Magnetic disk device and control method thereof

Abstract

Provided are a magnetic disk device capable of accurately and reliably detecting a synchronization mark of a spiral pattern, and a control method therefor. A magnetic disk device according to an embodiment writes a plurality of adjustment patterns having different frequencies to each magnetic disk through each magnetic head. Each adjustment pattern written in is read by each magnetic head, and the number of synchronization marks included in the read signal is detected. The frequency of the adjustment pattern for obtaining the detection number greater than or equal to the threshold value is selected as the writing frequency of each magnetic head. A spiral pattern having the same frequency as each selected writing frequency is written to each magnetic disk by each magnetic head. While tracking the written spiral pattern, a servo pattern serving as a reference for positioning control of a seek of each magnetic head is written to each magnetic disk by each magnetic head.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2024-158384 (filed on September 12, 2024). This application incorporates the entire contents of the basic application by reference to that basic application. Technical Field

[0002] Embodiments of the present invention relate to a disk device having multiple disks and multiple read / write heads, and a control method thereof. Background Technology

[0003] The controller of a disk device, which has multiple disks and multiple read / write heads for writing / reading data to each disk, performs a process called SSW (Self Servo Write) in the manufacturing process of the disk device, which writes multiple servo patterns to each disk, which is a blank medium without any records, to serve as a reference for the positioning control of each read / write head.

[0004] In this process, the controller writes a guide spiral pattern to one disk using one read / write head, and simultaneously tracks the written guide spiral pattern with each read / write head while writing a final spiral pattern to each disk using each read / write head.

[0005] Then, the controller uses each read / write head to track each final spiral pattern being written, and writes a servo pattern (called the product servo pattern) to each disk through each read / write head, which serves as the reference for the positioning control of each read / write head.

[0006] The guiding spiral pattern and the final spiral pattern are magnetic patterns in which the magnetic intensity changes at a predetermined frequency and includes a sync mark in each predetermined cycle.

[0007] When the aforementioned controller uses the magnetic head to track the guide spiral pattern and the final spiral pattern, it detects the signal component corresponding to the synchronization mark from the read signal of the magnetic head, and controls the movement of the magnetic head based on the detection result.

[0008] The data write width (width in the direction orthogonal to the write direction) of the multiple heads mounted on a disk drive is not constant due to manufacturing variations. There are cases where a wide spiral pattern is written and cases where a narrow spiral pattern is written.

[0009] When writing a narrow spiral pattern, the read area of ​​the read head for that spiral pattern becomes smaller. In this case, the read signal from the read head contains less of the synchronization marker signal component, which can lead to errors in tracking the spiral pattern. This error becomes a major cause of the deterioration in the write accuracy of the servo pattern. Summary of the Invention

[0010] Embodiments of the present invention provide a disk device and a control method thereof capable of accurately and reliably detecting synchronization marks of spiral patterns.

[0011] The disk device of this embodiment includes: a plurality of rotatable disks; a plurality of read / write heads capable of seeking along the radial direction of each disk and writing and reading data for each disk; and a controller that controls the rotation of each disk and the seeking of each read / write head. The controller writes a plurality of adjustment patterns at different frequencies to each disk via each read / write head, each pattern including a synchronization marker in each predetermined cycle; reads each written adjustment pattern with each read / write head, and detects the number of signal components of the synchronization marker included in the read signal of each read / write head; selects the frequency of the adjustment pattern whose detected number is above a threshold as the write frequency of each read / write head; writes a plurality of spiral patterns with the same frequency as the selected write frequency to each disk via each read / write head, each spiral pattern including a synchronization marker in each predetermined cycle; and while tracking the written spiral patterns with each read / write head, writes a servo pattern to each disk via each read / write head that serves as a reference for positioning control of the seeking of each read / write head. Attached Figure Description

[0012] Figure 1 This is a diagram showing the configuration of the first to third embodiments.

[0013] Figure 2 This is a diagram showing the composition of the main parts of the magnetic head in each embodiment.

[0014] Figure 3 It is a diagram showing the relationship between each disk and each read / write head in each implementation.

[0015] Figure 4 This is a graph showing the seek speed of each magnetic head in each implementation.

[0016] Figure 5 This is a flowchart illustrating the control process of the first embodiment.

[0017] Figure 6 It is a diagram showing the format of the pattern written by each magnetic head in each embodiment.

[0018] Figure 7This is a diagram showing the guide spiral patterns in each implementation.

[0019] Figure 8 It is a diagram showing the magnetic changes and synchronization marks of each spiral pattern in each embodiment.

[0020] Figure 9 This is a diagram showing the final spiral patterns in each implementation.

[0021] Figure 10 This is a diagram showing how the offset of the read and write elements of the magnetic head varies depending on the seek position of the magnetic head in each embodiment.

[0022] Figure 11 This is a diagram showing the servo patterns in each implementation.

[0023] Figure 12 This is a diagram showing the various adjustment patterns in each implementation method.

