JP2006260652A - Magnetic disk device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a magnetic disk device capable of detecting the deterioration of a magnetic head more early while the magnetic head can access the recording surface of the magnetic disk normally, thereby taking a necessary action normally. <P>SOLUTION: This device is provided with: a magnetic disk 2 having a recording surface b constituted of a magnetic medium and disposed to be rotary-controlled; a magnetic head 4 for accessing information in the recording surface b, an actuator 6 for supporting the magnetic head 4 and moving the magnetic head 4 in the diameter direction a of the magnetic disk 2; and a control unit 8 for controlling the rotation of the magnetic disk 2, the movement of the magnetic head 4 via the actuator 6, and accessing to the recording surface b via the magnetic head 4. The device is further provided with: a noise detection means 18 for detecting noise output from the magnetic head 4; and a head deterioration time processing means 8b for executing predetermined processing when the noise of a predetermined permissive level or higher is detected. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention provides a magnetic disk having a recording surface made of a magnetic medium and provided so as to be capable of rotation control, a magnetic head for accessing information to the recording surface, and supporting the magnetic head, and the magnetic head is attached to the magnetic head. An actuator for moving the disk in the radial direction; and a control unit that performs rotation control of the magnetic disk, movement control of the magnetic head via the actuator, and access control to the recording surface via the magnetic head. The present invention relates to a magnetic disk device.

  In a magnetic disk device, there is a problem that a magnetic head that accesses information on a recording surface (medium) of the magnetic disk deteriorates over a long period of use and eventually becomes unusable. In recent years, in particular, as the recording density of magnetic disks has increased, the distance between the magnetic head and the recording surface has become narrower, and the magnetic head and the recording surface have become easier to contact during operation. Head deterioration is easy to progress.

  When the magnetic head can not access the records degraded surface, such as the loss of recorded data, it is often to cover great damage to the user. Therefore, in Patent Document 1, the deterioration is detected by detecting the DC resistance of the magnetoresistive element of the magnetic head, and when the deterioration is detected, the data of the corresponding magnetic disk is accessed by another magnetic head. Magnetic disk devices have been proposed that perform abnormal processing such as moving to an area.

JP-A-9-198623

However, the conventional magnetic disk device described in Patent Document 1 has the following problems.
That is, in the magnetic disk device described in Patent Document 1, the direct current resistance of the magnetoresistive effect element of the magnetic head is detected, the abnormality of the magnetic head is detected by the increase in the direct current resistance value, Although abnormal processing such as data saving is performed, the resistance value of the magnetoresistive element changes when the magnetic head has deteriorated considerably. There is a problem that normal access cannot be performed and information cannot be read correctly from the recording surface. That is, when the resistance value of the magnetoresistive effect element is increased, there is a problem in that treatment such as normal reading and saving of data may not be performed normally.

  The present invention has been made to solve the above-mentioned problems, and its object is to detect the deterioration of the magnetic head earlier while the magnetic head can normally access the recording surface of the magnetic disk. An object of the present invention is to provide a magnetic disk device capable of normally performing necessary treatments.

  The inventors of the present application have conducted a scrutiny to solve the above problems, and if the deterioration of the magnetic head is detected from the amount of noise output from the magnetic head, the magnetic head can no longer access the recording surface. In addition, the inventors have found that the deterioration of the magnetic head can be detected at an early stage, and have completed the present invention.

In order to solve the above problems, a magnetic disk device according to the present invention comprises the following arrangement. That is, a magnetic disk having a recording surface made of a magnetic medium and provided so as to be controllable for rotation, a magnetic head for accessing information on the recording surface, and supporting the magnetic head, the magnetic head being attached to the magnetic disk And a control unit that performs rotation control of the magnetic disk, movement control of the magnetic head via the actuator, and access control to the recording surface via the magnetic head. In a disk device, a noise detecting unit for detecting noise output from the magnetic head, and when the noise is detected by the noise detecting unit at a predetermined allowable level or more, a predetermined process is performed. And a processing means.
According to this, by detecting the deterioration of the magnetic head from the amount of noise output from the magnetic head, the deterioration of the magnetic head can be detected at an early stage, and the magnetic head cannot access the recording surface of the magnetic disk. Before that, it is possible to perform a predetermined process and perform a necessary treatment.

