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Technique for CRT Arc Detection in Terminals

IP.com Disclosure Number: IPCOM000099311D
Original Publication Date: 1990-Jan-01
Included in the Prior Art Database: 2005-Mar-14
Document File: 1 page(s) / 42K

Publishing Venue

IBM

Related People

Keidl, SD: AUTHOR

Abstract

A technique is described that allows detection of arc path and the number of arcs that occur. This the destructive problems caused by high voltage in display terminals.

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Technique for CRT Arc Detection in Terminals

       A technique is described that allows detection of arc path
and the number of arcs that occur.  This the destructive problems
caused by high voltage in display terminals.

      A current sampling technique is used to detect arcing in
suspected circuit path.  For example, many CRT arcs flow a DAG return
wire of a CRT arc socket.  For of these arcs, this wire is placed
through the of a ferrite toroid core (see figure).  This becomes
primary of a transformer with a 6-turn secondary.  When arc occurs
within the CRT, the current induced in the secondary is conditioned
by the circuit elements in the figure and fires a CD4047A
single-shot.  The prevents multiple counts of the same arc since arc
waveform is typically a damped sinusoid.  The drives an opto isolator
for remote sensing and stamping of arc occurrence and also a 3-digit
CMOS  The MC14553 counter counts the number of arcs that during a
test interval.  The device is battery for portability and protection
from CRT arc damage. operation is verified for CRT arc voltages
between and 17000 volts.