JPH01154311A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To set a servo band at a higher level so as to shorten the seeking time by increasing the track density by suppressing thermal off-tracks and forming servo information outside a data storing area. CONSTITUTION:Eight magnetic heads are installed to one piece of head slider 1 and the head gaps 18 among the heads are set at nearly 1/8 or wider of the width of the full recording and reproducing area. The eight head gaps 10-17 are independently located to the ABS sections 2-9 of the head slider 1 and the part of the head slider 1 other than the ABS sections 2-9 does not come into contact with a magnetic disk at the time of CSS. Moreover, the head slider 1 is fitted to an actuator by means of a gimbal 19. A material having a coefficient of thermal expansion which is nearer as much as possible to the magnetic disk is used for the head slider 1.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) The present invention relates to a magnetic disk device comprising an fB magnetic disk and a magnetic head for recording and reproducing signals, and particularly relates to a magnetic disk device formed on a magnetic disk. The present invention relates to a magnetic disk device that positions a head on a target data track according to servo information obtained by the user.

(Conventional technology) Conventional magnetic disk devices do not allow The 1tlfla head slider is equipped with a 1vA magnetic head.
This head records and reproduces signals over the entire recording area on one side of the n-air disk.

In order to improve positioning accuracy and track density, this magnetic disk device uses a thermistor that provides track position information in order to follow track wobbling of the data track caused by deformation of the magnetic disk due to changes in temperature and humidity. A method is used in which information is formed on a magnetic disk in advance, and the head is controlled in a closed loop according to this surf information to cause the pressure line to follow the data track. Typical examples include a servo surface servo system that has a dedicated surface for forming servo information for positioning on one surface of the first magnetic disk and a head dedicated to reproducing the servo information; A data surface servo method has been proposed in which the servo information is also read out using a head that records and reproduces data.

A typical data surface servo method is the sector servo method, in which servo information is formed in some of the sectors obtained by dividing the magnetic disk radially, and the servo information is also read out by the head that records and plays data. It is something.

By the way, in the above-mentioned servo surface servo method, a solid servo information reproducing head and multiple data recording/reproducing heads are attached to the same head actuator via a gimbal, but the most problematic is the disk on thermical surface and data surface, head 1 gimbal 1 head actuator
Even if the thermal expansion coefficient of the eta is the same, variations in the temperature distribution depending on the location will cause differences in the amount of shape change, resulting in off-track (thermal off-track). This also causes off-track.

Therefore, in order to overcome these drawbacks, the Shichiritasaza method (data surface servo method) was devised.

Since it has servo + w information as well as data, problems like the above are unlikely to occur.However, with this method, continuous servo information can be obtained because the servo surface servo method can incorporate servo information on the entire surface. Compared to this, the servo information is obtained only intermittently for each sector, so the servo band cannot be increased, the stiffness cannot be increased, and the settling time is longer. Also, each disk m
Since the surfer is applied to each head of I, there is also the disadvantage that processing when switching between heads is more troublesome than the surfer surface surfer e method.

Therefore, a combined servo face-to-face and sector servo system has been proposed as a system that can provide a high thermage band and that does not cause thermal off-track. However, this also results in a low format efficiency due to the increase in the servo information area.
It has the disadvantage that it does.

Also, 111 as before! A head slider with 11 magnetic heads has to move from the innermost periphery of the disk to the outermost periphery of the disk, no matter what type of thermism method is used, and the distance the head seeks is maximum. . In order to achieve high-speed throughput, it is necessary to reduce seek time as well as rotation waiting time. ,
It is.

In order to reduce the seek time by 1f5j, it is effective to reduce the number of seek distance furnaces.
An OB3 disk device with a gimbal attached to one head actuator and the like has been proposed. The two magnetic heads each have recording and reproducing functions on the inner and outer sides of the recording area, and the seek distance is half that of when there is only one head. However, twice as many heads and gimbals are required, the total weight L1 of the movable parts increases, and a proportional effect in shortening the seek time cannot be obtained.

(Point to be solved by the invention) As described above, in the conventional magnetic disk drive in which one magnetic head is provided on one head slider, in the servo surface servo method, the thermal head and Because the data heads are located far apart and are connected through a number of different objects such as gimbals and head actuators, thermal off-track occurs due to variations in temperature distribution depending on the location, and in the sector servo method, Although thermal off-track does not occur, there is a problem in that a high thermium band cannot be achieved.

Furthermore, in these servo systems, since servo information is formed in the same area as the area in which data is recorded and reproduced, the formatting efficiency is worse than in the case of a non-servo positioning system using a stepping motor or the like. If servo information is formed on data to prevent thermal off-track, track density will increase, but format efficiency will decrease, and data format storage will not increase in proportion to track density. .

Furthermore, it has been difficult to effectively shorten the seek time by reducing the seek distance.

Therefore, the present invention has been made in consideration of such circumstances, and aims to suppress thermal off-track. High track density with 1ilJ, improved format efficiency by forming servo information outside the data storage area, narrow servo band by continuously obtaining servo information, effective shortening of seek time, etc. The purpose of the present invention is to provide a magnetic disk g device that can be used.

