Browse Prior Art Database

Read and Write Inhibitfor MR Head

IP.com Disclosure Number: IPCOM000115138D
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 4 page(s) / 68K

Publishing Venue

IBM

Related People

Kisaka, M: AUTHOR [+2]

Abstract

This article describes an algorithm to inhibit off track read/write for a hard disk drive. As a head like a MR head has offset between a read element and a write element, it is required to read or write data at offset position from servo pattern center. If there is no information to identify user data in user data area such as no ID format, only servo information is used for identifying accessed user data. The described method checks head position during read/write with 2 phase servo information (A-B,and C-D) instead of 1 servo information (A-B).

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Read and Write Inhibitfor MR Head

      This article describes an algorithm to inhibit off track
read/write for a hard disk drive.  As a head like a MR head has
offset between a read element and a write element, it is required to
read or write data at offset position from servo pattern center.  If
there is no information to identify user data in user data area such
as no ID format, only servo information is used for identifying
accessed user data.  The described method checks head position during
read/write with 2 phase servo information (A-B,and C-D) instead of 1
servo information (A-B).

      Fig. 1 shows typical servo pattern used for controlling read
element position around center of a track.  If a read element follows
at center of a track (A = B), a write element is not at the center in
case of a MR head.  So, to read the written data by the read element,
a head must follows at offset position.  In case of no ID format,
track ID area of servo information is used to identify user data, but
if the read element must read user data at offset position, track ID
read at offset position may be adjacent one.  That makes difficult to
read written data as only servo information (Track ID) can identify
user data.

      Fig. 2 shows 4 burst patterns that make 2 phase servo
information by using A-B and C-D.  By inhibiting read or write when
A-B and C-D values are out of certain range, correct user data can be
accessed.  Fig. 3 shows an algorithm.