JPH05182379A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To realize high recording density by arranging a recording and reproduction separation head opposite to a data face, arranging an induction head with a low sensitivity to a servo face and thereby preventing the servo head from being affected by a write magnetic field. CONSTITUTION:A recording and reproduction separation head 3 in combination with a recording induction head and a reproduction magnetic flux response type head is arranged opposite to a data face 1a and an induction type servo head 4 with a low detection sensitivity is arranged on a servo face 1b. Furthermore, the servo face is arranged on an uppermost face or a lowermost layer or its intermediate part of the device and a track width of a servo head 4 is almost doubled to that of the data head 3. Thus, even when the recording and reproduction separation head is employed for the data head 3, an adverse effect by a write magnetic field of the data head 3 is not caused and the rack width is doubled to improve the S/N of an output signal from the servo head to attain high density recording.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic disk device suitable for large capacity and high speed access, and more particularly to a magnetic disk device using a recording / reproducing separated head for achieving high density recording. Is.

[0002]

2. Description of the Related Art A magnetic disk device is required to have a large capacity, a high speed and a small size, and as a result, the performance is improved year by year. In particular, in addition to the progress of the medium and the head, the improvement of the positioning accuracy of the head and the like have steadily increased the capacity. On the other hand, the access time is also increased by the head positioning control technology. Further, recently, in order to realize higher density recording, a magnetic flux response type head has been put into practical use in place of the induction type head that has been used so far.

Conventionally, a reproducing head and a recording head are also used as a single induction type head, and when the medium moves, the magnetic flux Φ changes according to the change of the recorded magnetization pattern, and as a result, the head is wound. The wire terminals have N × according to the electromagnetic induction law.
A voltage proportional to dΦ / dt is induced, and this becomes a reproduction signal. Here, N is the number of windings. A head that uses Faraday's electromagnetic induction law in this way is called an inductive head. This inductive head does not generate a reproduction signal if the medium is stationary.

On the other hand, in a magnetic disk device, a magnetic flux response type head having a high detection sensitivity is attracting attention in order to perform higher density recording, and an induction type head for recording and a magnetic flux response type head for reproduction are used. The combined read / write head has entered the practical stage. In this recording / reproducing separated type head, a thin film head capable of generating a sharp and strong magnetic field is used as a recording induction type head, and a magnetoresistive head having high detection sensitivity is used as a reproducing magnetic flux response type head. To use. The magnetic flux response type head senses the magnetic flux Φ and generates a reproduction signal.

In order to position the head on a target track at high speed and with high accuracy, a hybrid servo using a dedicated servo surface on which position information is recorded and a data surface on which position information is recorded in addition to data information is used. The method is very effective. With this method, a lot of position information can be utilized by using the servo surface, and high-speed access can be realized. Also, by using the data surface, thermal off-track etc. can be dealt with. It is possible to achieve highly accurate positioning.

[0006]

In order to achieve high-density recording by using the recording / reproducing separated type head described above, it is necessary to strengthen the magnetic field for writing, and the reproducing sensitivity must be high. Is required. However, in a magnetic disk device having a dedicated servo surface, in order to read and write data with the data head, the servo head is always in a reproducing state for reproducing position information, and therefore, the write magnetic field of the data head is However, there arises a problem that the reproduction characteristics of the servo head are adversely affected and the positioning accuracy of the head is deteriorated. As a result, high density recording, that is, increase in capacity cannot be realized.

Further, in order to realize a large capacity, it is necessary to increase the track density, and for this purpose, it is important to improve the S / N of the reproduction signal of the servo head. However, as described above, when the write magnetic field of the data head adversely affects the reproduction characteristics of the servo head, the S / N of the reproduction signal of the servo head deteriorates. From the above, when the recording / reproducing separated type head is used, there is a serious problem that the reproduction signal quality of the servo head is deteriorated.

The present invention has been made in view of the above points,
It is an object of the present invention to provide a magnetic disk device that enables high density recording without adversely affecting the servo head due to the write magnetic field of the recording / reproducing separated type head even when the head is used.

[0009]

In order to achieve the above object, a first magnetic disk drive according to the present invention comprises an inductive head for recording and a magnetic flux responsive head for reproduction, which are opposed to a data surface. A recording / playback separation type head that combines the
It is configured so that an induction type head is arranged for recording and reproduction opposite to the servo surface.