[0024] Figure 13 It is a graph showing the differences in the frequency of each adjustment pattern in each embodiment.

[0025] Figure 14 It is a diagram that shows the corresponding states of the reading element of the magnetic head and the adjustment pattern L2 in each embodiment together with the reading signal of the magnetic head.

[0026] Figure 15 It is a diagram that shows the corresponding states of the reading element and adjustment pattern L3 of the magnetic head in each embodiment together with the reading signal of the magnetic head.

[0027] Figure 16 It is a graph showing the relationship between the number of synchronization markers detected from the read signals of each magnetic head and the seek position (zone) of each magnetic head.

[0028] Figure 17 This is a graph showing the relationship between the number of synchronization markers detected from the read signals of each head and the seek position (partition) of each head in each embodiment.

[0029] Figure 18 This diagram illustrates the generation units for the data reading clock signal and the data writing clock signal in each embodiment.

[0030] Figure 19 This is a graph showing the relationship between the frequency of the final spiral pattern B and the product servo pattern C in each embodiment and the seek position of the magnetic head.

[0031] Figure 20 This is a flowchart illustrating the control process in the second implementation method.

[0032] Figure 21This is a diagram showing the waveform of the write signal in the third embodiment.

[0033] Figure 22 This is a diagram representing multiple write conditions in the third embodiment.

[0034] Figure 23 This is a flowchart illustrating the selection control of each writing condition in the third embodiment.

[0035] Explanation of reference numerals in the attached figures

[0036] 1…disk, 10…head, 11…write element, 12a…read element (first read element), 12b…read element (second read element), 20…actuator, 30…controller. Detailed Implementation

[0037] [1] The first embodiment will be described with reference to the accompanying drawings.

[0038] like Figure 1 As shown, the disk drive 100 includes a circular disk 1 as a recording medium, a spindle motor (SPM) 2 that drives the disk 1 to rotate, and a read / write head 10 for writing and reading data from the disk 1.

[0039] The magnetic head 10 is rotatably held in the actuator 20. The actuator 20 includes a rotating shaft 21, an arm 22 mounted on the rotating shaft 21, a voice coil motor 23 that applies a rotational force to the arm 22, and a suspension member 24 mounted on the front end of the arm 22. The magnetic head 10 is mounted at the front end of the suspension member 24. The voice coil motor 23 includes a coil 23c, a magnet, and a yoke, and rotates the arm 22 by flowing a drive current in the coil 23c.

[0040] like Figure 2 As shown, the read / write head 10 includes a write element 11 for writing magnetic data to the disk 1, and a pair of read elements (first read element) 12a and a second read element 12b for reading data from the disk 1. These read elements 12a and 12b are arranged along the rotation direction of the actuator 20 (radial direction of the disk 1). As the actuator 20 rotates, the read / write head 10 seeks (moves) along the radial direction of the disk 1 between a first position P1 (shown as dashed in the figure) and a second position P2 (shown as solid in the figure) on the outer periphery.

[0041] A stopper ST and a ramp mechanism RL are disposed near the actuator 20. The stopper ST restricts the movement of the read / write head 10 at the inner circumference of the disk 1. The ramp mechanism RL retracts the read / write head 10 from the disk 1 when the spindle motor 2 stops.

[0042] like Figure 3As shown, disk 1 includes a pair of recording surfaces 1a and 1b arranged face-to-face. Multiple disks 1 (e.g., 5 disks) are arranged coaxially on the rotation shaft 2a of spindle motor 2, spaced apart by a predetermined interval. Each disk 10 is equipped with one read / write head 10, which is positioned opposite to the recording surfaces 1a and 1b of each disk 1. These read / write heads 10 are assigned head numbers H0 to H9.

[0043] Head 10 with head number H0 faces the recording surface 1b of the first-level (lowest-level) disk 1; head 10 with head number H1 faces the recording surface 1a of the first-level disk 1; head 10 with head number H2 faces the recording surface 1b of the second-level disk 1; head 10 with head number H3 faces the recording surface 1a of the second-level disk 1; head 10 with head number H4 faces the recording surface 1b of the third-level disk 1; head 10 with head number H5 faces the recording surface 1a of the third-level disk 1; head 10 with head number H6 faces the recording surface 1b of the fourth-level disk 1; head 10 with head number H7 faces the recording surface 1a of the fourth-level disk 1. The head 10 with head number H8 faces the recording surface 1b of the fifth (top) disk 1, and the head 10 with head number H9 faces the recording surface 1a of the fifth disk 1.

[0044] As each disk 1 rotates, the air pressure generated by the rotation of each read / write head 10 rises in the direction away from each disk 1.

