Disc device and method for generating data to be written

Abstract

Provided is a magnetic disk device capable of improving reliability and a method of generating write data. The magnetic disk device of the present embodiment includes a disk, a head that writes data to the disk and reads data from the disk, a preamplifier that generates a recording current corresponding to data written to the disk by the head, and a controller that, based on a pattern length of a second data pattern immediately preceding a first data pattern in first write data, transforms the first data pattern into a different data pattern that includes a dummy polarity inversion that does not occur when the recording current is transformed.

Description

[0001] Related Application

[0002] This application enjoys priority based on Japanese Patent Application No. 2021-151292 (Filing date: September 16, 2021) as a prior application. The entire contents of the prior application are hereby incorporated by reference in this application. TECHNICAL FIELD

[0003] Embodiments of the present application relate to a disk device and a generation method of write data. BACKGROUND

[0004] A disk device capable of writing in a PBW (Pulse Based Writing) manner is being developed, the PBW manner being a writing manner realized based on a waveform of a recording current including an overshoot waveform that is pulse-shaped raised or lowered every certain time, or a waveform not including a DC component equivalent to a certain current value that is smaller than an absolute value of the pulse-shaped raised or lowered waveform and greater than 0. In the disk device, a data pattern of a certain pattern length within predetermined write data (hereinafter, also referred to as a transformation target pattern) is 1 to 1 transformed into a certain data pattern (hereinafter, also referred to as a PBW pattern). The PBW pattern has a dummy polarity inversion (hereinafter, also referred to as a dummy inversion) that does not occur when transformed into the recording current. The disk device of the PBW manner causes the recording current to be generated from the PBW pattern without the polarity inversion occurring at a position of the dummy inversion based on a mask signal indicating the position of the dummy inversion. In the disk device, the data pattern around the transformation target pattern within the predetermined write data can have an influence on a recording quality such as a BER (Bit Error Rate) in a case where data is written to a disk in the PBW manner. SUMMARY

[0005] An object of embodiments of the present application is to provide a disk device and a generation method of write data capable of improving reliability.

[0006] The disk device of the present embodiment includes a disk, a head that writes data to the disk and reads data from the disk, a preamplifier that generates a recording current corresponding to data written to the disk by the head, and a controller that transforms a first data pattern into a different data pattern including a dummy polarity inversion that does not occur when transformed into the recording current, according to a pattern length of a second data pattern immediately before the first data pattern within first write data. BRIEF DESCRIPTION OF DRAWINGS

[0007] Figure 1 is a block diagram showing a configuration of a disk device of an embodiment.

[0008] Figure 2 is a schematic view showing an example of a disc of the embodiment.

[0009] Figure 3 is a schematic view showing a configuration example of a write system of the magnetic disk device of the embodiment.

[0010] Figure 4 is a graph showing an example of an influence on recording quality generated by a combination of a first pattern of a transform target pattern and a data pattern immediately before it.

[0011] Figure 5 is a graph showing an example of an influence on recording quality generated by a combination of a last pattern of a transform target pattern and a data pattern immediately before it.

[0012] Figure 6 is a graph showing an example of an influence on recording quality generated by a combination of a last pattern of a transform target pattern and a data pattern immediately before it.

[0013] Figure 7 is a schematic view showing an example of a pattern transform table of the embodiment.

[0014] Figure 8 is a schematic view showing an example of a pattern transform table of the embodiment.

[0015] Figure 9A is a schematic view showing an example of a transform method of write data of the embodiment.

[0016] Figure 9B is Figure 9A is an enlarged view of a part of the base write data, a part of the PBW write data, a part of the mask signal, and a part of the recording current.

[0017] Figure 10 is a flowchart showing an example of a generation method of write data of the embodiment. DETAILED DESCRIPTION

[0018] Hereinafter, the embodiments will be described with reference to the drawings. In addition, the drawings are examples, and do not limit the scope of the invention.

[0019] (Embodiment)

[0020] Figure 1 is a block diagram showing a configuration of the magnetic disk device 1 of the embodiment.

[0021] The magnetic disk device 1 is provided with: a head disk assembly (HDA) described later, a driver IC 20, a head amplifier integrated circuit (hereinafter, referred to as a head amplifier IC or a preamplifier) 30, a volatile memory 70, a non-volatile memory 80, a buffer memory (cache) 90, a system controller 130 which is an integrated circuit of a single chip. In addition, the magnetic disk device 1 is connected with a host system (hereinafter, referred to simply as a host) 100.

[0022] The HAD has: a magnetic disk (hereinafter, referred to as a disk) 10, a spindle motor (hereinafter, referred to as an SPM) 12, an arm 13 on which a head 15 is mounted, a voice coil motor (hereinafter, referred to as a VCM) 14. The disk 10 is mounted to the SPM 12, and rotates by driving of the SPM 12. The arm 13 and the VCM 14 constitute an actuator. The actuator moves and controls the head 15 mounted to the arm 13 to a predetermined position of the disk 10 by driving of the VCM 14. The disk 10 and the head 15 can also be provided in a number of two or more.

[0023] The disk 10 is assigned, in a region in which data can be written, a user data region 10a which can be used by a user, and a system region 10b in which information required for system management is written. Hereinafter, a direction from an inner periphery toward an outer periphery of the disk 10, or a direction from an outer periphery toward an inner periphery of the disk 10 is referred to as a radial direction. In the radial direction, a direction from the inner periphery toward the outer periphery is referred to as an outer direction (or an outer side), and a direction from the inner periphery toward the outer periphery is referred to as an inner direction (or an inner side). A circumferential direction corresponds to a direction along a circumference of the disk 10. The radial direction and the circumferential direction are orthogonal to each other. In addition, sometimes a predetermined position of the radial direction of the disk 10 is referred to as a radial position, and a predetermined position of the circumferential direction of the disk 10 is referred to as a circumferential position. Sometimes the radial position and the circumferential position are collectively referred to as a position. The user data region 10a of the disk 10 can be divided into a plurality of regions. For example, the user data region 10a can be divided in the radial direction by each region (hereinafter, sometimes referred to as a zone) containing a predetermined number of tracks. The zone can be divided in the radial direction by each track.

