JP7439702B2 - cartridge - Google Patents

Description

The present technology relates to a technology for a cartridge or the like that houses a magnetic tape therein.

In recent years, magnetic tapes have become widely used for purposes such as backing up electronic data. Magnetic tape is attracting more and more attention as a storage medium for big data and the like because it has a large capacity and can be stored for a long time.

A magnetic tape is provided with a data band including a plurality of recording tracks, and data is recorded on the recording tracks. Further, a servo band is provided at a position sandwiching the data band in the width direction, and a servo signal is recorded on this servo band. The magnetic head performs positioning with respect to the recording track by reading servo signals recorded on the servo band.

For example, Patent Document 1 discloses a linear tape drive device that detects the tape width from a servo signal, obtains a tape tension control signal from the tape width detection signal, and controls the tape tension using a tape tension control mechanism.

Japanese Patent Application Publication No. 2005-285268

In recent years, due to the demand for increased capacity of magnetic tapes, the overall thickness of magnetic tapes has become thinner, the number of recording tracks has increased, and the width of each recording track has become narrower. Therefore, if the width of the magnetic tape changes even slightly due to aging, environmental changes, etc. after data is stored on the magnetic tape, off-track of the data write/read head on the magnetic tape will occur. , there is a possibility that data recording/reproduction cannot be performed accurately.
Furthermore, in data centers where magnetic tape is used, the tape is stored for a long period of time after being recorded, and recording and playback are performed using multiple drives.

In view of the above circumstances, the purpose of this technology is to provide a technology that can minimize off-track by taking into account individual differences among multiple drives and changes in the width of magnetic tape under the usage environment. It is in.

A cartridge according to one embodiment of the present technology includes a cartridge case and a memory.
The cartridge case accommodates a magnetic tape.
The memory is provided in the cartridge case and stores information before data is recorded on the magnetic tape, and information for adjusting the width of the magnetic tape during data recording or data reproduction on the magnetic tape.

With this technology, information for adjusting the width of the magnetic tape before recording data is stored in memory, so by using this information during data recording/playback, the width of the magnetic tape can be adjusted appropriately. . Therefore, even if the width of the magnetic tape changes due to environmental changes or long-term storage, or even if multiple drives perform recording/reproduction, data can be recorded/reproduced accurately.

The information includes width information for the entire length of the magnetic tape, which is acquired during at least one of an unwinding operation and a rewinding operation of the magnetic tape performed by a data recording/reproducing device before data recording. But that's fine.
The inner side of the wound magnetic tape is deformed in the lateral direction due to the winding stress, so the width may differ between the time of unwinding and the time of winding. Therefore, it is better to obtain both width information.

The width information may be discrete data acquired for each predetermined length of the magnetic tape.

The information may include environmental information around the magnetic tape at the time of acquiring the width information.

The environmental information may include information about the temperature around the magnetic tape at the time of acquiring the width information.

The environmental information may include information on humidity around the magnetic tape at the time of acquiring the width information.

The information may include information on the tension of the magnetic tape at the time of acquiring the width information.

The information may include information regarding the base material of the magnetic tape.

The width of the magnetic tape may be adjusted so that the width of the magnetic tape is the same as the width information during data reproduction or data recording.

The width of the magnetic tape may be adjusted by adjusting the tension of the magnetic tape.

The information includes environmental information around the magnetic tape at the time of acquiring the width information, and based on the difference between the environmental information and the environmental information measured at the time of data recording or data reproduction. The width may be adjusted.

The cartridge may be a cartridge based on the LTO (linear tape open) standard.

A memory according to one embodiment of the present technology is provided in a cartridge case that accommodates a magnetic tape, and stores information before data is recorded on the magnetic tape, and stores information on the magnetic tape when recording data on the magnetic tape or when reproducing data. Remember information for adjusting width.

A data recording device according to one embodiment of the present technology is a data recording device that records data on a magnetic tape, the data recording device being a data recording device that records data on a magnetic tape, the data being stored in a memory provided in a cartridge case accommodating the magnetic tape. The width information for the entire length of the tape is read out, and the width of the magnetic tape at the time of data recording on the magnetic tape is adjusted based on the width information.

A data reproducing device according to one embodiment of the present technology is a data reproducing device that reproduces data recorded on a magnetic tape, the data reproducing device reproducing data recorded on a magnetic tape, the data reproducing device reproducing data recorded on a magnetic tape. Width information for the entire length of the tape before data recording is read out, and based on the width information, the width of the magnetic tape is adjusted when data is reproduced from the magnetic tape.

FIG. 1 is an exploded perspective view showing a cartridge according to an embodiment of the present technology. FIG. 2 is a schematic diagram of a magnetic tape viewed from the side. FIG. 2 is a schematic diagram of a magnetic tape viewed from above. FIG. 1 is a diagram showing a data recording/reproducing device. 7 is a flowchart showing the processing of the control device when acquiring pre-data recording information. 5 is a flowchart showing the processing of the control device during data recording. 5 is a flowchart showing the processing of the control device during data reproduction. It is a figure which shows an example of TDS in a comparative example. FIG. 3 is a schematic diagram showing an off-track state of a data write/read head with respect to a recording track. It is a figure showing an example of TDS in this embodiment. FIG. 3 is a schematic diagram showing an on-track state of a data write/read head with respect to a recording track. FIG. 2 is a cross-sectional view showing the structure of magnetic particles. FIG. 7 is a cross-sectional view showing the configuration of magnetic particles in a modified example. FIG. 2 is a perspective view showing the configuration of a measuring device. FIG. 2 is a schematic diagram showing details of the measuring device. It is a graph showing an example of an SFD curve.

Embodiments of the present technology will be described below with reference to the drawings.

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

As shown in FIG. 1, the cartridge 10 includes a cartridge case 11, a magnetic tape 1 rotatably housed inside the cartridge case 11, and a cartridge memory 9 provided inside the cartridge case 11.

The cartridge case 11 is constructed by connecting an upper shell 11a and a lower shell 11b with a plurality of screw members. A single tape reel 13 wound with magnetic tape 1 is rotatably housed inside the cartridge case 11.

At the center of the bottom of the tape reel 13, a chucking gear (not shown) that engages with a spindle 31 (see FIG. 4) of the data recording/reproducing device 30 is formed in an annular shape. 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 peripheral side of the chucking gear.

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

A tape draw-out opening 19 is provided on one side wall of the cartridge case 11 for drawing out one end of the magnetic tape 1 to the outside. A sliding door 20 for opening and closing the tape outlet 19 is arranged inside this side wall. The sliding door 20 is configured to slide in the direction of opening the tape ejection opening 19 against the biasing force of the torsion spring 21 by engagement with a tape loading mechanism (not shown) of the data recording/reproducing device 30. .

A leader pin 22 is fixed to one end of the magnetic tape 1. The leader pin 22 is configured to be attachable to and detachable from a pin holding portion 23 provided on the inner side of the tape outlet 19. The pin holding portion 23 has an elastic member that elastically holds the upper end and the lower end of the leader pin 22 on the inner surface of the upper wall (the inner surface of the upper shell 11a) and the inner surface of the bottom wall (the inner surface of the lower shell 11b) of the cartridge case 11, respectively. A holder 24 is provided.

On the inside of the other side wall of the cartridge case 11, there is a safety tab 25 for preventing accidental erasure of the information recorded on the magnetic tape 1, as well as a safety tab 25 that allows the content related to the data recorded on the magnetic tape 1 to be read and written without contact. A cartridge memory 9 is arranged.

[Magnetic tape 1]
FIG. 2 is a schematic diagram of the magnetic tape 1 viewed from the side, and FIG. 3 is a schematic diagram of the magnetic tape 1 viewed from above.

As shown in FIGS. 2 and 3, the magnetic tape 1 has a tape shape 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). ing.

The magnetic tape 1 includes a tape-shaped base material 2 that is long in the longitudinal direction (X-axis direction), a non-magnetic layer 3 provided on one main surface of the base material 2, and a non-magnetic layer 3 provided on the non-magnetic layer 3. It includes a magnetic layer 4 and a back layer 5 provided on the other main surface of the base material 2. Note that the back layer 5 may be provided as needed, and the back layer 5 may be omitted.

The base material 2 is a nonmagnetic support that supports the nonmagnetic layer 3 and the magnetic layer 4. The base material 2 includes, for example, at least one of polyesters, polyolefins, cellulose derivatives, vinyl resins, and other polymer resins.

The magnetic layer 4 is a recording layer for recording data. This magnetic layer 4 contains magnetic powder, a binder, conductive particles, and the like. The magnetic layer 4 may further contain additives such as a lubricant, an abrasive, and a rust preventive, if necessary.

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

Nonmagnetic layer 3 contains nonmagnetic powder and a binder. The nonmagnetic layer 3 may contain additives such as electrolytic particles, a lubricant, a hardening agent, and a rust preventive material, if necessary.

The back layer 5 includes nonmagnetic powder and a binder. The back layer 5 may contain additives such as a lubricant, a curing agent, and an antistatic agent, if necessary.

The upper limit of the average thickness (average total thickness) of the magnetic tape 1 is, for example, 5.6 μm or less, 5.0 μm or less, 4.4 μm or less, etc. When the average thickness of the magnetic tape 1 is 5.6 μm or less, the recording capacity that can be recorded in the cartridge 1021 can be increased compared to that of the general magnetic tape 1.

As shown in FIG. 3, the magnetic layer 4 has a plurality of data bands d (data bands d0 to d3) long in the longitudinal direction (X-axis direction) in which data is written, and a plurality of data bands d (data bands d0 to d3) long in the longitudinal direction in which servo signals 7 are written. servo bands s (servo bands s0 to s4). The servo bands s are arranged at positions sandwiching each data band d in the width direction (Y-axis direction).

In the example shown in FIG. 3, the number of data bands d is four and the number of servo bands s is five. Note that the number of data bands d and the number of servo bands s can be changed as appropriate.

The data band d is long in the longitudinal direction and includes a plurality of recording tracks 6 arranged in the width direction. Data is recorded within the recording track 6 along this recording track 6. The length of one bit in the longitudinal direction of data recorded in data band d is, for example, 48 nm or less. The servo band s includes a predetermined pattern of servo signals 7 recorded by a servo signal recording device (not shown).

Here, in the LTO standard magnetic tape 1, the number of recording tracks 6 increases with each generation, and the recording capacity has dramatically improved. For example, the number of recording tracks 6 is 384 in the first generation LTO-1, but is 512, 704, 896, 1280, 2176, 3584, and 6656 in LTO-2 to LTO8, respectively. Similarly, the data recording capacity was 100 GB (gigabyte) in LTO-1, but 200 GB, 400 GB, 800 GB, 1.5 TB (terabyte), 2.5 TB in LTO-2 to LTO-8, respectively. They are 6.0TB and 12TB.

In this embodiment, the number of recording tracks 6 and the recording capacity are not particularly limited and can be changed as appropriate. However, if it is applied to a magnetic tape 1 that has a large number of recording tracks 6 or a large recording capacity (for example, 6656 or more, 12 TB or more: LTO8 or later) and is easily affected by changes in the width of the magnetic tape 1, It's advantageous.

[Cartridge memory 9]
The cartridge memory 9 is composed of, for example, a non-contact communication medium in which an antenna coil, an IC chip, etc. are mounted on a substrate. The IC chip includes a voltage generation section that generates a starting voltage based on a signal magnetic field from the reader/writer 37 (see FIG. 4) received via an antenna coil, a memory section that stores predetermined information regarding the cartridge 10, and a memory section. It has a built-in control unit that reads information.

The cartridge memory 9 operates without a power source because the antenna coil receives a signal magnetic field transmitted from the reader/writer 37 to generate electric power. The power supply/communication frequency from the reader/writer 37 is 13.56 MHz, which is the same as NFC (Near Field Communication). For example, non-volatile memory (NVM) is used as the memory section built into the IC chip.

Management information is stored in the memory section. The management information includes product information of the cartridge 10 and the magnetic tape 1, usage history information, and a summary of information recorded on the magnetic tape 1. The product information includes unique information such as manufacturing information, the number of recording tracks 6 on the magnetic tape 1, and an ID. The usage history information includes access date and time, address information, communication history with the reader/writer 37, presence or absence of abnormalities during loading/unloading of the data recording/reproducing device 30, and the like.

Here, in particular, in this embodiment, in addition to the above-mentioned management information, etc., in the memory section, information before data recording on the magnetic tape 1 is stored on the magnetic tape 1 during data recording or data reproduction. Information for adjusting the width of 1 (hereinafter referred to as pre-data recording information) is stored.

In this embodiment, during a predetermined tape operation process before data recording, the reader/writer 37 sends pre-data recording information (for example, temperature information, humidity information, tension information, magnetic (information on the width of the tape 1, etc.) is stored. Then, during data recording or data reproduction, this information is read by the reader/writer 37, and this information is used to deal with variations in the width of the magnetic tape 1.

Note that details of the pre-data recording information will be described later.

As described above, the number of recording tracks 6 in the LTO standard magnetic tape 1 increases with each generation, and the recording capacity has dramatically improved. As the number of recording tracks 6 on the magnetic tape 1 increases, the amount of management information stored in the cartridge memory 9 also increases, so the capacity (memory capacity) of the cartridge memory 9 also increases. For example, while it was 4kB (kilobyte) for LTO-1 and LTO-2, it is 8kB for LTO-3 to LTO-5, and 16kB for LTO-6 to LTO-8.

In this embodiment, the storage capacity of the cartridge memory 9 is not particularly limited and can be changed as appropriate. However, in this embodiment, not only management information but also pre-data recording information is written into the cartridge memory 9. Therefore, the storage capacity of the cartridge memory 9 may be greater than the capacity required by the LTO standard. For example, when the present technology is applied to the LTO-6 to LTO-8 (or later) standards, the recording capacity of the cartridge memory 9 is typically 16 kB or more.

[Data recording/playback device 30]
FIG. 4 is a diagram showing the data recording/reproducing device 30. As shown in FIG. As shown in FIG. 4, the data recording/reproducing device 30 is configured such that a cartridge 10 can be loaded therein. The data recording/reproducing device 30 is configured so that one cartridge 10 can be loaded therein, but may be configured so that a plurality of cartridges 10 can be loaded simultaneously.

The data recording/reproducing device 30 includes a spindle 31, a take-up reel 32, a spindle drive device 33, a reel drive device 34, and a plurality of guide rollers 35. The data recording/reproducing device 30 also includes a head unit 36, a reader/writer 37, a control device 38, a thermometer 39, and a hygrometer 40.

The spindle 31 has a head portion that engages with a chucking gear of the tape reel 13 through an opening 14 formed in the lower shell 11b of the cartridge 10. The spindle 31 raises the tape reel 13 by a predetermined distance against the biasing force of the reel spring 16, and releases the reel locking function of the reel locking member 17. Thereby, the tape reel 13 is rotatably supported inside the cartridge case 11 by the spindle 31.

The spindle drive device 33 rotates the spindle 31 in response to commands 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).

The 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 respect to the head unit 36. The reel drive device 34 rotates the take-up reel 32 in response to commands from the control device 38.

When recording/reproducing data on the magnetic tape 1, the spindle 31 and the take-up reel 32 are rotated by the spindle drive device 33 and the reel drive device 34, and the magnetic tape 1 runs. The running direction of the magnetic tape 1 is a forward direction (a direction in which the tape is unwound from the tape reel 13 side to the take-up reel 32 side) shown by an arrow A1 in FIG. It is possible to reciprocate in the direction of rewinding to the reel 13 side.

In this embodiment, 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 control the longitudinal direction (X-axis direction) of the magnetic tape 1 during data recording/reproduction. The tension can be adjusted. Note that the tension of the magnetic tape 1 is adjusted by controlling the movement of the guide roller 35 and a tension control unit including a dancer roller instead of (or in addition to) controlling the rotation of the spindle 31 and take-up reel 32. It may also be done by, etc.

The reader/writer 37 is configured to be able to record management information and pre-data recording information in the cartridge memory 9 in response to commands from the control device 38 . Further, the reader/writer 37 is configured to be able to read management information and pre-data recording 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.

The control device 38 includes, for example, a control section, a storage section, a communication section, and the like. The control section is constituted by, for example, a CPU (Central Processing Unit) or the like, and centrally controls each section of the data recording device 20 according to a program stored in a storage section.

The storage unit includes a nonvolatile 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 described above may be read from a portable recording medium such as an optical disk or a semiconductor memory, or may be downloaded from a server device on a network. The storage unit temporarily or non-temporarily stores information in the cartridge memory 9 read from the reader/writer 27, outputs from the thermometer 39 and the hygrometer 40, and the like. The communication unit is configured to be able to communicate with other devices such as a PC (Personal Computer) and a server device.

The head unit 36 is configured to be able to record data on the magnetic tape 1 in accordance with commands from the control device 38. Further, the head unit 36 is configured to be able to reproduce data written on the magnetic tape 1 in response to commands from the control device 38.

The head unit 36 includes, for example, two servo read heads, a plurality of data write/read heads, and the like.

The servo read head is configured to be able to reproduce the servo signal 7 by reading the magnetic field generated from the servo signal 7 recorded on the magnetic tape 1 using an MR element (MR: Magneto Resistive) or the like. The distance between the two servo read heads 32 in the width direction is approximately the same as the distance between two adjacent servo bands s.

The data write/read heads 33 are arranged at equal intervals along the width direction at positions sandwiched between the two servo read heads 32. The data write/read head 34 is configured to be able to record data on the magnetic tape 1 using a magnetic field generated from a magnetic gap. Further, the data write/read head 35 is configured to be able to reproduce data by reading a magnetic field generated from data recorded on the magnetic tape 1 using an MR element (MR: Magneto Resistive) or the like.

The thermometer 39 measures the temperature around the magnetic tape 1 (cartridge 10) during data recording/reproduction and outputs it to the control device 38. Furthermore, the hygrometer 40 measures the humidity around the magnetic tape 1 (cartridge 10) during data recording/reproduction, and outputs it to the control device 38.

<Variations in the width of magnetic tape 1>
As mentioned above, according to the LTO standard, as the storage capacity increases, the total thickness of the magnetic tape 1 becomes thinner and the number of recording tracks 6 increases. In such a case, the width of the recording track 6 becomes narrow, and a slight variation in the width of the magnetic tape 1 (in the Y-axis direction) may become a problem. For example, the data recording/reproducing device 30 stores predetermined data on the magnetic tape 1, and then (for example, after storage for a certain period of time), the data recording/reproducing device 30 reproduces the data recorded on the magnetic tape 1. Suppose that In such a case, if the width of the magnetic tape 1 during data reproduction varies even slightly compared to the width when data is recorded on the magnetic tape 1, the data recorded on the magnetic tape 1 may not be reproduced accurately. There is a possibility that an error may occur.
For example, this type of cartridge 10 is mainly used in data centers and is stored for a long time after data is recorded, so the width of the magnetic tape 1 is likely to vary depending on the storage environment. In addition, since the magnetic tape 1 is recorded and played back by multiple drives (data recording/playback device 30) in data centers, etc., playback errors in recorded data may occur due to individual differences among the drives. There is a possibility that it will happen.

