Disk storage device with spiral data track and incremental error offsets in angularly spaced imbedded concentric servo patterns

• US 5,619,387 A
• Filed: 08/12/1996
• Issued: 04/08/1997
• Est. Priority Date: 01/21/1994
• Status: Expired due to Term

• Current Assignee: Western Digital Technologies Incorporated (Western Digital Corporation)
• Original Assignee: International Business Machines Corporation
• Inventors: Ottesen, Hal H., Greenberg, Richard, Cunningham, Earl A., Brown, Dana H.
• Primary Examiner(s): Kim, Kenneth S.
• Application Number:
  US08/689,582
• Time in Patent Office: 239 Days
• Field of Search: 360/77.08, 360/77.01, 369/111, 369/44.25, 358/342
• US Class Current: 360/77.08
• CPC Class Codes: G11B 19/20 Driving; Starting; Stopping; Control thereof
• CPC Class Codes: G11B 19/2009 Turntables, hubs and motors for disk drives; Mounting of motors in the drive means for clamping of disk to turntable G11B17/022 and subgroups
• CPC Class Codes: G11B 19/247 using electrical means
• CPC Class Codes: G11B 20/12 Formatting, e.g. arrangement of data block or words on the record carriers within interface between computers and data recorders G06F3/06
• CPC Class Codes: G11B 20/1258 where blocks are arranged within multiple radial zones, e.g. Zone Bit Recording or Constant Density Recording discs, MCAV discs, MCLV discs
• CPC Class Codes: G11B 2020/10916 Seeking data on the record carrier for preparing an access to a specific address
• CPC Class Codes: G11B 21/00 Head arrangements not specific to the method of recording or reproducing
• CPC Class Codes: G11B 21/02 Driving or moving of heads
• CPC Class Codes: G11B 21/04 Automatic feed mechanism producing a progressive transducing traverse of the head in a direction which cuts across the direction of travel of the recording medium, e.g. helical scan , e.g. by lead-screw G11B19/20, G11B21/08 and G11B21/10 take precedence
• CPC Class Codes: G11B 2220/20 Disc-shaped record carriers
• CPC Class Codes: G11B 2220/41 Flat as opposed to hierarchical combination, e.g. library of tapes or discs, CD changer, or groups of record carriers that together store one title
• CPC Class Codes: G11B 2220/415 Redundant array of inexpensive disks [RAID] systems
• CPC Class Codes: G11B 27/002 Programmed access in sequence to a plurality of record carriers or indexed parts, e.g. tracks, thereof, e.g. for editing; transfer of record carriers from magazine G11B15/68, G11B17/10; G11B17/22
• CPC Class Codes: G11B 27/105 of operating discs
• CPC Class Codes: G11B 5/012 Recording on, or reproducing or erasing from, magnetic disks G11B17/00, G11B19/00 take precedence
• CPC Class Codes: G11B 5/5521 across disk tracks spiral track following G11B5/596
• CPC Class Codes: G11B 5/5526 Control therefor; circuits, track configurations or relative disposition of servo-information transducers and servo-information tracks for control thereof G11B5/556 takes precedence
• CPC Class Codes: G11B 5/5965 Embedded servo format G11B5/59655 takes precedence
• CPC Class Codes: G11B 7/0037 with discs
• CPC Class Codes: H04N 7/17336 Handling of requests in head-ends

Abstract

A disk drive stores multimedia data in long spiral data tracks. The tracks on opposite surfaces of the disk spiral in opposite directions, so that a track on one surface can be read as the actuator sweeps in, and a track on the opposite surface can be read as the actuator sweeps out. Because the actuator only follows spiral tracks without performing long seek operations, the actuator motor can be reduced in size and stresses on actuator bearings and other parts are reduced. Additionally, due to reduced disturbances associated with seeks, it is possible to follow tracks more closely and therefore reduce the width of individual tracks. Further cost reductions are accomplished by spinning the disks at a slower speed and reducing the size of the spin motor accordingly. Finally, data density can be increased simply because multimedia data does not require the same low error rate as conventional data. Preferably, a group of disk drives optimized for multimedia data is used to form a video-on-demand system. Compressed, interleaved portions of a video presentation, such as a motion picture, are stored in blocks on the spiral tracks. The drives read the blocks on one spiral track at a time from beginning to end, placing the data from these blocks in a set of buffers corresponding to different short time intervals. Video signals are output from the buffers. Any short time interval of the presentation can be accessed on demand by switching to the appropriate buffer.

Claims

1. A rotating disk data storage device, comprising:

at least one disk rotatably mounted on a spindle, said at least one disk having a first annular recording surface for recording magnetically encoded data, wherein said recording surface is formatted to contain at least one spiral data track, and wherein said recording surface is formatted to contain a plurality of angularly spaced imbedded servo patterns, said imbedded servo patterns defining a plurality of concentric track centerlines;

a spindle motor for rotating said at least one disk in a predetermined direction;

a data transducer mounted on a movable actuator for accessing data recorded on said recording surface; and

a servo feedback system for positioning said data transducer to follow said spiral data track, wherein said servo feedback system derives separate position error information from each respective one of said angularly spaced imbedded servo patterns, each said position error information representing deviation of said data transducer from a concentric track centerline defined by said imbedded servo patterns, said deviation being measured at a respective one of said angularly spaced imbedded servo patterns, and wherein said servo feedback system adds a spiral track position error offset to each said position error information derived from each respective one of said angularly spaced imbedded servo patterns, said spiral track position error offset being a unique, discrete amount associated with each respective angularly spaced imbedded servo pattern, said unique, discrete amounts varying incrementally as a function of angular position of each said respective angularly spaced imbedded servo pattern on said disk.

2. The rotating disk data storage device of claim 1, further comprising:

a second annular recording surface on said at least one disk;

said second annular recording surface being formatted to contain at least one spiral data track;

wherein said first and second annular recording surfaces have respective inner and outer edges thereof;

wherein said spiral data track on said first annular recording surface spirals inward from said outer edge of said first recording surface toward said inner edge of said first recording surface as said at least one disk rotates in said predetermined direction; and

wherein said spiral data track on said second annular recording surface spirals outward from said inner edge of said second recording surface toward said outer edge of said second recording surface as said at least one disk rotates in said predetermined direction.

3. The rotating disk data storage device of claim 1, wherein said data transducer comprises a magneto-resistive read head and an inductive write head, said inductive write head having a width less than 1.5 times the width of the magneto-resistive read head.

4. The rotating disk data storage device of claim 1, wherein said spiral data track has a track width of not more than 3.5 microns.

5. The rotating disk data storage device of claim 1, wherein data is stored on said recording surface at an areal density of at least 500 Mega-bits per square inch.

6. The rotating disk data storage device of claim 1, wherein said servo feedback system increments said spiral track position error offset a discrete amount when said data transducer passes over each of said angularly spaced imbedded servo patterns.

7. The rotating disk data storage device of claim 3, wherein said inductive write head has a width about 1.15 times the width of the magneto-resistive read head.