Magnetic disk device

Abstract

To provide a magnetic disk device of a multistage actuator system in which stroke restriction of a micro-actuator is taken into consideration.SOLUTION: A magnetic disk device according to an embodiment includes: a plurality of heads capable of independently and simultaneously reading and writing data; one or more micro-actuators provided in each of the heads and all independently controllable; a VCM that controls each of the heads; a simultaneous on-track head determination unit that determines a final set which is a set of heads to be simultaneously on-tracked using at least a displacement amount of the micro-actuator; a VCM target position determination unit that determines a target position of the VCM at the time of simultaneous on-track; a VCM control switching unit that switches a VCM controller at the time of simultaneous on-track; and an MA control switching unit that switches a controller of the micro-actuator for each of the heads to be simultaneously on-tracked determined by the simultaneous on-track head determination unit.SELECTED DRAWING: Figure 6

Description

[Technical Field]

[0001] An embodiment of the present invention relates to a magnetic disk drive using a multi-stage microactuator system. [Background technology]

[0002] A multi-stage microactuator magnetic disk drive has multiple microactuators on one head. The input voltages to the multiple microactuators can be set independently, but applying a large voltage can cause degradation of the elements. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 5,072,318 [Patent Document 2] U.S. Patent No. 7,054,094 [Patent Document 3] U.S. Patent No. 8,503,124 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the embodiments of the present invention is to provide a magnetic disk drive with a multi-stage actuator system that takes into account the voltage constraints of the microactuator. [Means for solving the problem]

[0005] The magnetic disk device of this embodiment comprises a plurality of heads capable of independently reading and writing data simultaneously, one or more microactuators for each of the heads, all of which can be controlled independently, a VCM to control each of the heads, a simultaneous on-track head determination unit that determines a final set of heads to be simultaneously on-track using at least the control input (microactuator control voltage) or displacement amount of the microactuators, a VCM target position determination unit that determines the target position of the VCM when simultaneous on-track occurs, a VCM control switching unit that switches the VCM controller when simultaneous on-track occurs, and an MA control switching unit that switches the microactuator controller for each head to be simultaneously on-track determined by the simultaneous on-track head determination unit. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is a configuration diagram of a magnetic disk device according to an embodiment. [Figure 2] FIG. 2 is a schematic diagram showing an example of a multi-stage microactuator in a magnetic disk drive according to an embodiment. [Figure 3] FIG. 3 is an example of a block diagram of a servo control unit and related components in a magnetic disk device according to an embodiment, focusing on one head equipped with multiple microactuators. [Figure 4] FIG. 4 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 a plurality of heads and a plurality of microactuators. [Figure 5] FIG. 5 is an example of a block diagram of a controller that controls the VCM and microactuators in a magnetic disk device according to an embodiment, focusing on one head i equipped with multiple microactuators. [Figure 6] FIG. 6 is a first flowchart showing the processing operation when the magnetic disk device according to the first embodiment controls a plurality of heads. [Figure 7] FIG. 7 is a second flowchart showing the processing operation when the magnetic disk device according to the first embodiment controls a plurality of heads. [Figure 8] FIG. 8 is a schematic diagram for explaining a method for the magnetic disk device according to the first embodiment to select a head to be processed from among a plurality of heads. [Figure 9] FIG. 9 is a flowchart showing the processing operations when the magnetic disk device according to the second embodiment controls a plurality of heads. [Figure 10] FIG. 10 is a schematic diagram for explaining a method for selecting a head to be processed from a plurality of heads in the magnetic disk device according to the second embodiment. [Figure 11] FIG. 11 is a flowchart showing the processing operations when the magnetic disk device according to the third embodiment controls a plurality of heads. [Figure 12] FIG. 12 is a schematic diagram for explaining a method for selecting a head to be processed from a plurality of heads in a magnetic disk drive according to the third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0007] Hereinafter, embodiments will be described with reference to the drawings. Note that the drawings are merely examples and do not limit the scope of the invention.

[0008] (First embodiment) In this embodiment, an example of a magnetic disk device (Hard Disk Drive: HDD) is shown, which has multiple microactuators (hereinafter sometimes referred to as MAs) in one head and is configured so that the voltages of all MAs can be set independently, and in which multiple heads each perform on-track reading and writing simultaneously.

[0009] Applying a large absolute voltage to an MA can cause element degradation. Therefore, the magnetic disk drive of this embodiment controls multiple heads by simultaneously taking into account the input voltages to the multiple MAs that control each of the multiple heads when multiple heads are simultaneously on-track. More specifically, the input voltage to each MA is controlled by taking into account the voltage constraints of each MA (maximum voltage that can be input), and simultaneous reading and writing is performed using multiple heads.

[0010] FIG. 1 is a configuration diagram of a magnetic disk device according to an embodiment.

[0011] The magnetic disk device 1 is a storage device equipped with a magnetic disk 11 (hereinafter sometimes simply referred to as a disk) on which data is read and written, and is equipped with a processor equipped with computer functions such as arithmetic processing, for example, a processing device such as a microprocessor, and various memories. The magnetic disk device 1 outputs data to the host system 2 connected thereto based on commands received from the host system 2, and writes data input from the host system 2 to the disk 11. Although only one actuator and head are shown in FIG. 1, the magnetic disk device 1 is equipped with multiple disks and heads, as described below.

[0012] The host system 2 is, for example, a personal computer, and outputs a read command to read data from the disk 11, a write command to write data to the disk, and the like to the magnetic disk device 1. The host system 2 may also output information on the sampling period of the servo information contained in the disk 11 of the magnetic disk device 1 to specify this to the magnetic disk device 1.

