Disk device

Abstract

The present invention provides a disk device capable of appropriately suppressing the speed of a head when the head rides on a ramp. The disk device includes a disk, a head for accessing the disk, a motor for moving the head, a ramp, a motor driver, and a processor. The motor driver starts a retraction operation of retracting the head toward the ramp by controlling the voltage applied to the motor when the voltage value of the power supply voltage is lower than a first threshold. The processor sends an instruction related to applying a brake to the movement of the head to the motor driver when the voltage value of the power supply voltage is lower than a second threshold greater than the first threshold.

Description

[0001] This application claims priority based on Japanese Patent Application No. 2021-154048 (filing date: September 22, 2021). This application incorporates the entire contents of the base application by reference thereto. Technical Field

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

[0003] In a disk device, when power is turned off, a retraction operation is performed to retract the head onto a ramp. Summary of the Invention

[0004] In the retraction operation, if the speed of the head when mounting the head exceeds an appropriate level, the head recoils at the ramp and returns to the disk, and the disk may be damaged.

[0005] An object of one embodiment is to provide a disk device that can appropriately suppress the speed of the head when the head mounts on the ramp.

[0006] According to one embodiment, a disk device includes a disk, a head that accesses the disk, a motor that moves the head, a ramp, a motor driver, and a processor. The motor driver starts a retraction operation of retracting the head onto the ramp by controlling the voltage applied to the motor when the voltage value of the power supply voltage is lower than a first threshold. The processor sends an instruction related to applying a brake to the movement of the head to the motor driver when the voltage value of the power supply voltage is lower than a second threshold that is larger than the first threshold. Brief Description of the Drawings

[0007] Figure 1 It is a diagram showing an example of the configuration of the disk device of the first embodiment.

[0008] Figure 2 It is a diagram showing an example of the configuration of the disk of the first embodiment.

[0009] Figure 3 It is a schematic diagram showing an example of the seek control implemented in the disk device of the first embodiment.

[0010] Figure 4 It is shown for implementing Figure 3 A diagram showing an example of the transition of the voltage value of the drive voltage applied to the VCM in the first embodiment of the seek control shown.

[0011] Figure 5 It is shown in Figure 3 A diagram showing an example of the transition of the drive voltage applied to the VCM in the first embodiment when power is turned off during the seek control shown.

[0012] Figure 6 This is a flowchart showing an example of the operation of the processor according to the first embodiment.

[0013] Figure 7 This is a diagram showing an example of the relationship between the moving speed in the retracting direction of the head and the braking voltage value according to the first embodiment.

[0014] Figure 8 This is a diagram showing an example of the relationship between the distance of the head from the ramp and the braking voltage value according to the first embodiment.

[0015] Figure 9 This is a flowchart showing an example of the operation of the motor driver according to the first embodiment.

[0016] Figure 10 This is a diagram showing an example of the Figure 3 transition of the voltage applied to the VCM in the second embodiment in the case where a power-off occurs during the seek control shown.

[0017] Figure 11 This is a flowchart showing an example of the operation of the processor according to the second embodiment.

[0018] Figure 12 This is a flowchart showing an example of the operation of the motor driver according to the second embodiment.

[0019] Explanation of Reference Numerals

[0020] 1 Disk device, 2 I / F bus, 3 Power supply line, 11 Disk, 12 Spindle motor, 13 Ramp, 15 Actuator arm, 20 Power supply circuit, 21 Motor driver, 22 Head, 22r Read head, 22w Write head, 23 HDC, 24 Preamplifier, 25 RWC, 26 Processor, 27 RAM, 28 FROM, 29 Buffer memory, 30 Controller, 40 Host, 41 Power supply, 110 Servo area, 111, 111a, 111b Tracks. Detailed Description of the Embodiment

[0021] Hereinafter, the disk device according to the embodiment will be described in detail with reference to the drawings. In addition, the present invention is not limited by these embodiments.

[0022] (First Embodiment)

[0023] Figure 1This is a diagram showing an example of the configuration of the disk device according to the first embodiment. The disk device 1 is connected to the host 40 via the interface (I / F) bus 2. In addition, the disk device 1 is connected to an external power supply 41 via the power supply line 3. The disk device 1 operates based on the power supplied from the power supply 41 via the power supply line 3. The power supply 41 may also be provided in the host 40. The voltage applied to the power supply line 3 is referred to as the power supply voltage.

[0024] The disk device 1 receives an access command from the host 40. The access command includes a write command for requesting data writing and a read command for requesting data reading.

[0025] The disk device 1 includes one or more disks 11. For Figure 1 the sake of easy understanding, it is assumed that the disk device 1 includes one disk 11. The disk device 1 accesses the disk 11 according to the access command. The access to the disk 11 includes writing data to the disk 11 and reading data from the disk 11.

[0026] Figure 2 This is a diagram showing an example of the configuration of the disk 11 according to the first embodiment. On the recording surface of the disk 11, for example, servo information is written by a servo writer or the like before shipment. The servo information includes sector / cylinder information and a pulse train pattern. The sector / cylinder information provides servo addresses in the circumferential direction and the radial direction of the disk 11. The sector / cylinder information is used in the seek control for moving the head 22 to the target track. The pulse train pattern is used in the tracking control for maintaining the head 22 on the target track. In addition, the servo information may also be written to the disk 11 after shipment by self-servo writing (SSW). For Figure 2 the sake of example, the servo regions 110 arranged radially are shown as an example of the configuration of the servo regions where the servo information is written.

