An ink droplet is forced out of the cartridge nozzle onto the paper. 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.
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.
A piezoelectric inkjet allows a wider variety of inks in a much finer quality than thermal inkjets, while more economical in ink usage.
Ink jet printers use one of three main technologies: thermal, piezoelectric, and continuous.
Most consumer ink jet printers (Lexmark, Hewlett-Packard, Canon) work by having a print cartridge with a series of tiny electrically heated chambers constructed by photolithography. The ink used is usually water-soluble pigment or dye-based but the print head is produced usually at less cost than other ink jet technologies.
All Epson printers and most commercial and industrial ink jet printers use a piezoelectric material in an ink-filled chamber behind each nozzle instead of a heating element. Piezoelectric ink jet allows a wider variety of inks than thermal or continuous ink jet but is more expensive.
In continuous ink jet technology, a high-pressure pump directs liquid ink from a reservoir through a gun body and a microscopic nozzle, creating a continuous stream of ink droplets. Continuous ink jet is one of the oldest ink jet technologies in use and is fairly mature.
Aqueous inks are mainly being used in printers with disposable, so-called thermal, inkjet heads, as these heads require water in order to perform.
In professional wide format printers, a much wider range of inks is in use currently. Most of these inks require piezo inkjet heads:
In solvent inks, VOCs are the main ingredient. After printing, the ink has to be cured by exposure to strong UV-light.
Epson have traditionally used fixed print heads featuring micropiezo technology. Fixed-head designs normally use piezo inkjet heads. The disposable head philosophy uses a print head which is part of the replaceable ink cartridge. Every time the printer runs out of ink, the entire cartridge is replaced with a new one. Most high-volume Hewlett-Packard inkjet printers use this setup, with the disposable print heads used on lower volume models.
For models with "Think Tank" technology, the ink tanks are separate for each ink color.
The ink consumed in the cleaning process needs to be collected somewhere to prevent ink from leaking all over the surface under the printer. The type of ink used in the printer can affect how quickly the printhead nozzles become clogged. There is a second type of ink drying that most printers are unable to prevent. Present-day inkjet printers use stochastic or FM screening, which gives better-quality results than low-cost laser printers when printing photographic images. For some inkjet printers, monochrome ink sets are available either from the printer manufacturer or third-party suppliers. When switching between full-color and monochrome ink sets, it is necessary to flush out the old ink from the print head with a special cleaning cartridge.
As opposed to most other types of printers, inkjet cartridges can be refilled. Inkjet printers may have a number of disadvantages:
The ink is often very expensive (for a typical OEM cartridge priced at £15, containing 5 ml of ink, the ink effectively costs $3000 per liter)
Many "intelligent" ink cartridges contain a microchip that communicates the estimated ink level to the printer; this may cause the printer to display an error message, or incorrectly inform the user that the ink cartridge is empty. The color gamut of inkjet printers is limited
The capacity of ink cartridges is limited; a typical black ink cartridge will print 100-300 pages of text, while a toner cartridge for a laser printer may last 2,500-10,000 pages.
For best results, inkjet printers require more expensive paper than laser printers.
Double-sided printing is not usually practical with inkjet printers.
Third-party ink suppliers sell ink cartridges at significantly reduced costs (often 10%-30% of OEM cartridge prices) and also sell kits to refill cartridges, and bulk ink, at even lower prices.
Many vendors' "intelligent" ink cartridges have been reverse-engineered. Color gamut is also addressed by some third-party ink suppliers. Six-color printers are based on the CcMmYK color model. Ink capacity is inherently limited because the ink cartridges must fit inside the printer, usually directly attached to a moving print head. (but see continous ink systems, below)
The earliest inkjet printers, intended for home and small office applications, used dye-based inks. Even the best dye-based inks are not as durable as pigment-based inks, which are now available for many inkjet printers.
Many printer manufacturers discourage customers from using third-party inks, claiming that they may damage the print heads, leak, and produce inferior-quality output. The quality of third-party ink and cartridges is widely debated.
Many of the disadvantages of inkjet printers (items 2-7 above) are addressed by third-party continuous ink systems (not to be confused with continuous ink jet printers, described above). These conversion kits connect the ink cartridges to reservoirs outside the printer: they can therefore hold much more ink, and may be replaced or filled individually. Continuous ink systems typically hold pigment inks, and some have been produced for printers that were only designed to use dye-based inks. Microchips from Epson ink cartriges. A common business model for inkjet printers involves selling the actual printer at or below production cost, while dramatically marking up the price of the (proprietary) ink cartridges.
Most printer manufacturers discourage refilling disposable cartridges. Some inkjet printers enforce this product tying using microchips in the cartridges to prevent the use of third-party or refilled ink cartridges. This allows retailers to advertise extremely low prices for inkjet printers.
Besides the well known small inkjet printers for home and office, there is a market for professional inkjet printers; some being for page-width format printing, and most being for wide format printing. More professional high-volume inkjet printers are made by a range of companies.
High-end inkjet printers can be used to produce fine-art prints called giclées.
