Magnetic disk drive and its control method

Abstract

The present invention provides a magnetic disk device and a control method therefor that can accurately detect sync marks on a spiral pattern. [Solution] Multiple adjustment patterns with different frequencies are written to each magnetic disk by each magnetic head. Each written adjustment pattern is read by each magnetic head, and the number of sync marks contained in the read signal is detected. The frequency of the adjustment pattern that yields a number of detected marks above a threshold is selected as the write frequency for each magnetic head. A spiral pattern with the same frequency as the selected write frequency is written to each magnetic disk by each magnetic head. While tracking the written spiral pattern, a servo pattern that serves as the reference for the seek positioning control of each magnetic head is written to each magnetic disk by each magnetic head.

Description

Technical Field

[0001] Embodiments of the present invention relate to a magnetic disk drive including a plurality of magnetic disks and a plurality of magnetic heads, and a control method therefor.

Background Art

[0002] A controller of a magnetic disk drive including a plurality of magnetic disks and a plurality of magnetic heads for writing / reading data to / from each of the magnetic disks performs a process called SSW (Self Servo Write) of writing a plurality of servo patterns serving as a reference for positioning control of each magnetic head to each magnetic disk which is a blank medium having nothing recorded thereon in the manufacturing process of the magnetic disk drive.

[0003] In this process, the controller writes a guide spiral pattern to one magnetic disk by one magnetic head, and while tracking the written guide spiral pattern with each magnetic head, writes a final spiral pattern to each magnetic disk by each magnetic head.

[0004] Then, while tracking each written final spiral pattern with each magnetic head, the controller writes a servo pattern (referred to as a product servo pattern) serving as a reference for positioning control of each magnetic head to each magnetic disk by each magnetic head.

[0005] The guide spiral pattern and the final spiral pattern are magnetic patterns in which the magnetic intensity changes at a predetermined frequency and includes sync marks at predetermined intervals.

[0006] When tracking the guide spiral pattern and the final spiral pattern with the magnetic head, the controller detects a signal component corresponding to the sync mark from the read signal of the magnetic head, and controls the movement of the magnetic head according to the detection result.

Prior Art Documents

[0007] [Patent Document 1] U.S. Patent No. 7,349,171 [Overview of the project] [Problems that the invention aims to solve]

[0008] The data write width (the width dimension perpendicular to the write direction) of the multiple magnetic heads mounted on a magnetic disk drive is not constant due to manufacturing variations. Sometimes a wide spiral pattern is written, and sometimes a narrow spiral pattern is written.

[0009] When a narrow spiral pattern is lit, the magnetic head's read area for that spiral pattern becomes smaller. In this case, the sync mark signal component included in the magnetic head's read signal is reduced, which can result in tracking errors for the spiral pattern. These errors can degrade the accuracy of the servo pattern lighting.

[0010] The objective of this embodiment is to provide a magnetic disk device and a control method therefor that can accurately detect sync marks on a spiral pattern. [Means for solving the problem]

[0011] The magnetic disk device of the embodiment includes: a plurality of rotatable magnetic disks; a plurality of magnetic heads capable of radially seeking each magnetic disk and performing data writing and reading to each magnetic disk; and a controller that controls the rotation of each magnetic disk and the seeking of each magnetic head. The controller writes a plurality of adjustment patterns containing sync marks at predetermined intervals at different frequencies to each magnetic disk using each magnetic head; reads each of the written adjustment patterns with each magnetic head and detects the number of sync mark signal components included in the read signal of each magnetic head; selects the frequency of the adjustment pattern from the read adjustment patterns that yields a number of detected sync marks equal to or greater than a threshold as the writing frequency of each magnetic head; writes a plurality of spiral patterns containing sync marks at predetermined intervals at the same frequency as the selected writing frequency to each magnetic disk using each magnetic head; and while tracking each of the written spiral patterns with each magnetic head, writes a servo pattern that serves as a reference for positioning control of the seeking of each magnetic head to each magnetic disk using each magnetic head. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 shows the configurations of the first to third embodiments. [Figure 2] Figure 2 shows the configuration of the main parts of the magnetic head in each embodiment. [Figure 3] Figure 3 shows the relationship between each magnetic disk and each magnetic head in each embodiment. [Figure 4] Figure 4 shows the seek speed table for each magnetic head in each embodiment. [Figure 5] Figure 5 is a flowchart showing the control of the first embodiment. [Figure 6] Figure 6 shows the format of the patterns that each magnetic head lights in each embodiment. [Figure 7] Figure 7 shows the guide spiral patterns in each embodiment. [Figure 8] FIG. 8 is a diagram showing the magnetic change and sync marks of each spiral pattern in each embodiment. [Figure 9] FIG. 9 is a diagram showing each final spiral pattern in each embodiment. [Figure 10] FIG. 10 is a diagram showing how the offset amount between the read element and the write element of the magnetic head changes according to the seek position of the magnetic head in each embodiment. [Figure 11] FIG. 11 is a diagram showing each servo pattern in each embodiment. [Figure 12] FIG. 12 is a diagram showing each adjustment pattern in each embodiment. [Figure 13] FIG. 13 is a diagram showing the difference in frequency of each adjustment pattern in each embodiment. [Figure 14] FIG. 14 is a diagram showing the correspondence state between the read element of the magnetic head and the adjustment pattern L2 in each embodiment together with the read signal of the magnetic head. [Figure 15] FIG. 15 is a diagram showing the correspondence state between the read element of the magnetic head and the adjustment pattern L3 in each embodiment together with the read signal of the magnetic head. [Figure 16] FIG. 16 is a diagram showing the relationship between the number of sync marks detected from the read signals of each magnetic head and the seek position (zone) of each magnetic head in the prior art. [Figure 17] FIG. 17 is a diagram showing the relationship between the number of sync marks detected from the read signals of each magnetic head and the seek position (zone) of each magnetic head in each embodiment. [Figure 18] FIG. 18 is a diagram showing the generating means of the clock signal for data reading and the clock signal for data writing in each embodiment. [Figure 19] FIG. 19 is a diagram showing the relationship between the frequencies of the final spiral pattern B and the product servo pattern C and the seek position of the magnetic head in each embodiment. [Figure 20] FIG. 20 is a flowchart showing the control of the second embodiment. [Figure 21]FIG. 21 is a diagram showing the waveform of the write signal in the third embodiment. [Figure 22] FIG. 22 is a diagram showing a plurality of write conditions in the third embodiment. [Figure 23] FIG. 23 is a flowchart showing the selection control of each write condition in the third embodiment.

