Magnetic disk device

Abstract

The embodiment of the invention relates to a magnetic disk device of a multi-stage micro-actuator system. A magnetic disk device according to an embodiment includes: a plurality of headers capable of reading and writing data independently at the same time; microactuators, each of which is provided with one or more of the microactuators in each of the heads, and each of the microactuators can be independently controlled; a VCM that controls each of the heads; a simultaneous in-orbit head determination unit that determines a final set, which is a set of heads that are simultaneously in orbit, by using at least the amount of displacement of the microactuators; a VCM target position determination unit that determines the target position of the VCM when the VCM is in orbit at the same time; the VCM control switching part is used for switching the VCM controller when the VCM controller is in orbit at the same time; and an MA control switching unit that switches the controller of the microactuator with respect to each of the simultaneous on-orbit heads determined by the simultaneous on-orbit head determination unit.

Description

[0001] This application claims the benefit of priority based on Japanese Patent Application No. 2024-041925 (filing date: March 18, 2024), the entire contents of which are incorporated herein by reference. Technical Field

[0002] An embodiment of the present invention relates to a magnetic disk device having a multi-stage microactuator system. Background Art

[0003] A magnetic disk drive with a multi-stage microactuator system includes multiple microactuators in one head. The input voltages to the multiple microactuators can be set independently, but applying a voltage with a large absolute value may cause device degradation. Summary of the Invention

[0004] The magnetic disk drive of this embodiment includes: a plurality of heads capable of independently and simultaneously reading and writing data; microactuators, each head having at least one of the microactuators, all of which are independently controllable; a VCM for controlling each of the heads; a simultaneously-on-track head determination unit for determining a final set of heads simultaneously on-track using at least a control input (microactuator control voltage) or a displacement amount of the microactuators; a VCM target position determination unit for determining a target position of the VCM when simultaneously on-track; a VCM control switching unit for switching VCM controllers when simultaneously on-track; and an MA control switching unit for switching microactuator controllers for each head determined to be simultaneously on-track by the simultaneously-on-track head determination unit.

[0005] According to the embodiment of the present invention, it is possible to provide a magnetic disk device having a multi-stage actuator system that takes voltage constraints of microactuators into consideration. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 This is a diagram showing the configuration of a magnetic disk device according to an embodiment.

[0007] Figure 2 Schematic diagram showing an example of a multi-stage microactuator of a magnetic disk device according to an embodiment.

[0008] Figure 3 This is an example of a block diagram of a servo control unit and related parts in the magnetic disk device according to the embodiment, and focuses on the case of a single head including a plurality of microactuators.

[0009] Figure 4 This is an example of a block diagram of a controller that controls the VCM and microactuators in the magnetic disk device according to the embodiment, and is an example that takes into account the case of multiple heads and multiple microactuators.

[0010] Figure 5This is an example of a block diagram of a controller that controls the VCM and microactuators in the magnetic disk device according to the embodiment, and focuses on the case of one head i including a plurality of microactuators.

[0011] Figure 6 This is a first flowchart showing processing operations when the magnetic disk device according to the first embodiment controls a plurality of heads.

[0012] Figure 7 This is a second flowchart showing processing operations when the magnetic disk device according to the first embodiment controls a plurality of heads.

[0013] Figure 8 This is a schematic diagram for explaining a method in which the magnetic disk device according to the first embodiment selects a head to be processed from a plurality of heads.

[0014] Figure 9 This is a flowchart showing processing operations when the magnetic disk device according to the second embodiment controls a plurality of heads.

[0015] Figure 10 This is a schematic diagram for explaining a method in which the magnetic disk device according to the second embodiment selects a head to be processed from a plurality of heads.

[0016] Figure 11 This is a flowchart showing processing operations when the magnetic disk device according to the third embodiment controls a plurality of heads.

[0017] Figure 12 This is a schematic diagram for explaining a method in which the magnetic disk device according to the third embodiment selects a head to be processed from a plurality of heads.

[0018] Description of Reference Numerals

[0019] 1…Disk device, 2…Host system, 10…HDA, 11…Disk, 12…SPM, 13…VCM, 14…Pivot, 15…Arm, 16…Suspension, 17…Microactuator, 18…Slider, 19…Head, 20…Driver IC, 30…Head amplifier IC, 40…R / W channel, 50…HDC, 60…Main controller, 61…Read / write control unit, 62…Servo control unit, 63…Control switching unit, 70…Volatile memory, 80…Non-volatile memory, 631…Simultaneous on-track head determination unit, 632…VCM control switching unit, 633…MA control switching unit, 6311…VCM target position determination unit. DETAILED DESCRIPTION

[0020] Hereinafter, embodiments will be described with reference to the accompanying drawings. However, the accompanying drawings are merely examples and do not limit the scope of the invention.

[0021] (First embodiment)

[0022] In this embodiment, an example of a magnetic disk device (Hard Disk Drive: HDD) is shown as follows: in a magnetic disk device in which one head has multiple microactuators (hereinafter sometimes referred to as MAs) and the voltages of all MAs can be independently set, multiple heads perform reading and writing simultaneously on track.

[0023] Applying a voltage with a large absolute value to an MA can sometimes cause component degradation. Therefore, when multiple heads are simultaneously on track, the magnetic disk drive of this embodiment controls the multiple heads by simultaneously considering the input voltages to the multiple MAs that control the multiple heads. More specifically, the input voltage to each MA is controlled by considering the voltage constraints (maximum voltage that can be input) of each MA, allowing the multiple heads to perform simultaneous reading and writing.

[0024] Figure 1 This is a diagram showing the configuration of a magnetic disk device according to an embodiment.

