Servo pattern recording method, servo pattern recording device, magnetic tape manufacturing method, magnetic tape, and tape cartridge

Abstract

The servo pattern recording method according to one aspect of the present technology involves recording a servo pattern in a plurality of servo bands that are arranged at intervals in the width direction of a magnetic layer in a magnetic tape, the method including: causing the magnetic tape to travel with a prescribed tension; and recording a servo pattern in the plurality of servo bands at a second pitch narrower than a first pitch, which is the positioning interval of two servo lead heads in a tape drive device that records data in the magnetic layer or that plays back data recorded in the magnetic layer.

Description

[Technical Field]

[0001] The present technology relates to a servo pattern recording method, a servo pattern recording device, a magnetic tape manufacturing method, a magnetic tape, and a tape cartridge. [Background technology]

[0002] In recent years, magnetic recording media have been widely used for purposes such as backing up electronic data. Magnetic tape cartridges, for example, are one type of magnetic recording media and are attracting increasing attention as a storage medium for big data, etc., due to their large capacity and long-term storage capabilities.

[0003] LTO (Linear Tape Open) standard magnetic tape has multiple data bands parallel to the tape longitudinal direction, and data is recorded on multiple recording tracks within these multiple data bands. Furthermore, the magnetic tape has multiple servo bands parallel to the tape longitudinal direction, and each data band is disposed on the magnetic layer so as to be sandwiched between the multiple servo bands. Each servo band controls the positioning (tracking) of a read / write head relative to each recording track, and also records a servo pattern of a predetermined shape in which servo band identification information for identifying the tape and the data band is embedded (see, for example, Patent Documents 1 and 2). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2011-523487 [Patent Document 2] Japanese Patent Application Laid-Open No. 2005-285268 Summary of the Invention [Problem to be solved by the invention]

[0005] Magnetic tape is typically manufactured through processes such as coating a base film with a magnetic material, calendering, cutting, and recording servo patterns. Because these processes are performed while the base film is wound under a constant tension, the finished magnetic tape has internal distortion and tends to widen over time. Therefore, when recording or reproducing data using a tape drive, even if the magnetic tape is run under the same tension as when the servo patterns were recorded, the width of the magnetic tape may increase from the width of the magnetic tape when the servo patterns were recorded. In this case, the spacing between adjacent servo bands changes, which in turn causes fluctuations in the spacing of the servo patterns recorded on these servo bands, making it difficult to achieve the desired tracking control. This problem can become more pronounced as magnetic tape becomes thinner due to the recent trend toward higher recording capacities.

[0006] In view of the above circumstances, an object of the present technology is to provide a servo pattern recording method, a servo pattern recording device, a magnetic tape manufacturing method, a magnetic tape, and a tape cartridge that can ensure desired tracking control. [Means for solving the problem]

[0007] A servo pattern recording method according to one aspect of the present technology is a method for recording servo patterns on a plurality of servo bands arranged at intervals in a width direction of a magnetic layer of a magnetic tape, the method comprising: The magnetic tape is run at a predetermined tension, Servo patterns are recorded on the plurality of servo bands at a second pitch that is narrower than a first pitch, which is the spacing between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer.

[0008] A servo pattern recording device according to one embodiment of the present technology is a device that records servo patterns on a plurality of servo bands arranged at intervals in the width direction of a magnetic layer of a magnetic tape, and is equipped with a servo write head having a plurality of recording portions arranged corresponding to the plurality of servo bands. The multiple recording units each have a magnetic gap that records a servo pattern on the multiple servo bands at a second pitch that is narrower than a first pitch, which is the spacing between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer.

[0009] A method for manufacturing a magnetic tape according to one aspect of the present technology is a method for manufacturing a magnetic tape having a magnetic layer with a plurality of servo bands arranged at intervals in a width direction, the method comprising: The magnetic tape is run at a predetermined tension, Servo patterns are recorded on the plurality of servo bands at a second pitch that is narrower than a first pitch, which is the spacing between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer.

[0010] A magnetic tape according to one embodiment of the present technology includes a magnetic layer having a plurality of servo bands arranged at intervals in the width direction. The magnetic layer has at least a portion in which the servo band pitch, which is the distance between two adjacent servo bands, is narrower than the spacing between two servo read heads in a tape drive device that records information on the magnetic layer or reproduces information recorded on the magnetic layer.

[0011] A tape cartridge according to one aspect of the present technology includes a cartridge case, a tape reel rotatably housed inside the cartridge case, and a magnetic tape wound around the tape reel. The magnetic tape has a magnetic layer on which a plurality of servo patterns are recorded at intervals in the tape width direction. The magnetic layer has a first region in which the servo band pitch, which is the distance between two adjacent servo bands, is narrower than the spacing between two servo read heads in a tape drive device that records information on the magnetic layer or reproduces information recorded on the magnetic layer, and a second region in which the servo band pitch is wider than the spacing between the two servo read heads. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is an exploded perspective view showing a tape cartridge according to an embodiment of the present technology. [Figure 2] 1 is a schematic diagram of a magnetic tape according to an embodiment of the present technology, viewed from the side; [Figure 3] FIG. 2 is a schematic diagram of the magnetic tape as viewed from above (magnetic layer side). [Figure 4] FIG. 2 is an enlarged view showing recording tracks in a data band of the magnetic tape. [Figure 5] FIG. 2 is an enlarged view showing a servo pattern written in a servo band of the magnetic tape. [Figure 6] FIG. 1 illustrates a tape drive device. [Figure 7] FIG. 2 is a schematic diagram of a drive head in the tape drive device. [Figure 8] FIG. 2 is a diagram showing the state when the tape drive device is recording / reproducing a data signal. [Figure 9] 1 is a front view showing a servo pattern recording device according to an embodiment of the present technology; [Figure 10] FIG. 1 is a partially enlarged view showing a part of the servo pattern recording device. [Figure 11] 1A is a diagram showing the data structure of an LPOS word embedded in a servo pattern, and FIG. 1B is a diagram explaining a manufacturer word. [Figure 12] 1A is a schematic plan view showing an example of the arrangement of the servo pattern 6, and FIG. 1B is a diagram showing the reproduced waveform thereof. [Figure 13]3A and 3B are schematic diagrams showing configuration examples of a first servo pattern and a second servo pattern. [Figure 14] 3A and 3B are diagrams showing reproduced waveforms of the first servo pattern and the second servo pattern, respectively. [Figure 15] FIG. 2 is a perspective view schematically showing the configuration of a servo write head in the servo pattern recording device. [Figure 16] FIG. 2 is a block diagram showing a configuration of a drive unit in the servo pattern recording device. [Figure 17] 3A and 3B are diagrams each schematically showing a recording signal waveform of a first servo subframe in a first pulse signal and a second pulse signal. [Figure 18] 3 is a diagram showing the arrangement intervals of magnetic gaps provided in the servo write head. FIG. [Figure 19] FIG. 10 is a diagram showing an experimental result of the servo band pitch of a magnetic tape measured using the tape drive device. [Figure 20] 10A and 10B are diagrams showing other experimental results of the servo band pitch of the magnetic tape measured using the tape drive device. [Figure 21] FIG. 10 is a diagram showing still another experimental result of the servo band pitch of the magnetic tape measured using the tape drive device. [Figure 22] 10A and 10B are diagrams illustrating a method for measuring a servo band pitch using the tape drive device. [Figure 23] FIG. 10 is an explanatory diagram of a method for measuring a servo trace line. [Figure 24] FIG. 2 is an explanatory diagram of the particle shape of hexagonal ferrite, which is a magnetic powder. DETAILED DESCRIPTION OF THE INVENTION

[0013] Hereinafter, embodiments of the present technology will be described with reference to the drawings.

[0014] <Overall system configuration and configuration of each part> [Tape cartridge] 1 is an exploded perspective view showing a tape cartridge 10 according to an embodiment of the present technology. In the description of this embodiment, the tape cartridge 10 will be described as an example of a tape cartridge that complies with the LTO standard.

[0015] As shown in Figure 1, the tape cartridge 10 comprises a cartridge case 11, a tape reel 13, and a magnetic tape 1. The cartridge case 11 is constructed by joining an upper shell 11a and a lower shell 11b with a plurality of screws. Inside the cartridge case 11, a single tape reel 13 around which the magnetic tape 1 is wound is rotatably housed.

[0016] A ring-shaped chucking gear (not shown) that engages with a spindle 31 (see FIG. 6) of the tape drive device 30 is formed in the center of the bottom of the tape reel 13. This chucking gear is exposed to the outside through an opening 14 formed in the center of the lower shell 11b. An annular metal plate 15 that is magnetically attracted to the spindle 31 is fixed to the inner periphery of this chucking gear.

[0017] A reel spring 16, a reel lock member 17, and a spider 18 are disposed between the inner surface of the upper shell 11a and the tape reel 13. These components form a reel lock mechanism that prevents the tape reel 13 from rotating when the cartridge 10 is not in use.

[0018] A tape pull-out opening 19 for pulling out one end of the magnetic tape 1 to the outside is provided on one side wall of the cartridge case 11. A slide door 20 for opening and closing the tape pull-out opening 19 is disposed inside this side wall. The slide door 20 is configured to slide in the direction of opening the tape pull-out opening 19 against the biasing force of a torsion spring 21 by engaging with a tape loading mechanism (not shown) of the tape drive device 30.

[0019] A leader pin 22 is fixed to one end of the magnetic tape 1. The leader pin 22 is configured to be detachable from a pin holder 23 provided on the inside of the tape pull-out opening 19. The pin holder 23 is equipped with elastic holders 24 that elastically hold the upper and lower ends of the leader pin 22 on the inner surface of the top wall (inner surface of the upper shell 11a) and the inner surface of the bottom wall (inner surface of the lower shell 11b) of the cartridge case 11, respectively.

[0020] Inside the other side wall of the cartridge case 11, there is arranged a safety tab 25 for preventing accidental erasure of information recorded on the magnetic tape 1, as well as a cartridge memory 9 that can read and write contents related to the data recorded on the magnetic tape 1 without contact.

[0021] Fig. 2 is a schematic diagram of the magnetic tape 1 as seen from the side, and Fig. 3 is a schematic diagram of the magnetic tape 1 as seen from above (the magnetic layer 43 side). As shown in Figs. 2 and 3, the magnetic tape 1 is configured as a tape that is long in the longitudinal direction (X-axis direction), short in the width direction (Y-axis direction), and thin in the thickness direction (Z-axis direction).

[0022] The magnetic tape 1 includes a tape-shaped substrate 41 that is long in the longitudinal direction (X-axis direction), an underlayer (non-magnetic layer) 42 provided on one main surface of the substrate 41, a magnetic layer 43 provided on the underlayer 42, and a back layer 44 provided on the other main surface of the substrate 41. The back layer 44 may be provided as needed, and may be omitted. The magnetic tape 1 may be a perpendicular recording type magnetic recording medium or a longitudinal recording type magnetic recording medium. The magnetic layer 43 may be a coated film of a magnetic material, or may be a vapor-deposited or sputtered film of a magnetic material. The layers that make up the magnetic tape 1 will be described in detail later.

[0023] 3, the magnetic layer 43 has a plurality of data bands d (data bands d0 to d3) that are long in the longitudinal direction (X-axis direction) in which data is written, and a plurality of servo bands s (servo bands s0 to s4) that are long in the longitudinal direction in which servo patterns 6 are written. The servo bands s are arranged at positions that sandwich each data band d in the width direction (Y-axis direction).

[0024] In this technology, the ratio of the area of ​​the servo bands s to the area of ​​the entire surface of the magnetic layer 43 is typically 4.0% or less. The width of the servo bands s is, for example, 96 μm or less for a ½ inch tape width. The ratio of the area of ​​the servo bands s to the area of ​​the entire surface of the magnetic layer 43 can be measured, for example, by developing the magnetic tape 1 with a developer such as a ferricolloid developer, and then observing the developed magnetic tape 1 with an optical microscope.

[0025] 3 shows an example in which the number of data bands d is 4 and the number of servo bands s is 5. Note that the number of data bands d and the number of servo bands s can be changed as appropriate.

[0026] The data band d includes a plurality of recording tracks 5 that are long in the longitudinal direction and aligned in the width direction. The number of recording tracks 5 included in one data band d is, for example, about 1,000 to 2,000. Data is recorded along these recording tracks 5 within the recording tracks 5. The length of one bit in the longitudinal direction of the data recorded in the data band d is, for example, 48 nm or less. The servo band s includes a servo pattern 6 of a predetermined shape that is recorded by a servo pattern recording device (see FIG. 9) described later.

[0027] Here, the number of recording tracks 5 of LTO-standard magnetic tape 1 has increased with each generation, dramatically improving recording capacity. For example, the original LTO-1 had 384 recording tracks 5, but the number of recording tracks 5 for LTO-2 to LTO-8 has increased to 512, 704, 896, 1280, 2176, 3584, and 6656, respectively. Similarly, the data recording capacity for LTO-1 was 100 GB (gigabytes), but for LTO-2 to LTO-8 it is 200 GB, 400 GB, 800 GB, 1.5 TB (terabytes), 2.5 TB, 6.0 TB, and 12 TB, respectively.

[0028] In this embodiment, the number of recording tracks 5 and the recording capacity are not particularly limited and can be changed as appropriate. However, it is advantageous to apply this to a magnetic tape 1 that has a large number of recording tracks 5 and a large recording capacity (for example, 6656 or more tracks, 12 TB or more: LTO8 or later) and is susceptible to variations in the width of the magnetic tape 1.

[0029] [Data band and servo band]

[0030] FIG. 4 is an enlarged view showing recording tracks 5 in a data band d. As shown in FIG. 4, the recording tracks 5 are long in the longitudinal direction, aligned in the width direction, and each track has a predetermined recording track width (track pitch) Wd in the width direction. This recording track width Wd is typically 2.0 μm or less. Note that such recording track width Wd can be measured, for example, by developing the magnetic layer 43 of the magnetic tape 1 with a developer such as a ferricolloid developer, and then observing the developed magnetic layer 43 of the magnetic tape 1 with an optical microscope. Alternatively, as a measurement method using the drive head, the recording track width Wd can be measured from the change in output when the drive head is in a read-while-write state, ignoring fluctuations during tape travel. (IEEE_Sept1996_Crosstrack Profiles of Thin Film MR Tape Heads Using the Azimuth Displacement Method)

[0031] FIG. 5 is an enlarged view of a servo pattern 6 written in a servo band s. As shown in FIG. 5, the servo pattern 6 includes a plurality of stripes that are inclined at a predetermined azimuth angle α with respect to the width direction (Y-axis direction), details of which will be described later. These stripes are classified into a first group of stripes 61 that are inclined clockwise with respect to the width direction (Y-axis direction) and a second group of stripes 62 that are inclined counterclockwise with respect to the width direction. Each of the first group of stripes 61 and the second group of stripes 62 typically includes four or five stripes. The shape of the servo pattern 6 can be measured, for example, by developing the magnetic layer 43 of the magnetic tape 1 using a developer such as a ferricolloid developer and then observing the developed magnetic layer 43 of the magnetic tape 1 with an optical microscope.