Possible causes of variations in the width of the magnetic tape 1 include, for example, the following (1) to (4).

(1) Fluctuation in temperature The temperature when data is recorded on the magnetic tape 1 is different from the temperature when data is reproduced from the magnetic tape 1.
(A) For example, if the temperature of the magnetic tape 1 during data recording is high, the data will be stored with the width of the magnetic tape 1 expanded. It is assumed that the magnetic tape 1 is then stored at a low temperature for a certain period of time, and the data on the magnetic tape 1 is reproduced at the low temperature. In this case, the width of the magnetic tape 1 during data reproduction is narrower than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 is narrower. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.
(B) Conversely, if the temperature of the magnetic tape 1 during data recording is low, the data is stored with the width of the magnetic tape 1 contracted. It is assumed that the magnetic tape 1 is then stored at a high temperature for a certain period of time, and the data on the magnetic tape 1 is reproduced at the high temperature. In this case, the width of the magnetic tape 1 during data reproduction has become wider than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 has also become wider. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.

(2) Fluctuations in Humidity The humidity when data is recorded on the magnetic tape 1 is different from the humidity when data is reproduced from the magnetic tape 1.
(A) For example, if the humidity at the time of data recording on the magnetic tape 1 is high, the data will be stored with the width of the magnetic tape 1 expanded. It is assumed that the magnetic tape 1 is then stored at low humidity for a certain period of time, and the data on the magnetic tape 1 is reproduced at low humidity. In this case, the width of the magnetic tape 1 during data reproduction is narrower than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 is also narrower. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.
(B) Conversely, if the humidity at the time of data recording on the magnetic tape 1 is low, the data is stored with the width of the magnetic tape 1 contracted. It is assumed that the magnetic tape 1 is then stored at high humidity for a certain period of time, and the data on the magnetic tape 1 is reproduced at high humidity. In this case, the width of the magnetic tape 1 during data reproduction has become wider than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 has also become wider. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.

(3) Tension variation The tension applied in the longitudinal direction (X-axis direction) of the magnetic tape 1 during data recording is different from the tension applied in the longitudinal direction of the magnetic tape 1 during data reproduction.
(A) For example, if the tension when recording data on the magnetic tape 1 is high, the data is stored with the width of the magnetic tape 1 contracted. After that, for example, when the magnetic tape 1 is played back with a device different from the device that recorded the data (although it may be the same device), the data on the magnetic tape 1 is played back with a lower tension than when the data was recorded. Suppose it is played. In this case, the width of the magnetic tape 1 during data reproduction has become wider than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 has also become wider. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.
(B) Conversely, if the tension on the magnetic tape 1 during data recording is low, the data is stored with the width of the magnetic tape 1 expanded. After that, for example, when the magnetic tape 1 is played back with a device different from the device that recorded the data (although it may be the same device), the data on the magnetic tape 1 is played back with a higher tension than when the data was recorded. Suppose it is played. In this case, the width of the magnetic tape 1 during data reproduction is narrower than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 is also narrower. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.

(4) Others The tension when recording data on the magnetic tape 1 was higher than necessary, so the magnetic tape 1 was wound with a higher tension than necessary, and the magnetic tape 1 was stored in that state for a certain period of time. Suppose that In this case, the width of the magnetic tape 1 increases inside the cartridge 10 due to the winding tension. In this case, the width of the magnetic tape 1 during data reproduction has become wider than the width of the magnetic tape 1 during data recording, and the width of the recording track 6 has also become wider. In this case, the head unit 36 cannot be accurately aligned with the recording track 6, and an error may occur.

<Information before data recording>
Next, the pre-data recording information recorded in the memory section of the cartridge memory 9 will be explained.

As described above, the pre-data recording information is information for adjusting the width of the magnetic tape 1 when recording or reproducing data on the magnetic tape 1. In this embodiment, the pre-tape recording information includes information regarding the width over the entire length of the magnetic tape 1.

When the cartridge 10 is loaded, the data recording/reproducing device 30 runs the magnetic tape 1 in the forward direction (in the direction of arrow A1) and completely unwinds it onto the take-up reel 32 before recording data on the magnetic tape 1. After that, a series of tape operation processes are executed in which the magnetic tape 1 is run in the opposite direction (direction of arrow A2) and completely rewound onto the tape reel 13. The unwinding operation of the magnetic tape 1 is executed by the unwinding operation (FF) of the data recording/reproducing device 30, and the rewinding operation of the magnetic tape 1 is executed by the rewinding operation (REW) of the data recording/reproducing device 30. be done. In this series of tape operation processing, neither data recording nor data reproduction is performed.

Therefore, in this embodiment, width information of the entire length of the magnetic tape 1 is acquired as pre-data recording information during execution of the tape manipulation process. The width information includes width information of the entire length along the forward direction of the magnetic tape 1 acquired during the unwinding operation of the magnetic tape 1 (hereinafter also referred to as first width information), and width information acquired during the unwinding operation of the magnetic tape 1. The width information of the acquired entire length of the magnetic tape 1 in the opposite direction (hereinafter also referred to as second width information) is included. These width information are referred to as reference values for adjusting the width of the magnetic tape 1 during data recording or data reproduction, as will be described later.

Here, the first and second width information typically refers to the tape width of the magnetic tape 1, and here, the first and second width information typically refers to the width of each part of the magnetic tape when running in the forward direction and reverse direction. Information. The first and second width information are discrete data acquired for each predetermined length of the magnetic tape 1. This makes it possible to suppress an increase in the amount of information regarding width. The predetermined length is not particularly limited, and is, for example, 1 m to 20 m. The sampling rate of the width information is also not particularly limited, and can be arbitrarily set according to the unwinding/rewinding speed of the magnetic tape 1.

The first and second width information are obtained using the head unit 36 of the data recording/reproducing device 30. During the unwinding or rewinding operation of the magnetic tape 1, the head unit 36 reads the servo signals 7 recorded on two predetermined servo bands s adjacent to each other. At this time, the distance in the width direction of the two servo bands s is determined from the reproduced waveform of the servo signal read from the two servo bands s. Then, the width of the entire magnetic tape 1 is determined from the determined distance, and this information is written into the memory section of the cartridge memory 9 by the reader/writer 37. Hereinafter, the first width information and the second width information will be collectively referred to as information regarding the width W1 extending over the entire length of the magnetic tape 1, unless explained separately.

The reason why the width of the entire length of the magnetic tape 1 is obtained as width information is because the tightening force is stronger at the beginning of winding onto the tape reel 13, so the tape width tends to be larger than at the end of winding, and the tape width is not uniform. It's for a reason. This tendency becomes more pronounced as the tape length becomes longer. Further, the width information may be only the first width information or only the second width information.

Note that the inner circumferential side of the magnetic tape 1 wound onto the tape reel 13 is deformed in the lateral direction due to the winding stress, so that the width may be different between the time of unwinding and the time of winding. Depending on the type of magnetic tape 1, when the winding start side (inner peripheral side) of the magnetic tape 1 is pulled out from the tape reel 13, the winding stress is released and the tape width at the winding start side may increase. In this case, since the width of the winding start side of the magnetic tape 1 differs when traveling in the forward direction and when traveling in the reverse direction, it is preferable to acquire both the first width information and the second width information.

The pre-data recording information may include environmental information around the magnetic tape 1 before data is recorded on the magnetic tape 1. The environmental information includes information such as the temperature Tm1 around the magnetic tape 1 and the humidity H1 before data is recorded on the magnetic tape 1. Here, the term "before data recording" refers to the time when the above-mentioned series of tape operation processes (unwinding and rewinding operations over the entire length of the magnetic tape 1) are executed before data recording.

For example, regarding the information on temperature Tm1, when the data recording/reproducing device 30 executes the series of tape operation processes described above, the temperature Tm1 at that time is measured by the thermometer 39, and the measured value is transmitted to the reader/writer. 37 to the memory section. Regarding the humidity information H1, when the data recording/reproducing device 30 executes the series of tape operation processes described above, the humidity H1 at that time is measured by the hygrometer 40, and the measured value is sent to the reader/writer 37. is written to the memory section by.

The pre-data recording information also includes information on the tension T1 in the longitudinal direction (X-axis direction) applied to the magnetic tape 1 in the series of tape manipulation processes described above. The tension T1 is a constant value, for example, 0.55N. Hereinafter, this tension T1 will also be referred to as a reference tension.

Further, the pre-data recording information may include information regarding the base material 2 of the magnetic tape 1. Examples of the information regarding the base material 2 include material, thickness, elastic modulus, linear expansion coefficient, and the like. These pieces of information are used, for example, to set parameters for tension calculation executed during data recording or data reproduction, which will be described later.

<Operation explanation>
Next, the processing of the control device 38 of the data recording/reproducing device 30 will be explained.

[Acquisition of information before data recording]
In the description here, first, the processing of the control device 38 when acquiring the pre-data recording information will be described. FIG. 5 is a flowchart showing the processing of the control device 38 when acquiring pre-data recording information.

When the cartridge 10 is loaded into the data recording/reproducing device 30, the control device 38 (control unit) loads the cartridge 10 (step 001). Thereafter, the control device 38 acquires information regarding W1 of the magnetic tape 1 as pre-data recording information. More specifically, the control device 38 controls the rotation of the spindle 31 and the take-up reel 32 to fast-forward the magnetic tape 1 at a reference tension, and in the process acquires first width information of the magnetic tape 1 ( Step 002). Subsequently, the control device 38 rewinds the magnetic tape 1 at the reference tension by controlling the rotation of the spindle 31 and the take-up reel 32, and in the process acquires second width information of the magnetic tape 1 (step 003). ).

The cartridge 10 from which the information regarding the width W1 is acquired as the pre-data recording information is typically an unused cartridge. If an unused cartridge has been shipped for a considerable period of time, or if the width of the magnetic tape 1 has changed compared to when it was shipped due to changes in the magnetic tape 1 over time (aging) or the storage environment, etc. There is. By acquiring information regarding the width W1 of the magnetic tape 1 immediately before use when using the cartridge 10 for the first time (during data recording), it is possible to eliminate as much as possible the influence of unused periods, storage conditions, and the like.

Obtaining the pre-data recording information is typically performed as pre-processing when data is recorded on the cartridge 10 for the first time. When acquiring information regarding the width W1 (first width information, second width information), the two servo read heads of the head unit 36 are used to track the recording track where data is written during the first data recording. The distance between the two servo bands s in the width direction (Y-axis direction in FIG. 3) is determined from the reproduced waveform of the servo signal 7 obtained by tracing the two servo bands s. Based on this distance, the control device 38 adjusts the width W1 of the magnetic tape 1 for each predetermined length of the magnetic tape 1 (for each divided region when the entire length of the magnetic tape 1 is divided into a plurality of regions). Calculate. The control device 38 may write the value of the width W1 calculated as described above into the cartridge memory 9 as information regarding the width W1, or may write the distance between the two servo bands s in the width direction into the cartridge memory 9 as is. You can also write it down.

The control device 38 further acquires information on the temperature Tm1 and humidity H1 (environmental information) around the magnetic tape 1 from the thermometer 39 and the hygrometer 40 as pre-data recording information (step 004). The timing of acquiring the environmental information is not particularly limited, and may be at the time of loading the cartridge 10, at the unwinding operation of the magnetic tape 1 (when acquiring the first width information), or at the time of the rewinding operation of the magnetic tape 1 (when the second width information is acquired). (at the time of information acquisition).

Subsequently, the control device 38 causes the reader/writer 37 to record the pre-data recording information (first width information, second width information, and temperature/humidity information) acquired in steps 002 to 004 into the cartridge memory 9 ( Step 005). The pre-data recording information recorded in the cartridge memory 9 is read out during data recording and data reproduction, which will be described later, and is referred to as a reference value for tension adjustment.

Subsequently, the control device 38 executes data recording processing (step 005). The control device 38 controls the rotation of the spindle 31 and the take-up reel 32 to run the magnetic tape 1 while applying a reference tension to the magnetic tape 1 in the longitudinal direction (X-axis direction). Then, the control device 38 records data on the magnetic tape 1 using the head unit 36. After the data recording process is completed, the cartridge 10 is removed from the data recording/reproducing device 30.

Note that the pre-data recording information may be acquired each time the cartridge 10 is used. Furthermore, when reusing the cartridge 10 or rewriting the entire recorded information, the recorded contents of the cartridge memory 9 may be updated with the acquired pre-data recording information.

[When recording data]
Next, the processing of the control device 38 during the second and subsequent data recording will be explained. FIG. 6 is a flowchart showing the processing of the control device 38 during data recording.

First, the control device 38 (control unit) loads the cartridge 10 into the data recording/reproducing device 30 (step 101). Next, the control device 38 uses the reader/writer 37 to read out the pre-data recording information (information regarding the width W1 of the magnetic tape 1, information about the temperature Tm1, and information about the humidity H1) written in the cartridge memory 9, and reads the information. Obtain (step 102).

Next, the control device 38 acquires information on the current temperature Tm2 and humidity H2 around the magnetic tape 1 at the time of data recording from the thermometer 39 and the hygrometer 40 (step 103).

Next, the control device 38 calculates the temperature difference TmD (TmD=Tm2-Tm1) between the past temperature Tm1 at the time of acquiring the pre-data recording information and the current temperature Tm2 at the time of data recording (step 104). Further, the control device 38 calculates the humidity difference HD (HD=H2-H1) between the past humidity H1 at the time of acquiring the pre-data recording information and the current humidity H2 at the time of data recording (step 105).

Next, the control device 38 multiplies the temperature difference TmD by a coefficient α (TmD×α), and multiplies the humidity difference HD by a coefficient β (HD×β) (step 106).

The coefficient α is a value indicating how much the width of the magnetic tape 1 changes per 1° C. temperature difference (a value indicating the expansion rate per unit length (width direction) based on temperature). How much the tension of the magnetic tape 1 should be changed compared to the reference tension T1, which is the tension at the time of acquiring information before data recording, is determined by how much the width deforms when tension is applied in the longitudinal direction of the magnetic tape 1. It is determined by dividing the coefficient α by a value (hereinafter also referred to as ΔW) indicating whether the
Similarly, the coefficient β is a value indicating how much the width of the magnetic tape 1 changes per 1% humidity difference (a value indicating the expansion rate per unit length (width direction) based on humidity). The extent to which the tension of the magnetic tape 1 should be changed compared to the reference tension T1 is determined by the value obtained by dividing the coefficient β by ΔW.

Next, the control device 38 adds the value of TmD×α and the value of HD×β to the reference tension T1 to create a tension T2 that should be applied to the magnetic tape 1 at the time of data recording (currently). is calculated (step 107).
T2=T1+TmD×α+HD×β

After determining the tension T2 of the magnetic tape 1 during data recording, the control device 38 controls the drive of the spindle 31 and take-up reel 32 so that the magnetic tape 1 runs with the tension T2. control. By adjusting the tension of the magnetic tape 1, the width of the magnetic tape 1 is adjusted to be the same as the width W1 acquired as the pre-data recording information (step 108). Thereby, the data write/read head of the head unit 36 is accurately aligned with the recording track 6. The tension adjustment range is not particularly limited, and is, for example, 0.2N or more and 1.2N or less.

In this embodiment, it is confirmed from the reproduced waveform of the servo signal 7 whether the width of the magnetic tape 1 matches the width W1. In this case, when the running direction of the magnetic tape 1 is the forward direction (arrow A1 direction in FIG. 4), the first width information is referred to, and when the running direction of the magnetic tape 1 is the reverse direction (arrow A2 direction in FIG. 4), the first width information is referred to. In this case, the second width information is referred to. If the width of the magnetic tape 1 does not match the width W1, the tension T2 is corrected so that it matches the width W1. The first width information and the second width information each include width information for each tape area of the magnetic tape 1, so the width of the magnetic tape 1 is optimized according to the tape area currently running. can do.

Then, the control device 38 records data on the recording track 6 using the data write/read head of the head unit 36 while reading the servo signal 7 of the servo band s using the servo read head of the head unit 36 (step 109). ). As a result, even if the width of the magnetic tape 1 fluctuates due to environmental changes (for example, changes in temperature and humidity), data can be accurately recorded on the recording track 6 of the magnetic tape 1. .

Note that expansion due to temperature can occur not only in the magnetic tape 1 but also in the head unit 36, so the tension can be adjusted in response to temperature changes depending on which of the thermal expansion coefficients of the magnetic tape 1 and the head unit 36 is larger. The direction changes.

Typically, the thermal expansion coefficient of the magnetic tape 1 is larger than that of the head unit 36. In this case, the value of the tension T2 to be applied to the magnetic tape 1 at the time of data recording (currently) increases if the temperature Tm2 at the time of data recording is higher than the temperature Tm1 at the time of acquiring the information before data recording. Therefore, when the temperature becomes high and the width of the magnetic tape 1 becomes wider than the width W1, the width of the magnetic tape 1 can be narrowed to reproduce the same width as the width W1.

Conversely, the value of the tension T2 to be applied to the magnetic tape 1 at the time of data recording (currently) is lower if the temperature Tm2 at the time of data recording is lower than the temperature Tm1 at the time of acquiring the information before data recording. Therefore, when the temperature becomes low and the width of the magnetic tape 1 becomes narrower than the width W1, the width of the magnetic tape 1 can be increased to reproduce the same width as the width W1.

Further, the value of the tension T2 to be applied to the magnetic tape 1 at the time of data recording (currently) increases if the humidity H2 at the time of data recording is higher than the humidity H1 at the time of acquiring the information before data recording. Therefore, when the humidity becomes high and the width of the magnetic tape 1 becomes wider than the width W1, the width of the magnetic tape 1 can be narrowed to reproduce the same width as the width W1.

Conversely, the value of the tension T2 to be applied to the magnetic tape 1 at the time of data recording (currently) becomes lower if the humidity H2 at the time of data recording is lower than the humidity H1 at the time of acquiring the information before data recording. Therefore, when the humidity becomes low and the width of the magnetic tape 1 becomes narrower than the width W1, the width of the magnetic tape 1 can be increased to reproduce the same width as the width W1.

Here, in order to obtain the tension T2 to be applied to the magnetic tape 1 during data recording, the temperature Tm1 and the humidity H1 at the time of acquiring the pre-data recording information, as well as the reference tension T1 (or in place of the reference tension T1) are used. Furthermore, information on the width W1 of the magnetic tape 1 may be used.