[0025] The disk device 1 is a storage device that includes a disk 11 (hereinafter sometimes simply referred to as a disk) for reading and writing data. It includes a processor, such as a microprocessor, that has computer functions such as arithmetic processing, and various memories. The disk device 1 outputs data to the host system 2 based on commands received from the connected host system 2 or writes data input from the host system 2 to the disk 11. Figure 1 In FIG, only one actuator and head are shown, but the magnetic disk device 1 includes a plurality of disks and heads as will be described later.

[0026] The host system 2, such as a personal computer, outputs a read command, which is a command to read data from the disk 11, and a write command, which is a command to write data to the disk, to the magnetic disk device 1. Furthermore, the host system 2 may output information about a sampling period of servo information contained on the disk 11 of the magnetic disk device 1 and specify this information to the magnetic disk device 1.

[0027] The HDA 10 is called a head disk assembly, and the disk 11, the spindle motor (hereinafter sometimes referred to as SPM) 12, the arm 15 carrying the head 19, the voice coil motor (hereinafter sometimes referred to as VCM) 13, etc. are housed in a housing. Figure 1 The HDA 10 shows an example in which one disk 11 and one head 19 are provided, but more than one may be provided for each.

[0028] The disk 11 is a disk-shaped, magnetic, rotating disk storage medium. Within the data area where data can be written (sometimes referred to as "write"), there are allocated a user data area that can be used by the user and a system area for writing information required for system management. Hereinafter, the direction perpendicular to the radial direction of the disk 11 will be referred to as the circumferential direction. The disk 11 is mounted on the spindle motor 12 and is rotated by the drive of the spindle motor 12. The magnetic disk device 1 includes a plurality of disks 11. Therefore, for example, the iDth (iD is a natural number) disk is represented as disk 11[iD]. iD is used as an identification number to identify the iDth disk 11 among the plurality of disks 11, but iD can also be used as a variable and interpreted as any disk 11 among the plurality of disks 11.

[0029] The disk 11 is provided with a plurality of tracks. Figure 1 While three tracks TR1, TR2, and TR3 (referred to as tracks TR unless otherwise specified) are shown as examples in the figure, multiple tracks are concentrically arranged around the spindle motor 12 in the data area. When reading or writing data on the disk 11, the head 19 is moved to the track TR containing the data to be read or written (sometimes referred to as target data) through seek control, tracking control, etc., and the head 19 reads or writes the data. The track TR containing the target data is sometimes referred to as the target track.

[0030] In addition, servo information is written on the disk 11 for use in detecting the position of the head 19. The servo information is set at a predetermined position (called a servo area) in the circumferential direction of the disk 11. The servo information is general in nature and its detailed description is omitted. Figure 1 In the example shown, three servo areas SVA1, SVA2, and SVA3 (referred to as servo areas SVA unless otherwise specified) are shown as examples of servo areas. However, generally, servo areas SVA are provided at equal intervals along the entire circumference of the disk 11, and servo information is written to the servo areas SVA of each track TR. The magnetic disk device 1 can detect the current position of the head 19 (head position) using the servo information read by the head 19.

[0031] The spindle motor 12 (SPM12) is a support for the disk 11 and is provided on a magnetic disk housing, etc. The disk 11 rotates when the spindle motor 12 rotates.

[0032] The VCM 13 is a voice coil motor type actuator for operating the arm 15 and the like. The VCM 13 controls the operation of the arm 15 and the like based on an input current or voltage.

[0033] The pivot shaft 14 is a bearing for supporting the arm 15 and the like and performing a rotational operation.

[0034] The arm 15 supports the slider 18 and the head 19 and transmits power from the VCM 13 to the head 19, thereby moving the head 19 to the target track TR. The magnetic disk drive 1 includes a plurality of arms 15 corresponding to the plurality of heads 19. Therefore, for example, the iA-th (iA is a natural number) arm is represented as arm 15[iA].

[0035] A microactuator 17 is connected to the suspension 16. The magnetic disk drive 1 includes a plurality of suspensions 16 corresponding to a plurality of heads 19. Therefore, for example, the suspension corresponding to the i-th (i is a natural number) head 19[i] is represented as suspension 16[i]. "i" represents the number associated with the head 19. A suspension 16 is provided for each head 19. Therefore, the number "i" of the connected head 19 is used as the number associated with the suspension 16.

[0036] The microactuator 17 (sometimes referred to as the MA17) performs high-precision position adjustment, such as tracking control, for the head 19 based on the input current or voltage. The microactuator 17 has a general function, and detailed description is omitted. It performs fine adjustments to the position of the head 19 during stabilization (settling) after seek control, and tracking control of the target track after seek control. Stabilization refers to a state in which, after the movement of the head 19 based on seek control, the positioning error relative to the target track, including the influence of the vibration of the head 19 due to seek control, converges to below a certain threshold, for example. After the vibration of the head 19 has converged to a sufficiently small level due to stabilization, data read and write control and tracking control are performed.

[0037] The magnetic disk device 1 of this embodiment has one or more MA17s for controlling a plurality of heads 19 on each head, and therefore, for example, all MAs for controlling the i-th head 19 are represented as MA17[i] using i representing the number of the head 19. Moreover, the magnetic disk device 1 of this embodiment has a plurality of MA17s corresponding to one head 19, and therefore, for example, the j-th (j is a natural number) MA for controlling the i-th head 19 is represented as MA17[i][j]. In addition, the j-th MA is represented as Figure 1 As shown, there is a case where the piezoelectric elements are mounted in pairs on the left and right sides of the head 19. In order to indicate this, indexes such as ja and jb are given. Figure 1 In FIG. 1 , the piezoelectric elements constituting the second MA corresponding to the head 19[i] that reads and writes to the disk 11 are represented as MA17[i][2a] and MA17[i][2b], and are shown as a pair constituting MA17[i][2].

[0038] The head 19 is mounted on the slider 18. The magnetic disk device 1 includes a plurality of sliders 18 corresponding to the plurality of heads 19. Therefore, for example, a slider corresponding to the i-th head 19[i] is represented as slider 18[i].