[0024] Further, "track" is used in the meaning of one recording area within a plurality of recording areas obtained by dividing the disk 10 in the radial direction, one recording area of one turn at a predetermined radial position of the disk 10, a predetermined recording area at a predetermined radial position of the disk 10, a recording area extending in the circumferential direction of the disk 10, a recording area corresponding to a path of the head 15 positioned at a predetermined radial position of the disk 10, a path of the head 15 positioned at a predetermined radial position of the disk 10, data written to one recording area within a plurality of recording areas obtained by dividing the disk 10 in the radial direction, data written to one recording area of one turn at a predetermined radial position of the disk 10, data written to a predetermined recording area at a predetermined radial position of the disk 10, data written to a recording area extending in the circumferential direction of the disk 10, data written to a recording area corresponding to a path of the head 15 positioned at a predetermined radial position of the disk 10, data written along a path of the head 15 positioned at a predetermined radial position of the disk 10, data extending in the circumferential direction of the disk 10, data written to a predetermined track of the disk 10, data of one turn written to a predetermined track of the disk 10, a part of data written to a predetermined track of the disk 10, or other various meanings. "Sector" is used in the meaning of one recording area within a plurality of recording areas obtained by dividing a predetermined track of the disk 10 in the circumferential direction, one recording area within a plurality of recording areas obtained by dividing a recording area extending in the circumferential direction at a predetermined radial position of the disk 10, a predetermined recording area of a predetermined track of the disk 10, a predetermined circumferential position of a predetermined track of the disk 10, a predetermined circumferential position at a predetermined radial position of the disk 10 (predetermined position), data written to one recording area within a plurality of recording areas obtained by dividing a predetermined track of the disk 10 in the circumferential direction, data written to one recording area within a plurality of recording areas obtained by dividing a recording area extending in the circumferential direction at a predetermined radial position of the disk 10, data written to a predetermined recording area of a predetermined track of the disk 10, data written to a predetermined circumferential position of a predetermined track of the disk 10, data written to a predetermined circumferential position at a predetermined radial position of the disk 10 (predetermined position), data written to a predetermined sector, or other various meanings. Sometimes, "radial direction width of a track" is referred to as "track width". Sometimes, "a path passing through a center position of a track width in a predetermined track" is referred to as "track center".

[0025] The head 15 has a slider as a main body, and has a write head 15W and a read head 15R attached to the slider. The write head 15W writes data to the disc 10 according to a write current (or recording current) output from a head amplifier IC described later. The read head 15R reads data recorded on the disc 10. Also, "write head 15W" is sometimes referred to simply as "head 15", "read head 15R" is sometimes referred to simply as "head 15", and "write head 15W and read head 15R" are sometimes referred to collectively as "head 15". Also, "the center portion of head 15" is sometimes referred to as "head 15", "the center portion of write head 15W" is sometimes referred to as "write head 15W", and "the center portion of read head 15R" is sometimes referred to as "read head 15R". Also, "the center portion of write head 15W" is sometimes referred to simply as "head 15", and "the center portion of read head 15R" is sometimes referred to simply as "head 15". Also, the case where "the center portion of head 15 is positioned at the track center of a predetermined track" is sometimes expressed as "head 15 is positioned at a predetermined track", "head 15 is arranged at a predetermined track", or "head 15 is located at a predetermined track".

[0026] Figure 2 is a schematic view showing an example of the disc 10 of the present embodiment. As shown in Figure 2 , the direction in which the disc 10 is rotated is referred to as the rotation direction in the circumferential direction. Also, in the example shown in Figure 2 , the rotation direction is indicated in the counterclockwise direction, but it can be the opposite direction (clockwise direction). In Figure 2 , the disc 10 is divided into an inner circumferential region IR located in the inner direction, an outer circumferential region OR located in the outer direction, and a middle circumferential region MR located between the inner circumferential region IR and the outer circumferential region OR.

[0027] In the example shown in Figure 2 , the disc 10 includes a user data area 10a and a system area 10b. In Figure 2 , the user data area 10a and the system area 10b are adjacent in the radial direction. Here, "adjacent" means that data, objects, regions, spaces, and the like are arranged in contact with each other, but also includes the case where they are arranged with a predetermined interval therebetween. In Figure 2 , the system area 10b is adjacent to the user data area 10a in the outer direction thereof. Also, the system area 10b can be adjacent to the user data area 10a in the inner direction thereof. In addition, the system area 10b can be arranged between the user data area 10a in the radial direction.

[0028] In the example shown in Figure 2In the example shown, the user data area 10a is disposed in a range from the inner circumferential area IR to the outer circumferential area OR. The system area 10b is disposed in the outer circumferential area OR. The system area 10b can also be disposed in the inner circumferential area IR or the middle circumferential area MR. The system area 10b can also be disposed dispersed in the outer circumferential area OR, the middle circumferential area MR, or the inner circumferential area IR.

[0029] As shown, the head 15 is opposed to the disk 10, and is moved from the inner direction to the outer direction to be disposed at a predetermined position, or from the outer direction to the inner direction to be disposed at a predetermined position, by driving of the VCM 14. Figure 3

[0030] The drive IC 20 controls driving of the SPM 12 and the VCM 14 in accordance with control of the system controller 130 (in detail, the MPU 60 described later).

[0031] The head amplifier IC (pre-amplifier) 30 has a read amplifier and a write driver. The read amplifier amplifies a read signal read from the disk 10 and outputs it to the system controller 130 (in detail, the read / write (R / W) channel 60 described later). The write driver outputs a write current (or recording current) corresponding to write data output from the R / W channel 60 to the head 15. The head amplifier IC 30 is electrically connected to the head 15 and the R / W channel 60 via a wiring or the like.

[0032] The volatile memory 70 is a semiconductor memory in which data held when power supply is cut off is lost. The volatile memory 70 holds data and the like required for processing of each part of the disk device 1. The volatile memory 70 is, for example, a DRAM (Dynamic Random Access Memory) or a SDRAM (Synchronous Dynamic Random Access Memory).

[0033] The non-volatile memory 80 is a semiconductor memory in which data held is recorded even when power supply is cut off. The non-volatile memory 80 is, for example, a flash ROM (Flash Read Only Memory: FROM) of a NOR type or a NAND type.

[0034] ​The buffer memory 90 is a semiconductor memory that temporarily records data and the like that are transmitted and received between the disk device 1 and the host 100. Further, the buffer memory 90 can also be integrally constituted with the volatile memory 70. The buffer memory 90 is, for example, a DRAM, an SRAM (Static Random Access Memory), an SDRAM, a FeRAM (Ferroelectric Random Access memory), or an MRAM (Magnetoresistive Random Access Memory), or the like.

[0035] The system controller (controller) 130 is realized, for example, using a large-scale integrated circuit (LSI) called a System-on-a-Chip (SoC) in which a plurality of elements are integrated in a single chip. The system controller 130 includes a microprocessor (MPU) 40, a hard disk controller (HDC) 50, and a read / write (R / W) channel 60, and the like. The MPU 40, the HDC 50, and the R / W channel 60 are electrically connected to each other. The system controller 130 is electrically connected to, for example, the drive IC 20, the head amplifier IC 30, the volatile memory 70, the non-volatile memory 80, the buffer memory 90, and the host 100, and the like.

[0036] The MPU 40 is a main controller that controls each part of the disk device 1. The MPU 40 controls the VCM 14 via the drive IC 20, and performs servo control that performs positioning of the head 15. The MPU 40 controls the SPM 12 via the drive IC 20, and causes the disk 10 to rotate. The MPU 40 controls a write operation of data to the disk 10, and selects a storage destination of data (hereinafter, also referred to as write data) that is transmitted from the host 100 to be written to the disk 10. The MPU 40 controls a read operation of data from the disk 10, and controls processing of data (hereinafter, also referred to as read data) that is transmitted from the disk 10 to the host 100. Hereinafter, the "write data" is also sometimes referred to as simply "data". The "read data" is also sometimes referred to as simply "data". The "write data and the read data" are also sometimes collectively referred to as simply "data". In addition, the MPU 40 manages a region in which data is recorded. The MPU 40 is connected to each part of the disk device 1. The MPU 60 is electrically connected to, for example, the drive IC 20, the HDC 50, and the R / W channel 60, and the like.

