JP2022066533A - Magnetic recording medium, servo signal recording device and magnetic recording medium manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technology that can obtain a reproduced waveform of a servo signal with excellent symmetry in a case where a magnetization direction of the servo signal contains a component in a perpendicular direction.

SOLUTION: In a magnetic recording medium manufacturing method according to the present technology, a magnetic layer is magnetized in a direction different from a magnetization direction of a servo signal by a magnet rotatable and capable of changing a direction of a magnetic field to be applied to the magnetic layer in response to rotation before the servo signal is recorded, and a magnetic recording medium having the servo signal recorded is such that an absolute value of a product of a ratio of a magnetization quantity in a perpendicular direction perpendicular to a top surface of the magnetization layer when a maximum value of the magnetization quantity upon measuring the magnetization quantity with the magnetic recording medium caused to rotate is a reference and a squareness ratio of the magnetization layer in a longitudinal direction parallel with the top surface of the magnetization layer is equal to or more than 0.05 and less than 0.25, and a reproduced waveform when reading the servo signal is symmetric in a vertical direction (±).

SELECTED DRAWING: Figure 2

COPYRIGHT: (C)2022,JPO&INPIT

Description

This technique relates to a technique 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 long in one direction, and data is recorded on these recording tracks. In recent years, in order to realize high-density recording of data, a method of narrowing the distance between recording tracks has been used.

On the other hand, if the distance between the recording tracks is narrowed, there is a problem that the magnetic head cannot accurately align with the recording track when the magnetic head reads / writes data to / from the recording track. Therefore, generally, a method of recording a servo signal at a predetermined position between recording tracks is adopted. The data recording magnetic head can accurately align with the recording track by reading the servo signal recorded on the magnetic layer.

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

The following Patent Document 1 is mentioned as a technique related to the present application.

Japanese Unexamined Patent Publication No. 2005-166230.

In the case of the horizontal magnetic recording method, the magnetization direction of the servo signal recorded on the magnetic layer is in the horizontal direction. In this case, the reproduced waveform when the servo signal is read is symmetrical in the vertical (±) direction. On the other hand, in the case of the perpendicular magnetic recording method, when the servo signal is recorded on the magnetic layer, the magnetization direction of the servo signal includes a component in the vertical direction. In this way, when the magnetization direction of the servo signal includes a component in the vertical direction, there is a problem that the reproduced waveform when the servo signal is read becomes asymmetric in the vertical (±) direction unless some measures are taken. ..

In view of the above circumstances, an object of the present technology is 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 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 containing a component in a vertical direction perpendicular to the upper surface of the magnetic layer, and a servo signal is recorded, and before the servo signal is recorded. , Magnetized in a second direction opposite to the first direction, including the vertical component.

As a result, the magnetization direction of the servo signal recorded in the magnetization layer (first direction: including the vertical component) and the magnetization direction of the magnetic layer by the pretreatment (second direction: including the vertical component). ) And the opposite directions. In this way, by making the magnetization direction of the servo signal and the magnetization direction of the magnetic layer by the pretreatment opposite to each other, it is possible to obtain a reproduced waveform of the servo signal having good symmetry.

The magnetic recording medium has a ratio of the amount of magnetization in the vertical direction when the maximum value of the amount of magnetization when the amount of magnetization is measured by rotating the magnetic recording medium as a reference, and the ratio of the amount of magnetization in the longitudinal direction parallel to the upper surface. The absolute value of the product of the magnetic layer with the square ratio may be 0.05 or more and 0.25 or less.

As a result, it is possible to obtain a reproduced waveform of the servo signal having good symmetry.

In the magnetic recording medium, the magnetic layer may contain non-oriented or vertically oriented magnetic powder inside.

In the magnetic recording medium, the magnetic powder may be barium ferrite or 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, so that the magnetic layer contains a component in a vertical direction perpendicular to the upper surface of the magnetic layer. A part is magnetized and the servo signal is recorded.
By applying a magnetic field to the magnetic layer before the servo signal is recorded by the servo signal recording unit, the preprocessing unit contains the vertical component and is in a direction opposite to the first direction. The magnetic layer is magnetized in the second direction.

In the servo signal recording device, the preprocessing unit may have a magnet.
The magnet is rotatable and can change the magnetic field applied to the magnetic layer in response to the rotation.

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

The method for manufacturing a magnetic recording medium according to the present technology is a first direction including a component in a vertical direction perpendicular to the upper surface of the magnetic layer by applying a magnetic field to a part of the magnetic layer of the magnetic recording medium. Includes magnetizing a portion of the magnetic layer to record a 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, which includes the vertical component. Ru.