[0039] The head 19 is a part that writes data to the disk 11 or reads data recorded on the data tracks of the disk 11. The magnetic disk device 1 has multiple heads 19 corresponding to the multiple disks 11. Therefore, to represent each head 19, for example, the i-th (i is a natural number) head is represented as head 19[i]. i is used as an identification number to identify a head 19 among the multiple heads 19[i]. However, i can also be used as a variable and interpreted as any head 19 among the multiple heads 19. In addition, when making a special distinction, the head that writes data to the disk 11 is called a write head 19W, and the head that reads data recorded on the data tracks of the disk 11 is called a read head 19R.

[0040] The driver IC 20 outputs a current or a voltage for driving and controlling the SPM 12 , the VCM 13 , the MA 17 , and the like in accordance with control from the HDC 50 , the servo control unit 62 , and the like.

[0041] The head amplifier IC 30 includes a read amplifier and a write driver. The read amplifier amplifies the read signal from the disk 11 and outputs it to the R / W channel 40. The write driver outputs a write current corresponding to the signal output from the R / W channel 40 to the head 19. The magnetic disk drive 1 includes head amplifier ICs 30 corresponding to multiple heads 19. Therefore, for example, the head amplifier IC corresponding to the i-th head 19[i] is represented as head amplifier IC 30[i].

[0042] The R / W channel 40 controls the head amplifier IC 30, such as reading data from and writing data to the disk 11, based on instructions from the HDC 50, the main controller 60, and the like. The R / W channel 40 receives a read data signal from the head amplifier IC 30 and extracts the read data, or generates a write data signal based on commanded write data and outputs it to the head amplifier IC 30. The R / W channel 40 also measures the signal quality of the read data received from the head amplifier IC 30. The R / W channel 40 can also extract position information of the head 19 based on a servo information signal received from the head amplifier IC 30.

[0043] The HDC 50 serves as an interface between the disk drive 1 and the host system 2 and is a hard disk controller that controls various components of the disk drive 1. The HDC 50 may be comprised of a processing device (processor) such as a CPU, other processing device functions, an IC chip with various memories, a system LSI, an FPGA, or the like. Various processes performed by the HDC 50 may be executed by software (including firmware), hardware, or a combination of both.

[0044] The HDC 50 receives commands such as commands to write data to the disk 11 and commands to read data from the disk 11 from the host system 2. Based on the received commands, the HDC 50 controls various components of the magnetic disk device 1 or transfers data between the host system 2 and the R / W channel 40. The HDC 50 can also control the reading and writing of data from and to the volatile memory 70 and the nonvolatile memory 80.

[0045] The main controller 60 is a main controller that controls various components of the magnetic disk drive 1. It can be composed of a processing device (processor) such as a CPU or microprocessor that has computer functions such as arithmetic processing, other processing device functions, various memories, etc., an IC chip, a system LSI, an FPGA, etc. Various processes performed by the main controller 60 can be executed by software (including firmware, etc.) programs, or can be implemented as hardware, or a combination of software and hardware.

[0046] The read / write control unit 61 selects a storage destination for write data (e.g., information on the data sector or track of the disk 11) based on commands received from the host system 2 and controls the writing of data to the disk 11. Based on commands received from the host system 2, the read / write control unit 61 notifies the servo control unit 62 and other units of the storage destination for read data (e.g., information on the data sector or track of the disk 11) and operates the head 19 to control the reading of data from the disk 11.

[0047] The servo control unit 62 controls the head 19 based on, for example, a command received from the host system 2. For example, the servo control unit 62 controls the head 19 in order to move the head 19[i] to a target position (target track). i The VCM 13 is controlled via the driver IC 20 to perform seek control and tracking control. In addition, the servo control unit 62 controls the MA 17 [i] via the driver IC 20 to perform tracking control of the head 19 [i].

[0048] More specifically, the servo control unit 62 determines the target position r of the head 19[i] based on a command received from the host system 2 or the like. i The head position of the head 19 received from the R / W channel 40 determines an input current value or an input voltage value as a control value for seek control and tracking control of the head 19 and outputs it to the VCM 13 and the MA 17 [i].

[0049] The control switching unit 63 includes a simultaneous on-rail head determination unit 631, an MA control switching unit 633, and a VCM control switching unit 633. In addition, the simultaneous on-rail head determination unit 631 includes a VCM target position determination unit 6311. The VCM target position determination unit 6311 determines the target position r of the VCM 13. VCM About r VCM The method of determining is described later.

[0050] The simultaneous on-track head determination unit 631 determines the target position r of the head 19 based on the simultaneous on-track request. i The total maximum displacement of MA17[i] is used to determine the heads 19 that are actually on track at the same time. The set of heads 19 that are to be on track at the same time is set as set A.

[0051] The displacement of MA17 represents the radial movement distance of head 19 controlled by MA17. The voltage input to MA17 to move head 19 by the displacement amount is called the microactuator control voltage. The maximum displacement of MA17 represents the displacement amount when the maximum voltage that can be input to MA17 is applied. In addition, the total displacement of MA17[i] represents the sum of the displacements of all MA17[i][j] of head 19[i]. In addition, the total maximum displacement of each MA17[i] represents the sum of the maximum movement distance of head 19 that can be moved by each MA17[i][j] and depends on the maximum voltage that can be input to each MA17[i][j].

[0052] At the same time, the rail head determination unit 631 calculates the total maximum displacement y of the MA17[i] of the head 19[i] imax , remove the head 19 that meets the predetermined conditions from the set A. imax The method of determining is described later.

[0053] For example, the track head determination unit 631 calculates r VCM The target track r of head 19[i] i The difference d i , from d i ≥y imax +δ i d in the head 19[i] i -(y imax +δ i ) Remove the first 19 from the set A one by one starting from the largest first 19.

