Each ink cartridge contains one or more partitioned ink reservoirs; certain manufacturers also add electronic contacts and a chip that communicates with the printer.
Thermal Inkjets: Most consumer inkjet printers, such as Canon, HP, and Lexmark (but not Epson printers) use a thermal inkjet; inside each partition of the ink reservoir is a heating element with a tiny metal plate or resistor. In response to a signal given by the printer, a tiny current flows through the metal or resistor making it warm up, and the ink immediately surrounding the heated plate is vapourised into a tiny air bubble inside the nozzle. As a consequence, the total volume of the ink exceeds that of the nozzle. An ink droplet is forced out of the cartridge nozzle onto the paper. This process takes a matter of milliseconds.
The printing depends on the smooth flow of ink, which can be hindered if the ink begins to dry at the print head, as can happen when an ink level becomes low; dried ink can be cleaned from a cartridge print head, by gentle rubbing with isopropyl alcohol on a swab or folded paper towel.
The ink also acts as a coolant to protect the metal-plate heating elements: when the ink supply is depleted, and printing is attempted, the heating elements in thermal cartridges often burn out, permanently damaging the print head. When the ink first begins to run thin, the cartridge should be refilled or replaced, to avoid over-heating damage to the print-head; see more at: inkjet printer.
Piezoelectric Inkjets: All Epson printers use a piezoelectric crystal in each nozzle instead of a heating element. When current is applied, the crystal changes shape or size, forcing a droplet of ink from the nozzle. A piezoelectric inkjet allows a wider variety of inks in a much finer quality than thermal inkjets, while more economical in ink usage.
Ink cartridges, however, can be overrided, as some printers refuse to print when they claim the ink is low . One Which? researcher who over-rode the system found that in one case he could print up to 38% more good quality pages, even though the chip stated that the cartridge was empty . In the United Kingdom, in 2003, the cost of ink has been the subject of an Office of Fair Trading investigation, as Which? magazine has accused manufacturers of a lack of transparency about the price of ink and called for an industry standard for measuring ink cartridge performance . Which? stated that some cartridges cost over seven times more than vintage champagne per millilitre .
Consumers are often surprised at the price of replacing their printer cartridges, especially when compared with that of purchasing a brand new printer. The major printer manufacturers, Hewlett Packard, Lexmark, Dell, Canon, Epson and Brother, often break even or lose money selling printers and expect to recoup their losses by selling cartridges over the life span of the printer. (A "razor and blades" business model.) Since much of the printer manufacturers' profits are made up of ink and toner cartridge sales, some of these companies have taken various actions against aftermarket cartridges.
In following with Epson in some countries, Kodak is attempting to change this business model with the pending launch of its Kodak EasyShare inkjet printers which provide individual ink cartridges at a low price. Some printing industry analysts have said that along with Epson, Kodak's new strategy and the very low ink pricing in some countries are the first sign of a collapse in ink prices that will spread worldwide
Many consumers opt to have their cartridges refilled or purchased remanufactured cartridges from third parties to save money over buying new cartridges. This is much cheaper (as you need only buy the ink and some other small raw materials), and a whole industry has grown up around this idea. The legality of this industry was brought to the United States Court of Appeals for the Sixth Circuit in the case of Lexmark Int'l v. Static Control Components. The Court ruled that reverse-engineering the handshaking procedure to enable compatibility did not violate the Digital Millennium Copyright Act.
There are several qualities and types of refilling, some of them being safe and successful, while other types can ruin the printer and/or give bad quality prints. Options include taking empty cartridges to "refillers" or "remanufacturers" who pump in new ink (such as Ink in a Blink) and buying store-branded ink..
Another option is for the consumer to refill the cartridges. Instructions for most cartridges are available on the web, as well as sources who sell "bulk ink" in pints, quarts, and even gallons. This can be extremely cost effective if the consumer is a heavy user of cartridges. One pint (473 ml) is sufficient ink to fill approximately 15 to 17 large cartridges of a typical 27 ml capacity.
Generally speaking, Brother, Canon, Dell, HP, and Lexmark cartridges are not difficult to refill, while Epson cartridges usually require the additional purchase of a chip resetter to reset the counter chip inherent in the Epson cartridges. However, since the process involves handling ink, the process can be inherently messy until experience has been acquired. Laser/toner cartridges sold as "compatible" are usually re-filled cartridges, although many third-party newly manufactured cartridges exist. Inkjet cartridges sold as "compatible" are newly manufactured cartridges. Inkjet cartridges sold as "Remanufactured" are cartridges that have been used at least once by a consumer and then refilled by a third party.