Magnetic disk device

Abstract

A disk drive device capable of improving reliability is provided. The disk drive device according to this embodiment includes: a disk having tracks including a first servo sector and a second servo sector different from the first servo sector; a head for writing data to the disk and reading data from the disk; and a controller that records first signal strength recording data associated with the signal strength obtained from reading first target servo data, and normalizes the first signal strength data associated with the signal strength obtained from reading the first target servo data when reading the first target servo data, wherein the first target servo data is the target servo data of the first servo sector.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2022-028065 (filed on February 25, 2022). This application incorporates the entire contents of that basic application by reference. Technical Field

[0002] Embodiments of the present invention relate to disk drives. Background Technology

[0003] Disk drives control the head-to-disk spacing (hereinafter referred to as hover). High-fly writes (HFW) can occur in disk drives, where the head floats due to contact with contaminants on the disk, resulting in a higher hover than usual. When writing to the disk with an HFW-affected head, the magnetization of the disk may become insufficient. Therefore, read errors may occur when reading data written with an HFW-affected head. To avoid such read errors, disk drives need to ensure a margin for the bit error rate (BER) by setting the BPI (bits per inch) lower than the optimal BPI. This may result in ADC (Analog-to-Digital Converter) loss. Furthermore, with the recent increase in the TPI (tracks per inch) of disk drives, the amplitude of the reproduced signal when reading from a predetermined area weakens. Therefore, the deviation in signal strength between each servo sector of the disk drive increases. When considering the high-frequency deviation in each servo sector, and the slight variation in signal strength due to the NRRO (Non-Repeatable Run-Out) component each time it is reproduced, it may be difficult to determine the data written with normal and high float by a threshold. Summary of the Invention

[0004] The problem to be solved by the embodiments of the present invention is to provide a disk drive that can improve reliability.

[0005] The disk device according to this embodiment includes: a disk having tracks including a first servo sector and a second servo sector different from the first servo sector; a head for writing data to the disk and reading data from the disk; and a controller that records first signal strength recording data associated with the signal strength of read first target servo data, and normalizes the first signal strength data associated with the signal strength of read first target servo data when reading the first target servo data, wherein the first target servo data is the target servo data of the first servo sector. Attached Figure Description

[0006] Figure 1 This is a block diagram illustrating the configuration of the disk drive according to the first embodiment.

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

[0008] Figure 3 This is a schematic diagram illustrating an example of the configuration of the servo sector and data sector regions involved in the first embodiment.

[0009] Figure 4 This is a schematic diagram illustrating an example of a disc and a head before expansion.

[0010] Figure 5 This is a schematic diagram illustrating an example of a disc and an expanded head.

[0011] Figure 6 This is a schematic diagram illustrating an example of the configuration of the signal strength recording data (SIS) according to the first embodiment.

[0012] Figure 7 This is a schematic diagram illustrating an example of the HFW detection method according to the first embodiment.

[0013] Figure 8 This is a schematic diagram illustrating an example of how the object servo reproduction signal strength of each servo sector changes relative to each servo sector when each servo sector is read from a head that has been written with normal and high float values.

[0014] Figure 9 This is a schematic diagram illustrating an example of the variation of the normalized reproducible signal strength relative to each servo sector when reading from each servo sector written with a head of normal and high levitation.

[0015] Figure 10 This is a schematic diagram illustrating an example of how BER changes relative to BPI.

[0016] Figure 11 This is a schematic diagram illustrating an example of the change in ADC relative to BPI.

[0017] Figure 12 This is a flowchart illustrating an example of the HFW detection method according to the first embodiment.

[0018] Figure 13 This is a flowchart illustrating an example of the HFW detection method involved in Variation 1.

[0019] Figure 14 This is a schematic diagram illustrating an example of the HFW detection method involved in Variation Example 2.

[0020] Figure 15 This is a flowchart illustrating an example of the HFW detection method involved in Variation Example 2.

[0021] Figure 16 This is a schematic diagram illustrating an example of the configuration of averaged signal strength recording data involved in Variation Example 3.

[0022] Figure 17 This is a schematic diagram illustrating an example of the HFW detection method involved in Variation 3.

[0023] Figure 18 This is a flowchart illustrating an example of the HFW detection method involved in Variation Example 3.

[0024] Figure 19 This is a schematic diagram illustrating an example of the configuration of the servo sector according to the second embodiment.

[0025] Figure 20 This is a schematic diagram illustrating an example of the variation of each reproduced signal strength threshold relative to each servo sector in the second embodiment.

[0026] Figure 21 This is a flowchart illustrating an example of the HFW detection method according to the second embodiment.

[0027] Label Explanation

[0028] 1 Disk Device, 10 Disk, 10a User Data Area, 10b System Area, 12 Spindle Motor (SPM), 13 Arm, 14 Voice Coil Motor (VCM), 15 Head, 15W Write Head, 15R Read Head, 15H Heater, 20 Driver IC, 30 Head Amplifier IC, 40 Read / Write (R / W) Channels, 50 Hard Disk Controller (HDC), 60 Microprocessor (MPU), 70 Volatile Memory, 80 Non-Volatile Memory, 90 Buffer Memory, 100 Host System (Host), 130 System Controller. Detailed Implementation

[0029] The embodiments will now be described with reference to the accompanying drawings. Furthermore, the drawings are merely examples and do not limit the scope of the invention.

[0030] (First Embodiment)

[0031] Figure 1 This is a block diagram illustrating the configuration of the disk device 1 according to the first embodiment.

[0032] The disk drive 1 includes a head-disk assembly (HDA), a driver IC 20, a head amplifier integrated circuit (hereinafter referred to as a head amplifier IC or preamplifier) ​​30, volatile memory 70, non-volatile memory 80, buffer memory (cache) 90, and a system controller 130 as a single chip integrated circuit. Furthermore, the disk drive 1 is connected to a host system (hereinafter referred to as a host) 100. Alternatively, the disk drive 1 may be a two-dimensional magnetic recording (TDMR) disk drive with multiple read heads 15R on a single head 15.

[0033] The HDA includes a disk (hereinafter referred to as a disk) 10, a spindle motor (hereinafter referred to as a spindle motor) 12, an arm 13 with a head 15 mounted on it, and a voice coil motor (hereinafter referred to as a voice coil motor) 14. The disk 10 is mounted on the SPM 12 and rotates under the drive of the SPM 12. The arm 13 and the VCM 14 constitute an actuator. The actuator, driven by the VCM 14, moves the head 15 mounted on the arm 13 to a predetermined position on the disk 10. Two or more disks 10 and heads 15 may be provided. Additionally, two or more actuators may be provided.

[0034] Disk 10 allocates a user data area 10a for use by the user and a system area 10b for writing information required for system management within its writable data area. Additionally, disk 10 may also allocate a media cache (or sometimes called a media cache area) to temporarily hold data (or commands) transmitted from the host or other source before writing it to a predetermined area of ​​the user data area 10a, as a separate area from the user data area 10a and the system area 10b. Hereinafter, the direction from the inner periphery to the outer periphery of disk 10, or the direction from the outer periphery to the inner periphery of disk 10, is referred to as the radial direction. Within the radial direction, the direction from the inner periphery to the outer periphery is called the outer direction (or outer side), and the direction from the outer periphery to the inner periphery, i.e., the direction opposite to the outer direction, is called the inner direction (or inner side). The direction orthogonal to the radial direction of disk 10 is called the circumferential direction. That is, the circumferential direction corresponds to the direction along the circumference of disk 10. Furthermore, a predetermined position in the radial direction of disk 10 is sometimes called the radial position, and a predetermined position in the circumferential direction of disk 10 is sometimes called the circumferential position. Sometimes, the radial position and the circumferential position are simply referred to as "position". Disk 10 is divided into multiple zones (hereinafter sometimes called zones or zone areas) according to predetermined ranges in the radial direction. A zone contains multiple tracks. A track contains multiple sectors. Furthermore, a "track" refers to one of the multiple zones obtained by dividing disk 10 in the radial direction according to predetermined ranges, data written in one of the multiple zones obtained by dividing disk 10 in the radial direction according to predetermined ranges, a region extending circumferentially at a predetermined radial position of disk 10, data written in a region extending circumferentially at a predetermined radial position of disk 10, a region circumferentially around a predetermined radial position of disk 10, a region circumferentially around a predetermined radial position of disk 10, and a path of the head 15 for writing at a predetermined radial position of disk 10. The term "track" is used to refer to various meanings, including: diameter, data written to the head 15 positioned at a predetermined radius of the disk 10, data written in a predetermined track of the disk 10, and so on. The term "sector" refers to one of several regions obtained by dividing the predetermined track of the disk 10 circumferentially, data written to one of these regions, a region at a predetermined circumferential position at a predetermined radius of the disk 10, data written to a region at a predetermined circumferential position at a predetermined radius of the disk 10, data written in a predetermined sector of the disk 10, and so on. Sometimes, the "width in the radial direction of the track" is also referred to as "track width." Sometimes, the center position of the track width is also referred to as the track center. Sometimes, the track center is simply referred to as the track.

[0035] The head 15 has a slider as its main body and includes a write head 15W, a read head 15R, and a heater (heating element) 15H mounted on the slider. The write head 15W writes data onto the disk 10. For example, the write head 15W writes data to a predetermined track or sector of the disk 10. Hereinafter, "writing data" will sometimes be referred to as "data writing" or "write processing," etc. The read head 15R reads data recorded on the disk 10. For example, the read head 15R reads data from a predetermined track or sector of the disk 10. Hereinafter, "reading data" will sometimes be referred to as "data reading" or "read processing." Furthermore, sometimes "write head 15W" is simply referred to as "head 15," and sometimes "read head 15R" is simply referred to as "head 15." Additionally, sometimes "write head 15W and read head 15R" are collectively referred to as "head 15." Sometimes, the "center portion of head 15" is referred to as "head 15", the "center portion of write head 15W" is referred to as "write head 15W", and the "center portion of read head 15R" is referred to as "read head 15R". Sometimes, the "center portion of write head 15W" is simply referred to as "head 15", and sometimes the "center portion of read head 15R" is simply referred to as "head 15". Sometimes, phrases such as "positioning head 15 in a predetermined position", "configuring head 15 in a predetermined position", or "locating head 15 in a predetermined position" are used to express "positioning the center portion of head 15 in a predetermined position". Sometimes, phrases such as "positioning head 15 in a predetermined area", "configuring head 15 in a predetermined area", "locating head 15 in a predetermined area", "configuring head 15 in a predetermined area", or "located in a predetermined area" are used to express "positioning the center portion of head 15 in a predetermined area as a target position (hereinafter sometimes referred to as the area target position), for example, the center in the radial direction of the predetermined area". Sometimes, phrases like "positioning head 15 on a predetermined track," "arranging head 15 on a predetermined track," "positioning head 15 on a predetermined track," "positioning head 15 on a predetermined track," "arranging head 15 on a track," or "located on a track" are used to express the idea of ​​"positioning the center of head 15 at a target position on a predetermined track (hereinafter sometimes referred to as the track target position), such as the center of the track." The heater 15H is heated by being supplied with electricity. The heater 15H can also be located near the write head 15W and the read head 15R, respectively. Furthermore, in the case of a TDMR type disk device, head 15 may have one write head 15W, multiple read heads 15R, and at least one heater 15H.

[0036] Figure 2 This is a schematic diagram illustrating an example of the configuration of the disk 10 according to this embodiment. For example... Figure 2 As shown, the direction in which disk 10 rotates in the circumferential direction is called the rotation direction. Furthermore, in... Figure 2 In the example shown, the direction of rotation is represented by counterclockwise, but it can also be the opposite direction (clockwise).

[0037] Disk 10 has multiple servo regions SV and multiple data regions DA. The multiple servo regions SV may extend radially in the radial direction of disk 10 and be discretely arranged with predetermined intervals in the circumferential direction. Alternatively, the multiple servo regions SV may extend spirally from the inner circumference to the outer circumference or from the outer circumference to the inner circumference and be discretely arranged with predetermined intervals in the circumferential direction. Furthermore, the multiple servo regions SV may be arranged in an island-like pattern in the radial direction and discretely arranged with varying predetermined intervals in the circumferential direction. Hereinafter, "a servo region SV in a predetermined track" will sometimes be referred to as a "servo sector." That is, a servo region SV has at least one servo sector. Furthermore, "servo region SV" will sometimes be referred to as a "servo sector SV." A servo sector contains servo data. Hereinafter, "the configuration of several servo data constituting a servo sector" will sometimes be referred to as a "servo mode." Furthermore, "servo data written in a servo sector" will sometimes be referred to as a "servo sector."

