Browse Prior Art Database

Automated Assessment of Visual Display Unit Magnetic Susceptibility

IP.com Disclosure Number: IPCOM000116585D
Original Publication Date: 1995-Oct-01
Included in the Prior Art Database: 2005-Mar-30
Document File: 2 page(s) / 43K

Publishing Venue

IBM

Related People

Sawdon, D: AUTHOR

Abstract

VDU image jitter (caused by external magnetic fields) is becoming a much discussed topic but there are currently no published test methods or criteria for acceptable performance. The assessment of image jitter is difficult and requires both trained staff and a specially prepared test area.

This text was extracted from an ASCII text file.
This is the abbreviated version, containing approximately 66% of the total text.

Automated Assessment of Visual Display Unit Magnetic Susceptibility

      VDU image jitter (caused by external magnetic fields) is
becoming a much discussed topic but there are currently no published
test methods or criteria for acceptable performance.  The assessment
of image jitter is difficult and requires both trained staff and a
specially prepared test area.

      The following procedure enables such assessment to be simply
and effectively automated:
  1.  The VDU under test (VUT) is placed in a calibrated Helmholtz
coil
       which is connect to a programmable current source, initially
set
       at zero.
  2.  A shielded light sensitive device is attached to the screen of
       the VUT, preferably in one of the corners.
  3.  A programmable pattern generator is connected to the VUT and
used
       to generate a line on the screen of the VUT which is parallel
to
       the field generated by the Helmholtz coil.
  4.  The line is swept across the face of the VUT under program
       control until the light reaching the light sensitive device
       reaches a pre-set threshold; the phase position of the line is
       recorded.
  5.  The programmable current source is set to generate a specified,
       but non-critical, current.
  6.  The line is again swept across the face of the VUT (in the same
       direction as before) until the light reaching the light
sensitive
       devi...