Inkjet printers were an evolution of dot-matrix printers. They use hundreds of tiny guns to fire dots of ink at the paper. The characters they print are still made up of dots, just like in a dot-matrix printer, but the dots are so small that you cannot see them.
Different types of inkjet printer fire the ink in various ways.
In some printers, the ink is fired by heating it so it explodes toward the paper in bubbles.
This is why Canon sells its printers under the brand name "Bubble Jet."
The ink boils due to a current through a resistor. The vacuum formed by each bubble draws a new bubble through the nozzle.
Other printers work a different way. They use an effect called piezoelectricity.
Electric currents controlled by electronic circuits inside the printer make miniature crystals jiggle back and forth, firing ink in jets as they do so.
An ink droplet from 1 moves to 2 via capillary action. Then, the contacts at 3 are energised causing 4 to flex forward, pushing 5
forward as well. Finally, this causes 6 to push the ink
droplet onto the paper.
Laser printers put dry ink powder (toner) on the paper using static electricity.
The toner is negatively charged, meaning it is attracted to positively charged things and is repelled from negatively charged things.
The laser used, when it hits things, gives them a negative charge. This can be used to decide where the toner should stick to the paper.
- The computer decides to print something, and the “Corona Wire” is activated, giving everything nearby a strong static charge.
- The Corona Wire coats the “Photoreceptor Drum” in a uniform positive charge.
- The laser is activated, and it coats sections of the drum with negative charge. The negative charge represents where NOT to put toner, so the laser actually draws a negative image.
- Toner dust is rolled onto the photoreceptor drum. It sticks to the positive sections and is repelled by the negative sections.
- The dry toner dust is rolled onto the paper as it makes its way through the printer.
- The fuse sticks the toner onto the paper for good by heating it up. The paper is dispensed out of the printer.