Servo write head, servo pattern recording device, method for manufacturing magnetic tape, and method for recording servo pattern

Abstract

[Problem] To further reduce friction between a servo write head and magnetic tape, and enable more accurate writing of a servo pattern via a servo write head. [Solution] A servo write head according to the present technology includes a plurality of first regions, a plurality of second regions, and a plurality of third regions. The plurality of first regions each include a servo element for writing a servo pattern on the magnetic tape, and are arranged at predetermined intervals along a first direction. The plurality of second regions each include a plurality of first groove portions that have a first groove width and are cut along a second direction that is a direction intersecting the first direction, and are alternately arranged with the first regions in the first direction. The plurality of third regions each include a second groove portion, at least some of which have a second groove width wider than the first groove width and which are cut along the second direction, and the third regions correspond to regions between the first regions and the second regions.

Description

Servo write head, servo pattern recording device, magnetic tape manufacturing method, and servo pattern recording method

[0001] The present technology relates to a technology such as a servo write head that records a servo pattern on a magnetic tape.

[0002] In recent years, magnetic tape has become widely used for purposes such as backing up electronic data. Because of its large capacity and long-term storage capacity, magnetic tape is attracting increasing attention as a storage medium for big data and other data.

[0003] The magnetic tape is provided with a plurality of data bands each including a plurality of recording tracks and a plurality of servo bands each including a plurality of stripe-shaped servo patterns. In manufacturing the magnetic tape, first, servo patterns are recorded on the servo bands by a servo write head of a servo pattern recording device (see, for example, Patent Document 1).

[0004] Thereafter, the head unit of the data recording / reproducing device reads the servo patterns in the servo bands, aligns the servo patterns with the recording tracks in the data bands, and records data onto the recording tracks.

[0005] In recent years, the number of recording tracks has tended to increase significantly due to demands for higher density recording on magnetic tape. For example, the number of recording tracks on magnetic tapes conforming to the LTO (Linear Tape Open) standard was 384 for the original LTO-1, but has increased to 512, 704, 896, 1280, 2176, 3584, 6656, and 8960 for LTO-2 to LTO-9, respectively.

[0006] Since alignment with the recording tracks is performed based on the servo patterns, an increase in the number of recording tracks requires an improvement in the accuracy of the servo pattern recording. However, friction between the servo write head and the magnetic tape can sometimes reduce the accuracy of the servo pattern recording.

[0007] To reduce this friction, the technique described in Japanese Patent Laid-Open No. 2003-144997 discloses providing a plurality of grooves in the region between adjacent servo elements in the longitudinal direction of the servo write head.

[0008] JP 2014-199706 A JP 2022-157935 A

[0009] There is a need for a technology that can further reduce friction between the servo write head and the magnetic tape, thereby enabling the servo write head to write servo patterns more accurately.

[0010] A servo write head according to the present technology includes a plurality of first regions, a plurality of second regions, and a plurality of third regions. The plurality of first regions each include a servo element for writing a servo pattern to a magnetic tape and are arranged at predetermined intervals along a first direction. The plurality of second regions each have a first groove width and include a plurality of first groove portions cut along a second direction intersecting the first direction, and are arranged alternately with the first regions in the first direction. The plurality of third regions each have a second groove width, at least a portion of which is wider than the first groove width, and include a second groove portion cut along the second direction, corresponding to a region between the first region and the second region.

[0011] In this servo write head, a second groove with a relatively wide groove width is provided in the third region, allowing air to flow through the second groove between the magnetic tape and the servo write head, further reducing friction between the servo write head and the magnetic tape and enabling the servo write head to write servo patterns more accurately.

[0012] 1. A schematic diagram of a magnetic tape as viewed from the side. 2. A schematic diagram of a magnetic tape as viewed from above. 3. A schematic diagram showing a servo pattern recording device. 4. A perspective view of a servo write head as viewed from the magnetic tape side. 5. A plan view of the servo write head as viewed from the magnetic tape side. 6. A plan view of the recording surface of the servo write head as viewed from the magnetic tape side. 7. A cross-sectional view taken along line A-A' in FIG. 5. 8. A schematic partial enlarged view of the upper part of the servo write head as viewed from the side. 9. A diagram showing a partial enlarged view of the recording surface as viewed from the magnetic tape 1 side and a partial enlarged view of the recording surface as viewed from the side. 10. A plan view of the recording surface according to another embodiment as viewed from the magnetic tape side. 11. A diagram showing a partial enlarged view of the recording surface as viewed from the magnetic tape 1 side and a partial enlarged view of the recording surface as viewed from the side. 12. A diagram showing examples and comparative examples. 13. A table showing examples of the present embodiment and comparative examples to be compared with the examples. 14. A diagram showing the locations indicated by symbols A to L in FIG. 13. 15. A diagram showing an evaluation device for evaluating the contact state between the recording surface and the magnetic tape. 16. A magnified view showing the relationship between a dummy and the magnetic tape in the evaluation device. 17 is a cross-sectional view taken along line B-B' in FIG. 16; FIG. 18 is a diagram showing an example of a 2D profile acquired by a measurement device; FIG. 19 is a graph showing an example of an average 1D profile PaT(T); FIG. 20 is a diagram showing an example of a case where the longitudinal direction of the servo write head is inclined at a predetermined azimuth angle θ1 with respect to the width direction of the magnetic tape; and FIG. 21 is a diagram showing another example of a case where the longitudinal direction of the servo write head 13 is inclined at a predetermined azimuth angle θ1 with respect to the width direction of the magnetic tape.

[0013] First Embodiment [Magnetic Tape 1] First, the basic configuration of a magnetic tape 1 according to an embodiment of the present technology will be described. Fig. 1 is a schematic diagram of the magnetic tape 1 as seen from the side, and Fig. 2 is a schematic diagram of the magnetic tape 1 as seen from above. In the drawings, an orthogonal coordinate system based on the magnetic tape 1 is represented by an X'Y'Z' coordinate system.

[0014] As shown in FIGS. 1 and 2, the magnetic tape 1 is configured in a tape shape that is long in the length direction (X'-axis direction), short in the width direction (Y'-axis direction), and thin in the thickness direction (Z'-axis direction).

[0015] The magnetic tape 1 includes a tape-shaped substrate 2 that is long in the length direction (X'-axis direction), a non-magnetic layer 3 provided on one main surface of the substrate 2, a magnetic layer 4 provided on the non-magnetic layer 3, and a back layer 5 provided on the other main surface of the substrate 2. The back layer 5 may be provided as needed, and may be omitted.

[0016] The substrate 2 is a non-magnetic support that supports the non-magnetic layer 3 and the magnetic layer 4. The substrate 2 contains, for example, at least one of polyesters, polyolefins, cellulose derivatives, vinyl resins, and other polymer resins.

[0017] The magnetic layer 4 is a recording layer for recording data. This magnetic layer 4 contains magnetic powder, a binder, conductive particles, etc. The magnetic layer 4 may further contain additives such as a lubricant, an abrasive, and an anti-rust agent, as necessary.

[0018] The magnetic layer 4 may be vertically oriented or longitudinally oriented. The magnetic powder contained in the magnetic layer 4 may be, for example, nanoparticles containing ε-iron oxide (ε-iron oxide particles), nanoparticles containing hexagonal ferrite (hexagonal ferrite particles), or nanoparticles containing Co-containing spinel ferrite (cobalt ferrite).

[0019] The non-magnetic layer 3 contains a non-magnetic powder and a binder. The non-magnetic layer 3 may contain additives such as conductive particles, a lubricant, a hardener, and an anti-rust material, as needed.

[0020] The back layer 5 contains a non-magnetic powder and a binder, and may contain additives such as a lubricant, a hardener, and an antistatic agent, as needed.

[0021] The upper limit of the average thickness (average total thickness) of the magnetic tape 1 is, for example, 5.6 μm or less, 5.0 μm or less, 4.4 μm or less, etc. If the average thickness of the magnetic tape 1 is 5.6 μm or less, the recording capacity that can be recorded in the cartridge 21 can be increased compared to that of a general magnetic tape 1.

[0022] 2, the magnetic layer 4 has a plurality of data bands DB that are long in the length direction (X'-axis direction) in which data is written, and a plurality of servo bands SB that are long in the length direction in which servo patterns 7 are written. The servo bands SB are arranged at positions that sandwich each data band DB in the width direction (Y'-axis direction).

[0023] The number (n) of data bands DB and the number (n+1) of servo bands SB are not particularly limited and can be changed as appropriate.

[0024] The data band DB includes a plurality of recording tracks 6 that are long in the length direction and aligned in the width direction. Data is recorded along and within these recording tracks 6. The length of one bit in the length direction of the data recorded in the data band DB is, for example, 48 nm or less. The servo band SB includes a servo pattern 7 that is recorded by a servo pattern recording device 100 (see FIG. 3).

