JPH0836713A - Magnetic recording / reproducing device - Google Patents

Abstract

(57) [Abstract] [Purpose] By making the sense current value flowing through a magnetoresistive effect element (MR element) when reading servo information from a magnetic recording medium smaller than the sense current value when reading data, To extend the life of the MR element. [Structure] A current value flowing through a magnetoresistive element when reading a servo segment which is a first information recording portion and a data segment which is a second information recording portion of a sector on a magnetic recording medium 2 is Isv. , Ist
(Optimum value: minimize asymmetry of reproduced waveform)
Let sv <Ist. As a result, the average value of the substantial current flowing through the MR element can be reduced, so that the life of the MR element can be extended.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic recording / reproducing apparatus equipped with a magnetic head whose read head is a magnetoresistive element, and more particularly to a magnetic recording / reproducing apparatus suitable for ensuring reliability.

[0002]

2. Description of the Related Art As a conventional magnetic recording / reproducing apparatus, as shown in, for example, Japanese Patent Laid-Open No. 3-160675, FIG.
A configuration as shown in is known. In FIG. 7, a magnetic disk recording medium 2 is driven by a spindle 3, and a write / read separated magnetic head 1 is positioned on the recording medium 2 by a positioning mechanism 4. When a signal is written (recorded), a signal sent via a disk controller (hereinafter abbreviated as DKC) 21 is recorded / reproduced by a command from the CPU 20.
Is converted into a current signal and applied to the electromagnetic induction type write element portion of the magnetic head 1. The magnetic field of the magnetic head 1 generated by this current application is written in the medium 2 as magnetization information. At the time of reading (reproduction) of a signal, the magnetization information recorded in the recording medium 2 is caused to flow through a read element portion of the magnetic head 1 which is composed of a magnetoresistive effect element (magnetoresistive effect reproducing element, MR element). Convert it to an electrical signal,
It is detected as a signal through the recording / reproducing amplifier circuit 22. FIG. 8 is a conceptual diagram of tracks in a general magnetic recording medium. The magnetic recording medium 2 is divided into concentric tracks, and each track is divided into sectors. For example, in the case of the data surface servo system, as shown in FIG. 8, the sector further includes an ID segment 6 and a data segment 7. It is divided into servo segments 8. The magnetic head 1
CPU 20 when positioning the
Positioning command (servo signal) for the servo segment 8 in response to the command sent via the DKC 21
Is accurately positioned on the track 10. ID
In the segment 6, for example, a cylinder number, a head number,
The sector number and the like are recorded, and the magnetic head 1 has the ID
The information recorded in the segment 6 is detected, a predetermined place is found to write and read the data, and the data segment 7 at the rear of the ID segment 6 is detected.
Data is written to or read from.

Even when no signal is written or read, the magnetic head 1 is positioned on any track based on the positioning signal of the servo segment 8 on any track.

[0004]

As described above, the read element portion of the magnetic head 1 which is composed of the magnetoresistive effect element is in the operating state in many time zones during operation of the magnetic recording / reproducing apparatus.

However, the above-mentioned prior art has not been considered in terms of the life of the read element portion composed of the magnetoresistive effect element.

It is well known that a current (sense current I) is passed through the magnetoresistive effect element in order to read the information recording portion written on the magnetic recording medium.
On the other hand, this magnetoresistive element is a kind of resistor,
It is also well known that the life of a resistor is determined by the magnitude of the value of the current passed through the resistor and the integrated value of the time when the current is passed.

That is, when the magnetoresistive effect element is mounted on the magnetic recording / reproducing apparatus, the life time of the magnetic recording / reproducing apparatus is also determined by the magnitude of the current value flowing through the magnetoresistive effect element. In particular, in the case of the data surface servo system as in the above-mentioned embodiment, the read element portion composed of the magnetoresistive effect element is in operation in many time zones during operation of the magnetic recording / reproducing apparatus, so that it is This is a problem for the life of the magnetic recording / reproducing apparatus which is required to be 10 years.

The applicant of the present invention has previously filed Japanese Patent Application No. 5-15.
Due to the patent application of No. 459, a magnetoresistive head (M
A technique has been proposed in which the bias current (sense current) of the R head) is adjusted for each magnetic head and for each position in the medium radial direction and set to a required value. This "required value" means the difference between the magnitudes of the upper peak value and the lower peak value of the waveform when read by the MR head, or the time difference between the temporal upper peak position and the lower peak position of this waveform. Or a value that minimizes the read error of the data section information. However, in this patent application, the sense current flowing in the MR head is set as small as possible, and the servo information is read out without any problem even if the difference in magnitude between the upper peak value and the lower peak value is in the waveform.
No consideration is given to extending the life of the R head or extending the life by reducing the sense current value in the idle period.