[0045] like Figure 1 As shown, the disk drive 100 includes a controller 30 that serves as the control center, a head amplifier 41 that drives each read / write head 10, a signal processing circuit 42 disposed between the head amplifier 41 and the controller 30, a motor driver 43 that drives the spindle motor 2 and the voice coil motor 23 according to the instructions of the controller 30, a DRAM 45 that stores programs and other data required for the control of the controller 30, a flash ROM 46 that stores various data required for the control of the controller 30, and a hard disk controller (HDC) 47 disposed between the controller 30 and an external host device 50.

[0046] The head amplifier 41 amplifies the write signals of data from the signal processing circuit 42 to each magnetic head 10 and amplifies the read signals of data from each magnetic head 10. The signal processing circuit 42 appropriately processes the write signals from the controller 30 to each magnetic head 10 and provides them to the head amplifier 41, and appropriately processes the read signals amplified by the head amplifier 41 and provides them to the controller 30.

[0047] The controller 30 controls the rotation of each disk 1 and the seek of each read / write head 10.

[0048] Regarding the seek control of controller 30, a seek speed for each magnetic head 10 is set according to the settings of controller 30. Figure 4 The seek speed tables shown are stored in the flash ROM 46. These seek speed tables store a predetermined speed for determining the radial seek speed of the read / write head 10 of the disk 1 based on the seek position of the read / write head 10. This predetermined speed consists of an acceleration region that accelerates from zero to a constant speed value when seeking from the innermost circumference to the outermost circumference of the read / write head 10, a constant speed region that maintains the constant speed value, and a deceleration region that decelerates from the constant speed value to zero.

[0049] In the manufacturing process of the disk device 1, the controller 30 performs a process of writing multiple servo patterns for each disk 1, which is a blank medium without any records, to serve as a reference for the positioning control of each read / write head 10, also known as SSW (Self Servo Write).

[0050] In this process, the controller 30 designates any one of the 10 heads 10 with header numbers H0 to H9, for example, head 10 with header number H6, as the first head; designates any one of the heads 10 with header number H2, for example, as the second head; and designates all the remaining heads 10 with header numbers H0, H1, H3, H4, H5, H7, H8, and H9 as third heads. Simultaneously, the controller 30 designates the disk 1 corresponding to the first head (H6) 10 as the first disk, the disk 1 corresponding to the second head (H2) 10 as the second disk, and each disk 1 corresponding to each of the third heads (H0, H1, H3, H4, H5, H7, H8, H9) 10 as the third disk.

[0051] Furthermore, the controller 30 performs write processing of spiral patterns and servo patterns through the first magnetic head (H6) 10, the second magnetic head (H2) 10, and each of the third magnetic heads (H0, H1, H3, H4, H5, H7, H8, H9) 10.

[0052] Reference Figure 5 Flowchart and Figure 6 The pattern format is explained in the description of this writing process.

[0053] First, while the controller 30 rotates each disk 1 at a certain speed, it causes the first read / write head (H6) 10 to seek radially from the inner periphery to the outer periphery of the first disk 1 at the speed specified in the aforementioned seek speed table. Furthermore, while repeatedly performing seeks by the first read / write head 10 in the circumferential direction of the first disk 1, it writes data between the first read / write head 10 and the first disk 1 at predetermined intervals. Figure 7 The multiple guide spiral patterns A(S1) are shown.

[0054] like Figure 8 As shown, each guide spiral pattern A is a magnetic pattern in which the magnetic intensity varies along the writing direction at a predetermined frequency and includes a synchronization mark M in each predetermined period.

[0055] Next, the controller 30 tracks the written guide spiral patterns A using the first magnetic head (H6) 10 and the second magnetic head (H2) 10 that follows the first magnetic head (H6) 10, while simultaneously writing to the second disk 1 at predetermined intervals via the second magnetic head (H2) 10. Figure 9 The first final spiral pattern B(S2) with multiple (e.g., 310) predetermined frequencies is shown.

[0056] like Figure 8 As shown, each of the first final spiral patterns B is also a magnetic pattern in which the magnetic intensity varies along the writing direction at a predetermined frequency and contains a synchronization mark M in each predetermined period.

[0057] Then, while the controller 30 tracks the first final spiral pattern B written above using the second magnetic head (H2) 10 and all the other magnetic heads 10 that follow the second magnetic head (H2) 10, the controller 30 adjusts the floating position of each magnetic head 10 relative to each disk 1 to an appropriate state (S3).

[0058] Furthermore, while the controller 30 tracks each of the first final spiral patterns B written above using the second magnetic head (H2) 10, it detects the offset between the write element 11 and the read element 12a of the second magnetic head (H2) 10, namely the so-called R / W offset (S4). Figure 10 As shown, the R / W offset varies depending on the seek position of the second head (H2) 10.

[0059] Next, while tracking each of the first final spiral patterns B written above using the second magnetic head (H2) 10, and taking into account the detected R / W offset, the controller 30 writes to the second disk 1 at predetermined intervals using the second magnetic head (H2) 10, which serves as the reference for the positioning control of the seek operation of the second magnetic head (H2) 10. Figure 11 The spiral-shaped multiple servo patterns shown are the so-called product servo patterns C(S5).