[0027] On the recording surface of the disk 11, a plurality of concentric tracks 111 with different radii are provided at a predetermined pitch. Many sectors are continuously formed on each track 111. The head 22 performs data writing and data reading on each sector.

[0028] The explanation will return Figure 1 .

[0029] In addition to the disk 11 and the head 22, the disk device 1 further includes a spindle motor 12, a ramp 13, an actuator arm 15, a voice coil motor (VCM) 16, a power supply circuit 20, a motor driver 21, a hard disk controller (HDC) 23, a preamplifier 24, a read / write channel (RWC) 25, a processor 26, a RAM (Random Access Memory), a FROM (Flash Read Only Memory), and a buffer memory 29.

[0030] In addition, the configuration including the HDC 23, the RWC 25, and the processor 26 can also be regarded as a controller 30. The controller 30 may also include other elements such as the RAM 27, the FROM 28, or the buffer memory 29.

[0031] The power supply circuit 20 distributes the power supplied from the power source 41 to each component of the disk device 1. The power supply circuit 20 may also perform voltage conversion according to the power supply destination.

[0032] The spindle motor 12 rotates the disk 11 around the rotation axis at a predetermined rotational speed.

[0033] The head 22 uses the write head 22w and the read head 22r it has to perform access to the disk 11. The write head 22w performs writing to the disk 11. The read head 22r performs reading from the disk 11. The head 22 is mounted at the tip of the actuator arm 15. The head 22 moves along the radial direction of the disk 11 through the VCM 16. When the rotation of the disk 11 stops, etc., the head 22 moves onto the ramp 13.

[0034] When reading data from the disk 11, the preamplifier 24 amplifies and outputs the signal read from the disk 11 and supplies it to the RWC 25. In addition, the preamplifier 24 amplifies the signal corresponding to the data to be written supplied from the RWC 25 and supplies it to the head 22.

[0035] The HDC 23 controls the data transmission and reception between the host 40 via the I / F bus 2, controls the buffer memory 29, and performs error correction processing on the read data, etc.

[0036] The buffer memory 29 is a buffer memory provided to absorb the difference between the access speed between the host 40 and the disk device 1 and the access speed to the disk 11.

[0037] The buffer memory 29 is constituted by a volatile memory, for example, capable of high-speed operation. The type of the memory constituting the buffer memory 29 is not limited to a specific type. The buffer memory 29 can be constituted by, for example, a DRAM (Dynamic Random Access Memory), an SRAM (Static Random Access Memory), or a combination thereof.

[0038] The RWC 25 encodes and modulates the data to be written supplied from the HDC 23 and supplies it to the preamplifier 24. Further, the RWC 25 encodes and demodulates the signal read from the magnetic disk 11 and supplied from the preamplifier 24 and outputs it as digital data to the HDC 23.

[0039] The processor 26 is a processing unit such as a CPU (Central Processing Unit) or a DSP (Digital Signal Processor). The processor 26 may be constituted by two or more processing units. The RAM 27, the FROM (Flash Read Only Memory) 28, and the buffer memory 29 are connected to the processor 26.

[0040] The RAM 27 is constituted by, for example, a DRAM, an SRAM, or a combination thereof. The RAM 27 is used by the processor 26 as a memory for operation. For example, the RAM 27 is used as an area for loading a firmware program or an area for holding various management data.

[0041] The FROM 28 is a non-volatile memory. The processor 26 controls the overall operation of the magnetic disk device 1 in accordance with the firmware programs pre-stored in the FROM 28 and the magnetic disk 11. The processor 26 loads the firmware programs pre-stored in the FROM 28 and the magnetic disk 11 into the RAM 27 and executes the control of the motor driver 21, the preamplifier 24, the RWC 25, the HDC 23, etc. in accordance with the loaded firmware programs.

[0042] In particular, the processor 26 controls the positioning of the magnetic head 22. In the positioning control, the processor 26 uses the servo information read by the magnetic head 22 as a feedback input and calculates the voltage value of the drive voltage of the VCM 16 required to move the magnetic head 22 to the target position. Then, the processor 26 sends an indication value representing the calculated voltage value to the motor driver 21. This indication value is referred to as the first indication value. In the positioning control, in order to accurately position the magnetic head 22, the processor 26 repeatedly executes the calculation of the first indication value and the sending of the first indication value at a short time period.

[0043] The motor driver 21 drives the VCM 16 and the spindle motor 12. In particular, for the VCM 16, a drive voltage having a voltage value indicated by a first indication value received from the processor 26 is applied to the VCM 16. The VCM 16 is driven by the drive voltage applied from the motor driver 21, and accelerates or decelerates the moving speed of the head 22.

[0044] The motor driver 21 further controls the VCM 16 to perform a retraction operation when the power is turned off (that is, the supply of power from the power supply 41 is interrupted). Specifically, when the voltage value of the power supply voltage is lower than a threshold value Thd, the motor driver 21 ends the driving of the VCM 16 based on the positioning control, and retracts the head 22 to the ramp 13. The threshold value Thd is smaller than the rated voltage value of the disk device 1. That is, the motor driver 21 detects the occurrence of power-off by detecting a voltage drop in the power supply voltage.

[0045] When the motor driver 21 retracts the head 22 to the ramp 13, a voltage having a pulse-shaped waveform is repeatedly applied to the VCM 16 at a predetermined time period. That is, the motor driver 21 applies a voltage to the VCM 16 in an application mode in which pulse-on and pulse-off are repeated at a predetermined time period. The motor driver 21 calculates a state quantity (position or speed) of the VCM 16 based on the back electromotive force of the VCM 16 during the pulse-off period, and uses this state quantity as a feedback input to determine the wave height of the voltage having a pulse-shaped waveform applied during the subsequent pulse-on period. Hereinafter, the voltage having a pulse-shaped waveform will be simply referred to as a pulse.

