Disc device and servo pattern writing method

Abstract

Provided are a magnetic disk device and a servo pattern writing method that can improve reliability. A magnetic disk device according to the present embodiment includes a disk, a head that writes data to the disk and reads data from the disk, and a controller that writes a second spiral servo pattern that is different from a first spiral servo pattern in a radial direction of the disk so as to be overlaid with the first spiral servo pattern with a shift.

Description

[0001] This application enjoys priority based on Japanese Patent Application No. 2022-036125 (filed on March 9, 2022). This application incorporates the entire contents of the basic application by reference. Technical Field

[0002] Embodiments of the present invention relate to disk devices and servo pattern write methods. Background Technology

[0003] In the Blank Disc Writing (BDW) process, the disk device writes multiple spiral servo patterns onto a disk that has no data or patterns to be written. In the Self-Servo Write (SSW) process, based on the multiple spiral servo patterns, the disk device writes multiple servo patterns (hereinafter sometimes referred to as product servo patterns) used in the final product.

[0004] In disk drives, when the write width of the head is narrow, the width of the spiral servo pattern also becomes narrower, thus reducing the number of sync marks included in the read signal detecting the spiral servo pattern. Furthermore, in disk drives, the number of sync marks detected by reading the spiral servo pattern via the seek head is less than the number detected by reading the spiral servo pattern via the head in the track, thus increasing the possibility of servo disengagement due to the failure to detect sync marks during seek. This can reduce the reliability of the SSW process. Summary of the Invention

[0005] The problem to be solved by the embodiments of the present invention is to provide a disk device and a servo pattern writing method that can improve reliability.

[0006] The disk device according to this embodiment includes: a disk; a head for writing data to the disk and reading data from the disk; and a controller for writing a second spiral servo pattern, which is different from the first spiral servo pattern, in a radially offset manner from the first spiral servo pattern. Attached Figure Description

[0007] Figure 1 This is a block diagram illustrating the configuration of the disk drive according to the first embodiment.

[0008] Figure 2 This is a schematic diagram illustrating an example of the head's configuration relative to the disk according to the first embodiment.

[0009] Figure 3 This is a schematic diagram illustrating an example of a write signal for a spiral servo pattern.

[0010] Figure 4 This is a schematic diagram illustrating an example of a typical write (write) processing method for a spiral servo pattern.

[0011] Figure 5 This is a schematic diagram illustrating an example of a typical write processing method for a spiral servo pattern.

[0012] Figure 6 This is a schematic diagram illustrating an example of the write processing method for overlapping writing of a spiral servo pattern according to this embodiment.

[0013] Figure 7 This is a schematic diagram illustrating an example of a table showing the offset amount of the overlapping written spiral servo pattern involved in this embodiment.

[0014] Figure 8 This is a schematic diagram illustrating an example of the write processing method for overlapping writing of a spiral servo pattern according to this embodiment.

[0015] Figure 9 This is a schematic diagram illustrating an example of the write processing method for overlapping writing of a spiral servo pattern according to this embodiment.

[0016] Figure 10 This is a schematic diagram illustrating an example of a method for calculating the center position of a typical spiral servo pattern.

[0017] Figure 11 This is a schematic diagram illustrating an example of a method for calculating the center position of a spiral pattern in an overlapping spiral servo pattern according to this embodiment.

[0018] Figure 12 This is a flowchart illustrating an example of the servo pattern writing method according to this embodiment.

[0019] Figure 13 This is a flowchart illustrating an example of the servo pattern writing method according to this embodiment.

[0020] Figure 14 This is a schematic diagram illustrating an example of a write processing method involving an overlapping write-erase spiral pattern according to the second embodiment.

[0021] Figure 15 This is a schematic diagram of an example of a table showing the offset of the overlapping write-erase spiral pattern according to the second embodiment.

[0022] Figure 16This is a schematic diagram illustrating an example of the write processing method for overlapping write-erase spiral patterns according to the second embodiment.

[0023] Figure 17 This is a schematic diagram illustrating an example of the write processing method for overlapping write-erase spiral patterns according to the second embodiment.

[0024] Figure 18 This is a schematic diagram illustrating an example of a method for calculating the center position of the erase pattern in the overlapping write erase spiral pattern according to the second embodiment.

[0025] Figure 19 This is a flowchart illustrating an example of the servo pattern writing method according to the second embodiment.

[0026] Figure 20 This is a flowchart illustrating an example of the servo pattern writing method according to the second embodiment.

[0027] Label Explanation

[0028] 1. Disk drive; 10. Disk 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; 20. Driver IC; 30. Head amplifier IC; 40. Read / write (R / W) channel; 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, 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 simply referred to as the host) 100.

[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 by the drive of the SPM 12. The arm 13 and the VCM 14 constitute an actuator. The actuator, driven by the VCM 14, controls the head 15 mounted on the arm 13 to move to a predetermined position on the disk 10. Two or more disks 10 and heads 15 can be provided. Similarly, two or more actuators can also be provided.

[0034] Disk 10 has a user data area 10a available to users and a system area 10b for writing information required for system management, within its writable data area. Furthermore, disk 10 may also have a media cache (or, sometimes called a media cache area), as a separate area from the user data area 10a and system area 10b, for temporarily storing or recording data (or instructions) transmitted from the host 100, etc., before writing it to a predetermined area of ​​the user data area 10a. Hereinafter, the direction from the inner periphery of disk 10 to the outer periphery, or from the outer periphery of disk 10 to the inner periphery, 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 is called the inner direction (or inner side). A direction that intersects, for example, the radial direction of disk 10, is orthogonal to it is called the circumferential direction. The circumferential direction corresponds to the direction along the circumference of disk 10. Additionally, 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, both radial and circumferential positions 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 includes multiple tracks. A track includes multiple sectors. Furthermore, "track" has various meanings, such as "one of the multiple zones obtained by dividing disk 10 in the radial direction according to predetermined ranges," "data written to 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 to a region extending circumferentially at a predetermined radial position of disk 10," "a region around a predetermined radial position of disk 10," "a circumference of a region around a predetermined radial position of disk 10," "the path of the head 15 located at a predetermined radial position of disk 10 for writing," "data written through the head 15 located at a predetermined radial position of disk 10," "data written to a predetermined track of disk 10," and various other meanings. The term "sector" has various meanings, such as "one of several regions divided circumferentially by a predetermined track of disk 10," "data written to one of several regions divided circumferentially by a predetermined track of disk 10," "a region at a predetermined circumferential position at a predetermined radius of disk 10," "data written to a region at a predetermined circumferential position at a predetermined radius of disk 10," "data written to a predetermined sector of disk 10," and various other meanings. Sometimes, the "width of the track in the radial direction" is also called "track width." Sometimes, the "center position of the track width" is also called "track center." Sometimes, "track center" is simply referred to as "track."

[0035] The head 15 has a slider as its main body and includes a write head 15W and a read head 15R mounted on the slider. The write head 15W writes data to the disk 10. For example, the write head 15W writes a predetermined track on the disk 10. The read head 15R reads the data recorded on the disk 10. For example, the read head 15R reads a predetermined track of the disk 10. Sometimes, the "write head 15W" is simply referred to as "head 15," and sometimes the "read head 15R" is simply referred to as "head 15." Also sometimes, the "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, "positioning the center of head 15 in a predetermined position" is also expressed as "positioning head 15 in a predetermined position", "arranging head 15 in a predetermined position", or "positioning head 15 in a predetermined position".

[0036] Figure 2 This is a schematic diagram illustrating an example of the configuration of the head 15 relative to the disk 10 according to this embodiment. Figure 2 In the diagram, the innermost IMC and outermost OMC of disk 10 are represented. 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 indicated as counterclockwise, but it can also be the opposite (clockwise).

[0037] exist Figure 2 In the example shown, in disk 10, the system area 10b is positioned outwards from the user data area 10a. In other words, in disk 10, the user data area 10a is positioned inwards from the system area 10b. Figure 2 In the example shown, system area 10b is configured at the outermost OMC of disk 10. Furthermore, user data area 10a can also be configured by dividing the disk 10 radially. Additionally, system area 10b can also be configured in conjunction with... Figure 2 The locations shown are different. For example, system area 10b in disk 10 can be configured between multiple user data areas 10a, or it can be configured at the innermost IMC of disk 10.