The head deterioration processing unit further includes a signal indicating an abnormality of the magnetic head when noise exceeding the predetermined allowable level is detected by the noise detection unit. Output from the external interface.
According to this, by outputting a signal indicating an abnormality of the magnetic head from the external interface, it is possible to notify the computer or the like connected to the external interface of the abnormality of the magnetic head and to prompt necessary processing.

Further, the head deterioration time processing means changes the sense current or sense voltage applied to the magnetic head and changes the magnetic current by the noise detection means when the noise detection means detects a noise exceeding the predetermined allowable level. Detecting noise from the head, and setting a sense current or a sense voltage when accessing the recording surface so that the noise is minimized.
According to this, the sense current or the sense voltage is adjusted so that the noise output from the magnetic head is minimized, and the recording surface can be accessed with a more appropriate sense current or sense voltage even in a state where the deterioration has advanced. Can be adjusted to do.

In addition, a plurality of sets of the recording surface and the magnetic head for accessing information to the recording surface are provided, and the head deterioration processing unit is configured to detect from the one of the plurality of magnetic heads by the noise detection unit. When noise exceeding the predetermined allowable level is detected, a process of saving information recorded on the recording surface corresponding to the magnetic head to another recording surface is performed.
In addition, a plurality of sets of the recording surface and the magnetic head for accessing information to the recording surface are provided, and at least one of the recording surfaces is not accessed by the control unit. The pre-recording surface is set, and the head deterioration processing unit detects the pre-recording surface when the noise detection unit detects noise of the predetermined allowable level or more from one of the plurality of magnetic heads. The setting is canceled, and the recording surface corresponding to the magnetic head in which noise of a predetermined allowable level or more is detected is set as a new preliminary recording surface.
According to this, recorded information can be saved while the magnetic head can normally access the recording surface.

Further, the head deterioration processing unit performs a process of changing a recording density when the magnetic head accesses the recording surface when the noise detecting unit detects a noise exceeding the predetermined allowable level. It is characterized by that.
According to this, while the access to the recording surface by the magnetic head can be normally performed, it is possible to take measures such as changing the recording density on the recording surface of the magnetic head to be small.

The magnetic head further comprises head magnetizing means for re-magnetizing the magnetic head in an unloaded state in which the magnetic head is retracted from the recording surface. When noise exceeding an allowable level is detected, re-magnetization of the magnetic head by the head magnetizing means is executed.
According to this, when the deterioration of the magnetic head is detected, the magnetic head can be re-magnetized to reproduce the magnetic head.

Further, the head deterioration time processing means stores information indicating an abnormality of the magnetic head in the storage means when the noise detecting means detects noise of the predetermined allowable level or more.
According to this, the history of detecting noise from the magnetic head can be stored in the storage means. Based on the history information, it is possible to perform a process such as examining a deteriorated process of the magnetic head.

Further, the noise detecting means can measure the noise in a loaded state in which the magnetic head is positioned on the recording surface.
According to this, it is possible to suitably detect noise in the usage state of the magnetic head.

Further, the noise detecting means is capable of measuring the noise in an unloaded state in which the magnetic head is retracted from the recording surface.
According to this, it is possible to suitably detect noise that is constantly output from the magnetic head regardless of whether or not it is in a loaded state.

Further, the noise detecting means can detect random telegraph noise caused by shaking of the magnetic head by detecting the noise having a frequency of 50 MHz or less.
According to this, low-frequency random telegraph noise generated by the swing of the magnetic head itself can be suitably detected.

Further, a noise amount measuring track on which a predetermined recording pattern is recorded is formed in the recording surface, and the noise detecting means detects the noise while reading the recording pattern on the noise amount measuring track. It is characterized by performing.
According to this, it is possible to arbitrarily set an output pattern at the time of reading by the magnetic head and measure noise.

Further, the predetermined recording pattern is a recording pattern consisting of a demagnetized state.
According to this, it is possible to measure the noise generation state in the state where the output level is the lowest when the recording surface is read by the magnetic head.

The noise detecting means is provided so that the amount of noise can be detected for each frequency.
According to this, it becomes possible to identify the cause of noise and the state and cause of deterioration of the magnetic head.

