阅读说明：本技术 磁盘装置以及读处理方法 (Magnetic disk device and read processing method ) 是由 前东信宏 于 2019-07-15 设计创作，主要内容包括：实施方式提供一种能够提高读处理性能的磁盘装置以及读处理方法。本实施方式涉及的磁盘装置具备：盘；头,其具有对所述盘写入数据的写入头、和从所述盘读取数据的第1读取头及第2读取头；以及控制器,其在对所述盘的第1区域的第1磁道进行读取的情况下将所述第1读取头和所述第2读取头的中间部定位于所述第1磁道的第1磁道中央,在对与所述第1区域不同的所述盘的第2区域的第2磁道进行读取的情况下将所述第1读取头和所述第2读取头中的任一方定位于所述第2磁道的第2磁道中央。(Embodiments provide a magnetic disk device and a read processing method capable of improving read processing performance. The magnetic disk device according to the present embodiment includes: a disc; a head having a write head for writing data to the disk, and a 1 st read head and a 2 nd read head for reading data from the disk; and a controller that positions intermediate portions of the 1 st read head and the 2 nd read head at a 1 st track center of the 1 st track when reading a 1 st track of a 1 st region of the disk, and positions either the 1 st read head or the 2 nd read head at a 2 nd track center of the 2 nd track when reading a 2 nd track of a 2 nd region of the disk that is different from the 1 st region.)

1. A magnetic disk device is provided with:

a disc;

a head having a write head for writing data to the disk, and a 1 st read head and a 2 nd read head for reading data from the disk; and

and a controller that positions intermediate portions of the 1 st read head and the 2 nd read head at a 1 st track center of the 1 st track when reading a 1 st track of a 1 st region of the disk, and positions either the 1 st read head or the 2 nd read head at a 2 nd track center of the 2 nd track when reading a 2 nd track of a 2 nd region of the disk that is different from the 1 st region.

2. The magnetic disk apparatus according to claim 1,

the controller positions either the 1 st read head or the 2 nd read head at the 1 st track center in the 1 st region when retry reading is repeatedly performed with the intermediate portion positioned at the 1 st track center in the 1 st region.

3. The magnetic disk apparatus according to claim 2,

the controller positions one of the 1 st read head and the 2 nd read head at the 1 st track center in the 1 st region and then positions the other of the 1 st read head and the 2 nd read head at the 1 st track center, when the retry read is repeatedly performed with the intermediate portion positioned at the 1 st track center in the 1 st region.

4. The magnetic disk apparatus according to claim 1,

the controller positions one of the 1 st read head and the 2 nd read head at the 2 nd track center in the 2 nd area and repeatedly executes retry reading, and positions the other of the 1 st read head and the 2 nd read head at the 2 nd track center in the 2 nd area.

5. The magnetic disk apparatus according to claim 2,

the controller positions the intermediate portion at the center of the 3 rd track in the 1 st region having the 3 rd track having a radial width smaller than the radial width of the 1 st track, and when the retry read is repeatedly performed, positions the smaller one of the 1 st read head and the 2 nd read head at the center of the 3 rd track in the 1 st region.

6. The magnetic disk apparatus according to claim 1,

the controller positions a larger one of the 1 st read head and the 2 nd read head at a center of the 2 nd track in the 2 nd area having a 4 th track having a smaller radial width than a radial width of the 2 nd track.

7. The magnetic disk apparatus according to claim 1,

the controller positions a smaller one of the 1 st read head and the 2 nd read head at a 4 th track center of the 4 th track in the 2 nd area having a 4 th track having a smaller radial width than a radial width of the 2 nd track.

8. The magnetic disk device according to any of claims 1 to 7,

the head interval in the radial direction of the disk between the 1 st read head and the 2 nd read head in the 2 nd area is larger than the head interval in the 1 st area.

9. The magnetic disk apparatus according to claim 8,

the head interval is equal to or less than a threshold value in the 1 st region and is greater than the threshold value in the 2 nd region.

10. The magnetic disk device according to any of claims 1 to 7,

the bevel angle of the head of the 2 nd zone is greater than the bevel angle of the 1 st zone.

11. A read processing method applied to a magnetic disk apparatus having a disk and a head having a write head for writing data to the disk and a 1 st read head and a 2 nd read head for reading data from the disk, the read processing method comprising:

in the case of reading the 1 st track of the 1 st region of the disk, the intermediate portions of the 1 st read head and the 2 nd read head are positioned at the 1 st track center of the 1 st track,

when reading a 2 nd track of a 2 nd area of the disk different from the 1 st area, either the 1 st read head or the 2 nd read head is positioned at the 2 nd track center of the 2 nd track.

Technical Field

Embodiments of the present invention relate to a magnetic disk device and a read processing method.

Background

In recent years, magnetic disk devices of a Two-dimensional Recording (TDMR) system having a head including a plurality of read heads have been developed. In the TDMR magnetic disk device, the spacing (cross-track spacing: CTS) between the plurality of read heads in the direction crossing the tracks varies depending on the head skew angle. Therefore, in the magnetic disk device of the TDMR system, it is necessary to properly position the head in order to read data written on the disk.

Disclosure of Invention

Embodiments of the present invention provide a magnetic disk device and a read processing method capable of improving read processing performance.

The magnetic disk device according to the present embodiment includes: a disc; a head having a write head for writing data to the disk, and a 1 st read head and a 2 nd read head for reading data from the disk; and a controller that positions intermediate portions of the 1 st read head and the 2 nd read head at a 1 st track center of the 1 st track when reading a 1 st track of a 1 st region of the disk, and positions either the 1 st read head or the 2 nd read head at a 2 nd track center of the 2 nd track when reading a 2 nd track of a 2 nd region of the disk that is different from the 1 st region.

A read processing method according to the present embodiment is a read processing method applied to a magnetic disk device including a disk and a head having a write head for writing data to the disk, and a 1 st read head and a 2 nd read head for reading data from the disk, the read processing method including: when reading the 1 st track of the 1 st area of the disk, the middle parts of the 1 st read head and the 2 nd read head are positioned at the 1 st track center of the 1 st track, and when reading the 2 nd track of the 2 nd area of the disk different from the 1 st area, either the 1 st read head or the 2 nd read head is positioned at the 2 nd track center of the 2 nd track.

Drawings

Fig. 1 is a block diagram showing a configuration of a magnetic disk device according to embodiment 1.

Fig. 2 is a schematic diagram showing an example of the arrangement of the head with respect to the disk according to embodiment 1.

Fig. 3 is a schematic diagram showing an example of the geometrical arrangement of the write head and the two read heads in the case where the read head is positioned at the reference position.

Fig. 4 is a diagram showing an example of the geometrical arrangement of the write head and the two read heads in the case where the read head is positioned at a radial position.

Fig. 5 is a block diagram showing an example of the configuration of the R/W channel 50 and MPU60 according to embodiment 1.

Fig. 6 is a diagram showing an example of a relationship between the amount of offset (offset) in the radial direction of the read head with respect to the intermediate portion MP when the head is positioned at a target track located in a predetermined area of the disk in which the cross track interval is equal to or less than a predetermined value, and the error rate when the target track is read by positioning the head at the target track.

Fig. 7 is a diagram showing an example of the arrangement of the read head corresponding to fig. 6.

Fig. 8 is a diagram showing an example of a relationship between an offset amount in the radial direction of the read head with respect to the intermediate portion when the head is positioned at a target track located in a predetermined region of the disk where the cross track interval is larger than a predetermined value and an error rate when the target track is read by positioning the head at the target track.

Fig. 9 is a diagram showing an example of the arrangement of the read head corresponding to fig. 8.

Fig. 10 is a diagram showing an example of the arrangement of the reading head corresponding to fig. 8.

Fig. 11 is a diagram showing an example of the relationship between the cross-track pitch and the read/write offset according to embodiment 1.

Fig. 12 is a flowchart showing an example of the read processing according to embodiment 1.

Fig. 13 is a diagram showing an example of the arrangement of the reading head according to embodiment 2.

Detailed Description

Hereinafter, embodiments will be described with reference to the drawings. The drawings are exemplary and do not limit the scope of the invention.

(embodiment 1)

Fig. 1 is a block diagram showing a configuration of a magnetic disk device 1 according to embodiment 1.

The magnetic disk device 1 includes a Head Disk Assembly (HDA), a driver IC20, a head amplifier integrated circuit (hereinafter referred to as a head amplifier IC or a preamplifier) 30, a volatile memory 70, a buffer memory (buffer) 80, a nonvolatile memory 90, and a system controller 130 which is an integrated circuit of one chip, which will be described later. The magnetic disk device 1 is connected to a host system (host) 100. The Magnetic disk device 1 is, for example, a Two-Dimensional Magnetic Recording (TDMR) Magnetic disk device.

The HAD includes a magnetic disk (hereinafter referred to as a disk) 10, a spindle motor (SPM)12, an arm 13 on which a head 15 is mounted, and a Voice Coil Motor (VCM) 14. The disk 10 is attached to a spindle motor 12 and is rotated by driving the spindle motor 12. The arm 13 and the VCM14 constitute an actuator. The actuator controls the movement of the head 15 mounted on the arm 13 to a predetermined position of the disk 10 by driving the VCM 14. The number of the disks 10 and the heads 15 may be two or more. Hereinafter, data transferred from each unit of the magnetic disk device 1 or an external device, for example, the host 100 and written to the disk 10 may be referred to as write data, and data transferred to each unit of the magnetic disk device 1 or an external device, for example, the host 100 and read from the disk 10 may be referred to as read data.

