Laser quest

Introduction

For years we've been saying that colour printing in the office will become as commonplace as colour TV (not in the office, obviously) - that mono printers will come to be seen as something from the Stone Age, eventually becoming extinct. However, before this happens colour printers have to satisfy a number of requirements: they must be as fast, as simple to use, and as cheap as mono printers. This is now nearly the case, and - apart from some specific applications - mono printers are all but on the way out. This month we look at colour page printers that work in a network environment. There are a number of technologies represented: laser (the most common); LED; and solid-ink models. These technologies aren't new, but all have advanced since their first incarnations. A few years ago colour page printers were complex, requiring consumables such as fuser oil and multiple toner cartridges. Typically they weighed as much as a small car, and cost about the same. They were used in conjunction with a mono printer because the cost of using the colour printer was so high that people were scared off. In the early days of colour lasers, the target audience was specialist groups such as graphics and marketing departments, who were willing to put up with the slow technology because it meant they could output colour proofs and presentations in-house. For everyone else, though, the technology was too slow. The first speed breakthrough came a few years ago with the first single-pass models. The original colour-laser technology involved four-pass printing - one for each colour. This was the equivalent of having four mono laser printers stuffed in one box - and it was slow. The single-pass method lays down all four colours in turn, all in a single pass. This means print speeds improve dramatically. Making a pass
Now, all high-end printers are single pass, and prices have dropped dramatically. Corporate enterprises can now buy them en masse, which brings prices down even further. Since last year's Macworld round-up of colour page printers, prices have fallen by as much as 40 per cent - leaving mono printers looking a poor deal. Single-pass printers make four-pass designs look deadly slow, but instead of dumping a technology that took years to perfect, printer manufacturers slashed prices - so there are four-pass colour laser printers that sell for under a £1,000, and that work well. Although slower than single-pass models, they are still good value, because four-pass printers were selling for two or three times as much two years ago. Users for whom speed isn't a consideration should see them as a bargain. They promise to be the nail in the coffin for mono printing. Not all colour printers use laser technology. In the past each technology was noticeably different, and, although these differences are more now more subtle, they still exist. Wax waned, dye died
In the earliest days of colour page printing there were two main technologies: thermal wax-transfer and dye sublimation. Both of these were great for printing continuous-tone glossy photographic output, and some specialist photo printers still use these technologies. However, for everyday printing, both were extremely expensive - costing up to £5 per page. Solid ink has also been around for a long time, and is a Xerox-owned technology that was originally developed by Tektronix. This method is similar to ink-jet technology, but uses heated wax instead of traditional ink. This is a single- pass technology, and is faster than early colour-laser models. Solid ink's early days were marred by the thick layer of ink laid down in the printing process. The ink (actually a type of wax) could crack and even flake off when the page was folded. These difficulties were gradually overcome, and modern solid-ink printers output excellent colour without any flaking or cracking. One of the biggest advantages of solid ink is that it can produce glossy images on any paper stock because the ink itself is glossy. However the glossiness has been toned down to match the output of traditional laser prints. Solid ink is easy to replace: instead of using messy toners, it comes in blocks that are similar to crayons. These can be topped up at any time, so you need never run out of ink - and they are a whole lot cleaner to use. There are a couple of reasons why solid ink wasn't adopted as the standard colour-printing technology. First, it's difficult to explain the process, and corporate users accustomed to laser printing were loathe to embrace a new printing technology. Secondly, as a proprietary system, only Tektronix (now Xerox) ever used solid ink, making it the odd one out. Colour laser printers had the advantage of being an established technology, even though the carrousel design that moved each toner cartridge for every pass of the media was slow. Teething problems with alignment also meant solid-ink printers had an advantage over colour laser: keeping image registration lined up while passing it through the mechanism four times was a problem - but this was solved, and image quality caught up with solid-ink technology. It wasn't as glossy as solid ink, but this proved to be popular, because it's easier to read black text with a more matt finish. The slow four-pass process could never keep pace with solid ink. It wasn't until single-pass laser printers arrived that laser technology caught up - and eventually surpassed - solid ink for speed. Around this time the first LED-printer models were appearing. These were a quantum leap in speed, outpacing all-comers. LED is similar to laser printing, but more compact. Unfortunately, image quality let the technology down. Three years ago the choice was a trade off between fairly-slow-but-high-quality output from lasers and solid ink, or super-fast but-poor quality from LED. In the past three years all approaches have improved. The quality of LED printers is now impressive, and the speed of colour laser printers has leapt ahead, thanks to single-pass technology. The solid-ink printers from Xerox have fallen behind in the speed stakes: where they were once the premium option at a premium price, they are now the budget offering. Although solid-ink technology still has much to offer, the current models lag behind laser and LED models. Postscript
PCs are commonly used in giant corporations for doing menial work such as invoicing. Macs are used for more-creative work, and, if found in corporate environments, are usually restricted to the art department. Consequently, Macs in business have different requirements for printing than PCs. While PCs are most likely printing from Microsoft Word, Mac users will be printing from a graphics application. Mac people demand PostScript performance. In the past, printer manufacturers decided not to pay Adobe for the privilege of using Adobe PostScript, instead making their own versions, or buying a PostScript-compatible RIP. This tends not be an issue for PC users, as they mostly use a printer language called PCL5, or PCL6. However, these non-Adobe PostScript printers did a poor job of faking it. Early versions of these printers produced output that differed from on-screen images, and, while this seems to have been solved, the speed issues haven't. Printers with non-Adobe PostScript RIPs have over the years proved the slowest to render PostScript images. While the technology is better, it is still inferior to genuine Adobe PostScript. Most printer manufacturers have learned this lesson, but there are still some non-Adobe PostScript models around. This shows itself in the first-page-to-print test results, where the test page is a PDF.
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