[0038] Disk 10 has a data area DA, multiple servo patterns (hereinafter, sometimes referred to as product servo patterns) or multiple servo areas (hereinafter, sometimes referred to as product servo areas) PSV used in the final product, and multiple spiral servo patterns (multiple coarse guide spiral (CGS) servo patterns, multiple fine guide spiral (FGS) servo patterns, and multiple final spiral (FS) servo patterns) SSP that are different from the multiple product servo patterns PSV.

[0039] exist Figure 2 In this configuration, multiple data areas (DAs) are configured between multiple product servo patterns (PSVs). For example, a data area DA corresponds to the area between two consecutive product servo patterns (PSVs) in the circumferential direction. Furthermore, a "data area DA on a predetermined track" is sometimes referred to as a "data sector area." That is, a data area DA has at least one data sector area. Additionally, a "data area DA" is sometimes referred to as a "data sector area DA." A data sector area has at least one sector. Sometimes a "data sector area" is also referred to as a "sector." Sometimes, "data written to a data sector area" is also referred to as a "data sector area." Furthermore, sometimes "data other than product servo data written to a data sector area" is referred to as "user data."

[0040] exist Figure 2 For convenience, multiple spiral servo patterns SSPs extend spirally on disk 10. Although described as extending in parallel on disk 10, they may actually extend in a non-parallel manner. The multiple spiral servo patterns SSPs are discretely arranged at predetermined intervals along the circumference of disk 10. Hereinafter, the "spiral servo pattern SSP on a predetermined track" is sometimes referred to as a "spiral servo sector." Furthermore, the "spiral servo pattern SSP" is sometimes referred to as a "spiral servo sector." The "spiral servo sector" is sometimes referred to as a "spiral servo pattern." The "spiral servo sector" contains corresponding "servo data." Furthermore, the "spiral servo data written to the spiral servo sector" is sometimes referred to as a "spiral servo sector" or a "spiral servo pattern." Additionally, the "servo data" is sometimes referred to as a "servo sector" or a "servo pattern."

[0041] exist Figure 2For convenience, multiple product servo patterns (PSVs) extend linearly in the radial direction. However, while described as extending linearly from the inside to the outside in the radial direction, they can also be curved. For example, the product servo patterns (PSVs) can also extend spirally on disk 10. The multiple product servo patterns (PSVs) extend radially in the radial direction of disk 10 and are discretely arranged at predetermined intervals in the circumferential direction of disk 10. Hereinafter, "product servo patterns (PSVs) on predetermined tracks" will sometimes be referred to as "product servo sectors." Furthermore, "product servo patterns (PSVs)" will sometimes be referred to as "product servo sectors." "Product servo sectors" will sometimes be referred to as "product servo patterns." Product servo sectors contain servo data. Furthermore, "product servo data written to product servo sectors" will sometimes be referred to as "product servo sectors."

[0042] A servo sector (or servo data) may contain a preamble and a synchronization mark. Within the servo sector, the preamble and synchronization mark (or synchronization field data mark) are arranged sequentially from front to back in a circular direction. The preamble contains preamble information for synchronizing with the reproduction signal of the servo pattern composed of servo marks and Gray codes, etc. The synchronization mark contains information for detecting the beginning of data sector areas, etc. Furthermore, a servo sector may also contain data other than the preamble and synchronization mark. Additionally, the synchronization mark may also be included within the data sector area.

[0043] The driver IC20 is connected to the system controller 130 (specifically, the MPU60 described later), SPM12, and VCM14, and controls the driving of SPM12 and VCM14 according to the control of the system controller 130 (specifically, the MPU60 described later).

[0044] 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 corresponding to the signal output from the R / W channel 40 to the head 15. The head amplifier IC 30 is electrically connected to the head 15.

[0045] The volatile memory 70 is a semiconductor memory that loses its stored data when the power supply is disconnected. The volatile memory 70 stores data required for processing in various parts of the disk drive 1. The volatile memory 70 is, for example, DRAM (Dynamic Random Access Memory) or SDRAM (Synchronous Dynamic Random Access Memory). Furthermore, the volatile memory 70 may also be included in the system controller 130, which will be described later.

[0046] The non-volatile memory 80 is a semiconductor memory that records stored data even when the power supply is interrupted. The non-volatile memory 80 is, for example, a NOR or NAND flash memory (FROM). Furthermore, the non-volatile memory 80 may also be included in the system controller 130 described later.

[0047] The buffer memory 90 is a semiconductor memory that temporarily records data transmitted and received between the disk drive 1 and the host 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). Additionally, the buffer memory 90 may also be included in the system controller 130, which will be described later.

[0048] 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 R / W channel 40, HDC 50, and MPU 60 are electrically connected to each other. 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, buffer memory 90, and a host system 100.

[0049] R / W channel 40 performs signal processing on data transferred from disk 10 to host 100, such as read data, and data transferred from host 100, such as write data, according to instructions from MPU 60 (described later). R / W channel 40 is electrically connected to, for example, head amplifier IC 30, HDC 50, and MPU 60. R / W channel 40 has circuitry or functions for modulating write data. Additionally, R / W channel 40 has circuitry or functions for measuring the signal quality of read data and decoding the read data. R / W channel 40 is electrically connected to head amplifier IC 30, etc.

[0050] HDC50 controls the transmission of control data. HDC50 controls the data transmission between host 100 and disk 10 according to instructions from MPU60 (described later). HDC50 is electrically connected to, for example, head amplifier IC30, R / W channel 40, MPU60, volatile memory 70, non-volatile memory 80, and buffer memory 90.

[0051] MPU60 is the main controller that controls the various parts of disk drive 1. MPU60 controls VCM14 via driver IC20 to perform servo control for positioning head 15. MPU60 controls SPM12 via driver IC20 to rotate disk 10. MPU60 controls write operations (work) for writing data to disk 10 and selects the data transferred from host 100, such as the destination for writing data. MPU60 controls read operations for reading data from disk 10 and controls the processing of data transferred from disk 10 to host 100, such as read data processing. Additionally, MPU60 manages the area for recording data. 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.

[0052] The MPU60 includes a read / write control unit 610, a servo pattern writing unit 620, and a positioning control unit 630. The MPU60 executes the processing of each of these units, such as the read / write control unit 610, the servo pattern writing unit 620, and the positioning control unit 630, in its firmware. Alternatively, the MPU60 may also include these units, such as the read / write control unit 610, the servo pattern writing unit 620, and the positioning control unit 630, as circuitry.

[0053] The read / write control unit 610 controls data read and write processing according to instructions from the host 100. The read / write control unit 610 controls the VCM 14 via the driver IC 20 to position the head 15 at a predetermined radius position on the disk 10, and performs read or write processing. Hereinafter, "write processing" and "read processing" will sometimes be referred to uniformly as "access" or "access processing".

[0054] The servo pattern writing unit 620 writes servo patterns to the disk 10. The servo pattern writing unit 620 writes the spiral servo pattern SSP and the product servo pattern PSV to the disk 10.

[0055] The servo pattern writing unit 620 writes a spiral servo pattern SSP to the disk 10. In the blank disk writing (BDW) (or blank disk servo writing) process (hereinafter, sometimes referred to as BDW process) in which the servo pattern writing unit 620 sequentially writes the spiral servo pattern SSP to the blank disk 10 at a predetermined speed (hereinafter, sometimes referred to as spiral speed). In the BDW process, since data or patterns cannot be read from the blank disk 10, the servo pattern writing unit 620 does not perform read processing (or on-track processing). Instead, it takes the position of the disk 10, which corresponds to a reference clock once per cycle (hereinafter sometimes referred to as the clock reference position), as the starting point. Based on the speed information of the head 15 relative to the disk 10 (hereinafter sometimes referred to as the back EMF speed information) based on the back EMF generated from the VCM 14, it performs constant speed control on the head 15 at a predetermined spiral speed, and writes a spiral servo pattern SSP to the disk 10 from the inner direction in the radial direction, for example, from the innermost IMC to the outer direction, for example, from the outermost OMC. Alternatively, in the BDW process, the servo pattern writing unit 620 can also take the clock reference position of the blank disk 10 as the starting point, perform constant speed control on the head 15 at a predetermined spiral speed based on the back EMF speed information, and write a spiral servo pattern SSP to the disk 10 from the outer direction in the radial direction, for example, from the outermost OMC to the inner direction, for example, from the innermost IMC.

