Manufacturing method for magnetic disk device

Abstract

To provide a manufacturing method for a magnetic disk device capable of improving the quality of a first spiral pattern and improving reliability.SOLUTION: A manufacturing method for a magnetic disk device includes: detecting a plurality of second floating amounts of magnetic heads at a plurality of arbitrary positions by performing a detection operation for detecting the floating amount of the magnetic head at the plurality of arbitrary positions between a first position and a second position; determining a second distribution of the floating amount of the magnetic head from the first position to the second position based on the plurality of second floating amounts; and writing a spiral servo pattern on the recording surface by a write head while controlling the power supplied to the heater based on the second distribution.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] An embodiment of the present invention relates to a method for manufacturing a magnetic disk drive. [Background technology]

[0002] Conventionally, when performing self-servo writing on a magnetic disk with a blank recording surface, the magnetic head is moved to a position where its movement is restricted by a stopper, and touchdown is performed at the above position to detect the flying height of the magnetic head at the innermost circumference. At this time, since there is no pattern on the recording surface, positioning (also called "tracking") is not possible in areas other than the above position, and touchdown cannot be performed in areas other than the above position.

[0003] That is, the distribution of the flying height of other areas was estimated based on the flying height of the innermost circumference and the average flying height profile of many units obtained in another process, and the first spiral pattern (also called "CGS (Coarse Guide Spiral) pattern") was written on the recording surface using a flying height with a sufficient margin for the estimated distribution. In this case, there was a tendency for the estimated flying height to deviate from the actual flying height, which could lead to a deterioration in the quality of the CGS pattern. As a result, there was a problem that positioning errors (also called "tracking deviation") were likely to occur when tracking a poor-quality CGS pattern to write the next second spiral pattern (also called "FGS (Fine Guide Spiral) pattern") on the recording surface. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] US Patent Application Publication No. 2023 / 0088258 [Patent Document 2] US Patent Application Publication No. 2023 / 0084200 [Patent Document 3] U.S. Patent No. 7,719,785 Summary of the Invention [Problem to be solved by the invention]

[0005] This embodiment provides a method for manufacturing a magnetic disk drive that can improve the quality of the first spiral pattern and thereby improve reliability. [Means for solving the problem]

[0006] A method for manufacturing a magnetic disk device according to one embodiment includes a magnetic head having a magnetic disk having a recording surface, a write head for writing data to the recording surface, a heater for heating the write head, and a detection unit for detecting whether the write head is in contact with the magnetic disk, a stopper for restricting movement of the magnetic head from a first position toward the center of the magnetic disk in the radial direction of the magnetic disk, a ramp load mechanism for holding the magnetic head at a second position that is located on the outer periphery side in the radial direction than the first position, and a controller for calculating a protrusion amount of the magnetic head based on power supplied to the heater, moving the magnetic head to the first position; increasing power supplied to the heater until the magnetic head contacts the magnetic disk; calculating a first flying height of the magnetic head at the first position before increasing the power supplied to the heater based on the power when the magnetic head is in contact with the magnetic disk; estimating a first distribution of flying heights of the magnetic head from the first position to the second position based on the first flying height and a reference distribution previously stored in a memory of the controller; and moving the magnetic head between the first position and the second position a plurality of times while controlling the power supplied to the heater based on the first distribution. and returning the magnetic head to the first position, specifying the distance from the first position to the second position and determining the moving speed of the magnetic head, positioning the magnetic head at the moving speed at a plurality of arbitrary positions between the first position and the second position, and performing a detection operation to detect the flying height of the magnetic head, thereby detecting a plurality of second flying heights of the magnetic head at the plurality of arbitrary positions, determining a second distribution of the flying height of the magnetic head from the first position to the second position based on the plurality of second flying heights, and writing a spiral servo pattern on the recording surface with the write head while controlling the power supplied to the heater based on the second distribution. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a block diagram showing the configuration of a magnetic disk device according to an embodiment. [Diagram 2] FIG. 2 is a perspective view showing the magnetic head and the magnetic disk of the magnetic disk device according to the embodiment. [Diagram 3] FIG. 3 is a plan view showing an example of a servo pattern. [Figure 4] FIG. 4 is an enlarged cross-sectional view showing the magnetic head and magnetic disk of the magnetic disk device according to the embodiment. [Diagram 5] FIG. 5 is a graph showing the relationship between the flying height of the magnetic head and the position of the magnetic head in the radial direction. [Figure 6]FIG. 6 is a graph showing the relationship between the flying height of the magnetic head and the position of the magnetic head in the radial direction. [Figure 7] FIG. 7 is a plan view showing the recording surface on which the first spiral pattern is written. [Figure 8] FIG. 8 is a plan view showing the recording surface on which the second spiral pattern is written. [Figure 9] FIG. 9 is a plan view showing the recording surface on which the third spiral pattern is written. [Figure 10] FIG. 10 is a flowchart showing the procedure for blank disk self-servo writing in the magnetic disk device according to the embodiment. [Figure 11] FIG. 11 is a flowchart showing a procedure for performing touchdown in an untouched area and detecting the second flying height. [Figure 12] FIG. 12 is a flowchart following FIG. 11, showing the procedure for performing touchdown in the untouched down area and detecting the second flying height amount. [Figure 13] FIG. 13 is a flowchart following FIG. 12, showing the procedure for performing touchdown in the untouched down area and detecting the second flying height amount. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, the embodiment of the present invention will be described with reference to the drawings. Note that the disclosure is merely an example, and any suitable modification that a person skilled in the art can easily conceive of while maintaining the gist of the invention is naturally included in the scope of the present invention. In addition, in order to make the drawings and explanation clearer, the width, thickness, shape, etc. of each part may be shown in a schematic manner compared to the actual embodiment, but this is merely an example and does 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. A magnetic disk drive and a method for manufacturing a magnetic disk drive according to an embodiment will be described in detail below with reference to the drawings.