[0046] In the retraction operation, in either the case where the speed of the head 22 when riding on the ramp 13 is too fast or too slow, the head 22 cannot ride on the ramp 13 normally. In particular, when the speed at which the head 22 approaches the ramp 13 exceeds an appropriate level, the head 22 recoils at the ramp 13, and the head 22 returns to the disk 11. When the head 22 returns to the disk 11, the disk 11 may be damaged by the head 22. In order to prevent such damage to the disk 11, it is desirable to control the speed of the head 22 in such a way as to avoid the speed at which the head 22 approaches the ramp 13 from exceeding an appropriate level.

[0047] For example, consider the case where the head 22 moves as shown in Figure 3 FIG. Figure 3 is a schematic diagram showing an example of the seek control implemented in the disk device 1 of the first embodiment.

[0048] When the head 22 is moved from the position Pa for accessing a certain track 111a to the position Pb for accessing another track 111b located on the outer peripheral side of the track 111a, the speed of the head 22 is accelerated in the direction towards the ramp 13. After the acceleration is completed, it is maintained at a constant speed, and then decelerated in such a way that the head 22 can stop at the position Pb.

[0049] Generally, in order to shorten the time required for seek control, the maximum moving speed of the head in seek control is high. And this maximum moving speed exceeds the appropriate level when the head approaches the ramp. Thus, Figure 3 when a power-off occurs during the seek control process shown (especially before the start of deceleration), in order to prevent the speed of the head 22 approaching the ramp 13 from exceeding the appropriate level, sometimes a sharp braking is required.

[0050] Here, a technique compared with the first embodiment will be described. The technique compared with the first embodiment is denoted as a comparative example. According to the comparative example, if the occurrence of a power-off is detected, a retraction operation is started based on the detection of the occurrence of the power-off. In the retraction operation, the motor driver controls the amplitude of each pulse so that the speed of the head when riding on the ramp is within an appropriate range.

[0051] However, according to the voltage application pattern during the retraction operation, the state of applying the voltage for braking cannot be maintained, so it is difficult to apply a sharp braking to the movement of the head. Thus, according to the comparative example, sometimes, the speed of the head when riding on the ramp cannot be decelerated to an appropriate level, and the occurrence of disk damage cannot be prevented.

[0052] In contrast, according to the first embodiment, the processor 26 detects the occurrence of a power-off at a timing earlier than the motor driver 21. And the processor 26 stops the positioning control based on the detection of the occurrence of the power-off, and instructs the motor driver 21 to apply a braking force to the movement of the head 22.

[0053] More specifically, when the voltage value of the power supply voltage is lower than the threshold Thp, the processor 26 detects that a power supply disconnection has occurred. Thp is larger than Thd and smaller than the voltage value of the rated voltage of the disk device 1. Since the processor 26 uses the threshold Thp, which is larger than the threshold Thd used by the motor driver 21 in detecting the occurrence of a power supply disconnection, in detecting the occurrence of a power supply disconnection, the processor 26 can detect the occurrence of a power supply disconnection earlier than the motor driver 21. When the processor 26 detects that a power supply disconnection has occurred, it calculates the voltage value of the drive voltage of the VCM 16 for applying a brake to the movement of the head 22. The voltage value of the drive voltage of the VCM 16 for applying a brake to the movement of the head 22 is referred to as the brake voltage value. The processor 26 sends an indication value indicating the brake voltage value to the motor driver 21. This indication value is referred to as the second indication value. The motor driver 21 applies a voltage of the voltage value (that is, the brake voltage value) indicated by the second indication value to the VCM 16.

[0054] If the processor 26 repeatedly sends the second indication value, the motor driver 21 can continuously apply a brake to the movement of the head 22 during the period of receiving the transmission of the second indication value. Thus, when the motor driver 21 uses the second indication value to apply a brake to the movement of the head 22, a stronger brake can be applied compared to the case where a brake is applied to the movement of the head 22 by a retraction operation.

[0055] That is, according to the first embodiment, a stronger brake can be applied at the time of a power supply disconnection compared to the comparative example. Therefore, the speed of the head 22 when the head 22 rides on the ramp 13 can be decelerated to an appropriate level.

[0056] Hereinafter, the process of braking achieved by the second indication value is referred to as a braking operation.

[0057] In addition, the direction from the outer peripheral side to the inner peripheral side (in other words, the direction away from the ramp 13) is referred to as the forward direction. The direction from the inner peripheral side to the outer peripheral side (in other words, the direction toward the ramp 13) is referred to as the backward direction.

[0058] Next, an example of the transition of the voltage value of the drive voltage applied to the VCM 16 will be described.

[0059] Figure 4 It shows an example of the transition of the voltage value of the drive voltage applied to the VCM 16 for implementing Figure 3 the first embodiment of the seek control shown. In this figure, the vertical axis represents the drive voltage applied to the VCM 16. The horizontal axis represents the elapsed time. In addition, hereinafter, as an example, it is assumed that: when a drive voltage with a positive voltage value is applied to the VCM 16, the head 22 is accelerated in the forward direction, and when a drive voltage with a negative voltage value is applied to the VCM 16, the head 22 is accelerated in the backward direction.