[0060] The servo pattern C of each product is not limited to a spiral shape; it can also be a shape that extends in a straight line in the radial direction of disk 1.

[0061] Then, the controller 30 tracks the written product servo patterns C using the second magnetic head (H2) 10 and each of the third magnetic heads (H0, H1, H3, H4, H5, H7, H8, H9) 10 following the second magnetic head (H2) 10, while using each of the third magnetic heads 10 to transmit the data with different frequencies F1, F2, F3 and a synchronization mark M in each predetermined period. Figure 12A plurality of circular adjustment patterns L1, L2, and L3 are respectively written one by one (S6) into the inner peripheral partition Z1, the middle peripheral partition Z2, and the outer peripheral partition Z3 that are sequentially set along the radial direction of each third disk 10.

[0062] As Figure 12 shown, the adjustment patterns L1, L2, and L3 are magnetic patterns in which the magnetic intensity changes along the writing direction at frequencies F1, F2, and F3 and includes synchronization marks M for each predetermined period. The frequencies F1, F2, and F3 of the adjustment patterns L1, L2, and L3 have a magnitude relationship of F1 < F2 < F3. In addition to the adjustment patterns L1, L2, and L3, adjustment patterns L4 to Ln with frequencies F4 to Fn used when partitions (zones) Z4 to Zn are set are also prepared in advance.

[0063] Next, the controller 30 reads the above-written adjustment patterns L1, L2, and L3 (S7) with each of the third magnetic heads (H0, H1, H3, H4, H5, H7, H8, H9) 10 as Figure 14 and <000017​​​​​​​​​​​After detecting the number N, the controller 30 selects the frequency of the adjustment pattern L1, L2, L3 that has detected a threshold Ns (e.g., 5) or more as the write frequency for each third magnetic head 10 (S9). For example, if the number N detected from the adjustment pattern L3 is the threshold Ns or more, then the frequency F3 of the adjustment pattern L3 is selected as the write frequency for the third magnetic head 10. If the number N detected from both the adjustment patterns L2 and L3 is the threshold Ns or more, then either the frequency F2 of the adjustment pattern L2 or the frequency F3 of the adjustment pattern L3 is selected as the write frequency for the third magnetic head 10.

[0067] Along with this selection, the controller 30 sets the seek speed of each third magnetic head 10 to a value corresponding to the selected write pattern frequency, and sets this value to gradually increase from the inner peripheral position (inner peripheral partition Z1) to the outer peripheral position (outer peripheral partition Z3) along the radial direction of each third disk 1 (S10). Furthermore, the controller 30 updates the seek speed table for each third magnetic head 10 stored in the flash ROM 46 with the set seek speed as the new specified speed (the updated specified speed shown by the dotted line in the figure). Figure 4 Regarding the new specified speed, it is slightly lower than the original specified speed when the seeker position is on the inner circumference side, and gradually increases as the seeker position moves from the inner circumference side to the outer circumference side.

[0068] After the seek speed is set, the controller 30 tracks the servo pattern C written to the second disk 1 using the second magnetic head (H2) 10 and each of the third magnetic heads 10 following the second magnetic head (H2) 10, while simultaneously writing to each of the third disks at predetermined intervals a servo pattern having the same frequency as the selected writing frequencies and including a synchronization marker M in each predetermined cycle. Figure 9 The multiple (e.g., 310) second final spiral pattern B (S11) shown.

[0069] During tracking here, the controller 30 causes the second magnetic head (H2) 10 to seek at the speed specified by the seek speed meter used by the second magnetic head (H2) 10, and causes each third magnetic head 10 to seek at the speed specified by the updated seek speed meter used by each third magnetic head 10.

[0070] like Figure 8 As shown, each of the second final spiral patterns B is also a magnetic pattern in which the magnetic intensity changes at a predetermined frequency along the writing direction and contains a synchronization mark M in each predetermined period.

[0071] Then, while each of the third magnetic heads 10 tracks the written second final spiral pattern B, the controller 30 writes to each of the third disks 1 at predetermined intervals the positioning control reference for the seek of each of the third magnetic heads. Figure 11 The spiral-shaped multiple servo patterns shown are called the product servo pattern C (S12). During tracking here, the controller 30 causes each third magnetic head 10 to seek at the updated specified speed of the seek speed table used by each third magnetic head 10.

[0072] The servo pattern C of each product is not limited to a spiral shape; it can also be a shape that extends in a straight line in the radial direction of disk 1.

[0073] The data write width (width in the direction orthogonal to the write direction) of each read / write head 10 mounted on the disk device 100 is not constant due to manufacturing variations. There are cases where a wide spiral pattern is written and cases where a narrow spiral pattern is written.

[0074] When writing a narrow spiral pattern, the read area of ​​the magnetic head 10 for that spiral pattern becomes relatively small. Consequently, the signal component of the synchronization marker M included in the read signal of the magnetic head 10 decreases. As a result, errors may occur in tracking the spiral pattern. This error is a major cause of the deterioration in the write accuracy of the product's servo pattern C.