MODE FOR CARRYING OUT THE INVENTION

[0013] [1] The first embodiment will be described with reference to the drawings. As shown in FIG. 1, the magnetic disk device 100 includes a circular magnetic disk 1 as a recording medium, a spindle motor (SPM) 2 that rotationally drives the magnetic disk 1, and a magnetic head 10 that writes and reads data to and from the magnetic disk 1.

[0014] The magnetic head 10 is rotatably held by an actuator 20. The actuator 20 includes a rotation shaft 21, an arm 22 attached to the rotation shaft 21, a voice coil motor 23 that applies a rotational force to the arm 22, and a suspension member 24 attached to the tip of the arm 22. The magnetic head 10 is attached to the tip of the suspension member 24. The voice coil motor 23 includes a coil 23c, a magnet, and a yoke, and rotates the arm 22 when a drive current flows through the coil 23c.

[0015] As shown in FIG. 2, the magnetic head 10 includes a write element 11 that writes magnetic data to the magnetic disk 1, and a pair of read elements (first read element) 12a and a read element (second read element) 12b that read data from the magnetic disk 1. These read elements 12a and 12b are arranged side by side along the rotation direction of the actuator 20 (the radial direction of the magnetic disk 1). As the actuator 20 rotates, the magnetic head 10 seeks (moves) along the radial direction of the magnetic disk 1 between the first position P1 shown by the dashed line and the second position P2 shown by the solid line on the outer peripheral side in the drawing.

[0016] A stopper ST and a ramp mechanism RL are positioned near the actuator 20. The stopper ST restricts the movement position of the magnetic head 10 to the inner circumference side of the magnetic disk 1. The ramp mechanism RL retracts the magnetic head 10 from the magnetic disk 1 when the spindle motor 2 is stopped.

[0017] As shown in Figure 3, the magnetic disk 1 contains a pair of recording surfaces 1a and 1b in a front-to-back relationship. Multiple magnetic disks 1 (for example, 5 disks) are arranged coaxially on the rotation axis 2a of the spindle motor 2 at predetermined intervals from each other. One magnetic head 10 is positioned facing the recording surfaces 1a and 1b of each magnetic disk 1. These magnetic heads 10 are assigned head numbers H0 to H9.

[0018] The magnetic head 10 with head number H0 faces the recording surface 1b of the first (bottom) magnetic disk 1, and the magnetic head 10 with head number H1 faces the recording surface 1a of the first magnetic disk 1. The magnetic head 10 with head number H2 faces the recording surface 1b of the second magnetic disk 1, and the magnetic head 10 with head number H3 faces the recording surface 1a of the second magnetic disk 1. The magnetic head 10 with head number H4 faces the recording surface 1b of the third magnetic disk 1, and the magnetic head 10 with head number H5 faces the recording surface 1a of the third magnetic disk 1. The magnetic head 10 with head number H6 faces the recording surface 1b of the fourth magnetic disk 1, and the magnetic head 10 with head number H7 faces the recording surface 1a of the fourth magnetic disk 1. The magnetic head 10 with head number H8 faces the recording surface 1b of the fifth (topmost) magnetic disk 1, and the magnetic head 10 with head number H9 faces the recording surface 1a of the fifth magnetic disk 1.

[0019] As each magnetic disk 1 rotates, the air pressure generated by its rotation causes each magnetic head 10 to float away from each magnetic disk 1.

[0020] As shown in Figure 1, the magnetic disk device 100 includes a controller 30 which serves as the control center, a head amplifier 41 which drives each magnetic head 10, a signal processing circuit 42 provided between the head amplifier 41 and the controller 30, a motor driver 43 which drives the spindle motor 2 and the voice coil motor 23 according to the commands of the controller 30, a DRAM 45 which is a memory that stores programs and the like necessary for controlling the controller 30, a flash ROM 46 which is a memory that stores various data necessary for controlling the controller 30, and a hard disk controller (HDC) 47 provided between the controller 30, the hard disk controller (HDC), and the external host device 50.