[0009] First, the configuration of the magnetic disk device 10 will be described. FIG. 1 is a block diagram showing the configuration of a magnetic disk device 10 according to an embodiment. As shown in FIG. 1, the magnetic disk device 10 includes a rectangular housing 11, a magnetic disk 12 as a recording medium arranged within the housing 11, a spindle motor 14 that supports and rotates the magnetic disk 12, and a plurality of magnetic heads 16 that write (record) and read (reproduce) data on the magnetic disk 12.

[0010] The magnetic disk device 10 is equipped with a head actuator 18 that moves and positions the magnetic head 16 over any track on the magnetic disk 12. The head actuator 18 includes a carriage assembly 20 that movably supports the magnetic head 16, and a voice coil motor (VCM) 22 that rotates the carriage assembly 20. The carriage assembly 20 has a bearing portion 24 rotatably supported by the housing 11, and a plurality of suspensions 26 extending from the bearing portion 24. The magnetic head 16 is supported at the tip of each suspension 26, and moves along a trajectory T when the carriage assembly 20 rotates.

[0011] The magnetic disk device 10 includes a stopper ST that limits the movement of the magnetic head 16, and a ramp load mechanism RL that can hold the magnetic head 16. The stopper ST prevents the magnetic head 16 from moving too far toward the inner periphery of the magnetic disk 12. More specifically, the VCM 22, which rotates around a bearing portion 24, comes into contact with the stopper ST, thereby limiting the movement of the magnetic head 16. The ramp load mechanism RL is located in an area where the magnetic head 16 can move, and is located outside the outermost periphery of the magnetic disk 12 in the radial direction. As configured as described above, the magnetic head 16 can move along a trajectory T from a first position P1, where the movement is restricted by a stopper ST, to a second position (unload position) P2, where the magnetic head 16 is held by a ramp load mechanism RL. In one example, the first position P1 is an area facing the innermost periphery of the magnetic disk 12.

[0012] The magnetic disk device 10 includes a head amplifier IC (preamplifier) ​​30 that drives the magnetic head 16, a main controller 40, and a driver IC 48. The head amplifier IC 30 is electrically connected to the magnetic head 16. The head amplifier IC 30 includes a recording current supply circuit 32 that supplies a recording current to the recording coil of the magnetic head 16, and a heater power supply circuit 34 that supplies power to a heater H, which will be described later.

[0013] The main controller 40 and the driver IC 48 are configured, for example, on a control circuit board (not shown) provided on the rear side of the housing 11. The main controller 40 includes an R / W channel 42, a hard disk controller (HDC) 44, a microprocessor (MPU) 46, a memory 47, etc. The main controller 40 is electrically connected to the VCM 22 and the spindle motor 14 via the driver IC 48. The HDC 44 is connectable to a host computer (host) 45.

