Magnetic tape, magnetic tape cartridge, magnetic tape system, inspection method, and method for manufacturing magnetic tape

Abstract

According to the present invention, an index indicating the nonlinearity of a servo pattern is within 15% of a track pitch. The track pitch is the pitch between tracks. The index indicates the degree of variation of a plurality of distance differences from the average value of the plurality of distance differences. The distance difference is the difference between the distance between a pair of first positions, corresponding in the width direction, in the pair of servo patterns and the distance between a pair of second positions, shifted from the pair of first positions by a first predetermined interval in the width direction, in the pair of servo patterns. The plurality of distance differences are obtained by measuring the distance differences in the pair of servo patterns at second predetermined intervals along the width direction. The first predetermined interval is greater than the second predetermined interval.

Description

Magnetic tape, magnetic tape cartridge, magnetic tape system, inspection method, and magnetic tape manufacturing method

[0001] The technology of the present disclosure relates to a magnetic tape, a magnetic tape cartridge, a magnetic tape system, an inspection method, and a method for manufacturing a magnetic tape.

[0002] Japanese Patent Application Laid-Open Publication No. 2022-057517 discloses a magnetic tape having a timing-based servo pattern, which is used in a magnetic tape device having a total number of data tracks of 8,705 or more when converted into a 1 / 2-inch wide magnetic tape, and the ΔPNL of the timing-based servo pattern is 10.0% or less of the track pitch, and the ΔPNL indicates the amount of deviation from the linearity of the timing-based servo pattern.

[0003] Japanese Patent Application Laid-Open Publication No. 2019-046521 discloses a recording device equipped with a recording unit that records information regarding 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.

[0004] US Patent Application Publication No. 2019 / 0279673 discloses a shingled recording method as a method for recording data on magnetic tape.

[0005] One embodiment of the technology of the present disclosure 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.

[0006] A first aspect of the technique of the present disclosure is a magnetic tape on which a plurality of servo bands, each having a plurality of servo patterns recorded along its longitudinal direction, are arranged in the width direction, the magnetic tape having an index indicating nonlinearity of the servo patterns being within 15% of the track pitch, the track pitch being the pitch between a plurality of tracks formed by recording data on the magnetic tape by a recording element in accordance with signals obtained from the plurality of servo patterns, the index indicating the degree to which the plurality of PES difference gaps vary from an average value of the plurality of 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 that straddle one or more servo bands in the width direction among the plurality of 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 that are shifted in the width direction from the pair of first positions by a first predetermined interval, the plurality of PES difference gaps being obtained by measuring the PES difference gap in the pair of servo patterns at second predetermined intervals along the width direction, the first predetermined intervals being greater than the second predetermined intervals.

[0007] A second aspect of the technique of the present disclosure is the magnetic tape according to the first aspect, in which the plurality of tracks are formed by recording data on the magnetic tape using a recording element in an SMR system.

[0008] A third aspect of the technique of the present disclosure is the magnetic tape according to the first or second aspect, in which the index is a value equivalent to three times the standard deviation of a plurality of PES difference gaps.

[0009] A fourth aspect of the technology of the present disclosure 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 an interval that most closely approximates the reference interval that corresponds 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.

[0010] A fifth aspect of the technology of the present disclosure is a magnetic tape according to any one of the first to third aspects, in which the first predetermined interval is an interval equivalent to a natural number multiple of the second predetermined interval that is two or more.

[0011] A sixth aspect of the technique of the present disclosure is the magnetic tape according to any one of the first to sixth aspects, in which the first predetermined interval is greater than the track pitch.

[0012] A seventh aspect of the technique of the present disclosure is the magnetic tape according to any one of the first to sixth aspects, in which the indicator is within 10% or less of the track pitch.

[0013] An eighth aspect of the technique of the present disclosure is the magnetic tape according to any one of the first to seventh aspects, in which the indicator is within 5% or less of the track pitch.

[0014] A ninth aspect of the technology of the present disclosure is a magnetic tape according to any one of the first to eighth aspects, in which the magnetic tape has four or more servo bands arranged in the width direction as multiple servo bands, and an index is obtained for each pair of servo bands that spans one or more servo bands in the width direction.

[0015] A tenth aspect of the technology of the present disclosure is a magnetic tape according to the ninth aspect, in which an index is obtained for each of all pairs of servo bands that straddle one or more servo bands in the width direction, except for pairs of servo bands that are not used for recording and / or reproducing data.

[0016] An eleventh aspect of the technology of the present disclosure is a magnetic tape according to the ninth or tenth aspect, in which each of the indicators obtained for each of a pair of servo bands is within 15% of the track pitch.

[0017] A twelfth aspect of the technology of the present disclosure is a magnetic tape according to the ninth or tenth aspect, in which each of the indicators obtained for each of a pair of servo bands is within 10% of the track pitch.

[0018] A thirteenth aspect of the disclosed technology is a magnetic tape according to the ninth or tenth aspect, in which each of the indicators obtained for each of a pair of servo bands is within 5% of the track pitch.

[0019] In a fourteenth aspect of the technique of the present disclosure, the servo pattern is at least one pair of linear magnetization regions, the pair of linear magnetization regions being a first linearly magnetized region and a second linearly magnetized 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 being inclined in opposite directions with respect to the second linear magnetization region.

[0020] The magnetic tape according to any one of the first to thirteenth aspects, wherein the inclination angle with respect to the imaginary line is steeper than that of the region.

[0021] A fifteenth aspect of the present disclosure is the magnetic tape according to any one of the first to fourteenth aspects, wherein the magnetic tape has a base film, and the base film is made of polyethylene terephthalate, polyethylene naphthalate, or polyamide.

[0022] A sixteenth aspect of the technology of the present disclosure is a magnetic tape cartridge comprising a magnetic tape according to any one of the first to fifteenth aspects and a case in which the magnetic tape is housed.

[0023] A seventeenth aspect of the technology of the present disclosure is a magnetic tape system comprising a magnetic tape according to any one of the first to fifteenth aspects and a magnetic head for recording data on the magnetic tape and / or reproducing data recorded on the magnetic tape.

[0024] An eighteenth aspect of the technology of the present disclosure is an inspection method that includes obtaining an indicator from a magnetic tape according to any one of the first to fifteenth aspects, and inspecting the magnetic tape using the indicator.

[0025] A nineteenth aspect of the technique of the present disclosure is the inspection method according to the eighteenth aspect, in which inspecting the magnetic tape includes inspecting the linearity of the servo pattern using the indicator.

[0026] A twentieth aspect of the technique of the present disclosure is a method for manufacturing a magnetic tape having a plurality of servo bands arranged in a width direction, each having a plurality of servo patterns recorded along a first longitudinal direction, the method including: installing a servo write head having a facing surface that faces a recording surface of the magnetic tape when recording the 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 using the servo write head installed in this orientation to record the plurality of servo patterns on the recording surface along the first longitudinal direction, thereby forming the plurality of servo bands on the recording surface, wherein an index indicating nonlinearity of the servo patterns is within 15% of the track pitch, and the track pitch is set to be equal to or smaller than the number of servo patterns. a PES difference gap between a plurality of tracks formed by recording data on a magnetic tape by a recording element in accordance with a signal obtained from a magnetic recording element, the index indicating a degree of variation of the plurality of PES difference gaps from an average value of the plurality of 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 corresponding first positions in the width direction, in a pair of servo patterns recorded at corresponding positions in the width direction between a pair of servo bands that straddle one or more servo bands in the width direction among the plurality of 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 that are shifted a first predetermined interval in the width direction from the pair of first positions, the plurality of PES difference gaps being obtained by measuring the PES difference gap in the pair of servo patterns at second predetermined intervals along the width direction, and the first predetermined intervals being greater than the second predetermined intervals.

[0027] FIG. 1 is a conceptual diagram showing an example of the configuration of a magnetic tape system. FIG. 2 is a schematic perspective view showing an example of the appearance of a magnetic tape cartridge. FIG. 3 is a schematic configuration diagram showing an example of the hardware configuration of a magnetic tape drive. FIG. 4 is a schematic perspective view showing an example of a mode in which a magnetic field is emitted from the underside of a magnetic tape cartridge by a non-contact read / write device. FIG. 5 is a conceptual diagram showing an example of the correlation between a processing device, a moving mechanism, and a magnetic head. FIG. 6 is a conceptual diagram showing an example of a mode in which a magnetic head is positioned on a magnetic tape, observed from the surface side of the magnetic tape. FIG. 7 is a conceptual diagram showing an example of the configuration of data bands formed on the surface of a magnetic tape. FIG. 8 is a conceptual diagram showing an example of a correspondence between a data recording / reproducing element and a data track. FIG. 9 is a conceptual diagram showing an example of a mode in which a servo pattern is read by a servo read element. FIG. 10 is a conceptual diagram showing an example of a mode in which data is recorded on the surface of the magnetic tape by an SMR method on the upper side of the width direction of the surface of the magnetic tape (between servo band SB2 and servo band SB3 on the surface of the magnetic tape), whereby a plurality of divided data tracks are overlapped and shifted along a second direction. FIG. 1 is a conceptual diagram showing an example of a configuration of a data track formed by overlapping a plurality of divided data tracks shifted along a second direction by recording data on the surface of a magnetic tape by an SMR method on the lower side of the surface of the magnetic tape in the width direction (between servo band SB1 and servo band SB2 on the surface of the magnetic tape). FIG. 1 is a conceptual diagram showing an example of a configuration of a first recording module, a reproducing module, and a second recording module provided on a magnetic head. FIG. 1 is a conceptual diagram showing an example of a configuration of a servo writer. FIG. 1 is a conceptual diagram showing an example of a configuration of a servo pattern recording head and a pulse signal generator included in a servo writer. FIG. 2 is a flowchart showing an example of the flow of a linearity inspection method used in an inspection process included in a manufacturing method of a magnetic tape. FIG. 2 is a conceptual diagram showing an example of a configuration of a servo band formed on a magnetic tape. FIG. 3 is a conceptual diagram showing an example of a configuration in which a plurality of ΔdPESs are measured from servo pattern pairs.1 is a graph showing an example of a distribution of multiple dPESs obtained from a magnetic tape manufactured by a conventionally known technique without using linearity judgment conditions, and a distribution of multiple dPESs obtained from a magnetic tape manufactured through a process in which the linearity of the servo pattern is determined to be within an acceptable range using the linearity judgment conditions. FIG. 1 is a graph showing an example of a distribution of multiple ΔdPESs obtained from a magnetic tape manufactured by a conventionally known technique without using linearity judgment conditions, and a distribution of multiple ΔdPESs obtained from a magnetic tape manufactured through a process in which the linearity of the servo pattern is determined to be within an acceptable range using the linearity judgment conditions. FIG. 2 is a graph showing an example of a distribution of multiple ΔdPESs obtained under the first condition shown in Table 1. FIG. 3 is a graph showing an example of a distribution of multiple ΔdPESs obtained under the second condition shown in Table 2. FIG. 4 is a conceptual diagram showing an example of an aspect of a first recording module when a first servo read element reads a servo pattern by passing through a path closest to one end of the width of the magnetic tape among a plurality of paths used when recording data. FIG. 5 is a conceptual diagram showing an example of an aspect when one divided data track is formed by each of a plurality of first data recording elements of the first recording module. FIG. 1 is a conceptual diagram showing an example of a mode of a data track formed by overlapping a plurality of divided data tracks with a shift along a second direction by each of a plurality of first data recording elements of a first recording module. FIG. 1 is a conceptual diagram showing an example of a mode of a reproducing module when a data reproducing element reproduces data from a divided data track that is located at the most one end side in the width of a magnetic tape among a plurality of divided data tracks that form one data track. FIG. 1 is a conceptual diagram showing an example of a mode of a reproducing module when a data reproducing element reproduces data from a divided data track that is located at the most other end side in the width of a magnetic tape among a plurality of divided data tracks that form one data track. FIG. 1 is a conceptual diagram showing an example of a mode of a data track formed by overlapping a plurality of divided data tracks with a shift along a first direction by each of a plurality of data recording elements of a recording module. FIG. 1 is a conceptual diagram showing a modified configuration of a magnetic head. FIG. 1 is a conceptual diagram showing a modified configuration of a servo pattern. FIG. 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.A conceptual diagram showing an example of how magnetic processing is performed on a magnetic tape having a greater number of data bands and servo bands than the magnetic tape shown in Figure 6 by a magnetic head having a greater number of servo read elements and a greater number of data recording / reproducing elements than the magnetic head shown in Figure 6.

[0028] Hereinafter, examples of embodiments of a magnetic tape, a magnetic tape cartridge, a magnetic tape system, an inspection method, and a magnetic tape manufacturing method according to the techniques of the present disclosure will be described with reference to the accompanying drawings.

[0029] First, the terms used in the following description will be explained.

[0030] 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". 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".

[0031] 1, as an example, 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.

[0032] 1, in order to facilitate understanding of the technology of the present disclosure, the magnetic tape cartridge 12 and the magnetic tape drive 14 are each shown individually, 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.

[0033] For example, a magnetic tape cartridge 12 is selected from a 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 from a plurality of magnetic tape drives 14 .

[0034] In this embodiment, the magnetic tape system 10 is an example of a "magnetic tape system" according to the technology of the present disclosure. Also, in this embodiment, the magnetic tape MT is an example of a "magnetic tape" according to the technology of the present disclosure. Also, in this embodiment, the magnetic tape cartridge 12 is an example of a "magnetic tape cartridge" according to the technology of the present disclosure.

[0035] Next, an example of the configuration of the magnetic tape cartridge 12 will be described with reference to Figures 2 to 4. For convenience of explanation, in the following description, the loading direction of the magnetic tape cartridge 12 into the magnetic tape drive 14 is indicated by arrow A in Figures 2 to 4, the direction of arrow A is the front direction of the magnetic tape cartridge 12, and the front side of the magnetic tape cartridge 12 is the front side of the magnetic tape cartridge 12. In the following description of the structure, "front" refers to the front side of the magnetic tape cartridge 12.

[0036] 2 to 4, for convenience of explanation, the direction of arrow B, which is orthogonal to the direction of arrow A, is defined as the right direction, and the right side of the magnetic tape cartridge 12 is defined as the right side of the magnetic tape cartridge 12. In the following description of the structure, "right" refers to the right side of the magnetic tape cartridge 12.

[0037] 2 to 4, for convenience of explanation, the direction opposite to the direction of arrow B is referred to as the left direction, and the left side of the magnetic tape cartridge 12 is referred to as the left side of the magnetic tape cartridge 12. In the following description of the structure, "left" refers to the left side of the magnetic tape cartridge 12.

[0038] 2 to 4, for convenience of explanation, the direction perpendicular to the directions of arrows A and B is indicated by arrow C, the direction of arrow C is the upward direction of the magnetic tape cartridge 12, and the upward side of the magnetic tape cartridge 12 is the upper side of the magnetic tape cartridge 12. In the explanation of the structure shown below, "upper" refers to the upper side of the magnetic tape cartridge 12.

[0039] 2 to 4, for convenience of explanation, the direction opposite to the front direction of the magnetic tape cartridge 12 is referred to as the rear direction of the magnetic tape cartridge 12, and the rear side of the magnetic tape cartridge 12 is referred to as the rear side of the magnetic tape cartridge 12. In the following description of the structure, "rear" refers to the rear side of the magnetic tape cartridge 12.

[0040] 2 to 4, for convenience of explanation, the direction opposite to the upper direction of the magnetic tape cartridge 12 is referred to as the lower direction of the magnetic tape cartridge 12, and the lower side of the magnetic tape cartridge 12 is referred to as the lower side of the magnetic tape cartridge 12. In the following description of the structure, "lower" refers to the lower side of the magnetic tape cartridge 12.

[0041] 2, the magnetic tape cartridge 12 has a generally rectangular shape in plan view and includes a box-shaped case 16. The magnetic tape MT is housed in the case 16. The case 16 is an example of a "case" according to the technology of the present disclosure.

[0042] A supply reel 22 is rotatably housed inside the case 16. A 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 through the opening 16A1.

[0043] The case 16 accommodates a cartridge memory 24 as a storage medium other than the magnetic tape MT. An IC chip having an NVM is mounted on the cartridge memory 24. In this embodiment, 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 contactless manner.

[0044] The cartridge memory 24 stores management information 15 for managing 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.

