Magnetic disk device

Abstract

The present disclosure provides a magnetic disk device capable of improving write performance. According to an embodiment, the magnetic disk device includes a magnetic disk, a head that writes data to a track of the magnetic disk, and a controller that performs positioning of the head, registers an address of a sector to which the data is written and a positioning error of the head at the address, judges whether or not a positioning error of a second sector that is two tracks ahead of a first sector to which the data is to be written is registered, sets a first threshold value that allows a write operation with respect to the positioning error of the first sector based on the positioning error of the second sector in a case where the positioning error of the second sector is registered, judges whether or not the positioning error of the first sector exceeds the first threshold value, and stops the write operation in a case where the positioning error of the first sector exceeds the first threshold value.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2022-030916 (filing date: March 1, 2022) and Japanese Patent Application No. 2022-116443 (filing date: July 21, 2022), the entire contents of which are incorporated herein by reference. Technical Field

[0002] An embodiment of the present invention relates to a magnetic disk device. Background Art

[0003] The magnetic disk device includes a magnetic disk (hereinafter also referred to as a disk), a magnetic reproducing head (hereinafter also referred to as a head) for writing data on the disk, a system controller (hereinafter also referred to as a controller), and the like.

[0004] The controller carries out the positioning control (hereinafter, also referred to as " positioning ") of the head with respect to a plurality of magnetic tracks that are formed roughly concentrically on disk. For the head, there is the situation that the track is positioned relative to the radial direction off-track (off-track, deviating from the track) of the disk. If the off-track amount is large, the danger of erasing the data recorded in the adjacent magnetic track rises, so the controller is provided with a certain static threshold value to the off-track amount, stops writing when the off-track amount has exceeded the above-mentioned threshold value. In order to quantify the danger of data erasure, the narrow track width amount of definition allowable read error rate is referred to as TPI margin (margin).

[0005] Because of the large capacity of magnetic disk device, the track spacing of adjacent tracks is reduced. Thereby, TPI margin also reduces in linkage, and the off-track amount can become easy to exceed threshold value, and write error occurs frequently, and the overhead (overhead) that causes because of retry action and the problem that write performance reduces occur. Summary of the Invention

[0006] This embodiment provides a magnetic disk device that can improve write performance by suppressing write errors and retry operations caused by the amount of off-track exceeding a threshold.

[0007] A magnetic disk device in one embodiment comprises: a magnetic disk; a magnetic head positioned at a track of the magnetic disk having a predetermined track pitch, for writing data to the track of the magnetic disk and reading data from the track of the magnetic disk; and a controller for positioning the magnetic head, registering the address of the sector of the track where the data is written and the positioning error of the head relative to the track at the address, the controller determining whether the positioning error of the second sector two tracks forward in the radial direction of the first sector where the data is to be written is registered, and if the positioning error of the second sector is registered, setting a first threshold value for allowing a write action with respect to the positioning error of the first sector based on the positioning error of the second sector, determining whether the positioning error of the first sector exceeds the first threshold value, and stopping the write action if the positioning error of the first sector exceeds the first threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0008] Figure 1 This is a block diagram showing the configuration of a magnetic disk device according to one embodiment.

[0009] Figure 2 This is a diagram showing an example of basic write processing of a magnetic disk device.

[0010] Figure 3 This is a diagram showing an example of a write process of the magnetic disk device according to the above embodiment.

[0011] Figure 4 This is a diagram showing an example of a write process of the magnetic disk device according to the above embodiment.

[0012] Figure 5 This is a diagram showing an example of a write process of the magnetic disk device according to the above embodiment.

[0013] Figure 6 This is a diagram showing an example of a write process of the magnetic disk device according to the above embodiment.

[0014] Figure 7 This is a diagram showing an example of a write process of the magnetic disk device according to the above embodiment.

[0015] Figure 8 This is a block diagram showing an example of a control configuration of the magnetic disk device according to the above embodiment.

[0016] Figure 9 This is a block diagram showing a compression processing circuit according to the above embodiment.

[0017] Figure 10 This is a block diagram showing an example of a control configuration of the magnetic disk device according to the above embodiment.

[0018] Figure 11 This is a flowchart showing the write process of the magnetic disk device according to the above embodiment.

[0019] Figure 12 is a flowchart showing the write processing of the disk device of the above embodiment. Figure 11

[0020] Figure 13 is a flowchart showing the write processing of the disk device of the above embodiment. Figure 12

[0021] Figure 14 is a flowchart showing the write processing of the disk device of the above embodiment. Figure 12

[0022] Figure 15 is a flowchart showing the write processing of the disk device of the above embodiment. Figure 13 Figure 14

[0023] Figure 16 is a diagram showing an example of an offtrack write table of the disk device of the above embodiment.

[0024] Figure 17 is a flowchart showing the write processing of the disk device of the above embodiment. Figure 13 Figure 14

[0025] Figure 18 is a diagram showing the effects of the disk device of the above embodiment.

[0026] Figure 19 is a block diagram showing a compaction processing circuit of a disk device of another embodiment.

[0027] Figure 20 is a flowchart showing the write processing of the disk device of another embodiment.

[0028] Figure 21 is a block diagram showing a compaction processing circuit in a modification example of the disk device of another embodiment.

[0029] Figure 22 is a flowchart showing the write processing in a modification example of the disk device of another embodiment.

[0030] Explanation of Reference Numerals

[0031] ​​​​​​​1…disk drive, 10…disk, 15…head, 15W…write head, 130…system controller, 610…write control unit, 611…off-track write table, 612…compression processing circuit, 613…OR gate, 617…absolute value circuit, 618…AND gate, 619…OWT reference update block, GAIN…gain, predetermined amount…G0, PEO, PEI…positioning error, Tr-2, Tr-1, Tr0, Tr1, Tr2…tracks, WOS1, WOS12, WOS13…first threshold, WOS2…second threshold, WOS3…third threshold DETAILED DESCRIPTION

[0032] Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the accompanying drawings are merely examples and do not limit the scope of the invention.

[0033] Figure 1 This is a block diagram showing the configuration of the magnetic disk device 1 according to the embodiment.

[0034] The magnetic disk drive 1 includes a head disk assembly (HDA) (described later), a driver IC 20, a head amplifier integrated circuit (hereinafter sometimes referred to as a head amplifier IC or preamplifier) ​​30, a volatile memory 70, a nonvolatile memory 80, a buffer memory (cache) 90, and a system controller 130, which is a single-chip integrated circuit. The magnetic disk drive 1 is connected to a host system (host) 100.

[0035] The HDA includes a magnetic disk (hereinafter referred to as a disk) 10, a spindle motor (SPM) 12, an arm 13 carrying a magnetic head 15, and a voice coil motor (VCM) 14. The disk 10 is mounted on the spindle motor 12 and rotated by the spindle motor 12. The arm 13 and the voice coil motor 14 constitute an actuator. The actuator controls the movement of the magnetic head 15 mounted on the arm 13 to a predetermined position on the disk 10 by the drive of the voice coil motor 14. Two or more disks 10 and magnetic heads 15 may be provided.

[0036] Hereinafter, data written to various components of the magnetic disk device 1 and external devices, such as the disk 10, may be referred to as "write data," and data read from various components of the magnetic disk device 1 and external devices, such as the disk 10, may be referred to as "read data." Write data may be simply referred to as "data," read data may be simply referred to as "data," and both write data and read data may be collectively referred to as "data."

[0037] In the disc 10, as an area in which data can be written, a user data area 10a that can be used by a user, a media cache area 10b in which data (or a command) transferred from the host 100 or the like is temporarily held until written to a predetermined area of the user data area 10a, and a system area 10c in which information required for system management is recorded are allocated. Hereinafter, a direction orthogonal to the radial direction of the disc 10 will be referred to as the circumferential direction. Further, the media cache area 10b can not be allocated, and the system area 10c can be allocated to the nonvolatile memory 80 or the like.

[0038] The head (hereinafter, also referred to as a "slider") 15 has a slider as a main body, and has a write head 15W and a read head 15R mounted to the slider. The write head 15W writes data to a track of the disc 10. The read head 15R reads data recorded in a track of the disc 10. Further, there are cases in which the write head 15W is simply referred to as the head 15, cases in which the read head 15R is simply referred to as the head 15, and cases in which the write head 15W and the read head 15R are collectively referred to as the head 15. The "track" is used in the meaning of one of a plurality of areas distinguished in the radial direction of the disc 10, one of a plurality of areas distinguished in the circumferential direction of the disc 10, data written to a predetermined position of the disc 10, data written to a sector, and other various meanings. In addition, the width in the radial direction of the track is referred to as the track width, and the center position of the track width is referred to as the track center.

