disk devices

Abstract

This provides a high-performance disk device. Multiple first-servo sectors are arranged with circumferential spacing within the disk. Each of the multiple first-servo sectors includes a first region and a second region. First information, including a preamble, servo flag, and Gray code, is written to the first region. The second region is located behind the first region in the circumferential write / read direction and is written with second information including a burst pattern. The multiple first-servo sectors include multiple second-servo sectors and multiple third-servo sectors. One or more third-servo sectors are arranged between two adjacent second-servo sectors. The circumferential length of the first region in each of the multiple third-servo sectors is longer than the circumferential length of the first region in each of the multiple second-servo sectors.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2022-126097 (filed on August 8, 2022). This application incorporates the entire contents of that basic application by reference. Technical Field

[0002] This embodiment relates to a disk drive. Background Technology

[0003] In a typical disk drive, multiple servo areas, where servo information is written, are spaced apart along the circumference of the disk. Furthermore, the areas between these servo areas along the circumference of the disk serve as data areas where data can be written. Summary of the Invention

[0004] Embodiments of the present invention provide a high-performance disk device.

[0005] According to one embodiment, a disk drive includes a disk, read / write heads, and a controller. The disk has a plurality of first servo sectors arranged with circumferential spacing. The disk has a plurality of data regions disposed between adjacent first servo sectors along the circumferential direction. Each of the plurality of first servo sectors includes a first region and a second region. First information, including a preamble, a servo flag, and Gray code, is written to the first region. The second region is disposed behind the first region in the write / read direction along the circumferential direction and is written with second information including a burst pattern. The plurality of first servo sectors includes a plurality of second servo sectors and a plurality of third servo sectors. One or more third servo sectors are disposed between adjacent second servo sectors. The circumferential length of the first region of each of the plurality of third servo sectors is longer than the circumferential length of the first region of each of the plurality of second servo sectors. In a write operation, the controller demodulates the first and second information when the read / write head passes through one of the plurality of second servo sectors. When the read / write head passes through one of the plurality of third servo sectors, it demodulates the second information without demodulating the first information. The write operation is the act of using the read / write head to write data to one or more of the plurality of data regions. In a read operation, the controller demodulates the first and second information when the read / write head passes through one of the plurality of second servo sectors. When the read / write head passes through one of the plurality of third servo sectors, it demodulates the first and second information. The read operation is the act of using the read / write head to read data from one or more of the plurality of data regions. Attached Figure Description

[0006] Figure 1 This is a schematic diagram illustrating an example of the configuration of the disk device according to the first embodiment.

[0007] Figure 2 This is a schematic diagram illustrating an example of the configuration of the disk in the first embodiment.

[0008] Figure 3 This is a diagram illustrating an example of the positional relationship between the read head and the write head in the first embodiment.

[0009] Figure 4 This is a diagram illustrating an example of the configuration of a typical servo sector in the first embodiment.

[0010] Figure 5This is a diagram illustrating an example of the configuration of a short servo sector in the first embodiment.

[0011] Figure 6 This is a schematic diagram illustrating the Gray code written in the Gray code region of a typical servo sector in the first embodiment.

[0012] Figure 7 This is a schematic diagram illustrating the Gray code written in the Gray code region of the short servo sector in the first embodiment.

[0013] Figure 8 This is a schematic diagram used to explain the relationship between the types of servo sectors, the types of actions being executed, and the modes of the servo gates used in the first embodiment.

[0014] Figure 9 This is a schematic diagram illustrating an example of a servo gating waveform for the NormalSG1 pattern used when the read / write head passes through a normal servo sector during the write operation in the first embodiment.

[0015] Figure 10 This is a schematic diagram illustrating an example of the servo gating waveform used in the ShortSG mode during the write operation in the first embodiment when the read / write head passes through a short servo sector.

[0016] Figure 11 This is a schematic diagram illustrating an example of a servo gating waveform used in the NormalSG1 mode during the read operation in the first embodiment when the read head passes through a normal servo sector.

[0017] Figure 12 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG2 mode during the read operation in the first embodiment when the read head passes through a short servo sector.

[0018] Figure 13 This is a schematic diagram illustrating an example of a servo gating waveform used in the SeekSG1 mode during the seek operation in the first embodiment when the read / write head passes through a normal servo sector.

[0019] Figure 14 This is a schematic diagram illustrating an example of the servo gating waveform used in the SeekSG2 mode during the seek operation in the first embodiment when the read / write head passes through a short servo sector.

[0020] Figure 15 This is a flowchart illustrating an example of the operation of the controller in the first embodiment that determines the demodulation method of servo information for each servo sector.

[0021] Figure 16 This is a schematic diagram illustrating an example of the configuration of the disk in the second embodiment.

[0022] Figure 17 This is a diagram illustrating an example of the configuration of a typical servo sector in the second embodiment.

[0023] Figure 18 This is a schematic diagram used to illustrate the Gray code written in the Gray code region of the second embodiment.

[0024] Figure 19 This is a schematic diagram used to explain the relationship between the type of action and the servo gating mode used in the execution of the second embodiment.

[0025] Figure 20 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG3 mode during the write operation in the second embodiment when the read / write head passes through a normal servo sector.

[0026] Figure 21 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG3 mode during the read operation in the second embodiment when the read head passes through a normal servo sector.

[0027] Figure 22 This is a schematic diagram illustrating an example of the servo gating waveform used in the SeekSG3 mode during the seek operation in the second embodiment when the read / write head passes through a normal servo sector.

[0028] Figure 23 This is a flowchart illustrating an example of the operation of the controller in the second embodiment that determines the demodulation method of servo information for each servo sector.

[0029] Label Explanation

[0030] 1. 1a Disk drive; 2. Host; 11. 11a Disk; 12. Spindle motor; 13. Ramp; 15. Actuator arm; 16. VCM; 21. Motor driver IC; 22. Head; 22r Read head; 22w Write head; 23. HDC; 24. Head IC; 25. RWC; 26. Processor; 27. RAM; 28. FROM; 29. ​​Buffer memory; 30. 30a Controller; 31. Counter; 41. Track. Detailed Implementation

[0031] Hereinafter, the disk device according to the embodiments will be described in detail with reference to the accompanying drawings. However, the invention is not limited to these embodiments.

[0032] (First Embodiment)

[0033] Figure 1 This is a schematic diagram illustrating an example of the configuration of the disk device 1 according to the first embodiment.

[0034] Disk device 1 is connected to host 2. Disk device 1 can receive access commands such as write commands and read commands from host 2.

[0035] The disk drive 1 includes a disk 11 on which a magnetic layer is formed. The disk drive 1 writes data to the disk 11 and reads data from the disk 11 according to access commands.

[0036] Data writing and reading are performed via the read / write head 22. Specifically, in addition to the disk 11, the disk device 1 also includes a spindle motor 12, a ramp 13, an actuator arm 15, a voice coil motor (VCM) 16, a motor driver IC (Integrated Circuit) 21, a read / write head 22, a hard disk controller (HDC) 23, a head IC 24, a read / write channel (RWC) 25, a processor 26, RAM 27, FROM (Flash Read Only Memory) 28, a buffer memory 29, and a counter 31.

[0037] The disk 11 is rotated at a predetermined speed by a spindle motor 12 mounted coaxially. The spindle motor 12 is driven by a motor driver IC 21.

[0038] The processor 26 controls the rotation of the spindle motor 12 and the VCM 16 via the motor driver IC 21.

[0039] The read / write head 22 writes and reads information from the disk 11 using its write head 22w and read head 22r. The read / write head 22 is mounted at the front end of the actuator arm 15. The read / write head 22 moves radially across the disk 11 via a VCM 16 driven by a motor driver IC 21. Furthermore, either or both of the write head 22w and read head 22r can be provided in multiple configurations relative to a single read / write head 22.

