Method for manufacturing magnetic disk device and magnetic disk device

Abstract

Provided are a method for manufacturing a magnetic disk device for efficiently recording auxiliary servo patterns and a magnetic disk device capable of efficiently recording auxiliary servo patterns. The manufacturing method includes estimating the distribution of initial values ​​of the gap of the magnetic head in the first recording surface; and recording a first spiral signal on the first recording surface while controlling the gap using the distribution of the estimated initial values ​​of the gap. The manufacturing method includes measuring the distribution of initial values ​​of the gap of the magnetic head in the second recording surface under positioning control using the first spiral signal recorded on the first recording surface. The manufacturing method includes controlling the gap using the distribution of initial values ​​of the gap of the magnetic head in the second recording surface measured, while recording the first spiral signal on the second recording surface. The manufacturing method includes recording a second spiral signal on the third recording surface under positioning control using the first spiral signal recorded on the second recording surface.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-153431 (filing date: September 21, 2021), and the present application incorporates the entire contents of the basic application by reference. Technical Field

[0002] The present embodiment relates to a method for manufacturing a magnetic disk device and a magnetic disk device. Background Art

[0003] In the manufacturing process of a magnetic disk device, after the magnetic disk is assembled in the magnetic disk device, the magnetic disk device records a product servo pattern on the magnetic disk with reference to an auxiliary servo pattern. Such a process of recording the product servo pattern on the magnetic disk by the magnetic disk device itself is known as self-servo writing (SSW).

[0004] In the process before SSW, an auxiliary servo pattern is recorded on a blank disk. The recording of the auxiliary servo pattern is sometimes performed by the disk device itself, similar to the production servo pattern. The process of recording the auxiliary servo pattern on a blank disk by the disk device itself is called blank disk self-servo writing (BDSSW). Summary of the invention

[0005] An object of one embodiment is to provide a method for manufacturing a magnetic disk device for efficiently recording an auxiliary servo pattern and a magnetic disk device capable of efficiently recording an auxiliary servo pattern.

[0006] One embodiment is a method for manufacturing a magnetic disk device, the magnetic disk device comprising: a plurality of magnetic disks that rotate as a whole and have a plurality of recording surfaces; and a plurality of magnetic heads that move as a whole in the radial direction of the plurality of magnetic disks and correspond to the plurality of recording surfaces. The manufacturing method includes the step of measuring the initial value of the clearance at a first position between a blank first recording surface among the plurality of recording surfaces and a first magnetic head among the plurality of magnetic heads corresponding to the first recording surface. The manufacturing method also includes the step of estimating the distribution of the initial value of the clearance between the first recording surface and the first magnetic head in the radial direction, i.e., the first distribution, based on the measured initial value of the clearance at the first position of the first recording surface. The manufacturing method also includes the step of controlling the clearance between the first recording surface and the first magnetic head using the estimated first distribution, i.e., the first data, while recording a plurality of first spiral signals to the first recording surface using the first magnetic head. The manufacturing method also includes the step of measuring the distribution of the initial value of the gap between the blank second recording surface different from the first recording surface among the plurality of recording surfaces and the second magnetic head corresponding to the second recording surface among the plurality of magnetic heads, i.e., the second distribution, under the positioning control using the plurality of first spiral signals recorded on the first recording surface. The manufacturing method also includes the step of using the second magnetic head to record the plurality of first spiral signals to the second recording surface while using the second distribution to control the gap between the second recording surface and the second magnetic head. The manufacturing method also includes the step of using the third magnetic head corresponding to the third recording surface among the plurality of magnetic heads to record the plurality of second spiral signals to the third recording surface different from the first recording surface and the second recording surface among the plurality of recording surfaces, under the positioning control using the plurality of first spiral signals recorded on the second recording surface. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a diagram showing an example of the structure of a magnetic disk device according to an embodiment.

[0008] Figure 2 It is a diagram for explaining the positional relationship between the actuator system and the magnetic disk according to the embodiment.

[0009] Figure 3 It is a diagram showing the structure of each magnetic head according to the embodiment when viewed from the recording surface side of the magnetic disk.

[0010] Figure 4 It is a cross-sectional view when each magnetic head according to the embodiment is cut along the extending direction of the suspension.

[0011] Figure 5 This is a schematic diagram showing an example of the shape of a product servo pattern recorded on a magnetic disk according to the embodiment.

[0012] Figure 6 This is a schematic diagram showing an example of an auxiliary servo pattern recorded on a magnetic disk according to an embodiment.

[0013] Figure 7 This is a schematic diagram showing an example of a plurality of first spiral signals recorded on a first spiral surface according to the embodiment.

[0014] Figure 8 This is a schematic diagram showing an example of the second number of second spiral signals recorded on the second spiral surface according to the embodiment.

[0015] Fig. 9 This is a flowchart showing an example of the blank disk self-servo writing operation executed by the magnetic disk device according to the embodiment.

[0016] Fig.10 It is a schematic diagram showing an example of the estimated distribution of the reference floating amount in the first helical surface #1 and the measured distribution of the reference floating amount in the first helical surface #1 acquired by the controller according to the embodiment.

[0017] Fig.11 This is a flowchart showing an example of details of the process of S110 included in the blank disk self-servo writing according to the embodiment.

[0018] Description of symbols

[0019] 1 disk device, 2 host, 10 disk, 11 SPM, 12 rotating axis, 20 actuator system, 21 actuator arm, 22 suspension, 24 rotating axis, 25 ramp loading mechanism, 26 stopper, 30 controller, 31 servo controller, 32 head amplifier, 33 non-volatile memory, 34 volatile memory, 35 processor, 36 RWC, 37 HDC, 41 write element, 42 read element, 43 HDI sensor, 44 heater, 50 product servo pattern, 61 1st spiral signal, 62 2nd spiral signal, 63 3rd spiral signal, HD, HD1-HD12 magnetic heads. DETAILED DESCRIPTION

[0020] Hereinafter, a method for manufacturing a magnetic disk device and a magnetic disk device according to an embodiment will be described in detail with reference to the drawings. Note that the present invention is not limited to the embodiment.

[0021] (Implementation Method)

[0022] Figure 11 is a diagram showing an example of the structure of the magnetic disk device 1 according to the embodiment. The magnetic disk device 1 can be connected to the host 2. The standard of the communication path between the magnetic disk device 1 and the host 2 is not limited to a specific standard. In one example, SAS (Serial Attached SCSI) can be used.

[0023] The host 2 may be, for example, a processor, a personal computer, or a server. The magnetic disk device 1 can receive access commands (read commands and write commands) from the host 2 .