[Structure of the invention]

(Means for Solving the Problems) In order to achieve the above objects, the present invention has 1! A magnetic head of NM (N is 2 or more qyh>) is installed on the head slider, and the head gap distance between two adjacent heads of the plurality of heads is approximately the width of the entire data recording/reproducing area on the WI disk. l/N or more and smaller than the width of the entire data recording/reproducing area, and each of these N1 head gaps independently corresponds to the A of the head slider.
It is located in the BS (airbearing 5 surface) part, and this OAB S part is located in the N
! l/I is provided, C85 (contact 5ta
rt 5top) sometimes said head slider person BS
The area on the magnetic disk that does not come into contact with the magnetic disk for a period other than i minutes, and where the head located on the inner circumference e of the plurality of magnetic heads provided on the head slider 1 records and reproduces information is usually The area is used even further inside than the area where data is recorded and reproduced, and servo information for head positioning is formed only in this area, and continuous servo information can be obtained from there. Thus, there is provided a magnetic disk device characterized in that the head is positioned in accordance with the continuous thermal information.

(Function) According to the present invention, the thermal off-track, which is the opening angle of the servo face-to-face method, is achieved by the thermal off-track of the slider because the servo head and other data heads are connected only through the slider. If the expansion coefficient is chosen to be the same as that of the magnetic disk, it can be completely suppressed, and off-track due to mechanical misalignment will not occur at all.

In addition, by obtaining continuous surf information, off-track high-frequency components can be obtained, making it possible to increase the servo band, resulting in high soundness, making it resistant to external disturbances, and shortening settling time. .

Furthermore, by forming thermal information further inside the area than the area where normal data is recorded and reproduced, the reduction in format efficiency due to thermal information can be improved.

Furthermore, when a single slider has a large number of heads, the entire servo information area can be formed inside the innermost periphery determined by the maximum linear recording density, and formatting by forming servo information is possible. There is no reduction in efficiency at all.

Furthermore, compared to attaching multiple magnetic heads (head sliders), the slider requires only 1 WA, and if the parts other than AB8 are thinned out, the seek distance can be shortened to 1/N without significantly increasing the weight. , it is possible to effectively shorten the seek time significantly.

(Example) Hereinafter, details of the present invention will be explained based on illustrated embodiments.

FIG. 1 shows a magnetic head according to the present invention, in which 8111! magnetic heads are provided, and these s! The head gap interval 18 between two adjacent heads of the v4c+ head is approximately 178 or more of the width of the entire recording/reproducing area on the magnetic disk, and smaller than the width of the entire recording/reproducing area, and the head gap 18 of these 8!2i to 17 independently represent the head slider 10.
person BS (air bearing surface)
) portions 2 to 9, that is, eight ABS portions are provided on the head slider, and C88 (conta
ct 5 tart 5 top), the portion of the head slider other than the λB8 portion does not come into contact with the magnetic disk. In addition, the head slider 1 is connected via a gimbal 19 to
Attached to the actuator. Here, a head slider l is used whose MI expansion coefficient is as close as possible to that of the magnetic disk.

FIG. 2 shows the magnetic head (slider +8) according to the present invention.
1! The relationship between the head) and the surf information formed on the magnetic disk 20 is shown. There are four magnetic disks 20, that is, eight access surfaces. 8 on the 1111JC) head slider provided for each of these disk surfaces.
The head 10 located at the innermost circumference of the heads having dark heads is a servo-only head that does not record or reproduce data, and its core width is 11 to 1702 times as large as that of the data heads.

The area 21 on the disk accessed by the therme head 10 uses an area further inner than the innermost periphery of the data area determined by the maximum linear recording density of data, and continuous thermal information is stored therein in advance. are written alternately in the entire area. Then, the servo information is read out by the servo-dedicated head, and the head is positioned at a position within the servo area determined based on the servo information.

The data recording and reproducing heads 11 to 17 are formed on the same head slider 1 together with the servo dedicated head 10, and when the therme head is positioned on the track, the corresponding data recording and reproducing area 2
Positioned within 2.

By the way, the signal frequency of servo information is lower than the data recording frequency, and the minimum recording frequency is generally used.
The MFM modulation method uses 12 frequencies.Moreover, as mentioned above, the core width of the servo head is twice as wide as the data head, so 8/N of the servo signal is further inside the area where data is normally recorded and reproduced. Therefore, if all the thermistor information areas are formed inside the innermost periphery determined by the maximum linear recording density of data, there is no reduction in format efficiency due to servo information formation. Furthermore, even if the O servo information area is formed entirely within the data recordable area, the format area at that time is the same as in the case of the so-called therme surface servo system, which has a servo-dedicated surface on one side of the disk.

A thermal pattern as shown in FIG. 3 is formed in advance in the thermal information area, and the signal of the 8YNC area 23 is as follows.
This is a synchronization signal for extracting position information 24. The phase signals output and created by the therme head having a core width twice that of the data head are at two-phase positions A3, X25 and Y26 with a four-track period, as shown in FIG. 4(a).

