[chbot] Blue HD44780 LCDs

[Mark Atherton]

Hi Robin,

There are several polarizer technologies available to LCD manufacturers. 
One type requires a backlight, others are available that are viewable in 
direct sunlight. It could a swap between these when you moved to the new 
LCD which has caused the issue (or affected your expectation). See 
http://www.lxdinc.com/faq/difference_between_reflective_and_transreflective

Older LED backlights have sometimes needed upwards of 80mA to squeeze 
some light through-the-shutter while newer are much less hungry.

So there are lots of things that affect readability, see if complete 
datasheets are available for the units you are happy and unhappy with 
and see if you can find the parameter in question which is different.

-mark


From: "Robin Gilks" <robin at gilks.org>
> 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
>
> -- 
> Robin Gilks
>

-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ourshack.com/pipermail/chchrobotics/attachments/20150810/d508d784/attachment.html>