[0056] The servo pattern writing unit 620 writes a spiral servo pattern SSP while accelerating the head 15 to a predetermined spiral speed within the range from the starting point (clock reference position) to the point where constant speed control of the head 15 begins in the blank state disk 10. When the head 15 reaches the point where constant speed control begins, the servo pattern writing unit 620 writes the spiral servo pattern SSP by controlling the head 15 at a predetermined spiral speed within the range from the point where constant speed control begins to the point where deceleration begins in the blank state disk 10. When the head 15 reaches the point where deceleration begins, the servo pattern writing unit 620 writes the spiral servo pattern SSP by decelerating the head 15 from a predetermined speed to a predetermined speed within the range from the point where deceleration begins to the end point in the blank state disk 10. Hereinafter, the state in which the head 15 accelerates until it reaches a predetermined speed within the range from the starting point to the point where constant speed control of the head 15 begins will sometimes be referred to as acceleration state, acceleration time, acceleration control, or acceleration control; the state in which the head 15 writes at a constant speed will be referred to as constant speed state, constant speed time, constant speed control, or constant speed control; and the state in which the head 15 decelerates until it reaches a predetermined speed within the range from the starting point to the ending point will be referred to as deceleration state, deceleration time, or deceleration control. Furthermore, the term "the constant speed speed of the head 15 writing the spiral servo pattern" may be referred to as "spiral speed," as may the term "the speed of the head 15 writing the spiral servo pattern during acceleration," or as "the speed of the head 15 writing the spiral servo pattern during deceleration." Additionally, the term "the speed of the head 15 writing the spiral servo pattern (during acceleration, constant speed, and deceleration)" may be used collectively as "spiral speed."

[0057] The servo pattern writing unit 620 overlaps and writes multiple spiral servo patterns SSPs to the disk 10. In other words, the servo pattern writing unit 620 overlaps and writes other spiral servo patterns (hereinafter, sometimes simply referred to as other spiral servo patterns) SSPs that are different from the predetermined spiral servo pattern SSPs in a portion of the radial direction of the predetermined spiral servo pattern SSPs in the disk 10. Furthermore, the servo pattern writing unit 620 can also overwrite other spiral servo patterns SSPs in the disk 10 without misaligning them with the predetermined spiral servo pattern SSPs, as long as they are not overwritten on the exact same track, that is, as long as there is a slight deviation (misalignment). Hereinafter, "multiple spiral servo patterns that are overlapped and written" are sometimes referred to as "overlapped spiral servo patterns", or simply "spiral servo patterns". In addition, "spiral servo patterns that are not overlapped and written" and "one spiral servo pattern" are sometimes referred to as "normal spiral servo patterns", or simply "spiral servo patterns". Furthermore, the servo pattern writing unit 620 can also write overlapped spiral servo patterns across the entire surface of the disk 10. Additionally, the servo pattern writing unit 620 can also write an overlapping spiral servo pattern to a portion of the disk 10. In other words, the servo pattern writing unit 620 can also write an overlapping spiral servo pattern and a normal spiral servo pattern to the disk 10 in a mixed manner.

[0058] For example, the width of a typical spiral servo pattern SSP is smaller than the width of an overlay-written spiral servo pattern SSP. In other words, the width of an overlay-written spiral servo pattern SSP is larger than the width of a typical spiral servo pattern SSP. The width of a typical spiral servo pattern SSP is, for example, comparable to the width of the write head 15W. The width of a typical spiral servo pattern SSP can also be smaller than the width of the write head 15W, or it can be larger than the width of the write head 15W. The width of an overlay-written spiral servo pattern SSP is, for example, larger than the width of the write head 15W. The width of an overlay-written spiral servo pattern SSP can also be smaller than the width of the write head 15W, or it can be the same as the width of the write head 15W.

[0059] The servo pattern writing unit 620 overlaps and writes multiple spiral servo patterns (typically spiral servo patterns) SSPs onto a blank disk 10. The servo pattern writing unit 620 writes the multiple spiral servo patterns SSPs onto the blank disk 10 in a staggered manner in one direction (hereinafter, sometimes referred to as the forward direction), for example, the radial direction, thus writing the overlapped spiral servo pattern SSPs. The servo pattern writing unit 620 writes the multiple spiral patterns (typically spiral servo patterns) SSPs onto the blank disk 10 in a staggered manner in the radial direction at predetermined intervals (hereinafter, sometimes referred to as offsets), thus writing the overlapped spiral servo pattern SSPs. Hereinafter, the direction in which the multiple spiral servo patterns (typically spiral servo patterns) SSPs are overlapped and written is sometimes referred to as the forward direction. That is to say, the forward direction corresponds to the direction in which a portion of a predetermined spiral servo pattern is overlapped and written with other spiral servo patterns different from that spiral servo pattern. Furthermore, when writing an overlapping spiral servo pattern SSP, the servo pattern writing unit 620 can also write (or overwrite) each of the normal spiral servo patterns in the overlapping spiral servo pattern at the same position repeatedly a predetermined number of times (hereinafter sometimes referred to as the number of repetitions).

[0060] For example, the servo pattern writing unit 620 writes three overlapping spiral servo patterns SSPs in a blank disk 10, staggered by 0.5 tracks in the forward direction, thus writing overlapping spiral servo patterns SSPs. Furthermore, the servo pattern writing unit 620 can also write two overlapping spiral servo patterns SSPs in a blank disk 10, staggered by 0.5 tracks in the forward direction, thus writing overlapping spiral servo patterns SSPs. It can also write four or more overlapping spiral servo patterns SSPs in a blank disk 10, staggered by 0.5 tracks in the forward direction, thus writing overlapping spiral servo patterns SSPs. Moreover, the overlapping range of the written spiral servo patterns SSPs is not limited to 0.5 tracks; for example, it can be arbitrarily staggered within the range of 0 to 1, thus writing overlapping spiral servo patterns SSPs.

[0061] The servo pattern writing unit 620 calculates or obtains the center position (hereinafter sometimes referred to as the center position of the spiral pattern) of the width of the spiral servo pattern SSP. Whenever the servo pattern writing unit 620 detects the synchronization mark (Sync) of the read signal (or read signal strength) of the spiral servo pattern SSP, it obtains the demodulated MAG value and calculates or obtains the position corresponding to half (1 / 2) of the accumulated value (hereinafter sometimes simply referred to as the accumulated value) of the demodulated MAG value as the center position of the spiral pattern. The demodulated MAG value is equivalent to the value associated with the read signal. The demodulated MAG value is, for example, equivalent to the signal level or area.

[0062] For example, whenever the servo pattern writing unit 620 detects the synchronization mark of the normal spiral servo pattern SSP, it obtains the demodulated MAG value and calculates or obtains the position corresponding to half (1 / 2) of the cumulative value of the demodulated MAG value as the center position of the spiral pattern.

[0063] For example, whenever the servo pattern writing unit 620 detects the synchronization mark of the overlapping writing spiral servo pattern SSP, it obtains the demodulated MAG value and calculates or obtains the position corresponding to half (1 / 2) of the cumulative value of the demodulated MAG value as the center position of the spiral pattern.

[0064] The servo pattern writing unit 620 writes the product servo pattern PSV to the disk 10. In the self-servo writing (SSW) process (hereinafter sometimes referred to as the SSW process or SSW procedure), the servo pattern writing unit 620 writes the product servo pattern PSV based on the spiral servo pattern SSP. In the SSW process, the servo pattern writing unit 620, based on the spiral servo pattern SSP and the spiral pattern center position, corrects for position error by using the deviation of the spiral pattern center position for position error calculation, and writes the product servo pattern PSV from the inner direction in the radial direction, for example, the innermost IMC, to the outer direction, for example, the outermost OMC, in the radial direction. Alternatively, in the SSW process, the servo pattern writing unit 620 may also, based on the spiral servo pattern SSP and the spiral pattern center position, correct for position error by using the deviation of the spiral pattern center position for position error calculation, and write the product servo pattern PSV from the outer direction in the radial direction, for example, the outermost OMC, to the inner direction, for example, the innermost IMC. Furthermore, the BDW process and the SSW process are sometimes collectively referred to as the SSW process. The servo pattern writing unit 620 can also write spiral servo patterns (SSP) during the SSW process.