Further, the noise detection means includes an output of the magnetic head when reading a magnetized portion on the recording surface, and a noise output from the magnetic head when reading a demagnetized portion on the recording surface. The degradation processing means detects that the amount of noise when reading the demagnetized portion is greater than a predetermined ratio with respect to the output of the magnetic head when reading the magnetized portion. In this case, the predetermined process is executed.
According to this, when the demagnetized portion is read, it is possible to detect that noise close to a predetermined ratio or more is generated in the signal output when the magnetized portion is read.

Further, the noise detecting means detects an output of the magnetic head when reading the demagnetized portion on the recording surface, and the deterioration processing means is for detecting the output of the magnetic head when reading the demagnetized portion. The predetermined process is executed when the output is larger than a predetermined allowable level by a predetermined reference value or more.
According to this, it is possible to measure the noise generation state in the state where the output level is the lowest when the recording surface is read by the magnetic head.

In addition, the noise detection unit can detect the noise for each sense current value or sense voltage value by changing a sense current or a sense voltage applied to the magnetic head. .
According to this, it is possible to identify the cause of noise, the state and cause of deterioration of the magnetic head, and to detect the optimum sense current or sense voltage according to the state of the magnetic head.

Further, the noise detecting means is capable of measuring the noise while applying a predetermined direct current or alternating current load to the magnetic head.
According to this, it is possible to specify the cause of noise and the state and cause of deterioration of the magnetic head.

And a heating / cooling means for heating or cooling the magnetic head in an unloaded state in which the magnetic head is retracted from the recording surface, wherein the noise detection means is configured to heat / cool the magnetic head. The noise can be measured while heating or cooling by means.
According to this, it becomes possible to detect the amount of noise corresponding to the temperature of the magnetic head, or to set the temperature of the magnetic head to a temperature with a small amount of noise.

In addition, the noise detection unit performs the detection of the noise at regular intervals.
According to this, deterioration of the magnetic head can be periodically inspected and detected.

The magnetic head further comprises head operating time measuring means for measuring the operating time of the magnetic head, and the noise detecting means is configured to detect the noise with a constant cumulative operating time of the magnetic head measured by the head operating time measuring means. It is characterized by being executed every time.
According to this, the deterioration of the magnetic head can be inspected and detected every time the operating time of the magnetic head elapses.

The noise detection unit may detect the noise when the magnetic disk device is started up such as when the power is turned on or reset, or when the magnetic disk device is shut down.
According to this, since the deterioration of the magnetic head is inspected at the time of starting or ending the magnetic disk device, the inspection can be performed without affecting the operation during use of the magnetic disk device.

  According to the magnetic disk device of the present invention, the deterioration of the magnetic head can be detected earlier and the necessary treatment can be normally performed while the magnetic head can access the recording surface of the magnetic disk normally. it can.

The best mode for carrying out a magnetic disk device according to the present invention will be described below.
FIG. 1 is an explanatory diagram showing a configuration of a magnetic disk device A according to the present embodiment. FIG. 2 is an explanatory view of the magnetic disk 2 viewed from a direction parallel to the plate surface.
The magnetic disk device A has recording surfaces b, c, d, and e (see FIG. 2) made of a magnetic medium. The magnetic disk device A is provided so as to be capable of rotation control, and the recording surfaces b, c, d, and e. A magnetic head 4 of a GMR head or TMR head that accesses (reads) information, an actuator 6 that supports the magnetic head 4 and moves the magnetic head 4 in the radial direction of the magnetic disk 2, and rotation control of the magnetic disk 2 The control unit 8 that controls the movement of the magnetic head 4 through the actuator 6 and the access control to the recording surfaces b, c, d, and e through the magnetic head 4 can be connected to an external device such as ATAPI. External interface 16.

The magnetic disk 2 is formed in a disc shape, and recording surfaces b, c, d, e made of a magnetic medium on which information is recorded by being magnetized or demagnetized by the magnetic head 4 are formed on the front and back surfaces thereof. Has been. As shown in FIG. 2, the magnetic disk device A includes two magnetic disks 2, and the two magnetic disks 2 and 2 are provided in parallel with each other at a predetermined interval and connected at the center.
Further, the magnetic disk 2 is connected to a spindle motor 10 controlled by the control unit 8 and is provided so as to be able to control rotation.

