First of all let me state that touch screens are the best user-interface
that I have encountered.  There a couple of facts that need to be
straightened out...
 
Mr. Chadwick, only certain types of touch screens develop wear areas and
become insensitive - generally these are the cheaper resistive type touch
screens (I could go into detail).  SAW (Surface Acoustic Wave) touch
screens are made of glass and do not have this problem... I also believe
that the capacitive touch screens are also immune to this problem as they
are made of glass, but I'm not 100% sure.  Elographics manufactures the
SAW type screen (along with cheaper resistive types) and MicroTouch
manufactured the capacitive type screen.  We have had an Elographics SAW
touch screen for a few years now and it performs well.  I recently
evaluated and purchased the Microtouch touch screen and it responds
faster then the SAW type touch screen and does not get "confused" if it
receives input from several areas of the screen simultaneously (if
someone places their whole hand on the SAW, it takes a couple of seconds
to get it bearings again).  Just to be fair, it's not like the SAW is
slow to respond, it's just that if people don't see an immediate reaction
to their touch they spaz out and begin to touch other areas to try to get
a response.  Also, I'm running the SAW on a 386/40, so it's possible that
with a faster computer there would be no perceptable lag.
 
Another gentleman mentioned the arcade style trackballs and how durable
they were.  Commercial grade trackballs are durable... last time I priced
one I was quoted $800.00 by the manufacturer.  Besides... ANY mechanical
device will fail and depending on the visitor traffic in your museum, you
could easily go through even the most durable trackball in a year.  Let's
face it, people have dirt on their hands and bodies... this dirt will
work it's way into the trackball and cause it to act erratically and
eventually fail.  Dirt (and water for the SAW) can effect the performance
of a touch screen, but all you have to do to "repair" it is wipe it off.
 
As for joysticks... they can be broken easily and unless your exhibit is
a flight simulator, it's not an intuitive user interface.  I have watched
people of all ages walk right up to a touch screen exhibit and begin to
operate it right away... people always seem to want to touch a monitor.
How well they do from there depends on how well you developed your user
interface and your application.
 
As for budget considerations... get the money you need to build the
exhibit right the first time or be prepared to deal with the frustration
of visitor complaints and constant repair.
 
Mark C. Vang
Exhibit Technician
 
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