As described above, according to the present technique, 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 which shows the servo signal recording apparatus which concerns on one Embodiment of this technique. It is a partially enlarged view which shows a part of a servo signal recording apparatus. It is a top view which shows the magnetic tape which recorded the servo signal. It is a figure which shows the direction of the magnetization of a magnetic tape. It is a figure which shows the relationship between the magnetization direction, and the reproduction waveform of a servo signal. It is a figure which shows various examples and various comparative examples. It is a figure which shows the relationship between the magnetization direction in a non-oriented tape, and a reproduction waveform. It is a figure which shows the relationship between the magnetization direction in the vertical alignment tape, and the reproduction waveform. It is a figure which shows the vibration sample type magnetometer. It is a top view which shows the state when the magnetic tape is rotated, and the magnetizing amount of the magnetic tape is measured according to the rotation. It is a figure which shows the measurement result of the magnetization amount of a magnetic tape. It is a figure which shows the magnetization curve in the longitudinal direction of the longitudinal alignment tape and the vertical alignment tape, and the magnetization curve in the vertical direction. It is a figure which shows the relationship between the longitudinal angle ratio and the degree of vertical orientation. It is a figure which shows the relationship between the longitudinal angular ratio and the vertical magnetization amount (%). It is a figure for demonstrating the reason why the product of a longitudinal angle ratio and a vertical magnetization amount (%) is used. It is a perspective view which looked at the servo signal recording part from the recording surface side of a servo signal. It is a figure which shows an example of the case where the reproduction waveform of a servo signal is distorted. It is a schematic diagram which shows the state that the servo signal is recorded by the servo signal recording unit. It is a figure which shows the reproduction waveform when the servo signal recorded in the magnetic layer is read by the reproduction head part. It is a figure which shows the experimental result at the time of performing an experiment about how thin the line thickness in a servo signal should be made to obtain a good reproduction waveform without distortion. It is a figure which shows the relationship between the gap length in a magnetic gap, and the output in the reproduction waveform of a servo signal. It is a figure which shows the relationship between the gap length in a magnetic gap, and spacing (thickness of a line of a servo signal).

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

<Structure 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. 2 and 3. As shown in these figures, the magnetic tape 1 includes a tape-shaped base material 2 long 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. Includes 4 and.

As the material of the base material 2, for example, polyethylene terephthalate (PET), polyethylene naphthalate (PEN) and the like are used. The non-magnetic layer 3 contains, for example, α-Fe ₂ O ₃ , polyurethane and the like. The magnetic layer 4 is a ferromagnetic metal film containing magnetic powder inside. As the magnetic powder, for example, non-oriented or vertically oriented barium ferrite, vertically oriented needle-shaped metal, or the like 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 long in the longitudinal direction, and data is recorded for each recording track 5. The servo band s includes a servo signal 6 having a predetermined pattern recorded by the servo signal recording device 100. For example, the 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 includes a feeding roller 11, a preprocessing unit 12, a servo signal recording unit 13, a reproduction head unit 14, and the like, in order from the upstream side in the transport direction of the magnetic tape 1. A take-up roller 15 is provided. Although not shown, the servo signal recording device 100 stores a control unit that collectively controls each part 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 delivery roller 11 is capable of rotatably supporting the roll-shaped magnetic tape 1 (before recording the servo signal 6). The feeding roller 11 is rotated according to the drive of a drive source such as a motor, and the magnetic tape 1 is fed toward the downstream side 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 synchronization with the delivery roller 11 in response to the drive of a drive source such as a motor, and winds up the magnetic tape 1 on which the servo signal 6 is recorded in accordance with the rotation. The feeding roller 11 and the winding 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 arranged, for example, on the upper side (magnetic layer 4 side) of the magnetic tape 1. The servo signal recording unit 13 may be arranged on the lower side (base material 2 side) of the magnetic tape 1. The servo signal recording unit 13 generates a magnetic field at a predetermined timing in response to the pulse signal of the square wave, and applies the magnetic field to a part of the magnetic layer 4 (after pretreatment) of the magnetic tape 1.

As a result, the servo signal recording unit 13 magnetizes a part of the magnetic layer 4 in the first direction and records the servo signal 6 on the magnetic layer 4 (see the 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 under the servo signal recording unit 13.

The first direction, which is the magnetization direction of the servo signal 6, includes a vertical component perpendicular to the upper surface of the magnetic layer 4. That is, in the present embodiment, since the magnetic powder in vertical orientation or non-orientation is contained in the magnetic layer 4, the servo signal 6 recorded in the magnetic layer 4 contains a 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 the present specification, the direction of magnetization is based on the angle (0 °) when the direction of magnetization faces the transport direction of the magnetic tape 1, and the angle increases in the clockwise direction. It is considered to be the 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 the pretreatment described later and the magnetization direction of the entire magnetic layer 4.

The preprocessing unit 12 is arranged on the lower side (base material 2 side) of the magnetic tape 1 on the upstream side of the servo signal recording unit 13, for example. The pretreatment unit 12 may be arranged on the upper side (magnetic layer 4 side) of the magnetic tape 1. The pretreatment unit 12 includes a permanent magnet 12a that can rotate with the Y-axis direction (the width direction of the tape 1) as the central axis of rotation. The shape of the permanent magnet 12a is, for example, a cylindrical shape or a polygonal prism shape, but is not limited to these.

