disk device

Abstract

One embodiment provides a disk device capable of properly performing a write operation. According to one embodiment, a disk device having a first disk, a first head, a first actuator, and a controller is provided. The first actuator moves the first head relative to the first surface of the first disk. The controller performs positioning control on the first head via the first actuator, and controls the write operation of the first head to the first disk. The controller obtains information related to the state of a vibration source. The controller changes the value of a coefficient used to estimate the predicted position of the first head based on the information related to the state of the vibration source. The controller estimates the predicted position of the first head using the changed value of the coefficient. The controller performs a write operation on the first head when the estimated predicted position is below a threshold value, and prohibits the write operation on the first head when the estimated predicted position exceeds the threshold value.

Description

[0001] Related Application

[0002] This application claims priority based on Japanese Patent Application No. 2021-181249 (filing date: November 5, 2021), and the entire contents of the basic application are incorporated herein by reference. Technical Field

[0003] This embodiment relates to a disk device. Background Art

[0004] In a disk drive having a head and a disk, the head is moved relative to the surface of the disk to perform a writing operation on the disk. In the disk drive, it is desirable that the writing operation be performed appropriately. Summary of the Invention

[0005] One embodiment provides a disk device capable of performing a write operation appropriately.

[0006] According to one embodiment, a disk device having a first disk, a first head, a first actuator, and a controller is provided. The first actuator moves the first head relative to the first surface of the first disk. The controller performs positioning control on the first head via the first actuator, thereby controlling the first head's writing operation to the first disk. The controller obtains information related to the state of a vibration source. The controller changes the value of a coefficient used to estimate the predicted position of the first head based on the information related to the state of the vibration source. The controller estimates the predicted position of the first head using the changed value of the coefficient. The controller performs a writing operation on the first head when the estimated predicted position is below a threshold value, and prohibits the writing operation on the first head when the estimated predicted position exceeds the threshold value. BRIEF DESCRIPTION OF THE DRAWINGS

[0007] Figure 1 This is a diagram showing the structure of the disk device according to the first embodiment.

[0008] Figure 2 It is a plan view showing the structure of the disk in the first embodiment.

[0009] Figure 3 This is a plan view showing the positioning of the head in the first embodiment.

[0010] Figure 4 (a) and (b) are diagrams showing changes in the correlation between the actual position and the predicted position according to vibration in the first embodiment.

[0011] Figure 5 (a) and (b) are diagrams showing the data structure of coefficient information in the first embodiment.

[0012] Figure 6 This is a flowchart showing the operation of the disk device during tracking according to the first embodiment.

[0013] Figure 7 This is a flowchart showing the prediction position coefficient update process in the first embodiment.

[0014] Figure 8 This is a diagram showing the structure of a disk device according to the second embodiment.

[0015] Figure 9 It is a diagram showing the vibration transmission characteristics between actuators in the second embodiment.

[0016] Figure 10 (a) to (d) are diagrams showing changes in the seek current and the position error signal according to vibration in the second embodiment.

[0017] Figure 11 This is a diagram showing the difference in vibration transmission characteristics between heads in the second embodiment.

[0018] Figure 12 (a) to (d) are diagrams showing changes in the seek current and the position error signal according to vibration in the second embodiment.

[0019] Figure 13 (a) and (b) are diagrams showing the data structure of coefficient information in the second embodiment.

[0020] Figure 14 This is a flowchart showing the operation of the disk device during seek according to the second embodiment.

[0021] Figure 15 This is a flowchart showing the operation of the disk device during tracking according to the second embodiment.

[0022] Figure 16 This is a flowchart showing the prediction position coefficient update process in the second embodiment. DETAILED DESCRIPTION

[0023] Hereinafter, the disk device according to the embodiment will be described in detail with reference to the drawings. However, the present invention is not limited to these embodiments.

[0024] (First embodiment)

[0025] In the disk drive of the first embodiment, a write-inhibit determination is performed based on the predicted position of the head, but further efforts have been made to improve the accuracy of the write-inhibit determination.

[0026] For example, the disk device 100 is Figure 1 As shown. Figure 11 is a diagram illustrating the structure of disk device 100, with a portion of the structure of disk device 100 shown in a cross-sectional view and another portion shown in a block diagram. Hereinafter, the direction along the rotation axis of disk DK1 is referred to as the Z direction, and two directions orthogonal to each other in a plane perpendicular to the Z direction are referred to as the X direction and the Y direction.

[0027] The disk drive 100 includes a housing 1 , a disk DK1 , heads H0 and H1 , an actuator AC1 , a spindle motor 3 , a spindle 10 , RV (rotational vibration) sensors 11A and 11B, a shock sensor 12 , a write inhibit detector 13 , and a controller 5 .

[0028] The housing 1 includes a base 1a extending in a flat plate shape in the XY directions and a cover 1b (not shown). Cover 1b seals the base 1a from the +Z side, housing a disk DK1, a head H0, an actuator AC1, a spindle motor (SPM) 3, a spindle 10, an RV sensor 11, a shock sensor 12, and a write-inhibit detector 13.

[0029] like Figure 2 As shown, the disk DK1 is a substantially disk-shaped medium on which information is to be recorded. Figure 2 1 is a top view showing the structure of disk DK1. Disk DK1 is supported on the base of housing 1 so as to be rotatable about the Z axis via spindle 10. Disk DK1 may be a magnetic disk or a magneto-optical disk. The following mainly illustrates the case where disk DK1 is a magnetic disk. Disk DK1 has a recording surface M0 on the +Z side and a recording surface M1 on the -Z side. On each recording surface M0, M1 of disk DK1, a plurality of concentric tracks TR are defined in the radial direction by servo information pre-written in radial servo areas SR. The area between the servo areas SR on each recording surface M0, M1 of disk DK1 is a data area DR to which data can be written. Each track TR includes one or more sets of servo areas SR and data areas DR in the circumferential direction.

[0030] Figure 1 The illustrated head H0 is held by actuator AC1 and positioned opposite the recording surface M0 of disk DK1. Head H1 is held by actuator AC1 and positioned opposite the recording surface M1 of disk DK1. Each head H0, H1 comprises a write head and a read head. During seeks, for example, actuator AC1 moves heads H0, H1 relative to the recording surfaces M0, M1, positioning heads H0, H1 on any of a plurality of tracks TR.

[0031] Actuator AC1 includes a voice coil motor (VCM) 4 and actuator arms AM0 and AM1. Head H0 is positioned at the tip of actuator arm AM0, facing disk DK1 (recording surface M0). Head H1 is positioned at the tip of actuator arm AM1, facing disk DK1 (recording surface M1).

[0032] Alternatively, actuator AC1 may further include microactuators MA0 and MA1. In this case, microactuators MA0 and MA1 are located at the tips of actuator arms AM0 and AM1. Head H0 is located at the tip of microactuator MA0, on the disk DK1 side (recording surface M0 side). Head H1 is located at the tip of microactuator MA1, on the disk DK1 side (recording surface M1 side).

[0033] The actuator AC1 uses the voice coil motor 4 when seeking, etc. Figure 3 As shown, the actuator arms AM0 and AM1 are driven with the axis AX1 as the rotation center. Figure 3 1 is a diagram showing the positioning of the heads H0 and H1. When the actuator arms AM0 and AM1 are configured to rotate simultaneously, the actuator AC1 can also move the heads H0 and H1 simultaneously to position them.

[0034] For example, the actuator AC1 causes the heads H0 and H1 to seek horizontally on the track T via the actuator arms AM0 and AM1 , and positions the heads H0 and H1 toward the target track TR. The actuator AC1 causes the heads H0 and H1 to track on the target track TR.

[0035] Figure 1 The actuator arms AM0 and AM1 shown provide a pressing force to heads H0 and H1 that counteracts the lifting force of heads H0 and H1 caused by airflow during disk DK1 rotation. This maintains a constant lifting distance of heads H0 and H1 on the +Z and -Z sides of recording surfaces M0 and M1 of disk DK1. The spindle motor 3 rotates magnetic disk DK1 about a spindle 10. The voice coil motor 4 and spindle motor 3 are fixed to the base 1a of the housing 1.

