JP2010080028A - Disk device and control method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve resistance to shocks by surely detecting contact between a head and a disk medium to reduce the frequency of contact as regards a disk device and a control method. <P>SOLUTION: Rotational variation of a spindle motor is detected by measuring the cycle of a pulse signal generated in synchronization with the rotation of the spindle motor. Upon detection of rotational variation exceeding a threshold value, the head is retreated from the disk medium. Upon convergence of the rotational variation exceeding the threshold value, the head is moved onto the disk medium. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a disk device and a disk device control method.

  In a magnetic disk device, information is recorded on and read from a magnetic disk medium (sometimes referred to as “access” together with recording and reading) by a magnetic head that is very close to the magnetic disk medium. When the magnetic head comes into contact with the magnetic disk medium, the magnetic head is destroyed, or dust is generated due to the contact, causing an error in reading information.

  For this reason, proposals have been made to detect the contact of the magnetic head with the magnetic disk medium and reduce the frequency of the contact.

  For example, it has been proposed to detect contact between a magnetic head and a magnetic disk medium by detecting an abnormal change in the drive current of a spindle motor (Patent Document 1).

  However, in the case of current detection, noise is large and accurate detection is difficult.

  Further, it has been proposed to detect the impact by stopping the recording operation by detecting the rotation speed by reproducing the signal recorded on the magnetic disk medium with a magnetic head (Patent Document 2).

  In this case, if the impact is at a level that allows signal reproduction, the rotational speed can be detected, but if the signal reproduction is impossible, the impact of the portion of the magnetic disk medium is defective or the signal reproduction is not possible. It is not possible to determine whether or not it is impossible.

  Further, it has been proposed that when an impact force received from the outside is detected by an impact sensor and an impact exceeding a predetermined level is detected, the rotation of the motor is stopped after the magnetic head is retracted (Patent Document 3). ).

  However, since the contact of the magnetic head with the magnetic disk medium is also caused by wind disturbance caused by the rotation of the magnetic disk medium, it does not necessarily match the strength of the impact received from the outside.

In addition, during the power saving time in the test process, the motor is stopped to increase impact resistance (Patent Document 4), or the magnetic head is moved to the CSS (contact start / stop) zone when the motor is stopped to provide impact resistance. It is proposed to raise.
JP-A-3-91161 JP 2001-176181 A JP 2002-203360 A JP-A-10-302376 JP-A-10-188497

  An object of the disk device and the control method disclosed herein is to improve the resistance to impact by reliably detecting the contact between the head and the disk medium and reducing the frequency of the contact.

The disk device disclosed herein is
A head for recording and reading information on a rotating disk medium;
A spindle motor for rotating the disk medium;
An actuator for moving the head onto the rotating disk medium and retracting from the disk medium;
A motor control unit for controlling the rotation of the spindle motor and generating a pulse signal synchronized with the rotation of the spindle motor;
A rotation fluctuation detector for detecting a rotation fluctuation of the spindle motor by measuring the period of the pulse signal;
And a head control unit that controls the actuator so that the head is retracted from the disk medium in response to the rotation variation exceeding the threshold being detected by the rotation variation detection unit.

In addition, the control method of this disclosure is
A head for recording and reading information on a rotating disk medium;
A spindle motor for rotating the disk medium;
An actuator for moving the head onto the rotating disk medium and retracting from the disk medium;
A control method of a disk device comprising a motor control unit that controls rotation of a spindle motor and generates a pulse signal synchronized with the rotation of the spindle motor,
A rotation fluctuation detecting step for detecting a rotation fluctuation of the spindle motor by measuring the period of the pulse signal;
A head retracting step for retracting the head from the disk medium in response to the detection of the rotational variation exceeding the threshold in the rotational variation detecting step.

  In the disk device and the control method disclosed herein, the rotation fluctuation of the spindle motor is detected by measuring the cycle of the pulse signal synchronized with the rotation of the spindle motor, and the rotation fluctuation can be detected with high accuracy.

  Further, in the disk device and the control method disclosed in the present disclosure, the head is retracted from the disk medium in response to the detection of the rotational fluctuation exceeding the threshold value, so that the chance of contact between the head and the disk can be reduced.

  According to the disk device and the control method of the present disclosure, it is possible to improve the resistance to impact by reliably detecting the contact between the head and the disk medium and reducing the frequency of the contact.

  Hereinafter, an embodiment of the present case will be described.

