Dynamic magnetic information storage or retrieval – Record medium – In container
Reexamination Certificate
2000-06-30
2002-07-30
Heinz, A. J. (Department: 2652)
Dynamic magnetic information storage or retrieval
Record medium
In container
Reexamination Certificate
active
06426849
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a flexible or floppy disk (which may be abbreviated to “FD”) for use in a removable type magnetic recording/reproducing device such as a flexible or floppy disk drive (which may be abbreviated to “FDD”).
As is well known in the art, the flexible disk of the type described comprises a magnetic recording medium and a jacket for receiving the magnetic recording medium. The magnetic recording medium comprises a flexible thin sheet composed of synthetic resin, a magnetic recording layer formed on a surface of the flexible thin sheet, and a coating layer formed on the magnetic recording layer.
On the other hand, the flexible disk drive of the type described is an apparatus for carrying out data recording and reproducing operation to and from the magnetic recording medium of the flexible disk inserted or loaded therein. In recent years, the flexible disks are more and more improved to have a larger storage capacity. Specifically, development is made of the flexible disks having the storage capacity of 128 megabytes (which may be called large-capacity FDs) In contrast with the flexible disks having storage capacity of 1 megabytes or 2 megabytes (which may be called small-capacity FDs). Following such development, the flexible disk drives have also been improved to accept the large-capacity FDs for data recording and reproducing operations to and from the magnetic recording media of the large-capacity FDs. Furthermore, the large-capacity FDs are more improved to have a larger storage capacity of 256 Mbytes, 512 Mbytes, . . . , and so on.
Throughout the present specification, flexible disk drives capable of recording/reproducing data for magnetic recording media of the large-capacity FDs alone will be referred to as “high-density exclusive type FDDs.” On the other hand, flexible disk drives capable of recording/reproducing data for magnetic recording media of the small-capacity FDs alone will be called “low-density exclusive type FDDs.” Furthermore, flexible disk drives capable of recording/reproducing data for magnetic recording media of both the large-capacity and the small-capacity FDs will be called “high-density/low-density compatible type FDDs.” In addition, the high-density exclusive type FDDs and the high-density/low-density compatible type FDDs will collectively be called “high-density type FDDS.”
The low-density exclusive type FDD and the high-density type FDD are different in mechanism from each other in several respects, one of which will presently be described. In either FDD, a pair of magnetic heads is supported by a carriage which is driven by a drive arrangement to move in a predetermined radial direction with respect to the magnetic disk medium of the flexible disk loaded in the flexible disk drive. The difference resides in the structure of the structure of the drive arrangement. More specifically, the low-density exclusive type FDD uses a stepping motor as the drive arrangement. On the other hand, the high-density type FDD uses a linear motor such as a voice coil motor (which may be called “VCM” for short) as the drive arrangement.
Now, description will be made in slightly detail as regards the voice coil motor used as the drive arrangement in the high-density type FDD. The voice coil motor comprises a voice coil and a magnetic circuit. The voice coil is disposed on the carriage at a rear side and is wound around a drive axis extending in parallel to the predetermined radial direction. The magnetic circuit generates a magnetic field in a direction intersecting that of an electric current flowing through the voice coil. With this structure, by causing the electric current to flow through the voice coil in a direction intersecting that the magnetic field generated by the magnetic circuit, a drive force occurs in a direction extending to the axis on the basis of interaction of the electric current with the magnetic field. The drive force causes the voice coil motor to move the carriage in the predetermined radial direction.
Another difference between the low-density exclusive type FDD and the high-density type FDD resides in the number of revolution of a spindle motor for rotating the magnetic recording medium of the flexible disk loaded therein. More specifically, the low-density exclusive type FDD may rotate the magnetic recording medium of the small-capacity FD loaded therein at a low rotation speed having the number of revolution of either 300 or 360. On the other hand, the high-density type FDD can admit, as the flexible disk to be loaded therein, either the large-capacity FD alone or both of the large-capacity FD and the small-capacity FD. As a result, when the large-capacity FD is loaded in the high-density type FDD, the spindle motor for the high-density type FDD must rotate the magnetic recording medium of the large-capacity FD loaded therein at a high rotation speed having the number of revolution of 3,600 rpm which is equal to ten or twelve times as large as that of the small-capacity FD.
In the meanwhile, the large-capacity FD generally has an external configuration identical with that of the small-capacity FD. Specifically, both of the large-capacity and the small-capacity FDs have a flat rectangular shape of a width of 90 mm, a length of 94 mm, and a thickness of 3.3 mm in case of a 3.5-inch type. However, the large-capacity FD has a narrower track width (track pitch) than that of the small-capacity FD. As a result, it is difficult for the large-capacity FD to position a magnetic head of the high-density type FDD on a desired track in the magnetic recording medium thereof in contrast with the small-capacity FD. Accordingly, a servo signal for position detection is preliminarily written in the magnetic recording medium of the large-capacity FD.
In addition, the flexible disk is called a disk cartridge in the manner known in the art. The disk cartridge comprises the magnetic recording medium, upper and lower shells for receiving the magnetic recording medium with a space left therebetween, an upper liner adhered to an inner surface of the upper shell, and a lower liner adhered to an inner surface of the lower shell. The magnetic recorded medium is disposed between the upper and the lower liners. A combination of the upper and the lower shells is referred to as the jacket. That is, the magnetic recording medium is received in the jacket
The jacket is made by molding of synthetic resin. Specifically, the jacket comprises the combination of the upper and the lower shells each of which is generally made by injection molding.
The upper and the lower liners are for removing fine dust from adhered to upper and lower surfaces of the magnetic recording medium. Each of the upper and the lower liners is annular in shape and comprises a nonwoven fabric sheet which is made of, for example, rayon. The upper and the lower shells are provided with upper and lower rectangular head windows, respectively, to permit an access to the magnetic recording medium by a pair of magnetic heads.
The magnetic recording medium has an annular shape with a medium circular opening formed at its center to be concentric with a center axis of the magnetic recording medium. The magnetic recording medium is made of a magnetic material having a flexibility. That is, as described above, the magnetic recording medium comprises the flexible thin sheet composed of synthetic resin, the magnetic recording layer formed on the surface of the flexible thin sheet, and the coating layer formed on the magnetic recording layer. The magnetic recording medium is supported at the periphery of the medium circular opening by a metal hub through a double-sided adhesive tape called an A ring in the art.
The metal hub is generally made by press molding of a metal plate. Specifically, the metal hub has a substantially dish shape and comprises a concave portion at its center thereof and an outer circumferential portion at the periphery of the concave portion. That is, the concave portion consists of a cylindrical portion and a circular bottom portion. In addition, th
Frishauf Holtz Goodman & Chick P.C.
Heinz A. J.
Mitsumi Electric Co. Ltd.
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