Disk device

Abstract

The invention provides a disk device capable of reducing power consumption. In the disk device, when there is a rotation waiting time, a controller increases an absolute value of a motor current in a first interval of a first period, changes the absolute value of the motor current at a first average change rate in a second interval subsequent to the first interval, and decreases the absolute value of the motor current at a second average change rate in a third interval subsequent to the second interval. The absolute value of the motor current is reduced at a third average rate of change in a fourth section following the third section. When there is no rotation waiting time, the controller increases the absolute value of the motor current in a fifth section of the second period, changes the absolute value of the motor current at a fourth average change rate in a sixth section subsequent to the fifth section, and decreases the absolute value of the motor current at a fifth average change rate in a seventh section subsequent to the sixth section. The second period is a period during which the head is accelerated or decelerated. The fifth average change rate is more rapid than the fourth average change rate.

Description

[0001] This application claims the priority of Japanese Patent Application No. 2023-121460 (filing date: July 26, 2023) as a basic application. The present application incorporates the entire contents of the basic application by reference. Technical Field

[0002] The present embodiment relates to a disk device. Background Art

[0003] A disk device having a motor realizes a predetermined control operation by supplying driving power to the motor. In this case, it is desirable to reduce power consumption in the disk device. Summary of the invention

[0004] An embodiment of the present invention provides a disk device capable of reducing power consumption.

[0005] The disk device according to the embodiment provides a disk device having a head, a disk, a motor, and a controller. The disk has a recording surface. The motor causes the head to seek along the recording surface. The controller increases the absolute value of the motor current in the first interval of the first period, changes the absolute value of the motor current at a first average change rate in the second interval of the first period later than the first interval, decreases the absolute value of the motor current at a second average change rate in the third interval of the first period later than the second interval, and decreases the absolute value of the motor current at a third average change rate in the fourth interval of the first period later than the third interval. The rotational waiting time is the time from when the head reaches the target track of the disk until it reaches the target sector. The first period is a period for accelerating or decelerating the head. The second average change rate is steeper than the first average change rate. The third average change rate is steeper than the second average change rate. In the absence of the rotation waiting time, the controller increases the absolute value of the motor current in the fifth section of the second period, changes the absolute value of the motor current at the fourth average change rate in the sixth section of the second period later than the fifth section, and decreases the absolute value of the motor current at the fifth average change rate in the seventh section of the second period later than the sixth section. The second period is a period in which the head is accelerated or decelerated. The fifth average change rate is steeper than the fourth average change rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0006] Figure 1 It is a diagram showing the structure of a disk device according to the embodiment.

[0007] Figure 2 It is a diagram showing a seek operation in the embodiment.

[0008] Figure 3 It is a diagram showing the definition of the seek period and each section thereof in the embodiment.

[0009] Figure 4It is a diagram showing an equivalent circuit of the VCM in the embodiment.

[0010] Figure 5 3 is a diagram showing a VCM current waveform when there is no rotation waiting time in the embodiment.

[0011] Figure 6 1 is a diagram showing a VCM current waveform when a rotation waiting time is provided in the embodiment.

[0012] Figure 7 1 is a diagram showing a VCM current waveform when a rotation waiting time is provided in the embodiment.

[0013] Figure 8 1 is a diagram showing a VCM current waveform in a case where a rotation waiting time is provided in a first modification of the embodiment.

[0014] Fig. 9 FIG. 2 is a diagram showing a VCM current waveform in a case where a rotation waiting time is provided in a second modification of the embodiment.

[0015] Fig.10 It is a diagram showing the functional structure of the JIT seek control unit in the third variant of the implementation method.

[0016] Fig.11 It is a diagram showing the functional configuration of a servo control unit in a third modified example of the embodiment.

[0017] Fig.12 It is a diagram showing the functional structure of the JIT seek control unit in the fourth variant of the implementation method.

[0018] Fig.13 It is a diagram showing the configuration of a servo control unit in a fourth modified example of the embodiment.

[0019] Fig.14 It is a diagram showing the functional structure of the JIT seek control unit in the fifth variant of the implementation method.

[0020] Fig.15 It is a diagram showing the configuration of a servo control unit in a fifth variation of the embodiment.

[0021] Fig.16 It is a diagram showing the functional structure of the JIT seek control unit in the sixth variant of the implementation method.

[0022] Fig.17 It is a diagram showing the configuration of a servo control unit in a sixth variation of the embodiment.

[0023] Description of Reference Numerals

[0024] 1 disk device; 3 controllers; 13 VCM; H head. DETAILED DESCRIPTION

[0025] Hereinafter, a disk device according to an embodiment will be described in detail with reference to the drawings. However, the present invention is not limited to the embodiment.

[0026] (Implementation Method)

[0027] The disk device according to the embodiment includes a motor, and a predetermined control operation is implemented by supplying driving power to the motor, thereby reducing power consumption in the disk device.

[0028] like Figure 1 As shown, the disk device 1 includes a head disk assembly (HDA) 10 , a motor driver 20 , a head amplifier 30 , a controller 3 , a volatile memory 70 , a buffer memory 80 , and a nonvolatile memory 90 . Figure 1 1 is a diagram showing the structure of the disk device 1. The controller 3 includes a read / write channel (RWC) 40, a microprocessor unit (MPU) 50, and a hard disk controller (HDC) 60.

[0029] The HDA 10 includes a case 10a, a head H, an arm AM, a disk DK, a spindle motor 12, a voice coil motor (VCM) 13, a bearing 14, and a frame HS. In the frame HS, a lower case HSa and an upper case HSb (not shown) are fitted. The head H, the arm AM, the disk DK, the spindle motor 12, the voice coil motor (VCM) 13, and the bearing 14 are accommodated in the frame HS.

[0030] The disk DK has a recording surface S on the front and back sides thereof for recording data. The disk DK is driven to rotate by a spindle motor 12. A plurality of disks DK are provided in the disk device 1. Figure 1 In the example, for simplicity, a configuration in which one disk DK is provided is illustrated. In addition, physical addresses are set for all recording surfaces S used in the disk device 1. The physical addresses are position information indicating physical positions on the recording surfaces S. The spindle motor 12 is driven by current (or voltage) supplied from the motor driver 20.

[0031] The head H is provided for each recording surface S of the disk DK. The head H includes a write head WH and a read head RH. The write head WH is used to write data to the disk DK. The read head RH is used to read data from the disk DK.

[0032] The arm AM supports the head H and is provided relative to each head H. The VCM 13 is driven by a current (or voltage) supplied from the motor driver 20. The arm AM and the VCM 13 constitute an actuator. The actuator is driven by the VCM 13 to make the arm AM perform a seek movement in a circumferential direction around the bearing 14, and to perform positioning control on the recording surface S of the disk DK. The arm AM may also be connected to the recording surface S of the disk DK via the suspension 15 (see FIG. Figure 2 ) is also provided with a microactuator MA that can be driven independently from the VCM13.

[0033] The motor driver 20 controls each movable part of the HDA 10 under the control of the controller 3. The motor driver 20 includes an SPM control unit 201, a VCM control unit 202, and an MA control unit 203.

[0034] The SPM control unit 201 supplies current (or voltage) to the spindle motor 12 to drive the spindle motor 12 at a predetermined rotation speed.

[0035] The VCM control unit 202 supplies current (or voltage) to the VCM 13 to drive the actuator, thereby performing positioning control on the head H along the radial direction of the disk DK.

[0036] The MA control unit 203 supplies current (or voltage) to the microactuator MA to drive the microactuator MA and finely adjust the position of the head H along the radial direction of the disk DK.

[0037] The head amplifier 30 supplies a write signal (current) corresponding to write data input from the RWC 40 to the head H. The head amplifier 14 amplifies a read signal output from the head H (read data read from the disk DK by the head H) and supplies the amplified signal to the RWC 40.

[0038] The RWC 40 is a signal processing circuit and encodes (code modulates) write data input from the HDC 60 and outputs the data to the head amplifier 30 . The RWC 40 also decodes (code demodulates) read data from a read signal transmitted from the head amplifier 30 and outputs the data to the HDC 60 .

[0039] The MPU 50 controls the entire disk device 1 according to the firmware stored in the nonvolatile memory 90 or the disk DK. The firmware includes initial firmware that is first executed when the disk device 1 is activated and control firmware used in normal operation of the disk device 1.

[0040] In addition, the controller 3 including the RWC 16 , the HDC 60 and the MPU 50 may be configured as a one-chip integrated circuit (system on chip). The package of the controller 3 may be arranged on a printed circuit board outside the housing of the HDA 10 .

[0041] The HDC 60 controls data transmission and reception with the host system 2 via the I / F bus. The HDC 60 includes a host interface (host I / F) circuit (not shown). The HDC 60 receives commands from the host system 2 and performs command processing. Based on the results of the command processing, the HDC 60 performs servo control including seek control and tracking control.

[0042] The HDC 60 includes a command processing unit 61 and a servo control unit 64 .

[0043] When receiving a write command including a logical address and write data from the host system 2, the command processing unit 61 performs command processing on the write command. The command processing unit 61 converts the logical address included in the write command into a physical address. The command processing unit 61 obtains the target track and target sector corresponding to the logical address. The command processing unit 61 provides command information including the target track and target sector to the servo control unit 64. The command processing unit 61 provides the write data to the head H via the RWC 40 and the head amplifier 30. When the writing of the write data to the target sector by the head H is completed, the command processing unit 61 returns a write completion notification to the host system 2.

[0044] When the command processing unit 61 receives a read command including a logical address from the host system 2, it processes the read command. The command processing unit 61 converts the logical address included in the read command into a physical address. The command processing unit 61 obtains the target track and target sector corresponding to the logical address. The command processing unit 61 provides the servo control unit 64 with command information including the target track and target sector. After the head H reads the read data from the target sector, the command processing unit 61 returns the read data to the host system 2.

[0045] The command processing unit 61 includes a command queue control unit 611 and a reordering control unit 612 .

[0046] The command queue control unit 611 generates a command queue on the volatile memory 70 or the buffer memory 80. The command queue control unit 611 enqueues a command received from the host system 2 into the command queue. The command queue control unit 611 dequeues the head command in the command queue.

[0047] The reorder control unit 612 performs reordering using a predetermined condition as a trigger. For example, the reorder control unit 612 rearranges the commands in the command queue so that the commands with the nearest physical addresses are queued in order.

[0048] The servo control section 64 includes a seek control section 62 and a tracking control section 63 .

[0049] The seek control unit 62 obtains command information including a target track and a target sector from the command processing unit 61. The seek control unit 62 performs seek control to move the head H to the target track based on the command information. For example, the seek control unit 64 obtains servo information from the head H via the head amplifier 30 and the RWC 40, and finds the current position of the head H based on the servo information. The seek control unit 64 determines the trajectory (track) of the head H to the target track based on the current position of the head H. The seek control unit 64 determines the current indication value based on the trajectory of the head H, and provides it to the VCM control unit 202 via the MPU 50. The VCM control unit 202 supplies current (or voltage) to the VCM 13 based on the current indication value to drive the actuator. As a result, the head H is positioned along the radial direction of the disk DK.