  FIG. 1 is a schematic diagram of a magnetic disk device.

  In the housing 101 of the magnetic disk device 10 shown in FIG. 1, a magnetic disk medium 110 mounted on the rotating shaft of the spindle motor 102 and rotating, and information recording and reproduction (access) to the magnetic disk medium 110 are performed. A suspension 104 holding the magnetic head 103 at the tip, a carriage arm 106 to which the suspension 104 is fixed and moving along the surface of the magnetic disk medium 110 around the arm shaft 105, and a voice coil motor for driving the carriage arm 106 are provided. The arm actuator 107 provided is housed.

  The magnetic disk medium 110 receives information from a magnetic field carrying information and records information magnetically. When recording information on the magnetic disk medium 110 and reproducing information recorded on the magnetic disk medium 110, the carriage arm 106 is driven by the arm actuator 107, and the magnetic head 301 is rotated by the spindle motor 102. The desired track on the magnetic disk medium 110 is positioned. The magnetic head 301 sequentially records information by tracing a desired track of the magnetic disk medium 110 as the magnetic disk medium 110 rotates.

  When accessing the magnetic disk medium 110, the arm actuator 107 rotates (loads) the magnetic head 301 on the magnetic disk medium 110. When access to the magnetic disk medium 110 is unnecessary, the arm actuator 107 moves the magnetic head 301 to the position of the ramp 108. Rotate to rest (unload).

  Although not shown here, on the back side of the surface shown in FIG. 1 and on the inner bottom of the housing 101 are circuits for controlling the magnetic disk device 10 and communicating with the host. An on-board circuit board is provided. As an element characteristic of this embodiment, an impact sensor for detecting an impact when an external impact is applied to the magnetic disk device 10 is mounted on the circuit board.

  FIG. 2 is a block diagram showing a signal processing system of the magnetic disk device shown in FIG.

  The hard disk controller (HDC) 121 communicates with the host 20 such as a computer to receive write data for writing to the magnetic disk medium 110 from the host 20 and read data obtained by reading from the magnetic disk medium 110. Are transmitted to the host 20 and various commands are received from the host 20.

  When the HDC 121 receives write data from the host 20, it passes the write data to a read controller (RDC) 122, and the RDC 122 converts the write data into a write signal for the magnetic head 301 and sends it to the magnetic head 301. The magnetic head 301 generates a magnetic force corresponding to the write signal, and writes information corresponding to the write signal to the magnetic disk medium 110.

  Further, when reading the information recorded on the magnetic disk medium 110, the information is picked up by the magnetic head 301 and a read signal is generated, and the read signal is transmitted to the RDC 122. The RDC 122 is the signal format of the read signal. To generate read data and pass it to the HDC 121. The HDC 121 transmits the read data to the host 20.

  The operation start command transmitted from the host 20 is transmitted to the micro control unit (MCU) 123 via the HDC 121, and the MCU 123 transmits the command to the servo controller (SVC) 124. In response to the instruction, the SVC 124 sends an SPM control current to the spindle motor 102 to rotate the magnetic disk medium 110. The SVC 124 receives a pulse from a Hall sensor (not shown) that outputs a pulse every time the rotation shaft of the spindle motor 102 rotates by a predetermined angle, and performs servo control so that the magnetic disk medium 110 rotates at a constant speed. . The MCU 123 monitors the SVC 124 and detects the rotational speed fluctuation of the magnetic disk medium 110. Details will be described later.

  In addition, the SVC 124 sends a VCM control current to the voice coil motor constituting the arm actuator 107 in response to a command from the MCU 123 to rotate the carriage arm 106 in order to position the magnetic head 301 on a desired track of the magnetic disk medium 110. The magnetic head 101 is moved to a desired track.

  In FIG. 2, a RAM 125 is shown. The RAM 125 is a memory in which various information (device information) pre-recorded on the magnetic disk medium 110 regarding the specifications of the magnetic disk device is read and stored at an early stage after the operation of the magnetic disk device 10 is started. It is.

  Further, in FIG. 2, an impact sensor 126 is shown. The impact sensor 126 is a sensor that detects an impact when the magnetic disk device 10 receives an impact from the outside.

  FIG. 3 is a diagram showing signal waveforms generated by the servo controller (SVC). FIG. 3A shows a three-phase SVC control current for rotating the spindle motor, and FIG. 3B shows a phase signal composed of a counter electromotive voltage when the spindle motor is switched.

