Interesting stuff about printers, suitable for RP and part marking

Firstly Parallax did a bit of a competition using HP print heads:

http://www.parallax.com/html_pages/products/hpinkjetcontest/inkjetcontest.asp

They produced a controller that takes serial commands and produces
voltages for the print head.

They have also produced some documentation and have opened up the
design for anyone to use, have a look at:

http://www.parallax.com/dl/docs/prod/robo/InkjetKitDocs-v1.0.pdf

And go straight to page 33 to see the schematic. Also have a look at
the BOM on page 16 and the actual board on page 6. So although you
can buy this board you could easily build something similar yourself
uisng the uP of choice.

Basically they are just switching 24v to the inkhead elements using
some ULN2803 darlington arrays. The longer the pulse the more ink
sprayed I guess.

Now check out the videos at the bottom of this page:

http://www.parallax.com/detail.asp?product_id=27949

I think the "SX Handheld Printer" says it all. The guy is just waving
the print head around and it is printing on the paper. That itself
would be a cool thing for marking boxes if combined with a small
screen and keyboard.

All you have to do to put it into automated use is syncronize the
printing with the motion, most of us use step and direction control so
this becomes very simple. You could use it for marking out things,
adding text to parts to aid assembly, for a homemade starch based RP
machine and for loads more stuff.

Presumably the Epson print heads though piezo based will be similarly
easy to drive and make supplying different media more simple.

Just some food for thought

Graham