[0036] The RV sensors 11A and 11B and the impact sensor 12 each detect vibrations of a vibration source. The vibration source is a source of vibrations that may affect the actuator AC1.

[0037] like Figure 3 As shown, RV sensors 11A and 11B are fixed to the base 1a of the housing 1 at positions sandwiching the disk DK1 in the XY plane. RV sensors 11A and 11B can detect the amount of vibration in the X and Y directions, respectively. The difference between the detection values of RV sensor 11A and RV sensor 11B is amplified by a differential amplifier (not shown) to detect the amount of vibration in the substantially circumferential direction of the disk DK1. RV sensors 11A and 11B provide the vibration detection results to the controller 5.

[0038] The shock sensor 12 can detect the amount of vibration in each of the X, Y, and Z directions. The amount of vibration detected by the shock sensor 110 can be displacement, velocity, acceleration, or any other physical quantity. The shock sensor 12 is fixed to the base 1a of the housing 1 and can detect the amount of vibration of the housing 1 in the X, Y, and Z directions.

[0039] The write inhibit detector 13 receives the detection result from the shock sensor 12. If the amount of vibration detected by the shock sensor 12 exceeds a predetermined threshold, the write inhibit detector 13 detects write inhibition. If the amount of vibration detected by the shock sensor 12 is within the predetermined threshold, the write inhibit detector 13 does not detect write inhibition.

[0040] The controller 5 is connected to the host system HS so as to be communicable therewith, and upon receiving a command from the host system HS, can perform control in accordance with the command.

[0041] The controller 5 includes a head amplifier 6 , a driver 7 , a read / write (R / W) channel 8 , a hard disk controller (HDC) 9 , a volatile memory 14 , a buffer memory 15 , and a nonvolatile memory 16 .

[0042] The controller 5 controls the entire disk drive 100 according to firmware pre-stored in the non-volatile memory 16 or disk DK1. This firmware includes initial firmware and control firmware used during normal operation. The initial firmware, which is first executed at startup, is stored in the non-volatile memory 16, for example, while the control firmware used during normal operation is stored in the disk DK1. Under control of the initial firmware, data is temporarily read from the disk DK1 into the buffer memory 15 and then stored in the volatile memory 14.

[0043] The head amplifier 6 selects heads H0 or H1, amplifies the write signal, and detects the read signal. The head amplifier 6 includes a write current control unit 6A, a read signal detection unit 6B, and a head selection unit 6C. The head selection unit 6C selects the head H to be used between heads H0 and H1. The controller 5 controls the position of head H relative to disk DK1 based on the servo information read by the selected head H. When head H is positioned, the write current control unit 6A controls the write current flowing to the write head of head H. When head H is positioned, the read signal detection unit 6B detects the signal read by the read head of head H. The head amplifier 6 can be implemented as an integrated circuit (IC).

[0044] The driver 7 drives the voice coil motor 4 and the spindle motor 3, and receives RV (rotational vibration) signals from the RV sensors 11A and 11B. The driver 7 includes a spindle motor (SPM) control unit 7A, a voice coil motor (VCM) control unit 7B, and an RV signal input unit 7D. The spindle motor control unit 7A controls the rotation of the spindle motor 3. The voice coil motor control unit 7B controls the drive of the voice coil motor 4. The RV signal input unit 7D receives rotational vibration signals (RV signals) from the RV sensors 11A and 11B.

[0045] Furthermore, when the actuator AC1 further includes microactuators MA0 and MA1, the driver 7 further includes a microactuator (MA) control unit 7C. The microactuator (MA) control unit 7C controls the driving of the microactuators MA0 and MA1, thereby finely adjusting the position of the head H.

[0046] The read / write channel 8 exchanges data between the head amplifier 6 and the hard disk controller 9. The data includes read data, write data, and servo information. The read / write channel 8 includes a write inhibit section 8A. This section includes a sensor write inhibit section 8A1 and an HDC write inhibit section 8A2.

[0047] The sensor write inhibit unit 8A1 receives the detection result of the write inhibit detector 13. If write inhibit is detected, the sensor write inhibit unit 8A1 supplies a write inhibit command to the head amplifier 6. If write inhibit is not detected, the sensor write inhibit unit 8A1 supplies a write enable command to the head amplifier 6.

[0048] The HDC write inhibit unit 8A2 receives the write inhibit determination result from the hard disk control unit 9. If the determination result is write inhibit, the HDC write inhibit unit 8A2 supplies a write inhibit command to the head amplifier 6. If the determination result is write enable, the HDC write inhibit unit 8A2 supplies a write enable command to the head amplifier 6.

[0049] The head amplifier 6 prevents the head H from writing to the disk DK1 when receiving a write disable command from at least one of the sensor write disable unit 8A1 and the HDC write disable unit 8A2.

[0050] When the head amplifier 6 receives write enable commands from both the sensor write disable unit 8A1 and the HDC write disable unit 8A2, it causes the head H to write to the disk DK1. Specifically, the write current control unit 6A controls the write current flowing to the write tip of the head H while the head H is positioned.

[0051] The hard disk control unit 9 performs write and read control based on write and read commands from an external source (e.g., the host system HS) of the disk device 100, and exchanges data between the external source and the read / write channel 8. The configuration including the drive 7, the read / write channel 8, and the hard disk control unit 9 can be implemented as a system on a chip.

[0052] The hard disk control unit 9 includes a command control unit 9A and a servo control unit 9B. The command control unit 9A controls operations in response to commands received from the host system HS. The command control unit 9A includes a command selector 9A1. When the hard disk control unit 9 receives a command from the host system HS, the command selector 9A1 identifies the received command and selects a control operation based on the identified command. The command selector 9A1 determines the address and other information contained in the command.

[0053] When the command is a write command, the command selection unit 9A1 selects write control according to the write command. The command selection unit 9A1 determines the write address and write data included in the write command.

[0054] The servo control unit 9B controls the position of the head H according to the control operation selected by the command selection unit 9A1. The servo control unit 9B includes a tracking control unit 9B1, a seek control unit 9B2, and a write operation determination unit 9B3.

[0055] The seek control unit 9B2 controls the head H to seek to the target track TR on the disk DK1 based on the address (e.g., write address) included in the command. The seek control unit 9B2 controls the actuator AC1 via the read / write channel 8 and the head amplifier 6, causing the head H to seek horizontally on the track T via the actuator arm AM, thereby positioning the head H toward the target track TR. The target track TR is the track TR corresponding to the address (e.g., write address) included in the command.

[0056] The tracking control unit 9B1 controls the tracking of the head H on the target track TR of the disk DK1. The tracking control unit 9B1 controls the actuator AC1 via the read / write channel 8 and the head amplifier 6, and causes the head H to track on the target track TR via the actuator arm AM.

[0057] Here, when the command is a write command, the hard disk control unit 9 has the function of performing a write inhibit determination. When the head H is positioned and tracking the target track according to the write address, the write operation determination unit 9B3 performs a write inhibit determination. There are several types of write inhibit determination, but among them, there are write inhibit determinations based on the current position and write inhibit determinations based on the predicted position. The write operation determination unit 9B3 includes a position operation determination unit 9B31 and a predicted position operation determination unit 9B32. The position operation determination unit 9B31 performs a write inhibit determination based on the current position, and the predicted position operation determination unit 9B32 performs a write inhibit determination based on the predicted position.

[0058] The servo control unit 9B demodulates the position error signal based on the servo information read from the servo area via the head H. The position error signal indicates the relative position of the head H from the center of the track TR. The servo control unit 9B calculates the current actual position of the head H and the velocity component immediately before the head H reaches the current actual position based on the position error signal. The servo control unit 9B can calculate the current actual position of the head H as the absolute value of the current displacement of the head H from the center of the track TR. The servo control unit 9B estimates the future predicted position based on the current actual position of the head H and the velocity component immediately before the head H reaches the current actual position. The servo control unit 9B can calculate the future predicted position of the head H as the absolute value of the future displacement of the head H from the center of the track TR.