[0038] Multiple data regions (DAs) are configured between multiple servo regions (SVs). For example, a data region DA corresponds to the area between two consecutive servo regions SV in a circular direction. Furthermore, a data region DA within a predetermined track is sometimes referred to as a "data sector region." That is, a data region DA has at least one data sector region. A data sector region has at least one sector. A data sector region is sometimes referred to simply as a "sector." Additionally, the data written within a data sector region is sometimes referred to as a "data sector region."

[0039] The head 15 is driven by the VCM14 to rotate relative to the disk 10 about the rotation axis, moving from the inside to the outside to a predetermined position, or from the outside to the inside to a predetermined position.

[0040] Figure 3 This is a schematic diagram illustrating an example of the configuration of the servo sector (SS) and data sector region (DSR) involved in this embodiment. Figure 3 The diagram shows the predetermined servo sector SS and data sector area DSR written in the predetermined track TRn of disk 10. (Example) Figure 3 As shown, in the circumferential direction, the direction of the tip of the forward-pointing arrow is called forward (or forward direction), and the direction of the tip of the backward-pointing arrow is called backward (or backward direction). For example, in the circumferential direction, the direction of reading / writing (read / write direction) is equivalent to the direction from forward to backward. Furthermore, the read / write direction can also be equivalent to the direction from backward to forward. The read / write direction is, for example, equivalent to... Figure 2 The direction of rotation shown is opposite to the direction shown.

[0041] The servo sector SS contains servo data, such as preamble, sync mark, Gray code, PES (Position Error signal), and RRO (Repeatable Run-Out). Additionally, the servo sector SS may also contain servo data other than preamble, sync mark, Gray code, PES, and RRO. In the servo sector SS, the preamble, sync mark, Gray code, PES, and RRO are arranged sequentially from front to back in the circumferential direction as described above. The preamble contains preamble information used to synchronize with the reproduction signal of the servo mode, which is composed of the sync mark and Gray code. The sync mark contains sync mark information indicating the start of the servo mode. The Gray code consists of the address of a predetermined track (cylinder address) and the address of the servo sector of the predetermined track. PES corresponds to data related to tracking the position error signal. RRO is data related to the eccentricity of disk 10. For example, RRO corresponds to the data that corresponds to the error caused by the jitter (repeated yaw: RRO) that occurs when servo data is written to the disk due to the rotation of the disk 10, which is synchronized with the jitter. The track is positioned concentrically with the disk 10 as the target path of the head 15 (hereinafter sometimes referred to as the target path), such as the skew of the center of the track.

[0042] exist Figure 3In the example shown, the data sector region (DSR) in the area adjacent to a servo sector (SS) (hereinafter sometimes referred to as the signal strength recording area) contains data (hereinafter sometimes referred to as signal strength recording data) associated with the signal strength of the area or data (hereinafter sometimes referred to as the signal strength object area or signal strength object servo data) that is the object of the servo sector SS when a predetermined servo sector SS is read, such as the reproduced signal (hereinafter sometimes referred to as the object servo reproduced signal) corresponding to a part or all of the servo sector SS. Furthermore, the signal strength recording area may be contained within the servo sector SS, or within an area other than the data sector region (DSR) and the servo sector SS. Sometimes the "signal strength recording data SIS" is also referred to as the "signal strength recording area SIS". Hereinafter, "signal strength object area", "signal strength object servo data", and "part or all of the servo sector SS" are sometimes simply referred to as "servo sector SS". The signal strength recording area is adjacent to the servo sector SS in the read / write direction. In other words, the signal strength recording area is immediately adjacent to the servo sector SS. For example, the signal strength recording area is adjacent to the servo sector SS immediately following its RRO. Alternatively, the signal strength recording area may not be adjacent to the servo sector SS in the read / write direction. The term "adjacent" naturally includes meanings such as "continuous" and "grounded" in a predetermined direction, as well as meanings such as "separated to a degree that can be considered substantially continuous." The signal strength recording data SIS is adjacent to the servo sector SS in the read / write direction. In other words, the signal strength recording data SIS is adjacent to the servo sector SS immediately following its RRO. For example, the signal strength recording data SIS is adjacent to the servo sector SS immediately following its RRO. Alternatively, the signal strength recording data SIS may not be adjacent to the servo sector SS in the read / write direction. The signal strength recording data SIS may not be adjacent to the servo sector SS. For example, the signal strength recording data SIS may not be adjacent to the RRO of the servo sector SS. For example, the signal strength object area, signal strength object servo data, and signal strength recording data (SIS) are servo data that always produce the same read signal (or reproduced signal) without performing rewrite processes such as rewriting data from a predetermined area back to that area. Terms such as "same," "identical," "consistent," and "equivalent" naturally include the meaning of being completely identical, as well as the meaning of being different to a degree that can be considered substantially identical. Signal strength recording data (SIS) is data associated with the signal strength when the signal strength object area (or signal strength object servo data) has been read.Signal strength recording data (SIS) can be, for example, the value obtained by performing a Fourier transform on the object servo reproduced signal. Signal strength recording data (SIS) can also be, for example, the value obtained by performing Fourier transforms on the object servo reproduced signal and the ideal signal, or the demodulated signal, respectively, followed by a division operation. Signal strength recording data (SIS) can also be, for example, the 1 / 2 harmonic (2nd harmonic) obtained by performing a Fourier transform on the preamble used as a 2T mode, or the fundamental frequency or nth harmonic obtained by performing a Fourier transform on the reproduced signal (object servo reproduced signal) of the Sync Mark / Gray Code / RRO and the ideal signal or demodulated signal, followed by a division operation. Signal strength recording data (SIS) can also be, for example, the amplitude of the object servo reproduced signal (hereinafter sometimes referred to as the object servo reproduced signal amplitude).

[0043] Furthermore, multiple servo sectors (SS) can also have both regular servo sectors (hereinafter referred to as regular servo sectors) and short servo sectors. A regular servo sector, for example, is... Figure 3 The servo sector SS is shown below. A short servo sector is, for example, one where less servo data is read, less servo data is generated, and has a shorter circumferential length than a typical servo sector. When multiple servo sectors SS include both typical and short servo sectors, the signal strength recording area may be configured immediately following the typical servo sector in the read / write direction, but not between the short servo sector and the next servo sector in the read / write direction. In other words, when multiple servo sectors SV include both typical and short servo sectors, the signal strength recording area is adjacent to the typical servo sector in the read / write direction, but not adjacent to the short servo sector in the read / write direction. When multiple servo sectors SS include both typical and short servo sectors, the signal strength recording data SIS may also be written immediately following the typical servo sector in the read / write direction, but not between the short servo sector and the next servo sector in the read / write direction. In other words, when multiple servo sectors (SS) include both normal servo sectors and short servo sectors, the signal strength recording data (SIS) is adjacent to the normal servo sector in the read / write direction, but not adjacent to the short servo sector in the read / write direction.

[0044] Figure 4 This is a schematic diagram showing an example of disk 10 and head 15 before expansion. Figure 4 In the middle, the rotation direction B of disk 10 is consistent with the direction of airflow C. Figure 4 The direction Z is shown as the direction corresponding to the thickness or height. Hereinafter, the direction from the head 15 toward the disk 10 in direction Z will sometimes be referred to as the downward direction (or simply downward), and the direction from the disk 10 toward the head 15 in direction Z will be referred to as the upward direction (or simply upward).

[0045] The head 15 has a slider 150. The slider 150 is formed, for example, from a sintered body of alumina and titanium carbide (AlTiC). The slider 150 has a disk-facing surface (air-supported surface (ABS)) 15S opposite to the surface 10S of the disk 10 and a trailing end 151 located on the outflow side of the airflow C. The slider 150 has a write head 15W, a read head 15R, and a heater 15H. A portion of the write head 15W and the read head 15R are exposed on the disk-facing surface 15S.

[0046] The write head 15W is excited and magnetized by a predetermined current (write current or recording current). The write head 15W uses the magnetic flux flowing in the magnetized portion to change the magnetization direction of the recording bits of the magnetic recording layer of the disk 10, thereby recording a magnetization pattern corresponding to the recording current on the disk 10.

[0047] like Figure 4 As shown, when the heater 15H is not heating up, the WRP around the write head 15W and the read head 15R (hereinafter sometimes referred to as the recording and playback section) does not protrude toward the disk 10. Hereinafter, the distance between the disk 10 and the head 15 in the Z direction, such as the lowest part of the head 15 (around the write head 15W and the read head 15R) (hereinafter sometimes referred to as the lowest floating point) is sometimes referred to as the "float amount".

[0048] Figure 5 This is a schematic diagram showing an example of disk 10 and the expanded head 15.

[0049] like Figure 5 As shown, when the heater 15H is heating up, the recording and playback unit WRP expands due to the heat of the heater 15H (thermal expansion) and protrudes towards the disk 10. In this case, the apex of the thermally expanded recording and playback unit WRP becomes the lowest point of suspension of the head 15.

[0050] The driver IC20 controls the driving of SPM12 and VCM14 according to the control of the system controller 130 (specifically, MPU40 described later).

[0051] The head amplifier IC (preamplifier) ​​30 includes a read amplifier and a write driver. The read amplifier amplifies the read signal read from disk 10 and outputs it to the system controller 130 (specifically, the read / write (R / W) channel 40 described later). The write driver outputs a write current to head 15 corresponding to the signal output from R / W channel 40.

[0052] Volatile memory 70 is a semiconductor memory whose stored data is lost when the power supply is disconnected. Volatile memory 70 stores data required for processing in various parts of disk drive 1. Volatile memory 70 is, for example, DRAM (Dynamic Random Access Memory) or SDRAM (Synchronous Dynamic Random Access Memory).

[0053] Non-volatile memory 80 is a semiconductor memory that records stored data even when the power supply is disconnected. Non-volatile memory 80 is, for example, a NOR or NAND type flash ROM (Flash Read Only Memory).

[0054] The buffer memory 90 is a semiconductor memory that temporarily records data transmitted and received between the disk drive 1 and the host computer 100. Furthermore, the buffer memory 90 may be integrated with the volatile memory 70. The buffer memory 90 may be, for example, DRAM, SRAM (Static Random Access Memory), SDRAM, FeRAM (Ferroelectric Random Access Memory), or MRAM (Magnetoresistive Random Access Memory).

[0055] The system controller (controller) 130 is implemented, for example, using a large-scale integrated circuit (LSI) called a system-on-a-chip (SoC), which integrates multiple components onto 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, for example, to a driver IC 20, a head amplifier IC 30, volatile memory 70, non-volatile memory 80, a buffer memory 90, and a host 100.

[0056] R / W channel 40 performs signal processing on data transferred from disk 10 to host 100 (hereinafter sometimes referred to as read data) and data transferred from host 100 (hereinafter sometimes referred to as write data) according to instructions from MPU 60 (described later). R / W channel 40 has circuitry or functions for modulating write data. R / W channel 40 has circuitry or functions for measuring and demodulating the signal quality of read data. R / W channel 40 is electrically connected, for example, to head amplifier IC 30, HDC 50, and MPU 60.

[0057] HDC50 controls data transfer. For example, HDC50 controls data transfer between host 100 and disk 10 according to instructions from MPU60 (described later). HDC50 is electrically connected to, for example, R / W channel 40, MPU60, volatile memory 70, non-volatile memory 80, and buffer memory 90.

[0058] MPU60 is the main controller that controls the various parts of disk drive 1. MPU60 controls VCM14 via driver IC20, performing servo control for positioning head 15. MPU60 controls SPM12 via driver IC20, causing disk 10 to rotate. MPU60 controls write operations that write data to disk 10 and selects the destination for data transferred from host 100, such as write data. MPU60 controls read operations that read data from disk 10 and controls the processing of data transferred from disk 10 to host 100, such as read data. Additionally, MPU60 manages the areas where data is recorded. MPU60 is connected to various parts of disk drive 1. MPU60 is electrically connected to, for example, driver IC20, R / W channel 40, and HDC50.