[0050] The seek control unit 62 can perform the fastest seek control or JIT (Just In Time) seek control as seek control.

[0051] The fastest seek control is a control without rotation waiting time. In the fastest seek control, control is performed so that the head H moves to the target sector of the target track as quickly as possible. The fastest seek control can achieve the shortest time from the start of the seek until the head H reaches the target sector of the target track.

[0052] JIT seek control is a control with a rotation wait time. In JIT seek control, control is performed so that the head H moves to the target sector of the target track using the rotation wait time. In JIT seek control, there is a rotation wait of the disk DK from the start of seek until the head H reaches the target sector after reaching the target track.

[0053] The seek control unit 62 includes a fastest seek control unit 621 and a JIT seek control unit 622 .

[0054] The fastest seek control unit 621 performs the fastest seek control according to the command information. The fastest seek control unit 621 controls the input current to the VCM 13 to move the head H from the current position to the position of the target sector of the target track at a high speed.

[0055] For example, the motion acceleration data may be stored in the nonvolatile memory 90 in advance. The motion acceleration data is time series data of the motion acceleration of the head H that can move fastest based on the relationship between the moving distance and the moving time of the head H during seek control. When receiving the command, the fastest seek control unit 621 refers to the motion acceleration data and determines the motion acceleration of the head H from the current position to the position of the target sector of the target track. The fastest seek control unit 621 determines the current instruction value according to the motion acceleration and provides it to the VCM 13. Thus, the fastest seek control unit 621 performs the fastest seek control.

[0056] Alternatively, the parameters may be stored in the nonvolatile memory 90 in advance, and the motion acceleration formula may be set in the firmware. The motion acceleration formula may also be a function formula that represents the motion acceleration of the head H that can move fastest based on the relationship between the moving distance and the moving time of the head H during seek control. When receiving the command, the fastest seek control unit 621 obtains the parameters and applies them to the motion acceleration formula to calculate the motion acceleration of the head H. The fastest seek control unit 621 determines the current indication value based on the motion acceleration and provides it to the VCM 13. Thus, the fastest seek control unit 621 performs the fastest seek control.

[0057] The seek control unit 62 may also receive command information, estimate the time until the head H moves to the target track in the fastest seek mode, and determine whether the rotation wait of the disk DK occurs based on the estimation result. The seek control unit 62 may also perform the determination of performing JIT seek control based on the JIT seek control unit 622 when the rotation wait occurs.

[0058] The JIT seek control unit 622 performs JIT seek control based on the command information and controls the input current to the VCM 13 so that the head H moves from the current position to the position of the target sector of the target track using the rotation waiting time.

[0059] For example, the motion acceleration data may be stored in the nonvolatile memory 90 in advance. The motion acceleration data is time series data of the motion acceleration of the head H that can be moved using the rotation waiting time based on the relationship between the moving distance and the moving time of the head H during seek control. When receiving a command, the JIT seek control unit 622 refers to the motion acceleration data and determines the motion acceleration of the head H from the current position to the position of the target track using the rotation waiting time. The JIT seek control unit 622 may also determine the motion acceleration in such a way that the time until the head H starts processing the target sector after reaching the target track becomes greater than 0 and less than a certain threshold. The JIT seek control unit 622 determines the current indication value based on the motion acceleration and provides it to the VCM 13. Thus, the JIT seek control unit 622 performs JIT seek control.

[0060] Alternatively, the parameters may be stored in the nonvolatile memory 90 in advance, and the motion acceleration formula may be set in the firmware. The motion acceleration formula may also be a function formula that represents the motion acceleration of the head H that can be moved using the rotation waiting time based on the relationship between the moving distance and the moving time of the head H during seek control. When receiving the command, the JIT seek control unit 622 obtains the parameters and applies them to the motion acceleration formula to calculate the motion acceleration of the head H. The JIT seek control unit 622 determines the current indication value based on the motion acceleration and provides it to the VCM 13. Thus, the JIT seek control unit 622 performs the JIT seek control.

[0061] Alternatively, the current indication value data may be stored in the nonvolatile memory 90 in advance. The current indication value data is time series data of the current indication value corresponding to the motion acceleration of the head H that can be moved using the rotation wait time based on the relationship between the motion acceleration of the head H during seek control and the current indication value. When receiving the command, the JIT seek control unit 622 refers to the current indication value data, determines the current indication value of the head H from the current position to the position of the target track using the rotation wait time, and provides it to the VCM 13. Thus, the JIT seek control unit 622 performs the JIT seek control.

[0062] Alternatively, the parameters may be stored in the nonvolatile memory 90 in advance, and the formula for the current indication value may be set in the firmware. The formula for the current indication value may also be a function formula that represents the current indication value corresponding to the motion acceleration of the head H that can be moved using the rotation waiting time based on the relationship between the moving distance and the moving time of the head H during the seek control, with respect to the parameters. When receiving the command, the JIT seek control unit 622 obtains the parameters and applies them to the formula for the current indication value, calculates the current indication value of the head H, and provides it to the VCM 13. Thus, the JIT seek control unit 622 performs the JIT seek control.

[0063] The tracking control unit 63 controls the microactuator MA to make the head H track on the target track.

[0064] The volatile memory 70 is used to temporarily store data and the like by the controller 3. The volatile memory 70 is, for example, a DRAM (Dynamic RAM) or an SRAM (Static RAM).

[0065] The buffer memory 80 has a write cache and a read cache. The write cache temporarily stores data written to the disk DK by a command (e.g., a write command) instructing writing data to the disk DK. The read cache temporarily stores data read from the disk DK by a command (e.g., a read command) instructing reading data from the disk DK.

[0066] The nonvolatile memory 90 stores data in a nonvolatile manner. The nonvolatile memory 90 is, for example, a flash memory. The nonvolatile memory 90 may also store motion acceleration data, current indication value data, and parameters.

[0067] In the disk device 1, as Figure 2 The seek action is performed as shown. Figure 2 It is a diagram showing the path seeking action.

[0068] The SPM 12 is driven by the motor driver 20 to rotate the disk DK in the circumferential direction DR1. The VCM 13 is driven by the motor driver 20 to rotate the arm AM about the bearing 14 and move the head H supported by the front end of the arm AM in the radial direction DR2. Thus, a seek operation is realized.

[0069] A plurality of tracks TR (for example, tracks TR1 to TR3) are defined in a concentric circle in the disk DK. Each track TR includes a plurality of data sectors. Data can be written to each data sector. Figure 2 2 shows an example of a plurality of data sectors SC1 and SC2 included in the track TR2.

[0070] The seek control unit 64 may determine whether to perform JIT seek control or fastest seek control based on the relationship between the target sector of the disk DK and the current position of the head H.

[0071] For example, when the target track is track TR2 and the target sector is data sector SC2, and the current position of the head H is the circumferential position between data sectors SC1 and SC2 in track TR1, it is expected that rotation waiting time will occur when the seek moves from the current track TR1 to the target track TR2. Therefore, the seek control unit 64 may also determine to perform JIT seek control for adjusting the seek end time during the rotation waiting time until the target sector is in front.

[0072] Here, the period during which the seek operation is performed is referred to as the seek period, and each section in the seek period is associated with the current waveform of the VCM 13 as follows: Figure 3 Define as shown. Figure 3 This is a diagram showing the definition of the seek period and its respective sections.

[0073] Graph 6201 shows the current i of VCM13 VCM Graph 6202 shows the differential current di of VCM13. VCM / dt waveform. For current i VCM The direction of the head H is accelerated in the seek operation as positive, and the direction of the head H is decelerated as negative. Graph 6203 shows the absolute value of the current of VCM13 |iVCM | The graph 6204 shows the absolute value of the differential current of VCM13 |di VCM / dt| waveform.

[0074] In each of the graphs 6201 to 6204, the horizontal axis represents time. In the graph 6201, the vertical axis represents the current i of the VCM 13. VCM In the graph 6202, the vertical axis represents the differential current di of VCM13. VCM In the graph 6203, the vertical axis represents the absolute value of the current of VCM13 |i VCM In the graph 6204, the vertical axis represents the absolute value of the differential of the current of VCM13 |di VCM / dt|size.

[0075] In the graph 6201, REF11 and REF12 represent the limiting current. The characteristic CV11 is the current i of the VCM 13 during the seek period of the JIT seek control. VCM The characteristic CV11 falls within the range defined by the limiting currents REF11 and REF12.

[0076] In graph 6202, characteristic CV12 is a time series characteristic of the differential value with respect to characteristic CV11. In graph 6203, characteristic CV21 is an absolute value of the current of VCM13 during the seek period of JIT seek control. VCM |Time series characteristics. In the graph 6204, the characteristic CV22 is the differential value of the characteristic CV11 |di VCM / dt|'s time series characteristics.

[0077] The seek period Ts is a period from the start to the end of the seek operation. The seek period Ts includes an acceleration section Ta, a constant speed section Tc, and a deceleration section Td.

[0078] In the acceleration interval Ta, the controller 3 supplies a positive current i to the VCM 13. VCM , so as to accelerate the radial movement speed of the head H. In the constant speed section Tc, the controller 3 supplies a substantially zero current i to the VCM 13. VCM , the radial moving speed of the head H is maintained substantially constant. In the deceleration zone Td, the controller 3 supplies a negative current i to the VCM 13. VCM , the radial moving speed of the head H is decelerated.

[0079] The acceleration interval Ta includes an increasing interval A1, a flat interval A2, and a decreasing interval A3. In the increasing interval A1, the controller 3 makes the current i of the VCM 13 VCMThe waveform of VCM13 rises to the positive side. In the flat section A2, the controller 3 makes the current i VCM The waveform of VCM13 changes substantially flatly along the limit current REF11. In the falling interval A3, the controller 3 makes the current i VCM The waveform falls from the positive side.

[0080] The constant speed section Tc includes a flat section C1. In the flat section C1, the controller 3 makes the current i of the VCM 13 VCM The waveform changes smoothly.

[0081] The deceleration interval Td includes an increasing interval D1, a flat interval D2, and a decreasing interval D3. In the increasing interval D1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the negative side. In the flat section D2, the controller 3 makes the current i VCM The waveform of VCM13 changes substantially flatly along the limit current REF12. In the falling interval D3, the controller 3 makes the current i VCM The waveform falls from the negative side.

[0082] The limiting current REF11 and REF12 are based on the fact that VCM13 has Figure 4 The equivalent circuit shown in the figure is based on the current that is the electrical limit determined by the circuit characteristics of the VCM 13. Figure 4 It is a diagram showing an equivalent circuit of the VCM 13 .

[0083] The VCM 13 is supplied with a set voltage V from the motor driver 20. set , the current i is input from the motor driver 20 VCM The circuit 131 is set from the voltage V set The circuit 131 includes a resistor R others and circuit 1311 in series. Circuit 1311 corresponds to the coil portion in VCM13. Resistor R others This corresponds to the wiring connected to the coil portion in the VCM 13 .