[0032] 5, servo trace lines T, which are lines traced by a servo read head 132 (see FIG. 7), which will be described later, on the servo pattern 6, are shown by dashed lines. The servo trace lines T are set along the longitudinal direction (X-axis direction) and are set at predetermined intervals Ps in the width direction.

[0033] The number of servo trace lines T per servo band s is, for example, about 30 to 60. The spacing Ps between two adjacent servo trace lines T is the same as the recording track width Wd, and is, for example, 2.0 μm or less. Here, the spacing Ps between two adjacent servo trace lines T is a value that determines the recording track width Wd. In other words, if the spacing Ps between the servo trace lines T is narrowed, the recording track width Wd becomes smaller and the number of recording tracks 5 included in one data band d increases. As a result, the data recording capacity increases.

[0034] [Tape drive device] 6 is a diagram showing a tape drive device 30. The tape drive device 30 is a data recording / reproducing device capable of recording data on a magnetic tape 1 or reproducing data recorded on the magnetic tape 1.

[0035] 6, the tape drive device 30 is configured to be able to load a cartridge 10. The tape drive device 30 is configured to be able to load one cartridge 10, but may be configured to be able to load multiple cartridges 10 simultaneously.

[0036] The tape drive device 30 includes a spindle 31, a take-up reel 32, a spindle drive device 33, a reel drive device 34, a plurality of guide rollers 35, a drive head 36, a reader / writer 37, and a control device 38. The tape drive device 30 may further include a thermometer 39, a hygrometer 40, etc.

[0037] The spindle 31 has a head portion that engages with the chucking gear of the tape reel 13 through an opening 14 formed in the lower shell 11b of the cartridge 10. The spindle 31 lifts the tape reel 13 a predetermined distance against the biasing force of the reel spring 16, thereby releasing the reel lock function of the reel lock member 17. As a result, the tape reel 13 is rotatably supported inside the cartridge case 11 by the spindle 31.

[0038] The spindle drive device 33 rotates the spindle 31 in response to a command from the control device 38. The take-up reel 32 is configured to be able to fix the leading end (leader pin 22) of the magnetic tape 1 pulled out from the cartridge 10 via a tape loading mechanism (not shown).

[0039] A plurality of guide rollers 35 guide the running of the magnetic tape 1 so that the tape path formed between the cartridge 10 and the take-up reel 32 has a predetermined relative positional relationship with the drive head 36. The reel drive device 34 rotates the take-up reel 32 in response to commands from the control device 38.

[0040] When data is recorded on / played back from the magnetic tape 1, the spindle 31 and take-up reel 32 are rotated by the spindle drive device 33 and the reel drive device 34, causing the magnetic tape 1 to run. The magnetic tape 1 can run back and forth in the forward direction indicated by arrow A1 in Fig. 6 (the direction in which the tape is unwound from the tape reel 13 side to the take-up reel 32 side), and in the reverse direction indicated by arrow A2 (the direction in which the tape is rewound from the take-up reel 32 side to the tape reel 13 side).

[0041] In this embodiment, the tension in the longitudinal direction (X-axis direction) of the magnetic tape 1 during data recording / playback can be adjusted by controlling the rotation of the spindle 31 by the spindle drive device 33 and the rotation of the take-up reel 32 by the reel drive device 34. The tension of the magnetic tape 1 may be adjusted by controlling the movement of the guide roller 35, a tension control unit including a dancer roller, or the like, instead of (or in addition to) controlling the rotation of the spindle 31 and the take-up reel 32.

[0042] The reader / writer 37 is configured to be able to record management information in the cartridge memory 9 in response to a command from the control device 38. The reader / writer 37 is also configured to be able to read management information from the cartridge memory 9 in response to a command from the control device 38. As a communication method between the reader / writer 37 and the cartridge memory 9, for example, the ISO14443 method is adopted.

[0043] The control device 38 includes, for example, a control unit, a storage unit, a communication unit, etc. The control unit is configured, for example, with a CPU (Central Processing Unit) or the like, and performs overall control of each unit of the tape drive device 30 in accordance with a program stored in the storage unit.

[0044] The storage unit includes a non-volatile memory in which various data and programs are recorded, 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 storage unit temporarily or non-temporarily stores information from the cartridge memory 9 read by the reader / writer 27, outputs from the thermometer 39 and the hygrometer 40, etc. The communication unit is configured to be able to communicate with other devices such as a PC (Personal Computer) or a server device.

[0045] The drive head 36 is configured to be able to record data on the magnetic tape 1 in response to a command from the control device 38. The drive head 36 is also configured to be able to reproduce data written on the magnetic tape 1 in response to a command from the control device 38.

[0046] The drive head 36 is composed of a head unit having, for example, two servo read heads, a plurality of data write / read heads, etc. Fig. 7 is a schematic diagram of the drive head 36 as seen from the bottom (tape running surface).

[0047] 7, the drive head 36 includes a first drive head portion 36a and a second drive head portion 36b. The first drive head portion 36a and the second drive head portion 36b are configured symmetrically in the X'-axis direction (the running direction of the magnetic tape 1 (the X-axis direction in FIG. 3)). The first drive head portion 36a and the second drive head portion 36b are configured to be movable in the width direction of the magnetic tape 1 (the Y-axis direction in FIG. 3).

[0048] The first drive head unit 36a is a drive head that is used when the magnetic tape 1 runs in the forward direction (direction A1 in FIG. 6). On the other hand, the second drive head unit 36b is a drive head that is used when the magnetic tape 1 runs in the reverse direction (direction A2 in FIG. 6). The first drive head unit 36a and the second drive head unit 36b basically have the same configuration, so the first drive head unit 36a will be described as a representative example.

[0049] The first drive head unit 36 ​​a has a head body 131 , two servo read heads 132 , and a plurality of data write / read heads 133 .

[0050] The servo read head 132 is configured to be able to reproduce servo signals by using an MR element (MR: Magneto-Resistive effect) or the like to read magnetic flux generated from magnetic information recorded on the servo bands s of the magnetic tape 1. In other words, the servo read head 132 reads the servo patterns 6 recorded on the servo bands s, thereby reproducing the servo signals.

[0051] The servo read heads 132 are provided one on each end of the head body 131 in the width direction (Y'-axis direction in FIG. 7). MR elements include anisotropic magnetoresistive effect elements (AMR: Anisotropic Magneto-Resistive effect elements), giant magnetoresistive effect elements (GMR: Giant Magneto-Resistive effect elements), tunnel magnetoresistive effect elements (TMR: Tunnel Magneto-Resistive effect elements), etc. The spacing between the two servo read heads 132 in the width direction (Y'-axis direction) is approximately the same as the distance between adjacent servo bands s on the magnetic tape 1, and details of this will be described later.

[0052] The data write / read heads 133 are arranged at equal intervals along the width direction (Y'-axis direction). Each data write / read head 133 is arranged at a position sandwiched between two servo read heads 132. The number of data write / read heads 133 is, for example, about 20 to 40, but is not particularly limited to this number.

[0053] The data write / read head 133 includes a data write head 134 and a data read head 135. The data write head 134 is configured to be able to record a data signal on the data band d of the magnetic tape 1 by using a magnetic field generated from the magnetic gap. The data read head 135 is configured to be able to reproduce the data signal by reading the magnetic field generated from the magnetic information recorded on the data band d of the magnetic tape 1 using an MR element (MR: Magneto Resistive effect) or the like. Examples of MR elements include an anisotropic magnetoresistive effect element (AMR: Anisotropic Magneto Resistive effect), a giant magnetoresistive effect element (GMR: Giant Magneto Resistive effect), a tunnel magnetoresistive effect element (TMR: Tunnel Magneto Resistive effect), and the like.

[0054] In the first drive head unit 36a, the data write head 134 is arranged to the left of the data read head 135 (upstream when the magnetic tape 1 flows in the forward direction). On the other hand, in the second drive head unit 36b, the data write head 134 is arranged to the right of the data read head 135 (upstream when the magnetic tape 1 flows in the reverse direction). The data read head 135 is capable of reproducing a data signal immediately after the data write head 134 writes the data signal to the magnetic tape 1.

[0055] Fig. 8 is a diagram showing the state when the first drive head unit 36a is recording / reproducing a data signal. Note that the example shown in Fig. 8 shows the state when the magnetic tape 1 is running in the forward direction (A1 direction).

[0056] 8, when the first drive head unit 36a records / reproduces a data signal, one of the two servo read heads 132 is positioned on one of two adjacent servo bands s and reads the servo pattern 6 on this servo band s. The other of the two servo read heads 132 is positioned on the other of the two adjacent servo bands s and reads the servo pattern 6 on this servo band s.

[0057] Based on the reproduced waveform of the servo pattern 6, the control device 38 determines whether the servo read head 132 is accurately tracing the target servo trace line T (see FIG. 5).

[0058] This principle will be explained below. As shown in Fig. 5, the first stripe group 61 and the second stripe group 62 in the servo pattern 6 are inclined in opposite directions with respect to the width direction (Y-axis direction). Therefore, on the upper servo trace line T, the distance between the first stripe group 61 and the second stripe group 62 in the longitudinal direction (X-axis direction) is relatively narrow. On the other hand, on the lower servo trace line T, the distance between the first stripe group 61 and the second stripe group 62 in the longitudinal direction (X-axis direction) is relatively wide.

[0059] Therefore, by calculating the difference between the time when the reproduced waveform of the first stripe group 61 is detected and the time when the reproduced waveform of the second stripe group 62 is detected, the current position of the servo read head 132 in the width direction (Y-axis direction) relative to the magnetic tape 1 can be determined.

[0060] Therefore, the control device 38 can determine whether the servo read head 132 is accurately tracing the target servo trace line T based on the reproduced waveform of the servo pattern 6. If the servo read head 132 is not accurately tracing the target servo trace line T, the control device 38 moves the drive head 36 in the width direction (Y'-axis direction) to adjust the position of the drive head 36. A method for measuring the servo trace line T traced by the servo read head 132 will be described later with reference to FIG. 23.

[0061] Returning to FIG. 8, if the magnetic tape 1 fluctuates in the width direction while it is running, the data write / read head 133 adjusts its position to follow the servo trace line T and records a data signal in the recording track 5.

[0062] Here, when the magnetic tape 1 is completely pulled out from the tape cartridge 10, the magnetic tape 1 now runs in the reverse direction (A2 direction). At this time, the second drive head portion 36b is used as the drive head 36. The servo trace line T used is the servo trace line T adjacent to the previous servo trace line T. In this case, the drive head 36 is moved in the width direction (Y'-axis direction) by the interval Ps between the servo trace lines T (= recording track width Wd). In this case, a data signal is recorded on a recording track 5 adjacent to the recording track 5 on which the data signal was previously recorded.

[0063] In this way, the magnetic tape 1 is reciprocated many times, with its running direction changed between forward and reverse, and data signals are recorded on the recording tracks 5. For example, assume that there are 50 servo trace lines T and the first drive head unit 36a (or the second drive head unit 36b) includes 32 data write / read heads 133. In this case, the number of recording tracks 5 included in one data band d is 50 x 32 = 1,600, and in order to record data signals on all of these recording tracks 5, the magnetic tape 1 must be reciprocated 25 times.

[0064] [Servo pattern recording device] Next, a description will be given of the configuration of a servo pattern recording device that records the servo patterns 6 on the servo bands s of the magnetic tape 1. Fig. 9 is a front view showing the servo pattern recording device 100 according to an embodiment of the present technology. Fig. 10 is a partially enlarged view showing a part of the servo pattern recording device 100.

[0065] 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 111, a pre-processing unit 112, a servo write head 113, a reproducing head unit 114, and a take-up roller 115. The servo pattern recording device 100 further includes a drive unit 120 and a controller 130. The controller 130 includes a control unit that comprehensively controls each unit of the servo pattern recording device 100, a recording unit that stores various programs and data required for processing by the control unit, a display unit that displays data, an input unit for inputting data, etc.

[0066] The feed roller 111 is capable of rotatably supporting the rolled magnetic tape 1 (before the servo pattern 6 is recorded). The feed roller 111 is rotated in response to the driving of a driving source such as a motor, and feeds out the magnetic tape 1 downstream in response to the rotation.

[0067] The take-up roller 115 is capable of rotatably supporting the rolled magnetic tape 1 (after the servo pattern 6 is recorded). The take-up roller 115 rotates in synchronization with the feed-out roller 111 in response to the drive of a drive source such as a motor, and takes up the magnetic tape 1 on which the servo pattern 6 is recorded as it rotates. The feed-out roller 111 and the take-up roller 115 are capable of moving the magnetic tape 1 at a constant speed on the transport path.

[0068] The servo write head 113 is disposed, for example, above the magnetic tape 1 (on the magnetic layer 43 side). The servo write head 113 may also be disposed below the magnetic tape 1 (on the substrate 41 side). The servo write head 113 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 43 (after pre-processing) of the magnetic tape 1.

[0069] As a result, the servo write head 113 magnetizes a portion of the magnetic layer 43 in the first direction to record the servo pattern 6 on the magnetic layer 43 (see the black arrows in FIG. 10 for the magnetization direction). The servo write head 113 is capable of recording the servo pattern 6 on each of the five servo bands s0 to s4 when the magnetic layer 43 passes below the servo write head 113.

[0070] The first direction, which is the magnetization direction of the servo pattern 6, includes a perpendicular component perpendicular to the top surface of the magnetic layer 43. That is, in this embodiment, since perpendicularly oriented or non-oriented magnetic powder is included in the magnetic layer 43, the servo pattern 6 recorded in the magnetic layer 43 includes a perpendicular magnetization component.

[0071] The pre-processing unit 112 is disposed, for example, below the magnetic tape 1 (toward the substrate 41) and upstream of the servo write head 113. The pre-processing unit 112 may also be disposed above the magnetic tape 1 (toward the magnetic layer 43). The pre-processing unit 112 includes a permanent magnet 112a that can rotate around the Y-axis direction (width direction of the tape 1) as the central axis of rotation. The shape of the permanent magnet 112a is, for example, cylindrical or polygonal prism, but is not limited to these.

