peed, appropriate color quality, and a low cost per page. However, most people don't even think of augmenting business output with spot color, because it has never been an option.
Well, it is an option now. If you want to add color to a newsletter or a color bar chart to a widely distributed report, no other printer can do the job as well. Ink-jets don't have the speed (minutes per page, not pages per minute), duty cycle, or text quality. Dye-sublimation printers have gorgeous but expensive photo-image quality and require special stock. Thermal-wax-transfer printers have high page costs and need special paper, too.
A relatively new color-printer option that does compete with color laser printers is Tek
tronix's Phaser 350 solid-ink printer, which we include in this Lab Report along with six color lasers. The Phaser 350 has the advantages of laser-like color printing speed with a lower price. On the downside, it prints text output at the same speed as color, a maximum of 3 to 6 pages per minute (ppm) depending on the quality level. Also, it's a 300- by 600-dpi printer. It doesn't print text as sharply as some color lasers. The Phaser 350 makes a good adjunct to a network that is already equipped with monochrome lasers.
Six Lasers Plus One
The six
color lasers
we tested are from Apple, Hewlett-Packard, IBM, Lexmark, QMS, and Tektronix. All are capable network printers with prices as tested ranging from $5995 to $9778. The solid-ink Tektronix Phaser 350 costs $5495 with the 24 MB of RAM required to print at 300- by 600-dpi resolution. We didn't test color lasers from Canon, Digital Equipment, Panasonic, and Xerox, either because a review unit wasn't available in t
ime or because an upgraded model was close to introduction.
The laser printers have print engines with rated print speeds between 10 to 14 ppm for text and 2 to 6 ppm for color. The faster color page speeds represent lower-quality modes. We tested most of the printers with more than a standard memory configuration, so that all could print full-color pages in highest-quality mode. The QMS Magicolor CX-32 and HP Color LaserJet 5M come standard with enough memory. The test laser printers from Apple, IBM, and Lexmark use the same 600-dpi Canon P320 engine, and the Magicolor CX-32 uses a 600-dpi engine from Hitachi. HP's Color LaserJet 5M uses a 300-dpi Konica engine, while the Tektronix Phaser 550 uses a 1200-dpi KME (a division of Matsushita) engine.
While the print engine determines many basic features of a laser printer, including engine speed, base resolution, paper capacities, and consumables setup, the printer controller largely determines print quality, image-processing speed, and networking ca
pabilities. Most of these lasers play games with laser-beam modulation, adjusting the size and placement of toner dots in the print engine's native raster array to achieve higher apparent resolution, smoother edges to curves, and/or more than the 16 colors that basic bilevel printing allows (see the Tech Focus on page 132).
HP, for example, used a 300-dpi Konica engine in its underwhelming first Color LaserJet. The Color LaserJet 5M uses the same engine, but HP has gotten remarkable quality improvements from it by using a more sophisticated controller. By modulating the timing and pulse duration of the image-writing laser beam, HP manages to approximate the text resolution of 600-dpi engines (HP claims 1200 dpi) when printing at 300 lines per inch.
In color-image quality, the number of colors matters as much as resolution. Laser vendors take two approaches to increase the apparent number of colors from 16, both at the expense of resolution. One is dithering, which isn't totally satisfying at 300 d
pi or even 600 dpi because patterns of dots show in light areas. The other approach is to vary toner dot size by adjusting laser pulse width, a technically tricky feat that can lead to inconsistent color over time. A smaller dot appears as a lighter color. This is called contone or multilevel printing (as opposed to bilevel). Contone isn't the same as continuous tone.
You can get a greater range of colors by dropping resolution so that you can have not only smaller dots but larger ones, too. Considering its 300-dpi engine, the Color LaserJet 5M achieves remarkable color results by printing at 150 lines per inch, but with a wide variation in toner dot size that lets it approximate continuous-tone color. With its 1200-dpi resolution, the Tektronix Phaser 550 can use dithering for photo images that fool the naked eye. The other lasers in this report have 600-dpi engines, and all can do contone color, although the QMS laser combines dithering with its contone.
Muss and Fuss
With fo
ur toner colors, developer powders, fuser oil, dust collection bins, various drums, and fuser units, the number of components you must install and then replace over time can be more than 10. This makes network printer management interesting. The Tektronix Phaser 550 and the HP Color LaserJet 5M both have around a dozen parts you must install or keep track of, which didn't help their usability ratings. Canon-based lasers use a monocomponent toner that includes the developer powder, thereby cutting consumable components in half and simplifying maintenance.
Because color laser printers consume only as much pigment as they need for an image, and because they print on plain paper, they have a relatively low per-page printing cost for a color printer. This is also true for solid-ink printers. Cost per page is higher, however, than penny-per-page monochrome lasers. Because vendor differences in calculating cost-per-page estimates make comparisons a tricky business, we did not include this important factor in o
ur ratings analysis. It's interesting that HP, which claims per-page costs that are lower than some monochrome lasers, obtains some of its economy by virtue of its nonintegrated consumables design.
Contributors
Mary Anne Eves
, Acquisition Specialist/NSTL
Dorothy Hudson
, Project Manager/NSTL
Steve Platt
, Director of Electronic Publications/NSTL
Dave Rowell
, Senior Technical Editor/BYTE
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Seven Fast Color Printers
