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The ins and outs of laser printers

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The ins and outs of laser printers Powered By Docstoc
					The ins and outs of laser printers

This type of printing machine produces prints on paper or transparencies
using the toner particle exposure and printing processes. These printers
are different from ink-jet machines, exposure and pressure take place in
one pass. In common parlance, LED printers are usually referred to as
lasers, because the operating principle is very similar. Laser printer
Seattle is based on the xerographic printing procedure. Its centerpiece
is coated with a photo-conductor drum or endless belt.

In the early days, the coating of the imaging drum was initially
electrostatically charged, either by means of a corona charge (mounted
near the drum which generates a corona discharge under high voltage) or
by means of charge rollers. The latter has the opposite corona charge and
the advantage that it hardly produces any ozone is produced. This is
because the high voltage roller is in direct contact with the imaging
drum and thus ionization does not occur.

The first lasers designed to work with a personal computer were a
Hewlett-Packard Jet Classic. The first color lasers ColorScript 1000 were
built in 1993 by QMS. The pioneering Xerox 9700 built in 1977, was
monochrome enabled, with two-sided printing at 300 dpi and at 120 pages
per minute.

The main problem in the development of lasers revolved around the
modulation of their beams. In 1977 there were only gas lasers that were
not capable of reaching the required speed. Special lenses or
piezoelectric crystals moved mechanically, which distracted by the
applied voltage were the only way to accomplish this task. In the later
conventional diode lasers, however, it could be modulated with luminous
flux very quickly.

The data is supplied to the machine in an understandable format (called a
page description language), and then processed by the Raster Image
Processor. The control systems modulate the light beam generated by the
printing machine (raster output scanner), or combination of light-
emitting diodes (LED).

Light is directed to the drum to change the properties of photo-
conductive surfaces and thus allows the deposition of the image. In this
process, there is a ferromagnetic magnetic shaft, which approximates the
electrified particles of toner into the drum. The evolution of the laser
printer Seattle to the present is indeed a phenomenal one.


Form and function of a laser printer Seattle

Lasers are a type of printing machine that can impress text or graphics
in both black and color with great quality. These printers are very
efficient, enabling high-quality prints at remarkable speeds, measured in
terms of pages per minute (ppm). Laser printer Seattle is inherently more
expensive than inkjet, but the initial outlay is offset by the lower cost
of consumables. However, it should also be noted that once inkjet
printers dry up after lying idle for several months.

Lasers comprise a photoconductive drum attached to a   toner and beam,
modulated and projected through a mirror disc toward   the photoconductor
drum. The rotation of a disc causes the beam to scan   on the generatrix of
the drum. Monochrome printing is done using a single   toner.

Areas of the drum on which the beam impinges are ionized. The printing
machine's drum comes into contact with paper dust infusing the
corresponding zones. As a result, ink is finely deposited on paper via
dual action of pressure and heat.

Lasers impress on paper by depositing the toner particles. The principle
of these printers is very similar to the operation of photocopiers and
consists of several stages. Preparation of the shaft entails covering it
with a photosensitive material such as selenium, OPC (organic
photoconducting cartridge) or silicon. When exposure takes place the roll
is irradiated with light or LED bar.

With single-pass printers, the text is formed in a single passage of
paper through the machine (transmission from the photosensitive drum to
the media). The belt (if any) only serves an auxiliary function, such as
cleaning excess toner from the machine's drum.

With laser printer Seattle, printing of individual color components is
based on drum lighting and toner deposits, because the technology in
color lasers is a bit different. Although the color black can also be
obtained by mixing three primary colors, using a special black toner
improves print tonal depth and reduces toner consumption.

Basic overview of laser printer Seattle

Lasers are printing machines whose technique is derived directly from the
xerographic system, they offer exceptional print speeds and quality. From
1969 to date, the development of these machines has been very fast.
Originally, the printing environment was reduced to the machine itself,
now it comes with a range of options: toner, paper, service, software and
online tools. Laser printer Seattle surpasses the ink-jet models in terms
of print quality and speed.

The instant fuser technology provides increased print speed and economy
in power consumption. In summary, it boosts productivity with fast
printing. For example, in previous versions, it took 40 seconds to warm
up the printing machine. With the instant fuser, warming is 15 seconds.
It also helps save money through low power consumption and it is a
quieter system because it does not use cooling fans.

The cylinder is bathed in a fine powder black color, which is positively
charged and thus is attached to the negatively charged particles in the
cylinder. The parties repel the positively charged toner powder called
English toner (dry ink) - through which the visible impression is formed
on the drum.
The image formed along the drum is transferred to paper by means of a
greater negative charge (corona transfer). The toner deposits onto paper,
by means of a pair of rollers, one to generate heat and the other for the
purpose of pressing the sheet (otherwise known as fixing). To return to
the initial state, any toner remaining on a drum is cleaned by means of a
plastic sheet and at the same time light impinges on the cylinder to
completely discharge it.

Shades of gray can be achieved through halftoning, a similar procedure
with other colors is also possible. Higher-quality lasers achieve
superior resolutions in full-color system. With them, the charge onto a
drum is not reduced in a step to zero, but they can be attenuated in
stages (up to 256). The attenuation is reached either at mono exposure
times or by multiple exposure of the corresponding point.

The world of laser printer Seattle is making headway, transforming cycle
printing. According to studies of some businesses, these printers when
used in small and medium businesses they offer superior print quality on
any paper and provides better response to cycles of demanding work.

				
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