Components of a laser printer
Main power supply
The main power supply of a laser printer converts the AC voltage into DC voltage used in various circuit boards and the other parts of the printer. These DC voltages include +24 volts, +5 volts, and –5 volts.
High-voltage power supply
The high-voltage power supply produces very high voltages which are used in the printing process. The high voltages are used to charge with electrons, the EP drum, the toner, paper, and the corona wires.
The EP drum is the revolving cylinder that is coated with a highly photo conductive material (also called a photo receptor). This drum is charged with a highly negative voltage (–600 volts) by the primary corona wire. Then, as the drum rotates, a highly focused laser beam strips the charge from certain points on the drum.
Main motor assembly
This assembly is used for the movement of different rollers inside the laser printer.
Scanning motor assembly
The parts in this assembly contain certain motors and mirrors which move the laser beam over the EP drum.
Primary corona wire
The primary corona wire is what is used to charge the EP drum with the high negative voltage (–600 volts).
Transfer corona wire
The transfer corona wire is used to charge the surface of the paper. It charges the surface with a high positive voltage so that it will attract the negatively charged toner.
The writing mechanism is what guides the laser beam over the EP drum according to the output of the printer memory.
The toner cartridge is made from a number of sub-assemblies which include the toner, and a cleaner blade.
The fuser assembly of the laser printer contains heat and pressure rollers to properly bond the toner particles to the paper. This is why when a paper first comes from the printer its hot.
The erasing mechanism is used to remove the transferred image from the EP drum after tit has been copied to the paper.
The cleaning assembly is used to remove any residual toner particles from the surface of the EP drum.
Paper movement assembly
The Paper movement assembly is used to move the paper through the different parts of the printer.
Electronic control package
The Electronic control unit, which is also known as the logic assembly, contains the main circuit board of the laser printer that communicates with the PC to receive the print jobs. This assembly contains the raster image processor (RIP) that converts incoming signals into the signals used by the other sections of the printer.
This is the user interface located on top of the printer and this contains different controls and buttons. High-end laser printers now include a touch screen as well as the buttons to get user input.
The Connection interface connects the printer to the computer or also to the network. It can be connected via a parallel, serial, USB, IEEE 1394, or a network port depending on the type of printer.