[0013] HDA 10 is called a head disk assembly, and contains a magnetic disk 11, a spindle motor (hereinafter also referred to as SPM) 12, an arm 15 carrying a head 19, a voice coil motor (hereinafter also referred to as VCM) 13, etc. In the example shown in Fig. 1, HDA 10 is equipped with one disk 11 and one head 19, but one or more of each may be provided.

[0014] The disk 11 is a disk-shaped magnetic rotating disk storage medium, and its data area, where data can be written (sometimes called "write"), is divided into a user data area available to users and a system area where information required for system management is written. Hereinafter, the direction perpendicular to the radial direction of the disk 11 will be referred to as the circumferential direction. The disk 11 is attached to a spindle motor 12 and rotates when driven by the spindle motor 12. Since the magnetic disk device 1 includes multiple disks 11, for example, the iDth disk (iD is a natural number) will be referred to as disk 11[iD]. iD is used as an identification number to identify the iDth disk 11 among the multiple disks 11, but iD may also be considered a variable and interpreted as any disk 11 among the multiple disks 11.

[0015] A plurality of tracks are set on the disk 11. In Fig. 1, three tracks TR1, TR2, and TR3 (referred to as track TR when no particular distinction is made) are shown as examples, but a plurality of tracks are set concentrically around the spindle motor 12 in the data area. When reading or writing data from the disk 11, the head 19 is moved by seek control, tracking control, etc. to the track TR where the data to be read or written (sometimes referred to as target data) is located, and the head 19 reads or writes the data. The track TR where the target data is located is sometimes referred to as the target track.

[0016] Servo information is also written on the disk 11 and is used for detecting the position of the head 19, etc. The servo information is provided at predetermined positions (called servo areas) in the circumferential direction of the disk 11. The servo information is general content, and a detailed description will be omitted. In the example of FIG. 1, three servo areas SVA1, SVA2, and SVA3 (referred to as servo area SVA when no particular distinction is made) are shown as examples of servo areas, but generally, servo areas SVA are provided at equal intervals all over the circumferential direction of the disk 11, and servo information is written in the servo area SVA of each track TR. The magnetic disk device 1 can detect the current position of the head 19 (head position) based on the servo information read by the head 19.

[0017] The spindle motor 12 (SPM 12) is a support for the disk 11 and is installed in the housing of the magnetic disk, etc. The disk 11 rotates as the spindle motor 12 rotates.

[0018] The VCM 13 is a voice coil motor type actuator, and is used to move the arm 15 etc. The VCM 13 controls the operation of the arm 15 etc. based on the input current or voltage.

[0019] The pivot 14 is a bearing that supports the arm 15 and the like and allows it to rotate.

[0020] Arm 15 is an arm that supports slider 18 and head 19, and transmits power from VCM 13 to head 19, moving head 19 to a target track TR. Since magnetic disk device 1 is equipped with a plurality of arms 15 corresponding to a plurality of heads 19, for example, the iAth arm (iA is a natural number) is indicated as arm 15[iA].

[0021] A microactuator 17 is connected to the suspension 16. Since the magnetic disk device 1 includes a plurality of suspensions 16 corresponding to a plurality of heads 19, the suspension corresponding to the ith head 19[i] (i is a natural number) is indicated as suspension 16[i], for example. i indicates the number for the head 19, and since a suspension 16 is provided for each head 19, the number i of the head 19 connected to the suspension 16 is used as the number for the suspension 16.

[0022] The microactuator 17 (sometimes referred to as MA 17) performs high-precision position adjustments, such as tracking control, of the head 19 based on the input current or voltage. While this is a common function and detailed explanations are omitted, the microactuator 17 performs fine adjustments to the position of the head 19 during settling after seek control, and tracking control for the target track after seek control. Settling refers to the state in which, after movement of the head 19 by seek control, the positioning error for the target track, including the influence of vibration of the head 19 due to seek control, falls below a certain threshold. After the vibration of the head 19 has been sufficiently reduced by settling, data read / write control and tracking control are performed.

[0023] The magnetic disk drive 1 of this embodiment includes one or more MAs 17 for controlling multiple heads 19. Therefore, all MAs controlling the i-th head 19 are indicated, for example, as MA17[i], using the letter i to indicate the number of the head 19. Furthermore, the magnetic disk drive 1 of this embodiment includes multiple MAs 17 corresponding to one head 19. Therefore, the j-th MA (j is a natural number) controlling the i-th head 19 is indicated, for example, as MA17[i][j]. The j-th MA may be composed of a pair of piezoelectric elements attached to the left and right of the head 19, as shown in FIG. 1. To indicate this, indexes such as ja and jb are assigned. 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 indicated as MA17[i][2a] and MA17[i][2b], indicating that they form a pair, forming MA17[i][2].

[0024] A head 19 is mounted on the slider 18. Since the magnetic disk device 1 is equipped with a plurality of sliders 18 corresponding to the plurality of heads 19, the slider corresponding to the ith head 19[i] is indicated as slider 18[i], for example.

[0025] The head 19 is a component that writes data to the disk 11 and reads data recorded on the data tracks of the disk 11. Because the magnetic disk device 1 has multiple heads 19 corresponding to multiple disks 11, individual heads 19 are indicated, for example, by head 19[i], where i is a natural number, to indicate the i-th head. Although i is used as an identification number to identify a head 19 among the multiple heads 19[i], i may also be considered a variable and interpreted as any head 19 among the multiple heads 19. In addition, when particularly distinguishing between them, the head that writes data to the disk 11 is referred to as write head 19W, and the head that reads data recorded on the data tracks of the disk 11 is referred to as read head 19R.

