JP2003272331A - Disk device having external magnetic field detection function and method of controlling the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a disk device having a highly reliable external magnetic field detection function and a method for controlling the same in which the destruction of data saved on a disk medium is prevented even if a head receives an external magnetic field in a state in which the head is located on the disk medium. <P>SOLUTION: The disk device having the external magnetic field detection function and the method of controlling the same calculate the resistance of a head 121 consisting of a magnetoresistance effect element when the head 12 is present on the disk medium 11 to detect the external magnetic field applied to the device. When the external magnetic field is detected, the number of revolution of an SPM 14 is increased to elevate the flying height of the disk 12 and to evacuate the head 12 from the data area 112 of the disk medium 11. As a result, the destruction of recording data due to the external magnetic field is prevented. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a disk device having an external magnetic field detection function and a control method for the device.

[0002]

2. Description of the Related Art When data is read from or written to a magnetic disk device in an environment where a magnetic field is applied from the outside, the data on the disk medium may be destroyed by the effect of the external magnetic field. There is. In recent years, in particular, since the housings of electronic devices such as personal computers equipped with magnetic disk devices have become thinner and smaller, the disk devices have become more susceptible to the external magnetic field.

On the other hand, Japanese Patent Laid-Open No. 3-242866 discloses an electronic device with a magnetic disk device (magnetic storage device) such as an electronic calculator, which is provided with a magnetic field detection device for detecting that a magnetic field is applied to the magnetic disk device. Immediately before the host executes the data writing process to the magnetic disk device, the host inquires of the magnetic field detection device whether the magnetic field is applied to the magnetic disk device,
A technique is described in which data read / write processing is executed only when a magnetic field is not applied, and the host itself suspends execution of data read / write processing when a magnetic field is applied. According to the technique described in this publication, it is possible to prevent the program from running away due to a change in data during the data read / write processing with respect to the magnetic disk device which is caused by the influence of the magnetic field.

[0004]

As described above, in the technique disclosed in Japanese Patent Laid-Open No. 3-242866 (hereinafter referred to as "prior art"), the host executes data read / write processing with respect to the magnetic disk device. Immediately before, it is checked whether a magnetic field is applied to the magnetic disk device, and if the magnetic field is not applied, the data read / write processing is executed to read / write data to / from the magnetic disk device generated by the influence of the magnetic field. The program is prevented from running away due to changes in data during processing.

However, in the above prior art, the head (magnetic head) for reading / writing data from / to the disk medium (recording medium) of the magnetic disk device is located on the data area (data track) of the disk medium. No consideration is given to the problem when a magnetic field is applied while the magnetic field is on. That is, when an inductive head is used as the head, there is also a problem that a current flows through the head due to a noise induction magnetic field due to an external magnetic field. If the head is located on the data area (data track) of the disk medium,
As a result of an external magnetic field being applied to the head, if a current induced by the external magnetic field flows in the head, even if data read / write processing by the host is suspended, the data area (data track) in which the head is located Data is destroyed.

Generally, when the magnetic disk device starts up, when the disk medium reaches a certain rotational speed, the head is automatically loaded onto the data area of the disk medium from a head retraction mechanism such as a lamp, regardless of the operation of the host. It
In this state, the host can execute data read / write processing with respect to the disk medium. However, if an external magnetic field is applied to the head when the head is loaded,
Before the host executes the reading / writing process of data with respect to the disk medium, the data recorded on the disk medium may be destroyed by the current flowing through the head by the external magnetic field. That is, as in the above-mentioned prior art, checking whether or not an external magnetic field is applied to the magnetic disk device immediately before execution of the data read / write processing prevents the data recorded on the disk medium from being destroyed. From the point of view, it was not always effective.

A reproducing head (hereinafter referred to as an MR head) including a magnetoresistive effect element (hereinafter referred to as an MR element) before the head is loaded on the magnetic disk medium.
MR element and head amplifier IC circuit BHV (Buff
MR using the erd Head Voltage) function
A technique for detecting an external magnetic field from a change in the resistance value of the head and issuing a warning to the host side without loading the head when the external magnetic field is detected is also under study. Furthermore,
When the magnetic disk device is manufactured, the resistance value of each MR head is stored in a storage element such as a memory, and the external magnetic field can be detected in a form that includes variations in the MR head, preventing data destruction due to the external magnetic field. Technology to try is also being considered.