Before the servo signal 6 is recorded by the servo signal recording unit 13, the permanent magnet 12a applies a magnetic field to the entire magnetic layer 4 by a DC magnetic field to degauss the entire magnetic layer 4. As a result, the permanent magnet 12a can pre-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 making the two magnetization directions opposite to each other in this way, the reproduced waveform of the servo signal 6 when the servo signal 6 is read can be made symmetrical in the vertical direction (±) (see FIG. 5).

The magnetization direction (first direction) of the servo signal 6 differs depending on the square ratio of the magnetic layer 4 (see FIG. 12). For example, vertically oriented barium ferrite, non-oriented barium ferrite, and vertically oriented needle-like metal typically have different square 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 square ratio is the same and the conditions of the servo signal recording unit 13 are 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 depending on the square ratio of the magnetic layer 4, the magnetization direction (second direction) by the pretreatment is also different in order to match the magnetization direction of the servo signal 6. There is a need.

Therefore, in the present embodiment, the permanent magnet 12a can rotate with the axis in the Y-axis direction as the central axis of rotation. Thereby, the magnetization direction (second direction) by the pretreatment 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. It is considered to be the 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 regardless of the second direction as long as the square ratio of the magnetic layer 4 is the same.

The reproduction head unit 14 is arranged on the upper side (magnetic layer 4 side) of the magnetic tape 1 on the downstream side of the servo signal recording unit 13. The reproduction head unit 14 reads the servo signal 6 from the magnetic layer 4 of the magnetic tape 1 which has been preprocessed by the preprocessing unit 12 and has the servo signal 6 recorded by the servo signal recording unit 13. 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 reproduction head unit 14 detects the magnetic flux generated from the surface of the servo band s when the magnetic layer 4 passes under the reproduction head unit 14. The magnetic flux detected at this time becomes the reproduction waveform of the servo signal 6.

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

As shown in FIG. 5, in the present embodiment, the magnetization direction of the servo signal 6 and the magnetization direction by the preprocessing are opposite to each other. Therefore, the reproduction waveform of the servo signal 6 when the servo signal 6 is read. 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 contains a magnetization component in the vertical direction.

Further, in the present embodiment, the amount of magnetic flux generated in the vicinity of 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. As a result, a high-output reproduced waveform can be obtained even when the thickness of the magnetic layer 4 is thin.

Here, the magnetization direction (first direction) of the servo signal 6 and the magnetization direction (second direction) by the pretreatment do not have to be exactly 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 due to the preprocessing are not exactly opposite directions but are slightly deviated from each other. For example, assume that the magnetization direction of the servo signal 6 is −120 ° and the magnetization direction by preprocessing is 50 ° (see FIG. 4). Even in such a case, it is sufficient that the reproduced waveform of the servo signal 6 has symmetry to the extent 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 by preprocessing (second direction) are opposite to each other. It shows that it is.

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 of the reproduction waveform and the minimum voltage value Vmin (absolute value) is within the allowable range (about 5% to 10%) with respect to the amplitude of the reproduction waveform, the reproduction waveform is It is judged to have symmetry.

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

First, the present inventors prepare a total of five types of magnetic tape 1 as the magnetic tape 1, including the non-aligned tape 1A, the non-aligned tape 1B, the vertically oriented tape 1C, the vertically oriented tape 1D, and the longitudinally oriented tape 1E. bottom. The non-oriented tape 1A contains unoriented barium ferrite as a magnetic powder, and has a rectangular ratio in the longitudinal direction of 0.6. The non-oriented tape 1B contains unoriented barium ferrite as a magnetic powder and has a rectangular ratio in the longitudinal direction of 0.42. The vertically oriented tape 1C contains barium ferrite that is vertically oriented as a magnetic powder, and has a rectangular ratio in the longitudinal direction of 0.22. The vertically oriented tape 1D contains vertically oriented needle-shaped metal as magnetic powder, and has a rectangular ratio in the longitudinal direction of 0.3. The longitudinally oriented tape 1E contains a longitudinally oriented needle-like metal as a magnetic powder, and has a rectangular ratio in the longitudinal direction of 0.88.

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

For the non-oriented tape 1B, the angles of the permanent magnets 12a are 80 °, 50 °, 24 °, 20 °, 15 °, 0 °, -10 °, and -40 °, for a total of 8 patterns of angles. Pretreatment was done in. For the vertically oriented tape 1C, the angles of the permanent magnets 12a were set to 30 °, 90 °, and 150 °, and pretreatment was performed at three patterns of angles. For the vertically oriented tape 1D, the angles of the permanent magnets 12a were set to 30 °, 90 °, and 150 °, and pretreatment was performed at three patterns of angles. For the longitudinally oriented tape 1E, the angles of the permanent magnets 12a were set to −50 °, 50 °, and 120 °, and pretreatment was performed at three patterns of angles.