[0072] Before the servo write head 113 records the servo pattern 6, the permanent magnet 112a applies a magnetic field to the entire magnetic layer 43 using a DC magnetic field, thereby demagnetizing the entire magnetic layer 43. This allows the permanent magnet 112a to magnetize the magnetic layer 43 in advance in a second direction opposite to the magnetization direction of the servo pattern 6 (see the white arrow in FIG. 10). By thus setting the two magnetization directions in opposite directions, the reproduced waveform of the servo signal obtained by reading the servo pattern 6 can be made symmetrical in the up-down direction (±). As a method for adjusting the second direction, for example, the rotation angle of the permanent magnet 112a may be set arbitrarily, the entire magnetic layer 43 may be demagnetized, and then the servo pattern 6 may be recorded on the magnetic layer 43, and the rotation angle of the permanent magnet 112a centered on the width direction of the magnetic tape 1 may be adjusted based on the slope of the reproduced waveform.

[0073] The reproducing head unit 114 is disposed downstream of the servo write head 113 and above the magnetic tape 1 (on the magnetic layer 43 side). The reproducing head unit 114 reads the servo pattern 6 from the magnetic layer 43 of the magnetic tape 1, which has been preprocessed by the preprocessing unit 112 and on which the servo pattern 6 has been recorded by the servo write head 113. The reproduced waveform of the servo pattern 6 read by the reproducing head unit 114 is displayed on the screen of the display unit. Typically, the reproducing head unit 114 detects magnetic flux generated from the surface of the servo band s when the magnetic layer 43 passes below the reproducing head unit 114. The magnetic flux detected at this time becomes the reproduced waveform of the servo pattern 6 as a servo signal.

[0074] [Servo pattern] Next, the servo pattern 6 will be described in detail. The servo pattern 6 has a data structure that complies with the "ECMA-319 standard." Fig. 11(A) is a diagram showing the data structure of the LPOS word embedded in the servo pattern 6, and Fig. 11(B) is a diagram explaining the manufacturer word.

[0075] 11(A), a plurality of LPOS (Longitudinal position) words LW arranged consecutively in the longitudinal direction of the tape are embedded in the servo pattern 6. Each LPOS word LW is made up of 36 bits of data including an 8-bit synchronization mark Sy indicating its beginning, an LPOS value Ls consisting of six 4-bit pieces (24 bits in total) indicating a position (address) in the longitudinal direction of the tape, and 4-bit manufacturer data Tx.

[0076] The manufacturer data Tx forms a manufacturer word TW on the magnetic tape 1. As shown in Figure 11(B), the manufacturer word TW has a length of 97 pieces of manufacturer data Tx and is obtained by consecutively reading 97 LPOS words LW. The manufacturer word TW is constructed as follows: Manufacturer word TW:D,A0,A1,A0,A1,···,A0,A1

[0077] The first manufacturer data Tx, "D", is a symbol indicating the beginning of the manufacturer word TW, and contains 4 bits of data (typically "0001") converted using a specified table.

[0078] The second and subsequent 96 pieces of manufacturer data Tx consist of alternating "A0" and "A1" sequences, with two adjacent "A0" and "A1" sequences forming a symbol pair. Each pair of "A0" and "A1" has one of 13 basic symbols (typically 0, 1, 2, 3, 4, 5, 6, 7, 8, 9, A, B, and C) written in it, excluding "D." These 13 basic symbols also consist of 4-bit data converted using the predetermined table. A single symbol (hereinafter also referred to as the LPOS record value) is then identified based on the combination of two specific basic symbols (corresponding to the symbol pair) among the 13 basic symbols.

[0079] The LPOS record value consists of 8 bits of data. The two basic symbols that form a symbol pair may be homogeneous (e.g., 0,0) or heterogeneous (e.g., 0,1).

[0080] The 96 manufacturer data Tx configured as described above typically contain embedded information such as manufacturer information represented by the LPOS recorded value, management information such as the manufacturing date and serial number of the magnetic tape, and servo band identification information for identifying the servo band.

[0081] FIG. 12(A) is a schematic plan view showing an example of the arrangement of the servo pattern 6, and FIG. 12(B) is a diagram showing the reproduced waveform thereof.

[0082] In a timing-based head tracking servo, the servo pattern includes a plurality of azimuthal slope patterns of two or more different shapes. The position of the servo read head 132 is recognized based on the time interval between reading two slope patterns of different shapes and the time interval between reading two slope patterns of the same shape. Based on the position of the servo read head 132 recognized in this way, the position of the drive head 36 in the width direction (Y-axis direction) of the magnetic tape 1 is controlled (see FIGS. 7 and 8).

[0083] As shown in Figure 12(A), the servo pattern 6 forms a servo frame SF having a first servo subframe SSF1 and a second servo subframe SSF2. The servo frames SF are arranged consecutively at predetermined intervals along the longitudinal direction of the tape. Each servo frame SF encodes one bit, either "1" or "0." In other words, one servo frame SF corresponds to one bit.

[0084] The first servo subframe SSF1 is composed of an A burst 6a and a B burst 6b. The A burst 6a is composed of five straight line patterns (corresponding to the first stripe group 61 in FIG. 5) that are inclined in a first direction relative to the longitudinal direction of the tape, and the B burst 6b is composed of five straight line patterns (corresponding to the second stripe group 62 in FIG. 5) that are inclined in a second direction opposite to the first direction relative to the longitudinal direction of the tape.

[0085] On the other hand, the second servo subframe SSF2 is composed of a C burst 6c and a D burst 6d. The C burst 6c is composed of four straight line patterns inclined in the first direction (corresponding to the first stripe group 61 in FIG. 5), and the D burst 6d is composed of four straight line patterns inclined in the second direction (corresponding to the second stripe group 62 in FIG. 5).

[0086] The lengths of the servo frame SF and each of the servo subframes SSF1 and SSF2, and the intervals between the sloped portions that slope each of the bursts 6a to 6d can be set arbitrarily according to the type and specifications of the magnetic tape.

[0087] The reproduced waveform of the servo pattern 6 typically exhibits a burst waveform as shown in Figure 12(B), where signal S6a corresponds to A burst 6a, signal S6b corresponds to B burst 6b, signal S6c corresponds to C burst 6c, and signal S6d corresponds to D burst 6d.

[0088] In a timing-based head tracking servo, a position error signal (PES) is generated by reading servo patterns 6 on two servo bands adjacent to one data band, and the recording / playback head is appropriately positioned relative to the recording track within that data band. Typically, the servo patterns 6 are read from a magnetic tape 1 traveling at a predetermined speed, and the ratio of the distance (time interval) AC between A bursts 6a and C bursts 6c, which are arrays of inclined patterns with the same shape, to the distance (time interval) AB between A bursts 6a and B bursts 6b, which are arrays of inclined patterns with different shapes (or the ratio of the distance CA between C bursts 6c and A bursts 6a to the distance CD between C bursts 6c and D bursts 6d) is calculated, and the drive head 36 is moved in the tape width direction (Y-axis direction) until the calculated value becomes a preset value determined for each recording track (see Figure 8).

[0089] [Data band identification] A different combination of servo band identification information is written to each servo band s (s0 to s4) for each data band. For example, the combination of servo band identification information obtained from two servo bands s2 and s3 adjacent to data band d0 is different from the combination of servo band identification information obtained from servo bands s1 and s2 adjacent to data band d1, the combination of servo band identification information obtained from servo bands s3 and s4 adjacent to data band d2, and the combination of servo band identification information obtained from two servo bands s0 and s1 adjacent to data band d3. In this way, by making the servo band identification information obtained from two servo bands adjacent to one data band different from the servo band identification information obtained from two servo bands adjacent to another data band, it becomes possible to identify each individual data band.

[0090] In this embodiment, two types of servo bands are used to identify the data bands d0 to d4 to be recorded / reproduced. As described above, servo band identification information is embedded in the servo bands. The servo band identification information is multi-bit information, and is embedded in predetermined positions of the second and subsequent 96 pieces of manufacturer data Tx in the manufacturer word TW. The servo band identification information is typically 4 bits, but may be 8 bits (a combination of the symbol pair "A0" and "A1"), or may be a multi-bit information other than 4 bits or 8 bits.

[0091] In this embodiment, the two types of servo bands include a first servo band in which first servo band identification information is recorded and a second servo band in which second servo band identification information is recorded. The first servo band identification information is 4-bit information (e.g., "1001"), and the second servo band identification information is 4-bit information (e.g., "0111") different from the first servo band identification information.

[0092] The combination of the codes "0" and "1" that make up the first and second servo band identification information is identified from the reproduced waveform of the servo pattern 6. In other words, the reproduced waveform of the servo pattern 6 corresponds to a modulated wave of the codes "0" and "1", and the first and second servo band identification information is read out by demodulating the reproduced waveform and combining, for example, four bits. The first and second servo band identification information will be described below with reference to FIGS. 13 and 14.

[0093] 13A and 13B are schematic diagrams showing configuration examples of a servo pattern (hereinafter also referred to as a first servo pattern 601) in which first servo band identification information is embedded and a servo pattern (hereinafter also referred to as a second servo pattern 602) in which second servo band identification information is embedded. As shown in the figures, both the first servo pattern 601 and the second servo pattern 602 are composed of a combination of two types of servo frames SF, including a servo frame SF1 representing one code (e.g., "1") and a servo frame SF0 representing the other code (e.g., "0"). Each servo frame SF1, SF0 has in common the fact that it uses a servo frame SF consisting of a first servo subframe SSF1 and a second servo subframe SSF2 as a constituent unit, but the first servo subframe SSF1 (A burst 6a and B burst 6b) is different from each other.

[0094] As shown in FIG. 13A, in a servo frame SF1 representing the code "1," when the five slope patterns constituting the A burst 6a and the B burst 6b are, from left to right in the figure, the first slope, the second slope, the third slope, the fourth slope, and the fifth slope, the second and fourth slopes are positioned in positions biased toward the first and fifth slopes, respectively. In contrast, as shown in FIG. 13B, in a servo frame SF0 representing the code "0," the arrangement intervals of some of the slope patterns constituting the A burst 6a and the B burst 6b are different from those in the servo frame SF1. In the illustrated example, the five slope patterns constituting the A burst 6a and the B burst 6b are positioned in positions biased toward the third slope. Therefore, for the A burst 6a and the B burst 6b in the servo frame SF0, the distance between the second inclined portion and the third inclined portion, and between the third inclined portion and the fourth inclined portion, is the smallest, and the distance between the first inclined portion and the second inclined portion, and between the fourth inclined portion and the fifth inclined portion is the largest.

[0095] 14A and 14B show the reproduced waveforms SP1 and SP2 of the first servo pattern 601 and the second servo pattern 602, respectively. The reproduced waveforms of each servo frame SF1 and SF0 are composed of burst signals having peaks at positions corresponding to the slopes of each of the burst portions 6a to 6d. As described above, the configuration of the A burst 6a and the B burst 6b of the servo frame SF0 is different from that of the A burst 6a and the B burst 6b of the servo frame SF1. Therefore, the peak positions of the burst signals S6a and S6b are shifted corresponding to the intervals between the different slopes. Therefore, by detecting the location where the peak positions are shifted, as well as the amount and direction of the shift, it is possible to read the information written in the servo frame SF. Here, for example, the servo frame SF1 shown in FIG. 14A represents one bit "1," and the servo frame SF0 shown in FIG. 14B represents another bit "0." By arbitrarily combining, for example, four bits of these two servo frames SF1 and SF0, first and second servo band identification information can be configured.

[0096] 10, the servo pattern recording device 100 has a drive unit 120 that drives the servo write head 113. Fig. 15 is a perspective view that schematically shows the configuration of the servo write head 113, and Fig. 16 is a block diagram showing the configuration of the drive unit 120.

[0097] 15, the servo write head 113 has a plurality of head blocks h0 to h4 for recording servo patterns 6 on each of the servo bands s0 to s4 of the magnetic tape 1. The head blocks h0 to h4 are joined to one another via an adhesive layer hs. Each of the head blocks h0 to h4 forms a recording section disposed corresponding to each of the servo bands s0 to s4 of the magnetic tape 1, and has a magnetic gap g for recording a servo pattern on each of the servo bands.

[0098] The magnetic gap g consists of a pair of straight lines (" / " and "\") that are inclined in opposite directions, with one straight line " / " recording the A burst 6a and C burst 6c, and the other straight line "\" recording the B burst 6b and D burst 6d. The magnetic gaps g of each head block h1 to h5 are arranged so as to be aligned on an axis parallel to the longitudinal direction of the servo write head 113. The head blocks h0 to h4 are magnetically separated from each other and are configured to be able to record different types of servo patterns 6 simultaneously in two or more servo bands.

[0099] 16, the drive unit 120 has a converter 121 that converts servo information into pulse information based on the output from the controller 130 (see FIG. 9), a signal generation unit 122 that generates a pulse signal based on the output of the converter 121, and an amplifier 123 that amplifies the generated pulse signal. A plurality of signal generation units 122 and amplifiers 123 are provided corresponding to each of the head blocks h0 to h4, and are configured to be able to output pulse signals specific to the head blocks h0 to h4 of each servo write head 113.

[0100] The controller 130 includes a memory that stores data relating to the positions of the servo bands where the first servo band identification information should be recorded (s0, s1, s4 in this example) and the positions of the servo bands where the second servo band identification information should be recorded (s2, s3 in this example). The controller 130 controls the drive unit 120 based on the data stored in the memory.

[0101] The converter 121 outputs information corresponding to the servo band identification information to be recorded in each of the servo bands s0 to s4 to the signal generators 122 corresponding to each of the head blocks h0 to h4. In this embodiment, the converter 121 outputs a first pulse signal PS1 for recording a first servo pattern 601 (FIG. 13A) including the first servo band identification information in the head blocks h0, h1, and h4 corresponding to the servo bands s0, s1, and s4, and outputs a second pulse signal PS2 for recording a second servo pattern 602 (FIG. 13B) including the second servo band identification information in the head blocks h2 and h3 corresponding to the servo bands s2 and s3.

[0102] 17(A) and 17(B) show schematic diagrams of the recording signal waveforms of the first servo subframe SSF1 in the first pulse signal PS1 and the second pulse signal PS2, respectively. As shown in the figures, the first and second pulse signals PS1 and PS2 include a first pulse group SPF1 consisting of five pulse groups and a second pulse group SPF2 consisting of four pulse groups. The first pulse group SPF1 is a signal for recording each slope portion of the A burst 6a, and the second pulse group SPF2 is a signal for recording each slope portion of the B burst 6b.

[0103] As shown in the figure, the rise times of the second and fourth pulses in the first pulse group SPF1 are different between the first pulse signal PS1 and the second pulse signal PS2, with the second pulse rising later and the fourth pulse rising earlier in pulse signal PS2 than in pulse signal PS1. This forms a first servo subframe SSF1 in which the arrangement intervals of the slopes of the A bursts 6a are partially different from each other, as shown in Figures 13(A) and 13(B).