Further, in the first magnetic disk device according to the present invention, preferably, the recording / reproducing separated type head is arranged facing the plurality of data surfaces, and the induction type head is arranged facing one servo surface. Then, the heads are positioned by using the output signals of both heads.

Further, in the first magnetic disk drive according to the present invention, preferably, the track width of the recording / reproducing separated type head facing the data surface is approximately twice the track width of the induction type head facing the servo surface. To be done.

Further, in the first magnetic disk device according to the present invention, preferably, the servo surface is arranged on the uppermost surface or the lowermost surface of the device, or the servo surface is arranged on an intermediate portion of the device and the servo surface is arranged. The servo induction type head and the recording / reproducing separated type head that face each other are not adjacent to each other without a disk interposed therebetween.

Further, in order to achieve the above-mentioned object, the second magnetic disk drive according to the present invention faces the data surface and the servo surface, respectively, and has a recording induction type head and a reproducing magnetic flux response type head. A recording / playback separation type head, which is coupled to and, is arranged, and the servo surface is arranged on the uppermost surface or the lowermost surface of the device, or the servo surface is arranged in the middle part of the device and the recording facing the servo surface is performed. The reproducing / separating head and the recording / reproducing / separating head facing the data surface are configured so as not to be adjacent to each other without interposing a disc,
Furthermore, the track width of the recording / playback separation type head facing the servo surface is approximately doubled the track width of the recording / playback separation type head facing the data surface.

Further, in the first or second magnetic disk device according to the present invention, the reproducing magnetic flux response type head of the recording / reproducing separated type head is constituted by a magnetoresistive type.

[0015]

In the first magnetic disk device according to the present invention, even when the recording / reproducing separated type head is used as the data head,
Since an induction type head having a lower detection sensitivity than the recording / reproducing separated type head is used for the servo head, the head can be positioned by using the output signals of both heads without the servo head being adversely affected by the write magnetic field of the data head. Therefore, high density recording becomes possible.

Further, in the first magnetic disk device according to the present invention, even when the recording / reproducing separated type head is used as the data head, the induction type head whose detection sensitivity is lower than that of the recording / reproducing separated type head is used as the servo head. In addition, by making the track width of the servo head about twice as wide as the data head, the S / N of the output signal from the servo head can be improved and high density recording can be performed.

Further, in the first magnetic disk device according to the present invention, even when the recording / reproducing separated type head is used as the data head, the servo surface is arranged on the uppermost surface or the lowermost surface of the device, or the servo surface is formed. Since the servo induction type head and the recording / reproducing separated type head, which are arranged in the middle part of the device and are opposed to the servo surface, are not adjacent to each other without a disk interposed therebetween, the data head is written. Since the servo head is not affected by the magnetic field, high density recording is possible.

In the second magnetic disk device according to the present invention, even when the recording / reproducing separated type head is used for the data head and the servo head, the servo surface is arranged on the uppermost surface or the lowermost surface of the device, or the servo surface is formed. Is arranged in the middle part of the device, and the recording / reproducing separated type head facing the servo surface and the recording / reproducing separated type head facing the data surface are not adjacent to each other without a disk interposed therebetween. By making the track width of the recording / reproducing separated type head facing the servo surface approximately twice the track width of the recording / reproducing separated type head facing the surface, the servo head is not adversely affected by the write magnetic field of the data head. Therefore, high density recording becomes possible.

Further, in the first or second magnetic disk device according to the present invention, the reproducing magnetic flux response type head of the recording / reproducing separated type head is constituted by the magnetoresistive type, so that the detection sensitivity is increased and the high recording density is achieved. Can be realized.

[0020]

The present invention will be described below with reference to the illustrated embodiments. FIG. 1 is a functional block diagram of essential parts of a magnetic disk device according to a first embodiment of the present invention. As shown in the figure, the magnetic disk device according to the present embodiment includes a spindle motor 2 for rotationally driving a plurality of magnetic disks 1, and writes information on the data surfaces 1a ... Of the plurality of magnetic disks 1. A plurality of data heads 3 for reading information from the data surface 1a, and one dedicated servo surface 1b provided on a specific magnetic disk 1 for moving the data head 3 to a target track position. , A servo head 4 for reading and writing position information on the servo surface 1b, each data head 3, ..., and a carriage 5 for holding the servo head 4 via a supporting member and transferring each head, and driving the carriage 5. Actuator 6 and a head positioning control circuit system for controlling the actuator 6.

