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Aucbvax.2265 fa.works utzoo!duke!decvax!ucbvax!works Mon Jul 13 09:02:29 1981 Collected commentary on touchpanels >From WorkS-REQUEST@MIT-AI Mon Jul 13 08:37:33 1981 Here are the collected responses to Hal Abelson's query on touchpanels. For your convenience, I have included the initial query message. Enjoy, RDD

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Date: 8 JUL 1981 0755-EDT From: Hal at MIT-MC Subject: speaking of touch panels...

Does anyone know of touch panel technology that is good enough so that one could use it instead of mice? One would need to be able to pick out a region the size of a character. I've heard rumors of systems that allow one to resolve at less than a fingertip's size, but have never seen one in operation. In general, what do people think about the use of mice vs. touch panels vs. whatever?

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Date: 10 July 1981 22:37 edt From: SSteinberg.SoftArts at MIT-Multics (Seth A. Steinberg) Subject: Re: speaking of touch panels...

Elographics makes rather good transparent flexible touch sensitive digitizers which have fingertip style resolution. If you want finer resolution you need a mouse moved around by the finger tip or will have to use a stylus of some type. A TSD with a controller runs in the $900-$1550 range. They will lie flat on Trinitron (cylindrical tubes) but may be troublesome on many other (spherical) tubes.

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Date: 9 Jul 1981 11:03:22-EDT From: cfh at CCA-UNIX (Christopher Herot) Subject: Re: speaking of touch panels...

We use a touch panel made by Elographics in Oak Ridge, Tennessee. It has a resolution of at least 1000x1000, but the accuracy, repeatability, and linearity may cause you problems if you are trying to pick out a single character.

A panel to flush mount in front of a 19" CRT and an RS-232 controller costs about $2100 in single quantities.

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Date: 9 Jul 1981 12:38 PDT From: Farrell at PARC-MAXC Subject: Re: speaking of touch panels...

>From two years' experience with a mouse, I vastly prefer it to anything else I've used. In comparison, a touch panel display has at least three drawbacks:

It has atrocious resolution (~ 1/15 sq. inch, versus the mouse's ~ 1/5000);

It's slower: I have to move much more of my arm to change where I'm pointing on the screen. (Watching my mousing since I decided to answer this, it appears about 70% of the time I don't move any bones above my wrist, once I've grabbed the mouse.) Further, I have to move my arm over a larger distance -- the mouse displacement on the desk is 1/2 that of the cursor on the screen.

It's more fatiguing, partly for the same reasons it's slower. Too, over any length of time, there's a conflict between bad viewing angle if the panel is not upright, and fatigue continually reaching up to it if it is. With the mouse, my wrist rests on the desk; only my hand is cantilevered (and in "think time", my thumb & 2 outside fingers slide down to a rest position straddling the mouse & supporting the rest of my hand -- the only thing left up in the air is my index finger, which I can manage for a *long* time). With a vertically-oriented panel, I have to support everything below my shoulder when I point at the screen.

Using a mouse compares very closely to using a stylus & tablet, with a few differences: It's really handy to have buttons on top of the mouse to mean different things when I point. The displacement ratio mentioned above eases access. The fact that I don't need a big piece of real estate reserved on my desk (and generating unsocial fields of various sorts) is *wonderful*! and the fact that I can raise the mouse, move it a little way in the air, and then return in contact with the desk, means that I can treat it as a track ball. (I wouldn't have believed I'd do that before I started working here, but I do, a lot -- I can move the cursor from the top to the bottom of the screen without raising my wrist off the table, in three "pulls".)

An incidental annoyance with touching what you look at is the fact that nobody's hands are ever clean. A constant problem around here is kids coming in to play on the weekends who aren't used to a mouse, leaving smudgy fingerprints on the screen -- especially bad if the screen has a no-glare coating.

I find two drawbacks to the mouse: I have to move my hands from the keyboard (but the opposite problem, of having to key every action I wish to take, I find much worse); and being something of a slob, I keep clogging the ball with coffee residue, cookie crumbs, etc. Curing the latter requires a mouse without moving parts, or reforming my habits. I anxiously await the former.