[0075] exist Figure 16 The relationship between the number N of synchronization markers M detected from the read signals of each magnetic head 10 and the seek position (partition) of each magnetic head 10 is shown for reference. The number N of synchronization markers M detected varies according to the seek position, and there is a "deviation" in the number N of synchronization markers M detected for each magnetic head 10.

[0076] To address this issue, the controller 30 writes multiple adjustment patterns C1, C2, and C3 with different frequencies F1, F2, and F3 to each third disk 1 via each third magnetic head 10, and includes a synchronization marker M in each predetermined period. The controller 30 reads the written adjustment patterns C1, C2, and C3 with each third magnetic head 10, and detects the number N of the signal components of the synchronization marker M contained in the read signal of each third magnetic head 10.

[0077] Furthermore, the controller 30 selects the frequency of the adjustment pattern C1, C2, C3 that has obtained a detection number N above the threshold Ns as the writing frequency of each third magnetic head 10, and writes a plurality of second spiral patterns B with the same frequency as the selected writing frequency and containing a synchronization mark M in each predetermined cycle to each third disk 1 through each third magnetic head 10.

[0078] Then, while tracking the written second spiral pattern B with each third magnetic head 10, the controller 30 writes multiple product servo patterns C, which serve as the reference for the positioning control of the seek of each third magnetic head 10, to each third disk 10 via each third magnetic head 10.

[0079] Therefore, even if a narrow second spiral pattern B is written, resulting in a relatively smaller read area for the magnetic head 10, the reduced signal component of the synchronization marker M in the read signal of the magnetic head 10 can be avoided. That is, each synchronization marker M contained in the second spiral pattern B can be detected accurately and reliably. As a result, tracking of the second spiral pattern B will not produce errors, and the product servo pattern C can be written with high precision.

[0080] exist Figure 17 The diagram shows the relationship between the number N of synchronization markers M detected from the read signals of each magnetic head 10 and the seek position (partition) of each magnetic head 10. The number N of synchronization markers M detected is stable regardless of the seek position, and the "deviation" of the number N of synchronization markers M detected per magnetic head 10 is also suppressed.

[0081] Furthermore, if the spiral pattern is written at a certain seek speed, the density of magnetic changes in the written spiral pattern increases on the outer periphery of disk 1 compared to the inner periphery, and thus the amplitude of the written spiral pattern decreases.

[0082] To address this issue, the controller 30 sets the seek speed of each third magnetic head 10 writing each of the second spiral patterns B to a value corresponding to the selected writing pattern frequency, and sets this value to gradually increase from the inner circumferential position (inner circumferential partition Z1) to the outer circumferential position (outer circumferential partition Z3) along the radial direction of each third disk 1. Therefore, the undesirable condition of unnecessary reduction in the amplitude of the written spiral pattern can be eliminated. Furthermore, the product servo pattern C can be written with high precision.

[0083] Furthermore, regarding the written adjustment patterns C1, C2, and C3, since they are not needed after the signal component of the synchronization mark M is detected, it is preferable to erase them. For example, an AC erase (erase) at a frequency four times the frequency of the adjustment patterns C1, C2, and C3 can be performed. Alternatively, erasure is not required by setting the detection address pattern (SAM) of each synchronization mark M in the adjustment patterns C1, C2, and C3 to be different from the detection address pattern of the usual spiral pattern.

[0084] On the other hand, such as Figure 18As shown, the controller 30 includes a basic clock unit 31 that generates a basic clock signal (50MHz), a TBG (Time Base Generator) PLL circuit 32 that generates a data reading clock signal for each magnetic head 10 from the basic clock signal generated by the basic clock unit 31, and an SFG (Servo Frequency Generator) PLL circuit 33 that generates a data writing clock signal for each magnetic head 10 from the basic clock signal generated by the basic clock unit 31.

[0085] Regarding the frequency of the servo pattern C for each product, for example, by utilizing the CDS (Constant Density Servo) function as described in U.S. Patent 7,349,171, it is possible to achieve the following: Figure 19 As shown, the seek position of each head 10 along the radial direction of each disk 1 can be variably set. For example, by dividing the seek position of each head 10 into 10 zones from the inner periphery to the outer periphery of each disk 1, and variably setting the frequency of each product servo pattern C for each zone, the frequency of each product servo pattern C can be changed continuously and smoothly.

[0086] Similarly, by utilizing the aforementioned CDS (Constant Density Servo) function, it is also possible to obtain the frequency of each final spiral pattern B, such as... Figure 19 As shown, the position of each head 10 along the radial direction of each disk 1 can be set incrementally.

[0087] Next, the method for determining the seek speed of each third magnetic head 10 based on the writing pattern frequency selected for each third magnetic head 10 will be explained.

[0088] Figure 2 The diagram shows the skew angle θ of the read / write head 10 relative to the disk 1.

