JP4474376B2 - Magnetic disk evaluation method - Google Patents

Description

  The present invention relates to a magnetic disk evaluation method for evaluating characteristics of a magnetic disk mounted on a magnetic disk device such as a hard disk drive.

  Today, information recording technology, particularly magnetic recording technology, is required to undergo dramatic technological innovation with the development of the so-called IT industry. Unlike other magnetic recording media such as magnetic tapes and flexible disks, the magnetic disk mounted on a hard disk drive (HDD), which is a magnetic disk device used as a computer storage, is rapidly increasing in information recording density. Has been continued. The information capacity that can be stored in the personal computer device has been dramatically increased, supported by such an increase in the information recording density of the magnetic disk.

  Such a magnetic disk is configured by forming a magnetic layer or the like on a substrate such as a glass disk substrate or an aluminum alloy disk substrate. In particular, in recent years, with increasing demand for mounting hard disk drives in portable devices (so-called “notebook personal computer devices”, etc.), they have high strength, high rigidity, and high impact resistance. A magnetic disk using a glass disk substrate has attracted attention.

  In the hard disk drive, an information signal is recorded and reproduced as a magnetization pattern on the magnetic layer by the magnetic head while flying over the magnetic disk rotated at high speed. In a magnetic disk using a glass disk substrate, since a smooth surface can be obtained, the flying height of the magnetic head can be reduced, and a high information recording density can be realized. In other words, by using a glass disk substrate, it is possible to manufacture a magnetic disk that is excellent in low head flying height compatibility.

  On the other hand, in order to increase the information recording capacity of the magnetic disk, it is necessary to reduce the area of a useless area where information signals are not recorded on the magnetic disk. Therefore, instead of the conventionally used CSS method (“Contact Start Stop method”), the LUL method (“load unload”) that can increase the information recording capacity is used as a hard disk drive start / stop method. (Load Unload) method, also known as “ramp load method”) is being introduced.

  In the CSS system, it is necessary to provide a CSS zone on the magnetic disk on which the magnetic head is placed when the magnetic disk is not used (stopped), and information signals cannot be recorded in the CSS zone. The area of the magnetic disk where information signals are recorded is reduced.

  On the other hand, in the LUL method, when the magnetic disk is not in use (stopped), the magnetic head is moved to the outer peripheral side of the magnetic disk and is retracted and supported from the magnetic disk. It is not necessary to provide an area where information signals cannot be recorded such as a zone, and the area of the area where information signals are recorded on the magnetic disk can be secured to the maximum.

  In the LUL method, unlike the CSS method, the magnetic head and the magnetic disk do not come into contact with each other. Therefore, it is not necessary to provide the magnetic disk with an uneven shape for preventing adsorption as in the CSS zone. The main surface can be extremely smoothed. Therefore, in the magnetic disk for LUL system, the flying height of the magnetic head can be further narrowed compared to the magnetic disk for CSS system, and the S / N ratio (Signal Noise Ratio) of the recording signal is improved. There is also an advantage that a high recording density can be achieved.

  As a result of such a non-continuous narrowing of the flying height of the magnetic head accompanying the introduction of the LUL method, the magnetic head can be stably operated even in an extremely narrow flying height of less than 10 nm in recent years. It has come to be required. However, by smoothing the surface of the magnetic disk and narrowing the flying height of the magnetic head, the flying characteristics of the magnetic head become unstable, and various HDI failures such as a fly stiction failure can be caused. found.