[0045] The magnetic tape MT has a base film, which is a non-magnetic support, and a magnetic layer containing ferromagnetic powder. Examples of the base film (hereinafter also referred to simply as "support") include known materials such as biaxially oriented polyethylene terephthalate, polyethylene naphthalate, polyamide, polyamideimide, or aromatic polyamide. Examples of the ferromagnetic powder include ferromagnetic powders commonly used in the magnetic layers of various magnetic recording media. A preferred example of the ferromagnetic powder is hexagonal ferrite powder. Examples of the hexagonal ferrite powder include hexagonal strontium ferrite powder and hexagonal barium ferrite powder.

[0046] In one embodiment, the base film of the magnetic tape MT can be an aromatic polyester support. In this disclosure and this specification, "aromatic polyester" refers to a resin containing an aromatic backbone and multiple ester bonds, and "aromatic polyester support" refers to a support containing at least one layer of aromatic polyester film. "Aromatic polyester film" refers to a film in which the component that constitutes the film most predominantly by mass is an aromatic polyester. In this disclosure and this specification, "aromatic polyester support" includes supports in which all the resin films contained in the support are aromatic polyester films, as well as supports containing aromatic polyester films and other resin films. Specific forms of aromatic polyester support include a single-layer aromatic polyester film, a laminate film of two or more aromatic polyester film layers with the same constituent components, a laminate film of two or more aromatic polyester film layers with different constituent components, and a laminate film containing one or more aromatic polyester film layers and one or more resin films other than aromatic polyester. An adhesive layer or the like may optionally be included between two adjacent layers in the laminate film. Furthermore, the aromatic polyester support may optionally include a metal film and / or metal oxide film formed by vapor deposition or the like on one or both surfaces. The same applies to the "polyethylene terephthalate support" and the "polyethylene naphthalate support" in this disclosure and this specification.

[0047] The aromatic ring contained in the aromatic skeleton of the aromatic polyester is not particularly limited. Specific examples of aromatic rings include a benzene ring and a naphthalene ring. For example, polyethylene terephthalate (PET) is a polyester containing a benzene ring and is a resin obtained by polycondensation of ethylene glycol with terephthalic acid and / or dimethyl terephthalate. The term "polyethylene terephthalate" in this disclosure and this specification also includes structures having one or more other components (e.g., copolymerized components, components introduced into the terminal or side chain) in addition to the above components. Polyethylene naphthalate (PEN) is a polyester containing a naphthalene ring and is a resin obtained by performing an esterification reaction between dimethyl 2,6-naphthalenedicarboxylate and ethylene glycol, followed by a transesterification reaction and a polycondensation reaction. The term "polyethylene naphthalate" in this disclosure and this specification also includes structures having one or more other components (e.g., copolymerized components, components introduced into the terminal or side chain) in addition to the above components.

[0048] In one embodiment, the base film of the magnetic tape MT can be an aromatic polyamide support. In this disclosure and this specification, "aromatic polyamide" refers to a resin containing an aromatic backbone and multiple amide bonds. The aromatic ring contained in the aromatic backbone of the aromatic polyamide is not particularly limited. Specific examples of aromatic rings include benzene rings. An "aromatic polyamide support" refers to a support containing at least one layer of aromatic polyamide film. An "aromatic polyamide film" refers to a film in which aromatic polyamide is the predominant component by mass among the components constituting the film. In this disclosure and this specification, "aromatic polyamide support" includes support in which all resin films contained in the support are aromatic polyamide films and support containing an aromatic polyamide film and another resin film. Specific forms of aromatic polyamide support include a single-layer aromatic polyamide film, a laminate film of two or more layers of aromatic polyamide film with the same constituent components, a laminate film of two or more layers of aromatic polyamide film with different constituent components, and a laminate film containing one or more layers of aromatic polyamide film and one or more layers of resin film other than aromatic polyamide. The laminated film may optionally contain an adhesive layer or the like between two adjacent layers. The aromatic polyamide support may also optionally contain a metal film and / or a metal oxide film formed by vapor deposition or the like on one or both surfaces.

[0049] The base film may be a biaxially stretched film, and may be a film that has been subjected to corona discharge, plasma treatment, easy-adhesion treatment, heat treatment, or the like.

[0050] An example of an index of the physical properties of a base film is moisture content. In the present invention and this specification, the moisture content of a base film is a value determined by the following method. The moisture contents shown in the tables below are values ​​determined by the following method. A sample piece (e.g., a sample piece having a mass of several grams) cut out from the base film to be measured for moisture content is dried to a constant mass in a vacuum dryer at a temperature of 180°C and a pressure of 100 Pa (Pascal) or less. The mass of the sample piece dried in this manner is designated as W1. W1 is a value measured in a measurement environment at a temperature of 23°C and a relative humidity of 50% within 30 seconds after removal from the vacuum dryer. Next, W2 is the mass of the sample piece after placing it in an environment at a temperature of 25°C and a relative humidity of 75% for 48 hours. W2 is a value measured in a measurement environment at a temperature of 23°C and a relative humidity of 50% within 30 seconds after removal from the environment. The moisture content is calculated using the following formula.

[0051] Moisture content (%) = [(W2-W1) / W1] x 100

[0052] For example, after removing the magnetic layer and other portions of the magnetic tape MT other than the base film by a known method (for example, film removal using an organic solvent), the moisture content of the base film can be determined by the above method.

[0053] In one embodiment, the base film of the magnetic tape MT preferably has a moisture content of 2.0% or less, more preferably 1.8% or less, even more preferably 1.6% or less, even more preferably 1.4% or less, even more preferably 1.2% or less, and even more preferably 1.0% or less. The moisture content of the base film of the magnetic tape MT can be 0%, 0% or more, more than 0%, or 0.1% or more. Using a base film with a low moisture content can contribute to increasing the media life value of each magnetic tape cartridge 12. This is primarily because using a base film with a low moisture content is believed to contribute to reducing the value of "B" determined by the method described above.

[0054] Young's modulus can also be mentioned as an index of the physical properties of the base film. In the present invention and this specification, the Young's modulus of the base film is a value measured by the following method in a measurement environment at a temperature of 23°C and a relative humidity of 50%. The Young's moduli shown in the table below are values ​​determined by the following method using a Tensilon manufactured by Toyo Baldwin Co., Ltd. as a universal tensile testing device.

[0055] A sample piece cut from the base film to be measured is pulled using a universal tensile testing machine under conditions of a chuck distance of 100 mm, a pulling speed of 10 mm / min, and a chart speed of 500 mm / min. As the universal tensile testing machine, for example, a commercially available universal tensile testing machine such as the Toyo Baldwin Tensilon or a universal tensile testing machine with a known configuration can be used. The Young's modulus in the longitudinal and width directions of the sample piece is calculated from the tangent to the rising portion of the load-elongation curve thus obtained. Here, the longitudinal and width directions of the sample piece refer to the longitudinal and width directions when the sample piece is included in a magnetic tape MT.

[0056] For example, after removing the magnetic layer and other parts of the magnetic tape MT other than the base film by a known method (e.g., removal using an organic solvent), the Young's modulus of the base film in the longitudinal and transverse directions can be determined by the above method.

[0057] In one embodiment, the Young's modulus of the base film of the magnetic tape MT in the longitudinal direction is preferably 3,000 MPa or more, more preferably 4,000 MPa or more, even more preferably 5,000 MPa or more, and even more preferably 6,000 MPa or more. The Young's modulus of the base film of the magnetic tape MT in the longitudinal direction can be 15,000 MPa or less, 13,000 MPa or less, or 12,000 MPa or less. In the width direction, the Young's modulus of the base film of the magnetic tape MT in the width direction is preferably 2,000 MPa or more, more preferably 3,000 MPa or more, even more preferably 4,000 MPa or more, and even more preferably 5,000 MPa or more. The Young's modulus of the base film of the magnetic tape MT in the width direction can be 12,000 MPa or less, 11,000 MPa or less, or 10,000 MPa or less. When manufacturing magnetic tape MT, the base film is typically used with the MD (machine direction) of the film as the longitudinal direction and the TD (transverse direction) as the width direction. In one embodiment, the Young's modulus in the longitudinal direction is preferably greater than the Young's modulus in the width direction, and the difference (Young's modulus in the longitudinal direction - Young's modulus in the width direction) is more preferably in the range of 800 to 3000 MPa. The media life of each magnetic tape cartridge 12 can also be controlled by the Young's modulus of the base film.

[0058] The water content and Young's modulus of the base film can be controlled by the types and mixing ratios of the components constituting the support, the manufacturing conditions of the support, etc. For example, by adjusting the stretching ratio in each direction in the biaxial stretching treatment, the Young's modulus in the longitudinal direction and the Young's modulus in the width direction can be controlled.

[0059] 3, 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. In this embodiment, the magnetic head 28 is an example of a "magnetic head" according to the technology of the present disclosure.

[0060] The magnetic tape cartridge 12 is loaded into the magnetic tape drive 14 in the direction of arrow A. In the magnetic tape drive 14, the magnetic tape MT is pulled out from the magnetic tape cartridge 12 and used. The magnetic tape drive 14 manages the magnetic tape cartridge 12 and the magnetic tape drive 14 using management information 15 stored in a cartridge memory 24.

[0061] 14 controls each part.

[0062] 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 having 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). In this embodiment, the magnetic tape drive 14 selectively performs recording processing and reproducing processing using the magnetic head 28. That is, 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 to reproduce data from the surface 31 of the pulled-out magnetic tape MT using the magnetic head 28. In this embodiment, the surface 31 is an example of a "recording surface" according to the technology disclosed herein.

[0063] The processing device 30 controls the entire magnetic tape drive 14. In this embodiment, the processing device 30 is realized by an ASIC, but the technology of the present disclosure is not limited to this. For example, 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), and RAM. The processing device 30 may also be realized by a combination of two or more of the ASIC, FPGA, PLD, and computer. In other words, the processing device 30 may be realized by a combination of hardware and software.

[0064] The storage 32 is connected to the processing device 30, and the processing device 30 writes various types of information to the storage 32 and reads various types of information from the storage 32. Examples of the storage 32 include 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.

[0065] The UI device 29 is a device having a reception function for receiving instruction signals indicating instructions from a user and a presentation function for presenting information to the user. The reception function is realized by, for example, a touch panel, hard keys (e.g., a keyboard), and / or a mouse. The presentation function is realized by, for example, a display, a printer, and / or a speaker. The UI device 29 is connected to the processing device 30. The processing device 30 acquires the instruction signals received by the UI device 29. The UI device 29 presents various information to the user under the control of the processing device 30.

[0066] The transport device 26 is a device that selectively transports the magnetic tape MT in the forward direction or the reverse direction along a predetermined path, and includes a feed motor 36, a take-up reel 38, a take-up motor 40, and a plurality of guide rollers GR. Note that the forward direction here refers to the feed direction of the magnetic tape MT, and the reverse direction refers to the rewind direction of the magnetic tape MT.

[0067] The supply motor 36 rotates the supply reel 22 in the magnetic tape cartridge 12 under the control of the processing device 30. The processing device 30 controls the supply motor 36 to control the rotation direction, rotation speed, rotation torque, etc. of the supply reel 22.

[0068] The take-up motor 40 rotates the take-up reel 38 under the control of the processing device 30. The processing device 30 controls the take-up motor 40 to control the rotation direction, rotation speed, rotation torque, etc. of the take-up reel 38.

[0069] When the magnetic tape MT is wound by the take-up reel 38, the processing device 30 rotates the supply 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, rotational torque, etc. of the supply 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. Furthermore, tension is applied to the magnetic tape MT by adjusting the rotational speed, rotational torque, etc. of the supply motor 36 and the take-up motor 40 by the processing device 30. Furthermore, the tension applied to the magnetic tape MT is controlled by adjusting the rotational speed, rotational torque, etc. of the supply motor 36 and the take-up motor 40 by the processing device 30.

[0070] When the magnetic tape MT is to be rewound 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 travels in the reverse direction along the predetermined path.

[0071] Each of the plurality of guide rollers GR is a roller that guides the magnetic tape MT. The predetermined path, i.e., the running path of the magnetic tape MT, is determined by disposing the plurality of guide rollers GR at positions across the magnetic head 28 between the magnetic tape cartridge 12 and the take-up reel 38.

[0072] 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 come into contact with the running magnetic tape MT. The magnetic element unit 42 has a plurality of magnetic elements.

[0073] 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. Here, data refers to, for example, the servo patterns 52 (see FIG. 6) and data other than the servo patterns 52 (i.e., data recorded in the data band DB (see FIG. 6)).

[0074] 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.

[0075] 4, 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.

[0076] 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 in accordance with the control signal input from the processing device 30, and emits the generated magnetic field MF toward the cartridge memory 24.

[0077] The non-contact read / write device 46 performs contactless communication with the cartridge memory 24 via the magnetic field MF, thereby performing processing on the cartridge memory 24 in accordance with a control signal. For example, under the control of the processing device 30, the non-contact read / write device 46 selectively performs processing to read information from the cartridge memory 24 and processing to store information in the cartridge memory 24 (i.e., processing to write information to the cartridge memory 24). In other words, the processing device 30 reads information from the cartridge memory 24 and stores information in the cartridge memory 24 by communicating contactlessly with the cartridge memory 24 via the non-contact read / write device 46.

[0078] 5, 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 includes a movement mechanism 48. The processing device 30 is connected to the magnetic head 28 via the movement mechanism 48. The processing device 30 controls movement of the magnetic head 28 (e.g., movement in the width direction WD (see FIG. 6) of the magnetic tape MT) via the movement mechanism 48.

[0079] 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).

[0080] 6, servo bands SB1, SB2, and SB3 and data bands DB1 and DB2 are formed on the surface 31 of the magnetic tape MT. In this embodiment, the servo bands SB1, SB2, and SB3 are examples of "plurality of servo bands" according to the technology of the present disclosure. Note that, for convenience of explanation, the servo bands SB1 to SB3 will be referred to as "servo bands SB," and the data bands DB1 and DB2 will be referred to as "data bands DB" hereinafter, unless a distinction is particularly required.

[0081] 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. Here, the longitudinal direction LD refers to the running direction of the magnetic tape MT. The running direction of the magnetic tape MT is defined as two directions: a 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 a 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. In this embodiment, the longitudinal direction LD is an example of the "longitudinal direction" and "first longitudinal direction" according to the technology of the present disclosure.

[0082] The servo bands SB1 to SB3 are arranged at positions spaced apart in the width direction WD of the magnetic tape MT (hereinafter also simply referred to as the "width direction WD"). For example, the servo bands SB1 to SB3 are arranged at equal intervals along the width direction WD.

[0083] In this embodiment, "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 the present disclosure belongs and that does not contradict the spirit of the technology of the present disclosure. In this embodiment, the width direction WD is an example of the "width direction" according to the technology of the present disclosure.

[0084] The data band DB1 is arranged between the servo bands SB1 and SB2, and the data band DB2 is arranged between the servo bands SB2 and SB3. In other words, the servo bands SB and the data bands DB are arranged alternately along the width direction WD.

[0085] In the example shown in Figure 6, for the sake of convenience (to make it easier to understand the technology of the present disclosure), three servo bands SB and two data bands DB are shown, but this is merely an example, and the technology of the present disclosure can also 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.

[0086] 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. In this embodiment, "regular" refers not only to perfect uniformity, but also to uniformity that includes an error that is generally acceptable in the technical field to which the technology of the present disclosure pertains and that does not contradict the spirit of the technology of the present disclosure.

[0087] 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. In the example shown in Fig. 6, 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.

[0088] 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.

[0089] The servo pattern 52A is made up of a pair of linear magnetization regions 54A. In the example shown in Fig. 6, a pair of linear magnetization regions 54A1 and 54A2 is shown as an example of the pair of linear magnetization regions 54A. Each of the linear magnetization regions 54A1 and 54A2 is a linearly magnetized region.

[0090] 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. In the example shown in Fig. 6, 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.

[0091] The linear magnetization region 54A1 is a set of five magnetized straight lines 54A1a, and the linear magnetization region 54A2 is a set of five magnetized straight lines 54A2a.

[0092] The servo pattern 52B is made up of a pair of linear magnetization regions 54B. In the example shown in Fig. 6, 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.

[0093] The linear magnetization regions 54B1 and 54B2 are inclined in opposite directions with respect to a virtual line C2, which is a virtual line extending along the width direction WD. In the example shown in Fig. 6, 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 in the longitudinal direction LD with the virtual line C2 as the axis of symmetry.

[0094] The linear magnetization region 54B1 is a set of four magnetized straight lines 54B1a, and the linear magnetization region 54B2 is a set of four magnetized straight lines 54B2a.