The applicant of the present invention has previously filed Japanese Patent Application No. 5-9.
The patent application of No. 228 has proposed a technique for preventing the read error by changing the read current (sense current) flowing through the magnetic film of the magnetoresistive head (MR head) when the read error is detected. However, in this patent application, regardless of whether or not a read error has occurred, the sense current flowing to the MR head when reading servo information is set as small as possible to extend the life of the MR head and sense the idle period. No consideration is given to extending the life by reducing the current value as much as possible.

Therefore, the present invention solves the above-mentioned problems of the prior art, and is a required magnetic recording / reproducing apparatus in a magnetic recording / reproducing apparatus equipped with a magnetic head whose read element section is a magnetoresistive element. An object of the present invention is to provide a highly reliable magnetic recording / reproducing apparatus that satisfies the above life.

[0011]

In order to achieve the above object, the present invention is configured as follows.

(1) With a magnetic head having a magnetoresistive reproducing element, the head is positioned by reproducing servo information from the magnetic recording medium, and data is recorded and reproduced with respect to the magnetic recording medium. In the reproducing device, when the servo information is reproduced from the magnetic recording medium, a sense current value to be passed through the magnetoresistive effect reproducing element,
The value is smaller than the sense current value passed through the magnetoresistive effect reproducing element when reproducing data information from the magnetic recording medium.

(2) Further, the magnetic head having the magnetoresistive reproducing element reproduces servo information from the magnetic recording medium to position the head, thereby recording / reproducing data to / from the magnetic recording medium. In a magnetic recording / reproducing apparatus, a sense current value to be passed through the magnetoresistive effect reproducing element when the host apparatus is in an idle state where there is no access, and a sense current value which is passed through the magnetoresistive effect reproducing element when there is access from the upper apparatus. It is less than the current value.

(3) A sense current may be passed through the magnetoresistive effect reproducing element only when reproducing servo information from the magnetic recording medium in an idle state in which no access is made from the host device. .

[0015]

The operation based on the above configuration will be described.

(1) In general, the life of a magnetoresistive effect reproducing element is determined by the magnitude of the value of the current flowing through the magnetoresistive effect reproducing element and the integrated value of the time when the current is applied. That is, the life of the magnetoresistive reproducing element can be extended by reducing the value of the current flowing through the magnetoresistive reproducing element.

By the way, reproduction (reading) of the data signal
At times, the sense current value is set to an optimum value, that is, a value that provides a waveform with a larger reproduction voltage without amplitude asymmetry in order to ensure data discrimination and prevent read errors. Must be set. On the other hand, when reproducing (reading) the servo information, the servo information frequency is lower than the data signal frequency,
Since the ratio of the magnitudes of the two servo signals is used as information, a large reproducing voltage and a positive / negative symmetry of the reproducing waveform are not required. Therefore, when reproducing servo information,
It is possible to make the sense current value lower than the sense current value at the time of data reproduction.

The present invention focuses on this, and the sense current value flowing through the magnetoresistive effect reproducing element when reproducing servo information from the magnetic recording medium is changed to the magnetoresistive effect type when reproducing data information. By making the sense current value smaller than the sense current value flowing in the reproducing element, the average value of the substantial current flowing in the magnetoresistive effect reproducing element can be decreased, and the life of the magnetoresistive effect reproducing element can be extended. .

(2) Further, the sense current value to be passed through the magnetoresistive effect reproducing element in the idle state where no access is made from the host device (standby state where neither seek nor read / write is performed) is accessed from the host device. By reducing the sense current value flowing through the magnetoresistive effect reproducing element at the same time, the average value of the substantial sense current flowing through the magnetoresistive effect reproducing element can be reduced and the life can be extended. . In this case, the sense current value during the servo information reproduction period may be the same as the sense current value during the data signal reproduction period when there is access from the host device, but as in (1) above, the sense current value during the data signal reproduction period is the same. By lowering the value, the average value of the substantial sense current can be further reduced.

(3) In the above item (2), the sense current is supplied to the magnetoresistive effect reproducing element only when reproducing servo information from the magnetic recording medium in an idle state where there is no access from the host device. However, this can further reduce the substantial average value of the sense current.