[0060] In seek control, the motor driver 21 controls the voltage applied to the VCM 16 based on the first indication value received from the processor 26 at a predetermined time period. When the head 22 is at the position Pa, the processor 26 causes the motor driver 21 to start applying a voltage with a negative voltage value (timing t0) in order to start accelerating the moving speed of the head 22 in the backward direction. The application of the voltage with the negative voltage value continues until the timing t1 when the speed of the head 22 in the backward direction reaches the desired speed. That is, during the period from timing t0 to timing t1, the moving speed of the head 22 in the backward direction is accelerated.

[0061] The processor 26 maintains the voltage value of the voltage applied to the VCM 16 at zero during the period from timing t1 to the timing t2 when the head 22 approaches the position Pb. As a result, during the period from timing t1 to timing t2, the head 22 moves uniformly in the backward direction.

[0062] The processor 26 causes the motor driver 21 to start applying a voltage with a positive voltage value at the timing t2 when the head 22 approaches the position Pb in such a way that the head 22 can stop at the position Pb. By applying the voltage with the positive voltage value to the VCM 16 while the head 22 is moving in the backward direction, the deceleration of the moving speed of the head 22 in the backward direction starts. The application of the voltage with the positive voltage value continues until the timing t3 when the head 22 stops at the position Pb. As a result, during the period from timing t2 to timing t3, the moving speed of the head 22 in the backward direction is decelerated.

[0063] If the head 22 stops at the position Pb (timing t3), the seek control for moving the head 22 from the position Pa to the position Pb is completed.

[0064] Figure 5 It is a diagram showing an example of the transition of the drive voltage applied to the VCM 16 in the first embodiment in the case where a power-off occurs during the seek control shown in Figure 3 In this figure, the vertical axis represents the drive voltage applied to the VCM 16. The horizontal axis represents the elapsed time. Here, as an example, the case where a power-off occurs during the period when the head 22 is moving uniformly is described.

[0065] The processor 26 performs the same processing at the timings t10 and t11 as the processing performed at the timings t0 and t1 shown in Figure 4 As a result, from the timing t11, the period when the head 22 moves uniformly starts.

[0066] If a power-off occurs at a certain timing t12 during the uniform movement of the head 22, the processor 26 ends the seek control and starts the control of the braking operation. The processor 26 starts the control of the braking operation before the motor driver 21 starts the retraction operation.

[0067] During the execution of the braking operation, the processor 26 calculates the braking voltage value and sends the second indication value representing the braking voltage value to the motor driver 21. The processor 26 repeats the sending of the second indication value at a predetermined time period. Thus, during the repetition of the sending of the second indication value, the braking operation continues.

[0068] If the voltage value of the power supply voltage is lower than the threshold Thd (timing t14), the processor 26 ends the sending of the second indication value and the motor driver 21 starts the retraction operation. That is, the motor driver 21 starts to apply multiple pulses. The motor driver 21 controls the wave height of each pulse in such a way that the speed when the head 22 approaches the ramp 13 during the movement of the head 22 becomes a suitable speed that can enable the head 22 to normally ride on the ramp 13.

[0069] If the head 22 rides on the ramp 13 (timing t15), the retraction operation ends.

[0070] Thus, according to the first embodiment, it is possible to apply braking to the movement of the head 22 in advance before the start of the retraction operation. Thereby, even when a power-off occurs while the head 22 is moving in the backward direction at a very high speed, it is possible to decelerate the speed when the head 22 rides on the ramp 13 to an appropriate level. As a result, damage to the magnetic disk 11 can be suppressed.

[0071] In addition, the configuration of the processor 26 and the motor driver 21 for monitoring the power supply voltage can be arbitrarily designed.

[0072] In one example, as Figure 1 shown, the processor 26 and the motor driver 21 are connected to the power supply circuit 20 through the control signal line. The power supply circuit 20 includes an analog-to-digital converter for obtaining the voltage value of the power supply voltage as a digital value. And the signal output from this analog-to-digital converter is sent to the processor 26 and the motor driver 21 via the control signal line, and the processor 26 and the motor driver 21 can know the voltage value of the power supply voltage through the received signal.

[0073] In another example, each of the processor 26 and the motor driver 21 includes an analog-to-digital converter for obtaining the voltage value of the power supplied to itself as a digital value. Each of the processor 26 and the motor driver 21 can know the voltage value of the power supply voltage based on the signal output from this analog-to-digital converter.

[0074] When the power supply circuit 20 is configured to distribute power without voltage conversion, each of the processor 26 and the motor driver 21 recognizes as the power supply voltage value the signal output from the analog-to-digital converter provided in itself.

[0075] When the power supply circuit 20 is configured to distribute power by performing voltage conversion, each of the processor 26 and the motor driver 21 can execute processing equivalent to comparison between the power supply voltage value and thresholds (threshold Thd and threshold Thp) by multiplying the signal output from the analog-to-digital converter provided in itself or the thresholds (threshold Thd and threshold Thp) by a coefficient.

[0076] Next, the operation of the disk device 1 according to the first embodiment will be described.

[0077] Figure 6 It is a flowchart showing an example of the operation of the processor 26 according to the first embodiment.

[0078] The processor 26 determines whether the power supply voltage value has fallen below the threshold Thp (S101). When the power supply voltage value has not fallen below the threshold Thp (S101: No), the control returns to S101. The processor 26 repeatedly executes the process of S101 regardless of whether it is positioning control until it is determined that the power supply voltage value has fallen below the threshold Thp.

[0079] When the power supply voltage value has fallen below the threshold Thp (S101: Yes), the processor 26 calculates a braking voltage value (S102).