[0024] The magnetic disk device 1 includes a plurality of magnetic disks 10 that rotate about a rotation axis 12 of a spindle motor (SPM) 11. Here, as an example, the magnetic disk device 1 includes six magnetic disks 10-1, 10-2, 10-3, 10-4, 10-5, and 10-6. The six magnetic disks 10-1, 10-2, 10-3, 10-4, 10-5, and 10-6 rotate integrally through the SPM 310.

[0025] Recording surfaces capable of recording data are formed on the front and back surfaces of the six magnetic disks 10. That is, the six magnetic disks 10 have 12 recording surfaces. In order to access each of the 12 recording surfaces, the magnetic disk device 1 includes 12 magnetic heads HD1 to HD12 corresponding to the 12 recording surfaces.

[0026] The magnetic head HD1 is arranged in a manner opposite to the surface of the disk 10-1. The magnetic head HD2 is arranged in a manner opposite to the back side of the disk 10-1. The magnetic head HD3 is arranged in a manner opposite to the surface of the disk 10-2. The magnetic head HD4 is arranged in a manner opposite to the back side of the disk 10-2. The magnetic head HD5 is arranged in a manner opposite to the surface of the disk 10-3. The magnetic head HD6 is arranged in a manner opposite to the back side of the disk 10-3. The magnetic head HD7 is arranged in a manner opposite to the surface of the disk 10-4. The magnetic head HD8 is arranged in a manner opposite to the back side of the disk 10-4. The magnetic head HD9 is arranged in a manner opposite to the surface of the disk 10-5. The magnetic head HD10 is arranged in a manner opposite to the back side of the disk 10-5. The magnetic head HD11 is arranged in a manner opposite to the surface of the disk 10-6. The magnetic head HD12 is arranged in a manner opposite to the back side of the disk 10-6.

[0027] Hereinafter, the twelve magnetic heads HD1 to HD12 are collectively referred to as magnetic heads HD. Each magnetic head HD can access a recording surface provided on a surface opposite to itself of the six magnetic disks 10, that is, can record and reproduce data.

[0028] The magnetic disk device 1 includes an actuator system 20 for moving 12 magnetic heads HD in an integrated manner. The actuator system 20 includes 7 actuator arms 21, 12 suspensions 22, and a voice coil motor (VCM) 23. Each of the 12 suspensions 22 included in the actuator system 20 supports any one of the magnetic heads HD1 to HD12. Each of the 12 suspensions 22 included in the actuator system 20 is mounted on the front end of any one of the 7 actuator arms 21.

[0029] The actuator system 20 can rotate around the rotation axis 24. The rotation axis 24 is provided at a position parallel to the rotation axis 12 and away from the rotation axis 12. The VCM 111 can rotate the actuator system 20 within a predetermined range around the rotation axis 24. Thus, the actuator system 20 can move the magnetic heads HD1 to HD12 relative to the recording surfaces of the magnetic disks 10-1 to 10-6 in the radial direction.

[0030] Figure 2 2 is a diagram for explaining the positional relationship between the actuator system 20 and the magnetic disk 10 involved in the embodiment. As shown in this figure, the actuator system 20 can make the magnetic head HD move relative to the recording surface of the magnetic disk 10 along the track T. The magnetic disk device 1 is provided with a ramp loading mechanism 25 for stopping each magnetic head HD on the track T near the outer end of the magnetic disk 10. In addition, the magnetic disk device 1 is provided with a stopper 26 for limiting the magnetic head HD from moving in the inner peripheral direction of the magnetic disk 10 beyond necessity. More specifically, when the magnetic head HD is at position P0, the actuator system 20 abuts against the stopper 26, thereby limiting the movement of the magnetic head HD to the inner peripheral side than the position P0. As a result, the magnetic head HD can move within the range from the ramp loading mechanism 25 to the position P0. In addition, the position P0 is an example of the first position.

[0031] The magnetic disk device 1 further includes a servo controller 31 , a head amplifier 32 , a nonvolatile memory 33 , a volatile memory 34 , a processor 35 , a RWC (read write channel) 36 , and a HDC (hard disk controller) 37 .

[0032] The head amplifier 32 supplies a signal corresponding to the write data input from the RWC 36 to the magnetic head HD facing the recording surface to be written. The head amplifier 32 amplifies a signal output from the magnetic head HD facing the recording surface to be read and supplies it to the RWC 36.

[0033] The nonvolatile memory 33 is constituted by a nonvolatile memory such as a flash memory, etc. The program executed by the processor 35 is recorded in the nonvolatile memory 33 .

[0034] The volatile memory 34 is composed of a volatile memory such as a DRAM (Dynamic Random Access Memory) or an SRAM (Static Random Access Memory). The volatile memory 34 is provided with an area for buffering write data received from the host 2 before being written to the disk 10 and read data read from the disk 10 before being sent to the host 2.

[0035] The RWC 36 modulates the write data buffered in the volatile memory 34 and outputs the modulated data to the head amplifier 32. In addition, the RWC 36 demodulates the signal supplied from the head amplifier 32 and outputs the modulated data to the HDC 37.

[0036] The HDC 37 is a communication interface that enables communication with the host 2. Specifically, when the HDC 37 receives a write command from the host 2, it stores the write data in the volatile memory 34, and when the writing of the write data to the magnetic disk 10 is completed, it returns a response to the host 2. In addition, when the HDC 37 receives a read command from the host 2, after the data (read data) requested to be read by the read command is read from the magnetic disk 10 and buffered in the volatile memory 34, the HDC 37 returns the read data buffered in the volatile memory 34 to the host 2.

[0037] The servo controller 31 supplies current or voltage to the spindle motor for rotating the SPM 11 , thereby rotating the spindle motor at a predetermined speed.

[0038] In addition, the servo controller 31 drives the VCM 23 in order to move the magnetic head HD to the position specified by the processor 35 .

[0039] The processor 35 is, for example, a CPU (Central Processing Unit) and executes various processes using a program stored in a nonvolatile storage medium such as the nonvolatile memory 33 or the magnetic disk 10 .

[0040] For example, the processor 35 controls writing and reading of data by the magnetic head HD, determines an access position on the recording surface of the magnetic disk 10 , and instructs the servo controller 31 on an access position.

[0041] The servo controller 31, the head amplifier 32, the nonvolatile memory 33, the volatile memory 34, the processor 35, the RWC 36, and the HDC 37 constitute the controller 30 according to the embodiment. In addition, the components of the controller 30 are not limited to these.

[0042] Next, an example of the details of the structure of each magnetic head HD is described. Each magnetic head HD is configured to be able to adjust the gap between the magnetic head HD and the surface of the magnetic disk 10 opposite to the magnetic head HD. The gap between the magnetic head HD and the surface of the magnetic disk 10 opposite to the magnetic head HD is also called the flying height. The smaller the flying height, the higher the quality of writing can be achieved. The technology of controlling the flying height in a way that makes the flying height as small as possible is called DFH (Dynamic Flying Height) technology.

