Inkjet printers grew out of dot-matrix printers, but instead of tiny metal needles, they use hundreds of tiny nozzles to fire tiny splodges of ink at the paper. The print is still made of dots, as in a dot-matrix printer, but they’re so small you can’t see individual marks.
Some types of printers use piezoelectricity. In these models, small electric currents directed by circuits cause miniature crystals to move backwards and forwards, firing out ink in jets. To put things simply, inkjet printers are an assembly of thousands of nozzles working together in sequences to fire out countless dots of ink to make words and images.
How do the nozzles work, how does the ink get onto the page?
In other models, the ink is heated and fired out of nozzles; an electric circuit in the printer determines which group of nozzles have to fire out ink. They “decide” which character is to be created and whereabouts on the page it should go. There are hundreds of nozzles, each one ten times as fine as a human hair, which come together to make one single character.
The electric circuits fire up each nozzle by passing a current through a resistor next to it. This heats the nozzle up, boiling the ink inside. As the ink boils, it turns into a bubble of ink, which grows and bursts out of the nozzle, spilling onto the paper. Who knew those humble-looking packages you bought from cartridgepeople.com were so complex inside?
The collapse of the bubble makes a partial vacuum in the nozzle, which draws in more ink from the reservoir, ready to create the next dot.
While this process happens, the printhead of the cartridge is moving along, ready for the next character.
So, characters and images are built up from millions of microscopic dots. With dot-matrix printers, there may be 64 metal needles, which make each character using 64 dots. Inkjet printers, on the other hand, fire out thousands of dots to create print and images of much higher quality. An average inkjet printer can achieve 600 dots per inch (dpi), which is almost ten times as dense as a dot-matrix printer. High-end photo-quality inkjet printers can manage as high as 5,000 dpi.
Along the bottom of a printhead, you’ll see a number of slits where the inkjet nozzles lie. Generally there’ll be one long slit for the black ink and three smaller ones for the coloured inks. There are also copper connectors which link up the cartridge to the “brain” of the printer.
The inkjet nozzles of a cartridge create a page of text or an image by building them up from millions of tiny dots. The printer’s computer, linked to your PC or laptop, controls what the nozzles do as the cartridge moves from left to right and back again across the page. As it moves it deposits the ink on the paper as directed by the PC and once the cartridge reached the end of a line, the paper is moved forwards so the next line can be laid down.
Phew! It sounds exhausting just reading it!