[0104] Furthermore, the first pulse signal PS1 and the second pulse signal PS2 are transmitted to the head blocks h0 to h4 in the same phase (at the same timing), so that the first servo pattern 601 (first servo band identification information) is recorded in the servo bands s0, s1, and s4 of each head block h0 to h4, and the second servo pattern 602 (second servo band identification information) is recorded in the same phase in the servo bands s2 and s3 of each head block h0 to h4.

[0105] <Details of this technology> [About fluctuations in tape width] Incidentally, magnetic tape 1 is generally manufactured through processes such as coating a base film (substrate 41) with a magnetic material, calendering, cutting, and recording of servo patterns 6. Because these processes are performed while the base film is being wound with a constant tension, the completed magnetic tape 1 has internal distortion, and the width of the magnetic tape 1 tends to expand over time. Furthermore, the higher the temperature or humidity in the storage environment of the magnetic tape 1, the more likely the tape width will expand. Furthermore, in the magnetic tape 1 wound on the tape reel 13 of the tape cartridge 10, a higher winding pressure is applied to the inner side of the tape reel 13 than to the outer side, so the tape width tends to expand compared to the outer side. In particular, in recent magnetic tapes requiring high capacity, the overall tape thickness is thinned due to thinner base films and coating thicknesses, and the number of windings of magnetic tape around a reel is increasing, so the impact of fluctuations in the width dimension of the magnetic tape is becoming increasingly significant.

[0106] For this reason, when recording or reproducing data using a tape drive device, even if the magnetic tape is run with the same tension as when the servo patterns were recorded, the width of the magnetic tape may increase from the width of the magnetic tape when the servo patterns were recorded. In this case, the spacing between adjacent servo bands changes, which causes fluctuations in the spacing of the servo patterns recorded on these servo bands, making it difficult to achieve the desired tracking control. This problem can become more pronounced as magnetic tape becomes thinner due to the recent trend toward higher recording capacities.

[0107] More specifically, the ECMA-319 standard specifies the spacing between servo bands s (servo band pitch), which is 2858.8 μm±4.6 μm. In an LTO-standard tape drive device 30, a first pitch P1 (see FIG. 7), which is the spacing between two servo read heads 132 in the drive head 36, is typically set to the center value (2858.8 μm) of the standard values ​​for servo band pitch. The first pitch P1 is the distance between the centers of the two servo read heads 132 in the tape width direction.

[0108] On the other hand, the servo write head 113 in the servo pattern recording device 100 has a plurality of magnetic gaps g (see FIG. 15) for recording the servo patterns 6 on each servo band s of the magnetic tape 1. The magnetic gaps g are arranged at a constant second pitch P2, as shown in FIG. 18. The second pitch P2 is the distance between the centers of two adjacent magnetic gaps g in the pattern width Pw in the tape width direction.

[0109] Here, if the second pitch P2 is set to the same value (2858.8 μm) as the first pitch P1, fluctuations in the width dimension of the magnetic tape 1 may cause the tracing position of the servo pattern 6 by the servo read head 132 of the tape drive device 30 to deviate from the center value of the pattern width Pw of the servo pattern 6. As an example, Fig. 19 shows the results of an experiment in which the servo band pitch of a magnetic tape on which a servo pattern has been recorded using a servo write head whose second pitch P2 is the same value as the first pitch P1 is measured using two servo read heads 132 of the tape drive device 30.

[0110] The method for measuring the servo band pitch is to run the magnetic tape 1 using the tape drive device 30, measure the servo trace lines T on each servo band of the two servo read heads 132, and measure the servo band pitch from the relative position of each measured servo trace line T to the servo pattern 6. Here, if the servo band pitch of the magnetic tape 1 is the same as the first pitch P1, and the servo trace line T of one servo read head 132 is positioned at the center of the servo pattern 6 on one servo band, the servo trace line T of the other servo read head 132 will also be positioned at the center of the servo pattern 6 on the other servo band. On the other hand, if the other servo trace line T is deviated from the center position of the other servo pattern 6, the servo band pitch of the magnetic tape 1 will have a value different from the first pitch P1. Here, as shown on the vertical axis of FIG. 19, the difference between the measured values ​​of each servo trace line T is taken, and if the difference is positive, the servo band pitch is narrowed, and if it is negative, the servo band pitch is widened.

[0111] 19, the horizontal axis indicates the length from the outer edge (hereinafter also referred to as BOT) of the magnetic tape 1 wound around the tape reel 13 to the inner edge (hereinafter also referred to as EOT) of the magnetic tape 1 wound around the tape reel 13, which is set to approximately 1000 m here. The vertical axis indicates the servo band pitch determined from the servo signal, which is the playback signal of the servo pattern, and here indicates the deviation from the first pitch P1. Therefore, its center value of "0 μm" means that the difference between each servo trace line T is zero, and corresponds to the first pitch P1 (the same applies to FIGS. 20 and 21 described later). The tension during tape running was 0.55 N both during servo pattern recording and during servo pattern playback. In the figure, TA1 is the measurement value for the magnetic tape in the tape cartridge immediately after production, and TB1 is the measurement value for the magnetic tape in the tape cartridge stored for one week in a thermostatic chamber at 29±2°C and 80±5% RH.

[0112] As shown in Figure 19, the servo band pitch of the magnetic tape TA1 immediately after production was almost constant over its entire length, and the value was slightly wider than the center value. This is thought to be due to the fact that although the tape width decreases slightly due to the tension when the tape runs, the tape width begins to increase as the internal strain of the magnetic tape TA1 is alleviated.

[0113] In contrast, the magnetic tape TB1 stored under the specified conditions showed a large increase in tape width, especially from BOT to EOT. This is thought to be due to the swelling of the magnetic tape in a high-temperature, high-humidity environment and the influence of the tape winding pressure. According to this result, if the track width (Wd) of the recording track 5 of the data band d is 2 μm, the magnetic tape TB will be unable to trace the recording track in a length region of approximately 500 m or more from EOT, meaning that stable recording and playback accuracy will not be achieved.

[0114] To solve this problem, in this embodiment, the pattern pitch (second pitch P2, see FIG. 18) of the servo write head 113 is formed to be narrower than the first pitch P1, which is the spacing between the two servo read heads 132 in the tape drive device 30. That is, while the magnetic tape 1 is run with a predetermined tension, the servo patterns 6 are recorded on the multiple servo bands s at the second pitch P2, which is narrower than the first pitch P1, which is the spacing between the two servo read heads 132 in the tape drive device 30.

[0115] Here, the second pitch P2 was formed to be 0.75 μm narrower than the first pitch P1 (center value of the servo band pitch) (P2=2858.05 μm).The servo band pitch was measured under the same conditions as above, and the experimental results shown in FIG.

[0116] 20, TA2 is a measurement value for the magnetic tape of a tape cartridge immediately after production, and TB2 is a measurement value for the magnetic tape of a tape cartridge stored for one week in a thermostatic chamber at 29±2°C and 80±5% RH. According to this embodiment, the servo band pitch can be kept within the readable range of the tape drive device 30 over the entire length of not only the magnetic tape TA2 immediately after production, but also the magnetic tape TB2 stored under specified conditions. This enables stable tracking control over the entire length of the tape, making it possible to record and reproduce data with the desired high accuracy.

[0117] As shown in FIG. 20 , in a tape cartridge 10 including a magnetic tape 1 manufactured using the servo pattern recording method of this embodiment, the magnetic layer 43 of the magnetic tape 1 has a first region having a servo band pitch narrower than a first pitch P1, which is the spacing between two servo read heads 132, and a second region having a servo band pitch wider than the first pitch P1. The first region is the region on the BOT side, and the second region is the region on the EOT side. The servo band pitch of the magnetic layer 43 tends to gradually widen from the BOT side toward the EOT side. The tape length located at the boundary between the first and second regions is preferably 200 m or more and 400 m or less from the BOT, for example; in the example shown in FIG. 20 , it is approximately 300 m.

[0118] The servo band pitch of the magnetic tape 1 measured by the tape drive device 30 can also vary depending on the magnitude of the tension when recording the servo pattern 6. For example, Fig. 21 shows experimental results illustrating the effect of tension when recording a servo pattern. In the figure, TA3 is the measurement value immediately after production of a magnetic tape in which the running tension when recording a servo pattern is 0.3 N, and TA4 is the measurement value immediately after production of a magnetic tape in which the running tension when recording a servo pattern is 0.6 N. The running tension when reproducing the servo signal by the tape drive device 30 was 0.55 N, as described above.

[0119] 21, the lower the tape tension during servo pattern recording is compared to the tape tension during data recording / reproduction, the narrower the servo band pitch becomes. Conversely, if the tape tension during servo pattern recording is higher than the tape tension during data recording / reproduction, the servo band pitch widens (see the measurement results of TA2 and TA4). This shows that the servo band pitch of the magnetic tape 1 measured by the tape drive device 30 can also be controlled by the tape tension in the servo pattern recording device 100.

[0120] The tape tension in the servo pattern recording device 100 can be set arbitrarily depending on the tape tension in the tape drive device 30, the recording track width Wd of the data band, etc. For example, if the tape tension in the tape drive device 30 is 0.55 N and the recording track width Wd is 2 μm or less, the tape tension in the servo recording device 100 can be set to 0.3 N or more and 0.6 N or less. In other words, the servo band pitch can also be adjusted by adjusting the tape tension when the servo pattern recording device 100 writes the servo patterns 6.

[0121] Furthermore, the pattern pitch (second pitch P2) of the magnetic gap g in the servo write head 113 is not particularly limited as long as it is smaller than the pitch (first pitch P1) of the two servo read heads 132 in the tape drive device 30, and can be adjusted as desired depending on the type of magnetic tape 1 (e.g., the thickness of the substrate 41). For example, the difference between the second pitch P2 and the first pitch is 5 μm or less. More preferably, when the first pitch P1 is 2858.8 μm, the second pitch P2 is 2854.2 μm or more and 2858.7 μm or less.

[0122] [Method for measuring servo band pitch] Next, a method for measuring the servo band pitch will be described.

[0123] (Measurement example 1) The magnetic tape 1 is developed using a magnetic colloidal solution such as Sigma Marker Q, a developer manufactured by Sigma High Chemical Co., Ltd., as a ferricolloid developer, and the servo band pitch is calculated by measuring the distance between the center positions of the developed patterns of the servo patterns 6 recorded on two adjacent servo bands.

[0124] (Measurement example 2) The servo band pitch can be measured using the tape drive device 30. Here, an example will be described in which the drive head 36 tracks the data band d0 sandwiched between the servo band s2 and the servo band s3, as shown in FIG.

[0125] As described above, the method for measuring the servo band pitch using the tape drive device 30 involves running the magnetic tape 1 using the tape drive device 30, measuring the servo trace lines T on each servo band of the two servo read heads 132, and measuring the servo band pitch from the relative position of each measured servo trace line T with respect to the servo pattern 6. The spacing between the servo trace lines T shown by the solid lines in Fig. 22 indicates the servo band pitch when the width of the magnetic tape 1 does not change (first pitch P1, which is the arrangement distance between the two servo read heads 132 of the drive head 36). Also, the spacing between the servo trace lines T shown by the dashed lines in Fig. 22 corresponds to the servo band pitch (P2') when the width of the magnetic tape 1 is expanded.

[0126] FIG. 23 is a diagram illustrating a method for measuring the servo trace line T. The tape drive device 30 outputs a servo reproduction signal having a waveform corresponding to the position of the servo trace line T relative to the servo pattern 6 (see FIG. 19). Typically, the distance AC between the A burst and the C burst, which are arrays of inclined patterns of the same shape, and the distance AB between the A burst and the B burst, which are arrays of inclined patterns of different shapes, are calculated, and the position of the servo trace line T of each servo read head 132 is measured using the following formula (1). Note that θ is the azimuth angle of each of the inclined patterns, which corresponds to the angle α in FIG. 5, and is set to 12° in this example.

[0127]

number

[0128] Here, the distance AC may be the distance AC1 between the first slopes of the A burst and the C burst, the distance AC2 between the second slopes of the A burst and the C burst, the distance AC3 between the third slopes of the A burst and the C burst, or the distance AC4 between the fourth slopes of the C burst. These distances AC (AC1 to AC4) refer to the distances between the positions (upper peak positions) showing the maximum positive amplitude values ​​in the servo reproduction waveform.

[0129] Similarly, the distance AB may be the distance AB1 between the first inclined portions of the A burst and the B burst, the distance AB2 between their second inclined portions, the distance AB3 between their third inclined portions, or the distance AB4 between their fourth inclined portions. Typically, the distance AB1 is used when the distance AC1 is employed, the distance AB2 is used when the distance AC2 is employed, the distance AB3 is used when the distance AC3 is employed, and the distance AB4 is used when the distance AC4 is employed.

[0130] The servo band pitch is then calculated from the difference between the values ​​representing the position of each servo trace line T on the servo pattern, which is calculated from the ratio of distance AB to distance AC, calculated using equation [1]. Here, of the two servo bands being measured, the difference is taken between the measurement value of the servo band on the tape edge side (servo band s3) and the measurement value of the servo band on the tape center side (servo band s2). Whether this value is positive or negative indicates the direction of change in tape width; a positive value corresponds to a narrowing of the servo band pitch, and a negative value corresponds to a widening of the servo band pitch. If the difference is zero, it means that there is no change in tape width.

[0131] The servo band pitch is preferably determined from the difference between many servo frames, and may be the average value of measurements calculated from the difference between 100 to 100,000 servo frames. The tape tension during measurement is 0.55 N, and measurements are performed at a constant tension over the entire length of the magnetic tape 1.

[0132] The method of measuring the servo trace line T is not limited to the above example. For example, the distance CA between the C burst and the A burst and the distance CD between the C burst and the D burst may be calculated, and the position of the servo trace line T may be measured using the following equation (2).

[0133]

number

[0134] Here, the distance CA may be the distance CA1 between the first slopes of the C burst and the A burst, the distance CA2 between their second slopes, the distance CA3 between their third slopes, or the distance CA4 between their fourth slopes. These distances CA (CA1 to CA4) refer to the distances between positions showing the maximum positive amplitudes in the servo reproduction waveform.

[0135] Similarly, the distance CD may be the distance CD1 between the first inclined portions of the C burst and the D burst, the distance CD2 between their second inclined portions, the distance CD3 between their third inclined portions, or the distance CD4 between their fourth inclined portions. Typically, the distance CD1 is adopted when the distance CA1 is adopted, the distance CD2 is adopted when the distance CA2 is adopted, the distance CD3 is adopted when the distance CA3 is adopted, and the distance CD4 is adopted when the distance CA4 is adopted.

