How Laser Printers Work

Laser Printers build characters by placing dots on a page. The entire page is composed in the printers memory, then transferred to the print engine for printing. The process is called raster technology. Raster refers to how characters and graphics are built by the printer's controller. With raster technology, each character is composed of a series of dots that fill in a grid. Creating characters this way is very similar to filling in a checker board with checkers.

Laser Printers have become very popular because of their flexibility in printing high resolution raster images in a short amount of time. Laser Printers are based on a variety of technologies. The most common technology is electrophotographic. Simply stated, this technology utilizes toner and electricity. Toner, which is negatively charged, is attracted to paper from the fuser or corona wire. The positively charged wire draws toner to the paper and the toner is burned onto the paper from the fuser assembly.

Printer Language

Equally important to the print quality of a laser printer is its language. There are a wide variety of languages available. The most common are: Hewlett Packard's PCL4, PCL5 and HPGL/2, as well as Adobe's Postscript Level 1 and Postscript Level 2.

HP PCL is ideal for generating text and graphics. The PCL language has extensive support for how text is placed on a page, where graphics and text are placed, how text flows around a graphic and which fonts are included in a document. Most laser printers operate with a PCL language as its primary emulation. The PCL is normally transparent to the end user.

Adobes Postscript language is used throughout the desktop publishing world. It is also ideal for high end graphics, CAD and other word processing documents. The advantages of postscript include improved performance, enhanced functionality and expanded compatibility.

Selecting the right printer emulation, or language is a lot like choosing the right garden tool. Each language has its own strengths and weakness. If you work in an office environment and need to print spreadsheets and letters, HP PCL is probably the right language. For intensive, desktop publishing applications, Postscript is probably the language for you.

Resolution

Most printers are rated by dots per inch (DPI). DPI is the number of dots per inch that a printer can printer. The higher the resolution, the more precise and sharper the image. The early DPI ratings for most laser printers was 300 x 300 DPI. This DPI setting was very common in HP Laserjet II, III and IIp. Upon the advent of Laserjet IV. The standard was pushed up to 600 x 600 DPI. 300 x 300 DPI is an acceptable rating for most business environments.

Laser Printer Speed

Laser printer speed, PPM (pages per minute) is one of the most important factors when purchasing a laser printer. Laser Printers are divided into different segments, depending upon usage.

1 - 4 PPM

Laser printers in this category are low end printers that are normally personal laser printers. The most common uses include: simple word processing, infrequent use of special fonts and simple documents. Prices for these speed range from $300 to $600

6 - 10 PPM

This class of printers are office printers. These are the most common printers people see today. Prices range from $500 to $1500 for these printers.

12 - 20 PPM

Printers in the 12 - 20 PPM range are high end network printers. Price vary from $1500 - $3000. These printer exist in a department or network environment.