In this case, in step 106, the control device 38 calculates the temperature difference TmD (TmD=Tm2-Tm1) and the humidity difference HD (HD=H2-H1). Then, the control device 38 multiplies the temperature difference TmD by a coefficient α (TmD×α), and multiplies the humidity difference HD by a coefficient β (HD×β).

Next, the control device 38 calculates the current width W2 of the magnetic tape 1 based on the width W1 using the following formula.
W2=W1 (1+TmD×α+HD×β)

Next, the control device 38 calculates the difference WD between the current width W2 of the magnetic tape 1 and the width W1 (WD=W2-W1=W1(TmD×α+HD×β)).

Then, the control device 38 calculates the tension T2 of the magnetic tape 1 at the time of data recording by adding the value obtained by multiplying the width difference WD by the coefficient ε to the reference tension T1.
T2=T1+WD×ε

Here, the coefficient ε is a value representing the tension in the longitudinal direction of the magnetic tape 1 necessary to change the width of the magnetic tape 1 by a unit distance.

After determining the tension T2 of the magnetic tape 1 during data recording, the control device 38 controls the drive of the spindle 31 and take-up reel 32 so that the magnetic tape 1 runs with the tension T2. control. Then, the control device 38 records data on the recording track 6 using the data write/read head of the head unit 36 while reading the servo signal 7 of the servo band s using the servo read head of the head unit 36 .

Even if the tension T2 is determined in this way, if the width of the magnetic tape 1 fluctuates due to environmental changes (for example, changes in temperature or humidity), data cannot be transferred to the magnetic tape 1. Can be recorded accurately.

[When playing data]
Next, the processing of the control device 38 during data reproduction will be explained. FIG. 7 is a flowchart showing the processing of the control device 38 during data reproduction. When reproducing data, the width of the magnetic tape 1 is adjusted in the same manner as when recording data, and then data is reproduced.

During data reproduction, the control device 38 (control unit) first loads the cartridge 10 into the data recording/reproducing device 30 (step 201). Next, the control device 38 transfers the data recording time information written in the cartridge memory 9 (information on the width W1 of the magnetic tape 1, information on the temperature Tm1, information on the humidity H1, and information on the reference tension T1) to the reader/writer 37. (step 202).

Next, the control device 38 acquires information on the current temperature Tm3 and humidity H3 around the magnetic tape 1 at the time of data reproduction from the thermometer 39 and the hygrometer 40 (step 203).

Next, the control device 38 calculates the temperature difference TmD (TmD=Tm3-Tm1) between the past temperature Tm1 at the time of acquiring the pre-data recording information and the current temperature Tm3 at the time of data reproduction (step 204). Further, the control device 38 calculates the humidity difference HD (HD=H3-H1) between the past humidity H1 at the time of acquiring the pre-data recording information and the current humidity H3 at the time of data reproduction (step 205).

Next, the control device 38 multiplies the temperature difference TmD by a coefficient α (TmD×α), and multiplies the humidity difference HD by a coefficient β (HD×β) (step 206).

Next, the control device 38 adds the value of TmD×α and the value of HD×β to the reference tension T1 to create a tension T3 that should be applied to the magnetic tape 1 at the time of data reproduction (currently). is calculated (step 207).
T3=T1+TmD×α+HD×β

After determining the tension T3 of the magnetic tape 1 during data reproduction, the control device 38 controls the drive of the spindle 31 and take-up reel 32 so that the magnetic tape 1 runs at the tension T3. control. By adjusting the tension of the magnetic tape 1, the width of the magnetic tape 1 is adjusted to be the same as the width W1 acquired as the pre-data recording information (step 208). Thereby, the data write/read head of the head unit 36 is accurately aligned with the recording track 6. The tension adjustment range is not particularly limited, and is, for example, 0.2N or more and 1.2N or less.

Note that it may be confirmed from the reproduced waveform of the servo signal 7 whether the width of the magnetic tape 1 matches the width W1. In this case, when the running direction of the magnetic tape 1 is the forward direction (arrow A1 direction in FIG. 4), the first width information is referred to, and when the running direction of the magnetic tape 1 is the reverse direction (arrow A2 direction in FIG. 4), the first width information is referred to. In this case, the second width information is referred to. If the width of the magnetic tape 1 does not match the width W1, the tension T3 is corrected so that it matches the width W1. The first width information and the second width information each include width information for each tape area of the magnetic tape 1, so the width of the magnetic tape 1 is optimized according to the tape area currently running. can do.

Then, the control device 38 reads the servo signal 7 of the servo band s with the servo read head of the head unit 36, and reproduces the data recorded on the recording track 6 with the data write/read head of the head unit 36 ( Step 209). Thereby, even if the width of the magnetic tape 1 changes due to environmental changes (for example, changes in temperature and humidity), the data recorded on the magnetic tape 1 can be accurately reproduced.

Also during data reproduction, in order to determine the tension T2 to be applied to the magnetic tape 1, in addition to (or in place of) the temperature Tm1 and humidity H1 and the reference tension T1 at the time of acquiring the pre-data recording information, Furthermore, information on the width W1 of the magnetic tape 1 may be used.

In this case, in step 206, the control device 38 calculates the temperature difference TmD (TmD=Tm3-Tm1) and the humidity difference HD (HD=H3-H1). Then, the control device 38 multiplies the temperature difference TmD by a coefficient α (TmD×α), and multiplies the humidity difference HD by a coefficient β (HD×β).

Next, the control device 38 calculates the current width W3 of the magnetic tape 1 based on the width W1 using the following formula.
W3=W1 (1+TmD×α+HD×β)

Next, the control device 38 calculates the difference WD between the current width W3 of the magnetic tape 1 and the width W1 (WD=W3-W1=W1(TmD×α+HD×β)).

Then, the control device 38 calculates the tension T3 of the magnetic tape 1 during data reproduction by adding a value obtained by multiplying the width difference WD by a coefficient ε to the reference tension T1.
T3=T1+WD×ε

After determining the tension T3 of the magnetic tape 1 during data reproduction, the control device 38 controls the drive of the spindle 31 and take-up reel 32 so that the magnetic tape 1 runs at the tension T3. control. Then, the control device 38 reads the servo signal 7 of the servo band s using the servo read head of the head unit 36, and reproduces the data recorded on the recording track 6 using the data write/read head of the head unit 36.

Even when the tension T3 is determined in this way, if the width of the magnetic tape 1 fluctuates due to environmental changes (for example, changes in temperature and humidity), the width of the magnetic tape 1 may change. data can be accurately reproduced.

<Effect, etc.>
As explained above, in this embodiment, information regarding the width W1, tension T1, temperature Tm, humidity H, etc. acquired before data recording on the magnetic tape 1 is stored in the cartridge memory 9, so this information is stored in the data. By using it during recording and data reproduction, the width of the magnetic tape 1 can be adjusted to a reference value (width W1). Therefore, even if the width of the magnetic tape 1 changes due to environmental changes or long-term storage, or even if recording and playback are performed using multiple drives, data can be recorded accurately on the magnetic tape 1. Alternatively, data recorded on magnetic tape can be accurately reproduced.

Further, in this embodiment, information on the temperature Tm1 and humidity H1 (environmental information) around the magnetic tape 1 at the time of acquiring the information on the width W1 are written as pre-data recording information. Therefore, it is possible to appropriately cope with variations in the width of the magnetic tape 1 and the width of the recording track 6 due to differences in temperature and humidity during data recording or data reproduction.

Furthermore, in the present embodiment, when recording data, the magnetic tape 1 is The width is adjusted. Thereby, the width of the magnetic tape 1 can be adjusted more appropriately during data recording.
Similarly, during data reproduction, the width of the magnetic tape 1 is adjusted based on the difference TmD, HD between the temperature Tm1 and humidity H1 and the temperature Tm3 and humidity H3 during data reproduction. Thereby, the width of the magnetic tape 1 can be adjusted more appropriately during data reproduction.

Therefore, according to the present embodiment, when recording/reproducing data, the width of the magnetic tape can be actively changed to the width W1 of the magnetic tape 1 measured at the time of acquiring the information before data recording. Misalignment (off-track) of the data write/read head of the head unit 36 with respect to one recording track 6 can be minimized. This makes it possible to cope with an increase in track density.

For example, TDS (Transverse Dimensional Stability) is an index for evaluating the dimensional stability of the magnetic tape 1 in the width direction. TDS is an absolute value representing the rate of change in the dimension of the magnetic tape 1 in the width direction based on the width dimension of the standard magnetic tape 1 (width W1 in this embodiment), and the value of TDS is The smaller the size, the higher the dimensional stability in the width direction.

TDS is affected by environmental changes such as temperature and humidity, changes over time (aging), tension during data recording/reproduction, etc., and TDS cannot be reduced if no measures are taken. For example, FIG. 8 shows an example of actual performance in LTO-7. In the example shown in FIG. 8, a little less than 600 ppm is added due to environmental changes and aging, and a little less than 200 ppm is added due to the influence of tension during data recording/reproduction, so that the TDS becomes at least 750 ppm or more. In this case, off-track of the head unit with respect to the recording track is likely to occur, making it difficult to perform accurate data recording/reproduction.

FIG. 9 is a schematic diagram illustrating an off-track state of the head unit. Here, the situation is shown when the tape width changes in a direction in which the width of the magnetic tape 1 becomes smaller than the standard value (W1). As shown in the figure, in the recording track 61, both the data write head 36w and the data read head 36r are in an on-track state, whereas in the recording track 62, the data read head 36r is in an off-track state. In the linear recording method, the head width of the data read head 36r is narrower than the head width of the data write head 36w, so it is necessary to reduce the influence of off-track to improve track density. Furthermore, since the margin of the head width of the data write head 36w with respect to the recording track width is smaller than that of the head width of the data read head 36, stricter control is required for tracking during data recording in order to improve the track density.

On the other hand, in this embodiment, the tension is adjusted so that the width of the magnetic tape 1 becomes the standard value (W1) during data recording/reproduction, so that the TDS of the magnetic tape 1 can be reduced. For example, as shown in FIG. 10, the tape width fluctuation factors due to environmental changes and aging can be reduced by adjusting the tension. Thereby, the TDS can be suppressed to, for example, 200 ppm or less, so that off-track can be suppressed to a minimum. FIG. 11 is a schematic diagram showing the relative positional relationship between the magnetic tape 1 and the head unit 36 when off-track is minimized. According to this embodiment, as shown in the figure, it is possible to stably maintain the on-track state of the data write head 36w and the data read head 36r with respect to the recording tracks 61 and 62.

<Various variations>
Here, fluctuations in the width of the magnetic tape 1 and the width of the recording track 6 due to temperature and humidity are greater at positions at both ends of the magnetic tape 1 than at the center in the width direction (Y-axis direction). , the fluctuations may be large. Therefore, when recording/reproducing data, the magnitude of the tension on the magnetic tape 1 may be varied depending on the position of the recording track where data is to be recorded/reproduced.

For example, assume that the tension of the magnetic tape 1 is Tn(a) when the position of the recording track on which data is to be recorded/reproduced is near the center of the magnetic tape 1 in the width direction. Further, it is assumed that the tension of the magnetic tape 1 is Tn(b) when the positions of the recording tracks on which data is to be recorded/reproduced are at both ends of the magnetic tape 1 in the width direction.

In this case, if the temperature and humidity at the time of data recording/reproduction are higher than at the time of acquiring the information before data recording and the width of the magnetic tape 1 is widened, Tn(a)<Tn(b). Thus, the tension Tn of the magnetic tape 1 during data reproduction is adjusted.

Conversely, if the temperature and humidity at the time of data recording/reproduction are lower than at the time of acquiring the information before data recording and the width of the magnetic tape 1 is narrowed, Tn(a)>Tn(b). Thus, the tension Tn of the magnetic tape 1 during data reproduction is adjusted.

In the above description, a case has been described in which all of the information on temperature Tm1, information on humidity H1, information on reference tension T1, and information on width W1 are used as information before data recording. On the other hand, the pre-data recording information may be any one of temperature Tm1 information, humidity H1 information, reference tension T1 information, and width W1 information, or any combination of two or three. It may be.

In addition, the tension during data recording/reproduction is not limited to calculating from temperature and humidity information, but it is also possible to monitor the width of the magnetic tape 1 while changing the tension in stages, and check that the width matches the width W1. Sometimes the change in tension may be stopped. In this case, it can be determined whether to increase or decrease the tension from the information on temperature and humidity acquired during data recording/reproduction.

In the above description, the data recording/reproducing device 30 having both data recording/reproducing functions has been described as an example of the device. On the other hand, the data recording/reproducing device 30 may be a separate data recording device having at least a data recording function and a data reproducing device having at least a data reproducing function.

<Magnetic recording medium>
Next, a detailed example of a magnetic recording medium used in the magnetic tape 1 will be described.

The present inventors have studied a magnetic recording medium that is thin and suitable for use in a recording/reproducing device that adjusts tension in the longitudinal direction. As a result, the inventors discovered that a magnetic recording medium having a specific configuration satisfies these requirements. That is, the present technology has a layer structure including a magnetic layer, a non-magnetic layer, and a base layer in this order, the average thickness t _T is t _T ≦5.5 μm, and the width direction change with respect to the longitudinal tension change is A magnetic recording medium can be used in which the amount of dimensional change Δw satisfies 660 ppm/N≦Δw, and the average thickness t _n of the nonmagnetic layer satisfies t _n ≦1.0 μm.

The dimensional change amount Δw is 660 ppm/N≦Δw and the average thickness t _n is t _n ≦1.0 μm, making the thin magnetic recording medium suitable for use in a recording/reproducing device that adjusts longitudinal tension. It is assumed that there is
In addition, the amount of dimensional change Δw in the width direction due to a change in tension in the longitudinal direction of a magnetic recording medium largely depends on the physical characteristics of the base layer among the layers of the magnetic recording medium, but It is believed that it also depends on the physical properties of the non-magnetic layer, particularly the thickness t _n of the non-magnetic layer. It is considered that t _n ≦1.0 μm is suitable for increasing Δw.

The average thickness _tT of the magnetic recording medium according to the present technology is 5.5 μm or less, more preferably 5.3 μm or less, even more preferably 5.2 μm or less, 5.0 μm or less, or 4.6 μm or less. sell. Since the magnetic recording medium according to the present technology is thus thin, the length of the tape wound into one magnetic recording cartridge can be made longer, thereby increasing the recording capacity per one magnetic recording cartridge. be able to.

In the magnetic recording medium according to the present technology, the dimensional change Δw in the width direction with respect to the change in tension in the longitudinal direction is 660 ppm/N or more, preferably 670 ppm/N or more, more preferably 700 ppm/N or more, and More preferably, it may be 710 ppm/N or more, 730 ppm/N or more, 750 ppm/N or more, 780 ppm/N or more, or 800 ppm/N or more. The fact that the magnetic recording medium has a dimensional change ΔW within the above numerical range contributes to making it possible to keep the width of the magnetic recording medium constant by adjusting the tension in the longitudinal direction of the magnetic recording medium. do.
Further, the upper limit of the dimensional change amount ΔW is not particularly limited, but for example, 1700000 ppm/N or less, preferably 20000 ppm/N or less, more preferably 8000 ppm/N or less, even more preferably 5000 ppm/N or less, It can be 4000 ppm/N or less, 3000 ppm/N or less, or 2000 ppm/N or less. If the amount of dimensional change ΔW is too large, it may be difficult to run stably during the manufacturing process.

The average thickness t _n of the nonmagnetic layer of the magnetic recording medium according to the present technology is preferably t _n ≦1.0 μm, more preferably t _n ≦0.9 μm, and even more preferably t _n ≦0.7 μm. It is. The average thickness t _n of the nonmagnetic layer is, for example, 0.01 μm≦t _n , and preferably 0.02 μm≦t _n .

The surface roughness R _ab of the back layer of the magnetic recording medium according to the present technology is preferably 3.0 nm≦R _ab ≦7.5 nm, more preferably 3.0 nm≦Rab≦7.3 nm. Having the surface roughness R _ab within the above numerical range contributes to improving the handling properties of the magnetic recording medium.
The surface roughness R _ab of the back layer is more preferably 7.2 nm or less, and even more preferably 7.0 nm or less, 6.5 nm or less, 6.3 nm or less, or 6.0 nm or less. Further, the surface roughness R _ab may be more preferably 3.2 nm or more, and even more preferably 3.4 nm or more. When the surface roughness R _ab is within the above numerical range, particularly below the above upper limit, it is possible to achieve good electromagnetic conversion characteristics in addition to improved handling properties.

According to the present technology, the magnetic recording medium is preferably an elongated magnetic recording medium, and can be, for example, a magnetic recording tape (particularly an elongated magnetic recording tape).

A magnetic recording medium according to the present technology may include other layers in addition to the magnetic layer, nonmagnetic layer, and base layer. The other layers may be selected as appropriate depending on the type of magnetic recording medium. The magnetic recording medium according to the present technology may be, for example, a coating-type magnetic recording medium or a vacuum thin-film type magnetic recording medium.

A magnetic recording medium according to the present technology may have, for example, at least one data band and at least two servo bands, preferably a plurality of data bands and a plurality of servo bands. The number of data bands may be for example 2 to 10, in particular 3 to 6, more particularly 4 or 5. The number of servo bands may be, for example, from 3 to 11, in particular from 4 to 7, and more particularly from 5 to 6. These servo bands and data bands may be arranged, for example, so as to extend in the longitudinal direction of a long magnetic recording medium (particularly a magnetic recording tape), particularly so as to be substantially parallel to each other. The data band and the servo band may be provided on the magnetic layer. An example of a magnetic recording medium having a data band and a servo band as described above is a magnetic recording tape conforming to the LTO (Linear Tape-Open) standard. That is, the magnetic recording medium according to the present technology may be a magnetic recording tape according to the LTO standard. For example, a magnetic recording medium according to the present technology may be a magnetic recording tape conforming to LTO8 or later standards (eg, LTO9, LTO10, LTO11, or LTO12).
The width of the elongated magnetic recording medium (especially magnetic recording tape) according to the present technology is, for example, 5 mm to 30 mm, particularly 7 mm to 25 mm, more particularly 10 mm to 20 mm, and even more particularly 11 mm to 19 mm. It can be. The length of a long magnetic recording medium (particularly a magnetic recording tape) can be, for example, 500 m to 1500 m. For example, the tape width according to the LTO8 standard is 12.65 mm and the length is 960 m.

(1) Structure of Magnetic Recording Medium As explained with reference to FIG. A base material 2), an underlayer (non-magnetic layer 3) provided on one main surface of the base layer, a magnetic layer or recording layer (magnetic layer 4) provided on the underlayer, and the base layer. A back layer (back layer 5) provided on the other main surface. In the following, of both principal surfaces of the magnetic recording medium, the surface on which the magnetic layer is provided is referred to as the magnetic surface, and the surface opposite to the magnetic surface (the surface on which the back layer is provided) is referred to as the back surface. It's called a mask.