[0021]

Embodiments of the present invention will be described below with reference to the drawings.

First, as the first and second embodiments, the case of the data surface servo system in which servo information and data information are recorded on the same magnetic recording medium surface will be described with reference to FIGS.
Will be explained.

FIG. 1 is a block diagram of a magnetic recording / reproducing apparatus according to an embodiment of the present invention. In FIG. 1, a magnetic disk recording medium 2 is driven by a spindle 3, and a magnetic head 1 is positioned on the recording medium 2 by a positioning mechanism 4, which is a rotary actuator mechanism in this example. When writing a signal, the signal sent through the DKC 21 is converted into a current signal by the recording / reproducing amplifier circuit 22 by the write command of the CPU 20 and applied to the electromagnetic induction type write element portion of the magnetic head 1. The magnetic field of the magnetic head 1 generated by this current application is written in the medium 2 as magnetization information. At the time of reading a signal, a sense current is caused to flow through a read element portion, which is a magnetoresistive effect element of the magnetic head 1, so that the magnetization information recorded on the recording medium 2 is converted into an electric signal, and the recording / reproducing amplifier circuit 22.
Is detected as a signal through. In addition, the DKC21
Has a sense current switching function 25 for switching the current value of the sense current (bias current) flowing through the read element portion of the magnetic head 1 between the reading of servo information and the reading of data information. Further, the DKC 21 is provided with a servo position detection timer 26 which informs the position of the servo segment 8 on the track.

FIG. 2 is a diagram showing the concept of tracks and sense current switching timing in the recording medium of the embodiment of FIG. The magnetic recording medium 2 is divided into concentric tracks, and each track 10 is divided into sectors. In the data surface servo system, as shown in FIG. 2, the sector further stores an ID segment 6 and data information. It is divided into a data segment 7 and a servo segment 8 in which servo information is recorded. In addition,
Reference numeral 11 is an index signal representing the beginning of the track 10. A cylinder number, a head number, a sector number, etc. are recorded in the ID segment 6, and the read element unit of the magnetic head 1 detects the information recorded in the ID segment 6 and writes or reads data. A predetermined place (sector) to be performed is found, and data is written into the data segment 7 at the rear of the ID segment 6 by the write element section or read by the read element section. The servo segment 8 is, for example, further GAPA81, GAPB82, POSA83, POSB.
It is divided into 84.

As a first embodiment, the data segment 7
The switching of the sense current when the read element portion of the magnetic head 1 reads the servo segment 8 and the servo segment 8 will be described. Various methods are conceivable as the sense current switching method. In the first method, the sense current flowing through the read element portion of the magnetic head 1 is normally the optimum value Ist for reading data according to the instruction of the sense current switching function 25 of the DKC 21.
(Details will be described later), and the data written in the data segment 7 of a certain sector is read. At the rear of the data segment 7, there is the servo segment 8 of the next sector, and as described above, the GAPA 81, GAPB 8
2, POSA83, POSB84. G
A signal having a certain pattern is written in the APA 81, and no signal is written in the GAPB 82. The read element unit of the magnetic head 1 first reads the GAPA 81 and then the GAPB 82. The DKC 21 detects a portion 82, which has no signal next to the signal 81 of the fixed pattern, to detect the position signal PO used for the next positioning.
Know that SA83 and POSB84 exist. Based on this, Isv changes from Isv (details will be described later, Is
The value is smaller than t, but the servo signal can be read sufficiently), and the position signal POSA8 is set.
3. The POSB 84 is read to position the magnetic head 1. Position signals POSA83, POSB84
Based on this determination, the DKC 21 that has determined that the reading of the data has been completed sets the sense current to be supplied to the read element portion of the magnetic head 1 to Ist in the instruction of the sense current switching function 25 immediately after that. The ID segment and data segment 7 of the sector are read. The sense current switching portion is provided with a gap of 1 to 2 μs, which is sufficient in time to switch the sense current value flowing in the read element portion of the magnetic head 1. Further, when a series of sectors in a track is continuously read by the first method, the gap between the data segment of the immediately preceding constant length sector and the GAPA 81 of the next sector is detected, thereby As described above, the sense current may be switched from Ist to Isv.

As a second method, usually, the sense current value is set to Isv, and it is switched to Ist immediately after the POSB signal 84 is detected, and ID and data are stored until the sector of a certain length is completed. When the segment is read and the sector (fixed length) ends, Is
A method of reading a series of sectors by returning to v is also conceivable.

