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<p>Robin</p>
<p>My observation of the Blue background LCD's is that they are inverse of the Yellow ones. ie the pixel is clear or see through rather than blocking.</p>
<p>They tend to ghost more, and hence you need to scroll them slower.</p>
<p> </p>
<p>Mark</p>
<p> </p>
<p>On Sun, 09 Aug 2015 21:03:11 +1200, Helmut Walle wrote:</p>
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<pre>On 09/08/15 14:10, Robin Gilks wrote:</pre>
<blockquote type="cite" style="padding-left:5px; border-left:#1010ff 2px solid; margin-left:5px; width:100%">Greetings all I've only ever used green and yellow HD44780 style character mode LCDs and they have had a backlight (which draws a LOT of current) but been perfectly readable without the backlight being on. I'm now playing with a blue one and the backlight has to be on to read it - is this normal for blue LCDs ? I haven't checked the current yet (rebuilding alpha hardware into beta stage prototype) but I'm guessing its quite low since modern blue LEDs seem to be very efficient. Cheers</blockquote>
<pre>Differences in daylight readability between reflective and transmissive
LCDs maybe? And backlights for LCDs have not always been LED... for
example, if you are buying an "LED" TV today in many cases that means
the backlight for the LCD is made up from LEDs, rather than the fluoro
tubes that were standard for decades until recently. However, backlights
for smaller LCDs often were incandescent bulbs back in the last
millennium, and LEDs have been in use there for quite a while (much
longer than for bigger LCDs).
How much current is "a LOT"? I would expect an LED backlight for a small
module, say anything up to 4 x 16 character, to be around tens of
milliamps at most. It it draws a LOT more I would suspect either a fault
or a non-LED technology. You can find out the technology either by
opening it up or by driving it with a rather low current - if it's an
incandescent backlight it won't produce visible light at low current,
while an LED will...
Kind regards,
Helmut.
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