Magnetic recording / reproducing device and method of adjusting the same

Abstract

To provide a magnetic recording / reproducing device and a method of adjusting the same for determining a flying height change of a thermally assisted magnetic recording head.SOLUTION: A method of adjusting a magnetic recording / reproducing device according to the embodiment is a method of adjusting a magnetic recording / reproducing device having a thermally assisted magnetic recording head and a magnetic disk, and includes: performing a first write operation at a first position on a recording surface; measuring a first error rate at a second position having a different radial directional position from the first position; measuring a second error rate after performing a second write operation; obtaining a first difference between the first error rate and the second error rate; measuring a third error rate at the first position; measuring a fourth error rate after performing a third write operation; obtaining a second difference between the third error rate and the fourth error rate; and determining a flying height change by comparing the first difference and the second difference.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a magnetic recording and reproducing apparatus and an adjustment method thereof. [Background technology]

[0002] In thermally assisted magnetic recording heads, recording is performed by increasing the temperature of the magnetic disk with a laser. During this process, it has been found that the temperature rise causes components thought to originate from the magnetic film of the magnetic disk to adhere to the tip of the near-field optical element (NFT) via the lubricant, generating a hardened substance. Due to the nature of recording, it is impossible to prevent the formation of hardened lubricants. However, it is known that when hardened lubricants adhere to the recording medium, they act as a layer that increases the laser transmittance and improves the laser transmission efficiency.

[0003] The hardened lubricant is worn away by wear when the flying height is lowered, and is rebuilt when the flying height is raised by filling the gap between the head and the media with lubricant. Therefore, when the flying height changes within the disk surface, for example when the head moves from a track with low flying height to a track with high flying height, a problem occurs in that the write performance decreases until the hardened lubricant is generated. Furthermore, the flying height adjustment accuracy of the write head and NFT has traditionally been inferior to that of the read head, so it is desirable to adjust the flying height of the write head as well so that there is no difference in error rate between immediately after a seek and after sufficient writing. Furthermore, it is desirable to adjust the flying height in the same way when the temperature changes or when monitoring the flying height at the user's site. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2017 / 0221511 [Patent Document 2] U.S. Pat. No. 1,041,0660 [Patent Document 3] Patent Publication No. 2022-173700 [Patent Document 4] U.S. Pat. No. 1,173,5217 Summary of the Invention [Problem to be solved by the invention]

[0005] An embodiment of the present invention is directed to determining the flying height change of a thermally assisted magnetic recording head. [Means for solving the problem]

[0006] According to an embodiment, there is provided a method for adjusting a magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a magnetic disk, comprising the steps of: performing a first write operation with the thermally assisted magnetic recording head at a first position on a recording surface of the magnetic disk; measuring a first error rate by seeking the thermally-assisted magnetic recording head to a second position on the recording surface that is different in a radial direction from the first position; measuring a second error rate after performing a second write operation at the second position; determining a first difference between the first error rate and the second error rate; seeking the thermally-assisted magnetic recording head to the first position and measuring a third error rate; After performing a third write operation at the first position, a fourth error rate is measured. determining a second difference between the third error rate and the fourth error rate; A method for adjusting a magnetic recording and reproducing device is provided, the method including comparing the first difference with the second difference to determine a change in flying height. [Brief description of the drawings]

[0007] [Figure 1] FIG. 11 is a block diagram illustrating a configuration of an example of a magnetic recording and reproducing device according to a second embodiment. [Diagram 2] FIG. 11 is a partial exploded perspective view of a magnetic recording and reproducing device according to a second embodiment. [Diagram 3] FIG. 2 is a side view showing the magnetic head and the suspension. [Figure 4] FIG. 11 is a cross-sectional view of a portion of a magnetic recording and reproducing device according to a second embodiment. [Diagram 5] FIG. 4 is a flow chart showing an example of a method for adjusting the magnetic recording and reproducing device according to the first embodiment. [Figure 6] FIG. 7 is a block diagram illustrating another example of the MPU in FIG. 5. [Figure 7] FIG. 6 is a flow chart showing another example of the adjustment method for the magnetic recording and reproducing device according to the first embodiment. [Figure 8] FIG. 6 is a flow chart showing another example of the adjustment method for the magnetic recording and reproducing device according to the first embodiment. [Figure 9] FIG. 6 is a flow chart showing another example of the adjustment method for the magnetic recording and reproducing device according to the first embodiment. [Figure 10] FIG. 11 is a block diagram illustrating a configuration of another example of the magnetic recording and reproducing device according to the second embodiment. [Figure 11] FIG. 11 is a block diagram illustrating a configuration of another example of the magnetic recording and reproducing device according to the second embodiment. [Figure 12] FIG. 11 is a block diagram illustrating a configuration of another example of the magnetic recording and reproducing device according to the second embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] The method for adjusting a magnetic recording and reproducing device according to the first embodiment is a method for adjusting a magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a magnetic disk, performing a first write operation with the thermally assisted magnetic recording head at a first position on a recording surface of the magnetic disk; a thermally assisted magnetic recording head is caused to seek to a second position on the recording surface that is different in a radial direction from the first position, and a first error rate is measured; After performing a second write operation at the second position, a second error rate is measured; determining a first difference between the first error rate and the second error rate; a thermally assisted magnetic recording head is caused to seek to the first position and a third error rate is measured; performing a third write operation at the first position, and then measuring a fourth error rate; determining a second difference between the third error rate and the fourth error rate; This includes comparing the first difference to the second difference to determine a change in flying height.