Then, the inventors determined whether the reproduced waveform displayed on the screen had appropriate symmetry for all 24 patterns. In the example shown in FIG. 6, if the difference between the maximum voltage value Vmax of the reproduced waveform and the minimum voltage value Vmin (absolute value) is within the range of 5% with respect to the amplitude of the reproduced waveform, the reproduced waveform is symmetrical. It was judged to have sex. When the reproduced waveform has symmetry, it is regarded as an example, and when the reproduced waveform does not have symmetry, it is regarded as a comparative example.

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

In the upper figure of FIG. 7, the magnetization direction (first direction) of the servo signal 6 and the magnetization direction (second direction) due to the preprocessing are appropriately opposite to each other, and the servo signal 6 is reproduced. An example is shown in which the waveform has symmetry in the vertical direction (±). In the central figure of FIG. 7, when the magnetization direction of the servo signal 6 and the magnetization direction by the preprocessing do not properly face in opposite directions, and the reproduction waveform of the servo signal 6 is underbiased. An example is shown. The lower figure of FIG. 7 shows an example of a case where the reproduced waveform of the servo signal 6 is overbiased.

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

The vertically oriented tape 1 shown in FIG. 8 has a higher degree of vertical orientation (smaller longitudinal square ratio) than the non-aligned tape 1 shown in FIG. 7. Therefore, in the example shown in FIG. 8, the magnetization direction of the servo signal 6 is tilted in the vertical direction as compared with the example shown in FIG. 7.

In the upper figure of FIG. 8, the magnetization direction of the servo signal 6 and the magnetization direction by the preprocessing are appropriately opposite to each other, and the reproduced waveform of the servo signal 6 has symmetry in the vertical direction (±). An example of the case is shown. In the central figure of FIG. 8, when the magnetization direction of the servo signal 6 and the magnetization direction by the preprocessing do not properly face in opposite directions, and the reproduction waveform of the servo signal 6 is overbiased. An example is shown. The lower figure of FIG. 8 shows an example of a case 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 amount of magnetization of the magnetic tape 1 using a vibration sample magnetometer 20.

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

As shown in FIG. 9, the vibrating sample magnetometer 20 is attached to a support rod 21 to which the magnetic tape 1 is attached to the lower end portion and to the upper end portion of the support rod 21 to vibrate the magnetic tape 1 (support rod 21). Includes a vibrating rotating unit 22 that rotates while rotating. Further, the vibration sample type magnetic field meter 20 is arranged at a position where the magnetic tape 1 is sandwiched, a pair of magnetic field applying coils 23 that generate a magnetic field around the magnetic tape 1, and a plurality of coils for measuring the amount of magnetization of the magnetic tape 1. Includes a pickup coil 24.

One side surface of the magnetic tape 1 in the width direction is attached to the lower end portion 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 amount of magnetization is measured while being rotated.

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

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

When the amount of magnetization of the magnetic tape 1 is measured, the magnetization of the entire magnetic layer 4, that is, the magnetization of the pretreatment (see the white arrow) and the magnetization of the servo signal 6 (see the black arrow) are mixed. Be 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 pretreatment exists throughout the servo band s and the data band d. Therefore, when looking at the entire magnetic layer 4, the magnetization due to the pretreatment is dominant, and the magnetization due to the pretreatment is reflected in the measurement of the amount of magnetization.

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

The horizontal axis of FIG. 11 indicates the angle of the magnetic tape 1. The vertical axis of FIG. 11 shows the ratio of the amount of magnetization based on the maximum value of the amount of magnetization of the magnetic tape 1. To further explain the vertical axis, for example, when the amount of magnetization is measured by rotating the magnetic tape 1, if the amount of magnetization reaches the maximum value at an angle of 160 °, the maximum value is used as a reference at each angle. 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 unoriented tape 1A (unoriented barium ferrite, longitudinal angular 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 °. From this, it can be seen 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, the amount of magnetization is maximum when the angles of the magnetic tape 1 are about 165 °, about 170 °, about 195 °, and about 225 °. Take a value. Therefore, in Example 1, Example 2, Example 3, and Comparative Example 4, it can be seen that the magnetization directions of the entire magnetic layer 4 are about 15 °, 10 °, −15 °, and −45 °.

FIG. 6 shows the magnetization amount (%) (vertical magnetization amount (%)) when the angle of the magnetic tape 1 is 90 ° for each Example and each Comparative Example. The amount of magnetization (%) when the angle of the magnetic tape 1 is 90 ° is the amount of magnetization in the vertical direction when the maximum value of the amount of magnetization when the amount of magnetization is measured by rotating the magnetic tape 1 is used as a reference. Is the ratio of.

