How does ink monitoring work?

[Vorkolor]

How does a Canon printer know the ink level?

I'd guess something like this: The printer knows exactly how many droplets it has squirted out, and how much ink is supposed to be in a new cartridge (or the chip tells it). So it keeps track of ink use, and calculates remaining ink from that. The printer writes the ink level to the cartridge chip.

Then there's the prism, which senses optically if there's ink in the reservoir. When the prism says empty, the printer gives a "low ink" warning.

What happens if calculated ink level and prism doesn't match up? Does it give a low level warning anyway?

I've noticed that my MG6650 (PGI-550/CLI-551) has had me replace a couple of compatibles early, before the reservoir is completely drained. (Can't say what the actual ink level was when I replaced the OEMs, as they're opaque.) Poor prism design on the compatibles, making the printer go by calculated ink level only? Incorrect ink level in chip? Printer sabotaging use of compatibles? Probably Canon will blame the cartridges and the cartridge supplier will blame Canon.

 

[The Hat]

Your ink monitoring is all done by the printer itself and not by the pesky chip, its only purpose is to stop you from fitting a cartridge into the wrong position but the main reason for its presents is to prevent you from reusing the cartridge again.

Then there's the prism, which senses optically if there's ink in the reservoir. When the prism says empty, the printer gives a "low ink" warning. Correct.

You can also try and cheat the prism system by topping up the cartridge in an effort to delay this low ink notice, but it won’t work because the printer will still tell you that you’re out of ink and red X the cartridge chip, it’s like Roulette “The house always wins” …

 

[mikling]

How does a Canon printer know the ink level?

I'd guess something like this: The printer knows exactly how many droplets it has squirted out, and how much ink is supposed to be in a new cartridge (or the chip tells it). So it keeps track of ink use, and calculates remaining ink from that. The printer writes the ink level to the cartridge chip.

Then there's the prism, which senses optically if there's ink in the reservoir. When the prism says empty, the printer gives a "low ink" warning.

What happens if calculated ink level and prism doesn't match up? Does it give a low level warning anyway?

I've noticed that my MG6650 (PGI-550/CLI-551) has had me replace a couple of compatibles early, before the reservoir is completely drained. (Can't say what the actual ink level was when I replaced the OEMs, as they're opaque.) Poor prism design on the compatibles, making the printer go by calculated ink level only? Incorrect ink level in chip? Printer sabotaging use of compatibles? Probably Canon will blame the cartridges and the cartridge supplier will blame Canon.

On the printer model you own, the optical system becomes active within a window of chip level. When the chip is down a certain amount, the optical sensor is then turned on and it looks out for an out of ink condition. When the optical system detects an out of ink system, it then adjusts the ink level on the chip to match what it has found. So if the chip indicated higher than it should be it would immediately adjust the chip. From this point on...it relies on the chip to go to empty...more precise to a degree. Now suppose the optics never saw an out of ink condition......well the chip counter never stops because of this and will simply continue its journey to the out of ink condition despite the optical sensor saying that the printer still has ink.

The ink squirt count is very inaccurate because ink is used not just for the squirts but also for priming and cleaning. Since the purge pump is shared amongst all the colors, the amount of ink extracted by one pull will vary depending on the flow resistance of each cart. Since this resistance can vary depending on cartridge condition, ink levels and also position on the cartridge. One forgotten variant is also how long the cartridge has been in the printer......drying. An on compatibles this can be an issue as the air vent is directly to the atmosphere with no serpentine or tunnel system like the OEM carts have. Drying occurs much faster on compatibles.

So there you have it, The system is initially open loop, becomes closed for a period, white being watched with a timer of sorts during that period and then no matter what will resort back to open loop towards the last part. A fully closed loop for the entire operation will cause too many false results and errors. Why this complicated process....to protect the printhead towards the critical low ink period and make sure it has ink at a point the errors could have added up.

 

[stratman]

When the chip is down a certain amount, the optical sensor is then turned on and it looks out for an out of ink condition.

How would this help if there was a catastrophic loss of ink early on? The chip counter would be of no help and neither would the optical sensor in your scenario.

I thought the commonly held belief on the forum has been the optical sensor is on from the time you insert a new cartridge and not only guides the tracking of the low ink warning system on the way to empty but also to warn the user of low ink in the scenario of an unexpected leak of the cartridge earlier on, such as unexpected loss of ink from the spongeless side of the cartridge.

When did the optical sensor become a part time worker dependent on the chip to be activated? How did you come about this paradigm?

 

[mikling]

How would this help if there was a catastrophic loss of ink early on? The chip counter would be of no help and neither would the optical sensor in your scenario.

I thought the commonly held belief on the forum has been the optical sensor is on from the time you insert a new cartridge and not only guides the tracking of the low ink warning system on the way to empty but also to warn the user of low ink in the scenario of an unexpected leak of the cartridge earlier on, such as unexpected loss of ink from the spongeless side of the cartridge.

When did the optical sensor become a part time worker dependent on the chip to be activated? How did you come about this paradigm?

Lots of tests done specifically to see what is happening. I Started to retest 2 years ago since the Pro-100 and the newer PGI-250/251 and went back to the CLI-8 on the iP3300 to see what is happening. It all comes together.

 

[stratman]

@mikling

It sure is a different paradigm and riskier for print head damage if the optical sensor is not functioning from the start when a new/refilled and reset cartridge is inserted. Doesn't make sense to me - with potentially more service calls - but Canon has their reasons.

 

[Roy Sletcher]

@mikling

It sure is a different paradigm and riskier for print head damage if the optical sensor is not functioning from the start when a new/refilled and reset cartridge is inserted. Doesn't make sense to me - with potentially more service calls - but Canon has their reasons.

Also goes to show that sometimes simple street smarts trumps expensive engineering. We may be crazy but we're not stupid!

Then again the Canon reasons probably start with a $ sign. Sales and marketing types will sign-off on anything liberally sprinkled with them.

rs

 

[Vorkolor]

So if I understand @milkling correctly, I should be safe if I refill all the cartridges whenever one indicates low or empty. Only that cartridge will reset, the other cartridges will always indicate less ink than they actually have, so no risk of running empty, little risk of draining the sponge, and the frequent inspection probably doesn't hurt. Flush or replace cartridges if I suspect too much dry ink in the sponge.

What is the reason that compatibles/refillables don't have the air maze/serpentine? Too complicated to build cheaply? Patents?

 

[The Hat]

@mikling

It sure is a different paradigm and riskier for print head damage if the optical sensor is not functioning from the start when a new/refilled and reset cartridge is inserted. Doesn't make sense to me - with potentially more service calls - but Canon has their reasons.

From what I can gather, Mikling is referring to the use of ARC chips and not to the OEM chip, otherwise it wouldn’t make sense to me either, the newer printers have more advanced EPROM chips in them compared to the older models and Canon Inc. have now all the angles covered.

The CLl-42 and CLl-551 printers were the first models to use the advanced EPROM chips that could deny the use of certain software Apps. if you didn’t use their cartridges, and now nor do they allow the use of Service Mode anymore.

Some said they couldn’t do that, then try running one of these newer printers with all of the ink monitoring disabled and just see how far it gets you, it’s the revenge of the Empire..

 

[stratman]

revenge of the Empire

Thank you Obi-Wan The Hat Kenobi

From what I can gather, Mikling is referring to the use of ARC chips and not to the OEM chip

Ahh, OK. Strong is the dark side in Canon.