[0059] The predicted position operation determination unit 9B32 performs a write prohibition determination based on the predicted position. If the estimated predicted position is below a threshold, the predicted position operation determination unit 9B32 determines that writing is possible. If the estimated predicted position exceeds the threshold, the predicted position operation determination unit 9B32 determines that writing is not possible. If the predicted position operation determination unit 9B32 determines that writing is possible, the servo control unit 9B performs a write operation with the head H to the disk DK1. If the predicted position operation determination unit 9B32 determines that writing is not possible, the servo control unit 9B does not perform a write operation with the head H to the disk DK1. To prevent data from being written beyond the target track TR, the estimated value of the predicted position used in the write prohibition determination is preferably accurate.

[0060] For example, assume that the servo control unit 9B is causing the head H to track the target track TR. The actual position measured using the servo information read by the head H is represented by p, and the predicted position predicted by the servo control unit 9B is represented by p^. The actual position p and the predicted position p^ each represent the absolute value of the position error from the radial center position of the target track TR. The servo control unit 9B acquires (samples) the servo information at predetermined sampling intervals and calculates the current actual position of the head H and the velocity component immediately before reaching the current actual position. The simplest implementation of the predicted position p^ is based on linear interpolation and is expressed by the following mathematical formula 1.

[0061] p^(k+1)=p(k)+(p(k)-p(k-1))=2p(k)-p(k-1)…Mathematical formula 1

[0062] In Equation 1, k represents the current sampling timing, k-1 represents the past sampling timing one sampling interval ago, and k+1 represents the future sampling timing one sampling interval later. As shown in Equation 1, the predicted position p^(k+1) one sampling interval in the future is calculated by linearly interpolating the current position p(k) by the displacement from the past (p(k) - p(k-1)).

[0063] The purpose of performing write inhibit determination using the predicted position is to reduce the possibility that the head H will overrun (overtravel) the target track TR and erode and overwrite data on the adjacent track TR when the head H is positioned toward the target track TR.

[0064] The position error signal indicating the position of the head H is obtained only at discrete times (sampling intervals), and there is a time delay between position demodulation and write-inhibit determination. Therefore, even if a write-inhibit determination is made based on the current actual position, even if a threshold is used to determine that writing is possible, data may actually be written beyond that threshold. To prevent data on adjacent tracks from being erased, this excess must be suppressed to a certain level. To this end, write-inhibit determinations based not only on the current actual position but also on a predicted future position are used.

[0065] Here, (p(k)-p(k-1)) represents the velocity component based on the displacement from one sampling interval ago to the present time. However, the velocity estimation error based on the displacement is large. Therefore, in the write-inhibit determination based on the predicted position in Mathematical Formula 1, a threshold value T is used that is higher than that used in the write-inhibit determination based on the current actual position. h1 Large threshold T h2 The judgment condition at this time is expressed by the following mathematical formula 2.

[0066] p^(k+1)=2p(k)-p(k-1)>T h2 ...Mathematical formula 2

[0067] In Mathematical Formula 2, if T h2 =a1×T h1 , then Mathematical Formula 2 can be rewritten as the following Mathematical Formula 3.

[0068] p^(k+1) / a1=(2 / a1)×p(k)+(-1 / a1)×p(k-1)>T h1 ...Mathematical formula 3

[0069] In Mathematical Formula 3, by introducing the generalized coefficients a and b, Mathematical Formula 3 can be rewritten as the following Mathematical Formula 4.

[0070] p^(k+1) / a1=a×p(k)+b×p(k-1)>T h1 ...Mathematical formula 4

[0071] The coefficients a and b in Equation 4 can be adapted (e.g., optimized) based on, for example, time-lapse data of the actual position. It is assumed that, when the coefficients a and b are adapted for a certain vibration state, the predicted position estimated using the coefficients a and b has a good correlation with the actual position. In this case, using the same coefficients a and b for a different vibration state may deteriorate prediction accuracy. This is presumably because the appropriate values (e.g., optimal values) of the coefficients a and b vary depending on the frequency components of the vibration.

[0072] For example, let's assume that actuator AC1 receives vibrations with a peak frequency component at frequency F (e.g., 5kHz). Figure 4 The spectrum SP is shown by the single-dot chain line in (a). Figure 4 : is a graph showing the change in the correlation between the actual position and the predicted position according to the vibration. The spectrum SP has a peak at the frequency F. In this state, if the servo control unit 9B estimates the predicted position by adjusting the coefficients a and b, the predicted position estimated by the coefficients a and b and the actual position are as follows: Figure 4 The distribution DS is as shown by the dotted line in (b). The distribution DS is generally along Figure 4 The distribution of the ideal correlation straight line shown by the middle dotted line indicates that the predicted position estimated using the coefficients a and b has a good correlation with the actual position.

[0073] At this time, it is assumed that the vibration received by actuator AC1 changes to a vibration containing a peak frequency component at frequency F' (for example, 10kHz). At this time, the position error signal is Figure 4 The spectrum SP' is shown by the double-dashed line in (a). The spectrum SP' has a peak at the frequency F'. In this state, if the servo control unit 9B uses the same coefficients a and b as above to estimate the predicted position, the predicted position estimated by the coefficients a and b and the actual position are as follows: Figure 4 (b) is distributed as DS' shown by the double-dashed line. Figure 4 The distribution of deviations from the ideal correlation straight line IL indicated by the middle dotted line indicates that the correlation between the predicted position estimated using the coefficients a and b and the actual position has deteriorated.

[0074] In contrast, the hard disk control unit 9 further includes a predicted position coefficient updating unit 9B4. The predicted position coefficient updating unit 9B4 obtains information related to the state of the vibration source. The predicted position coefficient updating unit 9B4 can obtain the detection results of the RV sensors 11A and 11B as information related to the state of the vibration source, or can obtain the position error signal generated by the servo control unit 9B as information related to the state of the vibration source. The predicted position coefficient updating unit 9B4 changes the values of the coefficients a and b used to estimate the predicted position of the head H based on the information related to the state of the vibration source. The predicted position coefficient updating unit 9B4 can estimate the frequency of the vibration of the vibration source based on the detection results of the RV sensors 11A and 11B, or can estimate the frequency of the vibration of the vibration source based on the position error signal. The predicted position coefficient updating unit 9B4 can change the values of the coefficients a and b based on the estimated frequency.

[0075] Furthermore, when the multiple heads H0 and H1 moved by actuator AC1 receive vibrations from a certain vibration source, the manner in which these vibrations are transmitted may differ. Even if the vibration frequency is the same, the appropriate values (e.g., optimal values) of the coefficients may differ for each head H0 and H1. Therefore, the predicted position coefficient update unit 9B4 may modify the values of the coefficients a and b for each head H0 and H1 based on the estimated frequency.

[0076] For example, the nonvolatile memory 16 or the disk DK1 may also store the following Figure 5 The coefficient information is shown. Figure 5 This is a diagram showing the data structure of coefficient information. Figure 5 (a) illustrates a frequency level definition table as part of coefficient information, Figure 5 (b) illustrates a prediction position coefficient table as another part of the coefficient information. Figure 5 In (b), the coefficients are represented by a (header identifier, frequency level) and b (header identifier, frequency level).

[0077] exist Figure 5 In the frequency level definition table shown in (a), frequency ranges and frequency levels are associated with multiple frequency ranges. For example, the frequency range F0 to F1 is defined as frequency level "0." The frequency range F1 to F2 is defined as frequency level "1." The frequency range FM to F(M+1) is defined as frequency level "M." M is an arbitrary integer greater than or equal to 2.

[0078] exist Figure 5In the prediction position coefficient table shown in (b), a head identifier (e.g., head number), a frequency level, and a prediction position coefficient are associated with each head for multiple frequency levels. For head H0 with header identifier "0," coefficients a(0,0) and b(0,0) correspond to frequency level "0," and coefficients a(0,M) and b(0,M) correspond to frequency level "M." For head H1 with header identifier "1," coefficients a(1,0) and b(1,0) correspond to frequency level "0," and coefficients a(1,M) and b(1,M) correspond to frequency level "M."