The disc 10 is allocated to its recording area a user data area 10a that can be utilized by a user, and a system area 10b in which information necessary for system management is written. Hereinafter, the circumference of the disk 10, that is, the direction along a predetermined track of the disk 10 is referred to as the circumferential direction, and the direction intersecting the circumferential direction is referred to as the radial direction. Hereinafter, a position of the disk 10 in the predetermined circumferential direction is referred to as a circumferential position, and a position of the disk 10 in the predetermined radial direction is referred to as a radial position. Data written on a track of the disk 10, a predetermined radial position of the disk 10, a center position (hereinafter, referred to simply as a track center) of a width in a radial direction of a predetermined track of the disk 10 (hereinafter, referred to simply as a track width), a predetermined radial position within a track width of the predetermined track of the disk 10, and the like may be simply referred to as a track.

The head 15 is mainly composed of a slider, and includes a write head 15W and a read head 15R actually mounted on the slider. The write head 15W writes data to the disc 10. The read head 15R reads data recorded on the disc 10. The read head 15R has a plurality of read heads, for example, two read heads 15R1, 15R 2. The read head 15R1 is provided at, for example, the farthest position from the write head 15W. The read head 15R2 is provided closer to the write head 15W than the read head 15R1, for example. In other words, the read head 15R2 is located between the write head 15W and the read head 15R 1. The read head 15R may have three or more read heads. Hereinafter, the plurality of heads, for example, the two heads 15R1 and 15R2 may be collectively referred to as the head 15R, and the plurality of heads, for example, any one of the heads 15R1 and 15R2 may be simply referred to as the head 15R.

Fig. 2 is a schematic diagram showing an example of the arrangement of the head 15 with respect to the disk 10 according to the present embodiment. As shown in fig. 2, a direction toward the outer periphery of the disk 10 in the radial direction is referred to as an outward direction (outer side), and a direction opposite to the outward direction is referred to as an inward direction (inner side). As shown in fig. 2, the direction in which the disk 10 rotates in the circumferential direction is referred to as the rotation direction. In the example shown in fig. 2, the rotation direction is indicated in the clockwise direction, but may be reversed (counterclockwise direction). In fig. 2, the user data region 10a is divided into an inner peripheral region IR located in the inner direction, an outer peripheral region OR located in the outer direction, and an intermediate peripheral region MR located between the inner peripheral region IR and the outer peripheral region OR. In the example shown in fig. 2, the radial position IRP, the radial position RP0 and the radial position ORP are shown. The radial position IRP is located inward of the radial position RP0, and the radial position ORP is located outward of the radial position RP 0. In the example shown in fig. 2, the radial position RP0 is included in the middle peripheral region MR, the radial position ORP is included in the outer peripheral region OR, and the radial position IRP is included in the inner peripheral region IR. The radial position RP0 may be included in the outer peripheral region OR the inner peripheral region IR. The radial position IRP and the ORP may be included in the middle peripheral region MR. In fig. 2, the radial position IRP corresponds to the track center IIL of the predetermined track in the inner peripheral region IR, the radial position RP0 corresponds to the track center IL0 of the predetermined track in the middle peripheral region MR, and the radial position ORP corresponds to the track center OIL of the predetermined track in the outer peripheral region OR. The track center IIL corresponds to a track or a path (hereinafter, also referred to as a target track or a target path) that is a target of the head 15 in a predetermined track, for example, a predetermined track in the inner peripheral region IR. The track center IL0 corresponds to a target path of the head 15 in a predetermined track, for example, a predetermined track of the middle circumference region MR. The track center OIL corresponds to a target path of the head 15 in a predetermined track, for example, a predetermined track in the outer peripheral region OR. The track centers IIL, IL0, and OIL are located concentrically with respect to the disk 10. For example, the track center IIL, IL0, and OIL are located at perfect circles. The track centers IIL, IL0, and OIL may be located not in a circular shape but in a wavy position that varies in the radial direction of the disk 10.

The disk 10 has a plurality of servo patterns SV. Hereinafter, the servo pattern SV may be referred to as a servo sector or a servo field. The plurality of servo patterns SV extend radially in the radial direction of the disk 10 and are arranged discretely at predetermined intervals in the circumferential direction. The servo pattern SV contains servo data for positioning the head 15 at a predetermined radial position of the disk 10, and the like. Hereinafter, data other than servo data written in the user data area 10a other than the servo sector SV may be referred to as user data.

The Servo data includes, for example, Servo marks (Servo marks), address data, burst (burst) data, and the like. The address data is constituted by an address (cylinder address) of a predetermined track and an address of a servo sector of the predetermined track. The burst data is data (relative position data) used for detecting a position deviation (position error) of the head 15 in the radial direction with respect to the track center of a predetermined track, and is composed of a repetitive pattern (pattern) of a predetermined cycle. The burst data is written in an interleaved manner, for example, from a predetermined track to a track adjacent to the track in the radial direction.

In the case where the head 15 is located at the radius position RP0, the bevel angle is, for example, 0 °. Hereinafter, the radial position RP0 may be referred to as a reference position RP 0. In the case where the head 15 is located at the radial position ORP, the bevel angle is, for example, positive. The positive value of the bevel angle increases as the head 15 moves in the radial direction outward from the reference position RP 0. In the case of a head 15 at the radial position IRP, the bevel angle is, for example, negative. The negative value of the bevel decreases as the head 15 moves radially inward from the reference position RP 0. Further, in the case where the head 15 is located at the radial position ORP, the bevel angle may also be a negative value. In addition, the bevel angle may be a positive value when the head 15 is located at the radial position IRP.

Fig. 3 is a schematic diagram showing an example of the geometrical arrangement of the write head 15W and the two read heads 15R1 and 15R2 in the case where the read head 15R1 is positioned at the reference position RP 0. Hereinafter, the geometrical arrangement of the write head 15W and the two read heads 15R1 and 15R2 of the head 15 will be described with reference to the position of the read head 15R 1. Fig. 3 shows a center WC of the write head 15W, a center RC1 of the read head 15R1, a center RC2 of the read head 15R2, and an intermediate portion MP located between the center RC1 of the read head 15R1 and the center RC2 of the read head 15R 2. Hereinafter, the circumferential distance between the center portion RC1 of the read head 15R1 and the center portion RC2 of the read head 15R2 may be referred to as a Downstream Track Spacing (DTS). The radial distance between the center portion RC1 of the read head 15R1 and the center portion RC2 of the read head 15R2 may be referred to as a Cross Track Separation (CTS) or a head spacing. The radial distance between the read head 15R and the write head 15W, for example, the radial distance between the center portions RC1 and RC2 of the read heads 15R1 and 15R2 and the write head 15W, and the radial distance between the intermediate portion MP and the write head 15W may be referred to as read/write offset (offset). Hereinafter, for convenience of explanation, the "center portion of the write head" and the "respective portions of the write head" may be simply referred to as "write head", and the "center portion of the read head", the "intermediate portions of two read heads among the plurality of read heads", and the "respective portions of the read head" may be simply referred to as "read head".

In the example shown in fig. 3, when the read head 15R1 is disposed at the reference position RP0, the write head 15W, the read head 15R1, the read head 15R2, and the intermediate portion MP are arranged in the circumferential direction. In this case, the reader head 15R1 and the reader head 15R2 are not offset in the radial direction. That is, the cross track spacing CTS0 when the read head 15R1 is disposed at the reference position RP0 is 0. When the read head 15R1 is disposed at the reference position RP0, the read head 15R1 and the write head 15W, the read head 15R2 and the write head 15W, and the intermediate portion MP and the write head 15W are not offset in the radial direction. That is, the read/write bias OF10 OF the head 15R1 and the head 15W, the read/write bias OF20 OF the head 15R2 and the head 15W, the intermediate portion MP, and the head 15W in this case are 0, respectively. When the reading head 15R1 is disposed at the reference position RP0, the reading head 15R1 and the reading head 15R2 may be offset in the radial direction. In addition, when the read head 15R1 is disposed at the reference position RP0, the write head 15W and the read heads 15R1 and 15R2 may be offset in the radial direction.

In the example shown in fig. 3, when the read head 15R1 is disposed at the reference position RP0, the write head 15W and the read head 15R1 are separated by a gap GP0 in the circumferential direction. When the read head 15R1 is disposed at the reference position RP0, the read head 15R1 and the read head 15R2 are separated in the circumferential direction by the downstream track interval DTS 0.

Fig. 4 is a diagram showing an example of the geometrical arrangement of the write head 15W and the two read heads 15R1 and 15R2 in the case where the read head 15R1 is positioned at the radial position IRP.