[0009] The magnetic recording and reproducing apparatus according to the second embodiment is an example of an apparatus for implementing the adjustment method for the magnetic recording and reproducing apparatus according to the first embodiment, a magnetic disk including a magnetic recording layer and a lubricant provided on a recording surface of the magnetic recording layer; a thermally assisted magnetic recording head for magnetically recording on a magnetic disk; a head position control unit that positions the thermally assisted magnetic recording head at a first position on the recording surface or at a second position that is a radially different position from the first position; a write operation control unit that controls a first write operation at the first position, a second write operation at the second position, and a third write operation at the first position; an error rate measuring unit that measures a first error rate before a second write operation, a second error rate after the second write operation, a third error rate before a third write operation, and a fourth error rate after the third write operation; a calculation unit that calculates a first difference between the first error rate and the second error rate, and a second difference between the third error rate and the fourth error rate; The device further includes a determination unit that compares the first difference with the second difference and determines a change in the flying height.

[0010] According to the first and second embodiments, the difference between the error rates before and after the write operation at two or more different radial positions is calculated and compared, thereby making it possible to determine the change in the flying height of the thermally-assisted magnetic recording head. Also, it becomes possible to adjust the flying height of the thermally-assisted magnetic recording head based on the obtained difference and the flying height change.

[0011] Working Example Example 1 Hereinafter, embodiments will be described with reference to the drawings. The disclosure is merely an example, and appropriate modifications that are within the spirit of the invention and that can be easily conceived by a person skilled in the art are naturally included in the scope of the present invention. In addition, in order to make the explanation clearer, the width, thickness, shape, etc. of each part may be shown diagrammatically compared to the actual embodiment, but these are merely examples and do not limit the interpretation of the present invention. In this specification and each figure, elements similar to those described above with respect to the previous figures may be given the same reference numerals, and detailed explanations may be omitted as appropriate.

[0012] First, the configuration of an example of a disk drive according to the second embodiment will be described with reference to Fig. 1. The configuration of the disk drive, which is a magnetic recording and reproducing device, shown in Fig. 1 is also applied to each embodiment described later. As shown in FIG. 1, the disk drive 200 is a magnetic disk device of a perpendicular magnetic recording type incorporating a magnetic disk 1, which is a perpendicular magnetic recording medium, and a magnetic head 10 having a magnetic flux control layer, which will be described later.

[0013] FIG. 2 is a partial exploded perspective view of the magnetic recording and reproducing device according to the second embodiment. FIG. 2 shows a magnetic recording / reproducing device according to the second embodiment in which a plurality of magnetic disks 1 and a plurality of magnetic heads 10 are housed in a housing 51, with the cover omitted. The magnetic disk 1 is fixed to a spindle motor (SPM) 2 and attached so as to rotate. The magnetic head 10 is mounted on an actuator 3 and configured to move in a radial direction on the magnetic disk 1. The actuator 3 is rotationally driven by a voice coil motor (VCM) 4. In FIG. 1, for example, the magnetic head 10 can be shown as being sought to a first position on the recording surface 1a, and the magnetic head 10' mounted on the actuator 3' can be shown as being sought to a second position that is a radial position different from the first position. The magnetic head 10 includes a write head 10W, a read head 10R, and a thermal assist unit 100. The write head 10W writes data to the magnetic disk 1. The read head 10R reads data from the magnetic disk 1. The thermal assist unit 100 assists the write of data when the write head 10W writes data to the magnetic disk 1. The magnetic head 10 can include a single magnetic head or multiple magnetic heads.

[0014] Furthermore, the disk drive has a head amplifier integrated circuit (hereinafter referred to as head amplifier IC) 11, a read / write channel (R / W channel) 12, a hard disk controller (HDC) 13, a microprocessor (MPU) 14-1, a driver IC 16, and a memory 17. The R / W channel 12, HDC 13, and MPU 14 are incorporated in controller 15, which is a one-chip integrated circuit. The head amplifier IC11 includes a circuit group for driving a laser diode for performing thermal assist, as described later. The head amplifier IC11 further includes a driver for supplying a recording signal (write current) corresponding to write data supplied from the R / W channel 12 to the recording head 10W. The head amplifier IC11 also includes a read amplifier for amplifying a read signal output from the reproducing head 10R and transmitting the amplified signal to the R / W channel 12.