[0065] The positioning control unit 630 performs positioning control of the head 15. The positioning control unit 630 performs positioning control of the head 15 based on the spiral servo pattern SSP, the center position of the spiral pattern, and the product servo pattern PSV. The positioning control unit 630 calculates the position error based on the center position of the spiral pattern and performs positioning control of the head 15 based on the calculated position error. In other words, the MPU 60 calculates the position error using the deviation of the spiral pattern center position and performs positioning control of the head 15 based on the calculated position error.

[0066] Figure 3 This is a schematic diagram illustrating an example of the write signal for a spiral servo pattern SSP. In Figure 3 In the middle, the horizontal axis represents time. Figure 3 The horizontal axis of time passes as it travels towards the front of the arrow.

[0067] MPU60, for example, according to... Figure 3The write signal of the spiral servo pattern SSP shown is written to disk 10 by alternately writing the basic digit and the synchronization mark (Sync) to the spiral servo pattern SSP.

[0068] Figure 4 This is a schematic diagram illustrating an example of the write processing method for a typical spiral servo pattern SSP. Figure 4 The value in the figure represents the radial direction and the direction in which the spiral servo pattern SSP is written, along with the passage of time (hereinafter, sometimes also referred to as the time direction). Figure 4 The radius direction moves outward as it moves toward the front of the arrow, and inward as it moves toward the side opposite to the front of the arrow. Figure 4 The diagram shows typical spiral servo patterns SSPe1 (SSP), SSPe2 (SSP), and SSPe3 (SSP) arranged continuously at predetermined intervals on disk 10. Figure 4 In the typical spiral servo patterns SSPe1(SSP), SSPe2(SSP), and SSPe3(SSP), the vertical lines correspond to the synchronization markers (Sync). Figure 4 In the example shown, the width of the spiral servo patterns SSPe1, SSPe2, and SSPe3 is typically equivalent to the width of the 15W write head. Figure 4 The value ORRe represents the path (hereinafter sometimes referred to as the on-orbit path) of the read head 15R relative to the typical spiral servo pattern SSP (SSPe1, SSPe2, and SSPe3) when in orbit. Figure 4 For ease of explanation, the spiral servo patterns SSPe1 (SSP), SSPe2 (SSP), and SSPe3 (SSP) are typically shown as extending obliquely in a strip shape, but in reality, they can be arranged in a spiral shape on disk 10. Figure 4 In this context, RSe11, RSe21, and RSe31 represent the magnitude or strength of the read signal (hereinafter sometimes referred to as the on-orbit read signal strength) when reading a typical spiral servo pattern SSP (SSPe1, SSPe2, and SSPe3) using the read head 15R in orbit. Figure 4 The text indicates the time. Figure 4The time progresses as the arrow travels towards its forward end. The on-track read signal strength RSe11 corresponds to the magnitude of the signal read by the on-track (or configured on a predetermined track) read head 15R on the typical spiral servo pattern SSPe1. The on-track read signal strength RSe21 corresponds to the magnitude of the signal read by the on-track read head 15R on the typical spiral servo pattern SSPe2. The on-track read signal strength RSe31 corresponds to the magnitude of the signal read by the on-track read head 15R on the typical spiral servo pattern SSPe3. In the on-track read signal strengths RSe11, RSe21, and RSe31, the vertical lines correspond to the read signal strength of the synchronization mark (Sync).

[0069] exist Figure 4 In the example shown, the MPU60 writes the typical spiral servo patterns SSPe1, SSPe2, and SSPe3 to disk 10 at time intervals in the time direction. The MPU60 reads the typical spiral servo patterns SSPe1, SSPe2, and SSPe3 by keeping the read head 15R on track according to the on-track path ORRe, and obtains the on-track read signal strengths RSe11, RSe21, and RSe31.

[0070] Figure 5 This is a schematic diagram illustrating an example of a typical write processing method for a spiral servo pattern. Figure 5 The middle indicates Figure 4 The typical spiral servo patterns shown are SSPe1(SSP), SSPe2(SSP), and SSPe3(SSP). Figure 5 The path SRRe represents the path of the read head 15R relative to the typical spiral servo pattern SSP (SSPe1, SSPe2 and SSPe3) during seek (hereinafter, sometimes also called the seek path). Figure 5 The values ​​RSe12, RSe22, and RSe32 represent the read signal strengths (hereinafter sometimes referred to as seek-time read signal strengths) when reading typical spiral servo patterns SSP (SSPe1, SSPe2, and SSPe3) through the seek-time read head 15R. Seek-time read signal strength RSe12 corresponds to the magnitude of the signal read from spiral servo pattern SSPe1 by the seek-time read head 15R. Seek-time read signal strength RSe22 corresponds to the magnitude of the signal read from spiral servo pattern SSPe2 by the seek-time read head 15R. Seek-time read signal strength RSe32 corresponds to the magnitude of the signal read from spiral servo pattern SSPe3 by the seek-time read head 15R.

[0071] exist Figure 5In the example shown, the MPU60 uses the seek path SRRe to cause the read head 15R to seek and read the typical spiral servo patterns SSPe1, SSPe2 and SSPe3, and obtains the seek signal strengths RSe12, RSe22 and RSe32.

[0072] exist Figure 5 In the example shown, the seek-time read signal strengths RSe12, RSe22, and RSe32 are less than the on-orbit read signal strengths RSe11, RSe21, and RSe31. Therefore, the number of sync markers read by the seek-time read head 15R is less than the number of sync markers read by the on-orbit read head 15R.

[0073] Figure 6 This is a schematic diagram illustrating an example of the write processing method for overlapping writing of the spiral servo pattern SSP1 according to this embodiment. Figure 6 The radius and time directions are represented in the figure. Figure 6 In the context of the universe, the "clockwise" direction is equivalent to the "outer" direction. However, the clockwise direction can also be the "inner" direction, or any direction other than the "inner" or "outer" directions. Figure 6 The image shows the overlapping writing of the spiral servo pattern SSP1 (SSP). In Figure 6 For example, the overlapping writing of the spiral servo pattern SSP1 is constructed by overlapping and writing the usual spiral servo patterns SSP11, SSP12, and SSP13 in the described order. In other words, the overlapping writing of the spiral servo pattern SSP1 includes the usual spiral servo patterns SSP11, SSP12, and SSP13. Figure 6 In the typical spiral servo patterns SSP11, SSP12, and SSP13 shown, the vertical lines correspond to the synchronization markers (Sync). Figure 6 For ease of explanation, the spiral servo pattern SSP1 (SSP) is represented as an overlapping writing. Typically, the spiral servo patterns SSP11, SSP12 and SSP13 extend obliquely in a strip shape, but in reality they can be arranged in a spiral shape on disk 10.

[0074] exist Figure 6 In the example shown, the MPU60 writes a normal spiral servo pattern SSP11 to the disk 10 at a predetermined spiral speed. After writing the normal spiral servo pattern SSP11, the MPU60 offsets the normal spiral servo pattern SSP11 in the forward direction by a predetermined offset and overlaps it with the normal spiral servo pattern SSP12 at a predetermined spiral speed. After overlapping the normal spiral servo pattern SSP11 with the normal spiral servo pattern SSP12, the MPU60 offsets the normal spiral servo pattern SSP12 in the forward direction by a predetermined offset and overlaps it with the normal spiral servo pattern SSP13 at a predetermined spiral speed, thus writing the overlapping spiral servo pattern SSP1.