[0054] The VCM target position determination unit 6311 recalculates r for the head 19[i] of the set A. VCM , and the track head determination unit 631 uses the recalculated r VCM Calculate d again i Repeat the above process until there is no more d in set A i ≥y imax +δ i Finally, a set A of heads 19 controlled as being on track at the same time is obtained (referred to as the final set A).

[0055] The MA control switching unit 633 determines the voltage application method for controlling each head 19, each head having one or more MA17s. In addition, the MA control switching unit 633 determines the maximum voltage V to be applied by feedforward control based on the maximum displacement of each MA17[i][j] of each head 19[i] and the VCM target position among the multiple heads 19[i] on track at the same time. ijmax MA17[i][j], and switches the controller to reflect VCM13 and the maximum voltage V ijmax MA17[i][j] of the controller MA of the controller MA17.

[0056] The VCM control switching unit 633 controls the controller C based on the estimated position obtained from the position of any head 19 in the final set A of rail heads determined by the rail head determination unit 631 and the displacement amount of the MA 17. V Becomes a dedicated controller C for controlling only by VCM13 ～ V And positioning control is performed only through VCM13 to the VCM target position. Here, the controller C V Indicates that when only one head 19 (referred to as head 19[i]) is on track (r VCM With r i (i) VCM13 and MA17[i] are both used to control the VCM controller. In addition, when multiple heads 19 access simultaneously, basically r VCM With the head 19[i] r i Different, therefore, we need to VCM Control is only performed through VCM13. Set the VCM controller at this time as controller C ～ V Controller C ～ V Based on the assumption that only VCM13 is used for control, the characteristics are similar to those of controller C based on the assumption that MA17 is used. V The characteristics of the VCM are different, and a certain degree of positioning control can be performed only by VCM13.

[0057] Volatile memory 70 is a semiconductor memory that loses stored data when power is cut off. It stores data required for processing in magnetic disk drive 1. Examples of volatile memory 70 include DRAM (Dynamic Random Access Memory) and SDRAM (Synchronous Dynamic Random Access Memory).

[0058] The nonvolatile memory 80 is a semiconductor memory that records stored data even when power is cut off. The nonvolatile memory 80 is, for example, a NOR-type or NAND-type flash ROM (Flash Read Only Memory: FROM).

[0059] Figure 2 Schematic diagram showing an example of a multi-stage microactuator of a magnetic disk device according to an embodiment.

[0060] The magnetic disk drive 1 includes two or more disks 11. Multiple arms 15 corresponding to each disk 11 are controlled by a VCM 13, causing them to move in a circumferential direction around a pivot 14. The disks 11 can read and write data on both the top and bottom surfaces. Except for the top disk 11[1] and the bottom disk 11[iD], heads 19 are provided above and below each disk 11. For example, the top surface of disk 11[iD-1] is read and written by head 19[i-3], while the bottom surface of disk 11[iD-1] is read and written by head 19[i-2].

[0061] In addition, regarding the arms 15, as shown in the figure, the top and bottom arms 15 may be connected to the head 19 and the like on one side, and other arms 15 may be connected to the head 19 and the like on both sides. Therefore, the number iD for the disk 11, the number i for the head 19, and the number iA for the arm 15 may not necessarily be the same. For example, the head 19 that reads and writes to the disk 11[2] may be head 19[3] and head 19[4], and the arms 15 to which the heads 19 are connected may be arm 15[2] and arm 15[3], respectively.

[0062] The head 19[i] is connected to j=n (n is an integer greater than 2) MA17[i][1] to MA17[i][n], and the position is controlled. In addition, the number of MA17[i] that controls the head 19[i] is basically the same for all heads 19[i] (for example, Figure 2 , which shows a case where there are two MAs 17 for all heads 19).

[0063] Figure 3 This is an example of a block diagram of a controller that controls the VCM 13 and the MA 17 in the magnetic disk device according to the embodiment, and is an example of a case where only one head 19 [i] including a plurality of MAs 17 [i] is on track.

[0064] The control system 620 shows a control system for the head 19[i] based on the servo control unit 62, which has a function of setting the target position r of the head 19[i]. i As input and the current position y of head19[i] i The transfer function is used as the output. i 、y i A discrete-time signal is shown.

[0065] In the control system 620, Cv represents the controller or its transfer function that controls the VCM13, and C M [i][1]、C M [i][2]、C M [i][n] represent the controllers or transfer functions for controlling the microactuators MA17[i][1], MA17[i][2], and MA17[i][n] of the i-th head 19[i]. The transfer function Pv represents the VCM13 or its transfer function. M [i][1]、P M [i][2]、P M [i][n] represent MA17[i][1], MA17[i][2], MA17[i][n] or their transfer functions, respectively, included in the i-th head 19[i]. When MA17[i][1], MA17[i][2], and MA17[i][n] are not specifically distinguished, they are expressed as MA17[i].

[0066] The control system 620 is based on the target position r of the head 19[i]. i With the current position y i The difference (called head position error) e i Input the control input to VCM13 and MA17[i]. In VCM13, the determined current or voltage is input and the VCM position based on the transfer function Pv is output. In addition, the determined voltage is input to MA17[i][1], MA17[i][2], and MA17[i][n] respectively, and the output is based on the transfer function Pv. M [i][1]、P M [i][2]、P M The sum of these displacements and the VCM position is equal to the current position y i quite.

[0067] Figure 4 This is an example of a block diagram of a controller that controls the VCM 13 and the microactuator in the magnetic disk device according to the embodiment, and is an example that takes into account the case where a plurality of heads 19 and a plurality of MAs 17 are used.

[0068] The control system 621 shows a control system based on the servo control unit 62 obtained by integrating the control system 620 for one head 19 with N (N is an integer greater than or equal to 2). For example, the target position r of the N-th head 19 [N] is set to N As input, take the current head 19[N] head position y N The transfer function is used as the output. N 、y N A discrete-time signal is shown.

