What Is an Inkjet Printer?

How they work, their advantages, and their disadvantages

Inkjet printer with image of sunflower printing out

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Inkjet printers are the most popular choice for home printing needs. They work by propelling droplets of ink onto paper, as opposed to laser printers, which use toner and are used mostly for high-volume printing in office settings.

If you're considering purchasing an inkjet printer, here's a look at how they work and how they're used.

Inkjet printers are generally inexpensive and small, with the ability to print both high-quality images and text documents.

How an Inkjet Printer Works

An inkjet printer creates an image by firing tiny droplets of ink onto the paper. The print head moves back and forth as the document is fed through a set of rollers. The complete image is built up from many small dots, a bit like the pixels on a TV or phone screen.

The quality of an image is determined by the number of dots per inch (DPI) and the range of colors possible. A few different colors of ink can be combined to produce virtually any color. Yellow, red, and cyan ink are commonly used colors. These can be used to make black, although it's usually more economical if a separate black ink is used. Each color may be contained in a separately replaceable cartridge, or they may all be included in a single cartridge.

Inkjet cartridges have tiny computer chips that monitor the cartridge's ink level. When the ink gets low, you'll be prompted to replace the cartridge.

Refilling third party printer cartridges, inkjet.
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Inkjet Technologies

Several different technologies are used to propel ink onto paper. Most consumer printers use the thermal drop-on-demand (DOD) method. In this process, ink is pumped from a cartridge to a tiny reservoir sitting directly behind a nozzle. A small electric heating element is located in the reservoir. When a pulse of electrical current passes through, the ink's solvent vaporizes, causing an increase in pressure, which propels a drop of ink out of the nozzle. The bubble of vapor then condenses, contracting and drawing some more ink into the reservoir.

Some consumer printers, as well as most industrial printers, use a piezoelectric material instead of a heater. In these devices, a piezoelectric diaphragm, similar to a small speaker, sits at the back of the ink well.

Diagram showing nozzle for piezo and thermal inkjet nozzles

The print head contains the nozzle, reservoir, and heater or piezoelectric. In many consumer printers, the print head is part of a disposable ink cartridge, meaning it's replaced whenever new ink is required. In many more expensive printers, a fixed head is used.

Other technologies are used in large-scale commercial inkjet printers and other industrial devices. These often use a combination of ultrasonic vibration and electrical charge to propel and direct ink droplets in a continuous spray. Such printers may be much faster and use a greater variety of inks and dyes, including those which are solvent-based and ultraviolet curing. This can result in more durable and waterproof prints than can be achieved with consumer printers.

A man operating a commercial inkjet printer
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Other Uses for Inkjet Printing

Inkjet printing has an extensive range of uses. It's used for printing signs, billboards, and T-shirts, and even the "best before" dates on food, Special methods of inkjet material deposition have also been developed to print solder onto electrical circuit boards and living cells onto biosensors and biological scaffolds.

For most people, though, an inkjet printer is simply a relatively low-cost printer, capable of printing high-quality photos and documents.

Laser printers have to meet the demands of a workplace, so they can print faster (between 15 to 100 pages per minute, or ppm), while inkjet printers print more slowly at about 16 ppm.