First the computer communicates with the printer through a page description language. The page description language (PDL), usually installed into the printer, enables the printer to make the whole age that will be printed, thus freeing part of the computer’s memory for other tasks. All the creates the page that is send a description of the page to the printer and the PDL creates the page that is to printed. Among the PDLs that are available. Adobe System Inc’s Postscript is the most popular. Other popular PDLs include the Hewlett-Packard’s Printer Command Language (HP PCL5) and Canon’s CaPSL.
When the PDL (in the laser printer) receives the digital signal from the computer, it starts the page-making process and activates the printer’s engine (the Laser), turning the semiconductor laser diode on and off.
Now, here is where the most interesting part begins. The toner cartridge which carries the toner, actually a fine black powder is charge negatively and applied to the drum. Well, if you know the simple rule of electrostatics, you will by now be able to predict what will happen when the toner gets in contact with the drum.
Okay, so the image has been made. What now? Quite obviously, the image formed on the drum will have to be transferred to paper. A paper is then fed into the laser printer for the transfer of the image from the drum onto the toner. The paper, carrying a strong positive charge, passes the roller and the charge attracts the toner to the paper. But the toner is still not permanently set onto the paper. At this phase, if you were the take paper out of the printer, the toner will just “drop” off the paper like dust.
Two main engines used in the laser printers are the laser engine and the LED (light emmiting diode) engine. It doesn’t mater which engine the laser printer uses, they are all called laser printers. (Erm, now you see why i had earlier suggested that these printers be called electrostatics printers)
Image resolution in a laser printer makes curves in laser print more refined, unlike dot-matrix printers. With image resolution technology, text and graphics are nicer to read and look at. Looking at the trends today and the increasing deman for clearer print quality, laser printers are continuously evolving to provide better printouts.
But while the printing ability of the printer may be enchanced, the way laser printers work will always remain basically the same.