Magnetic disk device, control method for magnetic disk, and program

Abstract

To provide a magnetic disk device, a control method for the magnetic disk device, and a program to suppress vibrations of a magnetic head during microactuator switching, improve positioning accuracy, and prevent a decrease in access performance.SOLUTION: A magnetic disk device of an embodiment includes: a first MA amplifier that drives a first microactuator that positions a corresponding magnetic head; a second microactuator that positions the corresponding magnetic head; and a second MA amplifier that drives the second microactuator; in which a control unit is provided which starts an MA amplifier of a switching destination while keeping an MA amplifier of a switching source in an on state, when switching from the MA amplifier of the switching source, which is in the on state, to the MA amplifier of the switching destination, which is in an off state, and performs switching from the source MA amplifier to the destination MA amplifier after a predetermined time is elapsed.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] An embodiment of the present invention relates to a magnetic disk device, a control method for a magnetic disk device, and a program. [Background technology]

[0002] Conventionally, in order to improve the characteristics of the microactuator that positions the magnetic head in a HDD as a magnetic disk device, a function has been proposed to simultaneously drive multiple microactuators in order to shorten the processing time for SSW (Self Servo Write), which uses only the mechanical mechanisms of the HDD itself and an external circuit to write a product servo pattern. When such a configuration is adopted, one HDD has to have multiple microactuator amplifiers (MA amplifiers), which increases the standby power consumption in the environment in which the HDD product is actually used. To counter this problem, the MA amplifiers of magnetic heads that are not being used are turned off. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] U.S. Patent No. 9,007,714 [Patent Document 2] U.S. Pat. No. 1,393,496 [Patent Document 3] U.S. Patent No. 6,646,825 [Patent Document 4] Japanese Patent Application Publication No. 4-113850 Summary of the Invention [Problem to be solved by the invention]

[0004] In the prior art, the MA amplifier, which supplies the driving power to drive the microactuator, is switched on / off at the start of a seek. This switching causes vibrations in the suspension that holds the magnetic head, degrading the positioning accuracy of the magnetic head and degrading the random access performance of the HDD. To solve this problem, for example, technology has been proposed that provides a gradient in the MA amplifier voltage in the piezo drive circuit, but simply making the MA amplifier voltage gradient gentler takes a long time to switch, and ultimately results in a deterioration of the random access performance of the HDD.

[0005] The present invention has been made in consideration of the above, and aims to provide a magnetic disk device, a control method for a magnetic disk device, and a program that can suppress vibrations of a magnetic head that occur when switching a microactuator, improve positioning accuracy, and suppress deterioration of access performance. [Means for solving the problem]

[0006] The magnetic disk device of the embodiment is equipped with a first MA amplifier that drives a first microactuator that positions a corresponding magnetic head, a second microactuator that positions the corresponding magnetic head, and a second MA amplifier that drives the second microactuator, and is equipped with a control unit that, when switching from a source MA amplifier in an on state to a destination MA amplifier in an off state, starts up the destination MA amplifier while maintaining the source MA amplifier in an on state, and switches from the source MA amplifier to the destination MA amplifier after a predetermined time has elapsed. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an explanatory diagram of an example of a schematic configuration of a magnetic disk device according to an embodiment. [Diagram 2] FIG. 2 is a plan view of a schematic configuration example of the magnetic disk device according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating a conventional magnetic head change operation. [Figure 4] FIG. 4 is an explanatory diagram of the operation principle of the first embodiment. [Diagram 5] FIG. 5 is an explanatory diagram of the operation when changing the magnetic head in the first embodiment. [Figure 6] FIG. 6 is an explanatory diagram of a control data table used in the first embodiment. [Figure 7] FIG. 7 is a process flowchart of the switching process of the microactuator according to the embodiment. [Figure 8] FIG. 8 is an explanatory diagram of an example of switching of the MA amplifier in the first embodiment. [Figure 9] FIG. 9 is an explanatory diagram of an example of switching of the MA amplifier in the second embodiment. [Figure 10] FIG. 10 is an explanatory diagram of a control data table used in the third embodiment. [Figure 11] FIG. 11 is an explanatory diagram of an example of switching of the MA amplifier in the third embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] Hereinafter, embodiments will be described with reference to the drawings. [1] First embodiment FIG. 1 is an explanatory diagram of an example of a schematic configuration of a magnetic disk device according to an embodiment. The magnetic disk device 10 is, for example, a hard disk drive (HDD). However, the magnetic disk device 10 may be another type of magnetic disk device, such as a hybrid HDD.

[0009] The magnetic disk device 10 can be connected to the host 2 via a communication line. Here, the magnetic disk device 10 and the host 2 can communicate with each other via the communication line using a communication protocol conforming to the SAS (Serial Attached SCSI) standard, for example. Note that the standard of the communication line between the magnetic disk device 10 and the host 2 is not limited to this example.

[0010] The host 2 is configured as, for example, a processor, a personal computer, or a server. The magnetic disk device 10 can receive access commands (for example, read commands and write commands) from the host 2.

[0011] FIG. 2 is a plan view of a schematic configuration example of the magnetic disk device according to the embodiment. The magnetic disk device 10 includes a spindle motor (SPM) 11, a plurality of magnetic disks 12, a plurality of magnetic heads 13, an actuator unit 14, a ramp load mechanism 15, a head amplifier 16, an SoC 17, and a servo controller (SVC) 18.