[0026] The driver IC 20 outputs a current or voltage for driving and controlling the SPM 12, VCM 13, MA 17, etc., in accordance with the control from the HDC 50, servo control unit 62, etc.

[0027] The head amplifier IC 30 includes a read amplifier and a write driver. The read amplifier amplifies a read signal read from the disk 11 and outputs it to the R / W channel 40. The write driver outputs a write current to the head 19 according to the signal output from the R / W channel 40. Since the magnetic disk device 1 includes head amplifier ICs 30 corresponding to a plurality of heads 19, the head amplifier IC corresponding to the ith head 19[i] is indicated as head amplifier IC 30[i], for example.

[0028] The R / W channel 40 controls the head amplifier IC 30 to read data from the disk 11 and write data to the disk 11 in response to instructions from the HDC 50, main controller 60, etc. The R / W channel 40 receives a read data signal from the head amplifier IC 30 and extracts read data, generates a write data signal based on write data instructed to be written, and outputs the write data signal to the head amplifier IC 30. The R / W channel 40 also has a function of measuring the signal quality of the read data received from the head amplifier IC 30. The R / W channel 40 may also extract position information of the head 19 based on a servo information signal received from the head amplifier IC 30.

[0029] The HDC 50 is an interface between the magnetic disk device 1 and the host system 2, and is a hard disk controller that controls each part of the magnetic disk device 1. The HDC 50 may be configured with a processing unit (processor) having a calculation function such as a CPU, other processing unit functions, an IC chip having various memories, a system LSI, an FPGA, etc. The various processes of the HDC 50 may be executed by a software (including firmware, etc.) program, or may be provided as hardware or a combination of software and hardware.

[0030] The HDC 50 receives commands such as commands to write data to the disk 11 or commands to read data from the disk 11 from the host system 2. Based on the received commands, the HDC 50 controls each part of the magnetic disk device 1 and transfers data between the host system 2 and the R / W channel 40. The HDC 50 may also control the reading and writing of data from the volatile memory 70 and the nonvolatile memory 80.

[0031] The main controller 60 is a main controller that controls each part of the magnetic disk device 1, and may be configured by a processing device (processor) such as a CPU or microprocessor that has computer functions such as arithmetic processing, an IC chip that has other processing device functions, various memories, etc., a system LSI, an FPGA, etc. The various processes of the main controller 60 may be executed by a software (including firmware, etc.) program, or may be provided as hardware or a combination of software and hardware.

[0032] The read / write control unit 61 selects a destination for storing write data (e.g., information such as a data sector or track on the disk 11) based on commands received from the host system 2, and controls the operation of writing data to the disk 11. The read / write control unit 61 notifies the servo control unit 62 or the like of a destination for storing read data (e.g., information such as a data sector or track on the disk 11) based on commands received from the host system 2, and operates the head 19 to control the operation of reading data from the disk 11.

[0033] 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 moves the head 19[i] to a target position (target track) r iTo move the head 19[i] to the target position, the servo control unit 62 controls the VCM 13 via the driver IC 20 to perform seek control and tracking control. The servo control unit 62 also controls the MA 17[i] via the driver IC 20 to perform tracking control of the head 19[i].

[0034] More specifically, the servo control unit 62 determines the target position r of the head 19[i] based on commands received from the host system 2. i Based on the head position of the head 19 received from the R / W channel 40, the input current value or input voltage value is determined as a control value for the seek control or tracking control of the head 19, and is output to the VCM 13 and MA 17[i].

[0035] The control switching unit 63 includes a simultaneous on-track head determining unit 631, an MA control switching unit 633, and a VCM control switching unit 633. The simultaneous on-track head determining unit 631 also includes a VCM target position determining unit 6311. The VCM target position determining unit 6311 determines the target position r of the VCM 13. VCM Determine r VCM The method for determining this will be described later.

[0036] The simultaneous on-track head determination unit 631 determines the target position r of the head 19 for which a simultaneous on-track request is made. i The heads 19 that will actually be on-track simultaneously are determined from the total maximum displacement of MA17[i] and MA17[i]. A set of heads 19 that are to be on-track simultaneously is set as set A.

[0037] The displacement of MA17 refers to 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 refers to the displacement amount when the maximum voltage that can be input to MA17 is applied. The total displacement of MA17[i] refers to the sum of the displacement amounts of all MA17[i][j] of head 19[i]. The total maximum displacement of each MA17[i] refers to 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].

[0038] The simultaneous on-track head determination unit 631 also calculates the total maximum displacement y of MA17[i] of head 19[i]. imax Calculate y and remove the head 19 that satisfies the specified condition from set A. imax The method for determining this will be described later.

[0039] For example, the simultaneous on-track head determination unit 631 determines whether r VCM and the target track r of head 19[i] i The difference between i Calculate d i ≧y imax +δ i Of the heads 19[i], d i -(y imax +δ i ) are removed from set A in order starting with head 19, which has the largest size.

[0040] The VCM target position determination unit 6311 determines the position of the head 19[i] in the set A by VCM The simultaneous on-track head determination unit 631 recalculates the recalculated r VCM Using d again i Calculate d i ≧y imax +δ i This is repeated until there is no head 19[i] for which the above condition is satisfied. Finally, a set A of heads 19 to be controlled as simultaneously on-track (referred to as final set A) is obtained.