[0084] The circuit 1311 corresponds to an equivalent circuit in terms of the supply voltage to the VCM 13. The circuit 1311 includes an inductor L VCM , resistor R VCM , current source I BEMF The inductor L VCM This corresponds to the inductance component of the coil in VCM13. VCM This corresponds to the resistance component of the coil in VCM13. BEMF Corresponding to the back electromotive force V of the coil part in VCM13 BEMF , flows with the back EMF VBEMF The corresponding current.

[0085] VCM13 has Figure 4 The equivalent circuit shown is, therefore, Figure 3 The current i of VCM13 in the rising interval A1 and the flat interval A2 shown in FIG. VCM It can be expressed by the following formula 1.

[0086]

[0087] In formula 1, R C is the combined resistance of circuit 131. VCM is the inductance of circuit 1311. V set is the set voltage. V BEMF is the back electromotive force, which can be expressed by the following formula 2.

[0088] V BEMF =K f v ... Equation 2

[0089] In Formula 2, v is the moving speed of the head H in the radial direction. f is the current force constant. The current i of VCM13 VCM The relationship between φ and the acceleration a of the head H can be expressed by the following equation 3.

[0090]

[0091] In Formula 3, m is the equivalent mass of the head H.

[0092] In adjusting the current level in the acceleration section Ta, by changing the set voltage Vset in equation 1, the time of the constant speed section Tc is adjusted, and a long seek control can be performed for a reference seek (eg, fastest seek).

[0093] exist Figure 3 In the graph 6201 shown, at time t0 to t2 (rising interval A1, flat interval A2), the current i of VCM13 VCM It is generated according to Formula 1. At time t2 to t3 (falling interval A3), the current i of VCM13 VCM The discharge is controlled according to the time constant of the circuit 131 and approaches 0. At time t3 to t4 (flat interval C1), the current i of the VCM 13 is VCM is maintained at approximately 0. At time t4 to t6 (rising section D1, flat section D2), the current i of VCM13 VCM The current i of VCM13 is generated according to the opposite polarity of equation 1. VCMThe discharge is controlled according to the time constant of the circuit 131 so as to approach zero.

[0094] The flat interval A2 can also be defined as follows: It is an interval having a starting point at time t1 and an end point at time t2, where time t1 is the absolute value of the current of the VCM 13 in the acceleration interval Ta. VCM | becomes the maximum moment, which is the moment t2 when the current i in VCM13 VCM Before the moment t4 when the polarity of VCM13 is reversed, the absolute value of the differential current of VCM13 |di VCM / dt|Become the biggest moment.

[0095] The flat section D2 can also be defined as follows: It is a section having a starting point at time t5 and an end point at time t6. The time t5 is the absolute value of the current of the VCM 13 in the deceleration section Td. VCM | becomes the maximum moment, which is the moment t6 when the current i in VCM13 VCM The absolute value of the differential of the current of VCM13 before the time t7 becomes 0 |di VCM / dt|Become the biggest moment.

[0096] In addition, the supply voltage V supplied to the VCM13 sup It can be expressed by the following formula 4.

[0097]

[0098] As shown in equations 1 and 4, the supply voltage V sup Relative to the set voltage V set Attenuation of back EMF V BEMF Correspondingly, the current i of VCM13 VCM is limited to the back EMF V BEMF Below the corresponding limiting current. Figure 3 The limit currents REF11 and REF12 shown are based on the equivalent circuit of VCM13 (refer to Figure 4 )’s characteristics determine the electrical limits.

[0099] For example, in the case of no rotation waiting time, the fastest seek control is performed, but the current waveform of VCM13 at that time becomes as follows: Figure 5 Like that. Figure 5 FIG. 4 is a diagram showing a VCM current waveform when there is no rotation waiting time.

[0100] Graph 6205 shows the current i of VCM13 VCM The waveform CV31. The graph 6206 shows the differential current di of VCM13. VCMA graph 6207 shows a waveform CV33 of the power consumption P of the VCM 13 .

[0101] In each of the graphs 6205 to 6207, the horizontal axis represents time. In the graph 6205, the vertical axis represents the current i of the VCM 13. VCM In the graph 6206, the vertical axis represents the differential current di of VCM13. VCM In the graph 6207 , the vertical axis represents the magnitude of the power consumption P of the VCM 13 .

[0102] In the fastest seek control, such as Figure 5 As shown, time t10 to t16 is a seek period Ts, and the process TGT for the target sector can be started from time t16 when the seek period Ts ends. In this case, there is no rotation waiting time.

[0103] In the fastest seek control, the constant speed section Tc may be omitted. The time t10 to t13 is the acceleration section Ta, and the time t13 to t16 is the deceleration section Td.

[0104] As shown in the waveform CV31, in the acceleration interval Ta, saturation acceleration control is performed, and the maximum current i that can be input to the VCM13 is VCM , but falls below the limit current REF31. In order to suppress the stabilization (settling) of the head H in the deceleration zone Td, the current i VCM The maximum current that can be input is not set, and a current i that is suppressed to a certain extent is input to VCM13. VCM .

[0105] In the acceleration zone Ta, time t10 to t11 is a rising zone A1, time t11 to t12 is a flat zone A2, and time t12 to t13 is a falling zone A3.

[0106] In the rising interval A1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the positive side. The controller 3 can also make the current i of VCM13 according to equation 1 VCM change.

[0107] In the flat section A2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to (along) the limit current REF31. VCM The average rate of change AR1 can be obtained by using the time of the flat interval A2 to differentiate di VCMThe average rate of change AR1 is a value indicating the change in the limiting current REF31 and may be a negative value. The controller 3 may also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section A2, the controller 3 may replace the current instruction value with the estimated value of the limit current REF31.

[0108] In the falling interval A3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the φ2 drops from the positive side to zero at an average rate of change AR2. The average rate of change AR2 can be obtained by using the time of the falling interval A3 to differentiate the di VCM The average rate of change AR2 is a value indicating a more rapid change than the average rate of change AR1, and is a negative value.

[0109] In the deceleration zone Td, time t13 to t14 is the rising zone D1, time t14 to t15 is the flat zone D2, and time t15 to t16 is the falling zone D3.

[0110] In the rising interval D1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the negative side. The controller 3 can also make the current i of VCM13 VCM change.

[0111] In the flat section D2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF32. VCM The average rate of change DR1 can be obtained by using the time of the flat interval D2 to differentiate di VCM The average rate of change DR1 is a value indicating the change in the limiting current REF32 and can be a positive value. The controller 3 can also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section D2, the controller 3 may replace the current instruction value with a value obtained by adding a predetermined value to the estimated value of the limit current REF32.

[0112] In the falling interval D3, the controller 3 makes the current i of the VCM 13 VCM The waveform of DR2 decreases from the negative side to zero at an average rate of change DR2. The average rate of change DR2 can be obtained by using the time of the descending interval D3 to differentiate di VCM The average rate of change DR2 is a value indicating a more rapid change than the average rate of change DR1 and is a positive value.

[0113] As shown in waveform CV33, in the acceleration interval Ta, the power consumption P increases with the current i VCM The absolute value of the current i VCM At around time t11 when the limit current REF31 is reached, the power consumption P reaches Rci VCM 2 , then, the power consumption increases with the current i VCM In the deceleration zone Td, the power consumption decreases as the absolute value of the current i VCM The absolute value of the current i VCM At around time t14 when the limit current REF32 is reached, the power consumption P reaches Rci VCM 2 , then, the power consumption increases with the current i VCM decreases with the decrease of its absolute value.

[0114] In the case of the rotation waiting time ΔW, the first JIT seek control can be performed, but the current waveform of the VCM 13 in the first JIT seek control becomes Figure 6 As indicated by a single dotted line. Figure 6 3 is a diagram showing a VCM current waveform in the case of having a rotation waiting time ΔW.

[0115] The first JIT seek control is the fastest seek control (refer to Figure 5 ) Added control of the constant speed section Tc.

[0116] In the first JIT seek control, graph 6208 shows the current i of VCM13. VCM The waveform CV41. Graph 6209 shows the differential current di of VCM13. VCM A graph 6210 shows a waveform CV43 of the power consumption P of the VCM 13 .

[0117] In each of the graphs 6208 to 6210, the horizontal axis represents time. In the graph 6208, the vertical axis represents the current i of the VCM 13. VCM In the graph 6209, the vertical axis represents the differential current di of VCM13. VCM In the graph 6210 , the vertical axis represents the magnitude of the power consumption P of the VCM 13 .

[0118] In the first JIT seek control, Figure 6 As shown, time t20 to t27 is a seek period Ts, and there is a rotational waiting time ΔW from time t27 when the seek period Ts ends to time t28. From time t28, the process TGT for the target sector can be performed.

[0119] As shown in the waveform CV41, in the acceleration section Ta of the head H after the start of the seek control, the saturation acceleration control is suppressed, and a current i slightly smaller than the maximum current that can be input can be input to the VCM 13. VCM , but this current falls below the limit current REF41. In the deceleration zone Td, a current i is input to the VCM13 which is smaller than the maximum current that can be input. VCM The current i is further suppressed. VCM .

[0120] In the acceleration interval Ta, in the flat interval A2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF41. VCM The average rate of change AR11 can be obtained by using the time of the flat interval A2 to differentiate di VCM The average rate of change AR11 is a value that indicates a change roughly in accordance with the limit current REF41 and may be a negative value.

[0121] In the deceleration section Td, in the flat section D2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF42. VCM The average rate of change DR11 can be obtained by using the time of the flat interval D2 to differentiate di VCM The average rate of change DR11 is a value that indicates a change roughly in accordance with the limit current REF42 and can be a positive value.

[0122] As shown in waveform CV43, in the acceleration interval Ta, the power consumption P increases with the current i VCM The absolute value of the current i VCM After reaching the peak at time t21, the power consumption P reaches Rci VCM 2 For slightly lower values, then, the power dissipation P increases with the current i VCM In the deceleration interval Td, the power consumption P decreases as the absolute value of the current i VCM The absolute value of the current i VCM After reaching the peak at time t14, the power consumption P reaches a value higher than Rci VCM 2 For slightly lower values, then, the power dissipation P increases with the current i VCM decreases with the decrease of its absolute value.

[0123] In the first JIT seek control, the time t27 at which the rotational waiting time ΔW is determined to end is adjusted accordingly. In the first JIT seek control, the control has a time margin, and there is room to further suppress saturation acceleration control.

[0124] Therefore, the second JIT seek control can be performed with the rotation waiting time ΔW. In the second JIT seek control, the current i of the VCM 13 is increased relative to the first JIT seek control. VCM The absolute value of is further suppressed. In the second JIT seek control, lower power consumption can be achieved compared to the first JIT seek control.