[0080] As a method for calculating the braking voltage value, various methods can be adopted. Refer to Figure 7 and Figure 8 to describe an example of the method for calculating the braking voltage value.

[0081] In one example, the processor 26 obtains the moving speed of the head 22 in the retracting direction and calculates the braking voltage value based on the obtained moving speed of the head 22 in the retracting direction. For example, as Figure 7 shown, the faster the moving speed of the head 22 in the retracting direction, the larger the braking voltage value. In order to decelerate the moving speed of the head 22 when the head 22 rides on the ramp 13 to an appropriate level, the faster the moving speed of the head 22 in the retracting direction, the greater the deceleration amount required. According to Figure 7 the calculation method shown, this requirement can be satisfied.

[0082] In addition, according to Figure 7In the example shown, when the moving speed of the head 22 in the backward direction is negative, that is, when the head 22 is moving in the forward direction, the braking voltage value is set to zero. The calculation method of the braking voltage value when the head 22 is moving in the forward direction is not limited to this. The processor 26 can also obtain a negative braking voltage value in such a way that the moving speed of the head 22 can be decelerated even when the head 22 is moving in the forward direction.

[0083] In addition, the relationship between the moving speed of the head 22 in the backward direction and the braking voltage value is not limited to the Figure 7 linear relationship shown. For example, the relationship between the moving speed of the head 22 in the backward direction and the braking voltage value can also be defined in such a way that the braking voltage value changes stepwise according to the moving speed of the head 22 in the backward direction.

[0084] In another example, the processor 26 obtains the distance of the head 22 from the ramp 13 and calculates the braking voltage value based on the obtained distance of the head 22 from the ramp 13. For example, as Figure 8 shown, the closer the distance of the head 22 from the ramp 13, the larger the braking voltage value. The shorter the distance of the head 22 from the ramp 13, the shorter the distance the head 22 can move while decelerating, so stronger braking is required. According to this calculation method, the shorter the distance of the head 22 from the ramp 13, the stronger the braking that can be applied.

[0085] In addition, the relationship between the distance of the head 22 from the ramp 13 and the braking voltage value is not limited to the Figure 8 linear relationship shown. For example, the relationship between the distance of the head 22 from the ramp 13 and the braking voltage value can also be defined in such a way that the braking voltage value changes stepwise according to the distance of the head 22 from the ramp 13.

[0086] In yet another example, the processor 26 can also calculate the braking voltage value based on both the moving speed of the head 22 in the backward direction and the distance of the head 22 from the ramp 13. For example, the processor 26 can also calculate the braking voltage value based on both the Figure 7 relationship shown and the Figure 8 relationship shown.

[0087] The method by which the processor 26 obtains the moving speed of the head 22 in the backward direction and the distance of the head 22 from the ramp 13 is not limited to a specific method. For example, in positioning control and the like, the processor 26 calculates and estimates the current state quantity (such as position, moving speed, or both) of the head 22, and calculates the target position of the head 22 based on the estimated state quantity. The processor 26 can obtain the moving speed of the head 22 in the backward direction and the distance of the head 22 from the ramp 13 through the same algorithm as the algorithm for calculating the current state quantity of the head 22 in positioning control.

[0088] Return the description Figure 6 。

[0089] When the calculation of the braking voltage value is completed, the processor 26 controls the braking operation of the motor driver 21 (S103). That is, the processor 26 causes the motor driver 21 to perform a braking operation by sending the braking voltage value as the second indication value to the motor driver 21.

[0090] The control of the braking operation can continue until any timing before the start timing of the retraction operation. The period during which the control of the braking operation continues, that is, the execution period of the braking operation, can be set in any way from the period until the start timing of the retraction operation. For example, the execution period of the braking operation can also be fixed to a predetermined short period. Alternatively, it can be that the processor 26 determines the execution period of the braking operation based on the moving speed, position, or both of the head 22, etc. The processor 26 can also continue the control of the braking operation until the start timing of the retraction operation.

[0091] Next, the processor 26 determines whether the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold value Thd (S104).

[0092] If the voltage value of the power supply voltage is lower than the threshold value Thd, the motor driver 21 starts the retraction operation. That is, S104 corresponds to the process for the processor 26 to identify the timing at which the motor driver 21 starts the retraction operation.

[0093] If the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold value Thd, it notifies the processor 26 of the fact that the voltage value of the power supply voltage is lower than the threshold value Thd. In S104, the processor 26 determines whether the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold value Thd based on this notification.

[0094] The transmission method of this notification from the motor driver 21 to the processor 26 is not limited to a specific method. In one example, the motor driver 21 has a register, and when the voltage value of the power supply voltage is lower than the threshold value Thd, it sets a value indicating that the voltage value of the power supply voltage is lower than the threshold value Thd to this register. The processor 26 refers to the value of this register at a predetermined time period. And if the processor 26 obtains a value indicating that the voltage value of the power supply voltage is lower than the threshold value Thd through the reference of this register, it can know that the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold value Thd.

[0095] When the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold value Thd (S104: Yes), the processor 26 ends the operation.

[0096] In the case where the motor driver 21 does not detect that the power supply voltage has dropped below the threshold Thd even when the processor 26 waits for a predetermined time (S104: No), the control moves to S101.

[0097] For example, there is the following situation: after the voltage value of the power supply voltage has dropped below the threshold Thp, the voltage value of the power supply voltage does not drop below the threshold Thd and recovers to the rated voltage value. In such a case, it can be presumed that a power-off has not occurred. Therefore, when the processor 26 determines No in the process of S104, the operation related to the power-off ends, and the control moves to S101. If the control moves to S101, the processor 26 can start the positioning control again.