[0089] Based on the configuration relationship between head 10 and disk 1, define variables as follows.

[0090] Vact: Seek speed of head 10 (also known as actuator speed)

[0091] Rot: Disk 1's rotational speed (RPM)

[0092] Cyl_Rad: The seek position of head 10 (radial position of disk 1).

[0093] θ: The oblique angle at a specific seek position of the magnetic head 10

[0094] The pivot angle of head 10

[0095] In this case, the radial component of the seek speed of the head 10 can be expressed as Vact*cosθ, and the circumferential component of the seek speed of the head 10 can be expressed as Vact*sinθ. When calculating the linear angular velocity Wips (inches per second) of the disk 1, it is expressed by the following formula (Equation 1).

[0096] Wips=Rot*2π*Cyl_Rad / 60 (Formula 1)

[0097] Based on the above relationship, the "offset (Freq_diff)" of the data write frequency and data read frequency at a specific seek position of the magnetic head 10 can be expressed as the ratio of the circumferential component to the linear angular velocity component of the disk 1 (Equation 2) as follows.

[0098]

[0099] The calculation of the frequency "offset (Freq_diff)" includes the component of the oblique angle θ and the actuator's swing angle. Furthermore, by multiplication, the data write frequency can be calculated based on the data read frequency. In other words, if the write frequency of the magnetic head 10 is determined, the speed of the magnetic head 10 at a specific seek position (radial direction position) can be calculated. That is, the seek speed of the magnetic head 10 when writing the final helical pattern B can be calculated.

[0100] [2] The second embodiment will be described.

[0101] In the process of writing the servo pattern C, which serves as the reference for the positioning control of each magnetic head 10, the controller 30, such as... Figure 20 As shown in the flowchart, firstly, the read element 12a in each read element 12a and read element 12b of each magnetic head 10 is selected for data reading (S0).

[0102] Then, after performing the processing of S1 to S8 in the same manner as in the first embodiment, the controller 30 sums up the number N of the signal components of the synchronization mark M detected from the read signal of the adjustment pattern L1, the number N of the signal components of the synchronization mark M detected from the read signal of the adjustment pattern L2, and the number N of the signal components of the synchronization mark M detected from the read signal of the adjustment pattern L3, and divides the sum by the number of adjustment patterns L1, L2, and L3, thereby calculating the average value Na of each detection number N for each third magnetic head 10 (S21).

[0103] Regarding the third magnetic head that obtains an average value Na above the threshold N (S22 "Yes"), the controller 30, similarly to the first embodiment, selects the frequency of the adjustment pattern that obtains the number of detections N above the threshold Ns as the writing frequency (S9).

[0104] Regarding the third magnetic head that has not obtained an average value Na above the threshold N (S22 "No"), the controller 30 determines which of the reading elements 12a and 12b of the third magnetic head 10 has been selected for data reading (S23).

[0105] If the read element 12a is selected (S23 "No"), the controller 30 selects the read element 12b of the corresponding third magnetic head (the magnetic head that has not obtained an average value Na above the threshold N) 10 for data reading (S24). After this selection, the controller 30 repeats the process of S7 described above.

[0106] After repeating the process of S7, the controller 30 sums up the number N of the signal components of the synchronization mark M detected from the read signal of the adjustment pattern L1, the number N of the signal components of the synchronization mark M detected from the read signal of the adjustment pattern L2, and the number N of the signal components of the synchronization mark M detected from the read signal of the adjustment pattern L3, and divides the sum by the number of adjustment patterns L1, L2, and L3. Thus, the average value Na of the number N detected is calculated for each third magnetic head 10 (S21).

[0107] Regarding the third magnetic head that obtains an average value Na above the threshold N (S22 "Yes"), the controller 30, similarly to the first embodiment, selects the frequency of the adjustment pattern that obtains the number of detections N above the threshold Ns as the writing frequency (S9).

[0108] Regarding the third magnetic head that has not obtained an average value Na above the threshold N (S22 "No"), the controller 30 further determines which of the read elements 12a and 12b of the third magnetic head 10 has been selected for data reading (S23). In this case, since read element 12b has been selected (S23 "Yes"), the controller 30 selects the frequency of the adjustment pattern that has obtained the maximum number of detections N as the writing frequency of the third magnetic head 10 (S25).

[0109] For example, if the number of N detected from adjustment patterns L2 is the largest among the number of N detected from adjustment patterns L1, L2, and L3, then the frequency F2 of adjustment pattern L2 is selected as the writing frequency of the third magnetic head 10. If the number of N detected from adjustment pattern L3 is the largest, then the frequency F3 of adjustment pattern L3 is selected as the writing frequency of the third magnetic head 10.

[0110] Therefore, even if the synchronization mark M cannot be detected due to malfunction of the reading element 12a, the synchronization mark M can be detected accurately and reliably by using the reading element 12b.

[0111] The other components and effects are the same as in the first embodiment.