[0012] The spindle motor 11 has a rotating shaft 19. A plurality of magnetic disks 12 are held by, for example, a clamp on this rotating shaft 19. The spindle motor 11 rotates the plurality of magnetic disks 12 together around the rotating shaft 19.

[0013] A recording surface on which data can be recorded is formed on both sides of the magnetic disks 12. The number of magnetic heads 13 is set so that the magnetic heads 13 can access the recording surfaces of the magnetic disks 12.

[0014] Each of the multiple magnetic heads 13 is provided so as to be able to face the recording surface of the corresponding magnetic disk 12. Each of the multiple magnetic heads 13 can record data to and reproduce data from the recording surface of the magnetic disk 12 that the magnetic head 13 faces. In FIG. 1, for the sake of simplicity and ease of understanding, six magnetic heads 13 are shown with magnetic head IDs H0 to H5, but in reality, many more magnetic heads 13 (e.g., 20) are provided.

[0015] As shown in FIG. 1, the actuator unit 14 includes a plurality of suspensions 21, a plurality of actuator arms 22, a rotating shaft 23, a voice coil motor (VCM) 24, and a plurality of microactuators (MA) 25.

[0016] Each of the suspensions 21 is formed in an elastically deformable plate shape. Each of the suspensions 21 supports a corresponding one of the magnetic heads 13 near the tip of the suspension 21.

[0017] One end of each of the multiple actuator arms 22 is supported by the rotation shaft 23 so as to be rotatable about the rotation shaft 23. To the other end of each of the multiple actuator arms 22, a corresponding one of the multiple suspensions 21 is attached.

[0018] The voice coil motor 24 rotates the actuator arm 22 and the suspension 21 attached to the actuator arm 22 within a predetermined range around a rotation shaft 23. The rotation shaft 19 of the SPM 11 and the rotation shaft 23 of the actuator unit 14 are disposed approximately parallel to each other and spaced apart from each other. Therefore, the voice coil motor 24 can move the magnetic head 13 supported by the suspension 21 relative to the magnetic disk 12 .

[0019] The voice coil motor 24 moves the actuator arm 22 substantially parallel to the recording surface of the magnetic disk 12. The voice coil motor 24 of this embodiment moves the magnetic head 13 relative to the magnetic disk 12 in a radial direction substantially perpendicular to the rotation axis 19.

[0020] The microactuator 25 is provided at the connection between the suspension 21 and the actuator arm 22. The microactuator 25 is, for example, an actuator element such as a piezoelectric element. The microactuator 25 can move the suspension 21 substantially parallel to the recording surface of the magnetic disk 12. That is, the actuator unit 14 is configured as a two-stage actuator in which the voice coil motor 24 and the microactuator 25 move the magnetic head 13.

[0021] In the above configuration, the numbers of suspensions 21, actuator arms 22 and microactuators 25 are set in accordance with the number of magnetic heads 13. Furthermore, the actuator unit 14 may have a plurality of voice coil motors 24.

[0022] The actuator unit 14 can move the magnetic head 13 along a locus T with respect to the recording surface of the magnetic disk 12 by using the voice coil motor 24 and the microactuator 25. A ramp load mechanism 15 is provided on the locus T near the outer edge of the magnetic disk 12. Therefore, the voice coil motor 24 can move the magnetic head 13 between the ramp load mechanism 15 and the rotation shaft 19.

[0023] For example, during unloading and retraction, the ramp load mechanism 15 parks the multiple magnetic heads 13. For example, the ramp load mechanism 15 supports a lift tab provided at the tip of the suspension 21, thereby enabling the magnetic heads 13 supported by the suspension 21 to be held in a retracted position.

[0024] 1 amplifies and outputs the signal read by the magnetic head 13 from the magnetic disk 12, and supplies the amplified signal to the SoC 17. The SoC 17 demodulates the signal supplied from the head amplifier 16 into digital data by a read channel circuit.

[0025] Furthermore, a signal corresponding to the digital data is supplied to the head amplifier 16 from the SoC 17. The head amplifier 16 amplifies the signal supplied from the SoC 17 and supplies it to the magnetic head 13. The magnetic head 13 records the signal supplied from the head amplifier 16 on the recording surface of the magnetic disk 12.

[0026] The SVC 18 controls the voice coil motor 24 and the microactuator 25 of the actuator unit 14. Specifically, the SVC 18 drives the actuator unit 14 based on an instruction from the SoC 17 to position the magnetic head 13 at a position instructed by the SoC 17.

[0027] Furthermore, the SVC 18 drives the spindle motor 11 based on an instruction from the SoC 17. The SVC 18 drives the spindle motor 11 so that the rotation speed of the spindle motor 11 is constant at a predetermined target speed.

[0028] The SVC 18 retracts the magnetic head 13 when the power supply to the magnetic disk device 10 is cut off. Furthermore, the SVC 18 may retract the magnetic head 13 when a seek error occurs in the positioning control of the magnetic head 13.

[0029] The SoC 17 is electrically connected to the host 2. The SoC 17 interprets an access command from the host 2, and executes various controls such as access to the magnetic disk 12 based on the interpretation result.

[0030] The SoC 17 has a micro-processing unit (MPU) 17a. The MPU 17a operates according to a firmware program. The firmware program is stored in a predetermined non-volatile storage area. The predetermined non-volatile storage area may be the magnetic disk 12 or a read-only memory (ROM) of the SoC 17.

[0031] The MPU 17a controls the overall operation of the magnetic disk device 10. For example, the MPU 17a controls access to the magnetic disk 12 using the magnetic head 13 via the head amplifier 16. The MPU 17a also instructs the SVC 18 to control the rotation of the spindle motor 11, and controls the loading / unloading of the actuator unit 14 via the SVC 18.