[0095] 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 traverse 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 linearly along the longitudinal direction of the holder 44. In the example shown in Figure 6, the longitudinal direction of the magnetic head 28, i.e., the longitudinal direction of the holder 44, coincides with the width direction WD.

[0096] The magnetic element unit 42 has three servo read elements SR and multiple data read / write elements DRW as multiple magnetic elements. Here, three servo read elements SR are shown as an example to facilitate understanding of the present disclosure, but this is merely an example, and the present disclosure also applies to four or more servo read elements SR.

[0097] The length of the holder 44 in the longitudinal direction is sufficiently long compared to the width of the magnetic tape MT. For example, the length of the holder 44 in the longitudinal direction is set to be longer than the width of the magnetic tape MT no matter where the magnetic element unit 42 is placed on the magnetic tape MT.

[0098] Three servo read elements SR are mounted on the magnetic head 28. In the magnetic head 28, the relative positional relationship between the holder 44 and the three servo read elements SR is fixed. The three servo read elements SR consist of servo read elements SR1, SR2, and SR3. The servo read elements SR1, SR2, and SR3 are arranged at intervals along the longitudinal direction of the holder 44 (for example, arranged at equal intervals along the longitudinal direction of the holder 44).

[0099] The servo read element SR1 is disposed at one end of the magnetic element unit 42. The servo read element SR3 is disposed at the other end of the magnetic element unit 42. The servo read element SR2 is disposed midway (here, as an example, in the center) between the servo read elements SR1 and SR2 in the longitudinal direction of the magnetic head 28. In the example shown in FIG. 6, the servo read element SR1 is disposed at a position corresponding to the servo band SB3. Also, in the example shown in FIG. 6, the servo read element SR2 is disposed at a position corresponding to the servo band SB2. Furthermore, in the example shown in FIG. 6, the servo read element SR3 is disposed at a position corresponding to the servo band SB1.

[0100] A plurality of data recording and reproducing elements DRW are linearly arranged between the servo read element SR1 and the servo read element SR2, and between the servo read element SR2 and the servo read element SR3. Between the servo read element SR1 and the servo read element SR2, and between the servo read element SR2 and the servo read element SR3, the plurality of data recording and reproducing elements DRW are arranged at intervals along the longitudinal direction of the magnetic head 28 (for example, arranged at equal intervals along the longitudinal direction of the magnetic head 28). In the example shown in Fig. 6, a plurality of data recording and reproducing elements DRW are provided at positions corresponding to the data band DB2 and at positions corresponding to the data band DB1.

[0101] The processing device 30 acquires a servo pattern signal resulting from the servo read element SR reading the servo pattern 52, and performs servo control in accordance with the acquired servo pattern signal. In this embodiment, the servo pattern signal is an example of a "signal" according to the technology of the present disclosure.

[0102] Here, servo control refers to control for moving the magnetic head 28 in the width direction WD of the magnetic tape MT by operating the moving mechanism 48 in accordance with the servo pattern 52 read by the servo read element SR.

[0103] By performing servo control, the plurality of data recording / reproducing elements DRW are positioned over a designated area in the data band DB, and in this state, magnetic processing is performed on the designated area in the data band DB. In the example shown in Figure 6, magnetic processing is performed by the plurality of data recording / reproducing elements DRW on a designated area in the data band DB2.

[0104] As an example, as shown in Figure 7, data band DB2 has multiple divided areas obtained by dividing data band DB2 in the width direction WD, with data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7 and DT8 formed from the servo band SB2 side to the servo band SB3 side.

[0105] The magnetic head 28 has, as a plurality of data recording and reproducing elements DRW, 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.

[0106] Hereinafter, unless a particular distinction is required, data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7, and DT8 will be referred to as "data tracks DT." Also, below, unless a particular distinction is required, 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."

[0107] Although not shown, a plurality of data tracks DT corresponding to data tracks DT1, DT2, DT3, DT4, DT5, DT6, DT7 and DT8 are also formed on the data band DB1 (see FIG. 6).

[0108] As an example, as shown in Figure 8, the data track DT has divided data track groups DTG. Data tracks DT1 to DT8 correspond to divided data track groups DTG1 to DTG8. Hereinafter, unless there is a need to distinguish between them, the divided data track groups DTG1 to DTG8 will be referred to as "divided data track groups DTG."

[0109] The divided data track group DTG1 is a set of a plurality of divided data tracks obtained by dividing the data track DT in the width direction WD. In the example shown in Figure 8, divided data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11, and DT_12 are shown as an example of the divided 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 divided data track group DTG1. In other words, the data recording and reproducing element DRW1 is responsible for recording data to the divided data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11, and DT_12, and reproducing data from the divided data tracks DT_1, DT_2, DT_3, DT_4, ..., DT_11, and DT_12. In the following description, when it is not necessary to distinguish between the divided data tracks DT_1, DT_2, DT_3, DT_4, . . . , DT_11 and DT_12, they will be referred to as "divided data tracks DT_N."

[0110] Like the data recording / reproducing element DRW1, each of the data recording / reproducing elements DRW2 to DRW8 also performs magnetic processing on the divided data track group DTG of the data track DT corresponding to each data recording / reproducing element DRW.

[0111] The data recording / reproducing element DRW moves to a position corresponding to one designated data track DT among the multiple data tracks DT as the magnetic head 28 is moved in the width direction WD by the moving mechanism 48 (see FIG. 6) (i.e., along the longitudinal direction of the magnetic head 28). The data recording / reproducing element DRW is held at the position corresponding to the designated data track DT by servo control using servo patterns 52 (see FIGS. 6 and 7).

[0112] As an example, as shown in Figure 9, 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 plurality of divided data tracks DT_N (12 divided data tracks DT_N in the example shown in Figures 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. Hereinafter, when there is no need to distinguish between the paths P1 to P12, they will be referred to as "path P."

[0113] When the data recording / reproducing element DRW performs magnetic processing on a target divided data track, which is a divided data track DT_N designated as the target of magnetic processing, the movement mechanism 48 moves the magnetic head 28 in the width direction WD so that the servo read element SR passes along a path P corresponding to the target divided data track. For example, when the data recording / reproducing element DRW performs magnetic processing on a divided data track DT_1, the movement mechanism 48 moves the magnetic head 28 in the width direction WD so that the servo read element SR passes along path P1. Also, for example, when the data recording / reproducing element DRW performs magnetic processing on a divided data track DT_12, the movement mechanism 48 moves the magnetic head 28 in the width direction WD so that the servo read element SR passes along path P12. This allows the data recording / reproducing element DRW1 to directly face the target divided data track and perform magnetic processing on the target divided data track.

[0114] Here, examples of magnetic tape MT on which data is recorded using the SMR method will be described with reference to Figures 10A and 10B. Figure 10A is a conceptual diagram showing an example of the form of data tracks DT formed by recording data on surface 31 of magnetic tape MT using the SMR method in data band DB2 between servo bands SB2 and SB3, resulting in a plurality of divided data tracks DT_N overlapping and shifted along the other end of the width of magnetic tape MT. Figure 10B is a conceptual diagram showing an example of the form of data tracks DT formed by recording data on surface 31 of magnetic tape MT using the SMR method in data band DB1 between servo bands SB1 and SB2, resulting in a plurality of divided data tracks DT_N overlapping and shifted along the other end of the width of magnetic tape MT.

[0115] 10A and 10B, 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 / reproducing element DRW in the SMR system. The SMR system is a magnetic recording system for increasing the data density on the magnetic tape MT, and is also called the shingled recording system.

[0116] 10A and 10B , 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 when data is recorded 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.

[0117] In this embodiment, the multiple divided data tracks DT_N for each data track DT are an example of "multiple tracks" according to the technology of the present disclosure. Also, in this embodiment, the pitch Tp is an example of "track pitch" according to the technology of the present disclosure. Note that in the example shown in Figures 10A and 10B, the divided 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 positional relationship of the divided data tracks DT_1 to DT_12, but in reality, there is no shift in the longitudinal direction LD between the divided data tracks DT_1 to DT_12, and the divided data tracks DT_1 to DT_12 extend in the longitudinal direction LD.

[0118] Guard bands GB are formed between the data tracks DT in the width direction WD. The guard bands GB are blank areas that are not used for recording or reproducing data. The guard bands GB formed between the data tracks DT serve 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 / reproducing elements DRW (for example, variations within manufacturing tolerances).

[0119] In addition, guard bands GB are also 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 have the role of preventing the magnetic influence of the servo read element SR on the servo bands SB from affecting the data tracks DT, or the magnetic influence of the data read / write element DRW from affecting the servo bands SB.

[0120] 11, the magnetic head 28 includes a first recording module DWM1, a second recording module DWM2, and a playback module DRM. For ease of explanation, the first recording module DWM1 and the second recording module DWM2 will be referred to as the "recording module DWM" below unless they need to be distinguished.

[0121] The recording module DWM and the playback module DRM are arranged along the longitudinal direction LD (in other words, the short-side direction of the magnetic head 28 in the example shown in FIG. 11 ). For example, one recording module DWM is arranged on each side of the playback module DRM in the longitudinal direction LD. The example shown in FIG. 11 schematically illustrates an example of the front side of the magnetic head 28 when the magnetic head 28 shown in FIG. 3 is viewed from the opposite direction to the direction indicated by arrow B in FIG. 3 . The first recording module DWM1 is arranged on the side of the supply reel 22 (see FIG. 3 ) of the playback module DRM in the longitudinal direction LD, and the second recording module DWM2 is arranged on the side of the take-up reel 38 (see FIG. 3 ) of the playback module DRM in the longitudinal direction LD.

[0122] The recording module DWM and the reproducing 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 servo read element SR3, a first data recording element group DWG1, a second data recording element group DWG2, and a data reproducing 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 reproducing element group DRG is provided in the reproducing module DRM.

[0123] A servo read element SR1 is located at one end of the magnetic element unit 42, and a servo read element SR3 is located at the other end of the magnetic element unit 42. Of all the magnetic elements constituting the magnetic element unit 42, a servo read element SR2 is located in the middle between the servo read elements SR1 and SR3.

[0124] The data recording and reproducing element DRW is provided between the servo read element SR1 and the servo read element SR2, and between the servo read element SR2 and the servo read element SR3. The servo recording and reproducing element DRW has a first data recording element DW1, a second data recording element DW2, and a data reproducing element DR.

[0125] The first data recording element group DWG1 includes a plurality of first data recording elements DW1, which are linearly arranged 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 also parallel to the width direction WD (in other words, perpendicular to the longitudinal direction LD).

[0126] The second data recording element group DWG2 includes a plurality of second data recording elements DW2, which are linearly arranged along the width direction WD. The arrangement direction of the second data recording elements DW2 is parallel to the surface 31 of the magnetic tape MT and parallel to the width direction WD (in other words, perpendicular to the longitudinal direction LD).

[0127] The data reproducing element group DRG includes a plurality of data reproducing elements DR, which are linearly arranged along the width direction WD and are parallel to the surface 31 of the magnetic tape MT and parallel to the width direction WD (in other words, perpendicular to the longitudinal direction LD).

[0128] Hereinafter, for convenience of explanation, when there is no need to distinguish between the first data recording element DW1 and the second data recording element DW2, the first data recording element DW1 and the second data recording element DW2 will be referred to as the "data recording element DW." In this embodiment, the data recording element DW is an example of the "recording element" according to the technology of the present disclosure.

[0129] The data recording element DW records data onto the data track DT, and the data reproducing element DR reproduces data from the data track DT.

[0130] 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. Here, the term "regular interval" refers to, for example, an interval that is determined in advance by testing an actual device and / or computer simulation as an interval at which crosstalk does not occur between the data recording elements DW and the data reproducing elements DR.

[0131] 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, SR2, and SR3 has a first servo read element SRa, a second servo read element SRb, and a third servo read element SRc.

[0132] 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 Figure 3) side to the take-up reel 38 (see Figure 3) side in the longitudinal direction LD.

[0133] 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 track DT among all the data tracks DT included in the data band DB.

[0134] The first recording module DWM1 is provided with three 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. In the first recording module DWM1, the plurality of first data recording elements DW1 are linearly arranged at equal intervals between adjacent first servo read elements SRa.

[0135] The number of the plurality of 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. In the example shown in Fig. 11, eight first data recording elements DW1 are illustrated as the plurality of first data recording elements DW1, and the positions of these first data recording elements DW1 correspond to the positions of the data recording / reproducing elements DRW1, DRW2, DRW3, DRW4, DRW5, DRW6, DRW7, and DRW8 (see Figs. 7 and 8).

[0136] The data reproducing element group DRG has a plurality of data reproducing elements DR. Each data reproducing element DR reproduces data from a corresponding data track DT among all the data tracks DT included in the data band DB.

[0137] The reproduction module DRM is provided with three second servo read elements SRb, which are adjacent to each other in the width direction WD with a plurality of data reproduction elements DR interposed therebetween. In the reproduction module DRM, the plurality of data reproduction elements DR are arranged linearly and at equal intervals between adjacent second servo read elements SRb.

[0138] The number of the plurality 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. In the example shown in Figure 11, eight data reproducing elements DR are illustrated as the plurality of 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 Figures 7 and 8).

[0139] 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.

[0140] The second recording module DWM2 is provided with three third servo read elements SRc, and the three third servo read elements SRc are adjacent to each other in the width direction WD via a plurality of second data recording elements DW2.

[0141] In the second recording module DMW2, the second data recording elements DW2 are linearly arranged at equal intervals between adjacent third servo read elements SRc.

[0142] 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. In the example shown in Fig. 11, 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 Figs. 7 and 8).

[0143] Here, an example of the geometric relationship between the data recording element DW and the data reproducing element DR included in the data recording / reproducing element DRW corresponding to one data track DT will be described.

[0144] In the magnetic head 28 on the magnetic tape MT, the center position of the data recording element DW and the center position of the data reproducing element DR included in the data recording / reproducing element DRW corresponding to one data track DT coincide in the width direction WD. Here, 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. Also, 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. Also, here, "coincidence" refers to a coincidence in the sense of including an error that is generally acceptable in the technical field to which the technology of the present disclosure belongs, and that does not contradict the spirit of the technology of the present disclosure.

[0145] In this embodiment, the center positions of the data recording element DW and the data reproducing element DR coincide in the width direction WD, which is also to realize the so-called "read while write" operation. In "read while write," to verify whether data recorded on the magnetic tape MT is recorded correctly during the recording operation, the first recording module DWM1 records data on the magnetic tape MT in accordance with the servo pattern signal obtained by the first servo read element SRa. As the magnetic tape MT is transported in the forward direction, the reproducing module DRM immediately reproduces the data. When the magnetic tape MT is transported in the reverse direction and the second recording module DWM2 records data on the magnetic tape MT, "read while write" is performed between the second recording module DWM2 and the reproducing module DRM in a similar manner.

[0146] In addition, in the data recording / reproducing element DRW corresponding to one data track DT, the length L1 of the data recording element DW in the width direction WD is longer than the length β1 of the data reproducing element DR in the width direction WD and is at least twice the pitch Tp. Furthermore, the length β1 is less than the pitch Tp (see FIGS. 10A and 10B ).

[0147] In this embodiment, the length L1 is an example of a "recording element length" according to the technology of the present disclosure. Also, in this embodiment, the pitch Tp is an example of a "track pitch" according to the technology of the present disclosure.

[0148] After the first data write element DW1 forms a data track DT (see FIGS. 10A and 10B) by the SMR method in accordance with a 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 FIGS. 10A and 10B) included in the data track DT. At this time, the data reproducing element DR reproduces data from the divided data track DT_N in accordance with a servo pattern signal obtained by reading the servo pattern 52 by the second servo read element SRb.

[0149] When the data tracks DT are formed using the SMR method, adjacent divided data tracks DT_N overlap each other, so when the data is reproduced by the data reproducing element DR, the area from which data is reproduced by the data reproducing element DR is narrower than when data is recorded by the first data recording element DW1. For example, in the example shown in Figures 10A and 10B, only the area of ​​the divided data tracks DT_N that corresponds to the pitch Tp is the area from which data is reproduced by the data reproducing element DR.

[0150] Since the positions of the first servo read element SRa and the second servo read element SRb are aligned in the width direction WD, when reproducing data from the data tracks DT formed by the SMR method (i.e., when the data reproducing element DR reproduces data from the divided data tracks DT_N), the position of the magnetic head 28 must be shifted in the width direction WD by a distance Dr (={(length L1)-(pitch Tp)} / 2), which is greater than the pitch Tp, from when the data was recorded by the first data recording element DW1. In other words, it is required that the second servo read element SRb read the servo pattern 52 on a path P that is shifted by the distance Dr in the width direction WD from the path P through which the first servo read element SRa passes.

