Electrostatics

Laser Printers

About Laser Printers

The term laser printer is a bit mysterious. How can a laser beam, a highly focused beam of light, write letters and draw pictures on paper? Very few of us ever consider the drum, the fuser, the data exchange, or the static electricity that all come together to print our memos. In this flyer we will unravel the mystery behind the laser printer, and as you will found out, laser printers are based on some very basic scientific foundations, adjusted in an exceptionally new way

How laser printers work

The primary principle at work in a laser printer is electrostatics, also known as static electricity. Static electricity is simply an electrical charge built up on an insulated object. A laser printer uses this phenomenon as a sort of "temporary glue." The core component of this system is the photoreceptor drum. This drum assembly is made out of highly photo conductive material that is discharged by light photons. The drum is given a total positive charge by the charge corona wire, a wire with an electrical current running through it. As the drum revolves, the printer shines a tiny laser beam across the surface to discharge certain points. In this way, the laser "draws" the letters and images to be printed as a pattern of electrical charges (an electrostatic image). After the pattern is set, the printer coats the drum with positively charged toner (a fine, black powder). Since it has a positive charge, the toner clings to the negative discharged areas of the drum, but not to the positively charged "background." Finally, the printer passes the paper through the fuser, a pair of heated rollers. As the paper passes through these rollers, the loose toner powder melts, fusing with the fibers in the paper. The fuser rolls the paper to the output tray, and you have your finished page.

Why are laser printers better then inkjet printers?

Considering what goes into a laser printer, it is amazing they can be produced for so little money, which makes the price for a laser printer much less compared to an inkjet printer. In many ways, the components which make up a laser printer are far more sophisticated than those in a inkjet printer (these printers put an image on paper using tiny jets of ink). The engineering which goes into the bearings for the mirrors is very advanced; and the choice of chemicals for the drum and toner is fascinating. Getting the image from the PC’s screen to paper requires an interesting mix of coding, electronics, optics, mechanics and chemistry. Also toner has many advantages over the liquid ink that is used in inkjet printers. Laser printers can print documents at a much faster rate than inkjet printers. That is why laser printers are a much better choice then inkjet printers