Further, as a third method, as shown in FIG. 2, in order to determine the timing for switching the sense current values of the data segment 7 and the servo segment 8,
The servo signal detection timer 26 provided in the DKC 21 may be used. Since the sectors are equally divided and lined up on the track, the position signal also arrives at regular intervals. Therefore, as shown in FIG. 2, the servo signal detection timer 26 outputs the timer signal 26a in synchronization with the index signal 11 indicating the track start end, the timer signal 26a is used to switch the sense current value, and the position signal POSA83, The POSB 84 may be read. In this case, the sense current value changes from Ist to Isv in the gap immediately before the GAPA 81 as shown in FIG.
Switch to Isv to I in the gap immediately after POSB.
You can switch to st. Also in this case, the sense current switching portion is provided with a gap of 1 to 2 μs, which is sufficient in time to switch the sense current value flowing through the read element portion of the magnetic head 1.

Here, the setting of the sense current value flowing in the read element portion of the magnetic head 1 and the life of the magnetoresistive element which is the read element portion will be described.

FIGS. 3 and 4 are diagrams showing an example of the relationship between the sense current and the read voltage characteristic and the relationship between the sense current and the waveform amplitude asymmetry characteristic, which are the electromagnetic conversion characteristics of the magnetoresistive effect element. Here, the horizontal axes of FIGS. 3 and 4 both show values standardized by the optimum current value Ist (sense current value that minimizes asymmetric waveform distortion). The vertical axis of FIG. 3 shows the value standardized by the read voltage at the optimum current value Ist.

In FIG. 3, it can be seen that the read voltage is increased by increasing the sense current. On the other hand, in FIG. 4, it can be seen that the waveform amplitude asymmetry characteristic shifts from negative to positive by increasing the sense current, and a waveform without asymmetry can be obtained by selecting the sense current to an appropriate value (optimum value Ist).

When reading the data segment 7,
The sense current value of the magnetoresistive element is the optimum value Ist.
To use. The reason is to prevent a reading error by using a data discriminating circuit having a differentiating circuit and a threshold circuit to surely discriminate data with a waveform having a larger read voltage without amplitude asymmetry. On the other hand, when reading the servo segment 8, the sense current value Isv of the magnetoresistive effect element may be a value smaller than the optimum value Ist when reading the data segment 7. In this example, the case of Isv≈0.7 × Ist will be described. In FIG. 3, the read voltage at the sense current value Isv is about 80 times the read voltage at the sense current value Ist.
%, And in FIG. 4, the waveform amplitude asymmetry (P−N) /
(P + N) is about -8%. Here, P and N represent the positive amplitude value and the negative amplitude value of the read waveform. However, in the case of demodulating the servo signal, the magnitude of the read voltage and the symmetry of the waveform when demodulating the data signal are not required. The reason is that the frequency of the servo signal is smaller than the frequency of the data signal, and as described below, positioning does not use the waveform or amplitude of the servo signal as information, but rather the two servo signals (POSA, POSB)
This is because the ratio of the size of is used as information.

Positioning by servo signals will be described with reference to FIG. FIG. 5 is a diagram showing the relationship between the position of the magnetic head and the read waveform. Position signal POS
A83 and POSB 84 are recorded on the magnetic recording medium 2 as shown in FIG. When this signal is read by the read element unit of the magnetic head 1 positioned at the track center, the sense current value is set to Isv, so that the amplitude of the waveform becomes asymmetric as shown in FIG. 5b. As described above, the positioning is performed by detecting the size of the servo signal, that is, the read waveforms of the POSA 83 and the POSB 84, and the size of the shaded area in FIG. 5B using, for example, an integrator and using this ratio as information. There is no problem if the read waveform has asymmetric amplitude. Figure 5
In the case of b, since the magnitudes of the read waveforms of the POSA 83 and the POSB 84 are the same, the DKC 21 determines that there is no positional deviation. FIG. 5d shows the read waveform of the servo signal when the read element portion of the magnetic head 1 is positioned off the track center as shown in FIG. 5c. POSA83
The read waveform of No. 2 has a larger waveform amplitude according to the shift amount, and the read waveform of the POSB 84 has a smaller waveform amplitude according to the shift amount. POSA83 and POSB
Since the read waveform of 84 has the same amplitude asymmetry, the shift amount becomes the ratio of the read waveform sizes of the POSA 83 and the POSB 84. Based on this information, the DKC 21 determines the shift amount and corrects the shift.

