When you think of a printer, you probably think of a humming electronic device. But that's just the latest version in a long line of inventions! Printing is one of the oldest technologies in the world. From stone cylinder seals rolled on wet clay in ancient Mesopotamia, to woodblocks pressed on fabric in 5th century China, printing has taken many different forms.
Today, you can type up a book report and get a nice, fresh copy with a few clicks. Modern computer printers take digital text files or images and transfer them quickly to paper. There are two main types of printers, impact and non-impact. Impact printers have to touch the paper to print an image, and non-impact printers don't.
Laser printers are an example of non-impact printers. Have you printed something at the library before? You might have used a machine that is both a printer and photocopier. Laser printers work like photocopiers, using static electricity.
Is there actually a laser inside a laser printer? Yes! It draws all the words and pictures in your book report as a pattern of electrical charges. This is called an electrostatic image. Aside from lasers, there are a bunch of other important parts inside printers: mirrors, lenses, wires... there's even a small computer called a printer controller! The controller is in charge of putting your book report together for the laser to receive. It turns the text and images into countless tiny dots.
A revolving drum is coated with a fine, black powder called toner. When the drum rolls over a sheet of paper, static electricity pulls the image on to the paper. The paper then goes through heated rollers called a fuser. As the toner powder melts, it bonds with the fibers in the paper. This is why pages are hot when they come out of the printer!
As technology advances, there will be new ways of printing. Johannes Gutenberg would have been pretty amazed that you can use 3D printers at the library! You can print a keychain, a lunch box, a piggy bank, toys, tools and so much more. What else can printers do in the future? Dream it and invent it!