Retrofit LCD display light - any tips?

[N Cook]

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
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[Archon]

hr(bob) hofmann@att.net wrote:

On Oct 6, 6:42 am, "N Cook" <diver...@gazeta.pl> 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
electronic hints and repair briefs , schematics/manuals list onhttp://home.graffiti.net/diverse:graffiti.net/

Can't figure out what you're talking about. You have such a light and
want to figure out what you can do withit????

Take a look at the Philips scopes LCD display backlight, the lamp is in
the "L" shape perspex running the length of the display (lower images)

http://www.jetecnet.com/Scopes/backlight.html

Basically a piece of Perspex to the rear of the display with a milled
out lamp hole, internal reflection lights the display from the rear.
maybe do the trick? The gap behind these displays is however quite
large, 3-4mm so you may not have sufficient thickness.

JC

 

[hr(bob) hofmann@att.net]

On Oct 6, 6:42 am, "N Cook" <diver...@gazeta.pl> 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
electronic hints and repair briefs , schematics/manuals list onhttp://home.graffiti.net/diverse:graffiti.net/

Can't figure out what you're talking about. You have such a light and
want to figure out what you can do withit????

 

[Arfa Daily]

"N Cook" <diverse8@gazeta.pl> wrote in message
news:gcctl5$ovk$1@inews.gazeta.pl...

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
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

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

 

[N Cook]

Archon <Chipbee40_SpamNo@yahoo.com> wrote in message
news:SHzGk.955910$I42.758888@fe04.news.easynews.com...

hr(bob) hofmann@att.net wrote:
On Oct 6, 6:42 am, "N Cook" <diver...@gazeta.pl> 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
electronic hints and repair briefs , schematics/manuals list
onhttp://home.graffiti.net/diverse:graffiti.net/

Can't figure out what you're talking about. You have such a light and
want to figure out what you can do withit????


Take a look at the Philips scopes LCD display backlight, the lamp is in
the "L" shape perspex running the length of the display (lower images)
http://www.jetecnet.com/Scopes/backlight.html

Basically a piece of Perspex to the rear of the display with a milled
out lamp hole, internal reflection lights the display from the rear.
maybe do the trick? The gap behind these displays is however quite
large, 3-4mm so you may not have sufficient thickness.

JC

The problem here is the LCD backing plastic has some legends and segment
marking on it, associated with reading the LCD, and is not translucent
enough to pass much light through. So having to pass light into the glass of
the LCD. Have painted the inside of the well in the plastic outer casing,
that receives the LCD panel, with white correction fluid to reflect back
some of the light from 2 bright white LEDs mounted at one edge and angled
diagonally. Not ideal but gives just about adequate illumination.

But I can launch the LED light straight to the LCD glass edge, unlike your
scope example where the light has to go round the bend. I will try a photo,
under this LED light, when completed.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/

 

[IanM]

Arfa Daily wrote:

"N Cook" <diverse8@gazeta.pl> 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.

 

[Gareth Magennis]

"IanM" <Invalid@totally.invalid> wrote in message
news:gcfc3b$267s$1@energise.enta.net...

Arfa Daily wrote:
"N Cook" <diverse8@gazeta.pl> 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.

 

[Gareth Magennis]

"Gareth Magennis" <sound.service@btconnect.com> wrote in message
news:d_ednU2gvZkX3XbVnZ2dneKdnZydnZ2d@bt.com...

"IanM" <Invalid@totally.invalid> wrote in message
news:gcfc3b$267s$1@energise.enta.net...
Arfa Daily wrote:
"N Cook" <diverse8@gazeta.pl> 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/browse.jsp?N=500005+1000037&Ntk=gensearch_001&Ntt=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.

 

[N Cook]

Arfa Daily <arfa.daily@ntlworld.com> wrote in message
news:AzFGk.3467$iL2.1008@newsfe30.ams2...

"N Cook" <diverse8@gazeta.pl> wrote in message
news:gcctl5$ovk$1@inews.gazeta.pl...
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
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/




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

My camera does not work well enough at low light levels to produce an image
worth capturing. But visibly works well enough with, 2 off, using 25mA white
5mm LEDs angled diagonally. The white tippex on the other side works quite
well, in reflecting back some, for filling in the opposite side of the LCD.

Not the sort of kit that justifies electroluminescent panels and inverters
etc, just a get by solution was fine. A "Saltire" illumination pattern was
acceptable here.


--
Diverse Devices, Southampton, England
electronic hints and repair briefs , schematics/manuals list on
http://home.graffiti.net/diverse:graffiti.net/