The magnetic recording medium has a long shape, and is run in the longitudinal direction during recording and reproduction. Further, the magnetic recording medium may be configured to be able to record a signal at a shortest recording wavelength of preferably 100 nm or less, more preferably 75 nm or less, even more preferably 60 nm or less, particularly preferably 50 nm or less, for example, the shortest recording wavelength can be used in a recording/reproducing device within the above range. This recording/reproducing device may include a ring-shaped head as the recording head. The recording track width is, for example, 2 μm or less.

(2) Explanation of each layer (base layer)
The base layer can function as a support for the magnetic recording medium, and can be, for example, a flexible elongated nonmagnetic substrate, particularly a nonmagnetic film. The thickness of the base layer may be, for example, 2 μm or more and 8 μm or less, preferably 2.2 μm or more and 7 μm or less, more preferably 2.5 μm or more and 6 μm or less, and even more preferably 2.6 μm or more and 5 μm or less. . The base layer may include, for example, at least one of polyester resins, polyolefin resins, cellulose derivatives, vinyl resins, aromatic polyetherketone resins, and other polymer resins. When the base layer contains two or more of the above materials, the two or more materials may be mixed, copolymerized, or laminated.

Examples of the polyester resin include PET (polyethylene terephthalate), PEN (polyethylene naphthalate), PBT (polybutylene terephthalate), PBN (polybutylene naphthalate), PCT (polycyclohexylene dimethylene terephthalate), and PEB (polyethylene terephthalate). p-oxybenzoate), and polyethylene bisphenoxycarboxylate, or a mixture of two or more thereof. According to preferred embodiments of the present technology, base layer 11 may be formed from PET or PEN.

The polyolefin resin may be, for example, one or a mixture of two or more of PE (polyethylene) and PP (polypropylene).

The cellulose derivative may be, for example, one or a mixture of two or more of cellulose diacetate, cellulose triacetate, CAB (cellulose acetate butyrate), and CAP (cellulose acetate propionate).

The vinyl resin may be, for example, one or a mixture of two or more of PVC (polyvinyl chloride) and PVDC (polyvinylidene chloride).

The aromatic polyetherketone resin is, for example, one or two of PEK (polyetherketone), PEEK (polyetheretherketone), PEKK (polyetherketoneketone), and PEEKK (polyetheretherketoneketone). It may be a mixture of more than one species. According to a preferred embodiment of the present technology, the base layer may be formed from PEEK.

The other polymer resins include, for example, PA (polyamide, nylon), aromatic PA (aromatic polyamide, aramid), PI (polyimide), aromatic PI (aromatic polyimide), PAI (polyamideimide), aromatic PAI (aromatic polyamideimide), PBO (polybenzoxazole, e.g. Zylon (registered trademark)), polyether, polyether ester, PES (polyether sulfone), PEI (polyetherimide), PSF (polysulfone), It may be one or a mixture of two or more of PPS (polyphenylene sulfide), PC (polycarbonate), PAR (polyarylate), and PU (polyurethane).

(magnetic layer)
The magnetic layer can be, for example, a perpendicular recording layer. The magnetic layer may include magnetic powder. In addition to magnetic powder, the magnetic layer may further include, for example, a binder and conductive particles. The magnetic layer may further contain additives such as a lubricant, an abrasive, and a rust preventive, if necessary.

The average thickness _tm of the magnetic layer is preferably 35nm≦ _tm ≦120nm, more preferably 35nm≦ _tm ≦100nm, particularly preferably 35nm≦ _tm ≦90nm. Having the average thickness _tm of the magnetic layer within the above numerical range contributes to improving the electromagnetic conversion characteristics.

The average thickness t _m of the magnetic layer is determined as follows. First, a sample piece is prepared by thinning a magnetic recording medium perpendicular to its main surface, and the cross section of the sample piece is observed using a transmission electron microscope (TEM) under the following conditions. conduct.
Equipment: TEM (H9000NAR manufactured by Hitachi)
Acceleration voltage: 300kV
Magnification: 100,000 times Next, using the obtained TEM image, measure the thickness of the magnetic layer at at least 10 points in the longitudinal direction of the magnetic recording medium. ) and the average thickness of the magnetic layer is t _m (nm).

The magnetic layer is preferably a vertically oriented magnetic layer. In this specification, vertical alignment means that the squareness ratio S1 measured in the longitudinal direction (running direction) of the magnetic recording medium is 35% or less. The method for measuring the squareness ratio S1 will be explained separately below.
Note that the magnetic layer may be an in-plane oriented (longitudinally oriented) magnetic layer. That is, the magnetic recording medium may be a horizontal recording type magnetic recording medium. However, from the standpoint of achieving high recording density, vertical alignment is more preferable.

(Magnetic powder)
Examples of magnetic particles constituting magnetic powder contained in the magnetic layer include epsilon iron oxide (ε iron oxide), gamma hematite, magnetite, chromium dioxide, cobalt-coated iron oxide, hexagonal ferrite, barium ferrite (BaFe), and Co ferrite. , strontium ferrite, and metal, but are not limited to these. The magnetic powder may be one type of these or a combination of two or more types. Particularly preferably, the magnetic powder may include epsilon iron oxide magnetic powder, barium ferrite magnetic powder, cobalt ferrite magnetic powder, or strontium ferrite magnetic powder. Note that the ε iron oxide may contain Ga and/or Al. These magnetic particles may be appropriately selected by those skilled in the art based on factors such as the method of manufacturing the magnetic layer, the specifications of the tape, and the functions of the tape.

The average particle size (average maximum particle size) D of the magnetic powder is preferably 22 nm or less, more preferably 8 nm or more and 22 nm or less, and even more preferably 10 nm or more and 20 nm or less.

The average particle size D of the above magnetic powder is determined as follows. First, a magnetic recording medium to be measured is processed using the FIB (Focused Ion Beam) method or the like to produce a thin piece, and a cross section of the thin piece is observed using a TEM. Next, 500 ε iron oxide particles are randomly selected from the taken TEM photograph, the maximum particle size d _max of each particle is measured, and the particle size distribution of the maximum particle size d _max of the magnetic powder is determined. Here, the "maximum particle size d _max " means the so-called maximum Feret diameter, and specifically, the distance between two parallel lines drawn from any angle so as to be in contact with the contour of the ε iron oxide particle. The largest of these. Thereafter, the median diameter (50% diameter, D50) of the maximum particle size d _max is determined from the particle size distribution of the determined maximum particle size d _max , and this is defined as the average particle size (average maximum particle size) D of the magnetic powder.

The shape of the magnetic particles depends on the crystal structure of the magnetic particles. For example, BaFe and strontium ferrite can be hexagonal plate-shaped. ε iron oxide can be spherical. Cobalt ferrite can be cubic. The metal can be spindle-shaped. These magnetic particles are oriented during the manufacturing process of magnetic recording media.

According to one preferred embodiment of the present technology, the magnetic powder may preferably include powder of nanoparticles containing ε iron oxide (hereinafter referred to as "ε iron oxide particles"). Epsilon iron oxide particles can obtain high coercive force even in fine particles. Preferably, the ε iron oxide contained in the ε iron oxide particles is preferentially crystallized in the thickness direction (perpendicular direction) of the magnetic recording medium.

The ε iron oxide particles have a spherical or nearly spherical shape, or a cubic or almost cubic shape. Since the ε iron oxide particles have the shape described above, when ε iron oxide particles are used as the magnetic particles, the thickness of the medium is smaller than when hexagonal plate-shaped barium ferrite particles are used as the magnetic particles. The contact area between particles in the direction can be reduced, and aggregation of particles can be suppressed. Therefore, it is possible to improve the dispersibility of the magnetic powder and obtain a better SNR (Signal-to-Noise Ratio).

The ε iron oxide particles have a core-shell type structure. Specifically, as shown in FIG. 12, the ε iron oxide particles include a core portion 121 and a two-layer shell portion 122 provided around the core portion 121. The two-layer shell portion 122 includes a first shell portion 122a provided on the core portion 121 and a second shell portion 122b provided on the first shell portion 22a.

The core portion 121 contains ε iron oxide. The ε-iron oxide contained in the core portion 121 preferably has ε-Fe ₂ O ₃ crystal as its main phase, and more preferably consists of single-phase ε-Fe ₂ O ₃ .

The first shell portion 122a covers at least a portion of the periphery of the core portion 121. Specifically, the first shell portion 122a may partially cover the periphery of the core portion 121, or may cover the entire periphery of the core portion 121. From the viewpoint of ensuring sufficient exchange coupling between the core part 121 and the first shell part 122a and improving magnetic properties, it is preferable that the entire surface of the core part 121 be covered.

The first shell portion 122a is a so-called soft magnetic layer, and may include a soft magnetic material such as α-Fe, Ni-Fe alloy, or Fe-Si-Al alloy. α-Fe may be obtained by reducing ε iron oxide contained in the core portion 21.

The second shell portion 122b is an oxide film serving as an oxidation prevention layer. The second shell portion 122b may include alpha iron oxide, aluminum oxide, or silicon oxide. The α-iron oxide may include at least one type of iron oxide among, for example, Fe ₃ O ₄ , Fe ₂ O ₃ , and FeO. When the first shell portion 122a includes α-Fe (soft magnetic material), α-iron oxide may be obtained by oxidizing α-Fe contained in the first shell portion 122a.

Since the ε iron oxide particles have the first shell portion 122a as described above, thermal stability can be ensured, thereby maintaining the coercive force Hc of the core portion 121 alone at a large value and/or ε The coercive force Hc of the iron oxide particles (core-shell particles) as a whole can be adjusted to a coercive force Hc suitable for recording. In addition, since the ε iron oxide particles have the second shell portion 122b as described above, the ε iron oxide particles are exposed to the air during and before the manufacturing process of the magnetic recording medium, and rust occurs on the particle surface. It is possible to suppress the deterioration of the properties of the ε iron oxide particles due to the occurrence of the above. Therefore, deterioration of the characteristics of the magnetic recording medium can be suppressed.

As shown in FIG. 13, the ε iron oxide particles may have a shell portion 123 having a single layer structure. In this case, the shell portion 123 has the same configuration as the first shell portion 122a. However, from the viewpoint of suppressing the deterioration of the characteristics of the epsilon iron oxide particles, it is more preferable that the epsilon iron oxide particles have a shell portion 122 having a two-layer structure.

The ε iron oxide particles may contain an additive instead of having a core-shell structure, or may have a core-shell structure and contain an additive. In these cases, part of the Fe in the ε iron oxide particles is replaced by the additive. When the epsilon iron oxide particles contain an additive, the coercive force Hc of the entire epsilon iron oxide particles can be adjusted to a coercive force Hc suitable for recording, so that ease of recording can be improved. The additive is a metal element other than iron, preferably a trivalent metal element, more preferably one or more selected from the group consisting of aluminum (Al), gallium (Ga), and indium (In).
Specifically, the ε-iron oxide containing additives is a ε-Fe _2-x M _x O ₃ crystal (where M is a metal element other than iron, preferably a trivalent metal element, more preferably Al , Ga, and In. x is, for example, 0<x<1).

According to another preferred embodiment of the present technology, the magnetic powder may be barium ferrite (BaFe) magnetic powder. Barium ferrite magnetic powder includes magnetic particles of iron oxide having barium ferrite as a main phase (hereinafter referred to as "barium ferrite particles"). Barium ferrite magnetic powder has high reliability in data recording, with its coercive force not decreasing even in high-temperature and humid environments. From this point of view, barium ferrite magnetic powder is preferable as the magnetic powder.

The average particle size of the barium ferrite magnetic powder is 50 nm or less, more preferably 10 nm or more and 40 nm or less, and even more preferably 12 nm or more and 25 nm or less.

When the magnetic layer contains barium ferrite magnetic powder as magnetic powder, it is preferable that the average thickness t _m [nm] of the magnetic layer is 35 nm≦t _m ≦100 nm. Further, the coercive force Hc measured in the thickness direction (perpendicular direction) of the magnetic recording medium is preferably 160 kA/m or more and 280 kA/m or less, more preferably 165 kA/m or more and 275 kA/m or less, and even more preferably 170 kA/m. 270 kA/m or less.

According to yet another preferred embodiment of the present technology, the magnetic powder may be a cobalt ferrite magnetic powder. The cobalt ferrite magnetic powder includes magnetic particles of iron oxide having cobalt ferrite as a main phase (hereinafter referred to as "cobalt ferrite magnetic particles"). Preferably, the cobalt ferrite magnetic particles have uniaxial anisotropy. The cobalt ferrite magnetic particles have, for example, a cubic shape or a substantially cubic shape. Cobalt ferrite is cobalt ferrite containing Co. In addition to Co, the cobalt ferrite may further contain one or more elements selected from the group consisting of Ni, Mn, Al, Cu, and Zn.

Cobalt ferrite has, for example, an average composition represented by the following formula (1).
C _x M _y Fe ₂ O _z ...(1)
(However, in formula (1), M is, for example, one or more metals selected from the group consisting of Ni, Mn, Al, Cu, and Zn. x is 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 3≦z≦ The value is within the range of 4. Part of Fe may be substituted with another metal element.)

The average particle size of the cobalt ferrite magnetic powder is preferably 25 nm or less, more preferably 23 nm or less. The coercive force Hc of the cobalt ferrite magnetic powder is preferably 2,500 Oe or more, more preferably 2,600 Oe or more and 3,500 Oe or less.

According to yet another preferred embodiment of the present technology, the magnetic powder may include powder of nanoparticles containing hexagonal ferrite (hereinafter referred to as "hexagonal ferrite particles"). The hexagonal ferrite particles have, for example, a hexagonal plate shape or a substantially hexagonal plate shape. The hexagonal ferrite may preferably contain 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.
More specifically, hexagonal ferrite may have an average composition represented by the general formula MFe ₁₂ O ₁₉ . Here, 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. Furthermore, M may 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, a part of Fe may be substituted with another metal element.
When the magnetic powder includes powder of hexagonal ferrite particles, the average particle size of the magnetic powder is preferably 50 nm or less, more preferably 10 nm or more and 40 nm or less, and even more preferably 15 nm or more and 30 nm or less.

(binder)
As the binder, a resin having a structure obtained by imparting a crosslinking reaction to a polyurethane resin, a vinyl chloride resin, or the like is preferable. However, the binder is not limited to these, and other resins may be appropriately blended depending on the physical properties required for the magnetic recording medium. The resin to be blended is not particularly limited as long as it is a resin commonly used in coating type magnetic recording media.

Examples of the binder include polyvinyl chloride, polyvinyl acetate, vinyl chloride-vinyl acetate copolymer, vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic acid ester-acrylonitrile copolymer. , acrylic ester-vinyl chloride-vinylidene chloride copolymer, vinyl chloride-acrylonitrile copolymer, acrylic ester-acrylonitrile copolymer, acrylic ester-vinylidene chloride copolymer, methacrylic ester-vinylidene chloride copolymer , methacrylic acid ester-vinyl chloride copolymer, methacrylic acid ester-ethylene copolymer, polyvinyl fluoride, vinylidene chloride-acrylonitrile copolymer, acrylonitrile-butadiene copolymer, polyamide resin, polyvinyl butyral, cellulose derivative (cellulose) Examples include acetate butyrate, cellulose diacetate, cellulose triacetate, cellulose propionate, nitrocellulose), styrene-butadiene copolymers, polyester resins, amino resins, and synthetic rubbers.

Further, a thermosetting resin or a reactive resin may be used as the binder, and examples thereof include phenol resin, epoxy resin, urea resin, melamine resin, alkyd resin, silicone resin, polyamine resin, and urea formaldehyde resin.

In addition, polar functional groups such as -SO ₃ M, -OSO ₃ M, -COOM, and P=O(OM) ₂ are introduced into each of the above-mentioned binders for the purpose of improving the dispersibility of the magnetic powder. You can leave it there. Here, M in the formula is a hydrogen atom or an alkali metal such as lithium, potassium, and sodium.

Further, examples of the polar functional group include side chain types having terminal groups of -NR1R2 and -NR1R2R3 ⁺ X ^- , and main chain types having >NR1R2 ⁺ X ^- . Here, in the formula, R1, R2, and R3 are hydrogen atoms or hydrocarbon groups, and X ^- is a halogen element ion such as fluorine, chlorine, bromine, or iodine, or an inorganic or organic ion. Further, examples of the polar functional group include -OH, -SH, -CN, and epoxy group.

(Additive)
The magnetic layer contains aluminum oxide (α, β, or γ alumina), chromium oxide, silicon oxide, diamond, garnet, emery, boron nitride, titanium carbide, silicon carbide, titanium carbide, titanium oxide ( It may further contain rutile type or anatase type titanium oxide).

(Nonmagnetic layer)
The nonmagnetic layer contains nonmagnetic powder and a binder as main components. The nonmagnetic layer is also called an underlayer. The above description regarding the binder contained in the magnetic layer also applies to the binder contained in the nonmagnetic layer. The nonmagnetic layer may further contain at least one additive selected from conductive particles, a lubricant, a hardening agent, a rust preventive, and the like, as necessary.

The average thickness t _n of the nonmagnetic layer is 1.0 μm or less, more preferably 0.9 μm or less, and even more preferably t _n ≦0.7 μm. The average thickness t _n of the nonmagnetic layer is, for example, 0.01 μm or more, preferably 0.02 μm or more, more preferably 0.4 μm or more, and particularly preferably 0.5 μm or more. Note that the average thickness t _n of the nonmagnetic layer is determined in the same manner as the average thickness t _m of the magnetic layer. However, the magnification of the TEM image is adjusted as appropriate depending on the thickness of the nonmagnetic layer. Having the average thickness _tn of the nonmagnetic layer within the above numerical range contributes to an increase in Δw, and further makes the magnetic recording medium suitable for use in a recording/reproducing device that adjusts tension in the longitudinal direction. .

