Newsgroups: sci.electronics
Path: utzoo!henry
From: henry@zoo.toronto.edu (Henry Spencer)
Subject: Re: Life of LCD Panels
Message-ID: <1990Jun29.150402.6752@zoo.toronto.edu>
Organization: U of Toronto Zoology
References: <25269@unix.cis.pitt.edu> <3922@memqa.uucp>
Date: Fri, 29 Jun 90 15:04:02 GMT

In article <3922@memqa.uucp> r91400@memqa.uucp (Michael C. Grant) writes:
>	The problem is that no XOR gates (or square waves) are perfect, and
>some DC potential is applied to the cell...

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.
-- 
"Either NFS must be scrapped or NFS    | Henry Spencer at U of Toronto Zoology
must be changed."  -John K. Ousterhout |  henry@zoo.toronto.edu   utzoo!henry