnetization region 84A2 is inclined in the other direction with respect to the virtual line C1 (e.g., counterclockwise direction as viewed from the front side of the paper in FIG. 28).
• the linear magnetization regions 84A1 and 84A2 are non-parallel to each other and are inclined at different angles with respect to the virtual line C1.
• the linear magnetization region 84A1 has a steeper inclination angle with respect to the virtual line C1 than the linear magnetization region 84A2.
• “steep” refers to, for example, that the angle of the linear magnetization region 84A1 with respect to the virtual line C1 is smaller than the angle of the linear magnetization region 84A2 with respect to the virtual line C1. Additionally, the total length of the linear magnetization region 84A1 is shorter than the total length of the linear magnetization region 84A2.
• linear magnetization region 84A1 is an example of a "first linear magnetization region” according to the technology disclosed herein
• linear magnetization region 84A2 is an example of a “second linear magnetization region” according to the technology disclosed herein
• virtual line C1 is an example of a "virtual line” according to the technology disclosed herein.
• the linear magnetization region 84A1 includes multiple magnetization lines 84A1a
• the linear magnetization region 84A2 includes multiple magnetization lines 84A2a.
• the number of magnetization lines 84A1a included in the linear magnetization region 84A1 is the same as the number of magnetization lines 84A2a included in the linear magnetization region 84A2.
• Linear magnetization region 84A1 is a collection of five magnetized straight lines, magnetization lines 84A1a
• linear magnetization region 84A2 is a collection of five magnetized straight lines, magnetization lines 84A2a.
• the positions of both ends of linear magnetization region 84A1 i.e., the positions of both ends of each of the five magnetization lines 84A1a
• the positions of both ends of linear magnetization region 84A2 i.e., the positions of both ends of each of the five magnetization lines 84A2a
• the positions of both ends of the five magnetization lines 84A1a and the positions of both ends of the five magnetization lines 84A2a are aligned, but this is merely an example, and it is sufficient that the positions of both ends of one or more of the five magnetization lines 84A1a and the positions of both ends of one or more of the five magnetization lines 84A2a are aligned.
• the concept of "aligned” includes not only the meaning of being completely aligned, but also the meaning of "aligned” including an error that is generally acceptable in the technical field to which the technology of the present disclosure belongs and does not go against the spirit of the technology of the present disclosure.
• the servo pattern 82B is made up of a pair of linear magnetization regions 84B.
• linear magnetization regions 84B1 and 84B2 are shown as an example of the pair of linear magnetization regions 84B.
• Each of the linear magnetization regions 84B1 and 84B2 is a linearly magnetized region.
• the linear magnetization regions 84B1 and 84B2 are inclined in opposite directions with respect to the virtual line C2.
• the linear magnetization region 84B1 is inclined in one direction with respect to the virtual line C2 (e.g., clockwise direction as viewed from the front side of the paper in FIG. 28).
• the linear magnetization region 84B2 is inclined in the other direction with respect to the virtual line C2 (e.g., counterclockwise direction as viewed from the front side of the paper in FIG. 28).
• the linear magnetization regions 84B1 and 84B2 are non-parallel to each other and inclined at different angles with respect to the virtual line C2.
• the linear magnetization region 84B1 is a linear magnetization
• the inclination angle of linear magnetization region 84B1 relative to virtual line C2 is steeper than that of region 84B2.
• “steep” means, for example, that the angle of linear magnetization region 84B1 relative to virtual line C2 is smaller than the angle of linear magnetization region 84B2 relative to virtual line C2.
• the total length of linear magnetization region 84B1 is shorter than the total length of linear magnetization region 84B2.
• linear magnetization region 84B1 is an example of a "first linear magnetization region” according to the technology disclosed herein
• linear magnetization region 84B2 is an example of a “second linear magnetization region” according to the technology disclosed herein
• virtual line C2 is an example of a "virtual line” according to the technology disclosed herein.
