Having recently randomly decided to suck all the ink out of an Epson cartridge bought cheaply from eBay I just really wanted to see how much ink was actually in it. Uh, I then decided to open a cartridge and I don't recommend this because even if you've sucked all the ink out, there's plenty of ink. Just covering every surface makes a huge mess. But it turns out it's really complex inside and a lot of the complexity is just to make sure that no matter what happens during shipping or storage with the thermal expansion contractions, super hot climate, super cool climates, it can't force the ink back out the air holes.

And for that reason, there is a Pneumatic valve under here and there's a hydraulic valve here and here. it's very complex, really interesting. Let's get down closer and we shall explore this and I'll show you the path the ink takes through. So inside the cartridge, there's an outer plastic cover that welds on to this orange layer and that in there ends up full of ink as well as the main ink chamber.

Inside is a plastic film outlined by this pink era which covers an inner molding and that is the ink chamber and it's got various gaps to allow the ink to flow through sections within that and it's important to note that the air into the chamber comes in down here, but it's designed so that when this isn't the printer and that's pointing down and this is up the way, any bubbles that come up here will go straight up to the top and during printing. it's very unlike to pull it down because hopefully those bubbles will first. By the time it finally gets down here, the ink then has to find its way through here. One more bubble trap just before it goes out and then it goes up here and there's a filter.

And let me show you the filter. Here is the filter. It's a little spongy filter which is down here and that then has a little bridge that Couples from here to here and into this diaphragm area. The diaphragm.

This hole is not normally there I Had to use that to force the plastic off the other side. Let me show you the diaphragm side and that is the back layer. Here is the diaphragm itself. So the ink Bridges There is the back of the filter.

There's a little uh, seal that basically speaking because the plastic. There's a layer of plastic sealed on this side as well. It creates lots of little sealed areas that the liquid can flow from across barriers. so liquid flows into the chamber and then it enters the other side.

But the only way it can come through is via a silicon rubber diaphragm. So here is here's the plastic cover. I Removed off that very hard to get off as well fused in and also had the plastic layer over the top of it. Then there was a little plastic rubbery well actually a silicone rubber but very strange and Squishy very soft silicone rubber, diaphragm.

But the main thing is the Ink's coming through these holes. but it once gets through the middle because there is a hole in the middle of diaphragm. but there is also a tiny little spring here that is pushing that diaphragm down against that. PIN So for the printer to be able to suck ink, it has to pull a negative pressure against that for it to open.

This also means that if you, uh, try squirting ink back in via the outlet Port that diaphragm will close and you won't be able to refill the cartridge. but that way I don't know I Think this diaphragm is mainly to prevent ink siphoning down through the printhead, but it could also be to stop you squirting ink in the other way. If I was being terribly cynical about it, let's go back to this. Once the ink has found its way past that diaphragm, it goes down this channel here which is again sealed by the plastic strip, pops into this channel here and that is where we have the printer connection Port which is a little rubber diaphragm like this.

But let me show you here, let me bring in the next exhibit here. We have this little rubber Port which not only couples onto the uh, the ink pipe that the printer has, but it also has a ceiling surface on top and this plastic pin. Here, plastic pin pushes down against that and that is held down firmly by a much bigger spring. this spring.

Here there's also a little plastic Biff at the top. that means that when this is manufactured and it's pushed in against the spring, it clicks into a plastic housing account picked up. It's very fumbly and it stops it from popping back out and pushing this rubber diaphragm back out. So when you pop it into the printer, two things actually happen.

It also opens an air inlet at the same time as well as the pipe green here and pushing that Plunge in so the ink can flow down. Anything else worth mentioning about this now during the Uh during shipping and storage, ink is everywhere in these things. It literally this is an air void in here now. I'm guessing the reason there's an ear void is to allow for thermal expansion contraction, but the ink will inert because the there is a sealed plug here that stops irrigating initially and this uh, air void ink will end up coming down into it because there is a passage from here down to the bottom.

Here there's just this tiny little Gap at the very bottom of this Uh pickup pipe and this is a sump and any link ink that does find its way out there isn't wasted. Uh. during normal operation, the Air: as it sucks the ink the air in through this hole, it pulls the ink up from the sump back into the chamber, so very little ink will actually be left in here other than just what coats all the surfaces. Let's take a look at the air passage now, which is super complex.