[0125] The current waveform of VCM13 in the second JIT seek control becomes as follows Figure 6 As indicated by the solid line.

[0126] In the second JIT seek control, graph 6208 shows the current i of VCM13. VCM The waveform CV51. The graph 6209 shows the differential current di of VCM13. VCM A graph 6210 shows a waveform CV53 of the power consumption P of the VCM 13 .

[0127] As shown in the waveform CV51, in the acceleration section Ta of the head H after the start of the seek control, a current i that changes substantially flatly on the positive side can be input to the VCM 13. VCM In the deceleration zone Td, a current i that changes substantially flatly on the negative side can be input to the VCM 13. VCM .

[0128] In the acceleration interval Ta, in the flat interval A2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 makes the current i of VCM13 VCM The average rate of change AR21 can be obtained by using the time of the flat interval A2 to differentiate di VCM / dt is averaged. The average rate of change AR21 becomes a value close to zero, or may be substantially zero. The controller 3 may also set the current i of the VCM 13 to VCM Maintain the current threshold i thp Current threshold i thp Alternatively, the current i can be set to VCM The value reached at time t21 when a change is made.

[0129] In the deceleration zone Td, in the flat zone D2, the controller 3 makes the current i of the VCM 13VCM The controller 3 makes the current i of VCM13 VCM The average rate of change DR21 can be obtained by using the time of the flat interval D2 to differentiate di VCM / dt is obtained by averaging. The average rate of change DR21 becomes a value close to zero, or may be substantially zero. The controller 3 may also set the current i of the VCM 13 to VCM Maintain the current threshold i thn Current threshold i thn Alternatively, the current i may be set to VCM The value reached at time t25 when a change is made.

[0130] As shown in waveform CV53, in the acceleration interval Ta, the power consumption P increases with the current i VCM The absolute value of the current i VCM In the flat interval A2, the power consumption P changes flatly, and then the power consumption P changes with the current i VCM In the deceleration interval Td, the power consumption P decreases as the absolute value of the current i VCM The absolute value of the current i VCM In the flat interval D2, the power consumption P changes flatly, and then the power consumption P changes with the current i VCM decreases with the decrease of its absolute value.

[0131] When the fastest seek and the second JIT seek control are compared, the absolute value differential d|i of the current in the flat sections A2 and D2 is VCM | / dt has different sizes.

[0132] with by Figure 5 The differential d|i of the absolute value of the current in the flat sections A2 and D2 represented by the waveform CV32 shown in FIG. VCM | / dt is compared with the size of Figure 6 The differential d|i of the absolute value of the current in the flat sections A2 and D2 represented by the waveform CV52 shown in FIG. VCM The magnitude of | / dt is closer to zero.

[0133] When the current of VCM13 in the fastest seek without rotational latency is set to i VCM_NoRotWait , the current of VCM13 in the second JIT seek control performed with the rotation waiting time is set to i VCM_RotWait When , the following formula 5 holds.

[0134]

[0135] In equation 5, the left side shows the time of the flat interval A2 and D2 for the current i VCM_NoRotWait The left side is a negative value or zero. The right side shows the time of the flat interval A2 and D2 for the current i VCM_RotWait The value obtained by averaging. The right side is a negative value or zero.

[0136] Here, Figure 4 The power consumption P of the circuit 131 shown can be expressed by the following equation 6.

[0137] P=R C i VCM 2 ...Formula 6

[0138] In Formula 6, Rc is the combined resistance of circuit 131. As shown in Formula 6, the current i of VCM13 VCM The power consumption P is affected in a square manner. Therefore, as shown in the waveform CV51, by making the current i VCM The average rate of change is greater than that of waveform CV31 (refer to Figure 5 ) is closer to zero, flattening its change (e.g., stabilizing it), suppressing the current i VCM The absolute value of can reduce power consumption.

[0139] exist Figure 5 and Figure 6 The time of the corresponding intervals A1, A2, A3, D1, D2, and D3 is set to be equal. Figure 5 The waveforms CV33 and Figure 6 When comparing the waveform CV53 shown in FIG. 1 , in the flat section A2 , the integrated value of the power consumption P of the waveform CV53 is lower than the integrated value of the power consumption P of the waveform CV33 . In the flat section D2 , the integrated value of the power consumption P of the waveform CV53 is lower than the integrated value of the power consumption P of the waveform CV33 .

[0140] That is, in the second JIT seek control, power consumption can be reduced compared to the fastest seek control.

[0141] For example, in a seek over a distance of 15% of the width of the data area on the disk DK, a 2.5% reduction in power consumption is expected.

[0142] In addition, with Figure 6 The differential d|i of the absolute value of the current in the flat sections A2 and D2 represented by the waveform CV42 shown in FIG. VCM | / dt, the absolute value differential d|i of the current in the flat intervals A2 and D2 represented by the waveform CV52 is VCM The magnitude of | / dt is closer to zero.

[0143] As shown in equation 6, the current i of VCM13 VCM It also affects the power consumption P in a square manner. Therefore, as shown in the waveform CV51, by making the current i VCM The average rate of change of the waveform CV41 is closer to zero than that of the waveform CV41, and its change is flattened (for example, constant), suppressing the current i VCM The absolute value of can reduce power consumption.

[0144] When Figure 6 When comparing waveforms CV43 and CV53 shown, in flat section A2, the integrated value of power consumption P of waveform CV53 is lower than that of waveform CV43. In flat section D2, the integrated value of power consumption P of waveform CV53 is lower than that of waveform CV43.

[0145] That is, in the second JIT seek control, power consumption can be reduced compared to the first JIT seek control.

[0146] The second JIT seek control is different from the first JIT seek control in that the current i in the flat sections A2 and D2 is set to VCM The function is to make the average rate of change of close to zero and flatten (e.g., constant) its change. This function is called AFC (AccFlat const) function.

[0147] As described above, the limiting currents REF41 and REF42 are calculated based on the equivalent circuit of VCM13 (see Figure 4 ) is determined by the characteristics of the electric limit. Therefore, when the current i in the flat interval A2 and D2 is VCM When the average rate of change of current i is close to zero and its change is flattened (for example, constant), sometimes the current i VCM The limit currents REF41 and REF42 will be exceeded. In this case, even if the AFC function is enabled, it may not be possible to adjust the current i VCM If the current in VCM13 exceeds the limit current REF41 and REF42 due to the indicated value, the control of the controller 3 may fail. It is difficult for the controller 3 to validate the AFC function without causing the control failure.

[0148] Therefore, the third JIT seek control can be performed with the rotation waiting time ΔW. In the third JIT seek control, the current i in the flat section A2 and / or the flat section D2 is controlled relative to the second JIT seek control. VCMThe indicated value is flattened (e.g., constant), and adjusted so as to fall within the limit current REF41, REF42. In the third JIT seek control, the flat interval A2 and / or the flat interval D2 are divided into a first flat interval that does not exceed the limit current REF41, REF42 when the AFC function is enabled, and a second flat interval that exceeds the limit current REF41, REF42 when the AFC function is enabled, and changes are made in the second flat interval so that the current i VCM The indicated value is in accordance with the limit currents REF41 and REF42. Thus, in the third JIT seek control, the AFC function can be enabled within the limit currents REF41 and REF42, and low power consumption can be achieved while maintaining access performance.

[0149] The current waveform of VCM13 in the third JIT seek control is Figure 7 As indicated by the solid line. Figure 7 : is a diagram showing a VCM current waveform with a rotation waiting time ΔW. Figure 7 In FIG. 1 , as the third JIT seek control, control in the case where the AFC function is enabled in the acceleration section Ta but is not enabled in the deceleration section Td is exemplified.

[0150] In the third JIT seek control, the graph 6211 shows the current i of VCM13. VCM The waveform CV61. The graph 6212 shows the differential current di of VCM13. VCM / dt waveform CV62.

[0151] As shown in waveform CV61, in the acceleration interval Ta, the current i VCM On the positive side, the current changes almost flatly. Near the limit current REF51, the current i VCM According to the limit current REF51 changes. In the deceleration section Td, the current i VCM On the negative side, the current increases to near the limit current REF52. Near the limit current REF52, the current i VCM Changes according to the limit current REF52.

[0152] The controller 3 sets the flat zone A2 (refer to Figure 6 ) is divided into a flat section A21 in which the positive side does not exceed the limit current REF41 when the AFC function is enabled, and a flat section A22 in which the positive side exceeds the limit current REF41 when the AFC function is enabled. In the flat section A22, the current i VCM The indicated value is in accordance with the limiting current REF41.

[0153] In the acceleration zone Ta, time t40 to t41 is the rising zone A1, time t41 to t42 is the flat zone A21, time t42 to t43 is the flat zone A22, and time t43 to t44 is the falling zone A3.

[0154] In the rising interval A1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the positive side. The controller 3 can also make the current i of VCM13 correspond to equation 1. VCM change.

[0155] In the flat section A21, the controller 3 makes the current i of the VCM 13 VCM The controller 3 makes the current i of VCM13 VCM The average change rate AR31 changes. The average change rate AR31 can be obtained by using the time of the flat interval A21 to differentiate di VCM / dt is averaged. The average rate of change AR31 becomes a value close to zero, or may be substantially zero. The controller 3 may also set the current i of the VCM 13 to VCM Maintain the current threshold i thp Current threshold i thp Alternatively, the current i may be set to VCM The value reached at time t41 if it changes.

[0156] In the flat section A22, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF51. VCM The average rate of change AR32 can be obtained by using the time of the flat interval A2 to differentiate di VCM The average rate of change AR32 is a value indicating a more rapid change than the average rate of change AR31, and may be a negative value. The controller 3 may also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section A22, the controller 3 may replace the current instruction value with the estimated value of the limit current REF51.

[0157] In the falling interval A3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the φ200 waveform drops from the positive side to zero at an average rate of change AR33. The average rate of change AR33 can be obtained by using the time of the falling interval A3 to differentiate the di VCM The average rate of change AR33 is a value indicating a more rapid change than the average rate of change AR32, and is a negative value.

[0158] In the deceleration zone Td, time t45 to t46 is the rising zone D1, time t46 to t47 is the flat zone D2, and time t47 to t48 is the falling zone D3.

[0159] In the rising interval D1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the negative side. The controller 3 can also correspond to the formula after the formula 1 is changed to the opposite polarity, so that the current i of VCM13 VCM change.

[0160] In the flat section D2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF52. VCM The average change rate DR31 changes. The average change rate DR31 can be obtained by using the time of the flat interval D2 to differentiate di VCM The average rate of change DR31 is a value indicating the change in the limiting current REF52 and can be a positive value. The controller 3 can also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section D2, the controller 3 may replace the current instruction value with a value obtained by adding a predetermined value to the estimated value of the limit current REF52.

[0161] In the falling interval D3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the falling interval D3 decreases from the negative side to zero at an average rate of change DR32. The average rate of change DR32 can be obtained by using the time of the falling interval D3 to differentiate di VCM The average rate of change DR32 is a value indicating a more rapid change than the average rate of change DR31, and is a positive value.

