JP2020013630A - Magnetic record medium, servo signal storage unit and manufacturing method of magnetic record medium - Google Patents

Abstract

To provide a technique capable of obtaining a reproduction waveform of a servo signal having satisfactory symmetric property when the magnetization direction of the servo signal includes component in a vertical direction.SOLUTION: The magnetic record medium in an embodiment includes a magnetic layer. The magnetic layer records a servo signal in a part of the magnetic layer being magnetized in a first direction including a component in a vertical direction with respect to an upper plane of the magnetic layer. Before recording the servo signal, the magnetic layer is magnetized in a second direction in a direction opposite to the first direction including the component of the vertical direction.SELECTED DRAWING: Figure 2

Description

  The present technology relates to a technology such as a magnetic recording medium having a magnetic layer on which a servo signal is recorded.

  In recent years, magnetic recording media have been widely used for applications such as backup of electronic data. As one of the magnetic recording media, a magnetic tape having a magnetic layer is widely used.

  The magnetic layer of the magnetic recording medium is provided with a plurality of recording tracks that are long in one direction, and data is recorded on the recording tracks. In recent years, in order to realize high-density recording of data, a method of reducing the distance between recording tracks has been used.

  On the other hand, if the distance between the recording tracks is reduced, there is a problem that when the magnetic head reads and writes data on the recording tracks, the magnetic head cannot accurately align with the recording tracks. For this reason, a method of recording a servo signal at a predetermined position between recording tracks is generally adopted. The data recording magnetic head can read the servo signal recorded on the magnetic layer to accurately position the recording track.

  As a recording method on a magnetic recording medium, a horizontal magnetic recording method in which magnetic particles in a magnetic layer are magnetized in a horizontal direction to record data, and a magnetic recording method in which magnetic particles in a magnetic layer are magnetized in a vertical direction to record data. A perpendicular magnetic recording system is known. The perpendicular magnetic recording method can record data at a higher density than the horizontal magnetic recording method.

  As a technique related to the present application, the following Patent Document 1 is cited.

JP 2005-166230 A

  In the case of the horizontal magnetic recording system, the magnetization direction of the servo signal recorded on the magnetic layer is oriented in the horizontal direction. In this case, the reproduced waveform when the servo signal is read is symmetric in the vertical (±) directions. On the other hand, in the case of the perpendicular magnetic recording method, when a servo signal is recorded on the magnetic layer, the magnetization direction of the servo signal includes a component in the vertical direction. As described above, when the magnetization direction of the servo signal includes a component in the vertical direction, if no measures are taken, there is a problem that the reproduced waveform when the servo signal is read becomes asymmetric in the vertical (±) direction. .

  In view of the circumstances described above, an object of the present technology is to provide a technology that can obtain a reproduced waveform of a servo signal having good symmetry when the magnetization direction of the servo signal includes a component in the vertical direction. It is in.

The magnetic recording medium according to the present technology includes a magnetic layer.
In the magnetic layer, a part of the magnetic layer is magnetized in a first direction including a component in a vertical direction perpendicular to the upper surface of the magnetic layer, a servo signal is recorded, and before the servo signal is recorded, , Including a component in the vertical direction, and magnetized in a second direction opposite to the first direction.

  Thereby, the magnetization direction of the servo signal recorded on the magnetization layer (first direction: including a component in the vertical direction) and the magnetization direction of the magnetic layer by pre-processing (second direction: including a component in the vertical direction) ) Are opposite to each other. As described above, by setting the magnetization direction of the servo signal and the magnetization direction of the magnetic layer in the pre-processing to be opposite to each other, a reproduced waveform of the servo signal having good symmetry can be obtained.

  The magnetic recording medium, the ratio of the amount of magnetization in the perpendicular direction with respect to the maximum value of the amount of magnetization when rotating the magnetic recording medium and measuring the amount of magnetization, in the longitudinal direction parallel to the upper surface The absolute value of the product of the magnetic layer and the squareness ratio may be 0.05 or more and 0.25 or less.

  This makes it possible to obtain a reproduced waveform of a servo signal having good symmetry.

  In the above magnetic recording medium, the magnetic layer may include non-oriented or vertically oriented magnetic powder therein.

  In the magnetic recording medium, the magnetic powder may be barium ferrite or a needle-like metal.

The servo signal recording device according to the present technology includes a servo signal recording unit and a preprocessing unit.
The servo signal recording unit applies a magnetic field to a part of the magnetic layer of the magnetic recording medium, thereby causing the magnetic layer to move in a first direction including a vertical component perpendicular to the upper surface of the magnetic layer. A servo signal is recorded by magnetizing a part.
The pre-processing unit includes a component in the vertical direction by applying a magnetic field to the magnetic layer before a servo signal is recorded by the servo signal recording unit, and includes a component in the vertical direction, which is opposite to the first direction. Magnetizing the magnetic layer in a second direction;

In the servo signal recording device, the pre-processing unit may include a magnet.
The magnet is rotatable and can change a magnetic field applied to the magnetic layer according to the rotation.

  In this device, the direction of magnetization (second direction) of the magnetic layer in the pretreatment can be adjusted by rotating the magnet.

In the method for manufacturing a magnetic recording medium according to the present technology, a magnetic field is applied to a part of a magnetic layer of the magnetic recording medium, whereby a first direction including a component in a vertical direction perpendicular to an upper surface of the magnetic layer is provided. Recording a servo signal by magnetizing a part of the magnetic layer.
By applying a magnetic field to the magnetic layer before the servo signal is recorded, the magnetic layer is magnetized in a second direction opposite to the first direction, including the component in the vertical direction. You.

  As described above, according to the embodiments of the present technology, it is possible to provide a technique capable of obtaining a reproduced waveform of a servo signal having good symmetry when the magnetization direction of the servo signal includes a component in the vertical direction.

It is a front view showing the servo signal recording device concerning one embodiment of this art. FIG. 2 is a partially enlarged view showing a part of the servo signal recording device. FIG. 3 is a top view showing a magnetic tape on which servo signals are recorded. FIG. 3 is a diagram illustrating the direction of magnetization of a magnetic tape. FIG. 3 is a diagram illustrating a relationship between a magnetization direction and a reproduced waveform of a servo signal. It is a figure showing various examples and various comparative examples. FIG. 3 is a diagram illustrating a relationship between a magnetization direction in a non-oriented tape and a reproduction waveform. FIG. 4 is a diagram illustrating a relationship between a magnetization direction and a reproduction waveform in a vertically oriented tape. It is a figure showing a vibration sample type magnetometer. FIG. 6 is a top view showing a state in which the magnetic tape is rotated and the amount of magnetization of the magnetic tape is measured according to the rotation. It is a figure showing the measurement result of the amount of magnetization of a magnetic tape. It is a figure which shows the magnetization curve of the longitudinal direction of a longitudinally-oriented tape and a perpendicularly-oriented tape, and the magnetization curve of a perpendicular direction. It is a figure which shows the relationship between a longitudinal direction squareness ratio and a degree of perpendicular orientation. It is a figure which shows the relationship between a longitudinal direction squareness ratio, and a perpendicular direction magnetization amount (%). FIG. 7 is a diagram for explaining the reason for using the product of the longitudinal squareness ratio and the perpendicular magnetization (%). FIG. 3 is a perspective view of a servo signal recording unit viewed from a servo signal recording surface side. FIG. 4 is a diagram illustrating an example of a case where distortion has occurred in a reproduced waveform of a servo signal. FIG. 4 is a schematic diagram illustrating a state where a servo signal is recorded by a servo signal recording unit. FIG. 3 is a diagram showing a reproduced waveform when a servo signal recorded on a magnetic layer is read by a reproducing head unit. FIG. 11 is a diagram illustrating an experimental result when an experiment is performed as to how thin a line of a servo signal can be to obtain a good reproduced waveform without distortion. FIG. 3 is a diagram illustrating a relationship between a gap length in a magnetic gap and an output in a reproduced waveform of a servo signal. FIG. 4 is a diagram illustrating a relationship between a gap length in a magnetic gap and a spacing (thickness of a servo signal line).

