Browse Prior Art Database

Reliable Credit Card Magnetic Stripe

IP.com Disclosure Number: IPCOM000115522D
Original Publication Date: 1995-May-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 49K

Publishing Venue

IBM

Related People

Brady, MJ: AUTHOR [+5]

Abstract

Disclosed is a magnetic stripe ID card that has a high coercivity and the use of thermomagnetic writing to write data on the magnetic stripe. During writing, the magnetic stripe is saturated in one direction along its length. A bias field, less than the coercive field, is applied in the opposite direction along the length of the stripe. With the field on, small regions are heated. In the heated region the coercivity decreases to a value less than the bias field so the heated region switches its direction of magnetization. A magnetic flux transition is created where oppositely magnetized regions meet. Transitions are produced by regions where the magnetic domains are opposing so that some magnetic flux is directed out of the plane of the magnetic stripe in a flux return path through free space.

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This is the abbreviated version, containing approximately 66% of the total text.

Reliable Credit Card Magnetic Stripe

      Disclosed is a magnetic stripe ID card that has a high
coercivity and the use of thermomagnetic writing to write data on the
magnetic stripe.  During writing, the magnetic stripe is saturated in
one direction along its length.  A bias field, less than the coercive
field, is applied in the opposite direction along the length of the
stripe.  With the field on, small regions are heated.  In the heated
region the coercivity decreases to a value less than the bias field
so the heated region switches its direction of magnetization.  A
magnetic flux transition is created where oppositely magnetized
regions meet.  Transitions are produced by regions where the magnetic
domains are opposing so that some magnetic flux is directed out of
the
plane of the magnetic stripe in a flux return path through free
space.

      The heating is accomplished through the application of a
focused laser or multiple laser beams.  It may also be done by
bringing the magnetic stripe into close proximity with a resistively
heated wire or set of wires whose positions correspond to the
magnetic regions to be written.

      What is claimed is a magnetic strip ID card that has a
coercivity of 3000 Oe or more and the means to write to such a card
through the application of a localized elevated temperature in the
presence of an applied magnetic bias field such that:
  1.  the bias field is less than the coercivity at room temperature
      ...