[0162] In addition, Figure 7 6211 shows the current waveform of VCM 13 in the first JIT seek control for comparison. VCM The waveform CV71 is similar to the waveform CV41 (see Figure 6 ) is the same. Graph 6212 shows the differential current di of VCM13 VCM / dt waveform CV72. Waveform CV72 and waveform CV42 (refer to Figure 6 ) is the same.

[0163] with by Figure 7 The differential d|i of the absolute value of the current in the flat intervals A21 and A22 represented by the waveform CV62 shown in FIG. VCM| / dt, the absolute value differential d|i of the current in the flat sections A21 and A22 represented by the waveform CV72 is compared. VCM The magnitude of | / dt is closer to zero.

[0164] Accordingly, in the third JIT seek control, the absolute value of the current in the flat sections A21 and A22 can be suppressed compared to the first JIT seek control. VCM |, can reduce power consumption.

[0165] As described above, in the present embodiment, the controller 3 predicts the limiting current in the disk device 1 and makes the current instruction value of the VCM 13 follow the predicted limiting current. The controller 3 controls the current i in the flat section A2. VCM The controller 3 flattens the indicated value (e.g., makes it constant) and adjusts it so that it falls within the limit current REF41 and REF42. The controller 3 divides the flat interval A2 into a flat interval A21 that does not exceed the limit current REF41 and REF42 when the AFC function is enabled and a flat interval A22 that exceeds the limit current REF41 and REF42 when the AFC function is enabled. In the flat interval A22, changes are made so that the current i VCM The indicated value of is in accordance with the limit current REF41, REF42. Thus, in the disk device 1, the AFC function can be enabled within the limit current REF41, REF42, and the power consumption can be reduced while maintaining the access performance.

[0166] (First Modification of Implementation)

[0167] In the 3rd JIT seek control, such as Figure 8 As shown by the solid line in FIG. 8 , the AFC function may not be enabled in the acceleration section Ta but may be enabled in the deceleration section Td. Figure 8 1 is a diagram showing a VCM current waveform in a case where a rotation waiting time ΔW is provided in a first modification of the embodiment.

[0168] In the third JIT seek control, the graph 6213 shows the current i of VCM13. VCM The waveform CV81. Graph 6214 shows the differential current di of VCM13. VCM / dt waveform CV82.

[0169] As shown in waveform CV81, in the acceleration interval Ta, the current i VCM On the positive side, the current increases until it reaches the limit current REF51. At the limit current REF61, the current i VCM In the deceleration zone Td, the current i VCMOn the negative side, the current changes almost flatly. Near the limit current REF62, the current i VCM Changes according to the limit current REF62.

[0170] In the acceleration zone Ta, time t50 to t51 is the rising zone A1, time t51 to t52 is the flat zone A2, and time t52 to t53 is the falling zone A3.

[0171] In the rising interval A1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the positive side. The controller 3 can also make the current i of VCM13 correspond to equation 1. VCM change.

[0172] In the flat section A2, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF61. VCM The average rate of change AR41 can be obtained by using the time of the flat interval A2 to differentiate di VCM The average rate of change AR41 is a value indicating the change in the limiting current REF61 and may be a negative value. The controller 3 may also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section A2, the controller 3 may replace the current instruction value with the estimated value of the limit current REF31.

[0173] In the falling interval A3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the φ2000 waveform drops from the positive side to zero at an average rate of change AR42. The average rate of change AR42 can be obtained by using the time of the falling interval A3 to differentiate the di VCM The average rate of change AR42 is a value indicating a more rapid change than the average rate of change AR41, and is a negative value.

[0174] The controller 3 sets the flat section D2 (refer to Figure 6 ) is divided into a flat section D21 in which the negative side does not exceed the value obtained by adding a predetermined value to the limit current REF62 when the AFC function is enabled, and a flat section D22 in which the negative side exceeds the value obtained by adding a predetermined value to the limit current REF62 when the AFC function is enabled, and in the flat section D22, the current i is changed so that the current i VCM The indicated value is in accordance with the limiting current REF62.

[0175] In the deceleration zone Td, time t54 to t55 is the rising zone D1, time t55 to t56 is the flat zone D21, time t56 to t57 is the flat zone D21, and time t57 to t58 is the falling zone D3.

[0176] In the rising interval D1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the negative side. The controller 3 can also correspond to the formula after the formula 1 is changed to the opposite polarity, so that the current i of VCM13 VCM change.

[0177] In the flat section D21, the controller 3 makes the current i of the VCM 13 VCM The controller 3 makes the current i of VCM13 VCM The average change rate DR41 changes. The average change rate DR41 can be obtained by using the time of the flat interval D21 to differentiate di VCM / dt is averaged. The average rate of change DR41 becomes a value close to zero, or may be substantially zero. The controller 3 may also set the current i of the VCM 13 to VCM Maintain the current threshold i thp Current threshold i thp Alternatively, the current i may be set to the value corresponding to the formula after the formula 1 is reversed from the time 55. VCM The value reached at time t55 when a change is made.

[0178] In the flat section D22, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF62. VCM The average rate of change DR42 can be obtained by using the time of the flat interval D22 to differentiate di VCM The average rate of change DR42 is a value indicating a more rapid change than the average rate of change DR41 and may be a positive value. The controller 3 may also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section D22, the controller 3 may replace the current instruction value with a value obtained by adding a predetermined value to the estimated value of the limit current REF62.

[0179] In the falling interval D3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the falling interval D3 decreases from the negative side to zero at an average rate of change DR43. The average rate of change DR43 can be obtained by using the time of the falling interval D3 to differentiate di VCM The average rate of change DR43 is a value indicating a more rapid change than the average rate of change DR42, and is a positive value.

[0180] In addition, Figure 8 In FIG. 62, for comparison, the current waveform of VCM 13 in the first JIT seek control is shown by a single-dot chain line. In the first JIT seek control, the graph 6213 shows the current i of VCM 13. VCM The waveform CV91 is similar to the waveform CV41 (refer to Figure 6 ) is the same. Graph 6214 shows the differential current di of VCM13 VCM / dt waveform CV92. Waveform CV92 and waveform CV42 (refer to Figure 6 ) is the same.

[0181] with by Figure 8 The differential d|i of the absolute value of the current in the flat sections D21 and D22 represented by the waveform CV92 shown in FIG. VCM | / dt, the absolute value differential d|i of the current in the flat sections D21 and D22 represented by the waveform CV82 is greater than that in the flat sections D21 and D22. VCM The magnitude of | / dt is closer to zero.

[0182] Accordingly, in the third JIT seek control, the absolute value of the current in the flat sections D21 and D22 can be suppressed compared to the first JIT seek control. VCM |, can reduce power consumption.

[0183] Thus, the controller 3 divides the flat section D2 into a flat section D21 in which the negative side does not exceed the value obtained by adding the predetermined value to the limit current REF42 when the AFC function is enabled, and a flat section D22 in which the negative side exceeds the value obtained by adding the predetermined value to the limit current REF42 when the AFC function is enabled, and changes are made in the flat section D22 so that the current i VCM The indicated value of is in accordance with the limit current REF62. Thus, in the disk device 1, the AFC function can be enabled within the limit currents REF61 and REF62, and the power consumption can be reduced while maintaining the access performance.

[0184] (Second Modification of Implementation)

[0185] In the 3rd JIT seek control, such as Fig. 9 As indicated by the solid line in FIG. 8 , the AFC function can be enabled in both the acceleration zone Ta and the deceleration zone Td. Fig. 9 1 is a diagram showing a VCM current waveform in a case where a rotation waiting time ΔW is provided in a second modification of the embodiment.

[0186] In the third JIT seek control, the graph 6215 shows the current i of VCM13.VCM The waveform CV101. Graph 6216 shows the differential current di of VCM13. VCM / dt waveform CV102.

[0187] As shown in waveform CV101, in the acceleration interval Ta, the current i VCM On the positive side, the current changes almost flatly. Near the limit current REF71, the current i VCM According to the limit current REF71 changes. In the deceleration section Td, the current i VCM On the negative side, the current changes almost flatly. Near the limit current REF72, the current i VCM Changes according to the limit current REF72.

[0188] The controller 3 sets the flat zone A2 (refer to Figure 6 ) is divided into a flat section A21 in which the positive side does not exceed the limit current REF71 when the AFC function is enabled, and a flat section A22 in which the positive side exceeds the limit current REF71 when the AFC function is enabled. In the flat section A22, the current i VCM The indicated value is in accordance with the limiting current REF71.

[0189] In the acceleration zone Ta, time t60 to t61 is the rising zone A1, time t61 to t62 is the flat zone A21, time t62 to t63 is the flat zone A22, and time t63 to t64 is the falling zone A3.

[0190] In the rising interval A1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the positive side. The controller 3 can also make the current i of VCM13 correspond to equation 1. VCM change.

[0191] In the flat section A21, the controller 3 makes the current i of the VCM 13 VCM The controller 3 makes the current i of VCM13 VCM The average rate of change AR51 can be obtained by using the time of the flat interval A21 to differentiate di VCM / dt is averaged. The average rate of change AR51 becomes a value close to zero, or may be substantially zero. The controller 3 may also set the current i of the VCM 13 to VCM Maintain the current threshold i thp Current threshold i thp Alternatively, the current i may be set to VCM The value reached at time t41 if it changes.

[0192] In the flat section A22, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF71. VCM The average rate of change AR52 can be obtained by using the time of the flat interval A2 to differentiate di VCM The average rate of change AR52 is a value indicating a more rapid change than the average rate of change AR51, and may be a negative value. The controller 3 may also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section A22, the controller 3 may replace the current instruction value with the estimated value of the limit current REF71.

[0193] In the falling interval A3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the φ200 waveform drops from the positive side to zero at an average rate of change AR53. The average rate of change AR53 can be obtained by using the time of the falling interval A3 to differentiate the di VCM The average rate of change AR53 is a value indicating a more rapid change than the average rate of change AR52, and is a negative value.

[0194] In the deceleration zone Td, time t65 to t66 is the rising zone D1 , time t66 to t67 is the flat zone D21 , time t67 to t68 is the flat zone D22 , and time t68 to t69 is the falling zone D3 .

[0195] The controller 3 sets the flat section D2 (refer to Figure 6 ) is divided into a flat section D21 in which the negative side does not exceed the value obtained by adding a predetermined value to the limit current REF72 when the AFC function is enabled, and a flat section D22 in which the negative side exceeds the value obtained by adding a predetermined value to the limit current REF72 when the AFC function is enabled, and in the flat section D22, the current i is changed so that the current i VCM The indicated value is in accordance with the limiting current REF72.

[0196] In the rising interval D1, the controller 3 makes the current i of the VCM 13 VCM The waveform of VCM13 rises to the negative side. The controller 3 can also correspond to the formula after the formula 1 is changed to the opposite polarity, so that the current i of VCM13 VCM change.