[0151] For example, when data is reproduced by the data reproducing element DR from a specific divided data track DT_N formed by recording data by the data recording element DW, 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 through which the first servo read element SRa passes.

[0152] Next, an example of a method for manufacturing the magnetic tape MT will be described.

[0153] The manufacturing method of the magnetic tape MT includes a plurality of steps, including a servo pattern recording step, an inspection step, and a winding step, and an example of the servo pattern recording step, the inspection step, and the winding step will be described here with reference to FIG.

[0154] 12, 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, a plurality of guides SW6, a transport path SW7, a servo pattern recording head WH, and a verify head VH. In this embodiment, the servo pattern recording head WH is an example of a "servo write head" according to the technology of the present disclosure.

[0155] The control device SW5 controls the entire servo writer SW. In this embodiment, the control device SW5 is realized by an ASIC, but the technology of the present disclosure is not limited to this. For example, 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, flash memory (e.g., EEPROM and / or SSD), and RAM. The control device SW5 may also be realized by a combination of two or more of the ASIC, FPGA, PLC, and computer. In other words, the control device SW5 may be realized by a combination of hardware and software.

[0156] A pancake is set on the supply reel SW1. The pancake refers to a large diameter roll of magnetic tape MT, which is cut to the product width from a wide web before the servo pattern 52 is written, wound around a hub.

[0157] 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. 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, thereby rotating the supply reel SW1 and the take-up reel SW2.

[0158] That is, the supply reel SW1 receives power from the drive unit SW3 to rotate, thereby feeding the magnetic tape MT to a 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 fed from the supply reel SW1. The rotation speeds and rotation torques of the supply reel SW1 and the take-up reel SW2 are adjusted according to the speed at which the magnetic tape MT is wound around the take-up reel SW2.

[0159] A plurality 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 on the surface 31 side of the magnetic tape MT between the plurality of guides SW6. The magnetic tape MT sent out from the supply reel SW1 to the transport path SW7 is guided by the plurality of guides SW6, passes over the servo pattern recording head WH, and is taken up by the take-up reel SW2.

[0160] The pulse signal generator SW4 generates pulse signals under the control of the control device SW5 and supplies the generated pulse signals 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 the servo bands SB on the magnetic tape MT by recording a plurality of servo patterns 52 along the longitudinal direction LD (see FIG. 6, etc.) in accordance with the pulse signals supplied from the pulse signal generator SW4 in areas where the formation of the servo bands SB is planned in advance.

[0161] The inspection process is a process of inspecting the magnetic tape MT on which the servo bands SB are formed. For example, in the inspection process, 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 of determining whether the servo patterns 52 recorded on the servo bands SB are correct. Determining whether the servo patterns 52 are correct refers to, for example, determining whether the magnetization lines 54A1a, 54A2a, 54B1a, and 54B2a of the servo patterns 52A and 58B are recorded exactly and within the allowable error relative to predetermined locations on the surface 31 (i.e., verifying the servo patterns 52).

[0162] The inspection of the servo bands SB is performed using the control device SW5 and the verify head VH. The verify head VH is located 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), similar to the magnetic head 28, and the multiple servo read elements read the multiple servo bands SB.

[0163] 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 patterns 52 recorded on the servo band SB, and outputs the read results (hereinafter referred to as "servo pattern read results") to the control device SW5. The control device SW5 inspects the servo band SB (e.g., determines whether the servo patterns 52 are correct or not) based on the servo pattern read results (e.g., servo pattern signals) input from the verify head VH.

[0164] The control device SW5 outputs information indicating the results of inspecting the servo band SB (e.g., the results 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.).

[0165] Once the inspection process is completed (for example, when it is determined in the inspection process that the servo bands SB are correctly formed on the magnetic tape MT), the winding process is carried out. The winding process is a process of winding the magnetic tape MT onto the supply reel 22 (see FIGS. 2 to 4) housed in the magnetic tape cartridge 12 (see FIGS. 1 to 4)) used for each of the multiple magnetic tape cartridges 12 (see FIGS. 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. The winding motor M rotates the supply reel 22 by applying a rotational force to the supply reel 22 under the control of a control device (not shown). The magnetic tape MT wound onto the take-up reel SW2 is wound onto the supply reel 22 by the rotation of the supply reel 22. A cutting device (not shown) is used in the winding process. When the required amount of magnetic tape MT is wound onto each of the plurality of supply reels 22, the magnetic tape MT fed from the take-up reel SW2 to the supply reel 22 is cut by a cutting device.

[0166] Figure 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 running on the transport path SW7 (see Figure 12), and an example of the configuration of the pulse signal generator SW4.

[0167] 13, the servo pattern recording head WH has a base body WH1 and multiple head cores WH2. The base body 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 body WH1 is rectangular with 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.

[0168] The surface WH1A has a sliding surface WH1Ax. The sliding surface WH1Ax is the surface of the surface WH1A that overlaps with the surface 31 of the magnetic tape MT when the substrate WH1 crosses over the surface 31 of the magnetic tape MT in the width direction WD. The sliding surface WH1Ax slides against the running magnetic tape MT. The width of the sliding surface WH1Ax (i.e., the length in the direction LD1 corresponding to the longitudinal direction LD (e.g., the same direction as the longitudinal direction LD)) shown in FIG. 13 is merely an example, and the width of the sliding surface WH1Ax may be several times wider than the example shown in FIG. 13.

[0169] The longitudinal direction of the base WH1, that is, the direction WD3 (i.e., the direction along the long side WH1Aa), corresponds to the width direction WD (e.g., the same direction as the width direction WD). A plurality of head cores WH2 are incorporated into 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).

[0170] In this embodiment, the direction WD3 is an example of a "second longitudinal direction" according to the technology of the present disclosure. Furthermore, in this embodiment, the surface WH1A is an example of a "facing surface" according to the technology of the present disclosure. Furthermore, in this embodiment, the gap pattern G is an example of a "gap pattern" according to the technology of the present disclosure.

[0171] 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 line 54A1a located at the most upstream side in the forward direction among the five magnetization 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 line 54A2a located at the most upstream side in the forward direction among the five magnetization lines 54A2a included in the linear magnetization region 54A2 shown in Fig. 6 .

[0172] A plurality of gap patterns G are formed at intervals along the direction WD3 on the surface WH1A. The interval in the direction WD3 between adjacent gap patterns G on the surface WH1A 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).

[0173] A coil (not shown) is wound around the head core WH2, and pulse signals are supplied to the coil, including a pulse signal for the servo pattern 52A and a pulse signal for the servo pattern 52B.

[0174] When the servo writer SW configured as described above performs the servo pattern recording process, the servo pattern recording head WH is positioned so that the surface 31 of the magnetic tape MT faces the plurality of gap patterns G. Then, while maintaining this position, the servo write head WH records the plurality of servo patterns G on the surface 31 of the magnetic tape MT along the longitudinal direction LD, thereby forming a plurality of servo bands SB (see FIG. 6 ) on the surface 31. A method for forming the plurality of servo bands SB on the surface 31 will be described in more detail below.

[0175] When a pulse signal for servo pattern 52A is supplied to the coil of head core WH2 in a state where gap pattern G faces (in other words, faces directly) an area on surface 31 of magnetic tape MT running on transport path SW7 where servo bands SB are to be formed in advance, a magnetic field is applied from gap pattern G to servo bands SB of magnetic tape MT in accordance with the pulse signal. As a result, servo pattern 52A is recorded in the area on surface 31 of magnetic tape MT where servo bands SB are to be formed in advance. Also, when gap pattern G faces (in other words, faces directly) an area on surface 31 of magnetic tape MT running on transport path SW7 where servo bands SB are to be formed in advance, a pulse signal for servo pattern 52B is supplied to the coil of head core WH2, a magnetic field is applied from gap pattern G to servo bands SB of magnetic tape MT. As a result, servo pattern 52B is recorded in the area on surface 31 of magnetic tape MT where servo bands SB are to be formed in advance. In this way, 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.

[0176] The pulse signal corresponding to each servo pattern 52 (i.e., the servo pattern 52 for each frame 50 (see FIG. 6)) is modulated. By modulating the pulse signal, various pieces of information are embedded in the pulse signal. In this case, for example, by modulating the pulse signal for the servo pattern 52A, it is possible to change the interval between the third magnetization line 54A1a and the second magnetization line 54A1a (hereinafter referred to as the "first interval") and the interval between the third magnetization line 54A1a and the fourth magnetization line 54A1a (hereinafter referred to as the "second interval") among the five magnetization lines 54A1a (see FIG. 6) for each servo pattern 52A. By making 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 pieces of information by combining multiple servo patterns 52.

[0177] The various information includes, for example, information about the position of the magnetic tape MT in the longitudinal direction LD, information for identifying the servo band SB, and / or information for identifying the manufacturer of the magnetic tape MT.

[0178] 13, head cores WH2A, WH2B, and WH2C are shown as examples of the plurality of head cores WH2, and gap patterns G1, G2, and G3 are shown as examples of the plurality of 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.

[0179] Gap patterns G1 to G3 have the same geometric characteristics. In this embodiment, for example, 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), and gap pattern G3 is used to record servo pattern 52 (see FIG. 6) for servo band SB1 (see FIG. 6).

[0180] 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. In this embodiment, gap patterns G1 to G3 are examples of "plurality of gap patterns" according to the technology of the present disclosure.

[0181] 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.

[0182] When the gap pattern G1 is used to form the servo band SB3 (see Figure 6), when the first pulse signal generator SW4A supplies a pulse signal to the head core WH2A, a magnetic field is applied from the gap pattern G1 to the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is pre-planned in accordance with the pulse signal, and a servo pattern 52 (see Figure 6) is recorded in the area where the formation of the servo band SB3 is pre-planned.

[0183] For example, when the gap pattern G1 faces (or faces directly at) 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, and a pulse signal for the servo pattern 52A is supplied to the head core WH2A, 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, a linear magnetized area 54A1 (see FIG. 6) is recorded by the linear 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 a linear magnetized area 54A2 (see FIG. 6) is recorded in the servo band SB3 by the linear area G1B. 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.

[0184] Furthermore, for example, when the gap pattern G1 faces (i.e., directly faces) 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, and a pulse signal for the servo pattern 52B is supplied to the head core WH2A, 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, a linear magnetized area 54B1 (see FIG. 6) is recorded by the linear 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 a linear magnetized area 54B2 (see FIG. 6) is recorded by the linear area G1B in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is planned. As a result, the servo pattern 52B is formed in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is planned.

[0185] In this way, the servo band SB3 is formed by alternately forming the servo patterns 52A and 52B along the longitudinal direction LD in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB3 is planned in advance.

[0186] When the gap pattern G2 is used to form the servo band SB2 (see Figure 6), when the second pulse signal generator SW4B supplies a pulse signal to the head core WH2B, a magnetic field is applied from the gap pattern G2 to the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB2 is pre-planned in accordance with the pulse signal, and the servo pattern 52 (see Figure 6) is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB2 is pre-planned.

[0187] For example, when the gap pattern G2 faces (or faces directly at) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the servo band SB2 is to be formed, 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 servo band SB2 is to be formed. That is, a linear magnetized area 54A1 is recorded by the linear area G2A in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is to be formed, and a linear magnetized area 54A2 (see FIG. 6) is recorded by the linear area G2B in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is to be formed. As a result, the servo pattern 52A is formed in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is to be formed.

[0188] Furthermore, for example, when 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, if 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. That is, a linear magnetized area 54B1 is recorded by the linear area G2A in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is scheduled to be formed, and a linear magnetized area 54B2 (see FIG. 6) is recorded by the linear area G2B in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is scheduled to be formed. As a result, the servo pattern 52B is formed in the area on the surface 31 of the magnetic tape MT where the servo band SB2 is scheduled to be formed.

[0189] In this way, the 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 the servo band SB2 is planned in advance, thereby forming the servo band SB2.

[0190] When the gap pattern G3 is used to form the servo band SB1 (see Figure 6), when the third pulse signal generator SW4C supplies a pulse signal to the head core WH2C, a magnetic field is applied from the gap pattern G3 to the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is pre-planned in accordance with the pulse signal, and the servo pattern 52 (see Figure 6) is recorded in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is pre-planned.

[0191] For example, when the gap pattern G3 faces (or faces directly at) an area on the surface 31 of the magnetic tape MT running on the transport path SW7 where the servo band SB1 is to be formed, 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 servo band SB1 is to be formed. That is, a linear magnetized area 54A1 (see FIG. 6) is recorded by the linear area G3A in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is to be formed, and a linear magnetized area 54B2 (see FIG. 6) is recorded by the linear area G3B in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is to be formed. As a result, the servo pattern 52A is formed in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is to be formed.

[0192] Furthermore, for example, when 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 servo band SB1 is scheduled to be formed, if a pulse signal for the servo pattern 52B is supplied to the head core WH2C, the servo pattern 52B is recorded in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is scheduled to be formed. That is, a linear magnetized area 54B1 (see FIG. 6) is recorded by the linear area G3A in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is scheduled to be formed, and a linear magnetized area 54B2 (see FIG. 6) is recorded by the linear area G3B in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is scheduled to be formed. As a result, the servo pattern 52B is formed in the area on the surface 31 of the magnetic tape MT where the servo band SB1 is scheduled to be formed.

[0193] In this way, the servo band SB1 is formed by alternately forming the servo patterns 52A and 52B along the longitudinal direction LD in the area on the surface 31 of the magnetic tape MT where the formation of the servo band SB1 is planned in advance.

[0194] The head core WH2C includes a magnetic film 60 and a base glass 62. The magnetic film 60 forms the base of the head core WH2C. An example of the magnetic film 60 is a metal film. Here, the concept of "metal film" also includes alloy films. An example of a metal film is a deposited film formed by depositing one or more metal materials selected from the group consisting of one or more pure metals and one or more alloys. The metal film may also contain one or more additives, and may also contain one or more unavoidably mixed impurities. The magnetic film 60 may be an iron-based alloy film. Here, "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 one containing, as constituent elements, one or more elements selected from the group consisting of Fe and N, as well as Al and / or Ta. The magnetic film 60 may be obtained as a deposited film by depositing a metal material on a substrate by a known film formation method such as physical vapor deposition (PVD) such as sputtering and / or vacuum deposition, and / or chemical vapor deposition (CVD). 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. The magnetic film 60 and the base glass 62 form a flat surface 66.

[0195] 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.

[0196] 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, 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 is low, the accuracy of servo control would be reduced.

[0197] Methods for improving the linearity of the ridge region 70 include, for example, the following first to third methods. The first method is a method for improving the linearity of the ridge region 70 by improving the accuracy of a photomask used in photolithography. The second method is a method for forming a linear groove 71 of a size corresponding to the entire width of the opening 66A of a head core WH2C formed by a photolithography method by trimming the entire width of the opening 66A with an FIB or laser, and filling the groove 71 with a non-magnetic material 68 to form the linear region G3B. The third method is a method for forming a groove 72 of a base G3B1 of a head core WH2C formed by a photolithography method by linearly trimming the ridge region 70 with an FIB or laser, and filling the groove 72 with a non-magnetic material 68 to form the linear region G3B.

[0198] Regarding the third method, for example, first, a head core WH2C formed by a photolithography method is processed using an FIB or laser to shape the base G3B1. That is, a 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 linearly trimming the ridge region 70 of the base G3B1. Then, a non-magnetic material 68 is filled into the groove 72 obtained by trimming the base G3B1 with the FIB. By shaping the base G3B1 in this manner, the linear region G3B is formed. In this way, by performing processing using any of the first to third methods, the linearity of the linear region G3B can be improved and the durability of the linear region G3B can be increased.

[0199] Although the linear region G3B is shown as an example here, each of the linear regions G1A, G1B, G2A, G2B, and G3A can be obtained by processing similar to that performed to obtain the linear region G3B.

[0200] In this way, by processing the head core WH2 using an FIB or laser, the linearity of the linear regions G1A, G1B, G2A, G2B, G3A, and G3B is improved, and as a result, multiple highly linear servo patterns 52 are formed on the surface 31 of the magnetic tape MT along the longitudinal direction LD for each servo band SB.

[0201] In this embodiment, in order to further improve the linearity of each servo pattern 52 contained in each servo band SB, a linearity inspection method is performed on a magnetic tape MT on which multiple servo bands SB are formed, as shown in Figure 14 as an example.

