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#1: Gravity driven CISS anywhere? Author: GeorgesPlat,

Posted: Wed Nov 07, 2007 5:29 pm
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I have no experience with CISS but would very much like go use it. Careful study of lots of discussions about all sort of problems, especially with Canon printers, I figured out there should be a very simple system that will not have any of these problems.

That is a system where a constant level of ink in the cartridges is maintained without any fluctuation in air pressure in the cartridge. A very small (filtered) hole at the top of the cartridge allows the print head to really use much of the ink in the cartridge without creating an under pressure.
To maintain the ink level gravity is used, in stat of air (under) pressure. The tube connects the cartridge with a pressure neutral chamber, in or close by the reservoir. In this chamber the ink level is maintained in the usual way and the air pressure above the ink is kept neutral, the same way is in the cartridge, with a (filtered) hole on top.

In a system like this, the ink flow to the cartridge will be very slow but a half filled cartridge will supply more than enough ink to perform heavy tasks. The ink flow is slow but very constant as long as the ink level in the cartridge is low. Ink will flow even when there is no printing.
Adjustable height of the container gives the opportunity to adapt to different situations. If the printer has a lot of free time, the ink level could be lowered so less ink will leak through the print head or the bad connection between head and cartridge. If the printer has to print hundreds of photo’s without pause, maybe the ink level should be kept higher to maintain enough flow from the reservoir.

This looks all quite simple to me and I would be very surprised if this system is not yet on the marked today. Can anyone tell me where I can buy such a system?

#2: Author: Martin, Location: South Yorkshire, UK

Posted: Thu Nov 08, 2007 9:55 am
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I'm about 50% on understanding the concept you suggested and I suspect that this sort of thing has been tried already with some very mixed success.. The end result was that the guy who was playing with it (and he played a LOT) decided it couldn't really work due to various issues.

By all means give your system a shot but I'm not aware of anything that does what you're looking to do and I'm not 100% convinced it would necessarily work..

#3: who did it? Author: GeorgesPlat,

Posted: Thu Nov 08, 2007 3:25 pm
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Interesting. Just did a search on ‘gravity’ on this forum but did not find any notice of the concept I’m gaoling at. I’ll try to fill in the other half of understanding by simplifying the concept.

In a normal printer the ink is placed just above the print head. The weight of the ink is enough to bring it to the print head and the whole system is designed to operate with this minimal amount of ink pressure .To maintain this pressure, the cartridge has a small opening to let air in when ink gets out.

A CISS replicating this conditions must do the best job. Practically all problems with CISS have to do with changes to the operating conditions of the cartridge. The small pressure coursed by the inks weight is replaced by an under pressure when the print head sucks out ink, using that under pressure to suck ink from the big bottle, but also sucks in air through the smallest leaks in the entire system of cartridge, print head en tubing.

Two buckets are filled with water and connected with a fully filled tube to the bottom of each bucket. When you take water from one bucket, half of that water will flow through the tube to balance the levels.
You can take out much water at once, After a while the levels will be equal.
If one of the buckets is very big, lets say a floatable pool, and the other is a normal bucket, that normal bucket will give the impression it cannot be emptied. No matter how much you take out, it will fill again.
The only place in this system where pressure drops below the surrounding pressure is in the tube where the tube is higher than the water level. Presuming the tube does not leak and has no connections above water level, and water is not taken out faster than the bucket refills, this system is foolproof.

Taking this concept to a printer, the only complication is that the tanks have to be at a precise height. Putting them to high will overfill the cartridge and ink will flow out the air holes. Placed too low will let the ink flow back to the tank and the tubes will be filled with air.
Fine-tuning this is easy since most cartridges are transparent.

#4: Re: who did it? Author: canonfodder, Location: Pelham, New Hampshire, USA

Posted: Fri Nov 09, 2007 1:37 pm
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GeorgesPlat wrote:

Taking this concept to a printer, the only complication is that the tanks have to be at a precise height. Putting them to high will overfill the cartridge and ink will flow out the air holes. Placed too low will let the ink flow back to the tank and the tubes will be filled with air.
Fine-tuning this is easy since most cartridges are transparent.

