Disk device

Abstract

To provide a disk device capable of speeding up write processing.SOLUTION: According to one embodiment, a disk device having a head, a disk, and a controller is provided. The disk includes at least one band. When writing a target track in at least one band while partially overlapping a track adjacent to the target track, the controller writes a plurality of tracks to the band so that the track pitch at the beginning of the band is larger than other track pitch in at least a portion of the circumferential position range.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present embodiment relates to a disk device. [Background technology]

[0002] In a disk drive, a target track may be written to partially overlap a track adjacent to the target track in each band of a disk including multiple bands. In a disk drive, it is desirable to speed up the write process for writing the target track. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 8,867,161 [Patent Document 2] U.S. Patent No. 8,724,248 [Patent Document 3] U.S. Patent No. 9,281,008 [Patent Document 4] U.S. Patent No. 9,972,353 [Patent Document 5] US Patent Application Publication No. 2013 / 0057978 Summary of the Invention [Problem to be solved by the invention]

[0004] An object of one embodiment is to provide a disk device that can speed up write processing. [Means for solving the problem]

[0005] According to one embodiment, there is provided a disk drive including a head, a disk, and a controller. The disk includes at least one band. The controller writes a plurality of tracks in the band such that, when a target track in each of the at least one band is written so as to partially overlap tracks adjacent to the target track, the track pitch at the leading end of the band is larger than the track pitch of other tracks in at least a portion of a circumferential position range. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a diagram showing the configuration of a disk device according to a first embodiment. [Figure 2] FIG. 2 is a diagram showing the configuration of a data track in the first embodiment. [Figure 3] FIG. 2 is a diagram showing the configuration of an actuator arm and a head according to the first embodiment. [Figure 4] FIG. 4 is a diagram showing a waiting time in the first embodiment. [Figure 5] 5 is a flowchart showing the operation of the disk device according to the first embodiment. [Figure 6] 5 is a flowchart showing the operation of the disk device according to the first embodiment. [Figure 7] FIG. 10 is a diagram showing the configuration of a data track according to the second embodiment. [Figure 8] 10 is a flowchart showing the operation of a disk device according to a second embodiment. [Figure 9] 10 is a flowchart showing the operation of a disk device according to a second embodiment. [Figure 10] FIG. 10 is a diagram showing a read flag determination process according to the second embodiment. [Figure 11] FIG. 10 is a diagram showing the configuration of a data track according to the third embodiment. [Figure 12] FIG. 11 is a diagram showing a waiting time in the third embodiment. [Figure 13] 10 is a flowchart showing the operation of a disk device according to a third embodiment. [Figure 14]10 is a flowchart showing the operation of a disk device according to a third embodiment. [Figure 15] FIG. 10 is a diagram showing the configuration of a data track according to a fourth embodiment. [Figure 16] 10 is a flowchart showing the operation of a disk device according to a fourth embodiment. [Figure 17] 10 is a flowchart showing the operation of a disk device according to a fourth embodiment. [Figure 18] FIG. 13 is a diagram showing a read flag determination process according to the fourth embodiment. [Figure 19] FIG. 13 is a diagram showing the configuration of a data track according to the fifth embodiment. [Figure 20] 10 is a flowchart showing the operation of a disk device according to a fifth embodiment. [Figure 21] 10 is a flowchart showing the operation of a disk device according to a fifth embodiment. [Figure 22] FIG. 13 is a diagram showing the configuration of a data track according to the sixth embodiment. [Figure 23] 13 is a flowchart showing the operation of a disk device according to a sixth embodiment. [Figure 24] 13 is a flowchart showing the operation of a disk device according to a sixth embodiment. [Figure 25] FIG. 20 is a diagram showing a read flag determination process according to the sixth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Disc devices according to embodiments will be described in detail below with reference to the accompanying drawings, although the present invention is not limited to these embodiments.

[0008] (First embodiment) The disk device of the first embodiment writes a target track while partially overlapping it with tracks adjacent to the target track in each band of a disk that includes multiple bands, and is devised to speed up the write process for writing the target track.

[0009] A disk device 1 according to the first embodiment will be described with reference to Fig. 1. Fig. 1 is a diagram showing the configuration of the disk device 1.

[0010] The disk device 1 is a device that records information on a disk 11 using a head 22, and may be, for example, a magnetic disk device or an optical disk device. Specifically, the disk device 1 includes the disk 11, a spindle motor 12, a motor driver 21, a head 22, an actuator arm 15, a voice coil motor (VCM) 16, a lamp 23, a head amplifier 24, a read / write channel (RWC) 25, a hard disk controller (HDC) 31, a buffer memory 29, and a control unit 26.

[0011] The disk 11 is rotated at a predetermined rotation speed around a rotation axis by a spindle motor 12. The rotation of the spindle motor 12 is driven by a motor driver 21.

[0012] Head 22 uses write element 22a and read element 22b provided therein to write and read data to and from disk 11. Head 22 is located at the tip of actuator arm 15 and is moved in the radial direction (track width direction) of disk 11 by voice coil motor 16 driven by motor driver 21. When disk 11 is stopped from rotating, head 22 is retracted onto ramp 23.

[0013] The head amplifier 24 amplifies the signal read from the disk 11 by the head 22, outputs the signal, and supplies it to the RWC 25. The head amplifier 24 also amplifies the signal for writing data to the disk 11, which is supplied from the RWC 25, and supplies it to the head 22.

[0014] The HDC 31 controls the transmission and reception of data to and from the host computer 40 via the I / F bus, controls the buffer memory 29, and performs error correction processing on write data. The buffer memory 29 is also used as a cache for data transmitted and received to and from the host computer 40. The buffer memory 29 is also used to temporarily store data read from the disk 11, data to be written to the disk 11, or control firmware read from the disk 11.

[0015] The RWC 25 code-modulates data to be written to the disk 11, which is supplied from the HDC 31, and supplies the code-modulated data to the head amplifier 24. The RWC 25 also code-demodulates a signal read from the disk 11 and supplied from the head amplifier 24, and outputs the demodulated data to the HDC 31 as digital data.

