JP3265778B2 - Magnetic disk drive - Google Patents

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 equipped with a composite head for recording signals with an inductive magnetic head and reproducing signals with a magnetoresistive magnetic head.

[0002]

2. Description of the Related Art Conventionally, in order to prevent signal interference between adjacent tracks, a magnetic disk drive is disclosed in
As described in Japanese Patent No. 226509, an area where no signal is recorded and a guard band are provided between tracks.

[0003]

In the prior art described above, as the track density increases in the future, the track width of the inductive write head must be reduced, which limits the improvement of the track density. As the track becomes narrower, an inductive write head cannot generate a magnetic field sufficient to write a signal on a recording medium. Further, it is known that a demagnetization head that erases a signal recorded on a magnetic recording medium other than during a write operation is likely to occur.

[0004]

SUMMARY OF THE INVENTION The present invention provides a magnetic disk drive having a composite head comprising an inductive write head for recording signals on a magnetic recording medium and a magnetoresistive read head for reproducing recorded signals. In FIG. 6, the optical track width (Tww) 2, which is the physical length of the upper magnetic film 12 of the induction type write head and the lower magnetic film 15 also serving as the upper shield film, is larger than the track pitch. The above-mentioned problem is solved by performing the recording or by overlapping the ends of the adjacent data tracks. At this time, the optical track width (Tw
w) The relationship between 2 and the optical track width (Twr) 19 determined by the physical spacing between the electrodes 18 of the magnetoresistive read head is such that the composite track with Tww> Twr allows the track end to overlap. The recorded portion is not reproduced, and a decrease in S / N (signal-to-noise ratio) due to crosstalk of an adjacent track or a decrease in resolution does not occur.

[0005]

When the track width of an inductive write head is reduced as the track pitch becomes smaller,
A magnetic field sufficient to write a signal on the recording medium cannot be obtained. Also, as described above, it is known that an inductive write head tends to become a demagnetizing head that erases a signal recorded on a magnetic recording medium other than during a write operation as the track becomes narrower. . According to the present invention, an inductive write head having stable characteristics can be obtained by making the track width of the inductive write head wider than the track pitch.

[0006]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG. In the conventional magnetic disk device, as shown in FIG. 2, an area called a guard band 5 is provided in adjacent tracks 4 so that signals do not interfere with each other. Therefore, an optical track width (Tww) 2 which is a physical length obtained by measuring the track width of the leading end 1 of the inductive write head by an optical method, and a track pitch (Tp) 3 determined by the track density of the magnetic disk drive are: , Tww <T
p. On the other hand, in the magnetic disk drive according to the embodiment of the present invention shown in FIG. 1, the optical track width (Tw) is obtained in order to obtain an inductive write head having stable characteristics.
w) 2 is sufficiently larger (for example, 4 μm or more) than the domain wall width (about 1 μm), the track density is 6.35 kTPI or more,
The relationship between the optical track width (Tww) 2 and the track pitch (Tp) 3 of the magnetic disk is such that Tww> Tp. At this time, adjacent track ends are overwritten.

An embodiment of a head structure for realizing this will be described with reference to a perspective view shown in FIG. 5 and a floating surface view shown in FIG. Inductive write head 11 for recording a signal on a medium
Are an upper magnetic film 12 and an upper shield / lower magnetic film 1
5, and further, a conductor coil 13. A magnetoresistive read head 14 for reproducing a signal from a medium has an upper sheath.
It comprises a shield film 15, a lower shield film 16, and a magnetoresistive element 17 and an electrode 18 interposed therebetween. Optical write track width (Tww) 2 of the induction type write head 11
And an optical read track width (Twr) 19 determined by the distance between the electrodes 18 of the magnetoresistive read head 14,
There is a relationship Tww> Twr, and the overwritten portion is not reproduced. Thus, the optical write track width (Tww) 2 of the inductive write head 11 and the optical read track width (Twr) of the magnetoresistive read head 14 are obtained.
19, and the track pitch (Tp) 3 is Tww +
The relationship of Twr ≦ 2 × Tp holds.

The definition of the effective write track width Twref and the effective read track width Twref for magnetic recording will be described with reference to FIG. FIG. 7 shows a composite head comprising an inductive write head for recording signals on a magnetic recording medium to which the present invention is applied and a magnetoresistive read head for reproducing recorded signals, and writing on a magnetic recording medium. 4 shows the relationship between the signal for one track and the output Eout of the read head when the composite head moves in the track width direction.

A signal having a minimum linear recording density (longest wavelength) of the apparatus is recorded on a recording medium used in the apparatus of this embodiment by an inductive write head 11. Next, the magnetoresistive read head 14 is moved in the track width direction r over the recorded signal to reproduce the signal. Based on the obtained off-track profile, a width Twref that is actually recorded on the recording medium by the write head and a width Twref that enables the read head to obtain an effective sensitivity for reproduction output are defined. In this embodiment, the half width of the profile is Twweff, and the width of the point where the tangent of the profile intersects the output 0 or the maximum value is Twrefff.
Becomes Compared to the optical track widths Tww and Twr, the effective magnetic recording track width Tw defined by FIG.
If weff and Twref are slightly larger or smaller depending on the track end shape of the write head and the magnetic domain control method of the read head, or the recording frequency, etc., the optical track width is such that the relationship Twweff + Twref ≦ 2 × Tp is established. Tww and Twr are determined.

