JPH05314686A - Magnetic disk device - Google Patents

Abstract

(57) [Abstract] [Purpose] To realize high-speed access of a magnetic disk device having a recording / reproducing separated head structure using a magnetoresistive effect magnetic head (hereinafter referred to as an MR head). [Structure] A reproducing signal output switch of the induction type magnetic head is selected at the time of access and a reproducing output of the MR head is selected at the time of tracking, and a bias current required for reproducing the MR head is mounted at the time of access. The drive current of the voice coil motor 9 for moving the slider 8 is distributed.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk drive which moves to a target track at high speed.

[0002]

2. Description of the Related Art In recent years, magnetic disk devices have become more sophisticated, smaller in size, lighter in weight, larger in capacity, and more energy-saving. Particularly, magnetic disk devices aiming for large capacity are required to have high density and high track density. Has been done. In particular, with the increase in density, a magnetic disk device in which a recording head and a reproducing head are separated has appeared.

An example of the above-described conventional magnetic disk device will be described below with reference to the drawings.

FIG. 3 shows a recording / reproducing head of a conventional magnetic disk device. In FIG. 3, 1 is an inductive magnetic head that is a recording head, 2 is a magnetoresistive magnetic head (hereinafter, MR head) that is a reproducing head, and 3 is a magnetic disk. The MR head utilizes the property that the electric resistance value of the ferromagnetic thin film element having uniaxial magnetic anisotropy changes when the external magnetic field is applied to the element due to magnetization rotation. Further, in general, an external magnetic field is applied to the Shun for generating a magnetic field by applying a bias current to the MR head.
The t Bias method or the like is used. MR amplifier 4
Is for applying a bias current I to the MR head 2 and converting an electric resistance value that changes with a change in the magnetic field of the magnetic disk 3 into a change in voltage for detection. FIG. 4 shows the gap 25 of the induction type magnetic head 1 and the gap 26 of the MR head 2. Each magnetic head is attached to a slider which is a head mounting means. The gap width Tw1 of the induction type magnetic head 1 is generally set to be wider than the gap width Tw2 of the MR head 2. As described above, in the recording / reproducing separated head structure, recording is performed by the induction type magnetic head having a wide gap width and the reproducing is performed by the head having a narrow gap width, so that the previously recorded information is recorded off-track. When reproduced, there is an advantage that off-track overwrite noise in which previously recorded information becomes noise and crosstalk from an adjacent track are reduced. Further, the induction type magnetic head 1 can be designed optimally for recording and the MR head 2 can be optimally designed for reproducing, and the recording / reproducing characteristics are also improved.

FIG. 5 is a block diagram of the positioning control of a conventional magnetic disk device using the recording / reproducing separation head.
3 is a magnetic disk, 8 is a slider, 9 is a voice coil motor (hereinafter referred to as VCM) which is a head moving means for positioning the head on a target track, 4 is an MR amplifier, 11
Is a tracking means and comprises a position error detector 12 and a position control circuit 13. Reference numeral 14 is an access means, which comprises a position detector 15, a speed detector 16, a speed error detector 17 and a speed control circuit 18. Reference numeral 22 is a drive controller that issues a command to switch control signals between tracking and access, 20 is a control signal selector switch that switches control signals according to commands from the drive controller, and 21 is a VCM.
Is a VCM drive circuit for driving the. Reference numeral 23 is a position information recording area on the magnetic disk 3, and 24 is a data information recording area.

The operation of the magnetic disk device configured as described above will be described below. When recording / reproducing information in FIG. 3, the magnetic disk 3, which is a recording medium, is moving in the direction of arrow 7 with respect to the head.
At the time of recording, a recording signal A is sent from the controller, and a current is applied to the induction type magnetic head 1 by the head drive circuit 5,
A magnetic field is generated to record information on the magnetic disk 3. During reproduction, the MR head 2 detects a change in the magnetic field of the magnetic disk 3, and the MR amplifier 4 detects a reproduction signal B.