[0016] The control unit 26 is connected to an operating memory 27 (e.g., SRAM: Static Random Access Memory), a nonvolatile memory 28 (e.g., Flash ROM: Flash Read Only Memory), and a temporary storage buffer memory 29 (e.g., DRAM: Dynamic Random Access Memory). The control unit 26 performs overall control of the disk device 1 in accordance with firmware pre-stored in the nonvolatile memory 28 and the disk 11. The firmware includes initial firmware and control firmware used for normal operation. The initial firmware, which is executed first at startup, is stored in the nonvolatile memory 28. The control firmware includes an information recording program, which will be described later. The control firmware used for normal operation is recorded on the disk 11, and is temporarily read from the disk 11 to the buffer memory 29 under control in accordance with the initial firmware, and then stored in the operating memory 27.

[0017] The hardware configuration including the RWC 25, HDC 31, and control unit 26 can also be considered as the controller 32. The controller 32 can be configured as a one-chip integrated circuit (system-on-chip). The package of the controller 32 can be disposed on a printed circuit board outside a case (not shown) that houses the disk 11, spindle motor 12, motor driver 21, head 22, actuator arm 15, voice coil motor (VCM) 16, etc.

[0018] In the disk device 1, a plurality of concentric tracks are defined on the disk 11 by servo information written in advance on the disk 11.

[0019] In this specification, the tracks defined by the servo information are called servo tracks, and the tracks written by the write element 22a are called data tracks, to distinguish them from each other.

[0020] In the disk device 1, data tracks are formed on the disk 11 by writing data to a plurality of servo tracks by the write element 22a, for example, in order from the inside to the outside or from the outside to the inside.

[0021] In this case, the disk device 1 employs shingled magnetic recording (SMR) as a method for further increasing the recording capacity of the disk 11. In the SMR method, the servo track width (≈servo track pitch STP) of the disk 11 is narrower than the main pole width of the write element 22a. Therefore, when the disk device 1 writes using the write element 22a, the write is performed by partially overwriting the data track to be written and the adjacent data track.

[0022] In the SMR system, the disk device 1 can group multiple servo tracks into bands BN, each group consisting of one or more adjacent servo tracks. FIG. 1 illustrates a configuration in which three bands BN1 to BN3 are provided on the disk 11, but the number of bands BN may be one or two, or four or more. As shown in FIG. 2, guard tracks GT1 and GT2 are provided between multiple bands BN1 to BN3. FIG. 2 is a diagram showing the configuration of data tracks. Data is not written to the guard tracks GT1 and GT2. FIG. 2 illustrates a configuration in which each band BN includes n servo tracks TR, where n is any integer equal to or greater than 2.

[0023] The disk device 1 selects the band BN to be written from among the multiple bands BN1 to BN3. FIG. 2 illustrates the case where band BN2 is selected. The disk device 1 sets the first servo track TR_1 of the selected band BN2 as the target track for the head 22, and causes the actuator arm 15 to seek and write data using the write element 22a. At this time, the actuator arm 15 may vibrate in the radial direction.

[0024] To prevent radial vibrations, the actuator arm 15 has a microactuator 15a between the arm body 15b and the head 22, as shown in Figure 3(a). During a seek, the microactuator 15a is vibration-controlled to suppress radial vibrations, as shown by the dotted arrow in Figure 3(b). However, if the amount of radial vibration is large, radial vibrations may still remain in the actuator arm 15 even after vibration control by the microactuator 15a.

[0025] This vibration can cause the leading portion of data track DT_1 to undulate radially and extend circumferentially, resulting in a relatively large amount of off-track. If the write element 22a then writes an adjacent data track to the adjacent servo track TR_2, the data on data track DT_1 may be overwritten by the adjacent data track and lost.

[0026] In this specification, the leading side refers to the side that is written earlier in the shingled magnetic recording (SMR) method.

[0027] In the disk device 1, to avoid erasing data on adjacent data tracks DT during writing, writing is permitted within a certain range of fluctuation in the radial direction. Hereinafter, the amount of fluctuation permitted during writing is referred to as the off-track slice WOSx, where x is an arbitrary integer. The off-track slice WOSx is determined primarily by the servo track pitch STP, and in addition to data erasure on adjacent data tracks DT, the fact that data is not erased from adjacent data tracks DT after writing with fluctuation is also a determining factor for the off-track slice value. In the disk device 1, during a seek process from a long distance, the process usually switches to a settling process for on-track when the disk device reaches the vicinity of the target servo track TR.

[0028] The settling process drives the arm body 15b and microactuator 15a to move the head 22 onto the target track as quickly as possible. The vibrations at the target track during this settling process are called residual vibrations. Starting from the start of the settling process, tracing the center position of the write element 22a results in the result shown in Figure 4, which shows that residual vibrations occur relative to the center position of the servo track TR.

[0029] The residual vibration is greater than the steady state vibration, and write operations are not permitted until it is determined that the steady state has been reached. In the example of FIG. 4, during the waiting time Tx, the residual vibration exceeds the off-track slice WOSx, and writing is not permitted. After the waiting time Tx has elapsed, the residual vibration settles within the off-track slice WOSx, the settling process is completed, and writing is permitted. The waiting time Tx is the time from when the settling process begins to when the settling process is completed. For example, if the write start target sector is located at a circumferential position corresponding to the waiting time Tx, writing begins one rotation after the steady state has been reached, which tends to lengthen the write process time. The settling process waiting time Tx affects the write process speed.

[0030] Therefore, in this embodiment, the disk device 1 writes multiple data tracks to the band BN in the SMR method so that the data track pitch at the beginning of the band BN is larger than the other data track pitches in at least a portion of the circumferential position range, thereby reducing the wait time Tx for the settling process and thereby speeding up the write process.

[0031] The track pitch between the guard track GT and the first data track DT_1 of the adjacent band BN is at least one servo track pitch STP. The data track pitch TP between the first data track DT_1 and the second data track DT_2 of the band BN is set to be significantly wider than the data track pitch TP between other data tracks in the same band BN.

[0032] For example, as shown in Fig. 2, the disk device 1 writes data tracks DT_1 to DT_n-1 using servo tracks TR_1, TR_3 to TR_n other than the second leading servo track TR_2 among the plurality of servo tracks TR_1 to TR_n in band BN. This allows the data track pitch TP_1 between data track DT_1 and data track DT_2 to be larger than the other data track pitches TP_2 to TP_n-2. The data track pitch TP_1 is larger than the servo track pitch STP. The data track pitches TP_2 to TP_n-2 are each approximately equal to the servo track pitch STP.

