(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.