[0079] The prediction position coefficient updating unit 9B4 uses the estimated frequency Figure 5 Frequency level definition table shown in (a) and Figure 5 The prediction position coefficient table shown in (b) can update the values of coefficients a and b for each head H0 and H1.

[0080] In addition, the coefficient information for changing the values of coefficients a and b may also be used instead of Figure 5 The table shown in the example is installed in the disk device 100 in the form of a mathematical formula. For example, the nonvolatile memory 16 or the disk DK1 may store information of mathematical formulas such as the following mathematical formulas 5 and 6, and the prediction position coefficient update unit 9B4 may refer to them. a An arbitrary mathematical expression including the coefficient a expressed as a function of the peak frequency of vibration. b An arbitrary mathematical expression including the coefficient b expressed as a function of the peak frequency of vibration.

[0081] a(header identifier, frequency level) = f a (Peak frequency of vibration)… Equation 5

[0082] b(header identifier, frequency level) = f b (Peak frequency of vibration)… Equation 6

[0083] Next, use Figure 6 The operation of the disk device 100 will be described. Figure 6 This is a flowchart showing the tracking operation of the disk device 100. The disk device 100 can perform tracking at each sampling timing while the head H is tracking the target track TR. Figure 6 The actions shown are used as interrupt processing.

[0084] While the head H is tracking the target track TR, the controller 5 calculates the actual position of the head H based on servo demodulation (S1). The controller 5 reads servo information from the servo area SR via the read head of the head H. The controller 5 demodulates a position error signal based on the servo information. The position error signal indicates the relative position of the head H from the center of the track TR. The controller 5 calculates the current actual position of the head H based on the position error signal.

[0085] The controller 5 determines whether the actual position p(k) of the head H exceeds the threshold value T h1 (S2) If the actual position p(k) of the head H exceeds the threshold T h1 (Yes in S2), the controller 5 determines that write is prohibited (S11) and does not perform the write operation.

[0086] If the actual position p(k) of the head H is the threshold T h1 Next (if S2 is no), the controller 5 determines that there is a possibility of write permission and obtains the detection results of the RV sensors 11A, 11B and other sensors (S3). The controller 5 estimates the vibration state of the vibration source based on the detection results of the sensors (S4). The controller 5 can estimate the amplitude and direction of the vibration as the state of the vibration source. Based on the estimated vibration state, the controller 5 determines the vibration control instruction value in a manner to suppress the vibration (S5), and implements control based on the vibration control instruction value (S6). The controller 5 can implement excitation control to excite the actuator AC1 in a manner to offset the influence of the vibration as control.

[0087] The controller 5 performs the prediction position coefficient update process (S7). The controller 5 can perform Figure 7 The processes of S21 to S23 shown are regarded as prediction position coefficient updating processes. Figure 7 : is a flowchart showing the prediction position coefficient update process.

[0088] While implementing control in S6, the controller 5 generates a position error signal through servo demodulation (S21). Based on the position error signal, the controller 5 estimates the disturbance state of actuator AC1 (S22). The disturbance state includes vibrations caused by disturbances that cannot be completely suppressed by excitation control or other control methods (e.g., vibrations caused by a fan). The controller 5 can estimate the frequency of the vibrations caused by the disturbance as the disturbance state.

[0089] The controller 5 updates the values of coefficients a and b for obtaining the predicted position according to the estimated disturbance state (S23). The controller 5 may refer to the following example according to the frequency of the vibration caused by the disturbance: Figure 5 The coefficient information shown is used to update the values of coefficients a and b.

[0090] For example, if the frequency F of the vibration caused by the disturbance (refer to Figure 4 (a)) is within the frequency range of F0 to F1, the prediction position coefficient update unit 9B4 refers to Figure 5 The frequency level definition table shown in (a) defines the frequency level as "0". The prediction position coefficient update unit 9B4 refers to Figure 5 The prediction position coefficient table shown in (b) updates the coefficients of head H0 to a(0,0) and b(0,0) corresponding to frequency level "0", and updates the coefficients of head H1 to a(1,0) and b(1,0) corresponding to frequency level "0".

[0091] Alternatively, if the frequency F' of the vibration caused by the disturbance (refer to Figure 4 (a)) is within the frequency range of F1 to F2, the prediction position coefficient update unit 9B4 refers to Figure 5 The frequency level definition table shown in (a) determines the frequency level to be "1". The prediction position coefficient update unit 9B4 refers to Figure 5 The prediction position coefficient table shown in (b) updates the coefficients of head H0 to a(0, 1) and b(0, 1) corresponding to frequency level "1", and updates the coefficients of head H1 to a(1, 1) and b(1, 1) corresponding to frequency level "1".

[0092] When the values of coefficients a and b are updated, such as Figure 6 As shown, the controller 5 estimates the predicted position of the head H using the updated coefficients a and b (S8). The controller 5 can estimate the parameter p^(k+1) / a1 corresponding to the predicted position of the head H using Equation 4 using the updated coefficients a and b.

[0093] For example, in a case where the write operation should be performed by head H0 according to the write address contained in the write command, if the coefficients of head H0 are updated to a(0, 0) and b(0, 0) in S6, a(0, 0) and b(0, 0) can be substituted into formula 4 to infer the parameter p^(k+1) / a1.

[0094] The controller 5 determines whether the predicted position p^(k+1) of the head H exceeds the threshold value T h2 (S9) The controller 5 can use the updated coefficients a and b to determine whether the inequality of Mathematical Formula 4 holds. The controller 5 uses the updated coefficients a and b. If the inequality of Mathematical Formula 4 holds, it can be determined that the predicted position p^(k+1) of the head H exceeds the threshold value T h2 The controller 5 uses the updated coefficients a and b, and if the inequality in equation 4 does not hold, it can be determined that the predicted position p^(k+1) of the head H is at the threshold value T. h2 the following.

[0095] If the predicted position p^(k+1) of the head H exceeds the threshold T h2 (Yes in S9), the controller 5 determines that write is prohibited (S11), and does not perform the write operation of the head H.

[0096] If the predicted position p^(k+1) of the head H is the threshold T h2 Thereafter (No in S9 ), the controller 5 determines that writing is permitted ( S10 ) and performs a write operation of the head H. The controller 5 flows a write current to the write head of the head H and writes write data in the data region DR of the target track TR.

[0097] As described above, in the first embodiment, the controller 5 of the disk drive 100 obtains information related to the state of the vibration source, modifies the values of the coefficients used to estimate the predicted position of the head H based on the information related to the state of the vibration source, and uses the modified values of the coefficients to estimate the predicted position of the head H. This improves the accuracy of the estimated position, thereby improving the accuracy of the write-inhibit determination based on the predicted position. As a result, while preventing the head H from overwriting the target track TR and overwriting the adjacent track TR, it ensures that the head H can properly perform the write operation within the target track TR. In other words, even when vibration occurs, both improved reliability and improved performance of the write operation can be achieved, allowing for proper write operation.

[0098] In addition, Figure 6 In the illustrated operation, the processing of S3 may be omitted. In this case, the controller 5 may estimate the vibration state in S4 using the position error signal generated in S1 as information on the state of the vibration source.

[0099] (Second embodiment)

[0100] Next, a disk device 200 according to the second embodiment will be described. The following description will focus on the differences from the first embodiment.

[0101] In the first embodiment, the configuration and operation of the disk device 100 having one actuator are exemplified. However, in the second embodiment, the configuration and operation of the disk device 200 having multiple actuators (multi-actuator configuration) are exemplified.

[0102] The disk device 200 can be Figure 8 As shown. Figure 8 1 and 2 are diagrams showing the structure of the disk device 200 , with a portion of the structure of the disk device 200 being shown in a cross-sectional view and another portion being shown in a block diagram.

[0103] The disk drive 200 further includes a disk DK2, heads H2 and H3, an actuator AC2, a controller communication unit 17, and a controller 52. The controller 52 corresponds to the actuator AC1, and the controller 52 corresponds to the actuator AC2. Thus, the actuators AC1 and AC2 can be controlled independently of each other.