[0043] The assembly accuracy of the magnetic head HD may vary for each magnetic head HD. In addition, the surface state (e.g., concavoconvexity, etc.) of the magnetic disk 10 may vary for each magnetic disk 10 and for each radial position of the magnetic disk 10. Therefore, in a state where six magnetic disks 10 and 12 magnetic heads HD are assembled, the gap between the magnetic head HD and the corresponding recording surface is different for each magnetic head HD, and also varies depending on the radial position within one recording surface.

[0044] In order to control the suspension amount of the magnetic head HD with high precision, it is necessary to obtain the gap in a state where the suspension amount is not controlled. The gap in a state where the suspension amount is not controlled is recorded as an initial value of the gap (or suspension amount). The initial value of the gap is obtained, for example, by detecting a state where the magnetic head HD contacts the surface of the magnetic disk 10. The state where the magnetic head HD contacts the surface of the magnetic disk 10 is called touch down.

[0045] Reference Figure 3 and Figure 4 An example of the structure of each magnetic head HD for enabling control of the flying amount will be described. Figure 3 1 is a diagram showing the structure of each magnetic head HD according to the embodiment when viewed from the recording surface side of the magnetic disk 10 . Figure 4 It is a cross-sectional view when each magnetic head HD according to the embodiment is cut along the extending direction of the suspension 22 .

[0046] like Figure 3 and Figure 4 As shown, the magnetic head HD includes a write element 41 , a read element 42 , an HDI (Head-Disk Interface) sensor 43 , and a heater 44 .

[0047] The write element 41 records data on the recording surface of the magnetic disk 10 using a magnetic field generated from its magnetic pole. The read element 42 reproduces data recorded on the magnetic disk 10 by reading changes in the magnetic field on the magnetic disk 10 as data.

[0048] In addition, according to Figure 3 and Figure 4In the example shown, one magnetic head HD is provided with one write element 41 and one read element 42. In one magnetic head HD, a plurality of either or both of the write element 41 and the read element 42 may be provided.

[0049] The heater 44 receives power from the head amplifier 32 to heat the magnetic head HD. The magnetic head HD is thermally deformed by the heating, and thus the floating amount F of the magnetic head HD from the magnetic disk 10 changes. More specifically, the more power is supplied to the heater 44, the greater the thermal expansion of the magnetic head HD, and thus the floating amount F decreases.

[0050] The HDI sensor 43 includes a resistor element (not shown). The resistor element can detect the contact, i.e., the landing, of the magnetic head HD and the recording surface of the magnetic disk 10. More specifically, if the magnetic head HD contacts the magnetic disk 10, the HDI sensor 43 changes thermally under the influence of frictional heat when the two contact. As a result, the resistance value of the resistor element changes. The change in the resistance value of the resistor element is detected by the head amplifier 32, and the contact between the magnetic head HD and the magnetic disk 10 is detected.

[0051] When the landing is detected, the power supplied to the heater 44 is gradually increased under the control of the head amplifier 32 by the processor 35. The magnetic head HD expands according to the increase of the power supplied to the heater 44, thereby reducing the floating amount F. And when the floating amount F becomes zero, the head amplifier 32 detects the contact between the magnetic head HD and the magnetic disk 10 by the change of the resistance value of the resistance element of the HDI sensor 43. In other words, the landing is detected. The processor 35 calculates the value of the floating amount F in the state where the power is not supplied to the heater 44 based on the power supplied to the heater 44 when the landing is detected. For example, the relationship between the power supplied to the heater 44 and the protrusion amount of the magnetic head HD is recorded in advance in a predetermined position (for example, the non-volatile memory 33). The processor 35 calculates the protrusion amount of the magnetic head HD when the landing is detected based on the relationship, and stores the protrusion amount obtained by the calculation as the floating amount F in the state where the gap is not controlled, that is, the initial value of the gap. The processor 35 can control the flying amount to a desired value based on the initial value of the gap and the relationship between the power supplied to the heater 44 and the protrusion amount of the magnetic head HD. Hereinafter, the initial value of the gap may be described as a reference flying amount.

[0052] In the case where the magnetic disk device 1 is used by an end user, in the magnetic disk device 1 , the controller 30 performs positioning of each magnetic head HD based on a product servo pattern recorded on each recording surface.

[0053] Figure 51 is a schematic diagram showing an example of the shape of a product servo pattern recorded on a magnetic disk 10 according to an embodiment. According to the example shown in this figure, the product servo pattern 50 is recorded radially. The product servo pattern 50 includes sector / cylinder information and a burst pattern. The sector / cylinder information provides a servo address (servo sector address) in the circumferential direction of the magnetic disk 10 and a position of a track set in the radial direction (track number). The track number obtained from the sector / cylinder information is an integer value, and the burst pattern indicates an offset below the decimal point based on the track number. The area between the areas on the track where the product servo pattern 50 is recorded is used as an area where data can be recorded.

[0054] In the manufacturing process, the magnetic disk device 1 performs self-servo writing. In self-servo writing, the magnetic disk device 1 records the product servo pattern 50 on the magnetic disk 10 based on the auxiliary servo pattern previously recorded on the magnetic disk 10. That is, the controller 30 records the product servo pattern under positioning control using the auxiliary servo pattern.

[0055] In the manufacturing process, the magnetic disk device 1 performs a blank disk self-servo write in which the auxiliary servo pattern is recorded by itself. In the blank disk self-servo write, the magnetic disk device 1 records the auxiliary servo pattern on at least one of the 12 recording surfaces. In the self-servo write, the magnetic disk device 1 records the product servo pattern 50 on all of the 12 recording surfaces based on the auxiliary servo pattern recorded on at least one recording surface.

[0056] Figure 6 6 is a schematic diagram showing an example of an auxiliary servo pattern recorded on a magnetic disk 10 according to an embodiment. In addition, the rotation direction of the magnetic disk 10 is depicted in this figure. As shown in this figure, the auxiliary servo pattern is composed of a plurality of spiral signals 63. The greater the number of spiral signals 63 constituting the auxiliary servo pattern, the higher the accuracy of positioning control in self-servo writing. Therefore, in self-servo writing on a blank disk, the controller 30 is configured so as to record as many spiral signals 63 as possible.

[0057] However, it is difficult to accurately record many spiral signals 63 at once on a blank magnetic disk 10. If many spiral signals 63 are recorded at once on a blank magnetic disk 10, the spiral signals 63 are deformed and the intervals between the spiral signals 63 in the circumferential direction of the magnetic disk 10 are uneven. Therefore, the controller 30 records the auxiliary servo pattern in a plurality of stages. Here, as an example, the controller 30 records the auxiliary servo pattern by processing in three stages.