  Hereinafter, embodiments according to the present technology will be described with reference to the drawings.

<Configuration of Servo Signal Recording Device 100 and Configuration of Magnetic Tape 1>
FIG. 1 is a front view showing a servo signal recording device 100 according to an embodiment of the present technology. FIG. 2 is a partially enlarged view showing a part of the servo signal recording device 100. FIG. 3 is a top view showing the magnetic tape 1 on which the servo signal 6 is recorded.

  First, the configuration of the magnetic tape 1 (magnetic recording medium) will be described with reference to FIGS. As shown in these figures, a magnetic tape 1 is composed of a tape-shaped base material 2 elongated in one direction, a non-magnetic layer 3 laminated on the base material 2, and a magnetic layer laminated on the non-magnetic layer 3. 4 is included.

As a material of the base material 2, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or the like is used. The nonmagnetic layer 3 contains, for example, α-Fe ₂ O ₃ , polyurethane, and the like. The magnetic layer 4 is a ferromagnetic metal film containing a magnetic powder inside. As the magnetic powder, for example, non-oriented or vertically oriented barium ferrite or vertically oriented acicular metal is used.

  The magnetic layer 4 includes a plurality of data bands d (data bands d0 to d3) and a plurality of servo bands s (servo bands s0 to s4) arranged at positions sandwiching the data band d in the width direction (Y-axis direction). including. The data band d includes a plurality of recording tracks 5 that are long in the longitudinal direction, and data is recorded for each of the recording tracks 5. The servo band s includes a servo signal 6 of a predetermined pattern recorded by the servo signal recording device 100. For example, a recording head of a recording device (not shown) that records various data such as electronic data reads the servo signal 6 recorded on the magnetic layer and recognizes the position of the recording track 5.

  With reference to FIGS. 1 and 2, the servo signal recording device 100 sequentially includes a feed roller 11, a preprocessing unit 12, a servo signal recording unit 13, a reproducing head unit 14, A take-up roller 15 is provided. Although not shown, the servo signal recording device 100 stores a control unit that comprehensively controls each unit of the servo signal recording device 100 and various programs and data necessary for processing of the control unit. It has a recording unit, a display unit for displaying data, and the like.

  The feed roller 11 is capable of rotatably supporting the roll-shaped magnetic tape 1 (before recording the servo signal 6). The feed roller 11 is rotated in response to driving of a drive source such as a motor, and feeds the magnetic tape 1 downstream according to the rotation.

  The take-up roller 15 is capable of rotatably supporting the roll-shaped magnetic tape 1 (after recording the servo signal 6). The take-up roller 15 rotates in synchronism with the feed roller 11 in response to driving of a drive source such as a motor, and takes up the magnetic tape 1 on which the servo signal 6 is recorded according to the rotation. The feed roller 11 and the take-up roller 15 are capable of moving the magnetic tape 1 at a constant speed in the transport path.

  The servo signal recording unit 13 is disposed, for example, above the magnetic tape 1 (on the side of the magnetic layer 4). The servo signal recording section 13 may be arranged below the magnetic tape 1 (on the side of the base material 2). The servo signal recording unit 13 generates a magnetic field at a predetermined timing according to a rectangular wave pulse signal, and applies the magnetic field to a part of the magnetic layer 4 (after the pre-processing) of the magnetic tape 1.

  Thereby, the servo signal recording unit 13 records a servo signal 6 on the magnetic layer 4 by magnetizing a part of the magnetic layer 4 in the first direction (see a black arrow in FIG. 2). The servo signal recording unit 13 is capable of recording the servo signal 6 for each of the five servo bands s0 to s4 when the magnetic layer 4 passes below the servo signal recording unit 13.

  The first direction which is the magnetization direction of the servo signal 6 includes a component in a vertical direction perpendicular to the upper surface of the magnetic layer 4. That is, in the present embodiment, since the magnetic powder having the perpendicular orientation or the non-orientation is included in the magnetic layer 4, the servo signal 6 recorded on the magnetic layer 4 includes the magnetization component in the vertical direction.

  FIG. 4 is a diagram showing the direction of magnetization of the magnetic tape 1. As shown in FIG. 4, in this specification, the direction of the magnetization is based on the angle (0 °) when the direction of the magnetization is in the transport direction of the magnetic tape 1, and the angle increases in the clockwise direction. Direction. Although the magnetization direction of the servo signal 6 is shown in FIG. 4, the same applies to the magnetization direction of the magnetization by pre-processing described later and the magnetization direction of the entire magnetic layer 4.

  The pre-processing unit 12 is disposed, for example, below the magnetic tape 1 (on the side of the base material 2) upstream of the servo signal recording unit 13. The pre-processing unit 12 may be arranged above the magnetic tape 1 (on the side of the magnetic layer 4). The pre-processing unit 12 includes a permanent magnet 12a that can rotate with the Y-axis direction (width direction of the tape 1) as a center axis of rotation. The shape of the permanent magnet 12a is, for example, a columnar shape or a polygonal column shape, but is not limited thereto.

  Before the servo signal 6 is recorded by the servo signal recording unit 13, the permanent magnet 12 a applies a magnetic field to the entire magnetic layer 4 with a DC magnetic field to demagnetize the entire magnetic layer 4. Thereby, the permanent magnet 12a can previously magnetize the magnetic layer 4 in the second direction opposite to the magnetization direction of the servo signal 6 (see the white arrow in FIG. 2). By setting the two magnetization directions to be opposite to each other, the reproduced waveform of the servo signal 6 when the servo signal 6 is read can be symmetrical in the vertical direction (±) (see FIG. 5).

  The magnetization direction (first direction) of the servo signal 6 differs depending on the squareness ratio of the magnetic layer 4 (see FIG. 12). For example, vertically oriented barium ferrite, non-oriented barium ferrite, and vertically oriented needle-shaped metal typically have different squareness ratios. In such a case, even if a magnetic field is applied to the servo signal recording unit 13 under the same conditions, the magnetization directions (first directions) of the servo signals 6 are different from each other. Conversely, if the squareness ratio is the same and the condition of the servo signal recording unit 13 is the same, the first direction is the same even if the type of the magnetic tape 1 is different.