Next, the square 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 vertically aligned tape 1. As shown in FIG. 12, the square ratio is residual magnetization Mr / saturation magnetization Ms, and is a value indicating the ease with which magnetization remains.

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

FIG. 13 is a diagram showing the relationship between the longitudinal angle ratio and the degree of vertical orientation. From FIG. 13, it can be seen that the smaller the rectangular ratio in the longitudinal direction, the larger the degree of orientation in the vertical direction, and the larger the square ratio in the longitudinal direction, the smaller the degree of orientation in the vertical direction.

FIG. 14 is a diagram showing the relationship between the longitudinal angular ratio and the vertical magnetization amount (%). The amount of magnetization in the vertical direction (%) is the ratio of the amount of magnetization in the vertical direction when the maximum value of the amount of magnetization when the magnetic tape 1 is rotated and the amount of magnetization is measured is used as a reference (see FIG. 11). From FIG. 14, it can be seen that the smaller the rectangular ratio in the longitudinal direction, the larger the amount of magnetization (%) in the vertical direction, and the larger the square ratio in the longitudinal direction, the smaller the amount of magnetization (%) in the vertical direction.

FIG. 6 shows the product of the angular ratio in the longitudinal direction and the amount of magnetization (%) in the vertical direction. From FIG. 6, if the absolute value of the product of the angular ratio in the longitudinal direction and the amount of magnetization (%) in the vertical direction is 0.05 or more and 0.25 or less, the reproduced waveform of the servo signal 6 having good symmetry can be obtained. You can see that you can get it.

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

The angular ratio in the longitudinal direction is the ratio of the saturated 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 square ratio. The smaller the longitudinal angle ratio, the stronger the degree of vertical orientation (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 square ratio) and is determined according to the degree of vertical orientation (longitudinal square ratio). In other words, the longitudinal angle ratio is a parameter that determines the first direction (see the black arrow), which is the magnetization direction of the servo signal 6.

On the other hand, the amount of magnetization in the vertical direction (%) is the ratio of the amount of magnetization in the vertical direction when the maximum value of the amount of magnetization when the magnetic tape 1 is rotated and the amount of magnetization is measured is used as a reference (see FIG. 11). .. The region of magnetization due to preprocessing is sufficiently larger than the region of magnetization of the servo signal 6. Therefore, the amount of magnetization (%) in the vertical direction indicates the vertical component of the magnetization due to the pretreatment. That is, the amount of magnetization in the vertical direction (%) is a parameter that determines the second direction (see the white arrow), which is the magnetization direction due to the pretreatment.

As shown in FIGS. 14 and 15, the larger the amount of magnetization (%) in the vertical direction (the closer the white arrow is to the vertical), the smaller the angular ratio in the longitudinal direction. That is, there is a trade-off relationship between the angular ratio in the longitudinal direction and the amount of magnetization (%) in the vertical direction.

Therefore, when the first direction, which is the magnetization direction of the servo signal 6, and the second direction, which is the magnetization direction due to the pretreatment, are appropriately opposite to each other, the longitudinal direction is a parameter that determines the first direction. An absolute value of the product of the direction angle ratio and the vertical magnetization amount (%), which is a parameter that determines the second direction, is shown as a value in a certain range. This range is the above-mentioned range of 0.05 or more and 0.25 or less.

<Method for reducing distortion in the 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. I explained the technology. On the other hand, in the following description, a technique for solving the problem that the reproduced 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 reproduction 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 (absolute of positive output peak value and 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 is not distorted.

When the magnetization direction of the servo signal 6 includes a vertical component, the output in the reproduction waveform of the servo signal 6 can be made high, but on the other hand, 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 the vertical component, distortion is less likely to occur in the reproduction waveform of the servo signal 6, but on the other hand, it is difficult to increase the output in the reproduction waveform of the servo signal 6. There is.

Generally, by recording the servo signal 6 so as not to include the vertical component, a method of reducing the distortion in the reproduction waveform of the servo signal 6 at the expense of increasing the output in the reproduction waveform of the servo signal 6 is used. Often used.

However, even if the servo signal 6 is recorded so as to include a vertical component, if the distortion in the reproduction waveform of the servo signal 6 can be reduced, the output of the reproduction waveform can be increased and good reproduction without distortion can be achieved. It is considered that it is possible to obtain a waveform at the same time. Hereinafter, the techniques for achieving both of these will be described in detail with specific examples.

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 unit 13 has a recording surface 13a for recording the servo signal 6 with respect to the magnetic tape 1 while being in contact with the magnetic layer 4 of the magnetic tape 1. The recording surface 13a is provided with five sets of magnetic gaps 32 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 so as to be arranged at predetermined intervals in a direction (Y-axis direction) orthogonal to the transport direction (X-axis direction) of the magnetic tape 1. Then, the servo signal 6 is recorded for the five servo bands s0 to s4 by the leakage magnetic field generated from the five sets of magnetic gaps 32. Each of the five sets of magnetic gaps 32 is composed of two magnetic gaps 32 arranged so as to have a predetermined azimuth angle and are inclined in directions facing each other.

