Path: utzoo!attcan!uunet!husc6!cmcl2!nrl-cmf!ames!pasteur!ucbvax!dewey.soe.berkeley.edu!oster From: oster@dewey.soe.berkeley.edu (David Phillip Oster) Newsgroups: comp.society.futures Subject: Re: Personal Computing in the Year 2000. Summary: hand on the tablet, no problem. Keywords: input Message-ID: <24841@ucbvax.BERKELEY.EDU> Date: 26 Jun 88 00:25:09 GMT References: <8806251950.AA18594@bu-cs.bu.edu> Sender: usenet@ucbvax.BERKELEY.EDU Reply-To: oster@dewey.soe.berkeley.edu.UUCP (David Phillip Oster) Organization: School of Education, UC-Berkeley Lines: 19 Actually, the hand resting on the sensitive surface is more of a problem with current digitizing tablets than it would be with Tablet=dynabook. Some tablets work by broadcasting low power radiowaves. The problem is, the hand acts as an antenna. I've held the official stylus in one hand, and got the cursor to track using my the bare index finger of my other hand, tracing on the tablet! Tablet=dynabook can deal with this easily: if the input behavior looks like writing with a stylus, then ignore the large, mostly static lump below the penpoint. We know that the input manager of Tablet sees the entire faceplate as a bitmap: you login by just placing your hand on the faceplate. Current tablets just return the x,y coordinates of where it thinks the pen is. Put your hand near it, while you are holding the pen, and those x,y s change slightly. Many pressure to electricity trnasducers, (for example piezo-electric crystal) are bi-directional: press on it, you get a current. Send a current to it, it deforms slightly. The dynabook I designed in '77 used this effect to use its entire faceplate as a speaker/microphone.