[0112] [3] The third embodiment will be described.

[0113] In the process of writing the servo pattern C, which serves as the reference for the positioning control of each magnetic head 10, the waveforms of the write signals provided to the read element 12a or read element 12b for writing the adjustment patterns L1, L2, L3... are as follows: Figure 21 As shown, within a certain period T, the following events occur: holding the "-Iw" level, overshooting from the "-Iw" level to the "+Iw+OSA" level, holding the "OSD" level for a certain period of time at the "+Iw+OSA" level, dropping from the "+Iw+OSA" level to the "+Iw" level, holding the "+Iw" level, overshooting from the "+Iw" level to the "-Iw-OSA" level, holding the "OSD" level for a certain period of time at the "-Iw-OSA" level, rising from the "-Iw-OSA" level to the "-Iw" level, and holding the "-Iw" level.

[0114] The controller 30 will assign the parameters "Iw", "OSA", and "OSD" of the above write signal as follows: Figure 22 Multiple distinct write conditions W1, W2, ... Wn are stored in the internal memory. The write state changes of patterns L1, L2, L3, ... Ln are adjusted according to which of the write conditions W1, W2, ... Wn is used.

[0115] Reference Figure 23 The flowchart illustrates the control performed by controller 30 regarding the writing of adjustment patterns L1, L2, L3, ... Ln.

[0116] During the write processing of the first adjustment pattern L, the controller 30 selects the write condition W1 corresponding to the condition specification number n = 1 (S31), and uses the write condition W1 to write the first adjustment pattern L to the disk 1 (S32). Next, the controller 30 shifts the write position of the read / write head 10 (S33) and increments the condition specification number n by 1 (S34). Then, the controller 30 determines whether the condition specification number n (= 2) after incrementing by 1 has reached the predetermined maximum value ns (S35).

[0117] If the condition specified number n has not reached the threshold ns ("No" in S35), the controller 30 returns to the process in S31, selects the write condition W2 corresponding to the condition specified number n = 2 (S31), and uses the write condition W2 to write the second adjustment pattern L to the disk 1 (S32). Next, the controller 30 shifts the write position of the read / write head 10 (S33) and increments the condition specified number n by 1 (S34). Then, the controller 30 determines whether the condition specified number n (= 3) after incrementing by 1 has reached the maximum value ns (S35).

[0118] If the condition specified number n has not reached the threshold ns ("No" in S35), the controller 30 returns to the process in S31, selects the write condition W3 corresponding to the condition specified number n = 3 (S31), and uses the write condition W3 to write the third adjustment pattern L to the disk 1 (S32). Next, the controller 30 shifts the write position of the read / write head 10 (S33) and increments the condition specified number n by 1 (S34). Then, the controller 30 determines whether the condition specified number n (= 4) after incrementing by 1 has reached the maximum value ns (S35).

[0119] Subsequently, controller 30 repeats the same process.

[0120] By pre-determining detailed write conditions W1, W2, ... Wn related to the waveform of the write signal for the adjustment patterns L1, L2, L3..., and writing the adjustment patterns L1, L2, L3... while specifying the write conditions W1, W2, ... Wn in sequence, it is possible to write the good adjustment patterns L1, L2, L3... with varying magnetic intensity to each disk 1.

[0121] The other components and effects are the same as in the first embodiment.

[0122] This invention is not limited to the embodiments described above. During implementation, the constituent elements can be modified to be more specific without departing from its essence. Furthermore, various inventions can be formed through appropriate combinations of the multiple constituent elements disclosed in the above embodiments. For example, several constituent elements may be deleted from all the constituent elements shown in each embodiment. Moreover, constituent elements involved in different embodiments may be appropriately combined.

Claims

1. A disk drive, comprising: Multiple disks capable of spinning; Multiple read / write heads are capable of radially seeking along each disk and performing write and read operations on each disk; and The controller controls the rotation of each disk and the seek operation of each read / write head. The controller The write frequencies of each read / write head to each disk are different, and multiple adjustment patterns containing synchronization markers are used in each predetermined cycle. The written adjustment patterns are read using each of the magnetic heads, and the number of synchronization marker signal components contained in the read signal of each magnetic head is detected. The frequency of the adjustment pattern that obtains a detection number above a certain threshold among the read adjustment patterns is selected as the writing frequency of each magnetic head. The write frequency of each read / write head to each disk is the same as the selected write frequency, and multiple spiral patterns containing synchronization markers are used in each predetermined cycle. While each read / write head tracks the written spiral pattern, a servo pattern that serves as the reference for the positioning control of the seeker of each read / write head is written to each disk.

2. The disk drive according to claim 1, The controller The seek speed of each magnetic head is set to a value corresponding to the frequency of each selected writing pattern.

3. The disk drive according to claim 1, The controller The seek speed of each read / write head is set to a value corresponding to the selected write pattern frequency, and this value is set to gradually increase from the inner circumferential position to the outer circumferential position along the radial direction of each disk.

