JPS6288106A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To raise the positioning accuracy by providing a magnetic head having a transducer for servo having a gap of a yoke in the radial direction of a magnetic double layer disk, and a transducer for data having a gap in the peripheral direction. CONSTITUTION:A servo-pattern which is orthogonal to a data signal magnetizing direction of a data layer 11 and sets one track pitch as a magnetizing inversion interval in the radial direction of a magnetic double layer disk 1 is recorded in a servo-layer 12 of the disk 1. A magnetic head 2 is provided with a transducer 15 for servo and a transducer 16 for data. The transducer 15 is constituted of a magneto-resistance effect element 17 having a gap 19 of a yoke 18 in the radial direction of the disk 1, and the transducer 16 is constituted of an induction type having a gap in the peripheral direction of the disk 1. In this way, the track positioning accuracy is improved, and also a stable servo can be executed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a magnetic disk device, and more particularly to a servo pattern, a reproducing head, and a reproducing method in a buried servo method.

(Prior technology) Conventionally, the servo surface servo method has been the mainstream for magnetic disk drives, but in this servo surface servo method, the servo disk and data disk are placed on separate magnetic disk plates; In this method, a servo signal is reproduced by a servo magnetic head, and the data magnetic head is positioned to a data track of another magnetic disk using the servo signal.

Also, in recent magnetic disk drives, various data surface servo methods are being considered to improve head positioning accuracy, but in particular, data surface servo methods include a sector servo method that uses part of the data surface, and a sector servo method that uses a part of the data surface. A buried servo method that uses a magnetic double layer disk, uses the lower magnetic film as a servo information medium, and uses the information is under consideration.

(Problems to be Solved by the Invention) In the servo surface servo method, the servo magnetic head and the data magnetic head are placed on separate magnetic disk plates, so the magnetic head positioning accuracy may be affected due to the difference in ambient temperature. There was a risk of deterioration. In particular, the servo surface servo system has problems such as the positioning error of the magnetic head increases as the track density increases, making it difficult to increase the track density and thus making it difficult to realize a high recording density.

Next (This sector servo method divides one track into sectors and partially inserts servo information, but it has the problem that track servo is not possible except for the part where servo information is input. Therefore, head positioning accuracy is insufficient at high track densities.

Furthermore, the servo system that uses the data information itself as servo information has the problem of causing a head positioning error when the output envelope of the data information fluctuates because the data information itself is used.

In addition, the servo method that uses a magnetic double layer disk uses the upper layer for data information and the lower layer for servo information. Data and servo information are detected simultaneously by one data head, and positioning is performed because they are used separately. The error is small. However, in the buried servo method using this magnetic double layer medium, when data information and servo information are simultaneously detected by one data magnetic head, separation of data information and servo information during reproduction is easily performed by a filter. When recording, a filter and a bias circuit are required in the recording circuit to detect the servo information, resulting in a fairly complex circuit configuration, and the servo information S/
This has the problem of not only deteriorating N (signal-to-noise ratio) but also increasing the cost of the circuit system. To solve this problem, as a thin-film magnetic head for buried servo method, a data transducer is placed on one of the two rails of the same slider, and a servo transducer is placed on the other rail. There is a method of separating users and preventing deterioration of S/N during recording.

In this ηC buried servo system, as shown in Figure 4, the data signal and servo signal information are recorded in the same direction, so the servo or data magnetic head reproduces both the data and servo signals, respectively. However, there are problems in that mutual interference is likely to occur and margins for parameters of the disk head system are restricted.

An object of the present invention is to provide a magnetic disk device that eliminates the above-mentioned problems.

(Means for Solving the Problems) The present invention provides a magnetic disk device having a magnetic double layer disk, in which the servo layer of the magnetic double layer disk is provided with one track pitch in the radial direction of the disk, perpendicular to the magnetization direction of the data signal. A magnetic double-layer disk having a servo pattern recorded as a magnetization reversal interval, a servo transducer of a magnetoresistive element with a yoke having a yoke gap in the radial direction of the disk, and an inductor having a circumferential gap. This is a magnetic disk device including a magnetic head having a data transducer of the type shown in FIG.

(Function) The magnetic disk device according to the present invention uses a magnetic double layer disk, and the servo signal magnetization direction recorded on the servo layer of the magnetic disk is orthogonal to the data signal magnetization direction,
The servo signal is recorded in the radial direction so that the magnetization reversal interval of the servo signal magnetization is one track pitch, and during reproduction, the servo transducer has a yoke magnetoresistive element with a yoke gap in the radial direction. In this method, a user and a data transducer having a gap in the circumferential direction are arranged on the same slider using a magnetic head to reproduce the servo signal and position the magnetic head. In this case, the servo transducer reproduces only the servo signal because the magnetization directions of the servo signal and the data signal are orthogonal, and the servo signal itself becomes a positioning error signal (hereinafter referred to as the PE8 signal), so it is reproduced. The zero-crossing point of the servo signal is the point at which the head is positioned.

A data transducer and a servo transducer mounted on the same slider reproduce changes in magnetic flux in the circumferential direction and magnetic flux in the radial direction of the magnetic double layer disk, respectively.