[0202] The linearity inspection method is a method for inspecting the linearity of the servo patterns 52 formed on the magnetic tape MT, and is performed, for example, in the inspection step 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 also be performed using a magnetic tape drive 14. The linearity inspection method may be implemented mainly through manual measurements by an inspector (not shown), or may be implemented mainly through automation using an inspection device (not shown). In this embodiment, the linearity inspection method shown in FIG. 14 is an example of an "inspection method" according to the technology of the present disclosure.

[0203] In the linearity inspection method shown in Figure 14, first, in step ST10, from two servo bands SB that straddle one servo band SB in the width direction WD within the magnetic tape MT on which multiple servo bands SB have been formed by the above-mentioned servo pattern recording process, i.e., from a pair of servo bands SB that are not adjacent in the width direction WD (here, as an example, servo bands SB1 and servo band SB3), a pair of uninspected servo patterns 52 that are adjacent in the width direction WD (i.e., a pair of servo patterns 52 whose linearity has not been inspected) are selected.

[0204] In the next step ST12, an index (hereinafter also simply referred to as "index") indicating the nonlinearity of the servo patterns 52 is obtained from the pair of uninspected servo patterns 52 selected in step ST10.

[0205] In the next step ST14, the magnetic tape MT is inspected using the index acquired in step ST12. For example, in 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.

[0206] In the next 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) included in two servo bands SB that straddle one servo band SB in the width direction WD of the magnetic tape MT, i.e., pairs of servo bands SB that are not adjacent in the width direction WD, has been inspected. In step ST16, if the linearity of all test objects included in two servo bands SB that straddle one servo band SB in the width direction WD of the magnetic tape MT has not been inspected, the determination is negative, and the linearity inspection method proceeds to step ST10. In step ST16, if the linearity of all test objects included in two servo bands SB that straddle one servo band SB in the width direction WD of the magnetic tape MT has been inspected, the determination is positive, and the linearity inspection method ends. Note that, although an example is given here in which the linearity of all test objects included in two servo bands SB that straddle one servo band SB in the width direction WD of the magnetic tape MT is inspected, this is merely an example. For example, if there is a servo band (not shown here, but for convenience, referred to as "servo band SB4") on the magnetic tape MT that straddles one or more data bands (not shown) on the first direction WD1 side of servo band SB3, the linearity of all test objects included in servo band SB2 and servo band SB4 (i.e., all pairs of servo patterns 52 that have been pre-determined as test objects) may also be inspected.

[0207] Here, a specific example of how to obtain the index will be described.

[0208] A plurality of PESs are used as the index. The PES indicates the position in the width direction WD within the servo pattern 52. The PES is measured using the following equation (1).

[0209]

[0210] FIG. 15 shows a conceptual diagram for explaining 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) for measuring the PES.

[0211] In formula (1), "α1" is a predetermined angle formed by the virtual line C1 and the linear magnetization region 54A1. In formula (1), "α2" is a predetermined angle formed by the virtual line C1 and the linear magnetization region 54A2. In this embodiment, since the linear magnetization regions 54A1 and 54A2 are tilted axisymmetrically with respect to the virtual line C1, "α1" and "α2" are the same value.

[0212] In the formula (1), "i" is a natural number between 1 and 4. The maximum value of "i" (here, 4) is the number of magnetization lines 54A1a used in measuring the PES. ｉ " refers to the distance between the magnetization lines 54A1a and 54A2a at corresponding positions when the servo read element SR4 of the verify head VH crosses the servo pattern 52A along the longitudinal direction LD. Here, "the magnetization lines 54A1a and 54A2a at corresponding positions" refers to the first to fourth pairs of magnetization lines. The first pair of magnetization lines refers to the magnetization lines 54A1a and 54A2a that are 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 that are 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 that are third from the most upstream side to the most 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 that are fourth from the most upstream side to the most downstream side in the running direction of the magnetic tape MT in each of the linear magnetization regions 54A1 and 54A2.

[0213] In the formula (1), “B ｉ " refers to the distance between the magnetization lines 54A1a and 54B1a at corresponding positions when the servo read element SR4 crosses the servo pattern 52A and the servo pattern 52B adjacent to the servo pattern 52A on the forward direction side along the longitudinal direction LD. Here, "the magnetization 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 the magnetization lines 54A1a and 54B1a located at the most upstream 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 direction side. The sixth pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a that are second from the most upstream side to the most 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 that is adjacent to the servo pattern 52A on the forward side. The seventh pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a that are third from the most upstream side to the most 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 that is adjacent to the servo pattern 52A on the forward side. The eighth pair of magnetization lines refers to the magnetization lines 54A1a and 54B1a that are located fourth 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.

[0214] In formula (1), "d" is a predetermined distance between the linear magnetization regions 54A1 and 54B1 in the longitudinal direction LD. One example of "d" is the predetermined distance between the magnetization lines 54A1a and 54B1a at corresponding positions when the servo read element SR4 crosses the servo patterns 52A and 52B along the longitudinal direction LD.

[0215] Here, an example is given in which the formula (1) is used to measure the PES in the servo pattern 52A when the magnetic tape MT runs in the forward direction, but the formula (1) is also used to measure the PES in the servo pattern 52B. ｉ " indicates the distance between the magnetization lines 54B1a and 54A1a at corresponding positions when the servo read element SR4 crosses the servo pattern 52B and the servo pattern 52A adjacent to the servo pattern 52B on the forward side along the longitudinal direction LD.

[0216] "A ｉ " and "B ｉ " is measured based on the servo pattern signal obtained by reading the servo pattern 52 with the servo read element SR4 of the verify head VH.

[0217] When the center position of the width direction WD of the servo pattern 52 (for example, the position where the imaginary line C3 passing through the center of the width direction WD of the servo pattern 52 along the longitudinal direction LD intersects with the servo pattern 52) is set to "0", the position within the servo pattern 52 closer to the first direction WD1 than the imaginary line C3 is represented by a positive value, and the position within the servo pattern 52 closer to the second direction WD2 than the imaginary line C3 is represented by a negative value.

[0218] 16, two servo bands SB that straddle one servo band SB in the width direction WD in the magnetic tape MT on which a plurality of servo bands SB are formed by the above-described servo pattern recording process, i.e., a pair of servo patterns 52 adjacent in the width direction WD included in two servo bands SB (here, as an example, servo bands SB1 and SB3) that are not adjacent in the width direction WD in the magnetic tape MT on which a plurality of servo bands SB are formed by the above-described servo pattern recording process, are read by a servo read element SR4 used for each servo band SB (here, as an example, servo bands SB1 and SB3). Then, a plurality of dPESs are measured based on the servo pattern signals obtained by reading each servo pattern 52 (here, as an example, each of the pair of servo patterns 52 adjacent in the width direction WD included in servo bands SB1 and SB3).

[0219] For ease of explanation, two servo bands SB that straddle one servo band SB in the width direction WD in the magnetic tape MT on which a plurality of servo bands SB are formed by the servo pattern recording process described above (i.e., two servo bands SB that are not adjacent in the width direction WD in the magnetic tape MT on which a plurality of servo bands SB are formed by the servo pattern recording process described above) will also be referred to as a "servo band pair." For ease of explanation, a pair of servo patterns 52 adjacent in the width direction WD included in the servo band pair will also be referred to as a "servo pattern pair."

[0220] Here, if the PES measured for one servo pattern 52 included in the servo pattern pair (for example, the upper servo pattern 52 shown in FIG. 16) is defined as PES1, and the PES measured for the other servo pattern 52 included in the servo pattern pair (for example, the lower servo pattern 52 shown in FIG. 16) is defined as PES2, then 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 spacing between the two servo read elements SR4 used for the servo band pair (hereinafter also referred to as the "servo read element pair") is at the design center, then dPES will be "0."

[0221] The inspection process requires inspection of the linearity of the servo pattern 52. As will be described in detail later, a plurality of PESs and a plurality of dPESs are measured at a plurality of 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, a PES difference gap ΔdPES is measured from the plurality of PESs and the plurality of dPESs.

[0222] 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 a servo pattern pair recorded at corresponding positions in the width direction WD in the 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 a servo pattern pair recorded at corresponding positions in the width direction WD in the servo band pair, i.e., the lower servo pattern 52 shown in Fig. 16.

[0223] In a linear magnetization region 54A1 (e.g., a magnetization straight line 54A1a located at the most upstream side in the forward direction) included in one servo pattern 52, 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 have a predetermined corresponding relationship. The first positions 74 and the second positions 76, which are in a corresponding positional relationship to each other, are set on the linear magnetization region 54A1 with an interval INT1 between them in the width direction WD. Furthermore, the first positions 74 and the second positions 76, which are in a corresponding positional relationship 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. In this embodiment, for convenience of explanation, it is assumed that "interval INT1 = distance Dr" and "interval INT2 = pitch Tp".

[0224] This is merely an example, and the technology of the present disclosure is valid even if "interval INT1 ≒ distance Dr" and "interval INT2 ≒ pitch Tp." In this embodiment, interval INT1 is an example of a "first predetermined interval" according to the technology of the present disclosure. Interval INT2 is an example of a "second predetermined interval" according to the technology of the present disclosure.

[0225] Between the interval INT1 and the pitch Tp, there is a magnitude relationship of "interval INT1 > pitch Tp." Furthermore, between the interval INT1 and the interval INT2, there is a magnitude relationship of "interval INT1 > interval INT2." Furthermore, the 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 the interval INT2 (for example, a natural number multiple of 2 or greater), and refers to an interval that is equivalent to half the difference between the length L1 (see FIG. 11 ) and the pitch Tp. Here, 1200 nm (nanometers) is used as an example of the interval INT1, and 400 nm is used as an example of the interval INT2.

[0226] 16, when the variable n is a natural number equal to or greater than 3, the dPES is roughly divided into dPES(n) and dPES(n-3). In this embodiment, dPES(n-3) is an example of a "first PES difference" according to the technology of the present disclosure. Also, in this embodiment, dPES(n) is an example of a "second PES difference" according to the technology of the present disclosure.

[0227] In a linearity inspection method (e.g., step ST12 included in the linearity inspection method shown in FIG. 14 ), dPES(n−3) is measured by using the PES at one first position 74 and the PES at the other first position 74 of a pair of first positions 74 that are in a corresponding positional relationship in the servo pattern pair. More specifically, dPES(n−3) is measured by using the PES at one first position 74 and the PES at 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.

[0228] In a linearity inspection method (e.g., step ST12 included in the linearity inspection method shown in FIG. 14 ), dPES(n) is measured by using the PES at one second position 76 and the PES at the other second position 76 of a pair of second positions 76 that are in a corresponding positional relationship in the servo pattern pair. More specifically, dPES(n) is measured by using the PES at one second position 76 and the PES at 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.

[0229] In a linearity inspection method (for example, step ST12 included in the linearity inspection method shown in FIG. 14 ), multiple ΔdPESs are measured from multiple dPESs(n−3) and multiple dPESs(n). ΔdPES is the difference between the corresponding dPESs(n−3) and dPESs(n). The corresponding dPESs(n−3) and dPESs(n) refer to the dPESs(n−3) and dPESs(n) for a first position 74 and a second position 76 that are spaced apart by an interval INT1 along the width direction WD. In this embodiment, ΔdPES is an example of a “PES difference gap” according to the technology of the present disclosure.

[0230] In this embodiment, the interval INT2 is one step, and the variable n corresponds to the number of measurement steps. In this embodiment, 1200 nm is used as an example of the interval INT1, and 400 nm is used as an example of the interval INT2. ΔdPES is calculated using the dPES value at a measurement step position that is 3 apart, 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 by one measurement step along the second direction WD2. That is, the 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. When the pair of first positions 74 and the pair of second positions 76 are updated, dPES(n-3) is measured for the updated pair of first positions 74, and dPES(n) is measured for the updated pair of second positions 76. Then, every time dPES(n-3) and dPES(n) are measured, ΔdPES (i.e., the difference between dPES(n-3) and dPES(n)) is calculated from the measured dPES(n-3) and dPES(n).

[0231] Thus, in the example shown in Figure 16, in the servo pattern pair, for a pair of linear magnetization regions 54A1 adjacent in the width direction WD, ΔdPES is measured at intervals INT2 along the second direction WD2, thereby obtaining multiple ΔdPES.

[0232] In addition, in a similar manner to the way in which 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 the 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 the servo pattern pair (for example, the magnetization line 54A2a located at the most upstream side in the forward direction in one of the pair of linear magnetization regions 54A2, and the magnetization line 54A2a located at the most upstream side in the forward direction in the other of the pair of linear magnetization regions 54A2). Furthermore, in a similar manner to the way in which a plurality of dPES(n) and a plurality of dPES(n-3) are measured for a plurality of first positions 74 and a plurality of second positions 76 on a pair of linear magnetization regions 54A1 included in the servo pattern pair, a plurality of dPES(n) and a plurality of dPES(n-3) are also measured for a plurality of first positions 74 and a plurality of second positions 76 on a pair of linear magnetization regions 54A2 included in the servo pattern pair. Furthermore, in a similar manner to the way in which a plurality of ΔdPESs are measured from the plurality of dPES(n) and a plurality of dPES(n-3) measured for the plurality of first positions 74 and a plurality of second positions 76 on a pair of linear magnetization regions 54A1 included in the servo pattern pair, a plurality of ΔdPESs are also measured from the plurality of dPES(n) and a plurality of dPES(n-3) measured for the plurality of first positions 74 and a plurality of second positions 76 on a pair of linear magnetization regions 54A2 included in the servo pattern pair.

[0233] Furthermore, in a similar manner to the way in which 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 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. Furthermore, in a similar manner to the way in which a plurality of dPES(n) and a plurality of dPES(n-3) are measured for the plurality of first positions 74 and the plurality of second positions 76 on a pair of servo patterns 52A included in the 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 the plurality of second positions 76 of a pair of servo patterns 52B adjacent in the width direction WD. Furthermore, in a similar manner to the way in which multiple ΔdPESs are measured from multiple dPESs (n) and multiple dPESs (n-3) measured at multiple first positions 74 and multiple second positions 76 on a pair of servo patterns 52A included in a servo pattern pair, multiple ΔdPESs are also measured from multiple dPESs (n) and multiple dPESs (n-3) measured at multiple first positions 74 and multiple second positions 76 on a pair of servo patterns 52B adjacent in the width direction WD.

[0234] Incidentally, if there is no deformation in the width direction WD of the magnetic tape MT and the linearity of the servo pattern 52 is ideal, but the spacing between the servo read element pair (i.e., the spacing between one servo read element SR4 of the servo read element pair and the other servo read element SR4 in the width direction WD) is deviated from the design center, dPES will be a value corresponding to the amount by which the spacing between the servo read element pair is deviated from the design center. Also, if the magnetic tape MT is deformed in the width direction WD, dPES will be a value corresponding to the amount of deformation of the magnetic tape MT in the width direction WD.

[0235] However, by measuring ΔdPES (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 servo read element pairs is shifted from the design center are offset.

[0236] Specifically, dPES includes a value corresponding to the amount of deviation of the spacing between the servo read element pairs 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. However, for example, if there is no deformation in the width direction WD of the magnetic tape MT and there is deviation from the design value of the spacing between the servo read element pairs, both dPES(n) and dPES(n-3) include deviation from the design value of the spacing between the same servo read element pairs, and therefore, by calculating the difference between dPES(n) and dPES(n-3), the amount of deviation from the design value of the spacing between the pair of servo read elements SR is canceled out, and only the value indicating the linearity of the servo pattern 52 is calculated. Using the same concept, even if the magnetic tape MT is deformed in the width direction WD, it can be assumed that the magnetic tape MT is deformed in the same way at the first position 74 and the second position 76. Therefore, by similarly calculating the difference between dPES(n) and dPES(n-3), the amount of deformation in the width direction WD of the magnetic tape MT is canceled out, and only the value indicating the linearity of the servo pattern 52 is calculated. Therefore, the linearity of the servo pattern 52 is expressed by a plurality of ΔdPESs measured from a plurality of dPES(n) and a plurality of dPES(n-3) corresponding to a plurality of first positions 74 and a plurality of second positions 76.

[0237] Therefore, in step ST12 included in the linearity inspection method shown in Fig. 14, an index is obtained based on a plurality of ΔdPESs. Below, specific examples of a method for obtaining an index based on a plurality of ΔdPESs and a method for inspecting the linearity of the servo pattern 52 of the magnetic tape MT using the index will be described.