[0041] The MA control switching unit 633 determines how to apply voltage to one or more MAs 17 provided for each head that controls each head 19. In addition, the MA control switching unit 633 determines the maximum voltage V from the maximum displacement amount of each MA 17[i][j] of each head 19[i] that are simultaneously on-track, and the VCM target position. ijmax MA17[i][j] is multiplied by feedforward control, VCM13 and maximum voltage V ijmax The MA17 that switches the controller to the MA controller that reflects the controller of MA17[i][j] multiplied by is determined.

[0042] The VCM control switching unit 633 controls the controller C based on the position of any one of the heads 19 in the final set A of simultaneously on-track heads determined by the simultaneously on-track head determining unit 631 and the estimated position calculated from the displacement of the MA 17. V Dedicated controller C for controlling only VCM13 ~ V Then, the VCM 13 alone controls the positioning to the VCM target position. V When only one head 19 (head 19[i]) is on track (r VCM and r i This shows the VCM controller when controlling using all of VCM13 and MA17[i]. Also, when multiple heads 19 access simultaneously, basically r VCM and head 19[i] r i Since it is different from VCM In this case, it is necessary to control only VCM13. The VCM controller at that time is controller C. ~ V Controller C ~ V is based on the assumption that it will be controlled only by VCM13, and controller C is based on the assumption that MA17 will be used. V The characteristics are different from those of the VCM13, and a certain degree of positioning control is possible with just the VCM13.

[0043] The volatile memory 70 is a semiconductor memory in which stored data is lost when the power supply is cut off. The volatile memory 70 stores data necessary for processing in the magnetic disk device 1. The volatile memory 70 is, for example, a dynamic random access memory (DRAM) or a synchronous dynamic random access memory (SDRAM).

[0044] The nonvolatile memory 80 is a semiconductor memory that records stored data even when the power supply is cut off. The nonvolatile memory 80 is, for example, a NOR or NAND type flash ROM (Flash Read Only Memory: FROM).

[0045] FIG. 2 is a schematic diagram showing an example of a multi-stage microactuator in a magnetic disk drive according to an embodiment.

[0046] The magnetic disk device 1 includes two or more disks 11, and a VCM 13 controls multiple arms 15 corresponding to each disk 11, moving them circumferentially around a pivot 14. The disks 11 are capable of reading and writing on both the top and bottom surfaces, and each disk 11 is provided with a head 19 above and below it, except for the top disk 11[1] and the bottom disk 11[iD]. For example, the top surface of disk 11[iD-1] is read and written by head 19[i-3], and the bottom surface of disk 11[iD-1] is read and written by head 19[i-2].

[0047] As shown in the figure, the arms 15 are configured such that the heads 19, etc. are connected to one side of the uppermost and lowermost arms 15, and the rest are configured such that the heads 19, etc. are connected to both sides, so the number iD for the disk 11, the number i for the head 19, and the number iA for the arm 15 do not necessarily match. For example, the heads 19 that read and write to disk 11[2] are head 19[3] and head 19[4], and the arms 15 to which each head 19 is connected are arm 15[2] and arm 15[3], respectively.

[0048] Head 19[i] is connected to j=n (n is an integer equal to or greater than 2) MA17[i][1] to MA17[i][n], and its position is controlled. Basically, the number of MA17[i] controlling head 19[i] is the same for all heads 19[i] (for example, Figure 2 shows a case where all heads 19 have two MA17s).

[0049] FIG. 3 is an example of a block diagram of a controller that controls the VCM 13 and MA 17 in a magnetic disk device according to an embodiment, and shows an example of on-track operation using only one head 19[i] equipped with multiple MAs 17[i].

[0050] The control system 620 is a control system for the head 19[i] by the servo control unit 62, and is used to control the target position r of the head 19[i]. i is used as input, and the current position y of head 19[i] is i It has a transfer function with output r i , y i denotes a discrete-time signal.

[0051] In the control system 620, Cv represents a controller that controls the VCM 13 or its transfer function, and C M [i][1] 、 C M [i][2] 、 C M [i][n] indicate the controllers or their transfer functions that control the microactuators MA17[i][1], MA17[i][2], and MA17[i][n] that are provided in the i-th head 19[i]. The transfer function Pv indicates the VCM 13 or its transfer function, and P M [i][1] 、 P M [i][2] 、 P M [i][n] respectively indicate MA17[i][1], MA17[i][2], MA17[i][n] provided in the i-th head 19[i] or their transfer functions. When there is no particular distinction between MA17[i][1], MA17[i][2], and MA17[i][n], they are referred to as MA17[i].

[0052] The control system 620 determines the target position r of the head 19[i]. i and the current position y i The difference between the head position error and the i Based on the inputs such as the above, control inputs are output to VCM13 and MA17[i]. The determined current or voltage is input to VCM13, and the VCM position is output based on the transfer function Pv. Also, determined voltages are input to MA17[i][1], MA17[i][2], and MA17[i][n], and each is output based on the transfer function Pv. M [i][1] 、 P M [i][2] 、 P M The displacement amount based on [i][n] is output. The sum of these displacement amounts and the VCM position is the current position y i is equivalent to

[0053] FIG. 4 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 in which a plurality of heads 19 and a plurality of MAs 17 are taken into consideration.

[0054] The control system 621 indicates a control system by the servo control unit 62 that integrates N (N is an integer of 2 or more) control systems 620 for one head 19. For example, the target position r N is used as input, and the current head position y N It has a transfer function with output r N , y N denotes a discrete-time signal.