• the linear magnetization region 84B1 includes multiple magnetization lines 84B1a
• the linear magnetization region 84B2 includes multiple magnetization lines 84B2a.
• the number of magnetization lines 84B1a included in the linear magnetization region 84B1 is the same as the number of magnetization lines 84B2a included in the linear magnetization region 84B2.
• the total number of magnetization lines 84B1a and 84B2a included in servo pattern 82B is different from the total number of magnetization lines 84A1a and 84A2a included in servo pattern 82A.
• the total number of magnetization lines 84A1a and 84A2a included in servo pattern 82A is 10
• the total number of magnetization lines 84B1a and 84B2a included in servo pattern 82B is 8.
• Linear magnetization region 84B1 is a collection of four magnetized straight lines, magnetization lines 84B1a
• linear magnetization region 84B2 is a collection of four magnetized straight lines, magnetization lines 84B2a.
• the positions of both ends of linear magnetization region 84B1 i.e., the positions of both ends of each of the four magnetization lines 84B1a
• the positions of both ends of linear magnetization region 84B2 i.e., the positions of both ends of each of the four magnetization lines 84B2a
• a set of five magnetized magnetized straight lines 84A1a is given as an example of the linear magnetization region 84A1
• a set of five magnetized magnetized straight lines 84A2a is given as an example of the linear magnetization region 84A2
• the technology of the present disclosure is not limited to this.
• a set of four magnetized magnetized straight lines 84B1a is given as an example of the linear magnetization region 84B1
• a set of four magnetized magnetized straight lines 84B2a is given as an example of the linear magnetization region 84B2, but the technology of the present disclosure is not limited to this.
• the linear magnetization region 84A1 is a number of magnetization straight lines 84A1a that contribute to identifying the position of the magnetic head 28 on the magnetic tape MT1
• the linear magnetization region 84A2 is a number of magnetization straight lines 84A2a that contribute to identifying the position of the magnetic head 28 on the magnetic tape MT1
• the technology of the present disclosure is valid.
• the linear magnetization region 84B1 is a number of magnetization lines 84B1a that contribute to determining the position of the magnetic head 28 on the magnetic tape MT1
• the linear magnetization region 84B2 is a number of magnetization lines 84B2a that contribute to determining the position of the magnetic head 28 on the magnetic tape MT1
• the geometric characteristics of the linear magnetized region pair 84A on the magnetic tape MT1 will be described with reference to FIG. 29. Note that here, the geometric characteristics refer to generally recognized geometric characteristics such as length, shape, orientation, and/or position.
• the geometric characteristics of the linear magnetized region pair 84A on the magnetic tape MT1 can be expressed using a virtual linear region pair 86.
• the virtual linear region pair 86 consists of a virtual linear region 86A and a virtual linear region 86B.
• the geometric characteristics of the linear magnetized region pair 84A on the magnetic tape MT1 correspond to the geometric characteristics based on the virtual linear region pair 86 when the entire virtual linear region pair 86 is tilted with respect to the virtual line C1 by tilting the symmetry axis SA1 of the virtual linear region 86A and the virtual linear region 86B, which are tilted line-symmetrically with respect to the virtual line C1, with respect to the virtual line C1.
• the virtual linear region pair 86 is a virtual linear magnetization region pair having the same geometric characteristics as the linear magnetization region pair 54A shown in FIG. 6.
• the virtual linear region pair 86 is a virtual magnetization region used for convenience in explaining the geometric characteristics of the linear magnetization region pair 86A on the magnetic tape MT1, and is not an actual magnetization region.
• the virtual linear region 86A has the same geometric characteristics as the linear magnetization region 54A1 shown in FIG. 6, and is made up of five virtual straight lines 86A1 corresponding to the five magnetization straight lines 54A1a shown in FIG. 6.
• the virtual linear region 86B has the same geometric characteristics as the linear magnetization region 54B1 shown in FIG. 6, and is made up of five virtual straight lines 86B1 corresponding to the five magnetization straight lines 54A2a shown in FIG. 6.