  Since the magnetization direction (first direction) of the servo signal 6 differs according to the squareness ratio of the magnetic layer 4, the magnetization direction (second direction) obtained by the pre-processing is also changed to match the magnetization direction of the servo signal 6. There is a need.

  Therefore, in the present embodiment, the permanent magnet 12a is rotatable about the axis in the Y-axis direction as the center axis of rotation. Thereby, the magnetization direction (second direction) by the pre-processing can be appropriately adjusted according to the type of the magnetic tape 1.

  Regarding the angle of the permanent magnet 12a, there is an appropriate angle range depending on the type of the magnetic tape 1. In the present specification, the angle of the permanent magnet 12a is based on the angle (0 °) when the N pole of the permanent magnet 12a faces the transport direction of the magnetic tape 1, and the angle increases in the clockwise direction. Direction.

  Here, the servo signal recording unit 13 overwrites the servo signal 6 on the magnetic layer 4 in which the magnetic layer 4 is magnetized in the second direction by the permanent magnet 12a. However, the first direction, which is the magnetization direction of the servo signal 6, is constant irrespective of the second direction if the squareness ratio of the magnetic layer 4 is the same.

  The reproducing head section 14 is disposed above the magnetic tape 1 (on the side of the magnetic layer 4) downstream of the servo signal recording section 13. The reproducing head section 14 reads the servo signal 6 from the magnetic layer 4 of the magnetic tape 1 on which the servo signal 6 has been recorded by the servo signal recording section 13 and pre-processed by the pre-processing section 12. The reproduction waveform of the servo signal 6 read by the reproduction head unit 14 is displayed on the screen of the display unit.

  Typically, the read head unit 14 detects a magnetic flux generated from the surface of the servo band s when the magnetic layer 4 passes below the read head unit 14. The magnetic flux detected at this time becomes a reproduced waveform of the servo signal 6.

  FIG. 5 is a diagram showing the relationship between the magnetization direction and the reproduced waveform of the servo signal 6.

  As shown in FIG. 5, in the present embodiment, since the magnetization direction of the servo signal 6 and the magnetization direction by the pre-processing are opposite to each other, the reproduction waveform of the servo signal 6 when the servo signal 6 is read is shown. Can be symmetrical in the vertical direction (±). When the servo signal 6 is recorded without performing the preprocessing, the reproduced waveform becomes asymmetric in the vertical direction (±) because the servo signal 6 includes the magnetization component in the vertical direction.

  Further, in the present embodiment, the amount of magnetic flux generated near the surface of the magnetic layer 4 can be increased as compared with the case where the servo signal 6 is recorded without performing the preprocessing. Thus, a high-output reproduced waveform can be obtained even when the thickness of the magnetic layer 4 is small.

  Here, the magnetization direction (first direction) of the servo signal 6 and the magnetization direction (second direction) of the pre-processing need not be strictly opposite directions, but may be substantially opposite directions. . This is related to the symmetry of the reproduced waveform of the servo signal 6.

  It is assumed that the magnetization direction of the servo signal 6 and the magnetization direction by the pre-processing are not exactly opposite directions but are slightly shifted. For example, it is assumed that the magnetization direction of the servo signal 6 is −120 ° and the magnetization direction in the pre-processing is 50 ° (see FIG. 4). Even in such a case, it is sufficient that the reproduced waveform of the servo signal 6 has symmetry such that the servo signal 6 can be appropriately read. The fact that the reproduced waveform of the servo signal 6 has symmetry means that the magnetization direction (first direction) of the servo signal 6 and the magnetization direction (second direction) of the pre-processing are opposite to each other. It indicates that.

  The determination of whether the reproduced waveform of the servo signal 6 has symmetry or the reproduced waveform is asymmetric will be described. For example, if the difference between the maximum voltage value Vmax and the minimum voltage value Vmin (absolute value) of the reproduced waveform is within an allowable range (about 5% to 10%) with respect to the amplitude of the reproduced waveform, the reproduced waveform becomes It is determined that they have symmetry.

<Various Examples and Comparative Examples>
Next, various examples and various comparative examples according to the present technology will be described. FIG. 6 is a diagram illustrating various examples and various comparative examples according to the present technology.

  The present inventors first prepared a total of five types of magnetic tapes 1 as the magnetic tape 1, a non-oriented tape 1A, a non-oriented tape 1B, a vertically oriented tape 1C, a vertically oriented tape 1D, and a longitudinally oriented tape 1E. did. The non-oriented tape 1A contains non-oriented barium ferrite as magnetic powder, and has a squareness ratio in the longitudinal direction of 0.6. The non-oriented tape 1B contains non-oriented barium ferrite as magnetic powder, and has a squareness ratio in the longitudinal direction of 0.42. The vertically oriented tape 1C contains vertically oriented barium ferrite as magnetic powder, and has a squareness ratio in the longitudinal direction of 0.22. The vertically oriented tape 1D includes a vertically oriented acicular metal as magnetic powder, and has a squareness ratio in the longitudinal direction of 0.3. The longitudinally oriented tape 1E contains longitudinally oriented needle-shaped metal as magnetic powder, and has a squareness ratio in the longitudinal direction of 0.88.

  The inventors performed preprocessing on these five types of magnetic tapes 1A to 1E while changing the angle of the permanent magnet 12a of the preprocessing unit 12, and recorded the servo signal 6. Regarding the non-oriented tape 1A, the angles of the permanent magnets 12a are 80 °, 70 °, 50 °, 24 °, −10 °, −20 °, and −40 °, and the pretreatment is performed at a total of 7 patterns of angles. It was conducted. Note that the angle of the permanent magnet 12a is set as a reference (0 °) when the N pole of the permanent magnet 12a faces the transport direction of the magnetic tape 1 (see FIG. 2).

  Further, for the non-oriented tape 1B, the angles of the permanent magnets 12a are 80 °, 50 °, 24 °, 20 °, 15 °, 0 °, −10 °, and −40 °, and the angles of the eight patterns in total Pretreatment was performed. For the vertically oriented tape 1C, the angles of the permanent magnets 12a were set to 30 °, 90 °, and 150 °, and the pretreatment was performed at three patterns of angles. With respect to the vertically oriented tape 1D, the angles of the permanent magnets 12a were 30 °, 90 °, and 150 °, and the pretreatment was performed at three patterns of angles. With respect to the longitudinally oriented tape 1E, the angles of the permanent magnets 12a were -50 °, 50 °, and 120 °, and pretreatment was performed at three patterns of angles.

  The inventors have determined whether the reproduced waveforms displayed on the screen have appropriate symmetry for all of the 24 patterns. In the example shown in FIG. 6, if the difference between the maximum voltage value Vmax and the minimum voltage value Vmin (absolute value) of the reproduced waveform is within 5% of the amplitude of the reproduced waveform, the reproduced waveform is symmetric. Was determined to have sex. An example was taken when the reproduced waveform had symmetry, and a comparative example was taken when the reproduced waveform had no symmetry.