[0037] The MPU 40 controls a read process of reading data from the disc 10 and a write process of writing data to the disc 10 in accordance with a command or the like from the host 100. The MPU 40 controls the VCM 14 via the driver IC 20 to position the head 15 at a predetermined position of the disc 10, and performs the read process or the write process. Hereinafter, the term "access" is also used in the meaning of a case where data is recorded or written to a predetermined area (or write process), a case where data is read out or read from a predetermined area (or read process), and a case where the head 15 or the like is moved to a predetermined area.

[0038] The HDC 50 controls transfer of data. For example, the HDC 50 controls transfer of data between the host 100 and the R / W channel 60 described later in accordance with an instruction from the MPU 40. The HDC 50 is electrically connected to the MPU 40, the R / W channel 60, the volatile memory 70, the non-volatile memory 80, and the buffer memory 90, for example.

[0039] The R / W channel 60 performs signal processing of read data transferred from the disc 10 to the host 100 and write data transferred from the host 100 in accordance with an instruction from the MPU 40. The R / W channel 60 has a circuit or a function of measuring a signal quality of the read data. The R / W channel 60 has a circuit or a function of performing signal processing of the write data transferred from the host 100 or the like. The R / W channel 60 is electrically connected to the head amplifier IC 30, the MPU 40, and the HDC 50, for example.

[0040] Hereinafter, a system that writes the write data transferred from the host 100 to the disc 10 in the head 15, the head amplifier IC 30, and the system controller 130 will also be sometimes referred to as a write system.

[0041] Figure 3 is a schematic view that shows a configuration example of a write system WSY of the disc device 1 of the present embodiment. In Figure 4 , only configurations necessary for explanation are shown.

[0042] The write system WSY includes the head 15, the head amplifier IC 30, and the system controller 130. The write system WSY generates write data.

[0043] The R / W channel 60 has a write data generator 601, a pattern analyzer 602, a table management section 603, a PBW (Pulse Based Writing) write data generator 604, a mask signal generator 605, and a PECL 606, and the like as the write system WSY. The R / W channel 60 can also execute the processes of the write data generator 601, the pattern analyzer 602, the table management section 603, the PBW write data generator 604, the mask signal generator 605, and the PECL 606, and the like on firmware, or can have the write data generator 601, the pattern analyzer 602, the table management section 603, the PBW write data generator 604, the mask signal generator 605, and the PECL 606, and the like as circuits.

[0044] The head amplifier IC 30 has a mask signal controller 301 and a write driver 302, and the like as the write system WSY. The head amplifier IC 30 can also execute the processes of the mask signal controller 301 and the write driver 302, and the like on firmware, or can have the mask signal controller 301 and the write driver 302, and the like as circuits.

[0045] The write data generator 601 generates write data (hereinafter, also referred to as basic write data) by performing signal processing on data transferred from the host 100 via the HDC 50. The write data generator 601 is connected to the pattern analyzer 602. The write data generator 601 outputs the generated basic write data to the pattern analyzer 602.

[0046] The pattern analyzer 602 analyzes the data pattern (hereinafter, also referred to simply as pattern) of the write data. For example, the pattern analyzer 602 analyzes the data pattern of the bit sequence (bit string) of the write data, and the pattern length (nT) of the data pattern, and the like. Here, n is a positive integer. In addition, 1T corresponds to the unit length of the pattern length. 1T corresponds to the data pattern of 1T bit in the NRT (Non-Return to Zero) system. nT is the pattern length of n times 1T. The pattern analyzer 602 is connected to the write data generator 601, the table management section 603, and the PBW write data generator 604. The pattern analyzer 602 outputs the result of the analysis (hereinafter, also referred to as analysis result) to the table management section 603 and the PBW write data generator 604. Hereinafter, the "data pattern of the pattern length nT" is also referred to as "nT data pattern". In addition, the "data pattern of the pattern length nT and the data pattern of the pattern length mT, and the like" is also referred to as "[nT, mT, …] data pattern" or "nT+mT+… data pattern". Here, m is a positive integer.

[0047] The table management section 603 manages the pattern conversion table. For example, the table management section 603 can function as a memory that holds the pattern conversion table. The table management section 603 has at least one pattern conversion table. For example, the table management section 603 has a plurality of pattern conversion tables. The table management section 603 selects and switches the plurality of pattern conversion tables based on the analysis result input from the pattern analyzer 602, and the characteristics of the disc 10 and the head 15, and the like. The table management section 603 is connected to the pattern analyzer 602 and the PBW write data generator 604. The table management section 603 outputs the selected pattern conversion table to the PBW write data generator 604.

[0048] The PBW write data generator 604 generates write data (hereinafter, also referred to as PBW write data) corresponding to a recording current of a PBW (Pulse Based Writing) system. The PBW system is a recording system that writes data with a recording current waveform in which the recording current is pulsed up or down (hereinafter, also referred to as overshoot) at a position of polarity inversion, and does not include a DC section in which the recording current other than the recording current of the overshoot is set to a predetermined current value, for example, a certain current value larger than 0. Therefore, the recording current waveform of the PBW system is such that the recording current that is increased in order to enhance the magnetic field at the position of polarity inversion of the recording current is pulsed up or down (overshoot), and the recording current other than the recording current of the overshoot is set to a certain current value, for example, 0. The PBW write data generator 604 is connected to the pattern analyzer 602, the table management section 603, the shield signal generator 605, and the PECL 606, and the like. The PBW write data generator 604 outputs the PBW write data to the shield signal generator 605 and the PECL 606, respectively. In addition, the PBW write data generator 604 can output the PBW write data under generation to the pattern analyzer 602.

[0049] The PBW write data generator 604 converts (changes, modulates, or adjusts) a data pattern (hereinafter, also referred to as a conversion target pattern) of a predetermined pattern length in the base write data into a data pattern (hereinafter, also referred to as a PBW pattern) that includes a pseudo polarity inversion (hereinafter, also referred to as a pseudo inversion) that is signal-processed so as not to occur at the time of conversion into a recording current, based on the analysis result and the selected pattern conversion table, and thereby converts (changes, modulates, or adjusts) the base write data into PBW write data.