[0098] Figure 9 It is a flowchart showing an example of the operation of the motor driver 21 according to the first embodiment.

[0099] The motor driver 21 determines whether the voltage value of the power supply voltage has dropped below the threshold Thd (S201). When the voltage value of the power supply voltage has not dropped below the threshold Thd (S201: No), the control returns to S201. The motor driver 21 repeatedly executes the process of S201 until it is determined that the voltage value of the power supply voltage has dropped below the threshold Thd.

[0100] In addition, until the motor driver 21 determines No in the process of S201, the motor driver 21 controls the drive voltage of the motor driver 21 based on the indication value (the first indication value or the second indication value) from the processor 26. In particular, when the voltage value of the power supply voltage has dropped below the threshold Thp, the motor driver 21 performs a braking operation based on the second indication value from the processor 26.

[0101] When the voltage value of the power supply voltage has dropped below the threshold Thd (S201: Yes), the motor driver 21 notifies the processor 26 that the voltage value of the power supply voltage has dropped below the threshold Thd (S202), and performs a retraction operation (S203). If the head 22 rides on the ramp 13 by the retraction operation, the motor driver 21 ends the operation.

[0102] Thus, according to the first embodiment, when the voltage value of the power supply voltage has dropped below the threshold Thd, the motor driver 21 starts the retraction operation by controlling the drive voltage applied to the VCM16. When the voltage value of the power supply voltage has dropped below the threshold Thp that is larger than the threshold Thd, the processor 26 makes the motor driver 21 perform a braking operation by sending the second indication value.

[0103] Accordingly, before the voltage value of the power supply voltage falls below the threshold Thd, the motor driver 21 decelerates the speed of the head 22 according to the second indication value from the processor 26.

[0104] Accordingly, in the case where power-off occurs, a strong brake can be applied to the movement of the head 22. The moving speed of the head 22 when the head 22 rides on the ramp 13 can be appropriately suppressed in a manner that prevents the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0105] In addition, according to the first embodiment, in one example, the processor 26 obtains the moving speed of the head 22 toward the ramp 13, and calculates the braking voltage value based at least on this moving speed. Then, the processor 26 sends the braking voltage value to the motor driver as the second indication value. Before the retraction operation, the motor driver 21 applies a drive voltage having a voltage value corresponding to the second indication value to the VCM 16.

[0106] Accordingly, the faster the moving speed of the head 22 in the retracting direction, the stronger the brake that can be applied to the movement of the head 22. Therefore, the moving speed of the head 22 when the head 22 rides on the ramp 13 can be appropriately suppressed in a manner that prevents the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0107] In addition, according to the first embodiment, in one example, the processor 26 obtains the distance of the head 22 from the ramp 13, and calculates the braking voltage value based at least on this distance. Then, the processor 26 sends the braking voltage value to the motor driver as the second indication value. Before the retraction operation, the motor driver 21 applies a drive voltage having a voltage value corresponding to the second indication value to the VCM 16.

[0108] Accordingly, the shorter the distance of the head 22 from the ramp 13, the stronger the brake that can be applied. Therefore, the moving speed of the head 22 when the head 22 rides on the ramp 13 can be appropriately suppressed in a manner that prevents the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0109] In addition, in the first embodiment, the threshold Vtp is an example of the second threshold. The threshold Vtd is an example of the first threshold. The VCM 16 is an example of a motor. The second indication value is an example of an indication value.

[0110] (Second Embodiment)

[0111] As described above, in the retraction operation, the motor driver 21 calculates the state quantity (position or speed) of the VCM 16 during the pulse-off period, and uses this state quantity as a feedback input to determine the wave height of the pulse applied during the subsequent pulse-on period. Accordingly, at the time of applying the first pulse, the motor driver 21 is in a state where the state quantity of the VCM 16 has not been obtained.

[0112] In the comparative example, the peak height of the first pulse uses a fixed initial value, for example. The control of the peak height corresponding to the position or moving speed of the head can be performed in the pulses after the second time. That is, the timing at which a strong braking can be applied is delayed. Therefore, in a situation where a rapid braking is required, sometimes the moving speed of the head when the head rides on the ramp cannot be decelerated to an appropriate level.

[0113] In the second embodiment, in order to be able to apply a strong braking at a timing earlier than that in the comparative example, when the motor driver 21 starts applying a plurality of pulses to the VCM 16 during the retraction operation, the motor driver 21 controls the peak height of the first pulse according to the braking intensity value indicated in advance from the processor 26 before the start of the retraction operation. That is, when a power-off occurs, the processor 26 calculates the intensity of the braking required before the start of the retraction operation. The processor 26 transmits the intensity of the braking obtained by the calculation to the motor driver 21 as the braking intensity value.

[0114] Figure 10 It shows in Figure 3 FIG. is an example of the transition of the voltage applied to the VCM 16 in the second embodiment in the case where a power-off occurs during the seek control shown. In this figure, the vertical axis represents the drive voltage applied to the VCM 16. The horizontal axis represents the elapsed time.

[0115] The processor 26 performs the same processing at the timings t20 and t21 as the processing performed at the timings t0 and t1 shown in Figure 4 Accordingly, starting from the timing t21, the period during which the head 22 moves at a constant speed begins.