[0136] Furthermore, the average value of the measurement value obtained using the formula (1) and the measurement value obtained using the formula (2) may be used as the measurement value of the servo band pitch. Furthermore, the distances AC and AB in equation (1) and the distances CA and CD in equation (2) may be the distance between positions (lower peak positions) showing the maximum negative amplitude in the servo reproduction waveform. Alternatively, the distances AC and AB in equation (1) and the distances CA and CD in equation (2) may be the average values ​​of the distance between the positions (upper peak positions) showing the maximum positive amplitude value in the servo playback waveform and the distance between the positions (lower peak positions) showing the maximum negative amplitude value.

[0137] As shown in FIG. 22, when the servo trace line T is at the position indicated by the dashed line, the distance AB is 38.5 μm and the distance AC is 76 μm in the servo band s2, and the distance AB is 37.5 μm and the distance AC is 76 μm in the servo band s3. In servo band s2, (38.5 / 76)×(76 / 2tan12°)=90.5641[μm] In servo band s3, (37.5 / 76)×(76 / 2tan12°)=88.2118[μm] The difference between these values ​​is 88.2118-90.5641=-2.3523[μm] This becomes: Therefore, the servo band pitch in this case is determined to be a value that is 2.3523 μm wider than the first pitch P1, which is the interval between the servo read heads.

[0138] 22, when the servo trace line T is located at the position indicated by the solid line, the distance AB is 38 μm and the distance AC is 76 μm for both servo band s2 and servo band s3. In this case, the servo band pitch for both servo band s2 and servo band s3 is 89.3880 μm, and the difference therebetween is 0 μm.

[0139] In this embodiment, the servo patterns 6 are recorded on the magnetic tape 1 using a servo write head 113 having magnetic gaps g arranged at a second pitch P2 narrower than the first pitch P1. The magnetic tape 1 manufactured in this manner has at least a portion of an area (first area, see FIG. 20) where the servo pattern pitch, which is the distance between two adjacent servo bands, is narrower than the first pitch P1. Typically, the first area is distributed biased toward the BOT side area as described above.

[0140] The difference between the servo pattern pitch in the first region and the first pitch P1 is, for example, 0.1 μm to 4.6 μm, preferably 0.5 μm to 4.6 μm. The lower limit of this difference, 0.1 μm, means, for example, that the difference is 0.1 μm narrower than the first pitch P1 and the 2858.8 μm center value of the ECMA-319 standard. The upper limit of this difference, 4.6 μm, means, for example, the 2854.2 μm lower limit of the ECMA-319 standard. The lower and upper limits of this difference are dimensions that compensate for future widening of the servo pattern pitch on the tape due to aging. This enables stable tracking control of the drive head 36 over the entire length of the tape, ensuring the desired data recording and reproduction accuracy.

[0141] [Magnetic tape details] Next, the magnetic tape 1 will be described in detail.

[0142] The magnetic tape 1 has a long tape shape and runs longitudinally during recording and playback. The surface of the magnetic layer 43 is the surface on which a magnetic head provided in a recording and playback device (not shown) runs. The magnetic tape 1 is preferably used in a recording and playback device equipped with a ring-type head as a recording head. The magnetic tape 1 is preferably used in a recording and playback device configured to be able to record data with a data track width of 1500 nm or less or 1000 nm or less.

[0143] (base material) As shown in FIG. 2, the substrate 41 is a non-magnetic support that supports the underlayer 42 and the magnetic layer 43. The substrate 41 has the shape of a long film. The upper limit of the average thickness of the substrate 41 is preferably 4.2 μm or less, more preferably 4.0 μm or less, even more preferably 3.8 μm or less, and most preferably 3.4 μm or less. If the upper limit of the average thickness of the substrate 41 is 4.2 μm or less, the recording capacity that can be recorded in one data cartridge can be increased compared to that of general magnetic tape. The lower limit of the average thickness of the substrate 41 is preferably 3 μm or more, more preferably 3.2 μm or more. If the lower limit of the average thickness of the substrate 41 is 3 μm or more, a decrease in the strength of the substrate 41 can be suppressed.

[0144] The average thickness of the substrate 41 is determined as follows. First, a 1 / 2-inch wide magnetic tape 1 is prepared and cut into a length of 250 mm to prepare a sample. Next, the layers of the sample other than the substrate 41 (i.e., the underlayer 42, magnetic layer 43, and back layer 44) are removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Next, using a Mitutoyo Laser Hologram (LGH-110C) as a measuring device, the thickness of the sample (substrate 41) is measured at five or more positions, and the measured values ​​are simply averaged (arithmetic mean) to calculate the average thickness of the substrate 41. Note that the measurement positions are selected randomly from the sample.

[0145] The substrate 41 preferably contains polyester. By including polyester in the substrate 41, the Young's modulus of the substrate 41 in the longitudinal direction can be reduced. Therefore, by adjusting the tension in the longitudinal direction of the magnetic tape 1 during running using a recording / reproducing device, the width of the magnetic tape 1 can be kept constant or approximately constant. The Young's modulus of the substrate 41 in the longitudinal direction is, for example, 5 GPa or more and 10 GPa or less, preferably 2.5 GPa or more and 7.8 GPa or less, and more preferably 3.0 GPa or more and 7.0 GPa or less.

[0146] The polyester may include, for example, at least one of polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polybutylene terephthalate (PBT), polybutylene naphthalate (PBN), polycyclohexylene dimethylene terephthalate (PCT), polyethylene-p-oxybenzoate (PEB), and polyethylene bisphenoxycarboxylate. When the substrate 41 includes two or more polyesters, the two or more polyesters may be mixed, copolymerized, or laminated. At least one of the terminals and side chains of the polyester may be modified.

[0147] The inclusion of polyester in the substrate 41 can be confirmed, for example, as follows. First, similar to the method for measuring the average thickness of the substrate 41, magnetic tape 1 is prepared and cut to a length of 250 mm to prepare a sample, and then the layers of the sample other than the substrate 41 are removed. Next, an IR spectrum of the sample (substrate 41) is obtained by infrared absorption spectrometry (IR). Based on this IR spectrum, it can be confirmed that the substrate 41 contains polyester.

[0148] In addition to polyester, the substrate 41 may contain, for example, at least one of polyamide, polyetheretherketone, polyimide, polyamideimide, and polyetheretherketone (PEEK), or may further contain at least one of polyamide, polyimide, polyamideimide, polyolefins, cellulose derivatives, vinyl resins, and other polymer resins. The polyamide may be an aromatic polyamide (aramid). The polyimide may be an aromatic polyimide. The polyamideimide may be an aromatic polyamideimide.

[0149] When the substrate 41 contains a polymer resin other than polyester, it is preferable that the substrate 41 contains polyester as a main component. Here, the main component means the component with the largest content (mass ratio) among the polymer resins contained in the substrate 41. When the substrate 41 contains a polymer resin other than polyester, the polyester and the polymer resin other than polyester may be mixed or copolymerized.

[0150] The substrate 41 may be biaxially stretched in the longitudinal direction and the width direction. The polymer resin contained in the substrate 41 is preferably oriented in a direction oblique to the width direction of the substrate 41.

[0151] (magnetic layer) The magnetic layer 43 is a recording layer for recording signals using a magnetization pattern. The magnetic layer 43 may be a recording layer for perpendicular recording or a recording layer for longitudinal recording. The magnetic layer 43 contains, for example, magnetic powder, a binder, and a lubricant. If necessary, the magnetic layer 43 may further contain at least one additive selected from the group consisting of an antistatic agent, an abrasive, a hardener, an anticorrosive agent, and non-magnetic reinforcing particles. The magnetic layer 43 is not limited to being formed from a coated film of a magnetic material, but may also be formed from a sputtered film or a vapor-deposited film of a magnetic material.

[0152] The arithmetic mean roughness Ra of the surface of the magnetic layer 43 is 2.0 nm or less, preferably 1.8 nm or less, and more preferably 1.6 nm or less. When the arithmetic mean roughness Ra is 2.0 nm or less, output reduction due to spacing loss can be suppressed, thereby obtaining excellent electromagnetic conversion characteristics. The lower limit of the arithmetic mean roughness Ra of the surface of the magnetic layer 43 is preferably 1.0 nm or more, and more preferably 1.2 nm or more. When the lower limit of the arithmetic mean roughness Ra of the surface of the magnetic layer 43 is 1.0 nm or more, deterioration of running performance due to increased friction can be suppressed.

[0153] The arithmetic mean roughness Ra is calculated as follows. First, the surface of the magnetic layer 43 is observed with an AFM (Atomic Force Microscope) to obtain a 40 μm × 40 μm AFM image. A Digital Instruments Nano Scope IIIa D3100 AFM is used, with a silicon single crystal cantilever (Note 1). Measurements are performed at a tapping frequency of 200 to 400 Hz. Next, the AFM image is divided into 512 × 512 (= 262,144) measurement points, and the height Z(i) (i: measurement point number, i = 1 to 262,144) is measured at each measurement point. The heights Z(i) at each measurement point are simply averaged (arithmetic mean) to calculate the average height (average surface) Zave (= (Z(1) + Z(2) + ... + Z(262,144)) / 262,144). Next, the deviation Z"(i) (= Z(i) - Zave) from the average center line at each measurement point is found, and the arithmetic mean roughness Ra [nm] (= (Z"(1) + Z"(2) + ··· + Z"(262, 144)) / 262, 144) is calculated. In this case, the image is filtered using Flatten order 2 and planefit order 3 XY before being used as data. (Note 1) Nano World SPM probe NCH normal type PointProbe L (Cantilever length) = 125 μm

[0154] The average thickness t of the magnetic layer 43 m The upper limit of the average thickness t of the magnetic layer 43 is 80 nm or less, preferably 70 nm or less, and more preferably 50 nm or less. m If the upper limit is 80 nm or less, when a ring-type head is used as the recording head, the influence of the demagnetizing field can be reduced, and therefore, even better electromagnetic conversion characteristics can be obtained.

[0155] The average thickness t of the magnetic layer 43 m The lower limit of the average thickness t of the magnetic layer 43 is preferably 35 nm or more. mIf the lower limit is 35 nm or more, when an MR type head is used as the reproducing head, output can be ensured, and therefore even better electromagnetic conversion characteristics can be obtained.

[0156] The average thickness t of the magnetic layer 43 m is determined as follows. First, the magnetic tape 1 housed in the cartridge 10 is unwound, and the magnetic tape 1 is cut out at three positions, 10 m, 30 m, and 50 m from one end of the outermost circumference, to prepare three samples. Next, each sample (the magnetic tape 1 to be measured) is processed and sliced ​​using a FIB method or the like. When using the FIB method, a carbon layer and a tungsten layer are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below. The carbon layer is formed by vapor deposition on the surface of the magnetic tape 1 facing the magnetic layer 43 and the surface facing the back layer 44, and the tungsten layer is further formed by vapor deposition or sputtering on the surface facing the magnetic layer 43. The slice is performed along the length (longitudinal direction) of the magnetic tape 1. In other words, the slice results in a cross section parallel to both the longitudinal and thickness directions of the magnetic tape 1.

[0157] The cross section of the obtained sliced ​​sample is observed under a transmission electron microscope (TEM) under the following conditions to obtain a TEM image of each sliced ​​sample. Note that the magnification and acceleration voltage may be adjusted appropriately depending on the type of device. Apparatus: TEM (Hitachi H9000NAR) Accelerating voltage: 300 kV Magnification: 100, 000x

[0158] Next, using the TEM image of each obtained sliced ​​sample, the thickness of the magnetic layer 43 is measured at 10 or more positions on each sliced ​​sample. As described above, since the slices are made along the longitudinal direction of the magnetic tape 1, the 10 measurement positions on each sliced ​​sample are randomly selected from the test piece so that they are different positions in the longitudinal direction of the magnetic tape 1. The measured values ​​of each obtained sliced ​​sample (thickness of the magnetic layer 43 at 30 points in total) are simply averaged (arithmetic average) to obtain an average value, which is the average thickness t of the magnetic layer 43. m Let [nm].

[0159] (magnetic powder) The magnetic powder includes a plurality of magnetic particles. The magnetic particles are, for example, particles containing hexagonal ferrite (hereinafter referred to as "hexagonal ferrite particles"), particles containing epsilon iron oxide (ε-iron oxide) (hereinafter referred to as "ε-iron oxide particles"), or particles containing Co-containing spinel ferrite (hereinafter referred to as "cobalt ferrite particles"). It is preferable that the magnetic powder has a crystal orientation preferentially in the thickness direction (perpendicular direction) of the magnetic tape 1.

[0160] (Hexagonal ferrite particles) Hexagonal ferrite particles have, for example, a plate shape such as a hexagonal plate or a columnar shape such as a hexagonal column (however, the thickness or height is smaller than the major axis of the plate surface or base). In this specification, a hexagonal sloped shape includes an approximately hexagonal sloped shape. Hexagonal ferrite preferably contains at least one of Ba, Sr, Pb, and Ca, more preferably at least one of Ba and Sr. Specifically, the hexagonal ferrite may be, for example, barium ferrite or strontium ferrite. Barium ferrite may further contain at least one of Sr, Pb, and Ca in addition to Ba. Strontium ferrite may further contain at least one of Ba, Pb, and Ca in addition to Sr.

[0161] More specifically, hexagonal ferrites have the general formula MFe 12 O 19The alloy has an average composition represented by the formula: where M is, for example, at least one metal selected from Ba, Sr, Pb, and Ca, preferably at least one metal selected from Ba and Sr. M may be a combination of Ba and one or more metals selected from the group consisting of Sr, Pb, and Ca. M may also be a combination of Sr and one or more metals selected from the group consisting of Ba, Pb, and Ca. In the above general formula, part of Fe may be substituted with another metal element.

[0162] When the magnetic powder contains hexagonal ferrite particles, the average particle size of the magnetic powder is preferably 13 nm to 22 nm, more preferably 13 nm to 19 nm, even more preferably 13 nm to 18 nm, particularly preferably 14 nm to 17 nm, and most preferably 14 nm to 16 nm. When the average particle size of the magnetic powder is 22 nm or less, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained in a high-recording-density magnetic tape 1. On the other hand, when the average particle size of the magnetic powder is 13 nm or more, the dispersibility of the magnetic powder is further improved, and even better electromagnetic conversion characteristics (e.g., SNR) can be obtained.

[0163] When the magnetic powder contains hexagonal ferrite particles, the average aspect ratio of the magnetic powder is preferably 1.0 to 3.0, more preferably 1.5 to 2.8, and even more preferably 1.8 to 2.7. When the average aspect ratio of the magnetic powder is within the range of 1.0 to 3.0, aggregation of the magnetic powder can be suppressed. Furthermore, when the magnetic powder is vertically oriented in the process of forming the magnetic layer 43, the resistance applied to the magnetic powder can be suppressed. Therefore, the vertical orientation of the magnetic powder can be improved.