[0032] In the positioning control, the MPU 17a calculates a command value for the drive voltage of the VCM 24 and a command value for the drive voltage of the MA 25 in order to make the position of the magnetic head 13 follow the target position pos_target. The MPU 17a calculates each command value using the position signal pos read by the magnetic head 13 from the servo information formed on the recording surface of the magnetic disk 12 as a feedback input, and transmits each obtained command value to the SVC 18.

[0033] The SVC 18 applies a voltage corresponding to the command value of the drive voltage of the voice coil motor 24 to the voice coil motor 24, and applies a voltage corresponding to the command value of the drive voltage of the microactuator 25 to the microactuator 25. This positions the magnetic head 13 to the target position.

[0034] Before describing the operation of the embodiment, the problems associated with the prior art will be described. FIG. 3 is a diagram illustrating a conventional magnetic head change operation. In FIG. 3, the voltage applied from the MA amplifier to the microactuator (MA) when the microactuator is turned on is set to 10 V, and the voltage applied from the MA amplifier to the microactuator (MA) when the microactuator is turned off is set to 0 V.

[0035] In the example of Figure 3, when microactuator MA1, which is in the off state, is turned on and microactuator MA2, which is in the on state, is turned off, conventionally, the microactuators are switched by changing the output voltage of the MA amplifier at a first slew rate at time t10, which is immediately before time t11, which corresponds to the head change timing. More specifically, if the voltage output from the first MA amplifier to drive the microactuator MA1 is VMA11 and the voltage output from the second MA amplifier to drive the microactuator MA2 is VMA2, then at time t10, the voltage VMA1 output from the first MA amplifier is increased at a first slew rate, and the voltage VMA12 output from the second MA amplifier is decreased at the first slew rate. In this case, vibration occurs in the suspension that holds the magnetic head, and as shown in FIG. 3, the deviation of the magnetic head position from the target position PTG after the head change increases, resulting in a decrease in positioning accuracy.

[0036] Next, the operating principle of the first embodiment will be described. FIG. 4 is an explanatory diagram of the operation principle of the first embodiment. In Figure 4, the multiple magnetic heads 13 include n magnetic heads 13A whose magnetic head ID suffixes are even numbers (in the example of Figure 4, magnetic head IDs = H0, H2, H4, ..., H2n, where n is an integer greater than or equal to 0), and n magnetic heads 13B whose magnetic head ID suffixes are odd numbers (in the example of Figure 4, magnetic head IDs = H1, H3, H5, ..., H2n+1, where n is an integer greater than or equal to 0).

[0037] In the above configuration, the magnetic heads 13A are driven by the corresponding microactuators MA1, and the magnetic heads 13B are driven by the corresponding microactuators MA2.

[0038] Furthermore, all the microactuators MA1 are driven by power supplied from the first MA amplifier 30A. Similarly, all the microactuators MA2 are supplied with power and driven by the second MA amplifier 30B.

[0039] FIG. 5 is an explanatory diagram of the operation when changing the magnetic head in the first embodiment. Also in FIG. 5, when the microactuator 25 (MA1 or MA2) is turned on, the voltage applied to the microactuator 25 from the first MA amplifier 30A or the second MA amplifier 30B is set to 10 V, and when the microactuator 25 (MA1 or MA2) is turned off, the voltage applied to the microactuator 25 from the first MA amplifier 30A or the second MA amplifier 30B is set to 0 V.

[0040] 5, when the microactuator MA1 in the OFF state is turned ON and the microactuator MA2 in the ON state is turned OFF, the output voltage of the MA amplifier is changed by the absolute value of the second slew rate (<the absolute value of the first slew rate) at time t0 (t1-t0>t11-t10) before time t1 corresponding to the head change timing. Here, the first slew rate is the slope of the signal when it rises, and the second slew rate is the slope of the signal when it falls.

[0041] More specifically, when the first MA amplifier 30A turns the microactuator MA1, which is in the corresponding off state, to the on state, and the second MA amplifier 30B turns the microactuator MA2, which is in the corresponding on state, to the off state, the output voltage of the first MA amplifier 30A is increased from 0V to 10V at a first slew rate, and the output voltage of the second MA amplifier 30B is decreased from 10V to 0V at a second slew rate.

[0042] Then, the voltage VMA11 applied by the first MA amplifier 30A to the microactuator MA1 to be turned on is increased at a first slew rate from time t0, so that at time t1 the voltage of the voltage VMA11 becomes 10 V, which corresponds to the on state.

[0043] This state is further maintained, and when the vibration of the suspension holding the magnetic head decreases and stabilizes at time t2, the microactuator to be controlled is switched from microactuator MA2 to microactuator MA1.

[0044] In this case, from time t1 to time t2, both the microactuator MA1 and the microactuator MA2 are in the ON state. Then, at time t2, the voltage VMA12 applied by the second MA amplifier 30B to the microactuator MA2 to be turned off is gradually reduced at a second slew rate, so that at time t3, the voltage of the voltage VMA12 becomes 0 V, which corresponds to the off state.

[0045] By performing the above operations, the microactuator to be controlled is switched. However, even in this case, as shown in FIG. 4, vibrations occur in the suspension that holds the magnetic head 13B driven by the second MA amplifier 30B. However, according to the embodiment, compared to the case shown in Figure 3, the vibration is smaller, the deviation of the magnetic head position from the target position PTG after a head change is smaller than in the conventional case, and it can be seen that the positioning accuracy can be improved.