[0040] When the disk 11 stops rotating, the read / write head 22 is moved onto the ramp 13. The ramp 13 is configured to hold the read / write head 22 in a position where it has left the disk 11.

[0041] During a read operation, head IC24 amplifies and outputs the signal read by head 22 from disk 11, and provides it to RWC25. Additionally, during a write operation, head IC24 amplifies the signal corresponding to the data to be written from RWC25 and provides it to head 22.

[0042] HDC23 controls data transmission and reception between the HDC23 and the host 2 via the I / F bus, controls the buffer memory 29, and performs error correction processing on the read data.

[0043] The buffer memory 29 is used as a buffer for data transmission and reception between the host 2 and the host 2. For example, the buffer memory 29 is used to temporarily store data to be written or data read from the disk 11.

[0044] The buffer memory 29 may be composed, for example, of a volatile memory capable of high-speed operation. The type of memory constituting the buffer memory 29 is not limited to a specific type. The buffer memory 29 may be composed, for example, of DRAM (Dynamic Random Access Memory), SRAM (Static Random Access Memory), or a combination thereof. Furthermore, the buffer memory 29 may also be composed of any non-volatile memory.

[0045] RWC25 modulates the data to be written from HDC23 and provides it to head IC24. Additionally, RWC25 demodulates the signals read from disk 11 and provided by head IC24, outputting them as digital data to HDC23.

[0046] The processor 26 is, for example, a CPU (Central Processing Unit). Connected to the processor 26 are RAM 27, FROM (Flash Read Only Memory) 28, buffer memory 29, and a counter 31.

[0047] FROM 28 is a non-volatile memory. Firmware (program data) and various operational parameters are stored in FROM 28. Additionally, the firmware can also be stored on disk 11.

[0048] RAM 27 is composed of, for example, DRAM, SRAM, or a combination thereof. RAM 27 is used by the processor 26 as its working memory. RAM 27 is used as an area for loading firmware and as an area for temporarily storing various management data.

[0049] The processor 26 performs overall control of the disk device 1 according to the firmware stored in the FROM 28 or the disk 11. For example, the processor 26 loads the firmware from the FROM 28 or the disk 11 into the RAM 27, and executes the control of the motor driver IC 21, head IC 24, RWC 25, HDC 23, etc. according to the loaded firmware.

[0050] Counter 31 is a timer circuit whose count increases over time. Processor 26 uses counter 31 to determine the timing of various actions. The type of counter 31 is not limited to a specific type. In one example, counter 31 could also be a VCO (Voltage-controlled oscillator) counter.

[0051] Furthermore, the configuration including HDC23, RWC25, processor 26, and counter 31 can also be considered as controller 30. Besides these, controller 30 may also include other elements (such as RAM27, FROM28, or buffer memory 29). Counter 31 may also be located externally to controller 30.

[0052] Alternatively, the firmware program can also be stored on disk 11. Furthermore, some or all of the functions of processor 26 can be implemented using hardware circuitry such as FPGA (Field-Programmable Gate Array) or ASIC (Application Specific Integrated Circuit).

[0053] Figure 2 This is a schematic diagram illustrating an example of the configuration of the disk 11 according to the first embodiment. Furthermore, this figure shows an example of the rotation direction of the disk 11. The read / write head 22 moves relative to the disk 11 as the disk 11 rotates. Therefore, the direction in which data is written or read by the read / write head 22 along the write / read direction, i.e., the circumferential direction, is the opposite direction to the rotation direction of the disk 11.

[0054] During the manufacturing process, servo information used for positioning the read / write head 22 is written to the disk 11, for example, via a servo writer or self-servo write (SSW). Figure 2 As an example of the configuration of servo areas where servo information is written, multiple servo areas SV are depicted arranged radially in the radial direction and spaced at predetermined intervals in the circumferential direction. The area between two consecutive servo areas SV in the circumferential direction is used as a data area DA for writing data.

[0055] In addition, the data written to the data area DA includes user data received from host 2, metadata accompanying the user data (such as error correction codes), system data, etc.

[0056] Multiple servo regions (SVs) include multiple regular servo regions (NSVs) and multiple short servo regions (SSVs). According to... Figure 2In the example shown, typical servo regions NSV and short servo regions SSV are arranged alternately in the circumferential direction. That is, at least one short servo region SSV is arranged between two typical servo regions NSV arranged consecutively in the circumferential direction, or in other words, between two adjacent typical servo regions NSV.

[0057] Multiple concentric tracks 41 are set in the radial direction of the disk 11. Multiple data sectors are continuously formed along each track 41 in the data area DA. Servo information written to the servo area SV is used for seek operations to move the read / write head 22 toward the target track 41 and for tracking operations to keep the read / write head 22 on the target track 41.

[0058] From now on, the regions on track 41 distinguished by the normal servo region NSV will be recorded as normal servo sectors NSV. The regions on track 41 distinguished by the short servo region SSV will be recorded as short servo sectors SSV. In addition, the normal servo sectors NSV and short servo sectors SSV will be collectively referred to as servo sectors SV.

[0059] Furthermore, when first data and second data are written along the write / read direction, and the first data is written to an area before the second data is read, the direction from the area where the second data was written toward the area where the first data was written is sometimes described as "before" or "in front" of the area where the second data was written. Conversely, the direction from the area where the first data was written toward the area where the second data was written is sometimes described as "after" or "behind" of the area where the first data was written. When referring to the first area, it is described as "the second area immediately preceding" or "the second area immediately preceding". "The second area immediately preceding" and "the second area immediately preceding" are defined as the second area that the read / write head 22 passes through last, before the first area. When referring to the first area, it is described as "the second area immediately following" or "the second area immediately following". "The second area immediately following" and "the second area immediately following" are defined as the second area that the read / write head 22 first passes through, after the first area.

[0060] Additionally, in the circumferential direction, the front end of a region is sometimes referred to as the "beginning" of that region. Also, in the circumferential direction, the rear end of a region is sometimes referred to as the "end" of that region.

[0061] Figure 3This figure illustrates an example of the positional relationship between the read head 22r and the write head 22w in the first embodiment. According to the example shown in this figure, the read head 22r and the write head 22w are arranged in the direction in which the actuator arm 15 extends. Furthermore, the read head 22r is positioned closer to the rotation axis of the actuator arm 15 than the write head 22w. And, with the read head 22 positioned on a track 41, the write head 22w moves relative to the disk 11, lagging behind the read head 22r.

[0062] That is, in the circumferential direction of disk 11, there is a gap between the read head 22r and the write head 22w, and the write head 22w moves relative to disk 11 in a manner that lags behind the read head 22r accordingly. The length of the gap in the circumferential direction between the read head 22r and the write head 22w is recorded as the read / write gap length RWgap.

[0063] Furthermore, the read / write gap length RWgap varies according to the skew angle of the read / write head 22. And, the skew angle of the read / write head 22 varies according to the radius of the read / write head 22. That is, the read / write gap length RWgap varies according to the radius of the read / write head.

[0064] In the write operation of writing data to the data area of ​​the target track, the reading of servo information from the servo area SV by the read head 22r and the writing of data to the data area DA by the write head 22w are performed exclusively in time. However, since the write head 22w moves in the circumferential direction of the disk 11 with the read-write gap length RWgap correspondingly lagging behind the read head 22r, an area in the circumferential direction immediately preceding the servo sector SV may sometimes be generated where data cannot be written. Such an area where data cannot be written is referred to as the unwritable area UA in this specification.

[0065] In order to minimize the total capacity of the non-writable area UA in disk 11, controller 30 does not read the front part of the servo information recorded in the short servo sector SSV during write operations.