[0055] In the control system 621, Cv represents a controller that controls the VCM 13 or its transfer function, and C M [1] 、 C M [2] 、 C M[N] indicates a controller or its transfer function that controls the MA 17 provided in each of the first head 19[1], the second head 19[2], and the Nth head 19[N]. The transfer function Pv indicates the VCM 13 or its transfer function, and the transfer function P M [1] 、 P M [2] 、 P M [N] indicate the MA 17 or its transfer function corresponding to the first head 19[1], the second head 19[2], and the Nth head 19[N], respectively. The control system 620 in FIG. 3 includes a controller C that controls one head (for example, the i-th head 19[i]) in the control system 621. M [i], P M [i], Cv, Pv.

[0056] In the control system 621, the controller C for the i-th head 19[i] M [i], P M For each [i], the target position r of head 19[i] i and the current position y i Head position error e i , VCM13 target position y v and outputs the VCM current or voltage and microactuator voltage as control inputs to the VCM 13 and MA 17[i] that control the head 19[i].

[0057] The control switching unit 63 determines the head 19 to be controlled from among the multiple heads 19, determines the target position of the VCM 13, determines the method of supplying current or voltage to the VCM 13, and determines the method of supplying voltage to the MA 17.

[0058] FIG. 5 is an example of a block diagram of a controller that controls the VCM 13 and MA 17 in a magnetic disk device according to an embodiment, focusing on one head 19[i] equipped with multiple MA 17[i].

[0059] The control system 622 is a control system for the head 19[i] by the servo control unit 62, and is used to control the target position r of the head 19[i].i is used as input, and the current position y of the current head 19[i] is i It has a transfer function with output r i , y i denotes a discrete-time signal.

[0060] In the control system 622, Cv represents a controller that controls the VCM 13 or its transfer function, and C M [i] indicates a controller that controls MA17[i] provided in head 19[i] or its transfer function. Head 19[i] is provided with multiple MA17[i] (for example, MA17[i][1], MA17[i][2], MA17[i][n]), and similarly to control system 620, each transfer function is expressed as C M [i][1] 、 C M [i][2] 、 C M [i][n] 、 P M [i][1] 、 P M [i][2] 、 P M Let [i][n].

[0061] In Figure 5, the transfer function of MA17[i][2] is C M This shows an example of switching the transfer function for the controller [i][2], i.e., C M Switch [i][2] and C ~ M Let [i][2]. C ~ M The method for determining [i][2] will be described later. i1maxは、 Indicates the maximum voltage that can be input to MA17[i][1], and for each MA17[i][j], V ijmax is predetermined. V ijmax indicates the physical limit determined by the circuit limit or the configuration of the elements of MA17[i][j], and V ijmax Voltages above this level cannot be applied to the circuit or input, as this may damage MA17[i][j] and must be avoided.

[0062] The operation of this embodiment will be described below.

[0063] FIG. 6 is a first flowchart showing the processing operation when the magnetic disk device according to the first embodiment controls a plurality of heads.

[0064] The simultaneous on-track head determination unit 631 determines, as an initial value, a set A of heads 19 that are to be simultaneously on-track and perform simultaneous read / write operations, triggered by a simultaneous on-track request or the like, and passes the determined set A to the VCM target position determination unit 6311 (step S101). In step S101, the set A of heads 19 that are to be simultaneously on-track may be specified by the host 2 in the simultaneous on-track request and sent to the magnetic disk device 1, or, for example, the HDC 50 may analyze a data access request received from the host 2 and identify the heads 19 that are to be simultaneously on-track.

[0065] The VCM target position determination unit 6311 determines the target position r of the head 19 of the set A. i Using this, the target position r of the VCM VCM is calculated using Equation 1 (step S102).

[0066]

number

[0067] In steps S103 and S107, the process is repeated for each head 19[i] of set A using i as a variable, but before that, the variable Max_value used in the process is initialized (step S1021).

[0068] The simultaneous on-track head determination unit 631 determines whether r VCM and the target position r of head 19[i] i The difference between i , the total maximum displacement of head 19[i] yimax are calculated as equations 2 and 3, respectively, and the conditional expression of equation 4 is confirmed (step S104).

[0069]

number

[0070]

number

[0071]

number

[0072] The simultaneous on-track head determination unit 631 determines d i -(y imax +δ i ) are removed from set A in descending order (steps S103 to S107). The processing for head 19[i] will be described below as a specific example.

[0073] If the head 19[i] does not satisfy the formula 4 (No in step S104), the simultaneous on-track head determination unit 631 determines whether d i -(y imax +δ i ) with the Max_value of the internal variable, and i -(y imax +δ i ) is greater than Max_value (Yes in step S104), Max_value=d i -(y imax +δ i) and substitutes the index i of the head 19 at this time into Max_hd_id (step S106). The simultaneous on-track head determination unit 631 finally determines, through the above processing, the d i -(y imax +δ i ) and Max_hd_id, which is the index of the head 19 at that time. Note that the processes in steps S105 and S106 are merely examples, and other methods may be used.

[0074] The simultaneous on-track head determining unit 631 removes the identified head 19 [Max_hd_id] of Max_hd_id from set A (step S108).

[0075] 8 is a schematic diagram for explaining a method for selecting a head to be processed from among multiple heads in the magnetic disk drive according to the first embodiment. The horizontal axis indicates the radial direction of the head 19, and the x marks indicate the radial position of each head 19.