[0069] In the control system 621, Cv represents the controller or its transfer function that controls the VCM 13, and C M [1], C M [2], C M [N] represents a controller or a transfer function for controlling the MA 17 of the first head 19 [1], the second head 19 [2], and the N-th head 19 [N]. The transfer function Pv represents the VCM 13 or its transfer function. The transfer function P M [1] P M [2] P M [N] represents MA17 or its transfer function corresponding to the first head 19[1], the second head 19[2], and the Nth head 19[N] respectively. Figure 3 The control system 620 is connected to the controller C that controls one head (for example, set to be the i-th head 19[i]) in the control system 621. M [i]、P M [i], Cv, and Pv are equivalent.

[0070] In the control system 621, each controller C for the i-th head 19[i] M [i]、P M [i], the target position of head 19[i] is r i With the current position y i The head position error e i 、Target position y of VCM13 v As input, the VCM current or voltage and the microactuator voltage serving as control input are output to the VCM 13 and MA 17 [i] of the control head 19 [i].

[0071] The control switching unit 63 determines a head 19 to be controlled from among the plurality of heads 19 , determines a target position of the VCM 13 , determines a method of supplying current or voltage to the VCM 13 , or determines a method of supplying voltage to the MA 17 .

[0072] Figure 5 This is an example of a block diagram of a controller that controls the VCM 13 and the MA 17 in the magnetic disk device according to the embodiment, and focuses on the case where one head 19 [i] includes a plurality of MAs 17 [i].

[0073] The control system 622 shows a control system for the head 19[i] based on the servo control unit 62, which has a function of setting the target position r of the head 19[i]. i As input and the current position y of the current head 19[i] i The transfer function is used as the output. i 、y i A discrete-time signal is shown.

[0074] In the control system 622, Cv represents the controller or its transfer function that controls the VCM 13, and C M [i] represents a controller or transfer function of the MA17[i] of the control head 19[i]. In the head 19[i], there are multiple MA17[i] (for example, MA17[i][1], MA17[i][2], MA17[i][n]), and the transfer function is set to C in the same way as the control system 620. M [i][1]、C M [i][2]、C M [i][n]、P M [i][1]、P M [i][2]、P M [i][n].

[0075] exist Figure 5 The transfer function of switching to MA17[i][2] is shown in FIG. M [i][2] is an example of the case where the transfer function of the controller is switched M [i][2], set to C ～ M [i][2]. C ～ M The determination method of [i][2] will be described later. i1max Indicates the maximum voltage that can be input to MA17[i][1]. For each MA17[i][j], V is predetermined. ijmax . V ijmax Indicates the circuit limit or the physical limit determined by the composition of the components of MA17[i][j]. V ijmax Avoid applying voltages above these to the circuit or damaging MA17[i][j] when inputting them.

[0076] The operation of this embodiment will be described below.

[0077] Figure 6 This is a first flowchart showing processing operations when the magnetic disk device according to the first embodiment controls a plurality of heads.

[0078] The simultaneously on-track heads determining unit 631, triggered by a simultaneously on-track request or the like, determines a set A of heads 19 that are simultaneously on-track and performing read / write operations as an initial value, and passes the determined set A to the VCM target position determining unit 6311 (step S101). In step S101, the set A of heads 19 that are simultaneously on-track can be specified by the host 2 in a simultaneously on-track request and sent to the disk device 1. For example, the HDC 50 can parse the data access request received from the host 2 and determine the heads 19 that are simultaneously on-track.

[0079] The VCM target position determination unit 6311 uses the target position r of the head 19 of the set A. i The target position r of VCM is obtained by formula 1 VCM (Step S102).

[0080]

Mathematical formula 1

[0081]

[0082] Here, r i is the target position of the target track of the i-th head 19[i].

[0083] |A| represents the number of heads (number of elements) included in the set A.

[0084] In steps S103 and S107, i is used as a variable and the process is repeated for each head 19[i] of the set A. However, before this, the variable Max_value used in the process is initialized (step S1021).

[0085] At the same time, the track head determination unit 631 sets r VCM and the target position r of head 19[i] i The difference d i , the total maximum displacement y of head 19[i] imax These are obtained as Equation 2 and Equation 3, respectively, and the conditional expression of Equation 4 is confirmed (step S104).

[0086]

Mathematical formula 2

[0087] d i =|r i -r VCM | (Equation 2)

[0088]

Mathematical formula 3

[0089]

[0090] Here, j is a natural number indicating the index of n MAs 17 [i] for the control head 19 [i]. In Formula 3, MAs 17 [i] [j] with j = 1 to n are used.

[0091]

Mathematical formula 4

[0092] d i ≤y imax +δ i (Formula 4)

[0093] δ i This is a displacement amount corresponding to a predetermined voltage margin of the i-th head 19[i], and can be stored in advance in the nonvolatile memory 80 or the like.

[0094] At the same time, the track head determination unit 631 does not satisfy the d in the head 19[i] of the formula 4. i -(y imax +δ i ) The headers 19 are removed from the set A in order from the largest header 19 (steps S103 to S107). The following describes the processing of the header 19[i] as a specific example.

[0095] At the same time, when the track head determination unit 631 determines that the head 19[i] does not satisfy the formula 4 ("No" in step S104), and i -(y imax +δ i ) is compared with the Max_value of the internal variable and d i -(y imax +δ i ) is greater than Max_value ("Yes" in step S105), Max_value=d i -(y imax +δ i ), the index i of the head 19 at this time is substituted into Max_hd_id (step S106). At the same time, the track head determination unit 631 finally determines the d in the head 19[i] that does not satisfy the formula 3 through the above-mentioned processing. i -(y imax +δ i ) The largest header 19[i] and the index of the header 19 at this time, namely Max_hd_id. In addition, the processing of steps S105 and S106 is an example, and other methods can also be used.

