How does a laser printer work?

It turns the digital documents into printed pages. It is fast but to find out how, we have to open the printer. Inside the print cartridge...

there are two main components;

1- the drum
2- the toner hopper.
When the print job starts the drum begins to turn. It rushes against an electrically charged roller that coats the surface of the drum with negative electricity. The drum has a light sensitive surface and as it turns it gets hit by a pulsing laser beam. As the laser works line by line, it zaps the drum one million times per second; it creates more and more neutral spaces, until they form an image of the document on the drum. For that drum to print the image on the paper, it needs to fill those neutral spaces with toner.

How does that happen?

By steering the toner inside the hopper the toner is engineered so that the friction from steering generates static electricity.

So how does that toner get to the drum?

Just outside the hopper there is a roller that gets covered with toner, as the drum turns to pass the roller the toner has no choice. Since the toner carries negative charge it is attracted to the neutral spaces on the drum. At the same time, the toner is repelled by negative charges that cover the rest of the drum. So the toner only sticks to the spaces hit by the laser. Now, the toner forms a mirror image of the document on the surface of the drum.

While all of these are happening the printer is charging a piece of paper with positive charges of electricity. The rolling drum carries its toner image down onto the paper.

The moment of truth! That greater force of attraction pose the toner off of the drum and onto the paper. Now, the image of that text is on paper. One last roller heats up to 400 degrees Fahrenheit. Its job is to melt the toner permenantly onto the paper to create a printed page.