Printers can be classified into three categories: text printers, graphics printers and plotters. Text printers print alphabetic characters, either one character at a time (character printers) or a full line at a time (line printers). Although some text printers do a marginally acceptable job of printing graphics, they're generally not well suited for that task. Graphics printers, on the other hand, generally do a good job on both text and graphics. They do this by converting each page into a complex image made up of, literally, millions of tiny dots, and then printing those dots.
The most widely used text printers are dot-matrix and line printers. Dot-matrix printers have a mechanical print head that moves across the page and strikes an inked ribbon forming characters with dot patterns. Though the resolution of these dot patterns can sometimes be as fine as a laser printer's, the dots themselves are usually much bigger and cruder. This results in an image that doesn't have a laser printer's sharpness . That's why although dot-matrix printers can print graphics the results aren't as good as they would be with a real graphics printer. Line printers print by striking an inked ribbon with a fully formed character of "type", much like a typewriter or an old-fashionded mechanical typesetter. As a result, they can't produce graphics at all.
The most popular graphics printers are the laser and ink-jet styles, although there are several other similar technogies that are useful for specific purposes. Plotters are also used for graphics, particularly large line drawings, such as mechanical and architectural "blueprints", which they produce by drawing lines rather than connected dots. Plotters can't draw shaded pictures, however, and only do a mediocre job on alphabetic characters. In addition, plotters are much slower than graphics printers.
The following paragraphs describe what s going on of interest with each of the most popular printer types.
Laser printers first became popular in the late 1980s for three basic reasons:
In addition, their prices have come down over the past several years to the point where they're now less than other printers of comparable speed.
Laser printer speeds vary from 4 to 20 pages per minute (ppm) and up, and they cost much less than mechanical printers of the same speed. In the past year or so, there ve been two major improvements to the most common laser printers: speeds have improved from 8 ppm to 12 ppm and the resolution has quadrupled, while prices have stayed the same or gone down. Of course, less expensive 4- to 8-ppm laser printers are still available.
The most common laser printers offer 600 dots-per-inch (dpi) printing both horizally and vertically (which, at 360,000 dots per square inch, is four times as sharp as the prior standard, 300 dpi or 90,000 dots per square inch). Some new printers now offer 1200-dpi resolution another fourfold increase an improvement that begins to approach phototypesetter quality (phototypesetters set type at 1800 to 2500 dpi and up), which is what you'd see in the highest quality commercial printing.
The trade-off, of course, is resolution versus cost. To see what 600-dpi resolution can mean if you re considering an upgrade compare this Bulletin (which, if you're reading the printed instead of the WWW version, is printed at 600 dpi) side by side with a page from a 300-dpi printer. Although the higher resolution is most apparent on glossy paper and photographic picutres, you'll see the difference in crispness even here. You can still buy 300-dpi printers and save about 25%, but if you do, I d recommend getting one that offers resolution enhancement . This technique improves print quality by using varying size dots to smooth out the jagged edges on curves and diagonals (unlike the one-size dots that most laser printers use). The new 1200-dpi laser printers carry about a 50% premium in price over the 600-dpi standard.
Improved speed and resolution are not the only things that can run up the cost of a laser printer. Other features, which are usually most important on printers shared by many users over a network, are:
Inkjet printers have become available more recently than laser printers and have gained great popularity because of their low prices (they range from about $250 to $600). Inkjets work more like laser printers and their output looks more like laser printer output than any other kind of printer. In fact, many people can barely (if at all) distinguish the printed page results produced by the two. However, there are several significant differences between lasers and inkjets, other than price, that potential buyers should know.
The most important difference is speed. The fastest inkjet printers are much slower than even the slowest laser printers. Top text printing speeds range from 1 to 3 ppm and this falls off rapidly when printing graphics (to as low as several minutes per page). Thus, they're fine for a single user with light usage who prints mostly short documents. They're not appropriate at all for shared usage on a network (except for color printing, as described below).
The second difference is the ink. Inkjet printers use liquid ink instead of the dry toner used by laser printers. With nearly all brands, the ink is water soluable, which means that unlike laser printer output it can run if it gets wet.
An offsetting benefit of the ink difference is that many inkjet models can hold and apply several different color ink cartridges, allowing for full color printing at a reasonable price (note, color laser printers exist too, but their prices are in the $5000 and up range). However, color printing reduces the inkjet printer's speed and increases the printing cost per page sharply. Nonetheless, firms that have an occasional need for short color print runs (such as for overhead transparencies), can probably make good use of one color inkjet somewhere on a network.
Another factor you should be aware of, is that every inkjet printer has a different ink formulation (i.e., there's no interchangeability of ink cartridges) and each manufacturer requires the use of its own special paper and transparency stock for the best quality color. Thus, if you need several inkjet printers, you should pick one model and stick with it. By the way, neither inkjets nor lasers produce the absolute best color output. Other technologies (e.g., dye sublimation, thermal wax transfer, etc.) are available at a much higher cost for professional use.
Both laser and inkjet printers cost considerably more to operate than printers that use ribbons, but lasers are the less expensive of the two. Paper and toner for laser printers generally costs on the order of a cent or so per page. Inkjet printer supplies cost considerably more, from a few cents up to a dollar or more per page. Inkjets are most economical printing black on plain paper, only slightly higher than laser printers. However, color is much more expensive, which can bring the cost-per-page into the 15 to 30 cents range on plain paper. But plain paper doesn't give the best color quality . . . for that you need special coated paper (every printer manufacturer's coating is different), which can cost another 20 cents or more per page.
Low cost, reliability and high output quality of laser and inkjet printers have turned dot-matrix and line printers into almost a dying breed. But they do have a few advantages:
Mail to: brooks@bizauto.com with
any questions or comments
Copyright © 1995 Business Automation Associates, Inc.