[0015] The R / W channel 12 is a signal processing circuit for read / write data. The HDC 13 constitutes an interface between the disk drive and the host 18, and controls the transfer of read / write data. The MPU 14 is a main control unit of the disk drive, and executes servo control necessary for controlling read / write operations and positioning the magnetic head 10. The MPU 14 further includes a head position control unit 19 that places the thermally assisted magnetic recording head 10 at a first position on the recording surface or at a second position that is a different radial position from the first position, a write operation control unit 61 that controls a first write operation at the first position, a second write operation at the second position, and a third write operation at the first position, respectively, an error rate measurement unit 62 that measures a first error rate before the second write operation, a second error rate after the second write operation, a third error rate before the third write operation, and a fourth error rate after the third write operation, a calculation unit 63 that calculates a first difference between the first error rate and the second error rate, and a second difference between the third error rate and the fourth error rate, respectively, and a determination unit 64 that compares the first difference with the second difference and determines a change in flying height. The memory 17 includes a buffer memory made of a DRAM, a flash memory, and the like. The temperature sensor 9-1 can be installed in an empty space on the bottom wall 52a of the base 52, for example, between a board unit (FPC unit) 53 on which electronic components such as a conversion connector are mounted and the magnetic disk 1, and can be installed anywhere as needed.

[0016] FIG. 3 is a side view showing the magnetic head 10 and the suspension. As shown in Fig. 3, each magnetic head 10 is configured as a floating type head, and has a slider 42 having a substantially rectangular parallelepiped shape and a recording / reproducing head portion 44 provided at the trailing end (trailing end) of the slider 42. The magnetic head 10 is fixed to a gimbal spring 41 provided at the tip of the suspension 34. A head load L directed toward the surface of the magnetic disk 1 is applied to each magnetic head 10 due to the elasticity of the suspension 34. As shown in Fig. 2, each magnetic head 10 is connected to the head amplifier IC 11 and the HDC 13 via the suspension 34 and a wiring member (flexure) 35 fixed on the arm.

[0017] Next, the configurations of the magnetic disk 1 and the magnetic head 10 will be described in detail. FIG. 4 is a cross-sectional view of a write head 10W and a magnetic disk 1 which are part of the magnetic disk device. The magnetic disk 1 has a substrate 20, a heat sink layer 21, a crystal orientation layer 22, a perpendicular recording layer 23, and a protective film 24 with a lubricant applied to the surface, which are laminated in this order on the substrate 20. The perpendicular recording layer 23 has a large anisotropy in the direction perpendicular to the disk surface. The crystal orientation layer 22 is disposed under the perpendicular recording layer 23 to improve the orientation of the perpendicular recording layer 23. The heat sink layer 21 is disposed under the crystal orientation layer 22 to suppress the spread of the heated region. The protective film 24 is disposed on the upper part of the perpendicular recording layer 23 to protect the perpendicular recording layer 23.

[0018] The magnetic head 10 is a separated type magnetic head in which the recording head 10W and the reproducing head 10R are separated, and the recording head 10W is composed of a main pole 40 made of a high magnetic permeability material that generates a magnetic field perpendicular to the disk surface, a trailing yoke 50 that is magnetically connected to the main pole 40 and that passes magnetic flux to the main pole 40, a return shield pole 60 that is provided on the leading side of the main pole 40 to efficiently close the magnetic path immediately below the main pole, a coil 70 that is arranged to be wound around the magnetic path including the trailing yoke and the return shield pole to pass magnetic flux to the main pole 40, a heater 80 for controlling the flying height of the recording head, a near-field optical element 30 that generates near-field light that heats the perpendicular recording layer 23 of the magnetic disk 1 on the leading side of the main pole 40, and a waveguide 31 for propagating the light for generating near-field light. The light source is a laser diode 32 that is incorporated in the actuator assembly 3 by mounting it on the slider. For example, Au, Pd, Pt, Rh, or Ir, or an alloy made of a combination of some of these, can be used as the near-field light element 30. For example, an oxide made of SiO2, Al2O3, etc. can be used as the insulating layer provided between the main pole and the near-field light element.

[0019] Recording methods for thermally assisted magnetic recording that can be used in the magnetic disk device 200 include a conventional recording method known as CMR (Conventional Magnetic Recording), in which tracks are written at radial intervals and recording is performed so that adjacent tracks do not overlap; a shingled recording method known as SMR (Shingled Magnetic Recording), in which tracks are overlapped in sequence in the radial direction and recording is performed overlapping part of an adjacent track; an interlaced recording method known as IMR (Interlaced Magnetic Recording), in which adjacent tracks are alternately overlapped with a bottom track and a top track, and after recording on the bottom track, recording is performed overlapping the interlaced top track and the bottom track; or a combination of these.

[0020] FIG. 5 is a flow diagram showing an example of an adjustment method using the magnetic recording and reproducing device according to the first embodiment shown in FIG. Example 1 shows an example of an adjustment method using the magnetic recording and reproducing device according to the first embodiment, in which the flying height between two different radial positions is compared. As shown in the figure, the adjustment method for the magnetic recording and reproducing device is started, and first, at a first position on the recording surface of the magnetic disk, the write operation control unit 61 controls the thermally assisted magnetic recording head 10 to perform a first write operation (ST1) and form a hardened lubricant. Next, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek to a second position that is different in the radial direction from the first position on the recording surface, and the error rate measurement unit 62 measures a first error rate (ST2). Next, the write operation control unit 61 controls the thermally assisted magnetic recording head to perform a second write operation at the second position (ST3) and form a hardened lubricant. After that, the error rate measurement unit 62 measures a second error rate at the second position (ST4), and the calculation unit 63 calculates a first difference between the first error rate and the second error rate (ST5). Next, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek to the first position, and the error rate measurement unit 62 measures a third error rate (ST6). Thereafter, the write operation control unit 61 controls the thermally-assisted magnetic recording head 10 to perform a third write operation at the first position (ST7), forming a hardened lubricant. Thereafter, the error rate measurement unit 62 measures a fourth error rate at the first position (ST8), and the calculation unit 63 determines a second difference between the third error rate and the fourth error rate (ST9). Next, the determination unit 64 compares the first difference with the second difference to determine a change in the flying height (ST10), and the process ends. This allows a comparison of the flying height between two different positions.