[0050] The PBW write data generator 604 transforms the predetermined transform target pattern in the base write data into a PBW pattern in accordance with the pattern length of the data pattern in the PBW data pattern immediately preceding (immediately preceding transmitted or temporally preceding adjacent) based on the analysis result and the pattern transform table. In other words, the PBW write data generator 604 changes the position of the pseudo-inversion of the PBW pattern into which the transform target pattern is transformed based on the pattern length of the data pattern in the PBW data pattern immediately preceding the predetermined transform target pattern in the base write data based on the analysis result and the pattern transform table. In the process of transforming the base write data into the PBW write data, the PBW write data generator 604 transforms the predetermined transform target pattern in the base write data into a PBW pattern in accordance with the pattern length of the data pattern in the PBW data pattern immediately preceding based on the analysis result and the pattern transform table. In other words, in the process of transforming the base write data into the PBW write data, the PBW write data generator 604 changes the position of the pseudo-inversion of the PBW pattern into which the transform target pattern is transformed based on the pattern length of the data pattern in the PBW data pattern immediately preceding the predetermined transform target pattern in the base write data based on the analysis result and the pattern transform table. The PBW write data generator 604 transforms the plurality of transform target patterns in the base write data into PBW patterns in accordance with the pattern length of the data pattern in the plurality of PBW data patterns immediately preceding each of the plurality of transform target patterns in the base write data based on the analysis result and the selected pattern transform table, and transforms the base write data into the PBW write data. In other words, the PBW write data generator 604 changes the position of the pseudo-inversion of the plurality of PBW patterns into which the plurality of transform target patterns are transformed respectively based on the pattern length of the data pattern in the plurality of PBW data patterns immediately preceding each of the plurality of transform target patterns in the base write data based on the analysis result and the selected pattern transform table, and transforms the base write data into the PBW write data. The PBW write data generator 604 outputs the transformed PBW write data to the shield signal generator 605 and the PECL 606. Furthermore, the PBW write data generator 604 can update (or switch) the analysis result and the pattern transform table in the process of transforming the base write data into the PBW write data so as to correspond to the base write data after the predetermined transform target pattern is transformed into a PBW pattern. Hereinafter, the "data pattern immediately preceding the transform target pattern" is sometimes referred to simply as the "immediately preceding data pattern" or the "immediately preceding pattern".

[0051] Figure 4 is a diagram showing an example of the influence on the recording quality resulting from the combination of the first pattern of the transform target pattern and the immediately preceding data pattern. In Figure 4In the graph, the vertical axis indicates a gain in BER (Bit Error Rate) corresponding to an improvement in recording quality of data written to the disc 10 by the PBW method, and the horizontal axis indicates the pattern length of the immediately preceding data pattern. Figure 4 The horizontal axis shows the pattern length 1T, 2T, and 3T of the immediately preceding data pattern. Hereinafter, the "immediately preceding data pattern having a pattern length of nT" or the "immediately preceding data pattern having a pattern length of nT" is also sometimes referred to as the "immediately preceding nT data pattern". Hereinafter, a portion of a data pattern having a pattern length of mT, which is smaller than the pattern length nT, that is initially transmitted in a data pattern having a pattern length of nT is referred to as a head portion, a portion of a data pattern having a pattern length of IT, which is smaller than the pattern length nT, that is finally transmitted in a data pattern having a pattern length of nT is referred to as a tail portion, and a portion of a data pattern having a pattern length of kT, which is smaller than the pattern length nT, that is between the head portion and the tail portion in a data pattern having a pattern length of nT is referred to as an intermediate portion. Here, 1, k are positive integers. Figure 4 The graph shows a gain in BER (hereinafter, also sometimes referred to as a gain in BER corresponding to the [1T, 1T] head pattern) in the case where the data pattern of the head portion of the transform target pattern (hereinafter, also sometimes referred to as a head pattern) is transformed into a continuous [1T, 1T] data pattern (PBW pattern), and a gain in BER (hereinafter, also sometimes referred to as a gain in BER corresponding to the [2T, 1T] head pattern) in the case where the head pattern of the transform target pattern is transformed into a continuous [2T, 1T] data pattern (PBW pattern). Hereinafter, the "continuous [nT, mT,... ] data pattern of the head portion of the transform target pattern" is also sometimes referred to as the "[nT, mT,... ] head pattern" or the "nT + mT +... head pattern". In the graph, the gain in BER corresponding to the [1T, 1T] head pattern is indicated by a rectangular shape of a right-downward sloping line, and the gain in BER corresponding to the [2T, 1T] head pattern is indicated by a hollow rectangular shape. Figure 4 In the graph, the gain in BER corresponding to the [1T, 1T] head pattern is indicated by a rectangular shape of a right-downward sloping line, and the gain in BER corresponding to the [2T, 1T] head pattern is indicated by a hollow rectangular shape. The [1T, 1T] head pattern corresponds to a data pattern in which a data pattern having a pattern length of 1T (hereinafter, also sometimes referred to as a headmost pattern) disposed at the headmost of the head pattern is immediately followed by a data pattern having a pattern length of 1T (hereinafter, also sometimes referred to as a headmost adjacent pattern). The [2T, 1T] head pattern corresponds to a data pattern in which the headmost pattern having a pattern length of 2T is immediately followed by the headmost adjacent pattern having a pattern length of 1T.

[0052] In the graph, the gain in BER corresponding to the [1T, 1T] head pattern is indicated by a rectangular shape of a right-downward sloping line, and the gain in BER corresponding to the [2T, 1T] head pattern is indicated by a hollow rectangular shape. The [1T, 1T] head pattern corresponds to a data pattern in which a data pattern having a pattern length of 1T (hereinafter, also sometimes referred to as a headmost pattern) disposed at the headmost of the head pattern is immediately followed by a data pattern having a pattern length of 1T (hereinafter, also sometimes referred to as a headmost adjacent pattern). The [2T, 1T] head pattern corresponds to a data pattern in which the headmost pattern having a pattern length of 2T is immediately followed by the headmost adjacent pattern having a pattern length of 1T. Figure 4In the example shown, in the case where the pattern length of the immediately preceding data pattern is 1T, the gain in BER corresponding to the [2T, 1T] leading pattern is greater than the gain in BER corresponding to the [1T, 1T] leading pattern. That is, in the case where the pattern length of the immediately preceding data pattern is 1T, the recording quality is improved by transforming the leading pattern of the transform target pattern into the [2T, 1T] leading pattern, as compared to transforming the leading pattern of the transform target pattern into the [1T, 1T] leading pattern. In the case where the pattern length of the immediately preceding data pattern is 1T, when the write processing is performed on the disc 10 by the head 15 based on the recording current generated in accordance with the PBW pattern that is transformed from the transform target pattern, the magnetization response in the head 15 is delayed due to the magnetization reversal occurring immediately after the pulse current is generated. Therefore, in the case where the pattern length of the immediately preceding data pattern is 1T, the magnetization response of the head 15 is accelerated by transforming the leading pattern of the transform target pattern into the [2T, 1T] leading pattern, as compared to transforming the leading pattern of the transform target pattern into the [1T, 1T] leading pattern, and thus the improvement in recording quality is also greater. In other words, in the case where the pattern length of the immediately preceding data pattern is 1T, the magnetization response of the head 15 is accelerated by transforming the data pattern disposed in the most leading portion of the transform target pattern (hereinafter, also referred to as the most leading pattern) into a 2T data pattern, as compared to transforming the most leading pattern into a 1T data pattern, and thus the improvement in recording quality is also greater. The most leading pattern corresponds to the most leading portion of the leading pattern of the predetermined data pattern.