[0039] The driver IC 20 controls driving of the spindle motor 12 and the VCM 14 in accordance with the control of the system controller 130 (in detail, the MPU 60 described later).

[0040] The head amplifier IC (a preamplifier) 30 has a read amplifier and a write driver. The read amplifier amplifies a read signal read from the disc 10 by the read head 15R, and outputs the read signal to the system controller 130 (in detail, a read / write (R / W) channel 40 described later). The write driver outputs a write current corresponding to a signal output from the R / W channel 40 to the write head 15W.

[0041] The volatile memory 70 is a semiconductor memory in which data held when power supply is cut off is lost. The volatile memory 70 stores data and the like required for processing in each part of the disc device 1. The volatile memory 70 is, for example, a DRAM (Dynamic Random Access Memory) or a SDRAM (Synchronous Dynamic Random Access Memory).

[0042] The nonvolatile memory 80 is a semiconductor memory that records stored data even when power is cut off. The nonvolatile memory 80 is, for example, a NOR-type or NAND-type flash ROM (Flash Read Only Memory: FROM).

[0043] The buffer memory 90 is a semiconductor memory that temporarily stores data exchanged between the magnetic disk device 1 and the host computer 100. Alternatively, the buffer memory 90 may be integrated with the volatile memory 70. Examples of the buffer memory 90 include DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), and MRAM (Magnetoresistive Random Access Memory).

[0044] The system controller (controller) 130 is implemented, for example, using a large-scale integrated circuit (LSI) called a system-on-a-chip (SoC), in which multiple components are integrated into a single chip. The system controller 130 includes a read / write (R / W) channel 40, a hard disk controller (HDC) 50, and a microprocessor (MPU) 60. The system controller 130 is electrically connected to the driver IC 20, the head amplifier IC 30, the volatile memory 70, the nonvolatile memory 80, the buffer memory 90, and the host system 100.

[0045] The R / W channel 40 performs signal processing for read data transferred from the disk 10 to the host 100 and write data transferred from the host system 100, based on instructions from the MPU 60 described later. The R / W channel 40 includes circuitry or functionality for measuring the signal quality of read data. The R / W channel 40 is electrically connected to, for example, a head amplifier IC, the HDC 50, and the MPU 60.

[0046] The HDC 50 controls data transfer between the host system 100 and the R / W channel 40 according to instructions from the MPU 60 described later. The HDC 50 is electrically connected to the R / W channel 40, the MPU 60, the volatile memory 70, the nonvolatile memory 80, and the buffer memory 90, for example.

[0047] The MPU 60 is the main controller that controls various components of the magnetic disk drive 1. The MPU 60 controls the VCM 14 via the driver IC 20, performing servo control to position the head 15. Furthermore, the MPU 60 controls the SPM 12 via the driver IC 20 to rotate the disk 10. The MPU 60 controls writing data to the disk 10 and selects where to save the written data. Furthermore, the MPU 60 controls reading data from the disk 10 and controls the processing of read data. The MPU 60 is connected to various components of the magnetic disk drive 1. For example, the MPU 60 is electrically connected to the driver IC 20, the R / W channel 40, and the HDC 50.

[0048] The MPU 60 includes a write control unit 610 that controls write processing and a read control unit 620 that controls read processing. The MPU 60 executes the processing of each of these units, such as the write control unit 610 and the read control unit 620, in firmware. Alternatively, the MPU 60 may include each of these units, such as the write control unit 610 and the read control unit 620, as circuits.

[0049] The write control unit 610 controls the data writing process according to the command from the host 100, etc. The write control unit 610 controls the VCM 14 via the driver IC 20 to configure the head 15 at a predetermined position on the disk 10 to write data. Hereinafter, there may be cases where "positioning the center of the head 15 (write head 15W or read head 15R) at a predetermined position" or "configuring the center of the head 15 (write head 15W or read head 15R) at a predetermined position" is simply referred to as "positioning the head 15 (write head 15W or read head 15R) at a predetermined position" or "configuring the head 15 (write head 15W or read head 15R) at a predetermined position." In addition, there may be cases where "positioning the head 15 (write head 15W or read head 15R) at a predetermined position" or "configuring the head 15 (write head 15W or read head 15R) at a predetermined position" is simply referred to as "positioning" or "configuring."

[0050] The write control unit 610 positions the head 15 (write head 15W) at a position that is a target for the write process (hereinafter, also referred to as the target position or target write position) and writes data. The write control unit 610 positions the head 15 at the target write position and performs random writing. In other words, the write control unit 610 positions the head 15 at a radial position that is a target for the write process (hereinafter, also referred to as the target radial position or target write radial position) at a predetermined circumferential position and writes data randomly. For example, the write control unit 610 controls the head 15 so that it is positioned at the target write radial position at a predetermined circumferential position and randomly writes data to a predetermined sector.

[0051] The write control unit 610 can control the head 15 to be positioned at the target write position and to randomly write data to a predetermined position (hereinafter also referred to as the actual position or the actual write position). The actual write position can be the target write position or a position offset from the target write position.

[0052] Hereinafter, “the center portion of the write head 15W deviates in the radial direction from a predetermined target write position” may also be described as “the write head 15W deviates from a predetermined track”.

[0053] In addition, the write control unit 610 has Figure 8 The write processing circuit C1 will be described later in the description of . In addition, the write processing circuit C1 may be provided outside the write control unit 610 .

[0054] The read control unit 620 controls data reading according to commands from the host 100, etc. The read control unit 620 controls the VCM 14 via the driver IC 20 to position the head 15 at a predetermined position on the disk 10 to read data. The read control unit 620 can read data either randomly or sequentially.

[0055] The read control unit 620 positions the head 15 (read head 15R) at the target read position to read data. The read control unit 620 positions the head 15 at the target read position to perform reading. In other words, the read control unit 620 controls the head 15 so that it is positioned at the target read radius at a predetermined circumferential position to read data. For example, the read control unit 620 controls the head 15 so that it is positioned at the target read radius at a predetermined circumferential position to read a predetermined sector. Alternatively, the read control unit 620 can control the head 15 along the target read path to read a predetermined track.

[0056] Here, the basic concept of the embodiment will be described.

[0057] The head (magnetic recording and playback head) 15 of the magnetic disk device 1 is controlled in radial position by an actuator including a VCM 14 so that it stays on the track formed in the circumferential direction of the magnetic disk 10. The above control is also called positioning control. When vibration, impact, etc. are applied from the outside to the magnetic disk device 1 equipped with the actuator including the head and the magnetic disk 10, the head 15 sometimes writes to an actual position that is offset from the target position. In order to prevent the occurrence of the above offset, a feedback loop is used in the magnetic disk device 1 to perform positioning control on the head 15. Hereinafter, the offset between the target position and the actual position is also referred to as positioning error.

[0058] If the positioning error caused by the positioning control is large, the danger of erasing the data in adjacent magnetic tracks will rise. Therefore, there is following function: the positioning error is set to a threshold value (WOS:Write Offtrack Slice), when having exceeded this threshold value, the write operation is stopped to prevent the erasing of the data in adjacent magnetic tracks. The above-mentioned threshold value is also referred to as the write off-track threshold value below.

[0059] Hereinafter, the writing process will be described with reference to the drawings.

[0060] Figure 2 1 is a diagram showing an example of basic write processing of the magnetic disk device 1. Figure 2 In the figure, the upper part shows an example of a case where data is written in the order of track Tr1, track Tr0, and track Tr2 in three consecutive tracks arranged in the order of track Tr0, track Tr1, and track Tr2 from the outer circumference along the radial direction. The lower part shows an example of a case where the track width TW of the data area D1 of the data recorded in track Tr1 becomes the read limit track width TW0. Figures 2 to 7 In FIG. 1 , a data area where the track width TW to be protected becomes data such as the read limit track width TW0 is indicated by a dotted line.

[0061] like Figure 2 As shown in the upper section of , each data area of ​​the data written to track Tr0, track Tr1 and track Tr2 has a write width WW. The data recorded in track Tr0 is written in a staggered manner (hereinafter, staggering is also referred to as "deviation") toward track Tr1. In detail, the data area D0 of the data written to track Tr0 is located at a position that deviates from the track center TC0 of track Tr0 toward the inner circumference direction by an error (hereinafter, also referred to as positioning error, deviation amount or off-track amount) PEI.

