Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data in specific format
Reexamination Certificate
1997-12-17
2002-01-22
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data in specific format
C360S053000, C360S051000, C360S077080, C360S078140
Reexamination Certificate
active
06341045
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a magnetic recording medium such as 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”) and a format method thereof.
As is well known in the art, the FDD of the type described is a device for carrying out data recording and reproducing operations to and from a magnetic disk medium of the FD loaded therein. In recent years, the FDs have been more and more improved to have a larger storage capacity. Specifically, development has been made of FDs having a storage capacity of 128 Mbytes (which may be called large-capacity FDs) in contrast with FDs having a storage capacity of 1 Mbyte or 2 Mbytes (which may be called small-capacity FDs). Following such development, the FDDs have also been improved to accept the large-capacity FDs for data recording and reproducing operations to and from the magnetic disk media of the large-capacity FDs. Furthermore, the large-capacity FDs have been more improved to have a larger storage capacity of 256 Mbytes, 512 Mbytes, . . . , and so on.
Throughout the present specification, FDDs capable of recording/reproducing data for magnetic disk media of the large-capacity FDs alone will be referred to high-density exclusive type FDDs. On the other hand, FDDs capable of recording/reproducing data for magnetic disk media of the small-capacity FDs alone will be called low-density exclusive type FDDs. Furthermore, FDDs capable of recording/reproducing data for magnetic disk 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 magnetic head 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 FD loaded in the FDD. The difference resides in 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 abbreviated to “VCM”) as the drive arrangement.
Now, description will be made with respect to 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 of the magnetic field generated by the magnetic circuit, a drive force occurs in a direction extending to the drive 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 revolutions of a spindle motor for rotating the magnetic disk medium of the FD loaded therein. More specifically, the low-density exclusive type FDD may rotate the magnetic disk medium of the small-capacity FD loaded therein at a low rotation speed of either 300 rpm or 360 rpm. On the other hand, the high-density type FDD can admit, as the PD to be loaded thereinto, either the large-capacity FD alone or both of 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 disk medium of the large-capacity FD loaded therein at a high rotation speed of 3600 rpm which is equal to ten or twelve times as large as that of the small-capacity PD.
In the meanwhile, the large-capacity FD generally has an external configuration identical with that of the small-capacity PD. 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 disk medium thereof in contrast with the small-capacity FD. Accordingly, a servo signal for position detection is preliminarily written in the magnetic disk medium of the large-capacity FD.
In addition, it is necessary for the high-density/low-density compatible type FDD to identify and detect whether the FD loaded therein is the large-capacity FD or the small-capacity PD.
An FD about to be manufactured (which will be called a raw FD) comprises merely a magnetic disk medium having both surfaces coated with magnetic material. In order to enable to make the raw FD useable for an electronic device such as a personal computer or a word processor, it is necessary for the raw FD to partition the magnetic disk medium into a plurality of regions with addresses and to record and manage what information should be written in each region. Such a sequence of processing steps is called a format(ting) or an initialization.
In general, the FD comprises the magnetic disk medium on which a plurality of tracks which are arranged with concentric circles around a center of rotation thereof. The tracks may be arranged in a swirl fashion around the center of rotation. Each track is divided in a circumferential direction into a predetermined number of sectors having a length equal to one another.
The formatting is classified into a physical formatting and a logical formatting. The physical formatting determines how data is arranged on the magnetic disk medium. Specifically, the physical formatting determines the total tracks, the total usable tracks, the number of sectors in each track, a medium storage capacity, a format storage capacity, and so on. On the other hand, the logical formatting determines locations where information corresponding to table of contents is written on the magnetic disk medium and assigns addresses to units each of which writes information. The logical formatting is also called a sector formatting.
In the sector formatting, each sector is partitioned into a servo field and a data field. Each sector includes at least a number field indicative of a position thereof and a sector timing mark field for notifying the number field. The number field comprises a sector number field on which a sector number is written and a track number field on which a track number is written. In a conventional sector-formated FD, the sector timing mark field is included in the data field and therefore the number field is also included in the data field. As a result, the data region has a restricted amount for writable data in the sector-formated FD. Inasmuch as the number field is included in the data field, it is necessary to mask the number field so that any user cannot see it. In addition, procedure and processing become complicated after reading of information out of the data field in the sector. Furthermore, the conventional sector-formated FD has no space for storing alteration contents of the magnetic disk medium.
In addition, the sector formatting is performed by using a servo writer and a media formatter. The servo writer partitions first each sector into the servo field and the data field to write the above-
Hironaka Hisakazu
Itoh Toshimitsu
Majima Yoshihide
Shimizu Toshiharu
Touji Hidetsugu
Faber Alan T.
Frishauf, Holtz Goodman, Langer & Chick, P.C.
Mitsumi Electric Co. Ltd.
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