[0021] The lower of the absolute value of the first difference and the absolute value of the second difference can be determined as the lower levitation. The radial position here can be determined by the distance from the center of the recording surface 1a of the magnetic disk 1. For example, a second position that is a different radial position from the first position means that when the first position is on a concentric circle having a first distance from the center of the recording surface 1a of the magnetic disk 1, the second position is on a concentric circle having a second distance from the center of the recording surface 1a that is different from the first distance.

[0022] Furthermore, the write operations such as the first write operation, the second write operation, and the third write operation can be continuously written (written) for a predetermined time, for example, a time sufficient to form a hardened lubricant. The predetermined time for the write operation can be determined based on the time required for the difference in error rate to disappear. For example, it can be set to 1 to 3 seconds. The predetermined time can be set to the same time for the first write operation, the second write operation, and the third write operation. In measuring error rates such as the first error rate, the second error rate, the third error rate, and the fourth error rate, data for measuring the error rates can be written and reproduced.

[0023] According to an embodiment, by measuring the error rate before and after a write operation at two or more different radial positions on the recording surface 1a and calculating and comparing the difference, it becomes possible to determine the change in flying height due to the formation of a hardened lubricant, and if there is a change in the flying height, it can be determined which flying height should be used as the reference.

[0024] For example, it is possible to determine the flying height change at three different radial positions. In this case, in the adjustment method for the magnetic recording and reproducing device according to the first embodiment, after obtaining the second difference, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek to a third position that is a radial position different from the first and second positions, and the error rate measurement unit 62 measures the fifth error rate. Next, the write operation control unit 61 controls the thermally assisted magnetic recording head 10 to perform a fourth write operation at the third position, and then the error rate measurement unit 62 measures a sixth error rate. Thereafter, the calculation unit 63 obtains a third difference between the fifth error rate and the sixth error rate, and the determination unit 64 compares the first difference, the second difference, and the third difference to determine the flying height change. In addition, the flying height can be adjusted so that there is no difference in error rate between two or more different radial positions, making it possible to align the height of the hardened lubricant at two or more different radial positions.

[0025] In the method for adjusting the magnetic recording and reproducing device according to the first embodiment, furthermore, a write operation can be performed again at any timing, the error rates before and after the write operation can be measured, and the difference between the error rates can be found and compared for judgment. Such timing can be freely set, for example, before shipping after manufacture, after shipping, at regular intervals, when the temperature changes, or when the humidity changes. Also, if necessary, after shipment, for example at the user's site, the error rate before and after the write operation can be measured, and the difference can be calculated and compared to monitor the change in the flying height. Furthermore, the flying height can be adjusted as desired in response to the change in the flying height. Such monitoring of the change in the flying height can be performed in the background while the magnetic recording and reproducing device 200 is not performing a recording or reproducing operation. As the position for performing the write operation, a user area on the recording surface can be used, or a test cylinder can be provided for testing. Furthermore, when a change in flying height is determined, it can be notified to the host 18. At this time, the host 18 can be notified using the SMART (Self-Monitoring Analysis and Reporting Technology) function.

[0026] The magnetic disk 1 included in the magnetic recording and reproducing device 200 according to the embodiment can use a perpendicular magnetic recording medium. The perpendicular magnetic recording medium can include, for example, a magnetic recording layer with a granular structure. The magnetic recording layer with a granular structure includes magnetic particles having an L10 structure as a magnetic material. Examples of magnetic particles having an L10 structure include FePt alloy particles and CoPt alloy particles. As grain boundaries, grain boundary materials can include oxides including C, BN, and SiO2. The lubricant hardened product is considered to be a hardened product generated by components derived from the magnetic recording layer, such as SiO2 contained in the grain boundaries, adhering to the tip of the NFT via the lubricant. In addition, a protective layer can be provided on the magnetic recording layer. For example, carbon (C), diamond-like carbon, SiO2, and ZrO2 can be used as the protective layer. For example, perfluoropolyether, fluorinated alcohol, and fluorinated carboxylic acid can be used as the lubricant applied to the recording surface of the magnetic disk.

[0027] Example 2 Example 2 shows, as another example of the method for adjusting the magnetic recording and reproducing device according to the first embodiment, an example in which the flying height is adjusted based on the determination result of the flying height change. FIG. 6 shows an example of an MPU used in another example of the magnetic recording and reproducing device according to the second embodiment. 1, except that MPU14-2 further includes a flying height adjustment unit 65. The magnetic recording and reproducing device used in Example 2 is another example of the magnetic recording and reproducing device according to the second embodiment, and has the same configuration as that in FIG. 1, except that MPU14-2 in FIG. 6 is used instead of MPU14-1.