[0025] Here, the number of recording tracks of LTO-standard magnetic tape 1 has increased with each generation, dramatically improving recording capacity. For example, the number of recording tracks was 384 for the original LTO-1, but has increased to 512, 704, 896, 1280, 2176, 3584, 6656, and 8960 for LTO-2 to LTO-9, respectively. Similarly, the data recording capacity has increased from 100 GB (gigabytes) for LTO-1 to 200 GB, 400 GB, 800 GB, 1.5 TB (terabytes), 2.5 TB, 6.0 TB, 12 TB, and 18 TB for LTO-2 to LTO-9, respectively.

[0026] In this embodiment, the number of recording tracks 6 and the recording capacity are not particularly limited and can be changed as appropriate. However, this technology is advantageous when applied to a magnetic tape 1 on which the number of recording tracks 6 and the recording capacity are large (for example, 6656 tracks or more, 12 TB or more: LTO8 or later) and on which the servo patterns 7 need to be recorded with strict accuracy.

[0027] [Servo Pattern Recording Apparatus 100] Next, a description will be given of the servo pattern recording apparatus 100 that records the servo patterns 7 on the servo bands SB of the magnetic tape 1. FIG.

[0028] As shown in FIG. 3, the servo pattern recording device 100 includes, in order from the upstream side in the transport direction of the magnetic tape 1, a feed roller 11, a degaussing unit 12, a servo write head 13, a servo read head 14, and a take-up roller 15.

[0029] The feed roller 11 is capable of rotatably supporting the rolled magnetic tape 1. The feed roller 11 is rotated in response to the driving of a drive source such as a motor, and feeds the magnetic tape 1 downstream in response to the rotation.

[0030] The take-up roller 15 is capable of rotatably supporting the rolled magnetic tape 1. The take-up roller 15 rotates in synchronization with the delivery roller 11 in response to the driving of a drive source such as a motor, and takes up the magnetic tape 1 as it rotates.

[0031] The feed roller 11 and the take-up roller 15 are capable of moving the magnetic tape 1 at a constant speed within the transport path.

[0032] The servo write head 13 is disposed, for example, above the magnetic tape 1 (on the magnetic layer 4 side). The servo write head 13 generates a magnetic field at a predetermined timing in response to a square wave pulse signal, and applies the magnetic field to a part of the magnetic layer 4 of the magnetic tape 1.

[0033] As a result, the servo write head 13 magnetizes a portion of the magnetic layer 4 and records the servo pattern 7 on the magnetic layer 4. When the magnetic tape 1 passes below the servo write head 13, the servo write head 13 is capable of recording the servo pattern 7 on each of the plurality of servo bands SB.

[0034] The demagnetizing unit 12 is disposed, for example, below the magnetic tape 1 (toward the substrate 2) and upstream of the servo write head 13. The demagnetizing unit 12 is composed of a permanent magnet. Before the servo write head 13 records the servo patterns 7, the permanent magnet applies a magnetic field to the entire magnetic layer 4 using a DC magnetic field, thereby demagnetizing the entire magnetic layer 4.

[0035] The servo read head 14 is disposed downstream of the servo write head 13 and above the magnetic tape 1 (on the magnetic layer 4 side). The servo read head 14 is configured to be able to reproduce servo signals by reading magnetic fields generated from the servo patterns 7 recorded on the magnetic tape 1 using an MR element (Magneto Resistive (MR)), a GMR element (Giant Magneto Resistive (GMR)), a TMR element (Tunnel Magneto Resistive (TMR)), an inductive head, or the like. The reproduced waveform of the servo signal read by the servo read head 14 is used to confirm whether the servo patterns 7 have been recorded accurately.

[0036] Although not shown, the servo pattern recording device 100 is equipped with a control device that controls each section of the servo pattern recording device 100 in an integrated manner.

[0037] The control device includes, for example, a control unit, a storage unit, a communication unit, etc. The control unit is configured by, for example, a CPU (Central Processing Unit) etc., and controls each unit of the servo pattern recording device 100 in an integrated manner according to a program stored in the storage unit.

[0038] The storage unit includes a non-volatile memory for storing various data and programs, and a volatile memory used as a work area for the control unit. The various programs may be read from a portable recording medium such as an optical disk or semiconductor memory, or may be downloaded from a server device on a network. The communication unit is configured to be able to communicate with other devices, such as a server device.

[0039] Here, this embodiment is particularly characterized by the servo write head 13. Before describing the servo write head 13, the basic concept of this technology will be explained.

[0040] The positioning of the recording tracks 6 in the data band DB is performed based on the servo patterns 7 in the servo bands SB. Therefore, as the number of recording tracks increases, the accuracy of recording the servo patterns 7 must be improved accordingly. Regarding the number of recording tracks, LTO9 requires the preparation of 8,960 recording tracks 6, and it is expected that the number of recording tracks will further increase from LTO10 onwards. Therefore, in such cases, it is required to record the servo patterns 7 strictly and accurately (for example, on the order of nanometers).

[0041] On the other hand, in the case of a general servo write head 13, the accuracy of recording the servo pattern 7 may be reduced due to friction between the servo write head 13 and the magnetic tape 1. When the inventors actually performed a frequency analysis of the reproduced waveform of the servo pattern 7 written by the general servo write head 13, they confirmed that there was an error caused by friction in a specific frequency range.

[0042] As the number of recording tracks increases, it is necessary to eliminate errors caused by such friction. For this reason, in this embodiment, the influence of friction is reduced by devising the shapes of the portions of the servo write head 13 that slide against the magnetic tape 1 (the opposing portion 21 and recording surface 22, which will be described later), thereby improving the accuracy of recording the servo patterns 7.

[0043] This technology is advantageous when applied to recording servo patterns 7 on magnetic tapes 1 having a large number of recording tracks 6 (e.g., 6,656 or more: LTO8 and later), but it can also be applied to recording servo patterns 7 on magnetic tapes 1 having a small number of recording tracks (e.g., less than 6,656).

[0044] (Servo Write Head 13) Next, a detailed description will be given of the specific configuration of the servo write head 13. Fig. 4 is a perspective view of the servo write head 13 as seen from the magnetic tape 1 side. Fig. 5 is a plan view of the servo write head 13 as seen from the magnetic tape 1 side.

[0045] 6 is a plan view of the recording surface 22 of the servo write head 13 as seen from the magnetic tape 1 side. Fig. 7 is a cross-sectional view taken along line A-A' in Fig. 5. Fig. 8 is a schematic partial enlarged view of the upper part of the servo write head 13 as seen from the side.

[0046] In each of the drawings described in this specification, an orthogonal coordinate system based on the servo write head 13 (head block 20, dummy 70) is represented by an XYZ coordinate system.

[0047] In the servo write head 13, the length direction (Y-axis direction) corresponds to the width direction (Y'-axis direction) of the magnetic tape 1, and the width direction (X-axis direction) corresponds to the length direction (X'-axis direction) and the running direction of the magnetic tape 1. In addition, in the servo write head 13, the height direction (Z-axis direction) corresponds to the thickness direction (Z'-axis direction) of the magnetic tape 1.

[0048] As shown in these figures, the servo write head 13 comprises a head block 20 , a shield case 50 , and a plurality of coils 60 .

[0049] The shield case 50 shields the magnetic field from the coil 60 so that the magnetic field generated from the coil 60 of the servo write head 13 does not adversely affect other external components. The shield case 50 also shields the coil 60 from external magnetic fields so that the magnetic field generated from other external components does not adversely affect the coil 60.

[0050] The shield case 50 has a hollow rectangular shape that is long in the length direction (Y-axis direction), short in the width direction (X-axis direction), and tall in the height direction (Z-axis direction) (see Figures 4 and 5 in particular).

[0051] An opening 51 is provided at the top of the shield case 50 to expose the head block 20 from the shield case 50. In addition, an opening is provided at the bottom of the shield case 50 to allow a conductor 61 connected to the coil 60 to be drawn out of the shield case 50.

[0052] The head block 20 is formed long in the longitudinal direction (Y-axis direction), and when viewed from the longitudinal direction, the upper part (magnetic tape 1 side) is curved in an inverted U-shape (partially cylindrical) (see Figures 4 to 7 in particular).

[0053] At the top of the head block 20, near the center in the width direction (X-axis direction), a facing portion 21 is provided along the length direction (Y-axis direction) that faces the magnetic tape 1. This facing portion 21 is provided on the head block 20 so as to protrude higher (towards the magnetic tape 1) than other portions at the top of the head block 20.

[0054] Two tapered surfaces 25 inclined in opposite directions relative to the horizontal plane are provided at the upper portion of the head block 20 at positions sandwiching the opposing portion 21 in the width direction.

[0055] The surface of the facing portion 21 is flat. In this specification, this surface of the facing portion 21 is referred to as the recording surface 22. This recording surface 22 faces the running magnetic tape 1, and servo elements 26 provided on the recording surface 22 record servo patterns 7 on the magnetic tape 1.

[0056] In this embodiment, the shape of the recording surface 22 (opposing portion 21) is made different from the usual shape in order to reduce friction between the servo write head 13 and the magnetic tape 1. In this embodiment, the shape of this recording surface 22 makes it possible to bring the magnetic tape 1 into contact with a portion of the recording surface 22 (first region R1) and prevent the magnetic tape 1 from coming into contact with other portions of the recording surface 22 (second region R2, third region R3).