  FIG. 7 is a diagram showing the relationship between the magnetization direction in the non-oriented tape 1 and the reproduced waveform.

  In the upper part of FIG. 7, the magnetization direction (first direction) of the servo signal 6 and the magnetization direction (second direction) of the preprocessing are appropriately opposite to each other, and the reproduction of the servo signal 6 is performed. An example in which the waveform has symmetry in the vertical direction (±) is shown. 7 shows the case where the magnetization direction of the servo signal 6 and the magnetization direction by the pre-processing are not appropriately opposite to each other, and the reproduced waveform of the servo signal 6 is under-biased. An example is shown. The lower part of FIG. 7 shows an example where the reproduced waveform of the servo signal 6 is overbiased.

  FIG. 8 is a diagram showing the relationship between the magnetization direction in the vertically oriented tape 1 and the reproduced waveform.

  The vertically oriented tape 1 shown in FIG. 8 has a higher degree of vertical orientation (smaller longitudinal squareness ratio) than the non-oriented tape 1 shown in FIG. Therefore, in the example shown in FIG. 8, the magnetization direction of the servo signal 6 is tilted more vertically than in the example shown in FIG.

  In the upper diagram of FIG. 8, the magnetization direction of the servo signal 6 and the magnetization direction by the pre-processing are appropriately opposite, and the reproduced waveform of the servo signal 6 has symmetry in the vertical direction (±). An example is shown in the case where the operation is performed. 8 shows a case where the magnetization direction of the servo signal 6 is not appropriately opposite to the magnetization direction of the pre-processing, and the reproduced waveform of the servo signal 6 is overbiased. An example is shown. The lower part of FIG. 8 shows an example where the reproduced waveform of the servo signal 6 is under-biased.

  Next, the inventors cut each magnetic tape 1 on which the servo signal 6 was recorded to a predetermined length, and measured the magnetization amount of the magnetic tape 1 using a vibration sample type magnetometer 20.

  FIG. 9 is a diagram showing the vibration sample type magnetometer 20.

  As shown in FIG. 9, the vibrating sample magnetometer 20 has a support rod 21 to which the magnetic tape 1 is attached at the lower end, and is attached to the upper end of the support rod 21 to vibrate the magnetic tape 1 (support rod 21). And a vibration rotator 22 for rotating while rotating. The vibrating sample magnetometer 20 is disposed at a position sandwiching the magnetic tape 1 and has a pair of magnetic field applying coils 23 for generating a magnetic field around the magnetic tape 1, and a plurality of magnetic coils 1 for measuring the amount of magnetization of the magnetic tape 1. And a pickup coil 24.

  One side surface of the magnetic tape 1 in the width direction is attached to the lower end of the support rod 21. Then, the magnetic tape 1 is rotated about the axis in the width direction as the central axis of rotation, and the magnetization amount is measured while being rotated.

  FIG. 10 is a top view illustrating a state in which the magnetic tape 1 is rotated and the magnetization amount of the magnetic tape 1 is measured according to the rotation.

  As shown in the uppermost part of FIG. 10, the reference (0 °) is when the longitudinal direction of the magnetic tape 1 is parallel to the direction of measurement of the amount of magnetization of the vibrating sample magnetometer 20. When the magnetic tape 1 is at an angle of 0 °, the direction of the transport direction during the processing of the magnetic tape 1 is a minus direction of the magnetization measurement direction. From this state, the magnetic tape 1 is rotated 360 degrees clockwise, and the magnetization amount of the magnetic tape 1 at each angle is measured.

  When the magnetization amount of the magnetic tape 1 is measured, the magnetization of the entire magnetic layer 4, that is, the mixed magnetization of the magnetization by the pre-processing (see the white arrow) and the magnetization by the servo signal 6 (see the black arrow) is Measured. Here, the servo signal 6 is recorded in a part of the servo band s in the magnetic layer 4. On the other hand, the magnetization due to the pre-processing exists throughout the servo band s and the data band d. Therefore, when viewed in the entire magnetic layer 4, the magnetization by the pre-processing is dominant, and the magnetization by the pre-processing is reflected in the measurement of the magnetization amount.

  FIG. 11 is a diagram showing a measurement result of the magnetization amount of the magnetic tape 1.

  The horizontal axis in FIG. 11 indicates the angle of the magnetic tape 1. The vertical axis of FIG. 11 indicates the ratio of the magnetization amount based on the maximum value of the magnetization amount of the magnetic tape 1. To further explain the vertical axis, for example, when the magnetization amount is measured by rotating the magnetic tape 1 and the magnetization amount reaches a maximum value at an angle of 160 °, the maximum value is used as a reference and The amount of magnetization is represented.

  FIG. 11 shows the measurement results of Comparative Example 1, Example 1, Example 2, Example 3, and Comparative Example 4 shown in FIG. These examples are common in that a non-oriented tape 1A (non-oriented barium ferrite, longitudinal squareness ratio 0.6) is used, but the angles of the permanent magnets 12a in the pretreatment are different (80 °). , 50 °, 24 °, -10 °, -40 °).

  For example, focusing on Comparative Example 1, the amount of magnetization takes the maximum value when the angle of the magnetic tape 1 is about 140 °. This indicates that in Comparative Example 1, the magnetization direction of the entire magnetic layer 4 is oriented at about 40 ° (see FIG. 4). Similarly, in Example 1, Example 2, Example 3, and Comparative Example 4, when the angle of the magnetic tape 1 is about 165 °, about 170 °, about 195 °, and about 225 °, the amount of magnetization is maximum. Take the value. Therefore, in Examples 1, 2, 3 and Comparative Example 4, the magnetization directions of the entire magnetic layer 4 are about 15 °, 10 °, −15 °, and −45 °.

  FIG. 6 shows the magnetization amount (%) (perpendicular magnetization amount (%)) when the angle of the magnetic tape 1 is 90 ° for each example and each comparative example. The magnetization amount (%) when the angle of the magnetic tape 1 is 90 ° is the magnetization amount in the perpendicular direction based on the maximum value of the magnetization amount when the magnetic tape 1 is rotated and the magnetization amount is measured. Is the ratio of

  Next, the squareness ratio will be described. FIG. 12 is a diagram showing a magnetization curve in the longitudinal direction and a magnetization curve in the vertical direction of the longitudinally oriented tape 1 and the perpendicularly oriented tape 1. As shown in FIG. 12, the squareness ratio is residual magnetization Mr / saturated magnetization Ms, and is a value indicating the easiness of remaining magnetization.

  The longitudinally oriented tape 1 has a large squareness ratio in the longitudinal direction (a direction parallel to the upper surface of the magnetic layer 4) and a small squareness ratio in the vertical direction. Therefore, the longitudinally oriented tape 1 is easily magnetized in the longitudinal direction and hardly magnetized in the vertical direction. On the other hand, the vertically oriented tape 1 has a large squareness ratio in the vertical direction and a small squareness ratio in the longitudinal direction. Therefore, the vertically oriented tape 1 is easily magnetized in the vertical direction and hardly magnetized in the longitudinal direction.

  FIG. 13 is a diagram illustrating the relationship between the squareness ratio in the longitudinal direction and the degree of vertical alignment. From FIG. 13, it is understood that the degree of orientation in the vertical direction increases as the squareness ratio in the longitudinal direction decreases, and the degree of orientation in the vertical direction decreases as the squareness ratio in the longitudinal direction increases.

  FIG. 14 is a diagram illustrating the relationship between the longitudinal squareness ratio and the perpendicular magnetization (%). The perpendicular magnetization (%) is a ratio of the magnetization in the vertical direction with reference to the maximum value of the magnetization when the magnetic tape 1 is rotated and the magnetization is measured (see FIG. 11). From FIG. 14, it can be seen that the smaller the squareness ratio in the longitudinal direction, the larger the magnetization amount (%) in the vertical direction, and the larger the squareness ratio in the longitudinal direction, the smaller the magnetization amount (%) in the vertical direction.

  FIG. 6 shows the product of the squareness ratio in the longitudinal direction and the perpendicular magnetization (%). As shown in FIG. 6, if the absolute value of the product of the squareness ratio in the longitudinal direction and the perpendicular magnetization (%) is 0.05 or more and 0.25 or less, the reproduced waveform of the servo signal 6 having good symmetry can be obtained. It can be seen that it can be obtained.

  The reason for using the product of the squareness ratio in the longitudinal direction and the perpendicular magnetization (%) will be described. FIG. 15 is a diagram for explaining the reason for using the product of the longitudinal squareness ratio and the perpendicular magnetization (%).

  The squareness ratio in the longitudinal direction is the ratio between the saturation magnetization Ms and the residual magnetization Mr in the longitudinal direction, and indicates the ease of magnetization in the longitudinal direction. In FIG. 15, the numbers in parentheses indicate the longitudinal squareness ratio. It is shown that the smaller the longitudinal squareness ratio, the stronger the vertical orientation degree (see FIG. 13).

  The first direction, which is the magnetization direction of the servo signal 6, is related to the degree of vertical orientation (longitudinal squareness ratio) and is determined according to the vertical orientation degree (longitudinal squareness ratio). In other words, the longitudinal squareness ratio is a parameter that determines the first direction (see the black arrow) that is the magnetization direction of the servo signal 6.

  On the other hand, the perpendicular magnetization (%) is a ratio of the magnetization in the vertical direction based on the maximum value of the magnetization when the magnetic tape 1 is rotated and the magnetization is measured (see FIG. 11). . The region of the magnetization by the preprocessing is sufficiently larger than the region of the magnetization of the servo signal 6. Therefore, the perpendicular magnetization (%) indicates the perpendicular component of the magnetization by the pre-processing. That is, the perpendicular magnetization (%) is a parameter that determines the second direction (see the white arrow) that is the magnetization direction in the pre-processing.

  As shown in FIGS. 14 and 15, as the perpendicular magnetization amount (%) increases (the white arrow approaches vertical), the longitudinal squareness ratio decreases. That is, the squareness ratio in the longitudinal direction and the perpendicular magnetization (%) are in a trade-off relationship.

  Accordingly, when the first direction, which is the magnetization direction of the servo signal 6, and the second direction, which is the magnetization direction obtained by the pre-processing, are appropriately opposite to each other, the longitudinal direction, which is a parameter for determining the first direction, is used. The absolute value of the product of the directional squareness ratio and the perpendicular magnetization (%) which is a parameter for determining the second direction is a value in a certain range. This range is the range of 0.05 or more and 0.25 or less.

<Method for reducing distortion in reproduced waveform of servo signal 6>
In the above description, when the magnetization direction of the servo signal 6 includes a component in the vertical direction, the problem that the reproduced waveform when the servo signal 6 is read becomes asymmetric in the vertical (±) direction is solved. The technology was explained. On the other hand, in the following description, a technique for solving the problem that the reproduction waveform of the servo signal 6 is distorted when the magnetization direction of the servo signal 6 includes a component in the vertical direction will be described.

  Here, when calculating the position information of the magnetic tape 1 based on the reproduced waveform of the servo signal 6, a method of calculating the position information based on the positive output peak value and the negative output peak value is generally used. . Therefore, the reproduced waveform of the servo signal 6 has a high output (the absolute value of the positive output peak value and the negative output peak value) in addition to the condition that the waveform has good symmetry in the vertical (±) direction. It is desirable to satisfy the condition that the value is high) and the condition that the waveform has no distortion.

  When the magnetization direction of the servo signal 6 includes a vertical component, the output of the reproduction waveform of the servo signal 6 can be made high, but there is a problem that the reproduction waveform of the servo signal 6 is easily distorted.

  On the other hand, if the servo signal 6 is recorded so as not to include a vertical component, distortion is less likely to occur in the reproduced waveform of the servo signal 6, but it is difficult to increase the output in the reproduced waveform of the servo signal 6. There is.

  In general, there is a method of recording the servo signal 6 so as not to include a vertical component, thereby reducing distortion in the reproduced waveform of the servo signal 6 at the expense of increasing the output of the reproduced waveform of the servo signal 6. Often used.

  However, even if the servo signal 6 is recorded so as to include the vertical component, if the distortion in the reproduction waveform of the servo signal 6 can be reduced, it is possible to increase the output by the reproduction waveform, and to achieve good reproduction without distortion. It is considered that obtaining a waveform can be compatible. Hereinafter, a technique for achieving both of these will be described in detail with a specific example.

  FIG. 16 is a perspective view of the servo signal recording unit 13 as viewed from the recording surface 13a side of the servo signal 6. As shown in FIG. 16, the servo signal recording section 13 has a recording surface 13a for recording the servo signal 6 on the magnetic tape 1 while being in contact with the magnetic layer 4 of the magnetic tape 1. On the recording surface 13a, five sets of magnetic gaps 32 are provided at positions corresponding to the five servo bands s0 to s4 in the magnetic layer 4 of the magnetic tape 1.

  The five sets of magnetic gaps 32 are arranged at predetermined intervals in a direction (Y-axis direction) orthogonal to the magnetic tape 1 transport direction (X-axis direction). Then, the servo signal 6 is recorded for the five servo bands s0 to s4 by the leakage magnetic field generated from the five magnetic gaps 32. Each of the five sets of magnetic gaps 32 is constituted by two magnetic gaps 32 arranged so as to be inclined in directions opposite to each other with a predetermined azimuth angle.

  The magnetic gap 32 is configured such that the gap (X-axis direction) of the gap itself is 1 μm or less. Hereinafter, the gap itself in the magnetic gap 32 is referred to as a gap length A (see FIG. 18).

  In the present embodiment, by recording the servo signal 6 with the leakage magnetic field generated from the magnetic gap 32 of 1 μm or less, the magnetization direction of the servo signal 6 includes a perpendicular component. In this embodiment, the output of the reproduced waveform of the servo signal 6 is increased by including the perpendicular component in the magnetization direction of the servo signal 6 in this manner.

  On the other hand, if the gap length A of the magnetic gap 32 is set to 1 μm or less and the vertical direction is simply included in the magnetization direction of the servo signal 6, the reproduced waveform of the servo signal 6 may be distorted.