Negroponte's group experimented with a display panel which resolved forces (including torques) in the plane of the panel; this allowed considerably more control (e.g. resolution) than a simple pressure at x-y reading. I think you'd have to maintain the sideways pressure constant to stay on something, though, and that would be tedious. Chris Herot (cfh at CCA-UNIX) can tell more about that.

Jerry Farrell

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Date: 09 Jul 1981 1051-PDT From: Tom Wadlow <TAW SU-AI AT> Subject: Touch panels vs. Mice

About a year ago, I participated in the design of a control system for an experimental fusion power system. We used (instead of miles of dials, levers, and switches, as in a conventional fission reactor control system) small color monitors covered with Elographic touch panels. The idea was: Why keep the buttons around when you aren't using them?

Mostly this system is working fairly well. Having used both mice and touchpanels extensively, however, I tend to prefer the mice as pointing devices. The problems with touch panels that I noted are:

- Your hand often gets in the way of seeing what is happening. (Solving this with a pointing stylus means that you might as well be using a light pen instead of a touch panel)

- Your fingertip doesn't have the resolution of a mouse cursor. The Elographics TPs are analog touch panels, not light or wire grids, and have the resolution to let you sign your name with a stylus. You waste most of this with a finger.

- With a vertical screen, your arm gets tired of pointing. We solved this by mounting the screens with TPs as though they were keyboards. Unfortunately, we didn't then have room for keyboards, too. You need both.

- The concept of `clicking' (pointing and then touching one of several mouse buttons) an object is very difficult on a touch panel. It is also very useful.

- Parallax. Even with the TPs mounted directly on top of the glass shield bonded to the front of the CRT, there was a noticeable parallax error between operating from the seated or from the standing positions.

- Calibration. Because of the parallax problem, you had to `teach' the touch panel controller where you thought various points on the screen were. Since portions of the TPs can go `bad' after extended use, they were not permanently bonded to the screen face. This means that the panels might move slightly along the screen face. Thus the calibration had to be redone on the order of once a month.

The arguments I have heard against mice (You have to take your fingers off the keyboard. You need a big empty space next to the keyboard. etc.) are essentially duplicated by or negated when compared to touch panels.

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Date: 9 Jul 1981 1459-EDT From: JWALKER at BBNA Subject: Re: speaking of touch panels...

Frankly I don't like the idea of touching a screen a lot. Might sound silly, but I hate peering at things through a haze of fingerprints and jelly stains.

More seriously, the mice with three buttons give you a lot of codes -- on the LISP machine, operations are usually set up to take one or two clicks on each of the 3 buttons. So the mouse both selects an object to operate on and at the same time, lets you choose one of 6 things to do. A touch panel would seem to allow much less flexibility in command interface design. Touch an object to select it... OK, now what? Knock once to do this, knock twice to do that. you'd start to feel like Clever Hans (the horse who answered questions by pawing on the ground).

I guess you could have a menu appear and then touch that to select what to do (replacing the button clicks). This has the disadvantage of requiring more hand motion. Also your hand comes between your eyes and the screen more that way.

Jan

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Date: 9 July 1981 1457-EDT (Thursday) From: Joe.Newcomer at CMU-10A Subject: Re: speaking of touch panels...

I don't understand why people seem to want touch panels instead of mice or tabletop tablets. The reaching motion required to move a mouse is a very natural one, and has the advantage that the finger and hand do not obscure the object being pointed to. Reaching up to touch a screen, or bending over to see a screen placed flat on the table would drive me crazy. How would one seriously edit on such a terminal? Besides, how often will you have to clean the fingerprints off the screen? I know there are some very good touchscreen-based systems around (e.g., PROMIS), but they are working in a very restricted application domain. There are a number of cheap tablets around right now (for example, one that is available with the Perqs) and even the more expensive Bit Pad tablets are not all that expensive. I've used some early touchscreens, mice, and tablets, and I much prefer the mouse or flat-cursor tablet for accuracy, resolution, fine control, and overall convenience. Light pens and touch screens don't seem to be in the same class. I have never tried joysticks or tracking balls, but evidence suggests that joysticks are really big losers. See Stu Card's thesis, or the latest issue of Computing Surveys (particularly the bibliographies) for various studies. joe

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Date: Friday, 10 Jul 1981 15:07-PDT From: obrien at RAND-UNIX Subject: Re: speaking of touch panels...