So I'll start off with this picture here. So here is the back of the cartridge and there is the Ear Inlet The Ear Inlet starts as this tiny tiny little crevice in the plastic that weaves down and it takes a very long, convoluted route and then it comes back up again and then it goes down into this chamber. Here, this chamber has a piece of fibrous papery filter material like a stiff plastic in paper that is clearly perforated and it's designed partly to absorb any leakage of ink that comes back and also to allow air to go through but not allow ink to come back and blow out the top of the cartridge. Basically, note this chamber here and this chamber.

here. they are the air Chambers for actually and allowing the air into the whole system. So let me go back to this side. So the air has come down into that chamber with the filter and once the filter is removed, hold on, let me grab the other one.

So many images here. Once the filter is removed, you can see where I've just dragged off here and it's all where it's been heat sealed round. There is a hole at the back. That hole Ducks down to the other side goes across here Ducks down to this side and goes across here.

This is that a circuit board isn't it and then it goes into a chamber here and this has its own little seal going around it. This also has a plastic cover over it. This plastic cover here with a little Pip that when you slide it into printer this little Pip is pushed in and see that we pin push in. In this printer area is a little plastic well a little silicone rubber bun that goes into that hole on that is a very very Stout heat welded the heat stick, a metal spring that pushes that down really hard against that so that the air can basically so the air is in here.

It can't get through that because this plug is blocking that when you slide it into the printer. This is where we have to go to the other side again. there's a little pin that gets pushed in when the pin is pushed in. Uh from this side because this is a diaphragm.

Again, that the diaphragm doesn't get punctured, it merely uses it as a drum skin diaphragm that it pushes in and it pushes down against against that little pin and the air can get through to this side. The air then couples into this chamber here down to the bottom here and then we have to go to the other side again. Um and it then oh no Actually, I'm wrong here. Wrong here.

Almost, but not quite that. uh, chamber here. When the diaphragm is pressed, it couples the air to this chamber here, which goes to the top again. This is to make sure the air enters at the top of the cartridge and not the bottom and the air then flows down and can now find its way up inside this chamber here via that little slot in the back and into the ink cartridge so it can actually release the pressure of the ink.

It's ridiculously complex. Then you look at the refillable cartridges and they're so simple inside. Here's the ear plug with that little convoluted path for the air. Uh, there's the ink refill bit.

But the main advantage of these when they ship these, they don't have to worry about ink leaking out them because, well, there's no income in the ship them. So they are super simple. I Don't even see an obvious anti-siphon thing here. Uh, but the idea of these is you put the air plug in, you take this one out, you fill it with the desired ink up to the brim.

Uh, then you put that plug back in and then you put it back in the printer and remove this and it never lets air in through that. So this doesn't have to have the complication of the non-refillable cartridge that just leaves a chip. The chip is a little memory chip that look of it. very low capacity memory chip, low speed memory chip.

from what I've read it has connections on it plus and minus for the power and it's got reset, clock and data and basically speaking the printer reads how much ink is in it, base reads the number in it, and then when you do a print job, it then writes it back and says you've used x amount of encode estimate in this print job and it reduces the number and uh once it uh gets to the the leveler that's virtually zero then the Uh printers warns you that the cartridge is empty even if there's a little bit of ink in it because it is estimating that is worth mentioning. You do get chip re-centers and some people do refill these cartridges by basically drilling a hole through the case and uh, squirting the ink into this area and then putting a rubber bung in. Not sure if that'll go with the air passage thing but it doesn't matter. You get tons of ink because you can refill it and then they put this into a little chip resetter and when they do, it's got two linked pins in here and that basically Bridges the power from the little batteries in the the chip resetter and all it does I Think it reads the data from it, determine which type of air cartridge it is, and then it just sets the ink counter back to full.

Again, it just rewrites that and that's how it's restored to normal operation. I Did a poll about uh, whether people use the proprietary ink cartridges or the refillable ones, or if they, uh, the remanufactured ones like say, for instance, this remanufactured one and about 50 of people used uh, laser Jets But laser should printers because they were sick of the mess of the inkjet printers. A surprising number used the manufacturer's original cartridges. That's these ones.

Uh, but a significant number used to be manufactured. and uh, then there were the hardcore Geeks that just filled their own cartridges again and reset them. But there we go. That is it.

That's uh, what's inside have I covered everything I have that took such a long time to reverse engineer, particularly because I didn't realize these bits were I Just thought it was going to be something simple I thought it was going to be liquid out here and here in here. and that was it. I didn't realize there's that little valve. in fact, because I'd been sucking the ink out the syringe, the cartridge with a syringe, it had drawn a vacuum inside it and when I actually found that and pushed it, there was a loud hissing noises that let air back into the system.

But quite complex. Very neat it. Uh, it looks like this has evolved over time, probably due to shipping cartridges and finding ink everywhere. but very interesting.

Very neat. Take one apart, uh, much more complicated than I was expecting.