[0076] FIG. 8(a) shows the target radial position of head 19[i] of set A determined in step S101. For example, head 19[ID11] and head 19[ID12] are set at r VCM Centered on ±(y imax +δ i ) range. For simplicity, in Figure 8, imax +δ i is common to all heads.

[0077] The simultaneous on-track head determination unit 631 executes the processes of steps S103 to S107 to identify Max_hd_id=ID11, and then in step S108 removes head 19[ID11] from set A. Figure 8(b) shows set A after head 19[ID11] has been removed.

[0078] The VCM target position determination unit 6311 determines the VCM target position r for the heads 19 of set A using Equation 1. VCM(r2 in Figure 8(b) VCM (corresponding to) is calculated (step S109).

[0079] The simultaneous on-track head determination unit 631 determines the r VCM It is checked whether there is any head 19 that does not satisfy the condition of Expression 4 (step S111) by using [Formula 4]. In FIG. 8(b), one head 19 [ID12] is shown as an example of a head 19 in set A that does not satisfy the condition of Expression 4.

[0080] If there is a head 19 that does not satisfy the condition of Expression 4 (No in step S111), the processes of steps S103 to S107 are executed again to identify Max_hd_id from set A. In the case of FIG. 8(b), Max_hd_id=ID12 is selected.

[0081] The simultaneous on-track head determination unit 631 removes the head 19 [Max_hd_id] of Max_hd_id identified from set A (step S108), and again determines the target position r of the VCM for set A. VCM (r3 in Figure 8(c) VCM (corresponding to Equation 4) is calculated (step S109). Similarly, the process from step S103 onwards is repeated until all heads 19 in the set satisfy the condition of Equation 4.

[0082] In the case of FIG. 8(b), head [ID12] has been removed from set A, and therefore, as shown in FIG. 8(c), all heads 19 satisfy the condition of Equation 4 at this point. Through the above process, the magnetic disk device 1 of this embodiment removes from set A any head 19 whose total displacement, which is the sum of the displacement amounts of the MAs constituting the MA 17 of each head 19, exceeds the absolute value (calculated by Equation 2) of the difference between the target position of the VCM 13 and the target position of the head 19. Furthermore, the magnetic disk device 1 of this embodiment removes head 19[i] from set A if the target position of one or more microactuators 17[i] provided for head 19[i] exceeds the absolute value of the difference between the target position of the VCM 13 and the sum of the maximum displacement amounts of the one or more microactuators 17[i].

[0083] In the example of Figure 8(c), by removing head 19[ID11] and head 19[ID12] from set A, the result is r3 as shown in Figure 8(c). VCM Centered on ±(y imax +δ i ) can be left in set A. By the above procedure, set A (final set A) of heads 19 that actually simultaneously perform on-track reading and writing and set A (final set A) of heads 19 that actually ... VCM (r3 VCM (equivalent to) is determined.

[0084] By the above procedure, the magnetic disk device 1 of this embodiment calculates the sum of the displacement amounts of all the MAs 17 that control the heads 19 included in set A (final set A) by the maximum allowable voltage V that is predetermined for each MA 17. ijmax The maximum total displacement y when the sum of imax Control so as not to exceed

[0085] The following describes the procedure for determining how to apply voltage to the multiple MAs 17[i] for each head 19[i], which is an element of the final set.

[0086] FIG. 7 is a second flowchart showing the processing operation when the magnetic disk device according to the first embodiment controls a plurality of heads.

[0087] The MA[i] installed on the head 19[i] has a maximum displacement y ijmax The data are sorted by the maximum displacement and are assigned numbers (j=1, 2, 3, etc.) as MA[i][j] in descending order of the maximum displacement.

[0088] The MA control switching unit 633 is i ≦y imax +δ i For the head 19[i] in the final set A, which is made up of only the heads 19 that satisfy the following, the maximum displacement y ijmax The sum of the maximum displacement y imax ) and displacement d iCompare the following equation and find the smallest l i is calculated (step S114).

[0089]

number

[0090]

number

[0091] j <l i In the case of P M [i][j] is the maximum voltage V ijmax That is, the MA control switching unit 633 multiplies MA17[i][j] by j=l i - The first MA17[i][j] is set to voltage V ijmax Then, feedforward control (FF control) is performed (step S116).

[0092] The VCM control switching unit 632 switches the controller to the controller C for VCM 13 only based on the position of any one of the heads 19 in the final set A and the estimated position calculated from the displacement of the MA 17. ~ V Positioning control is performed to the VCM target position using only the VCM 13. Here, the estimated position is the position estimated from the displacement of the MA 17, since there is no sensor and the position of the VCM 13 is unknown.

[0093] By performing the processes of steps S114 to S117 on all of the heads 19 in the final set A, the control switching unit 63 determines the maximum voltage V that can be input to each MA 17[i][j] based on the maximum displacement amount of the multiple MAs 17[i] that control the heads 19[i] included in the final set A. ijmax The first type of microactuator is input by feedforward control, and the VCM control system and j <l i The second type microactuator to be controlled by the controller of Equation (6) taking into account the control system of MA[i][j] is determined, and the controller is switched.

[0094] By the above procedure, the magnetic disk device of this embodiment can reduce the input voltage to all MAs 17[i][j] of the heads 19[i] that are simultaneously on-track to the maximum voltage V ijmax , that is, by taking into consideration the stroke constraints of all MAs 17[i][j], it becomes possible to simultaneously bring the multiple heads 19[i] on track with high accuracy.