  The actuator 6 includes a carriage body 6a that is rotatable about an actuator shaft 6e in a plane parallel to the recording surfaces b, c, d, e, and the recording surfaces b, c, d, an arm 6b extending in parallel along e, a suspension 6c having one end attached to the arm 6b and a magnetic head 4 attached to the tip, and a carriage body 6a parallel to the recording surfaces b, c, d, e. And a spindle motor 6d controlled by the control unit 8 for moving the magnetic head 4 in the radial direction a of the magnetic disk 2 (see FIG. 1).

A total of three arms 6b are provided on both sides of the both magnetic disks 2 and one between the magnetic disks 2.
The suspension 6 c and the magnetic head 4 attached to the arm 6 b are provided corresponding to each recording surface b, c, d, e of the two magnetic disks 2. The arm 6b provided between the two magnetic disks 2 has two (two sets) suspensions 6c and 6c and a magnetic head 4 corresponding to the opposing recording surfaces c and d of the two magnetic disks 2 and 2, respectively. , 4 are attached.

The magnetic head 4 approaches the recording surfaces b, c, d, e of the rotated magnetic disk 2 and scans the recording surfaces b, c, d, e, so that the recording surfaces b, c, d, e The magnetic state recorded on the magnetic medium is converted into an electric signal. This electric signal is input to the preamplifier 12 and amplified, and is restored as digital information by the signal processing means 8 a realized by the control unit 8. The restored digital information is transmitted to the computer C, which is an external device connected via the external interface 16.
The magnetic disk device A also includes a noise detection circuit 14 that detects non-linear noise included in the electrical signal output from the magnetic head 4 and amplified by the preamplifier 12.

  The control unit 8 includes a CPU, other LSIs, a storage unit 8d, a timer 8c, and the like. The CPU 8 executes a firmware program recorded in the ROM and executes functions of the LSI, thereby executing the functions of the magnetic disk 2. Rotation control, movement control of the magnetic head 4 via the actuator 6, access control to the recording surfaces b, c, d, e of the magnetic disk 2 via the magnetic head 4 can be performed, and signal processing means 8a and The head deterioration processing means 8b described later is provided so as to be realizable.

(Head deterioration processing means 8b)
The head deterioration time processing means 8b executes a predetermined process when the noise detection means 18 (described later) detects non-linear noise exceeding a predetermined allowable level from the magnetic head 4 via the preamplifier 12.
Various processes can be adopted as the predetermined process. Several examples are given below. These “predetermined processes” are not necessarily configured to be all realizable, and only one or some of them may be employed.

The head deterioration time processing means 8b outputs a signal indicating an abnormality of the magnetic head 4 from the external interface 16 to an external device (computer C) when the noise detecting means 18 detects noise exceeding the predetermined allowable level. .
According to this, it is possible to notify the computer C or the like connected to the external interface 16 of the abnormality of the magnetic head 4 and prompt necessary processing. For example, the computer C is caused to perform processing for saving the data in the magnetic disk device A to another storage medium, or the display of the computer C is displayed to notify the abnormality of the magnetic disk device A to alert the user. It may be configured as follows.

Further, the head deterioration processing unit 8b is operated by the noise detection unit 18 while changing the sense current or the sense voltage applied to the magnetic head 4 when the noise detection unit 18 detects a noise exceeding the predetermined allowable level. The noise from the magnetic head 4 is detected, and the sense current or the sense voltage for accessing the recording surfaces b, c, d, e is set so that the noise is minimized.
According to this, by adjusting the sense current or the sense voltage so that the noise output from the magnetic head 4 is minimized, the recording surfaces b and c can be recorded with a more appropriate sense current or sense voltage even in a state where the deterioration has advanced. , D, e can be adjusted.

  Further, the head deterioration time processing means 8b responds to the magnetic head 4 when the noise detecting means 18 detects noise exceeding the predetermined allowable level from one of the plurality of magnetic heads 4, 4,. the information recorded on the recording surface (for example, a recording surface b) which is configured to perform a process of saving to another recording surface (for example, a recording surface c). According to this, it is possible to access to the recording surface b by the magnetic head 4 While performed successfully, saves the recorded information to the recording surface c.