4. The disk drive according to claim 1, The controller includes a basic clock unit that generates a basic clock signal, a circuit that generates a data reading clock signal for each magnetic head from the basic clock signal generated by the basic clock unit, and a circuit that generates a data writing clock signal for each magnetic head from the basic clock signal generated by the basic clock unit.

5. The disk drive according to claim 1, Each magnetic head includes a write element for writing data and a first read element and a second read element for reading data. The controller First, the first reading element of the first reading element and the first reading element of the second reading element of each magnetic head are selected for data reading. For the magnetic head that has not obtained the number of detections exceeding the threshold, the second read element of that magnetic head is selected for data reading. For a magnetic head that does not obtain a number of detections above the threshold even after the selection of the second read element, the frequency of the adjustment pattern that obtains the maximum number of detections is selected as the writing frequency.

6. A disk drive, comprising: A first disk, a second disk, and multiple third disks capable of rotation; The first read / write head is capable of seeking along the radial direction of the first disk and writing and reading data from the first disk. The second read / write head is capable of seeking along the radial direction of the second disk and writing and reading data from the second disk. Multiple third heads are capable of radially seeking along each of the third disks and writing and reading data from each of the third disks; and The controller controls the rotation of the first disk, the second disk, and each of the third disks, and controls the seek operation of the first read / write head, the second read / write head, and each of the third read / write heads. The controller A boot spiral pattern is written to the first disk using the first read / write head. While the first magnetic head and a second magnetic head following the first magnetic head are tracking the written guide spiral pattern, the second magnetic head writes a first final spiral pattern, which includes synchronization markers at a predetermined frequency, to the second disk. While the second read / write head tracks the first final spiral pattern being written, a servo pattern that serves as the reference for the positioning control of the second read / write head's seek operation is written to the second disk. While tracking the write servo pattern using the second magnetic head and each of the third magnetic heads following the second magnetic head, the third magnetic heads write multiple adjustment patterns to each of the third disks at different frequencies and containing synchronization markers in each predetermined cycle. The third magnetic head is used to read the written adjustment pattern, and the number of synchronization marker signal components contained in the read signal of each third magnetic head is detected. The frequency of the adjustment pattern in each of the read adjustment patterns that has a detection number above a certain threshold is selected as the writing frequency of each third magnetic head. While tracking the write servo pattern with the second magnetic head and each of the third magnetic heads following the second magnetic head, the third magnetic heads write multiple second final spiral patterns to each third disk at the same frequency as the selected write frequencies and containing synchronization markers in each predetermined cycle. While each of the third magnetic heads tracks the written second final spiral pattern, a servo pattern that serves as the reference for the positioning control of the seek of each of the third magnetic heads is written to each of the third disks via each of the third magnetic heads.

7. The disk drive according to claim 6, The controller The seek speed of each of the third magnetic heads is set to a value corresponding to the frequency of each selected writing pattern.

8. The disk drive according to claim 6, The controller The seek speed of each of the third heads is set to a value corresponding to the selected write pattern frequency, and the value is set to gradually increase from the inner peripheral position to the outer peripheral position along the radial direction of each of the third disks.

9. The disk drive according to claim 6, The controller includes a basic clock unit that generates a basic clock signal, a circuit that generates a data reading clock signal for each magnetic head from the basic clock signal generated by the basic clock unit, and a circuit that generates a data writing clock signal for each magnetic head from the basic clock signal generated by the basic clock unit.

10. The disk drive according to claim 6, Each magnetic head includes a write element for writing data and a first read element and a second read element for reading data. The controller First, the first reading element of the first reading element and the first reading element of the second reading element of each magnetic head are selected for data reading. For the third magnetic head that has not obtained the number of detections exceeding the threshold, the second read element of the third magnetic head is selected for data reading. For the third magnetic head that does not obtain a number of detections above the threshold after the selection of the second read element, the frequency of the adjustment pattern that obtains the maximum number of detections is selected as the writing frequency.

11. A method for controlling a disk drive, The disk device includes: Multiple disks capable of spinning; Multiple read / write heads are capable of radially seeking along each disk and performing write and read operations on each disk; and The controller controls the rotation of each disk and the seek operation of each read / write head. In the control method of the disk device, The write frequencies of each read / write head to each disk are different, and multiple adjustment patterns containing synchronization markers are used in each predetermined cycle. The written adjustment patterns are read using each of the magnetic heads, and the number of synchronization marker signal components contained in the read signal of each magnetic head is detected. The frequency of the adjustment pattern that obtains a detection number above a certain threshold among the read adjustment patterns is selected as the writing frequency of each magnetic head. The write frequency of each read / write head to each disk is the same as the selected write frequency, and multiple spiral patterns containing synchronization markers are used in each predetermined cycle. While each read / write head tracks the written spiral pattern, a servo pattern that serves as the reference for the positioning control of the seeker of each read / write head is written to each disk.

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