[0053] In Figure 5In the example shown, in the case where the pattern length of the immediately preceding data pattern is 2T, the gain in BER corresponding to the [1T, 1T] leading pattern is greater than the gain in BER corresponding to the [2T, 1T] leading pattern. That is, in the case where the pattern length of the immediately preceding data pattern is 2T, transforming the leading pattern of the transform target pattern into the [1T, 1T] leading pattern results in improved recording quality, as compared to transforming the leading pattern of the transform target pattern into the [2T, 1T] leading pattern. In the case where the pattern length of the immediately preceding data pattern is 2T, when the write processing of the disk 10 by the head 15 based on the recording current generated from the PBW pattern after the transform of the transform target pattern is performed, the magnetization state in the head 15 is also reset because the pulse current is once reset to zero. Therefore, in the case where the pattern length of the immediately preceding data pattern is 2T, when the write processing of the disk 10 by the head 15 based on the recording current generated from the PBW pattern after the transform of the transform target pattern is performed, since a large current is not required for the initial polarity inversion, by transforming the leading portion of the transform target pattern into the [1T, 1T] leading pattern, driving is performed with the necessary minimum current, and the influence on the NLTS (Non Linear Transition Shift), adjacent erasure, and the like can be suppressed. In other words, in the case where the pattern length of the immediately preceding data pattern is 2T, when the write processing of the disk 10 by the head 15 based on the recording current generated from the PBW pattern after the transform of the transform target pattern is performed, since a large current is not required for the initial polarity inversion, by transforming the leading pattern of the transform target pattern into the 1T data pattern, driving is performed with the necessary minimum current, and the influence on the NLTS, adjacent erasure, and the like can be suppressed.

[0054] In Figure 5In the example shown, in the case where the data length of the immediately preceding data pattern is 3T, the gain in BER corresponding to the [1T, 1T] leading pattern is greater than the gain in BER corresponding to the [2T, 1T] leading pattern. That is, in the case where the data length of the immediately preceding data pattern is 3T, compared to transforming the leading pattern of the transform target pattern into the [2T, 1T] leading pattern, transforming it into the [1T, 1T] leading pattern enables an improvement in recording quality. In the case where the data length of the immediately preceding data pattern is 3T, when the write processing of the disk 10 by the head 15 based on the recording current generated from the PBW pattern after the transformation of the transform target pattern is performed, the magnetization state in the head 15 is also reset because the pulse current is once reset to zero. Therefore, in the case where the pattern length of the immediately preceding data pattern is 3T, when the write processing of the disk 10 by the head 15 based on the recording current generated from the PBW pattern after the transformation of the transform target pattern is performed, since a large current is not required for the initial polarity inversion, by transforming the leading portion of the transform target pattern into the [1T, 1T] leading pattern, driving with the minimum necessary current enables suppression of the influence on the NLTS, adjacent erasure, and the like. In other words, in the case where the pattern length of the immediately preceding data pattern is 2T, when the write processing of the disk 10 by the head 15 based on the recording current generated from the PBW pattern after the transformation of the transform target pattern is performed, since a large current is not required for the initial polarity inversion, by transforming the leading pattern of the transform target pattern into the 1T data pattern, driving with the minimum necessary current enables suppression of the influence on the NLTS, adjacent erasure, and the like.

[0055] For example, the PBW write data generator 604 transforms the leading pattern of the transform target pattern into the [2T, 1T] leading pattern in the case where the pattern length of the immediately preceding data pattern is 1T. In addition, the PBW write data generator 604 transforms the leading pattern of the transform target pattern into the [1T, 1T] leading pattern in the case where the pattern length of the immediately preceding data pattern is 2T and 3T.

[0056] For example, the PBW write data generator 604 transforms the leading pattern of the transform target pattern into the [2T, 1T] leading pattern in the case where the pattern length of the immediately preceding data pattern is 1T. In addition, the PBW write data generator 604 transforms the leading pattern of the transform target pattern into the [1T, 1T] leading pattern in the case where the pattern length of the immediately preceding data pattern is 2T and 3T.

[0057] Figure 5 is a graph showing an example of the influence on the recording quality resulting from the combination of the immediately preceding data pattern and the leading adjacent pattern of the transform target pattern. In Figure 5 the vertical axis represents the gain in BER, and the horizontal axis represents the pattern length of the immediately preceding data pattern. Figure 5The horizontal axis represents the pattern lengths 1T, 2T, and 3T of the immediately preceding data pattern. Figure 5 The BER gain when the leading graph of the conversion object graph is converted into a continuous [2T, 1T] leading graph (PBW graph) (hereinafter sometimes referred to as the BER gain corresponding to the [2T, 1T] leading graph) and the BER gain when the leading graph of the conversion object graph is converted into a continuous [2T, 2T] leading graph (PBW graph) (hereinafter sometimes referred to as the BER gain corresponding to the [2T, 2T] leading graph) are shown. Figure 5 In the figure, the BER gain corresponding to the pattern starting with [2T, 1T] is represented by a rectangular shape with a rightward descending slash, and the BER gain corresponding to the pattern starting with [2T, 2T] is represented by a hollow rectangular shape. The pattern starting with [2T, 1T] corresponds to a data pattern containing a first adjacent pattern of a current zero interval of 1T immediately following the first pattern of a pulse-like pattern of 2T in length. For example, written data containing a pattern starting with [2T, 1T] corresponds to a data sequence such as [11011000]. The pattern starting with [2T, 2T] corresponds to a data pattern containing a first adjacent pattern of a current zero interval of 2T in length immediately following the first pattern of a pulse-like pattern of 2T in length. For example, written data containing a pattern starting with [2T, 2T] corresponds to a data sequence such as [11001100].

[0058] exist Figure 6 In the example shown, when the pattern length of the immediately preceding data pattern is 1T, 2T, or 3T, the BER gain corresponding to the pattern starting with [2T, 2T] is greater than the BER gain corresponding to the pattern starting with [2T, 1T]. In other words, when the pattern length of the immediately preceding data pattern is 1T, 2T, or 3T, converting the starting pattern of the conversion target pattern to a pattern starting with [2T, 1T] improves the recording quality compared to converting the starting pattern of the conversion target pattern to a pattern starting with [2T, 2T]. Figure 6 As can be seen in the example shown, regardless of the immediately preceding data pattern, converting to the first adjacent pattern with a pattern length of 2T further degrades the recording quality. Therefore, the recording quality can be improved by treating the [2T, 1T] data pattern as a set and repeating this set of data patterns.

[0059] For example, the PBW write data generator 604 converts a data pattern (hereinafter sometimes referred to as an intermediate pattern) that follows or is immediately after the leading pattern of the conversion target pattern (or in the middle of the conversion target pattern) into a data pattern that is a repetition of the [2T, 1T] data pattern. Hereinafter, the data pattern that follows the leading pattern of the predetermined write data may also be referred to as an intermediate pattern.