[0066] That is, the short servo sector (SSV) and the normal servo sector (NSV) are configured such that, during a write operation, the length of the interval in the short servo sector (SSV) for reading servo information is shorter than the length of the interval in the normal servo sector (NSV) for reading servo information. Furthermore, the short servo sector (SSV) and the normal servo sector (NSV) are configured such that, during a write operation, the first portion of the short servo sector (SSV) is not read.

[0067] Even when the read head 22r reaches the short servo sector SSV during a write operation, the controller 30 can still write data between the read head 22r and the rear part of the short servo sector SSV. Therefore, it can suppress the length of the unwritable region UA ​​that exists immediately before the short servo sector SSV. As a result, the total capacity of the unwritable region UA ​​within the disk 11 can be suppressed.

[0068] Furthermore, the servo information recorded in the first part of the short servo sector (SSV) is read during seek and read operations. The seek operation is the movement of the read / write head 22 radially toward the target track 41. The read operation is the reading of data from the data area DA.

[0069] While installing short servo sector SSVs can suppress the length of the unwritable region UA ​​immediately preceding the short servo sector SSV, it is not always possible to completely eliminate this unwritable region UA ​​in some cases. In the first embodiment, by optimizing the configuration of the servo information recorded in the short servo sector SSV, the length of the unwritable region UA ​​immediately preceding the short servo sector SSV can be further suppressed. Specific examples of the configuration of a typical servo sector NSV and a short servo sector SSV will be described below.

[0070] Figure 4 This diagram illustrates an example of the configuration of a typical servo sector NSV according to the first embodiment. In this example, in the typical servo sector NSV, the preamble region PA2 (for writing preamble #2), the preamble region PA1 (for writing preamble #1), the servo tag region SM (for writing servo tags), the Gray code region GC1 (for writing Gray code), the pad region PAD (for writing pads), the burst region BN (for writing N bursts), the burst region BQ (for writing Q bursts), and the postcode region PC (for writing postcodes) are configured in this order along the write / read direction.

[0071] Preamble #1 and preamble #2 are information that constitute a single-cycle pattern that changes periodically in the circumferential direction. Preamble #1 and preamble #2 are used to adjust the amplitude, phase, and frequency of the sampled data when the servo waveform read by the read head 22r is input into the RWC25 based on the servo clock.

[0072] During read and write operations, preamble #2 is not read; only preamble #1 is read. During seek operations, in order to suppress the degradation of the accuracy of the servo waveform sampling data caused by the high-speed radial movement of the read / write head 22, preamble #2 is also read in addition to preamble #1.

[0073] The servo flag is pattern data that indicates the start of servo information. The controller 30 uses the detection timing of the servo flag as a reference to determine the timing of subsequent servo information intake.

[0074] Furthermore, details will be described later, but servo markers are also written in short servo sectors (SSVs). That is, servo markers are written in each servo sector (SV) regardless of whether the servo sector (SV) is a normal servo sector (NSV) or a short servo sector (SSV). The intervals between the positions where servo markers are written are fixed in the circumferential direction. However, the intervals between the positions where servo markers are written may not be fixed in the circumferential direction.

[0075] Gray code includes cylinder addresses for identifying each track 41 on disk 11 and sector addresses for identifying each servo sector SV on track 41.

[0076] PAD represents the boundary between the Gray code region GC1 and the burst region BN.

[0077] The N-pulse and Q-pulse are pattern data used to detect the position deviation from the center of track 41, represented by the track number contained in Gray code #1. The N-pulse and Q-pulse are examples of pulse data. The cylinder address contained in the Gray code is provided, for example, as an integer value. By demodulating the N-pulse and Q-pulse, the offset below the decimal point, based on the position represented by the cylinder address, can be obtained. That is, by demodulating the N-pulse and Q-pulse, the current position of head 22 can be obtained. The current position of head 22 refers to the position of head 22 on disk 11 during the timing of demodulating servo information. The current position of head 22 obtained by demodulating the N-pulse and Q-pulse is recorded as the demodulated position.

[0078] The suffix represents the correction amount for the deviation of the shape of track 41, defined by Gray code, N-pulse, and Q-pulse, from the ideal shape of track 41. This deviation varies synchronously with the rotation of disk 11. Therefore, this deviation is also referred to as RRO (Repeatable Run Out). That is, the suffix is ​​used to correct the RRO.

[0079] The preamble region PA2, preamble region PA1, servo marker region SM, and Gray code region GC1 in the servo sector SV are referred to as the front area FA, meaning the area at the beginning of the servo sector SV. The area in the servo sector SV that is after region FA is referred to as the rear area RA, meaning the area at the end of the servo sector SV.

[0080] That is, the front region contains servo information (first information) including preamble, servo flag, and Gray code. The back region contains servo information including burst pattern (second information).

[0081] Furthermore, the preceding region FA in a servo sector NSV is usually recorded as the preceding region FAn. The following region RA in a servo sector NSV is usually recorded as the following region Ran.

[0082] During the write operation, the controller 30 reads servo information from the area after the preamble region PA1 within the normal servo sector NSV. A predetermined time is required to switch the mode of the read / write head 22 from write mode to read mode. During this switching period, the read / write head 22 continues to move in a circular direction. Write mode is the mode capable of writing data, and read mode is the mode capable of reading data. The distance traveled by the read / write head 22 during the switch from write data mode to read data mode is recorded as the write-read transition length. Figure 4 The write-read transition length (W2R) is required. That is, when writing data to the data area DA and then reading servo information from the servo area SV, a margin of at least the read transition length W2R is required between the end of the data writing position and the start of the servo information reading position.

[0083] In addition, after writing to the data area DA is completed, a degaussing process is performed where a write current flows in the write head 22w at a certain frequency and decays over a predetermined period. During the degaussing process, no intentional data writing is allowed. The length of the area where the degaussing process is performed is recorded as the degaussing length L. DEG .

[0084] exist Figure 4 In the process, when the read head 22r reaches position P1 after leaving the write-read transition length W2P in the opposite direction from the beginning position P0 of the preamble region PA1, data writing to the data region DA is stopped. At the timing of this write stop, the write head 22w is located at position P4 after leaving position P1 after leaving the read-write gap length RWgap in the opposite direction from the write / read direction. When the write head 22w reaches position P4, data writing stops, and degaussing begins. Degaussing is performed until the write head 22w reaches position P4 after leaving the degaussing length L in the write / read direction. DEG Position P3.

[0085] Therefore, in Figure 4 As shown in the example, the region from position P3 to the beginning of the preamble region PA2 is equivalent to the unwritable region UA.

[0086] Figure 5This diagram illustrates an example of the configuration of the short servo sector (SSV) according to the first embodiment. In this example, in the short servo sector (SSV), the preamble region PA2 (for writing preamble #2), the preamble region PA1 (for writing preamble #1), the servo tag region SM (for writing servo tags), the Gray code regions GC2 and GC1 (for writing Gray codes), the region PAD (for writing PAD), the pulse train region BN (for writing N pulse trains), the pulse train region BQ (for writing Q pulse trains), and the append code region AC (for writing additional code) are configured in this order along the write / read direction.

[0087] In other words, the difference between the structure of a short servo sector (SSV) and that of a typical servo sector (NSV) is that a Gray code region (GC2) is added to the front region (FA), and an append code region (AC) is set in the rear region (RA) to replace the postcode region (PC). Alternatively, the append code region (AC) may be omitted.

[0088] Furthermore, the preceding region FA in a short servo sector SSV is recorded as the preceding region FAs. The following region RA in a short servo sector SSV is recorded as the following region RAs.

[0089] Compared to a typical servo sector NSV, the length of the front region FA of a short servo sector SSV is correspondingly longer due to the addition of a Gray code region GC2 to the front region FA.