[0096] At the same time, the track header determination unit 631 removes the header 19 [Max_hd_id] of the determined Max_hd_id from the set A (step S108).

[0097] Figure 8 This is a schematic diagram for explaining a method of selecting a head to be processed from a plurality of heads in the magnetic disk device according to the first embodiment. The horizontal axis represents the radial direction of the head 19 , and the x mark represents the radial position of each head 19 .

[0098] Figure 8 (a) shows the radial target position of the head 19[i] of the set A determined in step S101, for example, the head 19[ID11] and the head 19[ID12] are shown from r VCM Center ±(y imax +δ i ) range. Figure 8 For simplicity, y imax +δ iCommon to all headers.

[0099] At the same time, after the track head determination unit 631 determines Max_hd_id=ID11 by executing the processing of steps S103 to S107 , it removes the head 19 [ID11] from the set A in step S108 . Figure 8 (b) shows the set A after the header 19 [ID11] is removed.

[0100] The VCM target position determination unit 6311 calculates the VCM target position r for the head 19 of the set A using equation 1. VCM (and Figure 8 (b) r2 VCM (equivalent) (step S109).

[0101] At the same time, the track head determination unit 631 uses the r obtained in step S109 for the head 19 of the set A. VCM , confirm whether there is a head 19 that does not meet the condition of formula 4 (step S111). Figure 8 In (b), as an example of the header 19 in the set A that does not satisfy the condition of Expression 4, one header 19 [ID12] is shown.

[0102] If there is a header 19 that does not satisfy the condition of Expression 4 (No in Step S111), the processing of Steps S103 to S107 is executed again to determine Max_hd_id from the set A. Figure 8 In the case of (b), select Max_hd_id=ID12.

[0103] At the same time, the track head determination unit 631 removes the head 19 [Max_hd_id] of the Max_hd_id determined from the set A from the set A (step S108), and calculates the target position r of the VCM for the set A again. VCM (and Figure 8 (c) r3 VCM (corresponding to) (step S109). Hereinafter, the processing from step S103 is repeated in the same manner until all the heads 19 of the set satisfy the condition of equation 4.

[0104] exist Figure 8 In case (b), the head [ID12] is removed from set A, so Figure 8As shown in (c), at this time point, all heads 19 satisfy the condition of Formula 4. Through the above processing, the magnetic disk device 1 of this embodiment removes from the set A heads 19 whose total displacement, that is, the sum of the displacements of the MAs constituting the MAs 17 of the heads 19 exceeds the absolute value of the difference between the target position of the VCM 13 and the target position of the head 19 (calculated by Formula 2). In addition, the magnetic disk device 1 of this embodiment removes head [i] from the set A when the target position of one or more microactuators 17 [i] provided in the head 19 [i] exceeds the absolute value of the difference between the target position of the VCM 13 and the sum of the maximum displacements of the one or more microactuators 17 [i].

[0105] exist Figure 8 In the example (c), by removing head 19[ID11] and head 19[ID12] from set A, Figure 8 (c) will only be in the r3 VCM Center ±(y imax +δ i ) are left in the set A. Through the above steps, the set A (final set A) of the heads 19 that actually read and write on the track at the same time and the target position r of the VCM are determined. VCM (with r3 VCM quite).

[0106] Through the above steps, the magnetic disk device 1 of this embodiment controls the total displacement of all MA17 of the head 19 included in the control set A (final set A) so as not to exceed the maximum allowable voltage V predetermined for each MA17. ijmax The total maximum displacement y when the sum of imax .

[0107] The following describes a procedure for determining the manner of applying voltage to the plurality of MAs 17 [i] for each of the heads 19 [i] that are elements of the final set.

[0108] Figure 7 This is a second flowchart showing processing operations when the magnetic disk device according to the first embodiment controls a plurality of heads.

[0109] The multiple MAs [i] set on the head 19 [i] are based on the maximum displacement y ijmax The numbers (j=1, 2, 3, ...) are assigned as MA[i][j] in descending order of the maximum displacement.

[0110] The MA control switching unit 633 controls only the state satisfying d i ≤y imax +δ i The final set of heads 19 of A is head 19[i], starting from j=1, and the maximum displacement yijmax The sum of (the maximum displacement y of MA17[i] imax ) and displacement d i Compare and find the smallest l that satisfies the following formula i (Step S114).

[0111]

Mathematical formula 5

[0112]

[0113] At j = l i In the case of VCM, the MA control switching unit 633 takes into account the control system and j <l i The control system of MA[i][j] is obtained as in Equation 6 for MA17[i][l i ] after the switch controller C ～ M [i][l i ](step S115).

[0114]

Mathematical formula 6

[0115]

[0116] The MA control switching unit 633 sets MA17[i][l i ] controller as C ～ M [i][l i ] to implement positioning control of head 19[i].

[0117] In j <l i In the case of P M [i][j] is set as feedforward control and the maximum voltage V ijmax Applied to MA17[i][j]. That is, the MA control switching unit 633 applies to the j=lth i - MA17[i][j] pass voltage V up to 1 ijmax Feedforward control (FF control) is performed (step S116).

[0118] The VCM control switching unit 632 changes the controller to the controller C for only the VCM 13 based on the estimated position obtained from the position of any head 19 in the final set A and the displacement amount of the MA 17. ～ V The positioning is controlled to the VCM target position only by the VCM 13. Here, since there is no sensor and the position of the VCM 13 is unknown, the estimated position is the position estimated from the displacement of the MA 17.

[0119] The control switching unit 63 performs the processing of steps S114 to S117 on all the heads 19 of the final set A, thereby determining the maximum voltage V that can be input to each MA17[i][j] based on the maximum displacement of the multiple MA17[i] of the head 19[i] included in the final set A. ijmax The first type of microactuator with input through feedforward control and the control system taking VCM into consideration and j <l i The controller of the control system of MA[i][j] of equation (6) controls the second type of microactuator and switches the controller.