[0059] The MPU60 includes a read / write control unit 610, a float control unit 620, and an HFW (High Fly write) detection unit 630. The MPU60 executes the processing of each unit, such as the read / write control unit 610, the float control unit 620, and the HFW detection unit 630, on the firmware. Alternatively, the MPU60 can also include each unit, such as the read / write control unit 610, the float control unit 620, and the HFW detection unit 630, as a circuit. The read / write control unit 610, the float control unit 620, and the HFW detection unit 630 can also be included in the R / W channel 40 or the HDC50.

[0060] The read / write control unit 610 controls the read processing of data read from disk 10 and the write processing of data written to disk 10 according to commands from host 100. The read / write control unit 610 controls VCM 14 via driver IC 20 to position head 15 at a predetermined location on disk 10 and perform read or write processing. Hereinafter, the term "access" will sometimes be used to mean that it includes recording or writing data to a predetermined area (write processing), reading or retrieving data from a predetermined area (read processing), and moving head 15 to a predetermined area.

[0061] The suspension control unit 620 controls the suspension amount of the head 15. The suspension control unit 620 controls the suspension amount of the head 15 (e.g., the recording / reproduction unit WRP) by controlling the applied current (or voltage) from the ab-head amplifier IC30 to the heater 15H. The suspension control unit 620 controls the suspension amount of the head 15 to a predetermined suspension amount (hereinafter sometimes referred to as the normal suspension amount) that allows for normal data writing or reading processing.

[0062] The HFW detection unit 630 detects High Fly Write (HFW). HFW occurs when the write head 15 comes into contact with contaminants generated on the disk 10, causing a float level higher than normal (hereinafter sometimes referred to as high float level or abnormal float level). In a predetermined area of ​​the disk 10, the magnetization in the write head 15W becomes insufficient to overwrite the disk 10, thus preventing normal data writing to that area and resulting in a read error when reading from that area.

[0063] The HFW detection unit 630 writes or records signal strength recording data (SIS) corresponding to each servo sector SS as a component of RRO. The HFW detection unit 630 continuously writes the signal strength recording data (SIS) corresponding to a predetermined servo sector SS immediately after the predetermined servo sector SS or a servo sector SS different from the predetermined servo sector SS (hereinafter sometimes referred to as other servo sectors) in the read / write direction. In other words, the HFW detection unit 630 writes the signal strength recording data (SIS) corresponding to the predetermined servo sector SS to the signal strength recording area immediately after the predetermined servo sector SS or other servo sector SS in the read / write direction. Furthermore, the HFW detection unit 630 can continuously write the signal strength recording data (SIS) corresponding to the predetermined servo sector SS immediately after the read / write direction of that servo sector SS, or it can continuously write it immediately after the read / write direction of other servo sector SSs. In addition, the HFW detection unit 630 can record the signal strength recording data SIS corresponding to the predetermined servo sector SS to an area other than the signal strength recording area immediately following the read / write direction of the servo sector SS, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90. Alternatively, it can record it to an area other than the servo sector SS that is immediately following the signal strength recording area in the read / write direction, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0064] The HFW detection unit 630, for example, continuously writes signal strength recording data (hereinafter sometimes referred to as next signal strength recording data) SIS corresponding to the next servo sector (hereinafter sometimes referred to as the next servo sector) configured after the current servo sector (hereinafter sometimes referred to as the current servo sector) SS in the read / write direction of the current servo sector SS, immediately after it. The HFW detection unit 630 may also continuously write the signal strength recording data (hereinafter sometimes referred to as current signal strength recording data) SIS corresponding to the current servo sector SS immediately after it in the read / write direction of the current servo sector SS. Furthermore, the HFW detection unit 630 may continuously write the current signal strength recording data SIS corresponding to the current servo sector SS immediately after it in the read / write direction of the current servo sector SS, or it may continuously write it immediately after it in the read / write direction of other servo sectors SS besides the current servo sector SS. In addition, the HFW detection unit 630 can write the current signal strength recording data SIS corresponding to the current servo sector SS to a region outside the immediately following signal strength recording region in the read / write direction of the current servo sector SS, or it can write it to a region outside the immediately following signal strength recording region in the read / write direction of other servo sectors SS besides the current servo sector SS.

[0065] During write processing, the HFW detection unit 630 detects HFW by monitoring the frequency components or ratios of the target servo reproduced signal. When reading a predetermined area where data has been written with the high slack head 15, the amplitude of the reproduced signal during reading of that area decreases. Consequently, the frequency components of the reproduced signal decrease, or the ratio of the fundamental frequency to the third harmonic of the reproduced signal changes.

[0066] During write processing, the HFW detection unit 630 normalizes the signal strength (hereinafter sometimes referred to as the object servo reproduction signal strength) of the target servo reproduction signal of the currently read servo sector SS when reading a predetermined servo sector SS. During write processing, the HFW detection unit 630 normalizes the object servo reproduction signal strength corresponding to the currently read servo sector SS based on the signal strength recording data SIS corresponding to the servo sector SS that was previously written to the object region of the servo sector SS. For example, during write processing, the HFW detection unit 630 normalizes the object servo reproduction signal strength by dividing or subtracting the signal strength recording data SIS corresponding to the predetermined servo sector SS. In other words, during the write process, the HFW detection unit 630 divides or subtracts the signal strength recording data SIS corresponding to the predetermined servo sector SS from the target servo reproduced signal strength, and calculates the standardized target servo reproduced signal strength (hereinafter sometimes referred to as the standardized reproduced signal strength) corresponding to the servo sector SS.

[0067] The signal strength recording data SIS corresponding to a predetermined servo sector SS and the target servo reproduced signal strength corresponding to that servo sector SS are, for example, the signal strength when the same data in the same area of ​​that servo sector is read at different time intervals. Furthermore, the signal strength recording data SIS corresponding to a predetermined servo sector SS and the target servo reproduced signal strength corresponding to that servo sector SS can also be the signal strength when the same data in the same area or different areas of that servo sector SS is read, or different data in those areas.

[0068] The object servo reproduced signal strength, for example, is a value obtained by performing a Fourier transform on the object servo reproduced signal, similar to the signal strength recording data SIS. The object servo reproduced signal strength, for example, is a value obtained by performing Fourier transforms on the object servo reproduced signal and the ideal signal, or the demodulated signal, respectively, followed by a division operation, similar to the signal strength recording data SIS. The object servo reproduced signal strength, for example, is a half-harmonic obtained by performing a Fourier transform on the preamble as a 2T mode, similar to the signal strength recording data SIS, and is the fundamental frequency or nth higher harmonic obtained by performing a Fourier transform on the reproduced signal (object servo reproduced signal) of the Sync Mark / Gray Code / RRO and the ideal signal or the demodulated signal, followed by a division operation. The object servo reproduced signal strength, for example, is the amplitude of the object servo reproduced signal (sometimes referred to as the object servo reproduced signal amplitude below), similar to the signal strength recording data SIS.

[0069] For example, during write processing, when the HFW detection unit 630 reads the current servo sector SS, it standardizes the signal strength (hereinafter sometimes referred to as the current object servo reproduction signal strength) of the object servo reproduction signal (hereinafter sometimes referred to as the current object servo reproduction signal) corresponding to the currently read servo sector. During write processing, when the HFW detection unit 630 reads the current servo sector SS, it standardizes the current object servo reproduction signal strength corresponding to the current servo sector SS based on the current signal strength recording data SIS. For example, during write processing, the HFW detection unit 630 standardizes the current object servo reproduction signal strength by dividing or subtracting the current signal strength recording data SIS from the current object servo reproduction signal strength corresponding to the current servo sector SS. In other words, during write processing, the HFW detection unit 630 calculates the standardized current object servo reproduction signal strength (hereinafter sometimes referred to as the current standardized reproduction signal strength) by dividing or subtracting the current signal strength recording data SIS from the current object servo reproduction signal strength corresponding to the current servo sector SS.

[0070] The HFW detection unit 630 determines whether the normalized reproducible signal strength corresponding to the predetermined servo sector SS is less than or greater than a threshold (hereinafter sometimes referred to as the HFW threshold), or greater than or less than the HFW threshold (or less than or greater than the HFW threshold). For example, the HFW detection unit 630 determines whether the current normalized reproducible signal strength corresponding to the current servo sector SS is less than or greater than the HFW threshold (or less than or greater than the HFW threshold).

[0071] The HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 if it determines that the normalized reproduction signal strength corresponding to a predetermined servo sector SS is less than (or below) the HFW threshold. The HFW detection unit 630 also determines that an HFW has occurred in a predetermined area of ​​disk 10 if it determines that the normalized reproduction signal strength corresponding to the predetermined servo sector SS is greater than or equal to the HFW threshold. For example, the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 if it determines that the current normalized reproduction signal strength corresponding to the current servo sector is less than (or below) the HFW threshold. Finally, the HFW detection unit 630 determines that no HFW has occurred in a predetermined area of ​​disk 10 if it determines that the current normalized reproduction signal strength corresponding to the current servo sector is greater than or equal to the HFW threshold.

[0072] Furthermore, the HFW detection unit 630 can also determine that an HFW has occurred in a predetermined area of ​​the disk 10 if it determines that the normalized reproduction signal strength corresponding to the predetermined servo sector SS is greater than (or above) the HFW threshold. The HFW detection unit 630 can also determine that an HFW has occurred in a predetermined area of ​​the disk 10 if it determines that the normalized reproduction signal strength corresponding to the predetermined servo sector SS is less than (or below) the HFW threshold.

[0073] If the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​the disk 10, it stops writing to that predetermined area. For example, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​the disk 10, it stops writing to that predetermined area and performs a rewrite operation on the predetermined area of ​​the disk 10.

[0074] For example, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 based on the normalized reproduction signal strength corresponding to a predetermined servo sector SS, it stops writing to the predetermined area of ​​disk 10 and performs rewrite processing on the predetermined area of ​​disk 10. For example, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 based on the signal strength recorded data corresponding to a predetermined servo sector SS, it stops writing to the predetermined area of ​​disk 10 and performs rewrite processing on the data sector area DSR immediately preceding that servo sector SS.

[0075] In addition, for example, if the HFW detection unit 630 determines that an HFW has been generated in a predetermined area of ​​disk 10, it stops writing in the predetermined area of ​​disk 10 and performs a process of recording or saving the data in the predetermined area of ​​disk 10 to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80 or buffer memory 90 (hereinafter sometimes referred to as transfer processing).

[0076] For example, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 based on the normalized reproduction signal strength corresponding to a predetermined servo sector SS, it stops writing in the predetermined area of ​​disk 10 and performs a transfer process to transfer the data of the predetermined area of ​​disk 10 to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90. For example, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 based on the signal strength recorded data corresponding to a predetermined servo sector SS, it stops writing in the predetermined area of ​​disk 10 and performs a transfer process to transfer the data of the data sector area DSR immediately preceding that servo sector SS to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0077] Figure 6 This is a schematic diagram illustrating an example of the configuration of the Signal Strength Recording Data (SIS) involved in this embodiment. Figure 6 The image shows track TRm. Track TRm contains servo sectors SS(k-1), SS(k), and SS(k+1) and signal strength recording data SIS(k), SIS(k+1), and SIS(k+2). Figure 6 In this configuration, servo sectors SS(k-1), SS(k), and SS(k+1) are arranged with a gap in the read / write direction, in the order described. In other words, servo sector SS(k) is arranged with a gap between it and servo sector SS(k-1) in the read / write direction. Servo sector SS(k+1) is arranged with a gap between it and servo sector SS(k) in the read / write direction. Figure 6In the diagram, signal strength recording data SIS(k), SIS(k+1), and SIS(k+2) are arranged with a gap in the read / write direction in the order they are recorded. In other words, signal strength recording data SIS(k+1) is arranged with a gap between signal strength recording data SIS(k) in the read / write direction. Signal strength recording data SIS(k+2) is arranged with a gap between signal strength recording data SIS(k+1) in the read / write direction. Signal strength recording data SIS(k) is located between servo sectors SS(k-1) and SS(k), and is adjacent to servo sector SS(k-1) in the read / write direction. Signal strength recording data SIS(k) corresponds to servo sector SS(k). Signal strength recording data SIS(k+1) is located between servo sectors SS(k) and SS(k+1), and is adjacent to servo sector SS(k) in the read / write direction. Signal strength recording data SIS(k+1) corresponds to servo sector SS(k+1). The signal strength recording data SIS(k+2) is adjacent to the servo sector SS(k+1) in the read / write direction. The signal strength recording data SIS(k+2) corresponds to the next servo sector SS(k+2) after the servo sector SS(k+1) (not shown).