In this way, a magnetic head having a data transducer and a servo transducer mounted on the same slider is reproduced by the servo transducer, amplified by the servo amplifier, and processed by the servo control circuit. Since it is connected to a motor (voice coil motor, DC servo motor) that is controlled by signals,
Track positioning of the magnetic head is performed using servo signals on the same disk surface and the same magnetic head slider. Therefore, since the servo transducer and the data transducer are on the same slider, the ambient temperature is the same, and since a magnetic double layer disk is used, track servo can be performed at all times, and the servo signal The envelope is constant and stable, and the data signal and servo signal operate so as not to interfere with each other.
Trunk positioning accuracy is greatly improved. Embodiments of the present invention will be specifically described below with reference to the drawings.

(Embodiment) FIG. 1 is a configuration diagram of an embodiment of a magnetic disk device of the present invention. 2 shows the cross section of the magnetic double layer disk l shown in FIG. 1 and the magnetization states of data signals and servo signals, and FIG. 3 shows the structure of the magnetic head 2 shown in FIG. 1. show.

As shown in FIGS. 1, 2, and 3, the present invention has a coercive force HC.
-13000e, servo layer 12 with film thickness t = 0.3 μm and coercive force Hc -6000e, film thickness L = 0.05 am
a magnetic double layer disk 1 having a data layer 11 of
A magnetic herad 2 was used which had a servo transducer 15 of a magnetoresistive element 17 (permalloy) and an induction type data transducer 16 having a gap of 0.3 μm in the circumferential direction. The servo signal magnetization 30 is 5 μm in the radial direction of the servo layer 12 of the magnetic double disk 1.
The track pitch was previously recorded as the magnetization transition interval, and the data signal magnetization 31 was recorded and reproduced in the circumferential direction at a linear density of 30,000 BPI (bit density per inch) as in the conventional example. Using the magnetic double layer disk 1 and the magnetic head 2, the magnetic flux generated from the servo signal magnetized in the radial direction of the magnetic double layer disk 1 is reproduced by the servo transducer 15, and the magnetic flux of the servo transducer 15 is reproduced. The reproduction output of the resistance effect element 17 is input to the servo amplifier 3, the output of the servo amplifier is input to the servo control circuit 4, and the output of the servo control circuit 4 controls the motor 5 (in this embodiment, the voice coil motor). was used) to position the magnetic head 2 coupled to the motor 5 on the track. After the track positioning of the magnetic head 2 is performed, the data signal processing circuit system 7, the data amplifier 6, and the data transducer 16 having a gap in the circumferential direction of the magnetic head 2 are used to position the data layer 11 in the circumferential direction. Data was recorded and reproduced at a recording density of 30,000 BPI.

(Effect of the invention) As described above, the servo signal magnetization and the data signal magnetization are made orthogonal, and the servo signal is further reproduced in the radial direction (by a servo transducer of a magnetoresistive effect element having a gap between the yoke and the servo signal). Detects the magnetic flux generated from magnetization,
Since data signals are recorded and reproduced using an inductive data transducer with a gap in the circumferential direction, there is almost no interference between servo signals and data signals, and conventional servo signal magnetization and data signal magnetization are in the same direction. Compared to the case (FIG. 4), the track positioning accuracy of the magnetic head was improved twice. Since the servo transducer and the data transducer are mounted on the same slider, there is no difference in ambient temperature on the same disk surface, and since a magnetic double layer is used, the servo signal is constantly transmitted. was detected and track servo was performed, and the servo signal was stable with a constant output.

[Brief explanation of drawings]

FIG. 1 is a configuration diagram showing an embodiment of a magnetic disk device of the present invention, FIG. 2 is a cross section of a magnetic double layer disk and the magnetization states of data signals and servo signals, and FIG. 3 is a structural diagram of a magnetic head. FIG. 4 is a diagram showing a conventional example. 1, 2, and 3, 1 is a magnetic double layer disk, 2 is a magnetic head, 3 is a servo amplifier, 4 is a servo control circuit, 5 is a motor, 6 is a data amplifier, and 7 is a Data signal processing circuit system, 8°9.10 is data track n, n+1. n+2 tracks, 11 is a data layer, 12 is a servo layer, 13 is a slider, 14 is a gimbal, 15 is a servo transducer, 16 is a data transducer, 17 is a magnetoresistive element, 18 is a yoke, 19 is Gap, 30 is servo signal magnetization, 31 is data signal magnetization, 32 is hold! ! 33 is a data/servo separation layer, and 34 is a nonmagnetic substrate. In FIG. 4, 20, 21, 22, and 23 are data tracks Ωl'``L'' 2+Ω+3 tracks, 24 is data signal magnetization, and 25 is servo signal magnetization. 3: n track 74;

Claims (1)

[Claims] In a magnetic disk device having a magnetic double layer disk, a magnetic disk having a servo pattern recorded on a servo layer of the magnetic double layer disk orthogonally to the data signal magnetization direction in the radial direction of the disk with a magnetization reversal interval of one track pitch. A magnetic head having a double layer disk, a servo transducer of a magnetoresistive element with a yoke having a yoke gap in the radial direction of the magnetic double layer disk, and an induction type data transducer having a gap in the circumferential direction of the disk. A magnetic disk device comprising: