Ink Carts showing full even when empty

[mikling]

I repeat. The sensor is not activated until the chip level is down a preset amount. So you cannot depend on the sensor to determine when ink is actually out. If you take a chip reading full and empty the ink out, the printer will continue to indicate that it is full.

This is done to prevent false empty warning. In the normal scheme of things, a cartridge will never be empty when the chip is full.

The real function of the prism is to allow recalibration of the empty condition. By being able to confirm when the liquid has run out, the printer then knows with a fair level of accuracy exactly how much ink is left. Prior to the prism detecting an out of ink condition, the amount of ink that is actually remaining is not very accurate. So the prism is like having a tracker report back how the artillery is landing.

 

[PeterBJ]

So contrary to what has been posted earlier, the prism and sensor do not protect against printhead running dry caused by the cartridge being underfilled or leaking?

 

[The Hat]

A normally filled or a half-filled cartridge that may or may not leak has sufficient ink in it for the prism sensor to alert the EPROM chip that the cartridge is low on ink and will then display the red X shortly afterwards...

If you take a chip reading full and empty the ink out, the printer will continue to indicate that it is full.

BUT as Mikling pointed out: - If an empty cartridge gets reset to full and reinstalled, then the printer will be oblivious to that deliberate act and will unknowingly destroy the print head...

 

[mikling]

The chip reading must be down a preset amount before the sensor algorithm becomes active. I've determined this a few years ago and recently on my heavy development use on my Pro-100, confirmed it multiple times when I was switching chips amongst multiple ink cartridges with varying levels.

Does the prism protect the printhead. It certainly does. It allows the printer to accurately use up the ink inside the sponge after the reservoir is empty without damaging the printhead. However, it relies on the aspect that the sponge is saturated when the ink runs out. Without this feedback the ink level could be off by as much as 20% at the time the reservoir is empty. If the inaccuracy was too little ink, then it destroys the printhead.

Normally the printer would keep dropping the ink level based on use. When it reaches the point when it knows to turn on the prism, it waits for the prism to signal and then sets the calibration point. So if it has more ink than normal due to overfilling , it just waits or stalls the decrementing of the ink level until the prism kicks in. If it has too little ink or has consumed more than it thinks, then it simply decrements to the calibration point immediately.

Understood? It does protect but does not offer FULL protection against any and all accidents.

How much preset before it turns on? Dunno and that would take a lot of work.

Now the algrothm also has a limit on the stall. If it stalls by too much, the printer would then indicate empty right after a certain point to protect the printhead. Why? in the event that something in the mechanism was mechanically defective. One possibility is ink dropping or simply dust on the optical sensor outside the cartridge thus blocking the sensor and this causing a misreading on the prism sensor. Does this sound familiar to an aviation event now in the world. Hmmm..see when you design something you need to think about everything that could happen because Murphy always hangs around. The other reason for stall override is to prevent refillers who are clever enough to try and stall it forever by refilling hoping they will stop the chip. Ha!

 

[Ink stained Fingers]

about everything that could happen because Murphy always hangs around

Murphy must be retired by now I assume,
I'm reading that he was working in 1949 at the Wright Field Aircraft Lab. at the Edwards Air Force Base......

 

[turbguy]

Unexpected "programming".

Why not just leave the sensor active at all times (including a 'sensor test target' on the carriage to confirm it's always working) rather than "delay" it's rather important function??

 

[The Hat]

Murphy must be retired by now I assume,
I'm reading that he was working in 1949 at the Wright Field Aircraft Lab. at the Edwards Air Force Base......

Murphy doesn’t just work in the aircraft industry, he’s a man of many places, and will always turn up in your house in time for breakfast as you drop your toast...

 

[jru]

Think I've cracked it. Reset EEPROM with a combination of power and reset buttons and now ink monitoring is back. Got details from the Internet. I think it was for resetting ink pads on the old "i" printers. However, it worked. Back to refilling OEM Carts again. Laying off ARC carts, because I am certain that they caused this problem.

Printer showing 4086 pages printed, so lots of mileage in the old girl yet.

Thanks for replies.

Hello Wilko,
Could you please say the steps you used to reset EEPROM on the ip4500? Thanks.

 

[PeterBJ]

For the iP4500 and other old Canon printers no service tools are used for the reset. Instead push button codes are used. You can read about this in the service manual page 15 and on. The instructions are not quite clear. but the Stop/Resume button serves to select an operation and the power button serves as an "Enter" button to execute the selected operation. Be careful, there is no regret/escape/cancel function! Please also read this warning.