[0014] The R / W channel 42 is a signal processing circuit for read / write data. The HDC 44 controls data transfer between the host 45 and the R / W channel 42 in response to instructions from the MPU 46. The HDC 44 is electrically connected to, for example, the R / W channel 42, the MPU 46, and a memory 47. The memory 47 includes a volatile memory and a non-volatile memory. For example, the memory 47 includes a buffer memory made of a DRAM and a flash memory. The memory 47 stores programs and parameters necessary for the processing of the MPU 46.

[0015] The MPU 46 is the main control unit of the magnetic disk device 10, and executes servo control necessary for controlling read / write operations and positioning the magnetic head 16. The MPU 46 includes a write control unit 46a that controls write processing, a read control unit 46b that controls read processing, a heater control unit 46c that controls the power value supplied to a heater H described below, and a calculation unit 46d that calculates the protrusion amount of the magnetic head 16.

[0016] The write control unit 46a controls the data write process in accordance with commands from the host 45 etc. Specifically, the write control unit 46a controls the VCM 22 via the driver IC 48, positions the magnetic head 16 at a predetermined position on the magnetic disk 12, and writes data. The read control unit 46b controls the data read process in accordance with commands from the host 45 etc. Specifically, the read control unit 46b controls the VCM 22 via the driver IC 48, positions the magnetic head 16 at a predetermined position on the magnetic disk 12, and reads the data. The calculation unit 46 d calculates the protrusion amount of the magnetic head 16 based on the relationship between the power value of the heater H and the protrusion amount of the magnetic head 16 that is stored in advance in the memory 47 .

[0017] Fig. 2 is a perspective view showing the magnetic head 16 and the magnetic disk 12 of the magnetic disk device 10 according to the embodiment. As shown in Fig. 2, the magnetic disk device 10 has a plurality of magnetic heads 16 and a plurality of magnetic disks 12. The plurality of magnetic heads 16 and the plurality of magnetic disks 12 are positioned side by side along the rotation axis a. Each magnetic disk 12 has a pair of recording surfaces S, and includes a plurality of tracks Tr along the circumferential direction and a plurality of sectors C formed by dividing the tracks Tr in the circumferential direction. The tracks Tr are aligned in the radial direction. As will be described later in the description of FIG. 3, a servo pattern is written on the recording surfaces S.

[0018] Each magnetic head 16 faces one recording surface S. The main controller 40 can individually control each magnetic head 16. For example, the main controller 40 can control the heater power supply circuit 34 with the heater control unit 46c to individually adjust the power value supplied to each magnetic head 16.

[0019] FIG. 3 is a plan view showing an example of a servo pattern. As shown in FIG. 3, the recording surface S of the magnetic disk 12 has a plurality of servo patterns (also referred to as "product servo patterns") PSV used in the final product, and a plurality of auxiliary servo patterns (e.g., a plurality of first spiral servo patterns (also referred to as "CGS (Coarse Guide Spiral) patterns"), a plurality of second spiral servo patterns (also referred to as "FGS (Fine Guide Spiral) patterns"), and a plurality of third spiral servo patterns (also referred to as "FS (Final Spiral) patterns") BSV) that are different from the plurality of product servo patterns PSV. The product servo pattern PSV is written on the recording surface S by self-servo writing while using the auxiliary servo pattern BSV written in the blank disk self-servo write process for positioning control of the magnetic head 16 .

[0020] 4 is an enlarged cross-sectional view showing the magnetic head 16 and the magnetic disk 12 of the magnetic disk device 10 according to the embodiment. As shown in FIG. 3, the magnetic head 16 has a write head 16W and a read head 16R formed by a thin film process at the end of the slider 15, and is formed as a separate head. The slider 15 has an ABS (Air Bearing Surface: head surface) 13, which is a surface facing the recording surface S of the magnetic disk 12 in order to float from the recording surface S of the magnetic disk 12. The write head 16W writes data onto the magnetic disk 12. The read head 16R reads data recorded on the magnetic disk 12.