[0021] The head amplifier 41 amplifies the data write signals from the signal processing circuit 42 to each magnetic head 10, and also amplifies the data read signals from each magnetic head 10. The signal processing circuit 42 processes the write signals from the controller 30 to each magnetic head 10 as appropriate and supplies them to the head amplifier 41, and processes the read signals amplified by the head amplifier 41 as appropriate and supplies them to the controller 30.

[0022] The controller 30 controls the rotation of each magnetic disk 1 and the seeking of each magnetic head 10.

[0023] Regarding the seek control of the controller 30, a seek speed table, as shown in Figure 4, is set for each magnetic head 10 to define the seek speed of each magnetic head 10, and each of these seek speed tables is stored in the flash ROM 46. These movement speed tables store a specified speed to define the seek speed of the magnetic head 10 in the radial direction of the magnetic disk 1 according to the seek position of the magnetic head 10. This specified speed consists of an acceleration region where the magnetic head 10 accelerates from zero towards a constant velocity value, a constant velocity region where the constant velocity value is maintained, and a deceleration region where the magnetic head 10 decelerates from the constant velocity value towards zero when seeking from the innermost to the outermost circumference.

[0024] In the manufacturing process of the magnetic disk device 1, the controller 30 performs a process known as SSW (Self Servo Write), which involves writing multiple servo patterns, which serve as a reference for positioning control of each magnetic head 10, to each magnetic disk 1, which is a blank medium on which nothing has been recorded.

[0025] In this process, the controller 30 designates one of the ten magnetic heads 10 with head numbers H0 to H9, for example, magnetic head 10 with head number H6, as the first magnetic head, one of the ten magnetic heads 10 with head numbers H2, for example, as the second magnetic head, and all the remaining magnetic heads 10 with head numbers H0, H1, H3, H4, H5, H7, H8, and H9 as third magnetic heads. Accordingly, the controller 30 designates the magnetic disk 1 corresponding to the first magnetic head (H6) 10 as the first magnetic disk, the magnetic disk 1 corresponding to the second magnetic head (H2) 10 as the second magnetic disk, and each magnetic disk 1 corresponding to each of the third magnetic heads (H0, H1, H3, H4, H5, H7, H8, H9) 10 as a third magnetic disk.

[0026] The controller 30 then performs light processing of spiral patterns and servo patterns using 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.

[0027] This lighting process will be explained with reference to the flowchart in Figure 5 and the pattern format in Figure 6.

[0028] First, the controller 30 rotates each magnetic disk 1 at a constant speed and seeks the first magnetic head (H6) 10 radially from the inner circumference to the outer circumference of the first magnetic disk 1 at the speed specified in the seek speed table, and while performing this seeking of the first magnetic head 10 multiple times in the circumferential direction of the first magnetic disk 1, the controller 30 writes multiple guide spiral patterns A shown in Figure 7 to the first magnetic disk 1 at predetermined intervals from each other using the first magnetic head 10 (S1).

[0029] Each guide spiral pattern A, as shown in Figure 8, is a magnetic pattern in which the magnetic intensity changes along the light direction at a predetermined frequency and contains a sync mark M at predetermined intervals.

[0030] Next, the controller 30 tracks each of the written guide spiral patterns A with the first magnetic head (H6) 10 and the second magnetic head (H2) 10 that follows the first magnetic head (H6) 10, and writes multiple (for example, 310) first final spiral patterns B of predetermined frequencies, as shown in Figure 9, to the second magnetic disk 1 at predetermined intervals from each other using the second magnetic head (H2) 10 (S2).

[0031] Each first final spiral pattern B is also a magnetic pattern in which the magnetic intensity changes along the light direction at a predetermined frequency, as shown in Figure 8, and which contains a sync mark M at predetermined intervals.

[0032] Then, the controller 30 tracks each of the first final spiral patterns B written above with the second magnetic head (H2) 10 and all the remaining magnetic heads 10 that follow the second magnetic head (H2) 10, and adjusts the floating position of each magnetic head 10 relative to each magnetic disk 1 to an appropriate state (S3).

[0033] Furthermore, the controller 30 tracks each of the first final spiral patterns B that have been lit using the second magnetic head (H2) 10, and detects the offset amount between the light element 11 and the read element 12a of the second magnetic head (H2) 10, also known as the R / W offset amount (S4). The R / W offset amount changes according to the seek position of the second magnetic head (H2) 10, as shown in Figure 10.

[0034] Subsequently, while the controller 30 tracks each of the written first final spiral patterns B with the second magnetic head (H2) 10 and taking into account the detected R / W offset amount, the controller 30 writes a plurality of spiral-shaped servo patterns so-called product servo patterns C as shown in FIG. 11, which serve as a reference for seek positioning control of the second magnetic head (H2) 10, on the second magnetic disk 1 by the second magnetic head (H2) 10 at predetermined intervals from each other (S5).