[0197] In the flat section D21, the controller 3 makes the current i of the VCM 13 VCM The controller 3 makes the current i of VCM13 VCMThe average change rate DR51 changes. The average change rate DR51 can be obtained by using the time of the flat interval D21 to differentiate di VCM / dt is obtained by averaging. The average rate of change DR51 becomes a value close to zero, or may be substantially zero. The controller 3 may also set the current i of the VCM 13 to VCM Maintain the current threshold i thp Current threshold i thp Alternatively, the current i may be set to VCM The value reached at time t66 when a change is made.

[0198] In the flat section D22, the controller 3 makes the current i of the VCM 13 VCM The controller 3 changes the current i of the VCM 13 according to the limit current REF72. VCM The average rate of change DR52 can be obtained by using the time of the flat interval D22 to differentiate di VCM The average rate of change DR52 is a value indicating a more rapid change than the average rate of change DR51 and may be a positive value. The controller 3 may also pre-estimate the value taking into account the back electromotive force V BEMF In the flat section D22, the controller 3 may replace the current instruction value with a value obtained by adding a predetermined value to the estimated value of the limit current REF72.

[0199] In the falling interval D3, the controller 3 makes the current i of the VCM 13 VCM The waveform of the falling interval D3 decreases from the negative side to zero at an average rate of change DR53. The average rate of change DR53 can be obtained by using the time of the falling interval D3 to differentiate di VCM The average rate of change DR53 is a value indicating a more rapid change than the average rate of change DR52, and is a positive value.

[0200] In addition, Fig. 9 6215 shows the current waveform of VCM 13 in the first JIT seek control for comparison. VCM The waveform CV111 is similar to the waveform CV41 (see Figure 6 ) is the same. Graph 6216 shows the differential current di of VCM13 VCM / dt waveform CV112. Waveform CV112 and waveform CV42 (refer to Figure 6 ) is the same.

[0201] with by Fig. 9The absolute value differential d|i of the current in the flat sections A21, A22, D21, and D22 represented by the waveform CV112 shown in FIG. VCM | / dt, the absolute value differential d|i of the current in the flat sections A21, A22, D21, and D22 represented by the waveform CV112 is greater than that in the flat sections A21, A22, D21, and D22. VCM The magnitude of | / dt is closer to zero.

[0202] Accordingly, in the third JIT seek control, the absolute value of the current in the flat sections A21, A22, D21, and D22 can be suppressed compared to the first JIT seek control. VCM |, can reduce power consumption.

[0203] Thus, the controller 3 sets the flat zone A2 (refer to Figure 6 ) is divided into a flat section A21 in which the positive side does not exceed the limit current REF71 when the AFC function is enabled, and a flat section A22 in which the positive side exceeds the limit current REF71 when the AFC function is enabled. In the flat section A22, the current i VCM The controller 3 sets the flat zone D2 (reference Figure 6 ) is divided into a flat section D21 in which the negative side does not exceed the value obtained by adding a predetermined value to the limit current REF72 when the AFC function is enabled, and a flat section D22 in which the negative side exceeds the value obtained by adding a predetermined value to the limit current REF72 when the AFC function is enabled, and in the flat section D22, the current i is changed so that the current i VCM The indicated value of is in accordance with the limit current REF72. Thus, in the disk device 1, the AFC function can be enabled within the limit currents REF71 and REF72, and power consumption can be reduced while maintaining access performance.

[0204] (Third Modification of Implementation)

[0205] like Fig.10 As shown, the third JIT seek control may also be implemented in the JIT seek control unit 622 (see Figure 1 ). Fig.10 This is a diagram showing the functional structure of the JIT seek control unit 622.

[0206] The JIT seek control unit 622 sets a target acceleration, and sets a current instruction value of the VCM 13 in consideration of the target acceleration and a BEMF (Back Electromotive Force) coefficient.

[0207] Considering the BEMF coefficient k BEMFIn the case of Figure 3 The current i of VCM13 in the rising interval A1 and the flat interval A2 shown in FIG. VCM It can be represented by the following formula 1'.

[0208]

[0209] In formula 1', V BEMF_set is the back electromotive force, which can be expressed by the following formula 2'.

[0210] V BEMF_set =k BEMF K f v ...Formula 2'

[0211] As shown in equation 1' and equation 2', the BEMF coefficient k BEMF is the change in back electromotive force V BEMF The current i of VCM13 VCM A coefficient indicating the degree of influence of the value.

[0212] Fig.10 The JIT seek control unit 622 shown in the figure has a current threshold setting unit 6221, a conversion unit 6222, a target acceleration setting unit 6223, and a control instruction value determination unit 6224 as a configuration for performing the third JIT seek control. The control instruction value determination unit 6224 has a BEMF coefficient setting unit 6225, a control instruction value calculation unit 6226, and a current instruction value update unit 6227.

[0213] The current threshold setting unit 6221 sets the absolute value of the current for VCM13. VCM |The current threshold I for limiting th .

[0214] For example, the current threshold setting unit 6221 may also set a flat interval A2 (see Figure 6 ) The current i of VCM13 in VCM The current threshold i thp The current threshold setting unit 6221 may also set a flat interval D2 (see Figure 6 ) The current i of VCM13 in VCM The current threshold i thn .

[0215] The conversion unit 6222 converts the current threshold value I set by the current threshold setting unit 6221 into th Transformed into acceleration threshold a th .

[0216] For example, the conversion unit 6222 converts the current threshold I of the flat interval A2 intothp Transformed to the acceleration threshold a of the flat interval A2 thp .

[0217]

[0218] The conversion unit 6222 converts the current threshold I of the flat interval D2 into thn Transformed into the acceleration threshold a of the flat interval D2 thn .

[0219]

[0220] The target acceleration setting unit 6223 receives the current threshold I th The corresponding acceleration threshold a th For example, the target acceleration setting unit 6223 can accept the current threshold i thp The corresponding acceleration threshold a thp , can also accept the current threshold i thn The corresponding acceleration threshold a thn The target acceleration setting unit 6223 sets the acceleration threshold a th The corresponding target acceleration a tgt The target acceleration setting unit 6223 provides the target acceleration a to the control instruction value calculation unit 6226. tgt .

[0221] The BEMF coefficient setting unit 6225 sets the BEMF coefficient k BEMF The BEMF coefficient setting unit 6225 provides the BEMF coefficient k to the control instruction value calculation unit 6226. BEMF .

[0222] The control instruction value calculation unit 6226 may use a controller that takes BEMF into consideration. The control instruction value calculation unit 6226 receives the target position P tgt , target speed V tgt , and receives the target acceleration a from the target acceleration setting unit 6223 tgt , receives the BEMF coefficient k from the BEMF coefficient setting unit 6225 BEMF The control instruction value calculation unit 6226 uses the target position P tgt , target speed V tgt 、Target acceleration a tgt , BEMF coefficient k BEMF , calculate the current indication value of VCM13.

[0223] For example, the control instruction value calculation unit 6226 calculates the current instruction value as follows: In the rising interval A1, the current instruction value rises to the positive side according to the formula 1', and in the flat interval A2, the current instruction value is maintained at approximately the current threshold value i thp In the falling interval A3, it falls from the positive side according to the time constant of the circuit 131. In the flat interval C1, it is maintained at approximately zero. In the rising interval D1, it rises to the negative side according to the formula after making the formula 1' the opposite polarity. In the flat interval D2, it is maintained at approximately the current threshold i thp In the falling interval D3, the voltage drops from the negative side according to the time constant of the circuit 131 (refer to Figure 6 ).

[0224] The current instruction value update unit 6227 estimates the limit current in advance taking the back electromotive force into consideration. The current instruction value update unit 6227 may estimate the time series characteristics of the limit current (for example, Fig. 9 When receiving the current instruction value from the control instruction value calculation unit 6226, the current instruction value update unit 6227 updates the current instruction value by adjusting the current instruction value so that it falls within the limit current. The current instruction value update unit 6227 may also determine the portion of the current instruction value that exceeds the limit current and replace the current instruction value of the portion that exceeds the limit current with the limit current (or a value corresponding to the limit current).

[0225] For example, the current instruction value update unit 6227 may compare the current instruction value with the limit current, and divide the flat interval A2 into a flat interval A21 that does not exceed the limit current REF71 on the positive side, and a flat interval A22 that exceeds the limit current REF71 on the positive side (see Fig. 9 The current instruction value update unit 6227 may replace the portion of the flat interval A22 in the current instruction value with the limit current REF71. Accordingly, the current instruction value update unit 6227 may make a fine correction to the portion after the falling interval A3.

[0226] The current indication value update unit 6227 may compare the current indication value with the limit current, and divide the flat interval D2 into a flat interval D21 which does not exceed the value obtained by adding a predetermined value to the limit current REF72 on the negative side, and a flat interval D22 which exceeds the value obtained by adding a predetermined value to the limit current REF72 on the negative side (see Fig. 9 The current instruction value update unit 6227 may replace the portion of the flat interval A22 in the current instruction value with a value obtained by adding a predetermined value to the limit current REF72. Accordingly, the current instruction value update unit 6227 may make a fine correction to the portion after the falling interval A3.

[0227] The current instruction value update unit 6227 outputs the updated current instruction value.

[0228] like Fig.11 As shown, the third JIT seek control may also be installed in the servo control unit 64 (see Figure 1 ). Fig.11 It is a diagram showing the functional configuration of the servo control unit 64 in the third modified example of the embodiment.

[0229] The servo control unit 64 includes a state estimation unit 645, subtractors 646 to 648, and an adder 649 in addition to the JIT seek control unit 622. Fig.10 Same composition.

[0230] The control instruction value determination unit 6224 determines the target acceleration a based on the target acceleration a. tgt , target speed V tgt 、Target position P tgt etc., determine the current indication value i VCM_tgt The control instruction value determination unit 6224 may also set the target acceleration a tgt Applied to equation 3, determine the current indication value i VCM_tgt The control instruction value determination unit 6224 provides the VCM current applying unit 2021 of the VCM control unit 202 with the current instruction value i VCM_tgt The VCM current applying unit 2021 generates a current according to the current instruction value i VCM_tgt , to the device (plant) P of VCM13 VCM Flowing current. Device P VCM Equivalent to the transfer function of VCM13.

[0231] The control instruction value determination unit 6224 determines the target acceleration a based on the target acceleration a. tgt , target speed V tgt 、Target position P tgt etc., determine the voltage indication value V MA_tgt The control instruction value determination unit 6224 provides the voltage instruction value V to the MA voltage application unit 2031 of the MA control unit 203. MA_tgt The MA voltage applying unit 2031 is set according to the voltage instruction value V MA_tgt , to the microactuator MA device P MA Applied voltage. Device P MA This is equivalent to the transfer function of the microactuator MA.

[0232] The state estimation unit 645 receives the current instruction value i from the control instruction value determination unit 6224. VCM_tgt And use an observer to calculate the current indication value I tgt_d To find the estimated position p of the head MHesti and the estimated speed v esti .