[0057] The recording surface 22 serves as a sliding surface that slides against the magnetic tape 1, but in this embodiment, the magnetic tape 1 is partially separated from the recording surface 22, so not all of the recording surface 22 serves as the recording surface 22. Furthermore, in the upper part of the head block 20, portions other than the recording surface 22, such as the tapered surface 25, are configured not to come into contact with the magnetic tape 1 in order to reduce friction. The configuration of this recording surface 22 will be described in detail later.

[0058] On the recording surface 22, multiple sets of servo elements 26 are provided at predetermined intervals along the length direction (Y-axis direction) (see FIG. 6 in particular). Each set of servo elements 26 is composed of two servo elements 26 (" / " and (\)) arranged so as to be inclined in directions opposite to each other with a predetermined azimuth angle ψ. The azimuth angle ψ is, for example, 12°±3°. The length of the servo elements 26 (Y-axis direction) is, for example, 96 μm±3 μm, and the gap width (X-axis direction), which is the width of the servo elements 26 themselves, is, for example, 0.9 μm.

[0059] The number of sets of servo elements 26 corresponds to the number of servo bands SB on the magnetic tape 1, and in this embodiment, the number of sets of servo elements 26 is 11. Furthermore, of these 11 sets of servo elements 26, the distance in the length direction (Y-axis direction) between two adjacent sets of servo elements 26 corresponds to the distance between two adjacent servo bands SB.

[0060] The head block 20 comprises a core portion 40 that forms the core of the head block 20, a base portion 45 that forms the base on which the servo elements 26 are formed, and a thin film portion 46 that forms the surface of the facing portion 21 (see particularly FIGS. 7 and 8). The thin film portion 46 includes a metal magnetic film 47 (FIG. 8) and a non-magnetic hard film 48 (FIG. 7). Note that the recording surface 22 described above actually corresponds to the surfaces of the metal magnetic film 47 and the non-magnetic hard film 48 (the surface of the thin film portion 46).

[0061] The core portion 40 is formed long in the longitudinal direction (Y-axis direction), and when viewed from the longitudinal direction, it is formed in an inverted U-shape with a curved upper portion (partially cylindrical: the part corresponding to the first core 41 described below).

[0062] An opening 49 penetrating vertically along the length direction (Y axis direction) is formed near the center in the width direction (X axis direction) in the upper part of the core part 40. The base part 45 is disposed in this opening 49 formed in the upper part of the core part 40 so as to fill this opening 49.

[0063] The base portion 45 is long in the length direction (Y-axis direction) and short in the width direction (X-axis direction) and thickness direction (Z-axis direction). The width of the base portion 45 is approximately ⅓ of the width of the facing portion 21.

[0064] As the material for the base portion 45, a hard non-magnetic material with a high melting point (various glass materials, various ceramic materials) is used, taking into consideration that heat treatment is performed during the manufacture of the head block 20 for various joints and to ensure the magnetic properties of the metal magnetic film 47.

[0065] The metal magnetic film 47 is made of, for example, Fe-based microcrystals, NiFe, or other soft magnetic alloys similar to these that have a high saturation magnetic flux density, and has a thickness of several μm.

[0066] The metal magnetic film 47 has openings 27 formed in positions corresponding to the servo elements 26 and in shapes corresponding to the servo elements 26. The openings 27 are formed in the metal magnetic film 47 so as to penetrate the metal magnetic film 47 in the vertical direction. A non-magnetic material is embedded in the openings 27. The upper surface of the non-magnetic material is flush with the surface (recording surface 22) of the metal magnetic film 47, and the lower surface of the non-magnetic material is connected to the upper surface of the base portion 45. The servo elements 26 are formed from the non-magnetic material embedded in the metal magnetic film 47.

[0067] When the core portion 40 is excited by the coil 60, the non-magnetic material (servo elements 26) embedded in the metal magnetic film 47 obstructs the magnetic flux that attempts to pass through the metal magnetic film 47, generating a leakage magnetic field at the position of the servo elements 26. This leakage magnetic field makes it possible to write the servo pattern 7 to the servo band SB.

[0068] The non-magnetic hard film 48 is made of, for example, SiO ２The magnetic film 47 is made of a metal film having the same thickness as the magnetic metal film 47 .

[0069] The surface of the metal magnetic film 47 and the surface of the non-magnetic hard film 48 (i.e., the recording surface 22) are at the same height and are flat. The grooves 33 are formed by processing the non-magnetic hard film 48. The recesses 34 are formed by processing the metal magnetic film 47.

[0070] The core unit 40 is configured such that first cores (positioned corresponding to the servo elements 26) made of a magnetic material and second cores made of a non-magnetic material are arranged alternately in the longitudinal direction. Note that by interposing the second cores made of a non-magnetic material between the first cores, it is possible to magnetically separate the individual first cores.

[0071] The magnetic material for forming the first core may be, for example, a single crystal ferrite or a polycrystalline ferrite, etc. Examples of ferrite materials include Mn—Zn ferrite.

[0072] The non-magnetic material constituting the second core is a material with a thermal expansion coefficient equivalent to that of the first core and the metal magnetic film, taking into consideration that heat treatment is performed for various joining processes and to ensure the magnetic properties of the metal magnetic film 47. For example, the non-magnetic material is BaO-TiO ２ Ceramics, CaO-TnO ２ Ceramics, glass ceramics, etc., whose thermal expansion coefficient is close to that of ferrite materials, are used.

[0073] In the core portion 40, individual coils 60 are formed by winding individual conductors 61 in a coil shape around the lower part of the first core.

[0074] A separate pulse signal can be supplied to each of the coils 60, and each of the first cores can be individually excited, which allows each of the first cores to write the servo pattern 7 to the servo band SB at a different timing.

[0075] The servo write head 13 may be movable in the height direction (Z-axis direction) by a head movement mechanism (not shown). In this case, the recording surface 22 of the head block 20 can be protruded toward the magnetic tape 1, making it possible to adjust the penetration distance toward the magnetic tape 1 and the wrap angle with respect to the magnetic tape 1.

[0076] [Configuration of Recording Surface 22] Next, a detailed description will be given of the configuration of the recording surface 22. Fig. 9 shows a partial enlarged view of the recording surface 22 (opposing portion 21) as viewed from the magnetic tape 1 side, and a partial enlarged view of the recording surface 22 (opposing portion 21) as viewed from the side.

[0077] 6 and 9, the recording surface 22 includes a plurality of first regions R1, a plurality of second regions R2, and a plurality of third regions R3.

[0078] The plurality of first regions R2 each include a set of servo elements 26 that write servo patterns 7 on the magnetic tape 1, and are arranged at predetermined intervals along the longitudinal direction (first direction: Y-axis direction) of the servo write head 13. The plurality of second regions R2 each include a plurality of first groove portions 61 that have a first groove width and are cut along a direction intersecting the longitudinal direction of the servo write head 13 (second direction: in this example, the width direction of the servo write head 13: X-axis direction), and are arranged alternately with the first regions R1 along the longitudinal direction of the servo write head 13.

[0079] The multiple third regions R3 each have a second groove width, at least a portion of which is wider than the first groove width, and each include a second groove portion 63 cut along the width direction (second direction) of the servo write head 13, and correspond to the region between the first region R1 and the second region R2.

[0080] The first regions R1 are regions having a set of servo elements 26 at their central positions, and are convex regions separated by two second groove portions 63 (third regions R3) adjacent to each other in the longitudinal direction (Y-axis direction) of the servo write head 13. The width (Y-axis direction) of the first regions R1 (see symbol A in FIG. 14) is, for example, 300 μm or less, 250 μm or less, 200 μm or less, etc.

[0081] Typically, the smaller the width (Y-axis direction) of the first region R1, the smaller the contact area between the magnetic tape 1 and the recording surface 22, and therefore the smaller the vibration due to frictional resistance with the magnetic tape 1. This improves the running stability of the magnetic tape 1, allowing the servo pattern 7 to be recorded on the magnetic tape 1 precisely and accurately. However, if the width of the first region R1 is too small, the magnetic tape 1 will not make proper contact with one set of servo elements 26 (length: approximately 96 μm), making it difficult to record the servo pattern 7 on the magnetic tape 1. For this reason, the width (Y-axis direction) of the first region R1 (see symbol A in FIG. 14 ) is typically set to 150 μm or more, or 170 μm or more.

[0082] The length (X-axis direction) of the first region R1 (see symbol G in FIG. 14) is typically set to a length corresponding to the width (X-axis direction) of the recording surface 22.

[0083] The second region R2 includes a plurality of first grooves 61 cut along the width direction (X-axis direction) of the servo write head 13 and aligned in the longitudinal direction (Y-axis direction) of the servo write head 13. The first grooves 61 are provided on the recording surface 22 so as to communicate with both ends of the servo write head 13 in the width direction (X-axis direction). The second region R2 also includes a plurality of convex portions 62 formed between two adjacent first grooves 61.

[0084] The width (Y-axis direction) of the second region R2 is typically about 2000 μm. The length (X-axis direction) of the second region R2 (see symbol G in FIG. 14 ) is typically set to a length corresponding to the width (X-axis direction) of the recording surface 22.