When recording / reproducing, first, an access operation for moving from the current track to a target track is performed,
When it approaches the target track, it shifts to the tracking state and positions on the target track. After that, the data information is recorded / reproduced in the data information area. When performing such tracking and access operations, position information is recorded in advance on the magnetic disk so that the position of the head on the magnetic disk can be detected. For example, a method is provided in which a position information recording area 23 is provided at regular intervals on a magnetic disk, track numbers are recorded therein, and an access operation is performed based on this information (JP-A-51-1).
31607). The position information recording area 2 is shown in FIG.
3 shows the position information pattern recorded in No. 3. In the position information pattern, a burst part for determining the amplification factor in the position information recording area 23, an erase part where nothing is recorded for identifying the position information recording area, and a track code part in which a track number is coded and recorded. , A position error information section for detecting how much the head is displaced from the track center. FIG. 7 shows a reproduction waveform when the position information recording area 23 is reproduced. The track number is recognized by detecting the track code from the waveform of the track code part. When there is no deviation between the head and the track, the waveform heights of the first half and the latter half of the position error information portion are equal, and when there is a deviation, the waveform heights become unbalanced and the deviation amount can be recognized.

The tracking and access operations will be described below with reference to FIG. At the time of access, the drive controller 22 commands the control signal changeover switch 20 to select the access means 14. The MR head mounted on the slider 8 outputs a reproduction signal from the track code portion of the position information recording area 23 to the MR amplifier 4
By detecting the position of the track by the position detector 15, the average speed between the position information recording areas 23 is obtained by the speed detector 16 and compared with the commanded speed at the current position by the speed error detector 17. The speed error is sent to the speed control circuit 18. The speed control circuit 18 performs necessary compensation for speed control, and issues a speed command to the VCM drive circuit 21 through the control signal changeover switch 20. At this time, the drive controller 22 outputs the output of the speed control circuit 18 to VC.
Control signal changeover switch 2 to send to M drive circuit 21
Switch 0. The VCM drive circuit 21 drives the VCM 9 based on the speed command and moves the head so as to reach the command speed. At this time, the larger the amount of current applied to the VCM 9 is, the larger the force for moving the head becomes, so that a high-speed access operation can be realized.

When performing the tracking operation, the drive controller 22 commands the control signal changeover switch 20 to select the tracking means 11. From the reproduced waveform of the position error information portion of the position information recording area 23, the position error detector 12 obtains a position error indicating how much the MR head deviates from the track. The position error information is compensated by the position control circuit 13 for the position control, and the VC is passed through the control signal changeover switch 20.
A position error command is issued to the M drive circuit 21. At this time, the drive controller 22 switches the control signal changeover switch 20 so as to send the output of the position control circuit 13 to the VCM drive circuit 21. The VCM drive circuit 21 drives the VCM 9 based on the position error command, and moves the slider so that the MR head is located at the center of the track.

[0010]

However, in the above-mentioned structure, since position information is detected by the MR head both during tracking and during access, a bias current for applying an external magnetic field to the MR head is constantly applied. If the current consumption of the entire magnetic disk device is fixed, the current that can be passed to the VCM at the time of access is limited, and there is a problem that high-speed access operation cannot be performed. ..

In view of the above problems, the present invention provides a magnetic disk device which directs a bias current flowing through an MR head at the time of access to a VCM to realize a high speed access operation.

[0012]

In order to solve the above problems, a magnetic disk apparatus of the present invention comprises a rotating magnetic disk, an inductive magnetic head capable of recording or reproducing information on the magnetic disk. A magnetic resistance effect type magnetic head having a reproduction width narrower than that of the induction type magnetic head, a head mounting means for mounting the induction type magnetic head and the magnetoresistive effect type magnetic head on the same center line, and the head mounting means for the magnetic disk. Head moving means for moving in a substantially radial direction, tracking means for positioning to a target track for reading recorded information using the head moving means, and access means for moving to the target track using the head moving means. , The reproduction output of the magnetoresistive magnetic head during tracking, and the inductive magnetic head during access. Those having a head output switching means for switching to use the raw output.