[0095] (Second embodiment) In this embodiment, the target position r of the VCM VCM Based on this, heads 19 whose radial position is significantly misaligned are excluded from the simultaneous on-track control target (set A), and candidates to be excluded from the control target are then selected based on the target position r of the VCM. VCM 10 shows an example of a magnetic disk drive in which the head 19 is located in the same radial direction as the head 19 that was first removed when viewed from the front.

[0096] FIG. 9 is a flowchart showing the processing operations when the magnetic disk device according to the second embodiment controls a plurality of heads.

[0097] The difference from the flowchart of the first embodiment shown in FIG. 6 is mainly the process of determining set A from step S2021 to step S2081, so this process will be mainly described and the same parts will not be described again.

[0098] The simultaneous on-track head determination unit 631 determines a set A of heads 19 that are simultaneously on-track and perform simultaneous read / write operations as an initial value, triggered by a simultaneous on-track request or the like, and passes the determined set A to the VCM target position determination unit 6311 (step S201). The VCM target position determination unit 6311 determines the target position r of head 19[i] of set A. i Using this, the target position r of the VCM VCM is calculated using Equation 1 (step S202).

[0099] 10 is a schematic diagram for explaining a method for selecting a head to be processed from a plurality of heads in a magnetic disk drive according to the second embodiment. The horizontal axis indicates the radial position, and the x marks indicate the target radial position for each head 19. For simplicity, in FIG. 10, y imax +δ i is common to all heads.

[0100] FIG. 10(a) shows the radial positions of the heads 19 in set A determined in step S201. For example, the heads 19 [ID21], [ID22], and [ID23] are located at r VCM ±(y imax +δ i ) and head 19 [ID21] is outside the range of r VCM The simultaneous on-track head determination unit 631 updates the set A by executing the process from step S203.

[0101] In steps S203 and S207, the process is repeated for each head 19[i] of set A using i as a variable, but before that, the Max_value used in the process is initialized to the initial value 0, and sets B and C are initialized to empty sets (step S2021).

[0102] The simultaneous on-track head determination unit 631 checks the conditional expression of Equation 4 (step S204).

[0103] If the head 19[i] does not satisfy the formula 4 (No in step S204), the simultaneous on-track head determination unit 631 determines whether r i -r VCM It is checked whether or not ≧0 (step S2041). If the condition of step S2041 is met, head 19[i] is included in set B (step S2042), and if not, head 19[i] is included in set C (step S2043).

[0104] d i -(y imax +δ i ) and the internal variable Max_value (initial value 0), and i -(y imax +δ i ) is greater than Max_value, then Max_value=d i -(y imax +δ i ) and Max_hd_id to sgn(r i -r VCM ) is substituted (step S206). sgn(x) indicates the sign (+, -) of the numeric value x.

[0105] After the simultaneous on-track head determination unit 631 executes the above process for all elements of set A (steps S203 to S207), it checks whether Max_hd_id>0 (step S208). If Max_hd_id>0, it removes the elements of set B from set A to create a new set A (step S2081), and if Max_hd_id>0 is not true, it removes the elements of set C from set A to create a new set A (step S2082). By the above procedure, r VCM Head 19 [ID21], which has the maximum distance from head 19 [ID21], and head 19 [ID21] and r VCM Based on this, head 19 [ID22] in the same radial direction can be removed from set A.

[0106] FIG. 10(b) shows the radial positions of the heads 19 in set A after removing the heads 19[ID21] and 19[ID22] from set A. VCMis the target position of the VCM determined for set A by the VCM target position determination unit 6311 in step S209.

[0107] The process from step S210 is executed for the head 19 of set A. For example, if the result of the process in step S211 for head 19 [ID22] is No (No in step S211), the process returns to step S203 and is repeated. Steps S210 to S212 may be repeated (For loop process) for the heads 19 of set A in order until No is returned in step S211, and the repeated process may be stopped when No is returned in step S211.

[0108] That is, by the processing of steps S210 to S212, the simultaneous on-track head determination unit 631 determines the VCM target position r VCM (r2 in Figure 10(b) VCM The head 19 that does not satisfy the condition of Equation 4, centered on the target object (equivalent to the target object), is detected.

[0109] For example, in the example of FIG. 10(b), the head 19 [ID23] is detected by the processes of steps S210 to S212, and the process returns to step S203.

[0110] In the reprocessing from step S203, the simultaneous on-track head determination unit 631 determines the newly calculated target position r of the VCM. VCM (In the example of Figure 10(b), r2 VCM ) is used to check the condition of step S204 for head 19 of set A. Therefore, as shown in the example of FIG. 10(b), in the reprocessing of steps S203 to S207, the simultaneous on-track head determination unit 631 detects that head 19[ID23] does not satisfy the condition of step S204. As a result, as shown in the example of FIG. 10(c), set A becomes a new set from which head 19[ID23] has been removed, that is, a set from which heads 19[ID21], head 19[ID21], and head 19[ID23] have been removed from the initial value of set A.

[0111] Next, in step S209, r is set as the target position of the VCM for set A. VCM (r3 in Figure 10(c) VCM As shown in the example of FIG. 10(c), the newly calculated VCM target position r3 VCM ±(y imax +δ i ), there is no case where the process proceeds to the next step, with the result No in steps S210 to S212. From the next step onwards, the process is the same as from S113 onwards in Fig. 7, with set A of heads 19 being set as final set A, and the process from step S113 onwards is executed on final set A.