[0078] exist Figure 6 In the example shown, the MPU60 writes signal strength recording data SIS(k) adjacent to servo sector SS(k-1) in the read / write direction on track TRm, writes signal strength recording data SIS(k+1) adjacent to servo sector SS(k) in the read / write direction, and writes signal strength recording data SIS(k+2) adjacent to servo sector SS(k+1) in the read / write direction. In other words, the MPU60 writes signal strength recording data SIS(k) immediately following servo sector SS(k-1) in track TRm, writes signal strength recording data SIS(k+1) immediately following servo sector SS(k), and writes signal strength recording data SIS(k+2) immediately following servo sector SS(k+1).

[0079] Figure 7 This is a schematic diagram illustrating an example of the HFW detection method according to this embodiment. Figure 7 The track TRm shown is Figure 6 The track TRm shown corresponds to this. Figure 7 The HFW threshold HTH is shown in the figure. Figure 7 In this context, the signal strength recording data SIS(k-1) is equivalent to the signal strength recording data corresponding to the servo sector SS(k-1).

[0080] exist Figure 7In the example shown, during the write processing of track TRm, the MPU60 reads the signal strength record data SIS(k-1) corresponding to the servo sector SS(k-1). The MPU60 reads the target servo reproduced signal strength corresponding to the servo sector SS(k-1). Based on the signal strength record data SIS(k-1) corresponding to the servo sector SS(k-1), the MPU60 normalizes the target servo reproduced signal strength corresponding to the servo sector SS(k-1) to a normalized reproduced signal strength. The MPU60 determines whether the normalized reproduced signal strength corresponding to the servo sector SS(k-1) is less than or greater than the HFW threshold HTH.

[0081] exist Figure 7 In the example shown, when the MPU60 determines that the normalized reproduction signal strength corresponding to the servo sector SS(k-1) is smaller than the HFW threshold HTH, it stops writing in the data sector region DSR(k-1) corresponding to the servo sector SS(k-1) of disk 10 and performs rewriting processing on the data sector region DSR(k-1) corresponding to the servo sector SS(k-1).

[0082] exist Figure 7 In the example shown, during write processing, the MPU60 reads the target servo reproduced signal strength of servo sector SS(k-1) and reads the signal strength recording data SIS(k). During write processing, the MPU60 reads the target servo reproduced signal strength of servo sector SS(k). Based on the signal strength recording data SIS(k) corresponding to servo sector SS(k), the MPU60 normalizes the target servo reproduced signal strength corresponding to servo sector SS(k) to a normalized reproduced signal strength. The MPU60 determines whether the normalized reproduced signal strength corresponding to servo sector SS(k) is less than or greater than the HFW threshold HTH.

[0083] exist Figure 7 In the example shown, when the MPU60 determines that the normalized reproduction signal strength corresponding to the servo sector SS(k) is smaller than the HFW threshold HTH, it stops writing to the data sector region DSR(k) corresponding to the servo sector SS(k) on disk 10 and performs rewriting processing on the data sector region DSR(k) corresponding to the servo sector SS(k).

[0084] exist Figure 7In the example shown, during write processing, the MPU60 reads the target servo reproduced signal strength of servo sector SS(k) and reads the signal strength recording data SIS(k+1). Based on the signal strength recording data SIS(k+1) corresponding to servo sector SS(k+1), the MPU60 normalizes the target servo reproduced signal strength corresponding to servo sector SS(k+1) to a normalized reproduced signal strength. The MPU60 determines whether the normalized reproduced signal strength corresponding to servo sector SS(k+1) is less than or greater than the HFW threshold HTH.

[0085] exist Figure 7 In the example shown, when the MPU60 determines that the normalized reproduction signal strength corresponding to the servo sector SS(k+1) is smaller than the HFW threshold HTH, it stops writing to the data sector region DSR(k+1) of disk 10 corresponding to the servo sector SS(k+1) and performs rewriting processing on the data sector region DSR(k+1) corresponding to the servo sector SS(k+1).

[0086] like Figure 7 As shown, the MPU60 minimizes the latency of write failure determination by reading and demodulating the signal strength record data SIS immediately following the current target servo sector (hereinafter sometimes referred to as the previous servo sector) in the read / write direction of the current servo sector SS, normalizing the current target servo reproduced signal strength of the current servo sector.

[0087] Figure 8 This is a schematic diagram illustrating an example of the change in the object servo reproduction signal strength of each servo sector SS relative to each servo sector SS when reading the SS of each servo sector SS written with normal and high float values ​​(head 15). Figure 8 In the diagram, the horizontal axis represents the servo sector (SS), and the vertical axis represents the signal strength of the object's servo reproduction. Figure 8 On the vertical axis, the object servo reproduction signal strength increases as it moves towards the tip of the larger arrow and decreases as it moves towards the tip of the smaller arrow. Figure 7The diagram shows the change in the object servo reproduction signal strength (USL) of each servo sector SS relative to each servo sector SS when each servo sector SS was written with the head 15 of normal float (hereinafter sometimes referred to as the change in object servo reproduction signal strength corresponding to normal float), and the change in the object servo reproduction signal strength (HSL) of each servo sector SS relative to each servo sector SS when each servo sector SS was written with the head 15 of high float (hereinafter sometimes referred to as the change in object servo reproduction signal strength corresponding to high float). Figure 8 The threshold value (hereinafter sometimes referred to as the reproducible signal strength threshold) STH for the object servo is shown in the figure. Figure 8 As shown, for example, the waveform of the change in object servo reproduced signal strength USL corresponding to normal float and the waveform of the change in object servo reproduced signal strength HSL corresponding to high float are similar in shape. In other words, the waveform of the object servo reproduced signal strength corresponding to normal float and the waveform of the object servo reproduced signal strength corresponding to high float are similar in shape.

[0088] exist Figure 8 In the example shown, the change in object servo reproducible signal strength USL corresponding to normal levitation and the change in object servo reproducible signal strength HSL corresponding to high levitation both have portions larger than the reproducible signal strength threshold STH and portions smaller than the reproducible signal strength threshold STH. Therefore, as Figure 8 As shown, it is difficult to determine HFW based on a threshold and the signal strength of the object servo reproduction signal.

[0089] Figure 9 This is a schematic diagram illustrating an example of the variation in the normalized reproducible signal strength relative to each servo sector SS when reading the SS of each servo sector written with normal and high float values ​​(first 15). Figure 9 In the diagram, the horizontal axis represents the servo sector (SS), and the vertical axis represents the normalized reproducible signal strength. Figure 9 On the vertical axis, the normalized reproducible signal strength increases as it moves towards the tip of the larger arrow and decreases as it moves towards the tip of the smaller arrow. Figure 9The diagram shows the variation of the normalized reproducible signal strength (NUSL) relative to each servo sector SS when each servo sector SS was read using the header 15 with normal float (sometimes referred to as the variation of the normalized reproducible signal strength corresponding to normal float), and the variation of the normalized reproducible signal strength (NHSL) relative to each servo sector SS when each servo sector SS was read using the header 15 with high float (sometimes referred to as the variation of the normalized reproducible signal strength corresponding to high float). Figure 9 The HFW threshold HTH is shown in the figure.

[0090] exist Figure 9 In the example shown, the normalized reproducible signal intensity (NUSL) corresponding to normal suspension volume is greater than the HFW threshold (HTH). Conversely, the normalized reproducible signal intensity (NHSL) corresponding to high suspension volume is smaller than the HFW threshold (HTH). Therefore, HFW can be determined based on the normalized reproducible signal intensity.

[0091] MPU60 determines whether the normalized reproducible signal strength corresponding to a predetermined servo sector SS is less than or greater than the HFW threshold. If MPU60 determines that the normalized reproducible signal strength corresponding to the predetermined servo sector SS is less than the HFW threshold, it determines that HFW has occurred. If MPU60 determines that the normalized reproducible signal strength corresponding to the predetermined servo sector SS is greater than or greater than the HFW threshold, it determines that HFW has not occurred.

[0092] Figure 10 This is a schematic diagram illustrating an example of how BER (Bit Error Rate) changes relative to BPI (Bits Per Inch). Figure 10 In the graph, the horizontal axis represents BPI (Bits Per Inch), and the vertical axis represents BER (Bit Error Rate). Figure 10 On the horizontal axis, BPI increases as it moves towards the tip of the arrow and decreases as it moves towards the opposite side. Figure 10 The horizontal axis represents BPI BP1 and BP2. BPI BP2 is larger than BPI BP1. Figure 10 On the vertical axis, BER increases as it moves towards the tip of the arrow and decreases as it moves towards the opposite side. Figure 10The vertical axis shows BER BE1, BE2, and BEs. BER BE2 is larger than BER BE1. BER BEs is larger than BER BE2. BER BEs, for example, corresponds to the BER of a disk device 1 that is set to prevent unrecoverable errors as unreadable errors. Figure 10 The diagram shows the change in BER relative to BPI (hereinafter sometimes referred to as the change in BER corresponding to normal FORM) BRLU when a predetermined area of ​​data written with the head 15 of normal FORM is read, and the change in BER relative to BPI (hereinafter sometimes referred to as the change in BER corresponding to high FORM) BRLH when a predetermined area of ​​data written with the head 15 of high FORM is read.

[0093] exist Figure 10 In the example shown, when the HFW detection method involved in this embodiment is not applied, it is necessary to consider the situation where HFW is generated and set BPI to BPI BP1 so that it becomes BER BE1 with a certain margin relative to BER BEs.

[0094] exist Figure 10 In the example shown, when applying the HFW detection method according to this embodiment, the necessity to consider the occurrence of HFW is reduced. Therefore, for example, BPI can be set to BPI BP2 so that BER becomes BER2. That is, by applying the HFW detection method according to this embodiment, BPI can be improved.

[0095] Figure 11 This is a schematic diagram illustrating an example of how ADC (Area Density Capability) changes relative to BPI. Figure 11 In the graph, the horizontal axis represents BPI, and the vertical axis represents ADC (Area Density Capability). ADC is equivalent to the product of BPI and TPI (Track Per Inch) (BPI × TPI). Figure 11 On the horizontal axis, BPI increases as it moves towards the tip of the arrow and decreases as it moves towards the opposite side. Figure 11 The horizontal axis shows BP1 and BP2. Figure 11 On the vertical axis, the ADC increases as it moves towards the tip of the arrow and decreases as it moves towards the opposite side. Figure 11 The vertical axis represents ADCs AD1 and AD2. ADC AD2 is larger than ADC AD1. Figure 11 The diagram shows the variation of the ADC in disk device 1 relative to the BPI (hereinafter sometimes referred to as the variation of the ADC) ADL.

[0096] exist Figure 11 In the example shown, when BPI is BP1, ADC becomes AD1. There is a predetermined interval between the maximum value of ADC and ADC AD1. That is, in disk device 1, ADC incurs a loss. When BPI is set to BP2, ADC becomes AD2. When ADC becomes AD2, the loss of ADC in disk device 1 can be reduced.

[0097] Figure 12 This is a flowchart illustrating an example of the HFW detection method according to this embodiment.