[0013]

According to the present invention, by using the reproduction output of the induction type magnetic head as a position detection signal at the time of access, the current consumed as the bias current of the MR head can be distributed to the current for the access operation. Since this is possible, a faster access operation can be realized.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A magnetic disk device according to an embodiment of the present invention will be described below with reference to the drawings. In addition, the same numbers are used to indicate the same functions as those of the conventional example.

FIG. 2 shows the structure of the recording / reproducing head of the magnetic disk device in the embodiment of the present invention. Figure 2
In the figure, 1 is an inductive magnetic head capable of recording and reproducing, 2 is an MR head, and 3 is a magnetic disk. An MR amplifier 4 supplies a bias current I to the MR head 2 and converts an electric resistance value that changes according to a change in the magnetic field of the magnetic disk 3 into a voltage change for detection. Reference numeral 6 is a reproducing amplifier of the induction type magnetic head 1. The induction type magnetic head 1 and MR
The head 2 is attached to a slider that is a head mounting means. The gap width Tw1 of the inductive magnetic head 1 for recording data information is generally set wider than the gap width Tw2 of the MR head 2 for reproducing data information. In such a head structure, when recording is performed with an induction type magnetic head having a wide gap width and reproduction is performed with a head having a narrow gap width, the information previously recorded is recorded off-track and reproduced. There is an advantage of reducing off-track overwrite noise that causes information recorded on the track to become noise and crosstalk from an adjacent track. The induction type magnetic head 1 is most suitable for recording,
The MR head 2 can be designed optimally for recording and recording.
The reproduction characteristics are also improved. FIG. 1 is a block diagram showing the positioning control of a magnetic disk device according to an embodiment of the present invention.
3 is a magnetic disk, 8 is a slider which is a head mounting means, 9 is a VCM which is a head moving means, and 19 is a reproduction signal changeover switch which is a head output changeover means for switching a head reproduction signal used for control during tracking and access , 11 are tracking means and are composed of a position error detector 12 and a position control circuit 13. Reference numeral 14 is an access means, which is a position detector 15, a speed detector 16, and a speed error detector 1.
7 and speed control circuit 18. Reference numeral 22 is a drive controller for switching a control signal changeover switch 20 and a reproduction signal changeover switch 19 for switching control signals between tracking and access. Reference numeral 21 is a VCM drive circuit. Reference numeral 23 is a position information recording area on the magnetic disk 3, 2
Reference numeral 4 is a data information recording area.

The operation of the magnetic disk device configured as described above will be described below with reference to FIGS. 1 and 2.

In FIG. 2, when recording / reproducing information,
The magnetic disk 3, which is a recording medium, has an arrow mark 7 with respect to the head.
Is moving in the direction of. At the time of recording, a recording signal A is sent from the controller, and a current is applied to the induction type magnetic head 1 by the head drive circuit 5 to generate a magnetic field, and the magnetic disk 3
Record the information in. During reproduction during tracking, the MR head 2 detects a change in the magnetic field of the magnetic disk 3, and M
The reproduced signal B is detected by the R amplifier 4. At the time of reproduction at the time of access, the reproduction signal A is detected by the reproduction amplifier 6 from the voltage induced in the induction type magnetic head 1. Even if the induction type magnetic head 1 is optimally designed for recording information, there are few problems in reproducing position information. This is because the frequency for recording the position information can be set lower than the frequency for recording the data information, and the error probability of the data information is 1
This is because there is no problem even if the error probability of the position information is about 10 −5, as compared with the case where about 0 −9 is required.

The tracking and access operations will be described below with reference to FIG. At the time of access, the drive controller 22 instructs the reproduction signal changeover switch 19 to select the reproduction amplifier 6 and also instructs the control signal changeover switch 20 to select the access means 14. The reproducing signal from the track code portion of the position information recording area 23 is detected by the inductive magnetic head mounted on the slider 8, amplified by the reproducing amplifier 6, and then sent to the access means 14 through the reproducing signal changeover switch 19. The position detector 15 of the access means 14 obtains the position of the track, the speed detector 16 obtains the average speed between the position information recording areas 23, the speed error detector 17 compares it with the commanded speed at the current position, and the speed is calculated. The error is sent to the speed control circuit 18. Speed control circuit 18
Performs necessary compensation for speed control, and issues a speed command to the VCM drive circuit 21 through the control signal changeover switch 20. The VCM drive circuit 21 detects the VCM 9 based on the speed command.
Drive the head to move to the commanded speed.