It may help you to learn how the Canon ink cartridges of today work. The ink chamber part of the cartridge works like a chicken waterer. It is sealed at the top with only a small opening at the bottom between it and the sponge chamber. When the sponge chamber is low enough on ink, it lets an air bubble into the ink chamber and that releases a bit of ink into the sponge chamber. The net result of this is to have the pressure at the bottom of the sponge chamber at about zero pressure relative to the atmospheric pressure. Gravity doesn't really control the ink flow. If you unseal the ink chamber, ink will flow out continously into the sponge chamber and down to the print head and either leak out or block the print head, ruining the printing.

You suggest that the outside ink tanks have to be at a precise height. I would ask you to think about whether it is the tanks or the ink in the tanks that needs to be at the correct height. If it should it be the ink level that needs to be at the correct height, who is taking care of that height as the ink is being consumed?

#5: Re: who did it? Author: GeorgesPlat,

Posted: Sun Nov 11, 2007 8:43 pm
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canonfodder wrote:

The net result of this is to have the pressure at the bottom of the sponge chamber at about zero pressure relative to the atmospheric pressure. Gravity doesn't really control the ink flow. If you unseal the ink chamber, ink will flow out continuously into the sponge chamber and down to the print head and either leak out or block the print head, ruining the printing.

Okay, get it. Thanks. This means that the sponge, connected to the open air is essential to preserve an instant ink buffer without any under/over pressure. The absence of pressure makes the whole gravity drive concept useless for Canon printers.
To maintain the situation where the ink in the cartridge behaves like a buffer, with absolute zero pressure, I start to believe the sponge chamber with air hole has to be left as it is. The CISS should keep the sponge wet without under pressure to suck ink and without over pressure to prevent overflow.
I'll seek for a solution making use of the surface tension of the ink. Very much like the sponge does. I'll keep you informed.

Quote:

You suggest that the outside ink tanks have to be at a precise height. I would ask you to think about whether it is the tanks or the ink in the tanks that needs to be at the correct height. If it should it be the ink level that needs to be at the correct height, who is taking care of that height as the ink is being consumed?

That would be the chicken waterer principle like you mentioned yourself. Making the level in the controlled chamber adjustable has no use because this should be as low as possible to maximise the effective tank capacity. The whole external unit will have to be positioned at the right height.

#6: Author: Martin, Location: South Yorkshire, UK

Posted: Sun Nov 11, 2007 8:51 pm
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Mod note:
The "chicken" word has been triggering the spam filter hence the problems with getting the last couple of posts through... I've been authorising them as soon as I notice they're not getting through.

#7: Author: canonfodder, Location: Pelham, New Hampshire, USA

Posted: Sun Nov 11, 2007 11:49 pm
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Reference Mod. Note.

We might start referring to a "domesticated fowl waterer" to humor the spam filter.

#8: Author: Martin, Location: South Yorkshire, UK

Posted: Mon Nov 12, 2007 10:13 pm
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canonfodder wrote:
Reference Mod. Note.

We might start referring to a "domesticated fowl waterer" to humor the spam filter.

Well it's not so much the chicken as it's offspring that's causing the issue Razz

#9: Author: bkovats,

Posted: Wed Feb 13, 2008 4:33 am
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For GeorgesPlat

If you haven't already found our been made aware of their availability, the gravity ciss, similar to what you proposed in November, is available from http://main.asc365.net/CIS/CISS.htm.

The black and white animated graphic on the site is a bit misleading in that it does not show air going up the diagonal tube as the ink in the smaller chamber gets used. It does illustrate, however, that the ink level in the small chamber varies very little no matter the level in the larger chamber, just like your large pool / small pool correlation.

Once the proper height of the ciss is determined (small chamber ink level relative to the cartridge), the pressure between the ciss and the cartridge will remain essentially constant even as the ink in the larger chamber is depleted.

#10: Your link needs small fix Author: canonfodder, Location: Pelham, New Hampshire, USA

Posted: Sat Feb 16, 2008 4:21 pm
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Bkovats,

Your link has a period at the end. That prevents it from working. If you just delete the period, the link will take a person to the site you intend.

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