[0062] The data that are recorded in track Tr2 deviate toward track Tr1 and write. Specifically, the data area D2 that is recorded in the data of track Tr2 is positioned at the position that has deviated from error (hereinafter, also referred to as positioning error, deviation amount or off-track amount) PEO from the track center TC2 of track Tr2 toward peripheral direction.

[0063] After data is written to each track as described above, the data area D1 in the data recorded in track Tr1 has a track width TW. If the track width TW is expressed using the write width WW, the track pitch TP, the error PEI, and the error PEO, it can be expressed as the following equation (1). Here, TW represents the track width, WW represents the write width, TP represents the track pitch, and PEI and PEO represent the errors.

[0064] TW=2TP-WW-(PEO+PEI)…(1)

[0065] If the track width of the data area becomes smaller than the read limit track width, data cannot be read. Specifically, when the track width TW becomes smaller than the read limit track width TW0 described in the lower section, data recorded in the data area D1 cannot be read. To prevent this, when writing data, a limit is placed on the total amount of deviation from each track adjacent to track Tr1 (track Tr0 and track Tr2). Based on equation (1), the sum of the error PEO and the error PEI can be expressed using the following equation.

[0066] PEO+PEI=2TP-WW-TW

[0067] Here, considering that the track pitch TP is narrowed and the track width of track Tr1 is reduced, thus reaching the read limit, the value obtained by subtracting the write width and the read limit track width TW0 from twice the track pitch TP can be defined as the TPI (Track Per Inch) margin (also called the track squeeze margin) TM. The condition that the sum of the error PEO and the error PEI should satisfy can be expressed by the following formula (2). In addition, TW0 represents the read limit track width, and TM represents the TPI margin.

[0068] PEO+PEI≤2TP-WW-TW0=TM…(2)

[0069] As the sufficient condition that is used to make the total of error PEI and error PEO satisfy formula (2), restriction was set to each off-track amount PEI, PEO in the past. Specifically, off-track amount PEO is below half of the TPI margin TM and off-track amount PEI is below half of the TPI margin TM. That is to say, half of the TPI margin TM is made as the threshold value of off-track amount PEI and off-track amount PEO.

[0070] When the track pitch TP is reduced in order to increase the capacity of the magnetic disk device 1, as shown in formula (1), the TPI margin TM is also reduced in conjunction, so the track deviation amounts PEO and PEI become more likely to exceed the threshold, write errors occur frequently, and the write performance is reduced due to the overhead caused by the retry action.

[0071] In a magnetic disk device 1 of SMR (slotted magnetic recording method), in order to address this problem, the following technology is disclosed: by pre-recording the positioning error during sequential write, when adjacent tracks are written, the write off-track threshold is dynamically set with reference to the positioning error, thereby preventing the reduction of write performance. However, this previous technology is based on the premise that SMR performs sequential write operations, and utilizes the positioning error before preserving one track with a small storage capacity. Therefore, for random write operations, this technology cannot be directly applied.

[0072] So, in embodiments of the present invention, provide and can obtain the magnetic disk that can suppress the reduction of write performance by also dynamically setting the write skew threshold value for random write.And, also can obtain the magnetic disk of high track density when guaranteeing to read quality.

[0073] Hereinafter, the write process of this embodiment will be described with reference to the drawings.

[0074] Figure 3 This is a diagram showing an example of the write process of the magnetic disk device 1 according to the above embodiment. Figure 3 The data is written in the order of track Tr1, track Tr2, and track Tr0. Figure 3 Shown, data area D2 is positioned at the position that has deviated from off-track amount PEO.When the off-track amount PEO of data area D2 is known, the 1st threshold value (also referred to as the 1st off-track threshold value) WOS1 when deciding to track Tr0 write data afterwards.That is to say, also can be decided when the off-track amount PEO of known data area D2 is written to track Tr0 the 1st threshold value WOS1.The 1st threshold value WOS1 is the threshold value that is used to decide whether to allow write action when track Tr0 write data.

[0075] The first threshold WOS1 is a value obtained by subtracting the offset amount PEO of the data area D2 from the TPI margin TM, and can be expressed by the following formula (3): WOS1 is the first threshold.

[0076] WOS1=TM-PEO…(3)

[0077] The amount of off-track movement PEI by which the data area D0 can deviate is limited by the first threshold WOS1 , and therefore the relationship between the amount of off-track movement PEI and the first threshold WOS1 is expressed by the following equation.

[0078] PEI≤WOS1=TM-PEO

[0079] If the above equation is expressed using the off-track amounts PEO and PEI and the TPI margin TM, the following equation is obtained.

[0080] PEI+PEO≤TM

[0081] According to the above formula, the TPI margin TM is set to a value greater than the sum of the off-track amount PEI in the track Tr2 and the off-track amount PEO in the track Tr0.

[0082] According to the above formula (PEI+PEO≤TM), formula (1), and formula (2), the following formula holds.

[0083] TW≥2TP-WW-TM=TW0

[0084] That is to say, by setting the first threshold value WOS1 to the value obtained by subtracting the off-track amount PEO of the data area from the TPI margin TM as shown in formula (3), the track width TW for reading the data written to the track Tr1 can be ensured. In other words, the reading quality of the data written to the track Tr1 can be guaranteed.

[0085] The first threshold WOS1 can also be determined when data is written in the order of track Tr1, track Tr0, and track Tr2. Figure 4 , the determination of the first threshold value WOS1 when data is written as described above will be described.

[0086] Figure 4 This is a diagram showing an example of the write process of the magnetic disk device 1 according to the above embodiment. Figure 4 The data is written in the order of track Tr1, track Tr0, and track Tr2. Figure 4 As shown, data area D0 is located at a position that has deviated from the off-track amount PEI. When the off-track amount PEI of data area D0 is known, Figure 3 Similarly, the first threshold value WOS1 when writing data to track Tr2 is determined later. That is, when the off-track amount PEI of the data area D0 is known, the first threshold value WOS1 when writing to track Tr2 can also be determined. The first threshold value WOS1 is a threshold value used to determine whether a write operation is allowed when writing data to track Tr2.

[0087] The first threshold WOS1 is a value obtained by subtracting the offset PEI of the data area D0 from the TPI margin TM, and can be expressed by the following formula (4).

[0088] WOS1=TM-PEI…(4)

[0089] By setting the first threshold WOS1 to the value obtained by subtracting the off-track amount PEI of the data area D0 from the TPI margin TM as in formula (4), Figure 3 Similarly to the description above, the track width TW for reading the data written to the track Tr1 can be ensured.

[0090] Below, using Figure 5 and Figure 6 The case where data is written in the order of track Tr1, track Tr2, and track Tr0 is described, but the same consideration can be given to the case where data is written in the order of track Tr1, track Tr0, and track Tr2.

[0091] exist Figure 3In the description of the above embodiment, the off-track amount PEI of the track TrO is limited to the first threshold WOSI determined from the off-track amount PEO of the data area D2 of the data written to the track Tr2 (refer to Equation (3)), but when the off-track amount PEO is a very large value, the off-track amount PEI is significantly limited by the first threshold WOSI, and in order to prevent a decrease in the write performance in the track TrO, it is also possible to further limit by a third threshold WOS3 independent of the position error at the time of writing. The third threshold WOS3 is a static threshold. Refer to Figure 5 The write processing with the third threshold WOS3 set will be described.

[0092] Figure 5 is a diagram showing an example of the write processing of the disk device 1 of the above embodiment. As shown in Figure 5 , the off-track amount PEI of the data area DO of the data written to the track TrO is limited by a predetermined third threshold WOS3 independent of the off-track amount PEO of the data area D2 of the data written first to the track Tr2. On the other hand, the off-track amount PEO of the data area D2 is also limited by the predetermined third threshold WOS3.

[0093] The range in which the third threshold WOS3 can be set will be described below.

[0094] Since the off-track amount PEO is limited by the third threshold WOS3, the relationship of the off-track amount PEO and the third threshold WOS3 can be expressed by the following equation. Further, WOS3 shown in the equation shows the third threshold.

[0095] PEO≤ WOS3

[0096] Considering Equation (3) and the above equation, the relationship of the first threshold WOSI and the third threshold WOS3 is expressed by the following equation.

[0097] WOSI = TM - PEO ≥ TM - WOS3

[0098] Further, considering that the first threshold WOSI is 0 or more and the above equation (TM - WOS3 is the lower limit value of WOSI), the third threshold WOS3 can be expressed by the following equation.

[0099] WOS3≤ TM

[0100] According to the above equation, it is possible to set the TPI margin TM as the upper limit of the third threshold WOS3.