[0085] The first groove width (Y-axis direction) of the first groove portion 61 in the second region R2 (see symbol H in FIG. 14 ) is, for example, about 10 μm or more and 50 μm or less. The depth (Z-axis direction) of the first groove portion 61 (see symbol L in FIG. 14 ) is, for example, 1 μm or more and 10 μm or less. The length (X-axis direction) of the first groove portion 61 (see symbol G in FIG. 14 ) corresponds to the width (X-axis direction) of the recording surface 22.

[0086] The width (Y-axis direction) of the convex portion 62 in the second region R2 (see symbol I in FIG. 14) is set to approximately 5 μm or more and 30 μm or less. The length (X-axis direction) of the convex portion 62 in the second region R2 (see symbol G in FIG. 14) is typically set to a length corresponding to the width (X-axis direction) of the recording surface 22.

[0087] The third region R3 is a region corresponding to the second groove portion 63 formed between the first region R1 and the second region R2. In this example, the case where the third region R3 has one second groove portion 63 will be described, but the third region R3 may have two or more second groove portions 63.

[0088] The second groove 63 is cut along the width direction (X-axis direction) of the servo write head 13, and at least a portion thereof is formed wider than the first groove width of the first groove 61 in the second region R2. Like the first groove 61, the second groove 63 is also provided on the recording surface 22 in the width direction (X-axis direction) of the servo write head 13 so as to communicate with both ends thereof.

[0089] The second groove width (Y-axis direction) (see symbol B in Figure 14) of the second groove portion 63 in the third region R3 is typically 100 μm or more, 150 μm or more, 200 μm or more, 250 μm or more, 300 μm or more, etc.

[0090] Here, the larger the second groove width (Y-axis direction) of the second groove portion 63, the smaller the contact area between the magnetic tape 1 and the recording surface 22, and therefore the smaller the vibration due to frictional resistance between the magnetic tape 1. This improves the running stability of the magnetic tape 1. Furthermore, the larger the second groove width of the second groove portion 63, the easier it is for air to flow through the position of the second groove portion 63. This makes it possible to appropriately prevent air from flowing between the first region R1 and the magnetic tape 1 and creating an air layer (see the lower side of Figure 12 described below). This also improves the recording stability when recording the servo pattern 7 on the magnetic tape 1. However, if the second groove width (Y-axis direction) of the second groove portion 63 is too large, the magnetic tape 1 may bend, and in this case, the magnetic tape 1 may come into contact with the bottom of the second groove portion 63. Therefore, the second groove width (see symbol B in FIG. 14) of the second groove portion 63 is typically set to about 550 μm or less.

[0091] The depth (Z-axis direction) of the second groove portion 63 in the third region R3 (see symbol L in FIG. 14 ) is typically the same as the depth of the first groove portion 61 in the second region R2 (e.g., 1 μm or more and 10 μm or less). The depth of the second groove portion 63 may be different from the depth of the second groove portion 63. The length (X-axis direction) of the second groove portion 63 in the third region R3 (see symbol G in FIG. 14 ) corresponds to the width (X-axis direction) of the recording surface 22.

[0092] (T-type) Next, other configurations of the recording surface 22 will be described. Fig. 10 is a plan view of the recording surface 22 (opposing portion 21) according to another configuration, as viewed from the magnetic tape 1 side. Fig. 11 is a partial enlarged view of the recording surface 22 (opposing portion 21) as viewed from the magnetic tape 1 side, and a partial enlarged view of the recording surface 22 (opposing portion 21) as viewed from the side.

[0093] In the recording surface 22 according to other embodiments, the first region R1 is generally T-shaped. Therefore, in the following description, this type of recording surface 22 will be referred to as a T-type for convenience. On the other hand, in the embodiments shown in Figures 7 and 9, the first region R1 is rectangular. Therefore, in the following description, this type of recording surface 22 will be referred to as a rectangular type for convenience.

[0094] This T-type recording surface 22 also has a first region R1, a second region R2, and a third region R3, just like the rectangular-type recording surface 22 described above, but in this T-type, the shape of the second groove portion 63 in the third region R3 is different from that of the rectangular type, and since the shape of the second groove portion 63 in this T-type is different from that of the rectangular type, the shape of the first region R1 (generally T-shaped) also differs from that of the rectangular type.

[0095] Here, in the case of a rectangular-type recording surface 22, the second groove width (Y-axis direction) of the second groove portion 63 in the third region R3 is constant and does not change in the width direction (X-axis direction) of the servo write head 13. In contrast, in the case of a T-type recording surface 22, the second groove width (Y-axis direction) of the second groove portion 63 in the third region R3 is not constant and changes in the width direction (X-axis direction) of the servo write head 13.

[0096] In the case of a T-type, typically, the width of the groove (second groove width) of the second groove portion 63 in the third region R3 is set so that the groove width on the side corresponding to the downstream side of the flow in the running direction of the magnetic tape 1 is wider than the groove width on the side corresponding to the upstream side of the flow of the magnetic tape 1.

[0097] That is, the second groove portion 63 in the T-shaped third region R3 includes a third groove portion 64 located upstream of the flow of the magnetic tape 1 and having a third groove width, and a fourth groove portion 65 located downstream of the flow of the magnetic tape 1 and having a fourth groove width wider than the third groove width.

[0098] The third groove width (Y-axis direction) (see symbol C in FIG. 14 ) of the third groove portion 64 is the same as the first groove width of the first groove portion 61 in the second region R2, or is slightly larger than the first groove width of the first groove portion 61. For example, the third groove width (Y-axis direction) of the third groove portion 64 is, for example, approximately 10 μm or more and 100 μm or less.

[0099] Furthermore, the fourth groove width of the fourth groove portion 65 (see symbol B in FIG. 14 ) is typically set to approximately the same size as the second groove width of the second groove portion 63 in the rectangular type. Therefore, the fourth groove width of the fourth groove portion 65 is set to, for example, 100 μm or more, 150 μm or more, 200 μm or more, 250 μm or more, 300 μm or more, and 550 μm or less.

[0100] Here, the multiple second grooves 63 include a pair of second grooves 63 arranged at positions sandwiching the first region R1 in the longitudinal direction (Y-axis direction) of the servo write head 13. This pair of second grooves 63 are formed symmetrically with respect to a line (see dashed dotted line in FIG. 11 ) that passes through the center of the first region R1 in the longitudinal direction (Y-axis direction) of the servo write head 13 and is aligned along the width direction (X-axis direction: direction in which the groove faces) of the servo write head 13. This also applies to the rectangular type (see dashed dotted line in FIG. 9 ).

[0101] In addition, in the case of a T-type, the width of the first region R1 is set so that the width on the side corresponding to the upstream side of the flow of magnetic tape 1 is wider than the width on the side corresponding to the downstream side of the flow of magnetic tape 1 (i.e., the width changes; in the case of a rectangular type, the width is constant).

[0102] That is, in the case of a T-type, the first region R1 includes a first portion 66 having a first width in the longitudinal direction (Y-axis direction) of the servo write head 13, and a second portion 67 including a pair of protrusions 68 that protrude outward from the first portion 66 at both ends in the Y-axis direction, and having a second width in the Y-axis direction that is wider than the first width.

[0103] The first width (Y-axis direction) of the first portion 66 (see symbol A in FIG. 14 ) is typically about the same as the width of the first region R1 in the rectangular type. Therefore, the first width of the first portion 66 is typically 300 μm or less, 250 μm or less, 200 μm or less, 150 μm or more, 170 μm or more, etc.

[0104] The second width (Y-axis direction) of the second portion 67 is, for example, 250 μm or more and 1000 μm or less. The width (Y-axis direction) of the protrusion 68 of the second portion 67 (see symbol D in FIG. 14 ) is, for example, 100 μm or more, 150 μm or more, 200 μm or more, etc.

[0105] If the width (Y-axis direction) of the protrusion 68 in the second portion 67 (see symbol D in FIG. 14 ) is made too long, the third groove width (Y-axis direction) of the third groove 64 in the third region R3 (see symbol C in FIG. 14 ) will not be adequately ensured. For this reason, the width of the protrusion 68 is set to 540 μm or less, for example.

[0106] Furthermore, the length (X-axis direction) of the protrusion 68 in the second portion 67 (see symbol E in FIG. 14 ) is, for example, 150 μm or more, 200 μm or more, 250 μm or more, etc. Note that if the length (X-axis direction) of the protrusion 68 is too long, the third region R3 becomes too small. For this reason, the length (X-axis direction) of the protrusion 68 in the second portion 67 (see symbol E in FIG. 14 ) is typically 500 μm or less.

[0107] The length (X-axis direction) of the protrusion 68 in the first region R1 (see symbol E in FIG. 14 ) corresponds to the length (X-axis direction) of the second portion 67 in the first region R1, and also corresponds to the length (X-axis direction) of the third groove 64 in the third region R3. The value (see symbol F in FIG. 14 ) obtained by subtracting the length (X-axis direction) of the protrusion 68 (see symbol E in FIG. 14 ) from the width (X-axis direction) of the recording surface 22 (see symbol G in FIG. 14 ) corresponds to the length (X-axis direction) of the first portion 66 in the first region R1, and also corresponds to the length (X-axis direction) of the fourth groove 65 in the third region R3.