[0098] During write processing, MPU60 reads the signal strength recording data SIS (B1201) corresponding to a predetermined servo sector SS, and reads the target servo reproduced signal strength of that servo sector SS (B1202). Based on the signal strength recording data SIS, MPU60 normalizes the target servo reproduced signal strength to a normalized reproduced signal strength (B1203). For example, MPU60 calculates the normalized reproduced signal strength by subtracting or dividing the target servo reproduced signal strength corresponding to the predetermined servo sector SS from the signal strength recording data SIS. MPU60 determines whether the normalized reproduced signal strength corresponding to the predetermined servo sector SS is less than or greater than the HFW threshold (B1204). If it determines that the normalized reproduced signal strength corresponding to the predetermined servo sector SS is greater than or greater than the HFW threshold (B1204: No), MPU60 determines that no HFW has been generated in the predetermined area and ends the process. If the MPU60 determines that the normalized reproducible signal strength corresponding to the predetermined servo sector SS is less than the HFW threshold (B1204: Yes), it determines that an HFW has occurred in the predetermined area, stops the write process in that area (B1205), and ends the process. For example, if the MPU60 determines that the normalized reproducible signal strength corresponding to the predetermined servo sector SS is less than the HFW threshold, it stops the write process in that area, performs a rewrite process on the predetermined area, or performs a transfer process on the predetermined area, and ends the process.

[0099] According to this embodiment, during write processing, the disk device 1 reads signal strength recording data SIS corresponding to a predetermined servo sector SS, and reads the target servo reproduced signal strength of that servo sector SS. Based on the signal strength recording data SIS, the disk device 1 normalizes the target servo reproduced signal strength to a normalized reproduced signal strength. The disk device 1 determines whether the normalized reproduced signal strength is less than or greater than the HFW threshold HTH. If it is determined that the normalized reproduced signal strength is less than the HFW threshold HTH, the MPU 60 determines that an HFW has occurred in a predetermined area, stops write processing in that area, performs rewrite processing on the predetermined area, or performs transfer processing on the predetermined area. Therefore, the disk device 1 can improve BPI. In addition, the disk device 1 can improve reliability.

[0100] Next, other embodiments and variations of the disk drive will be described. In these other embodiments and variations, the same reference numerals are used for parts that are the same as those in the first embodiment described above, and detailed descriptions thereof are omitted.

[0101] (Variation Example 1)

[0102] The HFW detection method of the disk device 1 involved in Variation Example 1 is different from that of the disk device 1 involved in the aforementioned embodiments.

[0103] For example, during write processing, the MPU60 averages the predetermined target servo reproduced signal strength corresponding to a predetermined servo sector SS and the target servo reproduced signal strength (hereinafter sometimes referred to as other target servo reproduced signal strengths) corresponding to other servo sectors SS that are different from this servo sector SS, and calculates the target servo reproduced signal strength (hereinafter sometimes referred to as averaged servo reproduced signal strength) corresponding to the predetermined servo sector SS. During write processing, the MPU60 averages the predetermined signal strength recording data SIS corresponding to the predetermined servo sector SS and the signal strength recording data (hereinafter sometimes referred to as other signal strength recording data) SIS corresponding to other servo sectors SS, and calculates the signal strength recording data (hereinafter sometimes referred to as averaged signal strength recording data) SIS corresponding to the predetermined servo sector SS. During write processing, the MPU60 normalizes the averaged servo reproduced signal strength corresponding to the predetermined servo sector SS and other servo sector SS based on the averaged signal strength recording data SIS corresponding to the predetermined servo sector SS and other servo sector SS. For example, during write processing, the MPU60 normalizes the averaged servo reproduced signal strength by dividing or subtracting the averaged signal strength recorded data SIS corresponding to the predetermined servo sector SS and other servo sectors SS. In other words, during write processing, the MPU60 calculates the normalized reproduced signal strength (hereinafter sometimes referred to as the averaged normalized reproduced signal strength) corresponding to the predetermined servo sector SS and other servo sectors SS by dividing or subtracting the averaged signal strength recorded data SIS corresponding to the predetermined servo sector SS and other servo sectors SS.

[0104] Furthermore, when the disk device 1 is a TDMR type disk device, the MPU60 can also, during write processing, average the multiple target servo reproduction signal strengths corresponding to predetermined servo sectors SS that have been read by the multiple read heads 15R mounted on the head 15, and calculate the averaged servo reproduction signal strength corresponding to the predetermined servo sectors SS. In this case, the MPU60 can also, during write processing, average the multiple signal strength recording data SIS corresponding to predetermined servo sectors SS that have been read by the multiple read heads 15R mounted on the head 15, and calculate the averaged signal strength recording data SIS corresponding to the predetermined servo sectors SS.

[0105] For example, during write processing, the MPU60 averages the current target servo reproduced signal strength corresponding to the current servo sector SS and the target servo reproduced signal strength corresponding to the previous servo sector SS (hereinafter sometimes referred to as the previous target servo reproduced signal strength), calculating the target servo reproduced signal strength corresponding to the current servo sector SS and the previous servo sector SS (hereinafter sometimes referred to as the current averaged servo reproduced signal strength). During write processing, the MPU60 averages the current signal strength record data SIS corresponding to the current servo sector SS and the signal strength record data SIS corresponding to the previous servo sector SS (hereinafter sometimes referred to as the previous signal strength record data), calculating the signal strength record data SIS corresponding to the current servo sector SS and the previous servo sector SS (hereinafter sometimes referred to as the current averaged signal strength record data). During write processing, the MPU60 normalizes the current averaged servo reproduced signal strength corresponding to the current servo sector SS and the previous servo sector SS based on the current averaged signal strength record data SIS. For example, during write processing, the MPU60 normalizes the current averaged servo reproduced signal strength by dividing or subtracting the current averaged signal strength recorded data SIS. In other words, during write processing, the MPU60 calculates the current normalized reproduced signal strength corresponding to the current servo sector SS and the previous servo sector SS by dividing or subtracting the current averaged signal strength recorded data SIS.

[0106] For example, if the MPU60 determines that an HFW (High-Frequency Wave) has occurred in a predetermined area of ​​disk 10 based on the averaged normalized reproduction signal strength corresponding to a predetermined servo sector SS and other servo sectors SS, it stops writing in the predetermined area of ​​disk 10 and performs a rewrite process from the DSR (Data Sector Region) corresponding to the other servo sectors SS (hereinafter sometimes referred to as other data sector regions) of disk 10 to the DSR of the data sector region corresponding to the predetermined servo sectors SS. For example, if the MPU60 determines that an HFW has occurred in the other data sector region corresponding to the other servo sectors SS and the predetermined data sector region corresponding to the predetermined servo sectors SS based on the averaged signal strength corresponding to the predetermined servo sectors SS, it stops writing in the other data sector region corresponding to the other servo sectors SS and the predetermined data sector region corresponding to the predetermined servo sectors SS of disk 10, and performs a rewrite process from the other data sector region to the predetermined data sector region.

[0107] For example, if the MPU60 determines that an HFW has occurred in a predetermined area of ​​disk 10 based on the averaged normalized reproduction signal strength corresponding to the predetermined servo sector SS and other servo sectors SS, it stops writing in the predetermined area of ​​disk 10 and performs a transfer process to transfer the data of disk 10 from the data sector area (hereinafter sometimes referred to as other data sector area) DSR corresponding to other servo sectors SS to the data sector area DSR corresponding to the predetermined servo sector SS to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80 or buffer memory 90. For example, if the MPU60 determines, based on the averaged signal strength recording data corresponding to the predetermined servo sector SS and other servo sectors SS, that an HFW has occurred in other data sector areas corresponding to other servo sectors SS and predetermined data sector areas corresponding to the predetermined servo sectors SS on disk 10, it stops writing operations in the other data sector areas corresponding to other servo sectors SS and predetermined data sector areas corresponding to the predetermined servo sectors SS on disk 10, and performs a transfer process to transfer the data from the other data sector area to the predetermined data sector area to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0108] Figure 13 This is a flowchart illustrating an example of the HFW detection method involved in Variation 1.

[0109] During write processing, MPU60 reads other signal strength record data SIS (B1301) corresponding to other servo sectors SS that are different from the predetermined servo sector, and reads other object servo reproduced signal strengths (B1302) corresponding to other servo sectors SS. MPU60 reads predetermined signal strength record data SIS (B1303) corresponding to the predetermined servo sector SS, and reads predetermined object servo reproduced signal strengths (B1304) corresponding to the predetermined servo sector SS. MPU60 averages the predetermined signal strength record data SIS and other signal strength record data SIS to calculate averaged signal strength record data SIS (B1305). MPU60 averages the predetermined object servo reproduced signal strength and other object servo reproduced signal strengths to calculate averaged servo reproduced signal strength (B1306). Based on this averaged signal strength record data SIS, MPU60 normalizes the averaged servo reproduced signal strength to an averaged normalized reproduced signal strength (B1307). MPU60 determines whether the averaged normalized reproducible signal strength corresponding to the predetermined servo sector SS and other servo sector SS is less than or greater than the HFW threshold (B1308). If it determines that the averaged normalized reproducible signal strength corresponding to the predetermined servo sector SS and other servo sector SS is greater than or greater than the HFW threshold (B1308: No), MPU60 determines that no HFW has been generated in the predetermined area and ends the process. If it determines that the averaged normalized reproducible signal strength corresponding to the predetermined servo sector SS and other servo sector SS is less than the HFW threshold (B1308: Yes), MPU60 determines that HFW has been generated in the predetermined area, stops the write process in that area (B1309), and ends the process.

[0110] According to Variation 1, during write processing, disk device 1 averages the servo reproduction signal strength of a predetermined target sector and the servo reproduction signal strengths of other targets to calculate an averaged servo reproduction signal strength. Based on this averaged signal strength, disk device 1 records data SIS and normalizes the averaged servo reproduction signal strength to a normalized reproduction signal strength. Disk device 1 determines whether the averaged normalized reproduction signal strength corresponding to the predetermined servo sector SS and other servo sectors SS is less than the HFW threshold or greater than the HFW threshold HTH. If the averaged normalized signal strength is determined to be smaller than the HFW threshold HTH, the disk device 1 determines that an HFW has occurred in a predetermined data sector region DSR corresponding to a predetermined servo sector SS and in other data sector regions DSR corresponding to other servo sectors SS. It then stops write processing in these regions and performs either a rewrite or a transfer process. Therefore, the disk device 1 can improve the BPI (Block Principle Indicator). Furthermore, the disk device 1 can improve reliability.

[0111] (Variation Example 2)

[0112] The HFW detection method of the disk device 1 involved in Variation Example 2 is different from that of the disk device 1 involved in the aforementioned embodiments.

[0113] For example, during write processing, the MPU60 normalizes the predetermined object servo reproduction signal strength corresponding to the predetermined servo sector SS to a predetermined signal strength (hereinafter sometimes referred to as object-normalized signal strength) based on the predetermined signal strength recording data SIS corresponding to the predetermined servo sector SS. During write processing, the MPU60 normalizes the other object servo reproduction signal strength corresponding to other servo sectors SS to a predetermined signal strength (hereinafter sometimes referred to as other normalized signal strength) based on the other signal strength recording data SIS corresponding to other servo sectors SS. The MPU60 averages the predetermined object-normalized signal strength corresponding to the predetermined servo sector SS and the other normalized signal strength corresponding to other servo sectors SS to calculate the averaged normalized signal strength corresponding to the predetermined servo sector SS.

[0114] The HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10 if it determines that the averaged normalized signal strength corresponding to a predetermined servo sector SS is smaller than (or below) the HFW threshold. The HFW detection unit 630 also determines that an HFW has occurred in a predetermined area of ​​disk 10 if it determines that the averaged normalized signal strength corresponding to a predetermined servo sector SS is greater than (or above) the HFW threshold.

[0115] Figure 14 This is a schematic diagram illustrating an example of the HFW detection method involved in Variation Example 2. Figure 14 The track TRm shown is Figure 6 The track TRm shown corresponds to this.

[0116] exist Figure 14 In the example shown, during write processing, the MPU60 reads the signal strength record data SIS(k-1) corresponding to the servo sector SS(k-1). During write processing, the MPU60 reads the target servo reproduced signal strength of the servo sector SS(k-1). Based on the signal strength record data SIS(k-1) corresponding to the servo sector SS(k-1), the MPU60 normalizes the target servo reproduced signal strength of the servo sector SS(k-1) to a normalized reproduced signal strength. During write processing, the MPU60 reads the signal strength record data SIS(k) corresponding to the servo sector SS(k). During write processing, the MPU60 reads the target servo reproduced signal strength of the servo sector SS(k). Based on the signal strength record data SIS(k) corresponding to the servo sector SS(k), the MPU60 normalizes the target servo reproduced signal strength of the servo sector SS(k) to a normalized reproduced signal strength. The MPU60 averages the normalized reproducible signal strength corresponding to servo sector SS(k-1) and servo sector SS(k), and calculates the averaged normalized signal strength corresponding to the predetermined servo sector SS. The MPU60 determines whether the averaged normalized reproducible signal strength corresponding to servo sectors SS(k-1) and SS(k) is less than the HFW threshold HTH or greater than the HFW threshold.

