HP 150 Touchscreen

From: ss_at_allegro.com <(ss_at_allegro.com)>
Date: Mon May 10 12:05:31 1999

Re:

> I've been playing with a HP 150 recently. Do any of you physicists out there
> know how the touch screen works? The electronics for it surround the screen
> but don't seem to contact it. Some sort of static electricity capacitive
> effect on one's finger?

Infrared beams...at least for the HP 150 A and B.

The first two models had visible holes where dust could get in and obscure
the IR LEDs. Later, HP added an IR-transparent bezel over them to avoid
that problem.
Received on Mon May 10 1999 - 12:05:31 BST