[0033] Here, if the off-track slice of the first data track DT_1 is designated as WOS1 and the off-track slices of the second and subsequent data tracks DT_2 to DT_n are designated as WOS0, it is possible to make WOS1 > WOS0. That is, the standard off-track slice is designated as WOS0, and a larger off-track slice for adjustment is designated as WOS1. The standard off-track slice WOS0 is used for most of the data tracks DT_2 to DT_n-1 in band BN, but the adjustment off-track slice WOS1 is selectively used for the first data track DT_1.

[0034] This reduces the waiting time T1, and even when there is residual vibration of the actuator arm 15, the disk device 1 can write the data track DT_1 as shown in Fig. 2. This allows the disk device 1 to reduce the predetermined waiting time and shorten the write processing time, compared to when the disk device 1 waits a predetermined waiting time until the residual vibration of the actuator arm 15 subsides before it can write the data track DT_1. WOS1 is determined so as to satisfy the following (Condition 1) to (Condition 3).

[0035] (Condition 1) When the second data track DT_2 in band BN is written, the first data track DT_1 is not erased and is readable.

[0036] (Condition 2) When the first data track DT_1 in the band BN is written, the last data track DT_n-1 in the adjacent band BN is not erased and is readable.

[0037] (Condition 3) When the last data track DT_n-1 of the adjacent band BN is written, the first data track DT_1 of the band BN is not erased and is readable.

[0038] The off-track slice WOS1 may be determined depending on the strength of the residual vibration within a range that satisfies (Conditions 1) to (Conditions 3). For example, the increase in the data track pitch TP between the first data track DT_1 and the second data track DT_2 is a maximum of one track. However, depending on the strength of the residual vibration, the write processing time may be improved even if the difference in the off-track slice (WOS1-WOS0) is one track or less. In this case, the data track pitch TP between the first data track DT_1 and the second data track DT_2 may be set larger than that between other tracks by half the servo track pitch (WOS1-WOS0). The first embodiment can be realized by setting the data track pitch TP between the first data track DT_1 and the second data track DT_2 larger than the difference in the off-track slice (WOS1-WOS0) between the first data track DT_1 and the second data track DT_2 compared to the other data track pitches TP.

[0039] Note that since the data track DT is written without using the second-to-first servo track TR_2, the data format efficiency may be reduced accordingly. To ensure the same data capacity as when servo track TR_2 is used for writing, the data recording pitch BPI of all tracks in band BN may be increased.

[0040] Next, the operation of the disk device 1 will be described with reference to Figures 5 and 6. Figures 5 and 6 are flowcharts showing the operation of the disk device 1. The operations shown in Figures 5 and 6 can be mainly controlled by the controller 32.

[0041] The disk drive 1 determines the target band BN and sets the first data track DT_1 in the target band BN as the track to be adjusted for WOS1 and latency T1 (S1). The disk drive 1 performs a long-distance seek to the track to be adjusted using the head 22, and measures the relationship between the time from the start of settling control and the amount of residual vibration (S2). The disk drive 1 uses the servo track pitch STP and the standard off-track slice WOS0 to calculate the off-track slice WOS1 for adjustment using the following equation 1 (S3). WOS1 = STP / 2 + WOS0 Equation 1

[0042] The disk device 1 determines a waiting time T1 from the start of settling control so that writing is possible on the off-track slice WOS1 (S4). The disk device 1 sets initial values ​​for each read flag. The disk device 1 sets read flag 1=0, read flag 2=0, and read flag 3=0 (S5). The disk device 1 writes one revolution of the final data track DT_n-1 of the adjacent band BN on the off-track slice WOS0 (S6). The disk device 1 writes one revolution of the adjustment target track (data track DT_1) under the conditions of waiting time T1 and off-track slice WOS1, while residual vibration is occurring immediately after a long-distance seek (S7).

[0043] The disk device 1 determines whether the last data track DT_n-1 of the adjacent band BN is readable (S8). If the last data track DT_n-1 of the adjacent band BN is unreadable (No in S8), the disk device 1 sets the read flag 1 to "1" (S9).

[0044] If the last data track DT_n-1 of the adjacent band BN is readable (Yes in S8), the disk device 1 skips S9.

[0045] The disk device 1 writes one revolution of the second data track DT_2 of the band BN in the off-track slice WOS0 (S10).

[0046] The disk device 1 determines whether the track to be adjusted (data track DT_1) is readable (S11). If the track to be adjusted is not readable (No in S11), the disk device 1 sets the read flag 2 to "1" (S12).

[0047] If the track to be adjusted is readable (Yes in S11), the disk device 1 skips S12.

[0048] The disk device 1 writes one revolution of the last data track DT_n-1 of the adjacent band BN in the off-track slice WOS0 (S13).

[0049] The disk device 1 determines whether the track to be adjusted (data track DT_1) is readable (S14). If the track to be adjusted is not readable (No in S14), the disk device 1 sets the read flag 3 to "1" (S15).

[0050] If the adjustment target track is readable (Yes in S11), the disk device 1 skips S15.

[0051] The disk device 1 determines whether read flag 1, read flag 2, and read flag 3 are all "0" (S16). If at least one of read flags 1, 2, and 3 is "1" (No in S16), the disk device 1 determines that data loss should be suppressed, reduces off-track slice WOS1 by a predetermined amount (S17), and returns the process to S4. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the off-track slice.

[0052] If read flag 1, read flag 2, and read flag 3 are all "0" (Yes in S16), the disk device 1 determines the waiting time of the first data track DT_1 in the target band BN to be T1 and the off-track slice to be WOS1 (S18).

[0053] As described above, in the first embodiment, the disk device 1 writes multiple data tracks to band BN in the SMR system so that the data track pitch at the leading end of band BN is larger than the other data track pitches in at least a portion of the circumferential position range. This allows a larger off-track slice to be applied to the leading data track than to the other data tracks, thereby reducing the wait time T1 for the settling process and enabling writing of the leading data track of band BN to begin while residual vibration is occurring after a seek of the actuator arm 15, thereby speeding up the write process.

[0054] Furthermore, in the first embodiment, the disk device 1 can set the off-track slice WOS1 of the first data track DT_1 in each band BN separately from the off-track slices WOS0 of the other data tracks DT_2 to DT_n-1 in the same band BN. This allows a larger off-track slice to be applied to the first data track than to the other data tracks, thereby reducing the wait time T1 for the settling process.