(Non-magnetic powder)
The nonmagnetic powder contained in the nonmagnetic layer may include, for example, at least one selected from inorganic particles and organic particles. 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, one or a combination of two or more selected from metals, metal oxides, metal carbonates, metal sulfates, metal nitrides, metal carbides, and metal sulfides. More specifically, the inorganic particles may be one or more selected from, for example, iron oxyhydroxide, hematite, titanium oxide, and carbon black. Examples of the shape of the non-magnetic powder include various shapes such as acicular, spherical, cubic, and plate-like shapes, but are not particularly limited to these shapes.
The nonmagnetic powder contained in the nonmagnetic layer preferably contains Fe group-containing nonmagnetic particles, more preferably Fe group-containing nonmagnetic inorganic particles. Examples of Fe group-containing nonmagnetic particles include iron oxyhydroxide (particularly goethite) and hematite, and one or a combination of two or more of these may be used as the nonmagnetic powder. can.
The non-magnetic powder may be, for example, a combination of hematite and carbon black. The mass ratio of hematite and carbon black can be, for example, from 2:1 to 20:1, preferably from 5:1 to 15:1, more preferably from 8:1 to 12:1.
The particle volume of the Fe-based nonmagnetic particles contained in the nonmagnetic layer is preferably 4.0×10 ⁻⁵ μm ³ or less, more preferably 3.0×10 ⁻⁵ μm ³ or less, and 2 It is even more preferable that it is .0×10 ⁻⁵ μm ³ or less, and even more preferably that it is 1.0×10 ⁻⁵ μm ³ or less. The thinner the non-magnetic layer is, the worse the surface properties on the magnetic layer side of the magnetic recording medium tend to be. However, the smaller the particle volume of the non-magnetic powder contained in the non-magnetic layer is, the more the surface properties are suppressed. In addition, Δw can be made larger.

Hereinafter, an example of a method for measuring the particle volume of Fe-based nonmagnetic particles will be explained step by step.
1. As sample pretreatment, thinning is performed along the longitudinal direction of the magnetic recording tape by the FIB method (μ-sampling method).
2. A cross section of the obtained thin sample including the base layer, nonmagnetic layer, and magnetic layer is observed. This observation is performed using a transmission electron microscope (Hitachi High Technologies H-9500) under conditions of an accelerating voltage of 300 kV and a total magnification of 250,000 times.
3. In the obtained cross-sectional TEM image, 50 Fe-based nonmagnetic particles are identified using a microelectron diffraction method on the particles contained in the nonmagnetic layer. This microelectron diffraction method is performed using a transmission electron microscope (JEM-ARM200F manufactured by JEOL Ltd.) under conditions of an accelerating voltage of 200 kV, a camera length of 0.8 m, and a beam diameter of approximately 1 nmΦ.
4. Using the 50 Fe-based non-magnetic particles specified as above, the average particle volume of the Fe-based non-magnetic particles is determined. The average particle volume V _ave of the Fe-based nonmagnetic particles can be calculated as V _ave = (π/6) x DS _ave ² x DL _ave .
Therefore, first, the major axis length DL and minor axis length DS of each Fe-based nonmagnetic particle are measured. Here, the long axis length DL means the maximum distance between two parallel lines drawn from any angle so as to be in contact with the contour of the particle (so-called maximum Feret diameter). On the other hand, the short axis length DS means the maximum length of the particle in the direction perpendicular to the long axis of the particle.
Next, the average long axis length DL _ave is determined by simply averaging (arithmetic mean) the measured long axis lengths DL of the 50 Fe-based nonmagnetic particles. The determined average major axis length DL _ave is also called the average particle size of the Fe-based nonmagnetic particles. Furthermore, the average short axis length DS _ave is determined by simply averaging (arithmetic mean) the short axis lengths DS of the 50 measured Fe-based nonmagnetic particles.
Finally, V _ave is determined by substituting the average major axis length DL _ave and average minor axis length DS _ave determined above into the formula for calculating V _ave .

(back layer)
The back layer may include a binder and non-magnetic powder. The back layer may contain various additives such as a lubricant, a curing agent, and an antistatic agent, if necessary. The explanation given regarding the binder and non-magnetic powder contained in the underlayer described above also applies to the binder and non-magnetic powder contained in the back layer.

The average particle size of the inorganic particles contained in the back layer 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 inorganic particles is determined in the same manner as the average particle size D of the magnetic powder described above.

The average thickness t _b of the back layer is preferably t _b ≦0.6 μm. By having the average thickness t _b of the back layer within the above range, even when the average thickness t _T of the magnetic recording medium is set to t _T ≦5.5 μm, the thickness of the underlayer and base layer can be kept thick, Thereby, running stability of the magnetic recording medium within the recording/reproducing apparatus can be maintained.

The average thickness t _b of the back layer is determined as follows. First, a 1/2 inch wide magnetic recording medium is prepared and cut into a length of 250 mm to produce a sample. Next, using a laser holo gauge manufactured by Mitutoyo as a measuring device, measure the thickness of the sample at five or more different locations, and simply average (arithmetic mean) these measured values to obtain the average value t _T [μm] Calculate. Next, after removing the back layer of the sample with a solvent such as MEK (methyl ethyl ketone) or diluted hydrochloric acid, measure the thickness of the sample at 5 or more different points using the laser hologage again, and record the measured values. The average value t _B [μm] is calculated by simply averaging (arithmetic mean). Thereafter, the average thickness t _b (μm) of the back layer is determined from the following formula.
t _b [μm] = t _T [μm] - t _B [μm]

(3) Physical properties and structure (average thickness _tT of magnetic recording medium)
The average thickness t _T of the magnetic recording medium is t _T ≦5.5 μm. When the average thickness t _T of the magnetic recording medium is t _T ≦5.5 μm, the recording capacity that can be recorded in one data cartridge can be increased compared to the conventional one. The lower limit of the average thickness _tT of the magnetic recording medium is not particularly limited, but is, for example, 3.5 [μm]≦ _tT .

The average thickness t _T of the magnetic recording medium is determined by the method for measuring the average value t _T described in the method for measuring the average thickness t _b of the back layer.

(Dimension change amount Δw)
The amount of dimensional change Δw [ppm/N] in the width direction of the magnetic recording medium with respect to the change in tension in the longitudinal direction of the magnetic recording medium is 660 ppm/N≦Δw, preferably 670 ppm/N≦Δw, and more preferably 680 ppm. /N≦Δw, more preferably 700 ppm/N≦Δw, even more preferably 750 ppm/N≦Δw, particularly preferably 800 ppm/N≦Δw. If the dimensional change amount Δw is Δw<660 ppm/N, there is a possibility that it will be difficult to suppress the width change by adjusting the tension in the longitudinal direction by the recording/reproducing device. The upper limit of the dimensional change amount Δw is not particularly limited, but for example, Δw≦1700000ppm/N, preferably Δw≦20000ppm/N, more preferably Δw≦8000ppm/N, even more preferably Δw≦5000ppm/N. , Δw≦4000ppm/N, Δw≦3000ppm/N, or Δw≦2000ppm/N.
Those skilled in the art can appropriately set the dimensional change amount Δw. For example, the dimensional change amount Δw can be set to a desired value by selecting the thickness of the base layer and/or the material of the base layer. Further, the dimensional change amount Δw may be set to a desired value, for example, by adjusting the stretching strength in the longitudinal and lateral directions of the film constituting the base layer. For example, by stretching more strongly in the width direction, Δw decreases, and on the contrary, by increasing stretching in the longitudinal direction, Δw increases.

（但し、式中、Ｄ（０．２Ｎ）及びＤ（１．０Ｎ）はそれぞれ、サンプル１０Ｓの長手方向に０．２Ｎ及び１．０Ｎに荷重をかけたときのサンプル１０Ｓの幅を示す。） The amount of dimensional change Δw is determined as follows. First, a 1/2 inch wide magnetic recording medium is prepared and cut into a length of 250 mm to produce a sample 10S. Next, a load of 0.2N, 0.6N, and 1.0N is applied in the longitudinal direction of the sample 10S in the order of 0.2N, 0.6N, and 1.0N, and the width of the sample 10S under the loads of 0.2N, 0.6N, and 1.0N is measured. Subsequently, the amount of dimensional change Δw is determined from the following formula. Note that the measurement with a load of 0.6N was performed in order to confirm that there are no abnormalities in the measurement (especially to confirm that these three measurement results are linear). The measurement results are not used in the following equations.

(However, in the formula, D (0.2N) and D (1.0N) indicate the width of the sample 10S when a load of 0.2N and 1.0N is applied in the longitudinal direction of the sample 10S, respectively.)

The width of the sample 10S when each load is applied is measured as follows. First, a measuring device shown in FIG. 14 incorporating a digital dimension measuring device LS-7000 manufactured by Keyence Corporation is prepared as a measuring device, and the sample 10S is set in this measuring device. Specifically, one end of the elongated sample (magnetic recording medium) 10S is fixed by the fixing part 231. Next, as shown in FIG. 14, the sample 10S is placed on five substantially cylindrical and rod-shaped support members 232. The sample 10S is placed on the five support members 232 so that its back surface is in contact with the five support members 232. The five supporting members 232 (particularly their surfaces) are all made of stainless steel SUS304, and have a surface roughness Rz (maximum height) of 0.15 μm to 0.3 μm.

The arrangement of the five rod-shaped support members 232 will be explained with reference to FIG. 15. As shown in FIG. 15, the sample 10S is placed on five support members 232. The five supporting members 232 will be referred to as "first supporting member", "second supporting member", "third supporting member" (having slit 232A), and "fourth supporting member" from the one closest to the fixed part 231. and the “fifth support member” (closest to the weight 233). The diameter of these five support members is 7 mm. The distance d ₁ between the first support member and the second support member (in particular the distance between the centers of these support members) is 20 mm. The distance _d2 between the second support member and the third support member is 30 mm. The distance _d3 between the third support member and the fourth support member is 30 mm. The distance _d4 between the fourth support member and the fifth support member is 20 mm. In addition, these three support members are arranged so that the portion of the sample 10S that rests between the second support member, the third support member, and the fourth support member forms a plane substantially perpendicular to the direction of gravity. is located. Further, the sample 10S is arranged so that the first support member and the second support member form an angle of θ ₁ =30° with respect to the substantially perpendicular plane between the first support member and the second support member. is located. Further, the sample 10S is configured such that the fourth support member and the fifth support member form an angle of θ ₂ =30° with respect to the substantially perpendicular plane between the fourth support member and the fifth support member. is located.
Further, among the five support members 232, the third support member is fixed so as not to rotate, but the other four support members are all rotatable.

The sample 10S is held on the support member 232 so as not to move in the width direction of the sample 10S. Note that a slit 232A is provided in the support member 232 located between the light emitter 234 and the light receiver 235 and approximately at the center of the fixing portion 231 and the portion to which a load is applied. Light L is irradiated from the light emitter 234 to the light receiver 235 through the slit 232A. The slit width of the slit 232A is 1 mm, and the light L can pass through the width without being blocked by the frame of the slit 232A.

Subsequently, after housing the measuring device in a chamber controlled in a constant environment at a temperature of 25° C. and a relative humidity of 50%, a weight 233 for applying a load of 0.2 N is attached to the other end of the sample 10S. 10S is placed in the above environment for 2 hours. After 2 hours, the width of sample 10S is measured. Next, the weight for applying a load of 0.2N is changed to a weight for applying a load of 0.6N, and 5 minutes after the change, the width of the sample 10S is measured. Finally, the weight was changed to apply a load of 1.0 N, and 5 minutes after the change, the width of the sample 10S was measured.
As described above, by adjusting the weight of the weight 233, the load applied in the longitudinal direction of the sample 10S can be changed. With each load attached, light L is irradiated from the light emitter 234 toward the light receiver 235, and the width of the sample 10S to which the load is applied in the longitudinal direction is measured. The measurement of the width is performed in a state where the sample 10S is not curled. The light emitter 234 and the light receiver 235 are included in the digital dimension measuring instrument LS-7000.

(Temperature expansion coefficient α)
The thermal expansion coefficient α [ppm/°C] of the magnetic recording medium is preferably 5.5 ppm/°C≦α≦9 ppm/°C, more preferably 5.9 ppm/°C≦α≦8 ppm/°C. When the temperature expansion coefficient α is within the above range, changes in the width of the magnetic recording medium can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic recording medium by the recording/reproducing device.

（但し、式中、Ｄ（４５℃）及びＤ（１０℃）はそれぞれ、温度４５℃及び１０℃におけるサンプル１０Ｓの幅を示す。） The temperature expansion coefficient α is determined as follows. First, a sample 10S was prepared in the same manner as in the method for measuring the amount of dimensional change Δw, and the sample 10S was set in the same measuring device as in the method for measuring the amount of dimensional change Δw. Housed in a chamber with a controlled environment. Next, a load of 0.2 N is applied in the longitudinal direction of the sample 10S, and the sample 10S is left in the above environment for 2 hours. After that, while maintaining the relative humidity of 24%, the temperature was changed in the order of 45°C, 29°C, and 10°C, and the width of sample 10S at 45°C, 29°C, and 10°C was measured, and the temperature was calculated from the following formula. Find the expansion coefficient α. Measurements at these temperatures are taken 2 hours after reaching each temperature. The measurement at a temperature of 29°C is carried out to confirm that there are no abnormalities in the measurement (especially to confirm that these three measurement results are linear). The measurement results are not used in the following equations.

(However, in the formula, D (45°C) and D (10°C) indicate the width of sample 10S at temperatures of 45°C and 10°C, respectively.)

(humidity expansion coefficient β)
The humidity expansion coefficient β [ppm/%RH] of the magnetic recording medium is preferably β≦5.5ppm/%RH, more preferably β≦5.2ppm/%RH, and even more preferably β≦5. .0 ppm/%RH. When the humidity expansion coefficient β is within the above range, changes in the width of the magnetic recording medium can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic recording medium by the recording/reproducing device.

（但し、式中、Ｄ（８０％）、Ｄ（１０％）はそれぞれ、温度８０％、１０％におけるサンプル１０Ｓの幅を示す。） The humidity expansion coefficient β is determined as follows. First, a sample 10S was prepared in the same manner as the method for measuring the amount of dimensional change Δw, and the sample 10S was set in a measuring device similar to that used for measuring the amount of dimensional change Δw. Housed in a chamber with a controlled environment. Next, a load of 0.2 N is applied in the longitudinal direction of the sample 10S, and the sample is placed in the above environment for 2 hours. Then, while maintaining the temperature at 29°C, change the relative humidity in the order of 80%, 24%, and 10%, measure the width of sample 10S at 80%, 24%, and 10%, and calculate the humidity expansion using the following formula. Find the coefficient β. Measurements at these humidity levels are taken immediately after each humidity level is reached. Note that the measurement at 24% humidity is performed to confirm whether any abnormality has occurred in the measurement, and the measurement result is not used in the following equation.

(However, in the formula, D (80%) and D (10%) indicate the width of sample 10S at temperatures of 80% and 10%, respectively.)

(Poisson's ratio ρ)
The Poisson's ratio ρ of the magnetic recording medium is preferably 0.25≦ρ, more preferably 0.29≦ρ, and even more preferably 0.3≦ρ. When Poisson's ratio ρ is within the above range, it becomes easier to change the width of the magnetic recording medium by adjusting the tension in the longitudinal direction of the magnetic recording medium by the recording/reproducing device.

Poisson's ratio ρ is obtained as follows. First, a 1/2 inch wide magnetic recording medium is prepared, a sample is cut out to a length of 150 mm, and a mark of 6 mm x 6 mm is attached to the center of the sample. Next, both ends of the sample in the longitudinal direction are chucked so that the distance between the chucks is 100 mm, an initial load of 2N is applied, the length of the mark in the longitudinal direction of the sample at that time is taken as the initial length, and the width of the sample is Set the width of the direction mark as the initial width. Next, the sample was pulled at a tensile speed of 0.5 mm/min using an Instron type universal tensile tester, and a Keyence image sensor was used to measure the length of the mark in the longitudinal direction of the sample and the width of the mark in the width direction of the sample. Measure the amount of dimensional change. After that, Poisson's ratio ρ is determined from the following formula.

(Longitudinal elastic limit value σ _MD )
The longitudinal elastic limit value σ _MD [N] of the magnetic recording medium is preferably 0.7N≦σ _MD , more preferably 0.75N≦σ _MD , even more preferably 0.8N≦σ _MD It can be. When the elastic limit value σ _MD is within the above range, changes in the width of the magnetic recording medium can be further suppressed by adjusting the tension in the longitudinal direction of the magnetic recording medium by the recording/reproducing device. Further, it becomes easier to control the drive side. The upper limit of the elastic limit value σ _MD in the longitudinal direction of the magnetic recording medium is not particularly limited, but is, for example, σ _MD ≦5.0N. Preferably, the elastic limit value σ _MD does not depend on the speed V at which the elastic limit measurement is performed. Since the elastic limit value σ _MD does not depend on the above-mentioned speed V, magnetic recording can be performed effectively without being affected by the traveling speed of the magnetic recording medium in the recording/reproducing device, the tension adjustment speed of the recording/reproducing device, and its responsiveness. This is because changes in the width of the medium can be suppressed. The elastic limit value σ _MD is set to a desired value by, for example, selection of the curing conditions of the underlayer, magnetic layer, and back layer, and/or selection of the material of the base layer 11. For example, the longer the curing time or the higher the curing temperature of the base layer forming paint, the magnetic layer forming paint, and the back layer forming paint, the more the reaction between the binder and curing agent contained in each of these paints accelerates. . This improves the elastic characteristics and improves the elastic limit value σ _MD .

The elastic limit value σ _MD is determined as follows. First, prepare a 1/2 inch wide magnetic recording medium, cut it into a length of 150 mm to make a sample, and place the sample in a universal tensile tester so that the distance between chucks λ ₀ is λ ₀ = 100 mm. Chuck both longitudinal ends. Next, the sample is pulled at a pulling speed of 0.5 mm/min, and the load σ (N) with respect to the inter-chuck distance λ (mm) is continuously measured. Subsequently, the relationship between Δλ (%) and σ (N) is graphed using the obtained data of λ (mm) and σ (N). However, Δλ (%) is given by the following formula.
Δλ (%) = ((λ-λ ₀ )/λ ₀ )×100
Next, in the above graph, a region where the graph is a straight line is calculated in the region where σ≧0.2N, and the maximum load σ is set as the elastic limit value σ _MD (N).

(Friction coefficient μ between magnetic surface and back surface)
The friction coefficient μ (hereinafter also referred to as "interlayer friction coefficient μ") between the surface on the magnetic layer side and the surface on the back layer side of the magnetic recording medium is preferably 0.20≦μ≦0.80. , more preferably 0.25≦μ≦0.75. When the friction coefficient μ is within the above range, the handling properties of the magnetic recording medium are improved. For example, when the friction coefficient μ is within the above range, it is possible to suppress winding misalignment when the magnetic recording medium is wound onto a reel (for example, the tape reel 13 in FIG. 1). More specifically, when the friction coefficient μ is too small (for example, when μ<0.20), the magnetic surface of the outermost portion of the magnetic recording medium already wound on the cartridge reel, The interlayer friction between the outside of the magnetic recording medium and the back surface of the newly wound magnetic recording medium is extremely low, and the newly wound magnetic recording medium is the most recently wound magnetic recording medium. It becomes easy to shift from the magnetic surface of the part located on the outer periphery. Therefore, winding misalignment of the magnetic recording medium occurs. On the other hand, if the friction coefficient μ is too large (for example, 0.80<μ), the back surface of the magnetic recording medium that is about to be unwound from the outermost circumference of the drive side reel, and the The interlayer friction between the magnetic surface of the magnetic recording medium still wound around the drive reel becomes extremely high, and the back surface and the magnetic surface become stuck together. Therefore, the operation of the magnetic recording medium toward the cartridge reel becomes unstable, which causes winding misalignment of the magnetic recording medium.

