How Does an Inkjet Printer Work?

Twenty or thirty years ago, many people thought computers would render paper obsolete. Xerox Corp, which pioneered photocopiers in the 1960s, became so worried that paper might disappear (taking with it its lucrative business) that it set up a famous laboratory called PARC to develop computers instead. Ironically, even though Xerox PARC has contributed to inventing the computers we all rely on today, paper has remained as popular as ever. Now, thanks to the popularity of home computers and digital cameras, an increasing number of people have printers at home, most of which are inkjets. But how exactly do they work?

Inkjet Printing

Inkjet printers are an evolution of dot-matrix printers. Instead of metal needles, they use hundreds of tiny guns to fire ink dots at the paper. The characters that they print still consist of dots, just like in a dot-matrix printer, but the dots are so tiny that you can barely see them. Different inkjet printers fire ink in different ways. In Canon printers, ink is fired by heating it, so it explodes toward the paper in bubbles. That is why Canon sells its printers under the brand name “Bubble Jet.” Epson printers function differently. They use an effect called piezoelectricity. Tiny electrical currents controlled by electronic circuits inside the printer make miniature crystals jiggle back and forth, and fire ink jets as they do. You can think of inkjet printers, very simply as a firing squad of nozzles, rattling off millions of ink dots on the paper every second.


How Do Inkjet Nozzles Work?

How do the ink nozzles in a thermal Bubble Jet printer eject ink on a page?

  • Instructed to do so by your computer, an electronic circuit inside the printer determines which nozzles to fire to print a particular color at a certain point on the page.
  • The circuit activates each nozzle by passing an electric current through a small resistor inside it.
  • The resistor heats up when electricity flows through it.
  • Heat from the resistor boils the ink inside the nozzle that is at once next to it.
  • As the ink boils, it generates a bubble of ink vapor. The bubble expands enormously and bursts.
  • When the bubble bursts, it ejects the ink that it contains on the page in a precisely formed dot.
  • The collapsing bubble creates a partial vacuum in the nozzle, which draws out more ink from the tank, ready for printing the next dot.
  • Meanwhile, the print head moves entirely to the side, ready for printing the next character.


  1. What are the main parts of an inkjet printer and what is the role of each one?

In an inkjet printer, we have:

  • Gears, driven by an electric motor, to rotate the rollers that advance the paper through the printer.
  • A flat flexible cable to carry the printing instructions from the electronic circuit inside the printer to the mobile cartridge.
  • Plastic and rubber rollers to pinch the paper so that it can be moved through the printer with absolute precision.
  • A sturdy metal rail to guide the printer head as it moves back and forth.
  • Spiked wheels at the front of the printer to help grip the paper securely and move it with precision.
  • The print cartridge to print from left to right, then reverse the printing information and print backwards from right to left. This is known as bidirectional printing. It allows you to print pages much faster.
Categories: Printer, Ink Cartridge

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