#511 How does a laser printer work?

How does a laser printer work? They use static electricity to imprint an image onto the paper.

Inkjet printers and laser printers are different in that inkjet printers use ink and laser printers don’t. An inkjet printer has liquid ink attached to nozzles that are fixed into the print head. When you want to print an image, the printer sprays microscopic droplets of ink through these nozzles onto the page. They can spray so accurately that they can recreate the most complex of images. Inkjet printers can make very clear images, but they are slow and not great if you are printing in large quantities.

Most printers are filled with cyan, magenta, yellow, and black ink (known as CMYK – black is K and it stands for Key color). These are the most common colors and the printer can mix these to make over 16,000 different shades of colors. Why do printers use CMYK instead of RGB? RGB stands for red, green, and blue, and they are the primary colors. They are the colors our eyes detect and they are how we can see in the world. Printers don’t use RGB because it is difficult to make light colors with them. CMY can be used to make lighter colors and then black, the key color, can be added to make darker colors.

So, how does a laser printer work? The laser printer works with rollers. There are usually four rollers in a printer and there is one for each CMYK color. Each roller is supplied from a hopper that contains toner, which is made of ink particles and is not liquid ink. When you press print on your computer, the image is transferred to the printer and broken down into its different color components. Each of the CMYK rollers will add their color to the image. While this is happening, the printer powers up the corona wire, which has a negative charge. The corona wire transfers this negative charge to each of the four rollers, making them negatively charged as well.

Once the printer has worked out which rollers will print which part of the image, it uses a laser to transfer the image to the rollers. The rollers rotate, but the laser itself doesn’t move. A mirror inside the printer moves to angle the laser. The laser is positively charged, and where it hits the roller, it changes the charge from negative to positive, making an impression of the image with a positive charge. The toner inside the hopper is stirred to give it a negative charge. When it is moved towards the roller, it sticks to the positively charged areas of the roller and not the negative because opposite charges attract.

The paper is fed through the printer and it is given a positive charge as it goes. When the paper comes in contact with the roller, it has a greater charge than the roller and it attracts the negatively charged toner particles off the rollers and they stick to the paper. It passes all four of the rollers, adding the colors one after another and making the finished image. Finally, the paper is sent through a fuser unit. This is made of two heated rollers that fuse the toner to the paper.

The laser printer was invented in 1969 by Gary Starkweather. He was working at the Xerox research lab and he developed the Xerox 9700, the world’s first laser printer. He was working with a photocopier and he had the idea that a laser could draw the image onto the drum.

Laser printers are much faster than inkjet printers and they are better for large copies of the same thing. A modern laser printer can print over 40 pages per minute. The fastest laser printer in the world is made by Brother and can print 100 pages per minute. They had to reinvent the way that the paper is fed into the printer because at the high speeds they wanted to print at, the old style of paper feeder would just jam.

Printing technology is improving year by year, but the next largest leaps will probably be in the field of 3D printing. There are different ways of 3D printing and the costs are coming down. It is already to 3D print biological parts and one day, it may be possible to 3D print a whole organ. That would be wonderful. If your liver fails, the hospital can 3D print a new one for you, using your own cells, so that you won’t reject it, or need immunosuppressants. And this is what I learned today.

Sources

https://techglimpse.com/brother-unveils-worlds-fastest-laser-printer-print-100-pages-minute/

https://en.wikipedia.org/wiki/Laser_printing

https://www.xerox.com/en-us/office/insights/laser-printers

https://www.binarytides.com/best-high-speed-laser-printers/

https://www.reliancedigital.in/solutionbox/your-next-printer-should-be-a-laser-printer-heres-why/

https://home.howstuffworks.com/photocopier6.htm

https://www.thehealthyjournal.com/faq/why-is-it-rgb-instead-of-ryb