[0055] In consideration of the case where the amount of residual vibration changes depending on the seek distance, the disk device 1 may be configured to be able to select whether or not to implement a track arrangement in which the data track pitch PT of the first data track DT in a band BN is larger than the other data track pitches PT, depending on the radial position of the band BN. For example, the disk device 1 may not implement this in a band BN near the middle of the disk 11 (e.g., band BN2) where the maximum seek distance is halved, but may implement it in other bands BN (e.g., bands BN1 and BN3). This makes it possible to suppress the effects of residual vibration while preventing a decrease in data format efficiency, thereby speeding up write processing.

[0056] (Second embodiment) Next, a disk device 1 according to a second embodiment will be described, focusing on the differences from the first embodiment.

[0057] In the first embodiment, a track arrangement is exemplified in which the radial position of the first data track DT of the target band BN is at the center position of the servo track, while in the second embodiment, a track arrangement is exemplified in which the radial position of the first data track DT of the target band BN is shifted from the center position of the servo track.

[0058] For example, depending on the read error occurrence conditions (Condition 1) to (Condition 3) described in the first embodiment, it may be found that the amplitude of the residual vibration occurs asymmetrically with respect to the center position of the servo track, as shown in Fig. 7. Fig. 7 is a diagram showing the configuration of the data track DT according to the second embodiment. Fig. 7 illustrates control in which the radial position of the first data track DT_1a of the target band BN2 is offset by ΔOF1 from the center position of the servo track TR_1 toward the inner periphery, in response to the amplitude of the residual vibration occurring so as to be larger on the outer periphery than on the inner periphery with respect to the center position of the servo track.

[0059] If the center offset is positive on the inner periphery and negative on the outer periphery, then in the case of Figure 7, the center offset ΔOF = ΔOF1 (>0). This allows the data track pitch TP_1a between data tracks DT_1a and DT_2 in the target band BN2 to be made larger relative to the other data track pitches TP_2 to TP_n-2. As a result, writing of the first data track of band BN can be started while asymmetric residual vibration is occurring, thereby speeding up the write process.

[0060] 8 and 9, the operation of the disk device 1 differs from that of the first embodiment in the following respects. FIGS. 8 and 9 are flowcharts showing the operation of the disk device 1. The operations shown in FIGS. 8 and 9 can be mainly controlled by the controller 32.

[0061] After steps S1 to S3 are performed in the same manner as in the first embodiment, the disk device 1 sets the center offset ΔOF for the first data track DT_1 (track to be adjusted) to an initial value of "0" (S21). Thereafter, steps S4 to S16 are performed in the same manner as in the first embodiment.

[0062] If at least one of read flag 1, read flag 2, and read flag 3 is "1" (No in S16), the disk device 1 determines that data loss should be suppressed and performs read flag determination processing (S22). As shown in Fig. 10, the disk device 1 may branch and determine whether to reduce the off-track slice WOS1 or to shift the center position of the first data track DT_1 and perform writing, depending on the combination of the values ​​of read flag 1, read flag 2, and read flag 3. Fig. 10 is a diagram showing the read flag determination processing.

[0063] For example, if (read flag 1, read flag 2, read flag 3)=(0,1,0), the disk device 1 sets ΔOF=ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 toward the adjacent band BN by a predetermined amount ΔOF1, and returns the process to S4. The predetermined amount ΔOF1 can be experimentally determined in advance as an amount appropriate for fine-tuning the center offset ΔOF.

[0064] If (read flag 1, read flag 2, read flag 3) = (0, 0, 1), the disk device 1 sets ΔOF = -ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the processing to S4.

[0065] If (read flag 1, read flag 2, read flag 3)=(0, 1, 1), the disk device 1 reduces the off-track slice WOS1 by a predetermined amount and returns the process to S21. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the off-track slice.

[0066] If (read flag 1, read flag 2, read flag 3) = (1, 0, 0), the disk device 1 sets ΔOF = -ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the process to S4.

[0067] If (read flag 1, read flag 2, read flag 3)=(1, 1, 0), the disk device 1 decreases the off-track slice WOS1 by a predetermined amount and returns the process to S21.

[0068] If (read flag 1, read flag 2, read flag 3) = (1, 0, 1), the disk device 1 sets ΔOF = -ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the processing to S4.

[0069] If (read flag 1, read flag 2, read flag 3)=(1, 1, 1), the disk device 1 decreases the off-track slice WOS1 by a predetermined amount and returns the process to S21.

[0070] If read flag 1, read flag 2, and read flag 3 are all "0" (Yes in S16), the disk device 1 determines the center offset of the first data track DT_1 in the target band BN to be 0, the waiting time from the start of settling control to be T1, and the off-track slice to be WOS1 (S23).

[0071] As described above, in the second embodiment, in the SMR system, when the amplitude of residual vibration occurs asymmetrically with respect to the center position of the servo track, the disk device 1 performs track placement to shift the radial position of the first data track DT of the target band BN from the center position of the servo track. This allows writing to the first data track of the band BN to start when the residual vibration after the seek of the actuator arm 15 occurs asymmetrically, thereby speeding up the write process.

[0072] In consideration of the case where the amount of residual vibration changes depending on the seek distance, the disk device 1 may be configured to be able to select whether or not to implement a track arrangement in which the data track pitch PT of the first data track DT in a band BN is larger than the other data track pitches PT, depending on the radial position of the band BN. For example, the disk device 1 may not implement this in a band BN near the middle of the disk 11 (e.g., band BN2) where the maximum seek distance is halved, but may implement it in other bands BN (e.g., bands BN1 and BN3). This makes it possible to suppress the effects of residual vibration while preventing a decrease in data format efficiency, thereby speeding up write processing.

[0073] (Third embodiment) Next, a disk device 1 according to a third embodiment will be described, focusing on the differences from the first and second embodiments.

[0074] In the first and second embodiments, a track arrangement is exemplified in which the data track pitch at the beginning of the target band BN is wider than the other data track pitches over the entire circumference, while in the third embodiment, a track arrangement is exemplified in which the data track pitch at the beginning is partially wider than the other data track pitches.

