speaking of displays & DPM

[dzorde at aesprodata.com.au]

     You'll find that as LCD's heat up you need to reduce the contrast 
     voltage (and it's not linear either).  Once you actually hit about 
     65?C the LCD will turn blue due to the heating of the crystals. The 
     easiest way to overcome any problems is to keep the LCD out of direct 
     sunlight and use a display with external contrast adjustment, set up a 
     compensation curve in the CPU and drive the contrast through a digital 
     pot and an opamp circuit.
     
     Dan        dzorde at aesprodata.com.au 


______________________________ Reply Separator _________________________________
Subject: Re: speaking of displays & DPM
Author:  diy_efi at coulomb.eng.ohio-state.edu at INTERNET
Date:    8/27/96 6:37 AM


>Maybe I have an odd LCD pannel (2x20, I doubt it). Mine turns black when the 
>car warms up in the sun.
>
     
Don't know -- only know what specs I am familiar with -- maybe something 
new ??  Don't think so, but maybe.  LCD specs (that I read umpteen years 
ago) say they don't work as well in the cold, get sluggish and go blank. 
I have experienced the problem you speak of -- think it must be an 
artifact of type of LCD or manufacture process ??  But that seems to only 
be isolated to certain displays.
     
I use LCD's in my car with no problem -- not even in 'cold' (except when in 
mountains in N.M. when it got into the teens -- then they went blank).