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.