[0101] On the other hand, the third threshold WOS3 is 0 or more than the first threshold WOSI. Further, the third threshold WOS3 is 0 or more than the off-track amount PEO. That is, the relationship of the third threshold WOS3, the first threshold WOSI, and the off-track amount PEO can be expressed by the following equation.

[0102] WOS1+PEO≤2WOS3

[0103] Taking into account equation (3) and the above equations, the third threshold WOS3 can be expressed by the following equation.

[0104] TM / 2≤WOS3

[0105] According to the above-mentioned formula, a value half of the TPI margin TM can be set as the lower limit of the third threshold value WOS3.

[0106] That is, the settable range of the third threshold value WOS3 is from half the value of the TPI margin TM to the TPI margin TM. The settable range of the third threshold value WOS3 is expressed as follows using the equation:

[0107] TM / 2≤WOS3≤TM

[0108] exist Figure 5 In the embodiment, the processing of the case where the off-track amount PEO of the data area D2 becomes extremely large is described. However, when the off-track amount PEO is small to a certain extent, the first threshold WOS1 for limiting the off-track amount PEI of the data area D0 will exceed the static third threshold WOS3 (refer to formula (3)). In the case as described above, data can also be written to the track Tr0 without being restricted by the first threshold WOS1. Figure 6 Next, a description will be given of a write process performed using the second threshold value WOS2 for determining whether or not to perform control based on the first threshold value WOS1.

[0109] Figure 6 FIG. 1 is a diagram showing an example of a write process of the magnetic disk device according to the above embodiment. Figure 6 As shown, the off-track amount PEO of the data area D2 exceeds the second threshold value WOS2. In the above-mentioned case, the off-track amount PEI of the data area D0 of the data written to the track Tr0 is limited by the first threshold value WOS1.

[0110] The second threshold value WOS2 will be described in detail below.

[0111] The margin of the TPI margin TM relative to the third threshold WOS3 as the static threshold is defined as the second threshold WOS2. In this case, the second threshold WOS2 can be expressed by the following equation (5). WOS2 is the second threshold.

[0112] WOS2=TM-WOS3…(5)

[0113] Taking equations (3) and (5) into consideration, the first threshold WOS1 is expressed by the following equation.

[0114] WOS1=WOS3-(PEO-WOS2)

[0115] Here, the condition for the first threshold WOS1 not to exceed the third threshold WOS3 is expressed by equation (3) as follows.

[0116] WOS1=TM-PEO≤WOS3

[0117] Taking the above equation and equation (5) into consideration, the relationship between the second threshold WOS2 and the off-track amount PEO is expressed by the following equation.

[0118] PEO≥TM-WOS3=WOS2

[0119] Also can only under the situation that the relation of the 2nd threshold value WOS2 and the off-track amount PEO satisfies above-mentioned formula, limit off-track amount PEI by the 1st threshold value WOS1.In addition, though aftermentioned, because aspect the thriftiness in storage area is favourable, so, also can only under the situation that satisfies above-mentioned formula, preserve the value of PEO.That is to say, also can the 2nd threshold value WOS2 be made as the threshold value that is used to judge whether to register positioning error (off-track amount) PEO.

[0120] use Figure 5 and Figure 6 An example of the writing process of the embodiment corresponding to the error PEO in the outer peripheral direction is shown, but it is also applicable to the error PEI in the inner peripheral direction. The cases corresponding to both the error PEO and the error PEI are shown in FIG. Figure 7 .

[0121] Figure 7 FIG. 1 is a diagram showing an example of a write process of the magnetic disk device 1 according to the above embodiment. Figure 7 As shown, five tracks are arranged in the order of track Tr-2, track Tr-1, track Tr0, track Tr1, and track Tr2 along the radial direction from the outer circumference. Figure 7 In, it is recorded that track Tr-2 and track Tr2 have written data and the situation before track Tr0 writes data. In the mode that the remaining width (track width) of the data written into track Tr-1 and track Tr1 becomes more than the read limit track width TW0, data is written to track Tr0 off-track. In other words, when writing track Tr0, what becomes the object of data protection based on off-track writing is track Tr-1 and track Tr1, and the positioning when writing to track Tr0 is restricted in the mode that the remaining width (track width) of the data on these tracks becomes more than the read limit track width TW0 by the write action to track Tr0.

[0122] When the positioning error PEO in the outer peripheral direction is less than the second threshold value WOS2 when the track Tr2 is written (refer toFigure 7 Therefore, the deviation amount in the inner circumference direction when writing to the track Tr0 is limited by the static third threshold value WOS3.

[0123] When the positioning error PEO in the outer peripheral direction exceeds the second threshold value WOS2 when writing the track Tr2 (refer to Figure 7 (see the lower section of the figure), information on the positioning error PEO in the outer circumferential direction is registered. Therefore, the deviation in the inner circumferential direction when writing to track Tr0 is limited by a dynamic first threshold value WOS1. Furthermore, the first threshold value WOS1 is the value obtained by subtracting the registered positioning error PEO from the TPI margin TM.

[0124] When the positioning error PEI in the inner circumference direction is less than the second threshold value WOS2 when the track Tr-2 is written (refer to Figure 7 Therefore, the deviation amount in the outer circumference direction when writing to the track Tr0 is limited by the static third threshold value WOS3.

[0125] When the positioning error PEI in the inner circumference direction exceeds the second threshold value WOS2 when writing the track Tr-2 (refer to Figure 7 (see the upper section of the figure), information on the positioning error PEI in the outer circumferential direction is registered. Therefore, the deviation from the inner circumference when writing to track Tr0 is limited by a dynamic first threshold value WOS1. Furthermore, the first threshold value WOS1 is the value obtained by subtracting the registered positioning error PEI from the TPI margin TM.

[0126] The following describes the control structure of the off-track slice tightening process for implementing the set threshold (the static third threshold WOS3 or the dynamic first threshold WOS1 after tightening) and the write inhibit processing for stopping the write action when the positioning error during writing exceeds the threshold.

[0127] Figure 8 1 is a block diagram showing an example of a control structure of the magnetic disk device 1 according to the above embodiment. Figure 8 In the target sector address (C, S), the header number H is omitted and only the cylinder number C and sector number S are marked. Figure 8 As shown, the write processing circuit C1 of the write control unit 610 includes an off-track write table 611, a compression processing circuit 612, operational amplifiers OP1 and OP2, an OR gate 613, a physical target position transducer 614, a controller 615, and an actuator 616.

[0128] The target sector address (C, S) is converted to a physical target position R by the physical target position converter 614. The difference between the actual physical position Y of the magnetic head 15 and the physical target position R becomes the positioning error PE(C, S) at the sector address (C, S). Hereinafter, the "sector address" will also be referred to as simply "sector."

[0129] The positioning error PE(C, S) is negatively fed back to the controller 615 and output to the actuator P as a control variable U. The actuator P takes the control variable U as input and outputs the physical position Y of the magnetic head 15.

[0130] On the other hand, the positioning error PE (C, S) is input to the operational amplifiers OP1 and OP2, and is compared with the write off-track threshold WOS1p (hereinafter, also referred to as "threshold") of the inner peripheral side in the operational amplifier OP1, and is compared with the write off-track threshold WOS1m (hereinafter, also referred to as "threshold") of the outer peripheral side in the operational amplifier OP2. When any one of the write off-track threshold WOS1p and the write off-track threshold WOS1m is exceeded, a write inhibit flag (Write Inhibit Flag) WINH is output from the OR gate 613. When the write inhibit flag WINH is output from the OR gate 613, the system controller 130 (more specifically, the write control unit 610) stops the write operation.

[0131] In addition, according to the target sector address (C, S), with reference to the off-track write table 611, the positioning error PEO (C+2, S) in the peripheral direction of the data area written by the sector (C+2, S) 2 tracks in the inner peripheral direction and the positioning error PEI (C-2, S) in the peripheral direction of the data area written by the sector (C-2, S) 2 tracks in the outer peripheral direction are output. About the target sector address (C, S), sector (C+2, S) and sector (C-2, S), if Figure 7 For example, if the target sector address (C, S) is set to the sector located on track Tr0, then sector (C-2, S) is the sector located on track Tr-2, and sector (C+2, S) is the sector located on track Tr2.

[0132] The positioning error PEO(C+2, S), the positioning error PEI(C-2, S), the predetermined TPI margin TM, and the third threshold WOS3 as a static value are input to the compaction processing circuit 612, and the corresponding write off-track thresholds WOS1p and WOS1m are output.

