On Thu, May 29, 2008 at 7:33 AM, Federico Lorenzi <[EMAIL PROTECTED]> wrote: > Not really, normal touch screen tablets have a capacitive touch > screen, which is why they usually only work with a special pen, and > you can rest your hand on them. Correcting myself - from Wikipedia: Passive tablets, most notably those by Wacom, make use of electromagnetic induction technology, where the horizontal and vertical wires of the tablet operate as both transmitting and receiving coils (as opposed to the wires of the RAND Tablet which only transmit). The tablet generates an electromagnetic signal, which is received by the LC circuit in the pen. The wires in the tablet then change to a receiving mode and read the signal generated by the pen. Modern arrangements also provide pressure sensitivity and one or more switches (similar to the buttons on a mouse), with the electronics for this information present in the pen itself, not the tablet. On older tablets, changing the pressure on the pen nub or pressing a switch changed the properties of the LC circuit, affecting the signal generated by the pen, which modern ones often encode a digital data stream onto the signal. By using electromagnetic signals, the tablet is able to sense the stylus position without the stylus having to even touch the surface, and powering the pen with this signal means that devices used with the tablet never need batteries. Wacom's patents don't permit their competitors to employ such techniques.
Cheers, Federico _______________________________________________ Openmoko community mailing list [email protected] http://lists.openmoko.org/mailman/listinfo/community
