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Browse Prior Art Database

Forming a Structure for Magnetic Matrix Display

IP.com Disclosure Number: IPCOM000123383D
Original Publication Date: 1998-Oct-01
Included in the Prior Art Database: 2005-Apr-04
Document File: 1 page(s) / 32K

Publishing Venue

IBM

Related People

Beeteson, JS: AUTHOR [+4]

Abstract

A basic component of a magnetic matrix display (MMD) is a permanent magnet, the same area as the display and 1 to 2mm thick, perforated with one aperture per pixel.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 92% of the total text.

Forming a Structure for Magnetic Matrix Display

   A basic component of a magnetic matrix display (MMD) is
a permanent magnet, the same area as the display and 1 to 2mm thick,
perforated with one aperture per pixel.

   One technique for producing such a magnet is to etch a
50mm thick non-magnetic stainless steel sheet with the required hole
pattern, to laminate this to a greensheet of glass bound ferrite and
to punch the ferrite using the steel plate as a punch guide.  The two
sheets are then pressed together and sintered at high temperature.
Thus steel-ferrite-steel laminate is produced having both stiffness
and tensile strength.

   A potential problem is that residual stresses in the steel
may cause an unpredictable bowing in the final assembly.  This
procedure described here provides a solution to this problem, and
further provides an aid to final assembly of the magnet in the
display.

   The improved procedure involves selecting the steel material
of the two magnet faces so that they have slightly different
coefficients of expansion - the precise values are determined by
experiment.  During processing the two sheets will be pressed flat
and taken to a high temperature.  When cooled one plate will
contract slightly more than the other, and thus the structure will
bow in a predictable direction and by a predictable amount (which
would, of course, be small).  The direction of bow may be chosen to
either be towards the anode of the display or to the cathode.

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