[0075] Figure 7 This is a schematic diagram of an example of table TB1, which represents the offset of the overlapping helical servo pattern involved in this embodiment. Figure 7 The middle indicates that with Figure 6 Table TB1 shows the offsets corresponding to the overlapping write spiral servo pattern SSP1. Table TB1 contains the numbers corresponding to the order in which the spiral servo patterns are overlapping (hereinafter, sometimes referred to as overlapping write numbers), the offset relative to the spiral servo pattern SSP1 with overlapping write number 1, and the number of repetitions of each spiral servo pattern SSP. Table TB1 may also be recorded in a predetermined recording area, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0076] exist Figure 7 In the example shown, after writing the normal spiral servo pattern SSP11, as shown in Table TB1, the MPU60 offsets the normal spiral servo pattern SSP11 by -0.5 tracks in the forward direction and overlaps it with the normal spiral servo pattern SSP12 at a predetermined spiral speed. After overlapping the normal spiral servo pattern SSP11 with the normal spiral servo pattern SSP12, the MPU60 offsets the normal spiral servo pattern SSP11 by -1.0 tracks in the forward direction and overlaps it with the normal spiral servo pattern SSP12 with the normal spiral servo pattern SSP13 at a predetermined spiral speed, thus writing the overlapping spiral servo pattern SSP1.

[0077] Figure 8 This is a schematic diagram illustrating an example of the write processing method for overlapping writing of a spiral servo pattern according to this embodiment. Figure 8 The symbol represents the radial direction, the forward direction, and the time direction. Figure 8 The diagram shows overlapping write spiral servo patterns SSP1 (SSP), SSP2 (SSP), and SSP3 (SSP) arranged sequentially at predetermined intervals on disk 10. Figure 8 The overlapping lines are written into the spiral servo patterns SSP1, SSP2, and SSP3, with the vertical lines acting as synchronization markers (Sync). Figure 8 In the process, the overlapping helical servo pattern SSP1 includes the typical helical servo patterns SSP11, SSP12, and SSP13. The overlapping helical servo pattern SSP2 includes the typical helical servo patterns SSP21, SSP22, and SSP23. The overlapping helical servo pattern SSP3 includes the typical helical servo patterns SSP31, SSP32, and SSP33. Figure 8In the example shown, the widths of the typical spiral servo patterns SSP11, SSP12, SSP13, SSP21, SSP22, SSP23, SSP31, SSP32, and SSP33 are equivalent to the width of a 15W write head. Figure 8 The text describes the on-orbit path ORR1 of the read head 15R relative to the overlapping write spiral servo patterns SSP (SSP1, SSP2, and SSP3) during on-orbit writing. Figure 8 For ease of explanation, the overlapping spiral servo patterns SSP1 (SSP), SSP2 (SSP), and SSP3 (SSP) are shown as extending obliquely in a strip shape, but in reality they are arranged in a spiral shape on disk 10. Figure 8 The values ​​represent the on-orbit read signal strengths RS11, RS21, and RS31. Figure 8 The values ​​represent time. The on-orbit read signal strength RS11 corresponds to the magnitude of the signal read by the on-orbit read head 15R on the overlapping helical servo pattern SSP1. The on-orbit read signal strength RS21 corresponds to the magnitude of the signal read by the on-orbit read head 15R on the overlapping helical servo pattern SSP2. The on-orbit read signal strength RS31 corresponds to the magnitude of the signal read by the on-orbit read head 15R on the overlapping helical servo pattern SSP3. In the on-orbit read signal strengths RS11, RS21, and RS31, the vertical lines correspond to the read signal strength at which the synchronization marker was read.

[0078] exist Figure 8 In the example shown, the MPU60 writes the normally overlapping spiral servo patterns SSP11, SSP12, and SSP13 onto disk 10 in a forward direction to write the overlapping spiral servo pattern SSP1. The MPU60 then writes the normally overlapping spiral servo patterns SSP21, SSP22, and SSP23 from the overlapping spiral servo pattern SSP1 at time intervals in the forward direction to write the overlapping spiral servo pattern SSP2. Finally, the MPU60 writes the normally overlapping spiral servo patterns SSP31, SSP32, and SSP33 from the overlapping spiral servo pattern SSP2 at time intervals in the forward direction to write the overlapping spiral servo pattern SSP3.

[0079] exist Figure 8 In the example shown, the MPU60 reads the overlapping spiral servo patterns SSP1, SSP2 and SSP3 by keeping the read head 15R on track according to the on-track path ORR1, and obtains the on-track read signal strengths RS11, RS21 and RS31.

[0080] The on-orbit read signal strengths RS11, RS21, and RS31 are greater than the on-orbit read signal strengths RSe11, RSe21, and RSe31. Therefore, the number of synchronization marks (Sync) for overlapping helical servo pattern SSPs read by the on-orbit read head 15R is greater than the number of synchronization marks (Sync) for reading a typical helical servo pattern SSP by the on-orbit read head 15R.

[0081] Figure 9 This is a schematic diagram illustrating an example of the write processing method for overlapping writing of a spiral servo pattern according to this embodiment. Figure 9 The middle indicates Figure 8 The overlapping written spiral servo patterns SSP1 (SSP), SSP2 (SSP), and SSP3 (SSP) are shown. Figure 9 The text indicates the seek path SRR1 of the read head 15R during seek relative to the overlapping writing spiral servo patterns SSP (SSP1, SSP2 and SSP3). Figure 9 The values ​​represent the seek signal strengths RS12, RS22, and RS32. RS12 represents the magnitude of the signal read from the seek head 15R when the overlapping helical servo pattern SSP1 is read. RS22 represents the magnitude of the signal read from the seek head 15R when the overlapping helical servo pattern SSP2 is read. RS32 represents the magnitude of the signal read from the seek head 15R when the overlapping helical servo pattern SSP3 is read.

[0082] exist Figure 9 In the example shown, the MPU60 uses the read head 15R to seek along the seek path SRR1 while reading the overlapping spiral servo patterns SSP1, SSP2 and SSP3, and obtains the read signal strengths RS12, RS22 and RS32 during the seek.

[0083] exist Figure 9 In the example shown, the seek-time read signal strengths RS12, RS22, and RS32 are greater than the seek-time read signal strengths RSe12, RSe22, and RSe32. Therefore, the number of sync markers read by the seek-time read head 15R from the overlay-written spiral servo pattern SSP is greater than the number of sync markers read by the seek-time read head 15R from the typical spiral servo pattern SSP.

[0084] Figure 10 This is a schematic diagram illustrating an example of a method for calculating the center position of a typical spiral servo pattern SSPe1. Figure 10 The middle indicates Figure 4The diagram shows the typical spiral servo pattern SSPe1, the on-orbit path ORRe, and the on-orbit read signal strength of the typical spiral servo pattern SSPe1. Figure 10 In the table, the demodulated MAG value (hereinafter sometimes referred to as the on-orbit normal demodulation MAG value) corresponding to the on-orbit read signal strength RSe1 of the normal spiral servo pattern SSPe1 is represented, as well as the cumulative value of the demodulated MAG value corresponding to this on-orbit normal demodulation MAG value (hereinafter sometimes referred to as the on-orbit normal cumulative value or cumulative value). The horizontal axis of the on-orbit normal demodulation MAG value and the on-orbit normal cumulative value represents time.

[0085] exist Figure 10 In the example shown, the MPU60 obtains the on-orbit normal demodulation MAG values ​​corresponding to each timing of the detection of a synchronization marker (Sync) based on the on-orbit read signal strength of the normal spiral servo pattern SSPe1. The MPU60 accumulates the obtained on-orbit normal demodulation MAG values ​​corresponding to each timing of the detection of a synchronization marker based on the on-orbit read signal strength of the normal spiral servo pattern SSPe1 to calculate an on-orbit normal cumulative value, and calculates or obtains the position corresponding to half (1 / 2) of the timing of the on-orbit normal cumulative value as the spiral pattern center position of the normal spiral servo pattern SSPe1. The MPU60 may also record the calculated spiral pattern center position of the normal spiral servo pattern SSPe1 in a predetermined recording area, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0086] Figure 11 This is a schematic diagram illustrating an example of a method for calculating the center position of the spiral pattern of the overlapping spiral servo pattern SSP1 involved in this embodiment. Figure 11 The middle indicates Figure 8 The diagram shows the overlapping write spiral servo pattern SSP1, the on-orbit path ORR1, and the on-orbit read signal strength RS11 of the overlapping write spiral servo pattern SSP1. Figure 11 The table shows the demodulated MAG value (hereinafter sometimes referred to as the on-orbit overwritten demodulated MAG value) corresponding to the on-orbit read signal strength RS11 of the overwritten spiral servo pattern SSP1, and the cumulative value of the demodulated MAG value corresponding to this on-orbit overwritten demodulated MAG value (hereinafter sometimes referred to as the on-orbit overwritten cumulative value or cumulative value). The horizontal axis of the on-orbit overwritten demodulated MAG value and the on-orbit overwritten cumulative value represents time.