[0108] In the description herein, the first region R1 has been described as being generally T-shaped. Meanwhile, the width of the first region R1 may typically be set so that the width on the side corresponding to the upstream side of the flow of the magnetic tape 1 is wider than the width on the side corresponding to the downstream side of the flow of the magnetic tape 1. Correspondingly, the groove width of the second groove portion 63 in the third region R3 may be set so that the groove width on the side corresponding to the downstream side of the flow of the magnetic tape 1 in the running direction is wider than the groove width on the side corresponding to the upstream side of the flow of the magnetic tape 1.

[0109] Therefore, for example, the first region R1 may be Y-shaped or trapezoidal. The width (Y-axis direction) of the first region R1 may be configured to increase in multiple steps from the downstream side to the upstream side of the flow of the magnetic tape 1, or may be configured to increase gradually in a linear manner. Correspondingly, the width (Y-axis direction) of the second groove portion 63 may also increase in multiple steps from the upstream side to the downstream side of the flow of the magnetic tape 1, or may be configured to increase gradually in a linear manner. Typically, the first region R1 is formed symmetrically with respect to a line that passes through the center of the first region R1 in the width direction (Y-axis direction) and is aligned along the longitudinal direction (X-axis direction: second direction).

[0110] Examples and Comparative Examples Next, the operation of the present technology will be described while describing examples according to the present embodiment and comparative examples to be compared with the examples.

[0111] 12 is a diagram showing each example and each comparative example. In FIG. 12, comparative example A has a first region R1 and a second region R2, similar to this embodiment, but does not have a third region R3 (second groove portion 63), unlike this embodiment. Furthermore, in comparative example A, the width of the first region R1 is wider than in this embodiment.

[0112] In the case of comparison example A, an air gap occurs between the first region R1 and the magnetic tape 1, gradually widening from the upstream side to the downstream side of the flow of the magnetic tape 1, which causes the running stability and recording stability of the magnetic tape 1 to be impaired.

[0113] In Comparative Example B, the width (Y-axis direction) of the first region R1 is narrower than that of Comparative Example A in order to reduce vibrations caused by frictional resistance between the magnetic tape 1 and the recording surface 22. In other respects, Comparative Example B is the same as Comparative Example A.

[0114] In Comparative Example B, as in Comparative Example A, an air gap occurs between the first region R1 and the magnetic tape 1, gradually widening from the upstream side to the downstream side of the flow of the magnetic tape 1, causing a loss of running stability and recording stability of the magnetic tape 1. Furthermore, in Comparative Example B, the width of the first region R1 is narrowed, which reduces frictional resistance, but an air gap occurs up to a position close to the servo element 26, making it difficult for the servo element 26 to write the servo pattern 7 on the magnetic tape 1 in the first place.

[0115] Example A corresponds to the rectangular type. In Example A, similar to Comparative Example B, the width (Y-axis direction) of the first region R1 is narrowed in order to reduce the frictional resistance between the magnetic tape 1 and the recording surface 22. However, unlike Comparative Example B, Example A has the third region R3, i.e., the second groove portion 63, through which air flows. Therefore, no air gap is generated between the first region R1 and the magnetic tape 1, gradually widening from the upstream side to the downstream side of the flow of the magnetic tape 1. Typically, the air gap is generated only slightly at a position away from the servo element 26.

[0116] Thus, unlike Comparative Examples A and B, Example A has a third region R3, which reduces vibrations due to frictional resistance and improves the running stability of the magnetic tape 1, while allowing the servo pattern 7 to be written precisely and accurately.

[0117] Example B corresponds to the T-type. In Example B, as in Example A, air flows through the third region R3, i.e., the second groove portion 63, so no gap in the air layer is generated that gradually widens from the upstream side to the downstream side of the flow of the magnetic tape 1. Therefore, in Example B, as in Example A, the servo pattern 7 can be written precisely and accurately while reducing frictional resistance and improving the running stability of the magnetic tape 1.

[0118] Furthermore, in the case of Example B, the air gap typically occurs only in a portion (the tip side) of the protrusion 68 in the T-shaped first region R1, which is thought to further improve the running stability and recording stability of the magnetic tape 1.

[0119] Fig. 13 is a table showing examples of this embodiment and comparative examples to be compared with each example. Fig. 14 is a diagram showing the locations indicated by symbols A to L in Fig. 13.

[0120] 14 , symbol A denotes the width (Y-axis direction) of the rectangular first region R1 or the width (Y-axis direction) of the first portion 66 in the T-shaped first region R1. Symbol B denotes the second groove width (Y-axis direction) of the second groove portion 63 in the rectangular third region R3 or the fourth groove width (Y-axis direction) of the fourth groove portion 65 of the second groove portion 63 in the T-shaped third region R3.

[0121] Furthermore, symbol C represents the third groove width (Y-axis direction) of the third groove portion 64 of the second groove portion 63 in the T-type third region R3. Symbol D represents the width (Y-axis direction) of the protrusion 68 of the second portion 67 in the T-type first region R1. Symbol E represents the length (X-axis direction) of the protrusion 68 of the second portion 67 in the T-type first region R1, or the length of the third groove portion 64 of the second groove portion 63 in the T-type third region R3.

[0122] Furthermore, the symbol F is the length (X-axis direction) of the first portion 66 in the T-shaped first region R1, or the length (X-axis direction) of the fourth groove portion 65 of the second groove portion 63 in the T-shaped third region R3. Furthermore, the symbol G is the width (X-axis direction) of the recording surface 22 (or the length of each groove, etc.).

[0123] Furthermore, symbol H is the first groove width (Y-axis direction) of the first groove portion 61 in the second region R2. Symbol I is the width (Y-axis direction) of the convex portion 62 in the second region R2. Symbol J is the pitch of the first groove portion 61 in the second region R2. Symbol K is the width (Y-axis direction) of the servo element 26 provided in the first region R1. Symbol L is the depth (Z-axis direction) of the first groove portion 61 in the second region R2 or the depth (Z-axis direction) of the second groove portion 63 in the third region R3.

[0124] 13, the running stability of the magnetic tape 1 is evaluated by a relative evaluation of the σSW value when the σSW in Comparative Example 1 is set as the reference (100%). This running stability will be described in detail later, but a lower σSW value indicates more stable running of the magnetic tape 1. Furthermore, the evaluation of the writing accuracy of the servo patterns 7 is performed based on the servo signals read and reproduced by the servo read head 14. The writing accuracy of this servo pattern 7 is also evaluated based on Comparative Example 1 (100%).

[0125] 13, the contact condition between the magnetic tape 1 and the recording surface 22 is evaluated by a relative evaluation of the R_Mrg value, with the R_Mrg in Comparative Example 1 set as the reference (100%). This contact condition will be described in detail later, but a lower R_Mrg value indicates a smaller contact area between the magnetic tape 1 and the recording surface 22.

[0126] In addition, in FIG. 13, the intrusion state indicates the degree to which air has entered between the magnetic tape 1 and the first region R1.

[0127] 13, Comparative Examples 1 and 2 correspond to Comparative Example A in Fig. 12. That is, Comparative Examples 1 and 2 have the first region R1 and the second region R2, similar to Examples 1 to 11, but do not have the third region R3 (second groove portion 63), unlike Examples 1 to 11. Furthermore, in Comparative Examples 1 and 2, the width of the first region R1 is wider (600 µm) than in Examples 1 to 11.

[0128] In Comparative Example 1, the width of the first region R1 is wide, and the contact area between the magnetic tape 1 and the recording surface 22 is large compared to Examples 1 to 11 (the value of R_Mrg is relatively high). Therefore, Comparative Example 1 has relatively low running stability compared to Examples 1 to 11 (the value of σSW is relatively high). Furthermore, in Comparative Example 1, a gap in the air layer occurs over a wide range between the first region R1 and the magnetic tape 1 (see the lower diagram of Comparative Example A in FIG. 12), and therefore the recording stability of the servo pattern 7 is low.

[0129] In Comparative Example 2, the first groove width (Y-axis direction) of the first groove portions 61 in the second region R2 is narrower than in Comparative Example 1, and the pitch of the first groove portions 61 is also narrower. Similar to Comparative Example 1, Comparative Example 2 also has a wide first region R1, and the contact area between the magnetic tape 1 and the recording surface 22 is larger than in Examples 1 to 11 (the value of R_Mrg is relatively high). Therefore, Comparative Example 2 also has relatively lower running stability than Examples 1 to 11 (the value of σSW is relatively high). Furthermore, similar to Comparative Example 1, Comparative Example 2 also has a wide air gap between the first region R1 and the magnetic tape 1 (see the lower diagram of Comparative Example A in FIG. 12 ), resulting in low recording stability of the servo pattern 7.

[0130] Comparative Examples 3 and 4 correspond to Comparative Example B in Fig. 12. That is, in Comparative Examples 3 and 4, the width (Y-axis direction) of the first region R1 is narrower (300 µm) than in Comparative Examples 1 and 2, in order to reduce the frictional resistance between the magnetic tape 1 and the recording surface 22.