The friction coefficient μ is determined as follows. First, a 1/2 inch wide magnetic recording medium is wound around a 1 inch diameter cylinder with the back side facing up, and the magnetic recording medium is fixed. Next, a 1/2 inch wide magnetic recording medium is brought into contact with this cylinder at an angle of embrace θ (°) = 180° + 1° to 180° - 10° so that the magnetic surface is in contact with the cylinder, and the magnetic recording medium is One end of the medium is connected to a movable strain gauge, and a tension T ₀ =0.6 (N) is applied to the other end. When the movable strain gauge was moved back and forth 8 times at 0.5 mm/s, the strain gauge readings T ₁ (N) to T ₈ (N) on each outward trip were measured, and the average value of T ₄ to T ₈ was calculated. Let it be T _ave (N). Then, calculate the friction coefficient μ from the following formula.

(Surface roughness R _ab of back layer)
The surface roughness of the back layer (that is, the surface roughness of the back surface) R _ab [nm] is preferably 3.0 nm≦R _ab ≦7.3 nm, more preferably 3.0 nm≦R _ab ≦7. 0 nm, more preferably 3.0 nm≦R _ab ≦6.5 nm, even more preferably 3.0 nm≦R _ab ≦6.0 nm. When the surface roughness R _ab of the back layer is within the above range, the handling properties of the magnetic recording medium can be improved. Further, when winding up the magnetic recording medium, the influence on the surface of the magnetic layer can be reduced, and the adverse influence on electromagnetic conversion characteristics can be suppressed. Handlability and electromagnetic conversion characteristics are contradictory characteristics, but a surface roughness R _ab within the above numerical range makes it possible to achieve both.

The surface roughness R _ab of the back surface is determined as follows. First, a 1/2 inch wide magnetic recording medium is prepared and attached to a glass slide with its back surface facing up (that is, the magnetic surface is attached to the slide glass) to form a sample piece. Next, the surface roughness of the back surface of the sample piece was measured using a non-contact roughness meter using optical interference as described below.
Equipment: Non-contact roughness meter using optical interference (Non-contact surface/layer cross-sectional shape measurement system VertScan R5500GL-M100-AC manufactured by Ryoka System Co., Ltd.)
Objective lens: 20x (approximately 237μm x 178μm field of view)
Resolution: 640 points x 480 points
Measurement mode: phase
Wavelength filter: 520nm
Surface correction: Correction using a quadratic polynomial approximation surface After measuring the surface roughness at at least 5 points in the longitudinal direction as described above, each surface roughness is automatically calculated from the surface profile obtained at each position. The average value of the arithmetic mean roughness Sa (nm) is defined as the surface roughness R _ab (nm) of the back surface.

(Coercive force Hc)
The coercive force Hc measured in the thickness direction (perpendicular direction) of the magnetic recording medium is preferably 220 kA/m or more and 310 kA/m or less, more preferably 230 kA/m or more and 300 kA/m or less, and even more preferably 240 kA/m or more and 290 kA. /m or less. When the coercive force Hc is 220 kA/m or more, the coercive force Hc becomes sufficiently large, so that deterioration of magnetization signals recorded in adjacent tracks due to leakage magnetic fields from the recording head can be suppressed. Therefore, better SNR can be obtained. On the other hand, when the coercive force Hc is 310 kA/m or less, saturation recording by the recording head becomes easy, and a better SNR can be obtained.

The above coercive force Hc is determined as follows. First, a measurement sample is cut out from a long magnetic recording medium, and a vibrating sample magnetometer (VSM) is used to measure the entire measurement sample's M- Measure the H loop. Next, the coating film (base layer, magnetic layer, etc.) is wiped off using acetone or ethanol, etc., leaving only the base layer for background correction. Measure the MH loop of the base layer in the thickness direction). Thereafter, the MH loop of the base layer is subtracted from the MH loop of the entire measurement sample to obtain the MH loop after background correction. The coercive force Hc is determined from the obtained MH loop. Note that all of the above MH loop measurements are performed at 25°C. Further, it is assumed that "demagnetizing field correction" is not performed when measuring the MH loop in the thickness direction (perpendicular direction) of the magnetic recording medium.

(Ratio R between coercive force Hc (50) and coercive force Hc (25))
The ratio R (=( Hc(50)/Hc(25))×100) is preferably 95% or more, more preferably 96% or more, even more preferably 97% or more, particularly preferably 98% or more. When the ratio R is 95% or more, the temperature dependence of the coercive force Hc becomes small, and it is possible to suppress deterioration of the SNR in a high-temperature environment.

The above-mentioned coercive force Hc (25) is obtained in the same manner as the method for measuring the above-mentioned coercive force Hc. Further, the above coercive force Hc (50) is obtained in the same manner as the above method for measuring the coercive force Hc, except that the measurement of the MH loop of the measurement sample and the base layer 11 is both carried out at 50°C. .

(Square ratio S1 measured in longitudinal direction)
The squareness ratio S1 measured in the longitudinal direction (running direction) of the magnetic recording medium is preferably 35% or less, more preferably 27% or less, even more preferably 20% or less. When the squareness ratio S1 is 35% or less, the vertical orientation of the magnetic powder becomes sufficiently high, so that a better SNR can be obtained. Therefore, better electromagnetic conversion characteristics can be obtained. Furthermore, the shape of the servo signal is improved, making it easier to control the drive side.
In this specification, the magnetic recording medium being vertically oriented can mean that the squareness ratio S1 of the magnetic recording medium is within the above numerical range (for example, 35% or less). Magnetic recording media according to the present technology are preferably vertically oriented.

The above squareness ratio S1 is determined as follows. First, a measurement sample is cut out from a long magnetic recording medium, and the MH loop of the entire measurement sample corresponding to the longitudinal direction (running direction) of the magnetic recording medium is measured using a VSM. Next, the coating film (base layer, magnetic layer, etc.) is wiped off using acetone or ethanol, etc., leaving only the base layer for background correction. Measure the MH loop of the base layer corresponding to the direction of travel of the base layer. Thereafter, the MH loop of the base layer 11 is subtracted from the MH loop of the entire measurement sample to obtain the MH loop after background correction. The obtained saturation magnetization Ms (emu) and residual magnetization Mr (emu) of the MH loop 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.
Squareness ratio S1 (%) = (Mr/Ms) x 100

(Square ratio S2 measured in the vertical direction)
The squareness ratio S2 measured in the perpendicular direction (thickness direction) of the magnetic recording medium is preferably 65% or more, more preferably 73% or more, and even more preferably 80% or more. When the squareness ratio S2 is 65% or more, the vertical orientation of the magnetic powder becomes sufficiently high, so that a more excellent SNR can be obtained. Therefore, better electromagnetic conversion characteristics can be obtained. Furthermore, the shape of the servo signal is improved, making it easier to control the drive side.
In the specification, the fact that the magnetic recording medium is vertically oriented may mean that the squareness ratio S2 of the magnetic recording medium is within the above numerical range (for example, 65% or more).

The squareness ratio S2 is determined in the same manner as the squareness ratio S1 except that the MH loop is measured in the perpendicular direction (thickness direction) of the magnetic recording medium and the base layer. In the measurement of the squareness ratio S2, "demagnetizing field correction" when measuring the MH loop in the direction perpendicular to the magnetic recording medium is not performed.

The squareness ratios S1 and S2 are, for example, the intensity of the magnetic field applied to the paint for forming a magnetic layer, the time of application of the magnetic field to the paint for forming a magnetic layer, the dispersion state of magnetic powder in the paint for forming a magnetic layer, or the magnetic powder for forming a magnetic layer. The desired value is set by adjusting the concentration of solid content in the paint. Specifically, for example, as the strength of the magnetic field increases, the squareness ratio S1 decreases, whereas the squareness ratio S2 increases. Moreover, as the application time of the magnetic field becomes longer, the squareness ratio S1 becomes smaller, whereas the squareness ratio S2 becomes larger. Further, as the dispersion state of the magnetic powder is improved, the squareness ratio S1 becomes smaller, whereas the squareness ratio S2 becomes larger. Further, as the solid content concentration is lowered, the squareness ratio S1 becomes smaller, whereas the squareness ratio S2 becomes larger. Note that the above adjustment methods may be used alone or in combination of two or more.

(SFD)
In the SFD (Switching Field Distribution) curve of the magnetic recording medium, the peak ratio X/Y between the main peak height X and the sub-peak height Y near zero magnetic field is preferably 3.0 or more, more preferably 5.0. Above, it is still more preferably 7.0 or more, particularly preferably 10.0 or more, and most preferably 20.0 or more (see FIG. 16). When the peak ratio It is possible to suppress the amount contained in it. Therefore, it is possible to suppress the deterioration of the magnetization signals recorded in the adjacent tracks due to the leakage magnetic field from the recording head, so that a better SNR can be obtained. The upper limit of the peak ratio X/Y is not particularly limited, but is, for example, 100 or less.

The above peak ratio X/Y is determined as follows. First, an MH loop after background correction is obtained in the same manner as the method for measuring the coercive force Hc described above. Next, an SFD curve is calculated from the obtained MH loop. A program attached to the measuring device may be used to calculate the SFD curve, or another program may be used. Let "Y" be the absolute value of the point where the calculated SFD curve crosses the Y axis (dM/dH), and let "X" be the height of the main peak seen near the coercive force Hc in the MH loop. Calculate the peak ratio X/Y. Note that the measurement of the MH loop is carried out at 25° C. in the same manner as the method for measuring the coercive force Hc described above. Further, it is assumed that "demagnetizing field correction" is not performed when measuring the MH loop in the thickness direction (perpendicular direction) of the magnetic recording medium.

(activation volume V _act )
The activation volume V _act is preferably 8000 nm ³ or less, more preferably 6000 nm ³ or less, even more preferably 5000 nm ³ or less, particularly preferably 4000 nm ³ or less, most preferably 3000 nm ^{3 or} less. When the activation volume V _act is 8000 nm ³ or less, the magnetic powder is well dispersed, so the bit reversal region can be made steep, and the leakage magnetic field from the recording head prevents recording on adjacent tracks. Deterioration of the magnetization signal can be suppressed. Therefore, there is a possibility that a better SNR cannot be obtained.

The above activation volume V _act is determined by the following formula derived by Street & Woolley.
V _act (nm ³ )=k _B ×T×Χ _irr /(μ ₀ ×Ms×S)
(However, _kB : Boltzmann constant (1.38× ^10-23 J/K), T: temperature (K), _Χirr : irreversible magnetic susceptibility, _μ0 : magnetic permeability of vacuum, S: magnetorheological coefficient, Ms: saturation magnetization (emu/cm ³ ))

The irreversible magnetic susceptibility Χ _irr , the saturation magnetization Ms, and the magnetorheological coefficient S, which are substituted into the above equation, are obtained as follows using VSM. Note that the measurement direction by VSM is the thickness direction (perpendicular direction) of the magnetic recording medium. Further, it is assumed that the measurement by VSM is performed at 25° C. on a measurement sample cut out from a long magnetic recording medium. Further, it is assumed that "demagnetizing field correction" is not performed when measuring the MH loop in the thickness direction (perpendicular direction) of the magnetic recording medium.

(irreversible magnetic susceptibility _Χirr )
The irreversible magnetic susceptibility _Χirr is defined as the slope of the residual magnetization curve (DCD curve) near the residual magnetic force Hr. First, a magnetic field of -1193 kA/m (15 kOe) is applied to the entire magnetic recording medium to return the magnetic field to zero and create a residual magnetization state. Thereafter, a magnetic field of about 15.9 kA/m (200 Oe) is applied in the opposite direction to return the magnet to zero and measure the amount of residual magnetization. Thereafter, a magnetic field that is 15.9 kA/m larger than the previously applied magnetic field is applied and the measurement is repeated to return to zero, and the amount of residual magnetization is plotted against the applied magnetic field to measure the DCD curve. From the obtained DCD curve, the point at which the amount of magnetization becomes zero is defined as the residual magnetic force Hr, and the DCD curve is further differentiated to determine the slope of the DCD curve in each magnetic field. In the slope of this DCD curve, the slope near the residual magnetic force Hr is _Χirr .

(Saturation magnetization Ms)
First, the MH loop of the entire magnetic recording medium (measurement sample) is measured in the thickness direction of the magnetic recording medium. Next, use acetone, ethanol, etc. to wipe away the coating film (base layer, magnetic layer, etc.), leaving only the base layer, and for background correction, conduct the MH loop of the base layer in the same way in the thickness direction. Measure. Thereafter, the MH loop of the base layer is subtracted from the MH loop of the entire magnetic recording medium to obtain the MH loop after background correction. Ms (emu/cm ³ ) is calculated from the value of the obtained saturation magnetization Ms (emu) of the MH loop and the volume (cm ³ ) of the magnetic layer in the measurement sample. Note that the volume of the magnetic layer is determined by multiplying the area of the measurement sample by the average thickness of the magnetic layer.

(Magneto-rheological coefficient S)
First, a magnetic field of -1193 kA/m (15 kOe) is applied to the entire magnetic recording medium (measurement sample) to return the magnetic field to zero and create a residual magnetization state. Thereafter, a magnetic field equivalent to the value of the residual magnetic force Hr obtained from the DCD curve is applied in the opposite direction. The amount of magnetization is continuously measured at regular time intervals for 1000 seconds while a magnetic field is applied. The magnetorheological coefficient S is calculated by comparing the thus obtained relationship between the time t and the amount of magnetization M(t) with the following equation.
M(t)=M0+S×ln(t)
(However, M(t): amount of magnetization at time t, M0: amount of initial magnetization, S: magnetorheological coefficient, ln(t): natural logarithm of time)

(Arithmetic mean roughness Ra)
The arithmetic mean roughness Ra of the magnetic surface is preferably 2.5 nm or less, more preferably 2.0 nm or less. When Ra is 2.5 nm or less, better SNR can be obtained.

The above arithmetic mean roughness Ra is determined as follows. First, the surface on the side where the magnetic layer is provided is observed using an AFM (Atomic Force Microscope) (manufactured by Bruker, Dimension Icon) to obtain a cross-sectional profile. Next, the arithmetic mean roughness Ra is determined from the obtained cross-sectional profile in accordance with JIS B0601:2001.

(4) Method for manufacturing a magnetic recording medium Next, a method for manufacturing a magnetic recording medium having the above-described configuration will be described. First, a paint for forming a base layer is prepared by kneading and/or dispersing nonmagnetic powder, a binder, and the like in a solvent. Next, a coating material for forming a magnetic layer is prepared by kneading and/or dispersing magnetic powder, a binder, and the like in a solvent. For preparing the coating material for forming the magnetic layer and the coating material for forming the base layer, the following solvents, dispersing devices, and kneading devices can be used, for example.

Solvents used in the above paint preparation include, for example, ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; alcohol solvents such as methanol, ethanol, and propanol; for example, methyl acetate, ethyl acetate, and butyl acetate. , propyl acetate, ethyl lactate, and ethylene glycol acetate; ether solvents such as diethylene glycol dimethyl ether, 2-ethoxyethanol, tetrahydrofuran, and dioxane; aromatic hydrocarbon solvents such as benzene, toluene, and xylene; Other examples include halogenated hydrocarbon solvents such as methylene chloride, ethylene chloride, carbon tetrachloride, chloroform, and chlorobenzene. One of these may be used or a mixture of two or more may be used.

As the kneading device used for preparing the above-mentioned paint, for example, a continuous twin-screw kneader, a continuous twin-screw kneader capable of multistage dilution, a kneader, a pressure kneader, and a roll kneader can be used. , but is not particularly limited to these devices. In addition, examples of dispersion equipment used in the above-mentioned coating preparation include roll mills, ball mills, horizontal sand mills, vertical sand mills, spike mills, pin mills, tower mills, pearl mills (such as "DCP Mill" manufactured by Eirich), homogenizers, and ultra A dispersion device such as a sonic dispersion machine can be used, but is not particularly limited to these devices.

Next, a base layer-forming paint is applied to one main surface of the base layer and dried to form a base layer. Subsequently, a magnetic layer-forming paint is applied onto the underlayer and dried to form a magnetic layer on the underlayer. Note that during drying, the magnetic powder is magnetically oriented in the thickness direction of the base layer using, for example, a solenoid coil. Further, during drying, the magnetic powder may be magnetically oriented in the longitudinal direction (running direction) of the base layer using, for example, a solenoid coil, and then the magnetic powder may be oriented in the thickness direction of the base layer. After forming the magnetic layer, a back layer is formed on the other main surface of the base layer. A magnetic recording medium is thus obtained.

Thereafter, the obtained magnetic recording medium is re-wound around a large-diameter core and subjected to a hardening process. Finally, the magnetic recording medium is calendered and then cut into a predetermined width (for example, 1/2 inch width). Through the above steps, the desired elongated magnetic recording medium can be obtained.

(5) Examples Hereinafter, the present technology will be specifically explained using examples, but the present technology is not limited only to these examples.

In the following Examples and Comparative Examples, the average thickness t _T of the magnetic recording tape as a magnetic recording medium, the amount of dimensional change Δw in the width direction of the magnetic recording tape with respect to the change in tension in the longitudinal direction of the magnetic recording tape, and the temperature of the magnetic recording tape Expansion coefficient α, humidity expansion coefficient β of the magnetic recording tape, Poisson's ratio ρ of the magnetic recording tape, longitudinal elastic limit value σ _MD of the magnetic recording tape, average thickness t _m of the magnetic layer, squareness ratio S2, average of the back layer The thickness t _b , the surface roughness R _ab of the back layer, and the interlayer friction coefficient μ between the magnetic surface and the back surface are values determined by the measuring method described in the above embodiment. However, as will be described later, in Example 11, the velocity V when measuring the elastic limit value σ _MD in the longitudinal direction was set to a different value from the measuring method described in the above embodiment.

[Example 1]
(Preparation process of paint for forming magnetic layer)
A paint for forming a magnetic layer was prepared as follows. First, a first composition having the following composition was kneaded using an extruder. Next, the kneaded first composition and the second composition having the following composition were added to a stirring tank equipped with a disperser for preliminary mixing. Subsequently, the mixture was further mixed in a sand mill and filtered to prepare a coating material for forming a magnetic layer.

