Homebrew PCBs

--- In Homebrew_PCBs@yahoogroups.com, Len Warner <yahoo@...> wrote:
>
> On Tue, 18 Apr 2006 at 23:54, Robert Hedan top-posted,

> >No, that's the strange part.  Black, red and yellow were replacement
> >cartridges she bought at Staples; those 3 don't work any more.  Blue is
> >stock Epson, and that one still works.
> >
> >Maybe the Staples ink dries/clogs faster?
> 
> Or maybe the surface tension is wrong and it falls out of the
> cartridge easier: that's one of the problems I have refilling my
> thermal inkjet Lexmark.

I don't think it's surface tension, although I could be wrong. Lexmark
and HP use a confusing system with some kind of slight negative
pressure. I found I could successfully fill HP with the bag inside by
refilling slowly, allowing the bag to collapse, wait a while with the
refiller still attached, then draw a little ink back out and quickly
seal the fill hole before the inner bag has a chance to recover.
Something like that. I tested it with water in a cleaned out black
cartridge that was clear plastic.

In HP 3 color heads and in older sponged Epson carts, they use a
sponge to sort of simulate this slight negative pressure. Get a sponge
wet, it tends to hold the water in it.

In Canon and newer Epson cartridges, it uses a different system to
regulate ink pressure. Surface tension in the outlet foam holds ink in
Canon carts, a spring loaded valve holds it in newer Epson carts.

Spongless empties from MIS for Epson use a system like the newer Epson
carts.

> I know Epson's different head technology but it must still depend
> on surface tension in the nozzles to hold the ink in, unless there
> is magically good pressure balancing - which, from recent
> discussions of CIS, I'm pretty sure there isn't.

The nozzles are incredibly tiny so forces from surface tension are
high for the area. I've not had a problem with ink leaking out unless
there is some other problem causing ink to be pushed out.

Yes, most CIS have bad pressure balancing over the course of using up
the ink, but when at the correct level it is very well balanced.

Steve Greenfield