  Usually, a magnetic disk is completed through a series of manufacturing processes of a disk substrate manufacturing process, a film forming process, and an inspection process, and is packed and shipped to the market. Therefore, in order to select a magnetic disk that does not cause fly stiction failure even if the flying height of the magnetic head is narrowed, the pressure is set to a predetermined pressure (referred to as TDP (Touch Down Pressure)) while the magnetic disk is rotated. After the magnetic head is brought into contact with the magnetic disk by decreasing the pressure, the magnetic head is lifted from the magnetic disk by increasing the atmospheric pressure, and the atmospheric pressure (TOP (Take Off Pressure)) when the magnetic head is lifted. By measuring, the flying characteristics of the magnetic head are inspected. As described in Patent Document 1, such TOP measurement is performed as a so-called fixed point flying test, and a magnetic head is installed at a predetermined position with respect to the magnetic disk, for example, at a position 22 mm from the rotation center of the magnetic disk. Done.

  Such sorting by TOP measurement is a test that can be performed quickly, but the result correlates with the load / unload durability test, so that magnetic disks with stable quality are stably and quickly supplied to the market. be able to. Note that the load / unload endurance test involves loading a magnetic disk on a hard disk drive and repeating the load / unload operation continuously for a number of times, for example, 600,000 times or more. This test takes a long time.

JP 2001-291218 A

  Incidentally, in recent magnetic disks, as described above, the spacing loss between the magnetic disk and the magnetic head has been improved and the S / N ratio of the recording signal has been improved, resulting in an information recording density of 1 square inch. It has reached 60 gigabits per second, and an ultra-high recording density exceeding 100 gigabits per square inch is also being realized.

  In recent magnetic disks that can realize such a high information recording density, it is possible to store a practically sufficient amount of information even if the disk area is much smaller than that of a conventional magnetic disk. Have. In addition, the magnetic disk has a feature that information recording speed and reproduction speed (response speed) are extremely fast compared with other information recording media, and information can be written and read at any time. .

  As a result of attention paid to various features of such magnetic disks, in recent years, portable so-called MP3 music players, mobile phones, digital cameras, portable information devices (for example, PDA (personal digital assistant): personal digital assistant, ), Or a small hard disk drive that can be mounted on a device that is much smaller than a personal computer device and requires a high response speed, such as a “car navigation system”. . Specifically, for example, there is a demand for a small hard disk drive equipped with a magnetic disk manufactured using a disk substrate having an outer shape of 50 mm or less (1.8 inches or less) and a plate thickness of 0.5 mm or less.

  However, the fixed-point levitation as described above is used for such a small-sized magnetic disk as used in such a small hard disk drive, such as a 1-inch type disk or a 0.85-inch type disk. Depending on the inspection, there was a problem that the selection could not be correlated with the load / unload durability test. That is, in the case of a magnetic disk with a small diameter, the relative linear velocity between the magnetic disk and the magnetic head becomes slow particularly on the inner peripheral side where the distance from the rotation center of the magnetic disk is 10 mm or less. It was found that the interaction between these magnetic heads and the magnetic disk became large, and the transition from the sliding state to the floating state was not performed smoothly by the above-described inspection, and the correct evaluation was not performed.

  Accordingly, the present invention has been made in view of the above-described circumstances, and the object thereof is TDP (Touch Down Pressure) even for small magnetic disks such as 1-inch disks and 0.85-inch disks. It is another object of the present invention to provide a magnetic disk evaluation method capable of performing correct evaluation and selection correlated with a load / unload endurance test by measuring TOP (Take Off Pressure).

  The present invention is suitable for increasing the recording density by providing such a magnetic disk evaluation method. For example, the present invention is suitable for portable information devices such as portable so-called MP3 players and mobile phones, Even when miniaturized so that it can be used for small hard disk drives that can be mounted on highly portable equipment such as navigation systems and other in-vehicle equipment, it is possible to provide advanced quality assurance and It is an object of the present invention to provide a stable and quick supply of a magnetic disk that can sufficiently prevent the occurrence of a failure in the market.

