|Red Hat Enterprise Linux 3: Introduction to System Administration|
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An older technology than inkjet, laser printers are another popular alternative to legacy impact printing. Laser printers are known for their high volume output and low cost-per-page. Laser printers are often deployed in enterprises as a workgroup or departmental print center, where performance, durability, and output requirements are a priority. Because laser printers service these needs so readily (and at a reasonable cost-per-page), the technology is widely regarded as the workhorse of enterprise printing.
Laser printers share much of the same technologies as photocopiers. Rollers pull a sheet of paper from a paper tray and through a charge roller, which gives the paper an electrostatic charge. At the same time, a printing drum is given the opposite charge. The surface of the drum is then scanned by a laser, discharging the drum's surface and leaving only those points corresponding to the desired text and image with a charge. This charge is then used to force toner to adhere to the drum's surface.
The paper and drum are then brought into contact; their differing charges cause the toner to then adhere to the paper. Finally, the paper travels between fusing rollers, which heat the paper and melt the toner, fusing it onto the paper's surface.
Color laser printers aim to combine the best features of laser and inkjet technology into a multi-purpose printer package. The technology is based on traditional monochrome laser printing, but uses additional components to create color images and documents. Instead of using black toner only, color laser printers use a CMYK toner combination. The print drum either rotates each color and lays the toner down one color at a time, or lays all four colors down onto a plate and then passes the paper through the drum, transferring the complete image onto the paper. Color laser printers also employ fuser oil along with the heated fusing rolls, which further bonds the color toner to the paper and can give varying degrees of gloss to the finished image.
Because of their increased features, color laser printers are typically twice (or several times) as expensive as monochrome laser printers. In calculating the total cost of ownership with respect to printing resources, some administrators may wish to separate monochrome (text) and color (image) functionality to a dedicated monochrome laser printer and a dedicated color laser (or inkjet) printer, respectively.
Depending on the type of laser printer deployed, consumable costs usually are fixed and scale evenly with increased usage or print job volume over time. Toner comes in cartridges that are usually replaced outright; however, some models come with refillable cartridges. Color laser printers require one toner cartridge for each of the four colors. Additionally, color laser printers require fuser oils to bond toner onto paper and waste toner bottles to capture toner spillover. These added supplies raise the consumables cost of color laser printers; however, it is worth noting that such consumables, on average, last about 6000 pages, which is much greater than comparable inkjet or impact consumable lifespans. Paper type is less of an issue in laser printers, which means bulk purchases of regular xerographic or photocopy paper are acceptable for most print jobs. However, if you plan to print high-quality images, you should opt for glossy paper for a professional finish.