I've used one type of touch panel quite extensively. Basically they're good only for menu selection, and don't give quite the feedback that a mouse does in that there's no cursor to drag around. Also they sometimes give false readings. So do mice, when their wheels get stuck, but since they're just sending out positional change, and not absolute position, they don't give results as wildly wrong as touch panels sometimes do. On the other hand touch panels get coffee spilled on them far less often and don't have any moving parts.

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Date: 9 Jul 1981 1256-EDT From: PRSPOOL at RUTGERS Subject: High Resolution Touch Screens

I don't see high merit to Touch Screens with discrimination of areas smaller than a fingertip. If a Touch Screen had the ability to discriminate individual characters, what should be used to point? If the purpose of the Touch Screen is convenience, then one would like to use one's fingertip. Taking the time to lift one's hands off the keyboard is only a slight annoyance; needing the extra time to pick up a pencil or stylus to point to something on the screen seems much more annoying to me. For menu-type applications, I would prefer menu items which were short words or icons over the use of single letters for choices.

--Peter R. Spool

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Date: 9 Jul 1981 09:32 PDT From: McBain.ES at PARC-MAXC Subject: Re: speaking of touch panels...

I've done some experimenting with a coarse resolution touch panel which seems to get good results for a limited set of cases. If the cursor is moved toward the touched spot (rather than to it), then the resolution of the cursor position approaches the resolution of the screen (rather than the resolution of the touch panel). To avoid the feeling of a very slow response, I used a non linear (accelerating) method. The cursor approached the touched spot faster as the spot was touched longer. If the touching finger was in motion, the cursor moved more slowly, giving the feel of a docking maneuver.

The technique doesn't seem very good for fast use (like a fast editor would expect), but was quite satisfactory where there was more think time involved.

/Dwight

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Date: 10 July 1981 12:28 edt From: MPresser.Multics at MIT-Multics Subject: Re: speaking of touch panels...

For a few months I worked on a research project at MIT on a touch sensitive panel, accurate to about 3/8'ths of an inch, the universal fat finger. We ran the thing, with an extensive software system to "understand" the menu being presented, or non-menu, if the user was drawing on the keyboard. Last I heard, a place in Wilmington, MA called SST had picked the thing up and had even made a public announcement about it. I have no idea if the company if still around , or of the state of their terminal. If anyone is interested, I can discourse on what I know of the prototype version. Marshall Presser

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Date: 9 July 1981 08:29-EDT From: John Howard Palevich <TANG AT MIT-AI> Subject: speaking of touch panels...

I have always been a great fan of Track balls ("golf balls", "dead mice", "the thing that's on Atari's Football & Missile Command", "the thing that NORAD uses instead of a joystick"). For many applications, a track ball (or one of those "capacitive activated transducers (CATs) from the Xerox 850) would strike me as better than either a joystick, a light pen, a mouse, or a touch sensitive screen. Track balls & Cats could be put right there on the keyboard, which means the hand doesn't have to move very far and that one isn't tied into the "CRT within arms' reach of the user" design. I find that a Track ball lets me use the palm of my hand for quickly moving to a point on the screen, then delicate fingertip control for fine positioning. And, unlike a light pen (or a mouse on a cluttered desk) the track ball tends to stay where I put it!

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Date: 10 July 1981 2305-EDT From: BNH at MIT-ML Subject: touch-panel mouse substitute

This may be a silly question, but... What's wrong with light pens? Given that technology has improved somewhat since the days when they were unreliable and large and required much-too-intense light sources, why not use one? Surely pointing at the screen with a stylus is no more unnatural than doing a coordinate transformation in your mind to get the mouse on the screen to the proper point by using the mouse on your desk? This isn't what you asked, but may be cheaper and more widely implementable. Brian

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End of collected commentary on touchpanels ******************************************

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