[0117] exist Figure 14 In the example shown, when the MPU60 determines that the averaged normalized reproduced signal strength corresponding to servo sector SS(k-1) and SS(k) is smaller than the HFW threshold HTH, it stops writing in the data sector region DSR(k-1) and the data sector region DSR(k) corresponding to servo sector SS(k-1) of disk 10, and performs rewrite processing from the data sector region DSR(k-1) to the data sector region DSR(k).

[0118] exist Figure 14 In the example shown, during write processing, the MPU60 reads the signal strength record data SIS(k) corresponding to the servo sector SS(k). During write processing, the MPU60 reads the target servo reproduced signal strength of the servo sector SS(k). Based on the signal strength record data SIS(k) corresponding to the servo sector SS(k), the MPU60 normalizes the target servo reproduced signal strength of the servo sector SS(k) to a normalized reproduced signal strength. During write processing, the MPU60 reads the signal strength record data SIS(k+1) corresponding to the servo sector SS(k+1). During write processing, the MPU60 reads the target servo reproduced signal strength of the servo sector SS(k+1). Based on the signal strength record data SIS(k+1) corresponding to the servo sector SS(k+1), the MPU60 normalizes the target servo reproduced signal strength of the servo sector SS(k+1) to a normalized reproduced signal strength. The MPU60 averages the normalized reproducible signal strength corresponding to servo sector SS(k) and servo sector SS(k+1), and calculates the averaged normalized signal strength corresponding to the predetermined servo sector SS. The MPU60 determines whether the averaged normalized reproducible signal strength corresponding to servo sectors SS(k) and SS(k+1) is less than or greater than the HFW threshold HTH.

[0119] exist Figure 14 In the example shown, when the MPU60 determines that the averaged normalized reproduced signal strength corresponding to servo sectors SS(k) and SS(k+1) is smaller than the HFW threshold HTH, it stops writing in the data sector region DSR(k) and the data sector region DSR(k+1) corresponding to servo sector SS(k) on disk 10, and performs rewrite processing from the data sector region DSR(k) through the data sector region DSR(k+1).

[0120] Figure 15 This is a flowchart illustrating an example of the HFW detection method involved in Variation Example 2.

[0121] During write processing, MPU60 reads other signal strength record data SIS (B1501) corresponding to other servo sectors SS that are different from the predetermined servo sector, and reads other object servo reproduction signal strengths corresponding to other servo sectors SS (B1502). MPU60 reads predetermined signal strength record data SIS (B1503) corresponding to the predetermined servo sector SS, and reads predetermined object servo reproduction signal strengths corresponding to the predetermined servo sector SS (B1504). Based on the other signal strength record data SIS, MPU60 normalizes the other object servo reproduction signal strengths to other normalized signal strengths (B1505). Based on the predetermined signal strength record data SIS, MPU60 normalizes the object servo reproduction signal strengths to object normalized signal strengths (B1506). MPU60 averages the other normalized signal strengths and object normalized signal strengths to calculate the averaged normalized signal strength corresponding to the predetermined servo sector SS (B1507).

[0122] MPU60 determines whether the averaged normalized signal strength corresponding to the predetermined servo sector SS is less than or greater than the HFW threshold (B1508). If it determines that the averaged normalized signal strength corresponding to the predetermined servo sector SS is greater than or greater than the HFW threshold (B1508: No), MPU60 determines that no HFW has been generated in the predetermined area and ends the process. If it determines that the averaged normalized signal strength corresponding to the predetermined servo sector SS is less than the HFW threshold (B1508: Yes), MPU60 determines that HFW has been generated in the predetermined area, stops the write process in that area (B1509), and ends the process.

[0123] According to Variation 2, during write processing, disk device 1 averages the other normalized signal strengths and the object normalized signal strength to calculate the averaged normalized signal strength corresponding to the predetermined servo sector SS and other servo sectors SS. Disk device 1 determines whether the averaged normalized signal strength corresponding to the predetermined servo sector SS and other servo sectors SS is less than the HFW threshold HTH or greater than the HFW threshold HTH. If the averaged normalized signal strength is determined to be smaller than the HFW threshold HTH, the disk device 1 determines that an HFW has occurred in a predetermined data sector region DSR corresponding to a predetermined servo sector SS and in other data sector regions DSR corresponding to other servo sectors SS. It then stops write processing in these regions and performs either a rewrite or a rollback. Therefore, the disk device 1 can improve the BPI (Block Principle Indicator). Furthermore, the disk device 1 can improve reliability.

[0124] (Variation Example 3)

[0125] The HFW detection method of the disk device 1 involved in Variation Example 3 is different from that of the disk device 1 involved in the aforementioned embodiments.

[0126] In a predetermined track, the MPU60 continuously writes the signal strength recording data (hereinafter sometimes referred to as averaged signal strength recording data) corresponding to the predetermined servo sector SS (SIS) to be calculated by averaging the predetermined signal strength recording data corresponding to the predetermined servo sector SS and other signal strength recording data corresponding to other servo sectors SS, immediately following the read / write direction. Furthermore, the MPU60 can continuously write the averaged signal strength recording data (ASIS) corresponding to the predetermined servo sector SS and other servo sectors SS immediately following the read / write direction, or it can continuously write it to other servo sectors SS immediately following the read / write direction. Furthermore, the MPU60 can write the averaged signal strength recording data (ASIS) corresponding to a predetermined servo sector SS and other servo sectors SS to a region outside the immediately following signal strength recording area in the read / write direction of that servo sector SS, or it can write it to a region outside the immediately following signal strength recording area in the read / write direction of other servo sectors SS. In this way, by averaging multiple signal strength recording data SIS corresponding to multiple servo sectors, such as two servo sectors respectively, or for example, two signal strength recording data SIS, the servo region that will be the object of the Fourier transform can be considered several times larger, for example, twice the size.

[0127] For example, in a predetermined track, the MPU60 continuously writes the averaged signal strength record data (hereinafter sometimes referred to as the next averaged signal strength record data) SIS, which is calculated by averaging the current signal strength record data SIS corresponding to the current servo sector SS and the next signal strength record data SIS corresponding to the next servo sector SS, immediately following the current servo sector SS in the read / write direction.

[0128] For example, the MPU60 can also continuously write the averaged signal strength record data (hereinafter sometimes referred to as the current averaged signal strength record data) corresponding to the previous servo sector SS and the current signal strength record data SIS, calculated by averaging the previous signal strength record data SIS corresponding to the previous servo sector SS and the current signal strength record data SIS corresponding to the current servo sector SS, immediately after the current servo sector SS in the read / write direction.

[0129] Furthermore, the MPU60 can continuously write the current averaged signal strength recording data (SIS) corresponding to the previous servo sector SS and the current servo sector SS immediately following the current servo sector SS in the read / write direction, or it can continuously write it immediately following the read / write direction of other servo sector SSs besides the current servo sector SS. Additionally, the MPU60 can write the current averaged signal strength recording data (SIS) corresponding to the previous servo sector SS and the current servo sector SS to a region outside the signal strength recording region immediately following the current servo sector SS in the read / write direction, or it can write it to a region outside the signal strength recording region immediately following the current servo sector SS in the read / write direction of other servo sector SSs besides the current servo sector SS.

[0130] During write processing on a predetermined track, the MPU60 normalizes the sum of the target servo reproduced signal strength corresponding to the servo sector SS and other servo sector SS based on the averaged signal strength recorded data SIS that was previously read from the target region of the servo sector SS. This normalizes the sum of the target servo reproduced signal strength corresponding to the currently read servo sector SS and the sum of the target servo reproduced signal strengths corresponding to other servo sector SS. For example, during write processing on a predetermined track, the MPU60 normalizes the sum of the target servo reproduced signal strength corresponding to the predetermined servo sector SS and the sum of the target servo reproduced signal strengths corresponding to other servo sector SS by dividing or subtracting the averaged signal strength recorded data SIS corresponding to the predetermined servo sector SS and the sum of the target servo reproduced signal strengths corresponding to other servo sector SS. In other words, the MPU60 calculates the averaged normalized reproducible signal strength corresponding to the predetermined servo sector SS and the other servo sector SS by dividing or subtracting the sum of the predetermined object servo reproduced signal strength corresponding to the predetermined servo sector SS and the other object servo reproduced signal strength corresponding to the other servo sector SS.

[0131] For example, during write processing on a predetermined track, when reading from the previous servo sector SS and the current servo sector SS, the MPU60 normalizes the sum of the previous object servo reproduced signal strength corresponding to the previous servo sector SS and the current object servo reproduced signal strength corresponding to the current servo sector SS, based on the current averaged signal strength recorded data SIS. For example, during write processing on a predetermined track, the MPU60 normalizes the sum of the previous object servo reproduced signal strength corresponding to the previous servo sector SS and the current object servo reproduced signal strength corresponding to the current servo sector SS by dividing or subtracting the current averaged signal strength recorded data SIS. In other words, when writing to a predetermined track, the MPU60 calculates the averaged normalized reproducible signal strength (hereinafter sometimes referred to as the current averaged normalized reproducible signal strength) corresponding to the current servo sector SS by dividing the sum of the previous object servo reproduced signal strength corresponding to the previous servo sector SS and the current object servo reproduced signal strength corresponding to the current servo sector SS by or by subtracting the current averaged normalized reproducible signal strength record data SIS.

[0132] Furthermore, when the disk device 1 is a TDMR type disk device, the MPU60 can also average multiple signal strength recording data SIS corresponding to predetermined servo sectors SS that have been read by multiple read heads 15R mounted on a head 15, and calculate averaged signal strength recording data SIS corresponding to the predetermined servo sectors SS. The MPU60 can also normalize the target servo reproduction signal strength corresponding to the currently read servo sector SS based on the averaged signal strength recording data SIS.

[0133] For example, if the MPU60 determines that an HFW (High-Frequency Wave) has occurred in a predetermined area of ​​disk 10 based on the averaged normalized reproduction signal strength corresponding to a predetermined servo sector SS and other servo sectors SS, it stops writing in the predetermined area of ​​disk 10 and performs a rewrite process from the other data sector area DSR (Data Sector Area Ratio) corresponding to the other servo sectors SS of disk 10 to the data sector area DSR corresponding to the predetermined servo sectors SS. For example, if the MPU60 determines that an HFW has occurred in the other data sector area corresponding to the other servo sectors SS and the predetermined data sector area corresponding to the predetermined servo sectors SS of disk 10 based on the averaged signal strength corresponding to the predetermined servo sectors SS, it stops writing in the other data sector area corresponding to the other servo sectors SS and the predetermined data sector area corresponding to the predetermined servo sectors SS of disk 10, and performs a rewrite process from the other data sector area to the predetermined data sector area.