[0035] Each product servo pattern C is not limited to a spiral shape and may have a shape that extends linearly in the radial direction of the magnetic disk 1.

[0036] Then, while the controller 30 tracks each of the written product servo patterns C with the second magnetic head (H2) 10 and each of the third magnetic heads (H0, H1, H3, H4, H5, H7, H8, H9) 10 that follow the second magnetic head (H2) 10, the controller 30 sequentially sets circular adjustment patterns L1, L2, L3 shown in FIG. 12, each including a sync mark M at predetermined periods with different frequencies F1, F2, F3, by each of the third magnetic heads 10 along the radial direction of each of the third magnetic disks 10 and writes them one by one in the inner peripheral zone Z1, the middle peripheral zone Z2, and the outer peripheral zone Z3 (S6).

[0037] As shown in FIG. 12, the adjustment patterns L1, L2, L3 are magnetic patterns in which the magnetic intensity changes at frequencies F1, F2, F3 along the writing direction and includes a sync mark M at predetermined periods. The frequencies F1, F2, F3 of the adjustment patterns L1, L2, L3 have a magnitude relationship of F1 < F2 < F3. In addition to the adjustment patterns L1, L2, L3, adjustment patterns L4 to Ln with frequencies F4 to Fn used when zones Z4 to Zn are set are also prepared in advance.

[0038] Next, the controller 30 reads the above-written adjustment patterns L1, L2, L3 with each of the third magnetic heads (H0, H1, H3, H4, H5, H7, H8, H9) 10 as shown in Figures 14 and 15 (S7). Then, the controller 30 detects the number N of sync mark M signal components included in the read signal of each of the third magnetic heads 10 (S8).

[0039] Figure 14 shows the correspondence between the adjustment pattern L2 written by the light element 11 of the third magnetic head 10 and the read element 12a of the third magnetic head 10, along with the read signal of the third magnetic head 10. If the data write width (width dimension in the direction perpendicular to the write direction) of the adjustment pattern L2 written by the light element 11 is narrow, the read area of ​​the third magnetic head 10 relative to the adjustment pattern L2 becomes relatively smaller. Consequently, the number N of sync mark M signal components included in the read signal of the third magnetic head 10 decreases.

[0040] Figure 15 shows the correspondence between the adjustment pattern L3, which is lit by the light element 11 of the third magnetic head 10, and the read element 12a of the third magnetic head 10, along with the read signal of the third magnetic head 10. If the data write width (width dimension in the direction perpendicular to the write direction) of the adjustment pattern L3 lit by the light element 11 is narrow, the read area of ​​the third magnetic head 10 relative to the adjustment pattern L3 becomes relatively smaller. However, since the frequency F3 of the adjustment pattern L3 is higher than the frequency F2 of the adjustment pattern L2, the number N of sync mark M signal components included in the read signal of the third magnetic head 10 does not decrease.

[0041] After detecting the number N, the controller 30 individually selects the frequency of the adjustment pattern from the read adjustment patterns L1, L2, and L3 that yields a detection number N of at least a threshold Ns (e.g., 5), as the light frequency for each third magnetic head 10 (S9). For example, if the detection number N from adjustment pattern L3 is at least the threshold Ns, the frequency F3 of adjustment pattern L3 is selected as the light frequency for the third magnetic head 10. If the detection numbers N from both adjustment patterns L2 and L3 are at least the threshold Ns, either the frequency F2 of adjustment pattern L2 or the frequency F3 of adjustment pattern L3 is selected as the light frequency for the third magnetic head 10.

[0042] Following 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 such a value gradually increases from the inner circumference position (inner zone Z1) to the outer circumference position (outer zone Z3) along the radial direction of each third magnetic disk 1 (S10). The controller 30 then updates and stores the set seek speed as a new specified speed (updated specified speed shown by the dashed line in the figure) in the seek speed table (Figure 4) for each third magnetic head 10 in the flash ROM 46. The new specified speed is slightly lower than the original specified speed when the seek position is on the inner circumference side, and gradually increases as the seek position moves from the inner circumference side to the outer circumference side.

[0043] After setting the seek speed, the controller 30 tracks the servo pattern C written to the second magnetic disk 1 with the second magnetic head (H2) 10 and each third magnetic head 10 that follows the second magnetic head (H2) 10, and writes multiple (e.g., 310) second final spiral patterns B shown in Figure 9, which include sync marks M at predetermined intervals at the same frequency as the selected write frequencies, to each third magnetic disk at predetermined intervals using each third magnetic head (S11).

[0044] During tracking, the controller 30 causes the second magnetic head (H2) 10 to seek at the specified speed in the seek speed table for the second magnetic head (H2) 10, and each third magnetic head 10 to seek at the updated specified speed in the seek speed table for each third magnetic head 10.

[0045] Each second final spiral pattern B, as shown in Figure 8, is a magnetic pattern in which the magnetic intensity changes along the light direction at a predetermined frequency and includes a sync mark M at predetermined intervals.