[0131] In Comparative Examples 3 and 4, the contact area between the magnetic tape 1 and the recording surface 22 is too small compared to Examples 1 to 11 (the R_Mrg value is too small, at 7% to 8%). This indicates that simply narrowing the first region R1 (the absence of the third region R3) results in an air gap extending up to the position of the servo element 26 (see the lower diagram of Comparative Example B in FIG. 12). Therefore, the servo read head 14 cannot read the servo pattern 7 (measurement not possible), and the running stability of the magnetic tape 1 cannot be measured (measurement not possible).

[0132] Examples 1 to 5 are rectangular types corresponding to Example A in Figure 12. In Examples 1 to 5, the width (Y-axis direction) of the first region R1 is narrowed (300 μm) for the purpose of reducing vibration due to frictional resistance. On the other hand, Examples 1 to 5 differ from Comparative Examples 1 to 4 in that a third region R3, i.e., a second groove portion 63, is provided, and air flows through this portion, so that there is little gap due to an air layer between the magnetic tape 1 and the first region R1 (see the lower diagram of Example A in Figure 12).

[0133] Therefore, in Examples 1 to 5, the contact area between the magnetic tape 1 and the recording surface 22 is narrow enough to appropriately reduce vibrations due to frictional resistance, and is wide enough to allow the servo element 26 to appropriately write the servo pattern 7 (R_Mrg value is 38% to 57%).

[0134] Therefore, compared to Comparative Examples 1 to 4, Examples 1 to 5 have relatively high running stability (relatively low σSW values: 76% to 84%), and therefore can write the servo patterns 7 precisely and accurately onto the magnetic tape 1. In other words, the servo patterns 7 can be written accurately and linearly along the servo bands SB, and a high output can be ensured for the servo signals when the servo patterns 7 are read (SRV 100%).

[0135] Examples 6 to 11 are T-type tape holders corresponding to Example B in Fig. 12. As in Examples 1 to 5, Examples 6 to 11 also have a third region R3, i.e., a second groove portion 63, through which air flows, so that little gap due to an air layer occurs between the magnetic tape 1 and the first region R1 (see the lower diagram of Example B in Fig. 12). Typically, the air layer gap occurs only in a portion (the tip side) of the protrusion 68 in the T-shaped first region R1.

[0136] Therefore, in Examples 6 to 11, as in Examples 1 to 5, the contact area between the magnetic tape 1 and the recording surface 22 is narrow enough to appropriately reduce vibrations due to frictional resistance, and is wide enough to allow the servo element 26 to appropriately write the servo pattern 7 (R_Mrg value is 46% to 62%).

[0137] Therefore, in Examples 6 to 11, similarly to Examples 1 to 5, the running stability is relatively high (the value of σSW is relatively low: 83% to 93%), and therefore the servo pattern 7 can be written precisely and accurately on the magnetic tape 1. In other words, the servo pattern 7 can be written accurately and linearly along the servo band SB, and a high output can be ensured for the servo signal when the servo pattern 7 is read (SRV 100%).

[0138] [Evaluation of the contact state between the recording surface 22 and the magnetic tape 1] Next, an evaluation of the contact state between the recording surface 22 and the running magnetic tape 1 in Fig. 13 will be described. Fig. 15 is a diagram showing an evaluation device for evaluating the contact state between the recording surface 22 and the magnetic tape 1.

[0139] In this evaluation, first, several types of dummies 70 were prepared that imitated the upper part of the head block 20 and were processed corresponding to Comparative Examples 1 to 4 and Examples 1 to 11. Next, these dummies 70 were each set in the evaluation device 200 and the contact state was evaluated.

[0140] As shown in FIG. 15, the evaluation device 200 includes a light source 81 , a beam splitter 82 , an imaging unit 83 , an amplifier unit 84 , a control device 85 , a display unit 86 , and an input unit 87 .

[0141] The dummy 70 is a pseudo head made of glass. Detailed information about the dummy 70 is as follows: Material: BK7 glass Shape: rectangular parallelepiped (width (X-axis direction) 1 mm x length (Y-axis direction) 20 mm x depth (Z-axis direction) 3 mm) Processing: Each edge is a sharp edge. Parallelism is within 10 minutes. The roughness of the recording surface 22 (tape contact surface) and its opposing surface is Ra≦0.2 nm.

[0142] The long side surface (1 mm wide x 20 mm long) of the dummy 70 is used as the recording surface 22. The reason why a glass material is used as the material of the dummy 70 is that the contact state between the recording surface 22 and the magnetic tape 1 can be evaluated by optical interference fringes.

[0143] The light source 81 is configured to emit monochromatic light in a specific wavelength range (e.g., red). The beam splitter 82 transmits the light emitted from the light source 81 and guides the light reflected by the dummy 70 and the magnetic tape 1 to the imaging unit 83.

[0144] The imaging unit 83 captures an image using light reflected from the dummy 70 and the magnetic tape 1. The amplifier 84 amplifies the signal of the image captured by the imaging unit 83 and outputs the amplified signal to the control device 85. The control device 85 includes, for example, a control unit, a storage unit, a communication unit, etc. The control unit is configured by, for example, a CPU, etc., and controls each unit of the evaluation device 200 in an integrated manner in accordance with a program stored in the storage unit.

[0145] The storage unit includes a non-volatile memory for storing various data and programs, and a volatile memory used as a work area for the control unit. The various programs may be read from a portable recording medium such as an optical disk or semiconductor memory, or may be downloaded from a server device on a network. The communication unit is configured to be able to communicate with other devices, such as a server device.

[0146] The display unit 86 is configured with, for example, a liquid crystal display or an EL (Electro-Luminescence) display, and displays the image captured by the imaging unit 83 on the display in response to instructions from the control device 85. The input unit 87 is, for example, a keyboard or a contact sensor, and inputs various instructions from the user and outputs them to the control device 85.

[0147] Here, the movement of light will be explained. First, light emitted from the light source 81 passes through the beam splitter 82 and enters the dummy 70 from the rear side of the dummy 70 (the side opposite the recording surface 22). A portion of the light that enters the dummy 70 is reflected by the recording surface 22. Another portion of the light that enters the dummy 70 passes through the recording surface 22 and is reflected by the magnetic tape 1. The light reflected by the recording surface 22 and the magnetic tape 1 is guided by the beam splitter 82 to the imaging unit 83, and an image is captured by the imaging unit 83.

[0148] If there is a distance between the recording surface 22 and the magnetic tape 1, the light reflected by the recording surface 22 and the light reflected by the magnetic tape 1 will strengthen or weaken each other depending on this distance, and will appear as interference fringes in the image captured by the imaging unit 83.

[0149] Fig. 16 is an enlarged view showing the relationship between the dummy 70 and the magnetic tape 1 in the evaluation device 200. Fig. 17 is a cross-sectional view taken along line BB' in Fig. 16. Fig. 18 is a diagram showing an example of a 2D profile acquired by the measurement device.

[0150] The measurement position of the 2D profile shown in Fig. 18 is region R in Fig. 16. The 2D profile shown in Fig. 18 indicates that the lighter the grayscale and the closer to white it is, the smaller the distance between the recording surface 22 of the dummy 70 and the magnetic tape 1. This 2D profile is used to calculate the index Ts, which will be described later.

[0151] 16 and 17, in addition to the components shown in Fig. 15, the evaluation device 200 is provided with a guide 88 for guiding the magnetic tape 1. Although not shown, the evaluation device 200 also includes a drive device for running the magnetic tape 1, a dummy 70 moving mechanism for moving the dummy 70 toward the magnetic tape 1, and the like.

[0152] The two guides 88 are arranged at a predetermined distance from the dummy 70 in a position sandwiching the dummy 70 in the width direction of the dummy 70 (X-axis direction: running direction of the magnetic tape 1). When the dummy 70 is installed in the evaluation device 200, the dummy 70 is installed so that the line connecting the corresponding positions of the two guides 88 is parallel to the surface of the dummy 70. Furthermore, the distance D' between the dummy 70 and the two guides 88 is set to be the same. In this measurement, the distance D' is set to 19.5 mm.

[0153] In this measurement, air guides were used as the two guides 88 for guiding the magnetic tape 1. That is, a certain amount of air released from holes in the surface of the guide 88 remains between the magnetic tape 1 and the guide 88, preventing direct contact between the magnetic tape 1 and the guide 88, and as a result, the friction between them can be significantly reduced.

[0154] The reason for using air guides as the guides 88 in this measurement was to achieve this low friction, which allows for more accurate spacing evaluation. The two guides 88 on both sides of the dummy 70 are equipped with air pressure measuring devices, and the tape tension can be measured using these measurements. The evaluation device 200 automatically controlled the air pressure to achieve the tension value (0.6 N) used in this measurement, which will be described later. Calibration was also performed before the measurement to ensure an accurate relationship between the tension value and air pressure.