However, with the above technique, it is possible to prevent data destruction due to an external magnetic field when the head is unloaded, but the head has already been loaded onto the disk medium and already exists on the disk medium. It is impossible to prevent the destruction of data by the external magnetic field generated during the operation.

Furthermore, since the external magnetic field is not detected even when the head is loaded on the disk medium, when a situation occurs in which a magnetic field is externally applied while the head is loading on the disk medium, The external magnetic field is pulled into the write head not only during the write / read operation but also during the seek operation (the data write / read operation is not performed), which is simply the positioning operation of the head. However, there is a problem that the risk of data destruction cannot be avoided.

The present invention has been made in consideration of the above circumstances, and an object thereof is to detect an external magnetic field after the head is loaded on the magnetic disk medium, that is, even when the head is positioned on the disk medium. In this case, it is an object of the present invention to provide a disk device having a highly reliable external magnetic field detection function that prevents destruction of data stored on a disk medium or minimizes damage, and a method of controlling the same.

[0011]

In order to achieve the above object, a disk device having an external magnetic field detecting function according to an aspect of the present invention magnetically records information recorded on a disk medium rotating by a spindle motor. In a disk device for reproducing by a head composed of a resistance effect element, an external magnetic field detecting means for detecting an external magnetic field applied to the disk device from a resistance value of the magnetoresistive effect element, and an external magnetic field detecting means for the disk device. When it is detected that an external magnetic field has been applied, the spindle motor is rotated to control the head to move to a position where there is no recorded information.

In the disk device having such a structure, when the head is loaded and exists on the disk medium, the resistance value of the head composed of the magnetoresistive effect element is calculated and applied to the magnetic disk device. The external magnetic field that is being detected is detected. As a result, when the external magnetic field is detected, the rotation speed of the spindle motor is increased to increase the flying height of the head, thereby increasing the distance between the head and the disk medium, and further recording the data of the disk medium. By retracting the head from the area where it is located, it is possible to prevent the data recorded on the disk medium from being destroyed by the external magnetic field, and when the external magnetic field is detected even when the head is located on the disk medium, It is possible to provide a disk device having a highly reliable external magnetic field detection function that prevents destruction of data stored on a disk medium or minimizes damage, and a method of controlling the same.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which the present invention is applied to a magnetic disk device will be described below with reference to the drawings. [First Embodiment] FIG. 1 is a block diagram showing a configuration of a magnetic disk device according to a first embodiment of the present invention. In the magnetic disk device (hereinafter referred to as HDD) of FIG. 1, the disk medium 11 has two disk medium surfaces, an upper side and a lower side. At least one of the two disk medium surfaces of the disk medium 11 such as both disk medium surfaces forms a recording surface on which data is magnetically recorded. A ring-shaped data area 112 in which a large number of concentric tracks (data tracks) 111 are arranged is secured on each recording surface. Heads (magnetic heads) 12 are arranged corresponding to the respective recording surfaces of the disk medium 11. The head 12 is used for writing data on the disk medium 11 (data recording) and reading data from the disk medium 11 (data reproduction). The head 12 is an MR (Magneto Resistive).
e) A composite head in which a read head (MR head) 121 composed of an element and a write head (inductive head) 122 composed of an inductive recording thin film element are integrated on the same slider. In the configuration of FIG. 1, an HDD including a single disk medium 11 is assumed,
It may be an HDD in which a plurality of disk media 11 are stacked.

On each recording surface of the disc medium 11, a plurality of servo areas (not shown) are arranged radially from the center of the disc medium and at equal intervals in the circumferential direction of the disc medium. Servo data used for seek / positioning of the head 12 is recorded in the servo area.