[0134] For example, if the MPU60 determines that an HFW has occurred in a predetermined area of ​​disk 10 based on the averaged normalized reproduction signal strength corresponding to the predetermined servo sector SS and other servo sectors SS, it stops writing in the predetermined area of ​​disk 10 and performs a transfer process to transfer the data of disk 10 from the data sector area (hereinafter sometimes referred to as other data sector area) DSR corresponding to other servo sectors SS to the data sector area DSR corresponding to the predetermined servo sector SS to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80 or buffer memory 90. For example, if the MPU60 determines, based on the averaged signal strength recording data corresponding to the predetermined servo sector SS and other servo sectors SS, that an HFW has occurred in other data sector areas corresponding to other servo sectors SS and predetermined data sector areas corresponding to the predetermined servo sectors SS on disk 10, the write operation is stopped in the other data sector areas corresponding to other servo sectors SS and predetermined data sector areas corresponding to the predetermined servo sectors SS on disk 10, and a transfer process is performed to transfer the data from the other data sector area to the predetermined data sector area to other alternative areas, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0135] Figure 16 This is a schematic diagram illustrating an example of the configuration of the averaged signal strength recording data (SIS) involved in Variation Example 3. Figure 16 The image shows track TRm. Track TRm contains servo sectors SS(k-1), SS(k), and SS(k+1) and averaged signal strength recording data ASIS(k), ASIS(k+1), and ASIS(k+2). Figure 16 In this configuration, the averaged signal strength recording data ASIS(k), ASIS(k+1), and ASIS(k+1) are arranged with a gap in the read / write direction in the order they are recorded. In other words, the averaged signal strength recording data ASIS(k+1) is arranged with a gap between it and the averaged signal strength recording data ASIS(k) in the read / write direction. The averaged signal strength recording data ASIS(k+2) is arranged with a gap between it and the averaged signal strength recording data ASIS(k+1) in the read / write direction. The averaged signal strength recording data ASIS(k) is located between servo sectors SS(k-1) and SS(k), and is adjacent to servo sector SS(k-1) in the read / write direction. The averaged signal strength recording data ASIS(k) is equivalent to the signal strength recording data obtained by averaging the signal strength recording data SIS(k-1) and SIS(k). The averaged signal strength recording data ASIS(k) corresponds to servo sector SS(k). Averaged signal strength recording data ASIS(k+1) is configured between servo sectors SS(k) and SS(k+1), adjacent to servo sector SS(k) in the read / write direction. ASIS(k+1) is equivalent to the signal strength recording data obtained by averaging the signal strength recording data corresponding to servo sectors SS(k) and SS(k+1). ASIS(k+1) corresponds to servo sector SS(k+1). ASIS(k+2) is adjacent to servo sector SS(k+1) in the read / write direction. ASIS(k+2) is equivalent to the signal strength recording data obtained by averaging the signal strength recording data corresponding to servo sectors SS(k+1) and SS(k+2). ASIS(k+2) corresponds to the next servo sector SS(k+2) after servo sector SS(k+1) (not shown).

[0136] exist Figure 16 In the example shown, the MPU60 writes signal strength recording data ASIS(k) adjacent to servo sector SS(k-1) in the read / write direction on track TRm, writes signal strength recording data SIS(k+1) adjacent to servo sector SS(k) in the read / write direction, and writes signal strength recording data ASIS(k+2) adjacent to servo sector SS(k+1) in the read / write direction. In other words, the MPU60 writes signal strength recording data ASIS(k) immediately after servo sector SS(k-1), then writes signal strength recording data SIS(k+1) immediately after servo sector SS(k), and then writes signal strength recording data ASIS(k+2) immediately after servo sector SS(k+1) on track TRm.

[0137] Figure 17 This is a schematic diagram illustrating an example of the HFW detection method involved in Variation 3. Figure 17 The track TRm shown is Figure 16 The track TRm shown corresponds to this.

[0138] exist Figure 17 In the example shown, during the write processing of track TRm, the MPU60 reads the target servo reproduced signal strength corresponding to servo sector SS(k-1). The MPU60 reads the averaged signal strength recorded data ASIS(k) corresponding to servo sectors SS(k-1) and SS(k). The MPU60 reads the target servo reproduced signal strength corresponding to servo sector SS(k). Based on the averaged signal strength recorded data ASIS(k) corresponding to servo sectors SS(k-1) and SS(k), the MPU60 normalizes the sum of the target servo reproduced signal strength corresponding to servo sector SS(k-1) and the target servo reproduced signal strength corresponding to servo sector SS(k) into an averaged normalized reproduced signal strength. The MPU60 determines whether the normalized reproduced signal strength corresponding to servo sectors SS(k-1) and SS(k) is less than or greater than the HFW threshold HTH.

[0139] exist Figure 17 In the example shown, when the MPU60 determines that the normalized reproducible signal strength corresponding to servo sector SS(k-1) and SS(k) is smaller than the HFW threshold HTH, it stops writing in the data sector region DSR(k-1) corresponding to servo sector SS(k-1) and the data sector region DSR(k) corresponding to servo sector SS(k), and performs rewrite processing from the data sector region DSR(k-1) through the data sector region DSR(k).

[0140] exist Figure 17In the example shown, during the write processing of track TRm, the MPU60 reads the target servo reproduced signal strength corresponding to servo sector SS(k). The MPU60 reads the averaged signal strength record data ASIS(k+1) corresponding to servo sectors SS(k) and SS(k+1). The MPU60 reads the target servo reproduced signal strength corresponding to servo sector SS(k+1). Based on the averaged signal strength record data ASIS(k+1) corresponding to servo sectors SS(k) and SS(k+1), the MPU60 normalizes the sum of the target servo reproduced signal strength corresponding to servo sector SS(k) and the target servo reproduced signal strength corresponding to servo sector SS(k) and SS(k+1) into an averaged normalized reproduced signal strength. The MPU60 determines whether the normalized reproduced signal strength corresponding to servo sectors SS(k) and SS(k+1) is less than or greater than the HFW threshold HTH.

[0141] exist Figure 17 In the example shown, when the MPU60 determines that the normalized reproducible signal strength corresponding to servo sectors SS(k) and SS(k+1) is smaller than the HFW threshold HTH, it stops writing in the data sector region DSR(k) corresponding to servo sector SS(k) and the data sector region DSR(k+1) corresponding to servo sector SS(k), and performs rewrite processing from the data sector region DSR(k) through the data sector region DSR(k+1).

[0142] Figure 18 This is a flowchart illustrating an example of the HFW detection method involved in Variation Example 3.

[0143] During write processing, MPU60 reads the other object servo reproduced signal strength corresponding to other servo sectors SS (B1801) and reads the predetermined averaged signal strength recording data ASIS corresponding to the predetermined servo sector SS (B1802). MPU60 reads the object servo reproduced signal strength of the predetermined servo sector SS (B1803). Based on the predetermined averaged signal strength recording data ASIS, MPU60 normalizes the sum of the other object servo reproduced signal strength and the predetermined object servo reproduced signal strength to an averaged normalized reproduced signal strength (B1804). MPU60 determines whether the averaged normalized reproduced signal strength corresponding to the other servo sector SS and the predetermined servo sector SS is less than or greater than the HFW threshold (B1805). If it determines that the averaged normalized reproduced signal strength corresponding to the other servo sector SS and the predetermined servo sector SS is greater than or greater than the HFW threshold (B1805: No), MPU60 determines that no HFW has been generated in the other servo sector SS and the predetermined servo sector SS, and ends the processing. If the averaged normalized reproducible signal strength corresponding to other servo sectors SS and the predetermined servo sector SS is smaller than the HFW threshold (B1805: Yes), the MPU60 determines that HFW has occurred in other servo sectors SS and the predetermined servo sector SS, stops the write processing in other servo sectors SS and the predetermined servo sector SS (B1806), and ends the processing.

[0144] According to Variation 3, during write processing, disk device 1 reads the other object servo reproduced signal strength corresponding to other servo sectors SS, reads predetermined averaged signal strength recording data ASIS corresponding to a predetermined servo sector SS, and reads the object servo reproduced signal strength of the predetermined servo sector SS. Based on the predetermined averaged signal strength recording data ASIS, disk device 1 normalizes the sum of the other object servo reproduced signal strength and the predetermined object servo reproduced signal strength to an averaged normalized reproduced signal strength. Disk device 1 determines whether the averaged normalized reproduced signal strength is less than or greater than the HFW threshold. If the averaged normalized reproduced signal strength is determined to be less than the HFW threshold, the MPU60 determines that HFW has occurred in the other data sector region corresponding to other servo sectors SS and the predetermined data sector region corresponding to the predetermined servo sector SS. Write processing is stopped in the other data sector region corresponding to other servo sectors SS and the predetermined data sector region corresponding to the predetermined servo sector SS. A rewrite process is performed from the other data sector region corresponding to other servo sectors SS to the predetermined data sector region corresponding to the predetermined servo sector SS, or a transfer process is performed on the other data sector region corresponding to other servo sectors SS and the predetermined data sector region corresponding to the predetermined servo sector SS. Therefore, the disk device 1 can improve BPI. Furthermore, the disk device 1 can improve reliability.

[0145] (Third Implementation)

[0146] The HFW detection method of the disk device 1 according to the third embodiment is different from that of the disk device 1 in the first embodiment, variation 1, variation 2 and variation 3 described above.

[0147] Figure 19 This is a schematic diagram illustrating an example of the configuration of the servo sector SS according to the second embodiment. Figure 19 The image shows a predetermined servo sector SS written in a predetermined track TR of disk 10.

[0148] exist Figure 19 In the example shown, the data sector region DSR does not contain signal strength recording data SIS corresponding to the predetermined servo sector SS in the signal strength recording area adjacent to the predetermined servo sector SS. That is, the data sector region DSR does not contain a signal strength recording area.

[0149] The MPU60 has multiple object servo reproduced signal strength thresholds (hereinafter sometimes referred to as reproduced signal strength thresholds) corresponding to multiple servo sectors respectively. For example, the reproduced signal strength threshold is equivalent to the intermediate value of the object servo reproduced signal strength of the servo sector SS when it is read from the servo sector SS written with the first 15 of the normal float (hereinafter sometimes referred to as the object servo reproduced signal strength corresponding to the normal float) and the object servo reproduced signal strength of the servo sector SS when it is read from the servo sector SS written with the first 15 of the high float (hereinafter sometimes referred to as the object servo reproduced signal strength corresponding to the high float). Alternatively, the reproduced signal strength threshold may also be equivalent to the average of multiple intermediate values ​​of the object servo reproduced signal strength corresponding to the normal float corresponding to multiple servo sectors and the object servo reproduced signal strength corresponding to the high float corresponding to multiple servo sectors.

[0150] MPU60 determines whether the reproduced signal strength of the object servo corresponding to a predetermined servo sector SS is less than, or greater than, the reproduced signal strength threshold corresponding to that servo sector SS (or less than, or greater than, the reproduced signal strength threshold). For example, MPU60 determines whether the reproduced signal strength of the current object servo corresponding to the current servo sector SS is less than, or greater than, the reproduced signal strength threshold (hereinafter sometimes referred to as the current reproduced signal strength threshold).

[0151] If MPU60 determines that an HFW (High-Frequency Signal Written) has occurred in a predetermined area of ​​disk 10 if the target servo signal strength corresponding to a predetermined servo sector SS is less than (or below) a target servo signal strength threshold, MPU60 determines that an HFW has occurred in a predetermined area of ​​disk 10 if the target servo signal strength corresponding to a predetermined servo sector SS is greater than (or above) a target servo signal strength threshold. For example, if MPU60 determines that an HFW has occurred in a predetermined area of ​​disk 10 if the target servo signal strength corresponding to the current servo sector is less than (or below) a target servo signal strength threshold, MPU60 determines that an HFW has occurred in a predetermined area of ​​disk 10 if the target servo signal strength corresponding to the current servo sector is greater than (or above) a target servo signal strength threshold, MPU60 determines that no HFW has occurred in a predetermined area of ​​disk 10.

[0152] If the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10, it stops writing to that predetermined area. For example, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10, it stops writing to that predetermined area and performs a rewrite operation on that predetermined area. Alternatively, if the HFW detection unit 630 determines that an HFW has occurred in a predetermined area of ​​disk 10, it stops writing to that predetermined area and performs a process to record or save the data in the predetermined area of ​​disk 10 to another alternative area, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90 (hereinafter sometimes referred to as a transfer process).

[0153] Figure 20 This is a schematic diagram illustrating an example of the variation of each reproduced signal strength threshold relative to each servo sector SS according to the second embodiment. Figure 20 In the diagram, the horizontal axis represents the servo sector (SS), and the vertical axis represents the signal strength of the object's servo reproduction. Figure 20 On the vertical axis, the object servo reproduction signal strength increases as it moves towards the tip of the larger arrow and decreases as it moves towards the tip of the smaller arrow. Figure 20 The figure shows the changes in the object servo reproduced signal strength USL corresponding to normal float and the changes in the object servo reproduced signal strength HSL corresponding to high float, and the changes in each reproduced signal strength threshold relative to each servo sector (hereinafter sometimes referred to as the changes in reproduced signal strength threshold) MTH.