[0164] When the magnetic powder contains hexagonal ferrite particles, the average particle size and average aspect ratio of the magnetic powder can be determined as follows. First, the magnetic tape 1 to be measured is processed and thinned using a FIB method or the like. When using the FIB method, a carbon layer and a tungsten layer are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below. The carbon layer is formed by vapor deposition on the surface of the magnetic tape 1 facing the magnetic layer 43 and the surface facing the back layer 44, and the tungsten layer is further formed by vapor deposition or sputtering on the surface facing the magnetic layer 43. The thinning is performed along the length (longitudinal direction) of the magnetic tape 1. In other words, the thinning results in a cross section parallel to both the longitudinal and thickness directions of the magnetic tape 1.

[0165] The cross section of the obtained thin sample is observed using a transmission electron microscope (H-9500 manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV and a total magnification of 500,000 times, so as to include the entire magnetic layer 43 in the thickness direction of the magnetic layer 43, and a TEM photograph is taken. The number of TEM photographs prepared is such that 50 particles can be extracted that can measure the plate diameter DB and plate thickness DA (see Figure 24) shown below.

[0166] In this specification, the size of a hexagonal ferrite particle (hereinafter referred to as "particle size") is defined as the plate diameter DB, which is the longest diameter of the plate surface or base, when the particle shape observed in the TEM photograph is plate-like or columnar (however, the thickness or height is smaller than the longest diameter of the plate surface or base), as shown in Figure 24. The thickness or height of the particle observed in the TEM photograph is defined as the plate thickness DA. When the plate surface or base of the particle observed in the TEM photograph is hexagonal, the longest diameter means the longest diagonal distance. When the thickness or height of a particle is not constant within a single particle, the thickness or height of the largest particle is defined as the plate thickness DA.

[0167] Next, 50 particles are selected from the TEM photograph based on the following criteria. Particles with parts outside the field of view of the TEM photograph are not measured, and only particles with a clear outline and that exist independently are measured. If particles overlap, those with a clear boundary between them and whose overall shape can be determined are measured as individual particles, but particles with unclear boundaries and whose overall shape cannot be determined are not measured as their shape cannot be determined.

[0168] The plate thickness DA of each of the selected 50 particles is measured. The plate thicknesses DA thus obtained are simply averaged (arithmetic mean) to obtain the average plate thickness DA ave Average plate thickness DA ave is the average particle plate thickness. Next, the plate diameter DB of each magnetic powder is measured. To measure the particle plate diameter DB, 50 particles whose particle plate diameter DB can be clearly confirmed are selected from the TEM photograph. The plate diameter DB of each of the selected 50 particles is measured. The plate diameters DB thus determined are simply averaged (arithmetic average) to obtain the average plate diameter DB ave Average plate diameter DB ave is the average grain size. And the average plate thickness DA ave and average plate diameter DB ave The average aspect ratio of the particles (DB ave / DA ave ) is found.

[0169] When the magnetic powder includes hexagonal ferrite particles, the average particle volume of the magnetic powder is preferably 500 nm 3 More than 2500nm 3 Less than 500 nm, more preferably 3 More than 1600nm 3 Less than 500 nm, more preferably 3 More than 1500nm 3 Below 600 nm, particularly preferably 3 More than 1200nm 3 Below 600 nm, most preferably 3 More than 1000nm 3 The average particle volume of the magnetic powder is 2500 nm or less. 3When the average particle size of the magnetic powder is 22 nm or less, the same effect as when the average particle volume of the magnetic powder is 500 nm or less can be obtained. 3 If the average particle size of the magnetic powder is 13 nm or more, the same effect as that obtained when the average particle size of the magnetic powder is 13 nm or more can be obtained.

[0170] The average particle volume of the magnetic powder can be calculated as follows: First, as described above in relation to the method for calculating the average particle size of the magnetic powder, the average major axis length DA ave and average plate diameter DB ave Next, calculate the average volume V of the magnetic powder using the following formula:

number

[0171] (ε iron oxide particles) ε-iron oxide particles are hard magnetic particles that can achieve high coercivity even in the form of fine particles. ε-iron oxide particles are spherical or cubic. In this specification, spherical includes nearly spherical. Furthermore, cubic includes nearly cubic. Because ε-iron oxide particles have the above-described shape, when ε-iron oxide particles are used as magnetic particles, the contact area between particles in the thickness direction of the magnetic tape 1 can be reduced and particle aggregation can be suppressed compared to when hexagonal plate-shaped barium ferrite particles are used as magnetic particles. This improves the dispersibility of the magnetic powder and allows for even better electromagnetic conversion characteristics (e.g., SNR).

[0172] The ε-iron oxide particles have a core-shell structure. Specifically, the ε-iron oxide particles have a core and a two-layer shell structure surrounding the core. The two-layer shell structure includes a first shell portion provided on the core and a second shell portion provided on the first shell portion.

[0173] The core portion contains ε-iron oxide. The ε-iron oxide contained in the core portion preferably has ε-Fe2O3 crystals as a main phase, and more preferably is composed of a single phase ε-Fe2O3.

[0174] The first shell portion covers at least a portion of the periphery of the core portion. Specifically, the first shell portion may cover a portion of the periphery of the core portion, or may cover the entire periphery of the core portion. From the viewpoint of ensuring sufficient exchange coupling between the core portion and the first shell portion and improving magnetic properties, it is preferable that the first shell portion covers the entire surface of the core portion.

[0175] The first shell portion is a so-called soft magnetic layer and includes a soft magnetic material such as α-Fe, a Ni-Fe alloy, or an Fe-Si-Al alloy. The α-Fe may be obtained by reducing ε-iron oxide contained in the core portion.

[0176] The second shell portion is an oxide coating serving as an anti-oxidation layer. The second shell portion contains α-iron oxide, aluminum oxide, or silicon oxide. The α-iron oxide includes at least one iron oxide selected from Fe3O4, Fe2O3, and FeO. When the first shell portion contains α-Fe (soft magnetic material), the α-iron oxide may be obtained by oxidizing the α-Fe contained in the first shell portion.

[0177] By having the first shell portion as described above, the coercivity Hc of the core portion alone can be maintained at a high value to ensure thermal stability, while the coercivity Hc of the entire ε-iron oxide particle (core-shell particle) can be adjusted to a coercivity Hc suitable for recording. Furthermore, by having the second shell portion as described above, it is possible to prevent the ε-iron oxide particles from being exposed to air during and before the manufacturing process of the magnetic tape 1, which can cause rust or other damage to the particle surface and lead to a deterioration in the properties of the ε-iron oxide particles. Therefore, deterioration of the properties of the magnetic tape 1 can be prevented.

[0178] The ε-iron oxide particles may have a shell part with a single layer structure. In this case, the shell part has the same structure as the first shell part. However, from the viewpoint of suppressing deterioration of the properties of the ε-iron oxide particles, it is preferable that the ε-iron oxide particles have a shell part with a two-layer structure, as described above.

[0179] The ε-iron oxide particles may contain an additive instead of the core-shell structure, or may have a core-shell structure and contain an additive. In this case, part of the Fe in the ε-iron oxide particles is substituted with the additive. By containing the additive in the ε-iron oxide particles, the coercivity Hc of the entire ε-iron oxide particles can be adjusted to a coercivity Hc suitable for recording, thereby improving ease of recording. The additive is a metal element other than iron, preferably a trivalent metal element, more preferably at least one of Al, Ga, and In, and even more preferably at least one of Al and Ga.

[0180] Specifically, the ε-iron oxide containing additives is ε-Fe 2-x M x O crystal (wherein M is a metal element other than iron, preferably a trivalent metal element, more preferably at least one of Al, Ga, and In, and even more preferably at least one of Al and Ga. x is, for example, 0 <x<1である。)である。

[0181] When the magnetic powder contains ε-iron oxide particles, the average particle size of the magnetic powder is preferably 10 nm to 20 nm, more preferably 10 nm to 18 nm, even more preferably 10 nm to 16 nm, particularly preferably 10 nm to 15 nm, and most preferably 10 nm to 14 nm. In the magnetic tape 1, the actual magnetization region is a region half the size of the recording wavelength. Therefore, by setting the average particle size of the magnetic powder to half the shortest recording wavelength or less, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained. Therefore, when the average particle size of the magnetic powder is 20 nm or less, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained in a high-recording-density magnetic tape 1 (e.g., a magnetic tape 1 configured to record signals at the shortest recording wavelength of 40 nm or less). On the other hand, when the average particle size of the magnetic powder is 10 nm or more, the dispersibility of the magnetic powder is further improved, and even better electromagnetic conversion characteristics (e.g., SNR) can be obtained.

[0182] When the magnetic powder contains ε-iron oxide particles, the average aspect ratio of the magnetic powder is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, even more preferably 1.0 to 2.1, and particularly preferably 1.0 to 1.8. When the average aspect ratio of the magnetic powder is within the range of 1.0 to 3.0, aggregation of the magnetic powder can be suppressed. Furthermore, when the magnetic powder is vertically oriented in the process of forming the magnetic layer 43, the resistance applied to the magnetic powder can be suppressed. Therefore, the vertical orientation of the magnetic powder can be improved.

[0183] When the magnetic powder contains ε-iron oxide particles, the average particle size and average aspect ratio of the magnetic powder can be determined as follows. First, the magnetic tape 1 to be measured is processed and thinned using a method such as FIB (Focused Ion Beam). When using the FIB method, a carbon layer and a tungsten layer are formed as protective layers as a pretreatment for observing the cross-sectional TEM image described below. The carbon layer is formed by vapor deposition on the surface of the magnetic tape 1 facing the magnetic layer 43 and the surface facing the back layer 44, and the tungsten layer is further formed by vapor deposition or sputtering on the surface facing the magnetic layer 43. The thinning is performed along the length (longitudinal direction) of the magnetic tape 1. In other words, the thinning results in a cross section parallel to both the longitudinal and thickness directions of the magnetic tape 1.

[0184] The cross section of the obtained thin sample was observed using a transmission electron microscope (H-9500 manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV and a total magnification of 500,000 times, so as to include the entire magnetic layer 43 in the thickness direction of the magnetic layer 43, and a TEM photograph was taken. Next, 50 particles whose particle shape could be clearly confirmed were selected from the TEM photograph, and the long axis length DL and short axis length DS of each particle were measured. Here, the long axis length DL refers to the longest distance between two parallel lines drawn from all angles so as to be tangent to the outline of each particle (the so-called maximum Feret diameter). Meanwhile, the short axis length DS refers to the longest length of the particle in the direction perpendicular to the long axis (DL) of the particle. Next, the long axis lengths DL of the measured 50 particles were simply averaged (arithmetic mean) to obtain the average long axis length DL. ave The average major axis length DL ave is the average particle size of the magnetic powder. The minor axis lengths DS of the 50 particles measured are simply averaged (arithmetic mean) to obtain the average minor axis length DS ave Then, calculate the average major axis length DL ave and mean minor axis length DS ave The average aspect ratio of the particles (DL ave / DS ave ) is found.

[0185] When the magnetic powder comprises ε iron oxide particles, the average particle volume of the magnetic powder is preferably 500 nm 3 More than 4000nm 3 Less than 500 nm, more preferably 3 More than 3000nm 3 less than or equal to 500 nm, and even more preferably 3 More than 2000nm 3 Below 600 nm, particularly preferably 3 More than 1600nm 3 Below 600 nm, most preferably 3 More than 1300nm 3Generally, the noise of the magnetic tape 1 is inversely proportional to the square root of the number of particles (i.e., proportional to the square root of the particle volume), so by making the particle volume smaller, it is possible to obtain even better electromagnetic conversion characteristics (for example, SNR). Therefore, when the average particle volume of the magnetic powder is 4000 nm 3 When the average particle size of the magnetic powder is 500 nm or less, it is possible to obtain even better electromagnetic conversion characteristics (for example, SNR), similar to when the average particle size of the magnetic powder is 20 nm or less. 3 If the average particle size of the magnetic powder is 10 nm or more, the same effect as that obtained when the average particle size of the magnetic powder is 10 nm or more can be obtained.

[0186] When the ε-iron oxide particles are spherical, the average particle volume of the magnetic powder can be calculated as follows: First, the average major axis length DL is calculated in the same manner as in the above-mentioned method for calculating the average particle size of the magnetic powder. ave Next, calculate the average volume V of the magnetic powder using the following formula: V=(π / 6)×DL ave 3

[0187] When the ε-iron oxide particles have a cubic shape, the average volume of the magnetic powder can be determined as follows. The magnetic tape 1 is processed and thinned by a method such as FIB (Focused Ion Beam). When the FIB method is used, a carbon film and a tungsten thin film are formed as protective films as a pretreatment for observing the cross-sectional TEM image described below. The carbon film is formed by vapor deposition on the surface of the magnetic tape 1 facing the magnetic layer 43 and the surface facing the back layer 44, and the tungsten thin film is further formed by vapor deposition or sputtering on the surface facing the magnetic layer 43. The thinning is performed along the length (longitudinal direction) of the magnetic tape 1. In other words, the thinning forms a cross section parallel to both the longitudinal and thickness directions of the magnetic tape 1.

[0188] The obtained thin film sample is observed using a transmission electron microscope (H-9500 manufactured by Hitachi High-Technologies Corporation) at an acceleration voltage of 200 kV and a total magnification of 500,000 times to observe the cross section of the magnetic layer 43 in the thickness direction of the magnetic layer 43 so as to include the entire magnetic layer 43, and a TEM photograph is obtained. Note that the magnification and acceleration voltage may be adjusted appropriately depending on the type of device. Next, 50 particles whose particle shape is clear are selected from the TEM photograph, and the side length DC of each particle is measured. Next, the side lengths DC of the measured 50 particles are simply averaged (arithmetic mean) to obtain the average side length DC ave Next, calculate the average side length DC ave Using the following formula, the average volume of the magnetic powder V ave (particle volume) is calculated. V ave =DC ave 3

[0189] (cobalt ferrite particles) The cobalt ferrite particles preferably have uniaxial crystal anisotropy. The uniaxial crystal anisotropy of the cobalt ferrite particles allows the magnetic powder to be preferentially crystalline oriented in the thickness direction (perpendicular direction) of the magnetic tape 1. The cobalt ferrite particles have, for example, a cubic shape. In this specification, cubic shape includes a nearly cubic shape. The Co-containing spinel ferrite may further contain at least one of Ni, Mn, Al, Cu, and Zn in addition to Co.

[0190] The Co-containing spinel ferrite has an average composition represented by the following formula, for example. Co x M y FeO Z (In the formula, M is at least one metal selected from the group consisting of Ni, Mn, Al, Cu, and Zn. x is a value within the range of 0.4≦x≦1.0. y is a value within the range of 0≦y≦0.3. However, x and y satisfy the relationship (x+y)≦1.0. z is a value within the range of 3≦z≦4. A portion of Fe may be substituted with another metal element.)