In the example shown in fig. 4, when the read head 15R1 is disposed at the radial position IRP, the write head 15W, the read head 15R1, the read head 15R2, and the intermediate portion MP (head 15) are inclined inward at an oblique angle θ sw with respect to the circumferential direction. The absolute value of the oblique angle θ sw becomes larger as the head 15 is radially away from the reference position RP0 in the inward direction. In the case where the head 15 is inclined inward at an oblique angle θ sw with respect to the circumferential direction, the read head 15R1 and the read head 15R2 are separated in the radial direction at the cross-track interval CTSx. As the head 15 is radially distanced inward from the reference position RP0, the absolute value of the cross-track interval CTSx becomes larger. In other words, as the absolute value of the skew angle θ sw becomes larger, the absolute value of the cross-track interval CTSx also becomes larger. When the read head 15R1 is disposed at the radial position IRP, the read head 15R1 and the write head 15W are separated in the radial direction by the read/write bias OF1 x. As the head 15 is radially inwardly directed away from the reference position RP0, the absolute value OF the read/write bias OF1x becomes larger. In other words, as the absolute value OF the skew angle θ sw becomes larger, the absolute value OF the read/write bias OF1x also becomes larger. When the read head 15R1 is disposed at the radial position IRP, the read head 15R2 and the write head 15W are separated in the radial direction by the read/write bias OF2 x. As the head 15 is radially inwardly directed away from the reference position RP0, the absolute value OF the read/write bias OF2x becomes larger. In other words, as the absolute value OF the skew angle θ sw becomes larger, the absolute value OF the read/write bias OF2x also becomes larger. When the read head 15R1 is disposed at the radial position IRP, the intermediate portion MP and the write head 15W are separated in the radial direction by the read/write bias OFMx. As the head 15 is radially away from the reference position RP0 in the inward direction, the absolute value of the read/write bias OFMx becomes larger. In other words, as the absolute value of the skew angle θ sw becomes larger, the absolute value of the read/write bias OFMx also becomes larger.

In the example shown in fig. 4, when the read head 15R1 is disposed at the radial position IRP, the read head 15R1 and the read head 15R2 are separated from each other in the circumferential direction by the downstream track interval DTSx. As the head 15 is radially distanced inward from the reference position RP0, the down-track interval DTSx becomes smaller. In other words, as the absolute value of the skew angle θ sw becomes larger, the down track interval DTSx also becomes smaller.

In addition, even when the read head 15R1 is disposed at the radial position ORP, the write head 15W, the read heads 15R1 and 15R2, and the intermediate portion MP are inclined outward at a predetermined inclination angle, as in the case where the read head 15R1 is positioned at the radial position IRP. When the read head 15R1 is disposed at the radial position ORP, the read head 15R1 and the read head 15R2 may be separated by a predetermined down track interval DTSx in the circumferential direction. The absolute value of the oblique angle θ sw becomes larger as the head 15 is radially away from the reference position RP0 in the outward direction. In the case where the head 15 is inclined in the outward direction at the oblique angle θ sw with respect to the circumferential direction, the read head 15R1 and the read head 15R2 may be separated in the outward direction at a predetermined cross-track interval CTSx. As the head 15 is radially away from the reference position RP0 in the outward direction, the absolute value of the cross-track interval CTSx becomes larger.

The driver IC20 controls the driving of the SPM12 and the VCM14 under the control of the system controller 130 (specifically, an MPU60 described later).

The head amplifier IC (preamplifier) 30 includes a read amplifier and a write driver. The read amplifier amplifies a read signal read from the disk 10 and outputs the amplified signal to the system controller 130 (specifically, a read/write (R/W) channel 50 described later). The write driver outputs a write current corresponding to write data output from the R/W channel 50 to the head 15.

The volatile memory 70 is a semiconductor memory in which data held when power supply is turned off is lost. The volatile memory 70 stores data and the like necessary for processing of each unit of the magnetic disk device 1. The volatile memory 70 is, for example, a dram (Dynamic Random Access memory) or an sdram (synchronous Dynamic Random Access memory).

The buffer memory 80 is a semiconductor memory that temporarily records data and the like transmitted and received between the magnetic disk device 1 and the host 100. The buffer memory 80 may be integrated with the volatile memory 70. The buffer Memory 80 is, for example, a DRAM (dynamic Random Access Memory), an SDRAM (synchronous dynamic Random Access Memory), a FeRAM (Ferroelectric Random Access Memory), an mram (magnetic Random Access Memory), or the like.

The nonvolatile memory 90 is a semiconductor memory that records stored data even when power supply is turned off. The nonvolatile Memory 90 is, for example, a Flash ROM (Flash Read Only Memory) of NOR type or NAND type.

The System controller (controller) 130 is implemented, for example, using a large scale integrated circuit (LSI) called a System-on-a-chip (soc) in which a plurality of elements are integrated on a single chip. The system controller 130 includes a Hard Disk Controller (HDC)40, a read/write (R/W) channel 50, and a Microprocessor (MPU) 60. The HDC40, the R/W channel 50, and the MPU60 are electrically connected to each other, respectively. The system controller 130 is electrically connected to, for example, a driver IC20, a head amplifier IC60, the volatile memory 70, the buffer memory 80, the nonvolatile memory 90, and the host system 100.

The HDC40 controls data transfer between the host 100 and the R/W channel 50 in accordance with an instruction from the MPU60 described later. The HDC40 is electrically connected to, for example, the volatile memory 70, the buffer memory 80, and the nonvolatile memory 90.

The R/W channel 50 controls signal processing of read data and write data in accordance with an instruction from the MPU 60. The R/W channel 50 has a circuit or function for measuring the signal quality of read data. The R/W channel 50 is electrically connected to, for example, a head amplifier IC30, etc.

The MPU60 is a main controller that controls each unit of the magnetic disk apparatus 1. The MPU60 controls the VCM14 via the driver IC20, and performs positioning of the head 15. The MPU60 controls the write operation for writing data to the disk 10, and selects a storage destination of the write data transferred from the host 100. Further, the MPU60 controls the read operation of reading data from the disk 10, and controls the processing of reading data transferred from the disk 10 to the host 100. The MPU60 is connected to each unit of the magnetic disk device 1. The MPU60 is electrically connected to, for example, the driver IC20, the HDC40, and the R/W channel 50. The term "positioning the head 15" includes "positioning (disposing) the read heads 15R1, 15R2 and the intermediate portion MP (the read head 15R) at a predetermined position on the disk 10" and "positioning (disposing) the write head 15W at a predetermined position on the disk 10".

Fig. 5 is a block diagram showing an example of the configuration of the R/W channel 50 and MPU60 according to the present embodiment. In fig. 5, the disc 10 and the like are omitted.

The R/W channel 50 includes a 1 st demodulation unit 510 and a 2 nd demodulation unit 520. For example, the 1 st demodulation unit 510 demodulates data read by the read head 15R1, for example, a servo signal, and outputs the demodulated servo data to the MPU60 or the like. Like the 1 st demodulation unit 510, the 2 nd demodulation unit 520 demodulates the servo signal read by the read head 15R2, and outputs the demodulated servo data to the MPU60 or the like. In addition, when three or more reading heads are provided, the R/W channel 50 may include three or more demodulation units corresponding to the respective reading heads.

The MPU60 includes a read/write control unit 610. The MPU60 executes processing of each unit, for example, the read/write control unit 610, on firmware. The MPU60 may also include each part as a circuit.

The read/write control unit 610 controls the read processing and write processing of data in accordance with a command from the host 100. The read/write control unit 610 controls the VCM14 via the driver IC20 to position the head 15 at a predetermined radial position on the disk 10, and executes read processing or write processing.

The read/write control section 610 performs read processing by a plurality of read heads, for example, at least one of the read heads 15R1 and 15R2 (read head 15R). For example, the read/write control unit 610 positions the read head 15R1 at the track center of a predetermined track, and reads the track by the read heads 15R1 and 15R 2. The read/write control unit 610 positions the read head 15R2 at the center of a predetermined track, and reads the track by the read heads 15R1 and 15R 2. The read/write control unit 610 positions the intermediate portion MP at the center of the track of the predetermined track, and reads the track by the read heads 15R1 and 15R 2. Hereinafter, the "positioning the read head 15R1 at (the track center of) a predetermined track and reading the track by the read heads 15R1 and 15R 2" and the "positioning the read head 15R1 at (the track center of) a predetermined track" may be referred to as "positioning the read head 15R1 at a predetermined track". The phrase "positioning the read head 15R2 at (the track center of) a predetermined track, reading the track by the read heads 15R1 and 15R 2" and "disposing the read head 15R2 at (the track center of) a predetermined track" may be also referred to as "positioning the read head 15R2 at a predetermined track". In addition, "the intermediate portion MP is positioned at (the track center of) a predetermined track, the track is read by the read heads 15R1 and 15R2," and "the intermediate portion MP is disposed at (the track center of) the predetermined track" may be referred to as "the intermediate portion MP is positioned at the predetermined track".