[0021] The magnetic disk 12 is configured as a perpendicular magnetic recording medium. The magnetic disk 12 is formed in a disk shape having a diameter of, for example, 96 mm (about 3.5 inches) and has a substrate 101 made of a non-magnetic material. On each surface (recording surface S) of the substrate 101, a soft magnetic layer 102 made of a material exhibiting soft magnetic properties as an underlayer is laminated in this order, and on the upper layer thereof, a perpendicular magnetic recording layer 103 having magnetic anisotropy in a direction perpendicular to the surface of the magnetic disk 12, and a protective film 104 are laminated in this order. The magnetic disk 12 is coaxially fitted to the hub of a spindle motor 14. The magnetic disk 12 is rotated by the spindle motor 14 at a predetermined speed in the direction of arrow B (see FIG. 1).

[0022] The read head 16R has a magnetoresistive element 55, and a first magnetic shield film 56 and a second magnetic shield film 57 arranged to sandwich the magnetoresistive element 55 in the longitudinal direction LD of the recording track formed on the perpendicular magnetic recording layer 103. The magnetoresistive element 55 and the magnetic shield films 56, 57 extend almost perpendicular to the ABS 13. The lower ends (tips) of the magnetoresistive element 55 and the magnetic shield films 56, 57 slightly protrude from the ABS 13.

[0023] The write head 16W has a main pole 60, a return pole 62, a non-conductor 52, a leading pole 64, a second connection portion 67, a first write coil 70, and a second write coil 72. The main pole 60, the return pole 62, and the leading pole 64 are formed of a highly permeable material. The main pole 60 and the return pole 62 constitute a first magnetic core that forms a magnetic path, and the main pole 60 and the leading pole 64 constitute a second magnetic core that forms a magnetic path. The main pole 60 extends almost perpendicular to the ABS 13. A tip 60a of the main pole 60 on the ABS 13 side tapers toward the ABS 13 and is formed in a columnar shape that is narrower than other portions. The tip 60a of the main pole 60 protrudes slightly from the ABS 13 of the slider 15.

[0024] The return pole 62 is provided to efficiently close the magnetic path via the soft magnetic layer 102 of the magnetic disk 12 directly below the main pole 60. The return pole 62 is formed in a substantially L-shape, and its tip 62a is formed in a thin and long rectangle. The tip 62a of the return pole 62 protrudes slightly from the ABS 13 of the slider 15. The tip 62a has a pole tip surface 62b that faces the tip 60a of the main pole 60 across the write gap WG. The pole tip surface 62b extends perpendicularly or slightly inclined with respect to the ABS 13. The return pole 62 has a first connection part 50 connected to the main pole 60. The first connection part 50 is magnetically connected to an upper part of the main pole 60, i.e., a part of the main pole 60 away from the ABS 13, via a non-conductor 52. The first recording coil 70 is wound around the first connection part 50 in the first magnetic core, for example. When writing a signal to the magnetic disk 12, a write current is passed through the first recording coil 70, whereby the first recording coil 70 excites the main pole 60 and passes a magnetic flux through the main pole 60.

[0025] The leading pole 64 is provided on the leading side of the main pole 60 so as to face the main pole 60. The leading pole 64 is formed in a substantially L-shape, and a tip portion 64a on the ABS 13 side is formed in a long and narrow rectangular shape. The tip portion 64a protrudes slightly from the ABS 13 of the slider 15. The tip portion 64a has a pole tip face 64b which faces the tip portion 60a of the main pole 60 with a gap therebetween. The leading pole 64 also has a second connection portion 67 joined to the main pole 60 at a position spaced apart from the ABS 13. This second connection portion 67 is formed of, for example, a soft magnetic material, and is magnetically connected to the upper portion of the main pole 60, i.e., the portion of the main pole 60 spaced apart from the ABS 13, via a non-conductor 59. As a result, the second connection portion 67 forms a magnetic circuit together with the main pole 60 and the leading pole 64. The second write coil 72 is arranged, for example, wound around the second connection portion 67, and applies a magnetic field to this magnetic circuit.

[0026] Further, the magnetic head 16 has a heater H and a detection unit 74. In one example, the heater H is composed of a first heater H1 for heating the write head 16W and a second heater H2 for heating the read head 16R. The first heater H1 and the second heater H2 are connected to the head amplifier IC 30 via wiring and a connection terminal 43, respectively. A desired power value is supplied to each of the first heater H1 and the second heater H2 from the heater power supply circuit 34 of the head amplifier IC 30. When power is supplied to the heater H (the first heater H1 and the second heater H2), the magnetic head 16 (the write head 16W and the read head 16R) is protruded toward the magnetic disk 12. The heater H is not limited to being composed of two heaters, the first heater H1 and the second heater H2, and may be composed of, for example, one heater that heats the write head 16W.