[0238] 17, when the data reproduction element DR having a length β1 of 350 nm is placed on the divided data track DT_N so that its center in the width direction WD coincides with the center in the width direction WD of the divided data track DT_N having a pitch Tp of 500 nm, margins BS1 and BS2 are generated between the divided data track DT_N and the data reproduction element DR. The margin BS1 is a margin generated on the first direction WD1 side, and the margin BS2 is a margin generated on the second direction WD2 side.

[0239] The length of the margin BS1 in the width direction WD and the length of the margin BS2 in the width direction WD each correspond to 15% of the pitch Tp.

[0240] 14, the average value μ and standard deviation σ of the plurality of ΔdPESs measured from the servo pattern pairs are calculated. The standard deviation σ represents the degree of linearity of the servo pattern 52. The linearity of the servo pattern 52 increases as the standard deviation σ decreases. Therefore, in the servo pattern recording step described above, it is preferable that the servo pattern 52 be recorded on the magnetic tape MT so that the standard deviation σ is as small as possible.

[0241] 17 shows a graph 78. The graph 78 is a graph showing a normal distribution obtained from the mean value μ and the standard deviation σ. If the total area of ​​the closed region surrounded by the graph 78 is taken as 100%, then ΔdPES exists in the σ section with a probability of 68.3%, ΔdPES exists in the 2σ section with a probability of 95.4%, and ΔdPES exists in the 3σ section with a probability of 99.7%.

[0242] 14, 3σ is calculated from the standard deviation σ. 3σ is an index showing the degree to which multiple ΔdPESs vary from the average value μ. 3σ decreases as the standard deviation σ decreases, and the smaller 3σ, the higher the linearity of the servo pattern 52. The higher the linearity of the servo pattern 52, the easier it is for the data recording element DW to record data at a location on the magnetic tape MT intended by a user, and the easier it is for the data reproducing element DR to be on-track with the divided data track DT_N.

[0243] Therefore, in order to make it easier for the user or the like to record data at the location on the magnetic tape MT and to make it easier for the data reproduction element DR to be on-track with the divided data track DT_N, in step ST14 included in the linearity inspection method shown in Fig. 14, it is determined whether or not the linearity determination condition that "3σ is within 15% of the pitch Tp" is satisfied. This is because if 3σ is within 15% of the pitch Tp, it can be expected that the data reproduction element DR will be on-track with the divided data track DT_N with a probability of 99.7%.

[0244] If the linearity judgment condition is satisfied, the linearity of the servo pattern 52 is judged to be within an acceptable range, and if the linearity judgment condition is not satisfied, the linearity of the servo pattern 52 is judged to be outside the acceptable range. A magnetic tape MT whose linearity of the servo pattern 52 is judged to be within the acceptable range is adopted, and a magnetic tape MT whose linearity of the servo pattern 52 is judged to be outside the acceptable range is not adopted. Furthermore, if the linearity of the servo pattern 52 is judged to be within the acceptable range, 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, by a servo pattern recording head WH with improved linearity of the gap pattern G).

[0245] In this embodiment, the standard deviation σ is an example of a "standard deviation" according to the technology of the present disclosure. Also, in this embodiment, 3σ is an example of an "index" and a "value equivalent to three times the standard deviation of a plurality of PES difference gaps" according to the technology of the present disclosure.

[0246] 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 ΔdPESs obtained from a magnetic tape MT manufactured by a conventionally known technique without using linearity judgment conditions, and a distribution of multiple ΔdPESs 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.

[0247] 18, the distribution of dPESs obtained from a magnetic tape MT manufactured through a process in which the linearity of the servo patterns 52 is determined to be within an acceptable range using the linearity determination conditions is more coherent than the distribution of dPESs obtained from a magnetic tape MT manufactured by a conventionally known technique without using the linearity determination conditions, i.e., the dPESs have less variation.

[0248] 19, the distribution of multiple ΔdPESs obtained from a magnetic tape MT manufactured through a process in which the linearity of the servo patterns 52 is determined to be within an acceptable range using the linearity determination conditions is more uniform than the distribution of multiple ΔdPESs obtained from a magnetic tape MT manufactured by a conventionally known technique without using the linearity determination conditions. In other words, the ΔdPESs have less variation.

[0249] 20A shows an example of a distribution of a plurality of ΔdPESs obtained under the first condition shown in Table 1. FIG. 20B shows an example of a distribution of a plurality of ΔdPESs obtained under the second condition shown in Table 2.

[0250]

[0251]

[0252] 20A and 20B, the distribution of the plurality of ΔdPESs obtained under the first condition is more coherent than the distribution of the plurality of ΔdPESs obtained under the second condition. In other words, the ΔdPESs have less variation.

[0253] Table 3 shows the 3σ 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 3σ values ​​obtained when the magnetic tape MT was manufactured using the first head, the second head, and the third head under the second condition.

[0254] The first head is a servo pattern recording head according to conventionally known technology, in which the openings of the gap pattern G are formed by MEMS processing. The second head is a servo pattern recording head WH in which the openings of the gap pattern G are formed by the second method described above (a method in which grooves 71 are formed by trimming the entire width of the opening 66A shown in FIG. 13 using an FIB or a laser, and then non-magnetic material 68 is filled in the grooves 71). The third head is a servo pattern recording head obtained by MEMS processing the openings of the gap pattern G under processing conditions different from those used in the MEMS processing performed on the openings of the gap pattern G of the first servo pattern recording head.

[0255]

[0256]

[0257] Next, the operation of the magnetic tape system 10 according to this embodiment will be described.

[0258] First, we will explain the case where the first recording module DWM1 simultaneously records data on data bands DB1 and DB2 by forming multiple data tracks DT between servo bands SB on a magnetic tape MT that has been determined to have linearity within the acceptable range (i.e., satisfying the linearity judgment conditions) using the linearity inspection method.

[0259] 21, first, a pair of first servo read elements SRa (hereinafter simply referred to as the "pair of first servo read elements SRa") included in the servo read element pair are positioned on the servo band pair. Specifically, one of the pair of first servo read elements SRa (hereinafter also referred to as the "one first servo read element SRa") is positioned on servo band SB3, and 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 SB1. More specifically, the magnetic head 28 is moved in the width direction WD so that one of the first servo read elements SRa is positioned on path Pa1 of servo band SB3 and the other first servo read element SRa is positioned on path Pa1 of servo band SB1, thereby positioning the first recording module DWM1 on the magnetic tape MT.

[0260] In this state, the magnetic tape MT is run in the forward direction, and each data recording element DW1 of the first recording module DWM1 performs a recording process. As a result, as shown in Figure 22 as an example, divided data tracks DT_1 are formed on the magnetic tape MT by each data recording element DW1 of the first recording module DWM1.

[0261] After the divided data track DT_1 is formed, the magnetic tape MT is run in the reverse direction, returning the first recording module DWM1 to the position where the formation of the divided 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, causing each data recording element DW1 of the first recording module DWM1 to perform a recording process. As a result, the divided data track DT_2 is formed on the magnetic tape MT by each data recording element DW1 of the first recording module DWM1.

[0262] In the same manner as the divided data tracks DT_1 and DT_2 were sequentially formed, divided data tracks DT_3 to DT_12 are sequentially formed by each data recording element DW1 of the first recording module DWM1, whereby, as shown in Fig. 23 for example, a data band DB2 including data tracks DT1 to DT8 is formed between the servo bands SB2 and SB3 in the width direction WD, and a data band DB1 including data tracks DT1 to DT8 is formed between the servo bands SB2 and SB1 in the width direction WD.

[0263] When the divided data tracks DT_1 to DT_12 are formed sequentially, the first servo read element SRa is positioned sequentially on paths Pa1 to Pa12 that are set at pitches Tp from the first direction WD1 to the second direction WD2 with respect to the plurality of 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 the paths Pa1 to Pa12, and servo control is performed in accordance with the servo pattern signals thus obtained.

[0264] Next, a case will be described in which the playback module DRM sequentially plays back data from divided data tracks DT_1 to DT_12 included in each data track DT.

[0265] 24 and 25, paths Pb1 to Pb12 are set at pitches Tp from the first direction WD1 to the second direction WD2 in the servo patterns 52 included in the servo band SB. The paths Pb1 to Pb12 correspond to the paths Pa1 to Pa12, and each of the paths Pb1 to Pb12 is set at a position shifted by a distance Dr toward the first direction WD1 from each of the paths Pa1 to Pa12.

[0266] 24, first, a pair of second servo read elements SRb (hereinafter simply referred to as "a pair of second servo read elements SRb") included in the servo read element pair are positioned on the servo band pair. Specifically, 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, and the other of the pair of second servo read elements SRb (hereinafter referred to as "the other second servo read element SRb") is positioned on servo band SB1. More specifically, 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 SB1, thereby positioning the playback module DRM on the magnetic tape MT.

[0267] In this state, the magnetic tape MT is run in the forward direction, and each data reproducing element DR of the reproducing module DRM performs a reproducing process, whereby data is reproduced from the divided data track DT_1 on the magnetic tape MT by each data reproducing element DR of the reproducing module DRM.

[0268] After the data from the divided data track DT_1 has been reproduced, the magnetic tape MT is run in the reverse direction, returning the playback module DRM to the position where the data from the divided data track DT_1 was 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, causing each data reproduction element DR of the playback module DRM to perform a playback process. As a result, data from the divided data track DT_2 on the magnetic tape MT is reproduced by each data reproduction element DR of the playback module DRM.

[0269] In the same manner as data is sequentially reproduced from divided data tracks DT_1 and DT_2, data is sequentially reproduced from divided data tracks DT_3 to DT_12 by each data reproducing element DR of the reproduction module DRM.

[0270] In the example shown in Figure 25, one second servo read element SRb is located on the path Pb12 of the servo band SB3, and the other second servo read element SRb is located on the path Pb12 of the servo band SB1. In this state, the magnetic tape MT is run in the forward direction, and each data reproducing element DR of the reproducing module DRM performs a reproducing process. As a result, data is reproduced from the divided data track DT_12 on the magnetic tape MT by each data reproducing element DR of the reproducing module DRM.

[0271] Here, an example is given in which data is reproduced from split data tracks DT_1 to DT_12 sequentially from split data track DT_1 to split data track DT_12, but this is merely one example, and data may be reproduced sequentially from split data track DT_12 to split data track DT_1, or data may be reproduced from split data track DT_N specified by a user, etc.

[0272] 22 to 25, the divided data tracks DT_1 to DT_12 are overlapped along the second direction WD2 by sequential shifts of pitch Tp. However, the technology of the present disclosure is not limited to this. For example, as shown in FIG. 26, multiple divided data tracks DT_N may be overlapped along the first direction WD1 using the SMR method. In this case, a second recording module DWM2 is used. Specifically, a pair of third servo read elements SRc (hereinafter simply referred to as the "pair of third servo read elements SRc") included in the servo read element pair are sequentially moved from path Pa12 to path Pa1, and the magnetic tape MT is run in the reverse direction. As the pair of third servo read elements SRc moves along path P, the pair of third servo read elements SRc reads the servo pattern 52. The magnetic head 28 is moved in the first direction WD1 in accordance with the servo pattern signal thus obtained, and the divided data tracks DT_12 to DT_1 are sequentially superimposed in the first direction WD1.

[0273] In this case, too, data reproduction from 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 is reproduced from divided data tracks DT_1 to DT_12, second servo read element SRb reads servo pattern 52 using paths Pb1 to Pb12, and servo control is performed in accordance with the servo pattern signal obtained thereby.

[0274] Here, an example is given in which data is reproduced from split data tracks DT_1 to DT_12 sequentially from split data track DT_1 to split data track DT_12, but this is merely one example, and data may be reproduced sequentially from split data track DT_12 to split data track DT_1, or data may be reproduced from split data track DT_N specified by a user, etc.

[0275] As described above, in this embodiment, in the inspection process included in the manufacturing method of the magnetic tape MT, 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 Figure 14) (see step ST14 shown in Figure 14).

[0276] In this embodiment, a plurality of ΔdPESs are measured (see FIG. 16) to check the linearity of the servo pattern 52. ΔdPES is the difference between dPES(n-3) and dPES(n) (see FIG. 16).

[0277] 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 recorded at corresponding positions in the width direction WD between one servo band SB (e.g., servo band SB3) and the other servo band SB (e.g., servo band SB1) of the servo band pair (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 recorded at corresponding positions in the width direction WD between one servo band SB (e.g., servo band SB3) and the other servo band SB (e.g., servo band SB1) of the servo band pair (see FIG. 16).

[0278] The plurality of ΔdPESs are obtained by measuring the ΔdPESs at intervals INT2 in the width direction WD in a pair of servo patterns 52. In this embodiment, to inspect the linearity of the servo patterns 52, the degree to which the plurality of ΔdPESs vary from the average value of the plurality of ΔdPESs is obtained as an index indicating the nonlinearity of the servo patterns 52 (see step ST12 in FIG. 14). Then, the index indicating the nonlinearity of the servo patterns 52 is used to inspect the linearity of the servo patterns 52 on the magnetic tape MT (see step ST14 in FIG. 14).

[0279] In this embodiment, if 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 ), it is determined that the linearity of the servo pattern 52 of the magnetic tape MT is within the allowable range (i.e., there is no problem with the linearity of the servo pattern 52 used for servo control). On the other hand, if 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 ). Having the index within 15% of the pitch Tp enables more accurate servo control than when the index exceeds 15% of the pitch Tp. This means that it is possible to form a plurality of divided data tracks DT_N with high accuracy and to perform highly accurate tracking of the data reproducing element DR with respect to the divided data tracks DT_N.

[0280] In this way, by determining whether the index indicating the nonlinearity of the servo patterns 52 satisfies the condition that the index indicating the nonlinearity of the servo patterns 52 is within 15% of the pitch Tp, it becomes possible to adopt as the magnetic tape MT for shipment only the magnetic tape MT on which only a plurality of servo patterns 52 that satisfy the condition that the index indicating the nonlinearity of the servo patterns 52 is within 15% of the pitch Tp is recorded. By adopting the magnetic tape MT for shipment in which the linearity of the servo patterns 52 is guaranteed to such a high level, it is possible to 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.

[0281] In particular, in this embodiment, it is determined whether or not the index indicating the nonlinearity of the servo patterns 52 included in the two servo bands SB (i.e., servo bands SB1 and SB3) that straddle the servo band SB2 satisfies the condition that the index is within 15% of the pitch Tp. As a result, a magnetic tape MT in which the linearity of the servo patterns 52 included in the two servo bands SB (i.e., servo bands SB1 and SB3) that straddle the servo band SB2 is guaranteed can be used as the magnetic tape MT for shipping. Therefore, the magnetic tape MT for shipping that is used in this manner can contribute to improving the accuracy of simultaneously recording data to the data bands DB1 and DB2 (in other words, the accuracy of recording data in parallel to the data bands DB1 and DB2) and the accuracy of simultaneously reproducing data from the data bands DB1 and DB2 (in other words, the accuracy of reproducing data in parallel from the data bands DB1 and DB2).

[0282] In addition, in this embodiment, the index obtained for the servo band pair (i.e., servo bands SB1 and SB3) included in the magnetic tape MT is within 15% of the pitch Tp. Therefore, compared to when the index obtained from adjacent servo bands SB in the width direction WD (e.g., servo bands SB2 and SB3) 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 over a wide range in the width direction WD of the magnetic tape MT (data bands DB1 and DB2 in this embodiment).

[0283] Furthermore, in this embodiment, a plurality of divided data tracks DT_N are formed on the magnetic tape MT by recording data by the SMR method in accordance with a plurality of servo patterns 52 on a magnetic tape MT that satisfies the condition that an 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, it is possible to guarantee a high level of quality for the plurality of divided data tracks DT_N that are formed by recording data on the magnetic tape MT by the SMR method, and it is also possible to reproduce data from the plurality of divided data tracks DT_N with high accuracy.

[0284] In particular, in this embodiment, a plurality of divided data tracks DT_N are formed on the magnetic tape MT by recording data by the SMR method according to a plurality of servo patterns 52 on the magnetic tape MT that satisfies the condition that an index indicating the nonlinearity of the servo patterns 52 included in a servo band pair (i.e., servo bands SB1 and SB3) included in the magnetic tape MT is within 15% of the pitch Tp. Therefore, compared to when data is recorded by the SMR method on the magnetic tape MT that satisfies the condition that an index obtained from adjacent servo bands SB in the width direction WD (e.g., servo bands SB2 and SB3) is within 15% of the pitch Tp, the quality of the plurality of divided data tracks DT_N formed by recording data on the magnetic tape MT by the SMR method can be guaranteed at a high level over a wide range in the width direction WD of the magnetic tape MT (data bands DB1 and DB2 in this embodiment), and data can be reproduced accurately from the plurality of divided data tracks DT_N.