The read/write control unit 610 positions the read head having the smallest error rate (bit error rate) in the read head 15R to the target track based on the cross track interval when the head 15, for example, the intermediate portion MP is positioned at the target radial position (hereinafter referred to as target position) indicated by a command or the like from the host 100, or the target track (hereinafter referred to as target track) indicated by a command or the like from the host 100, for example. The read/write control unit 610 positions the read head (hereinafter, also referred to as an initial read head) having the smallest error rate among the read heads 15R to the target track based on the skew angle when the head 15 is positioned to the target track, the radial position of the target track, or a predetermined region of the disk 10 including the target track, for example, a zone (zone). The sector corresponds to, for example, one of a plurality of areas obtained by dividing the user data area 10a of the disc 10 in the radial direction. In addition, the segment includes at least one track. When it is determined that the target track cannot be read in a state where a predetermined read head, for example, an initial read head, of the read heads 15R is positioned on the target track by High Fly Write (High Fly Write), the read/Write control unit 610 positions at least one predetermined read head (hereinafter, also referred to as a changed read head) of the read heads 15R different from the initial read head on the target track. For example, the read/write control unit 610 positions at least one changed read head on the target track when a retry read (read) is performed at least 1 time (or a plurality of times) in a state where the initial read head is positioned on the target track, or when a retry read is repeatedly performed in a state where the initial read head is positioned on the target track. The error rate in the case where the predetermined track is read with the initial read head positioned on the predetermined track and the error rate in the case where the predetermined track is read with the changed read head positioned on the predetermined track may be the same or different. In other words, the change head may or may not include the head having the smallest error rate among the heads 15R. For example, when a plurality of different change heads are positioned on the target track, the read/write control unit 610 outputs, to each unit, for example, each unit of the magnetic disk device 1 and the host 100, read data having the smallest error rate among a plurality of read data obtained by positioning the plurality of change heads on the target track. When the error rates of the plurality of read data obtained by positioning the plurality of changing read heads on the target track are the same, the read/write control unit 610 may select at least one read data from the plurality of read data and output the selected data to each unit, for example, each unit of the magnetic disk device 1 and the host 100.

When it is determined that the cross-track pitch at which the intermediate portion MP is positioned on the target track is equal to or less than a predetermined value, for example, the track width (or track pitch) of the target track, the read/write control portion 610 positions the intermediate portion MP on the target track. When determining that the target track cannot be read in the state where the intermediate portion MP is positioned on the target track, the read/write control unit 610 positions the read head 15R1 (or the read head 15R2) on the target track, positions the read head 15R1 (or the read head 15R2) on the target track, and then positions the read head 15R2 (or the read head 15R1) on the target track. For example, the read/write control unit 610 outputs the read data having a small error rate out of the read data obtained by positioning the read head 15R1 on the target track and the read data obtained by positioning the read head 15R2 on the target track.

When determining that the cross-track pitch when the intermediate portion MP is positioned on the target track is larger than a predetermined value, for example, the track width (or track pitch) of the target track, the read/write control unit 610 positions the read head 15R1 (or the read head 15R2) on the target track. When the read/write control unit 610 determines that reading cannot be performed in a state where the read head 15R1 (or the read head 15R2) is positioned on the target track, it positions the read head 15R2 (or the read head 15R1) on the target track. The read/write control unit 610 may position the intermediate portion MP on the target track when it is determined that the cross-track pitch when positioning the intermediate portion MP on the target track is larger than a predetermined value, for example, the track width (or track pitch) of the target track.

When determining that the skew angle at which the intermediate portion MP is positioned on the target track is a skew angle equal to or smaller than a predetermined value, for example, the track width (or track pitch) of the target track, the read/write control portion 610 determines that the cross-track pitch is equal to or smaller than the track width of the target track, and positions the intermediate portion MP on the target track. When determining that reading is not possible in the state where the intermediate portion MP is positioned on the target track, the read/write control unit 610 positions the read head 15R1 (or the read head 15R2) on the target track, positions the read head 15R1 (or the read head 15R2) on the target track, and then positions the read head 15R2 (or the read head 15R1) on the target track. For example, the read/write control unit 610 outputs the read data having a small error rate out of the read data obtained by positioning the read head 15R1 on the target track and the read data obtained by positioning the read head 15R2 on the target track.

When determining that the skew angle at which the intermediate portion MP is positioned on the target track is a skew angle at which the cross-track interval is greater than a predetermined value, for example, the track width (or track pitch) of the target track, the read/write control portion 610 determines that the cross-track interval is greater than the track width of the target track, and positions the read head 15R1 (or the read head 15R2) on the target track. When determining that reading cannot be performed in a state where the read head 15R1 (or the read head 15R2) is positioned on the target track, the read/write control unit 610 positions the read head 15R2 (or the read head 15R1) on the target track. When determining that the skew angle at which the intermediate portion MP is positioned on the target track is a skew angle of a cross-track interval larger than a predetermined value, for example, the track width of the target track, the read/write control portion 610 determines that the cross-track interval is larger than the track width of the target track, and positions the intermediate portion MP on the target track.

When it is determined that the radial position of the target track is a radial position of the cross track interval that is equal to or less than a predetermined value, for example, the track width (or track pitch) of the target track when the intermediate portion MP is positioned, the read/write control portion 610 determines that the cross track interval is equal to or less than the track width of the target track, and positions the intermediate portion MP on the target track. When determining that the target track cannot be read in the state where the intermediate portion MP is positioned on the target track, the read/write control unit 610 positions the read head 15R1 (or the read head 15R2) on the target track, positions the read head 15R1 (or the read head 15R2) on the target track, and then positions the read head 15R2 (or the read head 15R1) on the target track. For example, the read/write control unit 610 outputs the read data having a small error rate out of the read data obtained by positioning the read head 15R1 on the target track and the read data obtained by positioning the read head 15R2 on the target track.

When determining that the radial position of the target track is a radial position of the cross track interval larger than a predetermined value, for example, the track width (or track pitch) of the target track when the intermediate portion MP is positioned, the read/write control unit 610 determines that the cross track interval is larger than the track width of the target track, and positions the read head 15R1 (or the read head 15R2) on the target track. When determining that the target track cannot be read by the read head 15R1 (or the read head 15R2), the read/write control unit 610 positions the read head 15R2 (or the read head 15R1) on the target track. When it is determined that the radial position of the target track is a radial position at which the cross-track pitch is larger than a predetermined value, for example, the track width of the target track when the intermediate portion MP is positioned, the read/write control portion 610 determines that the cross-track pitch is larger than the track width of the target track, and positions the intermediate portion MP on the target track.

When it is determined that the zone including the target track is a zone having a cross-track pitch equal to or smaller than a predetermined value, for example, the track width (or track pitch) of the target track, the read/write control unit 610 determines that the cross-track pitch is equal to or smaller than the track width of the target track, and positions the intermediate portion MP on the target track. When determining that the target track cannot be read in the state where the intermediate portion MP is positioned on the target track, the read/write control unit 610 positions the read head 15R1 (or the read head 15R2) on the target track, positions the read head 15R1 (or the read head 15R2) on the target track, and then positions the read head 15R2 (or the read head 15R1) on the target track. For example, the read/write control unit 610 outputs the read data having a small error rate out of the read data obtained by positioning the read head 15R1 on the target track and the read data obtained by positioning the read head 15R2 on the target track.

When it is determined that the zone including the target track is a zone having a cross track pitch larger than a predetermined value, for example, the track width (or track pitch) of the target track, the read/write control unit 610 determines that the cross track pitch is larger than the track width of the target track, and positions the read head 15R1 (or the read head 15R2) on the target track. When the read/write control unit 610 determines that the target track cannot be read in a state where the read head 15R1 (or the read head 15R2) is positioned on the target track, it positions the read head 15R2 (or the read head 15R1) on the target track. When it is determined that the zone including the target track is a zone having a cross track pitch larger than a predetermined value, for example, the track width of the target track, the read/write control unit 610 determines that the cross track pitch is larger than the track width of the target track, and positions the intermediate portion MP on the target track.

The read/write control unit 610 measures, for example, the cross track pitch and skew angle when the head 15 is positioned at each radial position of the disk 10 in the manufacturing process, and the error rate when data is read by the read head 15R at each radial position of the disk 10. The read/write control unit 610 sets the read head 15R (first read head) having the smallest error rate corresponding to the measured cross track pitch and skew angle. The read/write control unit 610 records the measured cross track pitch and skew angle, the zone corresponding to the measured cross track pitch and skew angle, and the read head 15R (first read head) in which the error rate corresponding to the set cross track pitch and skew angle is the minimum in a memory, for example, the nonvolatile memory 90, the buffer memory 80, the volatile memory 70, or the disk 10.

Fig. 6 is a diagram showing an example of the relationship between the amount of offset in the radial direction of the read head 15R with respect to the intermediate portion MP when the head 15 is positioned at a target track located in a predetermined region of the disk 10 where the cross-track spacing is equal to or less than a predetermined value and the error rate when the target track is read with the head 15 positioned at the target track.

Fig. 6 shows a relationship between an offset amount in the radial direction of the read head 15R (hereinafter, also simply referred to as an offset amount) with respect to the intermediate portion MP in the case where the head 15 is positioned on a target track located in a predetermined region (hereinafter, also referred to as a narrow region) obtained by dividing the user data region 10a of the disk 10 in which the cross track interval is a predetermined value, for example, the track width (or track pitch) or less, for example, an intermediate peripheral region (hereinafter, also referred to as an intermediate peripheral region) MR including the reference position RP0, and an error rate in the case where the head 15 is positioned on the target track. The narrow region may be a region in which the cross-track pitch is 0.7 to 1.3 times the track width (or track pitch), for example. The narrow region may be a region in which the cross-track pitch is smaller than 0.7 times the track width (or track pitch), or may be a region in which the cross-track pitch is larger than 1.3 times the track width (or track pitch), for example. The narrow region is a region where (the absolute value of) the tilt angle of the head 15 is equal to or smaller than a predetermined angle (hereinafter, also referred to as an angle threshold value). The inner peripheral region IR OR the outer peripheral region OR may be a narrow region.

