Dynamic magnetic information storage or retrieval – General recording or reproducing – Signal switching
Reexamination Certificate
1998-10-14
2001-03-27
Kim, W. Chris (Department: 2651)
Dynamic magnetic information storage or retrieval
General recording or reproducing
Signal switching
C360S051000
Reexamination Certificate
active
06208480
ABSTRACT:
The present invention relates generally to disc drive data storage systems. More particularly, the present invention relates to circuits and methods for maintaining a rotation position reference on a headerless format disc drive.
In a headerless disc drive, header information is not available to identify unique sectors around the surface of the discs. Therefore, a constant rotational position reference is required by the controller to determine the location of a desired data sector. Servo information is written in spokes around the surface of the disc, and detection of this servo information can be used to provide a rotational position reference.
When data to be written to or read from a different disc surface than is currently being accessed, a “head switch” occurs. The timing of the servo information can shift during these head switches, and consequently multiple detections of servo information can be missed for the same rotational position. In order to obtain a constant rotational position reference, which is necessary to consistently identify the correct disc sector after a head switch occurs, it can sometimes be necessary to wait until the next INDEX mark data pattern is detected to become re-orientated. Since the INDEX mark data pattern is written at only one position on each disc, this method of re-orientating after a head switch can result in significant delay, as the discs may have to go through a complete rotation prior to detection of the INDEX mark data pattern.
The present invention provides a solution to this and other problems, and offers other advantages over the prior art.
SUMMARY OF THE INVENTION
The present invention relates to headerless format data storage systems and apparatus, such as disc drive data storage systems, which include a circuit and method for maintaining a rotation position reference.
In accordance with one embodiment of the invention, a data storage apparatus is provided in which the multiple disc surfaces of a disc stack are divided into multiple rotationally spaced apart servo frames. Servo data is written on the multiple disc surfaces within radially extending servo spokes such that each disc surface includes one servo spoke within each servo frame. Within each particular servo frame the servo spokes on each of the multiple disc surfaces are offset rotationally from one another. In addition, servo control circuitry and a method of using the same to provide positional reference signals for the staggered servo format are disclosed.
These and various other features as well as advantages which characterize the present invention will be apparent upon reading of the following detailed description and review of the associated drawings.
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Kim W. Chris
Seagate Technology LLC
Westman Champlin & Kelly P.A.
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