[0027] The detection unit 74 is provided near the heater H, and in one example, is located between the first heater H1 and the second heater H2. The detection unit 74 can detect contact between the magnetic disk 12 and the magnetic head 16. The detection unit 74 can also detect that the magnetic head 16 is held by the ramp load mechanism RL, i.e., that the magnetic head 16 has moved to the second position P2. In one example, the detection unit 74 is a head disk interface (HDI) sensor that detects a change in electrical resistance value caused by a temperature change. Specifically, when the power supplied to the heater H is increased and the magnetic head 16 comes into contact with the magnetic disk 12, frictional heat is generated between the magnetic head 16 and the magnetic disk 12, and the temperature of the HDI sensor changes (increases). At this time, the electrical resistance value of the HDI sensor, which is a resistive element, changes, making it possible to detect that the magnetic head 16 has come into contact with the magnetic disk 12.

[0028] Here, a method for detecting that the magnetic head 16 is located at the second position P2 will be described. Furthermore, when the magnetic head 16 is moved from the first position P1 to the second position P2, if the magnetic head 16 is located above the magnetic disk 12, the magnetic head 16 is kept at a constant temperature by the air flowing into the ABS 13. However, when the magnetic head 16 moves to the second position P1, the cooling by the air ceases and the temperature of the magnetic head 16 rises. From the above, if the detection unit 74 is an HDI sensor, it is possible to detect whether the magnetic head 16 is located at the second position P2 by monitoring the change in electrical resistance. The method of detecting that the magnetic head 16 is located at the second position P2 is not limited to the above method, and a method of monitoring the current supplied to the VCM 22 may also be used.

[0029] Hereinafter, "supplying power to the heater H to bring the magnetic head 16 into contact with the magnetic disk 12" will also be referred to as "touchdown." As described above, when the magnetic head 16 is in contact with the magnetic disk 12, the detection unit 74 can detect the contact. The calculation unit 46d calculates the protrusion amount of the magnetic head 16 at this time, thereby making it possible to detect the flying height of the magnetic head 16 before touchdown is started. In other words, the main controller 40 performs touchdown by increasing the power supplied to the heater H, detects that the magnetic head 16 is in contact with the magnetic disk 12 with the detection unit 74, and calculates the protrusion amount of the magnetic head 16 from the power supplied to the heater at that time, thereby detecting the flying height of the magnetic head 16 before touchdown is started. The magnetic disk device 10 is configured as described above.

[0030] Next, the blank disk self-servo write of the magnetic disk device 10 according to this embodiment will be described. Fig. 5 is a graph showing the relationship between the flying height of the magnetic head 16 and the position in the radial direction of the magnetic head 16. Fig. 6 is a graph showing the relationship between the flying height of the magnetic head 16 and the position in the radial direction of the magnetic head 16. Fig. 7 is a plan view showing the recording surface S on which the first spiral pattern is written. Fig. 8 is a plan view showing the recording surface S on which the second spiral pattern is written. Fig. 9 is a plan view showing the recording surface S on which the third spiral pattern is written. Fig. 10 is a flowchart showing the procedure of blank disk self-servo writing in the magnetic disk device 10 according to the embodiment.

[0031] 10, when the blank disk self-servo write process is started, first, the main controller 40 moves the magnetic head 16, which writes data to one recording surface S (hereinafter referred to as the "first spiral surface") among the multiple recording surfaces, to a first position P1 (S1), and performs touchdown to detect a first flying height F1 of the magnetic head 16 (S2). The first flying height F1 is the flying height of the magnetic head 16 before increasing the power supplied to the heater H for touchdown. The protrusion amount of the magnetic head 16 at this time (when touching down at the first position P1) is referred to as the "inner circumference side TD value."

[0032] Next, the main controller 40 estimates a first distribution D1 of the flying height of the magnetic head in the radial direction based on the first flying height F1 and a reference distribution (in one example, an average distribution AVE of the flying height of the magnetic head obtained in the past for another magnetic disk device) (S3). In the example shown in Fig. 5, the first distribution D1 is indicated by a dashed line, the first flying height F1 is indicated by a black circle, and the average distribution AVE is indicated by a solid line. In the example shown in Fig. 5, the first distribution D1 is lower than the average distribution AVE.