In fig. 6, the horizontal axis represents the offset of the read head 15R with respect to the intermediate portion MP when the head 15 is positioned on the target track located in the middle circumferential region MR, and the vertical axis represents the error rate when the head 15 is positioned on the target track located in the middle circumferential region MR. On the abscissa of fig. 6, the offset increases in the direction of a positive value as it goes from the offset equal to 0 (the intermediate portion MP) to the positive arrow direction, and decreases in the direction of a negative value as it goes from the offset equal to 0 to the negative arrow direction. For example, a direction of a positive value of the offset corresponds to an outer direction in the radial direction, and a direction of a negative value of the offset corresponds to an inner direction in the radial direction. In addition, a direction of a positive value of the offset amount may correspond to an inner direction in the radial direction, and a direction of a negative value of the offset amount may correspond to an outer direction in the radial direction. On the vertical axis of fig. 6, the error rate increases as one moves in the direction of the large arrow, and decreases as one moves in the direction of the small arrow.

Fig. 6 shows a change R1E1 of the error rate with respect to the offset when the head 15, for example, the intermediate portion MP is positioned on the target track located in the intermediate circumferential region MR and the read is performed only by the read head 15R1, a change R2E1 of the error rate with respect to the offset when the head 15, for example, the intermediate portion MP is positioned on the target track located in the intermediate circumferential region MR and the read is performed only by the read head 15R2, and MPE1 of the error rate with respect to the offset when the head 15, for example, the intermediate portion MP is positioned on the target track located in the intermediate circumferential region MR and the read is performed by the two read heads 15R1 and 15R 2. The error rate change MPE1 corresponds to, for example, a change in the error rate obtained by combining the error rate changes R1E1 and R2E1, or a change in the error rate obtained by averaging the error rate changes R1E1 and R2E 1.

In the example shown in fig. 6, the error rate change R1E1 changes in a parabolic (2-degree curve) shape having a vertex R1V 1. The change in error rate R1E1 is minimal at the apex R1V 1. The vertex R1V1 corresponds to an offset in a direction more positive than 0. In other words, the apex R1V1 corresponds to the offset amount with respect to the center portion RC1 of the readhead 15R1 at which the offset amount is 0. The change in error rate R2E1 changes in a parabolic shape with a vertex R2V 1. In the example shown in fig. 6, the change in error rate R2E1 overlaps with the change in error rate R1E1 at an offset of 0. The change in error rate R2E1 is minimal at the apex R2V 1. The vertex R2V1 corresponds to an offset in a direction that is more negative than 0. In other words, the apex R1V1 corresponds to the offset amount with respect to the center portion RC2 of the readhead 15R2 at which the offset amount is 0. In the example shown in FIG. 6, the vertices R2V1 are the same as the vertices R1V 1. The vertex R2V1 may be different from the vertex R1V 1. The change in error rate MPE1 changes in a parabolic shape with a vertex MPV 1. The change in error rate MPE1 is at a minimum at the vertex MPV 1. The vertex MPV1 corresponds to an offset amount of 0 (middle portion MP). The vertex MPV1 is smaller than the vertices R1V1 and R2V 1. The vertex MPV1 may be the same as at least one of the vertices R1V1 and R2V 1. The cross-track spacing CTS1 between vertices R1V1 and R2V1 is shown in FIG. 6. The cross track spacing CTS1 is equal to or less than the track width (or track pitch) of a predetermined track located in a narrow area.

In the example shown in fig. 6, the read/write control unit 610 positions the intermediate portion MP on the target track so that the error rate becomes minimum based on the cross track interval CTS 1. For example, when reading a target track located in an intermediate peripheral region where the cross track interval is equal to or less than the track width (or track pitch), the read/write control unit 610 determines that the cross track interval CTS1 is equal to or less than the track width of the target track, and positions the intermediate portion MP on the target track so as to minimize the error rate.

Fig. 7 is a diagram showing an example of the arrangement of the read head 15R corresponding to fig. 6. Fig. 7 shows only the components necessary for explanation. Fig. 7 shows the target track MTRj of the sector ZNj located inward of the reference position RP0 in the middle circumference region MR. In the example shown in fig. 7, the pickup head 15R1, the pickup head 15R2, and the intermediate portion MP are inclined inward at an oblique angle θ sw1 with respect to the circumferential direction. The read heads 15R1 and 15R2 are separated from each other by a cross-track spacing CTS 1. The cross-track spacing CTS1 is smaller than the track width TW1 of the target track MTRj. The intermediate portion MP is located at the track center mtcjof the target track MTRj. The read heads 15R1 and 15R2 overlap the target track MTRj. For example, the width R1W1 of the readhead 15R1 is the same as the width R2W1 of the readhead 15R 2. Further, the width R1W1 of the head 15R1 and the width R2W1 of the head 15R2 may be different.

In the example shown in fig. 7, when reading the target track MTRj located in the middle circumference area MR in which the cross track interval is smaller than the track width, the read/write control unit 610 determines that the cross track interval CTS1 is equal to or smaller than the track width TW1 of the target track MTRj, and positions the intermediate portion MP at the track center MTRj of the target track MTRj. When determining that the target track MTRj cannot be read while the intermediate portion MP is positioned on the target track MTRj, the read/write control unit 610 positions the read head 15R1 (or the read head 15R2) at the track center MTRj of the target track MTRj. The read/write control unit 610 positions the read head 15R1 (or the read head 15R2) on the target track MTRj, and then positions the read head 15R2 (or the read head 15R1) on the track center MTRj of the target track MTRj.

Fig. 8 is a diagram showing an example of the relationship between the amount of offset in the radial direction of the read head 15R with respect to the intermediate portion MP when the head 15 is positioned at a target track located in a predetermined region of the disk 10 where the cross track interval is larger than a predetermined value, and the error rate when the head 15 is positioned at the target track.

Fig. 8 shows an example of the relationship between the offset of the read head 15R with respect to the intermediate portion MP when the head 15 is positioned on the target track in the region (hereinafter, also referred to as a wide region) of the disk 10 where the cross track pitch is larger than a predetermined value, for example, the track width (or track pitch), for example, the inner peripheral region IR inward of the intermediate peripheral region MR, and the error rate when the head 15 is positioned on the target track. The wide area is, for example, an area where the cross track pitch is larger than the narrow area when the head 15 is positioned. In other words, the wide area is an area other than the narrow area of the user data area 10 a. The outer peripheral region OR in the outer direction from the middle peripheral region MR may be a wide region. Therefore, the same explanation as the relation between the offset amount of the read head 15R with respect to the intermediate portion MP when the head 15 is positioned on the target track located in the outer peripheral region OR outward of the middle peripheral region MR and the error rate when the head 15 is positioned on the target track can be applied to the relation between the offset amount and the error rate shown in fig. 8. The wide area may be, for example, an area in which the cross-track pitch is larger than 0.7 times the track width (or track pitch). The wide area may be an area in which the cross-track pitch is 0.7 times or less the track width (or track pitch), for example. The wide area is an area where (the absolute value of) the tilt angle of the head 15 is larger than the angle threshold. In other words, the wide area is an area where (the absolute value of) the tilt angle of the head 15 is larger than that of the narrow area. In addition, the middle region MR may be a wide region.

In fig. 8, the horizontal axis represents the offset of the read head 15R with respect to the intermediate portion MP when the head 15 is positioned on the target track located in the inner peripheral region IR, and the vertical axis represents the error rate when the head 15 is positioned on the target track located in the inner peripheral region IR. On the abscissa of fig. 8, the offset increases in the direction of a positive value as it goes from the offset equal to 0 (the intermediate portion MP) to the positive arrow direction, and decreases in the direction of a negative value as it goes from the offset equal to 0 to the negative arrow direction. On the vertical axis of fig. 8, the error rate increases as one moves in the direction of the large arrow, and decreases as one moves in the direction of the small arrow.

Fig. 8 shows the change R1E2 of the error rate with respect to the offset amount when reading is performed only by the read head 15R1 in a state where the head 15, for example, the intermediate portion MP is positioned at the target track located in the inner peripheral region IR, the change R2E2 of the error rate with respect to the offset amount when reading is performed only by the read head 15R2 in a state where the head 15, for example, the intermediate portion MP is positioned at the target track located in the inner peripheral region IR, and the MPE2 of the error rate with respect to the offset amount when reading is performed by two read heads 15R1 and 15R2 in a state where the head 15, for example, the intermediate portion MP is positioned at the target track located in the inner peripheral region IR. The error rate change MPE2 corresponds to, for example, a change in the error rate obtained by combining the error rate changes R1E2 and R2E2, or a change in the error rate obtained by averaging the error rate changes R1E2 and R2E 2.