[0090] During the write operation, the controller 30 does not read servo information in the front region FAs, but reads servo information from the rear region Ras. That is, the controller 30 starts reading servo information at the timing when the read head 22r reaches the beginning position P10 of the rear region Ras. Therefore, the controller 30 stops writing data to the data region DA at the timing when the read head 22r reaches position P11 after leaving the write / read transition length W2P in the opposite direction of the write / read direction from the beginning position P10 of the rear region Ras.

[0091] At the timing when data writing stops, the write head 22w is at position P14, located after leaving position P11 in the opposite direction to the write / read direction, following the read / write gap length RWgap. When the write head 22w reaches position P14, data writing stops, and degaussing begins. Degaussing is then performed until the write head 22w reaches position P14 again, after leaving position P14 in the write / read direction, following the degaussing length L. DEG The position after P13.

[0092] That is, the distance (P13-P10) between position P13 and the starting position P10 of the subsequent region Ras can be calculated according to the following formula (1).

[0093] P13-P10=W2R+RWGap-L DEG (1)

[0094] In contrast, the distance (P12-P10) between the beginning position P12 of the preamble region PA2 and the beginning position P10 of the subsequent region Ras can be calculated according to the following equation (2). However, in the following equation (2), L PA2 L represents the length of the preamble region PA2. PA1 L represents the length of the preamble region PA1. SM L represents the length of the servo marker region SM. GC2 L represents the length of the Gray code region GC2. GC1 This indicates the length of the Gray code region GC1.

[0095] P12-P10=L PA2 +L PA1 +L SM +L GC2 +L GC1 (2)

[0096] exist Figure 5 In the scenario shown, the distance (P13-P10) is equal to the distance (P12-P10). Therefore, there is no unwritable region UA.

[0097] Here, a technique compared to the implementation method is described. The technique compared to the implementation method is described as a comparative example. According to the comparative example, the front region of the short servo sector has the same configuration as the front region FAn of a typical servo sector NSV. That is, the front region involved in the comparative example has a configuration from... Figure 5 The preceding regions FAs shown omit the Gray code region GC2. In that case, the distance (P12'-P10) between the beginning position P12' of the preamble region PA2 and the beginning position P10 of the following region can be calculated according to the following equation (3). However, the lengths of the preamble region PA2, the preamble region PA1, the servo marker region SM, and the Gray code region GC1 are set to be equal in the comparative example and the embodiment.

[0098] P12'-P10=L PA2 +L PA1 +L SM +L GC1 (3)

[0099] From equations (2) and (3), it can be read that the distance (P12'-P10) in the comparative example is shorter than the distance (P12-P10) in the implementation method. This is the length L of the Gray code region GC2. GC2That is, according to the comparative example, there is a space between the position P13 at the end of the demagnetization process and the beginning position P12' of the preamble region PA2. This space becomes the unwritable region UA ​​immediately preceding the short servo sector SSV.

[0100] According to the implementation method, compared with the comparative example, it is possible to match the length L of the Gray code region GC2. GC2 Accordingly, the length of the non-writable region UA ​​immediately preceding the short servo sector SSV is suppressed. Thus, the total capacity of the non-writable region UA ​​within disk 11 can be suppressed.

[0101] Furthermore, according to the implementation method, as specified in equation (1), the position P13 at which the demagnetization process ends is independent of the length L of the Gray code region GC2. GC2 That is, the position P13 where the degaussing process ends is the same in both the implementation and the comparative example. Therefore, according to the implementation, the total capacity of the writable region UA ​​can be suppressed without degrading format efficiency.

[0102] In addition, Figure 5 In the example shown, the position P13 where the demagnetization process ends coincides with the beginning position P12 of the preamble region PA2. The position P13 where the demagnetization process ends and the beginning position P12 of the preamble region PA2 do not necessarily have to coincide. Alternatively, there may be a non-writable region UA ​​of a certain length in the circumferential direction between the two positions.

[0103] For example, consider the length L of the Gray code region GC2 in all tracks 41 within disk 11. GC2 This is assumed to be common. In that case, the designer can also set the length L of the Gray code region GC2 based on the minimum value of the read / write gap length RWgap within disk 11. GC2 Specifically, the designer can also determine the length L of the Gray code region GC2. GC2 This is done so that at the radius where the read / write gap length RWgap is minimized, the distance (P13-P10) is equal to the distance (P12-P10). The length L of the Gray code region GC2 is determined using this method. GC2 In the case where the read / write gap length RWgap does not take the minimum value, a space is generated between the position P13 where the demagnetization process ends and the beginning position P12 of the preamble region PA2. This space becomes the unwritable region UA.

[0104] Alternatively, the designer can also determine the length L of the Gray code region GC2. GC2This is done so that at the radius where the read / write gap length RWgap reaches its minimum value, the distance (P13-P10) is slightly larger than the distance (P12-P10). The length L of the Gray code region GC2 is determined using this method. GC2 In this case, a non-writable region UA ​​will be generated at any radius position, and the length of the non-writable region UA ​​becomes the minimum at the radius position where the read / write gap length RWgap is the minimum value.

[0105] In addition, the designer can also adjust the length L of the Gray code region GC2 in each track 41. GC2 Depending on the radius position, the distance (P13-P10) is equal to the distance (P12-P10) at any radius position. The length L of the Gray code region GC2 in each track 41 is determined in that way. GC2 In this case, the unwritable region UA ​​immediately preceding the short servo sector SSV can be eliminated at any radius location.

[0106] As mentioned above, an append code region AC is set in the rear region Ras of the short servo sector SSV.

[0107] During the write operation, the timing for demodulating the N-pulse and Q-pulse trains from the subsequent region Ras of the short servo sector SSV is not based on the servo flag written to the short servo sector SSV itself, but rather on the elapsed time based on the timing of detecting the servo flag in the immediately preceding normal servo sector NSV. The elapsed time is counted by counter 31; the larger the count value of counter 31, the greater the error contained in the count value. Therefore, in the short servo sector SSV, due to the error contained in the count value, sometimes the following unusual detection occurs: the timing for demodulating the N-pulse and Q-pulse trains deviates from the intended timing, thus causing the demodulation position to deviate significantly from the actual position. The append code written to the append code region AC is data used to correct the demodulation position obtained in the unusual detection.

[0108] Figure 6 This is a schematic diagram illustrating the Gray code written in the Gray code region GC1 of the general servo sector NSV of the first embodiment.

[0109] exist Figure 6 In the example shown, the full Gray code includes a complete sector address on the high-order side and a complete cylinder address on the low-order side. The complete sector address has a data structure including bits S0, S1, and S2 from the high-order side. The complete cylinder address has a data structure including bits C0, C1, C3, and Clow from the high-order side.

[0110] The complete sector address S0-S2 is divided into three parts, and the high-order bits C0-C2 of the complete cylinder address are also divided into three parts. Furthermore, in the Gray code region GC1 of the first of the three consecutive NSVs (Normal Server Sectors) arranged along the write / read direction, bits S0, C0, and Clow are written from the high-order side. In the Gray code region GC1 of the second NSV, bits S1, C1, and Clow are written from the high-order side. In the Gray code region GC1 of the last NSV, bits S2, C2, and Clow are written from the high-order side.

[0111] That is, in the implementation, the complete Gray code is distributed across three typical servo sectors (NSVs). This allows for the suppression of the length L of the Gray code region GC1. GC1 This improves formatting efficiency. Instead, to obtain the complete sector address and the complete cylinder address, the controller 30 needs to demodulate Gray code from three consecutively configured normal servo sectors (NSVs). For example, during a seek operation, if Gray code cannot be demodulated from all normal servo sectors of the three consecutively configured normal servo sectors (NSVs) without errors, the complete cylinder address cannot be determined.

[0112] Figure 7 This is a schematic diagram illustrating the Gray code written in the Gray code regions GC1 and GC2 of the short servo sector SSV in the first embodiment.