In each embodiment of the present invention, in order to position the head on a target track at high speed and with high precision,
A hybrid servo system that uses a dedicated servo surface 1b on which position information is recorded and a data surface 1a on which position information is recorded in addition to data information is adopted, and by detecting each position information, a plurality of The data head 3 ... And the servo head 4 are connected to the actuator 6 via the carriage 5.
Is positioned on the target track. When such a hybrid servo system is adopted, high-speed access can be realized by using the servo surface 1b, and high precision can be realized by using the data surface 1a.

The head positioning control circuit system described above, as shown in FIG. 1, includes a servo surface position detector 7, a data surface position detector 8, band limiters 9 and 10, an adder 11, and
It is composed of a phase compensator 12, a target speed generator 13, a speed detector 14, a subtractor 15, a switch 16, and a power amplifier 17.

In the above structure, in order to position the head on the target track, the speed control is performed and then the position control is performed. In the speed control, the actual speed is detected by the speed detector 14 from the output signals of the servo surface position detector 7 and the data surface position detector 8, and the difference between the detected signal and the output signal of the target speed generator 13 is subtracted by the subtracter 15 To switch 16
Input to the power amplifier 17 via the actuator 5
Is driven. After that, when the target position is approached, the switch 16 switches to a position control loop to position the head. In position control, the output of the servo surface position detector 7 is input to the band limiter 9, and the output of the data surface position detector 8 is input to the band limiter 10, and the outputs of both band limiters 9 and 10 are added. The output signal of the phase compensator 12 is input to the power amplifier 17 via the switch 16, and the actuator 5 is driven to perform head positioning control. .. The band limiter 8 is a high pass filter, and the band limiter 9 is a low pass filter.

In this embodiment, the plurality of data planes 1a ...
As the data heads 3 respectively arranged facing each other, a recording / reproducing separated type head in which a recording inductive type head and a reproducing magnetic flux response type head are combined is used, and the servo surface 1b is used. As the servo head 4 arranged so as to face with, an induction type head that also serves as recording / reproducing is used.

Next, the reproducing magnetic flux response type head of the recording / reproducing separated type head will be described. In each of the embodiments of the present invention, a magnetoresistive head effective for a magnetic disk device is adopted as a reproducing magnetic flux responsive head of a recording / reproducing separated head. The operation principle of this magnetoresistive head is shown in FIG. , FIG. 3 will be described.

As shown in FIG. 2, when the magnetoresistive element 22 is arranged close to the recording medium 21 and a current i is passed through the magnetoresistive element 22, a vertical magnetic field H is generated and magnetized as M. .. As a result, the resistance value of the magnetoresistive element 22 changes, and the terminal voltage changes. Data can be reproduced by using the change in the terminal voltage as a reproduction signal. The characteristic of the magnetoresistive element 22 is a parameter of R = R ₀ + ΔRCOS ² θ,
It is non-linear with respect to θ.

By the way, the magnetoresistive element 22 has a small change in the resistance R in a region where the magnetic field H is weak, that is, in a region where θ is small. Therefore, in order to improve the reproduction sensitivity and linearity, the DC bias H _B is required as shown in FIG. That is, when there is no signal, θ is approximately 45 °
Be biased to become.

FIG. 4 is a diagram showing the basic structure of a magnetoresistive head using a magnetoresistive element (magnetoresistive film). In FIG. 4, 41 is a magnetoresistive film, 42 is a ferromagnetic film, and 43 is a shunt film. , 44 are electrodes, and T _W1 is two electrodes 44, 4
The track width is defined by 4. Here, the ferromagnetic film 4
2 is provided between the magnetoresistive film 41 and the shunt film 43, and is located outside the boundary of the electrodes that define the track width. Although the recording / reproducing separated type head (data head 3) is not shown in the drawing, the induction type head for recording has the same structure as the induction type thin film head arranged facing the servo surface 1b described below. Type thin film head,
The track width is set equal to T _W1 of the magnetoresistive head. The recording / reproducing separated head (data head 3), the recording inductive thin film head, and the reproducing magnetoresistive head are combined and integrated by an appropriate method.