(First composition)
Powder of ε-iron oxide nanoparticles (ε-Fe ₂ O ₃ crystal particles): 100 parts by mass Vinyl chloride resin (cyclohexanone solution 30% by mass): 10 parts by mass (degree of polymerization 300, Mn=10000, OSO ₃ as a polar group) Contains K=0.07 mmol/g, secondary OH=0.3 mmol/g.)
Aluminum oxide powder: 5 parts by mass (α-Al ₂ O ₃ , average particle size 0.2 μm)
Carbon black: 2 parts by mass (manufactured by Tokai Carbon Co., Ltd., product name: SEAST TA)

(Second composition)
Vinyl chloride resin: 1.1 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
n-Butyl stearate: 2 parts by mass Methyl ethyl ketone: 121.3 parts by mass Toluene: 121.3 parts by mass Cyclohexanone: 60.7 parts by mass

Finally, 4 parts by mass of polyisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of myristic acid were added as curing agents to the magnetic layer forming paint prepared as described above. did.

(Preparation process of paint for base layer formation)
A paint for forming a base layer was prepared as follows. First, a third composition having the following composition was kneaded using an extruder. Next, the kneaded third composition and the fourth composition having the following composition were added to a stirring tank equipped with a disper for preliminary mixing. Subsequently, the mixture was further mixed in a sand mill and filtered to prepare a paint for forming a base layer.

(Third composition)
Acicular iron oxide powder: 100 parts by mass (α-Fe ₂ O ₃ , average major axis length 0.15 μm)
Vinyl chloride resin: 55.6 parts by mass (resin solution: resin content 30% by mass, cyclohexanone 70% by mass)
Carbon black: 10 parts by mass (average particle size 20 nm)

(Fourth composition)
Polyurethane resin UR8200 (manufactured by Toyobo): 18.5 parts by mass n-butyl stearate: 2 parts by mass Methyl ethyl ketone: 108.2 parts by mass Toluene: 108.2 parts by mass Cyclohexanone: 18.5 parts by mass

Finally, 4 parts by mass of polyisocyanate (trade name: Coronate L, manufactured by Nippon Polyurethane Co., Ltd.) and 2 parts by mass of myristic acid were added as curing agents to the base layer forming paint prepared as described above. did.

(Preparation process of paint for back layer formation)
A paint for forming a back layer was prepared as follows. A paint for forming a back layer was prepared by mixing the following raw materials in a stirring tank equipped with a disperser and filtering the mixture. Carbon black (manufactured by Asahi Co., Ltd., product name: #80): 100 parts by mass Polyester polyurethane: 100 parts by mass (manufactured by Nippon Polyurethane Co., Ltd., product name: N-2304)
Methyl ethyl ketone: 500 parts by mass Toluene: 400 parts by mass Cyclohexanone: 100 parts by mass

(Film forming process)
Using the paint produced as described above, a base layer with an average thickness of 1.0 μm and an average thickness t _m were formed on a long polyethylene naphthalate film (hereinafter referred to as "PEN film"), which is a non-magnetic support. A magnetic layer having a thickness of 90 nm was formed as follows. First, a base layer-forming paint was applied onto the film and dried to form a base layer on the film. Next, a magnetic layer-forming paint was applied onto the underlayer and dried to form a magnetic layer on the underlayer. In addition, when drying the paint for forming the magnetic layer, the magnetic powder was magnetically oriented in the thickness direction of the film using a solenoid coil. Further, the application time of the magnetic field to the paint for forming the magnetic layer was adjusted, and the squareness ratio S2 in the thickness direction (perpendicular direction) of the magnetic recording tape was set to 65%.

Subsequently, a back layer having an average thickness _tb of 0.6 μm was applied to the film on which the underlayer and magnetic layer had been formed and dried. Then, the film on which the underlayer, magnetic layer, and back layer were formed was subjected to a curing treatment. Subsequently, a calender treatment was performed to smooth the surface of the magnetic layer. At this time, the calendering conditions (temperature) were adjusted so that the interlayer friction coefficient μ between the magnetic surface and the back surface was approximately 0.5, and then rehardening treatment was performed to obtain a material with an average thickness _t of 5.5 μm. A magnetic recording tape was obtained.

(Cutting process)
The magnetic recording tape obtained as described above was cut to a width of 1/2 inch (12.65 mm) and wound around a core to obtain pancakes.

The magnetic recording tape obtained as described above had the characteristics shown in Table 1. For example, the dimensional change ΔW of the magnetic recording tape was 705 ppm/N.

[Example 2]
A magnetic recording tape was obtained in the same manner as in Example 1 except that the thickness of the PEN film was made thinner than in Example 1 so that the dimensional change Δw was 750 ppm/N. The average thickness of the magnetic recording tape was 5 μm.

[Example 3]
A magnetic recording tape was produced in the same manner as in Example 1, except that the thickness of the PEN film was made thinner than in Example 1 so that the amount of dimensional change Δw was 800 ppm/N, and the average thickness of the back layer and underlayer was made thinner. Obtained. The average thickness of the magnetic recording tape was 4.5 μm. Furthermore, as the back layer was made thinner, the surface roughness R _ab of the back layer increased.

[Example 4]
The thickness of the PEN film was made thinner than in Example 1 so that the amount of dimensional change Δw was 800 ppm/N, the average thickness of the back layer and the base layer was made thinner, and the base layer, magnetic layer, and back layer were formed. A magnetic recording tape was obtained in the same manner as in Example 1, except that the curing conditions for the film were adjusted.

[Example 5]
A magnetic recording tape was obtained in the same manner as in Example 4 except that the composition of the paint for forming the underlayer was changed so that the coefficient of thermal expansion α was 8 ppm/°C.

[Example 6]
A magnetic recording tape was produced in the same manner as in Example 4, except that thin barrier layers were formed on both surfaces of the PEN film so that the humidity expansion coefficient β was 3 ppm/%RH, and the average thickness of the underlayer was increased. Obtained. The average thickness of the magnetic recording tape was 4.6 μm.

[Example 7]
A magnetic recording tape was obtained in the same manner as in Example 4, except that the composition of the paint for forming the back layer was changed so that the Poisson's ratio ρ was 0.31.

[Example 8]
A magnetic recording tape was obtained in the same manner as in Example 4, except that the composition of the paint for forming the back layer was changed so that the Poisson's ratio ρ was 0.35.

[Example 9]
A magnetic recording tape was prepared in the same manner as in Example 7, except that the curing conditions of the film on which the underlayer, magnetic layer, and back layer were formed were adjusted so that the elastic limit value σ _MD in the longitudinal direction was 0.8N. Obtained.

[Example 10]
The same method as in Example 7 was used except that the curing conditions and re-curing conditions of the film on which the underlayer, magnetic layer, and back layer were formed were adjusted so that the elastic limit value σ _MD in the longitudinal direction was 3.5N. A magnetic recording tape was obtained.

[Example 11]
A magnetic recording tape was obtained in the same manner as in Example 9. Then, the elastic limit value σ _MD of the obtained magnetic recording tape was measured by changing the speed V at which the longitudinal elastic limit value σ _MD was measured to 5 mm/min. As a result, the elastic limit value σ _MD in the longitudinal direction was 0.8, with no change from the elastic limit value σ _MD in the longitudinal direction (Example 9) when the speed V was 0.5 mm/min.

[Example 12]
A magnetic recording tape was obtained in the same manner as in Example 7 except that the coating thickness of the coating material for forming the magnetic layer was changed so that the average thickness _tm of the magnetic layer was 40 nm. The average thickness of the magnetic recording tape was 4.4 μm.

[Example 13]
A magnetic recording tape was obtained in the same manner as in Example 7 except that the average thickness of the back layer and underlayer was reduced. The average thickness of the magnetic recording tape was 4.4 μm.

[Example 14]
A magnetic recording tape was obtained in the same manner as in Example 7 except that the surface roughness R _ab of the back layer was lowered to 3.2 nm and the friction coefficient μ was increased.

[Example 15]
A magnetic recording tape was obtained in the same manner as in Example 7 except that the coating thickness of the coating material for forming the magnetic layer was changed so that the average thickness _tm of the magnetic layer was 110 nm.

[Example 16]
A magnetic recording tape was obtained in the same manner as in Example 7 except that the surface roughness R _ab of the base layer was increased and the friction coefficient μ was decreased.

[Example 17]
A magnetic recording tape was again obtained in the same manner as in Example 7 except that the friction coefficient μ was lowered to 0.18.

[Example 18]
A magnetic recording tape was again obtained in the same manner as in Example 7 except that the friction coefficient μ was increased to 0.82.

[Example 19]
A magnetic recording tape was obtained in the same manner as in Example 7, except that the application time of the magnetic field to the magnetic layer forming paint was adjusted and the squareness ratio S2 in the thickness direction (perpendicular direction) of the magnetic recording tape was set to 73%.

[Example 20]
A magnetic recording tape was obtained in the same manner as in Example 7, except that the application time of the magnetic field to the magnetic layer forming paint was adjusted and the squareness ratio S2 in the thickness direction (perpendicular direction) of the magnetic recording tape was set to 80%.

[Example 21]
The same method as in Example 7 was used except that the curing conditions and re-curing conditions of the film on which the underlayer, magnetic layer, and back layer were formed were adjusted so that the elastic limit value σ _MD in the longitudinal direction was 5.0N. A magnetic recording tape was obtained.

[Example 22]
The same method as in Example 7 was used except that barium ferrite (BaFe ₁₂ O ₁₉ ) nanoparticles were used instead of ε iron oxide nanoparticles and the amount of vinyl chloride resin in the first composition was changed to 30 parts by mass. A magnetic recording tape was obtained.

[Example 23]
A magnetic recording tape was obtained in the same manner as in Example 1 except that the thickness of the back layer and the thickness of the underlayer were reduced. The average thickness of the magnetic recording tape was 5.0 μm. The dimensional change ΔW of the magnetic recording tape was 800 ppm/N.

[Example 24]
The reason is that barium ferrite (BaFe ₁₂ O ₁₉ ) nanoparticles were used instead of ε iron oxide nanoparticles, that the vinyl chloride resin in the first composition was changed to 30 parts by mass, and that the thickness of the PEN film and the back layer were A magnetic recording tape was obtained in the same manner as in Example 1 except that the thickness of the magnetic recording tape and the thickness of the underlayer were reduced. The average thickness of the magnetic recording tape was 5.0 μm. The dimensional change ΔW of the magnetic recording tape was 800 ppm/N.

[Comparative example 1]
A magnetic tape was obtained in the same manner as in Example 1, except that the tensilization of the PEN film was changed so that the amount of dimensional change Δw was 650 [ppm/N].

[Comparative example 2]
A magnetic recording tape was prepared in the same manner as in Example 24, except that a PEN film with increased stretching strength in the width direction was used in place of the PEN film used in Example 24, and the thickness of the base layer was increased. Obtained. Due to the change in the PEN film, the amount of dimensional change Δw was reduced compared to the magnetic recording tape of Example 24. The dimensional change Δw of the magnetic recording tape of Comparative Example 2 was 630 ppm/N. The average thickness of the magnetic recording tape was 5.7 μm.

[Comparative example 3]
Magnetic recording was performed in the same manner as in Example 24, except that a PEN film with increased stretching strength in the width direction was used in place of the PEN film used in Example 24, and the thickness of the underlayer was slightly increased. Got the tape. By changing the PEN film, the dimensional change Δw was significantly reduced compared to the magnetic recording tape of Example 24. The dimensional change Δw of the magnetic recording tape of Comparative Example 3 was 500 ppm/N. The average thickness of the magnetic recording tape was 6.5 μm.

(Determination of amount of change in tape width)
First, a cartridge sample incorporating a 1/2 inch wide magnetic recording tape was prepared. The cartridge sample contained the magnetic recording tape wound around a reel provided within the cartridge case. Note that on the magnetic recording tape, two V-shaped magnetic pattern rows are arranged parallel to each other in the longitudinal direction at known intervals (hereinafter referred to as "the known spacing between the magnetic pattern rows when recorded in advance"). More than one column was recorded in advance. Next, the cartridge sample was run back and forth using a recording/reproducing device. Two or more rows of the above-mentioned V-shaped magnetic pattern rows were simultaneously reproduced during reciprocal travel, and the interval between the magnetic pattern rows during travel was continuously measured from the shape of the reproduced waveform of each row. During running, the rotational drive of the spindle drive device and reel drive device is controlled based on the measured spacing information between the magnetic pattern rows, so that the spacing between the magnetic pattern rows is a specified width or almost a specified width. In addition, the longitudinal tension of the magnetic recording tape was automatically adjusted. The simple average of all the measured values for one round trip of the magnetic pattern sequence interval is defined as the "measured magnetic pattern sequence interval", and the difference between this and the "known magnetic pattern sequence interval recorded in advance" was defined as "change in tape width."

Further, the reciprocating run by the recording/reproducing device was performed in a constant temperature and humidity chamber. The speed of the round trip was 5 m/sec. The temperature and humidity during the round trip are independent of the above-mentioned round trip, and the temperature range is 10°C to 45°C, the relative humidity range is 10% to 80%, and a preset environmental change program (e.g. 10°C 10% → Repeat 29°C 80% → 10°C 10% twice. Change from 10°C 10% to 29°C 80% in 2 hours, and change from 29°C 80% → 10°C 10% in 2 hours.) , changed gradually and iteratively.

This evaluation was repeated until the "pre-programmed environmental change program" was completed. After the evaluation, calculate the average value (simple average) using all the absolute values of the "changes in tape width" obtained during each round trip, and use that value as the "effective amount of change in tape width" for that tape. And so. Judgments were made for each tape according to the deviation from the ideal of this "effective tape width change amount" (the smaller the better), and eight grades of judgment values were assigned to each tape. Note that an evaluation of "8" indicates the most desirable determination result, and an evaluation of "1" indicates the most undesirable determination result. For magnetic tapes rated in any of the eight grades, the following conditions are observed during tape running.
8: No abnormality occurs 7: A slight increase in the error rate is observed while driving 6: A severe increase in the error rate is observed while driving 5: The servo signal cannot be read while driving, and the error rate is mild (1~ 4: The servo signal cannot be read while driving and requires moderate rereading (within 10 times) 3: The servo signal cannot be read while driving and requires severe rereading (more than 10 times) 2: The servo cannot be read and the system sometimes stops due to a system error. 1: The servo cannot be read and the system stops immediately due to a system error.

(Evaluation of electromagnetic conversion characteristics)
First, a reproduction signal of the magnetic recording tape was obtained using a loop tester (manufactured by Microphysics). The conditions for acquiring the reproduced signal are shown below.
head:GMR
Headspeed: 2m/s
signal: single recording frequency (10MHz)
Recording current: optimal recording current

Next, the reproduced signal was captured using a spectrum analyzer with a span of 0 to 20 MHz (resolution band width=100 kHz, VBW = 30 kHz). Next, the peak of the acquired spectrum is set as the signal amount S, and the floor noise excluding the peak is integrated to obtain the noise amount N. The ratio S/N of the signal amount S and the noise amount N is determined as the SNR (Signal-to- Noise Ratio). Next, the obtained SNR was converted into a relative value (dB) based on the SNR of Comparative Example 1 as a reference medium. Next, using the SNR (dB) obtained as described above, the quality of the electromagnetic conversion characteristics was determined as follows.
Better: The SNR of the magnetic recording tape is 1 dB or more better than the SNR (0=(dB)) of the evaluation reference sample (Comparative Example 1).
Good: The SNR of the magnetic recording tape is equivalent to or exceeds the SNR (=0 (dB)) of the evaluation reference sample (Comparative Example 1).
Defective: The SNR of the magnetic recording tape is less than the SNR (=0 (dB)) of the evaluation standard sample (Comparative Example 1).

(Evaluation of winding misalignment)
First, a cartridge sample was prepared after the "determination of the amount of change in tape width" described above. Next, the reel on which the tape was wound was taken out from the cartridge sample, and the end surface of the wound tape was visually observed. Note that the reel has flanges, and at least one flange is transparent or semi-transparent, so that the state of internal tape winding can be observed through the flange.

As a result of the observation, if the end surface of the tape was not flat and there were steps or the tape protruded, it was determined that there was a tape winding misalignment. Furthermore, the more a plurality of these steps or tape protrusions were observed, the more the "winding misalignment" was considered to be bad. The above determination was made for each sample. The winding misalignment state of each sample was compared with the winding misalignment state of Comparative Example 1 as a reference medium, and quality was determined as follows.
Good: When the winding misalignment condition of the sample is equal to or less than the winding misalignment condition of the reference sample (Comparative Example 1). Bad: When the winding misalignment condition of the sample is more than the winding misalignment condition of the reference sample (Comparative Example 1).

Table 1 shows the configurations and evaluation results of the magnetic recording tapes of Examples 1 to 24 and Comparative Examples 1 to 3.

In addition, each symbol in Table 1 means the following measured value.
t _bs : Thickness of base layer (unit: μm)
t _T : Thickness of magnetic recording tape (unit: μm)
Δw: Amount of dimensional change in the width direction of the magnetic recording tape with respect to a change in tension in the longitudinal direction of the magnetic recording tape (unit: ppm/N)
α: Temperature expansion coefficient of magnetic recording tape (unit: ppm/°C)
β: Humidity expansion coefficient of magnetic recording tape (unit: ppm/%RH)
ρ: Poisson's ratio σ of the magnetic recording tape _MD : Elastic limit value in the longitudinal direction of the magnetic recording tape (unit: N)
V: Speed when performing elastic limit measurement (unit: mm/min)
t _m : Average thickness of magnetic layer (unit: nm)
S2: Squareness ratio in the thickness direction (vertical direction) of the magnetic recording tape (unit: %)
t _b : Average thickness of back layer (unit: nm)
R _ab : Surface roughness of back layer (unit: nm)
μ: Coefficient of interlayer friction between magnetic surface and back surface t _n : Thickness of underlayer (non-magnetic layer) (unit: μm)

The results shown in Table 1 reveal the following.

For all of the magnetic recording tapes of Examples 1 to 24, the determination result of the amount of change in tape width was 4 or more (that is, the deviation from the ideal amount of "effective amount of change in tape width" was small). Therefore, it can be seen that the magnetic recording medium according to the present technology is suitable for use in a recording/reproducing device that adjusts tension in the longitudinal direction.
On the other hand, in Comparative Example 1, even if the average thickness of the nonmagnetic layer is the same, 1.0 μm, when Δw is 650 ppm/N, the judgment result regarding the amount of change in tape width is poor. In Comparative Example 2, the average thickness of the nonmagnetic layer was 1.1 μm, and Δw was 630 ppm/N, giving poor judgment results regarding the amount of change in tape width. In Comparative Example 3, even if the average thickness of the nonmagnetic layer was 1.0 or less, when ΔW was 500, the determination result regarding the amount of change in tape width was poor.
From these results, it is clear that when ΔW is 660 ppm/N or more and the average thickness of the nonmagnetic layer is 1.0 or less, the magnetic recording tape can be used in recording and reproducing devices that adjust longitudinal tension (especially It is thought that this method will be suitable for adjusting the width of the tape by adjusting the tension.