[0120] Through the above steps, the magnetic disk device of this embodiment can control the input voltage to all MAs 17[i][j] of the head 19[i] on track at the same time so as not to exceed the maximum voltage V ijmax , that is, taking into account the travel constraints of all MA17[i][j], multiple heads 19[i] can be on track at the same time with high precision.

[0121] (Second embodiment)

[0122] In this embodiment, an example of a magnetic disk device is shown in which a target position r of a VCM is set. VCM The head 19 whose radial position deviates greatly from the reference is removed from the objects (set A) of simultaneous on-track control. Hereafter, the candidates to be excluded from the objects of control are set as the target position r of the VCM. VCM A head 19 that is located in the same radial direction as the head 19 that was initially excluded when viewed.

[0123] Figure 9 This is a flowchart showing processing operations when the magnetic disk device according to the second embodiment controls a plurality of heads.

[0124] The flowchart of the first embodiment Figure 6 The main difference is the processing of the decision set A from step S2021 to step S2081. Therefore, this processing will be mainly described, and the description of the same points will be omitted.

[0125] The simultaneous on-track head determination unit 631 uses a simultaneous on-track request or the like as a trigger to determine a set A of heads 19 that are simultaneously on-track and performing read / write operations as an initial value, and passes the determined set A to the VCM target position determination unit 6311 (step S201). The VCM target position determination unit 6311 uses the target position r of the head 19[i] in the set A to determine the target position r of the head 19[i] in the set A. i Set the target position of VCM to r VCM Calculated by formula 1 (step S202).

[0126] Figure 10Schematic diagram for explaining a method of selecting a head to be processed from a plurality of heads in the magnetic disk device according to the second embodiment. The horizontal axis represents the radial position, and the x mark represents the radial target position of each head 19. Figure 10 For simplicity, y imax +δ i Common to all headers.

[0127] Figure 10 (a) shows the radial position of the head 19 of the set A determined in step S201, for example, the head 19 [ID21], [ID22], [ID23] from r VCM ±(y imax +δ i ) range deviation, wherein the head 19 [ID21] is set to be r VCM At the same time, the track head determination unit 631 updates the set A by executing the process from step S203.

[0128] In steps S203 and S207, i is used as a variable and each head 19[i] of set A is repeatedly processed, but before that, the Max_value used in the processing is initialized to the initial value 0, and sets B and C are initialized to empty sets (step S2021).

[0129] At the same time, the track head determination unit 631 confirms the conditional expression of Expression 4 (step S204).

[0130] At the same time, when the track head determination unit 631 determines that the head 19[i] does not satisfy the formula 4 ("No" in step S204), it checks whether r i -r VCM ≥ 0 (step S2041). If the condition of step S2041 is met, head 19[i] is included in set B (step S2042). If not, head 19[i] is included in set C (step S2043).

[0131] Right i -(y imax +δ i ) is compared with the Max_value (initial value 0) of the internal variable, and i -(y imax +δ i ) is greater than Max_value, Max_value = d i -(y imax +δ i ), substitute sgn(r) into Max_hd_id i -r VCM) (Step S206 ). sgn(x) represents the positive or negative sign (+, −) of the value x.

[0132] At the same time, after the track head determination unit 631 performs the above-mentioned processing on all elements of set A (steps S203 to S207), it checks whether Max_hd_id>0 (step S208). If Max_hd_id>0, the elements of set B are removed from set A to form a new set A (step S2081). If Max_hd_id>0, the elements of set C are removed from set A to form a new set A (step S2082). Through the above steps, it is possible to remove elements of set B from set A. VCM The largest distance head 19 [ID21], and r VCM The reference is head 19 [ID22] which is in the same radial direction as head 19 [ID21].

[0133] Figure 10 (b) shows the radial position of the head 19 of the set A after removing the head 19 [ID21] and the head 19 [ID22] from the set A. r2 VCM This is the target position of the VCM obtained by the VCM target position determination unit 6311 for the set A in step S209 .

[0134] The process from step S210 onward is executed for header 19 of set A. For example, if the result of step S211 on header 19 [ID22] is "No" ("No" in step S211), the process returns to step S203 and iterates. Steps S210 to S212 may be repeated sequentially for header 19 of set A (a for loop process) until a "No" result is returned in step S211, with the iterative process terminating when a "No" result is returned in step S211.

[0135] That is, through the processing of steps S210 to S212, the target position r of the VCM newly calculated with respect to the head 19 of the set A is detected simultaneously in the track head determination unit 631. VCM (and Figure 10 r2 in (b) VCM The head 19 that does not satisfy the condition of formula 4 is centered at (equivalent to).

[0136] For example, in Figure 10 In the example of (b), the head 19 [ID23] is detected through the processing of steps S210 to S212, and the process returns to step S203.

[0137] In the reprocessing from step S203, the rail head determination unit 631 uses the newly calculated VCM target position r VCM (exist Figure 10In the example of (b), r2 VCM ), confirm the condition of step S204 for the head 19 of set A. Therefore, if Figure 10 As shown in the example of (b), in the reprocessing of steps S203 to S207, the track head determination unit 631 detects that the head 19 [ID23] does not meet the condition of step S204. As a result, Figure 10 As shown in the example of (c), set A becomes a set with header 19 [ID23] newly removed, that is, a set with header 19 [ID21], header 19 [ID21], and header 19 [ID23] removed from the initial value of set A.

[0138] Next, in step S209, r is newly calculated as the target position of the VCM for the set A. VCM (and Figure 10 r3 in (c) VCM equivalent), but if Figure 10 As shown in the example of (c), at the newly calculated VCM target position r3 VCM ±(y imax +δ i ) contains all the heads 19[i], so there is no situation where "No" is entered in steps S210 to S212, and the next step is entered. The next step is the same as the following Figure 7 The same is true after S113. Set A of the head 19 is regarded as the final set A, and the subsequent processing from step S113 is executed on the final set A.