The head 12 is attached to the tip of a rotary actuator 13, that is, the tip of a suspension 13b extending from an arm 13a of the actuator 13, and the disk medium 11 is rotated in accordance with the rotation (angle rotation) of the actuator 13. Move in the radial direction.
As a result, the head 12 seeks on the target track.
It is supposed to be positioned. A lamp (ramp mechanism) 10 is arranged near the outermost periphery of the disk medium 11. The ramp 10 is a head retracting mechanism for retracting the head 12 to the outside of the disk medium 11 when the rotation of the disk medium 11 is stopped. The ramp 10 is provided near the disk medium 11 and at a predetermined position on the movement path of the tip of the actuator 13.

The disk medium 11 is rotated at high speed by a spindle motor (hereinafter referred to as SPM) 14. The actuator 13 has a voice coil motor (hereinafter referred to as VCM) 15 that is a drive source of the actuator, and is driven by the VCM 15.

The SPM 14 and the VCM 15 are motor driver ICs (Integrated Circuits) 16
Driven by the drive currents respectively supplied from. The motor driver IC 16 is a one-chip motor driver and constitutes an SPM driver and a VCM driver. Motor driver IC 16 to SPM 14 and VCM
The value (control amount) for determining the drive current supplied to each of 15 is determined by the CPU 21.

The head 12 is a head IC (head amplifier I) mounted on a flexible printed wiring board (FPC).
C) 17 is connected. The head IC (head amplifier IC) 17 includes a read amplifier that amplifies a read signal read by the read head 121 in the head 12, a bias circuit that supplies a bias current to the read head 121 in the head 12, and write data. The head amplifier circuit is a one-chip head amplifier circuit that includes a write amplifier that converts the write current to be supplied to the write head 122 in the head 12.

The head IC (head amplifier IC) 17 is
It is connected to a read / write channel (not shown; hereinafter referred to as R / W channel) and an A / D (analog / digital) converter (hereinafter referred to as ADC) 19. The R / W channel is a head IC (head amplifier I
C) Various signal processing such as A / D (analog / digital) conversion processing, write data encoding processing, and read data decoding processing for the amplified read signal output from 17 is executed. The R / W channel extracts a burst signal in the servo data according to a pulsing function of pulsing a read signal and outputting it as pulsed read data, and a timing signal (burst timing signal) from a gate array (not shown). It has the function to do.
This burst signal is sent to the CPU 21 and the head 12
Is used for positioning control for positioning the target track on the target track, that is, track following control. The ADC 19 converts the amplified read signal output from the head IC (head amplifier IC) 17 into a digital value. This ADC
The output of 19 is sent to the CPU 21 and used to detect a magnetic field applied to the HDD from the outside. In addition, AD
It is also possible to incorporate C19 in the gate array,
In the embodiment of the present invention, the ADC 19 is built in the CPU 21.

The gate array has a function of generating various timing signals including a burst timing signal from a read pulse output from the R / W channel, and a function of extracting a track code included in servo data. There is. This track code is sent to the CPU 21,
It is used for seek control for moving the head 12 to a target track. The gate array also has a function of setting the value of the bias current supplied from the head IC (head amplifier IC) 17 to the read head 121 to the head IC (head amplifier IC) 17 according to the designation from the CPU 21. There is.

The CPU 21 is a non-volatile memory in which a control program executed by the CPU 21 is stored, for example,
FROM (Flash Read Only Memo)
ry) 22 and a RAM (Random Access Memory) that provides a work area for the CPU 21.
And (not shown) are built in. CPU21 is FR
Control of the entire device (HDD) according to a control program stored in the OM 22, for example, seek / positioning control of the head 12 based on the track code extracted by the gate array and the burst signal extracted by the R / W channel, from the host 26 Read / write command by the disk controller (HDC) 29
Performs light control, etc.

The CPU 21 also sets the head 12 retracted to the ramp 10 to the data area 11 of the disk medium 11.
The magnetic field applied to the HDD from the outside is detected based on the output value of the ADC 19 when loading onto the HDD 1, and the rotation speed of the disk medium 11 is controlled by the SPM 14 and the head load / unload by the VCM 15 is performed according to the detection result. Executes load control, etc.