[0113] exist Figure 7 In the example shown, the complete sector address S0 to S2 is divided into three parts, while the complete cylinder address is not divided. Furthermore, in the first short servo sector SSV of the three short servo sector SSVs configured consecutively along the write / read direction, bits S0 and C0 are written in the Gray code region GC2 starting from the high-order side, and bits C1, C2, and the column Clow are written in the Gray code region GC1 starting from the high-order side. In the second short servo sector SSV of the three short servo sector SSVs, bits S1 and C0 are written in the Gray code region GC2 starting from the high-order side, and bits C1, C2, and the column Clow are written in the Gray code region GC1 starting from the high-order side. In the last short servo sector SSV of the three short servo sectors SSV, starting from the high-order side, bits S2 and C0 are written in the Gray code region GC2, and bits C1, C2 and Clow are written in the Gray code region GC1 starting from the high-order side.

[0114] Since the Gray code is written as described above, the controller 30 can obtain the complete cylinder address from any short servo sector SSV. If the Gray code can be demodulated from a single short servo sector SSV without errors, the complete cylinder address can be determined, thus reducing the frequency of seek errors.

[0115] In addition, the controller 30 can determine whether the complete cylinder address has been understood earlier during the reading operation, thus improving the reading performance.

[0116] In addition, Figure 6 and Figure 7 The Gray code writing method described in [the document] is an example. It allows writing Gray code regions of length L to the GC2 region. GC2 In cases where the setting is longer, complete Gray codes can also be written into the Gray code regions GC1 and GC2 of each short servo sector SSV. In such cases, the controller 30 can obtain complete Gray codes from each short servo sector SSV during the read operation, thus reducing the speed required for positioning during the read operation.

[0117] That is, in the first embodiment, the amount of Gray code information obtained from the short servo sector SSV is greater than the amount of Gray code information obtained from the normal servo sector NSV. Furthermore, according to the first embodiment, the amount of Gray code information obtained from the short servo sector SSV is greater than that of the comparative example where there is no Gray code region GC2 in the preceding region. Therefore, read performance is improved compared to the comparative example. In other words, a high-performance disk device can be obtained. Additionally, the frequency of seek errors is improved compared to the comparative example, resulting in a high-performance disk device.

[0118] The controller 30 generates write strobe, read strobe, and servo strobe, and performs actions based on these generated internal signals. The write strobe is an internal signal that indicates the period during which data is written to the data area DA, the read strobe is an internal signal that indicates the period during which data is read from the data area DA, and the servo strobe is an internal signal that indicates the timing of reading servo information.

[0119] More specifically, when the read / write head 22 passes through a servo sector SV, the processor 26 notifies the HDC 23 and RWC 25 of the type of the servo sector SV and the type of action being performed. Based on the type of the servo sector SV and the type of action being performed as notified by the processor 26, the HDC 23 controls the write strobe, read strobe, and servo strobe. Based on the write strobe, read strobe, servo strobe, and notification from the processor 26, the RWC 25 causes the head IC 24 to perform the reading and writing of user data and the demodulation of servo information.

[0120] The controller 30 uses five modes of servo strobe based on the category of the servo sector (SV) and the category of the action being executed.

[0121] Figure 8 This is a schematic diagram used to explain the relationship between the types of servo sectors (SVs) in the first embodiment, the types of actions being executed, and the servo strobing modes used.

[0122] During write and read operations, when the read / write head 22 passes through the normal servo sector NSV, the servo gating of the waveform in the NormalSG1 mode is used. During seek operations, when the read / write head 22 passes through the normal servo sector NSV, the servo gating of the SeekSG1 mode is used.

[0123] During a write operation, when the read / write head 22 passes through a short servo sector (SSV), the servo gating mode of ShortSG is used. During a read operation, when the read / write head 22 passes through a short servo sector (SSV), the servo gating mode of NormalSG2 is used. During a seek operation, when the read / write head 22 passes through a short servo sector (SSV), the servo gating mode of SeekSG2 is used.

[0124] Figure 9 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG1 mode during the write operation of the first embodiment when the read / write head 22 passes through a normal servo sector NSV. Figure 9 The text describes the temporal shift of the position of the read head 22r in the circumferential direction. It also describes the relationship between the position of the read head 22r and the states of the write strobe and the servo strobe.

[0125] When the read head 22r reaches the position after leaving the write-read transition length W2R in the opposite direction of the write / read direction from the beginning of the preamble region PA1 (time t0), HDC23 disables data writing by deasserting the write strobe.

[0126] When the read head 22r reaches the beginning of the preamble region PA1 (time t1), HDC23 asserts the servo gating.

[0127] RWC25 demodulates servo information during the period when the servo strobe is asserted. When RWC25 detects a servo flag during the period when the servo strobe is asserted (time t2), it demodulates the signal read by read head 22r and provided by head IC24 into Gray code during the period T1 from time t2 to time t3. Period T1 is the known time required for read head 22 to pass through Gray code region GC1. Period T1 is pre-stored in RWC25 or in any storage device outside RWC25 in association with a normal servo sector NSV. When RWC25 is notified from processor 26 that the type of the servo sector SV being passed is a normal servo sector NSV, it determines the period T1 associated with the normal servo sector NSV and demodulates the signal obtained from time t2 until the period T1 has passed into Gray code.

[0128] After time t3, when the read head 22r reaches the end of the postcode region PC (time t4), HDC23 performs a cancel assertion on the servo strobe.

[0129] Figure 10 This is a schematic diagram illustrating an example of the servo gating waveform used in the ShortSG mode during the write operation of the first embodiment when the read / write head 22 passes through the Short Servo SSV.

[0130] When the read head 22r reaches the position after the write-read transition length W2R in the opposite direction of the write / read direction from the beginning position of the rear region Ras (time t10), HDC23 disables data writing by canceling the write strobe assertion.

[0131] When the read head 22r reaches the beginning of the back region Ras (time t11), HDC23 asserts the servo strobe.

[0132] When the read head 22r reaches the end of the region Ras, which is also the end of the append code region AC (time t12), HDC23 performs a cancel assertion on the servo strobe.

[0133] Because the servo gating configuration of mode ShortSG is such that the controller 30 does not acquire Gray code when the read / write head 22 passes through the short servo sector SSV during the write operation.

[0134] Figure 11 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG1 mode during the read operation of the first embodiment when the read head 22 passes through the normal servo sector NSV. Figure 11 The document describes the relationship between the position of the read head 22r and the read strobe state, as well as the servo strobe state.

[0135] Before the read head 22r reaches the immediately following demagnetized region DEG (time t20), HDC23 disables data reading by canceling the read strobe assertion.

[0136] When the read head 22r reaches the beginning of the preamble region PA1 (time t21), HDC23 asserts the servo gating.

[0137] When RWC25 detects a servo flag during the period when the servo strobe is asserted (time t22), it uses... Figure 9 Similarly, the actions described above will be performed by reading the signal from the read head 22r during the period T1 from time t22 to time t23 and interpreting it as Gray code for demodulation.

[0138] When the read head 22r reaches the end of the postcode region PC (time t24), HDC23 performs a cancel assertion on the servo strobe.

[0139] Therefore, when the read head 22 passes through the normal servo sector NSV during a read operation, the controller 30 obtains Gray code from the Gray code region GC1 in the same way as during a write operation.

[0140] Figure 12 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG2 mode during the read operation of the first embodiment when the read head 22 passes through the short servo sector SSV.

[0141] Before the read head 22r reaches the immediately following demagnetized region DEG (time t30), HDC23 disables data reading by canceling the read strobe assertion.

[0142] When the read head 22r reaches the beginning of the preamble region PA1 (time t31), HDC23 asserts the servo gating.