[0033] After estimating the first distribution D1 (S3), the main controller 40 executes lamp learning (S4). Now, the lamp learning will be described in detail. Ramp learning is a process that calculates the distance that the magnetic head 16 can move (in one example, the distance from the first position P1 to the second position P2) and determines the optimal speed of the magnetic head 16 based on the calculated distance. Specifically, it is a process that determines the distance from the first position P1 to the second position P2 and the optimal speed of the magnetic head 16 by repeatedly executing a load operation that moves the magnetic head 16 from the first position P1 to the second position P2 while adjusting the speed of the magnetic head 16 and an unload operation that moves the magnetic head 16 from the second position P2 to the first position P1.

[0034] In one example, the main controller 40 executes the load operation and the unload operation while controlling the power supplied to the heater H based on the first distribution D1 estimated in step S3. More specifically, the load operation and the unload operation are executed while controlling the power supplied to the heater H so that the protrusion amount of the magnetic head 16 is such that the magnetic head 16 does not contact the magnetic disk 12.

[0035] As a method for determining the optimal moving speed of the magnetic head 16, for example, if the number of data sampled by the magnetic head 16 in one load operation is 500 and the number of data to be sampled by the magnetic head 16 is desired to be 495, the moving speed of the magnetic head 16 can be increased so that the number of data sampled in one load operation becomes 495. According to the above method, it is possible to determine the moving speed of the magnetic head 16 that can sample the desired number of data in one load operation. Also, the distance from the first position P1 to the second position P2 can be calculated based on the time it takes for the magnetic head 16 to move from the first position P1 to the second position P2 and the moving speed of the magnetic head 16. In addition, when the number of sampled data is 500, it can be predicted that the intermediate position between the first position P1 and the second position P2 is located between the position where the number of sampled data is 250 and the position where the number of sampled data is 251. In other words, by obtaining the distance from the first position P1 to the second position P2 and determining the movement speed of the magnetic head 16, it is possible to identify where the magnetic head 16 is located between the first position P1 and the second position P2.

[0036] After executing the ramp learning (S4), the main controller 40 positions the magnetic head 16 at the moving speed determined in step S4 in the region between the first position P1 and the second position P2 (hereinafter also referred to as the "untouched down region"), executes touchdown, and detects a second flying height F2 corresponding to the actual flying height of the magnetic head 16 (S5). Details of step S5 will be described later in the description of Figs. 11 to 13. Next, the main controller 40 determines a second distribution D2 of the flying height of the magnetic head 16 from the first position P1 to the second position P2 based on the first flying height F1 and the second flying height F2 (S6). The second distribution D2 corresponds to the distribution of the actual flying height of the magnetic head 16 before increasing the power supplied to the heater H for touchdown. In the example shown in Fig. 6, the second flying height F2 is multiple (9 locations) and is indicated by white circles. The second distribution D2 is indicated by a dashed line.

[0037] Next, the main controller 40 writes the first spiral servo pattern SV1 on the first spiral surface S with the magnetic head 16 while controlling the power supplied to the heater H based on the second distribution D2 (S7). More specifically, the main controller 40 controls the power supplied to the heater H so that the size of the gap between the magnetic head 16 and the magnetic disk 12 becomes an optimal size. The above-mentioned optimal size is a size where the magnetic head 16 does not come into contact with the magnetic disk 12 and where the first spiral servo pattern SV1 can be written with high accuracy. In step S7, the main controller 40 may control the power supplied to the heater H based on the first distribution D1 and the second flying height F2, instead of the second distribution D2. In the example shown in FIG. 7, the first spiral servo pattern SV1 is written eight times, but the number of times it is written is not limited to eight.

[0038] Next, the main controller 40 performs touchdown on two recording surfaces S (hereinafter referred to as the "second spiral surface" and the "third spiral surface") different from the first spiral surface S among the multiple recording surfaces S while positioning (tracking) the magnetic head 16 based on the first spiral servo pattern SV1, and detects the flying height of the magnetic head 16 corresponding to the second spiral surface S and the flying height of the magnetic head 16 corresponding to the third spiral surface S (S8). In step S8, touchdown is performed at any multiple points from the first position P1 to the second position P2, and the distribution of the flying height of the magnetic head 16 from the first position P1 to the second position P2 is detected.