[0058] Specifically, the controller 30 first records a plurality of first spiral signals on one recording surface (hereinafter referred to as a first spiral surface) among the 12 recording surfaces. Figure 7: is a schematic diagram showing an example of a plurality of first spiral signals recorded on the first spiral surface involved in the embodiment. As shown in this figure, the controller 30 first records a plurality of first spiral signals 61. In this example, eight first spiral signals 61 are recorded from the inner periphery to the outer periphery of the first spiral surface. In addition, the direction of recording the first spiral signal 61 is not limited to the direction from the inner periphery to the outer periphery. The first spiral signal 61 recorded on the first spiral surface is recorded as the first quantity. That is, in Figure 7 In the example shown, the first number is "8". In addition, the first number is not limited to "8".

[0059] Next, the controller 30 uses the first number of first spiral signals 61 already recorded on the first spiral surface for positioning control, while recording the second number of second spiral signals, which is greater than the first number, on other recording surfaces (recorded as second spiral surfaces) among the 12 recording surfaces that are different from the first spiral surface. Figure 8 2 is a schematic diagram showing an example of a second number of second spiral signals recorded on the second spiral surface according to the embodiment. In this example, 12 second spiral signals 62 are recorded from the outer circumference to the inner circumference of the second spiral surface. Figure 8 In the example shown, the second number is "12". In addition, the second number is not limited to "12". In addition, the direction of recording the second spiral signal 62 is not limited to the direction from the outer circumference to the inner circumference.

[0060] The controller 30 uses the second number of second spiral signals 62 recorded on the second spiral surface for positioning control, and records a plurality of spiral signals 63 constituting the auxiliary servo pattern on a recording surface (recorded as the third spiral surface) that is different from both the first spiral surface and the second spiral surface among the 12 recording surfaces. In addition, each of the plurality of spiral signals 63 constituting the auxiliary servo pattern is recorded as the third spiral signal 63. The number of spiral signals 63 constituting the auxiliary servo pattern is greater than the second number. According to Figure 6 In the example shown in FIG. 1 , the number of spiral signals 63 constituting the auxiliary servo pattern is “24”. In addition, the number of spiral signals 63 constituting the auxiliary servo pattern is not limited to “24”. Figure 6 In the example shown, each spiral signal 63 constituting the auxiliary servo pattern is recorded from the inner periphery to the outer periphery. The direction of recording each spiral signal 63 constituting the auxiliary servo pattern is not limited to the direction from the inner periphery to the outer periphery. Hereinafter, the number of the third spiral signals 63 constituting the auxiliary servo pattern is recorded as the third number.

[0061] Thus, the controller 30 realizes recording of the correct auxiliary servo pattern by increasing the number of spiral signals to be recorded in stages. In addition, the number of stages required for recording the auxiliary servo pattern is not limited to 3. The number of stages required for recording the auxiliary servo pattern may be 2 or 4 or more.

[0062] As described above, the controller 30 is configured to control the suspension amount for each magnetic head HD. By controlling the suspension amount to a relatively small value, the writing quality can be improved. In order to correctly control the suspension amount, it is necessary to obtain a reference suspension amount (i.e., an initial value of the gap) based on the landing detection. The acquisition of the reference suspension amount is also necessary when writing to a blank disk by self-servo.

[0063] Here, a technique (hereinafter referred to as a comparative example) compared with the embodiment is described. According to the comparative example, before recording a plurality of first spiral signals on the first spiral surface, a landing detection is performed at position P0 of the first spiral surface. In addition, position P0 is selected as the position for performing the landing detection because the controller can position the magnetic head at position P0 by making the actuator system abut against the stopper, but when all the magnetic disks are blank, the magnetic head cannot be positioned at a position other than position P0. After the landing detection at position P0 of the first spiral surface is performed, the reference suspension amount at a plurality of positions in the radial direction of the first spiral surface is estimated based on the detection result of the landing. The reference suspension amount at a plurality of positions in the radial direction of the first spiral surface is recorded as a distribution of the reference suspension amount. In addition, the estimation of the distribution of the reference suspension amount is performed, for example, based on the insights obtained in the past. After the estimation of the distribution of the reference suspension amount, the recording of a plurality of first spiral signals on the first spiral surface is performed while the suspension amount control using the estimated distribution of the reference suspension amount is performed. Then, under positioning control using the plurality of first spiral signals recorded on the first spiral surface, a plurality of second spiral signals are recorded on the second spiral surface.

[0064] However, the distribution of the estimated reference suspension amount sometimes deviates from the distribution of the actual reference suspension amount. In such a case, the quality of the plurality of first spiral signals recorded on the first spiral surface is poor. In the case where the quality of the plurality of first spiral signals recorded is poor, when the second spiral signal is recorded on the second spiral surface under the positioning control using the plurality of first spiral signals, tracking deviation sometimes occurs. That is, during the process of recording the second spiral signal, the magnetic head may be separated from the target position. In the case where tracking deviation occurs, the recording of the plurality of second spiral signals is performed again.

[0065] Thus, according to the comparative example, due to the deterioration of the quality of the plurality of first spiral signals, the recording of the plurality of second spiral signals may be performed again. As a result, the time required for self-servo writing on the blank disk may be prolonged. In other words, the recording efficiency of the auxiliary servo pattern is poor.

[0066] In contrast, according to the embodiment, the controller 30 is configured to measure the distribution of the reference floating amount in the first helical surface, and to record a plurality of first helical signals on the first helical surface while executing the floating amount control using the measured distribution of the reference floating amount in the first helical surface.

[0067] More specifically, two first helical surfaces #1 and first helical surface #2 are set. Then, the controller 30 estimates the distribution of the reference floating amount in the first helical surface #1 in the same steps as the comparative example, performs the floating amount control using the estimated distribution of the reference floating amount, and records the first spiral signal 61 on the first helical surface #1. Then, the controller 30 measures the distribution of the reference floating amount in the first helical surface #2 under the positioning control using the first spiral signal 61 recorded on the first helical surface #1. The controller 30 measures the distribution of the reference floating amount by detecting landing at a plurality of different radial positions. The controller 30 performs the floating amount control using the measured distribution of the reference floating amount of the first helical surface #2, and records a plurality of first spiral signals 61 on the first helical surface #2. The controller 30 records a plurality of second spiral signals 62 on the second helical surface under the positioning control using the plurality of first spiral signals 61 recorded on the first helical surface #2.