[0028] FIG. 7 is a flow diagram showing another example of the method for adjusting the magnetic recording and reproducing device according to the first embodiment. As shown in the figure, the adjustment of the magnetic recording and reproducing device is started, and first, at a first position on the recording surface 1a of the magnetic disk 1, the write operation control unit 61 controls the thermally assisted magnetic recording head 10 to perform a first write operation (ST11), and a hardened lubricant is formed. Next, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek to a second position that is different in the radial direction from the first position on the recording surface 1a, and the error rate measurement unit 62 measures the first error rate (ST12). Next, the write operation control unit 61 controls the thermally assisted magnetic recording head to perform a second write operation at the second position (ST13), and a hardened lubricant is formed. After that, the error rate measurement unit 62 measures a second error rate at the second position (ST14), and the calculation unit 63 calculates a first difference between the first error rate and the second error rate (ST15). Next, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek to the first position, and the error rate measurement unit 62 measures the third error rate (ST16). Thereafter, the write operation control unit 61 controls the thermally assisted magnetic recording head 10 to perform a third write operation at the first position (ST17), and a hardened lubricant is formed. Thereafter, the error rate measurement unit 62 measures a fourth error rate at the first position (ST18), and the calculation unit 63 calculates a second difference between the third error rate and the fourth error rate (ST19). The steps from ST11 to ST19 are the same as the steps from ST1 to ST9 in the adjustment method of the first embodiment.

[0029] Next, the determination unit 64 compares the first difference with the second difference to determine whether there has been a change in the flying height (ST20). If the determination shows that there has been a change in the flying height, the flying height adjustment unit 65 adjusts the flying height (ST21), and then the steps from ST11 to ST20 are repeated. On the other hand, if there has been no change in the flying height, the process ends. This makes it possible to compare and adjust the flying heights at two different positions. In addition, when the flying height changes, for example, the lower of the absolute value of the first difference and the absolute value of the second difference can be determined as the reference radial position. In adjusting the flying height, the flying height can be lowered until the difference in error rate at radial positions other than the reference radial position becomes the same as the difference in error rate at the reference radial position. This makes it possible to align the heights of the hardened lubricant at the two positions.

[0030] Example 3 Example 3 shows an example in which a change in flying height is determined at three different radial positions as another example of the adjustment method for the magnetic recording and reproducing device according to the first embodiment. FIG. 8 is a flow chart showing yet another example of the method for adjusting the magnetic recording and reproducing device according to the first embodiment. Here, the same magnetic recording and reproducing device as in the second embodiment can be used. As shown in the figure, first, adjustment of the magnetic recording and reproducing device is started, and the first and second differences are obtained in steps ST31 to ST39 in the same manner as steps ST11 to ST19 in the second embodiment.

[0031] Next, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek to a third position that is different in the radial direction from the first and second positions, the error rate measurement unit 62 measures a fifth error rate (ST40), the write operation control unit 61 controls the thermally assisted magnetic recording head 10 to perform a fourth write operation at the third position (ST41), and then the error rate measurement unit 62 measures a sixth error rate (ST42), the calculation unit 63 determines a third difference between the fifth and sixth error rates (ST43), and the determination unit 64 compares the first difference, the second difference, and the third difference to determine a change in the flying height (ST44). The error rate measurement unit 62 measures the fifth error rate before the fourth write operation and the sixth error rate after the fourth write operation.

[0032] Furthermore, if necessary, if there is a change in the flying height, the flying height adjustment unit 65 adjusts the flying height (ST45), and then the steps from ST31 to ST43 are repeated. On the other hand, if the flying height does not change, the process can end. This allows comparison and adjustment of the flying heights between three different positions. In FIG. 8, after ST44, the flying height is adjusted in ST45 if necessary, but it is possible to end the adjustment method for the magnetic recording and reproducing device by only performing the judgment in ST44.

[0033] When the flying height changes, for example, the lowest absolute value of the third difference between the absolute value of the first difference and the absolute value of the second difference can be determined as the reference radial position. In adjusting the flying height, the flying height can be lowered until the difference in error rate at radial positions other than the reference radial position becomes the same as the difference in error rate at the reference radial position. This makes it possible to align the heights of the hardened lubricant at the three positions.

[0034] Example 4 Example 4 shows an example of monitoring the flying height change in the background as yet another example of the method for adjusting the magnetic recording and reproducing device according to the first embodiment. FIG. 9 is a flow chart showing yet another example of the method for adjusting the magnetic recording and reproducing device according to the first embodiment. Here, the same magnetic recording and reproducing device as in the second embodiment can be used. First, a magnetic recording and reproducing device is prepared in which the first and second differences are obtained in advance in the same manner as in the second embodiment, the flying heights at two positions are compared, and the flying height is adjusted as necessary.