[0233] Adder 649 performs the operation of adding the data from device P. VCM The signal and the signal from the device P MA The signals are added to obtain the position P of the head H and provided to the subtractor 648.

[0234] The subtractor 648 subtracts the estimated position P from the position P of the head H. esti , find the estimated error P err And feed back to the state estimation unit 645.

[0235] The state estimation unit 645 estimates the state estimation value (estimated position p) of the head MH. esti , estimated speed v esti ) is corrected so that the estimated error p err Close to zero.

[0236] Subtractor 646 obtains the target speed v tgt Subtract the estimated speed v esti , find the velocity error v e And provide it to the control instruction value determination unit 6224.

[0237] Subtractor 647 subtracts the target position P tgt Subtract the estimated position P esti , find the position error P e And provide it to the control instruction value determination unit 6224.

[0238] For example, the control instruction value determination unit 6224 determines the flat intervals A2 and D2 (see Figure 6 ) to enable the AFC function.

[0239] In the control instruction value determination unit 6224, the current threshold setting unit 6221 uses the seek distance d at the start of seek. seek , rotation waiting time t RotWait , Supply voltage V sup , ambient temperature, and VCM temperature, or a combination thereof, and refers to the table in the firmware or nonvolatile memory 90. Thus, the current threshold setting unit 6221 sets the current threshold value i for the acceleration zone Ta. thp , current threshold i for deceleration interval Td thn .

[0240] The conversion unit 6226 converts the current threshold value i used in the acceleration interval Ta into thp , current threshold i for deceleration interval Td thn The acceleration threshold a is converted into the acceleration interval Ta. thp, acceleration threshold a for deceleration interval Td thn .

[0241] The target acceleration setting unit 6223 sets the acceleration threshold a for the obtained acceleration interval Ta to thp , acceleration threshold a for deceleration interval Td thn Set as target acceleration a tgt The target acceleration setting unit 6223 provides the target acceleration a to the control instruction value calculation unit 6226. tgt .

[0242] Accordingly, the control instruction value calculation unit 6226 calculates the current instruction value that changes flatly in the flat intervals A2 and D2 (see Figure 6 ).

[0243] The BEMF coefficient setting unit 6225 sets the BEMF coefficient k BEMF The BEMF coefficient setting unit 6225 provides the BEMF coefficient k to the control instruction value calculation unit 6226. BEMF .

[0244] Accordingly, the control instruction value calculation unit 6226 calculates the value based on the BEMF coefficient k BEMF , while taking into account the influence of back electromotive force, the current indication value is calculated.

[0245] Here, the BEMF coefficient setting unit 6225 changes the BEMF coefficient k BEMF , the average rate of change of the current indication value can be changed. For example, in order to reduce the average rate of change of the current indication value, the BEMF coefficient setting unit 6225 sets the BEMF coefficient k in the range of 0 to 1. BEMF This can reduce the back electromotive force V calculated based on equation 2'. BEMF_set The absolute value of the back EMF V is calculated by using the circuit equation as in Equation 1' BEMF_set , which can reduce the average rate of change of the current indication value.

[0246] The control instruction value calculation unit 6226 provides the current instruction value to the current instruction value update unit 6227 .

[0247] The current instruction value update unit 6227 obtains the virtual limit current i VCM_AFC_limit .

[0248] For example, the current instruction value update unit 6227 uses the power supply voltage limit value V obtained by any of the measured value, the estimated value, and the designed value. AFC , current force constant K f_AFC 、Combined resistance R including VCM13 C_AFC, the radial velocity v of the head H, and the hypothetical limiting current i is calculated by the following formula 9: VCM_AFC_limit .

[0249]

[0250] Power supply voltage limit value V AFC It may be set to the lowest value (worst value) in the design of the disk device 1, or it may be set to a value measured when the disk device 1 is operating. f_AFC The combined resistance R including the VCM 13 may be set to the lowest value (worst value) in the design of the disk device 1, or may be set to a value measured when the disk device 1 is operating. C_AFC It may be set to the highest value (worst value) in the design of the disk device 1 or to a value measured when the disk device 1 is in operation. The radial velocity v of the head H may be the differential value of the position p or the estimated velocity v estimated by the state estimation unit. esti .

[0251] For example, the combined resistance value Rc can be set at a specific time (servo sampling) in the saturation acceleration interval at the set voltage Vset (refer to Figure 4 ), current force constant K f , the radial velocity v of the head H, the current i of the VCM13 VCM When is known, it is estimated by the following formula 10.

[0252]

[0253] In addition, if the seek operation is in the saturation acceleration period, the combined resistance R including the VCM 13 can be estimated. C_AFC If the seek operation does not include the saturation acceleration interval, the estimated combined resistance R for the seek operation including the saturation acceleration interval may also be used. C The combined resistance Rc is estimated from the heat dissipation of the coil of the VCM 13 due to the elapse of time and the heat generated by the coil of the VCM 13 due to the seek operation excluding the saturation acceleration section.

[0254] The current instruction value update unit 6227 updates the absolute value of the current instruction value and the virtual limit current i VCM_AFC_limit The current instruction value update unit 6227 compares the absolute value of the current instruction value with the absolute value of the virtual limit current i VCM_AFC_limit When the absolute value of the current indication value is equal to the absolute value of the current limit (or the value obtained by subtracting a predetermined value from the absolute value), the current indication value is updated to the virtual limit current i VCM_AFC_limit processing.

[0255] Thus, equivalently, the current instruction value update unit 6227 updates the flat interval A2 (see Figure 6 ) is divided into a flat section A21 in which the positive side does not exceed the limit current REF71 when the AFC function is enabled, and a flat section A22 in which the positive side exceeds the limit current REF71 when the AFC function is enabled. In the flat section A22, the current i VCM The indicated value is based on the limiting current REF71 (refer to Fig. 9 ).

[0256] Equivalently, the current instruction value update unit 6227 updates the flat interval D2 (refer to Figure 6 ) is divided into a flat section D21 in which the negative side does not exceed the value obtained by adding a predetermined value to the limit current REF72 when the AFC function is enabled, and a flat section D22 in which the negative side exceeds the value obtained by adding a predetermined value to the limit current REF72 when the AFC function is enabled, and in the flat section D22, the current i is changed so that the current i VCM The indicated value is based on the limit current REF72 (refer to Fig. 9 ).

[0257] The current instruction value updating unit 6227 provides the VCM current applying unit 2021 with the updated current instruction value i VCM_tgt .

[0258] exist Fig.10 and Fig.11 The controller 3 is shown in FIG. Fig. 9 The operation of the seek control shown in the figure is performed by the controller 3. Figure 7 In the case of seek control shown, the current threshold i is omitted thn Alternatively, the controller 3 performs Figure 8 In the case of seek control shown, the current threshold i is omitted thp Related actions.

[0259] With such a configuration, in the disk device 1 as well, the AFC function can be enabled within the limit currents REF71 and REF72, and power consumption can be reduced while maintaining access performance.

[0260] (Fourth Modification of Implementation Method)

[0261] like Fig.12 As shown, the third JIT seek control may also be implemented in the JIT seek control unit 622a. Fig.12 It is a diagram showing the functional structure of the JIT seek control unit 622a in the fourth variant of the embodiment.

[0262] The JIT seek control unit 622 a obtains an acceleration threshold value corresponding to the current threshold value, limits the target acceleration according to the acceleration threshold value, and sets the current instruction value of the VCM 13 .

[0263] The JIT seek control unit 622a replaces the target acceleration setting unit 6223 and the control instruction value determination unit 6224 (see Fig.10 ) and has a target acceleration limiter 6223a and a control instruction value determiner 6224a. The control instruction value determiner 6224a omits the BEMF coefficient setting unit 6225.

[0264] The target acceleration limiter 6223a receives the target acceleration a tgt , and receives the acceleration threshold a from the conversion unit 6222 th , using the acceleration threshold a th , and perform target acceleration a tgt For example, the target acceleration limiter 6223a uses the acceleration threshold a thp For the acceleration threshold a th The part corresponding to the flat interval A2 is clipped and the acceleration threshold a is used. thn For the acceleration threshold a th The target acceleration limiter 6223a provides the target acceleration a after clipping to the control instruction value determiner 6224a. tgt .

[0265] In the control instruction value determination unit 6224a, the control instruction value calculation unit 6226 does not use the BEMF coefficient k BEMF Based on the target acceleration a tgt , target speed V tgt 、Target position P tgt etc. to calculate the current indication value of VCM13.

[0266] For example, the control instruction value calculation unit 6226 calculates the current instruction value as follows. In the rising section A1, the current instruction value rises to the positive side according to equations 1 and 2, and in the flat section A2, the current instruction value is maintained at approximately the current threshold value i thp In the falling interval A3, it falls from the positive side according to the time constant of the circuit 131. In the flat interval C1, it is maintained at approximately zero. In the rising interval D1, it rises to the negative side according to equations 1 and 2, and in the flat interval D2, it is maintained at approximately the current threshold i thp In the falling interval D3, the voltage drops from the negative side according to the time constant of the circuit 131 (refer to Figure 6 ).

[0267] The other points are the same as those of the third modification example of the embodiment.

[0268] like Fig.13 As shown, the third JIT seek control may also be implemented in the servo control unit 64a. Fig.13 It is a diagram showing the functional configuration of a servo control unit 64 a in a fourth modified example of the embodiment.

[0269] The servo control unit 64a replaces the JIT seek control unit 622 (see Fig.11 ) and has a JIT seek control unit 622a. The JIT seek control unit 622a has Fig.12 Same composition.

[0270] In addition, the target acceleration a that has been clipped by the target acceleration limiter 6223a is tgt Sometimes, the acceleration dimension is not smooth. For example, the first-order differential of the acceleration may change discontinuously. Accordingly, mechanical vibration of the head H may be caused. In this case, Fig.12 , Fig.13 As indicated by the dotted line in FIG. 6 , the JIT seek control unit 622a may further include a smoothing filter 6228a.

[0271] The smoothing filter 6228a is used to adjust the target acceleration a clipped by the target acceleration limiter 6223a. tgt The smoothing filter 6228a provides the target acceleration a after smoothing to the control instruction value determination unit 6224a. tgt .

[0272] Thus, the target acceleration a can be tgt Smooth in the acceleration dimension, for example, it can be made continuous in the dimension of the first-order differential of acceleration, which can be consistent with the target acceleration a tgt Accordingly, the change of the current instruction value set in the control instruction value determination unit 6224a is smoothed. Thus, the mechanical vibration of the head H can be suppressed.

[0273] The current instruction value update unit 6227 updates the absolute value of the current instruction value and the virtual limit current i VCM_AFC_limit When the absolute value of the current indication value exceeds the imaginary limit current i VCM_AFC_limit When the absolute value of the current indication value is equal to the absolute value of the current limit (or the value obtained by subtracting a predetermined value from the absolute value), the current indication value is updated to the virtual limit current i VCM_AFC_limit This is the same as the third variant of the implementation example.