[0068] The plurality of first spiral signals 61 recorded on the first spiral surface #2 are performed based on the distribution of the measured reference suspension amount. Thus, the first spiral surface #2 on which the plurality of first spiral signals 61 with high quality are recorded can be obtained. Since the second spiral signal 62 is recorded under the positioning control using the plurality of first spiral signals 61 with high quality, the occurrence of tracking deviation during the recording of the second spiral signal 62 can be suppressed. Thus, the efficiency of recording the auxiliary servo pattern can be improved compared with the comparative example.

[0069] In addition, the 1st helical surface #1, the 1st helical surface #2, the 2nd helical surface and the 3rd helical surface can be determined in advance, or the controller 30 can select 4 recording surfaces from the 12 recording surfaces according to an arbitrary algorithm and set the 4 recording surfaces as the 1st helical surface #1, the 1st helical surface #2, the 2nd helical surface and the 3rd helical surface.

[0070] In addition, for example, in order to suppress the adverse effects generated between the wirings of each magnetic head HD built into the head amplifier 32, the first helical surface #1, the first helical surface #2, the second helical surface, and the third helical surface are selected so that the magnetic heads HD used in accessing them are not adjacent to each other. In addition, the method of selecting each helical surface is not limited to this.

[0071] In addition, the first helical surface #1 is an example of the first recording surface. The first helical surface #2 is an example of the second recording surface. The second helical surface is an example of the third recording surface. The third helical surface is an example of the fourth recording surface.

[0072] Next, the operation of the magnetic disk device 1 according to the embodiment will be described.

[0073] Fig. 9 This is a flowchart showing an example of blank disk self-servo writing operations performed by the magnetic disk device 1 according to the embodiment. The control of a series of blank disk self-servo writing operations shown in this figure is realized by, for example, the processor 35 executing a program in the nonvolatile memory 33 .

[0074] First, the controller 30 performs landing detection at the position P0 of the first helical surface #1 (S101). That is, the controller 30 measures a reference floating amount at the position P0 of the first helical surface #1.

[0075] Specifically, the controller 30 controls the SPM 11 to rotate the six magnetic disks 10 as a whole, and controls the actuator system 20 to unload the 12 magnetic heads HD from the ramp loading mechanism 25. Then, the controller 30 moves the 12 magnetic heads HD in the inner peripheral direction until the actuator system 20 abuts against the stopper 26. When the actuator system 20 abuts against the stopper 26, the magnetic head HD opposite to the first helical surface #1 is located at position P0. The controller 30 controls the magnetic head HD opposite to the first helical surface #1 to perform landing detection while the actuator system 20 is abutted against the stopper 26. Thus, the controller 30 obtains the measured value of the standard suspension amount at position P0 of the first helical surface #1.

[0076] In addition, the magnetic head HD facing the first helical surface # 1 is an example of a first magnetic head.

[0077] Next, the controller 30 estimates the distribution of the reference floating amount in the first helical surface #1 based on the result of the landing detection at the position P0 (S102). Hereinafter, the distribution of the reference floating amount obtained by estimation will be referred to as the estimated distribution of the reference floating amount.

[0078] Specifically, the controller 30 obtains the estimated distribution of the reference floating amount based on past knowledge. The manufacturer measures the distribution of the reference floating amount for many other magnetic disk devices in advance, and obtains the average of the distribution of the reference floating amounts of the many magnetic disk devices obtained by the measurement. The average of the distribution of the reference floating amount is stored in a predetermined position (for example, the non-volatile memory 33) of the controller 30. The controller 30 estimates the distribution of the reference floating amount based on the average of the distribution of the reference floating amount and the result of the landing detection at the position P0. For example, the controller 30 performs addition, subtraction, multiplication, or division operations on the average of the distribution of the reference floating amount so that the floating amount at the position P0 represented by the average of the distribution of the reference floating amount is consistent with the measured value of the floating amount at the position P0. The controller 30 obtains the estimated distribution of the reference floating amount through these operations. In addition, the method of obtaining the estimated distribution of the reference floating amount is not limited to this. The controller 30 may also be configured to obtain the estimated distribution of the reference floating amount by substituting the reference floating amount at the position P0 of the first helical surface #1 into a predetermined calculation formula. In addition, the controller 30 may be configured to obtain the estimated distribution of the reference suspension amount by using an AI (Artificial Intelligence) model.

[0079] In addition, the estimated distribution of the reference floating amount in the first helical surface #1 is an example of the first data.

[0080] Next, the controller 30 measures the range in the radial direction within which recording on the first helical surface # 1 is possible ( S103 ).

[0081] Specifically, the controller 30 moves the actuator system 20 from the movable limit on the outer circumference side to the movable limit on the inner circumference side (i.e., the position where the actuator system abuts against the stopper 26), and measures the movable range of the magnetic head HD relative to the first helical surface #1. The controller 30 sets the measured movable range of the magnetic head HD relative to the first helical surface #1 as the range in the radial direction that can be recorded.

[0082] Next, the controller 30 records the first number of first spiral signals 61 on the first spiral surface #1 while performing the levitation amount control using the estimated distribution of the reference levitation amount in the first spiral surface #1 (S104). The controller 30 records the first number of first spiral signals 61 in the recordable radial range obtained by the process of S103.

[0083] When recording of the first number of first spiral signals 61 on the first spiral surface # 1 is completed, the controller 30 determines to use the first number of first spiral signals 61 recorded on the first spiral surface # 1 for positioning control ( S105 ).

[0084] Next, the controller 30 measures the distribution of the reference suspension amount in the first helical surface #1 by performing landing detection at multiple positions of the first helical surface #1 (S106). In S106, the controller 30 sequentially positions the magnetic head HD relative to the first helical surface #1 at multiple different positions in the radial direction (recorded as radial positions) based on the first number of first spiral signals 61 recorded on the first helical surface #1. Then, the controller 30 performs landing detection at each of the multiple radial positions. Thus, the controller 30 can obtain the distribution of the reference suspension amount in the measured first helical surface #1. The distribution of the measured reference suspension amount is recorded as the measured distribution of the reference suspension amount.

[0085] Furthermore, the measured distribution of the reference floating amount in the first helical surface #1 is an example of the second data.

[0086] Next, the controller 30 performs landing detection at a plurality of radial positions of the first helical surface # 2 in the same procedure as S106 to measure the distribution of the reference floating amount on the first helical surface # 2 ( S107 ).

[0087] Next, the controller 30 performs landing detection at a plurality of radial positions of the second helical surface in the same procedure as S106 to measure the distribution of the reference floating amount on the second helical surface ( S108 ).

[0088] Next, the controller 30 performs landing detection at a plurality of radial positions of the third helical surface in the same procedure as S106 to measure the distribution of the reference floating amount on the third helical surface ( S109 ).