  In addition, at least one of the plurality of recording surfaces b, c, d, e (for example, the recording surface e) is set in advance as a preliminary recording surface to which no information is accessed by the control unit 8. The deterioration processing unit 8b cancels the setting of the recording surface e as the preliminary recording surface when the noise detection unit 18 detects noise of the predetermined allowable level or more from one of the plurality of magnetic heads 4. together, to set the recording surface corresponding to the magnetic head 4 to a predetermined allowable level or noise is detected (e.g. recording surface b) a new preliminary recording surface. According to this, it is possible to save a while access to the recording surface b by the magnetic head 4 can be performed properly, the recording surface e of the recorded information.

  Further, the head deterioration processing unit 8b performs a process of changing the recording density when the magnetic head 4 accesses the corresponding recording surface when the noise detecting unit 18 detects noise of the predetermined allowable level or more. Do. For example, even if the magnetic head 4 starts to deteriorate by decreasing the number of recording bits in the direction along the track (BPI bit per inch) or by decreasing the density between tracks (TPI track per inch). Ensure that the recording surface can be accessed normally.

Further, an unload state in which the magnetic head 4 is retracted from the recording surfaces b, c, d, e (in FIG. 1, the unload area of the outer peripheral portion of the magnetic disk 2 from which the magnetic head 4 is removed from the recording surface) 2a), a head magnetizing means 20 comprising an electromagnet for remagnetizing the magnetic head 4 is provided, and the head deterioration time processing means 8b is above the predetermined permissible level by the noise detecting means 18. When the noise is detected, re-magnetization of the magnetic head 4 by the head magnetizing means 20 is executed.
According to this, when the deterioration of the magnetic head 4 is detected, the magnetic head 4 can be re-magnetized to reproduce the magnetic head 4.

Further, the head deterioration processing unit 8b causes the storage unit 8d to store information indicating an abnormality of the magnetic head 4 when the noise detection unit 18 detects a noise that is equal to or higher than the predetermined allowable level.
According to this, the history of detecting noise from the magnetic head 4 can be stored in the storage means 8d. Based on this history information, it is possible to perform a process such as examining a deteriorated process of the magnetic head 4.

(Noise detection means 18)
Next, the configuration of the noise detection means 18 will be described.
The noise detection means 18 includes a noise detection circuit 14 and a control unit 8 (see FIG. 1).
Various methods can be adopted as a noise detection method by the noise detection means 18. Several examples are given below. These noise detection methods are not necessarily configured to be all realizable, and only one or some of them may be employed.

  The noise detection means 18 controls the actuator 6 by the control unit 8 and loads the magnetic head 4 on the recording surfaces b, c, d, e in a load state from the magnetic head 4 via the preamplifier 12. 14 is provided so that the noise input to 14 can be detected. According to this, it is possible to suitably detect noise in the usage state of the magnetic head 4.

  In addition, the noise detection means 18 controls the actuator 6 by the control unit 8 so that the magnetic head 4 is withdrawn from the recording surfaces b, c, d, e, and then from the magnetic head 4 via the preamplifier 12. The noise detection circuit 14 is provided so that it can detect noise. According to this, the noise output at all times from the magnetic head 4 regardless of whether the load state, can be suitably detected.

The noise detection means 18 is provided so as to detect random telegraph noise caused by the shaking of the magnetic head 4 by detecting the noise having a frequency of 50 MHz or less.
According to this, it is possible to suitably detect low-frequency random telegraph noise generated by the swing of the magnetic head 4 itself.

In addition, a noise amount measurement track on which a predetermined recording pattern is recorded is formed in advance in the recording surfaces b, c, d, and e, and the noise detection means 18 records the recording pattern on the noise amount measurement track. It may be configured to detect noise while reading. According to this, an output pattern at the time of reading by the magnetic head 4 can be arbitrarily set, and noise can be measured.
As an example of the predetermined recording pattern, for example, a recording pattern composed entirely of a demagnetized state can be employed. According to this, it is possible to measure a noise generation state in a state where the output level is the lowest when the recording surfaces b, c, d, e are read by the magnetic head 4.
As another example of the predetermined recording pattern, a so-called die pit pattern in which a pattern in which a positive magnetization state and a negative magnetization state continuously appear after a demagnetization state of a predetermined length may be employed. .