[0112] By the above procedure, the magnetic disk device of this embodiment can reduce the input voltage to all MAs 17[i][j] of the heads 19[i] that are simultaneously on-track to the maximum voltage V ijmax In other words, by taking into consideration the microactuator voltage constraints of all MAs 17[i][j], it becomes possible to simultaneously put multiple heads 19[i] on track with greater computational efficiency.

[0113] (Third embodiment) In this embodiment, the target position r of the VCM VCM 10 shows an example of a magnetic disk drive in which heads 19 whose radial positions are significantly misaligned are excluded from the simultaneous on-track control targets (set A) based on the above.

[0114] FIG. 11 is a flowchart showing the processing operations when the magnetic disk device according to the third embodiment controls a plurality of heads.

[0115] The difference from the first and second embodiments is the condition for removing the head 19 to be controlled from set A, so detailed explanation of the same processing as in the flowcharts (FIGS. 6 and 8) will be omitted.

[0116] 12 is a schematic diagram illustrating a method for selecting a head to be processed from multiple heads in a magnetic disk drive according to the third embodiment. The horizontal axis indicates the radial position, and the x marks indicate the target radial position for each head 19.

[0117] FIG. 12(a) shows the radial positions of the heads 19 in set A determined in step S301. For example, the heads 19 [ID31] and [ID32] are located at r VCM ±(y imax +δ i ) range. According to the flowchart in Figure 11, head 19 [ID31] and [ID32] are removed.

[0118] More specifically, if head 19[i] does not satisfy Expression 4 (No in step S304), head 19[i] is removed from set A. On the other hand, if head 19[i] satisfies Expression 4 in step S304 (Yes in step S301), the operation of the controller for head 19[i] is determined (processing of steps S306 to S309). The processing of steps S306 to S309 is similar to the processing of steps S114 to S117 in FIG. 7, and therefore description thereof will be omitted.

[0119] By executing the processes from steps S303 to S309 for all heads 19 in set A as described above, all heads 19 are VCM ±(y imax +δ i ) can be generated. In this embodiment, VCM The final set can be generated without performing a recalculation of

[0120] By the above procedure, the magnetic disk device of this embodiment can easily control the multiple heads 19 while taking into consideration the stroke constraints of the multiple MAs 17 provided on each of the multiple heads 19.

[0121] According to at least one of the embodiments described above, it is possible to provide a magnetic disk drive of a multi-stage actuator system that takes into consideration the stroke constraints of the microactuator. Furthermore, the magnetic disk drive according to at least one of the embodiments described above controls the VCM 13 and the MA 17 controller (for example, C in FIG. 4) to prevent a drop in positioning accuracy by taking into consideration the voltage of the MA 17 when multiple heads 19 are simultaneously on-track. M , C v ) (for example, the control switching unit 63 in FIG. 4).

[0122] Although several embodiments have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments may be embodied in various other forms, and various omissions, substitutions, and modifications may be made without departing from the spirit of the invention. These embodiments and their modifications are within the scope and spirit of the invention, and are also encompassed by the inventions and their equivalents as set forth in the claims. Furthermore, the processes shown in flowcharts, sequence charts, etc. may be implemented by hardware such as a CPU, an IC chip, or a digital signal processor (DSP), or software (e.g., a program) running on a computer including a microcomputer, or a combination of hardware and software. The device of the present invention is also applicable when the claims are expressed as control logic, a program including instructions for a computer to execute, or a computer-readable recording medium containing the instructions. Furthermore, the names and terms used are not intended to be limiting; other expressions that have substantially the same content and intent are also encompassed by the present invention. [Explanation of symbols]

[0123] 1...magnetic disk drive, 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.

Claims

1. Multiple heads that can read and write data independently and simultaneously; one or more microactuators provided in each of the heads, all of which can be controlled independently; a VCM for controlling each of the heads; a simultaneous on-track head determination unit that determines a final set of heads to be simultaneously on-track by using at least the displacement amount of the microactuator; a VCM target position determination unit that determines a target position of the VCM during simultaneous on-track; a VCM control switching unit that switches the VCM controller when simultaneously on-track; an MA control switching unit that switches a controller of a microactuator for each of the simultaneously on-track heads determined by the simultaneously on-track head determining unit; A magnetic disk device comprising:

2. 2. The magnetic disk drive according to claim 1, wherein the simultaneous on-track head determination unit determines the final set based on a first set of heads specified in an external simultaneous on-track request.

3. 2. The magnetic disk drive according to claim 1, wherein the simultaneous on-track head determination unit determines a first set of heads to be simultaneously on-track based on a data access request received from outside, and determines the final set based on the first set.

4. a first head included in the final set includes one or more first micro-actuators for controlling the first head; 4. A magnetic disk drive according to claim 2, wherein the first head is removed from the first set 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 displacement amounts of the one or more first microactuators.

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

6. 2. The magnetic disk drive according to claim 1, wherein 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 amount of one or more second microactuators that control the second head.

7. The magnetic disk drive of claim 1, wherein the MA control switching unit determines whether to switch between a first type microactuator or VCM control system that applies the maximum voltage that can be input through feedforward control and a second type microactuator that controls one or more third heads included in the final set, and a controller that takes into account the original characteristics of the microactuator control system that has been selected for feedforward control, and switches the controller.

8. The magnetic disk device described in claim 7, wherein the MA control switching unit controls the input voltage of one or more fourth microactuators that control the fourth heads included in the final set so that it does not exceed a maximum voltage, which is a maximum value of the input voltage predetermined for each of the fourth microactuators.

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