[0155] The dummy 70 can be moved in the thickness direction (Z-axis direction) of the dummy 70 by a dummy 70 moving mechanism, and can be protruded toward the magnetic tape 1. The distance by which the dummy 70 protrudes toward the magnetic tape 1 and penetrates into the magnetic tape 1 will hereinafter be referred to as the penetration distance P. The penetration distance P is based on the position of the dummy 70 when the magnetic tape 1 is flat and the dummy 70 is in contact with this flat magnetic tape 1 (penetration distance P=0).

[0156] Furthermore, the angle formed between the recording surface 22 of the dummy 70 and the magnetic tape 1 when viewed from the length direction of the dummy 70 (Y-axis direction: width direction of the magnetic tape 1) will hereinafter be referred to as the wrap angle θ (not the portion of the magnetic tape 1 that faces the recording surface 22, but the portions on both sides of the magnetic tape 1 that sandwich the portion that faces the recording surface 22 in the running direction of the magnetic tape 1). In this measurement, the entry distance P was adjusted so that the wrap angle θ was 5°. Also, in this measurement, the speed V at which the magnetic tape 1 was run was set to 5 m / s. The reason for setting the wrap angle θ to 5° and the speed V to 5 m / s in this measurement is to reduce variation in the measurement values.

[0157] First, the magnetic tape 1 contained in the cartridge 10 was unwound, and the magnetic tape 1 was cut out longitudinally from the connection 21 between the magnetic tape 1 and the leader tape LT in the ranges of 10 m to 210 m, 350 m to 550 m, and 700 m to 900 m, respectively, to produce three 200 m long tape samples MT1.

[0158] Next, the index Ts was determined from the three tape samples MT1 as follows. First, the tape sample 1 was placed in the drive device of the evaluation device 200 shown in FIG. 15. A Mountain Engendering Tape Transport System was used as the drive device. The measurement conditions for the evaluation device 200 were as follows: Light source: MORITEX red LED (wavelength 620 nm); CCD camera: Sony XC-75; horizontal resolution = L: 640 pix × T: 480 pix, vertical resolution 256 (8 bits); objective lens: TV-Z-H (magnification 4x); a dummy head 70 (glass pseudo head) 70 was pressed into the tape sample, and the wrap angle was set to 5°. Measurement environment: 23°C ± 2°C, 40% RH or higher and 60% RH or lower. The tape sample MT1 was run at a speed of 5 m / s. The tape sample 1 was set to 0.6 N.

[0159] Next, the tape sample 1 was run by the drive device, and the spacing state of the tape sample 1 was observed at three positions by the evaluation device 200, and 2D profiles P1(L,T) to P3(L,T) were acquired (see FIG. 18 ). The measurement positions were near the center in the width direction of the magnetic tape 1 (specifically, region R in FIG. 16 ). The 2D profiles P1(L,T) to P3(L,T) were acquired after at least three seconds had passed since the start of running, after the running speed had stabilized at 5 m / s, and during one run.

[0160] Position L in the 2D profile P1(L, T) indicates the position of the tape sample 1 in the longitudinal direction (X-axis direction) and the running direction of the tape sample 1, and position T in the 2D profile P1(L, T) indicates the position of the tape sample 1 in the width direction (Y-axis direction).

[0161] Next, the arithmetic mean of the 2D profiles P1(L,T) to P3(L,T) at the same L, T position was taken as the 2D profile Pa(L,T) in the spacing state. Next, the index Ts was calculated from the 2D profile Pa(L,T) in the spacing state as follows.

[0162] The profiles of the 2D profile Pa(L,T) within a specified range R' (see FIG. 18) at the same widthwise position T (position in the Y-axis direction) are arithmetically averaged to calculate an average 1D profile PaT(T) within the specified range R'. Here, the specified range R' is a range of 450 μm or more and 550 μm or less in the running direction of the tape sample MT1 from one end in the widthwise direction of the recording surface 22 of the dummy 70 (one end on the upstream side in the running direction of the tape sample MT1). The specified range R' has a long, narrow rectangular shape with a width of 100 μm and centered on the center line of the dummy 70.

[0163] 19 is a graph showing an example of an average 1D profile PaT(T). Only the neighborhood RT (width 700 μm) of the first region R1 in the average 1D profile PaT(T) was focused on, and the central portion of the first region R1 of the average 1D profile PaT(T) in the neighborhood RT of the first region R1 was determined as PaT(C). The spacing amount in this PaT(C) was determined as SPc (nm) (SPc may also be calculated by averaging several points near the central portion).

[0164] Next, the points on PaT(T) at the spacing amount where SPc is multiplied by 1.5 were determined to be PaT(A) and PaT(B). If there were multiple points that corresponded to PaT(A), the point closest to PaT(C) was determined to be PaT(A). The same applies to PaT(B). If PaT(A) and PaT(B) were not within the region corresponding to the first region R1, the points corresponding to the edges of the first region R1 were determined to be PaT(A) and PaT(B). The width values ​​of PaT(A) and PaT(B) determined in this manner were used as the index ts.

[0165] The three indices ts obtained from the three tape samples MT1 in the above manner were arithmetically averaged, and the result was taken as the final indices Ts. The indices Ts obtained in this manner were used to calculate the indices Mrg using the following equation. Note that 96 μm is the assumed width (Y-axis direction) of the servo element 26. Mrg (μm) = Ts (μm) - 96 (μm)

[0166] Mrg was calculated for each of Comparative Examples 1 to 5 and Examples 1 to 11 in Fig. 13. The Mrg value for Comparative Example 1 was set to Mrg0 (reference: 100%), and the ratio (%) calculated as a relative ratio of the Mrg values ​​for Comparative Examples 2 to 5 and Examples 1 to 11 was R_Mrg in Fig. 13.

[0167] [Evaluation of Running Stability of Magnetic Tape 1] Next, the evaluation of the running stability of the magnetic tape 1 in Figure 13 will be described. First, the magnetic tape 1 was incorporated into an LTO cartridge, and then the LTO cartridge was loaded into an LTO drive connected to a PC (personal computer) via serial cable communication, and the magnetic tape 1 was run. Next, of the multiple servo bands SB written on the magnetic tape 1, the servo band SB closest to one edge in the width direction of the magnetic tape 1 was used, and the actuator of the drive head was operated so that the drive head followed the servo track, and the magnetic tape 1 was run. At this time, a statistical value σSW-1 indicating the nonlinearity of the servo pattern 7 was measured from the obtained servo signal. The method described in Japanese Patent No. 6624332 was used to measure the statistical value σSW-1.

[0168] Next, the servo band SB closest to the other edge in the width direction of the magnetic tape 1, i.e., the servo band SB, was used to calculate σSW-2. The arithmetic mean of the data of σSW-1 and σSW-2 was calculated, and the obtained value was designated as σSW (nm).

[0169] σSW was calculated for each of Comparative Examples 1 to 5 and Examples 1 to 11 in Fig. 13. The value of σSW in Comparative Example 1 was set as (reference: 100%), and the ratios (%) calculated as relative ratios of the Mrg values ​​of Comparative Examples 2 to 5 and Examples 1 to 11 represent σSW in Fig. 13. The smaller the value of σSW, the higher the running stability, which is preferable from the viewpoint of running stability.

[0170] <<Various Modifications>> In the above explanation, the servo write head 13 is disposed so that the longitudinal direction (Y-axis direction) of the servo write head 13 coincides with the direction corresponding to the width direction (Y'-axis direction) of the magnetic tape 1. However, the servo write head 13 may also be disposed so that its longitudinal direction (Y-axis direction) is inclined at a predetermined azimuth angle θ1 with respect to the width direction (Y'-axis direction) of the magnetic tape 1.

[0171] FIG. 20 shows an example in which the longitudinal direction (Y-axis direction) of the servo write head 13 is inclined at a predetermined azimuth angle θ1 with respect to the width direction (Y′-axis direction) of the magnetic tape 1. In FIG.

[0172] FIG. 20 shows a servo write head 13 (left side) having a rectangular type recording surface 22 and a servo write head 13 (right side) having a T-type recording surface 22, each of which is positioned at an angle of a predetermined azimuth angle θ1.

[0173] Fig. 21 is a diagram showing another example in which the longitudinal direction (Y-axis direction) of the servo write head 13 is inclined at a predetermined azimuth angle θ1 with respect to the width direction (Y'-axis direction) of the magnetic tape 1. In Fig. 21, the left side shows a rectangular type, and the right side shows a T-type.

[0174] As shown in Figure 21, when the longitudinal direction (Y-axis direction) of the servo write head 13 is positioned so that it is inclined at a predetermined azimuth angle θ1 with respect to the width direction (Y'-axis direction) of the magnetic tape 1, the direction in which the first groove portion 61 and the second groove portion 63 are cut may be set to coincide with the running direction of the magnetic tape 1.

[0175] 9, 20, etc., the direction (second direction) in which the first groove 61 and the second groove 63 are cut is set to a direction that is 90 degrees (substantially 90 degrees: including an error of about ±3 degrees due to manufacturing errors) with respect to the longitudinal direction (Y-axis direction: first direction) of the servo write head 13. On the other hand, in the example shown in Fig. 21, the direction (second direction) in which the first groove 61 and the second groove 63 are cut is not a direction that is 90 degrees with respect to the longitudinal direction (Y-axis direction: first direction) of the servo head.

