Laser Printing

Understand Print-Based 

Media Production

Techniques & Technology 

DIGITAL

Laser Printing

It's an electrostatic digital printing process that rapidly produces high quality text and graphics, by passing a laser beam over a charged drum to then define a differentially charged image. The drum then selectively collects charge from a toner and transfers the image to paper, which is then heated to permanently fix the image. With the digital photocopiers and multifunction printer (called MFPs), laser printers employ a xerographic printing process, but this differs from analog photocopiers, in that the image is produced by the direct scanning of the medium across the printer's photoreceptor, this is why it proves to be a much faster process compared to the latter.

Design

The laser beam projects are an image of a page thats to be printed upon an electrically charged rotating drum coat, which has an selenium or, more common in modern printers - organic photoconductors.
Photoconductivity allows the charge to leak away from the areas that are exposed to light. Powered ink (toner) particles are then electrostatically picked up by the drum's charged areas, these have not been exposed to light. The drum then prints the image onto a paper by direct contact and heat, this then fuses the ink to the paper.

Depending on many factors, laser printers' speeds can vary widely including the graphic intensity of the job processed. 
- the fastest models can print over 200 monochrome pages per min (that's 12,000 pages per hour)
- the fastest colour laser printers can print over 100 pages per min (meaning 6,000 pages per hour)
The very high speed laser printers are used for mass mailings of personalized documents, such as;  credit card or utility bills. These are competing with lithography and in some commercial applications.

Costing for this technology depends on a combination of factors;
Including -
The cost of paper
Toner
Infrequent drum replacement 
The replacement of other consumables;
Such as -
The fuser assembly
Transfer assembly

Often the printers with soft plastic drums can have a pretty high cost of ownership that doesn't become apparent though, until the drum requires replacement.

Duplex Printing -printing on both sides of the paper

This can halve the paper costs and reduce filing volumes.

Only available on high-end printer, these duplexers are now common on the mid-range office printers, though not all the printers can accommodate a duplexing unit. As duplexing can also give a slower page-printing speed, because of the longer paper path.

In comparison with the laser printer, most of the inkjet printers and dot-matrix printers simple take an incoming stream of data and directly imprint into a slow lurching process that may have to include pauses as the printer waits for more data. 

The laser printer is unable to work this way due to such a large amount of data that needs to output to the printing device in a rapid, continuous process.

So the printer cannot stop the mechanism precisely enough to wait until more data that arrives without creating a visible gap or misalignment of the dots on the printed page. This is prior to the widespread deployment of high-speed Universal Serial Bus cables in the late 1990s, the only way to ensure that each page could be rendered smoothly in one continuous burst of data which was due to dedication to rasterizing hardware and a large onboard buffer of random access memory in each laser printer (at a time when memory was very expensive). 

The contemporary laser printers are now able to offload some of the rasterizing work to software device drivers, and memory prices have fallen dramatically over decades, thus enabling the laser printers in turn to become much more affordable.

History

In 1969 the laser printer was invented at Xerox by a researcher Gary Starkweather, who had an improved printer working in 1971 and incorporated into fully functional networked printer system by about a year later. When the prototype was built by modifying an existing xerographic copier. 

Starkweather disabled the imaging system and created a spinning drum with eight mirrored sides, with a laser that focuses on the drum. Light from the laser would then bounce off the spinning drum, sweeping across the page as it traveled through the copier. The hardware was completed in just a week or two, but the computer interface and software took almost 3 months to complete.

First commercial implementation of laser printer was the IBM 3800 in 1976, this was used for high-volume printing of documents such as invoices and mailing labels. It's often cited as "taking up a whole room", implying that it was a primitive version of the later familiar device used with a personal computer. 

While still large, it was designed for an entirely different purpose:

- replacing the manufacturer's own fan-fold "train" or "chain" impact printers

This had reached their practical limit to 1,000 to 2,000 lines per minute. The 3800 could be sheet-fed or web-fed, and was attached to the mainframe computer through the familiar System/360 OEMI parallel channel interface. 

In 1981 the first laser printer designed for use in an office setting, this was released with the Xerox Star 8010. Although it was innovative, the star was an expensive system that was purchased by only a few businesses and institutions. After personal computers became even more widespread, the first laser printer intended for a mass market was the HP LaserJet 8ppm, this was released in 1984, using a Canon engine controlled by HP software. The HP LaserJet printer was quickly followed by laser printers;

-Brother Industries

-IBM

-Apple Computer

(with the LaserWriter) and others.

First-generation machines had large photosensitive drums, of circumference greater than the papers length. Once faster-recovery coatings were developed, the drums could touch the paper multiple times in a pass, and could therefore be smaller in diameter.

Laser printers brought fast, high quality text printing with multiple fonts on a page to the business and consumer markets. No other commonly known available printer could offer this combination of features.

As with most electronic devices, the cost of laser printers has fallen markedly over the years. The Hp LaserJet sold in 1984, it had trouble with even small, love resolution graphics, and weighed 32kg (71 lb). As of 2008, low end monochrome laser printers often sell for less than 75 dollars. 

These printers tend to lack onboard processing and reply on the host computer to generate a raster image, but still will outperform the LaserJet Classic in nearly all situations.

Advantages and Disadvantages of Laser Printers

advantages

• Main benefit these printers is probably its efficiency and speed at printing. Laser printers are also known as "page printers" as they print documents a page at a time, and performs it at a very fast rate.

• They furnish the highest potential production in comparison with the other types of printers. This is generally due to the technology behind it as laser printer utilize electro-photography for printing which results in potential output.

• It's a small issue, noise can be very unproductive and disturbing especially at a work-place, laser printers are highly optimized and barely emits any sound.

• Also they offer user-friendliness with other features like self-printing, where printing may be done without supervision, thus the addition productivity at the work-place.

disadvantages

(laser printer wireless)

• The extra benefits in comparison with other printers, they're a lot more costly.

• Laser printers are considerable and utilize complicated technology and perform fast output, the result of which is a relatively large hardware gadget which can take up a lot of space.

• They're non-impact printer, multi part stationery cannot be used, so double printing cannot be simultaneously performed.

• While the cost is an issue, an initial venture only maybe worth it based on your organization's or personal requirements, any way maintenance, servicing and med of this hardware gadget is also very high. So the laser printers aren't very economical.

• Also known to be dangerous to the atmosphere and your health. Due to the high voltages when running the machine, small amounts of ozone are generated which can damage the ozone layer. Even some are known to emit particles that are suspected to cause respiratory diseases. 

Here is the pros and cons, finally summary,  so if you're planning on going for a laser printer, be sure to study the points above, the most important facts to reconsider would be the price, potential and speed of production you require.