[0046] Next, the detailed operation of the first embodiment will be described. FIG. 6 is an explanatory diagram of a control data table used in the first embodiment. The control data table TB1 of the first embodiment includes magnetic head ID data 31 for identifying each magnetic head 12 and corresponding MA data 32 for identifying the microactuator corresponding to the magnetic head identified by the magnetic head ID data 31.

[0047] For example, the corresponding microactuator that drives a magnetic head identified by magnetic head ID="H1" is microactuator MA2, and the corresponding microactuator that drives a magnetic head identified by magnetic head ID="H4" is microactuator MA1. In other words, in FIG. 6, the first MA amplifier 30A drives multiple magnetic heads 13A identified by magnetic head IDs="H0", "H2", "H4", "H6", ... via the corresponding microactuator MA1. Similarly, the second MA amplifier 30B drives a plurality of magnetic heads 13B identified by magnetic head IDs "H1", "H3", "H5", "H7", ... via the corresponding microactuators MA2.

[0048] FIG. 7 is a process flowchart of the switching process of the microactuator according to the embodiment. The switching process of the microactuator is performed by the MPU 17 a of the SoC 17 controlling the SVC 18 . In the magnetic head allocation process, the SoC 17 refers to the control data table TB1 shown in FIG. 6 (step S11), and determines whether or not switching of the MA amplifier is necessary based on the contents of the control data table (step S12). If it is determined in step S12 that switching of the MA amplifier is not necessary (step S11; No), the process ends. If it is determined in step S12 that switching of the MA amplifier is necessary (step S12; Yes), the MA amplifier to be switched to is selected based on the control data table TB1 shown in FIG. 5 referenced in step S11 (step S13).

[0049] FIG. 8 is an explanatory diagram of an example of switching of the MA amplifier in the first embodiment. FIG. 8A shows the switching order of the MA amplifiers when rearranging the seek order in conventional NCQ (Native Command Queuing), and FIG. 8B shows the switching order of the MA amplifiers in the first embodiment. Conventionally, for example, if the data access order was magnetic head ID="H0" → magnetic head ID="H3" → magnetic head ID="H4" → magnetic head ID="H1" → magnetic head ID="H6" → magnetic head ID="H5" as shown in Figure 8(A), the microactuator to be turned on would be changed each time the magnetic heads were switched. As a result, vibrations were generated as shown in Figure 3, and the positioning accuracy was reduced. Therefore, in the first embodiment, when rearranging the seek order by NCQ, the SoC 17 performs control so as to give priority to the magnetic head driven by the same microactuator as the microactuator that is currently in the on state in the MA amplifier switching order.

[0050] In FIG. 8, a plurality of magnetic heads 13A identified by magnetic head IDs "H0", "H4", and "H6" are supplied with power by a first MA amplifier 30A and are each driven by a corresponding microactuator MA1. Similarly, a plurality of magnetic heads 13B identified by magnetic head IDs "H1", "H3", and "H5" are supplied with power by the second MA amplifier 30B and are each driven by a corresponding microactuator MA2.

[0051] That is, in the case corresponding to the case shown in Figure 8 (A), based on the control data table TB1 referenced in step S13, SoC17 first sets the data access order as shown in Figure 8 (B) if the microactuator currently in the on state is MA1, as follows: magnetic head ID = "H0" → magnetic head ID = "H4" → magnetic head ID = "H6" corresponding to microactuator MA1. Therefore, the microactuator MA1 is not switched to the off state during this series of data accesses.

[0052] Next, the SoC 17 selects the microactuator MA2 as the switching destination MA amplifier (step S13). 8B, the switching destination MA amplifier start-up process is performed to turn on the microactuator MA2 that is in the OFF state (step S14) in the same manner as in the case of Fig. 5. That is, the start-up process of the second MA amplifier 30B is performed. More specifically, the output voltage of the second MA amplifier 30B is increased at a first slew rate.

[0053] Then, it is determined whether or not a first predetermined time has elapsed since the voltage applied by the second MA amplifier 30B to the multiple microactuators MA2 to be turned on started to rise at the first slew rate (in the example of Figure 5, whether or not time t2 has been reached) (step S15). In the determination in step S15, when the first predetermined time has not elapsed (step S15; No), the device goes into a standby state.

[0054] If it is determined in step S15 that the first predetermined time has elapsed, the voltage applied to microactuator MA2 will have become a predetermined on-state voltage (10 V in the above example) and the vibrations will have become smaller, so the microactuator to be controlled is switched from microactuator MA1 to microactuator MA2 (step S16).

[0055] And, since the microactuator currently in the on state is microactuator MA2 driven by the second MA amplifier 30B, the data access order is magnetic head ID="H1" corresponding to microactuator MA2 → magnetic head ID="H3" → magnetic head ID="H5".

[0056] In parallel with these operations, the first MA amplifier 30A, which is the MA amplifier from which the switching is made, starts to fall (step S17). More specifically, the output voltage of the first MA amplifier 30A starts to fall at the second slew rate. Then, it is determined whether or not a second predetermined time has elapsed since the voltage applied by the first MA amplifier 30A to the microactuator MA1 to be turned off is decreased at the second slew rate (step S18).

[0057] In the determination in step S18, when the second predetermined time has not elapsed (step S18; No), the device goes into a standby state. If it is determined in step S18 that the second predetermined time has elapsed (step S18; Yes), the first MA amplifier 30A corresponding to the microactuator MA1 is turned off and put into the OFF state, and the process ends.

