Path: utzoo!utgpu!news-server.csri.toronto.edu!rutgers!apple!portal!cup.portal.com!ISW
From: ISW@cup.portal.com (Isaac S Wingfield)
Newsgroups: sci.electronics
Subject: Re: Life of LCD Panels
Message-ID: <31306@cup.portal.com>
Date: 1 Jul 90 06:41:56 GMT
References: <25269@unix.cis.pitt.edu> <3922@memqa.uucp>
  <1990Jun29.150402.6752@zoo.toronto.edu> <25522@unix.cis.pitt.edu>
Distribution: na
Organization: The Portal System (TM)
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In article <1990Jun29.150402.6752@zoo.toronto.edu> henry@zoo.toronto.edu (Henr
 Spencer) writes:
 >However, 4000-series CMOS gates are pretty close to perfect for this. :-)
 >Still, the point is valid:  even the slightest DC offset will eventually
 >degrade the LCD.  Basically, it causes electrolytic reactions of various
 >kinds, as I recall.  With a perfectly symmetrical AC wave, e.g. square
 >wave, reactions during one half of a cycle reverse themselves (you hope)
 >in the other half.

If memory serves, it's simple electroplating that's the problem. Any voltage
will cause one or the other of the tim oxide electrodes to migrate, but if the
waveform is perfectly symmetrical, equal amounts move each way. With any DC
component, however, eventually one electrode will vanish.


Isaac
isw@cup.portal.com