[0104] The disk DK2 is a substantially disk-shaped medium similar to the disk DK1 (see Figure 2 ) is supported by the base of the housing 1 so as to be rotatable about the Z axis along with disk DK1 via spindle 10. Disk DK2 is disposed between disk DK1 and base 1a in the Z direction. Disk DK2 has a recording surface M2 on the +Z side and a recording surface M3 on the -Z side.

[0105] Head H2 is held by actuator AC2 and positioned opposite the recording surface M2 of disk DK2. Head H3 is held by actuator AC2 and positioned opposite the recording surface M3 of disk DK2. Each head H2, H3 comprises a write head and a read head. During seeks, etc., actuator AC2 moves heads H2, H3 relative to recording surfaces M2, M3, positioning heads H2, H3 on any of a plurality of tracks TR.

[0106] Actuators AC1 and AC2 are configured to be independently drivable. Actuator AC2 includes a voice coil motor (VCM) 42 and actuator arms AM2 and AM3. Head H2 is positioned at the tip of actuator arm AM2, facing disk DK2 (on the recording surface M2 side). Head H3 is positioned at the tip of actuator arm AM2, facing disk DK2 (on the recording surface M3 side).

[0107] Actuator AC2 may also include microactuators MA2 and MA3. In this case, microactuators MA2 and MA3 are located at the tips of actuator arms AM2 and AM3. Head H2 is located at the tip of microactuator MA2, on the disk DK2 side (the recording surface M2 side). Head H3 is located at the tip of microactuator MA3, on the disk DK2 side (the recording surface M3 side).

[0108] The actuator AC2 uses the voice coil motor 42 to move the axis AX1 (see Figure 3 ) is the center of rotation and drives the actuator arms AM2 and AM3. When the actuator arms AM2 and AM3 are configured to rotate simultaneously, the actuator AC2 can also move the heads H2 and H3 simultaneously to position them.

[0109] For example, the actuator AC2 causes the heads H2 and H3 to seek horizontally on the track T via the actuator arms AM2 and AM3, and positions the heads H2 and H3 toward the target track TR. The actuator AC2 causes the heads H2 and H3 to track on the target track TR.

[0110] The controller communication unit 17 mediates communication between the controller 5 and the controller 52. The controller communication unit 17 includes a communication unit 17A. The communication unit 17A includes a vibration-related information communication unit 17A1.

[0111] Upon receiving a notification request for vibration-related information from the controller 5, the communication unit 17A transmits the notification request to the controller 52. The controller 52 may store the vibration-related information or generate the vibration-related information in response to the notification request. Upon receiving the notification request, the controller 52 supplies the vibration-related information to the vibration-related information communication unit 17A1 in response. The vibration-related information communication unit 17A1 transmits the vibration-related information to the controller 5.

[0112] Upon receiving a notification request for vibration-related information from the controller 52, the communication unit 17A transmits the notification request to the controller 5. The controller 5 may store the vibration-related information or generate the vibration-related information in response to the notification request. Upon receiving the notification request, the controller 5 supplies the vibration-related information to the vibration-related information communication unit 17A1 in response. The vibration-related information communication unit 17A1 transmits the vibration-related information to the controller 52.

[0113] The controller 52 is connected to the host system HS so as to be communicable therewith, and upon receiving a command from the host system HS, can perform control in accordance with the command.

[0114] The controller 52 includes a head amplifier 62 , a driver 72 , a read / write (R / W) channel 82 , and a hard disk controller (HDC) 92 .

[0115] The head amplifier 62 selects heads H2 or H3, amplifies the write signal, and detects the read signal. The head amplifier 62 includes a write current control unit 62A, a read signal detection unit 62B, and a head selection unit 62C. The head selection unit 62C selects the head H to be used between heads H2 and H3. The controller 5 controls the position of head H relative to disk DK2 based on the servo information read by the selected head H. The write current control unit 62A controls the write current flowing to the write head of head H while head H is positioned. The read signal detection unit 62B detects the signal read by the read head of head H while head H is positioned. The head amplifier 62 can be implemented as an integrated circuit (IC).

[0116] The driver 72 drives the voice coil motor 42 and the spindle motor 3, and receives RV (rotational vibration) signals from the RV sensors 11A and 11B. The driver 72 includes a spindle motor (SPM) control unit 72A, a voice coil motor (VCM) control unit 72B, and an RV signal input unit 72D. The spindle motor control unit 72A controls the rotation of the spindle motor 3. The voice coil motor control unit 72B controls the drive of the voice coil motor 42. The RV signal input unit 72D receives rotational vibration signals (RV signals) from the RV sensors 11A and 11B.

[0117] Furthermore, when the actuator AC2 further includes microactuators MA2 and MA3, the driver 72 further includes a microactuator (MA) control unit 7C. The microactuator (MA) control unit 7C controls the driving of the microactuators MA2 and MA3, thereby finely adjusting the position of the head H.

[0118] The read / write channel 82 exchanges data between the head amplifier 62 and the hard disk controller 92. The data includes read data, write data, and servo information. The read / write channel 82 includes a write inhibit section 82A. The write inhibit section 82A includes a sensor write inhibit section 82A1 and an HDC write inhibit section 82A2.

[0119] The sensor write inhibit unit 82A1 receives the detection result of the write inhibit detector 13. If write inhibit is detected, the sensor write inhibit unit 82A1 supplies a write inhibit command to the head amplifier 62. If write inhibit is not detected, the sensor write inhibit unit 82A1 supplies a write enable command to the head amplifier 62.

[0120] The HDC write inhibit unit 82A2 receives the write inhibit determination result from the hard disk control unit 92. If the determination result is write inhibit, the HDC write inhibit unit 82A2 supplies a write inhibit instruction to the head amplifier 62. If the determination result is write enable, the HDC write inhibit unit 82A2 supplies a write enable instruction to the head amplifier 62.

[0121] The head amplifier 62 prevents the head H from writing to the disk DK2 when receiving a write disable command from at least one of the sensor write disable unit 82A1 and the HDC write disable unit 82A2.

[0122] When the head amplifier 62 receives write enable commands from both the sensor write disable unit 82A1 and the HDC write disable unit 82A2, it causes the head H to write to the disk DK2. Specifically, the write current control unit 62A controls the write current flowing to the write tip of the head H while the head H is positioned.

[0123] The hard disk control unit 92 performs write and read control based on write and read commands from an external source (e.g., the host system HS) of the disk device 100, and exchanges data between the external source and the read / write channel 82. The configuration including the drive 72, the read / write channel 82, and the hard disk control unit 92 can be implemented as a system on a chip.

[0124] The hard disk control unit 92 includes a command control unit 92A and a servo control unit 92B. The command control unit 92A controls operations in response to commands received from the host system HS. The command control unit 92A includes a command selector 92A1. When the hard disk control unit 92 receives a command from the host system HS, the command selector 92A1 identifies the received command and selects a control operation based on the identified command. The command selector 92A1 determines the address and other information contained in the command.

[0125] When the command is a write command, the command selection unit 92A1 selects write control according to the write command. The command selection unit 92A1 determines the write address and write data included in the write command.

[0126] The servo control unit 92B controls the position of the selection head H according to the control operation selected by the command selection unit 92A1. The servo control unit 92B includes a tracking control unit 92B1, a seek control unit 92B2, and a write operation determination unit 92B3.

[0127] The seek control unit 92B2 controls the head H to seek to the target track TR on the disk DK2 based on the address (e.g., write address) included in the command. The seek control unit 92B2 controls the actuator AC2 via the read / write channel 82 and the head amplifier 62, causing the head H to seek horizontally on the track T via the actuator arm AM, thereby positioning the head H toward the target track TR. The target track is the track TR corresponding to the address (e.g., write address) included in the command.

[0128] The tracking control unit 92B1 controls tracking of the head H on the target track TR of the disk DK2. The tracking control unit 92B1 controls the actuator AC2 via the read / write channel 82 and the head amplifier 62, and causes the head H to track on the target track TR via the actuator arm AM.