  The noise detection means 18 may be provided so that the amount of noise can be detected for each frequency. This is configured to incorporate a spectrum analyzer circuit in the noise detection circuit 14 or to decompose the noise signal output from the noise detection circuit 14 for each frequency by performing calculation processing such as fast Fourier transform by the control unit 8. It can be realized by doing. According to this, it becomes possible to identify the cause of noise and the state and cause of deterioration of the magnetic head.

Further, the noise detecting means 18 outputs the output of the magnetic head 4 when reading the magnetized portions on the recording surfaces b, c, d, e and the demagnetized portions on the recording surfaces b, c, d, e. The head deterioration processing means 8b detects the noise output from the magnetic head 4 when the magnetized portion is read, and the demagnetized portion with respect to the output of the magnetic head 4 when the magnetized portion is read. When the amount of noise when reading is larger than a predetermined ratio, a predetermined process is executed.
According to this, when the demagnetized portion is read, it is possible to detect that noise close to a predetermined ratio or more is generated in the signal output when the magnetized portion is read.

The noise detecting means 18 detects the output of the magnetic head 4 when the demagnetized portions on the recording surfaces b, c, d, e are read, and the head deterioration time processing means 8b is used for the demagnetized portions. When the output of the magnetic head at the time of reading is greater than a predetermined reference value by a predetermined allowable level or more, the predetermined processing is executed.
According to this, it is possible to measure a noise generation state in a state where the output level is the lowest when the recording surfaces b, c, d, e are read by the magnetic head 4.

Further, the noise detection means 18 changes the sense current or sense voltage applied to the magnetic head 4 so as to detect the noise for each sense current value or sense voltage value.
According to this, it is possible to identify the cause of noise, the state and cause of deterioration of the magnetic head, and to detect the optimum sense current or sense voltage according to the state of the magnetic head 4.

The noise detecting means 18 is provided so that the noise can be measured while applying a predetermined direct current or alternating current load to the magnetic head 4.
According to this, according to this, the cause of noise and the state and cause of deterioration of the magnetic head 4 can be specified.

Further, in the unloaded state in which the magnetic head 4 is retracted from the recording surfaces b, c, d, e, heating / cooling means 22 such as a heater or a cooler for heating or cooling the magnetic head 4 (see FIG. 1). The noise detecting means 18 is provided so that the noise can be measured while the magnetic head 4 is heated or cooled by the heating / cooling means 22.
According to this, it becomes possible to detect the amount of noise corresponding to the temperature of the magnetic head, or to set the temperature of the magnetic head to a temperature with a small amount of noise.

Moreover, the noise detection means 18 is comprised so that the detection of the said noise may be performed for every fixed time. This can be realized by performing a noise detection process in the timeout interrupt of the timer 8c that times out at regular intervals of the control unit 8.
According to this, deterioration of the magnetic head 4 can be periodically inspected and detected.

Further, a head operating time measuring means for measuring the operating time of the magnetic head 4 is provided, and the noise detecting means 18 detects the noise by a constant cumulative operating time of the magnetic head 4 measured by the head operating time measuring means. Provided to run every time.
According to this, deterioration of the magnetic head 4 can be inspected and detected every time the operating time of the magnetic head 4 elapses.