Next, an embodiment of a rotary-actuator type magnetic disk drive will be described with reference to FIGS. Since the head moves to the target track centering on the pivot position 20, in the rotary actuator type, the YAW angle, which is the inclination of the track 6 of the induction type write head with respect to the circumferential tangent 9 of the magnetic disk 7, depends on the radial position. 8 is different. Inner circumference YAW angle 0 °, outermost circumference Y
FIG. 3 shows an example of an AW angle of 20 °. When the YAW angle 8 is θ, the write track width Twy is Twy = Tww × COSθ.
Becomes When the track pitch (Tp) is uniform in the circumferential direction, Twy> Tp must be satisfied at least at the innermost radius position where the YAW angle θ is minimum. As shown in FIG. 4, the track pitch (Tp) 3 in the circumferential direction is
Also, for example, when the track pitch (Tp1) 10 is Tp1
= Tp × COSθ, Twy> Tp1 can be satisfied in all tracks, and a high track density can be achieved.

Although the present embodiment has been described with respect to the combined head of the shield and combined type, the present invention has the same effect in the case of the separated type, in-gap type, yoke type and flux guide type composite head. . The same applies to a magnetic disk device of a linear type actuator.

[0012]

As described above, according to the present invention, a high track density can be achieved by making the optical write track width larger than the track pitch. Also, Tww> T
By using the composite head of wr, there is an effect that a decrease in S / N (signal to noise ratio) due to crosstalk of an adjacent track or a decrease in resolution is not caused.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram showing features of a magnetic disk drive according to the present invention.

FIG. 2 is an explanatory diagram of a conventional magnetic disk drive.

FIG. 3 is an explanatory diagram of one embodiment of a magnetic disk device of a rotary actuator.

FIG. 4 is an explanatory diagram of one embodiment of a magnetic disk device of a rotary actuator.

FIG. 5 is a perspective view of one embodiment of a composite head used in the present invention.

FIG. 6 is a floating surface view of an embodiment of the composite head used in the present invention.

FIG. 7 is an explanatory diagram of a definition of an effective track width for magnetic recording.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Top end of write head 2 Optical write track width 3 Track pitch 4 Track 5 Guard band 6 Write head track part 7 Magnetic disk 8 YAW angle 9 Tangent line of magnetic disk circumference 10 Track pitch 11 Inductive write head 12 Upper magnetic film 13 Conductor coil 14 Magnetoresistive read head 15 Upper magnetic film also serving as lower magnetic film 16 Lower shield 17 Magnetoresistive element 18 Electrode 19 Optical lead track width 20 Pivot position

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Masayuki Takagi 2880 Kozu, Kodawara-shi, Kanagawa Prefecture Hitachi, Ltd. Storage System Division (72) Inventor Tetsuji Kameoka 2880 Kozu, Kozu, Odawara-shi, Kanagawa Prefecture Storage System Hitachi, Ltd. Within the Business Unit (72) Inventor Naoki Koyama 2880 Kozu, Kodahara, Kanagawa Prefecture Hitachi, Ltd.Storage System Business Unit (72) Inventor Shobun Miyamoto 2880 Kozu, Kozu, Odawara City, Kanagawa Prefecture Hitachi, Ltd.Storage System Business Unit (72) Inventor Toshiaki Tsuyoshi 2880 Kozu, Odawara-shi, Kanagawa Pref. Hitachi, Ltd. Storage Systems Division (56) References JP-A-6-318302 (JP, A) (58) Fields investigated (Int. Cl. ^7, DB ) G11B 5/39

Claims (2)

(57) [Claims] An inductive write head for recording a signal on a magnetic recording medium and a magnetoresistive read head for reproducing a recorded signal, wherein an optical track width of the inductive write head is a track pitch. When the optical track width of the inductive write head is defined as Tww, the optical track width of the magnetoresistive read head is defined as Twr, and the track pitch is defined as Tp, Tw + Twr ≦ 2 × Tp A magnetic disk device satisfying the following relationship: 2. An inductive write head for recording a signal on a magnetic recording medium, and a magnetoresistive read head for reproducing a recorded signal, wherein an optical track width of the inductive write head is a track pitch. In a larger magnetic disk device, the effective recording magnetic track width of the inductive write head is Twweff, and the effective magnetic recording track width of the magnetoresistive read head is Twrefff.
And when the track pitch is defined as Tp, Twwe
A magnetic disk device satisfying a relationship of ff + Twref ≦ 2 × Tp.