[0060] Figure 6 is a graph indicating an example of the influence on the recording quality resulting from the combination of the last pattern of the pattern to be transformed and the immediately preceding data pattern. In Figure 6 , the vertical axis indicates the gain in BER, and the horizontal axis indicates the pattern length of the immediately preceding data pattern. Figure 6 The horizontal axis of indicates the pattern length 1T, 2T, and 3T of the immediately preceding data pattern. Figure 6 shows the gain in BER (hereinafter, also referred to as the gain in BER corresponding to the 3T last pattern) in the case where the data pattern of the last portion of the pattern to be transformed (hereinafter, also referred to as the last pattern) is transformed into a 3T data pattern, and the gain in BER (hereinafter, also referred to as the gain in BER corresponding to the 4T last pattern) in the case where the last pattern of the pattern to be transformed is transformed into a 4T data pattern (PBW pattern). Hereinafter, the "nT data pattern of the last portion of the pattern to be transformed" is also referred to as the "nT last pattern". In Figure 7 , the gain in BER corresponding to the 3T last pattern is indicated by the rectangular shape of the sloping line descending to the right, and the gain in BER corresponding to the 4T last pattern is indicated by the hollow rectangular shape. Hereinafter, the "data pattern after the intermediate pattern of the pattern to be transformed" is also referred to as the "last pattern". The intermediate pattern is located between the beginning pattern and the last pattern.

[0061] In the example shown in Figure 7 , in the case where the pattern length of the immediately preceding data pattern is 1T, 2T, and 3T, the gain in BER corresponding to the 3T last pattern is greater than the gain in BER corresponding to the 4T last pattern. That is, in the case where the pattern length of the immediately preceding data pattern is 1T, 2T, and 3T, transforming the last pattern of the pattern to be transformed into a 4T data pattern results in a greater deterioration in recording quality than transforming it into a 3T data pattern. In Figure 7 , it is known that the last pattern transformed into a pattern length of 4T deteriorates the recording quality regardless of the immediately preceding data pattern. Therefore, it is desirable to set the pattern length of the last pattern of the pattern to be transformed to 1T, 2T, or 3T.

[0062] For example, the PBW write data generator 604 transforms the last pattern of the pattern to be transformed into a 1T, 2T, or 3T data pattern.

[0063] Figure 3 is a schematic view indicating an example of the pattern transformation table TB1 of the present embodiment. Figure 7The graph conversion table TB1 includes: a graph to be converted, a PBW graph group for converting a graph to be converted whose graph length is 1T (hereinafter sometimes referred to as PBW graph group 1), and a PBW graph group for converting a graph to be converted whose graph length is 2T or 3T (hereinafter sometimes referred to as PBW graph group 2). Figure 7 In the pattern conversion table TB1, the conversion target patterns include: 1T, 2T, 3T, 4T, 5T, 6T, 7T, 8T, 9T, 10T, 11T, 12T, 13T, 14T, 15T, and 16T. PBW pattern group 1 includes: PBW pattern and NRZ (Non-Return to Zero). PBW pattern group 2 includes: PBW pattern and NRZ. Pattern conversion table TB1 is maintained in Figure 8 The table management unit 603 is shown. In addition, the pattern conversion table TB1 may be provided as a table for the PBW pattern group 1 and a table for the PBW pattern group 2.

[0064] exist Figure 8 In the illustrated example, based on the pattern conversion table TB1, the PBW write data generator 604 converts the leading and intermediate patterns of a conversion target pattern with a pattern length of 4T or longer into data patterns that repeatedly form a [2T, 1T] data pattern, if the pattern length of the immediately preceding data pattern is 1T. Furthermore, based on the pattern conversion table TB1, the PBW write data generator 604 converts the leading and intermediate patterns of a conversion target pattern with a pattern length of 4T or longer into data patterns that repeatedly form a [2T, 1T] data pattern, and converts the final pattern of the conversion target pattern into a 1T, 2T, or 3T data pattern.

[0065] exist Figure 8 In the illustrated example, based on the pattern conversion table TB1, the PBW write data generator 604 converts the leading pattern of a conversion target pattern with a pattern length of 4T or longer into a data pattern obtained by converting the leading pattern of the leading PBW pattern of PBW pattern group 1 into a 1T data pattern, and then converts the trailing pattern of the conversion target pattern into a 1T, 2T, or 3T data pattern. Furthermore, based on the pattern conversion table TB1, the PBW write data generator 604 converts the leading pattern of a conversion target pattern with a pattern length of 4T or longer into a [1T, 1T] data pattern, converts the middle pattern of the conversion target pattern into a data pattern consisting of a repetition of [2T, 1T] data patterns, and then converts the trailing pattern of the conversion target pattern into a 1T, 2T, or 3T data pattern.

[0066] Figure 3 is a schematic view showing an example of a pattern conversion table TB2 of the present embodiment. Figure 8 The pattern conversion table TB2 of the present embodiment includes a conversion target pattern, a PBW pattern group 1, and a PBW pattern group 2. In the pattern conversion table TB2 of the present embodiment, the conversion target pattern includes 1T, 2T, 3T, 4T, 5T, 6T, 7T, 8T, 9T, 10T, 11T, 12T, 13T, 14T, 15T, and 16T. The PBW pattern group 1 includes PBW patterns and NRZ. The PBW pattern group 2 includes PBW patterns and NRZ. The pattern conversion table TB2 is held in the table management section 603 shown in Fig. 6. Further, the pattern conversion table TB2 can be provided as a table for the PBW pattern group 1 and a table for the PBW pattern group 2, respectively. Figure 8 In the pattern conversion table TB2 of the present embodiment, the conversion target pattern includes 1T, 2T, 3T, 4T, 5T, 6T, 7T, 8T, 9T, 10T, 11T, 12T, 13T, 14T, 15T, and 16T. The PBW pattern group 1 includes PBW patterns and NRZ. The PBW pattern group 2 includes PBW patterns and NRZ. The pattern conversion table TB2 is held in the table management section 603 shown in Fig. 6. Further, the pattern conversion table TB2 can be provided as a table for the PBW pattern group 1 and a table for the PBW pattern group 2, respectively. Figure 9A In the pattern conversion table TB2 of the present embodiment, the conversion target pattern includes 1T, 2T, 3T, 4T, 5T, 6T, 7T, 8T, 9T, 10T, 11T, 12T, 13T, 14T, 15T, and 16T. The PBW pattern group 1 includes PBW patterns and NRZ. The PBW pattern group 2 includes PBW patterns and NRZ. The pattern conversion table TB2 is held in the table management section 603 shown in Fig. 6. Further, the pattern conversion table TB2 can be provided as a table for the PBW pattern group 1 and a table for the PBW pattern group 2, respectively.

