JPH03225616A - Magnetic disk device - Google Patents

Abstract

PURPOSE:To eliminate trouble to be caused by leaked magnetic flux and to miniatwrize the device by canceling crosstalk noise from a magnetic head for recording and reproducing while outputting the outputs of a main head assembly and a sub head assembly in mutually inverting their phases. CONSTITUTION:A main head assembly 6 is composed of a gap 6a, coil 6b and a pair of electrodes 7c and 7d for drawing the coil, and a sub head assembly 7 is composed of a coil 7b and a pair of electrodes 7c and 7d for drawing the coil. The coils 6b and 7b are wound and formed in the same direction, th electrodes 6c and 7c are respectively defined as the winding start of the coils 6b and 7b and the electrodes 6d and 7d are defined as the winding end. For a thin film magnetic head 4 for servo to be used for this magnetic head device, a head assembly not to be used or unusable generally is used as the sub head assembly 7, and therefore, a metallic material is applied to the gap part so as to lose gap function. Thus, the crosstalk is canceled while inverting the phases of the outputs from the assemblies 6 and 7 each other.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a magnetic disk device having a magnetic head for recording/reproducing and a magnetic head for servo, and particularly relates to a magnetic disk device having a magnetic head for recording/reproducing and a magnetic head for servo. This is a significant reduction in talk.

[Prior Art] Conventionally, as shown in FIG. 3, a large-capacity magnetic disk device has a plurality of magnetic disks 21, which are magnetic recording media, coaxially stacked at regular intervals, and information is recorded on the disk surface. A plurality of magnetic heads 22 for writing and reading are provided. 23 is an actuator for moving the magnetic head.

As mentioned above, the narrow stacking spacing of magnetic disks
As shown in FIG. 4, two magnetic heads 22a, 22b
are located adjacent to each other. When a recording current is passed through the recording/reproducing coil 24a of the magnetic head 22a, a magnetic flux 25a is generated. This magnetic flux 25a flows through the magnetic circuit 26a, but some of it leaks from places where the magnetic flux easily leaks, such as various parts of the core, and becomes a magnetic flux that flows through the magnetic circuit 26a of the adjacent magnetic head 22b.
6b, and the coil 24b causes harmful effects such as electromagnetic coupling between the coils.

This problem is particularly noticeable between two adjacent magnetic heads that operate simultaneously, such as a servo magnetic head and a recording/reproducing magnetic head.

There is a magnetic head described in Japanese Patent Application Laid-open No. 78104/1983 which eliminates the above-mentioned disadvantages of electromagnetic coupling between coils.

In FIG. 5, 31 is a data recording/reproducing magnetic head (
32 is a recording/reproducing coil, 33 is a magnetic core gap, 34, 35 is a magnetic disk, 36 is a servo magnetic head (servo head), and 37 is a coil of the servo head 36.

Both heads are aligned in the central axis direction of the coil 32 of the data head 31 and the coil 3 of the servo head 36 installed adjacently.
7 is installed in a different direction from the central axis direction. With this arrangement, the servo head 3 due to leakage magnetic flux
Since the induced electromotive force in the magnetic head 6 is low, noise is reduced, and the electromagnetic heads are installed adjacent to each other, thereby reducing the size of the magnetic disk device.

[Problems to be Solved by the Invention] However, the conventional magnetic head shown in FIG. 5 has the following problems (a) to (1).

(a) Since it is necessary to align the central axes of multiple data heads 31 and install the servo head 36 at an offset position with respect to this central axis, it is necessary to install a small HDA (head disk assembly) of 3.5 inches or less. However, such a configuration is extremely difficult to install due to accuracy.

(a) Since the data head 31 and the servo head 36 have a core and a slider made of ferrite, complex electromagnetic induction noise is generated compared to when the coil 32 or the coil 37 is present alone, and the crosstalk is insufficient. Unable to reduce talk.

(1) Since at least one of the coils 32 and 37 of the data head 31 and the servo head 36 is far from the gap, the recording and reproducing efficiency decreases.