[0129] Here, when the command is a write command, the hard disk control unit 92 has the function of performing a write inhibit determination. When the head is positioned and tracking the target track TR according to the write address, the write operation determination unit 92B3 performs a write inhibit determination. There are several types of write inhibit determination, but there are two types: a write inhibit determination based on the current position and a write inhibit determination based on the predicted position. The write operation determination unit 92B3 includes a position operation determination unit 92B31 and a predicted position operation determination unit 92B32. The position operation determination unit 92B31 performs a write inhibit determination based on the current position, and the predicted position operation determination unit 92B32 performs a write inhibit determination based on the predicted position.

[0130] The servo control unit 92B demodulates the position error signal based on the servo information read from the servo area via the head H. The position error signal indicates the relative position of the head H from the center of the track TR. The servo control unit 92B calculates the current actual position of the head H and the velocity component immediately before the head H reaches the current actual position based on the position error signal. The servo control unit 92B can calculate the current actual position of the head H as the absolute value of the current displacement of the head H from the center of the track TR. The servo control unit 92B estimates the future predicted position based on the current actual position of the head H and the velocity component immediately before the head H reaches the current actual position. The servo control unit 92B can calculate the future predicted position of the head H as the absolute value of the future displacement of the head H from the center of the track TR.

[0131] The predicted position operation determination unit 92B32 performs a write prohibition determination based on the predicted position. If the estimated predicted position is below a threshold, the predicted position operation determination unit 92B32 determines that writing is possible. If the estimated predicted position exceeds the threshold, the predicted position operation determination unit 92B32 determines that writing is not possible. If the predicted position operation determination unit 92B32 determines that writing is possible, the servo control unit 92B performs a write operation with the head H to the disk DK2. If the predicted position operation determination unit 92B32 determines that writing is not possible, the servo control unit 92B does not perform a write operation with the head H to the disk DK2. To prevent data from being written beyond the target track TR, the estimated value of the predicted position used in the write prohibition determination is preferably accurate.

[0132] For example, assume that the servo control unit 92B is causing the head H to track the target track TR. If the actual position measured using the servo information read by the head H is represented by p, and the predicted position predicted by the servo control unit 92B is represented by p^, a write inhibit determination based on the predicted position can be performed based on whether the inequality in Equation 3 or Equation 4 holds true.

[0133] The appropriate values (e.g., optimal values) of the coefficients a and b used in estimating the predicted position may vary due to the influence of vibrations on actuators AC1 and AC2, as in the first embodiment. However, in a multi-actuator configuration, the operating states of the other actuators have a greater influence than the interference. Actuators AC1 and AC2 each influence each other, but here, the affected actuator AC performing a write operation is referred to as the victim, and the actuator AC causing the influence is referred to as the aggressor.

[0134] When the interference source performs a seek operation, the shape of the VCM current flowing to the voice coil motor (VCM) changes the way it affects the object. The VCM current during seek is called seek current. The position error on the interference target side at this time is expressed by (position error) = (interference source current) × (cross-transfer function) × (interference target sensitivity function). The interference source current is the VCM current on the interference source side (seek current during seek). The cross-transfer function is the transfer function from the interference source current to the interference target side. The interference target sensitivity function is a function that represents the feedback characteristics of the VCM current on the interference target side.

[0135] The controller 52 of the actuator AC2 and the controller 5 of the actuator AC1 are functionally the same as Figure 9 The controller 52 includes a subtractor 521, a CTLR 522, a notch filter 523, an LS 524, an adder 525, a GMA 526, a notch filter 527, an adder 528, an adder 529, and an adder 530. The controller 5 includes a subtractor 501, a CTLR 502, a notch filter 503, an adder 504, a notch filter 505, an LS 506, an adder 507, a GMA 508, a notch filter 509, and an adder 510.

[0136] Let the cross transfer function between the voice coil motor 42 of actuator AC2 and the voice coil motor 4 of actuator AC1 be A ct In the controller 52, the position error signal generated by subtracting the head position signal POS from the servo position using the subtracter 521 is set to p2, the current supplied from the adder 529 to the voice coil motor 42 of the actuator AC2 is set to I2, and the feedback characteristic from the voice coil motor 42 to the subtracter 521 is set to F B2 In the controller 5, the position error signal generated by subtracting the head position signal POS from the servo position by the subtracter 501 is set to p1, the current supplied from the adder 509 to the voice coil motor 4 of the actuator AC1 is set to I1, and the feedback characteristic from the voice coil motor 4 to the subtracter 501 is set to F B1 .

[0137] For example, when the interference source is actuator AC2 and the interference target is actuator AC1, the interference source current is I2 and the cross transfer function is A ct , the interference object sensitivity function is F B1 , so the position error signal p1 of the head H (head H0 or head H1) of the actuator AC1 is expressed by the following mathematical formula 7.

[0138] p1=I2×A ct ×F B1 ...Mathematical formula 7

[0139] Alternatively, when the interference source is actuator AC1 and the interference target is actuator AC2, the interference source current is I1 and the cross transfer function is A ct , the interference object sensitivity function is F B2 , so the position error signal p2 of the head H (head H2 or head H3) of the actuator AC2 is expressed by the following mathematical formula 8.

[0140] p2=I1×A ct ×F B2 ...Mathematical formula 8

[0141] In a multi-actuator configuration, the frequency of vibration received by the interfering actuator AC may vary depending on the operation mode. This frequency of vibration received by the interfering actuator AC appears as the frequency of fluctuation in the position error signal of the interfering head H.

[0142] For example, when a seek operation is performed on the interference source side, the waveform of the interference source current depends on the seek control method used for the seek operation. Seek control methods include long-distance seek and short-distance seek. Long-distance seek is a control method in which the seek head H moves a relatively long distance, while short-distance seek is a control method in which the seek head H moves a relatively short distance. The frequency component of the seek current (i.e., the frequency of the vibration on the interference source side) may vary significantly depending on the seek distance.

[0143] In the case where the interference source is actuator AC2 and the interference target is actuator AC1, and the seek control mode of the interference source is long-distance seek, the seek current on the interference source side is as follows: Figure 10 As shown in (a), the position error signal of the head H1 on the interference object side changes with a relatively large amplitude. Figure 10 As shown in (b), it changes at a relatively slow frequency. Figure 10 (a) Figure 10 (b) is a diagram showing changes in seek current and position error signal when the interference source is actuator AC2, the interference target is actuator AC1, and the seek control method of the interference source is long-distance seek. Figure 10 The vertical axis of (a) represents the level of seek current. Figure 10 The vertical axis of (b) represents the level of the position error signal, Figure 10 (a) Figure 10 The horizontal axis of (b) represents time.

[0144] In the case where the interference source is actuator AC2 and the interference target is actuator AC1 and the seek control mode of the interference source is short-distance seek, the seek current on the interference source side is as follows: Figure 10 (c) shows a relatively small amplitude change. Figure 10 As shown in (d), it changes at a relatively fast frequency. Figure 10 (c) Figure 10 (d) is a graph showing changes in seek current and position error signal when the interference source is actuator AC2, the interference target is actuator AC1, and the seek control method of the interference source is short-distance seek. Figure 10 The vertical axis of (c) represents the level of seek current. Figure 10 The vertical axis of (d) represents the level of the position error signal, Figure 10 (c) Figure 10 The horizontal axis of (d) represents time.

[0145] Long-distance seeks use speed feedback control that causes the speed of the head H (the first-order differential value of the head position signal POS) to follow the target speed, and mode switching control that switches the seek mode (acceleration mode, constant speed mode, deceleration mode). Short-distance seeks use position feedback control that causes the position of the head H (head position signal POS) to follow the target position track, and feedforward control that generates seek current (VCM currents I1, I2) according to predetermined characteristics. Mode switching control can also be further used in short-distance seeks. In mode switching control, the frequency components of the seek current in each stage of seek control may be significantly different. Each stage of seek control includes a rise in the seek current waveform in the acceleration mode, a fall in the seek current waveform in the acceleration mode, a rise in the seek current waveform in the deceleration mode, and a fall in the seek current waveform in the deceleration mode.

