| The printers utilizing inkjet technology were first | | | | electrostatic charge on each droplet. Charged |
| introduced in the late 1980s and since then have | | | | droplets are separated by one or more uncharged |
| gained much popularity while growing in | | | | "guard droplets" to minimize electrostatic repulsion |
| performance and dropping in price. They are the | | | | between neighboring droplets. The charged |
| most common type of computer printers for the | | | | droplets are then directed (deflected) to the |
| general consumer due to their low cost, high | | | | receptor material to be printed by electrostatic |
| quality of output, capability of printing in vivid | | | | deflection plates, or are allowed to continue on |
| color, and ease of use. Each printer which works | | | | undeflected to a collection gutter for reuse. |
| on inkjet technology places extremely small | | | | Continuous inkjet is one of the oldest inkjet |
| droplets of ink onto paper to create a text or an | | | | technologies in use and is fairly mature. One of its |
| image. In the personal and small business | | | | advantages is the very high velocity (~50 m/s) |
| computer market, inkjet printers currently | | | | of the ink droplets, which allows the ink drops to |
| predominate. Inkjets are usually inexpensive, quiet, | | | | be thrown a long distance to the target. Another |
| reasonably fast, and many models can produce | | | | advantage is freedom from nozzle clogging as the |
| high quality output. Like most modern | | | | jet is always in use When printing is started, the |
| technologies, the present-day inkjet is built on the | | | | software application sends the data to be printed |
| progress made by many earlier versions. Among | | | | to the printer driver which translates the data into |
| many contributors, Epson, Hewlett-Packard and | | | | a format that the printer can understand and |
| Canon can claim a substantial share of credit for | | | | checks to see that the printer is online and |
| the development of the modern inkjet technology. | | | | available to print. The data is sent by the driver |
| In the worldwide consumer market, four | | | | from the computer to the printer via the |
| manufacturers account for the majority of inkjet | | | | connection interface. The printer receives the |
| printer sales: Canon, Hewlett-Packard, Epson, and | | | | data from the computer. It stores a certain |
| Lexmark. The typical inkjet printer usually includes | | | | amount of data in a buffer. The buffer can range |
| inkjet printhead assembly, paper feed assembly, | | | | from 512 KB random access memory (RAM) to |
| power supply, control circuitry and interface ports. | | | | 16 MB RAM, depending on the printer model. |
| The inkjet printhead assembly contains several | | | | Buffers are useful because they allow the |
| components. One of them is the printhead which | | | | computer to finish with the printing process |
| is the core of the inkjet printer and contains a | | | | quickly, instead of having to wait for the actual |
| series of nozzles that are used to spray drops of | | | | page to print. If the inkjet printer has been idle for |
| ink. Another printhead component is the inkjet | | | | a period of time, it will normally go through a |
| cartridge or inkjet tank. Depending on the | | | | short cleaning cycle to make sure that the print |
| manufacturer and model of the printer, ink | | | | heads are clean. Once the cleaning cycle is |
| cartridges come in various combinations, such as | | | | complete, the inkjet printer is ready to begin |
| separate black and color cartridges, color and | | | | printing. The control circuitry activates the paper |
| black in a single cartridge or even a cartridge for | | | | feed stepper motor. |
| each ink color. The cartridges of some inkjet | | | | This engages the rollers, which feed a sheet of |
| printers include the print head itself. The printhead | | | | paper from the paper tray / feeder into the |
| along with the inkjet cartridge/s are moved back | | | | printer. A small trigger mechanism in the tray / |
| and forth across the paper by device called a | | | | feeder is depressed when there is paper in the |
| stepper motor using a special belt. | | | | tray or feeder. If the trigger is not depressed, |
| Some printers have an additional stepper motor | | | | the inkjet printer lights up the "Out of Paper" LED |
| to park the print head assembly when the printer | | | | and sends an alert to the computer. Once the |
| is not in use which means that the print head | | | | paper is fed into the inkjet printer and positioned |
| assembly is restricted from accidentally moving. | | | | at the start of the page, the print head stepper |
| The print head assembly uses a stabilizer bar to | | | | motor uses the belt to move the print head |
| ensure that movement is precise and controlled. | | | | assembly across the page. The motor pauses for |
| One of the paper feed assembly components is | | | | the merest fraction of a second each time that |
| the paper tray or/and paper feeder. Most inkjet | | | | the print head sprays dots of ink on the page and |
| printers have a tray that the paper is loaded into. | | | | then moves a tiny bit before stopping again. This |
| The feeder typically snaps open at an angle on | | | | stepping happens so fast that it seems like a |
| the back of the printer, allowing the paper to be | | | | continuous motion. Multiple dots are made at each |
| placed in it. Feeders generally do not hold as much | | | | stop. It sprays the CMYK (cyan / magenta / |
| paper as a traditional paper tray. A set of rollers | | | | yellow / black) colors in precise amounts to make |
| pull the paper in from the tray or feeder and | | | | any other color imaginable. At the end of each |
| advance the paper when the print head assembly | | | | complete pass, the paper feed stepper motor |
| is ready for another pass after which another | | | | advances the paper a fraction of an inch. |
| step motor powers the rollers to move the paper | | | | Depending on the inkjet printer model, the print |
| in the exact increment needed to ensure a | | | | head is reset to the beginning side of the page, |