[0191] When the magnetic powder contains cobalt ferrite particles, the average particle size of the magnetic powder is preferably 8 nm to 16 nm, more preferably 8 nm to 13 nm, and even more preferably 8 nm to 10 nm. When the average particle size of the magnetic powder is 16 nm or less, even better electromagnetic conversion characteristics (e.g., SNR) can be obtained in a high-recording-density magnetic tape 1. On the other hand, when the average particle size of the magnetic powder is 8 nm or more, the dispersibility of the magnetic powder is further improved, and even better electromagnetic conversion characteristics (e.g., SNR) can be obtained. The method for calculating the average particle size of the magnetic powder is the same as the method for calculating the average particle size of the magnetic powder when the magnetic powder contains ε-iron oxide particles.

[0192] When the magnetic powder contains cobalt ferrite particles, the average aspect ratio of the magnetic powder is preferably 1.0 to 3.0, more preferably 1.0 to 2.5, even more preferably 1.0 to 2.1, and particularly preferably 1.0 to 1.8. When the average aspect ratio of the magnetic powder is within the range of 1.0 to 3.0, aggregation of the magnetic powder can be suppressed. Furthermore, when the magnetic powder is vertically oriented in the process of forming the magnetic layer 43, the resistance applied to the magnetic powder can be suppressed. Therefore, the vertical orientation of the magnetic powder can be improved. The method for calculating the average aspect ratio of the magnetic powder is the same as the method for calculating the average aspect ratio of the magnetic powder when the magnetic powder contains ε-iron oxide particles.

[0193] When the magnetic powder includes cobalt ferrite particles, the average particle volume of the magnetic powder is preferably 500 nm 3 More than 4000nm 3 Less than 600 nm, more preferably 3 More than 2000nm 3 or less, even more preferably 600 nm 3 More than 1000nm 3 The average particle volume of the magnetic powder is 4000 nm or less. 3 If the average particle size of the magnetic powder is 16 nm or less, the same effect as when the average particle volume of the magnetic powder is 500 nm or less can be obtained. 3This produces the same effect as when the average particle size of the magnetic powder is 8 nm or more. The method for calculating the average particle volume of the magnetic component is the same as the method for calculating the average particle volume when the ε-iron oxide particles have a cubic shape.

[0194] (binder) Examples of binders include thermoplastic resins, thermosetting resins, reactive resins, etc. Examples of thermoplastic resins include vinyl chloride, vinyl acetate, vinyl chloride-vinyl acetate copolymers, vinyl chloride-vinylidene chloride copolymers, vinyl chloride-acrylonitrile copolymers, acrylic acid ester-acrylonitrile copolymers, acrylic acid ester-vinyl chloride-vinylidene chloride copolymers, acrylic acid ester-acrylonitrile copolymers, acrylic acid ester-vinylidene chloride copolymers, methacrylic acid ester-vinylidene chloride copolymers, methacrylic acid ester-vinyl chloride copolymers, methacrylic acid ester-ethylene copolymers, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymers, acrylonitrile-butadiene copolymers, polyamide resins, polyvinyl butyral, cellulose derivatives (cellulose acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene-butadiene copolymers, polyurethane resins, polyester resins, amino resins, and synthetic rubbers.

[0195] Examples of thermosetting resins include phenolic resins, epoxy resins, polyurethane curing resins, urea resins, melamine resins, alkyd resins, silicone resins, polyamine resins, and urea formaldehyde resins.

[0196] All of the above binders may contain -SO3M, -OSO3M, -COOM, P=O(OM)2 (where M represents a hydrogen atom or an alkali metal such as lithium, potassium, or sodium), -NR1R2, -NR1R2R3, etc., in order to improve the dispersibility of the magnetic powder. + X - A side chain amine having a terminal group represented by the formula: >NR1R2 + X -(wherein R1, R2, and R3 represent a hydrogen atom or a hydrocarbon group, and X - represents a halogen element ion such as fluorine, chlorine, bromine, or iodine, or an inorganic ion or an organic ion.) Furthermore, polar functional groups such as -OH, -SH, -CN, and epoxy groups may be introduced. The amount of these polar functional groups introduced into the binder is 10 -1 ~10 -8 mol / g, preferably 10 -2 ~10 -6 More preferably, it is expressed in moles / g.

[0197] (lubricant) The lubricant contains, for example, at least one selected from a fatty acid and a fatty acid ester, preferably both a fatty acid and a fatty acid ester. The inclusion of a lubricant in magnetic layer 43, particularly the inclusion of both a fatty acid and a fatty acid ester in magnetic layer 43, contributes to improving the running stability of magnetic tape 1. More particularly, the inclusion of a lubricant in magnetic layer 43 and the presence of pores achieves good running stability. This improvement in running stability is thought to be due to the lubricant adjusting the dynamic friction coefficient of the surface of magnetic tape 1 facing magnetic layer 43 to a value suitable for running magnetic tape 1.

[0198] The fatty acid may preferably be a compound represented by the following general formula (1) or (2). For example, the fatty acid may contain either or both of the compound represented by the following general formula (1) and the compound represented by the general formula (2).

[0199] The fatty acid ester may preferably be a compound represented by the following general formula (3) or (4). For example, the fatty acid ester may contain either or both of the compound represented by the following general formula (3) and the compound represented by the general formula (4).

[0200] By including in the lubricant one or both of the compounds shown in general formula (1) and the compounds shown in general formula (2), and one or both of the compounds shown in general formula (3) and the compounds shown in general formula (4), it is possible to suppress an increase in the dynamic friction coefficient of the magnetic tape 1 due to repeated recording or playback.

[0201] CH3(CH2) k COOH (1) (However, in general formula (1), k is an integer selected from the range of 14 or more and 22 or less, more preferably from the range of 14 or more and 18 or less.)

[0202] CH3(CH2) n CH=CH(CH2) m COOH (2) (However, in general formula (2), the sum of n and m is an integer selected from the range of 12 to 20, more preferably from the range of 14 to 18.)

[0203] CH3(CH2) p COO(CH2) q CH3···(3) (However, in general formula (3), p is an integer selected from the range of 14 or more and 22 or less, more preferably 14 or more and 18 or less, and q is an integer selected from the range of 2 or more and 5 or less, more preferably 2 or more and 4 or less.)

[0204] CH3(CH2) r COO-(CH2) s CH(CH3)2 (4) (In the general formula (4), r is an integer selected from the range of 14 to 22, and s is an integer selected from the range of 1 to 3.)

[0205] (antistatic agent) Examples of antistatic agents include carbon black, natural surfactants, nonionic surfactants, and cationic surfactants.

[0206] (abrasive) Examples of abrasives include acicular α-iron oxide obtained by dehydrating and annealing raw materials such as α-alumina with an α-conversion rate of 90% or more, β-alumina, γ-alumina, silicon carbide, chromium oxide, cerium oxide, α-iron oxide, corundum, silicon nitride, titanium carbide, titanium oxide, silicon dioxide, tin oxide, magnesium oxide, tungsten oxide, zirconium oxide, boron nitride, zinc oxide, calcium carbonate, calcium sulfate, barium sulfate, molybdenum disulfide, and magnetic iron oxide, and, if necessary, surface-treated with aluminum and / or silica.

[0207] (hardening agent) Examples of the curing agent include polyisocyanates. Examples of polyisocyanates include aromatic polyisocyanates such as an adduct of tolylene diisocyanate (TDI) and an active hydrogen compound, and aliphatic polyisocyanates such as an adduct of hexamethylene diisocyanate (HMDI) and an active hydrogen compound. The weight-average molecular weight of these polyisocyanates is preferably in the range of 100 to 3,000.

[0208] (rust inhibitor) Examples of the rust inhibitor include phenols, naphthols, quinones, heterocyclic compounds containing a nitrogen atom, heterocyclic compounds containing an oxygen atom, and heterocyclic compounds containing a sulfur atom.

[0209] (non-magnetic reinforcing particles) Examples of non-magnetic reinforcing particles include aluminum oxide (α, β or γ alumina), chromium oxide, silicon oxide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, and titanium oxide (rutile or anatase titanium oxide).

[0210] (base layer) The underlayer 42 serves to reduce the unevenness of the surface of the substrate 41 and adjust the unevenness of the surface of the magnetic layer 43. The underlayer 42 is a non-magnetic layer containing non-magnetic powder, a binder, and a lubricant. The underlayer 42 supplies the lubricant to the surface of the magnetic layer 43. If necessary, the underlayer 42 may further contain at least one additive selected from the group consisting of an antistatic agent, a hardener, and an anti-rust agent.

[0211] The average thickness t2 of the underlayer 42 is preferably 0.3 μm or more and 1.2 μm or less, more preferably 0.3 μm or more and 0.9 μm or less, or 0.3 μm or more and 0.6 μm or less. The average thickness t2 of the underlayer 42 is determined in the same manner as the average thickness t1 of the magnetic layer 43. However, the magnification of the TEM image is adjusted appropriately depending on the thickness of the underlayer 42. When the average thickness t2 of the underlayer 42 is 1.2 μm or less, the elasticity of the magnetic tape 1 due to external forces is further increased, making it even easier to adjust the width of the magnetic tape 1 by adjusting the tension.

[0212] (Non-magnetic powder) The non-magnetic powder includes, for example, at least one of inorganic particle powder and organic particle powder. The non-magnetic powder may also include carbon powder such as carbon black. One type of non-magnetic powder may be used alone, or two or more types of non-magnetic powder may be used in combination. The inorganic particles include, for example, metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, or metal sulfides. The shape of the non-magnetic powder may be, for example, acicular, spherical, cubic, plate-like, or other various shapes, but is not limited to these shapes.

[0213] (binder, lubricant) The binder and lubricant are the same as those used in the magnetic layer 43 described above.

[0214] (additives) The antistatic agent, hardener, and anticorrosive agent are the same as those in the magnetic layer 43 described above.

[0215] (Back layer) The back layer 44 contains a binder and a non-magnetic powder. If necessary, the back layer 44 may further contain at least one additive selected from the group consisting of a lubricant, a hardener, and an antistatic agent. The binder and non-magnetic powder are the same as those in the underlayer 42 described above.

[0216] The average particle size of the non-magnetic powder is preferably 10 nm or more and 150 nm or less, more preferably 15 nm or more and 110 nm or less. The average particle size of the non-magnetic powder is determined in the same manner as the average particle size of the magnetic powder. The non-magnetic powder may contain non-magnetic powder having two or more particle size distributions.

[0217] The upper limit of the average thickness of the back layer 44 is preferably 0.6 μm or less. If the upper limit of the average thickness of the back layer 44 is 0.6 μm or less, the thickness of the underlayer 42 and the substrate 41 can be kept thick even when the average thickness of the magnetic tape 1 is 5.6 μm or less, thereby maintaining running stability of the magnetic tape 1 within a recording / reproducing device. The lower limit of the average thickness of the back layer 44 is not particularly limited, but is, for example, 0.2 μm or more.

[0218] The average thickness t of the back layer 44 b is calculated as follows: First, the average thickness t of the magnetic tape 1 T Measure the average thickness t T The measurement method for is as described in "Average Thickness of Magnetic Tape" below. Next, the back layer 44 of the sample is removed with a solvent such as MEK (methyl ethyl ketone) or dilute hydrochloric acid. Next, the thickness of the sample is measured at five or more points using a Mitutoyo Laser Hologram (LGH-110C), and these measurements are simply averaged (arithmetic mean) to obtain the average thickness t B Then, the average thickness t of the back layer 44 is calculated using the following formula: b The measurement position is selected randomly from the sample. t b [μm]=t T [μm]-t B [μm]

[0219] The back layer 44 has a surface on which numerous protrusions are provided. The numerous protrusions are intended to form numerous pores in the surface of the magnetic layer 43 when the magnetic tape 1 is wound into a roll. The numerous pores are made up of, for example, numerous non-magnetic particles protruding from the surface of the back layer 44.

[0220] (average thickness of magnetic tape) Average thickness of magnetic tape 1 (average total thickness) t T The upper limit of the average thickness t of the magnetic tape 1 is 5.6 μm or less, preferably 5.0 μm or less, more preferably 4.6 μm or less, and even more preferably 4.4 μm or less. T If the average thickness t of the magnetic tape 1 is 5.6 μm or less, the recording capacity that can be recorded in one data cartridge can be increased compared to that of a general magnetic tape. T The lower limit is not particularly limited, but is, for example, 3.5 μm or more.

[0221] Average thickness t of magnetic tape 1 T is calculated as follows. First, a 1 / 2-inch wide magnetic tape 1 is prepared and cut into a length of 250 mm to prepare a sample. Next, a Mitutoyo Laser Hologram (LGH-110C) is used as a measuring device to measure the thickness of the sample at five or more points, and these measurements are simply averaged (arithmetic mean) to obtain the average value t T The measurement position is selected randomly from the sample.

[0222] (Coercive force Hc) The upper limit of the coercive force Hc2 of the magnetic layer 43 in the longitudinal direction of the magnetic tape 1 is preferably 2000 Oe or less, more preferably 1900 Oe or less, and even more preferably 1800 Oe or less. If the coercive force Hc2 of the magnetic layer 43 in the longitudinal direction is 2000 Oe or less, sufficient electromagnetic conversion characteristics can be obtained even at high recording densities.

[0223] The lower limit of the coercive force Hc2 of the magnetic layer 43 measured in the longitudinal direction of the magnetic tape 1 is preferably 1000 Oe or more. When the coercive force Hc2 of the magnetic layer 43 measured in the longitudinal direction is 1000 Oe or more, demagnetization due to leakage flux from the recording head can be suppressed.

[0224] The coercive force Hc2 is determined as follows. First, the magnetic tape 1 contained in the cartridge is unwound, and the magnetic tape 1 is cut out at a position 30 m from one end of the outermost circumference. Three pieces of the magnetic tape 1 are stacked with double-sided tape so that the longitudinal direction of the magnetic tape 1 is the same, and then punched out with a φ6.39 mm punch to prepare a measurement sample. At this time, marking is performed with any non-magnetic ink so that the longitudinal direction (running direction) of the magnetic tape 1 can be identified. Then, the MH loop of the measurement sample (the entire magnetic tape 1) corresponding to the longitudinal direction (running direction) of the magnetic tape 1 is measured using a vibrating sample magnetometer (VSM). Next, the coating film (underlayer 42, magnetic layer 43, back layer 44, etc.) of the magnetic tape 1 cut out above is wiped off with acetone, ethanol, etc., leaving only the substrate 41. Three of the obtained substrates 41 are then stacked together with double-sided tape and punched out with a φ6.39 mm punch to prepare a sample for background correction (hereinafter simply referred to as the "correction sample"). Thereafter, the MH loop of the correction sample (substrate 41) corresponding to the perpendicular direction of the substrate 41 (the perpendicular direction of the magnetic tape 1) is measured using a VSM.

