Laser Printer Copiers
Good quality copying made by laser beams
A laser printer copier is a model that uses a laser printer to give your copies better quality reproduction. Laser printers use a xerographic printing process however the images and text are made by a laser beam which scans across the printer's internal drum. The first laser printer was made in 1971 by the Xerox Company when a researcher modified a Xerox copier in 1971 however the first commercial laser printer brought out by IBM in 1976.
Laser printers can reproduce a combination of text and images, including various fonts and halftone images. Laser printers use toner, which is a black powder, instead of ink and they don’t require special paper. Laser printer copiers are generally better than inkjet printers as they have higher resolution, no paper smearing, lower cost per page, and are able to print faster as the entire page is imaged at the same time. However, laser printers always produce raster images, and usually only top of the line models can reproduce continuous tone images such as photographs.
Printer speed on a laser printer copier can vary and the slowest printers can produce about four pages per minute. The speed depends on many factors though, including the complexity of the page that’s being copied. The fastest laser copiers can print over 200 black and white pages a minute and about 60 color pages per minute. A duplexing laser printer can print on both sides of the paper [Copier Paper] and will cut your paper costs down.
There are basically six steps involved in laser printing:
- Charging
A corona wire or primary charge roller shoots an electrostatic charge onto a photosensitive surfaced revolving drum.
- Writing
A Raster Image Processor (RIP) chip is used to convert the incoming images and text to a raster image that can be scanned onto the drum. The laser is pointed at a moving mirror which guides the laser through various lenses and mirrors and then onto the drum. Lasers are ideal as they can produce a coherent beam of light, which results in a high level of accuracy. Wherever the laser hits the drum the charge is reversed, creating an electro-photographic image on the surface of the drum.
- Developing
The drum’s surface passes through the particles of charged toner and the toner is electrostatically attracted to the drum where the laser created the image;
- Transferring
The drum presses itself or rolls over the paper and transfers the image onto it. Some models have a positively charged transfer roller which pulls the toner from the drum onto the paper.
- Fusing
The paper goes through a fuser assembly, where hot and pressured rollers melt the powdered toner to the paper. The toner is easily melted as it contains wax or plastic.
- Clean up
When the job is done a rubber blade takes any excess toner from the drum and puts it into a reservoir, and a discharge lamp then takes away any remaining charge from the drum.
While most laser printers go through this process, these steps are often carried out in distinct ways by different models. Some lasers use a linear array of light-emitting diodes (LED) to write the light onto the drum. The paper may or may not be oppositely charged and the fuser may be an infrared oven, a heated roller, or a xenon flash lamp. Most high end multifunction copiers also use this laser system.