[0058] With the above-described configuration, in the conventional system shown in FIG. 8(A), the microactuator and therefore the MA amplifier had to be switched five times, whereas in the first embodiment shown in FIG. 8(B), the microactuator only needs to be switched once, thereby reducing the effects of switching the microactuator, i.e., the MA amplifier, and improving the positioning accuracy of the magnetic head.

[0059] In the above explanation, both the control shown in FIG. 5 and the control shown in FIG. 8(B) were performed, but even if only one of the controls is used, it is possible to reduce the effects of switching the microactuator and improve the positioning accuracy of the magnetic head.

[0060] [2] Second embodiment Next, a second embodiment will be described. FIG. 9 is an explanatory diagram of an example of switching of the MA amplifier in the second embodiment. FIG. 9A shows the switching order of the MA amplifiers during conventional sequential access, and FIG. 9B shows the switching order of the MA amplifiers during sequential access in the second embodiment. Here, sequential access usually refers to a process of accessing areas in ascending order of LBA (Logic Block Address). FIG. 9 also shows that a plurality of magnetic heads 13A identified by magnetic head IDs "H0", "H2", ..., "H18" corresponding to a plurality of microactuators MA1 to which power is supplied to the first MA amplifier 30A are driven. Similarly, it indicates that a plurality of magnetic heads 13B identified by magnetic head IDs = "H1", "H3", ..., "H19" corresponding to a plurality of microactuators MA2 supplied with power by the second MA amplifier 30B are being driven.

[0061] Therefore, in this second embodiment, when switching from a source MA amplifier in the on state to a destination MA amplifier in the off state, logical addresses are assigned in advance so that during sequential access, the magnetic head using the source MA amplifier is ordered first and the magnetic head using the destination MA amplifier is ordered last. That is, in the above example, the LBAs are arranged from smaller to larger so that the order of the magnetic heads 13A identified by magnetic head IDs = "H0", "H2", ..., "H18" corresponding to the multiple microactuators MA1 supplied with power by the first MA amplifier 30A is followed by the order of the multiple magnetic heads 13B identified by magnetic head IDs = "H1", "H3", ..., "H19" corresponding to the multiple microactuators MA2 supplied with power by the second MA amplifier 30B.

[0062] In the following, reference will again be made to the processing flowchart of FIG. For example, suppose that in the past, the data access order was as follows, as shown in Figure 9(A), magnetic head ID="H0" → magnetic head ID="H2" → magnetic head ID="H4" → ... → magnetic head ID="H16" → magnetic head ID="H17" → magnetic head ID="H18".

[0063] In this case as well, similarly to the first embodiment, switching of the corresponding microactuator occurs frequently, causing vibration as shown in FIG. 3 and deteriorating positioning accuracy.

[0064] That is, in the case corresponding to the case shown in Figure 9(A), first, as shown in Figure 9(B), when the microactuator currently in the on state is MA1, that is, when the MA amplifier currently supplying power is the first MA amplifier 30A, logical addresses are assigned in advance so that the data access order is magnetic head ID="H0" corresponding to microactuator MA1 → magnetic head ID="H2" → magnetic head ID="H4" → ... → magnetic head ID="H18".

[0065] Next, SoC17 refers to the control data table TB1 (step S12), and when access to the magnetic head corresponding to microactuator MA1 is completed, selects a second MA amplifier 30B corresponding to multiple microactuators MA2 as the destination MA amplifier based on the order of sequential access (step S13).

[0066] 9B, the switching destination MA amplifier start-up process is performed to turn on the microactuator MA2 from the OFF state (step S14) in the same manner as in the case of Fig. 4. That is, the start-up process of the second MA amplifier 30B is performed. More specifically, the output voltage of the second MA amplifier 30B is increased at a first slew rate.

[0067] Then, it is determined whether or not a first predetermined time has elapsed since the output voltage of the second MA amplifier 30B started to increase at the first slew rate (step S15). In the determination in step S15, when the first predetermined time has not elapsed (step S15; No), the device goes into a standby state.

[0068] If it is determined in step S15 that the first predetermined time has elapsed (step S15; Yes), the voltage applied to microactuator MA2 will have become a predetermined on-state voltage (10 V in the above example) and the vibrations will have become smaller, so the microactuator to be controlled is switched from microactuator MA1 to microactuator MA2 (step S16).

[0069] And since the microactuator that is currently in the ON state is microactuator MA2, the data access order according to the specified logical address is magnetic head ID="H19" corresponding to microactuator MA2 → magnetic head ID="H17" → ... → magnetic head ID="H1".

[0070] In parallel with these operations, the first MA amplifier 30A, which is the MA amplifier from which the switching is made, starts to fall (step S17). More specifically, the output voltage of the first MA amplifier 30A starts to fall at the second slew rate. Then, the voltage applied to the microactuator MA1 to be turned off is decreased at a second slew rate, and it is determined whether or not a second predetermined time has elapsed (step S18). In the determination in step S18, if the second predetermined time has not elapsed (step S18; No), the process goes to a standby state. If it is determined in step S18 that the second predetermined time has elapsed, the first MA amplifier 30A corresponding to the microactuator MA1 is turned off, and the process ends.

[0071] According to the above-described configuration, whereas in the conventional system shown in FIG. 9(A), the microactuator needs to be switched multiple times, in the first embodiment shown in FIG. 9(B), the microactuator needs to be switched only once, thereby reducing the effects of switching the microactuator even during sequential access, and improving the positioning accuracy of the magnetic head.