A disk controller (hereinafter referred to as HDC) 29 is connected to a host 26 that uses an HDD. The host 26 is an electronic device such as a personal computer. The HDC 29 processes the read data encoded by the R / W channel according to each control signal from the gate array to generate data to be transferred to the host 26. Further, the HDC 29 encodes the write data transferred from the host 26 in accordance with each control signal from the gate array and transfers it to the R / W channel.

A buffer RAM (not shown) is connected to the HDC 29. Data to be transferred from the host 26 and written to the disk medium 11 (write data) and data to be read from the disk medium 11 and transferred to the host 26 (read data) are stored in the buffer RAM.
A buffer area used for the primary storage of is reserved.

A temperature sensor 23 is provided in the HDD,
It is possible to detect the temperature inside the HDD. The analog output from the temperature sensor 23 is the AD converter 20.
Is converted into a digital value and processed by the CPU 21. In the embodiment of the present invention, the AD converter 2
0 has a configuration incorporated in the CPU 21.

The FROM 22 provided in the CPU 21 is provided with a resistance area 24 that stores the resistance value of each head 12 and a temperature table area 25 that defines the relationship between the resistance value of the head 12 at each temperature. .

An interface circuit (I / F) 18 is arranged between the HDC 29 and the host 26. Next, an outline of the operation of the HDD of FIG. 1 will be described. Here, a method of detecting the external magnetic field during the loading of the head 12 will be described. In this embodiment, the read means 121 MR (M
Agneto Resistive) Head 121 M
R element is used.

FIG. 1 is a block diagram of an HDD having an external magnetic field detecting function according to the first embodiment of the present invention. When a sense current, which is a constant current used for detecting the resistance value of the MR head 121 whose resistance value changes depending on the strength of the magnetic field, is passed through the head IC (head amplifier IC) 17, the MR head 121 passes the sense current. MR depending on current value
The voltage related to the head 121 is output. This output result is sent to the CPU 2 via the head IC (head amplifier IC) 17.
The A / D converter (ADC) 19 incorporated in the unit 1 converts the voltage value input as an analog value into a digital value.

By the digital value of this voltage value, the CPU 2
The resistance value of the MR head 121 can be calculated by the internal processing of 1. Next, the CPU 12 calculates the calculated MR
The strength of the external magnetic field applied to the HDD can be estimated from the resistance value of the head 21. HDD is operating,
A state in which the head 12 is located on the disk medium 11,
That is, while the head 12 is being loaded, the above-mentioned method is performed at regular time intervals, that is, by calculating the resistance value of the MR head 121 from the sense current value of the MR head 121, the external value added to the HDD at any time. The magnetic field shall be detected.

Next, the disk medium 1 mounted on the HDD
The external magnetic field that destroys the data recorded in 1
A method of determining whether or not the voltage is applied to the DD will be described with reference to the flowchart of FIG.

There are individual differences in the resistance value of the MR head 121. Normally, the HDD has 2 to 6 MR heads 12
1 may be mounted, and each of these MR heads 1
The resistance values of 21 are not all the same. Therefore, when the MR head 121 is used as a means for detecting the external magnetic field of the HDD, it is necessary to consider the individual differences in the resistance values of the MR heads 121. In the first embodiment of the present invention, the head 12 and the disk medium 11 are previously prepared, for example, at the time of manufacturing in a state where an external magnetic field is not applied to the HDD.
By loading data onto the disk medium 11 and reproducing the data (for example, servo data, measurement data, etc.) previously stored on the disk medium 11 in this state, the disk medium 11 in the state where the external magnetic field is not applied to the HDD The range of the resistance value of the MR head 121 that changes depending on the magnetic field is acquired as the reference resistance value for each head 12. Further, each MR head 12 measured in advance as described above
The reference resistance value of 1 is the FORM provided in the CPU 21.
It is stored in the resistance value storage area 24 of 22.

Similarly, a temperature sensor 23 is mounted inside the HDD or outside the apparatus housing, and the temperature sensor 23 allows the ambient temperature (for example, −20 ° C. to +6) during manufacturing or the like.
Head 12 corresponding to 5 ° C in the range of 0 ° C
By loading the head 12 onto the disk medium 11 in a state where no external magnetic field is applied to the disk and reproducing the data (for example, servo data, measurement data, etc.) previously stored on the disk medium 11 in this state , The disk medium 1 in the state where no external magnetic field is applied to the HDD
The range of the resistance value of the MR head 121 which changes with the magnetic field from 1 is acquired.