[0075] Residual vibration during long-distance seek may fall within the allowable range within a circumferential position range PR1, which is shorter than one rotation. For example, in a disk drive 1 with one rotation of 8.3 msec, residual vibration may fall within the off-track slice at approximately 4 msec. In this case, as shown in FIG. 11, the third data track DT_3 is radially adjacent to the first data track DT_1 in band BN within the circumferential position range PR1, and the second data track DT_2 is radially adjacent to it within the subsequent circumferential position range PR2. FIG. 11 shows the configuration of data tracks DT according to the third embodiment. This configuration can be achieved by writing the second data track DT_2 from the beginning not within the circumferential position range PR1 but within the subsequent circumferential position range PR2. As a result, the data track pitch TP_1 of the first data track DT_1 is larger than the other data track pitches TP_2 to TP_n-1 within the circumferential position range PR1, but can be equal to the other data track pitches TP_2 to TP_n-1 within the circumferential position range PR2. As a result, the track pitch at the beginning of band BN in circumferential position range PR1 is larger than the other track pitches, and the track pitch at the beginning of band BN in circumferential position range PR2 is equal to the other track pitches.

[0076] In this case, the first data track DT_1 switches to use the adjustment off-track slice WOS2 in the circumferential position range PR1, and the standard off-track slice WOS0, which is the same as the other data tracks DT, in the circumferential position range PR2. This operation makes it possible to make WOS2>WOS0, suppressing a decrease in data format efficiency, and enabling the first data track DT_1 to be written even when residual vibration is occurring, thereby speeding up the write process.

[0077] The off-track slice WOS2 that takes into account residual vibration is determined so as to satisfy the following (Condition 4) to (Condition 6).

[0078] (Condition 4) When the first data track DT_1 is written, even if there is a staggered write to the last data track DT_n-1 of the adjacent band BN, the last data track DT_n-1 of the adjacent band BN can be read.

[0079] (Condition 5) When the second data track DT_2b and the third data track DT_3 in band BN are written, the first data track DT_1 is not erased and is readable.

[0080] (Condition 6) When the last data track DT_n-1 of the adjacent band BN is written, even if there is a writing error on the first data track DT_1 of the band BN, the first data track DT_1 in the band BN is readable.

[0081] In the third embodiment, the maximum value of the off-track slice WOS2 is STP / 2+WOS0 However, if the maximum value of the off-track slice WOS2 does not satisfy (Condition 4) to (Condition 6), the value of the off-track slice WOS2 is decreased.

[0082] For the first data track DT_1, off-track slice WOS2 is used in circumferential position range PR1, and the off-track slice is switched from WOS2 to WOS0 at the start of circumferential position range PR2. Therefore, as shown in FIG. 12, the disk drive 1 performs control using a waiting time T21 for off-track slice WOS2 and a waiting time T22 for off-track slice WOS0. Waiting time T21 is the time from the start of the settling process until the residual vibration settles within off-track slice WOS2 and the settling process is completed. Waiting time T22 is the time from the start of the settling process until the residual vibration settles within off-track slice WOS0 and the settling process is completed.

[0083] 13 and 14, the operation of the disk device 1 differs from that of the first embodiment in the following respects. Figures 13 and 14 are flowcharts showing the operation of the disk device 1. The operations shown in Figures 13 and 14 can be mainly controlled by the controller 32.

[0084] After steps S1 and S2 are performed in the same manner as in the first embodiment, the disk device 1 uses the servo track pitch STP and the standard off-track slice WOS0 to determine the adjustment off-track slice WOS1 according to the following equation 2 (S31). WOS2 = STP / 2 + WOS0 Equation 2

[0085] The disk device 1 determines the waiting time T21 from the start of settling control so that writing is possible in the off-track slice WOS2 (S32).

[0086] The disk device 1 determines the waiting time T22 from the start of settling control so that writing is possible on the off-track slice WOS0 (S33).

[0087] The disk device 1 determines the circumferential position range PR1, which is the unused section of the second adjacent data track DT_2, from (T22-T21) (S34).

[0088] The disk device 1 sets an initial value for each read flag. The disk device 1 sets read flag 1=0, read flag 2=0, read flag 3=0, and read flag 4=0 (S35). Thereafter, steps S6 to S10 are performed in the same manner as in the first embodiment.

[0089] The disk device 1 writes one revolution of the third data track DT_3 of the band BN in the off-track slice WOS0 (S36).

[0090] The disk device 1 determines whether the adjustment target track (data track DT_1) is readable in the circumferential position range PR1 between T21 and T22 (S37). If the adjustment target track is not readable (No in S37), the disk device 1 sets "1" to read flag 2 (S38).

[0091] If the adjustment target track is readable (Yes in S37), the disk device 1 skips S38.

[0092] The disk device 1 determines whether the track to be adjusted is readable in the circumferential position range PR2 after T22 (S39). If the track to be adjusted is not readable (No in S39), the disk device 1 sets the read flag 3 to "1" (S40).

[0093] If the adjustment target track is readable (Yes in S39), the disk device 1 skips S40, and then S13 and S14 are carried out in the same manner as in the first embodiment.

[0094] If the track to be adjusted is unreadable (No in S14), the disk device 1 sets the read flag 4 to "1" (S41).

[0095] If the track to be adjusted is readable (Yes in S14), the disk device 1 skips S41.

[0096] The disk device 1 determines whether read flag 1, read flag 2, read flag 3, and read flag 4 are all "0" (S42). If at least one of read flag 1, read flag 2, read flag 3, and read flag 4 is "1" (No in S42), the disk device 1 determines whether only read flag 3 is "1" (S43).

[0097] If only the read flag 3 is "1" (Yes in S43), the disk device 1 determines that the waiting time T22 is insufficient, increases the waiting time T22 by a predetermined time (S44), and returns the process to S34. The predetermined time can be experimentally determined in advance as an appropriate time for fine-tuning the waiting time T22.

[0098] If there is a "1" other than the read flag 3 (No in S43), the disk device 1 determines that data loss should be suppressed, reduces the off-track slice WOS2 by a predetermined amount (S45), and returns the process to S32. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the off-track slice.

[0099] If read flag 1, read flag 2, read flag 3, and read flag 4 are all "0" (Yes in S42), the disk device 1 determines the waiting time from the start of settling control to be T21, the write-off track slice in the circumferential position range PR1 between T21 and T22 to be WOS2, and the waiting time from the start of settling control for switching the write-off track slice to WOS0 to T22 (S46).

[0100] As described above, in the third embodiment, the disk device 1 controls the data track pitch at the leading end of the band BN to be wider than the other data track pitches in the SMR system. The disk device 1 widens the data track pitch at the leading end of the band BN in the circumferential position range PR1, but equalizes it with the other data track pitches in the circumferential position range PR2. This reduces the settling process wait time T1 by applying a larger off-track slice to the leading data track in the circumferential position range PR1 than to the other data tracks, and ensures the number of data tracks in the circumferential position range PR2. This speeds up the write process and prevents a decrease in data formatting efficiency.

