remote control light

[Herb]

(I'm having difficulty zeroing in on this in web/Usenet searches,
because the common words lead to other subjects.)

I have a Radio Shack 4-in-1 remote control for the tv, with a button
that lights up the keys, for night use. However, there is something
now wrong with it. Only the top keys were illuminated anymore.

So I opened it up and lo and behold... there is no bulb that I could
locate. Where does the light come from? It's a mystery. To top it off,
the floppy soft-rubber piece that comprises the keys must have shifted
or something, because now the pattern of light vs dark keys is all
over the place.

What key words can I use to search and read up on this lighting?
Thanks.

 

[hr(bob) [email protected]]

(I'm having difficulty zeroing in on this in web/Usenet searches,
because the common words lead to other subjects.)

I have a Radio Shack 4-in-1 remote control for the tv, with a button
that lights up the keys, for night use. However, there is something
now wrong with it. Only the top keys were illuminated anymore.

So I opened it up and lo and behold... there is no bulb that I could
locate. Where does the light come from? It's a mystery. To top it off,
the floppy soft-rubber piece that comprises the keys must have shifted
or something, because now the pattern of light vs dark keys is all
over the place.

What key words can I use to search and read up on this lighting?
Thanks.

Just play with it, there are Light emitting diodes that are used for
illmination, they are about the size of the head of a pin for most of
these applications. If you want to play fine, if you need a remote,
its time to go to your nearest all-0purpose store and buy one for
under $10.00 USA.

H. R. (Bob) Hofmann

 

[Gary Tait]

So I opened it up and lo and behold... there is no bulb that I could
locate. Where does the light come from? It's a mystery. To top it off,
the floppy soft-rubber piece that comprises the keys must have shifted
or something, because now the pattern of light vs dark keys is all
over the place.

What key words can I use to search and read up on this lighting?
Thanks.

Its just LEDs. Small ones. Likey a resistor or a broken trace is the
culprit.

 

[Herb]

Just play with it, there are Light emitting diodes that are used for
illmination, they are about the size of the head of a pin for most of
these applications.

well no, as I'd said, this is different. I experimented and see that
it is some unusual device. There is a plastic film with wide, donut
shaped white traces that light up. The white center dot makes the
connection when a key is pressed, but the rings light up.
http://img514.imageshack.us/img514/6969/remoteta0.jpg

The links between rings don't seem to be broken. Maybe this material
just wears out. Or, it's maybe a problem with contact. I tried it
with the cover removed and see that the spots that light up are
scattered.

 

[Gary Tait]

well no, as I'd said, this is different. I experimented and see that
it is some unusual device. There is a plastic film with wide, donut
shaped white traces that light up. The white center dot makes the
connection when a key is pressed, but the rings light up.
http://img514.imageshack.us/img514/6969/remoteta0.jpg

The links between rings don't seem to be broken. Maybe this material
just wears out. Or, it's maybe a problem with contact. I tried it
with the cover removed and see that the spots that light up are
scattered.

It could be EL (Electro luminescent) material.
Is there a small transformer on the board?

The EL trace could be broken, which you may be able to repair with metallic
ink.

 

[Homer J Simpson]

well no, as I'd said, this is different. I experimented and see that
it is some unusual device. There is a plastic film with wide, donut
shaped white traces that light up. The white center dot makes the
connection when a key is pressed, but the rings light up.

Like the watches?

 

[Herb]

It could be EL (Electro luminescent) material.
Is there a small transformer on the board?

Yes, there is a small transformer on the other side of the board.

I noticed today, in a darker environment, that every ring has at
least a speck that is lighting. So that new observation tends to go
against the idea of a broken trace, I'd think.

Using the term you've provided, I found a journal abstract which
describes a type of failure:

http://pubs.acs.org/cgi-bin/abstract.cgi/langd5/1998/14/i20/abs/la9709406.html

"...defect on the indium tin oxide anode. These spherulites cause the
device to delaminate, and this results in a decrease in the
luminescence around the defect and, finally, the failure of the
electroluminescent device."

Degradation of Organic Electroluminescent Devices. Evidence for the
Occurrence of Spherulitic Crystallization in the Hole Transport Layer

Sounds unrepairable, I'd guess.

The EL trace could be broken, which you may be able to repair with metallic
ink.

And yes, I suppose it is just like the stuff on the watch I'm wearing
- though much brighter and lots more area of it.

They should make computer screens out of this stuff