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Building your PC:
Printer
Technically, a printer is defined as: a device that produces hard copy (ie physical printed pages) based upon a template stored in electronic form. A printer can either be physically attached to a single computer as a peripheral or it can be attached to a network via an interface (generally ethernet) which allows any computer on the same network to communicate with it and to submit print jobs to it.
The need for a computer to communicate with its operator has been recognized since the earliest advent of computing and the nineteenth century inventer Charles Babbage actually designed a mechanically-driven printer to accompany his difference engine.
In recent years small, relatively cheap, home printers have become available and jobs such as runs of local magazines and pamphlets which used to have to go to large print shops can now be done fairly economically at home, which has led to the advent of what is termed desktop publishing. The advent of digital cameras and the ready availablilty of high quality (so-called 'photo quality') inkjet printers along with more acessible photo-manipulation software has also led to the advent of home photographic printing.
Page Map |
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|---|---|
| Modern Printers | The Laser Printer |
| Inkjet Printers | Conclusion |
| Inkjet Printing Technologies |
History:
The first proper high-speed printer was developed by the Remington–Rand corporation in 1953 for use with he UNIVAC mainframe computer.
This was soon followed by the IBM 1403 printer, introduced in October 1953 which remained in the marketplace until 1971. The print mechanism is a spinning chain, with hammers that strike the chain through the paper exactly when the right character is underneath. Custom chains and printer control tapes could be mounted. The 1403 could print up to 1400 132-column lines per minute on 11-by-14 inch fanfold pinfeed paper. That's 23 pages a minute, under 3 seconds per page, and faster than that when a page contained any blank lines, for which the paper speed increased to 1.9 m/s. So good (and so fast) was the 1403 during its heyday that it was not uncommon for whole books to be typeset using it.
The IBM 1403 remained the 'gold standard' for printers until the early 1970s and it was not until 1969 that a technology which could rival it came along. In 1969 Gary Starkweather at Xerox demonstrated that, using a laser beam, Xerox's dry printing process of electrophotography (invented in 1938) could be extended and this breakthrough led to the invention of the laser printer. The original later printer (called EARS) was compelted in November 1971 but it was not released until 1977 under the rather cumbersome name of the The Xerox 9700 Electronic Printing System. This actually allowed IBM to pip Xerox to the post as they delivered the very first IBM 3800 Printing System in 1976. Though the printer did not become generally available until 1979.
After personal computers became more widespread, the first laser printer intended for a mass market was the HP Laserjet 8ppm, released in 1984, which used a Canon Inc. developed engine controlled by HP developed software. However, it could be argued that it wasn't until the introduction of the Apple LaserWriter for the Apple Macintosh, along with Aldus PageMaker software, in 1985 that desktop publishing became popular. The introduction of Hewlett-Packard's LaserJet IIP laser printer in 1990 saw the US$1000 street price being broken for the first time and prices have been falling ever since. Indeed, it is now possible to attain a barebones laser printer for around US$100. The next breakthrough came in 1993 when QMS introduced the first colour laser printer, the ColorScript Laser 1000 for a whopping US$12,499. By 1995 Apple Computer introduced its own colour laser printer, the Color Laser Printer 12/600PS at 600x600 dpi for US$7,000. Such colour laser printers have now almost ubiquitous in large network environments.
In 1970 Centronics produced the first dot matrix printer, which was actually a reselling of a printer mechanism produced by Brother Industries, Ltd. of Japan. However, they did design a parallel electrical interface for this printer that was was to become standard on most dot matrix printers (indeed, most printers in general) until it started to be replaced by the Universal Serial Bus (USB) in the late 1990s. Whilst Centronics were concentrating on the low-end home marketplace the Digital Equipment Corporation (DEC) were generating a series of high-end dot matrix printers beginning with their LA180 (at 180 c/s line) and culminating with their LA12 (in effect a portable terminal). The industrial printers were designed swpecifically for high-volume print jobs whilst the home versions were designed for low-volume, low-cost usages. Indeed, inthe late 1970s and early 1980s the dot matrix printer was considered to offer the best combination of expense and versatility.
It is probly fair to say that Epson's MX-80 dot matrix printer (picutured, left) is the model that sparked the initial popularity of impact printers in the personal computer market. This printer combined affordability with solid text-output (for its time at least) though its output was only 60dpi by 72 dpi in quality. Progressive hardware improvements to impact printers boosted the carriage speed, added more (typeface) font options, increased the dot density (from 60dpi up to 240dpi), and added pseudo-color printing. Faster carriage speeds meant faster (and sometimes louder) printing. Additional typefaces allowed the user to vary the text appearance of printouts. Proportional-spaced fonts allowed the printer to imitate the non-uniform character widths of a typesetter. Increased dot-density allowed for more detailed, darker printouts. The impact pins of the printhead were constrained to a minimum-size (for structural durability), and dot densities above 100dpi merely caused adjacent dots to overlap. While the pin-diameter placed a lower-limit on the smallest reproducible graphic-detail, manufacturers were able to use higher dot-density to great effect in improving text-quality.
Comparison of the output of the dot matrix printer with the laser printer clearly showed the former's limitations and attempts were made to provide a low-cost alternative with much improved print quality.
