The vast majority of domestic printers are inkjet printers. They are cheap, reliable, and accurate. They work by positioning small droplets of ink onto paper. Each tiny 60 micron drop contains a different amount of a primary colour. To the human eye, theses colours merge to form the desired colour, similar to phosphor dots on a tv screen combine to form a colour, but unlike a TV, photo quality can be achieved with the modern inkjet printer, due to it's ability to print at such a high 'resolution'. .

There are a few main methods by which inkjet printers work.

1. Principles of the Piezoelectric Ink-Jet

Ink is fed into the print head. Inside the print head, there is a piezoelectric crystal in a resevoir controlled by small electrical signals to which the crystal reacts by changing shape very quickly. The vibration to and fro causes a tiny amount of ink to be pushed out of the print head each time, while drawing in a similar amount of ink from the ink supply into the head. The electric charges on the print head are used to electrically attract the ink, so that it doesn't leak out.

Epson Printers are usually of the Piezoelectric type.

2. Principles of the Bubble-Jet Inkjet Printer

With a similar print-head architecture to the piezoelectric printer, the bubble jet creates ink vapour bubbles on the wall of the print head, by heating in short bursts from heating resistors. The tiny bubbles push a tiny amount of ink out from the head, and when it cools, a vacuum is created which draws ink from the ink supply. A bubblejet may have hundreds of thermal nozzles.

(Currently this ink jet principle is mainly used by EPSON, HP, CANON, LEXMARK etc. products)

3. Resolution ( DPI ( dots per inch ) )

This is the important measure of defining print quality. and represents the represents the number of the color dots per inch length including both the horizontal and vertical directions. DPI is an abbreviation of "Dots Per Inch".

(Currently inkjet printers have 5 different DPI ranges of about 300/360DPI, 600/720 DPI, 1200/1440 DPI, 2400/2880/5765 DPI etc.)