  This phase signal is a signal synchronized with the rotation of the spindle motor, that is, the rotation of the magnetic disk medium 110. In this embodiment, the phase signal is measured by measuring the period of the phase signal. A fluctuation in the rotational speed of the disk medium 110 is detected.

  FIG. 4 is a diagram showing a program execution timing (A) and an outline (B) of processing contents in the micro control unit (MCU).

  On the magnetic disk medium 110, hundreds of servo information is recorded per rotation. SG (Servo Gate) in FIG. 4A indicates the timing of reading servo information from the rotating magnetic disk medium 110 by the magnetic head 301, and the program processing is performed using the SG as an interrupt timing.

  FIG. 4B is an enlarged view of the time axis for one program process.

  Within one program processing, demodulation of servo information read from the magnetic disk medium, VCM control for driving the voice coil motor based on the servo information and causing the magnetic head 101 to follow a desired track, CAL control for performing various corrections (bias correction / loop gain correction, etc.), and spindle motor rotation information check and rotation control (SPM control) are performed. In this way, the micro control unit (MCU) controls the operation of the magnetic disk device by interrupt processing based on servo information, and checks the rotation accuracy of the spindle motor in the control to control the rotation of the spindle motor. ing.

  In the “SPM control” in the program processing, the rise of the phase signal shown in FIG. 3 is measured and the time from the rise to the next rise is measured, whereby the rotational fluctuations of the spindle motor and the magnetic disk medium are changed. Detected. This phase signal is an example of a pulse signal in this case.

  FIG. 5 is a diagram showing part of the parameter information recorded on the magnetic disk medium.

  The information shown in FIG. 5 is information recorded when the magnetic disk medium is manufactured (before being incorporated into the magnetic disk device).

  Here, “function information”, “rotational fluctuation threshold”, and “monitoring time” representing a mode to be executed when a rotational fluctuation equal to or greater than the threshold occurs are shown.

  “Functional information” indicates an operation mode that is performed when a rotation fluctuation indicating that the magnetic head has come into contact with the magnetic disk medium occurs in the magnetic disk device incorporating the magnetic disk medium.

  Mode 1 is a flag for instructing execution until unloading when there is a change in rotation, and mode 2 is executed until unloading is performed and further spindle mode is stopped when there is a change in rotation. It is a flag instructing that.

  Further, the “threshold of rotation fluctuation” indicates a threshold of how much rotation fluctuation occurs when the operation of the mode 1 or mode 2 is performed. “1P” is a threshold value applied to a magnetic disk device incorporating only one magnetic disk medium, “2P” is a threshold value applied to a magnetic disk device incorporating two magnetic disk media, and “3P” is magnetic This threshold is applied to a magnetic disk device in which three disk media are incorporated.

  In a magnetic disk device incorporating a plurality of magnetic disk media, the plurality of magnetic disk media are coaxially rotated at the same time. Therefore, the magnitude of the rotational moment differs depending on the number of magnetic disk media, and the magnetic head becomes a magnetic disk medium. Since the level of rotational fluctuation differs depending on the number of magnetic disk media even if contact is made at the same level, a threshold value is determined here for each number.

  The number information of the magnetic disk medium incorporated in the magnetic disk device is recorded on the magnetic disk medium incorporated in the magnetic disk device for each magnetic disk device separately from the information shown in FIG. In the initial stage of the operation, the data is read from the magnetic disk medium and stored in the RAM shown in FIG. 2 as one piece of device information.

  The “monitoring time” indicates a standby time when monitoring is repeatedly performed, and is recorded separately when the spindle motor is stopped and unloaded.

  Hereinafter, an operation flow characteristic of the present embodiment will be described.

  The operation flow described below is an operation flow based on a program created in common for a plurality of types of magnetic disk devices, and only a part of the operation flow described below is performed in a specific magnetic disk device. Executed.

  FIG. 6 is a diagram showing an operation flow executed by the micro control unit (MCU) when power is supplied to the magnetic disk device.

  Here, the parameter information of FIG. 5 is read from the magnetic disk medium (step S01), and it is determined whether it is mode 1 (step S02) or mode 2 (step S04). When the mode is 1, the flow proceeds to the mode 1 shown in FIG. 7 (step S03), and when the mode is 2, the flow proceeds to the mode 2 shown in FIG. 8 (step S04). When neither the mode 1 nor the mode 2 is selected, it is determined that the magnetic head is not in contact with the magnetic disk medium (step S06), and the flow of FIG. 6 is terminated.

