Dynamic magnetic information storage or retrieval – General processing of a digital signal – Data clocking
Reexamination Certificate
2001-10-22
2004-04-20
Faber, Alan T. (Department: 2651)
Dynamic magnetic information storage or retrieval
General processing of a digital signal
Data clocking
C360S031000
Reexamination Certificate
active
06724553
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to reading data in a disk drive and compensating for an offset between a read element and a write element of a head.
2. Background Information
Hard disk drives contain a plurality of magnetic heads that are coupled to rotating disks. The heads write and read information by magnetizing and sensing the magnetic fields of the disk surfaces. There have been developed magnetic heads that have a write element for magnetizing the disks and a separate read element for sensing the magnetic fields of the disks. The read element is typically constructed from a magneto-resistive material. The magneto-resistive material has a resistance that varies with the magnetic fields of the disk. Heads with magneto-resistive read elements are commonly referred to as magneto-resistive (MR) heads.
Each head is attached to a flexure arm to create a subassembly commonly referred to as a head gimbal assembly (“HGA”). The HGA's are suspended from an actuator arm. The actuator arm has a voice coil motor that can move the heads across the surfaces of the disks.
Information is typically stored in radial tracks that extend across the surface of each disk. Each track is typically divided up into a number of segments. The voice coil motor and actuator arm can move the heads to different tracks of the disks.
FIG. 1
shows a typical sector of a disk. The sector contains a servo address mark (SAM) that provides a sync for a SERVO field. The SERVO field contains servo bits that are used to center the head on the track. A DATA field follows the servo field. The data field typically contains a preamble that is used to phase lock the circuits of the disk drive with the information on the disk.
The head is typically connected to a pre-amplifier circuit that has a read gate and a separate write gate. Enabling the write gate allows information to be written onto the disk through the write element of the head. Enabling the read gate allows information to be read from the disk through the read element.
As shown in
FIG. 1
, the write gate WG is typically enabled in conjunction with the trailing edge of a SECTOR signal. The preamble and data are then written onto the disk. There are typically multiple DATA sectors, wherein the process of generating a SECTOR signal and writing data is repeated. The SECTOR signals are typically generated at predetermined time intervals after the detection of the SAM signal. When reading the data the read gate RG is enabled at approximately the trailing edge of the sector signal.
The write element is typically offset from the read element of an MR head. Consequently, some of the preamble is actually written prematurely so that the read element misses a portion of the preamble during a read routine. The preamble is used to phase lock the circuits of the disk drive to allow for proper reading of the data in the subsequent DATA sector(s). Without a sufficient amount of preamble to read, the disk drive may not acquire proper phase lock. A lack of phase lock may cause errors in reading the data. This problem can be alleviated by increasing the length of the preamble so that there is enough preamble data to allow phase lock. Unfortunately, stretching the preamble reduces the storage capacity of the disk drive.
BRIEF SUMMARY OF THE INVENTION
A hard disk drive that includes a head coupled to a disk. The head includes a read element offset from a write element. The drive further includes electrical circuits that enable the read element as a function of the offset.
REFERENCES:
patent: 3834392 (1974-09-01), Lampman et al.
patent: 4343300 (1982-08-01), Hattori
patent: 4499895 (1985-02-01), Takayama
patent: 4572198 (1986-02-01), Condrington
patent: 4573452 (1986-03-01), Greenberg
patent: 4601705 (1986-07-01), McCoy
patent: 4621618 (1986-11-01), Omagari
patent: 4633304 (1986-12-01), Nagasaki
patent: 4672963 (1987-06-01), Barken
patent: 4758222 (1988-07-01), McCoy
patent: 4785806 (1988-11-01), Deckelbaum
patent: 4788975 (1988-12-01), Shturman et al.
patent: 4790813 (1988-12-01), Kensey
patent: 4802033 (1989-01-01), Chi
patent: 4875897 (1989-10-01), Lee
patent: 4887605 (1989-12-01), Angelsen et al.
patent: 4974607 (1990-12-01), Miwa
patent: 4982295 (1991-01-01), Yakuwa et al.
patent: 4996975 (1991-03-01), Nakamura
patent: 5078714 (1992-01-01), Katims
patent: 5104392 (1992-04-01), Kittrell et al.
patent: 5125888 (1992-06-01), Howard et al.
patent: 5170299 (1992-12-01), Moon
patent: 5203781 (1993-04-01), Bonati et al.
patent: 5217001 (1993-06-01), Nakao et al.
patent: 5217003 (1993-06-01), Wilk
patent: 5217453 (1993-06-01), Wilk
patent: 5228429 (1993-07-01), Hatano
patent: 5233482 (1993-08-01), Galbraith et al.
patent: 5235478 (1993-08-01), Hoshimi et al.
patent: 5259365 (1993-11-01), Nishikori et al.
patent: 5268803 (1993-12-01), Sugita et al.
patent: 5274510 (1993-12-01), Sugita et al.
patent: 5301080 (1994-04-01), Ottesen et al.
patent: 5335121 (1994-08-01), Bombeeck
patent: 5335123 (1994-08-01), Shimizu et al.
patent: 5367409 (1994-11-01), Ottesen et al.
patent: 5368015 (1994-11-01), Wilk
patent: 5384671 (1995-01-01), Fisher
patent: 5388127 (1995-02-01), Scarpa
patent: 5402280 (1995-03-01), Supino
patent: 5483393 (1996-01-01), Mento et al.
patent: 5497111 (1996-03-01), Cunningham
patent: 5500776 (1996-03-01), Smith
patent: 5523899 (1996-06-01), Parken et al.
patent: 5539714 (1996-07-01), Andrews, Jr. et al.
patent: 5566101 (1996-10-01), Kodra
patent: 5581420 (1996-12-01), Chainer et al.
patent: 5587850 (1996-12-01), Ton-that
patent: 5590154 (1996-12-01), Forni et al.
patent: 5606469 (1997-02-01), Kosugi et al.
patent: 5608587 (1997-03-01), Smith
patent: 5615058 (1997-03-01), Chainer et al.
patent: 5715105 (1998-02-01), Katayama et al.
patent: 5781133 (1998-07-01), Tsang
patent: 5822143 (1998-10-01), Cloke et al.
patent: 5844920 (1998-12-01), Zook et al.
patent: 5862007 (1999-01-01), Pham et al.
patent: 5898532 (1999-04-01), Du et al.
patent: 5905601 (1999-05-01), Tsunoda
patent: 5961658 (1999-10-01), Reed et al.
patent: 5986847 (1999-11-01), Le et al.
patent: 6094316 (2000-07-01), Pham et al.
patent: 0079524 (1983-05-01), None
Chu Sang Hoon
Kim Gyu Tack
Lee Kang Seok
Yun Jong Yun
Aiello Jeffrey P.
Faber Alan T.
Irell & Manella LLP
Samsung Electronics Co,. Ltd.
LandOfFree
Method and apparatus for generating the optimum read timing... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Method and apparatus for generating the optimum read timing..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Method and apparatus for generating the optimum read timing... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3244034