[0154] like Figure 20 The variation of the reproducible signal strength threshold MTH is shown in the figure. Each reproducible signal strength threshold corresponding to each servo sector SS is equivalent to the median value of the object servo reproducible signal strength corresponding to each high slack value in each servo sector and the object servo reproducible signal strength corresponding to each normal slack value in each servo sector SS. For example, the MPU60 has a variation of the reproducible signal strength threshold MTH.

[0155] Figure 21 This is a flowchart illustrating an example of the HFW detection method according to the second embodiment.

[0156] During write processing, MPU60 reads the target servo reproduction signal strength of a predetermined servo sector SS (B2101). MPU60 determines whether the target servo reproduction signal strength corresponding to the predetermined servo sector SS is less than or greater than the reproduction signal strength threshold corresponding to that servo sector SS (B2102). If it determines that the target servo reproduction signal strength corresponding to the predetermined servo sector SS is greater than or greater than the reproduction signal strength threshold (B2102: No), MPU60 determines that no HFW has been generated in the predetermined area and ends the process. If it determines that the target servo reproduction signal strength corresponding to the predetermined servo sector SS is less than the reproduction signal strength threshold (B2102: Yes), MPU60 determines that an HFW has been generated in the predetermined area, stops write processing in that area (B2103), and ends the process.

[0157] According to the second embodiment, during write processing, the disk device 1 reads the target servo reproduction signal strength of a predetermined servo sector SS. The disk device 1 determines whether the target servo reproduction signal strength corresponding to the predetermined servo sector SS is less than or greater than a reproduction signal strength threshold corresponding to that servo sector SS. If it is determined that the target servo reproduction signal strength corresponding to the predetermined servo sector SS is less than the reproduction signal strength threshold, the disk device 1 determines that an HFW has occurred in the predetermined area, stops write processing in that area, and ends the processing.

[0158] Several embodiments 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.

[0159] The following is an example of a disk device derived from the configuration disclosed in this specification.

[0160] (1) A disk device comprising: a disk having tracks including a first servo sector and a second servo sector different from the first servo sector; a head for writing data to the disk and reading data from the disk; and a controller for recording first signal strength recording data associated with a signal strength obtained from reading first target servo data, and for normalizing the first signal strength data associated with the signal strength obtained from reading the first target servo data when reading the first target servo data, wherein the first target servo data is target servo data of the first servo sector.

[0161] (2) According to the disk device described in (1), the controller normalizes the first signal strength data into first normalized data based on the first signal strength recording data.

[0162] (3) According to the disk device described in (1), the controller calculates the first normalized data by subtracting or dividing the first signal strength data from the first signal strength recorded data.

[0163] (4) According to the disk device described in (2) or (3), the controller determines whether the first standardized data is smaller than the first threshold or greater than the first threshold.

[0164] (5) According to the disk device described in (4), the controller stops writing when it determines that the first standardized data is smaller than the first threshold.

[0165] (6) According to the disk device described in (4), the controller stops writing when it determines that the first standardized data is above the first threshold.

[0166] (7) According to the disk device described in (5) or (6), the controller performs rewrite processing or writes to other alternative areas when write processing is stopped.

[0167] (8) The disk device according to any one of (1) to (7), wherein the controller writes the first signal strength recording data adjacent to the first servo sector between the first servo sector and the second servo sector configured next to the first servo sector.

[0168] (9) The disk device according to (7) further comprises volatile memory and non-volatile memory, wherein the alternative region comprises the disk, the volatile memory or the non-volatile memory.

[0169] (10) The disk device according to any one of (1) to (9), wherein the first signal strength recording data and the first signal strength data are values ​​obtained by performing a Fourier transform on the reproduced signal when the first object servo data is read.

[0170] (11) The disk device according to any one of (1) to (9), wherein the first signal strength recording data and the first signal strength data are values ​​obtained by performing Fourier transform and division operation on the reproduced signal and the ideal signal or the demodulated signal when the first object servo data is read.

[0171] (12) The disk apparatus according to any one of (1) to (9), wherein the first signal strength recording data and the first signal strength data are the amplitude of the reproduced signal when the first object servo data is read.

[0172] (13) According to the disk device of (1), the controller records second signal strength recording data associated with the signal strength obtained by reading the second object servo data, and when reading the first object servo data, calculates a first averaged signal strength recording data obtained by averaging the first signal strength recording data and the second signal strength recording data, calculates a first averaged signal strength data obtained by averaging the first signal strength data and the second signal strength data associated with the signal strength obtained by reading the second object servo data, and normalizes the first averaged signal strength data into first averaged normalized data based on the first averaged signal strength recording data, wherein the second object servo data is the object servo data of the second servo sector.

[0173] (14) According to the disk device of (13), the controller performs rewrite processing on the first data area corresponding to the first servo sector and the second data area corresponding to the second servo sector when the write processing stops based on the first averaged normalized data.

[0174] (15) According to the disk device described in (13) or (14), the controller determines whether the first averaged normalized data is smaller than the first threshold or greater than the first threshold.

[0175] (16) According to the disk device of (1), the controller records second signal strength recording data associated with the signal strength obtained by reading the second object servo data, and when reading the first object servo data, normalizes the first signal strength data into first normalized data based on the first signal strength recording data, and when reading the second object servo data, normalizes the second signal strength data associated with the signal strength obtained by reading the second object servo data into second normalized data based on the second signal strength recording data, and calculates a first averaged normalized data obtained by averaging the first normalized data and the second normalized data, wherein the second object servo data is the object servo data of the second servo sector.

[0176] (17) According to the disk device of (16), the controller performs rewrite processing on the first data area corresponding to the first servo sector and the second data area corresponding to the second servo sector when the write processing stops based on the first averaged normalized data.

[0177] (18) According to the disk device of (1), the head has a first read head and a second read head for reading data from the disk, and when the controller reads the first object servo data with the first read head and the second read head, it calculates a first averaged signal strength record data obtained by averaging the first signal strength record data obtained by reading the first object servo data with the first read head and the second signal strength record data associated with the signal strength obtained by reading the first object servo data with the second read head, calculates a first averaged signal strength data obtained by averaging the first signal strength data read from the first object servo data with the first read head and the second signal strength data associated with the signal strength read from the first object servo data with the second read head, and normalizes the first averaged signal strength data into a first averaged normalized data based on the first averaged signal strength record data.

[0178] (19) A disk device comprising: a disk having tracks including a first servo sector and a second servo sector different from the first servo sector; a head for writing data to the disk and reading data from the disk; and a controller that, upon reading first target servo data, determines whether first signal strength data associated with the signal strength obtained from reading the first target servo data is less than or greater than a first threshold corresponding to the first signal strength data, wherein the first target servo data is target servo data of the first servo sector.

[0179] (20) According to the disk device of (19), the controller stops writing when it determines that the first signal strength data is smaller than the first threshold.

[0180] (21) According to the disk device of (19) or (20), the first threshold is equivalent to the intermediate value of the first signal strength data when the head reads the first servo sector with a first hover amount and the first signal strength data when the head reads the first servo sector with a second hover amount higher than the first hover amount.

[0181] (22) According to the disk device of (19), the controller calculates the first threshold by averaging the first signal strength data and the second signal strength data associated with the signal strength obtained when reading the second object servo data, wherein the second object servo data is the object servo data of the second servo sector.

[0182] (23) A disk drive comprising: a disk having tracks including a first servo sector and a second servo sector different from the first servo sector; a head for writing data to the disk and reading data from the disk; and a controller for recording first averaged signal strength recording data obtained by averaging a signal strength obtained from reading first target servo data and a signal strength obtained from reading second target servo data, and for standardizing first signal strength data associated with the signal strength obtained from reading the first target servo data into first normalized data when reading the first target servo data, wherein the first target servo data is target servo data of the first servo sector and the second target servo data is target servo data of the second servo sector.

[0183] (24) According to the disk device of (23), the controller normalizes the first signal strength data into the first normalized data based on the first averaged signal strength recording data.

[0184] (25) According to the disk device described in (23) or (24), the controller performs rewrite processing on the first data area corresponding to the first servo sector and the second data area corresponding to the second servo sector when the write processing stops based on the first averaged normalized data.

Claims

1. A disk device comprising: a disk having a track including a first servo sector and a second servo sector different from the first servo sector; a head that writes data to the disk and reads data from the disk; and a controller that records first signal strength record data associated with a signal strength obtained when a first target servo data is read, normalizes first signal strength data associated with a signal strength obtained when the first target servo data is read at a time when the first target servo data is read, the first target servo data being servo data of the first servo sector that becomes a target, the controller writing the first signal strength record data adjacent to the first servo sector between the first servo sector and the second servo sector disposed next to the first servo sector.

2. The disk device according to claim 1, the controller normalizing the first signal strength data to first normalized data based on the first signal strength record data.

3. The disk device according to claim 1, the controller calculating first normalized data by subtracting or dividing the first signal strength data by the first signal strength record data.

4. The disk device according to claim 2 or 3, the controller determining whether the first normalized data is less than a first threshold value or is equal to or greater than the first threshold value.

5. The disk device according to claim 4, the controller stopping a write process when it is determined that the first normalized data is less than the first threshold value.

6. The disk device according to claim 4, the controller stopping a write process when it is determined that the first normalized data is equal to or greater than the first threshold value.

7. The disk device according to claim 5, the controller performing a rewrite process or writing to another alternative area when the write process is stopped.

8. The disk device according to claim 7, further comprising a volatile memory and a nonvolatile memory, the alternative area having the disk, the volatile memory, or the nonvolatile memory.

9. The disk device according to any one of claims 1 to 3, the first signal strength record data and the first signal strength data being values obtained by Fourier transforming a reproduction signal at a time when the first target servo data is read.

10. The disk device according to any one of claims 1 to 3, the first signal strength record data and the first signal strength data being values obtained by Fourier transforming a reproduction signal and an ideal signal, or demodulated signals, respectively, at a time when the first target servo data is read, and performing a division operation.

11. The disk device according to any one of claims 1 to 3, the first signal strength record data and the first signal strength data being amplitudes of a reproduction signal at a time when the first target servo data is read.

12. The disk device according to claim 1, ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ ​ The controller records first signal intensity record data associated with signal intensity obtained by reading first target servo data, calculates first averaged signal intensity record data obtained by averaging the first signal intensity record data and second signal intensity record data associated with signal intensity obtained by reading second target servo data when the first target servo data is read, calculates first averaged signal intensity data obtained by averaging the first signal intensity data and the second signal intensity data based on the first averaged signal intensity record data, normalizes the first averaged signal intensity data to first averaged normalized data based on the first averaged signal intensity record data, and the second target servo data is servo data of the second servo sector that becomes a target.

13. The disk device according to claim 12, The controller executes rewrite processing on a first data area corresponding to the first servo sector and a second data area corresponding to the second servo sector in a case where write processing is stopped based on the first averaged normalized data.

14. The disk device according to claim 12 or 13, The controller determines whether the first averaged normalized data is smaller than a first threshold value or is equal to or greater than the first threshold value.

15. The disk device according to claim 1, The controller records first signal intensity record data associated with signal intensity obtained by reading first target servo data, calculates first signal intensity data based on the first signal intensity record data when the first target servo data is read, records second signal intensity record data associated with signal intensity obtained by reading second target servo data when the second target servo data is read, calculates second signal intensity data based on the second signal intensity record data when the second target servo data is read, calculates first averaged normalized data obtained by averaging the first normalized data and the second normalized data, and the second target servo data is servo data of the second servo sector that becomes a target.

16. The disk device according to claim 15, The controller executes rewrite processing on a first data area corresponding to the first servo sector and a second data area corresponding to the second servo sector in a case where write processing is stopped based on the first averaged normalized data.

17. The disk device according to claim 1, The head has a first read head and a second read head that read data from the disk, The controller calculates first-averaged signal intensity record data obtained by averaging the first signal intensity record data obtained by reading the first target servo data with the first reading head and second signal intensity record data associated with signal intensity obtained by reading the first target servo data with the second reading head, calculates first-averaged signal intensity data obtained by averaging the first signal intensity data read from the first target servo data with the first reading head and second signal intensity data associated with signal intensity read from the first target servo data with the second reading head, and normalizes the first-averaged signal intensity data to first-averaged normalized data based on the first-averaged signal intensity record data.

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