  As a result of researches to solve the above-mentioned problems, the present inventor has found the following facts. That is, in the conventional evaluation method, since the measurement is performed by floating at a fixed point, particularly in a small magnetic disk, the interaction between the magnetic head and the magnetic disk is large, and the transition from the sliding state to the floating state is difficult. In view of the fact that correct evaluation has not been performed, after the magnetic head is loaded and brought into contact with the magnetic disk, the magnetic head is reciprocated at a predetermined amplitude and frequency in the radial direction of the magnetic disk (seek operation), It was found that a smooth transition from the sliding state to the floating state was made.

  That is, the magnetic disk evaluation method according to the present invention has any one of the following configurations.

[Configuration 1]
A magnetic disk evaluation method for evaluating a magnetic disk for recording and / or reproducing by flying a magnetic head on the magnetic disk by rotating the magnetic disk, wherein the atmospheric pressure is reduced while the magnetic disk is rotated. After the magnetic head is brought into contact with the magnetic disk, the magnetic head is lifted from the magnetic disk by increasing the atmospheric pressure, and when measuring the atmospheric pressure when the magnetic head is lifted, the magnetic head is moved in the radial direction of the magnetic disk. It is characterized by reciprocating at a predetermined amplitude and frequency.

[Configuration 2]
A magnetic disk evaluation method for evaluating a magnetic disk that records and / or reproduces by floating a magnetic head on the magnetic disk by rotating the magnetic disk, wherein the rotation speed is set while the magnetic disk is rotated. After the magnetic head is brought into contact with the magnetic disk by decreasing the magnetic head, the rotational speed of the magnetic disk is increased, and then the magnetic head is levitated from the magnetic disk, and the peripheral speed of the magnetic disk when the magnetic head is levitated Is measured, the magnetic head is reciprocated at a predetermined amplitude and frequency in the radial direction of the magnetic disk.

[Configuration 3]
A method for evaluating a magnetic disk having Configuration 1 or Configuration 2, wherein the magnetic head is installed at a location of 10 mm or less from the center of rotation of the magnetic disk.

[Configuration 4]
A method of evaluating a magnetic disk having any one of Structures 1 to 3, wherein the magnetic disk is a load / unload magnetic disk.

[Configuration 5]
A method for evaluating a magnetic disk having any one of Structures 1 to 4, wherein the magnetic disk has a diameter of 1.8 inches or less.

  In the magnetic disk evaluation method according to the present invention, after the magnetic disk is rotated, the magnetic head is brought into contact with the magnetic disk by reducing the atmospheric pressure or the peripheral speed of the magnetic disk at the position of the magnetic head. The magnetic head is lifted from the magnetic disk by increasing the atmospheric pressure or the peripheral speed of the magnetic disk. Since the reciprocating movement is performed in the radial direction with a predetermined amplitude and frequency, even when the interaction between the magnetic head and the magnetic disk is large, the transition from the sliding state to the floating state is performed smoothly, and the correct evaluation is performed. Sorting can be performed.

  In addition, by installing the magnetic head at a position 10 mm or less from the center of rotation of the magnetic disk, a small-sized disk having a diameter of 1.8 inches or less, such as a 1-inch disk or a 0.85-inch disk. The present invention can also be applied to a magnetic disk.

  Further, by applying this magnetic disk evaluation method to a load / unload type magnetic disk, correct evaluation and selection correlated with the load / unload durability test can be performed.

  In other words, the present invention can measure a TDP (Touch Down Pressure) and a TOP (Take Off Pressure) even for a small magnetic disk having a diameter of 1.8 inches or less, such as a 1-inch disk or a 0.85-inch disk. It is possible to provide a magnetic disk evaluation method capable of performing correct evaluation and selection correlated with the load / unload durability test.

  The present invention is suitable for increasing the recording density by providing such a magnetic disk evaluation method. For example, the present invention is suitable for portable information devices such as portable so-called MP3 players and mobile phones, Even when miniaturized so that it can be used for small hard disk drives that can be mounted on highly portable equipment such as navigation systems and other in-vehicle equipment, it is possible to provide advanced quality assurance and It is possible to realize a stable and quick supply to the market of a magnetic disk that can sufficiently prevent the occurrence of a failure.

