Laser Printers

1. Printers LaserPrinters

2. The Laser Components of a Laser Printer Here are the main components of an laser printer Laser Printer Printers

3. Components of a Laser Printer Components Controller circuitry Photoconducting drum Charging roller Laser beam Rotating mirror Developer roller Toner hopper Belt or roller assembly Paper tray Charging wire Cleaning blade Fuser Laser Printer Printers

4. Electric Charge Static Electricity Static Electricity occurs when electric charge is built up in an insulated object. Since oppositely charged atoms are attracted to each other, then objects with opposite static electricity cling together. - - + + + - - - + + + + + + - - - - Excess of electrons Balanced atoms Deficiency of Electrons (Net negative charge) (Net charge zero) (Net positive charge) Laser Printer Printers

5. The Basics The Corona Wire Initially, the photoconducting drum is given a total positive charge by the charge corona wire (or sometimes use a charging roller). The Corona Wire + + + Photoconducting drum + Laser Printer Printers

6. The Basics Laser Beam As the drum revolves, a tiny laser beam is focused across the surface of the drum. The charge on the roller is discharged at certain points, reversing the charge, creating an electrostatic image. Reverses the charge - The Corona Wire Laser Beam + Electrostatic patterned image is set + + Positive charge Photoconducting drum + Laser Printer Printers

7. The Basics Toner After the pattern is set on the drum, the printer coats the drum with positively charged toner (powder). The positively charged toner is attracted to the discharged (negatively charged) areas on the drum. Reverses the charge - The Corona Wire Laser Beam + Developer roller Photoconducting drum Toner hopper + + Positive charge + Laser Printer Printers

8. The Basics Paper The photoconducting drum now rolls over a sheet of paper, which is moving along a belt below. Reverses the charge - The Corona Wire Positive charge Laser Beam + Developer roller Photoconducting drum Toner hopper + + The Corona Wire + Paper Laser Printer Printers

9. The Basics Paper: negatively charged The paper is negatively charged using a corona wire. Reverses the charge - The Corona Wire Positive charge Laser Beam + Developer roller Photoconducting drum + Toner hopper The Corona Wire - - - Negative charge Paper Laser Printer Printers

10. Toner transferred to paper The Basics Toner displaced The Corona Wire Positive toner is transferred onto strongly negatively charged paper. The paper is then immediately discharged. Positive charge + Reverses the charge + Laser Beam Developer roller Photoconducting drum Toner hopper The Corona Wire - - - - Negative charge Paper Laser Printer Printers

11. Toner transferred to paper The Basics The Fuser Finally, the paper passes through a pair of heated rollers that melts the loose toner paper, fusing the fibers in the paper. Heated rollers Powdered toner Melted toner Paper Negative charge No negative charge Melts the loose toner (Discharge) Laser Printer Printers

12. Summary Data is transferred, buffered and sent to the printer’s processor. The photoconducting drum is given a positive charge by a corona wire or a charging drum. As the drum revolves, a tiny laser beam is focused on the drum, discharging the drum at certain points forming an electrostatic image. The developer roller coats the drum with positively charged toner. The positively charged toner is attracted towards the discharged areas. The photoconducting drum now rolls over negatively charged paper, attracting the positively charged toner. The paper passes between two heated rollers that melt the powdered toner fusing the fibers in the paper. Laser Printer Printers