The resistance value of each head 12 for each environmental temperature is stored in the temperature table 25 of the FORM 22 provided in the CPU 21. By setting the temperature table 25 in which the resistance value of each head 12 for each environmental temperature is tabulated in the FROM 2 in the CPU 21, the MR head 1 changes as the environmental temperature changes.
Even when the resistance value of 21 changes, based on each reference resistance value at the corresponding environmental temperature from this temperature table,
The MR head 121 can accurately detect the external magnetic field applied to the HDD in consideration of the change in the environmental temperature.

Next, when the HDD actually mounted on the PC operates, the head 12 moves to the disk medium 11
The external environment temperature during actual operation is measured by the temperature sensor 23 while being loaded on the upper side, and M is measured by the above-mentioned external magnetic field detection method.
The resistance value of the R head 12 is detected by the resistance value detecting means.

Each head 1 is set in correspondence with the current resistance value of each head 12 by the resistance value detecting means and each environmental temperature in advance.
Table for each 2 and temperature table 2 in FROM 22
The CPU 21, which is the comparison means, performs a comparison with the reference resistance value of the MR head 121 stored in step 5.

The CPU 21 determines that the current resistance value of the MR head 121 detected by the resistance value detecting means is changing within the preset reference resistance value of the MR head 121. In this case, it is determined that the external magnetic field applied to the HDD is not applied, and normal read / write
Perform a write or seek operation. Then, after the elapse of a certain time, the above-mentioned external magnetic field detection routine is repeatedly executed again.

The current resistance value of the MR head 121 detected by the resistance value detecting means by the CPU 21 is
When it is determined that the preset reference resistance value range of the MR head 121 is deviated, it is determined that the external magnetic field is applied to the HDD, and the read / write operation currently in operation. Alternatively, the execution of the seek operation is suspended.

Next, when the CPU 21 detects the application of the external magnetic field to the HDD, after the execution of the read / write operation or the seek operation described above is interrupted, the host 26, that is, the user, is currently in the HDD. It issues a warning that the external magnetic field is being applied or that the execution of the read / write operation or seek operation is interrupted by the application of the external magnetic field.

Further, the HDD issues a warning to the host 26, that is, the user, and detects the data concerning the external magnetic field applied to the HDD, for example, which head 12 detects when and how strong the external magnetic field is. Data such as whether it has been recorded is recorded as log information (external magnetic field generation history information) in a predetermined area on the disk medium 11, for example.

After detecting the external magnetic field applied to the HDD as described above, in order to prevent the data recorded on the disk medium 11 from being destroyed or to minimize the damage, the following operation is forced. Switch to the mode.

That is, the head 1 when the external magnetic field is detected
The second operation (read / write operation or seek operation) is interrupted by the processing of the CPU 21, and the host 26 (user)
After recording the log information regarding the sending of the warning and the external magnetic field to the disk medium 11, the CPU 21
Perform the operation of.

SP rotating the disk medium 11
The motor driver IC 16 is controlled so as to increase the rotation speed of M14 above the normal rotation speed. Then, the MR head 12 is loaded on the disk medium 11 in a floating state.
Increase the flying height of 1. That is, the write head 122
SPM to widen the space between the disk medium 11 and
By forcibly controlling the rotation of 14, the data destruction due to the external magnetic field can be prevented. After that, in a state where the flying height of the head 12 is increased, that is, in a state where the rotation of the SPM 14 is increased above the normal rotation speed, the VCM 15 is driven to move the head 12 to the area where the data of the disk medium 11 is recorded. Motor driver IC to be retracted from
Control 16 That is, the operation of the head 12 is forcibly controlled.