[0039] Next, the main controller 40 writes the second spiral servo pattern SV2 on the second spiral surface S with the magnetic head 16 (S9). In the example shown in FIG. 8, the second spiral servo pattern SV2 is written 12 times, but the number of times it is written is not limited to 12. Next, the main controller 40 writes the third spiral servo pattern SV3 on the third spiral surface S with the magnetic head 16 (S10), and ends the blank-disk self-servo write process. In the example shown in FIG. 9, the third spiral servo pattern SV3 is written 24 times, but the number of times it is written is not limited to 24.

[0040] Next, the process of performing touchdown in the untouched down area and detecting the second flying height (step S5 in FIG. 10) will be described in detail. Fig. 11 is a flowchart showing the procedure for performing touchdown in an untouched down area and detecting the second flying height F2. Fig. 12 is a flowchart following Fig. 11 showing the procedure for performing touchdown in an untouched down area and detecting the second flying height F2. Fig. 13 is a flowchart following Fig. 12 showing the procedure for performing touchdown in an untouched down area and detecting the second flying height F2. Figs. 11 to 13 show a process for identifying the flying height of area z5 as an example.

[0041] 11, when step S5 is started, the main controller 40 moves the magnetic head 16 to the first position (S501) and controls the heater power supply circuit 34 to reduce the protrusion amount of the magnetic head 16 by a predetermined amount (back-off amount) BO from the inner circumference side TD value (S502). Next, the main controller 40 determines the rate X of increase in the protrusion amount in one detection operation (S503) and sets an upper limit value of the number of detections N (S504). Next, the main controller 40 sets the end of the process of step S5 when the magnetic head 16 is held by the ramp load mechanism RL, in other words, when the magnetic head 16 moves to the second position P2 (S505).

[0042] Next, the main controller 40 drives the VCM 22 to start the load / unload operation (S506) and judges whether the magnetic head 16 is located around the area z5 (S507). In the graph of FIG. 5, the area around the area z5 is, for example, an area from the midpoint between the area z6 and the area z5 to the midpoint between the area z5 and the area z4. If the magnetic head 16 is not located around the area z5 (S507), the main controller 40 reduces the protrusion amount of the magnetic head 16 (S508) and executes step S507 again. In step S508, the main controller 40 may reduce the protrusion amount until it becomes almost 0, for example, so that the magnetic head 16 can be prevented from contacting the magnetic disk 12. In addition, if the detection unit 74 is an HDI sensor, in step S508, the electric resistance value detected by the detection unit 74 may be monitored to confirm whether the magnetic head 16 is located at the second position P2.

[0043] If the magnetic head 16 is located near the area z5 (S507), the main controller 40 increases the protrusion amount of the magnetic head 16 (S509). More specifically, the protrusion amount DFHz5 in the area z5 is increased to a value obtained by adding the value obtained by multiplying the detection count N by the rate of increase X to the flying height D1z5 in the area z5 of the first distribution D1 and subtracting the back-off amount BO. The protrusion amount DFHz5 in the area z5 can be expressed by the following formula. DFHz5=D1z5+N×X-BO For example, if the flying height D1z5 is 115 nm, the number of detections N is the first, the rate of increase X is 3 nm, and the back-off amount BO is 2 nm, the protrusion amount DFHz5 of the magnetic disk 12 in step S509 is 116 nm.

[0044] Next, the main controller 40 determines whether or not the magnetic head 16 has come into contact with the magnetic disk 12 based on the detection result of the detection unit 74 (S510), and if the magnetic head 16 has come into contact with the magnetic disk 12, stores the protrusion amount DFHz5 at this time in the memory 47 (S511), reduces the protrusion amount of the magnetic head 16 (S512), and terminates the processing of step S5. In one example, whether or not the magnetic head 16 has come into contact with the magnetic disk 12 is determined based on the result of detection by the HDI sensor. If the detector 74 is an HDI sensor, in step S512, the electrical resistance value detected by the detector 74 may be monitored to confirm whether or not the magnetic head 16 is located at the second position P2.

[0045] If the magnetic head 16 is not in contact with the magnetic disk 12 (S510), the main controller 40 clears the value detected by the detection unit 74 (in one example, the power value corresponding to the change in electrical resistance value detected by the HDI sensor) and stores the current number of detections in the memory 47 (S513). Thereafter, the main controller 40 determines whether or not the number of detection times N has reached the upper limit value determined in step S504 (S514), and if the number of detection times N has not reached the upper limit value, the process proceeds to step S506.

[0046] On the other hand, if the number of detection times N has reached the upper limit (S514), the main controller 40 ends the process of step S5. When the detection count N reaches the upper limit and the process of step S5 is terminated, the protrusion amount DFHz5 when the detection count N reaches the upper limit may be stored in the memory 47 as the second flying height F2. Moreover, touchdown can be performed in a similar manner in areas other than area z5, and the flying height can be obtained.

[0047] The effects of this embodiment will be described. According to the magnetic disk device 10 of this embodiment, the magnetic disk device 10 performs ramp learning while controlling the power supplied to the heater H based on the first distribution D1 estimated based on the first flying height F1, detects multiple second flying heights F2 of the magnetic head 16 at multiple arbitrary positions in the area between the first position and the second position, determines (calculates) the second distribution D2 based on the multiple second flying heights F2, and writes a spiral servo pattern (in one example, the first spiral servo pattern SV) while controlling the power supplied to the heater H based on the second distribution D2.

[0048] This improves the accuracy of the first spiral servo pattern SV1, and also improves the accuracy of the second spiral servo pattern SV2 and the third spiral servo pattern written based on the first spiral servo pattern SV1. In addition, the accuracy of the product servo pattern PSV written based on the above-mentioned auxiliary servo pattern BSV is also improved, so that a highly reliable manufacturing method for the magnetic disk device 10 can be obtained.

[0049] Although the embodiment of the present invention has been described, the above embodiment is presented as an example and is not intended to limit the scope of the invention. The above-mentioned novel embodiment can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the gist of the invention. The above-mentioned embodiment and its modifications are included in the scope and gist of the invention, and are included in the scope of the invention and its equivalents described in the claims. [Explanation of symbols]

[0050] 10...magnetic disk device, 12...magnetic disk, 16...magnetic head, 16W...write head, 40...main controller, 46c...heater control unit, 46d...calculation unit, 47...memory, 74...detection unit, BO...back-off amount, D1...first distribution, D2...second distribution, F1...first flying height, F2...second flying height, H...heater, N...number of detections, P1...first position, P2...second position, RL...ramp load mechanism, S...recording surface, SV1...first spiral servo pattern, SV2...second spiral servo pattern, SV3...third spiral servo pattern, X...proportion.

Claims

1. a magnetic disk having a recording surface; a magnetic head having a write head for writing data onto the recording surface, a heater for heating the write head, and a detection unit for detecting whether the write head is in contact with the magnetic disk; a stopper that limits movement of the magnetic head toward the center of the magnetic disk from a first position in a radial direction of the magnetic disk; a ramp load mechanism that holds the magnetic head at a second position that is located on the outer circumferential side of the first position in the radial direction; a controller that calculates a protrusion amount of the magnetic head based on an electric power supplied to the heater, moving the magnetic head to the first position, increasing the power supplied to the heater until the magnetic head comes into contact with the magnetic disk, and calculating a first flying height of the magnetic head at the first position before increasing the power supplied to the heater based on the power when the magnetic head is in contact with the magnetic disk; estimating a first distribution of flying heights of the magnetic head from the first position to the second position based on the first flying height and a reference distribution previously stored in a memory of the controller; While controlling the power supplied to the heater based on the first distribution, the magnetic head is caused to reciprocate a plurality of times between the first position and the second position, and a distance from the first position to the second position and a moving speed of the magnetic head are determined; positioning the magnetic head at the moving speed at a plurality of arbitrary positions between the first position and the second position, and performing a detection operation to detect a flying height of the magnetic head, thereby detecting a plurality of second flying heights of the magnetic head at the plurality of arbitrary positions; determining a second distribution of flying heights of the magnetic head from the first position to the second position based on the plurality of second flying heights; writing a spiral servo pattern onto the recording surface with the write head while controlling the power supplied to the heater based on the second distribution; A method for manufacturing a magnetic disk device.

2. The detection unit is an HDI sensor. The method for manufacturing the magnetic disk drive according to claim 1 .

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