[0116] If a power-off occurs at a certain timing t22 during the period in which the head 22 moves at a constant speed, the processor 26 ends the seek control, calculates the braking intensity value, and transmits the braking intensity value obtained by the calculation to the motor driver 21.

[0117] If the voltage value of the power supply voltage is lower than the threshold Thd (timing t23), the motor driver 21 starts the retraction operation. That is, the motor driver 21 starts applying a plurality of pulses. The motor driver 21 applies a pulse having a peak height H1 corresponding to the braking intensity value to the VCM 16 as the first pulse. For the pulses after the second time, the motor driver 21 controls the peak height based on the state quantity of the VCM 16 obtained during the period when the immediately previous pulse is turned off.

[0118] If the head 22 rides on the ramp 13 (timing t24), the retraction operation ends.

[0119] In this way, the first pulse applied to the VCM 16 during the retraction operation can be controlled.

[0120] Next, the operation of the disk device 1 according to the second embodiment will be described.

[0121] Figure 11 It is a flowchart showing an example of the operation of the processor 26 according to the second embodiment.

[0122] The processor 26 determines whether the voltage value of the power supply voltage is lower than the threshold Thp in the same manner as in S101 (S301). When the voltage value of the power supply voltage is not lower than the threshold Thp (S301: No), the control returns to S301. The processor 26 repeatedly executes the process of S301 regardless of whether it is positioning control until it is determined that the voltage value of the power supply voltage is lower than the threshold Thp.

[0123] When the voltage value of the power supply voltage is lower than the threshold Thp (S301: Yes), the processor 26 calculates the braking intensity value (S302).

[0124] As a method for calculating the braking intensity value, various methods can be adopted. The processor 26 can calculate the braking intensity value in the same manner as the method for calculating the braking voltage value according to the first embodiment. That is, in the method for calculating the braking voltage value described in Figure 7 and Figure 8 the method obtained by changing the braking voltage value to the braking intensity value in the method for calculating the braking voltage value according to the first embodiment can be used as the method for calculating the braking intensity value.

[0125] In addition, the braking intensity value can be represented by a value selected from multiple levels such as full braking, medium braking, and weak braking, or can be represented as numerical information using multiple bits.

[0126] Next, the processor 26 sends the calculated braking intensity value to the motor driver 21 (S303).

[0127] Then, in the same manner as S104, the processor 26 determines whether the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold Thd (S304).

[0128] When the motor driver 21 detects that the voltage value of the power supply voltage is lower than the threshold Thd (S304: Yes), the processor 26 ends the operation.

[0129] When the motor driver 21 does not detect that the power supply voltage is lower than the threshold Thd even if the processor 26 waits for a predetermined time (S304: No), it can be presumed that a power-off has not occurred, so the control moves to S301.

[0130] If the control moves to S301, the processor 26 can start the positioning control again.

[0131] Figure 12It is a flowchart showing an example of the operation of the motor driver 21 according to the second embodiment.

[0132] When the voltage value of the power supply voltage falls below the threshold Thp, through the process of S303 of the processor 26, the motor driver 21 receives the braking intensity value from the processor 26 (S401). Then, the motor driver 21 determines whether the voltage value of the power supply voltage has fallen below the threshold Thd (S402). When the voltage value of the power supply voltage has not fallen below the threshold Thd (S402: No), the control returns to S402. The motor driver 21 repeatedly executes the process of S402 until it is determined that the voltage value of the power supply voltage has fallen below the threshold Thd.

[0133] In addition, until the motor driver 21 determines No in the process of S402, the motor driver 21 can control the drive voltage of the motor driver 21 based on the indicated value (the first indicated value) from the processor 26.

[0134] When the voltage value of the power supply voltage has fallen below the threshold Thd (S402: Yes), the motor driver 21 notifies the processor 26 that the voltage value of the power supply voltage has fallen below the threshold Thd (S403), and executes the retraction action (S404).

[0135] When applying the first pulse of the retraction action, the motor driver 21 applies a pulse with a wave height H1 corresponding to the braking intensity value to the VCM16. For example, the greater the braking intensity value, the higher the motor driver 21 makes the wave height H1.

[0136] If the retraction action is completed, the motor driver 21 ends the operation.

[0137] In this way, according to the second embodiment, when the voltage value of the power supply voltage falls below the threshold Thp, the processor 26 calculates the braking intensity value and sends the braking intensity value to the motor driver 21. The motor driver 21 applies a pulse with a wave height corresponding to the braking intensity value to the VCM16 in the first application of the pulses applied multiple times.

[0138] Thereby, it is possible to apply a strong brake to the movement of the head 22 at an early timing. It is possible to appropriately suppress the moving speed of the head 22 when the head 22 rides on the ramp 13 so as to prevent the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0139] In addition, according to the second embodiment, in one example, the processor 26 obtains the moving speed in the retracting direction of the head 22 and calculates the braking intensity value based at least on the moving speed.

[0140] Accordingly, the faster the moving speed of the head 22 in the retracting direction, the stronger the braking force that can be applied to the movement of the head 22. Thus, the moving speed of the head 22 when it rides on the ramp 13 can be appropriately suppressed in a manner that prevents the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0141] In addition, according to the second embodiment, in one example, the processor 26 obtains the distance of the head 22 from the ramp 13 and calculates the braking intensity value based at least on this distance.

[0142] Accordingly, the shorter the distance of the head 22 from the ramp 13, the stronger the braking force that can be applied. Thus, the moving speed of the head 22 when it rides on the ramp 13 can be appropriately suppressed in a manner that prevents the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0143] Furthermore, in the second embodiment, the threshold Vtp is an example of the second threshold. The threshold Vtd is an example of the first threshold. The VCM 16 is an example of a motor. The braking intensity value is an example of an indication value.