When the magnetic field detecting means detects the external magnetic field applied to the HDD, and if the head 12 is located on the outer peripheral side of the disk medium 11, the head 12 is unloaded outside the disk medium 11, When the head 12 is located on the inner circumference side than the middle circumference, the head 12 is moved to the disk medium 11
Control to retract to the innermost circumference. Specifically, when the external magnetic field is detected when the head 12 is located on the outer circumference side of the disk medium 11 from the middle circumference, the head 12 is placed on a ramp (head retreat) arranged near the outer circumference end of the disk medium 11. The VCM 15 is forcibly controlled so as to move onto the (member) 10. In addition, the head 12 is the disk medium 11
When an external magnetic field is detected when the head 12 is located on the inner side of the inner circumference, the head 12 moves to a save area, which is a non-data area called a CSS area 113 provided on the innermost circumference of the disk medium 11. The VCM 15 is forcibly controlled to operate.

As described above, the head 12 is connected to the disk medium 1
1 is unloaded to the outside or saved in the CSS area 113 provided in the innermost periphery of the disk medium 11, and then the external magnetic field detecting means detects the external magnetic field applied to the HDD again, and there is a risk of data destruction. Until it is determined that the external magnetic field is not detected, it is possible to repeatedly execute the external magnetic field detection and prevent the data destruction due to the external magnetic field.

[Second Embodiment] Next, a second embodiment of the present invention will be described with reference to FIGS. In the second embodiment of the present invention, the HD using the MR element of the MR head 121 is similar to the configuration according to the first embodiment described above.
The external magnetic field detection method according to D is different in that the external magnetic field detection method in the first embodiment described above detects the external magnetic field by software, whereas it detects it by hardware. FIG. 3 shows a block diagram of an external magnetic field detection circuit according to the second embodiment of the present invention, and FIG. 4 shows a flowchart.

In the second embodiment of the present invention, HD
MR head 12 when there is no external magnetic field at D
The reference voltage supply circuit 27 that generates a reference voltage corresponding to the resistance value of 1 under the control of the CPU 21, the reference voltage supplied from the reference voltage supply circuit 27, and the MR head 121.
And a comparator 28 for comparing a voltage generated when a constant current is supplied via the head IC (head amplifier IC) 17 with the comparator 28.

Similar to the first embodiment described above, the resistance values of the MR heads 121 mounted on the HDD have individual differences. Usually, two to six MR heads 121 are mounted on the HDD, and the resistance values of the MR heads 121 are not the same. Therefore, when the MR head 121 is used as a means for detecting the external magnetic field of the HDD, it is necessary to consider the individual differences in the resistance values of the MR heads 121. Even in the second embodiment of the present invention, the head 12 is loaded onto the disk medium 11 in advance in a state where an external magnetic field is not applied to the HDD at the time of manufacturing, for example, and in this state in advance on the disk medium 11. By reproducing the stored data (for example, servo data, measurement data, etc.), the range of the resistance value of the MR head 121 which is changed by the magnetic field from the disk medium 11 in the state where the external magnetic field is not applied to the HDD is set. The reference resistance value is acquired for each head 12. Further, the reference resistance value of each MR head 121 measured in advance as described above is F
It is stored in the resistance value storage area 24 of the ORM 22.

Further, a temperature sensor 23 is mounted inside the HDD or outside the apparatus housing, and by this temperature sensor 23,
At the time of manufacturing, the head 12 is loaded on the disk medium 11 in a state where an external magnetic field is not applied to the head 12 in correspondence with each environmental temperature (for example, in the range of −20 ° C. to + 60 ° C. in steps of 5 ° C.) By reproducing the data (for example, servo data, measurement data, etc.) stored in advance on the disk medium 11 in this state, it is changed by the magnetic field from the disk medium 11 when the external magnetic field is not applied to the HDD. The range of the resistance value of the MR head 121 is acquired.

The resistance value of each head 12 for each ambient temperature is stored in the temperature table 25 of the FORM 22 provided in the CPU 21. Here, in the second embodiment of the present invention, the temperature sensor 2 is set at regular intervals.
3, the ambient temperature of the HDD is read, and the temperature table 25 of the FROM 22 incorporated in the CPU 21 is referred to from the read ambient temperature to obtain the reference voltage value corresponding to the resistance value of the MR head 121 when there is no external magnetic field in the HDD. To do. The CPU 21 is connected to the reference voltage supply circuit 27 and generates a reference voltage according to an instruction from the CPU 21.