• the virtual linear region pair 86 has a center O1.
• the center O1 is the center of a line segment 88 that connects the center of the straight line 86A1 that is located most upstream in the forward direction among the five straight lines 86A1, and the center of the straight line 86B1 that is located most upstream in the forward direction among the five straight lines 86B1.
• the virtual linear region pair 86 has the same geometric characteristics as the linear magnetization region pair 54A shown in FIG. 6, the virtual linear region 86A and the virtual linear region 86B are tilted in line symmetry with respect to the virtual straight line C1.
• the servo read element SR shown in FIG. 27 reads the virtual linear region pair 86 when the entire virtual linear region pair 86 is tilted with respect to the virtual straight line C1 by tilting the symmetry axis SA1 of the virtual linear regions 86A and 86B by an angle a (for example, 10 degrees) with respect to the virtual straight line C1 with the center O1 as the rotation axis.
• each of the virtual linear regions 86A and 86B the missing portions are supplemented and unnecessary portions are removed. This aligns the positions of both ends of the virtual linear region 86A (i.e., the positions of both ends of each of the five straight lines 86A1) with the positions of both ends of the virtual linear region 86B (i.e., the positions of both ends of each of the five straight lines 86B1) in the width direction WD.
• the geometric characteristics of the virtual linear region pair 86 thus obtained correspond to the geometric characteristics of the actual servo pattern 82A. That is, in the servo band SB, a linear magnetization region pair 84A having geometric characteristics equivalent to the geometric characteristics of the virtual linear region pair 86 obtained by aligning the positions of both ends of the virtual linear region 86A and the positions of both ends of the virtual linear region 86B in the width direction WD is recorded.
• the linear magnetization region pair 84B differs from the linear magnetization region pair 84A only in that it has four magnetization lines 84B1a instead of five magnetization lines 84A1a, and four magnetization lines 84B2a instead of five magnetization lines 84A2a. Therefore, in the servo band SB, a linear magnetization region pair 84B with geometric characteristics equivalent to the geometric characteristics of a virtual linear region pair (not shown) obtained by aligning the positions of both ends of each of the four lines 86A1 and the positions of both ends of each of the four lines 86B1 in the width direction WD is recorded.
• a magnetic tape MT1 is used on which a servo pattern 82A consisting of a pair of linear magnetized regions 84A and a servo pattern 82B consisting of a pair of linear magnetized regions 84B are formed.
• This contributes to improving the accuracy of recording data on the magnetic tape MT1 and the accuracy of playing back data recorded on the magnetic tape MT1, even when data is recorded on the magnetic tape MT1 or played back from the magnetic tape MT1 using a magnetic head 28 skewed above the magnetic tape MT1 to reduce the effects of TDS.
• the linearity of the servo pattern 82 is guaranteed by performing a linearity inspection method (see FIG. 14) on the magnetic tape MT1 in the same manner as in the above embodiment. Therefore, the same effect as in the above embodiment can be obtained.
• the formation of the multiple servo bands SB, each including multiple servo patterns 82 along the longitudinal direction LD, is performed in the same manner as in the above embodiment using a skew-compatible servo pattern recording head (not shown) instead of the servo pattern recording head WH.
• the skew-compatible servo pattern recording head refers to a servo pattern recording head in which multiple gap patterns having geometric characteristics equivalent to the geometric characteristics of a straight line 86A1 located at the most upstream side in the forward direction in the virtual linear region 86A and a straight line 86B1 located at the most upstream side in the forward direction in the virtual linear region 86B are formed at equal intervals along the direction WD3 (see FIG. 13).
• a and/or B is synonymous with “at least one of A and B.”
• a and/or B means that it may be just A, or just B, or a combination of A and B.
• the same concept as “A and/or B” is also applied when three or more things are expressed by linking them with “and/or.”

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