[0143] When RWC25 detects a servo flag during the period when the servo strobe is asserted (time t32), it reads the signal from read head 22r during the period T2 from time t32 to time t33 and interprets it as Gray code for demodulation. Period T2 is the known time required for read head 22 to pass through Gray code regions GC2 and GC1, and is longer than period T1. Period T2 is pre-stored in RWC25 or in any external storage device in association with short servo sectors (SSVs). When RWC25 is notified from processor 26 that the type of the servo sector SV being passed is a short servo sector (SSV), it determines period T2 as the period associated with the short servo sector (SSV) and demodulates the signal acquired from time t32 until the passage of period T2 into Gray code.

[0144] After time t33, when the read head 22r reaches the end of the back region Ras, which is also the end of the append code region AC (time t34), HDC23 performs a cancel assertion on the servo strobe.

[0145] Figure 13 This is a schematic diagram illustrating an example of the servo gating waveform used in the SeekSG1 mode during the seek operation of the first embodiment when the read / write head 22 passes through a normal servo sector NSV. Figure 13 The relationship between the position of the read head 22r and the state of the servo strobe is described in the text.

[0146] When the read head 22r reaches the beginning of the preamble region PA2 (time t40), HDC23 asserts the servo gating.

[0147] When the RWC25 detects a servo flag during the period when the servo strobe is asserted (time t41), it uses... Figure 9 Similarly, the operation described above will be performed by reading the signal from the read head 22r during the period T1 from time t41 to time t42 and interpreting it as Gray code for demodulation.

[0148] After time t42, when the read head 22r reaches the end of the postcode region PC (time t43), HDC23 performs a cancel assertion on the servo strobe.

[0149] Figure 14 This is a schematic diagram illustrating an example of the servo gating waveform used in the SeekSG2 mode during the seek operation of the first embodiment when the read / write head 22 passes through the short servo sector SSV.

[0150] When the read head 22r reaches the beginning of the preamble region PA2 (time t50), HDC23 asserts the servo gating.

[0151] When the RWC25 detects a servo flag during the period when the servo strobe is asserted (time t51), it uses... Figure 12 Similarly, the actions described above will be performed by reading the signal from the read head 22r during the period T2 from time t51 to time t52 and interpreting it as Gray code for demodulation.

[0152] After time t52, when the read head 22r reaches the end of the append code region AC (time t53), HDC23 performs a cancel assertion on the servo strobe.

[0153] Figure 15 This is a flowchart illustrating an example of the operation of the controller 30 in the first embodiment, which determines the demodulation method for the servo information of each servo sector SV. Furthermore, this is performed whenever the read / write head 22 passes through each servo sector SV. Figure 15 The series of actions shown.

[0154] First, the controller 30 (e.g., processor 26) determines whether the read / write head 22 is about to pass through a short servo sector (SSV) (S101). If the read / write head 22 is not about to pass through a short servo sector (SSV) but is about to pass through a normal servo sector (NSV) (S101: No), the controller 30 (e.g., processor 26) determines whether the type of the action being performed is a seek action (S102).

[0155] If the type of the action being executed is a seek action (S102: Yes), the controller 30 (e.g., HDC23) generates a servo strobe for the SeekSG1 pattern (S103). Then, the RWC25 obtains the Gray code from the Gray code region GC1 (S104). The action then ends.

[0156] If the type of action being performed is not a seek action but a tracking action, that is, an action that maintains the position of the read / write head 22 on the target track 41 for a write or read action (S102: No), the controller 30 (e.g., HDC23) generates a servo strobe for the NormalSG1 mode (S105). As a result, the RWC25 obtains the Gray code from the Gray code region GC1 (S104). Then, the action ends.

[0157] When the read / write head 22 is about to pass through the short servo sector (SSV) (S101: Yes), the controller 30 (e.g., processor 26) determines whether the type of the action being executed is a seek action (S106).

[0158] If the type of the action being executed is a seek action (S106: Yes), the controller 30 (e.g., HDC23) generates a servo strobe for the SeekSG2 pattern (S107). Then, RWC25 obtains the Gray code from the Gray code regions GC1 and GC2 (S108). The action then ends.

[0159] If the type of the action being executed is not a seek action but a trace action (S106: No), the controller 30 (e.g., the processor 26) determines whether the type of the action being executed is a write action (S109).

[0160] If the type of the action being executed is a read action instead of a write action (S109: No), the controller 30 (e.g., HDC23) generates a servo strobe for the NormalSG2 mode (S110). Then, RWC25 obtains the Gray code from the Gray code regions GC1 and GC2 (S108). The action then ends.

[0161] If the type of the action being performed is a write action (S109: Yes), the controller 30 (e.g., HDC23) generates a servo strobe for the ShortSG mode (S111). As a result, RWC25 does not acquire the Gray code (S112), and the action ends.

[0162] Thus, according to the first embodiment, each servo sector (SV) includes a front region (FA) and a rear region (RA) configured after the front region (FA). The front region (FA) is written with first information including a preamble, a servo flag, and Gray code, and the rear region (RA) is written with second information including a burst pattern. Furthermore, the circumferential length of the front region of each short servo sector (SSV) is longer than the circumferential length of the front region of each normal servo sector (NSV) by an amount corresponding to the addition of a Gray code region (GC2) to the front region of each short servo sector (SSV).

[0163] During the read operation, the controller 30 is able to obtain more information from the short servo sector (SSV) than the Gray code of the comparison example, thus improving read performance. In other words, performance is improved.

[0164] Furthermore, during seek operations, the controller 30 can obtain more information from the short servo sector (SSV) than the Gray code of the comparison example, thus reducing the frequency of seek errors. In other words, performance is improved.

[0165] Furthermore, according to the first embodiment, the length of the front region FAs of the short servo sector SSV is set based on the read / write gap length RWgap.

[0166] For example, the length L of the Gray code region GC2 can be determined by making the distance (P13-P10) equal to the distance (P12-P10) at the radius position where the read-write gap length RWgap is minimized. GC2 The length L of the Gray code region GC2 GC2 The length of the front region FAs is determined by equation (2). The length L of the Gray code region GC2 is thus determined. GC2 It can also be set to be common within disk 11.

[0167] Alternatively, the length L of the Gray code region GC2 can be determined such that the distance (P13-P10) at the radius where the read-write gap length RWgap is minimized is slightly larger than the distance (P12-P10). GC2 The length L of the Gray code region GC2 GC2 The length of the front region FAs is determined by equation (2). The length L of the Gray code region GC2 is thus determined. GC2 It can also be set to be common within disk 11.

[0168] Alternatively, the length L of the Gray code region GC2 in each track 41 can be determined in such a way that the distance (P13-P10) is equal to the distance (P12-P10) at any radius position. GC2 The length L of the Gray code region GC2 GC2 The length of the front region FAs in each track 41 is determined by formula (2).

[0169] Furthermore, according to the first embodiment, the Gray code written in the front region FAs of the short servo sector SSV includes the complete cylinder address, while the Gray code written in the front region FSn of the normal servo sector NSV includes a portion of the cylinder address.

[0170] Therefore, the controller 30 can obtain the complete cylinder address when the read head 22 passes through the short servo sector (SSV) during the read operation. Additionally, the controller 30 can obtain the complete cylinder address when the read head 22 passes through the short servo sector (SSV) during the seek operation.

[0171] Furthermore, in the first embodiment, the amount of Gray code information written in the front region FAs of the short servo sector SSV is greater than that in the comparative example. The type of servo information with greater information content than in the comparative example is not limited to Gray code.

[0172] For example, a preamble can be written in a longer region than the comparison example within the front region FAs of a short servo sector SSV, thus increasing the length of the front region FAs. By increasing the region where the preamble is obtained, the accuracy of the servo waveform sampling data input into the RWC25 is improved. As a result, positioning accuracy is improved, which means performance is improved.