The reference voltage and the output from the head IC (head amplifier IC) 17 determined by the resistance value of the MR head 121 are input to the comparator 28, and the comparison result is output to the HDC 29. The HDC 29 has a function of causing the CPU 21 to generate an interrupt in accordance with the comparison result of the comparator 28. That is, the comparison result of the comparator 28 indicates that the MR head 12 in which a preset external magnetic field does not exist.
If the value exceeds the resistance value range of 1, it is determined that the external magnetic field is being applied to the HDD, and the CPU 21 performs a later-described embedded process.

In response to the interrupt, the CPU 21 performs the following operation in order to prevent the data recorded on the disk medium 11 from being destroyed or to minimize the damage, as in the first embodiment. Switch to the forced mode.

That is, the head 1 when the external magnetic field is detected
The second operation (read / write operation or seek operation) is interrupted by the processing of the CPU 21, and the host 26 (user)
After recording the log information regarding the warning sending and the external magnetic field in the disk medium 11, the CPU 21 executes the above-mentioned,
Perform the operation of.

That is, the motor driver IC 16 is controlled so as to increase the rotation speed of the SPM 14 rotating the disk medium 11 above the normal rotation speed, and the MR head 121 loaded on the disk medium 11 in a floating state. Increase the ascent height. That is, the SPM 1 is arranged so that the write head 122 and the disk medium 11 are widely spaced apart.
By forcibly controlling the rotation of No. 4, data destruction due to an external magnetic field can be prevented. After that, in a state where the flying height of the head 12 is increased, that is, in a state where the rotation of the SPM 14 is increased above the normal rotation speed, the VCM 15 is driven to move the head 12 to the area where the data of the disk medium 11 is recorded. Motor driver IC1 to be retracted from
6 is controlled to forcibly control the operation of the head 12.

More specifically, the magnetic field detecting means is an HDD.
When the external magnetic field is detected, if the head 12 is present on the outer peripheral side of the disk medium 11 from the inner circumference, the head 12 is unloaded outside the disk medium 11,
When present on the inner circumference side of the middle circumference, the head 12
Is controlled to be retracted to the innermost circumference of the disk medium 11. In other words, when the external magnetic field is detected when the head 12 is located on the outer circumference side of the disk medium 11, the head 12 has a ramp (head retracting member) 10 arranged near the outer circumference end of the disk medium 11. The VCM 15 is forcibly controlled to move up. Further, when an external magnetic field is detected when the head 12 is located on the inner circumference side of the disk medium 11, the head 12 is called a CSS area 113 provided on the innermost circumference of the disk medium 11. VCM1 to move to the save area which is the data area
5 is forcibly controlled.

As described above, the head 12 is connected to the disk medium 1
1 is unloaded to the outside or saved in the CSS area 113 provided in the innermost periphery of the disk medium 11, and then the external magnetic field detecting means detects the external magnetic field applied to the HDD again, and there is a risk of data destruction. Until it is determined that the external magnetic field is not detected, it is possible to repeatedly execute the external magnetic field detection and prevent the data destruction due to the external magnetic field.

In this embodiment, the MR head mounted on the HDD is used as the external magnetic field detecting means.
The present invention is not limited to this, and as long as the external magnetic field in the HDD can be detected, GMR (Giant M
It is needless to say that the same effect can be obtained by disposing an external magnetic field detection circuit (element) separately from the head mounted on the HDD or inside the apparatus housing or in the vicinity of the outside.

[0057]

As described in detail above, according to the present invention,
When the head is present on the disk medium, the resistance value of the head composed of the magnetoresistive effect element is calculated to detect the external magnetic field applied to the device, and when the external magnetic field is detected, the SPM is detected. By increasing the number of revolutions of the head to increase the flying height of the head and retracting the head from the data area of the disk medium, even if the head is placed on the disk medium and an external magnetic field is received, It is possible to provide a disk device having a highly reliable external magnetic field detection function and a control method for the same device, which prevents destruction of stored data.