[0139] Through the above steps, the magnetic disk device of this embodiment can make the input voltage to all MA17[i][j] of the head 19[i] on the track at the same time not exceed the maximum voltage V ijmax The approach, i.e., considering the voltage constraints of the micro-actuators of all MA17[i][j], is computationally more efficient to enable multiple heads 19[i] to be on track simultaneously.

[0140] (Third embodiment)

[0141] In this embodiment, an example of a magnetic disk device is shown in which a target position r of a VCM is set. VCM The heads 19 whose radial positions deviate significantly from the reference are all excluded from the targets (set A) of simultaneous on-track control.

[0142] Figure 11 This is a flowchart showing processing operations when the magnetic disk device according to the third embodiment controls a plurality of heads.

[0143] The difference from the first embodiment and the second embodiment is that the condition of removing the head 19 as the control target from the set A is used. Therefore, for the condition corresponding to the flowchart ( Figure 6 、 8 ) For the parts with the same processing, detailed description is omitted.

[0144] Figure 12 Schematic diagram for explaining a method of selecting a head to be processed from a plurality of heads in the magnetic disk device according to the third embodiment. The horizontal axis represents the radial position, and the x mark represents the target radial position of each head 19.

[0145] Figure 12 (a) shows the radial position of the head 19 of the set A determined in step S301, for example, the head 19 [ID31], [ID32] from r VCM ±(y imax +δ i ) range. Figure 11 Flowchart, remove header 19 [ID31], [ID32].

[0146] More specifically, if head 19[i] does not satisfy equation 4 ("No" in step S304), head 19[i] is removed from set A. On the other hand, if head 19[i] satisfies equation 4 in step S304 ("Yes" in step S301), the controller action for head 19[i] is determined (processing of steps S306 to S309). The processing of steps S306 to S309 is the same as Figure 7 The same processing is performed in steps S114 to S117, so the description is omitted.

[0147] By executing the processing of steps S303 to S309 for all the heads 19 of the set A as described above, Figure 12 As shown in (b), all the headers 19 are generated in the form of r VCM ±(y imax +δ i ) of the range of the final set A. In this embodiment, it is possible to not perform r VCM The final set is generated by recalculating .

[0148] Through the above steps, the magnetic disk device of this embodiment can easily control the plurality of heads 19 in consideration of the stroke constraints of the plurality of MAs 17 provided in the plurality of heads 19 .

[0149] According to at least one embodiment described above, a magnetic disk device having a multi-stage actuator system that takes into account the stroke constraints of the microactuator can be provided. In addition, the magnetic disk device of at least one embodiment described above includes a controller (for example, a controller) that switches VCM13 and MA17 in a manner that does not reduce positioning accuracy by taking into account the voltage of MA17 when multiple heads 19 are simultaneously on track. Figure 4 C M 、Cv ) functions (e.g. Figure 4 control switching unit 63).

[0150] Several embodiments have been described, but 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 gist of the invention. These embodiments and their variations are included in the scope and gist of the invention, and are included in the invention described in the claims and their equivalents. In addition, the processing shown in the flowchart, sequence diagram, etc. can be implemented by hardware such as a CPU, an IC chip, a digital signal processing processor (Digital Signal Processor or DSP), or software (programs, etc.) that is enabled to work by a computer including a microcomputer, or a combination of hardware and software. In addition, even when the technical solution is described as a control logic, as a program including instructions for executing a computer, and as a computer-readable recording medium recording the instructions, the device of the present invention is also applicable. In addition, the names and terms used are not limiting, and even other descriptions are included in the present invention if they are essentially the same content and the same gist.

Claims

1. A magnetic disk device comprising: Multiple heads can read and write data independently and simultaneously; microactuators, wherein each of the heads is provided with one or more microactuators, and all of the microactuators are independently controllable; VCM, controlling each of the heads; a simultaneously-on-rail head determination unit that determines a final set of simultaneously-on-rail heads using at least the displacement of the microactuator; a VCM target position determination unit, which determines the target position of the VCM when both are on track; A VCM control switching unit, switching the VCM controllers when both are on track; and The MA control switching unit switches the controller of the microactuator for each head that is simultaneously on track determined by the simultaneously on track head determining unit.

2. The magnetic disk device according to claim 1, The simultaneous-on-track header determination unit determines the final set based on a first set of headers specified by an external simultaneous-on-track request.

3. The magnetic disk device according to claim 1, The simultaneously-on-track header determination unit determines a first set of simultaneously-on-track headers based on a data access request received from the outside, and determines the final set based on the first set.

4. The magnetic disk device according to claim 2 or claim 3, The first head included in the final set includes one or more first microactuators for controlling the first head. When the target position of the one or more first microactuators exceeds the absolute value of the difference between the target position of the VCM and the sum of the maximum displacements of the one or more first microactuators, the first head is removed from the first set.

5. The magnetic disk device according to claim 1, The VCM target position determination unit determines the target position of the VCM based on the target positions of all the heads included in the final set.

6. The magnetic disk device according to claim 1, The VCM is controlled based on the VCM target position determined by the VCM target position determination unit, the target position of the second head included in the final set, and the total displacement of one or more second microactuators controlling the second head.

7. The magnetic disk device according to claim 1, The MA control switching unit determines whether to apply the maximum input voltage to the first type of microactuator through feedforward control, or to switch to the second type of microactuator controlled by a controller that takes into account the original characteristics of the VCM control system and the microactuator control system set to perform feedforward control, with respect to controlling one or more third microactuators of the third head included in the final set, and switches the controller.

8. The magnetic disk device according to claim 7, The MA control switching unit performs control so that the input voltage to one or more fourth microactuators of the fourth head included in the final set does not exceed a maximum voltage which is a maximum value of input voltages predetermined for each of the fourth microactuators.

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