[0225] The MH loop of the measurement sample (entire magnetic tape 1) and the MH loop of the correction sample (substrate 41) are measured using a high-sensitivity vibration sample magnetometer "VSM-P7-15" manufactured by Toei Kogyo Co., Ltd. The measurement conditions are as follows: measurement mode: full loop, maximum magnetic field: 15 kOe, magnetic field step: 40 bits, time constant of locking amp: 0.3 sec, waiting time: 1 sec, number of MH averages: 20.

[0226] After obtaining the MH loop of the measurement sample (entire magnetic tape 1) and the MH loop of the correction sample (substrate 41), background correction is performed by subtracting the MH loop of the correction sample (substrate 41) from the MH loop of the measurement sample (entire magnetic tape 1), resulting in the MH loop after background correction. This background correction calculation is performed using the measurement and analysis program included with the VSM-P7-15. The coercive force Hc2 is calculated from the obtained MH loop after background correction. Note that this calculation is performed using the measurement and analysis program included with the VSM-P7-15. Note that all of the above MH loop measurements are performed at 25°C ± 2°C and 50% RH ± 5% RH. Furthermore, no "demagnetizing field correction" is performed when measuring the MH loop in the longitudinal direction of the magnetic tape 1.

[0227] (Square ratio) The squareness ratio S1 of the magnetic layer 43 in the perpendicular direction (thickness direction) of the magnetic tape 1 is preferably 65% ​​or more, more preferably 70% or more, even more preferably 75% or more, particularly preferably 80% or more, and most preferably 85% or more. When the squareness ratio S1 is 65% or more, the perpendicular orientation of the magnetic powder is sufficiently high, thereby achieving even better electromagnetic conversion characteristics (e.g., SNR).

[0228] The squareness ratio S1 in the vertical direction is determined as follows. First, the magnetic tape 1 housed in the cartridge is unwound, and the magnetic tape 1 is cut out at a position 30 m from one end of the outermost circumference. Three pieces of the magnetic tape 1 are stacked with double-sided tape so that the longitudinal direction of the magnetic tape 1 is the same, and then punched out with a φ6.39 mm punch to prepare a measurement sample. At this time, markings are made with any nonmagnetic ink so that the longitudinal direction (running direction) of the magnetic tape 1 can be identified. Then, the MH loop of the measurement sample (the entire magnetic tape 1) corresponding to the longitudinal direction (running direction) of the magnetic tape 1 is measured using a vibrating sample magnetometer (VSM). Next, the coating film (underlayer 42, magnetic layer 43, back layer 44, etc.) of the magnetic tape 1 cut out above is wiped off with acetone, ethanol, etc., leaving only the substrate 41. Three of the obtained substrates 41 are then stacked together with double-sided tape and punched out with a φ6.39 mm punch to prepare a sample for background correction (hereinafter simply referred to as the "correction sample"). Thereafter, the MH loop of the correction sample (substrate 41) corresponding to the perpendicular direction of the substrate 41 (the perpendicular direction of the magnetic tape 1) is measured using a VSM.

[0229] The MH loop of the measurement sample (entire magnetic tape 1) and the MH loop of the correction sample (substrate 41) are measured using a high-sensitivity vibration sample magnetometer "VSM-P7-15" manufactured by Toei Kogyo Co., Ltd. The measurement conditions are as follows: measurement mode: full loop, maximum magnetic field: 15 kOe, magnetic field step: 40 bits, time constant of locking amp: 0.3 sec, waiting time: 1 sec, number of MH averages: 20.

[0230] After obtaining the MH loop of the measurement sample (entire magnetic tape 1) and the MH loop of the correction sample (substrate 41), background correction is performed by subtracting the MH loop of the correction sample (substrate 41) from the MH loop of the measurement sample (entire magnetic tape 1), and the MH loop after background correction is obtained. This background correction calculation is performed using the measurement and analysis program included with the "VSM-P7-15 model."

[0231] The saturation magnetization Ms (emu) and residual magnetization Mr (emu) of the MH loop after background correction are substituted into the following formula to calculate the squareness ratio S1 (%). Note that all of the above MH loop measurements are performed at 25°C ± 2°C and 50% RH ± 5% RH. Also, no "demagnetizing field correction" is performed when measuring the MH loop in the perpendicular direction to the magnetic tape 1. Note that this calculation uses the measurement and analysis program attached to the "VSM-P7-15 model." do. Squareness ratio S1(%)=(Mr / Ms)×100

[0232] The squareness ratio S2 of the magnetic layer 43 in the longitudinal direction (running direction) of the magnetic tape 1 is preferably 35% or less, more preferably 30% or less, even more preferably 25% or less, particularly preferably 20% or less, and most preferably 15% or less. When the squareness ratio S2 is 35% or less, the magnetic powder has a sufficiently high perpendicular orientation, resulting in even better electromagnetic conversion characteristics (e.g., SNR).

[0233] The squareness ratio S2 in the longitudinal direction is determined in the same manner as the squareness ratio S1, except that the MH loop is measured in the longitudinal direction (running direction) of the magnetic tape 1 and the substrate 41.

[0234] (Back surface roughness Rb) Surface roughness of the back surface (surface roughness of the back layer 44) R b But R b The surface roughness R of the back surface is preferably ≦6.0 [nm]. bWhen the content of the magnetic layer is within the above range, even better electromagnetic conversion characteristics can be obtained.

[0235] [Variations] In the above embodiment, the azimuth angle tilt (azimuth angle) of the servo frame SF constituting the servo pattern 6 is set to 12°, but is not limited to this and can be set to, for example, 11° to 36°, preferably 11° to 26°. Also, while the above azimuth angle tilts are of two types, " / " and "\", the servo pattern may further include azimuth angle tilts with different tilt angles.

[0236] Furthermore, in the above embodiment, a magnetic tape conforming to the LTO standard has been used as an example of a tape-type magnetic recording medium, but the present invention is equally applicable to magnetic tapes conforming to other standards.

[0237] The present technology can also be configured as follows. (1) A method for recording servo patterns on a plurality of servo bands arranged at intervals in the width direction of a magnetic layer of a magnetic tape, comprising: The magnetic tape is run at a predetermined tension, Servo patterns are recorded on the plurality of servo bands at a second pitch that is narrower than a first pitch that is an arrangement interval between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer. Servo pattern recording method. (2) The servo pattern recording method according to (1), The difference between the first pitch and the second pitch is 5 μm or less. Servo pattern recording method. (3) The servo pattern recording method according to (2), The second pitch is equal to or greater than 2854.2 μm and equal to or less than 2858.7 μm. Servo pattern recording method. (4) The servo pattern recording method according to any one of (1) to (3) above, The predetermined tension is equal to or greater than 0.3 N and equal to or less than 0.6 N. Servo pattern recording method. (5) An apparatus for recording servo patterns on a plurality of servo bands arranged at intervals in the width direction of a magnetic layer of a magnetic tape, comprising: a servo write head having a plurality of recording sections arranged corresponding to the plurality of servo bands; The plurality of recording units each have a magnetic gap for recording a servo pattern on the plurality of servo bands at a second pitch that is narrower than a first pitch that is an arrangement interval between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer. Servo pattern recording device. (6) The servo pattern recording device according to (5), The difference between the first pitch and the second pitch is 5 μm or less. Servo pattern recording device. (7) The servo pattern recording device according to (6), The second pitch is equal to or greater than 2854.2 μm and equal to or less than 2858.7 μm. Servo pattern recording device. (8) A method for manufacturing a magnetic tape having a magnetic layer with a plurality of servo bands arranged at intervals in the width direction, comprising the steps of: The magnetic tape is run at a predetermined tension, Servo patterns are recorded on the plurality of servo bands at a second pitch that is narrower than a first pitch that is an arrangement interval between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer. How magnetic tape is manufactured. (9) A method for producing the magnetic tape according to (8) above, The difference between the first pitch and the second pitch is 5 μm or less. How magnetic tape is manufactured. (10) A method for producing a magnetic tape according to (8) or (9), The second pitch is equal to or greater than 2854.2 μm and equal to or less than 2858.7 μm. How magnetic tape is manufactured. (11) A magnetic layer having a plurality of servo bands arranged at intervals in the width direction, The magnetic layer has at least a portion of an area in which a servo band pitch, which is the distance between two adjacent servo bands, is narrower than the spacing between two servo read heads in a tape drive device that records information on the magnetic layer or reproduces information recorded on the magnetic layer. Magnetic tape. (12) The magnetic tape according to (11) above, The difference between the servo band pitch in the area and the arrangement interval between the two servo read heads is 0.1 μm or more and 4.6 μm or less. Magnetic tape. (13) The magnetic tape according to (12) above, The difference between the servo band pitch in the area and the arrangement interval between the two servo read heads is 0.5 μm or more and 4.6 μm or less. Magnetic tape. (14) a cartridge case; a tape reel rotatably accommodated inside the cartridge case; a magnetic tape wound around the tape reel; Equipped with the magnetic tape has a magnetic layer on which a plurality of servo patterns are recorded at intervals in the tape width direction, The magnetic layer is a first region in which a servo band pitch, which is a distance between two adjacent servo bands, is narrower than the spacing between two servo read heads in a tape drive device that records information on the magnetic layer or reproduces information recorded on the magnetic layer; a second region in which the servo band pitch is wider than the spacing between the two servo read heads; Tape cartridge. (15) The tape cartridge according to (14) above, the first region is a region on a first end side of the outer periphery of the magnetic tape wound around the tape reel, The second region is a region of a second end portion on the inner circumferential side of the magnetic tape wound around the tape reel. Tape cartridge. (16) The tape cartridge according to (15) above, The servo band pitch of the magnetic layer gradually widens from the first end side toward the second end side of the magnetic tape. Tape cartridge. [Explanation of symbols]

[0238] 1...Magnetic tape 6...Servo pattern 10...Tape cartridge 11...Cartridge case 13...Tape reel 30...Tape drive device 36...Drive head 43...Magnetic layer 100...Servo pattern recording device 113...Servo light head 132...Servo read head 601,602...Servo pattern

Claims

1. A method for recording servo patterns on a plurality of servo bands arranged at intervals in the width direction of a magnetic layer of a magnetic tape, comprising: While the magnetic tape is running at a constant tension, Servo patterns are recorded on the plurality of servo bands at a second pitch that is narrower than a first pitch that is an arrangement interval between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer. Servo pattern recording method.

2. 2. The servo pattern recording method according to claim 1, The difference between the first pitch and the second pitch is 5 μm or less. Servo pattern recording method.

3. 3. The servo pattern recording method according to claim 2, The second pitch is equal to or greater than 2854.2 μm and equal to or less than 2858.7 μm. Servo pattern recording method.

4. 2. The servo pattern recording method according to claim 1, The constant tension is equal to or greater than 0.3 N and equal to or less than 0.6 N. Servo pattern recording method.

5. 1. An apparatus for recording servo patterns on a plurality of servo bands arranged at intervals in a width direction of a magnetic layer of a magnetic tape while running the magnetic tape under a constant tension, comprising: a servo write head having a plurality of recording sections arranged corresponding to the plurality of servo bands; The plurality of recording sections each have a magnetic gap for recording a servo pattern on the plurality of servo bands at a second pitch that is narrower than a first pitch that is an arrangement interval between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer. Servo pattern recording device.

6. 6. The servo pattern recording device according to claim 5, The difference between the first pitch and the second pitch is 5 μm or less. Servo pattern recording device.

7. 7. The servo pattern recording device according to claim 6, The second pitch is equal to or greater than 2854.2 μm and equal to or less than 2858.7 μm. Servo pattern recording device.

8. 1. A method for manufacturing a magnetic tape having a magnetic layer with a plurality of servo bands arranged at intervals in the width direction, comprising: While the magnetic tape is running at a constant tension, Servo patterns are recorded on the plurality of servo bands at a second pitch that is narrower than a first pitch that is an arrangement interval between two servo read heads in a tape drive device that records data on the magnetic layer or reproduces data recorded on the magnetic layer. How magnetic tape is manufactured.

9. 9. A method for manufacturing a magnetic tape according to claim 8, comprising: The difference between the first pitch and the second pitch is 5 μm or less. How magnetic tape is manufactured.

10. 9. A method for producing a magnetic tape according to claim 8, comprising the steps of: The second pitch is equal to or greater than 2854.2 μm and equal to or less than 2858.7 μm. How magnetic tape is manufactured.

11. A magnetic tape wound on a tape reel, The magnetic recording medium has a first end portion on the outer circumferential side, a second end portion on the inner circumferential side, and a magnetic layer having a plurality of servo bands arranged at intervals in the width direction, the magnetic layer has, in at least a portion thereof, an area in which a servo band pitch, which is a distance between two adjacent servo bands, is narrower than an arrangement interval between two servo read heads in a tape drive device that records information on the magnetic layer or reproduces information recorded on the magnetic layer; The servo band pitch gradually widens from the first end side toward the second end side. Magnetic tape.

12. 12. The magnetic tape of claim 11, The difference between the servo band pitch in the area and the arrangement interval between the two servo read heads is 0.1 μm or more and 4.6 μm or less. Magnetic tape.

13. 13. The magnetic tape of claim 12, The difference between the servo band pitch in the area and the arrangement interval between the two servo read heads is 0.5 μm or more and 4.6 μm or less. Magnetic tape.

14. A cartridge case, a tape reel rotatably accommodated inside the cartridge case; a magnetic tape wound around the tape reel; Equipped with the magnetic tape has a magnetic layer on which a plurality of servo patterns are recorded at intervals in the tape width direction, The magnetic layer is a first region in which a servo band pitch, which is a distance between two adjacent servo bands, is narrower than the spacing between two servo read heads in a tape drive device that records information on the magnetic layer or reproduces information recorded on the magnetic layer; a second region in which the servo band pitch is wider than the spacing between the two servo read heads; the first region is a region on a first end side of the outer periphery of the magnetic tape wound around the tape reel, the second region is a region on a second end side of an inner periphery of the magnetic tape wound around the tape reel, The servo band pitch gradually widens from the first end side toward the second end side. Tape cartridge.

15. 15. The tape cartridge of claim 14, The difference between the servo band pitch in the area and the arrangement interval between the two servo read heads is 0.1 μm or more and 4.6 μm or less. Tape cartridge.

16. 16. The tape cartridge of claim 15, The difference between the servo band pitch in the area and the arrangement interval between the two servo read heads is 0.5 μm or more and 4.6 μm or less. Tape cartridge.

Images