[0089] Next, the controller 30 determines whether the estimated distribution of the reference floating amount in the first helical surface #1 deviates from the measured distribution of the reference floating amount in the first helical surface #1 (S110). The details of the process of S110 will be described later.

[0090] When the estimated distribution of the reference floating amount in the first helical surface #1 deviates from the measured distribution of the reference floating amount in the first helical surface #1 (S110: Yes), it can be considered that the quality of the first number of first spiral signals 61 recorded on the first helical surface #1 is poor. Therefore, the controller 30 performs the processing of S111 to S112 to record the first number of first spiral signals 61 on the first helical surface #2.

[0091] In S111 , the controller 30 measures the range in the radial direction within which recording on the first helical surface # 2 can be achieved in the same procedure as in S103 ( S111 ).

[0092] In S112, the controller 30 records the first number of first spiral signals 61 on the first spiral surface #2 while performing the levitation control based on the measured distribution of the reference levitation in the first spiral surface #2 (S112). The controller 30 uses the magnetic head HD opposite to the first spiral surface #2 to record the first number of first spiral signals 61 in the radial range that can be recorded obtained by the process of S111.

[0093] Furthermore, the magnetic head HD facing the first helical surface #2 is an example of a second magnetic head.

[0094] When recording of the first number of first spiral signals 61 on the first spiral surface # 2 is completed, the controller 30 determines to use the first number of first spiral signals 61 recorded on the first spiral surface # 2 for positioning control ( S113 ).

[0095] Thus, when the estimated distribution of the reference floating amount in the first helical surface #1 deviates from the measured distribution of the reference floating amount in the first helical surface #1 (S110: Yes), the floating amount control using the measured distribution of the reference floating amount in the first helical surface #2 is performed while recording the first number of first spiral signals 61 on the first helical surface #2. Then, in the processing of S114 and S115 described later, the positioning control using the first number of first spiral signals 61 recorded on the first helical surface #2 is performed.

[0096] When the estimated distribution of the reference floating amount in the first helical surface #1 does not deviate from the measured distribution of the reference floating amount in the first helical surface #1 (S110: No), it can be considered that the quality of the first number of first spiral signals 61 recorded in the first helical surface #1 is sufficiently high. Therefore, the processing of S111 to S113 is skipped, and in the processing of S114 and S115 described later, positioning control using the first number of first spiral signals 61 recorded in the first helical surface #1 is performed.

[0097] Furthermore, the case where the estimated distribution of the reference floating amount in the first helical surface #1 does not deviate from the measured distribution of the reference floating amount in the first helical surface #1 (S110: No) is an example of the first case. The case where the estimated distribution of the reference floating amount in the first helical surface #1 deviates from the measured distribution of the reference floating amount in the first helical surface #1 (S110: Yes) is an example of the second case where the deviation between the first data and the second data is greater than the first case.

[0098] In S114 , the controller 30 learns the values ​​of various parameters necessary for recording the second number of second spiral signals 62 on the second spiral surface while moving the magnetic head HD facing the second spiral surface.

[0099] Then, in S115, the controller 30 records the second number of second spiral signals 62 on the second helical surface while performing the levitation amount control using the measurement distribution of the reference levitation amount in the second helical surface. The controller 30 records the second number of second spiral signals 62 using the magnetic head HD facing the second helical surface.

[0100] Furthermore, the magnetic head HD facing the second helical surface is an example of a third magnetic head.

[0101] After S115, the controller 30 determines to use the second number of second spiral signals 62 recorded on the second spiral surface for positioning control (S116). The controller 30 executes the processes of S117 and S118 under positioning control using the second number of second spiral signals 62 recorded on the second spiral surface.

[0102] In S117 , the controller 30 learns the values ​​of various parameters necessary for recording the third number of third spiral signals 63 on the third spiral surface while moving the magnetic head HD facing the third spiral surface.

[0103] Then, in S118, the controller 30 records the third number of third spiral signals 63 on the third helical surface while performing the levitation amount control using the measurement distribution of the reference levitation amount in the third helical surface. The controller 30 records the third number of third spiral signals 63 using the magnetic head HD facing the third helical surface.

[0104] Furthermore, the magnetic head HD facing the third helical surface is an example of a fourth magnetic head.

[0105] When the process of S118 is completed, the blank disk self-servo writing operation is completed. In the subsequent self-servo writing, the controller 30 records the product servo pattern 50 on all the recording surfaces under positioning control using the third number of third spiral signals 63 recorded on the third spiral surface.

[0106] Next, the details of the process of S110 will be described. In S110, the controller 30 compares the estimated distribution of the reference floating amount in the first helical surface #1 with the measured distribution of the reference floating amount in the first helical surface #1.

[0107] Fig.10 It is a schematic diagram showing an example of the estimated distribution of the reference floating amount in the first helical surface # 1 and the measured distribution of the reference floating amount in the first helical surface # 1 acquired by the controller 30 according to the embodiment.

[0108] exist Fig.10In the example shown, a total of 10 radial positions, namely, P0, P1, P2, P3, P4, P5, P6, P7, P8 and P9, are set in this order from the inner circumference of the magnetic disk 10. The distribution of the reference suspension amount (measured distribution and estimated distribution) is a collection of estimated values ​​or measured values ​​of the reference suspension amount when the magnetic head HD is located at each of the radial positions P1 to P9. In other words, the distribution of the reference suspension amount (measured distribution and estimated distribution) includes the reference suspension amounts at the plurality of radial positions P1 to P9. The method for setting the radial position at which the estimated value or measured value of the reference suspension amount is obtained is arbitrary. The radial position at which the estimated value or measured value of the reference suspension amount is obtained can be set, for example, for each zone.

[0109] exist Fig.10 In the example shown, the estimated distribution and measured distribution of the reference floating amount in the first helical surface #1 are different except for the reference floating amount at position P0. In S110, the controller 30 compares the estimated value and the measured value of the reference floating amount for each radial position.

[0110] Fig.11 1 is a flowchart showing an example of the details of the processing of S110 included in the blank disk self-servo writing according to the embodiment. In the description of this figure, the position Px represents the radial position where the estimated value or measured value of the reference floating amount is obtained. The subscript "x" of Px is an integer from 0 to imax. Fig.10 In the example shown, imax is "9".

[0111] First, the controller 30 initializes i, which is a loop index, to "0" (S201). Then, the controller 30 determines whether the difference between the measured value and the estimated value of the reference suspension amount at the position Pi exceeds a threshold value (S202). A positive value is preset as the threshold value. The threshold value is preset according to the degree of deviation allowed between the estimated distribution and the measured distribution of the reference suspension amount.

