Disclosed is a magnetic disk memory having a magnetic disk and a magnetic head device adapted to record and/or reproduce information using the magnetic disk as a medium. The magnetic head device is composed of a plurality of magnetic heads rigidly mounted on one slider, these plurality of magnetic heads being arranged in the radial direction of the magnetic disk.
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1. A magnetic disk memory comprising a magnetic disk and a magnetic head device adapted to record and/or reproduce information using said magnetic disk as a recording and/or reproducing medium having a defined recording and/or reproducing area, said magnetic head device being comprised of at least three magnetic heads rigidly mounted on one slider, said at least three magnetic heads being arranged in a radial direction of said magnetic disk at an equal pitch corresponding to a distance determined by dividing a radius of said defined recording and/or reproducing area of said magnetic disk by the number of magnetic heads, said magnetic head device being adapted to be moved by said pitch or distance.
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This invention relates to a magnetic disk memory, and in particular to the magnetic head mounting structure of a magnetic head device for a magnetic disk memory.
A magnetic disk memory is equipped with a magnetic head device by means of which recording and/or reproduction of information on or from the magnetic disk is effected. Conventionally, a magnetic disk memory having a large-diameter magnetic disk is equipped with a so-called multihead-type magnetic head device in which a plurality of magnetic heads are arranged in a row in the radial direction of the magnetic disk in order to shorten the access time by reducing the magnetic head transfer distance.
In a well-known multihead-type magnetic head device, a magnetic head assembly is so constructed that each magnetic head is attached to one slider. A plurality of magnetic head assemblies thus constructed are mounted at equal pitch on a support member in a longitudinal direction thereof, through respective gimbal springs.
This magnetic head device is arranged in the radial direction of the magnetic disk, with the magnetic gaps of the magnetic heads facing the magnetic disk. The magnetic heads are moved radially over the magnetic disk by driving an actuator connected to the support member.
The recording area for recording and/or reproducing information on a magnetic disk memory equipped with this magnetic head device is shared by a plurality of magnetic heads arranged in the radial direction of the magnetic disk, so that the magnetic head transfer range which is effected by the actuator can be relatively narrow, whereby the access time can be shortened.
The above-described multihead-type magnetic head device is effective for a magnetic head device having a magnetic disk with a relatively large diameter.
However, the construction of this magnetic head device is such that one magnetic head is attached to one slider, which is mounted on a support member through a gimbal spring, so that a large area is needed for one magnetic head to be mounted on the support member. For the magnetic heads to be arranged on the support member, the space between two adjacent magnetic heads must be equal to or greater than the width of the gimbal spring. Accordingly, it is by no means easy to apply a multihead-type magnetic head device to a magnetic disk having a small diameter such as 5.25 inches. In particular, it is next to impossible to apply a multihead-type magnetic head device to a magnetic disk whose diameter is 2.5 inches or less.
In the field of magnetic disk memory, one of the most important technical problems have become how to make the device smaller and how to increase the access speed. Hence the urgent demand for a multihead-type magnetic head device which can be applied to a magnetic disk memory equipped with a magnetic disk having such a small diameter as mentioned above.
Accordingly, it is an object of this invention to provide a magnetic disk memory which will overcome the problems in the above-described prior art.
The present invention provides a small magnetic disk memory equipped with a magnetic head device on which a plurality of magnetic heads are mounted close to each other.
In accordance with this invention, a plurality of magnetic heads are rigidly mounted on one slider, the magnetic heads being arranged in the radial direction of the magnetic disk.
Since in this invention the plurality of sliders and gimbal springs required in the conventional device, providing one slider and spring for each magnetic head, are omitted, the magnetic heads can be arranged in a row at a pitch corresponding to from several to a few hundreds of tracks. Accordingly, this invention makes it possible to apply a multihead-type magnetic head device to a magnetic disk memory equipped with a magnetic disk having a small diameter.
A small-diameter magnetic disk can be driven at high speeds. This high rotational speed of the magnetic disk and the shortness of the transfer distance to be covered by the magnetic heads together help to shorten the access time in recording/reproduction.
FIG. 1 is a perspective view of a magnetic disk memory according to an embodiment of the present invention;
FIG. 2 is a perspective view of the magnetic head assembly of the magnetic disk memory shown in FIG. 1; and
FIG. 3 is an exploded, perspective view of a conventional multihead-type magnetic head device.
In the conventional multihead-type magnetic head device shown in FIG. 3, magnetic head assemblies 23, each composed of one slider 21 and one magnetic head 22 attached thereto, are mounted on a support member 25 at equal pitch in the longitudinal direction thereof, through respective gimbal springs 24.
This magnetic head device is arranged in the direction of the magnetic disk such that the magnetic gaps of the magnetic heads 22 face the magnetic disk. The magnetic heads 22 are moved over the magnetic disk in the radial direction of the disk by driving an actuator (not shown) connected to the support member 25. In this magnetic head device, it is impossible to arrange the magnetic head assemblies 23 on the support member 25 at a pitch corresponding to the width W of the gimbal spring 24 or less. Accordingly, it is by no means easy to apply this multihead-type magnetic head to a magnetic disk whose diameter is as small as 5.25 inches. In particular, it is next to impossible to apply this multihead-type magnetic head device to a magnetic disk whose diameter is 2.5 inches or less.