  The best mode of the magnetic disk evaluation method according to the present invention will be described below in detail.

  This magnetic disk evaluation method is a method for evaluating a magnetic disk on which recording and / or reproduction is performed by floating a magnetic head on the magnetic disk by rotating the magnetic disk. By reducing the pressure, the head slider with the magnetic head is brought into contact with the magnetic disk in TDP (Touch Down Pressure), and then the air pressure is increased to raise the head slider from the magnetic disk in TOP (Take Off Pressure). The magnetic disk is evaluated and selected by measuring the atmospheric pressure (TOP) when the head slider floats.

  Further, this magnetic disk evaluation method is a method of evaluating a magnetic disk for recording and / or reproduction by floating a magnetic head on the magnetic disk by rotating the magnetic disk, and the magnetic disk is rotated. The rotational speed of the magnetic disk is reduced by rotating the magnetic disk after the head slider provided with the magnetic head is brought into contact with the magnetic disk when the peripheral speed of the magnetic disk at the magnetic head position is TDV (Touch Down Velocity). By increasing the speed, the head slider is lifted from the magnetic disk when the peripheral speed is TOV (Take Off Velocity), and the peripheral speed (TOV) when the head slider is lifted is measured to evaluate and sort the magnetic disk. How to do it.

  First, TDP and TOP will be described. As described above, in recent years, with the improvement of the recording density of the magnetic disk, there is a concern that the flying height of the head slider is reduced and the contact frequency between the head slider and the magnetic disk increases. Therefore, TDP measurement and TOP measurement are performed as evaluation of flying characteristics of the magnetic disk with respect to the head slider.

  FIG. 1 is a graph showing the concept of TDP and TOP.

  As shown in FIG. 1, TDP means that the head slider moves from a floating state to a sliding state when the atmospheric pressure in the hard disk drive is gradually lowered (when it moves to the left side on the horizontal axis in FIG. 1). The value of atmospheric pressure when doing. TOP indicates that the head slider moves from the sliding state to the floating state when the atmospheric pressure in the hard disk drive is gradually increased after confirming the TDP (when it moves to the right side in the horizontal axis in FIG. 1). The value of the atmospheric pressure at the time of transition.

  These TDP and TOP are measured by installing the hard disk drive in a container capable of controlling the atmospheric pressure. The TDP and TOP can be confirmed by using an AE (Acoustic Emission) sensor that measures the output from the magnetic head and viewing the output from the AE sensor (vertical axis in FIG. 1).

  The value of TDP indicates the difficulty of contact of the head slider with the magnetic disk, and the value of TOP is when the head slider that is in contact with the magnetic disk and is in a sliding state with respect to the magnetic disk leaves the magnetic disk. It shows the ease of leaving. Therefore, it is required for the magnetic disk that both the TDP value and the TOP value are small. In addition, it is desirable for the magnetic disk to have a small ΔP, which is the difference between the TDP value and the TOP value. If this ΔP is small, it can be said that the flying characteristics of the head slider are good.

  Next, TDV and TOV will be described.

  FIG. 2 is a graph showing the concept of TDV and TOV.

  As shown in FIG. 2, TDV means that when the peripheral speed of the magnetic disk at the position of the magnetic head is gradually lowered (when it moves to the left in the horizontal axis in FIG. 2), the head slider moves from the floating state. The value of the peripheral speed when shifting to the sliding state. The TOV means that the head slider slides when the peripheral speed of the magnetic disk at the magnetic head position is gradually increased after the TDV is confirmed (when the magnetic disk moves to the right side in the horizontal axis in FIG. 2). The value of the peripheral speed when shifting from the state to the floating state.

  These TDV and TOV measurements are performed using a flying characteristic measuring apparatus capable of controlling the rotational speed of the magnetic disk. These TDV and TOV can be confirmed by observing the output waveform of the oscilloscope (vertical axis in FIG. 2) using a piezo element (PZT) sensor.