[0087] exist Figure 11In the example shown, the MPU60 obtains the on-track overwrite demodulation MAG values ​​corresponding to each timing of the detection of the synchronization marker (Sync) based on the on-track read signal strength RS11 of the overwrite spiral servo pattern SSP1. The MPU60 accumulates the obtained on-track overwrite demodulation MAG values ​​corresponding to each timing of the detection of the synchronization marker based on the on-track read signal strength RS11 of the overwrite spiral servo pattern SSP1 to calculate the on-track overwrite cumulative value, and calculates or obtains the position corresponding to half (1 / 2) of the on-track overwrite cumulative value as the spiral pattern center position of the overwrite spiral servo pattern SSP1. The MPU60 may also record the calculated spiral pattern center position of the overwrite spiral servo pattern SSP1 in a predetermined recording area, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0088] Figure 12 This is a flowchart illustrating an example of the servo pattern writing method according to this embodiment.

[0089] MPU60 writes a predetermined spiral servo pattern (normal spiral servo pattern) SSP (B1201) to disk 10, offset by a predetermined amount in the forward direction, and overlaps this spiral servo pattern (normal spiral servo pattern) SSP with other spiral servo patterns (normal spiral servo patterns) SSPs to write overlapping spiral servo patterns SSP (B1202). MPU60 determines whether to overlap the spiral servo pattern (normal spiral servo pattern) SSPs to write (B1203).

[0090] If it is determined that the spiral servo pattern (normal spiral servo pattern) SSP should be written in an overlapping manner (B1203: Yes), the MPU60 proceeds to the B1202 process. If it is determined that the spiral servo pattern (normal spiral servo pattern) SSP should not be written in an overlapping manner (B1203: No), the MPU60 ends the process.

[0091] Figure 13 This is a flowchart illustrating an example of the servo pattern writing method according to this embodiment.

[0092] MPU60 reads the helical servo pattern SSP (B1301). Whenever the synchronization marker of the read signal of the helical servo pattern SSP is detected, it obtains each demodulated MAG value (B1302). MPU60 calculates the cumulative value of the demodulated MAG values ​​corresponding to the helical servo pattern SSP (B1303), calculates the position corresponding to the timing of half (1 / 2) of the cumulative value of the demodulated MAG value as the center position of the helical pattern (B1304), and ends the processing.

[0093] According to this embodiment, the disk drive 1 writes multiple normally written spiral servo patterns SSPs in a staggered, longitudinal direction on the disk 10 to form overlapping spiral servo patterns SSPs. Whenever the disk drive 1 detects the synchronization marker of the read signal of a spiral servo pattern SSP, it acquires a demodulation MAG value and calculates the position corresponding to a timing value equal to half (1 / 2) of the cumulative value of the demodulation MAG value as the spiral pattern center position. Therefore, even with a narrow write width at the head 15, the disk drive 1 can reduce defects in the SSW process. Thus, the disk drive 1 can improve reliability.

[0094] Next, other embodiments of the disk device according to the first embodiment will be described. In the other embodiments, the same reference numerals are used for the parts that are the same as those in the first embodiment described above, and their detailed descriptions are omitted.

[0095] (Second Implementation)

[0096] The disk device 1 according to the second embodiment differs from the disk device 1 of the first embodiment in that the write processing method of the spiral servo pattern SSP is different.

[0097] The MPU60 writes an overlay helical servo pattern SSP and writes (or overwrites) an erase pattern to the overlay helical servo pattern SSP. Since the MPU60 expects the two ends (hereinafter sometimes simply referred to as the ends of the erase pattern) of the erase pattern in the width direction, such as the radial direction, of the overlay helical servo pattern to have the same shape, the erase pattern is written (or overwritten) only once in the center of the width of the overlay helical servo pattern SSP. Alternatively, the MPU60 may write (or overwrite) the erase pattern outside the center of the width of the overlay helical servo pattern SSP. Furthermore, the MPU60 may write (or overwrite) the erase pattern multiple times to the overlay helical servo pattern SSP. The erase pattern corresponds to an AC erase pattern with a frequency higher than predetermined data, such as the frequency of a typical helical servo pattern. The erase pattern corresponds to an AC erase pattern with a frequency several times higher than the frequency of a typical helical servo pattern, such as four times higher.

[0098] The MPU60 calculates or obtains the center position (hereinafter, sometimes referred to as the erase pattern center position) of the width of the erase pattern of the overlapping write spiral servo pattern (hereinafter, sometimes referred to as the overlapping write erase spiral pattern) SSP that has overwritten the erase pattern. Whenever the MPU60 detects the synchronization marker (Sync) of the read signal (or read signal strength) of the overlapping write erase spiral pattern SSP, it obtains the demodulation MAG value (hereinafter, sometimes referred to as the erase spiral demodulation MAG value). The MPU60 calculates the difference (hereinafter, sometimes referred to as the erase spiral difference value) between the largest erase spiral demodulation MAG value (hereinafter, sometimes referred to as the maximum erase spiral demodulation MAG value or demodulation MAG value) in the region excluding the erase pattern of the overlapping write erase spiral pattern and each erase spiral demodulation MAG value (hereinafter, sometimes referred to as the erase demodulation MAG value or demodulation MAG value) in the region containing the erase pattern of the overlapping write erase spiral pattern. The MPU60 calculates the cumulative value obtained by accumulating the differential values ​​of each eraser spiral (hereinafter sometimes referred to as the differential cumulative value or cumulative value), and calculates or obtains the position corresponding to half (1 / 2) of the timing of the differential cumulative value as the center position of the eraser pattern.

[0099] The MPU60 calculates the positional error based on the center position of the erased pattern, and performs positioning control of the head 15 based on the calculated positional error. In other words, the MPU60 uses the deviation of the center position of the erased pattern to calculate the positional error, and performs positioning control of the head 15 based on the calculated positional error.

[0100] Figure 14 This is a schematic diagram illustrating an example of the write processing method for the overlapping write-erase spiral pattern SSP4 involved in this embodiment. Figure 14 The symbol represents the radial direction, the forward direction, and the time direction. Figure 14 In the context of the universe, the "clockwise" direction is equivalent to the "outer" direction. However, the clockwise direction can also be the "inner" direction, or any direction other than the "inner" or "outer" directions. Figure 14 The image shows the overlapping write-erase spiral pattern SSP4 (SSP). In Figure 14 For example, the overlapping write erase spiral pattern SSP4 includes the typical spiral servo patterns SSP41, SSP42, SSP43, SSP44, SSP45, and SSP46, as well as the erase pattern EP4. Figure 14 In the typical spiral servo patterns SSP41, SSP42, SSP43, SSP44, SSP45, and SSP46 shown, the vertical lines correspond to the synchronization markers (Sync). Figure 14For ease of explanation, the overlapping write erase spiral pattern SSP4, the typical spiral servo patterns SSP41 to SSP46, and the erase pattern EP4 are shown as extending obliquely in a strip shape, but in reality they can be arranged in a spiral shape on disk 10.

[0101] exist Figure 14 In the example shown, the MPU60 writes a normal spiral servo pattern SSP41 to the disk 10 at a predetermined spiral speed. After writing the normal spiral servo pattern SSP41, the MPU60 writes the normal spiral servo pattern SSP42, offset in the forward direction by a predetermined offset relative to the normal spiral servo pattern SSP41, at a predetermined spiral speed. After writing the normal spiral servo pattern SSP42, which is offset in the forward direction by a predetermined offset relative to the normal spiral servo pattern SSP42, the MPU60 writes the normal spiral servo pattern SSP43, which is offset in the forward direction by a predetermined offset relative to the normal spiral servo pattern SSP42, at a predetermined spiral speed. After writing the normal spiral servo pattern SSP43, which is offset in the forward direction by a predetermined offset relative to the normal spiral servo pattern SSP43, the MPU60 writes the normal spiral servo pattern SSP44, which is offset in the forward direction by a predetermined offset relative to the normal spiral servo pattern SSP43. After overlapping and writing the normal spiral servo pattern SSP44 with the normal spiral servo pattern SSP43, the MPU60 overlaps and writes the normal spiral servo pattern SSP45 with the normal spiral servo pattern SSP44 at a predetermined offset in the forward direction and at a predetermined spiral speed. After overlapping and writing the normal spiral servo pattern SSP45 with the normal spiral servo pattern SSP44, the MPU60 overlaps and writes the normal spiral servo pattern SSP46 with the normal spiral servo pattern SSP45 at a predetermined offset in the forward direction and at a predetermined spiral speed, thus writing the overlapping spiral servo pattern.

