How does your computer know how much ink is left in the cartridge?
How exactly does your printer know when an ink cartridge is almost empty? Different manufacturers use different technologies for this process.
Epson cartridges are equipped with an integrated circuit chip. This chip tells the printer that the correct cartridge is installed and also helps the printer keep track of how much ink each cartridge has expelled. As soon as a cartridge approaches the low ink threshold, the chip will send a warning to your computer and you will see a message on your screen.
Canon takes a different approach. Every printer uses an optical sensor that shines a light through a prism on the bottom of the ink tank. As soon as the ink level drops to a predetermined level, a beam of light strikes a low ink level sensor, which again triggers an on-screen message prompting you to replace the cartridge.
Some other printer manufacturers build the printhead directly onto the cartridge so that the printer cannot be permanently damaged if the ink runs low. These use a chip that is similar to the Epson models. But as part of the system, some of these printers stubbornly refuse to print more pages even with ink remaining, meaning you have no choice but to throw out perfectly good ink.
The big question, of course, is how accurate these systems really are. Journalists and industry insiders offer mixed reports on ink yields, but the consensus seems to be that manufacturers are heavily on the side of cushioning warnings of low ink levels. That is, they’d rather ditch a cartridge with leftover ink than print for weeks or months before spending more money on new ones. One study found that nearly 60 percent of ink is wasted and thrown away [source: Haworth].
If you are concerned about the cost of ink, it is best to do a little research before buying a printer. In general, the cheaper the printer, the more expensive the ink. Spend a little more on the printer itself and your ink costs will likely go down [source: Wood].
Also consider leaving the printer turned on. Every time you turn an inkjet off and on again, it goes through a maintenance routine that can use a large percentage of the ink in each cartridge [source: Consumer Reports].
Print only when you need it and keep the printer on so you get the maximum range of each cartridge. Hopefully you will save some money too.