  Whether to execute mode 1 or mode 2 is information recorded on the magnetic disk medium before being incorporated into the magnetic disk device (see FIG. 3), and it is determined which mode is executed depending on the magnetic disk medium. The

  FIG. 7 is a diagram showing an operation flow in mode 1.

  Here, it is monitored whether or not the rotational fluctuation of the magnetic disk medium (spindle motor) exceeds a threshold value. As the threshold value, one of “1P”, “2P”, and “3P” is adopted according to the configuration of the magnetic disk device as shown in FIG.

  When the rotational fluctuation exceeds the threshold value, the magnetic head 301 is unloaded (step S12) and supported by the ramp 108 (see FIG. 1).

  Next, the standby time recorded during the monitoring time (UnLoad) shown in FIG. 5 is set (step S13), and it is determined whether or not the rotational fluctuation exceeds the threshold (step S14). When the rotational fluctuation exceeding 1 converges, the magnetic head 301 is loaded again from the ramp 108 onto the magnetic disk medium 110 (step S15).

  In this mode 1, the impact sensor 126 shown in FIG. 2 is not necessary. In this mode 1, the magnetic disk device not provided with the impact sensor 126, or even if provided with the impact sensor, the operation of this impact sensor is the mode 1. It is executed in a magnetic disk device used for unrelated operations.

  FIG. 8 is a diagram showing an operation flow in mode 2.

  The operation flow in mode 2 shown in FIG. 8 is an operation flow applied to the magnetic disk device shown in FIGS. That is, the present embodiment is a magnetic disk device in which a magnetic disk medium in which it is recorded that mode 2 is to be executed is incorporated, and this diagram in a program that is commonly incorporated in a plurality of types of magnetic disk devices. The operation flow shown in FIG. 8 is executed.

  Here, it is monitored whether or not the circuit fluctuation of the magnetic disk medium exceeds a threshold value (step S21). When the threshold value is exceeded, the magnetic head 101 is unloaded to the position of the ramp 108 (step S22), and the spindle motor is stopped. (Step S23).

  Next, after waiting for the waiting time recorded in the “monitoring time (when SPM is stopped)” shown in FIG. 5 (step S24), the impact sensor 126 is monitored. When the impact sensor 126 is reacting, that is, when an impact is applied to the magnetic disk device and the impact has not yet converged, the impact sensor is monitored again after waiting for a waiting time.

  When there is no response to the impact sensor, that is, when the impact has converged or when the impact originally does not exist, the spindle motor is started (step S26), and this time is recorded in the “monitoring time (UnLoad)” shown in FIG. Waiting for the waiting time (step S27), it is determined whether or not there is a rotational fluctuation exceeding the threshold (step S28). When there is a rotational fluctuation exceeding the threshold, the system waits again for the standby time (step S27), and the presence / absence of the rotational fluctuation exceeding the threshold is determined again (step S28).

  When there is no rotational fluctuation exceeding the threshold value (step S28), the magnetic head 301 is loaded onto the magnetic disk medium 110 from the ramp.

  FIG. 9 is a diagram showing an operation flow as a modified example of mode 2 that can be employed instead of the operation flow of mode 2 shown in FIG. In the operation flow shown in FIG. 9, the impact sensor is not used. Therefore, the present invention can be executed even with a magnetic disk device having no impact sensor.

  Steps S31 to S33 and S35 to S38 in FIG. 9 are substantially the same as steps S21 to S23 and S26 to S29 in FIG. 8, and only the differences will be described.

  In steps S24 and S25 of FIG. 8, the impact sensor is monitored and the spindle motor is restarted when there is no response to the impact sensor (the impact does not exist or the impact has converged) (step S26). In step S34 of 9, the spindle motor is restarted after a certain time has passed (step S26) after the spindle motor is stopped (step S33). Further, after the spindle motor is restarted, if there is a rotation fluctuation exceeding the threshold value (step S37), the spindle motor is stopped again (step S33).

  If the operation flow of FIG. 9 is adopted instead of the operation flow of FIG. 8, an impact sensor becomes unnecessary.

  The present invention can be applied to any disk device that records or reproduces information by flying a head over a disk medium rotated by a spindle motor. Therefore, the present invention is a technology applicable to a removable disk device from which a disk medium can be removed, and is not limited to the magnetic disk device shown in the embodiment, but an optical disk device or a magneto-optical disk device. It is a technology that can also be applied to.