(1) An offset between the data head 31 and the servo head 36 (indicated by a in the figure) by one or two degrees is required, resulting in a loss of recording area of several tens of tracks.

Furthermore, in order to reduce crosstalk, it has been conventionally practiced to arrange a shield plate. However, it is necessary to use a ferrite material as the shield plate, which increases the cost and prevents downsizing of the device.

Furthermore, in order to minimize crosstalk, it has been conventionally practiced to provide a servo head at the top position (the topmost magnetic disk) or the bottom position (the bottommost magnetic disk). However, as the number of magnetic disks increases, thermal off-track cannot be ignored, and the servo head must be placed at its center position (the center position of a plurality of magnetic disks), which makes it impossible to employ this method.

[Means for Solving the Problems] In order to solve the above problems, the present invention provides a magnetic disk in which a data surface and a servo surface are formed, and a recording and reproducing method for recording and reproducing data on the data surface of the magnetic disk. A servo for reproducing servo signals from the servo surface of the magnetic disk, in which a main head assembly having a magnetic head for reproducing servo signals, a main head assembly having a gap and a coil for reproducing servo signals, and a sub-head assembly having only a coil are formed as thin films adjacent to each other. The present invention provides a magnetic disk drive comprising a thin-film magnetic head for use in magnetic disks, in which the coil of the main head assembly and the coil of the sub-head assembly are connected in reverse phase, and the output of the reverse phase connection is used as a servo reproduction signal. .

[Operation] In the above magnetic disk device, crosstalk noise (electromagnetic induction noise) from the recording/reproducing magnetic head is canceled by being output from the main head assembly and the sub head assembly in opposite phases.

[Embodiment] An embodiment of the magnetic disk device according to the present invention will be described in detail below with reference to the drawings. FIG. 1 is a side view showing the main parts of a magnetic disk drive, and FIG. 2 is a perspective view showing a thin film magnetic head for a subwoofer.

In this magnetic disk device, a plurality of magnetic disks (for example, five disks) are rotatably arranged on the same axis as shown in FIG. is provided. However, the surface (2a) of the magnetic disk (2) placed in the center (for example, the third disk if it consists of five magnetic disks) is a servo surface, and the pre-warning servo signal is recorded on it. ing. As will be described in detail later, the magnetic head on the servo surface is composed of a servo thin film magnetic head (4), and the output of this servo thin film magnetic head (4) is the servo reproduction output. The actuator for moving the magnetic head operates in response to this servo reproduction output, and the plurality of recording/reproducing magnetic heads and the servo thin film magnetic head (4) are integrally transported.

FIG. 1 is a diagram showing the relationship between a servo thin film magnetic head and a recording/reproducing head adjacent to this head.

In the figure, reference numerals 1 and 2 are magnetic disks; both sides of the magnetic disk 1], a, lb, and the back side 2 of the magnetic disk 2.
b is the data surface. Desired information (data) is recorded and reproduced on this data surface by a recording/reproducing magnetic head 3 (only the head for the data surface 1b is shown). The recording/reproducing magnetic head 3 has a gap 3 a s coil 3
b, consisting of core 3C. As described above, the surface 2a of the magnetic disk 2 disposed at the center is a servo surface, and the servo thin film magnetic head 4 is disposed on this servo surface.

As shown in FIG. 2, the servo thin-film magnetic head 4 has a main head assembly 6 and a sub-head assembly 7 formed as thin films on one side 5a of a slider 5 made of ferrite.

The main head assembly 6 consists of a gap 6a, a (printed) coil 6b, and a pair of electrodes 6c and 6d for extracting the coil. The sub head assembly 7 is a (printed) coil 7
b, and a pair of electrodes 7c and 7d for drawing out the coil. The coil 6b and the coil 7b are wound in the same direction (for example, clockwise), and the electrode 6C and the electrode 7
C and the winding of each coil 6b and 7b has started,
Coils 6b for electrodes 6d and 7d.

This is the end of winding 7b.