  FIG. 17 is a diagram illustrating an example of a case where distortion has occurred in the reproduction waveform of the servo signal 6. As shown in FIG. 17, when the magnetization direction of the servo signal 6 includes a vertical component, two peak values may be generated on the positive output side. As described above, the generation of two peak values leads to erroneous detection of the peak position.

  In the present embodiment, in order to make the reproduced waveform of the servo signal 6 a good waveform without distortion, the thickness of the line of the servo signal 6 (corresponding to the spacing described later) is set to 1.2 μm or less. As described above, by setting the line thickness of the servo signal 6 to 1.2 μm or less, even if the servo signal 6 is recorded so as to include a vertical component, distortion in the reproduced waveform of the servo signal 6 can be reduced. it can. As a result, it is possible to achieve both an increase in the output based on the reproduced waveform and a favorable reproduced waveform without distortion.

  Here, the thickness of the line in the servo signal 6 will be described. FIG. 18 is a schematic diagram illustrating a state where the servo signal 6 is recorded by the servo signal recording unit 13. In FIG. 18, for convenience of description, only one magnetic gap 32 of two magnetic gaps 32 arranged at an angle with a predetermined azimuth angle is shown. Also, in FIG. 18, for convenience of description, the ratio of the gap length A to the entire size of the servo signal recording unit 13 is shown to be larger than the actual ratio.

  In the upper part of FIG. 18, supply of a pulse to the servo signal recording unit 13 is started at a predetermined time, and a leakage magnetic field is generated in the magnetic gap 32. This leakage magnetic field causes a part of the magnetic layer 4 to move forward. The state when magnetization is performed in a direction opposite to the magnetization direction by the processing is shown. The lower part of FIG. 18 illustrates a state where the supply of the pulse to the servo signal recording unit 13 is stopped at a predetermined time and the recording of one servo signal 6 is completed.

  As shown in FIG. 18, the magnetic tape 1 is moved at a predetermined transport speed along the transport direction of the magnetic tape 1. Then, as shown in the upper part of FIG. 18, when the supply of the pulse to the servo signal recording unit 13 is started at a predetermined time, a leakage magnetic field is generated in the magnetic gap 32, and at that moment, the magnetic gap 32 A part of the magnetic layer 4 is magnetized in a direction opposite to the magnetization direction by the pre-processing by a length corresponding to the gap length A of the above.

  Even after the supply of the pulse is started, the magnetic tape 1 is moved in the transport direction at a predetermined transport speed. Thus, even while the magnetic tape 1 is moving, a part of the magnetic layer 4 is magnetized in a direction opposite to the magnetization direction by the pre-processing due to the leakage magnetic field generated from the magnetic gap 32. The length of the magnetic layer 4 magnetized with the movement of the magnetic tape 1 is set to a length corresponding to (pulse supply period) × (conveyance speed of the magnetic tape 1). Hereinafter, the length corresponding to (pulse supply period) × (conveyance speed of magnetic tape 1) is referred to as recording current distance B.

  As understood from the above description, the thickness of the line in the servo signal 6 corresponds to a value obtained by adding the gap length A of the magnetic gap 32 and the recording current distance B (see the lower diagram in FIG. 18). ). In this embodiment, the pulse supply period (clk) is adjusted in order to record the servo signal 6 having a line thickness of 1.2 μm or less on the magnetic layer 4.

  Here, the thickness of the line of the servo signal 6 corresponds to a value obtained by adding the gap length A of the magnetic gap 32 and the recording current distance B, but a slight difference occurs between them. This is for the following reason.

  Referring to FIG. 18, attention is paid to a boundary (two places) where the magnetization direction is reversed between the first direction (see the black arrow) and the second direction (see the white arrow). In this boundary region (having a predetermined length), the magnetization direction of the magnetic powder contained in this region is not oriented in a fixed direction, but is oriented in the second direction or in the first direction. Or Due to this, a slight shift occurs between the line thickness of the servo signal 6 and the value obtained by adding the gap length A and the recording current distance B.

  Here, in the present embodiment, the thickness of the line of the servo signal 6 is set to be very thin (1.2 μm or less). For this reason, it is difficult to measure this thickness by observation by imaging. On the other hand, the thickness of the line of the servo signal 6 can be obtained from the reproduced waveform of the servo signal 6.

  FIG. 19 is a diagram showing a reproduction waveform when the servo signal 6 recorded on the magnetic layer 4 is read by the reproduction head unit 14. As shown in FIG. 19, in the reproduced waveform of the servo signal 6, two peak values (a positive output peak value and a negative output peak value) occur at positions corresponding to the boundary where the magnetization direction is reversed.

  In the present embodiment, a value obtained by converting the time indicated by the interval between the adjacent positive output peak value and negative output peak value into a distance is referred to as spacing. That is, spacing = (time indicated by the interval between the positive output peak value and the negative output peak value) × (the transport speed of the magnetic tape 1). This spacing corresponds to the thickness of the line in the servo signal 6. That is, in the present embodiment, the spacing is set to 1.2 μm or less.

  This spacing can be determined, for example, as follows. First, the reproduced waveform of the servo signal 6 is digitized by the data collection board to determine the output peak value of the reproduced waveform, and then the difference between the time when the positive output peak value is obtained and the time when the negative output peak value is obtained is obtained. Thereafter, an average value of n (for example, n = 30) differences is obtained, and the average value is multiplied by the transport speed of the magnetic tape 1 to obtain the spacing.

  Hereinafter, the reason why the line thickness (that is, spacing) of the servo signal 6 is set to 1.2 μm or less will be described.

  The present inventors conducted an experiment on how much the line thickness (that is, spacing) of the servo signal 6 can be reduced to obtain a good reproduced waveform without distortion. FIG. 20 is a diagram showing the results of this experiment.

  In this experiment, the present inventors first prepared a plurality of servo signal recording units 13 in which the gap lengths A of the magnetic gaps 32 were different. Specifically, four servo signal recording units 13 were prepared in which the gap lengths A of the magnetic gaps 32 were 0.71 μm, 0.81 μm, 1.1 μm, and 1.22 μm, respectively.

  Next, the present inventors differed the recording current distance B by varying the pulse supply time (clk) for each of the plurality of servo signal recording units 13, thereby reducing the line thickness. Different servo signals 6 were recorded on the magnetic layer 4. Specifically, the supply times of the pulses were set to 1 clk, 2 clk, 2.5 clk, and 3 clk. When the pulse supply time is 1 clk, 2 clk, 2.5 clk, and 3 clk, the recording current distance B (= pulse supply time × conveyance speed of magnetic tape 1) is 0.25 μm, 0.5 μm, 0.625 μm and 0.75 μm.

  FIG. 20 shows a reproduced waveform when the servo signal 6 recorded on the magnetic tape 1 under different conditions is read by the reproducing head unit 14.