[0133] Figure 9 FIG. 6 is a block diagram showing the compression processing circuit 612 of the above embodiment. Figure 9As shown, the compression processing circuit 612 includes operational amplifiers OP3 and OP4, and selectors SE1 and SE2. Terminal Q of selector SE1 receives input to determine whether the positioning error PEO(C+2, S) is zero. If it is zero, the input to terminal W3 is output from terminal W1. If it is not zero, the input to terminal W2 is output from terminal W1. Terminal Q of selector SE2 receives input to determine whether the positioning error PEI(C-2, S) is zero. If it is zero, the input to terminal W3 is output from terminal W1. If it is not zero, the input to terminal W2 is output from terminal W1.

[0134] A third static threshold WOS3 is input to terminal W3. A value obtained by subtracting the positioning error PEI(C-2, S) from the TPI margin TM or a value obtained by subtracting the positioning error PEO(C+2, S) from the TPI margin TM is input to terminal W2.

[0135] Figure 10 This is a block diagram showing an example of a control configuration of the magnetic disk device 1 according to the above embodiment. Figure 10 The structure for registering and updating the positioning error in the off-track writing table 611 is shown.

[0136] The position error PE(C, S) generated when writing to the target sector address (C, S) is input to the absolute value circuit 617 and output as the absolute value PEA of the position error PE(C, S). The absolute value PEA is compared with the second threshold value WOS2 for registration determination by the operational amplifier OP5. If the absolute value PEA exceeds the second threshold value WOS2, the operational amplifier OP5 sets the registration flag RF1 to 1 and outputs it. If the absolute value PEA does not exceed the second threshold value WOS2, the operational amplifier OP5 sets the registration flag RF1 to 0 and outputs it.

[0137] On the other hand, the off-track write table reference update block (hereinafter, also referred to as OWT reference update block) 619 outputs the past maximum positioning error PEP on the object direction of the sector (in one example, sector (C, S)) of the object. The object direction mentioned here means the direction identical with the positioning error PE (C, S).

[0138] The operational amplifier OP6 compares the past maximum positioning error PEP with the absolute value PEA of the current positioning error PE(C, S). If the absolute value PEA exceeds the maximum positioning error PEP, the operational amplifier OP6 sets the update flag RF2 to 1 and outputs the result. If the absolute value PEA does not exceed the maximum positioning error PEP, the operational amplifier OP6 sets the update flag RF2 to 0 and outputs the result. In addition, there is no entry for the sector (C, S) in the OWT reference update block 619 ( Figure 16In the case described later in the description of ), the maximum positioning error PEP is set to 0 and output, so the operational amplifier OP6 sets the update flag RF2 to 1 and outputs it.

[0139] The operational amplifier OP7 sets the flag DPE to 1 and outputs the result when the positioning error PE(C, S) is less than 0, and sets the flag DPE to 0 and outputs the result when the positioning error PE(C, S) is not less than 0. In other words, the sign of the positioning error PE(C, S) can be determined based on the flag DPE.

[0140] When registration flag RF1 is set to 1 and output, and update flag RF2 is set to 1 and output, AND gate 618 updates registration flag RF and outputs it. When update registration flag RF is set to 1 and output, in the off-track write table 611, information corresponding to the sign of positioning error PE (C, S) (specifically, PEI (C, S) or PEO (C, S)) is updated or newly registered.

[0141] Hereinafter, the steps of the write process of the present invention will be described.

[0142] First, use Figure 11 and Figure 12 , yes Figure 8 and Figure 9 The determination of the write inhibit flag WINH and the write off-track thresholds WOS1p and WOS1m described in . Figure 11 This is a flowchart showing the write process of the magnetic disk device according to the above embodiment. Figure 12 Then Figure 11 A flowchart showing a write process of the magnetic disk device according to the above embodiment.

[0143] like Figure 11 Shown, after the write process begins, in step S5, system controller 130 carries out the seek action to target sector address (C, H, S).In addition, so-called seek action is the action that makes head 15W move to target position (in one example, being target sector address (C, H, S)).Then, in step S10, system controller 130 is set to initial value+WOS3 with the write skew track threshold value WOS1p of inner peripheral side, and is set to initial value-WOS3 with the write skew track threshold value WOS1m of outer peripheral side.

[0144] After having set write off-track threshold values ​​WOS1p and WOS1m in step S10, in step S15, system controller 130 judges whether to register the positioning error PEO (C+2, H, S) in the sector (C+2, H, S) of 2 tracks on the inner peripheral side of the target position. In step S15, if it is judged that there is no registration positioning error PEO (C+2, H, S), the system controller 130 moves to step S25.

[0145] On the other hand, when being judged as registering positioning error PEO (C+2, H, S) (step S15), move to step S20, in step S20, write off-track threshold value WOS1p is set to the value that obtains by deducting positioning error PEO (C+2, H, S) from TPI margin TM.If utilize formula to represent write off-track threshold value WOS1p, then become following like this.In addition, WOS1p is the write off-track threshold value, and PEO is the positioning error in sector (C+2, H, S).

[0146] WOS1p=+(TM-PEO)

[0147] In step S20 , after setting the write off-track threshold WOS1 p , the process proceeds to step S25 .

[0148] In step S25, the system controller 130 determines whether the positioning error PEI (C-2, H, S) in the sector (C-2, H, S) two tracks outside the target position is registered. If it is determined in step S25 that the positioning error PEI (C-2, H, S) is not registered, the process proceeds to step S35. (See Figure 12 )

[0149] On the other hand, when being judged as registering and having positioning error PEI (C-2, H, S) (step S25), move to step S30, in step S30, write off-track threshold value WOS1m is set to the value that obtains by deducting positioning error PEI (C-2, H, S) from TPI margin TM.If utilize formula to represent write off-track threshold value WOS1m then become following like this.In addition, WOS1m is the write off-track threshold value, and PEI is the positioning error in sector (C-2, H, S).

[0150] WOS1m=-(TM-PEI)

[0151] In step S30 , after setting the write off-track threshold WOS1m, the process proceeds to step S35 .

[0152] Next, in step S35, system controller 130 judges whether the positioning error PE in target sector (C, H, S) is larger than write off-track threshold value WOS1p. When positioning error PE is larger than write off-track threshold value WOS1p, move to step S50, system controller 130 forbids write operation.

[0153] When the positioning error PE is less than the write off-track threshold value WOS1p (step S35), the process proceeds to step S40, in which the system controller 130 determines whether the positioning error PE is less than the write off-track threshold value WOS1m. When the positioning error PE is less than the write off-track threshold value WOS1m, the process proceeds to step S50, in which the system controller 130 forbids the write operation.

[0154] When the positioning error PE is larger than the write off-track threshold WOS1m (step S40), the process moves to step S45 to perform a write operation.

[0155] In addition, step S15 and step S20 can be interchanged with step S25 and step S30. Figure 11 For example, after writing the setting of the off-track threshold values ​​WOS1p and WOS1m in step S10, step S25 is performed, and when there is no registration positioning error PEI, step S15 is performed. Similarly, step S35 and step S40 can be interchanged.

[0156] use Figure 13 , yes Figure 10 The steps for registering the positioning error in the deflection track writing table 611 described in the description are explained. Figure 13 Then Figure 12 A flowchart showing a write process of the magnetic disk device according to the above embodiment.

[0157] After the write operation is performed in step S45 (see Figure 12 ), moves to step S55. In step S55, the system controller 130 determines whether the positioning error PE is smaller than 0. If the positioning error PE is smaller than 0, the process moves to step S60.

[0158] In step S60, the system controller 130 determines whether the positioning error PEO(C, H, S) in the peripheral direction of the sector (C, H, S) has been registered. If the positioning error PEO(C, H, S) has not been registered, it moves to step S70. In step S70, the positioning error PEO(C, H, S) is registered using the absolute value of the positioning error PE.

[0159] In step S60, if the positioning error PEO(C, H, S) has been registered, the process proceeds to step S65. In step S65, the system controller 130 determines whether the absolute value of the positioning error PE is greater than the registered positioning error PEO(C, H, S). If the absolute value of the positioning error PE is not greater than the registered positioning error PEO(C, H, S), the process proceeds to step S95 (see step S95). Figure 15 ).

[0160] When the absolute value of the positioning error PE is larger than the registered positioning error PEO(C, H, S) (step S65), the processing proceeds to step S70, in which the system controller 130 updates the positioning error PEO(C, H, S) using the absolute value of the positioning error PE. Thereafter, the processing proceeds to step S95.