As described above, the read waveform of the servo signal may have the minimum required read voltage magnitude and the minimum required waveform amplitude symmetry. That is the above-mentioned read voltage at the sense current value Isv, which is the waveform amplitude asymmetry.

Next, the life of the magnetoresistive element will be described with reference to FIG. FIG. 6 is an example showing the relationship between the sense current and the life characteristic of the magnetoresistive effect element. Here, the horizontal axis of FIG. 6 shows a value normalized by the optimum current value Ist,
The vertical axis shows the value standardized by the life time of the magnetoresistive effect element at the optimum current value Ist. In FIG. 6, it can be seen that assuming that the life time at the sense current value Ist is 1, the life time at the sense current value Isv (when Isv is constantly supplied) is improved about 100 times.

As described above, the servo signal can be positioned even with a read waveform having an asymmetric amplitude due to the decrease in the sense current, and the life of the magnetoresistive effect element can be reduced by decreasing the sense current. Can be extended.

According to the present embodiment, the value of the current flowing through the read element portion formed of the magnetoresistive element of the magnetic head can be reduced, so that the life of the read element portion can be extended.

Next, as a second embodiment, when the servo element 8 is read by the read element section of the magnetic head 1, there is access from the host device and an idle state without access (seek is also read / write). Switching of the sense current between (when not doing) and

When there is an access from the host device, that is, when there is a command for writing or reading a signal to the magnetic recording device via the DKC 21 in response to a command from the CPU 20 (when seeking or reading / writing), for example, reading Command, the sense current flowing through the read element portion of the magnetic head 1 is set to Ist by the instruction of the sense current switching function 25 of the DKC 21, and the data segment 7 and the servo segment 8 of a certain sector have the same current value Ist. Read. Alternatively, the sense current may be switched from Ist to Isv according to an instruction from the sense current switching function 25 when reading the data segment 7 and the servo segment 8 as in the first embodiment. On the other hand, when the host device is in an idle state where there is no access, tracking control is necessary at this time as well. Therefore, the DKC 21 activates the sense current switching function 25 to set the sense current to Isv, and the magnetic field is read only when the servo segment 8 is read. The sense current Isv is passed through the read element portion of the head 1 to read the servo signal, and the sense current is not passed in the other segments. At this time, the servo signal detection timer 26 provided in the DKC 21 is used as the timing for supplying the sense current to the read element portion of the magnetic head 1.

According to the present embodiment, the value of the current flowing through the read element portion of the magnetoresistive effect element of the magnetic head in the idle state can be made smaller than that in the case of access, so that the read element portion. The life of can be extended. In particular, when the first embodiment (switching between Ist and Isv for the data segment and the servo segment when there is an access) is further adopted in this embodiment, the life of the read element section can be further extended.

In the case of a data surface servo type magnetic recording apparatus, for example, in a magnetic recording apparatus of the type having two heads (magnetic heads are provided on the front and back sides of a magnetic disk), one head is used. However, the time for reading the servo information is about 2,000 to 3,000 hours, the time for reading the data information is about 2,000 hours, and both are about the same. As described above, according to the first and second embodiments, the sense current value at the time of reading the servo information is Isv.
You can Read the servo information I sense current value
If sv, the life at this time is improved by about 100 times as long as the life at the sense current value Ist for reading data information.
The life at this time does not have to be taken into consideration, and the life time of the read element portion of the magnetic head 1 is set to Is.
It can be extended approximately twice as much as in the case of v = Ist.

Next, as a third embodiment, a case of a servo surface servo system in which servo information and data information are recorded on different magnetic recording medium surfaces will be described.

In the case of this method, the value of the current flowing in the read element portion of the magnetoresistive element of the magnetic head used for the servo surface is set to Isv, and the magnetic resistance of the magnetic head used for the data surface is set. The value of the current flowing through the read element section including the effect element is set to Ist. By setting the value of the current flowing through the read element portion of the magnetic head used for the data surface to the optimum value Ist described in the first embodiment, a waveform having a larger read voltage without amplitude asymmetry can be obtained. , It is possible to reliably discriminate data. The value of the current flowing through the read element portion of the magnetic head used on the servo surface is the optimum value I described in the first embodiment.
Set Isv less than st to read out the servo signal. At this time, the read waveform of the servo signal has an asymmetric amplitude, but as described in the first embodiment, positioning can be performed with this asymmetric waveform.