In the example shown in fig. 8, the error rate change R1E2 changes in a parabolic (2-degree curve) shape having a vertex R1V 2. The change in error rate R1E2 is minimal at the apex R1V 2. The vertex R1V2 corresponds to an offset in a direction more positive than 0. In other words, the apex R1V2 corresponds to the offset amount with respect to the center portion RC1 of the readhead 15R1 at which the offset amount is 0. The change in error rate R2E2 changes in a parabolic shape with a vertex R2V 2. In the example shown in fig. 8, the error rate change R2E2 is separated from the error rate change R1E2, and does not overlap with the error rate change R1E2 at the offset amount of 0. The change in error rate R2E2 is minimal at the apex R2V 2. The vertex R2V2 corresponds to an offset in a direction that is more negative than 0. In other words, the apex R1V1 corresponds to the offset amount with respect to the center portion RC2 of the readhead 15R2 at which the offset amount is 0. In the example shown in FIG. 8, the vertices R2V2 are the same as the vertices R1V 2. The vertex R2V2 may be different from the vertex R1V 2. The change in error rate MPE2 changes in a 4-th order curve with a maximum MPV2, a minimum MPV3, and an MPV 4. The change in error rate MPE2 is minimal at minimum values MPV3 and MPV 4. The maximum MPV2 is larger than the minimum MPV3 and MPV 4. The maximum value MPV2 corresponds to the offset amount of 0 (intermediate portion MP). The minimum value MPV3 corresponds to the offset amount from the center portion RC1 (the apex R1V2) of the readhead 15R1 at which the middle portion MP is 0. The minimum value MPV4 corresponds to the offset amount from the center portion RC2 (the apex R2V2) of the readhead 15R2 at which the middle portion MP is 0. The maximum MPV2 is larger than the minimum MPV3 and MPV 4. Minimum MPV3 is the same as minimum MPV 4. Minimum MPV3 and minimum MPV4 may be different. The minimum value MPV3 may be the same as or different from the vertex R1V 2. The minimum MPV4 may be the same as or different from the vertex R2V 2. The cross-track spacing CTS2 between the vertex R1V2 (minimum MPV3) and the vertex R2V2 (minimum MPV4) is shown in FIG. 8. The cross-track spacing CTS2 is larger than the track width (or track pitch) of a predetermined track located over a wide area. The cross-track spacing CTS2 is greater than the cross-track spacing CTS1 shown in fig. 6.

In the example shown in fig. 8, the read/write control unit 610 positions the intermediate portion MP on the target track so that the error rate becomes minimum based on the cross track interval CTS 2. For example, when reading a target track located in the inner peripheral region IR having a cross track spacing larger than the track width (or track pitch), the read/write control unit 610 determines that the cross track spacing CTS2 is larger than the track width of the target track, and positions the intermediate portion MP on the target track so as to minimize the error rate.

When reading a target track located in the outer peripheral region OR where the cross track pitch is larger than the track width (OR track pitch), the read/write control unit 610 determines that the cross track pitch is larger than the track width of the target track, and positions the read head 15R1 OR 15R2 on the target track so as to minimize the error rate.

In addition, when reading the target tracks located in the inner peripheral region IR and the outer peripheral region OR, in which the cross track pitch is larger than the track width (OR the track pitch), the read/write control unit 610 may determine that the cross track pitch is larger than the track width of the target track and position the intermediate portion MP on the target track.

Fig. 9 is a diagram showing an example of the arrangement of the read head 15R corresponding to fig. 8. Fig. 9 shows only the components necessary for explanation. Fig. 9 shows the target track ITRk of the block ZNk located in the inner peripheral region IR inward of the middle peripheral region MR including the reference position RP 0. In the example shown in fig. 9, the pickup head 15R1, the pickup head 15R2, and the intermediate portion MP are inclined inward at an oblique angle θ sw2 with respect to the circumferential direction. The read heads 15R1 and 15R2 are separated from each other by a cross-track spacing CTS 2. The cross-track spacing CTS2 is larger than the track width (or track pitch) TW2 of the target track ITRk. The track width TW2 is the same as the track width TW1, for example. The track width TW2 may be different from the track width TW 1. The read head 15R1 is located at the track center ITCk of the target track ITRk. In the example shown in FIG. 9, the read head 15R1 overlaps the target track ITRk. The read head 15R2 does not overlap the target track ITRk.

In the example shown in fig. 9, when reading a target track located in the inner peripheral region IR where the cross track pitch is larger than the track width (or track pitch), the read/write control unit 610 determines that the cross track pitch CTS2 is larger than the track width TW2 of the target track ITRk, and positions the read head 15R1 at the track center ITCk of the target track ITRk. When the read/write control unit 610 determines that the target track ITRk cannot be read by the read head 15R1, it positions the read head 15R2 at the track center ITCk of the target track ITRk.

When reading a target track located in the outer peripheral region OR where the cross track pitch is larger than the track width (OR track pitch), the read/write control unit 610 determines that the cross track pitch is larger than the track width of the target track, and positions the read head 15R1 on the target track. When the read/write control unit 610 determines that reading is not possible in the state where the read head 15R1 is positioned on the target track, it positions the read head 15R2 on the target track.

Fig. 10 is a diagram showing an example of the arrangement of the read head 15R corresponding to fig. 8. Fig. 10 shows only the components necessary for explanation. Fig. 10 shows the target track ITRk of the block ZNk located in the inner peripheral region IR inward of the middle peripheral region MR including the reference position RP 0. The read head 15R2 is located at the track center ITCk of the target track ITRk. In the example shown in FIG. 10, the read head 15R2 overlaps the target track ITRk. The read head 15R1 does not overlap the target track ITRk.

In the example shown in fig. 10, when reading a target track located in the inner peripheral region IR where the cross track pitch is larger than the track width (or track pitch), the read/write control unit 610 determines that the cross track pitch CTS2 is larger than the track width TW2 of the target track ITRk, and positions the read head 15R2 at the track center ITCk of the target track ITRk. When the read/write control unit 610 determines that the target track ITRk cannot be read with the read head 15R2 positioned over the target track ITRk, it positions the read head 15R1 over the track center ITCk of the target track ITRk as shown in fig. 9.

When reading a target track located in the outer peripheral region OR where the cross track pitch is larger than the track width (OR track pitch), the read/write control unit 610 determines that the cross track pitch is larger than the track width of the target track, and positions the read head 15R2 on the target track. When the read/write control unit 610 determines that the target track cannot be read by the read head 15R2, it positions the read head 15R1 on the target track.

In the example shown in fig. 9 and 10, when reading the target tracks located in the inner peripheral region IR and the outer peripheral region OR, in which the cross track pitch is larger than the track width (OR the track pitch), the read/write control section 610 may determine that the cross track pitch is larger than the track width of the target tracks and position the intermediate section MP at the track center of the target tracks.

Fig. 11 is a diagram showing an example of the relationship between the cross-track pitch and the read/write offset according to the present embodiment.

In fig. 11, the horizontal axis represents the cross-track spacing at a predetermined radial position of the disk 10, and the vertical axis represents the read/write offset at a predetermined radial position of the disk 10. On the abscissa of fig. 11, the cross-track pitch increases in the direction of a positive value as it goes from the cross-track pitch of 0 to the positive arrow direction, and decreases in the direction of a negative value as it goes from the cross-track pitch of 0 to the negative arrow direction. Fig. 11 shows the cross track interval Th1 when the head 15 is positioned at a radial position corresponding to the boundary between a narrow region, for example, a wide region in the inner direction including the reference position RP0, the middle peripheral region MR, and the narrow region, for example, the inner peripheral region IR, and the cross track interval Th2 when the head 15 is positioned at a radial position corresponding to the boundary between a wide region in the outer direction of the narrow region and the narrow region, for example, the outer peripheral region OR. The absolute value of the cross-track interval Th1 is, for example, the same as the absolute value of the cross-track interval Th 2. The absolute value of the cross-track pitch Th1 and the absolute value of the cross-track pitch Th2 may be 0.7 to 1.3 times the track width (or track pitch), for example. The absolute value of the cross track interval Th1 and the absolute value of the cross track interval Th2 may be smaller than 0.7 times the track width or larger than 1.3 times the track width. The absolute value of the cross track interval Th1 and the absolute value of the cross track interval Th2 may be different from each other. On the abscissa of fig. 11, the crossing track intervals in the negative direction with respect to the crossing track interval Th1 correspond to the crossing track intervals when the head 15 is positioned at the respective radial positions of the inner peripheral area IR. On the abscissa of fig. 11, the cross-track intervals Th1 and Th2 correspond to the cross-track intervals when the head 15 is positioned at the respective radial positions of the mid-circumference region MR. On the abscissa of fig. 11, the cross track intervals in the positive direction with respect to the cross track interval Th2 correspond to the cross track intervals when the head 15 is positioned at the respective radial positions in the outer peripheral region OR. In the vertical axis of fig. 11, the read/write bias increases in the direction of a positive arrow from 0, which corresponds to the cross track interval of 0, and decreases in the direction of a negative arrow from 0, which corresponds to the cross track interval of 0. For example, a positive direction of the read/write offset corresponds to an outer direction in the radial direction, and a negative direction of the read/write offset corresponds to an inner direction in the radial direction. In addition, a direction of a positive value of the read/write offset may correspond to an inner direction in the radial direction, and a direction of a negative value of the read/write offset may correspond to an outer direction in the radial direction. Fig. 11 shows a change R1L in read/write offset with respect to the cross track pitch in the case where the read head 15R1 is positioned at each radial position of the disk 10, a change R2L in read/write offset with respect to the cross track pitch in the case where the read head 15R2 is positioned at each radial position of the disk 10, and a change MPL in read/write offset with respect to the cross track pitch in the case where the intermediate portion MP is positioned at each radial position of the disk 10. As shown in fig. 11, a change R1L in read/write offset with respect to the cross-track interval and a change R2L in read/write offset with respect to the cross-track interval are present over the cross-track interval corresponding to each radial position from the inner peripheral region IR to the outer peripheral region OR. A variation MPL of read/write bias with respect to the cross-track interval is exhibited throughout the cross-track interval corresponding to each radius position of the mid-circumference region MR. The read/write offset may be present over the cross-track pitch corresponding to each radial position from the inner peripheral region IR to the outer peripheral region OR, respectively.