[0072] [3] Third embodiment Next, a third embodiment will be described. FIG. 10 is an explanatory diagram of a control data table used in the third embodiment. The control data table TB2 of the third embodiment includes magnetic head ID data 41 for identifying each magnetic head, corresponding MA data 42 for identifying the microactuator corresponding to the magnetic head identified by the magnetic head ID data 41, and vibration rank data 43 that stores the vibration level at the time when the microactuator starts to be driven. In this case, the vibration level refers to a number of levels of vibration magnitude in the magnetic head 13. In the above configuration, the vibration rank data is determined in advance by measurement. In the example of FIG. 9, there are three ranks: vibration rank "S", which is the rank with the least vibration amount and where the vibration amount is less than a first predetermined vibration amount; vibration rank "L", which is the rank with the greatest vibration amount and where the vibration amount is even greater than a second predetermined vibration amount that is greater than the first predetermined vibration amount; and vibration rank "M", which is the rank with the vibration amount equal to or greater than the first predetermined vibration amount and equal to or less than the second vibration amount.

[0073] For example, the corresponding microactuator that drives a magnetic head identified by magnetic head ID="H0" is microactuator MA1, and the corresponding vibration rank is set to "S". Also, the corresponding microactuator that drives a magnetic head identified by magnetic head ID="H3" is microactuator MA2, and the corresponding vibration rank is set to "M". Furthermore, the corresponding microactuator that drives a magnetic head identified by magnetic head ID="H18" is microactuator MA1, and the corresponding vibration rank is set to "L".

[0074] FIG. 11 is an explanatory diagram of an example of switching of the MA amplifier in the third embodiment. FIG. 11(A) shows the switching order of the MA amplifiers during conventional sequential access, and FIG. 11(B) shows the switching order of the MA amplifiers during sequential access in the third embodiment. In the following, reference will again be made to the processing flowchart of FIG. In the past, for example, as shown in Figure 11 (A), the data access order was as follows: magnetic head ID = "H0":MA1: vibration rank = "S" → magnetic head ID = "H1":MA2: vibration rank = "S" → magnetic head ID = "H2":MA1: vibration rank = "M" → magnetic head ID = "H3":MA2: vibration rank = "M" → ... → magnetic head ID = "H16":MA1: vibration rank = "S" → magnetic head ID = "H17":MA2: vibration rank = "S" → magnetic head ID = "H18":MA1: vibration rank = "L" → magnetic head ID = "H19":MA2: vibration rank = "L". In this case, as in the first embodiment, the corresponding microactuator is frequently switched, and after the switching, an MA amplifier with a higher vibration rank is driven, which may cause more vibration as shown in FIG. 3, and may result in longer periods of poor positioning accuracy. Therefore, in this third embodiment, when switching the MA amplifier in the case of rearranging the seek order during sequential access, the LBA allocation is changed so that the magnetic head driven by the microactuator with the lowest vibration rank among the selectable microactuators is used when switching the microactuator to be turned on next.

[0075] First, in the magnetic head allocation process, the SoC 17 refers to the control data table TB1 shown in FIG. 5 (step S11), and determines whether or not switching of the MA amplifier is necessary based on the contents of the control data table (step S12). If it is determined in step S12 that switching of the MA amplifier is not necessary (step S12; No), the process ends. If it is determined in step S12 that the MA amplifier needs to be switched (step S12; Yes), the control data table TB1 shown in FIG. 5 is again referred to (step S13). That is, in the case shown in Figure 11 (A), SoC17 refers to control data table TB2, and as shown in Figure 11 (B), first, if the microactuator currently in the on state is MA1, the data access order is set as follows: magnetic head ID = "H0":MA1: vibration rank = "S" corresponding to microactuator MA1 → magnetic head ID = "H2":MA1: vibration rank = "S" → ... → magnetic head ID = "H18":MA1: vibration rank = "L" → magnetic head ID = "H16":MA1: vibration rank = "S".

[0076] Next, when the SoC 17 finishes accessing the magnetic head corresponding to the microactuator MA1, it selects the microactuator MA2 as the switching destination MA amplifier (step S13). Next, in the case shown in FIG. 11(B), similarly to the case of FIG. 5, a switching destination MA amplifier start-up process is performed to turn on the microactuator MA2 that is in the OFF state (step S14).

[0077] Then, the voltage applied to the microactuator MA2 to be turned on is increased at a first slew rate, and it is determined whether or not a first predetermined time has elapsed (step S15). If it is determined in step S15 that the first predetermined time has elapsed, the voltage applied to microactuator MA2 will have become a predetermined on-state voltage (10 V in the above example) and the vibrations will have become smaller, so the microactuator to be controlled is switched from microactuator MA1 to microactuator MA2 (step S16).

[0078] And, since the microactuator that is currently in the on state is microactuator MA2, the data access order is set as follows: magnetic head ID="H17" :MA2: vibration rank="S" corresponding to microactuator MA2 → magnetic head ID="H19" :MA2: vibration rank="L" → ... → magnetic head ID="H1" :MA2: vibration rank="S". Therefore, in the case of the above example, when the microactuator is switched, the magnetic head corresponding to the vibration rank="S" is the switching target, so that the switching time of the microactuator can be shortened and the positioning accuracy can be improved.