When performing the tracking operation, the drive controller 22 instructs the reproduction signal changeover switch 19 to select the MR amplifier 4 and the control signal changeover switch 20 with the tracking means 11.
Command to select. The position error detector 12 obtains a position error indicating how much the MR head deviates from the track from the reproduced waveform of the position error information portion of the position information recording area 23 by the MR head mounted on the slider 8. The position error information is compensated by the position control circuit 13 for position control, and a position error command is issued to the VCM drive circuit 21 through the control signal changeover switch 20. At this time, the drive controller 22 switches the control signal changeover switch 20 so as to send the output of the position control circuit 13 to the VCM drive circuit 21. VCM drive circuit 21
Drives the VCM 9 based on the position error command, and moves the slider so that the MR head is located at the center of the track.

As described above, according to this embodiment, the bias current is supplied to the MR head at the time of access by providing the switch for switching to use the output of the inductive magnetic head at the time of access operation and the output of the MR head at the time of tracking. Since the position information can be reproduced without flowing the current, a large amount of current can be supplied to the VCM that moves the slider equipped with the head, and high-speed access operation becomes possible.

In the embodiment, the head output switching means is a reproduction signal changeover switch 1 for selecting a reproduction signal.
However, a switch for switching the operations of the MR amplifier 4 and the regenerative amplifier 6 may be used.

[0022]

As described above, according to the present invention, a rotating magnetic disk, an induction type magnetic head capable of recording or reproducing information on the magnetic disk, and a magnetoresistive effect having a reproduction width narrower than that of the induction type magnetic head. Type magnetic head, head mounting means for mounting the induction type magnetic head and the magnetoresistive effect magnetic head on the same center line, head moving means for moving the head mounting means in a substantially radial direction of the magnetic disk, and Tracking means for positioning to a target track for reading recorded information by using the head moving means, access means for moving to the target track by using the head moving means, and reproduction output of the magnetoresistive magnetic head during tracking. Is switched to use the reproduction output of the inductive magnetic head at the time of access. Head output switching By providing the means, it is possible to enable high-speed access operation.

[Brief description of drawings]

FIG. 1 is a block diagram of a positioning control of a magnetic disk device according to an embodiment of the present invention.

FIG. 2 is a configuration diagram of a recording / reproducing head of the magnetic disk device in the embodiment.

FIG. 3 is a block diagram of a recording / reproducing head of a conventional magnetic disk device.

FIG. 4 is a gap structure diagram of a recording / reproducing head of a conventional magnetic disk device.

FIG. 5 is a positioning control configuration diagram of a conventional magnetic disk device.

FIG. 6 is a positional information pattern diagram of a conventional magnetic disk device.

FIG. 7 is a reproduction waveform diagram of a position information recording area of a conventional magnetic disk device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Induction type magnetic head 2 Magnetoresistive effect type magnetic head 3 Magnetic disk 4 MR amplifier 8 Slider 9 Voice coil motor 12 Position error detector 13 Position control circuit 15 Position detector 18 Speed control circuit 19 Reproduction signal changeover switch 20 Control signal changeover Switch 21 Voice coil motor drive circuit

Claims (1)

[Claims] 1. A rotating magnetic disk, an induction type magnetic head capable of recording or reproducing information on the magnetic disk, a magnetoresistive effect magnetic head reproducing information on the magnetic disk, and the induction type magnetic head. Head mounting means for simultaneously mounting a head and a magnetoresistive effect magnetic head, head moving means for moving the head mounting means in a substantially radial direction of the magnetic disk, and moving to a target track using the head moving means. Access means, tracking means for positioning to a target track for reading recorded information, head output for switching to use the inductive magnetic head reproduction output during access and use the magnetoresistive effect magnetic head reproduction output during tracking A magnetic disk device comprising a switching means.