  In FIG. 20, the reproduced waveforms 9a to 9d, 9e to 9h, 9i to 9l, and 9m to 9p arranged in a vertical line have gap lengths A of 0.71 μm, 0.81 μm, 1.1 μm, The waveform when the servo signal 6 is recorded on the magnetic layer 4 by the leakage magnetic field from the magnetic gap 32 of 1.22 μm and the servo signal 6 is read is shown.

  In FIG. 20, the reproduced waveforms 9a to 9m, 9b to 9n, 9c to 9o, and 9d to 9p arranged in a horizontal line are sequentially determined by the supply times of the pulses 1clk, 2clk, 2.5clk, and 3clk. 6 shows a waveform when a servo signal 6 signal is recorded on the magnetic layer 4 and the servo signal 6 is read.

  The outputs of the reproduced waveforms 9a to 9p are, respectively, 0.995V, 0.940V, 0.935V, 0.920V, 0.905V, 0.920V, 0.890V, 0.890V, and 0.995V. 855V, 0.870V, 0.870V, 0.840V, 0.825V, 0.795V, 0.779V, 0.770V.

  For the reproduced waveforms 9a to 9p, the spacings (that is, the line thickness of the servo signal 6) are 0.877 μm, 1.009 μm, 1.098 μm, 1.234 μm, 0.911 μm, and 1.052 μm, respectively. , 1.14 μm, 1.262 μm, 1.219 μm, 1.319 μm, 1.413 μm, 1.567 μm, 1.373 μm, 1.427 μm, 1.484 μm and 1.655 μm.

  Referring to FIG. 20, it can be seen that the output of the reproduced waveform increases as the gap length A of the magnetic gap 32 decreases. This is because the perpendicular component in the magnetization direction gradually increases as the gap length A of the magnetic gap 32 decreases. In particular, when the gap length A of the magnetic gap 32 is 1 μm or less, a clear perpendicular component is included in the magnetization direction of the servo signal 6.

  Therefore, in the present embodiment, the gap length A of the magnetic gap 32 is set to 1 μm or less to include a perpendicular component in the magnetization direction of the servo signal 6, thereby improving the output of the reproduced waveform of the servo signal 6.

  If the gap length A of the magnetic gap 32 is the same, the output of the servo signal 6 increases as the pulse supply time (clk) decreases.

  On the other hand, the distortion of the reproduction waveform of the servo signal 6 will be described. The characteristic is that as the gap length A of the magnetic gap 32 becomes narrower and the vertical component in the magnetization direction becomes gradually larger, the waveform becomes more easily distorted. Referring to the four reproduced waveforms 9d, 9h, 9l, and 9p shown at the bottom of FIG. 20, as the gap length A of the magnetic gap 32 becomes narrower and the vertical component in the magnetization direction gradually increases, the reproduced waveform becomes larger. It can be seen that the distortion of is large.

  Particularly, in the reproduced waveforms 9d and 9h, the distortion of the reproduced waveform is large, and two peak values are generated on the positive output side. As described above, the generation of two peak values leads to erroneous detection of the peak position.

  However, the reproduced waveform is characterized in that the shorter the pulse supply time and the shorter the spacing (thickness of the line of the servo signal 6), the smaller the distortion. In the present embodiment, utilizing this relationship, it is possible to achieve both high output of the reproduced waveform and obtain a good reproduced waveform without distortion.

  Here, attention is paid to the reproduction waveform 9d and the reproduction waveform 9c. In the reproduced waveform 9d, the spacing (the thickness of the line of the servo signal 6) is 1.234 μm, and the spacing is too long, and the reproduced waveform of the servo signal 6 is distorted. On the other hand, as shown in the reproduction waveform 9c, when the pulse supply time becomes short (2.5 clk) and the spacing (thickness of the line of the servo signal 6) becomes 1.098 μm, the reproduction waveform becomes distorted. It is a good waveform without any.

  Similarly, focusing on the reproduced waveform 9h and the reproduced waveform 9g, in the reproduced waveform 9h, the spacing (the thickness of the line of the servo signal 6) is 1.262 μm, and the spacing is too long. The waveform is distorted. On the other hand, when the pulse supply time is short (2.5 clk) and the spacing (thickness of the line of the servo signal 6) is 1.14 μm, the reproduced waveform is a good waveform without distortion.

  From this result, even if the gap length A is 1 μm and the magnetization direction of the servo signal 6 includes a perpendicular component, if the spacing (thickness of the line of the servo signal 6) is 1.2 μm or less, distortion can be reduced. It is considered that no good reproduced waveform can be obtained.

  Therefore, in the present embodiment, the spacing (the thickness of the line of the servo signal 6) is set to 1.2 μm or less. By setting the spacing to 1.1 μm or less, it is considered that a good reproduced waveform without further distortion can be obtained (see reproduced waveforms 9a, 9b, 9c, 9e, 9f). By setting the spacing to 1.0 μm or less, it is considered that a good reproduced waveform without further distortion can be obtained (see reproduced waveforms 9a and 9e).

  FIG. 21 is a diagram showing the relationship between the gap length A in the magnetic gap 32 and the output of the servo signal 6 in the reproduced waveform.

  As shown in FIG. 21, as the gap length A of the magnetic gap 32 becomes narrower, the output of the reproduced waveform of the servo signal 6 becomes higher. If the gap length A is the same, the output of the servo signal 6 increases as the pulse supply time (clk) decreases.

  In FIG. 21, the plot in the case where the gap length A exceeds 1 μm is surrounded by a broken line. On the other hand, the plot when the gap length A is 1 μm or less is surrounded by a solid line.

  FIG. 22 is a diagram showing the relationship between the gap length A in the magnetic gap 32 and the spacing (the thickness of the line of the servo signal 6).

  As shown in FIG. 22, as the gap length A in the magnetic gap 32 increases, the spacing (thickness of the line of the servo signal) increases. If the gap length A is the same, the spacing (thickness of the line of the servo signal 6) becomes shorter as the pulse supply time (clk) becomes shorter.

  In FIG. 22, a plot in the case where the gap length A in the magnetic gap 32 exceeds 1 μm is surrounded by a broken line. Further, although the gap length A in the magnetic gap 32 is 1 μm or less, the spacing exceeds 1.2 μm, and a plot in a case where distortion occurs in the reproduced waveform is surrounded by a dashed line. Further, in FIG. 22, a plot in the case where the gap length A in the magnetic gap 32 is 1 μm or less and the spacing (thickness of the line of the servo signal 6) is 1.2 μm or less is surrounded by a solid line. . With respect to the plot within the range surrounded by the solid line, it is possible to achieve both high output of the reproduced waveform and obtain a good reproduced waveform without distortion.

  In the above description, the case where the reproduction waveform of the servo signal 6 is reproduced by the reproduction head unit 14 provided in the servo signal recording device 100 has been described. On the other hand, the reproduced waveform of the servo signal 6 may be reproduced by a reproducing head provided in a device separate from the servo signal recording device 100.