[0161] On the other hand, when the positioning error PE is larger than 0 in step S55, the processing proceeds to step S75, in which the system controller 130 determines whether the inward direction positioning error PEI(C, H, S) in the sector (C, H, S) has been registered. When the inward direction positioning error PEI(C, H, S) has not been registered, the processing proceeds to step S85, in which the inward direction positioning error PEI(C, H, S) is registered using the absolute value of the positioning error PE.

[0162] When the inward direction positioning error PEI(C, H, S) has been registered in step S75, the processing proceeds to step S80, in which the system controller 130 determines whether the absolute value of the positioning error PE is larger than the registered inward direction positioning error PEI(C, H, S), and when the absolute value of the positioning error PE is not larger than the registered inward direction positioning error PEI(C, H, S), the processing proceeds to step S95.

[0163] When the absolute value of the positioning error PE is larger than the registered inward direction positioning error PEI(C, H, S) (step S80), the processing proceeds to step S85, in which the system controller 130 updates the inward direction positioning error PEI(C, H, S) using the absolute value of the positioning error PE. Thereafter, the processing proceeds to step S95.

[0164] Although the registration of the positioning error of the outward direction skew track writing table 611 has been described, the second threshold value WOS2 described in the first embodiment can be added to determine whether the registration of the positioning error is performed. A specific example is shown in FIG. 18. Figure 6 Figure 14

[0165] Figure 14 is followed by Figure 12 a flowchart showing the write processing of the disk device of the above-described embodiment.

[0166] As shown in FIG. 17, after the write operation is performed in step S45 (refer to FIG. 16), the processing proceeds to step S90, in which the system controller 130 determines whether the absolute value of the positioning error PE is larger than the second threshold value WOS2. When the absolute value of the positioning error PE is larger than the second threshold value WOS2, the processing of steps S55 to S70, or steps S55 to S85 described in the first embodiment is performed. Figure 14 Figure 12 Figure 13 When the absolute value of the positioning error PE is not larger than the second threshold value WOS2, the processing proceeds to step S95.​​​​

[0167] When the absolute value of the positioning error PE is smaller than the second threshold WOS2, the process proceeds to step S95.

[0168] Next, the steps for releasing the registration information in the off-track write table 611 are described. Figure 15 Then Figure 13 or Figure 14 A flowchart showing a write process of the magnetic disk device according to the above embodiment. Figure 15 , the steps for releasing the information registered in the off-track write table 611 are shown.

[0169] like Figure 15 As shown, in step S95, the system controller 130 determines whether the positioning error PEO(C+1, H, S) in the outer circumference direction of the sector (C+1, H, S) located one track inner than the sector (C, H, S) where the write operation was performed has been registered. If the positioning error PEO(C+1, H, S) has been registered, the process proceeds to step S105, where the positioning error PEO(C+1, H, S) is cleared. The "clearing" mentioned above means "setting the value of the positioning error PEO(C+1, H, S) to 0." Thereafter, the process proceeds to step S100.

[0170] When the positioning error PEO(C+1, H, S) has not been registered (step S95), the process proceeds to step S100.

[0171] In step S100, the system controller 130 determines whether a positioning error PEI (C-1, H, S) in the inner circumference direction of a sector (C-1, H, S) located one track outside the sector (C, H, S) to which the write operation is performed has been registered. If the positioning error PEI (C-1, H, S) has been registered, the system controller 130 proceeds to step S110, where the positioning error PEI (C-1, H, S) is cleared. The write operation to the target position is then terminated.

[0172] That is, the process of releasing the registration information is to release the registration of the positioning error of the sector (C, H, S) adjacent to the sector (C, H, S) and the sector (C-1, H, S) to the sector (C, H, S) when data is written to the sector (C, H, S).

[0173] Here, the registration of the off-track writing table 611 is explained.

[0174] Figure 16is a drawing showing an example of the off-track write table 611 of the disk device of the above-described embodiment. One registration includes the cylinder number C, the head number H, the sector number S, the positioning error in the inner peripheral direction PEI, and the positioning error in the outer peripheral direction PEO of the track. In the example, a sequence number is given to the registration, and 2401 sectors are registered. The "registration" as used herein means "registration of information". Also, in the example, 10000 is set as the upper limit of the number of registrations (hereinafter referred to as the registration number), but as long as the storage capacity permits, the information of all the sectors can be stored in the off-track write table 611. In the case where the upper limit is set to the registration number, registration release processing is performed on the information of the sectors that are no longer needed.

[0175] The registration release processing will be described in detail below.

[0176] Specifically, the registration release processing is performed on the information of the registered sector that has been overwritten with respect to the adjacent track in the case where the registered sector does not affect the adjacent track any more.

[0177] In the case where the sector located one track on the inner peripheral side of the registered sector is overwritten, the positioning error PEI of the registered sector is cleared. That is, the positioning error PEI is set to 0. In the case where the sector located one track on the outer peripheral side of the registered sector is overwritten, the positioning error PEO of the registered sector is cleared. That is, the positioning error PEO is set to 0.

[0178] In the case where both the positioning error PEI and the positioning error PEO of the registered sector become 0, registration release processing is performed on the information of the registered sector. As a result, the registration of the registered sector is released.

[0179] The steps of the above-described registration release processing will be described below.

[0180] Figure 17 is a flowchart showing the write processing of the disk device of the above-described embodiment, which is a continuation of Figure 13 or Figure 14 The steps S95, S100, S105, and S110 are the same processing as described in Figure 15 , and thus are omitted.

[0181] As described in Figure 17As shown, after clearing the positioning error PEO(C+1, H, S) in the outer circumference direction in the sector (C+1, H, S) in step S105, the process proceeds to step S115. In step S115, the system controller 130 determines whether the positioning error PEI(C+1, H, S) in the inner circumference direction in the sector (C+1, H, S) is zero. If the positioning error PEI(C+1, H, S) is not zero, the process proceeds to step S100.

[0182] If the positioning error PEI(C+1, H, S) is 0 (step S115), the process proceeds to step S120, where the system controller 130 cancels the registration in the sector (C+1, H, S). Thereafter, the process proceeds to step S100.

[0183] In step S110, after clearing the positioning error PEI(C-1, H, S) in the inner circumference direction of the sector (C-1, H, S), the process proceeds to step S125. In step S125, the system controller 130 determines whether the positioning error PEO(C-1, H, S) in the outer circumference direction of the sector (C-1, H, S) is zero. If the positioning error PEO(C-1, H, S) is not zero, the writing process to the target position is terminated.

[0184] If the positioning error PEO(C-1, H, S) is 0 (step S125), the process proceeds to step S130, where the system controller 130 cancels the registration in the sector (C-1, H, S). Thereafter, the writing process to the target position is terminated.

[0185] Next, the effects of applying the above-described write processing will be described.

[0186] Figure 18 : is a graph showing the effect of the magnetic disk device of the above embodiment. Figure 18 In the figure, the horizontal axis shows the TPI gain, which represents the ratio of the track pitch TP to a given track density achieved by reducing the required value of the TPI margin TM. The vertical axis is a performance index, which represents the ratio of the number of random writes per unit time under a vibration environment relative to the on-board environment (specifically, a positioning error 3σ value of 6.1nm). The dotted line shows the situation where the write off-track threshold is uniformly narrowed as in the past, while the solid line shows the situation where the write off-track threshold is dynamically narrowed based on the write positioning information of the first two tracks.

[0187] like Figure 18As shown, the performance improvement effect is shown until the TPI gain reaches the predetermined 1.25 times. For example, when the performance index in a vibration environment is 0.9, the TPI gain of the dotted line is about 1.1 times, and the TPI gain of the solid line is about 1.25 times. Therefore, by dividing 1.25 by 1.1, it can be seen that there is a potential of 1.13 times.

[0188] The magnetic disk device 1 configured as described above includes a magnetic disk 10, a magnetic head 15, and a controller 130. The controller 130 determines whether positioning errors PEI and PEO are registered in the sector two tracks before the sector to be written. If so, the controller 130 sets a first threshold value WOS1 based on the positioning errors PEI and PEO, and determines whether to perform a write operation based on the first threshold value WOS1 and the positioning error PE of the sector to be written.

[0189] The controller 130 registers both the positioning error PEI in the inner peripheral direction and the positioning error PEO in the outer peripheral direction.

[0190] The controller 130 determines whether to register the positioning errors PEI and PEO based on the positioning error PE of the sector to be written and the second threshold WOS2 for determining registration.

[0191] The first threshold WOS1 is a value obtained by subtracting positioning errors PEI and PEO of sectors registered two tracks before the sector to be written from a predetermined TPI margin.