[0101] In consideration of the case where the amount of residual vibration changes depending on the seek distance, the disk device 1 may be configured to be able to select whether or not to implement a track arrangement in which the data track pitch at the beginning is partially wider than the other data track pitches. For example, the disk device 1 may not implement this in band BN (e.g., band BN2) near the middle of the disk 11, where the maximum seek distance is half, but may implement it in other bands BN (e.g., bands BN1 and BN3). This can further suppress the degradation of data format efficiency while suppressing the effects of residual vibration and speeding up write processing.

[0102] (Fourth embodiment) Next, a disk device 1 according to a fourth embodiment will be described, focusing on the differences from the first to third embodiments.

[0103] The fourth embodiment is a combination of the second and third embodiments, and illustrates a track arrangement in which the radial position of the first data track DT of the target band BN is shifted from the center position of the servo track, and the data track pitch on the leading side is partially wider than the other data track pitches.

[0104] For example, depending on the read error occurrence conditions (Condition 4) to (Condition 6) described in the third embodiment, it may be recognized that the amplitude of the residual vibration occurs asymmetrically with respect to the center position of the servo track, as shown in Fig. 15. Fig. 15 is a diagram showing the configuration of the data track DT according to the third embodiment. Fig. 15 illustrates an example of control in which the radial position of the first data track DT_1a of the target band BN2 is offset by ΔOF1 from the center position of the servo track TR_1 toward the inner periphery, in response to the amplitude of the residual vibration occurring so as to be larger on the outer periphery than on the inner periphery with respect to the center position of the servo track.

[0105] 16 and 17, the operation of the disk device 1 differs from that of the third embodiment in the following respects. Figures 16 and 17 are flowcharts showing the operation of the disk device 1. The operations shown in Figures 16 and 17 can be mainly controlled by the controller 32.

[0106] After steps S1 to S6 are performed in the same manner as in the third embodiment, the disk device 1 sets the off-track slice to WOS2 during the waiting time T21 to T22 from the start of settling control (i.e., in the circumferential position range PR1), and sets the off-track slice to WOS0 from T22 onwards (i.e., in the circumferential position range PR2), and performs a write operation for one revolution to the target track while residual vibration is occurring immediately after the long-distance seek (S51). Thereafter, steps S8 to S42 are performed in the same manner as in the third embodiment.

[0107] If at least one of read flag 1, read flag 2, read flag 3, and read flag 4 is "1" (No in S42), the disk device 1 determines that data loss should be suppressed and performs read flag determination processing (S22). As shown in FIG. 18, the disk device 1 may branch and determine whether to lengthen the wait time T22 for the settling processing, reduce the off-track slice WOS1, or shift the center position of the first data track DT_1 before writing, depending on the combination of the values ​​of read flag 1, read flag 2, read flag 3, and read flag 4. FIG. 18 is a diagram showing the read flag determination processing.

[0108] For example, if (read flag 1, read flag 2, read flag 3, read flag 4)=(0,0,1,0), the disk device 1 sets the waiting time T22 so as to increase the waiting time T22 of the settling process by a predetermined amount, and returns the process to S34. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the waiting time T22.

[0109] If (read flag 1, read flag 2, read flag 3, read flag 4)=(0,0,0,1), the disk device 1 sets ΔOF=-ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the process to S32. The predetermined amount ΔOF1 can be experimentally determined in advance as an amount appropriate for fine-tuning the center offset ΔOF.

[0110] If (read flag 1, read flag 2, read flag 3, read flag 4)=(0, 0, 1, 1), the disk device 1 reduces the off-track slice WOS2 by a predetermined amount and returns the process to S21. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the off-track slice.

[0111] If (read flag 1, read flag 2, read flag 3, read flag 4) = (0, 1, 0, 0), the disk device 1 sets ΔOF = ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the adjacent band BN, and returns the processing to S32.

[0112] If (read flag 1, read flag 2, read flag 3, read flag 4) = (0, 1, 1, 0), the disk device 1 sets ΔOF = ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the adjacent band BN, and returns the processing to S32.

[0113] If (read flag 1, read flag 2, read flag 3, read flag 4)=(0, 1, 0, 1), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0114] If (read flag 1, read flag 2, read flag 3, read flag 4)=(0, 1, 1, 1), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0115] If (read flag 1, read flag 2, read flag 3, read flag 4) = (1, 0, 0, 0), the disk device 1 sets ΔOF = -ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the processing to S32.

[0116] If (read flag 1, read flag 2, read flag 3, read flag 4)=(1, 0, 1, 0), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0117] If (read flag 1, read flag 2, read flag 3, read flag 4) = (1, 0, 0, 1), the disk device 1 sets ΔOF = -ΔOF1 so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the processing to S32.

[0118] If (read flag 1, read flag 2, read flag 3, read flag 4)=(1, 0, 1, 1), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0119] If (read flag 1, read flag 2, read flag 3, read flag 4)=(1, 1, 0, 0), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0120] If (read flag 1, read flag 2, read flag 3, read flag 4)=(1, 1, 1, 0), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0121] If (read flag 1, read flag 2, read flag 3, read flag 4)=(1, 1, 0, 1), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0122] If (read flag 1, read flag 2, read flag 3, read flag 4)=(1, 1, 1, 1), the disk device 1 decreases the off-track slice WOS2 by a predetermined amount and returns the process to S21.

[0123] If read flag 1, read flag 2, read flag 3, and read flag 4 are all "0" (Yes in S43), the disk device 1 determines the track center position of the first data track DT_1, sets the waiting time from the start of settling control to T21, sets the write-off track slice for the section from T21 to T22 to WOS2, and determines the waiting time from the start of settling control to switch to WOS0 to T22 (S53).

[0124] As described above, in the fourth embodiment, in the SMR system, when the amplitude of residual vibration occurs asymmetrically with respect to the center position of the servo track, the disk device 1 performs track placement to shift the radial position of the first data track DT of the target band BN from the center position of the servo track. This allows writing to the first data track of the band BN to start when the residual vibration after the seek of the actuator arm 15 occurs asymmetrically, thereby speeding up the write process.