[0035] After a write operation is performed in the user area, the thermally assisted magnetic recording head is confirmed to be capable of operating in the background, and monitoring of the flying height change is started. A state in which the head can operate in the background means a state in which the head can operate out of sight of the user, such as an idle state. First, the head position control unit 19 controls the thermally assisted magnetic recording head 10 to seek the thermally assisted magnetic recording head 10 to a fourth position, for example, a position on a test cylinder that is different in radial direction from the first and second positions, and measures a sixth error rate (ST51). Next, the write operation control unit 61 controls the thermally assisted magnetic recording head 10 to perform a fifth write operation at the fourth position (ST52) to form a hardened lubricant. After that, the error rate measurement unit 62 measures a seventh error rate at the fourth position (ST53). That is, the error rate measurement unit 62 measures the sixth error rate before the fifth write operation and the seventh error rate after the fifth write operation. Next, the calculation unit 63 calculates a fourth difference between the seventh error rate and the sixth error rate (ST54).

[0036] Next, the determination unit 64 compares the fourth difference with the first difference and / or the second difference obtained in advance, and determines whether there is a change in the flying height (ST55). If there is a change in the flying height, it is determined whether the fourth difference is a negative value (ST56). If the fourth difference is a negative value, the monitor is abnormally terminated. If the fourth difference is not a negative value, the flying height is adjusted (ST57). Then, ST51 to ST55 are repeated. If there is no change in the flying height, monitoring of the flying height change is terminated. In Fig. 9, after ST55, a judgment is made in ST56 and, if necessary, the flying height is adjusted in ST57. However, it is possible to only make the judgment in ST55 and terminate monitoring of the flying height change.

[0037] For example, when a change in flying height is detected, when monitoring has been abnormally terminated, or when monitoring has been terminated, the host 18 can be notified in any of the following cases. At this time, the SMART function can be used. This makes it possible to automatically monitor changes in the flying height of the magnetic recording / reproducing device in the background, invisible to the user, at any time before or after shipment, for example. In the description of FIG. 9, an example has been given in which the fourth position is a radial position different from the first and second positions, but it is also possible to use the first or second position as the fourth position.

[0038] Example 5 A fifth embodiment shows an example in which a further comparison is made when the temperature changes. FIG. 10 is a block diagram showing a configuration of yet another example of the magnetic recording and reproducing device according to the second embodiment. As shown in the figure, a magnetic recording and reproducing device 201 is a magnetic recording and reproducing device used in the fifth embodiment, and has the same configuration as that shown in FIG. 1, except that a temperature sensor 9-1 is further connected to the MPU 14-1. As shown in FIG. 2, the temperature sensor 9-1 is provided at an arbitrary position within the magnetic disk device in order to detect the temperature of the device atmosphere.

[0039] In the fifth embodiment, for example, instead of starting to monitor the change in flying height at a timing when the device is operable in the background, the comparative judgment of the change in flying height is started at a timing when it is determined that there is a temperature change based on temperature information from temperature sensor 9-1. In the same manner as in the fourth embodiment, except that the change in flying height can be judged by steps ST51 to ST57 in FIG. 9 between two or more different radial positions. The temperature information from the temperature sensor 9-1 can be set to be acquired at regular intervals. The temperature difference between the acquired temperature information can be calculated by the calculation unit 63. The determination unit 64 can determine whether a temperature change has occurred based on the temperature difference.

[0040] Example 6 A sixth embodiment shows an example in which a further comparison is made when the humidity changes. FIG. 11 is a block diagram showing the configuration of still another example of the magnetic recording and reproducing device according to the second embodiment. As shown in FIG. 11, the magnetic recording and reproducing device 202 has the same configuration as that in FIG. 1, except that the MPU 14-1 is provided with a humidity sensor 9-2. The humidity sensor 9-2 is provided at an arbitrary position in the magnetic disk device to detect the humidity of the device atmosphere. In Fig. 2, the humidity sensor 9-2 is provided in an empty space on the bottom wall 52a of the base 52, for example, between the magnetic disk 1 and a board unit (FPC unit) 53 on which electronic components such as a conversion connector are mounted, like the temperature sensor 9-1. If necessary, an air pressure sensor (not shown) and a temperature sensor similar to that in Fig. 8 can be further provided.

[0041] In the sixth embodiment, for example, instead of starting to monitor the change in flying height at a timing when the device is operable in the background, the comparative judgment of the change in flying height is started at a timing when it is determined that there is a humidity change based on humidity information from humidity sensor 9-2. In the same manner as in the fourth embodiment, except that the change in flying height can be judged by steps ST51 to ST57 in FIG. 9 between two or more different radial positions. The humidity information from the humidity sensor 9-2 can be set to be acquired at regular intervals. The humidity difference between the acquired humidity information can be calculated by the calculation unit 63. The determination unit 64 can determine whether there is a humidity change based on the humidity difference.