[0173] Alternatively, a servo marker can be written in a longer region than the comparison example within the front region FAs of the short servo sector SSV. Correspondingly, the length of the front region FAs of the short servo sector SSV is increased. By increasing the region where the servo marker is obtained, the frequency of servo marker detection errors is improved. As a result, positioning accuracy is improved; that is, performance is improved.

[0174] Thus, the type of servo information with more information than the comparative example can be any type of preamble, servo tag, or Gray code. Alternatively, an area with arbitrary information different from the preamble, servo tag, and Gray code can be added to the front area FAs of the short servo sector SSV, thereby increasing the length of the front area FAs of the short servo sector SSV.

[0175] (Second Implementation)

[0176] In the second embodiment, the disk device is capable of simultaneously writing data using the write head and reading servo information in parallel with the data writing using the read head. This function of reading servo information in parallel with data writing is described as a servo read during write function. According to the servo read during write function, by eliminating noise from the signal from the read head caused by the data writing process, data writing and servo information reading can be performed simultaneously.

[0177] In disk devices equipped with write-on-servo read functionality, the length of the unwritable region UA ​​caused by the read / write gap length RWgap is suppressed. Therefore, in the second embodiment, all servo sectors (SVs) are essentially composed of normal servo sectors (NSVs). Furthermore, in the second embodiment, short servo sectors (SSVs) may also be provided on the disk.

[0178] From now on, the disk device of the second embodiment will be referred to as disk device 1a, the disk of the second embodiment will be referred to as disk 11a, and the controller of the second embodiment will be referred to as controller 30a. Furthermore, matters that differ from those of the first embodiment will be described, while matters that are the same as those of the first embodiment will be omitted from the description or described briefly.

[0179] Figure 16This is a schematic diagram illustrating an example of the configuration of disk 11a in the second embodiment. As shown in this figure, the difference between disk 11a and disk 11 in the first embodiment is that all of the multiple servo sectors SV are composed of ordinary servo sectors NSV.

[0180] Figure 17 This diagram illustrates an example of the configuration of a typical servo sector NSV according to the second embodiment. In this example, in the typical servo sector NSV, the preamble region PA2 (for writing preamble #2), the preamble region PA1 (for writing preamble #1), the servo tag region SM (for writing servo tags), the Gray code regions GC3 and GC1 (for writing Gray codes), the region PAD (for writing PAD), the pulse train region BN (for writing N pulse trains), the pulse train region BQ (for writing Q pulse trains), and the postcode region PC (for writing postcodes) are configured in this order along the write / read direction.

[0181] As mentioned above, in the disk device 1a with write-on-servo read capability, the length of the unwritable region UA ​​immediately preceding the servo sector SV, caused by the read-write gap length RWgap, is suppressed. However, sometimes it is not possible to completely eliminate the unwritable region UA ​​immediately preceding the servo sector SV.

[0182] In the second embodiment, the length of the region to be written in Gray code is increased from the length of Gray code region GC1 to the length of Gray code regions GC1 and GC3. Correspondingly with the increase in the length of the region to be written in Gray code, the length of the unwritable region UA ​​is further suppressed.

[0183] In addition, Figure 17 In the example shown, there is no writable region UA ​​immediately preceding the normal servo sector NSV. Alternatively, a writable region UA ​​of a certain length can be left preceding the normal servo sector NSV.

[0184] Figure 18 This is a schematic diagram used to illustrate the Gray code written in the Gray code regions GC1 and GC3 of the second embodiment.

[0185] exist Figure 18 In the example shown, Gray code with the same structure as the normal servo sector NSV in the first embodiment is written in the Gray code region GC1.

[0186] Therefore, when only the Gray code region GC1 is considered, the complete Gray code is scattered across three normal servo sectors (NSVs). To obtain the complete sector address and the complete cylinder address, the controller 30 needs to demodulate the Gray code from the three consecutively configured normal servo sectors (NSVs).

[0187] The lower two bits of the complete cylinder address, namely bits C1 and C2, are written in the Gray code region GC3.

[0188] Therefore, the complete cylinder address can be obtained from one of the three consecutively configured normal service sectors (NSVs). Additionally, the portion of the complete cylinder address, excluding the most significant bit, can be obtained from the other two of the three normal service sectors (NSVs).

[0189] That is, in the second embodiment, by setting a Gray code region GC3 in the normal servo sector NSV based on the Gray code region GC1, the amount of Gray code information obtained from the normal servo sector NSV is increased.

[0190] In controller 30a, processor 26 notifies HDC23 and RWC25 of the type of action being performed when read / write head 22 passes through a servo sector SV (i.e., a typical servo sector NSV). HDC23 generates either of two servo strobe modes based on the notified type of action being performed. RWC25 controls write strobe, read strobe, and servo strobe based on the servo strobe and the notified type of action being performed.

[0191] Figure 19 This is a schematic diagram used to explain the relationship between the type of action and the servo gating mode used in the execution of the second embodiment.

[0192] During write and read operations, when the read / write head 22 passes through the normal servo sector NSV, the servo gating of the waveform in NormalSG3 mode is used. During seek operations, when the read / write head 22 passes through the normal servo sector NSV, the servo gating of the SeekSG3 mode is used.

[0193] Figure 20 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG3 mode during the write operation of the second embodiment when the read / write head 22 passes through a normal servo sector NSV. Figure 20 The text depicts the temporal shift of the position of the read head 22r in the circumferential direction. It also describes the relationship between the position of the read head 22r and the states of the write strobe and the servo strobe.

[0194] When the read head 22r reaches the beginning of the preamble region PA1 (time t60), HDC23 asserts the servo gating. Then, RWC25 begins demodulation of the servo information.

[0195] Furthermore, at time t60, the write strobe is maintained in the asserted state. Thus, while continuously writing data using write head 22w, the RWC25 begins demodulating servo information using read head 22r.

[0196] When RWC25 detects a servo flag during the period when the servo gating is asserted (time t61), it determines the timing (time t63) at which the read head 22r arrives at the beginning of the Gray code region GC1 based on the elapsed time from time t61. Furthermore, RWC25 demodulates the signal read by the read head 22r and provided by the head IC24 as Gray code during the period T1 from time t63 to time t64. Period T1 is the known time required for the read head 22 to pass through the Gray code region GC1. Period T1 is pre-stored in RWC25 or in any storage device outside of RWC25 in association with a write operation. When RWC25 is notified that the type of the operation being performed is a write operation, it determines the period T1 and time t63 as the period associated with the write operation, and considers the period T1 from time t63 as the period for acquiring Gray code.

[0197] When the read head 22r reaches the position after the write-read transition length W2R in the opposite direction of the write / read direction from the beginning position of the Gray code region GC1 (time t62), HDC23 disables data writing by canceling the write strobe assertion.

[0198] As mentioned above, by eliminating the noise from the signal from the read head 22r caused by the data writing of the write head 22w, the write of data and the reading of servo information can be performed simultaneously, according to the write-while-read function.

[0199] Preamble #1, preamble #2, and servo flags have a positional structure independent of the radial direction; therefore, noise removal from the read preamble #1, preamble #2, and servo flags is relatively easy. However, Gray code written into the Gray code region GC1, if used... Figure 18 As explained, this includes cylinder addresses. That is, the Gray code written to the Gray code region GC1 has a positional structure dependent on the radial direction. Therefore, removing noise from the Gray code read from the Gray code region GC1 is relatively difficult.

[0200] The use of write header 22w is stopped before it reaches the Gray code region GC1, so that the Gray code can be obtained from the Gray code region GC1 with as few errors as possible. Therefore, the write strobe is canceled as the read header 22r backtracks from the beginning of the Gray code region GC1 to the position of the write-read transition length W2R.