[0125] In the fourth embodiment, the disk drive 1 controls the data track pitch at the leading end of the SMR system to be wider than the other data track pitches. The disk drive 1 widens the data track pitch at the leading end of band BN in circumferential position range PR1, but equalizes it with the other data track pitches in circumferential position range PR2. This allows a larger off-track slice to be applied to the leading data track in circumferential position range PR1 than to the other data tracks, thereby reducing the settling process wait time T1, and ensuring the number of data tracks in circumferential position range PR2. This allows for faster write processing and suppresses a decrease in data formatting efficiency.

[0126] (Fifth embodiment) Next, a disk device 1 according to a fifth embodiment will be described, focusing on the differences from the first to fourth embodiments.

[0127] The first embodiment exemplifies a track arrangement in which the data track pitch at the beginning is widened by omitting the data track corresponding to the second servo track, while the fifth embodiment exemplifies a track arrangement in which the data track pitch at the beginning is widened by writing the first data track closer to the adjacent band.

[0128] For example, as shown in Figure 19, the first data track DT_1b of band BN is written by offsetting it by 0.5 servo track pitches toward the last data track DT_n of the adjacent band BN, and the data track pitch TP_1d between the first data track DT_1 and the second data track is wider than the other data track pitches TP_2 to TP_n-1.

[0129] In the fifth embodiment, the first data track DT is written closer to the adjacent band BN, and the second data track DT_2 and subsequent data tracks are written at the standard data track pitch TP, which ensures the number of data tracks DT in the band BN and improves data format efficiency.

[0130] The fifth embodiment can be realized when the residual vibration is small and there is no need to make the data track pitch at the beginning wider by an amount equivalent to one servo track than the other data track pitches, as in the first to fourth embodiments.

[0131] If the off-track slice of the first data track DT_1 is WOS3 and the standard off-track slice is WOS0, it is possible to make WOS3 > WOS0. This makes it possible to write to the first data track during residual vibration, thereby improving the write processing speed.

[0132] The off-track slice WOS3 is determined so as to satisfy the following (Condition 7) to (Condition 9).

[0133] (Condition 7) When the first data track DT_1 is written, even if there is a staggered write to the last data track DT_n of the adjacent band BN, the last data track DT_n of the adjacent band BN can be read.

[0134] (Condition 8) When the second data track DT_2 is written, the first data track DT_1 is not erased and is readable.

[0135] (Condition 9) When the last data track DT_n of the adjacent band BN is written, even if there is a shaky write to the first data track DT_1 of the band BN, the first data track DT_1 of the band BN can be read.

[0136] In the fifth embodiment, the maximum value of the off-track slice WOS3 is STP / 4 + WOS0 However, if the maximum value of the off-track slice WOS3 does not satisfy (Condition 7) to (Condition 9), the value of the off-track slice WOS3 is decreased. Also, the waiting time for the settling process for the off-track slice WOS3 is set to T3.

[0137] 20 and 21, the operation of the disk device 1 differs from that of the first embodiment in the following respects. Figures 20 and 21 are flowcharts showing the operation of the disk device 1. The operations shown in Figures 20 and 21 can be mainly controlled by the controller 32.

[0138] After steps S1 and S2 are performed in the same manner as in the first embodiment, the disk device 1 uses the servo track pitch STP and the standard off-track slice WOS0 to determine the adjustment off-track slice WOS3 according to the following equation 3 (S61). WOS3 = STP / 2 + WOS0 Equation 3

[0139] The disk device 1 determines the waiting time T3 from the start of settling control so that writing is possible on the off-track slice WOS3 (S62), after which steps S5 to S16 are carried out in the same manner as in the first embodiment.

[0140] If at least one of read flags 1, 2, and 3 is "1" (No in S16), the disk device 1 determines that data loss should be suppressed, reduces the off-track slice WOS3 by a predetermined amount (S63), and returns the process to S62. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the off-track slice.

[0141] If read flag 1, read flag 2, and read flag 3 are all "0" (Yes in S16), the disk device 1 determines the center offset of the first data track DT_1 in the target band BN to be 0.5 x STP, the waiting time from the start of settling control to T1, and the off-track slice to WOS3 (S64).

[0142] As described above, in the fifth embodiment, the disk device 1 performs track allocation in the SMR system, widening the data track pitch at the leading end by writing the leading data track in band BN closer to the adjacent band. This applies a larger off-track slice to the leading data track than to the other data tracks, reducing the settling process wait time T3, and enabling writing of the leading data track in band BN to begin while residual vibration is occurring after a seek of the actuator arm 15, thereby speeding up the write process.

[0143] In consideration of the case where the amount of residual vibration changes depending on the seek distance, the disk device 1 may be configured to be able to select whether or not to implement a track arrangement that widens the data track pitch at the leading end by writing the leading data track in a band BN closer to the adjacent band, depending on the radial position of the band BN. For example, the disk device 1 may not implement this in a band BN near the middle of the disk 11 (e.g., band BN2) where the maximum seek distance is halved, but may implement it in other bands BN (e.g., bands BN1 and BN3). This makes it possible to suppress the effects of residual vibration while preventing a decrease in data format efficiency, thereby speeding up write processing.

[0144] (Sixth embodiment) Next, a disk device 1 according to a sixth embodiment will be described, focusing on the differences from the first to fifth embodiments.

[0145] The sixth embodiment is a combination of the second embodiment and the fifth embodiment. The sixth embodiment illustrates a track arrangement in which the radial position of the first data track DT of the target band BN is further shifted from the position closer to the adjacent band BN with respect to the center position of the servo track.

[0146] For example, depending on the read error occurrence conditions of (Condition 7) to (Condition 9) described in the fifth embodiment, it may be understood that the amplitude of the residual vibration occurs asymmetrically with respect to the position shifted from the center position of the servo track to the adjacent band BN side, as shown in Fig. 22. Fig. 22 is a diagram showing the configuration of the data track DT according to the sixth embodiment. Fig. 22 illustrates an example of control in which the radial position of the first data track DT_1c of the target band BN2 is offset by ΔOF1 toward the inner periphery with respect to the position shifted 0.5 servo tracks toward the adjacent band BN from the center position of the servo track TR_1, in response to the amplitude of the residual vibration occurring so as to be larger toward the outer periphery than toward the inner periphery with respect to the position shifted from the center position of the servo track to the adjacent band BN side.

[0147] 23 and 24, the operation of the disk device 1 differs from that of the fifth embodiment in the following respects. Figures 23 and 24 are flowcharts showing the operation of the disk device 1. The operations shown in Figures 23 and 24 can be mainly controlled by the controller 32.