[0067] In the example shown in Fig. 7, the PBW write data generator 604 converts, based on the pattern conversion table TB2, the beginning pattern and the middle pattern of the conversion target pattern whose pattern length is 4T or more to the data pattern of [2T, 1T] repeated, in the case where the pattern length of the immediately preceding data pattern is 1T. Further, the PBW write data generator 604 converts, based on the pattern conversion table TB2, the beginning pattern of the conversion target pattern whose pattern length is 4T or more to the data pattern of [2T, 1T] repeated, in the case where the pattern length of the immediately preceding data pattern is 1T, and converts the last pattern of the conversion target pattern to the data pattern of 1T, 2T, or 3T. Figure 9A In the example shown in Fig. 7, the PBW write data generator 604 converts, based on the pattern conversion table TB2, the beginning pattern and the middle pattern of the conversion target pattern whose pattern length is 4T or more to the data pattern of [2T, 1T] repeated, in the case where the pattern length of the immediately preceding data pattern is 1T. Further, the PBW write data generator 604 converts, based on the pattern conversion table TB2, the beginning pattern of the conversion target pattern whose pattern length is 4T or more to the data pattern of [2T, 1T] repeated, in the case where the pattern length of the immediately preceding data pattern is 1T, and converts the last pattern of the conversion target pattern to the data pattern of 1T, 2T, or 3T.

[0068] Figure 9A In the example shown in Fig. 7, the PBW write data generator 604 converts, based on the pattern conversion table TB2, the beginning pattern and the middle pattern of the conversion target pattern whose pattern length is 4T or more to the data pattern of [2T, 1T] repeated, in the case where the pattern length of the immediately preceding data pattern is 1T. Further, the PBW write data generator 604 converts, based on the pattern conversion table TB2, the beginning pattern of the conversion target pattern whose pattern length is 4T or more to the data pattern of [2T, 1T] repeated, in the case where the pattern length of the immediately preceding data pattern is 1T, and converts the last pattern of the conversion target pattern to the data pattern of 1T, 2T, or 3T.

[0069] The mask signal generator 605 generates a mask signal that masks pseudo inversion. In other words, the mask signal generator 605 generates a mask signal that indicates pseudo inversion. The mask signal generator 605 generates the mask signal based on the PBW write data input from the PBW write data generator 604. The mask signal generator 605 is connected to the PBW write data generator 604 and the mask signal controller 301. The mask signal generator 605 outputs the generated mask signal to the mask signal controller 301.

[0070] ​The PECL 606 generates a voltage (or a current) corresponding to the write data. In other words, the PECL 606 generates a voltage (or a current) waveform corresponding to the write data. For example, the PECL 606 generates a voltage (or a current) corresponding to the PBW write data input from the PBW write data generator 604. In other words, the PECL 606 generates a voltage (or a current) waveform corresponding to the PBW write data input from the PBW write data generator 604. The PECL 606 is connected to the PBW write data generator 604 and the write driver 302. The PECL 606 outputs the generated voltage (or a current) corresponding to the PBW write data to the write driver 302. In other words, the PECL 606 outputs the generated voltage (or a current) waveform corresponding to the PBW write data to the write driver 302.

[0071] The shield signal controller 301 controls the shield signal. The shield signal controller 301 controls the shield signal input from the shield signal generator 605. The shield signal controller 301 is connected to the shield signal generator 606 and the write driver 302. The shield signal controller 301 outputs the controlled shield signal to the write driver 302.

[0072] The write driver 302 generates a recording current. The write driver 302 generates a recording current based on the voltage (or a current) corresponding to the PBW write data input from the PECL 606 and the shield signal input from the shield signal controller 301. The write driver 302 generates a recording current in which the polarity of the pseudo inversion within the voltage (or a current) corresponding to the PBW write data is not inverted according to the shield signal. In other words, the write driver 302 generates a recording current in which the pseudo inversion within the voltage (or a current) corresponding to the PBW write data is shielded according to the shield signal. The write driver 302 is connected to the PECL 606 and the shield signal controller 301. The write driver 302 outputs the recording current to the head 15 (write head 15W).

[0073] Figure 9A is a schematic view showing an example of a write data conversion method of the present embodiment. In Figure 9A , the horizontal axis represents time t. In Figure 9A , the horizontal axis, the leading end side of the arrow of time t is sometimes referred to as the rear side or the right side, and the side opposite to the leading end of the arrow of time t is sometimes referred to as the front side or the left side. Figure 9A The base write data, the PBW write data, the shield signal, and the recording current are shown. The base write data and the PBW write data rise at High (H) and fall at Low (L). The shield signal rises at the position of the pseudo inversion and falls at the position other than the position of the pseudo inversion. The recording current rises to the positive (+) side and rises to the negative (-) side.

[0074] In Figure 9B In the example shown, the write system WSY transforms the transform target pattern of 4T or more in the base write data into a PBW pattern based on the pattern transform table TB1. For example, the write system WSY transforms the data pattern of 4T whose pattern length is 2T in the immediately preceding data pattern in the front side of the base write data into a [1T, 1T, 2T] PBW pattern based on the pattern transform table TB1. The write system WSY transforms the data pattern of 5T whose pattern length is 1T in the immediately preceding data pattern in the front side of the base write data into a [2T, 1T, 2T] PBW pattern based on the pattern transform table TB1. The write system WSY transforms the data pattern of 4T whose pattern length is 1T in the immediately preceding data pattern in the rear side of the base write data into a [2T, 1T, 1T] PBW pattern based on the pattern transform table TB1. The write system WSY transforms the data pattern of 4T whose pattern length is 2T in the immediately preceding data pattern in the rear side of the base write data into a [1T, 1T, 2T] PBW pattern based on the pattern transform table TB1.

[0075] In Figure 9A In the example shown, the write system WSY transforms the transform target pattern of 4T or more in the base write data into a PBW pattern based on the pattern transform table TB1, as described above, and transforms the base write data into a PBW write data.

[0076] In Figure 9B In the example shown, the write system WSY generates a recording current based on the PBW write data and the mask signal. The write system WSY generates the recording current from the PBW write data based on the mask signal so that the position of the pseudo-inversion does not undergo a polarity inversion.

[0077] Figure 9A is Figure 9B An enlarged view of a part of the base write data, a part of the PBW write data, a part of the mask signal, and a part of the recording current shown in Figure 9B Corresponding to Figure 9B The transform method of the write data is described in detail using Figure 9B

[0078] In Figure 10 In the example shown, the base write data is composed of data patterns of 1T, 1T, 5T, and 2T. The write system WSY transforms the data pattern of 5T whose pattern length is 1T in the immediately preceding data pattern into a [2T, 1T, 2T] PBW pattern based on the pattern transform table TB1. ​ In the example shown, the base write data is composed of data patterns of 1T, 1T, 5T, and 2T. The write system WSY transforms the data pattern of 5T whose pattern length is 1T in the immediately preceding data pattern into a [2T, 1T, 2T] PBW pattern based on the pattern transform table TB1.

[0079] In ​ ​In the example shown, the write system WSY generates a recording current from the write data of the [2T, 1T, 2T] PBW pattern based on the write data of the [2T, 1T, 2T] PBW pattern and the mask signal such that the 1T data pattern between the 2T data pattern and the 2T data pattern corresponding to the position of the pseudo-inversion of the [2T, 1T, 2T] PBW pattern does not undergo a polarity inversion.