  The value of TDV indicates the difficulty of contact of the head slider with the magnetic disk, and the value of TOV is when the head slider that is in contact with the magnetic disk and is in a sliding state with respect to the magnetic disk moves away from the magnetic disk. It shows the ease of leaving. Therefore, the magnetic disk is required to have a small value for both TDV and TOV. Further, it is desirable for the magnetic disk to have a small ΔV, which is the difference between the TDV value and the TOV value. If this ΔV is small, it can be said that the flying characteristics of the head slider are good.

  In the conventional evaluation method, with respect to the 2.5 inch type air disk, the head slider floated within the atmospheric pressure after the TDP was confirmed. However, in small magnetic disks such as 1-inch disks and 0.85-inch disks, as described above, the interaction between the magnetic head and the magnetic disk is large, and the transition from the sliding state to the floating state is smooth. The correct evaluation cannot be performed.

  Further, in the conventional evaluation method, for the 2.5 inch type air disk, the head slider floated at the peripheral speed at the start of measurement after confirming TDV. However, in small magnetic disks such as 1-inch disks and 0.85-inch disks, as described above, the interaction between the magnetic head and the magnetic disk is large, and the transition from the sliding state to the floating state is smooth. The correct evaluation cannot be performed.

  Therefore, in the magnetic disk evaluation method according to the present invention, in order to alleviate the interaction between the head slider and the magnetic disk, after the TDP and TDV are confirmed, the head slider seek operation in the measurement of TOP and TOV, that is, The head slider is reciprocated at a predetermined amplitude and frequency in the radial direction of the head slider. The amplitude (pitch) of the seek operation of such a head slider is preferably about 10 μm to 100 μm. Further, the speed of the head slider in this seek operation is preferably about 7 mm / sec to 70 mm / sec. Therefore, the frequency of this seek operation is preferably about 35 Hz to 3500 Hz.

  In this evaluation method, in a small magnetic disk, the head slider is installed at a position of 10 mm or less, for example, 7 mm from the rotation center of the magnetic disk. This evaluation method is preferably applied to a load / unload type magnetic disk.

  Hereinafter, the present invention will be specifically described by giving examples and comparative examples of the present invention.

[First embodiment]
For magnetic disk A, magnetic disk B, and magnetic disk C with different surface roughnesses, these magnetic disks are mounted on a flying characteristic measuring device, and the atmospheric pressure in the flying characteristic measuring device is gradually lowered in a container capable of controlling atmospheric pressure. Then, the atmospheric pressure (TOP) when the head slider provided with the magnetic head transited from the floating state to the sliding state was measured. About this TOP, 0.65 atm (atm) or less is accepted.

  In this embodiment, the head slider seek operation was performed when measuring TOP. This seek operation was performed with an amplitude (pitch) of 10 μm, a magnetic head speed of 7 mm / sec, and a frequency of 35 Hz.

  The head slider was installed at a position 7 mm from the rotation center of each magnetic disk A, B, C. Since the rotation speed of each of the magnetic disks A, B, and C was 3600 rotations (rpm) per minute, the peripheral speed of the magnetic disk at the position of the magnetic head was 2.6 m / s.

  FIG. 3 is a graph showing hysteresis data of TDP and TOP in the first embodiment.

  As a result of the measurement, as shown in [Table 1] below, the magnetic disk A and the magnetic disk B both have a TOP value of 0.65 atm or less and pass. As for ΔP, which is the difference between the TDP value and the TOP value, the magnetic disk A and the magnetic disk B are acceptable because ΔP is smaller than the predetermined value.

  On the other hand, with respect to the magnetic disk C, the TOP value is 0.80 atm. Regarding ΔP, the magnetic disk C is rejected because ΔP is larger than a predetermined value. It seems that the magnetic disk C failed because the surface roughness was too low.