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

In the present embodiment, the servo signal 6 is recorded by the leakage magnetic field generated from the magnetic gap 32 of 1 μm or less in this way, so that the component perpendicular to the magnetization direction of the servo signal 6 is included. Then, in the present embodiment, the output of the reproduced waveform of the servo signal 6 is increased by including the component perpendicular to the magnetization direction of the servo signal 6 in this way.

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

FIG. 17 is a diagram showing an example of a case where the reproduced waveform of the servo signal 6 is distorted. As shown in FIG. 17, when the magnetization direction of the servo signal 6 includes a vertical component, two peak values may occur on the positive output side. In this way, if two peak values are generated, it 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 line thickness of the servo signal 6 (corresponding to the spacing described later) is set to 1.2 μm or less. By setting the line thickness of the servo signal 6 to 1.2 μm or less in this way, 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. can. As a result, it is possible to achieve both high output of the reproduced waveform and obtaining a good reproduced waveform without distortion.

Here, the thickness of the line in the servo signal 6 will be described. FIG. 18 is a schematic diagram showing how the servo signal 6 is recorded by the servo signal recording unit 13. Note that, for convenience of explanation, FIG. 18 shows only one of the two magnetic gaps 32 that are inclined to each other with a predetermined azimuth angle. Further, in FIG. 18, for convenience of explanation, the ratio of the gap length A to the total size of the servo signal recording unit 13 is shown to be larger than the actual ratio.

In the upper view of FIG. 18, 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 the leakage magnetic field causes a part of the magnetic layer 4 to move forward. The state when magnetized in the direction opposite to the magnetization direction by the treatment is shown. The lower figure of FIG. 18 shows a state when 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 diagram 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 is generated. A part of the magnetic layer 4 is magnetized in the direction opposite to the magnetization direction by the pretreatment by the length corresponding to the gap length A of.

Even after the pulse supply is started, the magnetic tape 1 is moved along the transport direction at a predetermined transport speed. Even while the magnetic tape 1 is being moved in this way, a part of the magnetic layer 4 is magnetized in a direction opposite to the magnetization direction by the pretreatment 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 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 the magnetic tape 1) is referred to as a recording current distance B.

As can be understood from the above description, the line thickness in the servo signal 6 corresponds to the sum of the gap length A of the magnetic gap 32 and the recording current distance B (see the lower diagram of FIG. 18). ). Then, in the present 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 the value obtained by adding the gap length A of the magnetic gap 32 and the recording current distance B, but a slight deviation occurs between them. This is due to the following reasons.

With reference to FIG. 18, attention is paid to the boundary (two points) 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 does not face a certain direction, but faces a second direction or a first direction. Or something. Due to this, a slight deviation occurs between the line thickness of the servo signal 6 and the value to which the gap length A and the recording current distance B are added.

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). Therefore, 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 reproduction 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 reproduction waveform of the servo signal 6, two peak values (positive output peak value and negative output peak value) are generated at positions corresponding to the boundary where the magnetization direction is reversed.

In the present embodiment, the time indicated by the interval between the positive output peak value and the negative output peak value adjacent to each other 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) × (conveyance speed of the magnetic tape 1). This spacing corresponds to the thickness of the line in the servo signal 6. That is, in this embodiment, this 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 a data acquisition board to obtain the output peak value of the reproduced waveform, and then the difference between the time when the positive output peak value is reached and the time when the negative output peak value is reached is obtained. After that, the average value of the differences of n pieces (for example, n = 30) is obtained, and the spacing can be obtained by multiplying this average value by the transport speed of the magnetic tape 1.

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

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

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

Next, the present inventors make the recording current distance B different by making the pulse supply time (clk) different for each of the plurality of servo signal recording units 13, thereby increasing the line thickness. Different servo signals 6 were recorded on the magnetic layer 4. Specifically, the pulse supply time was 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, 2.5 clk, and 3 clk, the recording current distance B (= pulse supply time × carrier speed of the magnetic tape 1) is 0.25 μm and 0.5 μm, respectively. It is 0.625 μm and 0.75 μm.

FIG. 20 shows a reproduction waveform when the servo signal 6 recorded on the magnetic tape 1 under different conditions is read by the reproduction 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 row have gap lengths A of 0.71 μm, 0.81 μm, and 1.1 μm, respectively. The servo signal 6 is recorded on the magnetic layer 4 by the leakage magnetic field from the magnetic gap 32 having 1.22 μm, and the waveform when the servo signal 6 is read is shown.

