[GreenKeys] Inktronic

[John Nagle]

> From: Jim Haynes<jhhaynes at earthlink.net>
> Subject: Re: [GreenKeys] model 40 update - no suprise on the type
> 	carrier aka belt
>
> On Wed, 1 Jun 2011, Gerry Block wrote:
>
>> Jim I've never seen the inktronic but from what I've read over the years I
>> thought they were designed to spray paint everything but the paper.
>> ?
> I first saw the Inktronic principle demonstrated in 1959, printing on a
> strip of paper tape.  If there had been a market for a high speed tape
> strip printer it might have been a real winner.  The problems got a lot
> worse when it was made into a page printer, with 40 nozzles to print
> 80 columns.  As it came from the factory the print was readable across
> the page; but things went downhill from there.  I guess the main problem
> was paper dust getting attracted to the electrodes, which were in the
> open air.  It was very hard to clean the electrodes without bending
> them, which caused distortion of the printing.    There was a problem
> getting ink droplets of uniform size to come out of the nozzles.
> All in all, a clever idea but not very practical.

     The Teletype Inktronic was an interesting concept.  The idea was
straightforward - generate a stream of ink droplets and deflect them
with electrostatic deflection plates, like an oscilloscope tube.
Doing this in air was tough, and too dependent on humidity.

     Also, at the time, ink droplet formation wasn't well understood.
It turns out that intuition fails you at that scale, where turbulence,
surface tension, and bonding forces dominate.  HP had to resort
to fluid dynamics simulations to figure out how to make a reliable
droplet emitter.

     For background on this, see

	http://doc.utwente.nl/58366/1/thesis_Wijshoff.pdf

     The Inktronic is mentioned on page 4.

						John Nagle