Today I found an old First Alert timer that was in the shed, about to be discarded. So I salvaged the cabinet which was pretty nice, and the internal boards for the 12VDC supply parts. While taking it apart I also got an LCD:
From the 16 contacts on the board I suppose it's probably some kind of HD77480 variety. Unfortunately the timer's dead so I can't really test anything out. I guess it's probably another misc part that's not usable. But... I am curious to find out what I'm looking at.
There's no metallic contacts on the LCD itself. And no wiring. There was a black sponge (visible in the photos) sandwiched between the glass LCD and the board. If I tilt the LCD I can see very faint transparent markings in the glass that seem to have the same shape as the contacts on the board. On one side of the sponge I can also see contact markings, but on the other side nothing.
So, how does this work? I suppose the electrical current goes from the board to the display through the sponge... what exactly is that sponge made out of? Are there discrete conductors inside it, or is it one single conductive piece? And how does the current get to the LCD itself if it's all encased in glass, with no metal contacts anywhere?