According to this embodiment, the value of the current flowing through the read element portion of the magnetic head used on the servo surface can be reduced, so that the life of the read element portion of the magnetic head used on the servo surface can be reduced. Can be extended.

In the above embodiment, Isv≈0.7 × Ist
As described above, the ratio between the sense current value Isv and Ist depends on the electromagnetic conversion characteristics and the life characteristics of the read element portion including the magnetoresistive element of the magnetic head 1 and the life required for the magnetic recording device. It is necessary to change. As is clear from FIG. 6, if this ratio is 0.9 or less, the life can be significantly extended.

As is apparent from the above description, according to the above-described embodiment, the average value of the substantial sense currents flowing in the read element portion formed of the magnetoresistive effect element of the magnetic head can be reduced. It is possible to extend the life of the magnetoresistive effect element.

[0046]

As described above in detail, according to the present invention, the sense current value flowing through the magnetoresistive effect reproducing element of the magnetic head during reproduction of servo information is caused to flow through this magnetoresistive effect reproducing element during data reproduction. By reducing the sense current value (optimum value), it is possible to reduce the average value of the substantial current flowing in the magnetoresistive effect reproducing element, which can extend the life of the magnetoresistive effect reproducing element. Therefore, there is an effect that the reliability of the magnetic recording device can be improved.

Further, by making the sense current value of the magnetoresistive reproducing element in the idle state in which there is no access from the host device smaller than the sense current value in the case of access, the average value of the sense current is similarly set. It is also possible to obtain the effect that the life of the magnetoresistive effect reproducing element can be extended by reducing the amount.

[Brief description of drawings]

FIG. 1 is a diagram showing an example of a magnetic recording / reproducing apparatus to which the present invention is applied.

FIG. 2 is an explanatory diagram showing a concept of tracks on a recording medium and a concept of timing of switching a sense current.

FIG. 3 is a characteristic diagram showing an example of the sense current and read voltage characteristics of the magnetoresistive effect reproducing element.

FIG. 4 is a characteristic diagram showing an example of sense current and waveform amplitude asymmetry characteristics of a magnetoresistive effect reproducing element.

FIG. 5 is an explanatory diagram showing the relationship between the positioning of the magnetic head and the read waveform.

FIG. 6 is a characteristic diagram showing an example of sense current and life characteristics of a magnetoresistive effect reproducing element.

FIG. 7 is a diagram showing an example of a conventional magnetic recording / reproducing apparatus.

FIG. 8 is an explanatory diagram showing the concept of tracks on a recording medium.

[Explanation of symbols]

 1 Magnetic Head 2 Magnetic Recording Medium 3 Spindle 4 Positioning Mechanism 6 ID Segment 7 Data Segment 8 Servo Segment 20 CPU 21 Disk Controller 22 Recording / Reproducing Amplifying Circuit 25 Sense Current Switching Function 26 Servo Signal Detection Timer 83, 84 Position Signal

Front page continuation (72) Inventor Hideo Tanabe 2880, Kozu, Odawara-shi, Kanagawa Hitachi Storage Systems Division, (72) Inventor Shigeyoshi Saito 2880, Kozu, Odawara, Kanagawa Storage Systems Division, Hitachi, Ltd.

Claims (3)

[Claims] 1. A magnetic recording / reproducing method for recording / reproducing data to / from a magnetic recording medium by positioning the head by reproducing servo information from the magnetic recording medium by a magnetic head having a magnetoresistive reproducing element. In the apparatus, a sense current value flowing through the magnetoresistive effect reproducing element when reproducing servo information from the magnetic recording medium is caused to flow through the magnetoresistive effect reproducing element when reproducing data information from the magnetic recording medium. A magnetic recording / reproducing apparatus characterized in that it is smaller than the sense current value. 2. A magnetic recording / reproducing method for recording / reproducing data to / from a magnetic recording medium by positioning the head by reproducing servo information from the magnetic recording medium with a magnetic head having a magnetoresistive reproducing element. In the device, the sense current value to be flown to the magnetoresistive effect reproducing element when the host device is in an idle state where there is no access from the sense current value to be passed to the magnetoresistive effect reproducing element when there is access from the host device. A magnetic recording / reproducing apparatus characterized in that the number is also reduced. 3. A sense current is supplied to the magnetoresistive effect reproducing element only when reproducing servo information from the magnetic recording medium in an idle state where there is no access from the host device. The magnetic recording / reproducing apparatus described.