[0274] exist Fig.12 and Fig.13 The controller 3 is shown in FIG. Fig. 9The operation of the seek control shown in the figure is performed by the controller 3. Figure 7 In the case of seek control shown, the current threshold i is omitted thn Alternatively, the controller 3 performs Figure 8 In the case of seek control shown, the current threshold i is omitted thp Related actions.

[0275] With such a configuration, in the disk device 1 as well, the AFC function can be enabled within the limit currents REF71 and REF72, and power consumption can be reduced while maintaining access performance.

[0276] (Fifth Modification of Implementation Method)

[0277] like Fig.14 As shown, the third JIT seek control may also be installed in the JIT seek control unit 622b. Fig.14 It is a diagram showing the functional structure of the JIT seek control unit 622b in the fifth variation of the embodiment.

[0278] The JIT seek control unit 622 b limits the current instruction value according to the current threshold value, and sets the current instruction value of the VCM 13 .

[0279] The JIT seek control unit 622b omits the conversion unit 6222 and the target acceleration limiter 6223a (see Fig.12 ), instead of the control instruction value determination unit 6224a (refer to Fig.10 ) and has a control instruction value determination unit 6224b. The control instruction value determination unit 6224b further has a current instruction value restriction unit 6229b.

[0280] The current instruction value limiting unit 6229b receives the current instruction value from the control instruction value calculating unit 6226 and receives the current threshold value i from the current threshold setting unit 6221. th , using the current threshold i th , and perform the current instruction value clipping processing. For example, the current instruction value limiting unit 6229b uses the current threshold i thp The portion of the current indication value corresponding to the flat interval A2 is clipped, and the current threshold i thn The portion of the current instruction value corresponding to the flat section D2 is clipped. The current instruction value limiter 6229 b supplies the current instruction value after the clipping process to the current instruction value updater 6227 .

[0281] The other points are the same as those of the fourth variation of the embodiment.

[0282] like Fig.15 As shown, the third JIT seek control may also be implemented in the servo control unit 64b. Fig.15 It is a diagram showing the functional configuration of the servo control unit 64b in the fifth modification of the embodiment.

[0283] The servo control unit 64a replaces the JIT seek control unit 622a (see Fig.13 ) and has a JIT seek control unit 622b. The JIT seek control unit 622b has Fig.14 Same composition.

[0284] In addition, the current instruction value that has been clipped in the current instruction value limiting unit 6229b may not be smooth in the current dimension. For example, it may change discontinuously in the dimension of the first-order differential of the current. Accordingly, mechanical vibration of the head H may be caused. In this case, Fig.14 , Fig.15 As indicated by the dotted line in FIG. 6 , the control instruction value determination unit 6224b may further include a smoothing filter 6228b.

[0285] The smoothing filter 6228b smoothes the current instruction value clipped by the current instruction value limiting unit 6229b and supplies the current instruction value after the smoothing process to the current instruction value updating unit 6227.

[0286] This makes it possible to smooth the current indication value in the current dimension, for example, to make it continuous in the dimension of the first-order differential of the current. This makes it possible to suppress the mechanical vibration of the head H.

[0287] The current instruction value update unit 6227 updates the absolute value of the current instruction value and the virtual limit current i VCM_AFC_limit When the absolute value of the current indication value exceeds the imaginary limit current i VCM_AFC_limit When the absolute value of the current indication value is equal to the absolute value of the current limit (or the value obtained by subtracting a predetermined value from the absolute value), the current indication value is updated to the virtual limit current i VCM_AFC_limit This is the same as the fourth variant of the implementation example.

[0288] exist Fig.14 and Fig.15 The controller 3 is shown in FIG. Fig. 9 The operation of the seek control shown in the figure is performed by the controller 3. Figure 7 In the case of seek control shown, the current threshold i is omitted thn Alternatively, the controller 3 performs Figure 8 In the case of seek control shown, the current threshold i is omitted thp Related actions.

[0289] With such a configuration, in the disk device 1 as well, the AFC function can be enabled within the limit currents REF71 and REF72, and power consumption can be reduced while maintaining access performance.

[0290] (Sixth Modification of Implementation Method)

[0291] like Fig.16 As shown, the third JIT seek control may also be installed in the JIT seek control unit 622c. Fig.16 It is a diagram showing the functional structure of the JIT seek control unit 622c in the sixth variation of the implementation method.

[0292] The JIT seek control unit 622 c sets a target acceleration, and sets a current instruction value of the VCM 13 in consideration of the target acceleration without considering the BEMF.

[0293] Without considering BEMF, Figure 3 The current i of VCM13 in the rising interval A1 and the flat interval A2 shown in FIG. VCM It can be expressed by the following formula 1".

[0294]

[0295] The JIT seek control unit 622c replaces the control instruction value determination unit 6224 (see Fig.10 ) and has a control instruction value determination unit 6224c. The control instruction value determination unit 6224c omits the BEMF coefficient setting unit 6225.

[0296] The control instruction value calculation unit 6226c may use a controller that does not consider BEMF. The control instruction value calculation unit 6226c receives the target position P tgt , target speed V tgt , and receives the target acceleration a from the target acceleration setting unit 6223 tgt The control instruction value calculation unit 6226c uses the target position P tgt , target speed V tgt 、Target acceleration a tgt , calculate the current indication value of VCM13.

[0297] For example, the control instruction value calculation unit 6226c calculates the current instruction value as follows. In the rising interval A1, it rises to the positive side according to the formula 1", and in the flat interval A2, it is maintained at approximately the current threshold value i thp In the falling interval A3, it falls from the positive side according to the time constant of the circuit 131. In the flat interval C1, it is maintained at approximately zero. In the rising interval D1, it rises to the negative side according to the formula after making the formula 1" with the opposite polarity. In the flat interval D2, it is maintained at approximately the current threshold i thpIn the falling interval D3, the circuit 131 decreases from the negative side according to the time constant (refer to Figure 6 ).

[0298] like Fig.17 As shown, the third JIT seek control may also be implemented in the servo control unit 64c. Fig.17 It is a diagram showing the functional configuration of a servo control unit 64 c in a sixth modification of the embodiment.

[0299] The servo control unit 64c replaces the JIT seek control unit 622 (see Fig.10 ) and has a JIT seek control unit 622c. The JIT seek control unit 622c has Fig.16 Same composition.

[0300] The current instruction value update unit 6227 updates the absolute value of the current instruction value and the virtual limit current i VCM_AFC_limit When the absolute value of the current indication value exceeds the imaginary limit current iVCM_AFC_limit When the absolute value of the current indication value is equal to the absolute value of the current limit (or the value obtained by subtracting a predetermined value from the absolute value), the current indication value is updated to the virtual limit current i VCM_AFC_limit This is the same as the third variant of the implementation example.

[0301] exist Fig.16 and Fig.17 The controller 3 is shown in FIG. Fig. 9 The operation of the seek control shown in the figure is performed by the controller 3. Figure 7 In the case of seek control shown, the current threshold i is omitted thn Alternatively, the controller 3 performs Figure 8 In the case of seek control shown, the current threshold i is omitted thp Related actions.

[0302] With such a configuration, in the disk device 1 as well, the AFC function can be enabled within the limit currents REF71 and REF72, and power consumption can be reduced while maintaining access performance.

[0303] Several embodiments of the present invention have been described, but these embodiments are provided as examples and are not intended to limit the scope of the invention. These new embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the scope of the invention. These embodiments and their variations are included in the scope and / or purpose of the invention, and are included in the invention described in the claims and their equivalents.

Claims

1. A disk device comprising: head; a disk having a recording surface; a motor that causes the head to seek along the recording surface; and a controller for controlling the motor, the controller, In a case where there is no rotation waiting time from the time when the head reaches the target track of the disk until the time when the head reaches the target sector, the absolute value of the motor current is increased in a first interval of a first period in which the head is accelerated or decelerated, the absolute value of the motor current is changed at a first average change rate in a second interval later than the first interval of the first period, and the absolute value of the motor current is reduced at a second average change rate that is steeper than the first average change rate in a third interval later than the second interval of the first period, In the case of the rotation waiting time, the absolute value of the motor current is increased in the 4th interval of the 2nd period in which the head is accelerated or decelerated, the absolute value of the motor current is changed at a third average change rate in a 5th interval later than the 4th interval of the 2nd period, the absolute value of the motor current is decreased at a 4th average change rate that is steeper than the 3rd average change rate in a 6th interval later than the 5th interval of the 2nd period, and the absolute value of the motor current is decreased at a 5th average change rate that is steeper than the 4th average change rate in a 7th interval later than the 6th interval of the 2nd period.

2. The disk device according to claim 1, The controller estimates a limiting current taking back electromotive force into consideration, and reduces the absolute value of the motor current in the sixth section at the fourth average change rate in accordance with a change in the absolute value of the limiting current when the rotation waiting time is provided.

3. The disk device according to claim 2, The controller estimates the limiting current taking into account the back electromotive force, generates a current indication value for the second period while having the rotation waiting time, corrects the current indication value for the sixth interval that exceeds the limiting current by replacing it with the limiting current, and drives the motor with the corrected current indication value.

4. The disk device according to claim 2, The controller changes the absolute value of the motor current at the third average change rate that is closer to zero than the average change rate of the absolute value of the limiting current in the fifth section.

5. The disk device according to claim 2, When the power supply voltage is set to V and the back EMF is set to V BEMF When the circuit resistance of the motor is set to R, the controller controls the motor by i VCM _ limit =(V-V BEMF ) / R estimates the limiting current i VCM _ limit .

6. The disk device according to claim 5, The controller uses the measured power supply voltage or the power supply voltage designed for the worst condition as the power supply voltage V.

7. The disk device according to claim 5, When the power supply voltage is set to V and the back EMF is set to V BEMF And the motor current in the sixth interval is set to i VCM When the controller uses R = (V - V BEMF ) / i VCM The estimated R is used as the circuit resistance R of the motor.

8. The disk device according to claim 5, The controller uses the measured back electromotive force or generates a voltage by V when the speed in the radial direction of the head is set to v and the current force constant is set to Kf. BEMF = vKf estimated V BEMF , as the back electromotive force V BEMF .

9. The disk device according to claim 5, The controller uses, as the velocity v in the radial direction of the head, a differential of a position demodulated from servo information read by the head from the disk, or a velocity estimated from the demodulated position and a current indication value.

10. The disk device according to claim 7, The controller uses the measured current, the current estimated by multiplying the second-order differential of the position demodulated from the servo information read by the head from the disk by the acceleration current conversion coefficient, or the current estimated by multiplying the acceleration estimated from the demodulated position and the current indication value by the acceleration current conversion coefficient as the motor current i VCM .

11. The disk device according to claim 8, The controller uses, as the circuit resistance R of the motor, R obtained by correcting the estimated R in consideration of continuous heat dissipation between the time of measurement and the time of use and heat generated by the operation of the motor.

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