[0201] After time t64, when the read head 22r reaches the end of the postcode region PC (time t65), HDC23 performs a cancel assertion on the servo strobe.

[0202] Figure 21 This is a schematic diagram illustrating an example of the servo gating waveform used in the NormalSG3 mode during the read operation of the second embodiment when the read head 22 passes through the normal servo sector NSV. Figure 21 The relationship between the position of the read head 22r and the read gating state and the servo gating state is described.

[0203] Before the read head 22r reaches the immediately following demagnetization region DEG (time t70), HDC23 disables data reading by canceling the read strobe assertion.

[0204] When the read head 22r reaches the beginning of the preamble region PA1 (time t71), HDC23 asserts the servo gating.

[0205] When RWC25 detects a servo flag during the period when the servo gating is asserted (time t72), it will read the signal from read head 22r during the period T3 from time t72 to time t73 and interpret it as Gray code for demodulation. Period T3 is the known time required for read head 22 to pass through Gray code regions GC1 and GC3. Period T3 is longer than period T1. Period T3 is pre-stored in association with both read and seek operations in any storage device within or outside RWC25. When RWC25 is notified that the type of operation being performed is a read operation, it determines period T3 as the period associated with the read operation, and considers the period T3 from time t73 onwards as the period for acquiring Gray code.

[0206] After time t73, when the read head 22r reaches the end of the postcode region PC (time t74), HDC23 performs a cancel assertion on the servo strobe.

[0207] Therefore, when the read head 22 passes through the normal servo sector NSV during the reading operation, the controller 30a obtains Gray code from the Gray code regions GC1 and GC3.

[0208] Figure 22 This is a schematic diagram illustrating an example of the servo gating waveform used in the SeekSG3 mode during the seek operation of the second embodiment when the read / write head 22 passes through a normal servo sector NSV. Figure 22 The relationship between the position of the read head 22r and the state of the servo strobe is described in the text.

[0209] When the read head 22r reaches the beginning of the preamble region PA2 (time t80), HDC23 asserts the servo strobe.

[0210] When RWC25 detects a servo flag during the period when the servo strobe is asserted (time t81), it will read the signal from read head 22r during the period T3 from time t81 to time t82 and interpret it as Gray code for demodulation. That is, when RWC25 is notified that the type of the action being performed is a seek action, it determines the period T3 as the period associated with the seek action and regards the period T3 from time t81 as the period for acquiring Gray code.

[0211] After time t82, when the read head 22r reaches the end of the postcode region PC (time t83), HDC23 performs a cancel assertion on the servo strobe.

[0212] Therefore, when the read / write head 22 passes through the normal servo sector NSV during the seek operation, the controller 30a obtains Gray code from the Gray code regions GC1 and GC3.

[0213] Figure 23 This is a flowchart illustrating an example of the operation of the controller 30a in the second embodiment, which determines the demodulation method for the servo information of each servo sector SV. Furthermore, this is performed whenever the read / write head 22 passes through each servo sector SV. Figure 23 The series of actions shown.

[0214] First, the controller 30a (e.g., processor 26) determines whether the type of the action being executed is a seek action (S201).

[0215] If the type of the action being executed is a seek action (S201: Yes), the controller 30a (e.g., HDC23) generates a servo strobe for the SeekSG3 mode (S202). Then, RWC25 obtains the Gray code from the Gray code regions GC1 and GC3 (S203). The action then ends.

[0216] If the type of the action being executed is not a seek action (S201: No), the controller 30a (e.g., processor 26) determines whether the type of the action being executed is a write action (S204).

[0217] If the type of action being performed is a read action rather than a write action (S204: No), the controller 30a (e.g., HDC23) generates a servo strobe for the NormalSG3 mode during the read action (S205). As a result, RWC25 obtains the Gray code from the Gray code regions GC1 and GC3 (S203). Then, the action ends.

[0218] If the type of the action being performed is a write action (S204: Yes), the controller 30a (e.g., HDC23) generates a servo strobe for the NormalSG3 mode during the write action (S206). As a result, RWC25 obtains the Gray code from the Gray code region GC1 (S207). Then, the action ends.

[0219] Thus, in the disk device 1a with write-on-servo read capability, a Gray code region GC3 is set in the normal servo sector NSV based on the Gray code region GC1. As a result, the amount of Gray code information obtained from the normal servo sector NSV during seek and read operations is increased.

[0220] For example, in passing Figure 18 The method shown, when Gray code is written to Gray code regions GC1 and GC3, allows the complete cylinder address to be obtained simply by the read / write head 22 passing through a specific servo sector SV. This improves read performance and reduces the frequency of seek errors, resulting in performance enhancement.

[0221] Furthermore, the type of servo information with increased information content can also be any type of preamble, servo flag, or Gray code, just like in the first embodiment. Alternatively, an area can be added to the front region FA containing arbitrary information that is different from the preamble, servo flag, and Gray code, thereby suppressing the length of the write-prohibited region UA.

[0222] Several embodiments of the present invention have been described above, but these embodiments are merely illustrative and not intended to limit the scope of the invention. These new embodiments can be implemented in a wide variety of other ways, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and / or variations thereof are included within the scope and spirit of the invention, and are included within the scope of the invention as described in the claims and its equivalents.

Claims

1. A disk drive comprising a disk, read / write heads, and a controller. The disk is configured with a plurality of first servo sectors spaced out in a circumferential direction. Each first servo sector has multiple data regions disposed between adjacent first servo sectors along the circumferential direction. Each first servo sector includes a first region and a second region. The first region is written with first information including a preamble, servo flag, and Gray code. The second region is disposed behind the first region in the write / read direction along the circumferential direction and is written with second information including a burst pattern. The plurality of first servo sectors includes a plurality of second servo sectors and a plurality of third servo sectors. One or more third servo sectors are disposed between adjacent second servo sectors. The circumferential length of the first region in each of the plurality of third servo sectors is longer than the circumferential length of the first region in each of the plurality of second servo sectors. During the write operation where the controller uses the magnetic head to write data to one or more of the plurality of data areas, when the magnetic head passes through one of the plurality of second servo sectors, the first information and the second information are demodulated; when the magnetic head passes through one of the plurality of third servo sectors, the first information is not demodulated, but the second information is demodulated. In the reading operation of the controller using the magnetic head to read data from one or more of the plurality of data areas, when the magnetic head passes through one of the plurality of second servo sectors, the first information and the second information are demodulated; when the magnetic head passes through one of the plurality of third servo sectors, the first information and the second information are demodulated.

2. The disk drive according to claim 1, During the seek operation in which the read / write head moves in the radial direction of the disk, the controller demodulates the first information and the second information when the read / write head passes through one of the plurality of second servo sectors, and demodulates the first information and the second information when the read / write head passes through one of the plurality of third servo sectors.

3. The disk drive according to claim 1 or 2, The amount of Gray code information written in the first region of each of the plurality of third servo sectors is greater than the amount of Gray code information written in the first region of each of the plurality of second servo sectors.

4. The disk drive according to claim 1 or 2, The magnetic head has a read head and a write head. The write head moves relative to the disk in the circumferential direction, lagging behind the read head by a first gap. The length of the first region in the circumferential direction of each of the plurality of third servo sectors is set based on the first gap.

5. The disk drive according to claim 1 or 2, The magnetic head has a read head and a write head. The write head moves relative to the disk in the circumferential direction, lagging behind the read head by a first gap. The first gap varies depending on the radius of the disk. The length of the first region in the circumferential direction of each of the plurality of third servo sectors is set based on the minimum value of the first gap.

6. The disk drive according to claim 1 or 2, The Gray code written in the first region of each of the plurality of third servo sectors includes a complete cylinder address. The Gray code written in the first region of each of the plurality of second servo sectors includes a portion of the cylinder address.

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