[0112] When the difference between the measured value and the estimated value of the reference floating amount at the position Pi exceeds the threshold value ( S202 : YES), the controller 30 determines that the estimated distribution of the reference floating amount deviates from the measured distribution ( S203 ), and the process of S110 ends.

[0113] When the difference between the measured value and the estimated value of the reference suspension amount at the position Pi does not exceed the threshold value (S202: No), the controller 30 determines whether i is equal to imax (S204). When i is not equal to imax (S204: No), the controller 30 increases i by 1 (S205) and executes the process of S202 again.

[0114] When i and imax are equal ( S204 : YES), the controller 30 determines that the estimated distribution of the reference suspension amount does not deviate from the measured distribution ( S206 ), and the process of S110 ends.

[0115] In addition, Fig.11 In the example shown, when the difference between the measured value and the estimated value of the reference floating amount at the position Pi is equal to the threshold, the controller 30 executes the process of S204. The process of the case where the difference between the measured value and the estimated value of the reference floating amount at the position Pi is equal to the threshold is not limited to this. When the difference between the measured value and the estimated value of the reference floating amount at the position Pi is equal to the threshold, the controller 30 may also execute the process of S203.

[0116] In addition, Fig. 9 In the example shown, it is determined in S110 whether the estimated distribution of the reference floating amount in the first helical surface #1 deviates from the measured distribution. If it is determined that the estimated distribution of the reference floating amount in the first helical surface #1 does not deviate from the measured distribution, the processing of S111 to S113 is skipped. The processing of S110 may be discarded and the controller 30 may be configured to always execute the processing of S111 to S113.

[0117] As described above, according to the embodiment, the controller 30 measures the reference suspension amount at the position P0 of the blank first helical surface #1, and estimates the distribution of the reference suspension amount in the first helical surface #1 based on the measured value of the reference suspension amount at the position P0 of the first helical surface #1 (for example, referring to Fig. 9 Then, the controller 30 uses the estimated distribution of the reference suspension amount in the first helical surface #1 to control the suspension amount of the magnetic head HD relative to the first helical surface #1, and records a plurality of first spiral signals 61 (for example, referring to Fig. 9 Then, the controller 30 measures the distribution of the reference suspension amount in the blank first helical surface #2 (for example, referring to Fig. 9 Then, the controller 30 performs the suspension amount control using the measured distribution of the reference suspension amount in the first helical surface #2, while recording a plurality of first helical signals 61 (for example, referring to Fig. 9 Then, the controller 30 records a plurality of second spiral signals 62 (for example, referring to S112) on the second spiral surface under positioning control using a plurality of first spiral signals 61 recorded on the first spiral surface #2. Fig. 9 S113, S115).

[0118] This allows position control using the plurality of high-quality first spiral signals 61 to be performed, thereby suppressing the occurrence of tracking deviation when recording the plurality of second spiral signals 62. This allows the auxiliary servo pattern to be recorded efficiently.

[0119] According to the embodiment, the controller 30 measures the distribution of the reference suspension amount in the first helical surface #1 (for example, referring to Fig. 9 Then, the controller 30 compares the estimated distribution of the reference suspension amount in the first spiral surface #1 with the measured distribution (for example, referring to Fig. 9 S110 and Fig.11 ). Furthermore, when the estimated distribution of the reference suspension amount in the first helical surface #1 does not deviate from the measured distribution, the controller 30 records a plurality of second helical signals 62 (for example, referring to the first helical signal 61 recorded on the first helical surface #1) on the second helical surface under positioning control using the plurality of first helical signals 61 recorded on the first helical surface #1. Fig. 9 In the case where the estimated distribution of the reference suspension amount in the first helical surface #1 deviates from the measured distribution, the controller 30 records a plurality of first helical signals 61 to the first helical surface #2, and records a plurality of second helical signals 62 to the second helical surface under positioning control using the plurality of first helical signals 61 recorded on the first helical surface #2 (for example, referring to Fig. 9 S112, S113, S115 when it is judged as yes in S110).

[0120] When the estimated distribution of the reference suspension amount in the first helical surface #1 does not deviate from the measured distribution, it can be considered that the quality of the plurality of first spiral signals 61 recorded on the first helical surface #1 is high. In such a case, the recording of the plurality of second spiral signals 62 on the second helical surface is performed under the positioning control using the plurality of first spiral signals 61 recorded on the first helical surface #1. Thus, the occurrence of tracking deviation can be suppressed when recording the plurality of second spiral signals 62. Thus, the auxiliary servo pattern can be efficiently recorded.

[0121] In addition, according to the embodiment, the controller 30 calculates the difference between the estimated value and the measured value of the reference suspension amount in the first helical surface #1 for each radial position. Then, when all the differences at each radial position do not meet the threshold value, the controller 30 determines that the estimated distribution of the reference suspension amount in the first helical surface #1 does not deviate from the measured distribution. When at least one of all the differences at each radial position exceeds the threshold value, the controller 30 determines that the estimated distribution of the reference suspension amount in the first helical surface #1 deviates from the measured distribution (for example, referring to Fig.11 ).

[0122] Even when the estimated distribution of the reference floating amount in the first spiral surface #1 includes one estimated value with poor accuracy, the controller 30 performs floating amount control using the measured distribution of the reference floating amount in the first spiral surface #1 while re-executing the recording of the plurality of first spiral signals 61. Thus, the occurrence of tracking deviation can be suppressed when recording the plurality of second spiral signals 62. Thus, the auxiliary servo pattern can be recorded efficiently.

[0123] According to the embodiment, the controller 30 measures the distribution of the reference suspension amount in the second helical surface under positioning control using the plurality of first helical signals 61 recorded on the first helical surface #1 (for example, referring to Fig. 9 Then, the controller 30 performs the suspension amount control using the measured distribution of the reference suspension amount in the second helical surface, while recording a plurality of second helical signals 62 (for example, referring to Fig. 9 S115).

[0124] This can improve the quality of the plurality of second spiral signals 62 recorded on the second spiral surface.

[0125] In addition, as an example, the auxiliary servo pattern is recorded by three stages of processing. In this case, the controller 30 records a plurality of third spiral signals 63 (see FIG. 1 ) on the third spiral surface under positioning control using a plurality of second spiral signals 62 recorded on the second spiral surface. Fig. 9 (S116, S118).

[0126] In addition, according to the embodiment, the plurality of first spiral signals 61 is a first number of first spiral signals 61, the plurality of second spiral signals 62 is a second number of second spiral signals 62, and the plurality of third spiral signals 63 is a third number of third spiral signals 63. The second number is larger than the first number, and the third number is larger than the second number. In addition, the magnitude relationship among the first number, the second number, and the third number is arbitrary.

