The BASICS of a CISS

[mikling]

I think it is important to understand how a basic CISS works. In many products we see all kinds of terms such as isobaric, constant pressure etc etc. All of them are based on a simple principle though cloaked in smoke and mirrors ad marketing goop. That principle is the Mariotte siphon or bottle.

http://weather.nmsu.edu/Teaching_Material/SOIL456/lab6.htm
http://en.wikipedia.org/wiki/Mariotte's_bottle
http://lawr.ucdavis.edu/classes/ssc100/mariotte_bottle1.pdf

The essential thing to observe is that the RELATIVE height of the dip tube where air enters into the tank and where ink or liquid exits is the determinant of pressure on the nozzle. That is why raising or lowering the tank height will adjust pressure on the inkhead nozzles. This is because the printhead height is constant but the dip tube then goes up and down when you raise and lower the tanks.

From this you can then infer that the ink level in the tank should not fall under the dip tube if you want constant pressure to work.

Having said that, Let me add I have found, that a normal siphon bottle has worked just as well for me( http://www.nifty-stuff.com/forum/viewtopic.php?id=2136) , even without a mariotte principle. You will find that for years a popular company has supplied and continue to supply these. Thus it makes you wonder if the mariotte is actually required? Well most CISS have them so it won't hurt. The CISS I use currently has a dip tube.

I'll start another thread another time where I will try to explain why sometimes a mariotte bottle or constant pressure can sometimes create problems rather than solve one.

 

[johnwarfin]

Your siphon thread was very interesting. I also did that on an old Stylus from the recycle center. I found that while the seal on cartridges was important the one to the bottles is not. In mine the tube is loosely fit through a hole in the center of the cap so I can screw and unscrew easily for new bottles. Another advantage is no air hole was required for this reason. 3 years and going strong.

I was always curious about why the Mariotte was required and look forward to your explanation of the drawbacks.

 

[kgvickers]

I thought I'd never seen such a device. Turns out I've been looking at one for the past few days. Take a look at the first picture I posted in this thread: http://www.nifty-stuff.com/forum/viewtopic.php?id=4715

I puzzled over this design for a while. It is simply a Mariotte siphon arrangement. As Spock would say: Fascinating!

Now I'm going to have to conduct a little experiment to determine the relative height of the print head and the dip tube. Logic tells me that the print head will likely be slightly below the dip tube - correct?

Thanks for posting this.

Keith

 

[mikling]

You will see all kinds of arrangements and pathways etc. but as long as the principle holds with a type of dip tube and outlet then it will work the asme as any other one.

Now for the really curious really take a look at the Canon ink tanks with a reservoir. Look very closely. You will need to put your thinking caps on here.

 

[websnail]

As I'm sat here waiting on a call from someone I've a few things to add too...


As Mikling said there have been a number of CIS kits that existed long before the appearance of what I term the "Clone kits" with their constant pressure approaches. MIS Associates, IIRC, took a look at the CIS systems that were available in industry and worked hard on creating a scaled down version to work with some of the early Epson printers like the Epson Style 740.

Epson was a perfect system for this as the cartridge/printhead connection involves a large seal area that makes it very difficult for air to leak into the system at that point (not so with the Canons but that's another story). As a result the issue of air/ink pressure was less important especially as the printer nozzles seem able to cope with a range of pressure. This system is one that I, like Mikling prefer because it's simple to use and there's none of the faffing when it comes to filling that you get with the constant pressure systems.

Anyhoo... At some point the Chinese caught on to the marketing potential for CIS systems and decided on mass production... Along the way someone must have decided that ink pressures were an issue and that it was worth creating something that delivered the ink at a pressure that wouldn't damage the printhead. My guess is that came about because other printers with more delicate printheads (like the Canon bubblejets) were more sensitive and if you're going to sell in bulk you want to sell to all the manufacturers, right?! Pure suposition on my part but it makes commercial sense.

Anyway... since these clone kits started appearing those without prior experience have simply assumed that pressure balance is the rule and acted accordingly... It isn't... It's useful to have, in some cases it's essential but it is not a requirement for ALL inkjets. In some instances it's actually a hinderance when sitting at the usual printer level (eg: HP88 printers) so it's a bit like "I before E except after C".. except for erm.. all those times it isn't


So, that's a bit of an update... You have to admit the contant pressure systems have their benefits for manufacturers, easy to mass produce, assemble, etc... and like the "spongeless cartridge" must have BS* if you go back to an older approach you're looked at like you're "retro man" and assumed to be a throwback.

On the spongeless cartridge bit... There's all this cr*p about how they are sooo much better, etc... when it's patently obvious from discussion since that they are actually worse, not better. The only reason they came about was because Epson got lawyer happy with it's "sponge in a box" patent and threatened manufacturers with dire bank balance draining legal action so it was side stepped with the spongeless (ha! two fingers to you Epson) design. At the same time various folks got it into their heads that less sponge meant more ink and this myth that the printer manufacturers were using sponge to put less ink in was born... Wonderful marketing ploy but as numerous folks have since discovered they result in greater reliance on constant pressure systems (see how I tied that together ) and all sorts of ink feed issues because, *gasp*, guess what those bits of sponge were actually a regulation system, not some neo pinko conspiracy...

Anyway... If you look about now, the majority of CIS systems are produced in China... There has been some development but overall they've stayed pretty standard throughout... Almost all efforts now are aimed at the protections being designed or programmed in by the manufacturers.


Interestingly some manufacturers have played with CIS systems built into their printers like the HP Officejet range or recently Epson with the B300N / B500DN but in each case they manufacturers miss the point about bulk ink being cheaper.


Hmm... gone on a bit here but hopefully it adds to the conversation and besides it helped me kill a bit of time

 

[websnail]

... and yeah now that I re-read it's a bit patchy and sensationalist as the spongeless cartridges aren't all bad, sponged cartridges weren't nirvana either (algae or ink foam clogs for example).

Still n'all there's some useful additions in there, you may have to ignore my grammer though

 

[mikling]

websnail,

Epson introduced the spongeless because it was the sponge cartridge that was a large contributor towards their nozzles not printing and causing perceived clogs. The typical response was that the sponge was breaking down. Additionally many third party compatible cartridges for Epson are still sponges and depending on the quality and the ink capacity and how much ink was put in, would give "clogs" before the ink levels said empty. This deserves another thread. In a CISS whether it is sponge or spongeless will hardly make a large difference. The key word is in a CISS.

 

[websnail]

That's interesting... I was under the impression Epson had forced the move legally but I guess I was misinformed. I stand corrected then...

If anyone else would like some humble pie... ?

 

[Ashton44]

Its really appreciative work and I hope you will keep it up as well

 

[nche11]

Any CIS which depends on the orientation of the ink bottles is a cheap hack. It is a waste of money. One day the bottles are too high and the other they are too low. It's a torture. Everyday you question yourself are they at the right hight today? Having tried two CIS my third is ready to go to ebay to have someone else tortured.