Further, from the results of determining the amount of change in tape width for Examples 1 to 24, the amount of dimensional change ΔW of the magnetic recording tape is preferably 700 ppm/N or more, more preferably 750 ppm/N or more. , and even more preferably 800 ppm/N or more, the magnetic recording tape is more suitable for use in a recording/reproducing device that adjusts tension in the longitudinal direction (particularly for adjusting the width of the tape by adjusting the tension). It turns out that

Comparing Example 24 and Comparative Example 2, it is considered that the average thickness of 5.5 μm or less contributes to making the magnetic recording tape suitable for use in the recording/reproducing apparatus described above.
Further, in Examples 2 to 24, the average thickness of the magnetic recording tape was 5.3 μm or less, and in Example 1, the average thickness of the magnetic recording tape was 5.5 μm. In Examples 2 to 24, the determination result of the amount of change in tape width is 5 or more, while in Example 1, the determination result of the amount of change in tape width is 4. From this, it can be seen that a magnetic recording tape having an average thickness of 5.3 μm or less is more suitable for use in the above recording/reproducing apparatus.

Furthermore, from the determination results of the amount of change in tape width for Examples 1 to 24, it is clear that the average thickness of the magnetic recording tape is 5.2 μm or less, more preferably 5.0 μm or less, so that the magnetic recording It can be seen that the tape becomes even more suitable for use in the recording and reproducing apparatus described above.

Further, in Examples 3 to 5 and 7 to 24, the average thickness of the nonmagnetic layer is 0.9 μm or less, and in Examples 1 and 2, the average thickness of the nonmagnetic layer is 1.0 μm. In Examples 3 to 5 and 7 to 24, the tape width determination results are 6 or more, while in Examples 1 and 2, the tape width determination results are 5 or less. From this, it can be seen that a magnetic recording tape in which the average thickness of the nonmagnetic layer is 0.9 μm or less is more suitable for use in the above-mentioned recording/reproducing apparatus.

Furthermore, when comparing Example 3 and Example 23, even if Δw is the same 800 ppm/N, the average thickness of the nonmagnetic layer is 0.61 μm than the average thickness of the tape is 0.9 μm. The judgment results regarding the amount of change in width are good.
From this result, it can be seen that a magnetic recording tape in which the average thickness of the nonmagnetic layer is 0.7 μm or less is even more suitable for use in the above-mentioned recording/reproducing apparatus.

When comparing the evaluation results of Examples 3 to 6, etc., from the viewpoint of suppressing deviation from the ideal amount of change in effective tape width, the coefficient of thermal expansion α is 6 ppm/°C≦α≦ It can be seen that 8 ppm/°C is preferable.

When comparing the evaluation results of Examples 3 to 5, etc., from the viewpoint of suppressing the deviation from the ideal "amount of change in effective tape width", it is found that the humidity expansion coefficient β is β≦5ppm/%RH It can be seen that it is preferable that

When comparing the evaluation results of Examples 7, 9, 10, etc., from the viewpoint of suppressing the deviation from the ideal "amount of change in effective tape width", it is found that the elastic limit value σ _MD in the longitudinal direction is , 0.8[N]≦σ _MD .
A comparison between Example 9 and Example 11 shows that the elastic limit value σ _MD does not depend on the speed V at which the elastic limit measurement is performed.

When the evaluation results of Examples 7 and 20 are compared with each other, from the viewpoint of improving electromagnetic conversion characteristics, it is found that the squareness ratio S2 of the magnetic recording tape in the vertical direction is 75% or more, particularly 80% or more. It turns out that this is preferable.

Comparing the evaluation results of Examples 7 and 22, etc., it can be seen that when barium ferrite nanoparticles are used as the magnetic particles, the same evaluation results as when ε iron oxide nanoparticles are used as the magnetic particles can be obtained. I understand.

Comparing the evaluation results of Examples 7 and 15, it can be seen that from the viewpoint of improving electromagnetic conversion characteristics, it is preferable that the thickness of the magnetic layer is 100 nm or less, particularly 90 nm or less.

Comparing the evaluation results of Examples 7, 14, 16 to 18, it is found that from the viewpoint of improving winding misalignment, the friction coefficient μ is 0.18<μ<0.82, particularly 0.20≦μ It can be seen that it is preferable that ≦0.80.

Although the embodiments and examples of the present technology have been specifically described above, the present technology is not limited to the above-described embodiments and examples, and various modifications based on the technical idea of the present technology are possible. It is.

For example, the configurations, methods, processes, shapes, materials, numerical values, etc. mentioned in the above-mentioned embodiments and examples are merely examples, and different configurations, methods, processes, shapes, materials, and values may be used as necessary. Numerical values etc. may also be used. Further, the chemical formulas of compounds, etc. are representative ones, and as long as they are general names of the same compound, they are not limited to the stated valency, etc.

Furthermore, the configurations, methods, processes, shapes, materials, numerical values, etc. of the embodiments and examples described above can be combined with each other without departing from the gist of the present technology.

Furthermore, in this specification, a numerical range indicated using "~" indicates a range that includes the numerical values written before and after "~" as the minimum value and maximum value, respectively. In the numerical ranges described stepwise in this specification, the upper limit or lower limit of the numerical range of one step may be replaced with the upper limit or lower limit of the numerical range of another step. The materials exemplified herein can be used alone or in combination of two or more, unless otherwise specified.

The present technology can also have the following configuration.
(1) A cartridge case that houses the magnetic tape;
a memory that is provided in the cartridge case and stores information before data is recorded on the magnetic tape, the information for adjusting the width of the magnetic tape when recording data on the magnetic tape or when reproducing data. cartridge.
(2) The cartridge according to (1) above,
The information includes width information for the entire length of the magnetic tape, which is obtained during at least one of the unwinding operation and rewinding operation of the magnetic tape performed by the data recording/reproducing device before data recording. cartridge.
(3) The cartridge according to (2) above,
The width information is discrete data acquired for each predetermined length of the magnetic tape.Cartridge.
(4) The cartridge according to (2) or (3) above,
The information includes environmental information around the magnetic tape at the time of acquiring the width information. Cartridge.
(5) The cartridge according to (4) above,
The environmental information includes information about the temperature around the magnetic tape at the time of acquiring the width information.
(6) The cartridge according to (4) or (5) above,
The environmental information includes information on the humidity around the magnetic tape at the time of acquiring the width information.
(7) The cartridge according to any one of (1) to (6) above,
The information includes information on the tension of the magnetic tape at the time of acquiring the width information. Cartridge.
(8) The cartridge according to any one of (1) to (7) above,
The information includes information regarding the base material of the magnetic tape. Cartridge.
(9) The cartridge according to (2) above,
A cartridge in which the width of the magnetic tape is adjusted so that the width of the magnetic tape is the same as the width information during data reproduction or data recording.
(10) The cartridge according to (9) above,
A cartridge in which the width of the magnetic tape is adjusted by adjusting the tension of the magnetic tape.
(11) The cartridge according to (9) or (10) above,
The information includes environmental information around the magnetic tape at the time of acquiring the width information,
The width of the magnetic tape is adjusted based on the difference between the environmental information and the environmental information measured during data recording or data reproduction.
(12) The cartridge according to any one of (1) to (11) above,
The cartridge is a cartridge based on the LTO (linear tape open) standard.
(13) Information provided in a cartridge case that accommodates a magnetic tape, before data is recorded on the magnetic tape, for adjusting the width of the magnetic tape when recording or reproducing data on the magnetic tape. Remember memory.
(14) A data recording device that records data on a magnetic tape,
The width information for the entire length of the magnetic tape before data recording, which is stored in a memory provided in a cartridge case that accommodates the magnetic tape, is read out, and based on the width information, the magnetic tape during data recording is determined based on the width information. A data recording device that adjusts the width of the tape.
(15) A data reproducing device that reproduces data recorded on a magnetic tape,
The width information for the entire length of the magnetic tape before data recording is stored in a memory provided in a cartridge case that accommodates the magnetic tape, and based on the width information, the magnetic tape during data reproduction of the magnetic tape is read out. A data playback device that adjusts the tape width.
(16) having a layered structure including a magnetic layer, a nonmagnetic layer, and a base layer in this order;
The average thickness t _T is t _T ≦5.5 μm,
The amount of dimensional change Δw in the width direction with respect to the change in tension in the longitudinal direction is 660 ppm/N≦Δw, and
The average thickness t _n of the nonmagnetic layer is t _n ≦1.0 μm.
is,
magnetic recording medium.
(17) The magnetic recording medium according to (16) above,
A magnetic recording medium with a squareness ratio of 65% or more in the vertical direction.
(18) The magnetic recording medium according to (16) or (17) above,
The nonmagnetic layer contains Fe-based nonmagnetic particles, and the Fe-based nonmagnetic particles have a particle volume of 4.0×10 ⁻⁵ μm ³ or less.
(19) The magnetic recording medium according to any one of (16) to (18) above,
A magnetic recording medium whose average thickness t _T is t _T ≦5.3 μm.
(20) The magnetic recording medium according to any one of (16) to (19) above,
A magnetic recording medium whose average thickness t _T is t _T ≦5.2 μm.
(21) The magnetic recording medium according to any one of (16) to (20) above,
A magnetic recording medium having an average thickness t _T of t _T ≦5.0 μm.
(22) The magnetic recording medium according to any one of (16) to (21) above,
The average thickness t _n of the nonmagnetic layer is t _n ≦0.9 μm. A magnetic recording medium.
(23) The magnetic recording medium according to any one of (16) to (22) above,
The average thickness t _n of the nonmagnetic layer is t _n ≦0.7 μm. A magnetic recording medium.
(24) The magnetic recording medium according to any one of (16) to (23) above,
A magnetic recording medium, wherein the dimensional change amount Δw satisfies 700 ppm/N≦Δw.
(25) The magnetic recording medium according to any one of (16) to (24) above,
A magnetic recording medium, wherein the dimensional change amount Δw satisfies 750 ppm/N≦Δw.
(26) The magnetic recording medium according to any one of (16) to (25) above,
A magnetic recording medium, wherein the dimensional change amount Δw satisfies 800 ppm/N≦Δw.
(27) The magnetic recording medium according to any one of (16) to (26) above,
The layer structure has a back layer on the side opposite to the non-magnetic layer side of the base layer, and the surface roughness R _ab of the back layer is 3.0 nm≦R _ab ≦7.5 nm.Magnetic recording Medium.
(28) The magnetic recording medium according to any one of (16) to (27) above,
The layered structure has a back layer on the opposite side of the base layer to the non-magnetic layer, and has a friction coefficient μ between the surface of the magnetic recording medium on the magnetic layer side and the surface of the back layer side. is 0.20≦μ≦0.80. A magnetic recording medium.
(29) The magnetic recording medium according to any one of (16) to (28) above,
A magnetic recording medium in which the temperature expansion coefficient α is 6 ppm/°C≦α≦8 ppm/°C, and the humidity expansion coefficient β is β≦5 ppm/%RH.
(30) The magnetic recording medium according to any one of (16) to (29) above,
A magnetic recording medium having a Poisson's ratio ρ of 0.3≦ρ.
(31) The magnetic recording medium according to any one of (16) to (30) above,
A magnetic recording medium in which the elastic limit value σ _MD in the longitudinal direction is 0.8N≦σ _MD .
(32) The magnetic recording medium according to (31) above,
A magnetic recording medium, wherein the elastic limit value σ _MD does not depend on the speed V at which the elastic limit measurement is performed.
(33) The magnetic recording medium according to any one of (16) to (32) above,
A magnetic recording medium, wherein the magnetic layer is vertically aligned.
(34) The magnetic recording medium according to any one of (16) to (33) above,
The layered structure includes a back layer on a side of the base layer opposite to the nonmagnetic layer, and the average thickness t _b of the back layer is t _b ≦0.6 μm. The magnetic recording medium.
(35) The magnetic recording medium according to any one of (16) to (34) above,
A magnetic recording medium, wherein the average thickness t _m of the magnetic layer is 9 nm≦t _m ≦90 nm.
(36) The magnetic recording medium according to any one of (16) to (35) above,
A magnetic recording medium, wherein the magnetic layer contains magnetic powder.
(37) The magnetic recording medium according to any one of (16) to (36) above,
A magnetic recording medium, wherein the average thickness t _m of the magnetic layer is 35 nm≦t _m ≦90 nm.
(38) The magnetic recording medium according to any one of (16) to (37) above,
A magnetic recording medium, wherein the magnetic powder includes epsilon iron oxide magnetic powder, barium ferrite magnetic powder, cobalt ferrite magnetic powder, or strontium ferrite magnetic powder.
(39) The magnetic recording medium according to any one of (16) to (38) above,
The layer structure has a back layer on a side of the base layer opposite to the non-magnetic layer,
A magnetic recording medium, wherein the back layer has a surface roughness R _ab of 3.0 nm≦R _ab ≦7.5 nm.
(40) The magnetic recording medium according to any one of (16) to (38) above,
The layer structure has a back layer on a side of the base layer opposite to the non-magnetic layer,
A magnetic recording medium, wherein a friction coefficient μ between the surface on the magnetic layer side and the surface on the back layer side of the magnetic recording medium satisfies 0.20≦μ≦0.80.
(41) The magnetic recording medium according to any one of (16) to (40) above,
The temperature expansion coefficient α is 6 ppm/°C≦α≦9 ppm/°C, and
The humidity expansion coefficient β is β≦5.5ppm/%RH,
magnetic recording medium.
(42) The magnetic recording medium according to any one of (16) to (41) above,
A magnetic recording medium having a Poisson's ratio ρ of 0.25≦ρ.
(43) The magnetic recording medium according to any one of (16) to (42) above,
A magnetic recording medium in which the elastic limit value σ _MD in the longitudinal direction is 0.7N≦σ _MD .
(44) The magnetic recording medium according to (43) above,
A magnetic recording medium, wherein the elastic limit value σ _MD does not depend on the speed V at which the elastic limit measurement is performed.
(45) The magnetic recording medium according to any one of (16) to (44) above,
A magnetic recording medium, wherein an average thickness _tn of the nonmagnetic layer satisfies tn≦0.9 μm.
(46) The magnetic recording medium according to any one of (16) to (45) above,
A magnetic recording medium, wherein the nonmagnetic layer has an average thickness _tn of tn≦0.7 μm.

DESCRIPTION OF SYMBOLS 1... Magnetic tape 9... Cartridge memory 10... Cartridge 11... Cartridge case 30... Data recording/reproducing device 38... Control device

Claims (24)

magnetic tape and
a cartridge case that accommodates the magnetic tape;
a memory provided in the cartridge case for storing information before data is recorded on the magnetic tape and for adjusting the width of the magnetic tape when recording data on the magnetic tape and when reproducing data; Equipped with
The magnetic tape has a magnetic layer, a nonmagnetic layer, and a base layer in this order,
The average thickness t _T of the magnetic tape is t _T ≦5.5 μm,
The average thickness t _n of the nonmagnetic layer is t _n ≦1.0 μm,
The base layer includes a polyester resin. The cartridge according to claim 1,
A dimensional change Δw [ppm/N] in the width direction with respect to a change in tension in the longitudinal direction of the magnetic tape satisfies 680 ppm/N≦Δw. The cartridge according to claim 2,
A dimensional change Δw [ppm/N] in the width direction with respect to a change in tension in the longitudinal direction of the magnetic tape satisfies 700 ppm/N≦Δw. The cartridge according to claim 3,
A dimensional change Δw [ppm/N] in the width direction with respect to a change in tension in the longitudinal direction of the magnetic tape satisfies 750 ppm/N≦Δw. The cartridge according to claim 4,
A dimensional change Δw [ppm/N] in the width direction with respect to a change in tension in the longitudinal direction of the magnetic tape satisfies 800 ppm/N≦Δw. The cartridge according to any one of claims 1 to 5,
The average thickness t _T of the magnetic tape is t _T ≦5.3 μm. Cartridge. The cartridge according to claim 6,
The average thickness t _T of the magnetic tape is t _T ≦5.2 μm. Cartridge. The cartridge according to claim 7,
The average thickness t _T of the magnetic tape is t _T ≦5.0 μm. Cartridge. The cartridge according to claim 8,
The average thickness t _T of the magnetic tape is t _T ≦4.6 μm. Cartridge. The cartridge according to any one of claims 1 to 9,
The average thickness t _n of the non-magnetic layer is t _n ≦0.7 μm. The cartridge according to claim 10,
The average thickness t _n of the nonmagnetic layer is 0.01 μm≦t _n ≦0.61 μm. The cartridge. The cartridge according to any one of claims 1 to 11,
The magnetic layer includes magnetic powder,
The average particle size (average maximum particle size) of the magnetic powder is 8 nm or more and 22 nm or less. Cartridge. 13. The cartridge according to claim 12,
The magnetic layer includes magnetic powder,
The average particle size (average maximum particle size) of the magnetic powder is 10 nm or more and 20 nm or less. Cartridge. The cartridge according to any one of claims 1 to 13,
The information includes width information for the entire length of the magnetic tape, which is obtained during at least one of the unwinding operation and rewinding operation of the magnetic tape performed by the data recording/reproducing device before data recording. cartridge. 15. The cartridge according to claim 14,
The width information is discrete data acquired for each predetermined length of the magnetic tape.Cartridge. The cartridge according to claim 14 or 15,
The information includes environmental information around the magnetic tape at the time of acquiring the width information. Cartridge. 17. The cartridge according to claim 16,
The environmental information includes information about the temperature around the magnetic tape at the time of acquiring the width information. The cartridge according to claim 16 or 17,
The environmental information includes information on the humidity around the magnetic tape at the time of acquiring the width information. The cartridge according to any one of claims 14 to 18,
The information includes information on the tension of the magnetic tape at the time of acquiring the width information. Cartridge. The cartridge according to any one of claims 1 to 19,
The information includes information regarding the base material of the magnetic tape. Cartridge. 15. The cartridge according to claim 14,
A cartridge in which the width of the magnetic tape is adjusted so that the width of the magnetic tape is the same as the width information during data reproduction or data recording. 22. The cartridge according to claim 21,
A cartridge in which the width of the magnetic tape is adjusted by adjusting the tension of the magnetic tape. The cartridge according to claim 21 or 22,
The information includes environmental information around the magnetic tape at the time of acquiring the width information,
The width of the magnetic tape is adjusted based on the difference between the environmental information and the environmental information measured during data recording or data reproduction. The cartridge according to any one of claims 1 to 23,
The cartridge is a cartridge based on the LTO (linear tape open) standard.

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