In parallel with the development of laser printers Hewlett-Packard began, during 1978, to initiate research into inkjet technology. (This was despite the abysmal failure of the original inkjet printer, the Teletype Inktronic, which introduced the concept of video-type distortions to printing. This was released in 1971 but had such poor print quality that it soon vanished without trace.) Although large, industrial inkjet-marking devices already existed, they weren't suitable for document printing needs. By miniaturizing the technology and offering it in the form of a personal printer, HP is able to offer better print quality than serial dot-matrix printing, quieter operation, extremely low power consumption and, eventually, high-quality, low-cost color. This research culminated in the release during 1984 of HP's ThinkJet, a high-quality, low-price personal printer with 96-dpi printing quality. With its far superior printing quality and inexpensive price, the ThinkJet spells the end to noisy dot-matrix printers.
As well as HP's thermal inkjet technology IBM were developing continuous inkjet printers that use electrically-charged droplets to coat the page with ink very quickly but also waste a lot of ink. This technology never caught on with consumers, but is used today in industrial settings, for labeling cartons and addressing direct mail. The more popular design among consumers is the drop-on-demand inkjet printer, invented by Siemens in 1977. These printers, which spray ink only where needed, are slower than continuous inkjet printers but less expensive. Epson uses its own technology, called piezo-electric, to achieve the same effect. The inkjet printer has come a long way since it became available almost twenty years ago: Hewlett Packard's DeskJet printer, which was among the first available to the public (indeed, HP's next generation of printer the DeskJet was priced at US$1000 when released in 1988).
Modern Printers
The potted history given above should essentially tell you that if you're chosing a modern printer then your choice lies between an inkjet printer (of which there are many types) or a laser printer. As the price and features of these two types of printer are becoming ever closer it's probably more important than ever to make a proper informed choice about what printer you're going to buy.
The Inkjet Printer
A typical inkjet printer (such as the one on the left) is generally cheap to buy (indeed, you can get a decent inkjet printer for less that US$70). However, it should be noted that a common business model for inkjet printer manufacturers involves them selling the physical printer at or even below production cost, while dramatically marking up the price of the (proprietary) ink cartridges. As a result they make their money on the cost of the ink cartridges rather than based on the cost of the printer itself. This has led to a booming market in cheaper copies of cartridges, produced by other companies, and in the production of ink for physically refilling the cartridges. Indeed, as a result of the large OEM (original equipment manufacturer) markup on such products there are many companies specializing in the manufacture of alternative off-brand ink cartridges.
Many inkjet manufacturers are now attempting to enforct the tying of their own ink cartridges to their printers by the use of microchips on the surface of the cartridge to prevent the use of third-party or refilled ink cartridges. This practice has recently come under legal scrutiny and the European Commisison ruled this practice anticompetitive and will not be seen on newer printer models sold in the EU. The case of Lexmark v. Static Control tried in the United States Supreme Court also ruled that circumvention of this technique does not violate the Digital Millennium Copyright Act. As a result consumers will still be able to source cheaper copies of inkjet ink. Even if you are buying off-brand inkjet cartridges the cost of these consumables still need to be factored into the cost of inkjet printing. Especially as cartridges can cost up to US$30–$40 apiece.
On the positive side, inkjet printers can produce very fine details and a large number of photo-quality inkjet printers are now on the market. They are also quite quiet and therefore well suited for the home market. They also have a relatively low power consumption and a low cost per page as compared with most printing technologies (except for laser printers). Inkjet printers also have very short warm-up times and thus are ideally suited to the home setting where they are generally only called upon to print a few tens of pages at a time. It should also be noted that the ink used in most inkjet printers is water soluble. As a result the exposure of a printed page to even a small drop of water can cause blurring or running of the ink. If stored in a damp pages then capillary action in the paper may cause the ink to smear giving you a strawberry-coloured mess. There are papers treated with special clays that are designed to reduce such bleeding but these are expensive. Though new 'colorfast' technologies producing quicker-drying inks with more water-resistant and lightfast properties are becoming available.
Inkjet Printing Technologies
In terms of design Inkjet printers come in two main types: fixed-head printers; printers such as Epson's range which have an inbuilt print head designed to last the entire lifetime of the printer. This reduces the cost of the printer and the ink cartridges but does leave the printer potentially prone to problems if the print head clogs with dried ink. The alternative is to have a disposable head in which case the print head itself becomes a part of the physical ink cartridge. Hewlett-Packard favours this printing method and it was also present in early Canon models. Canon have now moved to an intermediate positon where their printers have replaceable print heads that are designed to last the lifetime of the printer but which can be replaced if necessary.
It should be noted that most consumer inkjet printers work by having a print cartridge with a series of tiny electrically-heated chambers constructed by photolithography. To produce an image, the printer runs a pulse of current through the heating elements. A steam explosion in the chamber forms a bubble, which propels a droplet of ink onto the paper (hence Canon's tradename for its inkjets, Bubblejet). When the bubble condenses, surplus ink is sucked back up from the printing surface. The ink's surface tension pumps another charge of ink into the chamber through a narrow channel attached to an ink reservoir. This technology is called the 'Thermal Inkjet'. The other system in use is the 'Piezoelectric Inkjet' that's used by Epson in all it's inkjet printers. These incorporate a piezoelectric crystal in the print nozzle instead of a heating element. When a current is applied across the crystal this flexes and forces a droplet of ink from the nozzle. Piezoelectric ink jet allows a wider variety of inks than thermal or continuous ink jet but is more expensive.