1 is a schematic diagram of a magnetic disk device. It is a block diagram showing a signal processing system of a magnetic disk device. It is a figure which shows the signal waveform produced | generated by a servo controller (SVC). It is a figure which shows the execution timing (A) of the program in a micro control unit (MCU), and the outline | summary (B) of the processing content. It is the figure which showed a part of parameter information currently recorded on the magnetic disc medium. It is a figure which shows the operation | movement flow performed with a micro control unit (MCU) when power is supplied to this magnetic disc unit. It is a figure which shows the operation | movement flow in the mode 1. It is a figure which shows the operation | movement flow in the mode 2. It is a figure which shows the operation | movement flow as a modification of the mode 2 which can be employ | adopted instead of the operation | movement flow of the mode 2 shown in FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Magnetic disk apparatus 20 Host 101 Housing 103 Magnetic head 102 Spindle motor 104 Suspension 105 Arm shaft 106 Carriage arm 107 Arm actuator 108 Lamp 110 Magnetic disk medium 121 Hard disk controller (HDC)
122 Read controller (RDC)
123 Micro Control Unit (MCU)
124 Servo controller (SVC)
125 RAM
126 Impact sensor

Claims (7)

A head for recording and reading information on a rotating disk medium;

A spindle motor that rotationally drives the disk medium;
An actuator for moving the head onto the rotating disk medium and retracting from the disk medium;
A motor control unit for controlling the rotation of the spindle motor and generating a pulse signal synchronized with the rotation of the spindle motor;
A rotation fluctuation detecting unit that detects a rotation fluctuation of the spindle motor by measuring a cycle of the pulse signal;
And a head control unit that controls the actuator so that the head is retracted from the disk medium in response to a rotation fluctuation exceeding a threshold being detected by the rotation fluctuation detection unit. apparatus. The rotation fluctuation detecting unit detects a rotation fluctuation of the spindle motor after the head control unit retreats the head from the disk medium in response to the rotation fluctuation detecting unit detecting a rotation fluctuation exceeding a threshold value. Repeated detection,
2. The disk apparatus according to claim 1, wherein the head control unit moves the head onto the disk medium in response to convergence of rotation fluctuations exceeding a threshold value by the rotation fluctuation detection unit.   2. The disk apparatus according to claim 1, wherein the motor control unit is configured to stop the rotation of the spindle motor when the rotation variation detecting unit detects a rotation variation exceeding a threshold value. The motor control unit is configured to restart rotation of the spindle motor after stopping rotation of the spindle motor in response to detection of rotation fluctuation exceeding a threshold value by the rotation fluctuation detection unit,
The rotation fluctuation detector detects rotation fluctuations of the spindle motor that has resumed rotation,
The motor control unit stops rotation of the spindle motor again in response to detection of rotation fluctuation exceeding the threshold value of the spindle motor that has resumed rotation by the rotation fluctuation detection unit,
4. The head control unit moves the head onto the disk medium in response to convergence of rotation fluctuations exceeding a threshold value of the spindle motor that has resumed rotation at the rotation fluctuation detection unit. The disk device described. It further includes an impact sensor for detecting an impact applied to the disk device,
The motor control unit receives the fact that the rotation fluctuation detection unit has detected a rotation fluctuation exceeding a threshold and stops the rotation of the spindle motor, and then receives no shock detection by the shock sensor, Resuming rotation of the spindle motor;
The motor control unit detects the presence or absence of rotation fluctuation exceeding a threshold value of the spindle motor that has resumed rotation by the rotation fluctuation detection unit,
4. The head control unit moves the head onto the disk medium in response to convergence of rotation fluctuations exceeding a threshold value of the spindle motor that has resumed rotation at the rotation fluctuation detection unit. The disk device described. Further comprising a disk medium,
6. The disk device according to claim 1, wherein the threshold value is recorded on the disk medium. A head for recording and reading information on a rotating disk medium;

A spindle motor that rotationally drives the disk medium;
An actuator for moving the head onto the rotating disk medium and retracting from the disk medium;
A control method of a disk device comprising a motor control unit that controls the rotation of the spindle motor and generates a pulse signal synchronized with the rotation of the spindle motor,
A rotation fluctuation detecting step of detecting a rotation fluctuation of the spindle motor by measuring a cycle of the pulse signal;
And a head retracting step for retracting the head from the disk medium in response to detection of a rotational variation exceeding a threshold in the rotational variation detecting step.

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