FIG. 5 shows the structure of an induction type thin film head (servo head 4) which is arranged so as to face the servo surface 1b. A lower magnetic layer (not shown), a thin-film coil conductor 52 embedded in an interlayer insulating layer, and an upper magnetic layer 53 are formed on a substrate 51 shown in the figure, and the lower magnetic layer and the upper magnetic layer 53 are on the front side. in constitute the working gap are joined through a gap regulating film having a track width T _W2, are bonded through a hole bored in an interlayer insulating layer in the rear side, thereby the lower magnetic layer and the upper magnetic layer 53 Thus, a closed magnetic circuit interlinking with the thin film coil conductor 52 is formed. In the present embodiment, in order to improve the S / N of the servo head 4, the track width T _W2 of the inductive thin film head (servo head 4) shown in FIG. 5, the track width of the magnetoresistive head described above T _W1 However, it is roughly doubled.

FIG. 6 shows an example of the position information pattern of the servo surface 1b and the position information pattern of the data surface 1a. The servo surface 1b is composed of a mark area, a track information area, a position information area, and a GAP area, and this information is repeatedly written on the track. In the track center, the position information pattern A and the position information pattern B are
This is where the output signals from the position information pattern C and the position information pattern D have the same magnitude. on the other hand,
Servo areas are intermittently written between the data areas on the data surface 1a. The track center is where the output signals from the position information pattern A and the position information pattern B have the same magnitude. In FIG. 6, the track width T _W2 of the servo head 4 is shown as approximately twice the track width T _W1 of the data head 3.

The magnetization reversal interval of the position information patterns on the servo surface 1b and the data surface 1a is generally longer than the magnetization reversal interval of the data information on the data surface 1a.
That is, the head positioning is lower than the frequency for handling data. Therefore, it is possible to use an induction type head for the servo head 4.

As described above, in this embodiment, the recording / reproducing separated type head is arranged so as to face a plurality of data surfaces,
Since the induction type heads are arranged so as to face one servo surface and the head positioning control is performed by using the output signals of both heads, that is, the induction type head having a low detection sensitivity is used as the servo head 4. Therefore, the servo head 4 is not affected by the write magnetic field of the data head 3, and the outputs of the servo head 4 and the data head 3 are used.
The head can be positioned at high speed and with high accuracy. Further, by making the track width of the servo head 4 approximately twice that of the data head 3, the servo head 4
It is possible to improve the S / N ratio of the output signal from, and it is possible to record at a high track density.

Next, second and third embodiments of the present invention will be described with reference to FIGS. 7 and 8. In the second embodiment of the present invention,
In the configuration in which the recording / reproducing separated type head is used as the data head 3 and the induction type head is also used as the servo head 4, the servo surface 1b is arranged on the uppermost surface or the lowermost surface of the apparatus. In FIG. 7, the servo head 4
Shows an example in which the servo surfaces 1b facing each other are arranged on the uppermost surface of the device. With this arrangement, the servo head 4 and the data head 3 are arranged with the magnetic disk 1 interposed therebetween, and the servo head 4 can avoid the write magnetic field from the data head 3.

In the third embodiment of the present invention, the data head 3
In the configuration in which the recording / reproducing separated type head described above is used and the induction type head is also used as the servo head 4, FIG.
As shown in, the servo surface 1b facing the servo head 4 is arranged in the center of the apparatus, and the data head 3 is not arranged on the back surface of the servo head 4. That is, the servo head 4 and the data head 3 facing the servo surface 1b arranged at the center of the device are configured so as not to be adjacent to each other without the magnetic disk 1 interposed therebetween. Also by doing so, the servo head 4 can avoid the write magnetic field from the data head 3.