Further, in FIG. 20, the reproduced waveforms 9a to 9m, 9b to 9n, 9c to 9o, and 9d to 9p arranged in a horizontal row are sequentially arranged by 1clk, 2clk, 2.5clk, and 3clk, respectively, depending on the pulse supply time. The servo signal 6 signal is recorded on the magnetic layer 4, and the waveform when the servo signal 6 is read is shown.

For the reproduced waveforms 9a to 9p, the outputs are 0.995V, 0.940V, 0.935V, 0.920V, 0.905V, 0.920V, 0.890V, 0.890V, 0. It was 855V, 0.870V, 0.870V, 0.840V, 0.825V, 0.795V, 0.779V, 0.770V.

For the reproduced waveforms 9a to 9p, the spacing (that is, the thickness of the line of the servo signal 6) is 0.877 μm, 1.009 μm, 1.098 μm, 1.234 μm, 0.911 μm, 1.052 μm, respectively, in order. , 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, 1.655 μm.

With reference 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 becomes narrower. This is because the vertical component in the magnetization direction gradually increases as the gap length A of the magnetic gap 32 becomes narrower. In particular, when the gap length A of the magnetic gap 32 is 1 μm or less, a clear vertical 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, and a component perpendicular to the magnetization direction of the servo signal 6 is included to improve 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) becomes shorter.

On the other hand, to explain the distortion of the reproduced waveform of the servo signal 6, there is a feature that the gap length A of the magnetic gap 32 becomes narrower and the waveform becomes more easily distorted as the vertical component in the magnetization direction gradually increases. With reference to the four reproduced waveforms 9d, 9h, 9l, and 9p shown at the bottom of FIG. 20, the reproduced waveform as the gap length A of the magnetic gap 32 becomes narrower and the vertical component in the magnetization direction gradually increases. It can be seen that the distortion of is increasing.

In particular, 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. In this way, if two peak values are generated, it leads to erroneous detection of the peak position.

However, the reproduced waveform has a feature that the distortion becomes smaller as the pulse supply time becomes shorter and the spacing (thickness of the line of the servo signal 6) becomes shorter. In the present embodiment, this relationship is utilized to achieve both high output of the reproduced waveform and obtaining a good reproduced waveform without distortion.

Here, attention is paid to the reproduced waveform 9d and the reproduced waveform 9c. In the reproduced waveform 9d, the spacing (thickness of the line of the servo signal 6) is 1.234 μm, 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 (2.5cl) and the spacing (thickness of the line of the servo signal 6) becomes 1.098 μm, the reproduction waveform is distorted. It has a good waveform without any noise.

Similarly, focusing on the reproduction waveform 9h and the reproduction waveform 9g, in the reproduction waveform 9h, the spacing (thickness of the line of the servo signal 6) is 1.262 μm, and the spacing is too long to reproduce the servo signal 6. The waveform is distorted. On the other hand, when the pulse supply time is shortened (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 a component perpendicular to the magnetization direction of the servo signal 6 is included, if the spacing (thickness of the line of the servo signal 6) is 1.2 μm or less, the distortion will occur. It is considered that a good reproduction waveform can be obtained.

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

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

In FIG. 21, the plot when 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 (thickness of the line of the servo signal 6).

As shown in FIG. 22, as the gap length A in the magnetic gap 32 becomes wider, the spacing (thickness of the servo signal line) becomes longer. 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, the plot when 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 the plot when the reproduced waveform is distorted is surrounded by the alternate long and short dash line. Further, in FIG. 22, the plot when 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. .. For the plot within the range surrounded by the solid line, it is possible to achieve both high output of the reproduced waveform and obtaining 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 reproduction head unit provided in a device separate from the servo signal recording device 100.