In the example shown in FIG. 11, the read/write bias versus cross-track spacing variation R1L has read/write biases IP11, ThP11, MDP11, ThP12, and OP 11. In the example shown in fig. 11, the read/write offset IP11 is negative. The read/write bias IP11 corresponds to the cross-track spacing ICS when the head 15 is positioned at a position in the negative direction, for example, the inner direction, with respect to the radial position corresponding to the cross-track spacing Th 1. For example, the read/write bias ThP11 is negative. In addition, the read/write bias ThP11 may also be positive. The read/write bias ThP11 corresponds to the cross-track spacing Th 1. For example, the read/write bias MDP11 is negative. In addition, the read/write bias MDP11 may also be positive. The read/write offset MDP11 corresponds to the cross-track spacing MCS in the case where the head 15 is positioned at a radial position between a radial position corresponding to the cross-track spacing Th1 and a radial position corresponding to the cross-track spacing Th 2. For example, the read/write bias ThP12 is positive. In addition, the read/write bias ThP12 may also be negative. The read/write bias ThP11 corresponds to the cross-track spacing Th 2. For example, the read/write bias OP11 is positive. In addition, the read/write bias OP11 may also be negative. The read/write bias OP11 corresponds to the cross-track spacing OCS when the head 15 is positioned in the forward direction, for example, in the outward direction, with respect to the radial position corresponding to the cross-track spacing Th 2.

In the example shown in FIG. 11, the read/write bias versus cross-track spacing variation R2L has read/write biases IP21, ThP21, MDP21, ThP22, and OP 21. In the example shown in fig. 11, the read/write offset IP21 is negative. The read/write offset IP21 corresponds to the cross-track spacing ICS. For example, the absolute value of the read/write offset IP21 is smaller than the absolute value of the read/write offset IP 11. For example, the read/write bias ThP21 is negative. In addition, the read/write bias ThP21 may also be positive. The read/write bias ThP21 corresponds to the cross-track spacing Th 1. The absolute value of the read/write offset ThP21 is less than the absolute value of the read/write offset ThP 11. For example, the absolute value of read/write offset ThP21 is about 0.7 times the absolute value of read/write offset ThP 11. In this case, the cross track spacing Th1 corresponds to a radial position where the absolute value of the read/write offset ThP21 becomes about 0.7 times the absolute value of the read/write offset ThP11 in the case where the head 15 is positioned. The absolute value of the read/write offset ThP21 may be 0.7 times or more the absolute value of the read/write offset ThP11, or may be smaller than 0.7 times the absolute value of the read/write offset ThP 11. For example, the read/write bias MDP21 is negative. In addition, the read/write bias MDP21 may also be positive. The read/write offset MDP21 corresponds to the cross-track spacing MCS. For example, the absolute value of the read/write offset MDP21 is smaller than the absolute value of the read/write offset MDP 11. For example, the read/write bias ThP22 is positive. In addition, the read/write bias ThP22 may also be negative. The read/write bias ThP22 corresponds to the cross-track spacing Th 2. The absolute value of the read/write offset ThP22 is less than the absolute value of the read/write offset ThP 12. For example, the absolute value of read/write offset ThP22 is about 0.7 times the absolute value of read/write offset ThP 12. In this case, the cross track spacing Th2 corresponds to a radial position where the absolute value of the read/write offset ThP22 becomes about 0.7 times the absolute value of the read/write offset ThP12 in the case where the head 15 is positioned. The absolute value of the read/write offset ThP22 may be 0.7 times or more the absolute value of the read/write offset ThP12, or may be smaller than 0.7 times the absolute value of the read/write offset ThP 12. For example, the read/write bias OP21 is positive. In addition, the read/write bias OP21 may also be negative. For example, the absolute value of the read/write offset OP21 is smaller than the absolute value of the read/write offset OP 11. The read/write offset OP21 corresponds to the cross-track spacing OCS.

In the example shown in FIG. 11, the read/write offset has a read/write offset MDP31 with respect to the varying MPL of cross-track spacing. In the example shown in FIG. 11, the read/write bias MDP31 is negative. In addition, the read/write bias MDP31 may also be a positive value. For example, the absolute value of the read/write offset MDP21 is smaller than the absolute value of the read/write offset MDP11 and larger than the absolute value of the read/write offset MDP 21. The read/write offset MDP31 corresponds to the cross-track spacing MCS.

In the example shown in fig. 11, when a target track is instructed from the host 100 by a command or the like and a read process is executed (hereinafter, also referred to as initial read), the read/write control section 610 positions the read head 15R1 on the target track located in a wide area, for example, the inner peripheral area IR, based on the read/write offset IP 11. When the read head 15R1 is positioned on the target track and the retry reading is performed at least 1 time, the read/write control unit 610 positions the read head 15R2 on the target track so as to be offset from the read/write offset IP11 to the read/write offset IP 21.

Further, the read/write control section 610 may position the read head 15R2 at the target track located in a wide area, for example, the inner peripheral area IR, with the read/write offset IP21 at the time of initial reading. When the read head 15R2 is positioned on the target track and the retry reading is performed at least 1 time, the read/write control unit 610 positions the read head 15R1 on the target track so as to be offset from the read/write offset IP21 to the read/write offset IP 11.

In the example shown in fig. 11, at the time of initial reading, the read/write control section 610 positions the middle portion MP at the object track located in a narrow region, for example, the middle circumference region MR, with the read/write bias MDP 31. When the intermediate portion MP is positioned on the target track and the retry reading is performed at least 1 time, the read/write control section 610 positions the read head 15R1 on the target track so as to be offset from the read/write offset MDP31 to the read/write offset MDP 11. After positioning the read head 15R1 on the target track, the read/write control section 610 positions the read head 15R2 on the target track so as to be offset from the read/write offset MDP11 to the read/write offset MDP 21.

When the intermediate portion MP is positioned on the target track and the retry reading is performed at least 1 time, the read/write control unit 610 may position the read head 15R2 on the target track so as to be offset from the read/write offset MDP31 to the read/write offset MDP 21. After positioning the read head 15R2 on the target track, the read/write control section 610 positions the read head 15R1 on the target track so as to be offset from the read/write offset MDP21 to the read/write offset MDP 11.

In the example shown in fig. 11, at the time of initial reading, the read/write control section 610 positions the read head 15R1 at the read/write offset OP11 to the object track located in a wide area, for example, the outer peripheral area OR. When the read head 15R1 is positioned on the target track and the retry reading is performed at least 1 time, the read/write control section 610 positions the read head 15R2 on the target track so as to be offset from the read/write offset OP11 to the read/write offset OP 21.

Further, at the initial reading, the read/write control section 610 positions the read head 15R2 at the read/write offset OP21 to the object track located in a wide area, for example, the outer peripheral area OR, and reads the object track by the read head 15R 2. When the read head 15R2 is positioned on the target track and the retry reading is performed at least 1 time, the read/write control section 610 positions the read head 15R1 on the target track so as to be offset from the read/write offset OP21 to the read/write offset OP 11.

The read/write control unit 610 may record the relationship between the cross-track pitch and the read/write offset shown in fig. 11 in a memory, for example, the nonvolatile memory 90, the buffer memory 80, the volatile memory 70, the disk 10, or the like.

Fig. 12 is a flowchart showing an example of the read processing according to the present embodiment.