[0146] For example, when the interference source is actuator AC2 and the interference target is actuator AC1, and the seek control mode of the interference source is long-distance seek, Figure 10 In the periods TP1, TP2, and TP3 shown in (a), the mode is switched to the acceleration mode, the constant speed mode, and the deceleration mode, respectively.

[0147] During the rise of the seek current waveform in the interference source period TP1 (acceleration mode), the position error signal of the interference target head H1 is as follows: Figure 10As shown in (b), the frequency changes at a relatively fast rate. When the seek current waveform of the interference source period TP1 falls, the position error signal of the interference target head H1 is as follows: Figure 10 As shown in (b), it changes at a relatively slow frequency.

[0148] During the rise of the seek current waveform in the interference source period TP3 (deceleration mode), the position error signal of the head H1 on the interference target side is as follows: Figure 10 As shown in (b), the frequency changes at a relatively fast rate. When the seek current waveform falls during the interference source period TP3, the position error signal of the head H1 on the interference target side is as follows: Figure 10 As shown in (b), it changes at a relatively slow frequency.

[0149] In addition, the cross transfer function varies greatly depending on the Z position of the head H. For example, when the interference source = actuator AC2 and the interference target = actuator AC1, Figure 11 As shown, the head H1 is located in the middle of the Z direction of the axis AX1 and is connected to the axis AX1 (refer to Figure 3 ) of the bending mode appears accordingly, with a relatively slow frequency F H1 On the other hand, the head H0 located at the top in the Z direction and close to the axis AX1 vibrates at a relatively fast frequency F corresponding to the fact that its mode is hardly observed. H0 vibration. Figure 11 Graphs showing differences in vibration transmission characteristics between heads.

[0150] When the interference source is actuator AC1 and the interference target is actuator AC2, although not shown, the head H2 (see FIG. 1 ) located in the middle of the axis AX1 in the Z direction is Figure 8 ), and by axis AX1 (refer to Figure 3 ) appears significantly, and thus vibrates at a relatively slow frequency. On the other hand, the head H3 located at the bottom in the Z direction near the axis AX1 vibrates at a relatively fast frequency, as its mode is hardly observed.

[0151] For example, when the interference source = actuator AC2 and the interference target = actuator AC1, Figure 12 (a) shows the change of the seek current on the interference source side. The head H0 on the interference target side corresponds to the uppermost position in the Z direction of the axis AX1. Figure 12 As shown in (b), it changes at a relatively fast frequency. Figure 12 (a) Figure 12 (b) is a diagram showing changes in the seek current and the position error signal when the interference source is actuator AC2 and the interference target is actuator AC1. Figure 12 The vertical axis of (a) represents the level of seek current. Figure 12The vertical axis of (b) represents the level of the position error signal, Figure 12 (a) Figure 12 The horizontal axis of (b) represents time.

[0152] In the case of interference source = actuator AC2 and interference target = actuator AC1, Figure 12 (c) shows the change of the seek current on the interference source side. The head H1 on the interference target side is located in the middle of the Z direction of the axis AX1. Figure 12 As shown in (d), it changes at a relatively slow frequency. Figure 12 (c) Figure 12 (d) is a diagram showing changes in the seek current and the position error signal when the interference source is actuator AC2 and the interference target is actuator AC1. Figure 12 The vertical axis of (c) represents the level of seek current. Figure 12 The vertical axis of (d) represents the level of the position error signal, Figure 12 (c) Figure 12 The horizontal axis of (d) represents time.

[0153] Therefore, the predicted position coefficient updaters 9B4 and 92B4 of the controllers 5 and 52 acquire the operation mode information as information on the state of the vibration source. The predicted position coefficient updaters 9B4 and 92B4 change the values of the coefficients a and b for estimating the predicted position of each head H based on the operation mode information.

[0154] For example, the nonvolatile memory 16, the disk DK1 or the disk DK2 may also store the following data: Figure 13 The coefficient information is shown. Figure 13 This is a diagram showing the data structure of coefficient information. Figure 13 (a) illustrates an action mode definition table as part of the coefficient information, Figure 13 (b) illustrates a prediction position coefficient table as another part of the coefficient information. Figure 13 In (b), the coefficients are represented by a (header identifier, operation mode) and b (header identifier, operation mode).

[0155] exist Figure 13In the action mode definition table shown in (a), the action state and the action mode are corresponded with each other for multiple action states. For example, the action state "tracking" is defined as action mode "0". The action state "fan vibrating" is defined as action mode "1". The action state "accelerating and rising during seek" is defined as action mode "2". The action state "accelerating and descending during seek" is defined as action mode "3". The action state "constant speed during seek" is defined as action mode "4". The action state "decelerating and rising during seek" is defined as action mode "5". The action state "decelerating and descending during seek" is defined as action mode "6". The action state "stable" is the state from the end of seek until the position of the head H is stabilized, and is defined as action mode "M". M is an arbitrary integer greater than 2.

[0156] exist Figure 13 In the prediction position coefficient table shown in (b), a head identifier (e.g., head number), an operation mode, and a prediction position coefficient are associated with each head for multiple operation modes. For head H0 with head identifier "0," coefficients a(0,0) and b(0,0) correspond to operation mode "0," and coefficients a(0,M) and b(0,M) correspond to operation mode "M." For head H1 with head identifier "1," coefficients a(1,0) and b(1,0) correspond to operation mode "0," and coefficients a(1,M) and b(1,M) correspond to operation mode "M."

[0157] Here, the controller controlling the interference source can understand the state of the interference source in the past, present, and future. The interference source controller then notifies the controller of the target device of the interference source of the state of the interference source. The target device controller can estimate the predicted position by switching the coefficients a and b used according to the specific situation. This minimizes performance degradation while preventing biased writing.

[0158] Next, use Figure 14 The operation of the disk device 200 will be described. Figure 14 This is a flowchart showing the operation of the disk device 200 during seek. Figure 14 The operation of the controller 52 on the interference source side during seek is exemplified in the case where the interference source is actuator AC2 and the interference target is actuator AC1. The disk device 200 can perform seek operation at each sampling timing while the head H is being sought. Figure 14 The actions shown are used as interrupt processing.

[0159] During a seek, the controller 52 calculates the actual position of the head H based on servo demodulation (S31). The controller 52 reads servo information from the servo area SR via the read head of the head H. The controller 52 demodulates a position error signal based on the servo information. The position error signal indicates the relative position of the head H from the center of the track TR. The controller 52 calculates the current actual position of the head H based on the position error signal.

[0160] The controller 52 obtains detection results from sensors such as the RV sensors 11A and 11B via the controller 5 and the controller communication unit 17, and estimates the vibration state of the vibration source based on the sensor detection results (S32). The controller 52 can estimate the amplitude and direction of the vibration as the state of the vibration source. Based on the estimated vibration state, the controller 52 determines a vibration control instruction value to suppress the vibration (S33) and implements control based on the vibration control instruction value (S34). The controller 52 can implement excitation control to excite the actuator AC2 to offset the effects of the vibration as control. The controller 52 determines whether to switch the seek mode based on the progress of the seek control (S35). For example, if the current seek mode is acceleration mode, the controller 52 determines whether to switch from acceleration mode to constant speed mode. If the current seek mode is constant speed mode, the controller 52 determines whether to switch from constant speed mode to deceleration mode. The controller 52 notifies the controller 5 on the interfering object side of the operation mode information as needed (S36). For example, if it is determined in S35 that the acceleration mode should be switched to the constant speed mode, the controller 52 notifies the controller 5 of the operation mode information indicating that the seek mode after switching is the constant speed mode. If it is determined in S35 that the constant speed mode should be switched to the deceleration mode, the controller 52 notifies the controller 5 of the operation mode information indicating that the seek mode after switching is the deceleration mode.