Further, the control unit 8, at the start of power-on or reset of the magnetic disk device A, or, at the end of such shutdown, configured to perform the noise detection by the noise detection unit 18.
According to this, since the deterioration of the magnetic head 4 is inspected at the time of starting or ending the magnetic disk device A, the inspection can be performed without affecting the operation during use of the magnetic disk device A.
(Appendix 1)
A magnetic disk having a recording surface made of a magnetic medium and provided so as to be capable of rotation control, a magnetic head for accessing information on the recording surface, and supporting the magnetic head, and the magnetic head is arranged with a diameter of the magnetic disk Magnetic disk apparatus comprising: an actuator that moves in a direction; a rotation control of the magnetic disk; a movement control of the magnetic head via the actuator; and a control unit that performs access control to the recording surface via the magnetic head And a noise detecting means for detecting noise output from the magnetic head, and a head deterioration processing means for executing a predetermined process when the noise detecting means detects the noise above a predetermined allowable level. And a magnetic disk device.
(Appendix 2)
An external interface that can be connected to an external device, and the head deterioration processing unit outputs a signal indicating an abnormality of the magnetic head when the noise detection unit detects a noise of the predetermined allowable level or more. The magnetic disk apparatus according to appendix 1, wherein the magnetic disk apparatus outputs the data from an interface.
(Appendix 3)
Said head degradation during processing means, when the predetermined allowable level or noise is detected by said noise detecting means, from the magnetic head by the noise detection means while changing the sense current or a sense voltage applied to the magnetic head The magnetic disk apparatus according to appendix 1 or 2, wherein a sense current or a sense voltage for accessing the recording surface is set so that the noise is detected and the noise is minimized.
(Appendix 4)
A plurality of sets of the recording surface and the magnetic head for accessing information to the recording surface are provided, and the head degradation processing unit is configured to detect the predetermined value from one of the plurality of magnetic heads by the noise detection unit. When noise exceeding the allowable level is detected, information recorded on the recording surface corresponding to the magnetic head is evacuated to another recording surface. The magnetic disk device according to claim 1.
(Appendix 5)
Preliminary recording in which a plurality of sets of the recording surface and the magnetic head for accessing information to the recording surface are provided, and at least one of the plurality of recording surfaces is not accessed by the control unit The head deterioration time processing means sets the preliminary recording surface when the noise detection means detects a noise exceeding the predetermined allowable level from one of the plurality of magnetic heads. The magnetic surface according to any one of appendices 1 to 4, wherein the recording surface corresponding to the magnetic head in which noise of a predetermined allowable level or higher is detected is set as a new preliminary recording surface. Disk unit.
(Appendix 6)
The head deterioration processing unit performs a process of changing a recording density when the magnetic head accesses the recording surface when the noise detecting unit detects noise of the predetermined allowable level or more. The magnetic disk device according to any one of Supplementary notes 1 to 5, which is characterized by the following.
(Appendix 7)
In unloaded state is retracted the magnetic head from the said recording surface, a head magnetizing means for performing re-magnetizing the magnetic head, the head degradation during processing means, said predetermined allowable level by said noise detecting means 7. The magnetic disk device according to any one of appendices 1 to 6, wherein when the above noise is detected, re-magnetization of the magnetic head by the head magnetizing unit is executed.
(Appendix 8)
The head deterioration time processing means stores information indicating an abnormality of the magnetic head in a storage means when noise exceeding the predetermined allowable level is detected by the noise detection means. 8. The magnetic disk device according to claim 7.
(Appendix 9)
9. The magnetic disk device according to claim 1, wherein the noise detecting unit is capable of measuring the noise in a loaded state in which the magnetic head is positioned on the recording surface. .
(Appendix 10)
10. The magnetic disk according to claim 1, wherein the noise detecting unit can measure the noise in an unloaded state in which the magnetic head is retracted from the recording surface. apparatus.
(Appendix 11)
The noise detection means is capable of detecting random telegraph noise caused by shaking of the magnetic head by detecting the noise having a frequency of 50 MHz or less. The magnetic disk device described.
(Appendix 12)
A noise amount measuring track on which a predetermined recording pattern is recorded is formed in the recording surface, and the noise detecting means detects the noise while reading the recording pattern on the noise amount measuring track. The magnetic disk device according to any one of appendices 1 to 11, characterized in that:
(Appendix 13)
13. The magnetic disk device according to appendix 12, wherein the predetermined recording pattern is a recording pattern consisting of a demagnetized state.
(Appendix 14)
The magnetic disk device according to any one of appendices 1 to 13, wherein the noise detecting means is provided so that the amount of the noise can be detected for each frequency.
(Appendix 15)
The noise detecting means detects an output of the magnetic head when reading a magnetized portion on the recording surface and a noise output from the magnetic head when reading a demagnetized portion on the recording surface. And the deterioration processing means is configured such that the amount of noise when the demagnetized portion is read is larger than a predetermined ratio with respect to the output of the magnetic head when the magnetized portion is read. The magnetic disk device according to claim 1, wherein the predetermined process is executed.
(Appendix 16)
The noise detection means detects the output of the magnetic head when reading the demagnetized portion on the recording surface, and the degradation processing means detects the output of the magnetic head when reading the demagnetized portion. The magnetic disk device according to any one of appendices 1 to 15, wherein the predetermined processing is executed when the predetermined reference level is greater than a predetermined allowable level.
(Appendix 17)
The noise detecting means is capable of detecting the noise for each current value or sense voltage value of the sense current by changing a sense current or a sense voltage applied to the magnetic head. The magnetic disk device according to any one of?
(Appendix 18)
18. The magnetic disk device according to claim 1, wherein the noise detecting unit is capable of measuring the noise while applying a predetermined direct current or alternating current load to the magnetic head. .
(Appendix 19)
In unloaded state is retracted the magnetic head from the said recording surface, comprising a heating / cooling means for the magnetic head warming or cooling, said noise detection means, by the heating / cooling means the magnetic head The magnetic disk device according to any one of appendices 1 to 18, wherein the noise can be measured while heating or cooling.
(Appendix 20)
20. The magnetic disk device according to any one of appendices 1 to 19, wherein the noise detection unit detects the noise at regular intervals.
(Appendix 21)
A head operating time measuring means for measuring the operating time of the magnetic head, the noise detecting means, the detection of the noise, the head operation time measuring means by elapsed accumulation operation time of a predetermined time of the magnetic head measured The magnetic disk device according to any one of appendices 1 to 20, wherein the magnetic disk device is executed each time the operation is performed.
(Appendix 22)
Any one of Supplementary notes 1 to 21, wherein the noise detection unit executes the noise detection when the magnetic disk device is started up such as when the power is turned on or reset, or when the magnetic disk device is shut down or the like. A magnetic disk device according to claim 1.