[0285] In this embodiment, the mean value μ and standard deviation σ of the plurality of ΔdPESs are calculated. Then, as an index of the nonlinearity of the servo patterns 52, 3σ of a graph 78 (see FIG. 17 ) showing a normal distribution obtained from the mean value μ and standard deviation σ is used (see FIG. 17 ). ΔdPES exists in the closed region of 3σ in the graph 78 with a probability of 99.7%. In this embodiment, by determining whether or not the condition that 3σ is within 15% of the pitch Tp is satisfied, it becomes possible to adopt, as the magnetic tape MT for shipment, a magnetic tape MT on which only a plurality of servo patterns 52 that satisfy the condition that 3σ is within 15% of the pitch Tp are recorded. Adopting a magnetic tape MT with such a high level of guaranteed linearity of the servo patterns 52 as the magnetic tape MT for shipment contributes to improving the accuracy of recording data on the magnetic tape MT and the accuracy of reproducing data recorded on the magnetic tape MT.

[0286] In particular, in this embodiment, a magnetic tape MT on which only a plurality of servo patterns 52 are recorded, which satisfy the condition that 3σ obtained from a pair of servo bands (i.e., servo bands SB1 and SB3) included in the magnetic tape MT is within 15% of the pitch Tp, can be adopted as the magnetic tape MT for shipment. Therefore, the magnetic tape MT for shipment adopted in this manner 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 over a wide range in the width direction WD of the magnetic tape MT (data bands DB1 and DB2 in this embodiment), compared to a magnetic tape MT on which only a plurality of servo patterns 52 are recorded, which satisfy the condition that 3σ obtained from adjacent servo bands SB in the width direction WD (e.g., servo bands SB2 and SB3) is within 15% of the pitch Tp.

[0287] Furthermore, in this embodiment, the interval INT1 (see FIG. 16) used in measuring ΔdPES (see FIG. 16) 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 that corresponds to half the difference between the length L1 (see FIG. 11) and the pitch Tp (see FIG. 10). Therefore, compared to a case where the interval INT1 is determined independently of the length L1 and the pitch Tp, even if the density of the multiple divided data tracks DT_N is increased, the data reproduction element DR can be placed on track with high precision on each of the multiple divided data tracks DT_N during data reproduction.

[0288] In this embodiment, the interval INT1 (see FIG. 16) used to measure ΔdPES (see FIG. 16) is three times the interval INT2 (see FIG. 16). Therefore, it is possible to collect just the right number of ΔdPES (see FIG. 16) to obtain an index showing the nonlinearity of the servo pattern 52.

[0289] The interval INT1 (see FIG. 16) 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. When 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 influence of the distortion is kept relatively small. Conversely, when the distance Dr is long, the influence of the distortion becomes relatively large, and the position deviation due to the distortion becomes large.

[0290] Assuming that data is recorded on a magnetic tape MT using the SMR method, the difference between the position of the first servo read element SRa when a divided data track DT_1 is formed by the first data recording and the position of the second servo read element SRb when a divided data track DT_2 is formed by the second data recording corresponds to the pitch Tp.

[0291] If the distance Dr during data reproduction (see Figures 11, 24 and 25) is shorter than the pitch Tp (see Figures 10 and 23 to 25), the influence of positional deviation during data reproduction will be within the range of the influence of positional deviation during data recording, and the influence of the linearity of the servo pattern 52 will be reduced.

[0292] Conversely, if the distance Dr during data reproduction is greater than the pitch Tp, the effect of misalignment during data reproduction will not be contained within the range of the effect of misalignment during data recording, and the linearity of the servo pattern 52 will be significantly affected, which will lead to a deterioration in servo control performance.

[0293] Therefore, in this embodiment, an interval INT1 (see FIG. 16 ), which is an interval corresponding to the distance Dr, is set to an interval greater than the pitch Tp. As a result, servo pattern 52 is formed so that an index (e.g., 3σ) indicating the degree of variation in the multiple ΔdPESs determined based on interval INT1, which is greater than the pitch Tp, falls within 15% of the pitch Tp. Therefore, compared to when interval INT1 is equal to or less than pitch Tp, even if the multiple divided data tracks DT_N are arranged at a higher density, data reproduction element DR can be positioned on track with high precision on each of the multiple divided data tracks DT_N during data reproduction.

[0294] In the above embodiment, the index (e.g., 3σ) obtained for each servo band pair (e.g., each servo band SB1 and SB3) is set to 15% or less of the pitch Tp, but the technology of the present disclosure is not limited to this. For example, the index obtained for each servo band pair (e.g., each servo band SB1 and SB3) may be set to 10% or less of the pitch Tp, or the index obtained for each servo band pair (e.g., each servo band SB1 and SB3) may be set to 5% or less of the pitch Tp. In the example shown in FIG. 17, the length β1 is 500 nm, but if the index is set to 10% or less of the pitch Tp, the length β1 can be extended to 400 nm, and if the index is set to 5% or less of the pitch Tp, the length β1 can be extended to 450 nm. If the length β1 can be extended in this way, improvement in data reproduction performance can be expected. In addition, PES due to fluctuations in the width direction WD of the magnetic tape MT can also be a factor in positional deviation of the data reproduction element DR, but by keeping the index within 10% of the pitch Tp or within 5% of the pitch Tp, it is possible to design with increased tolerance for positional deviation due to PES.

[0295] In the above embodiment, the divided data tracks DT_1 to DT_12 are overlapped sequentially along the second direction WD2 by a pitch Tp. However, the technology disclosed herein is not limited to this. For example, as shown in FIG. 26 , multiple divided data tracks DT_N may be overlapped along the first direction WD1 using the SMR method. In this case, a second recording module DWM2 is used. Specifically, the pair of third servo read elements SRc is sequentially moved from path P12 to path P1, and the magnetic tape MT is run in the reverse direction. As the pair of third servo read elements SRc moves along path P, the pair of third servo read elements SRc reads the servo pattern 52. The magnetic head 28 is then moved along the first direction WD1 in accordance with the servo pattern signal obtained thereby, and the divided data tracks DT_12 to DT_1 are sequentially overlapped along the first direction WD1. The data from the divided data tracks DT_1 to DT_12 is reproduced by each data reproducing element DR of the reproduction module DRM.

[0296] In the examples shown in Figures 24 and 25, 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.

[0297] Recently, research into techniques for reducing the effects of TDS has been progressing. TDS is influenced by temperature, humidity, the pressure with which the magnetic tape is wound around the reel, and deterioration over time, and it is known that if no countermeasures are taken, TDS will increase, causing off-track (i.e., misalignment of the data read / write element DRW with respect to the divided data tracks DT_N in the data band DB) when magnetic processing is performed on the data band DB.

[0298] For example, if the width of the magnetic tape MT shrinks over time, it may go off-track. Off-track refers to a state in which the data recording / 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 / reproducing element DRW in the width direction WD).

[0299] The width of the magnetic tape MT may expand, and in this case, there is also 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 predetermined position determined by design (i.e., the predetermined position determined by design for each of the linear magnetized regions 54A1, 54A2, 54B1, and 54B2). If the position of the servo read element SR relative to the servo pattern 52 deviates in the width direction WD from the predetermined 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 (e.g., a designated divided data track DT_N among the divided data tracks DT1_1, DT1_2, DT1_3, DT1_4, ..., DT1_11, and DT1_12). As a result, magnetic processing is not performed on the divided data track DT_N as originally planned.

[0300] One possible method for reducing the effects of TDS is to adjust the width of the magnetic tape MT by adjusting the tension applied to the magnetic tape MT. However, if the deformation of the magnetic tape MT in the width direction WD is too great, adjusting the tension applied to the magnetic tape MT may not eliminate off-track. Furthermore, if the tension applied to the magnetic tape MT is too strong, the load on the magnetic tape MT increases, which may shorten the life of the magnetic tape MT. Furthermore, if 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. As an example of a method for reducing the effects of TDS other than adjusting the tension applied to the magnetic tape MT, as shown in FIG. 27, there is a known method for skewing the magnetic head 28 on the magnetic tape MT to maintain the position of the servo read element SR relative to the servo pattern 52 at a predetermined position determined by design.

[0301] 27, the first recording module DWM1 may be arranged around the rotation axis RA1 and tilted relative to the width direction WD along the surface 31 of the magnetic tape MT. The playback module DRM may be arranged around the rotation axis RA2 and tilted relative to the width direction WD along the surface 31 of the magnetic tape MT. Furthermore, the second recording module DWM2 may be arranged around the rotation axis RA3 and tilted relative to the width direction WD along the surface 31 of the magnetic tape MT.

[0302] In the example shown in Figure 27, 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 Figure 11). Also, in the example shown in Figure 27, the length β2 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 β1 (see Figure 1). Also, the positions of the first servo read element SRa in the width direction WD, the second servo read element SRb in the width direction WD, and the third servo read element SRc in the width direction WD are aligned.

[0303] The orientations of the first recording module DWM1, the playback module DRM, and the second recording module DWM2 relative to 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). To change the orientations of the first recording module DWM1, the playback module DRM, and the second recording module DWM2 relative to the width direction WD, a tilting mechanism (not shown) that operates under the control of the processing device 30 is used. The tilting mechanism is mechanically connected to the first recording module DWM1, the playback module DRM, and the second recording module DWM2. In this case, the tilting mechanism adjusts the degree of tilt of the first recording module DWM1, the playback module DRM, and the second recording module DWM2 relative to the width direction WD depending on the situation, under the control of the processing device 30.

[0304] For example, 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 can be adjusted by rotating the first recording module DWM1 on the surface 31 along the surface 31 with the rotation axis RA1 as the central axis, rotating the playback module DRM on the surface 31 along the surface 31 with the rotation axis RA2 as the central axis, and rotating the second recording module DWM2 on the surface 31 along the surface 31 with the rotation axis RA3 as the central axis.

[0305] Here, we have given an example in which the first recording module DWM1, the playback module DRM, and the second recording module DWM2 are individually controlled to rotate by tilting mechanisms, but this is merely one example, and the entire magnetic head 28 may also be rotated by a single tilting mechanism with the rotation axis RA2 as the central axis.

[0306] By tilting the recording module DWM and the reproduction module DRM with respect to the width direction WD along the surface 31 of the magnetic tape MT, a certain deviation occurs in the width direction WD among 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. In this case, the positions at which the servo patterns 52 are read by each of the first servo read element SRa, the second servo read element SRb, and the third servo read element SRc (in other words, the path P) may be adjusted according to an adjustment amount determined based on the certain deviation occurring in the width direction WD.

[0307] In this way, by arranging the recording module DWM and the playback module DRM in an attitude inclined 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 due to 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 a planned position or data cannot be reproduced from a planned position due to deformation of the magnetic tape MT.

[0308] In the above embodiment, the magnetic tape system 10 is exemplified as one in which the magnetic tape cartridge 12 is freely insertable into and removable from the magnetic tape drive 14, but the technology of the present disclosure is not limited to this. For example, 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 a 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.

[0309] In the above embodiment, a single magnetic head 28 is illustrated, but the technology of the present disclosure is not limited to this. For example, a plurality of magnetic heads 28 may be arranged above the magnetic tape MT.

[0310] 27, when the recording module DWM and the playback module DRM are tilted relative to the width direction WD along the surface 31 of the magnetic tape MT, the angle formed by the linear magnetized region 54A1 and the servo read element SR differs from the angle formed by the linear magnetized region 54A2 and the servo read element SR in the linear magnetized region pair 54A. When the angles differ in this way, variations (e.g., variations in signal level and waveform distortion) due to azimuth loss occur between the servo pattern signal derived from the linear magnetized region 54A1 (i.e., the servo pattern signal obtained by reading the linear magnetized region 54A1 with the servo read element SR) and the servo pattern signal derived from the linear magnetized region 54A2 (i.e., the servo pattern signal obtained by reading the linear magnetized region 54A2 with the servo read element SR).

[0311] As shown in Figure 27, when the recording module DWM and the playback module DRM are tilted relative to the width direction WD along the surface 31 of the magnetic tape MT, the angle formed by the servo read element SR and the linear magnetized region 54A1 (see Figure 6) is larger than the angle formed by the servo read element SR and the linear magnetized region 54A2, resulting in a smaller output of the servo pattern signal and a wider waveform. This results in variations in the servo pattern signal read by the servo read element SR across the servo band SB while the magnetic tape MT is running. Furthermore, when the servo read element SR reads the servo pattern 52B, variations due to azimuth loss occur between the servo pattern signal derived from the linear magnetized region 54B1 and the servo pattern signal derived from the linear magnetized region 54B2. Such variations in the servo pattern signal can be a factor in reducing the accuracy of servo control.

[0312] Another example of a conventionally known servo pattern 52A is one in which the linear magnetized region 54A1 is parallel to the virtual line C1 and the linear magnetized region 54A2 is inclined relative to the virtual line C1 (i.e., only the linear magnetized region 54A2 is inclined). Even in this conventionally known configuration, when the servo pattern 52A is read by the servo read element SR, 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. Such angle differences result in variations due to azimuth loss between the servo pattern signals derived from the linear magnetized region 54A1 and the servo pattern signals derived from the linear magnetized region 54A2. Such variations in the servo pattern signals can be a factor in reducing the accuracy of servo control.

[0313] Therefore, when the recording module DWM and the playback module DRM are inclined relative to the width direction WD along the surface 31 of the magnetic tape MT (see FIG. 27), as an example, a magnetic tape MT1 is used instead of the magnetic tape MT, as shown in FIG. 28. 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.

[0314] 28, 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.

[0315] 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. Here, the linear magnetization region pairs 84 are an example of the "linear magnetization region pairs" according to the technology of the present disclosure.

[0316] The servo pattern 82A is made up of a pair of linear magnetization regions 84A. In the example shown in Fig. 28, linear magnetization regions 84A1 and 84A2 are shown as an example of the pair of linear magnetization regions 84A. Each of the linear magnetization regions 84A1 and 84A2 is a linearly magnetized region.

[0317] The linear magnetization regions 84A1 and 84A2 are inclined in opposite directions with respect to the virtual line C1. In other words, the linear magnetization region 84A1 is inclined in one direction with respect to the virtual line C1 (e.g., clockwise as viewed from the front side of the paper in FIG. 28). On the other hand, the linear magnetization region 84A2 is inclined in another direction with respect to the virtual line C1 (e.g., counterclockwise 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 inclination angle of the linear magnetization region 84A1 with respect to the virtual line C1 is steeper than that of the linear magnetization region 84A2. Here, "steep" refers to, for example, the angle of the linear magnetization region 84A1 with respect to the virtual line C1 being smaller than the angle of the linear magnetization region 84A2 with respect to the virtual line C1. The total length of the linear magnetized region 84A1 is shorter than the total length of the linear magnetized region 84A2.

[0318] Here, linear magnetization region 84A1 is an example of a "first linear magnetization region" according to the technology of the present disclosure, linear magnetization region 84A2 is an example of a "second linear magnetization region" according to the technology of the present disclosure, and virtual line C1 is an example of a "virtual line" according to the technology of the present disclosure.

[0319] In the servo pattern 82A, the linear magnetization region 84A1 includes a plurality of magnetization lines 84A1a, and the linear magnetization region 84A2 includes a plurality of 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.

[0320] The linear magnetization region 84A1 is a set of five magnetized straight lines 84A1a, and the linear magnetization region 84A2 is a set of five magnetized straight lines 84A2a. Within the servo band SB, the positions of both ends of the linear magnetization region 84A1 (i.e., the positions of both ends of each of the five magnetization straight lines 84A1a) and the positions of both ends of the linear magnetization region 84A2 (i.e., the positions of both ends of each of the five magnetization straight lines 84A2a) are aligned in the width direction WD. Note that, although an example is given here in which the positions of both ends of each of the five magnetization lines 84A1a and the positions of both ends of each of the five magnetization lines 84A2a are aligned, 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. Furthermore, in this specification, the concept of "aligned" not only means completely aligned, but also includes the meaning of "aligned" that includes an error that is generally acceptable in the technical field to which the technology of the present disclosure belongs and that does not contradict the spirit of the technology of the present disclosure.