The MPU60 positions the initial read head of the read heads 15R to a predetermined track in accordance with a command or the like from the host 100 based on the cross-track spacing (CTS) (B1201). For example, when the cross track interval is equal to or smaller than a predetermined value, the MPU60 positions the intermediate portion MP on the predetermined track in accordance with a command from the host 100 or the like. The MPU60 positions a predetermined read head, for example, the read head 15R1 or the read head 15R2, of the read heads 15R at a predetermined track in the case where the cross-track interval is larger than a predetermined value. The MPU60 determines whether the predetermined track can be read or cannot be read in a state where the initial read head is positioned on the predetermined track (B1202). If it is determined that reading is possible (B1202: yes), the MPU60 ends the processing. If it is determined that reading is impossible (B1202: no), the MPU60 determines whether the cross-track interval is greater than or equal to a predetermined value (B1203). For example, the MPU60 determines that the predetermined track cannot be read in a state where the initial read head is positioned on the predetermined track when the initial read head is positioned on the predetermined track and the retry reading is performed at least 1 time, and determines whether the cross-track pitch is larger than the track width (or track pitch) of the predetermined track or equal to or smaller than the track width (or track pitch). In other words, the MPU60 determines that the predetermined track cannot be read in the state where the initial read head is positioned on the predetermined track when the initial read head is positioned on the predetermined track and the retry reading is performed at least 1 time, and determines whether the area where the predetermined track is positioned is a wide area or a narrow area. That is, the MPU60 determines that the predetermined track cannot be read in a state where the initial read head is positioned on the predetermined track when the initial read head is positioned on the predetermined track and the retry reading is performed at least 1 time, and determines whether to position the read head 15R1 or 15R2 on the predetermined track as the initial read head or to position the intermediate portion MP on the predetermined track as the initial read head. If it is determined that the cross-track interval is greater than the predetermined value (B1203: yes), the MPU60 proceeds to the process at B1206. In other words, if it is determined that a changed read head (hereinafter, also referred to as a 1 st changed read head) different from the original read head is fixed to the predetermined track because the cross-track interval is larger than the predetermined value, the MPU60 proceeds to the process of B1205. When it is determined that the cross track interval is equal to or smaller than the predetermined value (B1203: no), the MPU60 positions the change head on the predetermined track (B1204). In other words, when determining that the intermediate portion MP is positioned on the predetermined track because the cross-track interval is equal to or less than the predetermined value, the MPU60 positions the 1 st modified read head among the read heads 15R different from the initial read head on the predetermined track. The MPU60 reads a predetermined track by a different change read head (hereinafter, also referred to as a "2 nd change read head") different from the 1 st change read head (B1205), and ends the process.

According to the present embodiment, the magnetic disk device 1 includes the read head 15R, for example, the read heads 15R1 and 15R 2. The magnetic disk apparatus 1 positions the intermediate portion MP at a predetermined track located in a narrow area in accordance with a command or the like from the host 100. When the intermediate portion MP is located at a predetermined track and the retry reading is performed at least 1 time (or a plurality of times), the magnetic disk apparatus 1 positions the read head 15R1 at the predetermined track. After positioning the read head 15R1 at a predetermined track, the magnetic disk apparatus 1 positions the read head 15R2 at a predetermined track. The magnetic disk apparatus 1 positions the read head 15R1 (or the read head 15R2) at a predetermined track located over a wide area in accordance with a command or the like from the host 100. In the case where at least 1 (or a plurality of) retried reading is performed with the read head 15R1 (or the read head 15R2) positioned at a predetermined track, the magnetic disk apparatus 1 positions the read head 15R2 at the predetermined track. Therefore, the magnetic disk device 1 can position the appropriate one of the read heads 15R to the predetermined track based on the cross-track pitch without performing the process of selecting the appropriate read head from the read head 15R and the process of adjusting and positioning the selected read head at the optimum position. In addition, when the initial read head is positioned on the predetermined track and the retry reading is performed at least 1 time, the magnetic disk apparatus 1 can position at least one changed read head different from the initial read head among the read heads 15R on the predetermined track based on the cross track interval, thereby shortening the time for the retry reading. Therefore, the magnetic disk apparatus 1 can improve the read processing performance.

Next, a magnetic disk device according to another embodiment will be described. In other embodiments, the same portions as those in the above-described embodiments are denoted by the same reference numerals, and detailed description thereof is omitted.

(embodiment 2)

The read head 15R of the magnetic disk device 1 of embodiment 2 is different from the magnetic disk device 1 of embodiment 1.

Fig. 13 is a diagram showing an example of the arrangement of the reading head 15R according to embodiment 2. Fig. 13 shows only the components necessary for explanation. Fig. 13 shows a target track ITRm of the sector ZNm located in the inner peripheral region IR inward of the middle peripheral region MR including the reference position RP0, and a track (hereinafter, also referred to as an adjacent track) ITRm +1 adjacent to the target track ITRm in the inner direction in the sector ZNm. The adjacent track ITRm +1 may be adjacent to the target track ITRm in the outer direction. The adjacent track ITRm +1 is written so as to overlap the target track ITRm in the inner direction. The track width TW3 of the target track ITCm is smaller than the track width TW2 of the adjacent track ITRm + 1. The read head 15R2 is located at the track center ITCm of the target track ITRm. In the example shown in FIG. 13, the read head 15R2 overlaps the target track ITRm. The read head 15R1 does not overlap the target track ITRm. For example, the width R2W2 of the readhead 15R2 is less than the width R1W1 of the readhead 15R 1. The width of the pickup head 15R1 may be smaller than the width of the pickup head 15R 2. For example, the error rate in the case where the read head 15R2 is positioned on the target track ITRm and the target track ITRm is read by the read head 15R2 is smaller than the error rate in the case where the read head 15R1 is positioned on the target track ITRm and the target track ITRm is read by the read head 15R 1. For example, the error rate in the case where the read head 15R1 is positioned on the target track ITRm and the target track ITRm is read by the read head 15R1 may be smaller than the error rate in the case where the read head 15R2 is positioned on the target track ITRm and the target track ITRm is read by the read head 15R 2. For example, the error rate in the case where the read head 15R1 is positioned on the adjacent track ITRm +1 and the adjacent track ITRm +1 is read by the read head 15R1 is smaller than the error rate in the case where the read head 15R2 is positioned on the adjacent track ITRm +1 and the adjacent track ITRm +1 is read by the read head 15R 2. For example, the error rate in the case where the read head 15R2 is positioned on the adjacent track ITRm +1 and the adjacent track ITRm +1 is read by the read head 15R2 may be smaller than the error rate in the case where the read head 15R1 is positioned on the adjacent track ITRm +1 and the adjacent track ITRm +1 is read by the read head 15R 1.

In the example shown in fig. 13, the read/write control unit 610 positions the small-width read head 15R2 of the read heads 15R1 and 15R2 at the track center ITCm of the target track ITRm when the track width TW3 of the target track ITRm located in the inner peripheral region IR having the cross-track pitch larger than the track width (or track pitch) is smaller than the track width of the peripheral track, for example, the track width TW2 of the adjacent track ITRm + 1. When determining that the target track ITRm cannot be read with the read head 15R2 positioned over the target track ITRm, the read/write control unit 610 positions the read head 15R1 over the track center ITCm of the target track ITRm.

When the track width of the target track located in the outer peripheral region OR having the cross track pitch larger than the track width (OR track pitch) is smaller than the track width of the peripheral track, for example, the track width of the adjacent track, the read/write control unit 610 positions the read head 15R2 having the smaller width of the read heads 15R1 and 15R2 to the target track. When the read/write control unit 610 determines that the target track cannot be read while the read head 15R2 is positioned on the target track, it positions the read head 15R1 on the target track.

When reading the target track ITRm +1 of the track width TW2 located in the inner peripheral region IR where the cross track pitch is larger than the track width (or the track pitch) and the track width TW3 of the adjacent track ITRm, the read/write control unit 610 positions the read head 15R1 having a larger width of the read heads 15R1 and 15R2 at (the track center of) the target track ITRm + 1. When determining that the target track ITRm +1 cannot be read with the read head 15R1 positioned over the target track ITRm +1, the read/write control unit 610 positions the read head 15R2 over (the center of) the target track ITRm + 1.

When the read/write control unit 610 determines that the target track cannot be read while the intermediate portion MP is positioned on the target track having a track width smaller than the track width of the peripheral track in the middle peripheral region (narrow region) MR having a cross track pitch smaller than the track width (or track pitch), the small read head 15R2 of the read heads 15R1 and 15R2 is positioned on the target track. After positioning the read head 15R2 on the target track, the read/write control section 610 positions the read head 15R1 on the target track.

In the example shown in fig. 13, when reading the target tracks located in the inner peripheral region IR and the outer peripheral region OR, in which the cross track pitch is larger than the track width (OR track pitch), the read/write control section 610 may determine that the cross track pitch is larger than the track width of the target tracks and position the intermediate section MP at the track center of the target tracks.

According to embodiment 2, the magnetic disk device 1 includes the read head 15R, for example, the read heads 15R1 and 15R 2. The width R2W2 of the readhead 15R2 is less than the width R1W1 of the readhead 15R 1. When reading a predetermined track located in a wide area in accordance with a command or the like from the host 100, the magnetic disk device 1 determines whether the track width of the predetermined track is equal to or less than the track width (or track pitch) of peripheral tracks, for example, adjacent tracks, or is larger than the track width of the adjacent tracks. When it is determined that the track width of the predetermined track located in the wide area is equal to or less than the track width (or track pitch) of the adjacent tracks, the magnetic disk apparatus 1 positions the small-width read head 15R2 of the read heads 15R1 and 15R2 at the predetermined track. In addition, when the magnetic disk device 1 determines that the predetermined track cannot be read in a state where the intermediate portion MP is positioned at the predetermined track having a track width smaller than the track width (or track pitch) of the peripheral tracks in the narrow region, the small-width read head 15R2 of the read heads 15R1 and 15R2 is positioned at the predetermined track. Therefore, when the track width of the predetermined track is equal to or less than a predetermined value, for example, the track width (or track pitch) of the peripheral track, the magnetic disk device 1 positions the initial read head having the smallest width among the read heads 15R at the predetermined track. Therefore, the magnetic disk apparatus 1 can improve the read processing performance.

Although several embodiments have been described above, these embodiments are presented as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the spirit of the invention. These embodiments and modifications thereof are included in the scope and spirit of the invention, and are included in the invention described in the claims and the equivalent scope thereof.