[0192] Therefore, even if the write off-track thresholds WOS1p and WOS1m are not uniformly narrowed, the track width TW can be maintained above the read limit track width TW0, and a magnetic disk device can be obtained that can improve the write performance by suppressing write errors and retry actions caused by the positioning error PE exceeding the threshold while maintaining the reading quality.

[0193] The controller 130 may also cancel the registration of the positioning errors PEI and PEO registered in the sectors adjacent to the sector after writing. This can cope with the off-track writing table 611 having an upper limit on the number of registrations.

[0194] If no positioning errors PEI and PEO are registered in sectors two tracks before the sector to be written, the controller 130 determines whether to perform the write operation based on the positioning error PE of the sector to be written and a third constant static threshold WOS3.

[0195] The third threshold WOS3 is between half of the TPI margin and the TPI margin, thereby preventing the dynamic write off-track thresholds WOS1p and WOS1m from being extremely relaxed.

[0196] (Other embodiments)

[0197] Next, a magnetic disk device 1 according to another embodiment will be described. Except for the points described in the other embodiment, the magnetic disk device 1 is the same as that of the above embodiment.

[0198] First, the write process of the magnetic disk device 1 will be described. The definition of the first threshold value differs between the above embodiment and other embodiments, but the write procedure is the same. Therefore, the first threshold value WOS12 in other embodiments will be described in detail.

[0199] In the above embodiment, Figure 3 The first threshold WOS1 shown is expressed using formula (3), Figure 6 The second threshold WOS2 shown is represented by equation (5). The first threshold WOS1 in the above embodiment can be represented by the following equation based on equations (3) and (5).

[0200] WOS1=WOS3-(PEO-WOS2)

[0201] The first threshold value WOS12 in another embodiment can be expressed using the following equation, which is obtained by multiplying the difference (PEO - WOS2) between the positioning error PEO and the second threshold value WOS2 shown in the above equation by a predetermined gain GAIN. WOS12 represents the first threshold value in another embodiment, and GAIN represents the predetermined gain.

[0202] WOS12=WOS3-GAIN×(PEO-WOS2)

[0203] Here, the first threshold WOS12 can be expressed by the following formula (6) based on the above formula and formula (5).

[0204] WOS12=TM+G0-GAIN×PEO…(6)

[0205] In addition, G0 is a constant expressed by the following formula and is a predetermined value.

[0206] G0=(GAIN-1)×WOS2

[0207] Furthermore, considering equation (3), equation (6) can be transformed into the following equation.

[0208] WOS12=WOS1+(1-GAIN)×(PEO-WOS2)

[0209] According to the above equation, when the positioning error PEO is greater than the second threshold WOS2 and the gain GAIN is greater than 1, the first threshold WOS12 for the positioning error PEI described below is smaller than the first threshold WOS1 in the above embodiment. Furthermore, as described above, the gain GAIN is a value greater than 1, such as 1.5, 2, or the like.

[0210] on the other hand, Figure 4 The first threshold WOS1 in the above-described embodiment can be expressed by the following equation based on equations (4) and (5).

[0211] WOS1=WOS3-(PEI-WOS2)

[0212] The first threshold WOS12 in other embodiments can be expressed by the following equation obtained by multiplying the difference (PEI-WOS2) between the positioning error PEI and the second threshold WOS2 shown in the above equation by a predetermined gain GAIN.

[0213] WOS12=WOS1+GAIN(PEI-WOS2)

[0214] Here, the first threshold WOS12 is expressed by the following equation (7) based on the above equation and equation (5).

[0215] WOS12=TM+G0-GAIN×PEI…(7)

[0216] Furthermore, considering equation (3), equation (7) can be transformed into the following equation.

[0217] WOS12=WOS1+(1-GAIN)×(PEI-WOS2)

[0218] According to the above equation, when the positioning error PEI is greater than the second threshold WOS2 and the gain GAIN is greater than 1, the first threshold WOS12 for the positioning error PEO described below is smaller than the first threshold WOS1 in the above embodiment. Furthermore, as described above, the gain GAIN is a value greater than 1, such as 1.5, 2, or the like.

[0219] Next, the compaction processing circuit 612 of the magnetic disk device 1 according to another embodiment will be described. Figure 19 FIG. 6 is a block diagram showing a compaction processing circuit 612 of a magnetic disk device 1 according to another embodiment. Figure 19 As shown, the compression processing circuit 612 further includes gain amplifiers GA1, GA2, and GA3, an operational amplifier OP8, and an amplifier AN.

[0220] Gain amplifier GA1 outputs the value obtained by multiplying the input positioning error PEO(C+2, S) by the gain GAIN (hereinafter also referred to as the "product of the positioning error PEO(C+2, S) and the gain GAIN") to operational amplifier OP3 and selector SE1. Gain amplifier GA2 outputs the value obtained by multiplying the input positioning error PEI(C-2, S) by the gain GAIN (hereinafter also referred to as the "product of the positioning error PEI(C-2, S) and the gain GAIN") to operational amplifier OP4 and selector SE2. Gain amplifier GA3 outputs the value obtained by multiplying the input second threshold value WOS2 by the gain GAIN to operational amplifier OP8. Operational amplifier OP8 outputs the value (predetermined value G0) obtained by subtracting the second threshold value WOS2 from the value input from gain amplifier GA3 to amplifier AN. Amplifier AN outputs the value obtained by adding the predetermined value G0 to the TPI margin TM to operational amplifier OP3 and operational amplifier OP4.

[0221] Whether the product of the positioning error PEO(C+2, S) and the gain GAIN is zero is input to terminal Q of selector SE1. If the value input from terminal Q is zero, selector SE1 outputs the value input to terminal W1. If the value input from terminal Q is other than zero, selector SE1 outputs the value input to terminal W2.

[0222] Terminal Q of selector SE2 is input with the product of positioning error PEI (C-2, S) and gain GAIN to determine whether it is zero. When the value input from terminal Q is zero, selector SE2 outputs the value input to terminal W1. When the value input from terminal Q is other than zero, selector SE2 outputs the value input to terminal W2.

[0223] Terminal W3 receives an input of a third static threshold value WOS3. Terminal W2 receives an input of a value obtained by subtracting the position error PEO(C+2, S) multiplied by the gain GAIN from the sum of the TPI margin TM and the predetermined value G0, or a value obtained by subtracting the position error PEI(C-2, S) multiplied by the gain GAIN from the sum of the TPI margin TM and the predetermined value G0.

[0224] Next, a description will be given of a procedure for determining the write off-track thresholds WOS1p and WOS1m in the magnetic disk device 1 according to another embodiment. Figure 20 This is a flowchart showing a write process of the magnetic disk device 1 according to another embodiment. Except for step S21 and step S31, the process is the same as that of the above embodiment, so only step S21 and step S31 will be described.

[0225] like Figure 20Shown, in step S15, when being judged to register and having positioning error PEO (C+2, H, S), move to step S21, system controller 130, in step S21, write off-track threshold value WOS1p is set to and TPI margin TM is added predetermined amount G0 and deducts the value that the product of positioning error PEO (C+2, H, S) and gain GAIN obtains.If utilize formula to represent write off-track threshold value WOS1p, then become following like this.In addition, WOS1p is the write off-track threshold value, and PEO is the positioning error in sector (C+2, H, S).

[0226] WOS1p=+(TM+G0-GAIN×PEO)

[0227] In step S21 , after setting the write off-track threshold WOS1 p , the process proceeds to step S25 .

[0228] In step S25, when being judged as registering positioning error PEI (C-2, H, S), move to step S31, system controller 130, in step S31, write off-track threshold value WOS1m is set to TPI margin TM adding predetermined amount G0 and deducting the value that the product of positioning error PEI (C-2, H, S) and gain GAIN obtains.If utilizing formula to represent write off-track threshold value WOS1m, then become following like this.In addition, WOS1m is the write off-track threshold value, and PEI is the positioning error in sector (C-2, H, S).

[0229] WOS1m=-(TM+G0-GAIN×PEI)

[0230] In step S31, after setting the write off-track threshold WOS1m, the process proceeds to step S35.

[0231] Next, effects of the magnetic disk device 1 according to another embodiment will be described.

[0232] According to the magnetic disk drive 1 configured as described above, the first threshold WOS12 is obtained by adding a predetermined amount G0 to a predetermined TPI margin TM and subtracting a predetermined gain GAIN and the product of the positioning errors PEI and PEO registered in the sector two tracks before the sector to be written. In this case, the gain GAIN is a value greater than 1.

