Thilo Klein wrote:
>> Was that a button
>> press, or someone picking the  unit up?
> 
> The last question is a riddle.

It was one of my stumpers.  Best I could do was to add a second "enable 
button," either opto or conventional, on the side or someplace where 
you'd be unlikely to push both at the same time... but that's not very good.

>> What are the main criteria that attract you to the optical button? 
> 
> Mainly effortlessly fast pushing and releasing. I tested it yesterday
> and it is an awesome feeling.

It is a very cool feeling.  Fast and silent.

Effectively, the opto approach reduces the required actuation pressure 
to zero.  Whether this is a good thing or a bad thing depends entirely 
on the application.

You might look at capacitive touch sensors as well - similar effect, 
different mechanism, maybe more widely implemented so you could see if 
there are some tricks you could borrow.
-- 
Timothy J. Weber
http://timothyweber.org
-- 
http://www.piclist.com PIC/SX FAQ & list archive
View/change your membership options at
http://mailman.mit.edu/mailman/listinfo/piclist