[chbot] Blue HD44780 LCDs

[m.beckett at amuri.net]

Robin 

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. 

They tend to ghost more, and hence you need to
scroll them slower. 

Mark 

On Sun, 09 Aug 2015 21:03:11 +1200, Helmut
Walle wrote: 

> On 09/08/15 14:10, Robin Gilks wrote:
> 
>> 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
> 
>
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.
> 
>
_______________________________________________
> Chchrobotics mailing
list Chchrobotics at lists.linuxnut.co.nz [1]
>
http://lists.ourshack.com/mailman/listinfo/chchrobotics [2]
> Mail
Archives: http://lists.ourshack.com/pipermail/chchrobotics/ [3]
>
Meetings usually 3rd Monday each month. See http://kiwibots.org [4] for
venue, directions and dates.
> When replying, please edit your Subject
line to reflect new subjects.

  

Links:
------
[1]
mailto:Chchrobotics at lists.linuxnut.co.nz
[2]
http://lists.ourshack.com/mailman/listinfo/chchrobotics
[3]
http://lists.ourshack.com/pipermail/chchrobotics/
[4]
http://kiwibots.org
-------------- next part --------------
An HTML attachment was scrubbed...
URL: <http://lists.ourshack.com/pipermail/chchrobotics/attachments/20150811/17c45907/attachment.html>