<Various modifications>
The present technology can also employ the following configurations.
(1) A part of the magnetic layer is magnetized in a first direction including a vertical component perpendicular to the upper surface of the magnetic layer to record a servo signal, and before the servo signal is recorded, A magnetic recording medium comprising: a magnetic layer including a component in a vertical direction and magnetized in a second direction opposite to the first direction.
(2) The magnetic recording medium according to the above (1),
The ratio of the amount of magnetization in the perpendicular direction with respect to the maximum value of the amount of magnetization when the amount of magnetization is measured by rotating the magnetic recording medium, and the squareness ratio of the magnetic layer in the longitudinal direction parallel to the upper surface. A magnetic recording medium having an absolute value of the product of 0.05 to 0.25.
(3) The magnetic recording medium according to (1) or (2),
The magnetic recording medium, wherein the magnetic layer contains non-oriented or vertically oriented magnetic powder inside.
(4) The magnetic recording medium according to (3) above,
The magnetic powder is barium ferrite or a needle-shaped metal.
(5) By applying a magnetic field to a part of the magnetic layer of the magnetic recording medium, the part of the magnetic layer is magnetized in a first direction including a vertical component perpendicular to the upper surface of the magnetic layer. A servo signal recording unit for recording a servo signal by
Before the servo signal is recorded by the servo signal recording unit, by applying a magnetic field to the magnetic layer, including the component in the vertical direction, the second direction in the second direction opposite to the first direction, A servo signal recording device comprising: a preprocessing unit for magnetizing a magnetic layer.
(6) The servo signal recording device according to (5),
The servo signal recording device, wherein the preprocessing unit includes a magnet that is rotatable and that can change a magnetic field applied to a magnetic layer according to the rotation.
(7) By applying a magnetic field to a part of the magnetic layer of the magnetic recording medium, the part of the magnetic layer is magnetized in a first direction including a vertical component perpendicular to the upper surface of the magnetic layer. And record the servo signal,
By applying a magnetic field to the magnetic layer before the servo signal is recorded, the magnetic layer is magnetized in a second direction opposite to the first direction, including the component in the vertical direction. A method for manufacturing a magnetic recording medium.
(8) A magnetic layer on which a servo signal is recorded by a leakage magnetic field of a magnetic gap having a gap of 1 μm or less, and positive output peaks adjacent to each other in a reproduction waveform when the servo signal is read. And a distance indicated by the interval between the negative output peaks is 1.2 μm or less.
(9) The magnetic recording medium according to (8),
The magnetic recording medium, wherein the distance indicated by the interval between the adjacent positive output peak and the negative output peak is 1.1 μm or less.
(10) The magnetic recording medium according to (9),
The magnetic recording medium, wherein the distance indicated by the interval between the adjacent positive output peak and the negative output peak is 1.0 μm or less.
(11) The magnetic recording medium according to any one of (8) to (10),
In the magnetic layer, a part of the magnetic layer is magnetized in a first direction including a component in a vertical direction perpendicular to an upper surface thereof, the servo signal is recorded, and before the servo signal is recorded, A magnetic recording medium which is magnetized in a second direction opposite to the first direction, including the component in the perpendicular direction.
(12) The distance between adjacent positive output peaks and negative output peaks in a reproduced waveform when a servo signal recorded on a magnetic layer of a magnetic recording medium is read is 1.2 μm or less. A servo signal recording device comprising: a servo signal recording unit for recording the servo signal on the magnetic layer by a leakage magnetic field of a magnetic gap having a gap itself of 1 μm or less.
(13) The distance between adjacent positive output peaks and negative output peaks in a reproduction waveform when a servo signal recorded on a magnetic layer of a magnetic recording medium is read is 1.2 μm or less. A method of manufacturing a magnetic recording medium, wherein the servo signal is recorded on the magnetic layer by a leakage magnetic field of a magnetic gap having a gap of 1 μm or less.

DESCRIPTION OF SYMBOLS 1 ... Magnetic tape 2 ... Base material 3 ... Non-magnetic layer 4 ... Magnetic layer 6 ... Servo signal 12 ... Pre-processing part 12a ... Permanent magnet 13 ... Servo signal recording part 14 ... Reproduction head part 20 ... Vibration sample type magnetometer 100 ... Servo signal recording device

Claims (6)

Base material, a non-magnetic layer laminated on the substrate, including a plurality of servo bands, a magnetic recording medium having a magnetic layer laminated on the non-magnetic layer,
In the magnetic layer, a part of the magnetic layer is magnetized in a first direction including a component in a vertical direction perpendicular to the upper surface of the magnetic layer, a servo signal is recorded, and before the servo signal is recorded, , Including a component in the vertical direction, magnetized in a second direction opposite to the first direction,
The magnetic recording medium in which the servo signal is recorded, the ratio of the amount of magnetization in the perpendicular direction based on the maximum value of the amount of magnetization when rotating the magnetic recording medium and measuring the amount of magnetization, A magnetic recording medium, wherein an absolute value of a product of the magnetic layer and a squareness ratio in a longitudinal direction parallel to the upper surface is 0.05 or more and 0.25 or less. The magnetic recording medium according to claim 1,
The magnetic recording medium, wherein the magnetic layer contains non-oriented or vertically oriented magnetic powder inside. The magnetic recording medium according to claim 2, wherein
The magnetic powder is barium ferrite or a needle-shaped metal. A base, a non-magnetic layer laminated on the substrate, including a plurality of servo bands, perpendicular to an upper surface of the magnetic layer in a magnetic recording medium having a magnetic layer laminated on the non-magnetic layer; A servo signal recording unit that magnetizes a part of the plurality of servo bands in a first direction including a vertical component, and records a servo signal in each of the plurality of servo bands;
And a pre-processing unit that magnetizes the magnetic layer in a second direction opposite to the first direction, including the component in the vertical direction, before the servo signal is recorded. And
The magnetic recording medium in which the servo signal is recorded, the ratio of the amount of magnetization in the perpendicular direction based on the maximum value of the amount of magnetization when rotating the magnetic recording medium and measuring the amount of magnetization, A servo signal recording device, wherein an absolute value of a product of the magnetic layer and a squareness ratio in a longitudinal direction parallel to the upper surface is 0.05 or more and 0.25 or less. The servo signal recording device according to claim 4, wherein
The servo signal recording device, wherein the preprocessing unit includes a magnet that is rotatable and that can change a magnetic field applied to a magnetic layer according to the rotation. A base, a non-magnetic layer laminated on the substrate, including a plurality of servo bands, perpendicular to an upper surface of the magnetic layer in a magnetic recording medium having a magnetic layer laminated on the non-magnetic layer; Magnetizing a part of the plurality of servo bands in a first direction including a vertical component, and recording a servo signal in each of the plurality of servo bands;
A method for manufacturing a magnetic recording medium, comprising: magnetizing the magnetic layer in a second direction opposite to the first direction, including the component in the vertical direction, before recording the servo signal.
The magnetic recording medium in which the servo signal is recorded, the ratio of the amount of magnetization in the perpendicular direction based on the maximum value of the amount of magnetization when rotating the magnetic recording medium and measuring the amount of magnetization, A method for manufacturing a magnetic recording medium, wherein the absolute value of the product of the magnetic layer and the squareness ratio in the longitudinal direction parallel to the upper surface is 0.05 or more and 0.25 or less.