"Gareth Magennis" wrote in message
...
"IanM" wrote in message
...
Arfa Daily wrote:
"N Cook" wrote:
Kit often used in bad lighting and no built in illumination , gooseneck
illuminator would be awkward.
Complex 2 inch square one with only zebra spacing, so indirect side
illumination. Intend 2 bright white 5mm LEDs angled into the LCD glass
or
would some thin translucent white perspex/luxite in the zebra space make
for
better illumination. Just thin white backing sheet there at the moment.
--
Diverse Devices, Southampton, England
I'm not sure that you are going to have too much success with this. I
have tried before to light displays that were not intended for it, and
have never managed to get enough light in there to make it work. On
transreflective types, the reflective surface is, I seem to recall,
bonded to the back face of the glass panel, to maximise the light
reflection back through the panel, and minimise the losses. The light
output from high intensity white LEDs is also pretty narrow angled, so
you might struggle to get even illumination across the display surface,
if you attempt to side inject it. How about a couple of the surface
mount LED 'bars' that you can get now, perhaps fixed along the two long
edges of the display, casting their light across its surface. I'm sure
that with a bit of imagination, they could be shrouded and fixed on in a
way that looked ok. Can't remember where I saw them now, but I'm sure
that one of the newsletters that I get from suppliers, or a mag advert
somewhere, showed some bars that were 'snap-off' to the length / number
of LEDs that you needed. Googling might turn up something along those
lines.
Arfa
You *could* add an EL backlight replacing the backing sheet. The
following link may be usefull if you dont have any scrap EL backlight
LCDs to cannabalize.
http://electroluminescence-inc.com/customPattern.htm
They have a A5 size blue green cut to size EL sheet for $26. You could
get 8 2" square (+ contacts on one end) pieces out of that.
RS have a suitable product as well.
http://uk.rs-online.com/web/2678728.html
Seikosha White electro-luminescent sheet 60x50mm (you can trim it to
size)
You'd also need an inverter (backlight driver) for either product
http://uk.rs-online.com/web/2678857.html
12V 45ma supply. 5V model also available, less than 1" cube.
HTH.
Ian.
I've done this quite a lot in the past. There are a few things to note
though.
The sheet on its own is useless, there is no way to atatch the wires, as
it is plastic. (except maybe conductive epoxy which I'm sure I tried years
ago without success)
What you need is the kit, which contains terminal strips and the all
important conductive glue pads to attatch them to the sheet. Farnell
sells this.
The back of the sheet is one of the conductors, so this should be
insulated. I use electrical tape. Hot lamination machines destroy the
sheet. There are cold laminators available.
You cut the sheet to size using scissors, though I have read that if you
don't seal the edges, the sheet can start to fail round the edges as
moisture gets in. (unsubstantiated claim). I fold the elctrical tape
over them.
Sometimes after all your efforts they do not work, as the two terminals
become shorted. This could happen during the cutting with scissors
operation, I don't know, I just stat again.
The sheets are very expensive - make a careful note of the sizes and how
many backlights you can make out of them - some sizes wll provide only a
couple of strips and a lot of wasted sheet due to their dimensions and the
way the borders are made. Much more economical to get the larger sheets.
I did have one occasion where the display would not accept the backlight
at all - the original was LED, and I assume the invertor drive (around
100v a.c) interfered with the electronics.
You can get these pre-made on Ebay. That might actualy be your best
option given the above.
Gareth.
I haven't tried this but there is also a product called EL wire or
"Glow-Wire". It is a flexible plastic fluorescent tubing, powered with an
inverter in the same way as EL sheet. RS and Farnell stock this stuff but
at a massively inflated price compared with what you can get it for from the
club / entertainment industry. (Google Glow Wire) Seems to be very cheap in
bulk from the States.
http://uk.farnell.com/jsp/search/bro... EL+wire&Ntx=
You might be able to run some of this under or around the display, but
you'll still need an invertor.
Gareth.