[0176] Typically, the direction (second direction) in which the first groove 61 and the second groove 63 are cut is the direction of θ2 in Fig. 22 with respect to the longitudinal direction (Y-axis direction: first direction) of the servo write head 13. This θ2 corresponds to the angle obtained by subtracting the azimuth angle θ1 of the servo write head 13 from 90°.

[0177] In this case, in the rectangular type (left side of FIG. 21), the first region R1 is a parallelogram, and in the T-type (right side of FIG. 22), the first region R1 is a distorted T-shape.

[0178] The present technology can also have the following configurations. (1) A servo write head comprising: a plurality of first regions each including a servo element that writes a servo pattern on a magnetic tape and arranged at predetermined intervals along a first direction; a plurality of second regions each including a plurality of first groove portions having a first groove width and cut along a second direction that intersects with the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least a portion of which has a second groove width wider than the first groove width and each including second groove portions cut along the second direction. (2) The servo write head according to (1), wherein the second groove width is constant in the second direction. (3) The servo write head according to (1), wherein the second groove width is not constant in the second direction. (4) The servo write head according to (3) above, wherein the second groove portion has a groove width on a side corresponding to the downstream side of the flow of the magnetic tape that is wider than the groove width on a side corresponding to the upstream side of the flow of the magnetic tape. (5) The servo write head according to (4) above, wherein the second groove portion includes a third groove portion located on the upstream side of the flow of the magnetic tape and having a third groove width, and a fourth groove portion located on the downstream side of the flow of the magnetic tape and having a fourth groove width that is wider than the third groove width. (6) The servo write head according to (4) or (5) above, wherein the servo write head includes a pair of second groove portions that are positioned to sandwich the first region in the first direction, and the pair of second groove portions are formed symmetrically with respect to a line that passes through the center of the first region in the first direction and is along the second direction. (7) The servo write head according to (1) or (2) above, wherein the width of the first region in the first direction is constant in the second direction. (8) The servo write head according to any one of (1) and (3) to (6) above, wherein the width of the first region in the first direction is not constant in the second direction.(9) The servo write head according to (7) above, wherein the first region has a width that is wider on the side corresponding to the upstream side of the flow of the magnetic tape than on the side corresponding to the downstream side of the flow of the magnetic tape. (10) The servo write head according to (9) above, wherein the first region has a first portion having a first width in the first direction and a second portion including a pair of protrusions that protrude outward from the first portion on both ends in the first direction and having a second width in the first direction that is wider than the first width. (11) The servo write head according to (9) or (10) above, wherein the first region is formed symmetrically with respect to a line that passes through the center of the first region in the first direction and is along the second direction. (12) The servo write head according to any one of (1) to (11) above, wherein the second direction is a direction that is at an angle of 90 degrees with respect to the first direction. (13) The servo write head according to any one of (1) to (11) above, wherein the longitudinal direction of the servo write head is inclined at a predetermined azimuth angle with respect to the width direction of the magnetic tape, and the second direction is a direction corresponding to an angle obtained by subtracting an angle corresponding to the azimuth angle from 90 degrees with respect to the first direction. (14) The servo write head according to any one of (1) to (13) above, wherein the width of the first region in the first direction is 300 μm or less. (15) The servo write head according to any one of (1) to (14) above, wherein the second groove width is 100 μm or more. (16) The servo write head according to (10) above, wherein the width of the protrusion in the first region in the first direction is 100 μm or more. (17) The servo write head according to (10) or (16) above, wherein the length of the protrusion in the first region in the second direction is 150 μm or more.(18) A servo recording device comprising a servo write head having: a plurality of first regions arranged at predetermined intervals along a first direction, each including a servo element for writing a servo pattern on a magnetic tape; a plurality of second regions each including a plurality of first groove portions having a first groove width and cut along a second direction that intersects with the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least a portion of which has a second groove width wider than the first groove width and each including a second groove portion cut along the second direction. (19) A method for manufacturing a magnetic tape, in which a servo pattern is written on the magnetic tape by a servo write head including: a plurality of first regions arranged at predetermined intervals along a first direction, each including a servo element for writing a servo pattern on the magnetic tape; a plurality of second regions each including a plurality of first groove portions having a first groove width and cut along a second direction that intersects with the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least a portion of which has a second groove width wider than the first groove width and each including second groove portions cut along the second direction. (20) A method for recording a servo pattern, in which a servo write head includes: a plurality of first regions, each including a servo element for writing a servo pattern onto a magnetic tape, and arranged at predetermined intervals along a first direction; a plurality of second regions, each including a plurality of first groove portions having a first groove width and cut along a second direction that intersects with the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions, at least a portion of which has a second groove width wider than the first groove width, each including a second groove portion cut along the second direction, and corresponding to regions between the first and second regions.

[0179] REFERENCE SIGNS LIST 1 magnetic tape 7 servo pattern 13 servo write head 22 recording surface 26 servo element 61 first groove portion 62 convex portion 63 second groove portion 100 servo pattern recording device R1 first region R2 second region R3 third region

Claims

1. A servo write head comprising: a plurality of first regions arranged at predetermined intervals along a first direction, each region including a servo element for writing a servo pattern to a magnetic tape; a plurality of second regions each including a plurality of first groove portions having a first groove width and cut along a second direction that intersects with the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least some of which have a second groove width wider than the first groove width and each including a second groove portion cut along the second direction.

2. A servo write head according to claim 1, wherein the second groove width is constant in the second direction.

3. A servo write head according to claim 1, wherein the second groove width is not constant in the second direction.

4. A servo write head according to claim 3, wherein the second groove has a groove width on the downstream side of the flow of the magnetic tape that is wider than the groove width on the upstream side of the flow of the magnetic tape.

5. A servo write head according to claim 4, wherein the second groove portion includes a third groove portion located upstream of the flow of the magnetic tape and having a third groove width, and a fourth groove portion located downstream of the flow of the magnetic tape and having a fourth groove width wider than the third groove width.

6. A servo write head as claimed in claim 4, comprising a pair of second grooves arranged at positions sandwiching the first region in the first direction, the pair of second grooves being formed symmetrically with respect to a line that passes through the centre of the first region in the first direction and is aligned with the second direction.

7. A servo write head according to claim 1, wherein the width of said first region in said first direction is constant in said second direction.

8. A servo write head according to claim 1, wherein the width of said first region in said first direction is not constant in said second direction.

9. A servo write head according to claim 7, wherein the first region has a width that is wider on the side corresponding to the upstream side of the flow of the magnetic tape than on the side corresponding to the downstream side of the flow of the magnetic tape.

10. A servo write head according to claim 9, wherein the first region has a first portion having a first width in the first direction, and a second portion including a pair of protrusions that protrude outward beyond the first portion on both ends in the first direction, and having a second width in the first direction that is wider than the first width.

11. A servo write head according to claim 9, wherein the first region is formed symmetrically with respect to a line that passes through the center of the first region in the first direction and is aligned with the second direction.

12. A servo write head according to claim 1, wherein the second direction is a direction that is 90 degrees to the first direction.

13. A servo write head according to claim 1, wherein the servo write head is disposed with its longitudinal direction inclined at a predetermined azimuth angle with respect to the width direction of the magnetic tape, and the second direction is a direction corresponding to an angle obtained by subtracting an angle corresponding to the azimuth angle from 90 degrees with respect to the first direction.

14. A servo write head according to claim 1, wherein the width of said first region in said first direction is 300 μm or less.

15. A servo write head according to claim 1, wherein the second groove width is 100 μm or more.

16. A servo write head according to claim 10, wherein the width of the protrusion in the first region in the first direction is 100 μm or more.

17. A servo write head according to claim 10, wherein the length of the protrusion in the first region in the second direction is 150 μm or more.

18. A servo pattern recording device comprising a servo write head having: a plurality of first regions arranged at predetermined intervals along a first direction, each including a servo element for writing a servo pattern onto a magnetic tape; a plurality of second regions each including a plurality of first groove portions having a first groove width and cut along a second direction intersecting the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least a portion of which has a second groove width wider than the first groove width and each including second groove portions cut along the second direction.

19. A method for manufacturing a magnetic tape in which a servo pattern is written on the magnetic tape using a servo write head comprising: a plurality of first regions arranged at predetermined intervals along a first direction, each region including a servo element for writing a servo pattern on the magnetic tape; a plurality of second regions each including a plurality of first groove portions having a first groove width and cut along a second direction intersecting the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least a portion of which has a second groove width wider than the first groove width and each including second groove portions cut along the second direction.

20. A method for writing servo patterns onto magnetic tape using a servo write head comprising: a plurality of first regions arranged at predetermined intervals along a first direction, each region including a servo element for writing servo patterns onto magnetic tape; a plurality of second regions each including a plurality of first grooves having a first groove width and cut along a second direction intersecting the first direction, and arranged alternately with the first regions in the first direction; and a plurality of third regions corresponding to regions between the first and second regions, at least a portion of which has a second groove width wider than the first groove width and each including a second groove cut along the second direction.

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