[0144] As described above, according to the first embodiment and the second embodiment, when the power supply voltage drops below a threshold Thp that is greater than the threshold Thd used in the determination at the timing of starting the retraction operation, the processor 26 sends an indication related to applying braking to the movement of the head 22 to the motor driver 21. In the first embodiment, the indication related to applying braking to the movement of the head 22 is a braking indication value for implementing the braking operation. In the second embodiment, it is the braking intensity value for controlling the amplitude of the pulse initially applied to the VCM 16 during the retraction operation. The motor driver 21 receives the indication related to applying braking to the movement of the head 22 before the start of the retraction operation and performs processing corresponding to this indication.

[0145] Accordingly, according to the first embodiment and the second embodiment, in the event of a power-off, a strong braking force can be applied to the movement of the head 22. The moving speed of the head 22 when it rides on the ramp 13 can be appropriately suppressed in a manner that prevents the head 22 from recoiling on the ramp 13 and returning to the disk 11.

[0146] For example, according to the first embodiment, in the case where a power-off occurs while the head 22 is moving in the retracting direction, the motor driver 21 applies braking to the movement of the head 22, and then applies a plurality of pulses to the VCM 16 through the retraction operation. That is, braking can be applied to the movement of the head 22 before the retraction operation.

[0147] For example, according to the second embodiment, when power is turned off during the backward movement of the head 22, the motor driver 21 can change the amplitude of the pulse initially applied to the VCM 16 during the retraction operation according to the moving speed of the head 22 when the power is turned off.

[0148] Although some embodiments of the present invention have been described, these embodiments are presented by way of example and are not intended to limit the scope of the invention. These novel embodiments can be implemented in various other ways, and various omissions, substitutions, and changes can be made without departing from the gist of the invention. These embodiments and their modifications are included in the scope and gist of the invention, and are included in the invention described in the claims and the scope of equivalents thereof.

Claims

1. A disk device, comprising: A disk; A head for accessing the disk; A motor for moving the head; A ramp; A motor driver that starts a retraction operation of retracting the head to the ramp by controlling the voltage applied to the motor when the voltage value of the power supply voltage is lower than a first threshold; And A processor that sends an instruction related to braking the movement of the head to the motor driver when the voltage value of the power supply voltage is lower than a second threshold greater than the first threshold, The motor driver decelerates the speed of the head according to the instruction before the voltage value of the power supply voltage is lower than the first threshold.

2. The disk device according to claim 1, The processor, when the voltage value of the power supply voltage is lower than the second threshold, obtains the moving speed of the head towards the ramp, calculates an instruction value based on at least the moving speed, The instruction includes the instruction value, The motor driver applies a voltage of a voltage value corresponding to the instruction value to the motor before the voltage value of the power supply voltage is lower than the first threshold.

3. The disk device according to claim 1, The processor, when the voltage value of the power supply voltage is lower than the second threshold, obtains the distance of the head from the ramp, calculates an instruction value based on at least the distance, The instruction includes the instruction value, The motor driver applies a voltage of a voltage value corresponding to the instruction value to the motor before the voltage value of the power supply voltage is lower than the first threshold.

4. The disk device according to claim 1, During the retraction operation, the motor driver applies a voltage of a pulsed waveform to the motor multiple times, and controls the wave height of the pulse applied in the first time among the multiple applications according to the instruction.

5. The disk device according to claim 1 or 4, The processor, when the voltage value of the power supply voltage is lower than the second threshold, obtains the moving speed of the head towards the ramp, calculates an instruction value based on at least the moving speed, The instruction includes the instruction value, During the retraction operation, the motor driver applies a voltage of a pulsed waveform to the motor multiple times, and in the first time among the multiple applications, applies a voltage of a pulsed waveform with a wave height corresponding to the instruction value to the motor.

6. The disk device according to claim 1 or 4, The processor, when the voltage value of the power supply voltage is lower than the second threshold, obtains the distance of the head from the ramp, calculates an instruction value based on at least the distance, The instruction includes the instruction value, During the retraction operation, the motor driver applies a voltage of a pulsed waveform to the motor multiple times, and in the first time among the multiple applications, applies a voltage of a pulsed waveform with a wave height corresponding to the instruction value to the motor.

7. The disk device according to claim 2, The processor calculates the instruction value in such a manner that the faster the moving speed, the greater the intensity of braking the movement of the head.

8. The disk device according to claim 3, wherein the processor calculates the indication value such that the shorter the distance, the greater the intensity of the braking applied to the movement of the head.

9. A disk device, comprising: a disk; a head for accessing the disk; a motor for moving the head; a ramp; and a motor driver that applies braking to the movement of the head when power-off occurs during the movement of the head toward the ramp, and after applying braking to the movement of the head, applies a voltage having a pulse-shaped waveform to the motor a plurality of times to retract the head to the ramp.

10. A disk device, comprising: a disk; a head for accessing the disk; a motor for moving the head; a ramp; and a motor driver that, when power-off occurs during the movement of the head toward the ramp, applies a voltage having a pulse-shaped waveform to the motor a plurality of times after applying braking to the movement of the head to retract the head to the ramp, wherein the motor driver changes the amplitude of the voltage having a pulse-shaped waveform applied to the motor for the first time among the voltages having a pulse-shaped waveform applied to the motor a plurality of times according to the moving speed of the head when the power-off occurs.

Images