In essence, if you are only going to be printing low volumes then it will be cheaper to buy and run an inkjet printer. Otherwise, if you are going to be printing large numbers of pages you might be better-off considering a laser printer (see below). One final note about inkject printers. Almost all now come with USB connections (though some are still supplied with a centroinics parallel port to support older PCs. The latest printers also support the faster USB 2.0 standard.
Laser Printer:
The image on the left shows a fairly standard laser printer intended for home/personal use. Laser printers reproduce high quality text and graphics on plain paper and employ a xerographic printing process by the direct scanning of a laser beam across the printer's internal drum. They have seval advantages over inkjet printers in that they typically have a higher resolution, no smearing, lower cost per page, and faster print speed as the entire page is imaged in a single pass rather than being printed in a series of narrow strips, as is the case for inkjet printers. However, laser printers always produce raster images, and except in the highest-quality versions are less able to reproduce continuous tone images such as photographs. Laser printers also tend to take a long time to warm up and are really designed for long periods of continuous printing.
It should also be noted that the cost of owning a laser printer depends of a combination of the costs of paper, toner replacement, and drum replacement, as well as the replacement of other consumables such as the fuser assembly and transfer assembly. Often lower-end printers with soft plastic drums can have a very high cost of ownership that does not become apparent until the drum requires replacement.
In general, there are six steps involved in how a laser printer works. First of all the print drum needs to be charged. In older printers this is done by means of a charged corona wire, though modern printers tend to use a charge roller to project an electrostatic charge onto a revolving drum that's surfaced either with a special plastic or with garnet. Once the drum is charged a laser is then used to write the page to be printed onto the drum. Laser printers all have a special chip witin them, called a Raster Image Pocessor (RIP) that converts incoming images or pages into a raster image suitable for scanning onto the charged drum. Under the control of the RIP chip a laser (usually a diode laser) is aimed at a moving mirror that directs the laser's beam through a system of lenses and mirrors onto the photosensitive drums. When the laser light strikes the charged drum the charge on that region of the drum is reversed which effectively creates a charge image of the page to be printed on the drum. Now the surface of the drum can be passed through the toner (very fine particles of plastic mixed either with ink of lampblack (amoorphous carbon). These are attracted to the regions of the drum whose charge has been reversed by the laser so that in effect the mirror image of the page to be printed is created on the charged drum. Now the drum can be pressed onto a page of paper so that the image is written upon it. As the plastic particles are only gently impressed onto the surface of the paper, this is then passed throug ha fuser asssembly that uses rollers to both heat the plastic (up to 200°C) and to press it into the paper, thus fusing the plastic in place. This is why laser printed pages are more permanent than inkjet printed papers. This is also why pages emerging from a laser printer are warm to the touch when they emerge. Once a page has been printed an electrically neutral rubber blade cleans off any excess toner on the drum and deposits it into a reservoir, and a discharge lamp removes the remaining charge from the drum. The printer is now ready for the cycle to begin all over again. Though various laser printers achieve these steps by slightly different means they still essentially undergo the six steps defined here. Indeed, it is the heating of the fuser element that takes all the time as a laser printer quite literally 'warms up'. It is also this process that consumes most of the energy that a laser printer uses. Colour laser printers add three colour sets to the charged drum (typically cyan, magenta and yellow) and it is the mixture of these primary colours along with black that generates colour output.
These days it is fairly east yo buy a monochrome laser printer for home use in the sub US$100.00 bracket, though for economic purposes it may be better to buy a slightly more expensive printer that delivers more pages per toner cartridges, has a longer mean time between failures and a longer time between the need to change the charge roller. It's even possible to buy a colour laser printer for under US$350.00.
Most laser printers designed for home use ae dupplied with a centronics printer port and an USB port and may be available with an optional ethernet port so that they can be easily networked. Higher-end laser printer will be supplied with an ethernet port as standard and may come with and USB 2.0 or a Firewire port.
Whether you chose a laser printer over an inkjet printer will really depend on what purpose the printer will be put to and how many pages you expect to print. The more you need to print then the more economical a laser printer will become.
Conclusion
On this page, you've seen a potted history of printing technologies and you've had a brief comparison of modern printers, including the pros and cons of inkjet and laser printers. Traditionally laser printers have been used in small and large companies and they are designed from the ground up to be networked. In contrast inkjet printers have almost exclusively been designed to attach to a single computer in a home context. However, as more and more networks become wireless wireless networking capabiliteis are being build into laser printers and wireless network adaptors are (usually USB dongles) becoming available for USB printers. Thus much of the networking functionality of the machines is merging.
Before buying a printer you should work out how many pages you are going to print each month then you can make an educated analysis of how much each printer type will cost you per page.
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