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Browse Prior Art Database

High-Speed High-Resolution Measurement of Disk Bulk Magnetics

IP.com Disclosure Number: IPCOM000100767D
Original Publication Date: 1990-Jun-01
Included in the Prior Art Database: 2005-Mar-16
Document File: 2 page(s) / 63K

Publishing Venue

IBM

Related People

Nguyen, SV: AUTHOR [+2]

Abstract

Described is a technique to nondestructively measure the bulk magnetic properties of the recording film on magnetic rigid disks. The measuring device consists of a spindle 4 to rotate the disk 3, a magnetic recording head(s) 2, an external H field magnet 1 and associated electronics and data processor. The envelope from the read signal is digitized at X points on the disk at Y applied external H fields. From this matrix the disk 3 coercivity, coercive squareness and magnetic moment can be determined for the X positions on the disk 3 at the radius of the test head(s) 2. This device is referred to as a Spinning Disk Magnitometer (SDM).

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 55% of the total text.

High-Speed High-Resolution Measurement of Disk Bulk Magnetics

       Described is a technique to nondestructively measure the
bulk magnetic properties of the recording film on magnetic rigid
disks.  The measuring device consists of a spindle 4 to rotate the
disk 3, a magnetic recording head(s) 2, an external H field magnet 1
and associated electronics and data processor.  The envelope from the
read signal is digitized at X points on the disk at Y applied
external H fields.  From this matrix the disk 3 coercivity, coercive
squareness and magnetic moment can be determined for the X positions
on the disk 3 at the radius of the test head(s) 2. This device is
referred to as a Spinning Disk Magnitometer (SDM).

      The device works as follows (refer to Figs. 1 and 2):
      1.   With the calibrated H field source 1 set at zero,
           a low frequency signal is recorded on the disk 3
           with the magnetic recording head 2 and write
           electronics 10.  The write current should be high
           enough to saturate the medium.
      2.   The envelope is extracted from the read/write head
           signal and filtered with a low-pass filter 8 via
           electronics.
      3.   The envelope is digitized at X positions
           physically synchronized to the disk by the D/A
           converter 9 and position generator 7.  The X
        ...