[0161] use Figure 15 Other operations of the disk device 200 will be described. Figure 15 This is a flowchart showing the operation of the disk device 200 during tracking. Figure 15 The left figure illustrates the operation of the controller 52 on the interference source side in any state when the interference source is actuator AC2 and the interference target is actuator AC1. The controller 52 can perform the operation at each sampling timing in any state. Figure 15 The action shown in the left figure is used as interrupt processing. Figure 15 The right figure illustrates the tracking operation of the controller 5 on the interference target side when the interference source is actuator AC2 and the interference target is actuator AC1. The controller 5 can perform tracking at each sampling timing while the head H is tracking the target track TR. Figure 15 The action shown in the right figure is used as interrupt processing.

[0162] After performing steps S1 and S2, the controller 5 checks the operation mode of the other actuators AC (S41). The controller 5 sends a request to send the operation mode information to the controller 52 via the controller communication unit 17. The controller 52 waits until the request to send the operation mode information is received (no in S51). If the request to send the operation mode information is received (yes in S51), the controller 5 sends the operation mode information of the actuator AC2 to the controller 5 via the controller communication unit 17 (S52). The controller 5 receives the operation mode information. The controller 5 estimates the vibration state of the vibration source based on the operation mode information (S42). The operation mode information is information indicating the operation state of the actuator AC2.

[0163] After performing the processing of S5 and S6, the controller 5 performs the predicted position coefficient update processing (S43). The controller 5 can perform Figure 16 The processing of S61 to S62 shown is regarded as the prediction position coefficient updating processing. Figure 16 : is a flowchart showing the prediction position coefficient update process.

[0164] The controller 5 checks the operation mode of the other actuators AC (S61). The controller 5 transmits a request to transmit the operation mode information to the controller 52 via the controller communication unit 17. The controller 52 waits until the request to transmit the operation mode information is received (No in S53). If the request to transmit the operation mode information is received (Yes in S53), the controller 52 transmits the operation mode information of the actuator AC2 to the controller 5 via the controller communication unit 17 (S54). The controller 5 receives the operation mode information.

[0165] The controller 5 updates the values of the coefficients a and b for obtaining the predicted position for each head H according to the motion mode information (S62). The controller 5 can refer to the following example according to the motion mode of the actuator AC2 indicated by the motion mode information. Figure 13 The coefficient information shown is used to update the values of coefficients a and b.

[0166] For example, when the heads H0 and H1 are tracking by the actuator AC2, the predicted position coefficient updating unit 9B4 refers to Figure 13 The operation mode definition table shown in (a) defines the operation mode as "0". The prediction position coefficient update unit 9B4 refers to Figure 13 The predicted position coefficient table shown in (b) updates the coefficients of head H0 to a(0,0) and b(0,0) corresponding to action mode "0", and updates the coefficients of head H1 to a(1,0) and b(1,0) corresponding to action mode "0".

[0167] Alternatively, when the heads H0 and H1 are in the acceleration mode during seek by the actuator AC2 and the waveform is rising, the predicted position coefficient update unit 9B4 refers to Figure 13 The operation mode definition table shown in (a) defines the operation mode as "2". The prediction position coefficient update unit 9B4 refers to Figure 13 The predicted position coefficient table shown in (b) updates the coefficients of head H0 to a(0, 2) and b(0, 2) corresponding to action mode "0", and updates the coefficients of head H1 to a(1, 2) and b(1, 2) corresponding to action mode "0".

[0168] Afterwards, if Figure 15 As shown, the controller 5 performs the processing after S8.

[0169] As described above, in the second embodiment, the controller 5 of the disk drive 200 obtains information related to the operating states of other actuators, modifies the values of the coefficients used to estimate the predicted position of the head H based on this information, and uses the modified values of the coefficients to estimate the predicted position of the head H. This improves the accuracy of the estimated predicted position, thereby improving the accuracy of write-inhibit determinations based on the predicted position. As a result, while preventing the head H from overwriting the target track TR and overlapping the adjacent track TR, it ensures that the head H can properly perform the write operation within the target track TR. In other words, even when vibration occurs, both improved reliability and improved performance of the write operation can be achieved, allowing for proper write operation.

[0170] Furthermore, the information related to the operating state of the other actuators obtained by the controller on the interfering object side during coefficient update may include information related to the seek control mode and information related to the seek distance. The information related to the seek control mode includes information indicating whether the seek control mode of the other actuator is long-distance seek or short-distance seek. The information related to the seek distance includes information indicating whether the seek distance of the other actuator is equivalent to the seek distance of long-distance seek or the seek distance of short-distance seek.

[0171] Alternatively, the information related to the operating state of the other actuators obtained by the controller of the interference object side when updating the coefficients may also be the first-order differential value of the seek current of the other actuators. In this case, the controller of the interference object side can estimate the frequency of the vibration based on the first-order differential value of the seek current of the other actuators, referring to Figure 5 The coefficients a and b are updated using the coefficient information shown.

[0172] While some embodiments of the present invention have been described, these embodiments are provided as examples and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways and can be omitted, replaced, or modified without departing from the spirit of the invention. These embodiments and their variations are included within the scope and spirit of the invention and are included in the invention described in the claims and their equivalents.

[0173] Description of Reference Numerals

[0174] 5, 52 controllers, 100, 200 disk devices, AC1, AC2 actuators, DK1, DK2 disks, H0~H3 heads, 4 voice coil motors.

Claims

1. A disk device comprising: 1st set; No. 1; a first actuator for moving the first head relative to the first surface of the first disk; and a controller that controls the positioning of the first head via the first actuator, and controls the writing operation of the first head to the first disk; The controller obtains information related to the state of the vibration source, changes the value of the coefficient used to estimate the predicted position of the first head according to the information related to the state of the vibration source, uses the changed value of the coefficient to estimate the predicted position of the first head, performs the writing action of the first head when the estimated predicted position is below a threshold value, and prohibits the writing action of the first head when the estimated predicted position exceeds the threshold value.

2. The disk device according to claim 1, further comprising a sensor for detecting vibration of the vibration source, The controller obtains a detection result of the sensor as information related to a state of the vibration source.

3. The disk device according to claim 1, Also has a second head, The first actuator moves the second head relative to the second surface of the first disk. The controller obtains information on the state of the vibration source and changes the values of the coefficients used to estimate the predicted position of the first head and the coefficients used to estimate the predicted position of the second head according to the information on the state of the vibration source.

4. The disk device according to claim 1, further comprising: 2nd set; No. 3; a second actuator for moving the third head relative to the first surface of the second disk; and The second controller controls the positioning of the third head via the second actuator, thereby controlling the writing operation of the third head to the second disk. The controller obtains information on the state of the second actuator from the second controller, and changes a value of a coefficient for estimating the predicted position of the first head based on the information on the state of the second actuator.

5. The disk device according to claim 4, The second controller obtains information related to the state of the first actuator from the controller, changes the value of the coefficient used to estimate the predicted position of the third head according to the information related to the state of the first actuator, uses the changed value of the coefficient to estimate the predicted position of the third head, performs the writing action of the third head when the estimated predicted position is below a threshold, and prohibits the writing action of the third head when the estimated predicted position exceeds the threshold.

6. The disk device according to claim 4, It also has the second and fourth heads. The first actuator moves the second head relative to the second surface of the first disk. The second actuator moves the fourth head relative to the second surface of the second disk. The controller obtains information related to the state of the second actuator from the second controller, and changes the values of the coefficients used to estimate the predicted position of the first head and the coefficients used to estimate the predicted position of the second head according to the information related to the state of the second actuator. The second controller obtains information related to the state of the first actuator from the controller, and changes the values of the coefficients used to estimate the predicted position of the third head and the coefficients used to estimate the predicted position of the fourth head according to the information related to the state of the first actuator.

7. The disk device according to claim 4, The state of the second actuator includes at least one of a seek control method of the second actuator, a change state of a seek current of the second actuator, and a first-order differential value of the seek current of the second actuator.

8. The disk device according to claim 5, The state of the second actuator includes at least one of a seek control mode of the second actuator, a change state of a seek current of the second actuator, and a first-order differential value of the seek current of the second actuator. The state of the first actuator includes at least one of a seek control method of the first actuator, a change state of a seek current of the first actuator, and a first-order differential value of the seek current of the first actuator.

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