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From: nadst2@unix.cis.pitt.edu (Nilanjan Adhikari)
Newsgroups: sci.electronics
Subject: Re: Life of LCD Panels
Message-ID: <25522@unix.cis.pitt.edu>
Date: 29 Jun 90 21:57:33 GMT
References: <25269@unix.cis.pitt.edu> <3922@memqa.uucp> <1990Jun29.150402.6752@zoo.toronto.edu>
Reply-To: nadst2@unix.cis.pitt.edu (Nilanjan Adhikari)
Organization: Univ. of Pittsburgh, Comp & Info Services
Lines: 15

In article <1990Jun29.150402.6752@zoo.toronto.edu> henry@zoo.toronto.edu (Henry 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.
>-- 

  It appears that the degradation requires a dc field to be present.
Does that mean that for intermittently used lcd's (like those in a
camera or a calculator), the degradation is practically of no concern ?
Do lcd's deteriorate over time anyway, whether or not they are turned
on ?  I came to know that Canon warns about a possible degradation of
the lcd panels in their EOS series cameras after about five years.