[0102] The MPU60 writes the overlapping write erase spiral pattern SSP4 by overwriting the erase pattern EP4 in the center of the width of the overlapping write spiral servo patterns SSP41 to SSP46, which contain the usual spiral servo patterns SSP41 to SSP46.

[0103] Figure 15 This is a schematic diagram of an example of table TB2, which represents the offset of the overlapping write-erase spiral pattern according to the second embodiment. Figure 15 The middle indicates that with Figure 14 Table TB2 shows the offsets corresponding to the overlapping write erase spiral pattern SSP4. Table TB2 contains the overlapping write number corresponding to the order of overlapping write spiral servo patterns in the overlapping write erase spiral pattern, the offset relative to the overlapping write number 4 spiral servo pattern SSP44, and the number of repetitions of each spiral servo pattern SSP. Table TB2 may also be recorded in a predetermined recording area, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0104] exist Figure 15 In the example shown, the MPU60 writes the spiral servo pattern SSP41 from the position where the spiral servo pattern SSP44 is configured, offset by +1.5 tracks in the opposite direction (hereinafter sometimes referred to as the reverse direction). The MPU60 can also repeatedly write (or overwrite) the spiral servo pattern SSP41 in overlapping fashion 1 to 5 times.

[0105] Starting from the position where the spiral servo pattern SSP44 is configured, the MPU60 writes the spiral servo pattern SSP42 in a direction opposite to the clockwise direction (hereinafter sometimes referred to as the reverse direction) by +1.0 tracks, overlapping the spiral servo pattern SSP41 in the clockwise direction. The MPU60 can also repeatedly write (or overwrite) the spiral servo pattern SSP42 in an overlapping manner 1 to 5 times.

[0106] Starting from the position where the spiral servo pattern SSP44 is configured, the MPU60 writes the spiral servo pattern SSP43 in the opposite direction, offset by +0.5 tracks, overlapping with the spiral servo pattern SSP42 in the forward direction. The MPU60 can also repeatedly write (or overwrite) the spiral servo pattern SSP43 in an overlapping manner 1 to 5 times.

[0107] The MPU60 writes the spiral servo pattern SSP44 in a forward overlapping manner with the spiral servo pattern SSP43. The MPU60 can also repeatedly write (or overwrite) the spiral servo pattern SSP44 in an overlapping manner 1 to 5 times.

[0108] Starting from the position where the spiral servo pattern SSP44 is configured, the MPU60 writes the spiral servo pattern SSP45, offset by -0.5 tracks in the clockwise direction, overlapping with the spiral servo pattern SSP44 in the clockwise direction. The MPU60 can also repeatedly write (or overwrite) the spiral servo pattern SSP45 in an overlapping manner 1 to 5 times.

[0109] Starting from the position of the configured spiral servo pattern SSP44, the MPU60 offsets it by -1.0 tracks in the forward direction and overlaps it with the spiral servo pattern SSP45 in the forward direction to write the spiral servo pattern SSP46, thereby writing an overlapping spiral servo pattern containing spiral servo patterns SSP41 to SSP46. The MPU60 can also repeatedly overlap and write (or overwrite) the spiral servo pattern SSP46 1 to 5 times.

[0110] Starting from the position of the configured spiral servo pattern SSP44, the MPU60 offsets the position by 0.5 to 0 tracks in the clockwise direction, and overwrites the erase pattern EP4 in the center of the width of the overlapping spiral servo patterns SSP41 to SSP46, thus writing the overlapping write erase spiral pattern SSP4. The MPU60 only overwrites the erase pattern EP4 once.

[0111] Furthermore, if the MPU60 can perform gapless writing even if it cannot achieve sufficient overlap writing accuracy, it can repeatedly overlap or overwrite the spiral servo patterns SSP41 to SSP46 more than 6 times. In addition, the MPU60 can also overlap write up to 5 spiral servo patterns SSP to write an overlapped spiral servo pattern, and it can also overlap write more than 7 spiral servo patterns SSP to write an overlapped spiral servo pattern.

[0112] Figure 16 This is a schematic diagram illustrating an example of the write processing method for overlapping write-erase spiral patterns according to the second embodiment. Figure 16 The symbol represents the radial direction, the forward direction, and the time direction. Figure 16 The diagram shows overlapping write-erase spiral patterns SSP4 (SSP) and SSP5 (SSP) arranged consecutively at predetermined intervals on disk 10. Figure 16 The overlapping strokes are written into the erase spiral patterns SSP4 and SSP5, with the vertical lines corresponding to the sync markers. Figure 16 In the process, the overlapping write erase spiral pattern SSP4 includes spiral servo patterns SSP41, SSP42, SSP43, SSP45, SSP46 and erase pattern EP4. The overlapping write erase spiral pattern SSP5 includes spiral servo patterns SSP51, SSP52, SSP53, SSP55, SSP56 and erase pattern EP5. Figure 16 In the example shown, the width of the spiral servo patterns SSP41, SSP42, SSP43, SSP45, SSP46, SSP51, SSP52, SSP53, SSP55, SSP56, and the erase patterns EP4 and EP5 are equivalent to the width of the write head 15W. Figure 16 The text indicates the on-orbit path ORR2 of the read head 15R relative to the overlapping write-erase spiral pattern SSP (SSP4 and SSP5) during on-orbit operation. Figure 16 For ease of explanation, the overlapping write-erase spiral patterns SSP4 (SSP) and SSP5 (SSP) are shown as extending obliquely in a strip shape, but in reality they can be arranged in a spiral shape on disk 10. Figure 16 The values ​​represent the on-orbit read signal strengths RS41, RS42, RS51, and RS52. Figure 16The values ​​represent time. On-orbit read signal strengths RS41 and RS42 correspond to the magnitudes of signals read by the overlay write-erase spiral pattern SSP4 via the on-orbit read head 15R. On-orbit read signal strengths RS51 and RS52 correspond to the magnitudes of signals read by the overlay write-eradication spiral pattern SSP5 via the on-orbit read head 15R. In the on-orbit read signal strengths RS41, RS42, RS51, and RS52, the vertical lines correspond to the read signal strengths at which the synchronization marker was read.

[0113] exist Figure 16 In the example shown, the MPU60 overwrites the erase pattern EP4 onto the center of the width of the overlapping-write spiral servo pattern SSP4, which is obtained by overlapping and writing spiral servo patterns SSP41 to SSP46 in the forward direction on disk 10, thus writing the overlapping-write erase spiral pattern SSP4. The MPU60 then, at time intervals from the overlapping-write erase spiral pattern SSP4, overwrites the erase pattern EP5 onto the center of the width of the overlapping-write spiral servo pattern SSP5, which is obtained by overlapping and writing spiral servo patterns SSP51 to SSP56 in the forward direction on disk 10, thus writing the overlapping-write erase spiral pattern SSP5.

[0114] exist Figure 16 In the example shown, the MPU60 reads the overlapping write erase spiral patterns SSP4 and SSP5 by keeping the read head 15R on track according to the on-track path ORR2, and obtains the on-track read signal strengths RS41, RS42, RS51 and RS52.