[0046] Then, while tracking each of the written second final spiral patterns B with each third magnetic head 10, the controller 30 writes a plurality of spiral-shaped servo patterns, so-called product servo patterns C, as shown in Figure 11, which serve as a reference for the seek positioning control of each third magnetic head, to each third magnetic disk 1 at predetermined intervals from each other (S12). During tracking here, the controller 30 causes each third magnetic head 10 to seek at the updated specified speed in the seek speed table for each third magnetic head 10.

[0047] Each product servo pattern C is not limited to a spiral shape; it may also have a shape that extends linearly in the radial direction of the magnetic disk 1.

[0048] Incidentally, the data write width (width dimension in the direction perpendicular to the write direction) of each magnetic head 10 mounted on the magnetic disk drive 100 is not constant due to manufacturing variations. Sometimes a wide spiral pattern is written, and sometimes a narrow spiral pattern is written.

[0049] When a narrow spiral pattern is lit, the read area of ​​the magnetic head 10 relative to that spiral pattern becomes relatively smaller. Consequently, the signal component of the sync mark M included in the read signal of the magnetic head 10 decreases. As a result, tracking errors may occur for the spiral pattern. These errors can degrade the accuracy of lighting the product servo pattern C.

[0050] Figure 16 shows, for reference, the relationship between the number of sync marks M detected from the read signals of each magnetic head 10 and the seek position (zone) of each magnetic head 10. The number of detected sync marks M N varies depending on the seek position, and there is "variation" in the number of detected sync marks M N from one magnetic head 10 to the other.

[0051] To address these challenges, the controller 30 writes multiple adjustment patterns C1, C2, and C3, each containing a sync mark M at predetermined intervals with different frequencies F1, F2, and F3, to each third magnetic disk 1 using each third magnetic head 10. The controller then reads the written adjustment patterns C1, C2, and C3 with each third magnetic head 10 and detects the number N of signal components of the sync mark M included in the read signal of each third magnetic head 10.

[0052] Furthermore, the controller 30 selects the frequency of the adjustment pattern from the read adjustment patterns C1, C2, and C3 that yields a number of detections N greater than or equal to the threshold Ns as the write frequency for each third magnetic head 10, and writes multiple second spiral patterns B containing sync marks M at predetermined intervals at the same frequency as the selected write frequency to each third magnetic disk 1 using each third magnetic head 10.

[0053] Then, the controller 30 tracks each written second spiral pattern B with each third magnetic head 10, and writes a plurality of product servo patterns C, which serve as the reference for the seek positioning control of each third magnetic head 10, to each third magnetic disk 10 using each third magnetic head 10.

[0054] Therefore, even if a narrow second spiral pattern B is lit and the read area of ​​the magnetic head 10 relative to the second spiral pattern B is relatively small, it is possible to avoid the problem of a decrease in the signal component of the sync mark M included in the read signal of the magnetic head 10. In other words, each sync mark M included in the second spiral pattern B can be accurately detected. As a result, errors in tracking the second spiral pattern B are eliminated, and the product servo pattern C can be written with high accuracy.

[0055] Figure 17 shows the relationship between the number of sync marks M detected from the read signals of each magnetic head 10 and the seek position (zone) of each magnetic head 10. Regardless of the seek position, the number of detected sync marks M N remains stable, and the "variation" in the number of detected sync marks M N from one magnetic head 10 to the other is also suppressed.

[0056] Furthermore, when the spiral pattern is written at a constant seek speed, the density of magnetic changes in the written spiral pattern increases on the outer circumference of the magnetic disk 1 more than on the inner circumference, which reduces the amplitude of the written spiral pattern.

[0057] To address this issue, the controller 30 sets the seek speed of each third magnetic head 10 that writes each second spiral pattern B to a value corresponding to the selected writing pattern frequency, and sets this value to gradually increase from the inner circumference position (inner zone Z1) to the outer circumference position (outer zone Z3) along the radial direction of each third magnetic disk 1. This eliminates the problem of the amplitude of the written spiral pattern being unnecessarily reduced. Consequently, the product servo pattern C can be written with high accuracy.

[0058] Furthermore, the written adjustment patterns C1, C2, and C3 are no longer needed after detecting the signal component of sync mark M, so it is desirable to erase them. For example, AC erasure can be performed at a frequency four times the frequency of adjustment patterns C1, C2, and C3. Alternatively, by setting the detection address pattern (SAM) for each sync mark M in adjustment patterns C1, C2, and C3 to be different from the detection address pattern of the normal spiral pattern, erasing becomes unnecessary.

[0059] On the other hand, as shown in Figure 18, the controller 30 includes a basic clock unit 31 that generates a basic clock signal (50 MHz), a TBG (Time Base Generator) PLL circuit 32 that generates a clock signal for data reading 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 clock signal for data writing for each magnetic head 10 from the basic clock signal generated by the basic clock unit 31.

[0060] The frequency of each product servo pattern C can be variably set according to the seek position of each magnetic head 10 along the radial direction of each magnetic disk 1, as shown in Figure 19, by utilizing the CDS (Constant Density Servo) function described in, for example, U.S. Patent No. 7,349,171. For example, by dividing the seek position of each magnetic head 10 into 10 zones from the inner circumference to the outer circumference of each magnetic 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.