Therefore, the servo-dedicated head is positioned at the following position for each track (using No. 3 (N is an integer) 4N) rack position signal X (=A-B) 4
N+1) Rack ・Position signal Y (=C-D)4N+
2) Rack ・Position signal -X (=B-A)4N+3)
Rack Fist Position signal - ¥ (=D-C) Switching of the position signal is performed using the fR4 diagram obtained by binarizing each position signal (
This is done by switching the analog switch using the signal shown in b), and the position signal shown in #14 (C) is obtained as a result at the output of the analog switch. Further, the speed of the head can be obtained by differentiating the output of the 11th analog switch.

Positioning control is performed by speed control to move the head at high speed to near the target track and position control to accurately follow the familiar track.

In speed control, in order to move the head efficiently and at high speed, a target speed profile is created in advance according to the distance from the current track to the target track.
Velocity feedback control is applied to the helad actuator to follow the degree of deviation.

When the vehicle reaches a predetermined distance from the target track, control is switched to position control. At this time, the speed is controlled so that the speed becomes almost zero. When switched to position control, the above position signal is used depending on the target orange track. For position control, we set high stability 7ness for the surza loop, apply phase lag compensation to the low range to sufficiently follow the target track without steady errors, and provide sufficient phase margin to ensure stable surza thread. Insert phase lead compensation in series near the Therme band.

Note that the present invention is not limited to the above embodiments,
Various modifications can be made without departing from the gist of the invention.

For example, in the above embodiment, the number of fB air heads is eight, but the seek time is generally as follows: toc m e X/K f- (t: seek time 9 m: total mass of moving parts, X: seek distance, Kf: thrust As shown by the constant, it is proportional to the total mass of the moving parts, the seek distance, and the thrust constant, and the smaller the former two, the shorter the seek time, so the more heads installed on one slider, the better. The larger the number, the shorter the seek distance and seek time. Moreover, as the number of heads increases, the area accessed by one head becomes narrower, so the area used for the thermal information area decreases, and format efficiency improves. In addition, in order to reduce the total mass of moving parts,
Furthermore, if a portion of the slider is made into a skeleton structure, the seek time can be further shortened.

〔Effect of the invention〕

According to the present invention, the problem of thermal off-track, which is a problem with the thermistor surface method, is solved because the thermistor head and other data heads are connected only through the slider. If you choose the same, it will be possible to completely suppress it, and off-track due to mechanical deviation will not occur at all.

In addition, by obtaining continuous therme information, off-track components can be obtained, making it possible to increase the therme band, resulting in high stability and resistance to external disturbances, as well as shortening time. Can be shortened.

Furthermore, by forming the servo information further inside the area than the area where normal data is recorded and reproduced, the decrease in format efficiency due to the servo information can be corrected.

Moreover, when a large number of heads are installed on a 11-piece slider, all of the thermal information areas can be formed inside the innermost periphery determined by the maximum linear recording density, and formatting by forming thermal information is possible. There is no reduction in efficiency at all.

Furthermore, the magnetic head (head slider) is duplicated! l! Compared to the slider III to attach it! Furthermore, if the meat is pierced in areas other than the AB8 portion, the seek distance can be shortened to 17N without significantly increasing the weight, and the seek time can be effectively shortened significantly.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a magnetic head used in an embodiment of the present invention, seen from the back side, and FIG. 2 is a schematic diagram of the structure of the embodiment, and the structure of the magnetic head and the magnetic head. FIG. 3 is a diagram showing the relationship between the alarm recording areas, FIG. 3 is a diagram of the siren pattern formed in the alarm alarm area, and FIG. 4 (a) is a diagram of a signal used as a reference for selection. 1...Head slider, 2-9...AB8 part, 10...Head gap for service, 11-17...Do gap for data, 18...
Head gap interval, 19...To gimbal 20...Magnetic disk, 21...Thermistor information exclusive area, 22...Data recording/reproducing area, 23...8YNC area, 24...Position III# Information, 25...X I1, 26...Y signal. 3rd prisoner

Claims (5)

[Claims] (1) In a magnetic disk device consisting of a plurality of magnetic disks and a plurality of magnetic heads for recording and reproducing signals, one head slider is provided with N magnetic heads (N is an integer of 2 or more), and the plurality of magnetic heads are The head gap interval between adjacent heads is approximately 1/N or more of the width of the entire recording/reproducing area on the disk, and smaller than the width of the entire recording/reproducing area, and each of these N head gaps is independent of each other. and the ABS (air be
1. A magnetic disk device characterized in that N ABS portions are provided on the head slider. (2) Claim 1, characterized in that servo information for head positioning is formed only in one of the areas on the magnetic disk where a plurality of magnetic heads respectively perform recording and reproduction. magnetic disk device. (3) The magnetic disk device according to claim 2, wherein the area on the disk where the servo information is formed is an area corresponding to the magnetic head located at the innermost circumference. (4) The magnetic disk device according to claim 2, wherein the servo information is formed not only in an area where data can be recorded and reproduced, but also in an area on the inner periphery thereof. (5) The magnetic disk device according to claim 2, wherein the servo information obtained from the magnetic disk by the magnetic head is continuous.