[0233] Furthermore, the predetermined amount G0 is the product of the value obtained by subtracting 1 from the predetermined gain GAIN and the second threshold value WOS2. This reduces the positioning error PEI and the positioning error PEO, thereby ensuring a sufficient track width TW (see equation (1)) even when the track pitch TP is reduced. For these reasons, a magnetic disk device 1 with an improved recording density can be obtained.

[0234] (Variation)

[0235] A modification of the disk device 1 of the other embodiment will be described. The disk device 1 is the same as the other embodiment except for the description in the modification.

[0236] In the above-described embodiment, Figure 3 The first threshold WOS1 shown is represented by the equation (3). The first threshold WOS13 in the modification can be represented by the following equation (8) obtained by multiplying the positioning error PEO of the equation (3) by a predetermined gain GAIN. Further, WOS13 represents the first threshold in the modification.

[0237] WOS13 = TM - GAIN x PEO... (8)

[0238] If the equation (3) is considered, the equation (8) can be transformed into the following equation.

[0239] WOS13 = WOS1 + (1 - GAIN) x PEO

[0240] According to the above-described equation, in the case where the gain GAIN is larger than 1, the first threshold WOS12 for the positioning error PEI to be written next is smaller than the first threshold WOS1 in the above-described embodiment. According to the above, the gain GAIN is a value of 1 or more.

[0241] On the other hand, in the above-described embodiment, Figure 4 The first threshold WOS1 shown is represented by the equation (4). The first threshold WOS13 in the modification can be represented by the following equation (9) obtained by multiplying the positioning error PEI of the equation (4) by a predetermined gain GAIN.

[0242] WOS13 = TM - GAIN x PEI... (9)

[0243] If the equation (3) is considered, the equation (9) can be transformed into the following equation.

[0244] WOS13 = WOS1 + (1 - GAIN) x PEI

[0245] According to the above-described equation, in the case where the gain GAIN is larger than 1, the first threshold WOS13 for the positioning error PEO to be written next is smaller than the first threshold WOS1 in the above-described embodiment. According to the above, the gain GAIN is a value of 1 or more.

[0246] Next, the compaction processing circuit 612 in the modification of the disk device 1 of the other embodiment will be described. Figure 21 is a block diagram showing the compaction processing circuit 612 in the modification of the disk device 1 of the other embodiment.

[0247] like Figure 21 As shown, the pinch processing circuit 612 is configured without the gain amplifier GA3, the operational amplifier OP8, and the amplifier AP.

[0248] Terminal W3 receives a third static threshold value WOS3, while terminal W2 receives a value obtained by subtracting the product of the positioning error PEO(C+2, S) and the gain GAIN from the TPI margin TM, or a value obtained by subtracting the product of the positioning error PEI(C-2, S) and the gain GAIN from the TPI margin TM.

[0249] Next, a description will be given of a procedure for determining the write off-track thresholds WOS1p and WOS1m in a modified example of the magnetic disk device 1 according to another embodiment. Figure 22 This is a flowchart showing a write process in a modified example of another embodiment of the magnetic disk device 1. Since the processes other than step S22 and step S32 are the same as those in the other embodiments, only step S22 and step S32 will be described.

[0250] like Figure 22 Shown, in step S15, when being judged to register and having positioning error PEO (C+2, H, S), move to step S22, system controller 130, in step S22, will write off-track threshold value WOS1p and be set to the value that obtains from the product of deducting positioning error PEO (C+2, H, S) and gain GAIN from TPI margin TM.If utilize formula to represent write off-track threshold value WOS1p, then become following like this.In addition, WOS1p is the write off-track threshold value, and PEO is the positioning error in sector (C+2, H, S).

[0251] WOS1p=+(TM-GAIN×PEO)

[0252] In step S22 , after setting the write off-track threshold WOS1 p , the process proceeds to step S25 .

[0253] In step S25, when being judged as registering positioning error PEI (C-2, H, S), move to step S32, system controller 130, in step S32, will write off-track threshold value WOS1m and be set to the value that obtains from the product of TPI margin TM deducting positioning error PEI (C-2, H, S) and gain GAIN.If utilize formula to represent write off-track threshold value WOS1m, then become following like this.In addition, WOS1m is the write off-track threshold value, and PEI is the positioning error in sector (C-2, H, S).

[0254] WOS1m=-(TM-GAIN×PEI)

[0255] In step S32, after setting the write off-track threshold WOS1m, the process proceeds to step S35.

[0256] According to the magnetic disk device 1 configured as described above, the first threshold WOS13 is a value obtained by subtracting the product of a predetermined gain GAIN and positioning errors PEI and PEO registered in sectors two tracks before the sector to be written from a predetermined TPI margin TM. This achieves the same effects as those of the other embodiments.

[0257] While 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. The novel embodiments described above can be implemented in various other forms and can be omitted, replaced, or modified without departing from the gist of the invention. The embodiments described above and / or their variations are included within the scope and gist of the invention and are included in the invention described in the claims and their equivalents.

Claims

1. A magnetic disk device comprising: disk; a magnetic head positioned at a track of the magnetic disk having a predetermined track pitch, and writing data to the track of the magnetic disk and reading data from the track of the magnetic disk; and A controller is provided for positioning the magnetic head, registering an address of a sector of the track where the data is written and a positioning error of the magnetic head relative to the track at the address, the controller, determining whether a positioning error of a second sector two tracks radially forward of a first sector to which the data is to be written is registered; and if the positioning error of the second sector is registered, setting a first threshold value for allowing a write operation with respect to the positioning error of the first sector based on the positioning error of the second sector; It is determined whether the positioning error of the first sector exceeds the first threshold, and the writing operation is stopped if the positioning error of the first sector exceeds the first threshold.

2. The magnetic disk device according to claim 1, The controller registers both the positioning error in the inner peripheral direction and the positioning error in the outer peripheral direction.

3. The magnetic disk device according to claim 1, the controller, setting a second threshold value for determining registration of a positioning error of the first sector, It is determined whether the positioning error of the first sector exceeds the second threshold, and if the positioning error of the first sector exceeds the second threshold, the positioning error of the first sector is registered.

4. The magnetic disk device according to claim 2, the controller, setting a second threshold value for determining registration of a positioning error of the first sector, Determine whether the positioning error of the first sector exceeds the second threshold, Determine whether there is a registered positioning error in the first sector, determining whether the positioning error of the first sector and the registered positioning error are consistent in direction in either the inner circumferential direction or the outer circumferential direction, Determine whether the absolute value of the positioning error of the first sector is greater than the registered positioning error, When the positioning error of the first sector exceeds the second threshold, the registered positioning error exists, the positioning error of the first sector is consistent with the direction of the registered positioning error, and the absolute value of the positioning error of the first sector is larger than the registered positioning error, the positioning error of the first sector is registered.

5. The magnetic disk device according to claim 1, the controller, determining whether a positioning error of a third sector radially adjacent to the first sector has been registered, Determine whether the direction of the positioning error of the third sector is toward the direction of the first sector, When the positioning error of the third sector is registered and the direction of the positioning error of the third sector is toward the first sector, registration of the positioning error of the third sector is canceled.

6. The magnetic disk device according to claim 1, The first threshold value is a value obtained by subtracting the positioning error of the second sector from a predetermined track pitch narrowing margin.

7. The magnetic disk device according to claim 5, The first threshold is a value obtained by subtracting the positioning error of the second sector from a predetermined track pitch narrowing margin. The predetermined track pitch narrow margin is the sum of the positioning error of the first sector and the positioning error of the second sector, which is the width of the read limit track of the third sector sandwiched between the first sector and the second sector when the first sector and the second sector are written.

8. The magnetic disk device according to claim 6, the controller, When the positioning error of the second sector is not registered, a third threshold value for allowing the write operation is set with respect to the positioning error of the first sector. Determine whether the positioning error of the first sector exceeds the third threshold, When the positioning error of the first sector exceeds the third threshold, the writing operation is stopped.

9. The magnetic disk device according to claim 8, The third threshold has a size ranging from half of the track pitch narrow margin to the track pitch narrow margin.

10. The magnetic disk device according to claim 3, The first threshold value is a value obtained by adding a predetermined amount to a predetermined track pitch narrowing margin and subtracting a product of a predetermined gain and a positioning error of the second sector.

11. The magnetic disk device according to claim 10, The predetermined amount is the product of a value obtained by subtracting 1 from the predetermined gain and the second threshold value.

12. The magnetic disk device according to claim 1, The first threshold value is a value obtained by subtracting the product of a predetermined gain and a positioning error of the second sector from a predetermined track pitch narrowing margin.

13. The magnetic disk device according to claim 10 or 12, The predetermined gain is a value greater than or equal to 1.

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