[0061] Similarly, by utilizing the CDS (Constant Density Servo) function described above, it is possible to gradually vary the frequency of each final spiral pattern B according to the seek position of each magnetic head 10 along the radial direction of each magnetic disk 1, as shown in Figure 19.

[0062] Next, we will explain how to determine the seek speed of each third magnetic head 10 from the light pattern frequency selected for each third magnetic head 10. Figure 2 shows the skew angle θ of the magnetic head 10 relative to the magnetic disk 1.

[0063] Based on the relative positions of the magnetic head 10 and the magnetic disk 1, the following variables are defined. Vact: Seek speed of magnetic head 10 (also called actuator speed) Rot: Rotation speed (RPM) of magnetic disk 1 Cyl_Rad: Seek position of magnetic head 10 (radial position of magnetic disk 1) θ: Skew angle at a specific seek position of the magnetic head 10 φ: Pivot angle of magnetic head 10

[0064] In this case, the radial component of the seek velocity of the magnetic head 10 can be expressed as Vact*cosθ, and the circumferential component of the seek velocity of the magnetic head 10 can be expressed as Vact*sinθ. The linear angular velocity of magnetic disk 1 in Wips (inches per second) can be calculated using the following formula. Wips = Rot * 2π * Cyl_Rad / 60

[0065] From the above relationship, the "diff (Freq_diff)" between 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 magnetic disk 1, as shown below. Freq_diff = 60*(Vact*sinθ / Rot*(2π*Cyl_Rad))*cosφ

[0066] The formula for calculating this frequency "diff" (Freq_diff) includes the skew angle θ and the actuator pivot angle φ, and since it is obtained by multiplication, the data write frequency can be calculated from the data read frequency. In other words, if the write frequency of the magnetic head 10 is determined, the velocity of the magnetic head 10 at a specific seek position (radial position) can be determined. That is, it becomes possible to calculate the seek velocity of the magnetic head 10 when writing the final spiral pattern B.

[0067] [2] A second embodiment will be described. In the process of writing the servo pattern C which serves as the reference for positioning control of each magnetic head 10 (SSW), the controller 30 first selects the lead element 12a of the lead elements 12a and 12b of each magnetic head 10 to be used for data reading (S0), as shown in the flowchart of Figure 20.

[0068] Then, the controller 30 performs the same processing S1 to S8 as in the first embodiment, and then sums up the number of signal components N of the sync mark M detected from the read signal for adjustment pattern L1, the number of signal components N of the sync mark M detected from the read signal for adjustment pattern L2, and the number of signal components N of the sync mark M detected from the read signal for adjustment pattern L3, and divides the sum by the number of adjustment patterns L1, L2, and L3 to calculate the average value Na of each detected number N for each third magnetic head 10 (S21).

[0069] For the third magnetic head from which an average value Na greater than or equal to the threshold N is obtained (YES in S22), the controller 30 selects the frequency of the adjustment pattern from which a number of detected objects N greater than or equal to the threshold Ns is obtained as the frequency for the light, as in the first embodiment (S9).

[0070] For third magnetic heads that cannot obtain an average value Na greater than or equal to the threshold N (NO in S22), the controller 30 determines which of the read elements 12a or 12b of the third magnetic head 10 has been selected for data reading (S23).

[0071] If the lead element 12a has already been selected (NO in S23), the controller 30 selects the lead element 12b of the corresponding third magnetic head (a magnetic head from which an average value Na greater than or equal to the threshold N cannot be obtained) 10 for data reading (S24). After this selection, the controller 30 repeats the process in S7.

[0072] After repeating the process in S7, the controller 30 sums the number of signal components N of sync marks M detected from the read signal for adjustment pattern L1, the number of signal components N of sync marks M detected from the read signal for adjustment pattern L2, and the number of signal components N of sync marks M detected from the read signal for adjustment pattern L3, and divides this sum by the number of adjustment patterns L1, L2, and L3 to recalculate the average value Na of each detected number N for each third magnetic head 10 (S21).

[0073] For the third magnetic head from which an average value Na greater than or equal to the threshold N is obtained (YES in S22), the controller 30 selects the frequency of the adjustment pattern from which a number of detected objects N greater than or equal to the threshold Ns is obtained as the frequency for the light, as in the first embodiment (S9).

[0074] For the third magnetic head for which an average value Na greater than or equal to the threshold N cannot be obtained (NO in S22), the controller 30 re-determines which of the lead elements 12a or 12b of the third magnetic head 10 has already been selected for data reading (S23). In this case, since lead element 12b has been selected (NO in S23), the controller 30 selects the frequency of the adjustment pattern for which the maximum number of detected elements N was obtained as the writing frequency for the third magnetic head 10 (S25).

[0075] For example, if the number of detections N from adjustment patterns L2 is the largest among the number of detections N from adjustment patterns L1, L2, and L3, then the frequency F2 of adjustment pattern L2 is selected as the light frequency for the third magnetic head 10. If the number of detections N from adjustment pattern L3 is the largest, then the frequency F3 of adjustment pattern L3 is selected as the light frequency for the third magnetic head 10.

[0076] Therefore, even if the sync mark M cannot be detected due to a malfunction of the lead element 12a, the sync mark M can be accurately detected by using the lead element 12b. Other configurations and effects are the same as in the first embodiment.