[First Comparative Example]
With respect to the magnetic disk A, magnetic disk B, and magnetic disk C used in the first embodiment, these magnetic disks are mounted on a floating characteristic measuring device, and the floating characteristics are measured in a container capable of controlling the atmospheric pressure as in the first embodiment. The atmospheric pressure (TOP) when the magnetic head moved from the floating state to the sliding state was measured by gradually decreasing the atmospheric pressure in the measuring apparatus. About this TOP, 0.70 atm (atm) or less is accepted.

  In this comparative example, the seek operation of the magnetic head was not performed when measuring TOP.

  The head slider was installed at a position 7 mm from the rotation center of each magnetic disk A, B, C. Since the rotation speed of each of the magnetic disks A, B, and C was 3600 rotations (rpm) per minute, the peripheral speed of the magnetic disk at the position of the magnetic head was 2.6 m / s.

  FIG. 4 is a graph showing hysteresis data of TDP and TOP in the first comparative example.

  In the measurement results, as shown in [Table 2] below, the magnetic disk A, the magnetic disk B, and the magnetic disk C all have a TOP value of 0.65 atm. It has become. Further, regarding ΔP which is the difference between the TDP value and the TOP value, the magnetic disk A, the magnetic disk B, and the magnetic disk C have ΔP larger than the predetermined value, and all are unacceptable.

  In this comparative example, the value of TOP and the value of ΔP are substantially equal for the magnetic disk A, the magnetic disk B, and the magnetic disk C.

[Second Embodiment]
For magnetic disk A, magnetic disk B, and magnetic disk C having different surface roughnesses, these magnetic disks are mounted on a flying characteristic measuring device capable of controlling the rotational speed of the magnetic disk, and inside a container capable of atmospheric pressure control (maintenance). Then, the rotational speed of the magnetic disk was gradually decreased, and the peripheral speed (TOV) of the magnetic disk at the position of the magnetic head when the head slider provided with the magnetic head transitioned from the floating state to the sliding state was measured. About this TOV, 8m or less per second is set as the pass.

  In this embodiment, the head slider seek operation was performed when measuring the TOV. This seek operation was performed with an amplitude (pitch) of 10 μm, a magnetic head speed of 7 mm / sec, and a frequency of 35 Hz.

  The head slider was installed at a position 7 mm from the rotation center of each magnetic disk A, B, C. The atmospheric pressure in the levitation characteristic measuring apparatus was maintained at 0.91 atm (atm).

  FIG. 5 is a graph showing hysteresis data of TDV and TOV in the second embodiment.

  As a result of the measurement, as shown in [Table 2] below, the magnetic disk A and the magnetic disk B both pass the TOV value of 8 m / second or less. In addition, regarding ΔV, which is the difference between the value of TDV and the value of TOV, ΔV is smaller than the predetermined value and the magnetic disk A and the magnetic disk B are passing.

  On the other hand, regarding the magnetic disk C, the value of TOV is 12 m / s, which is rejected. Regarding ΔV, the magnetic disk C is rejected because ΔV is larger than a predetermined value. It seems that the magnetic disk C failed because the surface roughness was too low.

[Second Comparative Example]
About the magnetic disk A, magnetic disk B, and magnetic disk C used in the second embodiment, these magnetic disks are mounted on a flying characteristic measuring device capable of controlling the rotation speed of the magnetic disk, and atmospheric pressure control (maintenance) is possible. In such a container, the rotational speed of the magnetic disk is gradually decreased, and the peripheral speed (TOV) of the magnetic disk at the position of the magnetic head when the head slider provided with the magnetic head shifts from the floating state to the sliding state is set. It was measured. About this TOV, 8m or less per second is set as the pass.

  In this comparative example, the seek operation of the magnetic head was not performed when measuring TOP.

  The head slider was installed at a position 7 mm from the rotation center of each magnetic disk A, B, C. The atmospheric pressure in the levitation characteristic measuring apparatus was maintained at 0.91 atm (atm).