<Various deformation examples>
The present technology can also adopt the following configurations.
(1) A part of the magnetic layer is magnetized in the first direction including a component in the vertical direction perpendicular to the upper surface of the magnetic layer, a servo signal is recorded, and the servo signal is recorded before the servo signal is recorded. A magnetic recording medium comprising a magnetic layer containing a component in the vertical direction and magnetized in a second direction opposite to the first direction.
(2) The magnetic recording medium according to (1) above.
The ratio of the amount of magnetization in the vertical direction when the maximum value of the amount of magnetization when the amount of magnetization is measured by rotating the magnetic recording medium is used as a reference, and the square ratio of the magnetic layer in the longitudinal direction parallel to the upper surface. A magnetic recording medium having an absolute value of 0.05 or more and 0.25 or less.
(3) The magnetic recording medium according to (1) or (2) above.
The magnetic layer is a magnetic recording medium containing non-oriented or vertically oriented magnetic powder inside.
(4) The magnetic recording medium according to (3) above.
The magnetic powder is a magnetic recording medium which is barium ferrite or needle-shaped metal.
(5) By applying a magnetic field to a part of the magnetic layer of the magnetic recording medium, a part of the magnetic layer is magnetized in the first direction including a component in the vertical direction perpendicular to the upper surface of the magnetic layer. The servo signal recording unit that records the servo signal and
By applying a magnetic field to the magnetic layer before the servo signal is recorded by the servo signal recording unit, the above is performed in a second direction opposite to the first direction, which includes the component in the vertical direction. A servo signal recording device including a pretreatment unit that magnetizes the magnetic layer.
(6) The servo signal recording device according to (5) above.
The pretreatment unit is a servo signal recording device having a magnet that is rotatable and can change the magnetic field applied to the magnetic layer in response to the rotation.
(7) By applying a magnetic field to a part of the magnetic layer of the magnetic recording medium, a part of the magnetic layer is magnetized in the first direction including a component in the vertical direction 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, which includes the vertical component. A method for manufacturing a magnetic recording medium.
(8) It has a magnetic layer in 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 reproduced waveform when the servo signal is read. A magnetic recording medium in which the distance indicated by the interval between the negative output peaks is 1.2 μm or less.
(9) The magnetic recording medium according to (8) above.
A magnetic recording medium in which the distance indicated by the distance between the positive output peak and the negative output peak adjacent to each other is 1.1 μm or less.
(10) The magnetic recording medium according to (9) above.
A magnetic recording medium in which the distance indicated by the distance between the positive output peak and the negative output peak adjacent to each other is 1.0 μm or less.
(11) The magnetic recording medium according to any one of (8) to (10) above.
A part of the magnetic layer is magnetized in the first direction including a component in the vertical direction perpendicular to the upper surface of the magnetic layer, the servo signal is recorded, and the servo signal is recorded before the servo signal is recorded. A magnetic recording medium containing the vertical component and magnetized in a second direction opposite to the first direction.
(12) The distance indicated by the interval between the positive output peak and the negative output peak adjacent to each other in the reproduced waveform when the servo signal recorded on the magnetic layer of the magnetic recording medium is read is 1.2 μm or less. A servo signal recording device including a servo signal recording unit that records the servo signal on the magnetic layer by a leakage magnetic field of a magnetic gap having a gap of 1 μm or less.
(13) The distance indicated by the interval between the positive output peak and the negative output peak adjacent to each other in the reproduced waveform when the servo signal recorded on the magnetic layer of the magnetic recording medium is read is 1.2 μm or less. A method for manufacturing a magnetic recording medium that records the servo signal on the magnetic layer by a leakage magnetic field of a magnetic gap having a gap of 1 μm or less.

1 ... Magnetic tape 2 ... Base material 3 ... Non-magnetic layer 4 ... Magnetic layer 6 ... Servo signal 12 ... Preprocessing unit 12a ... Permanent magnet 13 ... Servo signal recording unit 14 ... Playback head unit 20 ... Vibration sample type magnetometer 100 ... Servo signal recording device

Claims (6)

A base material, a non-magnetic layer laminated on the base material, and a magnetic layer laminated on the non-magnetic layer are included, and the magnetic layer contains a magnetic powder of barium ferrite and a part of the magnetic layer is contained. A method for manufacturing a magnetic recording medium that is magnetized and has a readable servo signal recorded.
The magnetic layer is rotatable and has a direction different from the magnetization direction of the servo signal before the servo signal is recorded by a magnet capable of changing the direction of the magnetic field applied to the magnetic layer according to the rotation. Magnetized to
The magnetic recording medium on which the servo signal is recorded is in a direction perpendicular to the upper surface of the magnetic layer when the maximum value of the magnetization amount when the magnetic recording medium is rotated and the magnetization amount is measured is used as a reference. The absolute value of the product of the ratio of the amount of magnetization and the square ratio of the magnetic layer in the longitudinal direction parallel to the upper surface of the magnetic layer is 0.05 or more and 0.25 or less.
A method for manufacturing a magnetic recording medium in which the reproduced waveform when the servo signal is read is symmetrical in the vertical direction (±). The method for manufacturing a magnetic recording medium according to claim 1.
A method for manufacturing a magnetic recording medium, in which the difference between the maximum voltage value Vmax of the reproduced waveform and the minimum voltage value Vmin (absolute value) is 5% to 10% with respect to the amplitude of the reproduced waveform. The method for manufacturing a magnetic recording medium according to claim 1 or 2.
A method for producing a magnetic recording medium in which the material of the base material is polyethylene terephthalate or polyethylene naphthalate. The method for manufacturing a magnetic recording medium according to any one of claims 1 to 3.
The non-magnetic layer is a method for producing a magnetic recording medium containing α-Fe ₂ O ₃ or polyurethane. The method for manufacturing a magnetic recording medium according to any one of claims 1 to 4.
A method for manufacturing a magnetic recording medium, wherein the magnetic layer includes a plurality of data bands and a plurality of servo bands arranged at positions sandwiching the data bands in the width direction of the magnetic recording medium. The method for manufacturing a magnetic recording medium according to claim 5.
The plurality of servo bands are five servo bands, which is a method for manufacturing a magnetic recording medium.

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