[0077] [3] A third embodiment will be described. In the process (SSW) of lighting the servo pattern C which serves as the reference for positioning control of each magnetic head 10, the waveform of the light signal supplied to the lead element 12a or lead element 12b for lighting each adjustment pattern L1, L2, L3... changes over a constant period T as shown in Figure 21, maintaining the "-Iw" level, overshooting from the "-Iw" level to the "+Iw+OSA" level, maintaining the "+Iw+OSA" level with "OSD" for a certain period of time, descending from the "+Iw+OSA" level to the "+Iw" level, maintaining the "+Iw" level, overshooting from the "+Iw" level to the "-Iw+OSA" level, maintaining the "-Iw" level with "OSD" for a certain period of time, ascending from the "-Iw+OSA" level to the "-Iw" level, and maintaining the "-Iw" level.

[0078] The controller 30 stores in its internal memory multiple light conditions W1, W2, ... Wn, where the parameters "Iw", "OSA", and "OSD" of the above-mentioned light signals are all different, as shown in Figure 22. Depending on which of the light conditions W1, W2, ... WnX1, X2, ... Xn is used, the light state of the adjustment patterns L1, L2, L3, ... Ln changes.

[0079] The control performed by the controller 30 with respect to the lights of adjustment patterns L1, L2, L3, ... Ln will be explained with reference to the flowchart in Figure 23. When writing the first adjustment pattern L, the controller 30 selects a write condition W1 corresponding to condition specification number n=1 (S31), and writes the first adjustment pattern L to the magnetic disk 1 using that write condition W1 (S32). Subsequently, the controller 30 offsets the write position of the magnetic 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 the increment has reached a predetermined maximum value ns (S35).

[0080] If the condition specification 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 condition specification number n=2 (S31), and writes the second adjustment pattern L to the magnetic disk 1 using that write condition W2 (S32). Subsequently, the controller 30 offsets the write position of the magnetic head 10 (S33) and increments the condition specification number n by 1 (S34). Then, the controller 30 determines whether the condition specification number n after the increment (=3) has reached the maximum value ns (S35).

[0081] If the condition specification 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 condition specification number n=3 (S31), and writes the third adjustment pattern L to the magnetic disk 1 using that write condition W3 (S32). Subsequently, the controller 30 offsets the write position of the magnetic head 10 (S33) and increments the condition specification number n by 1 (S34). Then, the controller 30 determines whether the condition specification number n after the increment (=4) has reached the maximum value ns (S35). Thereafter, the controller 30 repeats the same process.

[0082] By defining detailed write conditions W1, W2, ... Wn regarding the waveform of the write signals for adjustment patterns L1, L2, L3, ..., and writing the adjustment patterns L1, L2, L3, ... while sequentially specifying these write conditions W1, W2, ... Wn, it is possible to write good adjustment patterns L1, L2, L3, ..., which exhibit distinct changes in magnetic intensity, to each magnetic disk 1. Other configurations and effects are the same as in the first embodiment.

[0083] The present invention is not limited to the embodiments described above, and can be implemented by modifying the components without departing from the spirit of the invention. Furthermore, various inventions can be formed by appropriately combining the multiple components disclosed in the above embodiments. For example, some components may be deleted from all the components shown in each embodiment. Moreover, components from different embodiments may be appropriately combined. [Explanation of Symbols]

[0084] 1...Magnetic disk, 10...Magnetic head, 11...Write element, 12a...Read element (first read element), 12b...Read element (second read element), 20...Actuator, 30...Controller.

Claims

1. Multiple rotatable magnetic disks, Multiple magnetic heads capable of seeking radially across each of the aforementioned magnetic disks and performing data writing and reading to each of the aforementioned magnetic disks, A controller that controls the rotation of each of the magnetic disks and the seeking of each of the magnetic heads, Equipped with, The aforementioned controller, Multiple adjustment patterns, each containing a sync mark at a predetermined period at different frequencies, are written to each magnetic disk by each magnetic head. Each of the written adjustment patterns is read by each of the magnetic heads, and the number of sync mark signal components included in the read signal of each magnetic head is detected. The frequency of the adjustment pattern from which the number of detected items equal to or greater than the threshold is obtained is selected as the light frequency for each magnetic head. Multiple spiral patterns containing sync marks are written to each magnetic disk by each magnetic head at the same frequency as the selected writing frequency, with each spiral head having a predetermined period. While tracking each of the written spiral patterns with each of the magnetic heads, a servo pattern that serves as a reference for the seek positioning control of each of the magnetic heads is written to each of the magnetic disks by each of the magnetic heads. Magnetic disk drive.

2. The aforementioned controller, The seek speed of each of the aforementioned magnetic heads is set to a value corresponding to the selected pattern frequency for each light. The magnetic disk device according to claim 1.

3. The aforementioned controller, The seek speed of each magnetic head is set to a value corresponding to the selected write pattern frequency, and such a value gradually increases from the inner circumference to the outer circumference along the radial direction of each magnetic disk. The magnetic disk device according to claim 1.

4. The aforementioned controller, A basic clock unit that generates a basic clock signal, a circuit that generates a data read clock signal for each of the magnetic heads from the basic clock signal generated by the basic clock unit, and a circuit that generates a data write clock signal for each of the magnetic heads from the basic clock signal generated by the basic clock unit. including, The magnetic disk device according to claim 1.

5. Each of the aforementioned magnetic heads includes a light element for data writing, and also includes a first read element and a second read element for data reading. The aforementioned controller, Of the first and second lead elements of each of the aforementioned magnetic heads, the first lead element is first selected for data reading. For magnetic heads that do not obtain a number of detections equal to or greater than the threshold, the second lead element of the magnetic head is selected for data reading. For magnetic heads that do not obtain a number of detections equal to or greater than the threshold even after selecting the second lead element, the frequency of the adjustment pattern that yields the maximum number of detections is selected as the frequency for lighting. The magnetic disk device according to claim 1.

6. A rotatable first magnetic disk, a second magnetic disk, and a plurality of third magnetic disks, A first magnetic head capable of seeking radially across the first magnetic disk and performing data writing and reading to the first magnetic disk, A second magnetic head capable of seeking radially across the second magnetic disk and performing data writing and reading to the second magnetic disk, A plurality of third magnetic heads capable of seeking radially across each of the third magnetic disks and performing data writing and reading to each of the third magnetic disks, A controller that controls the rotation of the first magnetic disk, the second magnetic disk, and each of the third magnetic disks, and controls the seeking of the first magnetic head, the second magnetic head, and each of the third magnetic heads, Equipped with, The aforementioned controller, The guide spiral pattern is written to each of the first magnetic disks by the first magnetic head. While tracking the written guide spiral pattern with the first magnetic head and the second magnetic head that follows the first magnetic head, a first final spiral pattern with a predetermined frequency containing sync marks is written to the first magnetic disk by the second magnetic head at predetermined intervals. While tracking the first final spiral pattern written above with the second magnetic head, the second magnetic head writes a servo pattern that serves as a reference for the seek positioning control of the second magnetic head to the second magnetic disk. While tracking the written servo pattern with the second magnetic head and each of the third magnetic heads that follow the second magnetic head, each of the third magnetic heads writes a plurality of adjustment patterns containing sync marks at predetermined intervals at different frequencies to each of the third magnetic disks. Each of the written adjustment patterns is read by each of the third magnetic heads, and the number of sync mark signal components included in the read signal of each of the third magnetic heads is detected. The frequency of the adjustment pattern from which the number of detected items equal to or greater than the threshold is obtained is selected as the light frequency for each of the third magnetic heads. While tracking the written servo pattern with the second magnetic head and each of the third magnetic heads that follow the second magnetic head, each of the third magnetic heads writes a plurality of second final spiral patterns containing sync marks at predetermined intervals at the same frequency as the selected writing frequency to each of the third magnetic disks. While tracking each of the written second final spiral patterns with each of the third magnetic heads, a servo pattern that serves as a reference for the seek positioning control of each of the third magnetic heads is written to each of the third magnetic disks by each of the third magnetic heads. Magnetic disk drive.

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

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

9. The aforementioned controller, A basic clock unit that generates a basic clock signal, a circuit that generates a data read clock signal for each of the magnetic heads from the basic clock signal generated by the basic clock unit, and a circuit that generates a data write clock signal for each of the magnetic heads from the basic clock signal generated by the basic clock unit. including, The magnetic disk device according to claim 6.

10. Each of the aforementioned magnetic heads includes a light element for data writing, and also includes a first read element and a second read element for data reading. The aforementioned controller, Of the first and second lead elements of each of the aforementioned magnetic heads, the first lead element is first selected for data reading. For the third magnetic head in which the number of detected objects above the threshold cannot be obtained, the second lead element of the third magnetic head is selected for data reading. For the third magnetic head in which the number of detected elements does not exceed the threshold after the selection of the second lead element, the frequency of the adjustment pattern that yields the maximum number of detected elements is selected as the frequency for lighting. The magnetic disk device according to claim 6.

11. Multiple rotatable magnetic disks, Multiple magnetic heads capable of seeking radially across each of the aforementioned magnetic disks and performing data writing and reading to each of the aforementioned magnetic disks, A controller that controls the rotation of each of the magnetic disks and the seeking of each of the magnetic heads, A control method for a magnetic disk device comprising: Multiple adjustment patterns, each containing a sync mark at a predetermined period at different frequencies, are written to each magnetic disk by each magnetic head. Each of the written adjustment patterns is read by each of the magnetic heads, and the number of sync mark signal components included in the read signal of each magnetic head is detected. The frequency of the adjustment pattern from which the number of detected items equal to or greater than the threshold is obtained is selected as the light frequency for each magnetic head. Multiple spiral patterns containing sync marks are written to each magnetic disk by each magnetic head at the same frequency as the selected writing frequency, with each spiral head having a predetermined period. While tracking each of the written spiral patterns with each of the magnetic heads, a servo pattern that serves as a reference for the seek positioning control of each of the magnetic heads is written to each of the magnetic disks by each of the magnetic heads. A method for controlling a magnetic disk drive.

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