[0321] The servo pattern 82B is made up of a pair of linear magnetization regions 84B. In the example shown in Fig. 28, 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.

[0322] The linear magnetization regions 84B1 and 84B2 are inclined in opposite directions with respect to the virtual line C2. In other words, the linear magnetization region 84B1 is inclined in one direction with respect to the virtual line C2 (e.g., clockwise as viewed from the front side of the paper in FIG. 28). On the other hand, the linear magnetization region 84B2 is inclined in another direction with respect to the virtual line C2 (e.g., counterclockwise 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 are inclined at different angles with respect to the virtual line C2. The inclination angle of the linear magnetization region 84B1 with respect to the virtual line C2 is steeper than that of the linear magnetization region 84B2. Here, "steep" means, for example, that the angle of the linear magnetization region 84B1 with respect to the virtual line C2 is smaller than the angle of the linear magnetization region 84B2 with respect to the virtual line C2. The total length of the linear magnetized region 84B1 is shorter than the total length of the linear magnetized region 84B2.

[0323] Here, linear magnetization region 84B1 is an example of a "first linear magnetization region" according to the technology of the present disclosure, linear magnetization region 84B2 is an example of a "second linear magnetization region" according to the technology of the present disclosure, and virtual line C2 is an example of a "virtual line" according to the technology of the present disclosure.

[0324] In the servo pattern 82B, the linear magnetization region 84B1 includes a plurality of magnetization lines 84B1a, and the linear magnetization region 84B2 includes a plurality of 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.

[0325] The total number of magnetization lines 84B1a and 84B2a included in the servo pattern 82B is different from the total number of magnetization lines 84A1a and 84A2a included in the servo pattern 82A. In the example shown in Fig. 28, the total number of magnetization lines 84A1a and 84A2a included in the servo pattern 82A is 10, while the total number of magnetization lines 84B1a and 84B2a included in the servo pattern 82B is 8.

[0326] The linear magnetization region 84B1 is a set of four magnetized straight lines 84B1a, and the linear magnetization region 84B2 is a set of four magnetized straight lines 84B2a. Within the servo band SB, the positions of both ends of the linear magnetization region 84B1 (i.e., the positions of both ends of each of the four magnetization straight lines 84B1a) and the positions of both ends of the linear magnetization region 84B2 (i.e., the positions of both ends of each of the four magnetization straight lines 84B2a) are aligned in the width direction WD.

[0327] Although an example is given here in which the positions of both ends of each of the four magnetization lines 84B1a and the positions of both ends of each of the four magnetization lines 84B2a are aligned, this is merely an example. For example, the technology of the present disclosure is effective as long as the positions of both ends of one or more of the four magnetization lines 84B1a and the positions of both ends of one or more of the four magnetization lines 84B2a are aligned.

[0328] Although the linear magnetization region 84A1 is exemplified here as a set of five magnetized straight lines 84A1a, and the linear magnetization region 84A2 is exemplified as a set of five magnetized straight lines 84A2a, the technology of the present disclosure is not limited thereto. Furthermore, the linear magnetization region 84B1 is exemplified as a set of four magnetized straight lines 84B1a, and the linear magnetization region 84B2 is exemplified as a set of four magnetized straight lines 84B2a, the technology of the present disclosure is not limited thereto. For example, the technology of the present disclosure is valid as long as the linear magnetization region 84A1 has a number of magnetization straight lines 84A1a that contribute to identifying the position of the magnetic head 28 on the magnetic tape MT1, and the linear magnetization region 84A2 has a number of magnetization straight lines 84A2a that contribute to identifying the position of the magnetic head 28 on the magnetic tape MT1. Furthermore, the technology disclosed herein is valid if 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, and 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.

[0329] Here, 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.

[0330] 29 , the geometric characteristics of the linear magnetization 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 magnetization 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 axes SA1 of the virtual linear regions 86A and 86B, which are tilted line-symmetrically with respect to the virtual line C1, with respect to the virtual line C1.

[0331] 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.

[0332] 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.

[0333] A center O1 is provided in the pair of imaginary linear regions 86. For example, the center O1 is the center of a line segment 88 connecting the center of the straight line 86A1 located most upstream in the forward direction among the five straight lines 86A1 and the center of the straight line 86B1 located most upstream in the forward direction among the five straight lines 86B1.

[0334] Since 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 symmetrically with respect to the virtual line C1. Consider a case where 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 regions 86A and 86B by an angle a (e.g., 10 degrees) with respect to the virtual line C1 around the center O1 as the rotation axis, and then the servo read element SR shown in Fig. 27 reads the virtual linear region pair 86. In this case, there are some portions of the virtual linear region pair 86 in the width direction WD where the virtual linear region 86A is read but the virtual linear region 86B is not, or where the virtual linear region 86A is not read but the virtual linear region 86B is read. That is, when reading is performed by the servo read element SR in each of the imaginary linear regions 86A and 86B, there are insufficient portions and unnecessary portions.

[0335] Therefore, in each of the imaginary linear regions 86A and 86B, the missing portions are supplemented and the unnecessary portions are removed, thereby aligning the positions of both ends of the imaginary 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 imaginary linear region 86B (i.e., the positions of both ends of each of the five straight lines 86B1) in the width direction WD.

[0336] The geometric characteristics of the virtual linear region pair 86 thus obtained (i.e., the geometric characteristics of the virtual servo pattern) correspond to the geometric characteristics of the actual servo pattern 82 A. 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 86 A and the positions of both ends of the virtual linear region 86 B in the width direction WD is recorded.

[0337] 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 having 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.

[0338] In this way, when the recording module DWM and the playback module DRM are tilted with respect to the width direction WD along the surface 31 of the magnetic tape MT (see FIG. 27), a magnetic tape MT1 is used on which a servo pattern 82A consisting of pairs of linear magnetized regions 84A and a servo pattern 82B consisting of pairs 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 reproducing data recorded on the magnetic tape MT1, even when data is recorded on or reproduced from the magnetic tape MT1 using a magnetic head 28 skewed above the magnetic tape MT1 to reduce the effects of TDS.

[0339] The linearity of the servo patterns 82 can be guaranteed by carrying out the linearity inspection method (see FIG. 14) on the magnetic tape MT1 in the same manner as in the above embodiment, thereby achieving the same effects as in the above embodiment.

[0340] Furthermore, the formation of a plurality of servo bands SB, each including a plurality of servo patterns 82 along the longitudinal direction LD, is performed in the same manner as in the above embodiment using a skew-adaptive servo pattern recording head (not shown) instead of the servo pattern recording head WH. The skew-adaptive servo pattern recording head refers to a servo pattern recording head in which a plurality of gap patterns having geometric characteristics corresponding to the geometric characteristics of a straight line 86A1 located at the most upstream side in the forward direction within the imaginary linear region 86A and a straight line 86B1 located at the most upstream side in the forward direction within the imaginary linear region 86B are formed at equal intervals along the direction WD3 (see FIG. 13 ).

[0341] Furthermore, in the above embodiment, the magnetic tape MT and magnetic head 28 are exemplified, but this is merely an example. For example, as shown in FIG. 30, a magnetic tape MT2 and a magnetic head 28A may be used instead of the magnetic tape MT and magnetic head 28. The magnetic tape MT2 differs from the magnetic tape MT in that it has a data band DB0 and a servo band SB0. The data band DB0 is adjacent to the data band DB1 in the width direction WD with the servo band SB1 interposed therebetween. The configuration of the servo band SB0 is the same as the configuration of the servo band SB described in the above embodiment, and the configuration of the data band DB0 is the same as the configuration of the data band DB described in the above embodiment.

[0342] Magnetic head 28A differs from magnetic head 28 in that it has a magnetic element unit 42A instead of magnetic element unit 42. Magnetic element unit 42A differs from magnetic element unit 42 in that it has four servo read elements SR as the multiple magnetic elements, and in that it has more multiple data read / write elements DRW than magnetic element unit 42. The four servo read elements SR are servo read elements SR1, SR2, SR3, and SR5.

[0343] The configuration of the servo read element SR5 is the same as the configuration of the servo read element SR described in the above embodiment. The servo read element SR5 is used for the servo band SB0. A plurality of data recording / reproducing elements DRW are provided between the servo read elements SR3 and SR3 in the width direction WD. The plurality of data recording / reproducing elements DRW provided between the servo read elements SR3 and SR3 are used for the data band DB0.

[0344] In the description using the example shown in Figure 30, when it is not necessary to distinguish between the data bands DB0, DB1, and DB2, they will be referred to as "data band DB." Also, in the description using the example shown in Figure 30, when it is not necessary to distinguish between the servo bands SB0, SB1, SB2, and SB3, they will be referred to as "servo band SB." Also, in the description using the example shown in Figure 30, when it is not necessary to distinguish between the servo read elements SR1, SR2, SR3, and SR5, they will be referred to as "servo read elements SR."

[0345] When such a magnetic tape MT2 and magnetic head 28A are used, for example, the indexes described in the above embodiment are obtained for each of all pairs of servo bands SB that straddle one or more servo bands SB in the width direction WD. Here, in the example shown in Figure 30, each of all pairs of servo bands SB that straddle one or more servo bands SB in the width direction WD refers to the combination of servo bands SB1 and SB3, the combination of servo bands SB0 and SB2, and the combination of servo bands SB0 and SB3.

[0346] In this way, by obtaining an index for each pair of servo bands SB that span one or more servo bands SB in the width direction WD, the same effect as in the above embodiment can be obtained even when using magnetic head 28A on magnetic tape MT2.

[0347] Here, we have given examples in which an index can be obtained from each of the combination of servo bands SB1 and SB3, the combination of servo bands SB0 and SB2, and the combination of servo bands SB0 and SB3, but this is merely an example, and an index can also be obtained from one or two of the combination of servo bands SB1 and SB3, the combination of servo bands SB0 and SB2, and the combination of servo bands SB0 and SB3.

[0348] 30, when magnetic processing is performed by the magnetic head 28A only on the data bands DB0 and DB2 among the data bands DB0, DB1, and DB2, the indexes described in the above embodiment are obtained for the data bands DB not used in the magnetic processing, that is, for each of the data bands DB (here, as an example, servo bands SB0 and SB3) other than the pair of servo bands SB not used in the magnetic processing (here, as an example, servo bands SB1 and SB2).In this case, too, the same effect as in the above embodiment can be obtained.

[0349] 30 is merely an example, and the technology of the present disclosure can be applied to a magnetic tape having a greater number of servo bands SB and a greater number of data band DBs than the magnetic tape MT2. In this case, too, in the same manner as in the above-described example, it is possible to obtain an index for at least one of all pairs of servo band DBs that straddle one or more servo band DBs in the width direction WD (i.e., at least one servo band pair), or to obtain an index for at least one of all pairs of servo band DBs that straddle one or more servo bands in the width direction WD other than a pair of servo band DBs that are not used in recording and / or reproducing data (i.e., at least one servo band pair).

[0350] The above-described description and illustrations are a detailed explanation of the parts related to the technology of the present disclosure and are merely an example of the technology of the present disclosure. For example, the above description of the configuration, functions, actions, and effects is an explanation of an example of the configuration, functions, actions, and effects of the parts related to the technology of the present disclosure. Therefore, it goes without saying that unnecessary parts may be deleted, new elements may be added, or replacements may be made to the above-described description and illustrations within the scope of the gist of the technology of the present disclosure. Furthermore, to avoid confusion and facilitate understanding of the parts related to the technology of the present disclosure, the above-described description and illustrations omit explanations of common technical knowledge that do not require particular explanation to enable the implementation of the technology of the present disclosure.

[0351] In this specification, "A and / or B" is synonymous with "at least one of A and B." In other words, "A and / or B" means that it may be only A, only B, or a combination of A and B. Furthermore, in this specification, the same concept as "A and / or B" is also applied when three or more things are expressed by connecting them with "and / or."

[0352] All publications, patent applications, and technical standards mentioned in this specification are herein incorporated by reference to the same extent as if each individual publication, patent application, or technical standard was specifically and individually indicated to be incorporated by reference.

Claims

1. A magnetic tape on which a plurality of servo bands, each having a plurality of servo patterns recorded along a longitudinal direction, are arranged in a width direction, an index indicating nonlinearity of the servo patterns is within 15% of a track pitch, the track pitch being the pitch between a plurality of tracks formed by recording data on the magnetic tape by a recording element in accordance with a signal obtained from the plurality of servo patterns, the index indicating the degree to which the plurality of PES difference gaps vary from an average value of a plurality of 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 corresponding first positions in the width direction, in a pair of servo patterns recorded at corresponding positions in the width direction between a pair of servo bands spanning one or more of the plurality of servo bands in the width direction, 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 predetermined interval, the plurality of PES difference gaps being obtained by measuring the PES difference gap in the pair of servo patterns at second predetermined intervals along the width direction, The first predetermined interval is greater than the second predetermined interval.

2. The magnetic tape according to claim 1, wherein the plurality of tracks are formed by recording the data on the magnetic tape by the recording element using an SMR method.

3. The magnetic tape according to claim 1, wherein the index is a value equivalent to three times the standard deviation of the plurality of PES difference gaps.

4. A magnetic tape as described in claim 1, wherein the first predetermined interval is a reference interval that is a natural number multiple of the second predetermined interval and is an interval that most closely resembles a reference interval that corresponds 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.

5. The magnetic tape according to claim 1, wherein the first predetermined interval is an interval corresponding to a natural number multiple of the second predetermined interval that is equal to or greater than 2.

6. The magnetic tape of claim 1, wherein said first predetermined interval is greater than said track pitch.

7. The magnetic tape according to claim 1, wherein the index is within 10% of the track pitch.

8. The magnetic tape according to claim 1, wherein the index is within 5% of the track pitch.

9. The magnetic tape according to claim 1, wherein the magnetic tape has four or more servo bands arranged in the width direction as the plurality of servo bands, and the index is obtained for each of all pairs of servo bands that straddle one or more of the servo bands in the width direction.

10. The magnetic tape according to claim 9, wherein the index is obtained for each of all pairs of servo bands that straddle one or more of the servo bands in the width direction, except for a pair of servo bands that is not used in recording and / or reproducing the data.

11. The magnetic tape according to claim 9, wherein each of the indices obtained for each of the pair of servo bands is within 15% of the track pitch.

12. The magnetic tape according to claim 9, wherein each of the indices obtained for each of the pair of servo bands is within 10% of the track pitch.

13. The magnetic tape according to claim 9, wherein each of the indices obtained for each of the pair of servo bands is within 5% of the track pitch.

14. The magnetic tape of claim 1, wherein 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.

15. The magnetic tape according to claim 1, wherein the magnetic tape has a base film, the base film being made of polyethylene terephthalate, polyethylene naphthalate, or polyamide.

16. A magnetic tape cartridge comprising: a magnetic tape according to any one of claims 1 to 15; and a case in which the magnetic tape is housed.

17. A magnetic tape system comprising: a magnetic tape according to any one of claims 1 to 15; and a magnetic head for recording data onto said magnetic tape and / or reproducing data recorded on said magnetic tape.

18. An inspection method comprising: acquiring the indicator from a magnetic tape according to any one of claims 1 to 15; and inspecting the magnetic tape using the indicator.

19. The inspection method according to claim 18, wherein inspecting the magnetic tape includes inspecting linearity of the servo pattern using the index.

20. A method for manufacturing 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 comprising: installing a servo write head having a facing surface that faces the recording surface of the magnetic tape when the plurality of servo patterns are recorded 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 the plurality of servo bands on the recording surface by recording the plurality of servo patterns along the first longitudinal direction using the servo write head installed in the above orientation, wherein an index indicating nonlinearity of the servo patterns is within 15% or less of a track pitch, the track pitch being the pitch between a plurality of tracks formed by recording data on the magnetic tape by a recording element in accordance with a signal obtained from the plurality of servo patterns, and the index indicating a degree of variation of the plurality of PES difference gaps from an average value of a plurality of PES difference gaps, A method for manufacturing a magnetic tape, wherein the PES difference gap is a difference between a first PES difference which is a difference in PES between a pair of corresponding first positions in the width direction in a pair of servo patterns recorded at corresponding positions in the width direction between a pair of servo bands that span one or more of the plurality of servo bands in the width direction, and a second PES difference which is a difference in PES between a pair of second positions in the pair of servo patterns that are shifted in the width direction from the pair of first positions by a first predetermined interval, the plurality of PES difference gaps being obtained by measuring the PES difference gap in the pair of servo patterns at second predetermined intervals along the width direction, the first predetermined interval being greater than the second predetermined interval.

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