  FIG. 6 is a graph showing hysteresis data of TDV and TOV in the second comparative example.

  In the measurement results, as shown in Table 4 below, the magnetic disk A, the magnetic disk B, and the magnetic disk C all have a TOV value of 12 m / s and all fail. Yes. Regarding ΔP, which is the difference between the TDV value and the TOV value, ΔV is larger than the predetermined value for the magnetic disk A, the magnetic disk B, and the magnetic disk C, and all of them are rejected.

  In this comparative example, the values of TOV and ΔV are almost equal for the magnetic disk A, the magnetic disk B, and the magnetic disk C.

[Verification of each example and each comparative example]
The magnetic disk A and magnetic disk B that passed each example were mounted on a LUL (load / unload) type hard disk drive, and the magnetic head flying height was set to 10 nm, and the LUL durability test was performed.

  As a result, the number of LUL endurances could exceed 600,000 times and passed. It should be noted that it is said that the use of about 10 years is necessary for the number of LULs to exceed 400,000 times under normal usage conditions of hard disk drives, and magnetic disk A and magnetic disk B have high reliability and quality. It turns out that the magnetic disk can be guaranteed.

  On the other hand, the magnetic disk C which failed in the examples was also mounted on a LUL (load unload) type hard disk drive, and a magnetic head flying height was set to 10 nm, and a LUL durability test was performed. As a result, it crashed before the number of LUL endurances reached 600,000, and it failed.

  That is, it is confirmed that the result of the magnetic disk evaluation method according to the present invention has a correlation with the result of the LUL durability test, and the magnetic disk inspected by this magnetic disk evaluation method has high reliability and quality assurance. It was confirmed that the magnetic disk can be provided with a magnetic disk.

  On the other hand, it was confirmed that the result by the magnetic disk evaluation method in the comparative example had no correlation with the result by the LUL durability test.

It is a graph which shows the concept of TDP and TOP. It is a graph which shows the concept of TDV and TOV. It is a graph which shows the hysteresis data of TDP and TOP in a 1st Example. It is a graph which shows the hysteresis data of TDP and TOP in a 1st comparative example. It is a graph which shows the hysteresis data of TDV and TOV in a 2nd Example. It is a graph which shows the hysteresis data of TDV and TOV in a 2nd comparative example.

Claims (5)

A magnetic disk evaluation method for evaluating a magnetic disk for recording and / or reproducing by floating a magnetic head on the magnetic disk by rotating the magnetic disk,
With the magnetic disk rotated, the magnetic head was brought into contact with the magnetic disk by decreasing the atmospheric pressure, and then the magnetic head was levitated from the magnetic disk by increasing the atmospheric pressure, and the magnetic head was levitated When measuring the atmospheric pressure, the magnetic head is reciprocated at a predetermined amplitude and frequency in the radial direction of the magnetic disk. A magnetic disk evaluation method for evaluating a magnetic disk for recording and / or reproducing by floating a magnetic head on the magnetic disk by rotating the magnetic disk,
After rotating the magnetic disk, the magnetic head is brought into contact with the magnetic disk by decreasing the rotation speed, and then the magnetic head is levitated from the magnetic disk by increasing the rotation speed of the magnetic disk. The magnetic head is reciprocated at a predetermined amplitude and frequency in the radial direction of the magnetic disk when measuring the peripheral speed of the magnetic disk at the position of the magnetic head when the magnetic head is levitated. To evaluate magnetic disk. The method for evaluating a magnetic disk according to claim 1, wherein the magnetic head is installed at a position of 10 mm or less from the rotation center of the magnetic disk. The magnetic disk evaluation method according to any one of claims 1 to 3, wherein the magnetic disk is a load / unload type magnetic disk. The magnetic disk evaluation method according to any one of claims 1 to 4, wherein the magnetic disk has a diameter of 1.8 inches or less.

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