[0127] Fig. 9 and Fig.11 The above-mentioned actions are executed by the controller 30 . Fig. 9 and Fig.11 The above-mentioned operation is performed by the controller 30 under the control of the processor 35 according to a predetermined program (for example, a program stored in advance in the non-volatile memory 33). Specifically, the processor 35 controls the servo controller 31, the head amplifier 32, the non-volatile memory 33, the volatile memory 34, the RWC 36, and the HDC 37 according to the program. As a result, the servo controller 31, the head amplifier 32, the non-volatile memory 33, the volatile memory 34, the processor 35, the RWC 36, and the HDC 37 realize Fig. 9 and Fig.11 Action shown.

[0128] In addition, part or all of the functions of the processor 35 may be implemented by other components (such as the servo controller 31, the head amplifier 32, the RWC 36, or the HDC 37) in the controller 30. In addition, part or all of the functions of the processor 35 may be implemented by hardware circuits such as FPGA (Field-Programmable Gate Array) or ASIC (Application Specific Integrated Circuit).

[0129] 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 ways, and various omissions, substitutions, and changes can be made without departing from the scope of the subject matter of the invention. These embodiments and / or their variations are included in the scope and subject matter of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A method for manufacturing a magnetic disk device, the magnetic disk device comprising: a plurality of magnetic disks rotating in an integrated manner and having a plurality of recording surfaces; and a plurality of magnetic heads, which move integrally in the radial direction of the plurality of magnetic disks and correspond to the plurality of recording surfaces, The manufacturing method comprises: measuring an initial value of a gap at a first position between a blank first recording surface among the plurality of recording surfaces and a first magnetic head among the plurality of magnetic heads corresponding to the first recording surface; estimating a first distribution based on the measured initial value of the gap at the first position of the first recording surface, the first distribution being a distribution in the radial direction of the initial value of the gap between the first recording surface and the first magnetic head; while controlling the gap between the first recording surface and the first magnetic head using the estimated first distribution, i.e., first data, and recording a plurality of first spiral signals on the first recording surface using the first magnetic head; Under positioning control using the plurality of first spiral signals recorded on the first recording surface, measuring a second distribution, the second distribution being a distribution in the radial direction of an initial value of a gap between a blank second recording surface different from the first recording surface among the plurality of recording surfaces and a second magnetic head corresponding to the second recording surface among the plurality of magnetic heads; recording the plurality of first spiral signals on the second recording surface using the second magnetic head while controlling a gap between the second recording surface and the second magnetic head using the measured second distribution; and Under the positioning control of the multiple first spiral signals recorded on the second recording surface, multiple second spiral signals are recorded on a third recording surface among the multiple recording surfaces that is different from the first recording surface and the second recording surface, using a third magnetic head among the multiple magnetic heads corresponding to the third recording surface.

2. The manufacturing method according to claim 1, further comprising: measuring the first distribution under positioning control using the plurality of first spiral signals recorded on the first recording surface; comparing the first data with the measured first distribution, that is, second data; as well as In the first case, the plurality of second spiral signals are recorded on the third recording surface using the third magnetic head under the positioning control using the plurality of first spiral signals recorded on the first recording surface, and in the second case where the deviation between the first data and the second data is larger than that in the first case, the plurality of first spiral signals are recorded on the second recording surface and the plurality of second spiral signals are recorded on the third recording surface under the positioning control using the plurality of first spiral signals recorded on the second recording surface.

3. The manufacturing method according to claim 2, The first distribution includes initial values ​​of the gaps at a plurality of different radial positions. Comparing the first data with the second data includes: calculating, for each radial position, a difference between an initial value of the gap included in the first data and an initial value of the gap included in the second data, The first case is a case where all the differences in the radial positions do not satisfy a threshold value, and the second case is a case where at least one of the differences in the radial positions exceeds the threshold value.

4. The production method according to any one of claims 1 to 3, Also includes: measuring a third distribution under positioning control using the plurality of first spiral signals recorded on the first recording surface, the third distribution being a distribution in the radial direction of an initial value of a gap between the third recording surface and the third magnetic head, Recording the plurality of second spiral signals on the third recording surface using the third magnetic head includes recording the plurality of second spiral signals while controlling a gap between the third recording surface and the third magnetic head using the measured third distribution.

5. The production method according to any one of claims 1 to 3, Also includes: Under the positioning control of the multiple second spiral signals recorded on the third recording surface, multiple third spiral signals are recorded on a fourth recording surface among the multiple recording surfaces that is different from the first recording surface, the second recording surface, and the third recording surface, using a fourth magnetic head among the multiple magnetic heads corresponding to the fourth recording surface.

6. The production method according to any one of claims 1 to 3, The plurality of first spiral signals are a first number of first spiral signals, The plurality of second spiral signals are a second number of second spiral signals, The second number is greater than the first number.

7. The manufacturing method according to claim 5, The plurality of first spiral signals are a first number of first spiral signals, The plurality of second spiral signals are a second number of second spiral signals, The plurality of third spiral signals are a third number of third spiral signals, The second number is greater than the first number, The third number is greater than the second number.

8. A magnetic disk device comprising: A plurality of magnetic disks rotate integrally and have a plurality of recording surfaces; A plurality of magnetic heads corresponding to the plurality of recording surfaces; an actuator system for moving the plurality of magnetic heads integrally in a radial direction of the plurality of magnetic disks; and Controller, The controller is composed of: measuring an initial value of a gap at a first position between a blank first recording surface among the plurality of recording surfaces and a first magnetic head among the plurality of magnetic heads corresponding to the first recording surface; estimating a first distribution based on the measured initial value of the gap at the first position of the first recording surface, the first distribution being a distribution in the radial direction of the initial value of the gap between the first recording surface and the first magnetic head; while controlling the gap between the first recording surface and the first magnetic head using the estimated first distribution, i.e., first data, and recording a plurality of first spiral signals on the first recording surface using the first magnetic head; Under positioning control using the plurality of first spiral signals recorded on the first recording surface, measuring a second distribution, the second distribution being a distribution in the radial direction of an initial value of a gap between a second recording surface different from the first recording surface among the plurality of recording surfaces and a second magnetic head corresponding to the second recording surface among the plurality of magnetic heads; recording the plurality of first spiral signals on the second recording surface using the second magnetic head while controlling the gap between the second recording surface and the second magnetic head using the measured second distribution; as well as Under the positioning control of the multiple first spiral signals recorded on the second recording surface, multiple second spiral signals are recorded on a third recording surface among the multiple recording surfaces that is different from the first recording surface and the second recording surface, using a third magnetic head among the multiple magnetic heads corresponding to the third recording surface.

Images