September 21, 2005
LEDs as input devices?!?
I came across Multi-Touch Sensing through LED Matrix Displays in a posting on the synth-diy mailing list. After some extended googling I found the notes from Forrest M Mims that Jeff Han referenced in the above link. It turns out that LEDs work as very narrowband (50nm) detector, producing around 2-5 microamps depending on the LED. The LED's peak sensitivity is about 30nm shorter than its emitted wavelength, so red emitters work great with yellow-orange LEDs as detectors, yellow emiiters work well with green LED detectors, and so forth. I already have a great idea about using bicolor LED dot matrix displays for real time interactive displays.
Posted by cary at September 21, 2005 02:58 AM