| continuous image is printed. | | | | or, in most cases, simply reverses direction and |
| While earlier printers often had an external | | | | begins to move back across the page as it prints. |
| transformer, most printers sold today use a | | | | This process continues until the page is printed. |
| standard power supply that is incorporated into | | | | The time it takes to print a page can vary widely |
| the printer itself. A small but sophisticated amount | | | | from printer to printer. It will also vary based on |
| of circuitry is built into the printer to control all the | | | | the complexity of the page and size of any |
| mechanical aspects of operation, as well as | | | | images on the page. Once the printing is complete, |
| decode the information sent to the printer from | | | | the print heads are parked. The paper feed |
| the computer. It is connected to the computer by | | | | stepper motor spins the rollers to finish pushing |
| a cable through the interface port. The interface | | | | the completed page into the output tray. |
| port can be either parallel port, USB port or SCSI | | | | Most inkjet printers today use inkjet inks that are |
| port. The parallel port is still used by many | | | | very fast-drying, so that you can immediately |
| printers, but most newer printers use the USB | | | | pick up the sheet without smudging it. Compared |
| port. A few printers connect using a serial port or | | | | to earlier consumer-oriented printers, inkjet |
| small computer system interface (SCSI) port. | | | | printers have a number of advantages. They are |
| Different types of inkjet printers exist based on | | | | quieter in operation than impact dot matrix |
| the method they use to deliver the droplets of | | | | printers or daisywheel printers. They can print |
| ink. There are three main inkjet technologies | | | | finer, smoother details through higher printhead |
| currently used by printer manufacturers. The | | | | resolution, and many inkjet printers with |
| thermal bubble technology used by manufacturers | | | | photorealistic-quality color printing are widely |
| such as Canon and Hewlett Packard is commonly | | | | available. In comparison to more expensive |
| referred to as bubble jet. In a thermal inkjet | | | | technologies like thermal wax, dye sublimations, |
| printer, tiny resistors create heat, and this heat | | | | and laser printers, the inkjet printers have the |
| vaporizes ink to create a bubble. | | | | advantage of practically no warm-up time and |
| As the bubble expands, some of the ink is pushed | | | | lower cost per page (except when compared to |
| out of a nozzle onto the paper. When the bubble | | | | laser printers). |
| collapses, a vacuum is created. This pulls more ink | | | | The disadvantages of the inkjet printers include |
| into the print head from the cartridge. A typical | | | | flimsy print heads (prone to clogging) and |
| bubble jet print head has 300 or 600 tiny nozzles, | | | | expensive inkjet cartridges. This typically leads |
| and all of them can fire a droplet simultaneously. | | | | value-minded consumers to consider laser printers |
| Thermal inkjet technology is used almost | | | | for medium-to-high volume printer applications. |
| exclusively in the consumer inkjet printer market. | | | | Other disadvantages include ink bleeding, where |
| The ink used is usually water-based, | | | | ink is carried sideways away from the desired |
| pigment-based or dye-based but the print head is | | | | location by the capillary effect; the result is a |
| produced usually at less cost than other ink jet | | | | muddy appearance on some types of paper. Most |
| technologies. Contrary to the bubble jet | | | | inkjet printer manufacturers also sell special |
| technology, the piezoelectric technology, patented | | | | clay-treated paper designed to reduce bleeding. |
| by Epson, uses piezo crystals. A crystal is located | | | | Because the ink used in most inkjet cartridges |
| at the back of the ink reservoir of each nozzle. | | | | and ink tanks is water-soluble, care must be taken |
| The crystal receives a tiny electric charge that | | | | with inkjet-printed documents to avoid even the |
| causes it to vibrate. When the crystal vibrates | | | | smallest drop of water, which can cause severe |
| inward, it forces a tiny amount of ink out of the | | | | "blurring" or "running." |
| nozzle. When it vibrates out, it pulls some more | | | | Besides the well known small inkjet printers for |
| ink into the reservoir to replace the ink sprayed | | | | home and office, there is a market for |
| out. | | | | professional inkjet printers; some being for |
| The continuous inkjet method is used | | | | page-width format printing, and most being for |
| commercially for marking and coding of products | | | | wide format printing. "Page-width format" means |
| and packages. The first patent on the idea is | | | | that the print width ranges from about 8.5" to |
| from 1867, by William Thomson. The first | | | | 37". "Wide format" means that these are inkjet |
| commercial model was introduced in 1951 by | | | | printers ranging in print width from 24" up to 15'. |
| Siemens. In continuous inkjet technology, a | | | | The application of the page-width inkjet printers is |
| high-pressure pump directs liquid ink from a | | | | for printing high-volume business communications |
| reservoir through a microscopic nozzle, creating a | | | | that have a lesser need for flashy layout and |
| continuous stream of ink droplets. A piezoelectric | | | | color. Particularly with the addition of variable data |
| crystal causes the stream of liquid to break into | | | | technologies, the page-width inkjet printers are |
| droplets at regular intervals. The ink droplets are | | | | important in billing, tagging, and individualized |
| subjected to an electrostatic field created by a | | | | catalogs and newspapers. The application of most |
| charging electrode as they form. The field is | | | | of the wide format inkjet printers is for printing |
| varied according to the degree of drop deflection | | | | advertising graphics; a minor application is printing |
| desired. This results in a controlled, variable | | | | of designs by architects or engineers. |