Next, a fourth embodiment of the present invention will be described with reference to FIG. In the fourth embodiment of the present invention, the recording / reproducing separated type head is used for the data head 3 as described above, and the recording / reproducing separated type head is also used for the servo head 4 '. In the fourth embodiment, the servo surface 1b facing the servo head 4'is arranged on the uppermost surface or the lowermost surface of the apparatus, or the servo surface 1b facing the servo head 4'is arranged in the center of the apparatus. The data head 3 is not arranged on the back surface of the servo head 4 '(the servo head 4'and the data head 3 are not adjacent to each other without the magnetic disk 1 interposed therebetween). Note that FIG. 9 shows an example in which the servo surface 1b is arranged on the uppermost surface. By arranging in this way, the servo head 4 ′ can avoid the write magnetic field from the data head 3. Further, if the track width of the servo head 4'is approximately twice as wide as the track width of the data head 3, the S / N of the output of the servo head 4'is improved, which is more effective.

In the magnetic disk device described above,
By using it as an external storage device of an information processing device such as a workstation, it becomes possible to handle a large amount of data at high speed.

[0037]

As described above, according to the present invention, when a recording / reproducing separated type head is used as the data head in order to realize a large capacity, that is, a high recording density, the write magnetic field of the head causes It is possible to provide a magnetic disk device capable of achieving high recording density without the servo head being adversely affected by noise or the like.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a main configuration of a magnetic disk device according to a first embodiment of the invention.

FIG. 2 is an explanatory diagram showing an operating principle of a magnetoresistive element.

FIG. 3 is an explanatory diagram showing a relationship between a magnetic field and a resistance change of a magnetoresistive element.

FIG. 4 is an explanatory diagram showing an example of a magnetoresistive head for reproduction of a recording / reproducing separated type head (data head) used in the first embodiment of the present invention.

FIG. 5 is an explanatory diagram showing an example of an induction type thin film head which is a servo head used in the first embodiment of the present invention.

FIG. 6 is an explanatory diagram showing an example of position information patterns on a servo surface and a data surface.

FIG. 7 is an explanatory diagram showing a main configuration of a magnetic disk device according to a second embodiment of the invention.

FIG. 8 is an explanatory diagram showing a main configuration of a magnetic disk device according to a third embodiment of the invention.

FIG. 9 is an explanatory diagram showing a main configuration of a magnetic disk device according to a fourth embodiment of the invention.

[Explanation of symbols]

 1 magnetic disk 1a data surface 1b servo surface 2 spindle motor 3 data head 4, 4'servo head 5 carriage 6 actuator

Claims (8)

[Claims] 1. A magnetic disk device having a data surface and a servo surface for head positioning, wherein an inductive head for recording and a magnetic flux response head for reproduction are coupled to face the data surface. A magnetic disk drive, wherein the recording / reproducing separated type head is arranged, and an induction type head for recording and reproducing is arranged facing the servo surface. 2. The recording / reproducing separated type head is arranged so as to face a plurality of data surfaces, and the servo induction type head is arranged so as to face a servo surface. A magnetic disk device characterized in that the head is positioned by using the output signals of the servo induction type head and the recording / reproducing separated type head. 3. The track width of the recording / reproducing separated type head facing the data surface is approximately 2 times the track width of the servo induction type head facing the servo surface. A magnetic disk device characterized by being doubled. 4. The servo surface according to claim 1, wherein the servo surface is arranged on the uppermost surface or the lowermost surface of the apparatus, or the servo surface is arranged on an intermediate portion of the apparatus and faces the servo surface. A magnetic disk device characterized in that the induction type head for servo and the recording / reproducing separated type head are not adjacent to each other without a disk interposed therebetween. 5. A magnetic disk device comprising a data surface and a servo surface for head positioning, wherein an inductive head for recording and a magnetic flux response for reproduction are provided facing the data surface and the servo surface, respectively. A recording / reproducing separated type head coupled with a mold head is provided, and the servo surface is arranged on the uppermost surface or the lowermost surface of the device, or the servo surface is arranged at an intermediate part of the device and the servo surface is arranged. 2. The magnetic disk apparatus, wherein the recording / reproducing separated type head facing the data surface and the recording / reproducing separated type head facing the data surface are not adjacent to each other without a disk. 6. The track width of the recording / playback separation type head facing the servo surface is approximately twice the track width of the recording / playback separation type head facing the data surface. Characteristic magnetic disk device. 7. The magnetic disk device according to claim 1, wherein the reproducing magnetic flux response type head of the recording / reproducing separated type head is of a magnetoresistive type. 8. The method according to any one of claims 1 to 7,
The magnetic disk device according to any one of items 1 to 7 is used in an information processing system for processing information.