[0042] Example 7 A seventh embodiment shows an example in which a further comparison is made when the atmospheric pressure changes. FIG. 11 is a block diagram showing the configuration of still another example of the magnetic recording and reproducing device according to the second embodiment. As shown in FIG. 11, the magnetic recording and reproducing device 203 has the same configuration as that in FIG. 1, except that an air pressure sensor 9-3 is provided in the MPU 14-1. The air pressure sensor 9-3 is provided at an arbitrary position in the magnetic disk device to detect the air pressure in the device atmosphere. In Fig. 2, the air pressure sensor 9-3 is provided in an empty space on the bottom wall 52a of the base 52, for example, between a board unit (FPC unit) 53 on which electronic components such as a conversion connector are mounted, and the magnetic disk 1, like the temperature sensor 9-1. If necessary, an air pressure sensor (not shown) and a temperature sensor similar to that in Fig. 8 can be further provided.

[0043] In the sixth embodiment, for example, instead of starting to monitor the change in flying height at a timing when the device can operate in the background, the comparative judgment of the change in flying height is started at a timing when it is determined that there is a change in air pressure based on air pressure information from the air pressure sensor 9-3, but in the same manner as in the fourth embodiment, the change in flying height between two or more different radial positions can be judged by steps ST51 to ST57 in FIG. 9. The atmospheric pressure information from the atmospheric pressure sensor 9-3 can be set to be acquired at regular intervals. The atmospheric pressure difference between the acquired atmospheric pressure information can be calculated by the calculation unit 63. The determination unit 64 can determine that there is an atmospheric pressure change based on the atmospheric pressure difference.

[0044] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0045] 1...magnetic disk, 1a...recording surface, 10, 10W, 10R...thermally assisted magnetic recording head, 9-1...temperature sensor, 9-2...humidity sensor, 9-3...atmospheric pressure sensor, 18...host, 19...head position control unit, 61...write operation control unit, 62...error rate measurement unit, 63...calculation unit, 64...determination unit, 65...flying height adjustment unit, 200, 201, 202...magnetic recording and reproducing device

Claims

1. A method for adjusting a magnetic recording and reproducing device equipped with a thermally assisted magnetic recording head and a magnetic disk, comprising the steps of: performing a first write operation with the thermally assisted magnetic recording head at a first position on a recording surface of the magnetic disk; a first error rate is measured by seeking the thermally-assisted magnetic recording head to a second position on the recording surface that is different in a radial direction from the first position; After performing a second write operation at the second position, measuring a second error rate at the second location; calculating a first difference between the first error rate and the second error rate; seeking the thermally assisted magnetic recording head to the first position and measuring a third error rate; After performing a third write operation at the first position, measuring a fourth error rate at the first location; calculating a second difference between the third error rate and the fourth error rate; a step of comparing the first difference with the second difference to determine a change in flying height between the first position and the second position;

2. Before determining the change in flying height, the thermally-assisted magnetic recording head is moved to a third position, the third position being a radial position different from the first position and the second position, and a fifth error rate is measured; After a fourth write operation is performed at the third position, a sixth error rate is measured. determining a third difference between the fifth error rate and the sixth error rate; 2. The method for adjusting a magnetic recording and reproducing device according to claim 1, wherein determining the change in flying height comprises comparing the first difference, the second difference, and the third difference, and determining the change in flying height at the first position, the second position, and the third position.

3. When the temperature inside the magnetic recording / reproducing device changes, the thermally-assisted magnetic recording head is moved to a fourth position, the fourth position being a radial position different from the first position and the second position, and a sixth error rate is measured; measuring a seventh error rate after performing a fifth write operation at the fourth location; and A fourth difference between the sixth error rate and the seventh error rate is calculated.

2. The method of adjusting a magnetic recording / reproducing device according to claim 1, further comprising: comparing the first difference and / or the second difference with the fourth difference to determine a change in flying height at a fourth position.

4. When the humidity of the magnetic recording and reproducing device changes, the thermally-assisted magnetic recording head is moved to a fourth position, the fourth position being a radial position different from the first position and the second position, and a sixth error rate is measured; measuring a seventh error rate after performing a fifth write operation at the fourth location; and A fourth difference between the sixth error rate and the seventh error rate is calculated.

2. The method of adjusting a magnetic recording / reproducing device according to claim 1, further comprising: comparing the first difference and / or the second difference with the fourth difference to determine a change in flying height at a fourth position.

5. When the air pressure inside the magnetic recording and reproducing device changes, the thermally-assisted magnetic recording head is moved to a fourth position, the fourth position being a radial position different from the first position and the second position, and a sixth error rate is measured; measuring a seventh error rate after performing a fifth write operation at the fourth location; and A fourth difference between the sixth error rate and the seventh error rate is calculated.

2. The method of adjusting a magnetic recording / reproducing device according to claim 1, further comprising: comparing the first difference and / or the second difference with the fourth difference to determine a change in flying height at a fourth position.

6. When the magnetic recording and reproducing device is monitored in the background, the thermally-assisted magnetic recording head is moved to a fourth position, the fourth position being a radial position different from the first position and the second position, and a sixth error rate is measured; measuring a seventh error rate after performing a fifth write operation at the fourth location; and A fourth difference between the sixth error rate and the seventh error rate is calculated.

2. The method of adjusting a magnetic recording / reproducing device according to claim 1, further comprising: comparing the first difference and / or the second difference with the fourth difference to determine a change in flying height at a fourth position.