[Brief description of drawings]

FIG. 1 is a block diagram showing a configuration of a magnetic disk device according to a first embodiment of the present invention.

FIG. 2 is a flowchart illustrating a method of controlling the magnetic disk device according to the first embodiment of the invention.

FIG. 3 is a block diagram showing a configuration of a magnetic disk device according to a second embodiment of the present invention.

FIG. 4 is a flowchart illustrating a method of controlling the magnetic disk device according to the second embodiment of the present invention.

[Explanation of symbols]

10 ... Lamp (head retracting member) 11 ... Disk medium 12 ... Head (composite head) 13 ... Actuator 14 ... SPM (spindle motor) 15 ... VCM (voice coil motor) 16 ... Motor driver IC 17 ... head IC (head amplifier IC) 18 ... interface circuit (I / F) 19, 20 ... AD converter (ADC) 21 ... CPU 22 ... FROM 23 ... temperature sensor 24 ... resistance value storage area 25 Temperature table 26 Host 27 Reference voltage supply circuit 28 Comparator 29 Disk controller (HDC) 112 Data area 113 CSS area (non-data area, head retract mechanism) 121 Read head (magnetic field detector) 122 ... write head

Claims (11)

[Claims] 1. A disk device for reproducing information recorded on a disk medium rotating by using a spindle motor by a head composed of a magnetoresistive effect element, wherein the resistance value of the magnetoresistive effect element is applied to the disk device. An external magnetic field detecting means for detecting an external magnetic field; and, when the external magnetic field detecting means detects that an external magnetic field is applied to the disk device, the spindle motor is rotated so that the head does not have the recorded information. A disk device comprising: a control unit that moves to a position. 2. A temperature sensor is provided, and when the external magnetic field detection means determines that an external magnetic field is not applied to the disk device, all the heads when the head is loaded on the disk medium are used. 2. The disk device according to claim 1, further comprising a storage unit that presets and stores a range of resistance values of the magnetoresistive effect element for each environmental temperature. 3. The external magnetic field detecting means according to claim 1, wherein when the head is loaded on the disk medium, the external magnetic field detecting means periodically detects the presence or absence of the external magnetic field at regular time intervals. Disk device. 4. When the external magnetic field detection means detects that an external magnetic field is applied to the disk device, the head-related information including at least the resistance value of the magnetoresistive element is logged. The disk device according to claim 1, further comprising: a log information holding unit that stores the information as information, and a warning generation unit that issues a warning to the host system. 5. The control means forcibly stops the current operation when the external magnetic field detecting means detects that an external magnetic field is applied to the disk device. Disk device. 6. The disk device according to claim 1, wherein the control means increases the number of revolutions of the spindle motor to increase the flying height of the head. 7. The control unit includes a head retracting unit that retracts the head to the outside of the disk medium or to an area on the disk medium where data is not stored. Disk device. 8. The disk drive according to claim 7, wherein the head retracting means forcibly unloads the head out of the disk medium. 9. The head retracting means positions the head outside the middle circumference on the disk medium when the external magnetic field detecting means detects that an external magnetic field is applied to the disk device. In this case, the head is retracted to the outside of the disk medium, and the head is retracted to the innermost circumference of the disk medium if the head is located inside the middle circumference on the disk medium. The disk device according to claim 7. 10. The control means detects that an external magnetic field is applied to the disk device by the external magnetic field detection means, and the head retracting means moves the head out of the disk medium or on the disk medium. Data is saved in the save area in which the external magnetic field is not saved, the external magnetic field detection means executes the external magnetic field detection in the head save area, and the external magnetic field detection means externally detects the external magnetic field until the external magnetic field is no longer applied. 8. The disk device according to claim 7, wherein the magnetic field detection is controlled to be repeated. 11. A method of controlling a disk device for reproducing information recorded on a disk medium rotating by using a spindle motor by using a head composed of a magnetoresistive effect element, wherein the disk is determined from a resistance value of the magnetoresistive effect element. Detecting the external magnetic field applied to the device, and when detecting the external magnetic field applied to the disk device, increasing the rotation of the spindle motor to control the movement of the head to a position without the recorded information. And a method for controlling a disk device.