When you print a page on your inkjet printer, if you have your drivers
properly installed, you will see a small screen pop up telling you how full
your cartridges are. How does your printer know this?

Most printers count ink drops. Every line of print is produced by tiny
droplets of ink and your very smart printer keeps track of every one of
them. It's pretty impressive because it's nothing for todays inkjet printers
to lay down 12,000,000 drops per second.

Canon also uses an optical method. The ink sensor monitors the ink levels
through optical detection and dot counting and alerts users when the
supply of any color ink is low.

Canon's ink level system is probably the most accurate although you can
still trick the printer into printing more from an "empty" ink tank. Just tell the
software that you have installed a new cartridge and you can get more
pages out of it.

You can reset the Epson cartridges after they run out and get a whole lot
more pages out of them. Of course you need an Epson universal resetter
to do that.

Things can happen to throw off this counter and you may get erroneous
readings from your ink level indicator, so don't put a whole lot of trust in
it. It's just a guide.

It goes both ways too. Sometimes your levels will be good but your ink
cartridge runs out of ink. It could be that the cartridge was not filled
properly at the factory but it most likely is caused by faulty ink level data.

The data can get corrupt by things like power loss from lightning storms,
a virus, hard drive crashes, Spyware, corrupt printer drivers etc, etc.

So when you think you have a tough job just be glad you don't have to
keep track of 12,000,000 drops of ink per second all day long!