7. 7. The method of adjusting a magnetic recording / reproducing device according to claim 1, further comprising adjusting the flying height of the thermally assisted magnetic recording head when it is determined that there is a flying height change as a result of the determination.

8. 7. The method for adjusting a magnetic recording and reproducing device according to claim 6, further comprising notifying an externally connected host when it is determined that there is a change in flying height as a result of said determination.

9. 9. The method for adjusting a magnetic recording and reproducing device according to claim 8, wherein the notification to the host utilizes a SMART function.

10. a magnetic disk including a magnetic recording layer and a lubricant provided on a recording surface of the magnetic recording layer; a thermally assisted magnetic recording head for magnetically recording on the magnetic disk; a head position control unit that positions the thermally-assisted magnetic recording head at a first position on the recording surface or at a second position that is a radial position different from the first position; a write operation control unit that controls a first write operation at the first position, a second write operation at the second position, and a third write operation at the first position; an error rate measuring unit that measures a first error rate before the second write operation, a second error rate after the second write operation, a third error rate before the third write operation, and a fourth error rate after the third write operation; a calculation unit that calculates a first difference between the first error rate and the second error rate, and a second difference between the third error rate and the fourth error rate, The magnetic recording and reproducing device includes a determination unit that compares the first difference with the second difference and determines a change in flying height.

11. the head position control unit further disposes the thermally-assisted magnetic recording head at a third position that is a radial position different from the first position and the second position, the write operation control unit further controls a fourth write operation at the third position; the error rate measurement unit further measures a fifth error rate before the fourth write operation and a sixth error rate after the fourth write operation; The calculation unit further calculates a third difference between the fifth error rate and the sixth error rate; and 11. The magnetic recording and reproducing apparatus according to claim 10, further comprising: the determining section comparing the first difference, the second difference and the third difference to determine a change in flying height.

12. Further comprising a temperature sensor; the head position control unit seeks the thermally-assisted magnetic recording head to a fourth position that is a radial position different from the first position and the second position, the write operation control unit performs a fifth write operation at the fourth position; the error rate measurement unit measures a sixth error rate before the fifth write operation and a seventh error rate after the fifth write operation; and the calculation unit determines a temperature difference within the magnetic recording and reproducing device based on temperature information from the temperature sensor, and determines a fourth difference between the sixth error rate and the seventh error rate; 11. The magnetic recording and reproducing device according to claim 10, wherein the determination unit determines a temperature change based on information about the temperature difference, compares the first difference and / or the second difference with the fourth difference, and determines a change in the flying height at the fourth position.

13. Further comprising a humidity sensor; the head position control unit seeks the thermally-assisted magnetic recording head to a fourth position that is a radial position different from the first position and the second position, the write operation control unit performs a fifth write operation at the fourth position; the error rate measurement unit measures a sixth error rate before the fifth write operation and a seventh error rate after the fifth write operation; and the calculation unit determines a humidity difference within the magnetic recording and reproducing device based on humidity information from the humidity sensor, and determines a fourth difference between the sixth error rate and the seventh error rate; The magnetic recording and reproducing device according to claim 10 , wherein the determination unit determines a humidity change based on the information on the humidity difference, compares the first difference and / or the second difference with the fourth difference, and determines a change in the flying height at the fourth position.

14. Further comprising an air pressure sensor; the head position control unit seeks the thermally-assisted magnetic recording head to a fourth position that is a radial position different from the first position and the second position, the write operation control unit performs a fifth write operation at the fourth position; the error rate measurement unit measures a sixth error rate before the fifth write operation and a seventh error rate after the fifth write operation; and the calculation unit determines an air pressure difference within the magnetic recording and reproducing device based on air pressure information from the air pressure sensor, and determines a fourth difference between the sixth error rate and the seventh error rate; 11. The magnetic recording and reproducing device according to claim 10, wherein the determination unit determines a change in air pressure based on information on the air pressure difference, compares the first difference and / or the second difference with the fourth difference, and determines a change in the flying height at the fourth position.

15. the thermally assisted magnetic recording head is operable in the background; the head position control unit seeks the thermally-assisted magnetic recording head to a fourth position that is a radial position different from the first position and the second position, the write operation control unit performs a fifth write operation at the fourth position; the error rate measurement unit measures a sixth error rate before the fifth write operation and a seventh error rate after the fifth write operation; and the calculation unit determines a fourth difference between the sixth error rate and the seventh error rate; 11. The magnetic recording and reproducing apparatus according to claim 10, wherein the determining section compares the first difference and / or the second difference with the fourth difference to determine the flying height change at the fourth position.

16. a flying height adjustment unit that adjusts the flying height of the thermally assisted magnetic recording head, 16. The magnetic recording and reproducing device according to claim 10, wherein when it is determined that there is a change in flying height as a result of the determination, the flying height adjustment section adjusts the flying height of the thermally assisted magnetic recording head.

17. further including an external connection to the host; 16. The magnetic recording and reproducing apparatus according to claim 15, wherein if it is determined that there is a change in the flying height as a result of the determination, a host is notified of this.

18. 20. The magnetic recording and reproducing apparatus according to claim 17, wherein the notification to the host utilizes a smart function.

Images