FIG. 1 schematically shows a magnetic disk memory in accordance with an embodiment of the present invention. This magnetic disk memory includes a magnetic disk 1, a spindle 2 adapted to drive the magnetic disk 1, and a magnetic head device 3.
The magnetic disk 1 is composed of a glass plate 4 having an outer diameter of 2.5 inches, an inner diameter of 1 inch, and a thickness of 0.2 mm. Both surfaces of this glass plate 4 are polished smooth and coated with magnetic films 5. The magnetic film 5 is composed of a chromium layer having a thickness of 0.2 μm, a cobalt-nickel alloy layer having a thickness of 0.05 μm, and a carbon layer having a thickness of 0.02 μm, sputtered and arranged in this order outward from the surface of the glass plate 4. In this magnetic disk 1, the area corresponding to a radius of about 21.8 mm to about 28.3 mm serves as the recording area. A track 6 for a tracking servo is provided in the area radially extending about 1.6 mm from the innermost border of the recording area (i.e., the area corresponding to a radius of about 21.8 mm to about 23.4 mm) with a track density of 1000 tpi. The remaining portion of the recording area other than the innermost servo tracking area serves as a data area where data is recorded.
The spindle 2 which is connected to a motor (not shown) drives the disk 1 at 7200 r.p.m.
The magnetic head device 3 is composed of a magnetic head assembly 7, a spring member 8 elastically supporting this magnetic head assembly 7, and an actuator adapted to transfer the magnetic head assembly 7 radially over the magnetic disk 1.
As FIG. 2 shows in detail, the magnetic head assembly 7 includes a floating slider 10 on whose medium side surface, i.e. that side surface of the slider 10 which faces the magnetic disk, four thin-film magnetic heads 11a, 11b, 11c and 11d having a width (W) of 3 mm, a height (H) of 1 to 2 mm, and a thickness (T) of 0.15 mm are embedded at equal pitch P of 1.6 mm. By a floating slider is meant the type of slider which is separated from the surface of the magnetic disk and floats over it by introducing an air flow between its medium side surface and the magnetic disk when the latter is rotated. The slider 10 may also be of the contact type. Reference numerals 12a, 12b, 12c and 12d in FIG. 2 denote leads connecting the magnetic heads 11a, 11b, 11c and 11d to an external apparatus. In this magnetic head assembly 7, the magnetic head 11a which will be farthest from the actuator 9 is so adjusted that it comes to the position over the track 6 for the tracking servo, the magnetic heads 11a, 11b, 11c and 11d being arranged in a row in the radial direction of the magnetic disk. As described above, the servo tracking area is arranged on the innermost side of the recording area surrounded by the recording area, so that there is obtained a favorable signal to noise ratio for data. For the actuator 9 which serves to drive the magnetic head assembly 7, a stepping motor, a voice coil, or the like may be employed.
Since in the above-described magnetic disk four magnetic heads 11a, 11b, 11c and 11d are arranged in a row in the radial direction of the magnetic disk 1, the recording area to be shared by one magnetic head is 1/4 of the entire recording area. Accordingly, the transfer distance to be covered by the magnetic disk assembly 7 when it is driven by the actuator 9 can be reduced to 1/4 of the recording area, resulting in a greatly reduced access time. Since the magnetic heads are rigidly embedded in one slider 10, the pitch P between two adjacent magnetic heads can be as small as 1.6 mm. Accordingly, the magnetic head device can be applied to a magnetic disk whose diameter is as small as 2.5 inches.
Further, since 1/4 of the recording area of the magnetic disk can be used as the servo track area, a sufficient effective area can be secured advantageously.
A magnetic disk memory in accordance with the above-described embodiment was tested under the following conditions: the rotational speed of the magnetic disk was 7200 rpm and the linear information recording density 30 kbpi. The actuator 9 used was of the voice coil type. The test gave an average track positioning time of 8 mS, an average rotation waiting time of about 4 mS, which means an average access time of 12 mS. Thus an ultra-high-speed access was realized.
While in the above-described embodiment only one magnetic disk is provided, the gist of this invention is not to be so restricted. A multitude of magnetic disks may be stacked on the spindle, magnetic heads being arranged on both surfaces of each magnetic disk. In that case, a track for the tracking servo is formed on one surface of one of the magnetic disks.
The present invention essentially relates to a magnetic head mounting structure in a magnetic disk memory. The size, structure and material of the magnetic disk used and the structure, number, spacing, etc. of the magnetic heads embedded in one slider are not to be restricted to those in the above-described embodiment. They may be arbitrarily selected as needed.
As described above, in the magnetic disk memory of this invention a plurality of magnetic heads are rigidly embedded in one slider, so that the distance between two adjacent magnetic heads can be very small. This enables a multihead-type magnetic head device to be applied to a small-diameter magnetic disk. Accordingly, the access time in recording/reproduction can be substantially reduced by the synergistic effect of the increased rotational speed of the magnetic disk and the shortened transfer distance of the magnetic heads.
The invention being thus described, it will be obvious that the same may be varied in many ways. Such variations are not to be regarded as a departure from the spirit and scope of the present invention, and all such modifications as would be obvious to one skilled in the art are intended to be included within the scope of the following claims.
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| Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
| Sep 15 1988 | Hitachi Maxell Ltd. | (assignment on the face of the patent) | / |
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