The servo thin film magnetic head (4) shown in FIG.
It is extremely difficult to form the gap (6a) and the production yield is low. For this reason, the yield is improved by forming two sets of head assemblies into thin films and using only one of the head assemblies with a precisely formed gap as a servo head.

The other head assembly does not have its coil end open.

On the other hand, in the servo thin-film magnetic head 4 of the present magnetic disk device, a head assembly that is not generally used or cannot be used is used as the sub-head assembly 7. Therefore, if necessary, a metal material or the like is applied to the gap portion of the sub-head assembly 7 to eliminate the gap function. Note that the gap may not be formed in advance during the thin film forming process, or the gap may fail to be formed. The sub head assembly 7 only needs to have at least the coil 7b reliably formed.

Further, the output of the main head assembly 6 and the output of the sub-head assembly 7 are connected to have opposite phases, and the output 8 having the opposite phase becomes the output of the thin film magnetic head 4 for servo. That is, the winding start side electrode 6c of the coil 6b of the main head assembly 6 and the winding end side electrode 7d of the coil 7b of the sub head assembly 7 are connected, and the coil 6
The winding end side electrode 6d of the coil 7b and the winding start side electrode 7c of the coil 7b are connected.

In the servo thin-film magnetic head 4 configured as described above, crosstalk components from the main head assembly 6 (coil 6b), the sub-head assembly (coil 7b), the recording/reproducing magnetic head 3, etc. are large. are output equally and in opposite phases to each other, so the crosstalk components are canceled out in the final servo reproduction output. In addition, magnetic disk 2
Since the servo signal from the surface 2a is output only from the main head assembly 6 having the gap 6b, the sub-head assembly 7 without a gap will not have an adverse effect.

Therefore, there is no need to dispose a shield plate or the like between the recording/reproducing magnetic head 3 and the servo thin-film magnetic head 4 to remove crosstalk components, so there is no increase in cost, and the structure is thin (small) and This is a high-performance magnetic disk device with excellent servo control.

In addition, as shown in FIG. 1, in this magnetic disk device,
The axial direction of the coil of the recording/reproducing head 3 (the direction parallel to the plane of the paper due to the coil 3b) is offset from the axial direction of the servo thin film magnetic head 4 (the direction perpendicular to the plane of the paper due to the print coils 6b and 7b). , Also from this point of view, there is less crosstalk.

In addition, as shown in FIG.
Since they are disposed facing each other at the center between the two, there is little crosstalk from this point as well.

[Effects of the Invention] As explained above, according to the present invention, it is possible to reduce the influence of leakage magnetic flux from adjacently arranged magnetic heads, thereby making it possible to miniaturize the device, and furthermore, it is possible to reduce the influence of leakage magnetic flux from adjacent magnetic heads. A magnetic disk device is provided that prevents the adverse effects of.

[Brief explanation of drawings]

FIG. 1 is a diagram showing an embodiment of a magnetic disk device according to the present invention, FIG. 2 is a perspective view showing a thin film magnetic head for servo,
FIG. 3 shows a general magnetic disk device composed of a plurality of magnetic disks, and FIGS. 4 and 5 show conventional examples. 1.2...Magnetic disk, 1a, 1b, 2b--Recording surface, 2a
-...Servo surface, 3...Magnetic head for recording/reproduction, 4...Thin film magnetic head for servo, 6...Main head assembly, 6a...Gap, 6
b... (Printed) coil, 7... Sub head assembly, 7b... (Printed) coil, 6c, 7c... Electrode on the winding start side of the coil, 6d, 7
d... Electrode on the winding end side of the coil, 8... Final output.

Claims (1)

[Claims] A magnetic disk having a data surface and a servo surface, a magnetic head for recording and reproducing data on and from the data surface of the magnetic disk, and a gap and a coil for reproducing servo signals. a main head assembly having a main head assembly, and a sub-head assembly having only a coil formed in a thin film adjacent to each other, and a servo thin film magnetic head for reproducing servo signals from the servo surface of the magnetic disk, the coil of the main head assembly and a coil of the auxiliary head assembly are connected in reverse phase, and the output of the reverse phase connection is used as a servo reproduction signal.