[0148] After steps S1 to S61 are performed in the same manner as in the fifth embodiment, the disk device 1 sets the center offset ΔOF for the first data track DT_1 (track to be adjusted) to an initial value of 0.5×STP (S71). Thereafter, steps S62 to S16 are performed in the same manner as in the fifth embodiment.

[0149] If at least one of read flag 1, read flag 2, and read flag 3 is "1" (No in S16), the disk device 1 determines that data loss should be suppressed and performs read flag determination processing (S72). As shown in Fig. 25, the disk device 1 may branch and determine whether to reduce the off-track slice WOS3 or to shift the center position of the first data track DT_1 and perform writing, depending on the combination of the values ​​of read flag 1, read flag 2, and read flag 3. Fig. 25 is a diagram showing the read flag determination processing.

[0150] For example, if (read flag 1, read flag 2, read flag 3) = (0, 1, 0), the disk device 1 sets ΔOF = ΔOF1 + 0.5 × STP so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the adjacent band BN, and returns the process to S62. The predetermined amount ΔOF1 can be experimentally determined in advance as an amount appropriate for fine-tuning the center offset ΔOF.

[0151] If (read flag 1, read flag 2, read flag 3) = (0, 0, 1), the disk device 1 sets ΔOF = -ΔOF1 + 0.5 × STP so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns processing to S62.

[0152] If (read flag 1, read flag 2, read flag 3)=(0, 1, 1), the disk device 1 reduces the off-track slice WOS3 by a predetermined amount and returns the process to S71. The predetermined amount can be experimentally determined in advance as an amount appropriate for fine-tuning the off-track slice.

[0153] If (read flag 1, read flag 2, read flag 3) = (1, 0, 0), the disk device 1 sets ΔOF = -ΔOF1 + 0.5 × STP so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns processing to S62.

[0154] If (read flag 1, read flag 2, read flag 3)=(1, 1, 0), the disk device 1 decreases the off-track slice WOS3 by a predetermined amount and returns the process to S71.

[0155] If (read flag 1, read flag 2, read flag 3) = (1, 0, 1), the disk device 1 sets ΔOF = -ΔOF1 + 0.5 × STP so as to shift the center offset ΔOF of the first data track DT_1 by a predetermined amount ΔOF1 toward the second data track DT_2, and returns the processing to S4.

[0156] If (read flag 1, read flag 2, read flag 3)=(1, 1, 1), the disk device 1 decreases the off-track slice WOS3 by a predetermined amount and returns the process to S71.

[0157] If read flag 1, read flag 2, and read flag 3 are all "0" (Yes in S16), the disk device 1 determines the center offset of the first data track DT_1 in the target band BN to be 0.5 x STP, the waiting time from the start of settling control to T1, and the off-track slice to WOS3 (S64).

[0158] As described above, in the sixth embodiment, in the SMR system, when the amplitude of residual vibration occurs asymmetrically with respect to the center position of the servo track, the disk device 1 performs track placement to further shift the radial position of the first data track DT of the target band BN from the position closer to the adjacent band BN with respect to the center position of the servo track. This allows writing to the first data track of the band BN to begin when residual vibration occurs asymmetrically after the actuator arm 15 seeks, thereby speeding up the write process.

[0159] In the sixth embodiment, the disk device 1 performs track allocation in the SMR system, widening the data track pitch at the leading end by writing the leading data track in band BN closer to the adjacent band. This allows a larger off-track slice to be applied to the leading data track than to the other data tracks, reducing the settling process wait time T3. This allows writing to the leading data track of band BN to begin while residual vibration is occurring after the actuator arm 15 seeks, thereby speeding up the write process.

[0160] In consideration of the case where the amount of residual vibration changes depending on the seek distance, the disk device 1 may be configured to be able to select whether or not to implement a track arrangement that widens the data track pitch at the leading end by writing the leading data track in a band BN closer to the adjacent band, depending on the radial position of the band BN. For example, the disk device 1 may not implement this in a band BN near the middle of the disk 11 (e.g., band BN2) where the maximum seek distance is halved, but may implement it in other bands BN (e.g., bands BN1 and BN3). This makes it possible to suppress the effects of residual vibration while preventing a decrease in data format efficiency, thereby speeding up write processing.

[0161] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0162] 1 disk unit, 11 disks, 22 heads, 32 controllers.

Claims

1. Head and a disc containing at least one band; a controller for writing a plurality of tracks in the band such that, when writing the target track in each of the at least one band while partially overlapping the target track with a track adjacent to the target track, the track pitch at the leading end of the band is larger than the track pitch of other tracks in at least a portion of a circumferential position range; A disk device comprising:

2. The controller The first track, the second track, and the third track are written within the band so as to have a track arrangement in which the track pitch between the first track and the second track is larger than the track pitch between the second track and the third track.

2. The disk device according to claim 1.

3. The controller The first track is written using a first off-track slice, and the second track and the third track are written using a second off-track slice.

3. The disk device according to claim 2.

4. The first off-track slice is greater than the second off-track slice.

4. The disk device according to claim 3.

5. A first track, a second track, and a third track are written in the band so that the track pitch at the leading end of the band is larger than the other track pitches in a first circumferential position range, and the track pitch at the leading end of the band is equal to the other track pitches in a second circumferential position range.

2. The disk device according to claim 1.

6. The controller the first track, the second track, and the third track are written within the band so that the first track is adjacent to the third track in the radial direction via a gap in the first circumferential position range, and the first track is adjacent to the third track in the radial direction via the second track in the second circumferential position range; 6. The disk device according to claim 5.

7. The controller the first track, the second track, and the third track are written within the band so that a track pitch between the first track and the second track is larger than a track pitch between the second track and the third track in the second circumferential position range; 7. The disk device according to claim 6.

8. The controller writing the first track using a first off-track slice in the first circumferential position range, writing the first track using a second off-track slice in the second circumferential position range, and writing the second track and the third track using the second off-track slice in the first circumferential position range and the second circumferential position range, respectively; 7. The disk device according to claim 6.

9. The controller Depending on the radial position of the band including the first track, the second track, and the third track, it is possible to select for each of the at least one band whether or not to implement a track arrangement in which the track pitch between the first track and the second track is larger than the track pitch between the second track and the third track.

3. The disk device according to claim 2.

10. The controller Depending on the radial position of the band including the first track, the second track, and the third track, it is possible to select whether to limit the use range of the second track in the circumferential direction for each of the at least one band.

6. The disk device according to claim 5.

Images