[0079] In parallel with these operations, the source MA amplifier is turned off (step S17), the voltage applied to the microactuator MA1 to be turned off is decreased at a second slew rate, and it is determined whether a second predetermined time has elapsed (step S18). If it is determined in step S18 that the second predetermined time has not elapsed (step S19; No), the device goes into a standby state. If it is determined in step S18 that the second predetermined time has elapsed, the MA amplifier corresponding to the microactuator MA1 is turned off and put into the OFF state, and the process ends.

[0080] According to the above-described configuration, whereas in the conventional embodiment shown in FIG. 11(A), the microactuator needs to be switched multiple times, in the third embodiment shown in FIG. 11(B), the microactuator needs to be switched only once, thereby reducing the effects of switching the microactuator even during sequential access, and improving the positioning accuracy of the magnetic head.

[0081] [4] Fourth embodiment The above describes each microactuator and the MA amplifier corresponding to that microactuator. However, as shown in FIG. 1, a magnetic disk 12 faces each of the actuator arms 22 other than the top actuator arm 22 and the bottom actuator arm 22 in FIG. 1 in the vertical direction, and therefore a magnetic head 13 is provided on each of the magnetic disks 12. In the fourth embodiment, the microactuators 25 corresponding to the pair of upper and lower magnetic heads 13 can be controlled independently and are exclusively turned on.

[0082] Here, a pair of upper and lower heads refers to magnetic heads 13 being provided on a first surface of one actuator arm 22 (for example, the upper surface of actuator arm 22 in FIG. 1) and a second surface (in the above example, the lower surface of actuator arm 22 in FIG. 1) that is opposite to the first surface and in a direction intersecting the recording surface of magnetic disk 12 with respect to the first surface. More specifically, a magnetic head 13B is provided on the first surface, and a magnetic head 13A is provided on the second surface.

[0083] In this case, of the second MA amplifier 30B that drives the microactuator 25 (=microactuator MA2) corresponding to the magnetic head 13B provided on the upper surface side of the actuator arm 22, and the first MA amplifier 30A that drives the microactuator 25 (=microactuator MA1) corresponding to the magnetic head 13A provided on the lower surface side of the actuator arm 22, one of the MA amplifiers that is in the on state is the MA amplifier to be switched from, and the other is the MA amplifier to be switched to.

[0084] Furthermore, when switching from a source MA amplifier to a destination MA amplifier that is in the off state, it is desirable to set the voltage slew rate (slew rate at the time of rising) when switching an MA amplifier in the off state to the on state and the voltage slew rate (slew rate at the time of falling) when switching an MA amplifier in the on state to the off state to values ​​that avoid the resonant frequency of the corresponding microactuator.

[0085] This makes it possible to suppress vibrations of the microactuator that accompany switching of the MA amplifier, and in turn prevents a decrease in access performance. As a result, also in the fourth embodiment, the influence of vibrations caused by switching of the microactuator can be reduced, and the positioning accuracy of the magnetic head can be improved. Furthermore, it is possible to provide a magnetic disk drive capable of high-speed access by suppressing an increase in access time that accompanies switching of the microactuator.

[0086] As described above, according to each embodiment, the influence of vibrations caused by switching of the microactuator can be reduced, and the positioning accuracy of the magnetic head can be improved. Furthermore, it is possible to provide a magnetic disk drive capable of high-speed access by suppressing an increase in access time that accompanies switching of the microactuator.

[0087] The programs executed by the SoC of this embodiment are provided in a state that they are pre-installed in a ROM or the like.

[0088] The program executed by the magnetic disk device of this embodiment may be configured to be provided by recording it in an installable or executable format on a computer-readable recording medium such as a USB memory, a semiconductor memory device such as an SSD (Solid State drive), or a DVD (Digital Versatile Disk).

[0089] Furthermore, the program executed by the magnetic disk device of the present embodiment may be stored on a computer connected to a network such as the Internet and provided by being downloaded via the network. Also, the program executed by the magnetic disk device of the present embodiment may be provided or distributed via a network such as the Internet.

[0090] Although some embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included in the scope and spirit of the invention, and are included in the scope of the invention and its equivalents described in the claims.

[0091] For example, it is possible to reduce the frequency of switching the microactuator by limiting switching of the microactuator to only when a long distance seek occurs. Furthermore, although the above explanation has been given with respect to the case where two microactuators (MA1, MA2) driven by two different MA amplifiers are switched, it is also possible to switch between three or more microactuators (three or more systems) driven by three or more different MA amplifiers.

[0092] Furthermore, the rise and fall of the MA amplifier may not only have a constant slope, but may also be such that the output voltage rises or falls in a stepped manner, as shown by the dotted thin line Lstp in Fig. 5. In this case, the number of steps (number of stages) and the height of each step can be set appropriately from the viewpoint of suppressing vibration. [Explanation of symbols]

[0093] 10 Magnetic disk device 11 Spindle motor 12 Magnetic Disk 13 Magnetic Head 14 Actuator unit 15 Ramp load mechanism 16 Head Amplifier 17 SoC 17a MPU 18 SVC 19 Rotational Axis 21 Suspension 22 Actuator Arm 23 Rotation axis 24 Voice coil motor 25 Microactuators 30A 1st MA amplifier 30B 2nd MA amplifier 31 Magnetic head ID data 32 Compatible MA data 41 Magnetic head ID data 42 Compatible MA data 43 Vibration Rank Data MA1 Micro Actuator MA2 Micro Actuator TB1, TB2 Control data table

Claims

1. A magnetic disk drive including a first MA amplifier for driving a first microactuator for positioning a corresponding magnetic head, a second microactuator for positioning the corresponding magnetic head, and a second MA amplifier for driving the second microactuator, A magnetic disk device equipped with a control unit that, when switching from a source MA amplifier in an on state to a destination MA amplifier in an off state, starts up the destination MA amplifier while maintaining the source MA amplifier in an on state, and switches from the source MA amplifier to the destination MA amplifier after a predetermined time has elapsed.