It is explanatory drawing which shows the structure of the magnetic disc apparatus based on this invention. It is explanatory drawing which looked at the magnetic disk from the direction parallel to the plate surface.

Explanation of symbols

A Magnetic disk unit C Computer (external device)
b, c, d, e Recording surface 2 Magnetic disk 2a Unload area 4 Magnetic head 6 Actuator 8 Control unit 8a Signal processing means 8b Head degradation processing means 8c Timer 8d Storage means 10 Spindle motor 12 Preamplifier 14 Noise detection circuit 16 External Interface 18 Noise detection means 20 Head magnetizing means 22 Heating / cooling means

Claims (5)

A magnetic disk having a recording surface made of a magnetic medium and provided so as to be capable of rotation control;
A magnetic head for accessing information to the recording surface;
An actuator for supporting the magnetic head and moving the magnetic head in a radial direction of the magnetic disk;
In a magnetic disk device comprising: a rotation control of the magnetic disk; a movement control of the magnetic head via the actuator; and a control unit that performs access control to the recording surface via the magnetic head.
Noise detection means for detecting noise output from the magnetic head;
A magnetic disk apparatus comprising: a head deterioration processing unit that executes a predetermined process when the noise detection unit detects the noise of a predetermined allowable level or higher. It has an external interface that can be connected to external devices,
The head deterioration time processing means outputs a signal indicating an abnormality of the magnetic head from the external interface when the noise detection means detects a noise exceeding the predetermined allowable level. 1. The magnetic disk device according to 1.   The head deterioration time processing means changes the sense current or the sense voltage applied to the magnetic head from the magnetic head while changing the sense current or the sense voltage applied when the noise detection means detects a noise exceeding the predetermined allowable level. 3. The magnetic disk device according to claim 1, wherein a sense current or a sense voltage for accessing the recording surface is set so that the noise is detected and the noise is minimized. A plurality of sets of the recording surface and the magnetic head for accessing information to the recording surface are provided,
The head deterioration time processing means is recorded on the recording surface corresponding to the magnetic head when the noise detecting means detects noise of the predetermined allowable level or more from one of the plurality of magnetic heads. The magnetic disk apparatus according to claim 1, wherein a process of saving information to another recording surface is performed. A plurality of sets of the recording surface and the magnetic head for accessing information to the recording surface are provided,
At least one of the plurality of recording surfaces is set as a preliminary recording surface where information is not accessed by the control unit,
The head deterioration time processing means cancels the setting of the preliminary recording surface when the noise detection means detects a noise exceeding the predetermined allowable level from one of the plurality of magnetic heads, 5. The magnetic disk apparatus according to claim 1, wherein a recording surface corresponding to a magnetic head in which noise of an allowable level or more is detected is set as a new preliminary recording surface. 6.

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