[0080] ​ is a flowchart showing an example of the method of generating write data of the present embodiment.

[0081] The disk device 1 transforms the nth data pattern of the base write data (the nth transformation target pattern) (B1001), and determines whether n = 1 (B1002). In the case where it is determined that n = 1 (B1002: Yes), the disk device 1 transforms the transformation target pattern based on the PBW pattern group 1 (B1003), and sets n = n + 1 to proceed to the process of B1001. In the case where it is determined that n ≠ 1 (B1002: No), the disk device 1 determines whether n < max or n = max (B1004).

[0082] In the case where it is determined that n < max (B1005: Yes), the disk device 1 determines whether the pattern length of the immediately preceding PBW data pattern is 1T (B1005). In the case where it is determined that the pattern length of the immediately preceding PBW data pattern is 1T (B1005: Yes), the disk device 1 transforms the transformation target pattern based on the PBW pattern group 1 (B1006), and sets n = n + 1 to proceed to the process of B001. In the case where it is determined that the pattern length of the immediately preceding PBW data pattern is not 1T (B1005: No), the disk device 1 transforms the transformation target pattern based on the PBW pattern group 2 (B1007), and sets n = n + 1 to proceed to the process of B001.

[0083] In the case where it is determined that n = max (B1005: No), the disk device 1 generates a write current based on the PBW write data and the mask signal (B1008), and ends the process.

[0084] According to the present embodiment, the disk device 1 converts, based on the pattern conversion table TB1, the beginning pattern of a conversion target pattern equivalent to a data pattern of 4T or more whose pattern length is 1T immediately before the data pattern into a [2T, 1T] data pattern, converts the middle pattern of the conversion target pattern into a data pattern in which a [2T, 1T] data pattern is repeated, and converts the last pattern of the conversion target pattern into a 1T, 2T, or 3T data pattern. The disk device 1 converts, based on the pattern conversion table TB1, the beginning pattern of a conversion target pattern equivalent to a data pattern of 4T or more whose pattern length is 2T or 3T immediately before the data pattern into a [1T, 1T] data pattern, converts the middle pattern of the conversion target pattern into a data pattern in which a [2T, 1T] data pattern is repeated, and converts the last pattern of the conversion target pattern into a 1T, 2T, or 3T data pattern. The disk device 1 converts, based on the pattern conversion table TB2, the beginning pattern of a conversion target pattern equivalent to a data pattern of 4T or more whose pattern length is 1T immediately before the data pattern into a [2T, 1T] data pattern, converts the middle pattern of the conversion target pattern into a data pattern in which a [2T, 1T] data pattern is repeated, and converts the last pattern of the conversion target pattern into a 1T, 2T, or 3T data pattern. The disk device 1 converts, based on the pattern conversion table TB2, the beginning pattern of a conversion target pattern equivalent to a data pattern of 4T or more whose pattern length is 2T or 3T immediately before the data pattern into a [1T, 1T] data pattern or a [2T, 1T] data pattern, converts the middle pattern of the conversion target pattern into a data pattern in which a [2T, 1T] data pattern is repeated, and converts the last pattern of the conversion target pattern into a 2T or 3T data pattern. The disk device 1 converts, based on the pattern conversion table, the base write data into the PBW write data in accordance with the data pattern immediately before the data pattern. Thus, the disk device 1 can improve the effect of improvement of BER achieved by the write processing of the PBW method. Thus, the disk device 1 can improve reliability.

[0085] The embodiments have been described as examples, and are not intended to limit the scope of the application. The new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the application. The embodiments and modifications thereof are included in the scope and spirit of the application, and are included in the scope of the application recited in the claims and the scope equivalent thereto.

[0086] Label Explanation

[0087] 1…disk device, 10…disk, 10a…user data area, 10b…system area, 12…spindle motor (SPM), 13…arm, 14…voice coil motor (VCM), 15…head, 15W…write head, 15R…read head, 20…drive IC, 30…head amplifier IC, 40…microprocessor (MPU), 50…hard disk controller (HDC), 60…read / write (R / W) channel, 70…volatile memory, 80…nonvolatile memory, 90…buffer memory, 100…host system (host), 130…system controller.

Claims

1. A magnetic disk device comprising: plate; a head for writing data to and reading data from the disk; a preamplifier that generates a recording current corresponding to data written by the head to the disk; and The controller converts the first data pattern into a different data pattern based on a pattern length nT of a second data pattern immediately preceding the first data pattern within the first write data. The different data pattern includes a pseudo polarity reversal that does not cause a polarity reversal when converting to the recording current. Here, n is a positive integer, 1T corresponds to a unit length of the pattern length, and corresponds to a 1T-bit data pattern in an NRT (non-return-to-zero) encoding method.

2. The magnetic disk device according to claim 1, When the pattern length of the PBW pattern obtained by converting the second data pattern is 1T, the controller converts the first data pattern into a third data pattern including a continuous 2T+1T data pattern at the beginning.

3. The magnetic disk device according to claim 2, The controller converts the first data pattern into the third data pattern in which the middle portion after the leading portion is formed by repeating a continuous 2T+1T data pattern.

4. The magnetic disk device according to claim 3, The controller converts the first data pattern into the third data pattern including a 1T, 2T, or 3T data pattern at the end portion following the middle portion.

5. The magnetic disk device according to claim 1, When the pattern length of the PBW pattern obtained by converting the second data pattern is other than 1T, the controller converts the first data pattern into a fourth data pattern including a continuous 1T+1T data pattern at the beginning.

6. The magnetic disk device according to claim 5, The controller converts the first data pattern into the fourth data pattern in which the middle portion after the leading portion is formed by repeating a continuous 2T+1T data pattern.

7. The magnetic disk device according to claim 6, The controller converts the first data pattern into the fourth data pattern including a 1T, 2T, or 3T data pattern at the end portion following the middle portion.

8. The magnetic disk device according to any one of claims 1 to 7, The controller has a table for converting the first data pattern into a different data pattern according to the pattern length nT of the second data pattern, wherein the different data pattern includes a pseudo polarity reversal that does not cause polarity reversal when converted to the recording current. Here, n is a positive integer, 1T is equivalent to the unit length of the pattern length, and 1T is equivalent to a 1T-bit data pattern in the non-return-to-zero encoding method.

9. A magnetic disk device comprising: plate; a head for writing data to and reading data from the disk; a preamplifier that generates a recording current corresponding to data written by the head to the disk; and The controller converts the first data pattern in the first write data into a plurality of data patterns having different positions of pseudo polarity inversion that does not cause polarity inversion when converting to the recording current.

10. A method for generating write data, applicable to a magnetic disk device, the magnetic disk device comprising: a disk; a head for writing data to the disk and reading data from the disk; and a preamplifier for generating a recording current corresponding to the data written by the head to the disk, In the generation method, the first data pattern in the first write data is converted into a plurality of data patterns having different positions of pseudo polarity inversion that does not cause polarity inversion when converted to the recording current.

Images