2. The predetermined time is set as a time during which vibration caused by switching of the microactuator corresponding to the switching destination MA amplifier becomes less than a predetermined magnitude.

2. The magnetic disk drive according to claim 1.

3. The control unit controls the MA amplifier to increase the driving force stepwise at a predetermined slew rate or a predetermined ratio.

2. The magnetic disk drive according to claim 1.

4. A magnetic disk drive including a first MA amplifier for driving a first microactuator for positioning a corresponding magnetic head, a second microactuator for positioning the corresponding magnetic head, and a second MA amplifier for driving the second microactuator, the magnetic head is provided on a first surface of one actuator arm and on a second surface opposite to the first surface in a direction intersecting a recording surface of the magnetic disk, a pair of microactuators corresponding to the magnetic heads corresponding to the actuator arms are independently controllable and are exclusively turned on; a control unit that, of a pair of MA amplifiers corresponding to the pair of magnetic heads, one of the MA amplifiers in an ON state is set as a switching source MA amplifier and the other is set as a switching destination MA amplifier, and switches from the switching source MA amplifier to the switching destination MA amplifier in an OFF state; the control unit sets a voltage slew rate when switching the MA amplifier in the OFF state to an ON state and a voltage slew rate when switching the MA amplifier in the ON state to an OFF state to values ​​that avoid a resonance frequency of the corresponding microactuator. Magnetic disk device.

5. A magnetic disk drive including a first MA amplifier for driving a first microactuator for positioning a corresponding magnetic head, a second microactuator for positioning the corresponding magnetic head, and a second MA amplifier for driving the second microactuator, A magnetic disk device having a control unit that rearranges the seek order of the magnetic heads and, when switching from a source MA amplifier in an on state to a destination MA amplifier in an off state in accordance with the rearranged seek order, arranges the magnetic heads that use the source MA amplifier in earlier order and arranges the magnetic heads that use the destination MA amplifier in later order in the rearrangement.

6. During sequential access, logical addresses are assigned in advance so that magnetic heads driven by the same MA amplifier are accessed consecutively.

5. The magnetic disk drive according to claim 1.

7. A vibration level when switching to the microactuator is classified into a plurality of ranks in advance, When switching the MA amplifier, the control unit selects an MA amplifier that belongs to a rank with the least vibration as an MA amplifier that can be selected as a switching destination MA amplifier.

5. The magnetic disk drive according to claim 1.

8. the control unit switches the MA amplifier when a long distance seek of a predetermined distance or more occurs.

5. The magnetic disk drive according to claim 1.

9. A method for controlling a magnetic disk drive having a plurality of sets of microactuators for positioning a magnetic head and corresponding MA amplifiers, comprising: When switching from a source MA amplifier in an on state to a destination MA amplifier in an off state, maintaining the source MA amplifier in an on state; A step of starting up the MA amplifier to be switched to at a predetermined slew rate while maintaining the MA amplifier to be switched to in an on state; a step of switching from the source MA amplifier to the destination MA amplifier after a predetermined time has elapsed in which vibrations caused by switching of the microactuator corresponding to the destination MA amplifier become less than a predetermined magnitude; A method for controlling a magnetic disk device comprising the steps of:

10. A method for controlling a magnetic disk drive including a first MA amplifier for driving a first microactuator for positioning a corresponding magnetic head, a second microactuator for positioning the corresponding magnetic head, and a second MA amplifier for driving the second microactuator, comprising the steps of: When rearranging the seek order of the magnetic head, In the rearrangement, a step of arranging the magnetic heads using the MA amplifier from which the switching is made in a first order and arranging the magnetic heads using the MA amplifier to which the switching is made in a latter order; switching from a source MA amplifier in an on state to a destination MA amplifier in an off state according to the rearranged seek order; A method for controlling a magnetic disk device comprising the steps of:

11. A program for controlling a magnetic disk device by a computer, the magnetic disk device including a first MA amplifier for driving a first microactuator for positioning a corresponding magnetic head, a second microactuator for positioning the corresponding magnetic head, and a second MA amplifier for driving the second microactuator, The computer, A means for maintaining the source MA amplifier in an on state when switching from a source MA amplifier in an on state to a destination MA amplifier in an off state; A means for starting up the MA amplifier to be switched to at a predetermined slew rate while maintaining the MA amplifier to be switched to in an on state; a means for switching from the source MA amplifier to the destination MA amplifier after a predetermined time has elapsed in which vibrations caused by switching of the microactuator corresponding to the destination MA amplifier become less than a predetermined magnitude; A program that makes it work.

12. A program for controlling a magnetic disk device by a computer, the magnetic disk device including a first MA amplifier for driving a first microactuator for positioning a corresponding magnetic head, a second microactuator for positioning the corresponding magnetic head, and a second MA amplifier for driving the second microactuator, The computer, When rearranging the seek order of the magnetic head, a means for arranging the magnetic heads using the MA amplifier from which the switching is made in the first order and arranging the magnetic heads using the MA amplifier to which the switching is made in the second order in the rearrangement; a means for switching from an MA amplifier in an ON state to an MA amplifier in an OFF state according to the rearranged seek order; A program that makes it work.

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