[0115] Figure 17 This is a schematic diagram illustrating an example of the write processing method for overlapping write-erase spiral patterns according to the second embodiment. Figure 17 The middle indicates Figure 16 The overlapping write-erase spiral patterns SSP4 (SSP) and SSP5 (SSP) are shown. Figure 17 The text indicates the seek path SRR2 of the read head 15R relative to the overlapping write-erase spiral pattern SSP (SSP4 and SSP5) during seek. Figure 17 The values ​​represent the seek-time read signal strengths RS43, RS44, RS53, and RS54. Seek-time read signal strengths RS43 and RS44 correspond to the signal magnitudes read by the seek-time read head 15R on the overlay write-erase spiral pattern SSP4. Seek-time read signal strengths RS53 and RS54 correspond to the signal magnitudes read by the seek-time read head 15R on the overlay write-erase spiral pattern SSP5.

[0116] exist Figure 17In the example shown, the MPU60 uses the seek path SRR2 to make the read head 15R seek to read the overlapping write erase spiral patterns SSP4 and SSP5, and obtains the read signal strengths RS43, RS44, RS53 and RS54 during the seek.

[0117] Figure 18 This is a schematic diagram illustrating an example of a method for calculating the center position of the erase pattern of the overlapping write erase spiral pattern SSP4 according to the second embodiment. Figure 18 The middle indicates Figure 16 The overlapping write-erase spiral pattern SSP4, the on-orbit path ORR2, and the on-orbit read signal strengths RS41 and RS42 of the overlapping write-erase spiral pattern SSP4 are shown. Figure 18 The table shows the erase screw demodulation MAG values ​​corresponding to the on-orbit read signal strengths RS41 and RS42 of the overlapping erase screw pattern SSP4, the erase screw difference value between the maximum (MAX) erase screw demodulation MAG value and the erase demodulation MAG value, and the cumulative difference value corresponding to the erase screw difference value (hereinafter sometimes referred to as the on-orbit cumulative difference value or cumulative difference value). The horizontal axis of the erase screw demodulation MAG value, the erase screw difference value, and the cumulative difference value represents time.

[0118] exist Figure 18 In the example shown, the MPU60 obtains the demodulation MAG values ​​of each erase spiral corresponding to the timing of the detection of the synchronization mark (Sync) based on the on-orbit read signal strengths RS41 and RS42 of the overlapping write erase spiral pattern SSP4. The MPU60 calculates the difference between the maximum erase spiral demodulation MAG value and the difference between each erase spiral MAG value in the overlapping write erase spiral pattern SSP4. The MPU60 calculates the cumulative difference value obtained by accumulating these cumulative difference values, and calculates the position corresponding to half (0.5) of this cumulative difference value as the center position of the erase pattern of the overlapping write erase spiral pattern SSP4. The MPU60 may also record the calculated center position of the erase pattern of the overlapping write erase spiral pattern SSP4 in a predetermined recording area, such as disk 10, volatile memory 70, non-volatile memory 80, or buffer memory 90.

[0119] Figure 19 This is a flowchart illustrating an example of the servo pattern writing method according to the second embodiment.

[0120] MPU60 writes a predetermined spiral servo pattern (normal spiral servo pattern) SSP (B1201) to disk 10, offset by a predetermined offset in the forward direction, and overlaps this spiral servo pattern (normal spiral servo pattern) SSP with other spiral servo patterns (normal spiral servo pattern) SSPs to write overlapping spiral servo pattern SSPs (B1202). MPU60 determines whether to overlap the spiral servo pattern (normal spiral servo pattern) SSPs to write (B1203). If it is determined that the spiral servo pattern (normal spiral servo pattern) SSPs to be overlapped to write (B1203: yes), MPU60 enters the process of B1202.

[0121] If it is determined that the spiral servo pattern (normal spiral servo pattern) SSP is not written in an overlapping manner (B1203: No), the MPU60 overwrites the erase pattern (B1901) at the center of the width of the overlapping spiral servo pattern SSP obtained by overlapping writing of multiple spiral servo pattern SSPs, and ends the process.

[0122] Figure 20 This is a flowchart illustrating an example of the servo pattern writing method according to the second embodiment.

[0123] MPU60 reads a spiral servo pattern, such as an overlapping write erase spiral pattern SSP (B2001), and acquires each demodulation MAG value whenever the synchronization marker of the read signal of the overlapping write erase spiral pattern SSP is detected (B2002). MPU60 calculates the maximum erase spiral demodulation MAG value among the demodulation MAG values ​​of the overlapping write erase spiral pattern SSP and the erase spiral difference value of each erase demodulation MAG value (B2003). MPU60 calculates the cumulative difference value obtained by accumulating the difference values ​​of each erase spiral (B2004), calculates the position corresponding to the timing of half of the cumulative difference value as the center position of the erase pattern (B2005), and ends the processing.

[0124] According to the second embodiment, the disk device 1 writes an overlapping write erase spiral pattern SSP by overwriting an erase pattern at the center of the width of the overlapping write spiral servo pattern SSP. The disk device 1 reads the overlapping write erase spiral pattern SSP and acquires each demodulation MAG value whenever the synchronization flag of the read signal of the overlapping write erase spiral pattern SSP is detected. The disk device 1 calculates the difference between the largest erase spiral demodulation MAG value and each erase spiral difference value among the demodulation MAG values ​​of the overlapping write erase spiral pattern SSP. The disk device 1 calculates the cumulative difference value obtained by accumulating the difference values ​​of each erase spiral and calculates the position corresponding to half of the cumulative difference value as the center position of the erase pattern. Even if the width of the spiral servo pattern is uneven due to insufficient overlapping write accuracy, the disk device 1 can overlap write multiple spiral servo patterns SSP without gaps to overwrite the erase pattern. Therefore, even if the width of the head 15 is narrow, the disk device 1 can reduce defects in the SSW process. Therefore, the disk device 1 can improve reliability.

[0125] Several embodiments have been described, but these embodiments are provided as examples and are 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 / or spirit of the invention, and are included within the scope of the invention described in the technical solution and its equivalents.

Claims

1. A disk drive, comprising: plate; The head writes data to the disk and reads data from the disk; and A controller controls the position of the head and writes an overlapping spiral servo pattern to the disk. The overlapping spiral servo pattern includes a first spiral servo pattern and a second spiral servo pattern. The second spiral servo pattern is a spiral servo pattern different from the first spiral servo pattern, which is written with the first spiral servo pattern offset from the first spiral servo pattern in the radial direction of the disk by a predetermined offset and overlaps with a portion of the radial direction of the first spiral servo pattern.

2. The disk drive according to claim 1, The controller performs positioning control based on a MAG value associated with a read signal that reads the overlapping helical servo pattern.

3. The disk drive according to claim 2, The controller calculates a position corresponding to half the timing of the accumulated value obtained by accumulating the MAG values ​​as the center position of the width of the overlapping helical servo pattern.

4. The disk drive according to claim 3, The controller calculates the position error based on the center position.

5. The disk drive according to claim 1, The controller writes an erase pattern to the center of the width of the overlapping spiral servo pattern.

6. The disk drive according to claim 5, The frequency of the erasure pattern is greater than the frequencies of the first spiral servo pattern and the second spiral servo pattern.

7. The disk drive according to claim 5 or 6, The controller writes the erasure pattern to the central portion only once.

8. The disk drive according to claim 5 or 6, The controller performs positioning control based on a MAG value associated with a read signal that reads an overlapping write-erase spiral pattern obtained by writing the erase pattern at the center of the width of the overlapping write spiral servo pattern.

9. The disk drive according to claim 8, The controller calculates the difference between the maximum value of the MAG value corresponding to the overlapping write-erase spiral pattern that does not contain the erase pattern and the MAG value corresponding to the overlapping write-erase spiral pattern that contains the erase pattern, and calculates a position corresponding to half of the accumulated value obtained by accumulating the difference value as the center position of the width of the overlapping write-erase spiral pattern.

10. The disk drive according to claim 9, The controller calculates the position error based on the center position.

11. A servo pattern writing method, applied to a disk device, the disk device having a disk and a head, the head writing data to the disk and reading data from the disk, the servo pattern writing method comprising: An overlapping helical servo pattern is written to the disk. The overlapping helical servo pattern includes a first helical servo pattern and a second helical servo pattern. The second helical servo pattern is a different helical servo pattern that is written with the first helical servo pattern offset from the first helical servo pattern by a predetermined offset in the radial direction of the disk and overlapped with a portion of the radial direction of the first helical servo pattern.

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