Digital BW, The Print

Eric Ashworth wrote:

"... the purpose of the cartridges is to provide a supply of ink that does
not readily flow unless there is enough suction to draw air into the cart to
replace the used ink. And as a means of holding the cartridge's chip in
place so as to make contact with the print head so it is recognized by the
printer."

Eric - First of all, I am NOT an expert but I did stay in a Holiday Inn
Express last night. I have been thinking about this myself but I have some
critical questions and observations mostly pertaining to small format like
the 2200/2400/1800 printers.

1) It seems that one obvious point is the need for a firm seal between the
tubes and the "nipples" in the head. A lot of complaints about CIS systems
now seem to result from the cart fitting loosely and not making a good
enough seal. Air getting into the cart from the head-end is not a good
thing. Venting is. With the right size tube and a small zip tie or clamp the
tubing could be secured but it would be a "bitch" getting it done in such a
confined space. I have had good luck inserting tubes over these "nipples" or
"needles" for the purpose of injecting cleaner through the heads (NOT
recommended except as a last resort). However, the tube will eventually come
loose if it's not more securely clamped.

2) There appears to be the need for some kind of "damper" such as the ones
used on the large format printers to suppress larger particulates. Perhaps
the large format dampers could be used in lieu of the carts?? What other
role does the damper play?

3) Some large format carts are pressurized, some not. Is it suction at work
or pressure? Which is it in the small format printers... Appears to be
suction. However, I can say that most CIS systems are HIGHLY sensitive to
gravity and placing the bottles even a little too high will result in a mess
of ink dripping through the head. Bottles too low will result in starvation
and may even draw ink back from the head causing air bubbles or air in the
lines. In fact, some people have reported that it's not enough to get the
bottles at the right height but that the level of the ink in the bottles
should be level with the head at al times. The bottles need to be raised as
the ink is used for best results (hearsay).

Part of what has kept me from moving forward has to do with unanswered
questions about the role of gravity vs. suction vs. pressure in these
printers and an inadequate understanding on my part of just how the ink is
regulated. Pumps pull ink through for cleaning but what causes the ink to
flow while printing? Are these things known or are we just taking a shot in
the dark.

It also seems obvious that building a good CIS is more complicated than it
seems. There are a lot of problems reported. Heck, there are people getting
clogs with OEM carts too. Why some and not others? Printer tolerances?
Climatic conditions? Humidity? Atmospheric pressure? Black magic? Carts that
aren't sitting tight enough? Who does know? Any engineers out there or ex
Epson folks who really understand this stuff?

Hmmm.. Lots of food for thought but too little time to digest...

Rick Colson