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Sci Tech
IT TRENDS
Printing technology: consumables are the key
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The dependence on inks and toners is subtly changing the entire dynamics of the business for the buyer
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Quality, speed rely on cartridge characteristics The challenge is to get uniform, smaller toner particles
— Photo: Special Arrangement
Quality control: Inspecting print heads at HP’s inkjet cartridge factory in Singapore
Once upon a time, you bought a printer, mainly to go with your PC. If this happened any time in the1980s, chances were, your first choice was a dot matrix impact printer. You replaced or re-inked the ribbon every once in a while — but otherwise you had no major recurring expenses till the printer died on you. And — which meant the print head was worn out or the carriage motor burned up … and such disasters were a rarity.
Today, it has become the technology equivalent of the tail wagging the dog: The heart of an inkjet printer lies in the only part that your keep changing: the ink cartridge. In almost all consumer printers, the cartridge includes the crucial print head, the smart part of the printer that senses the electronic signals that flow from the PC, and squirts up to 30 million drops a second on the paper to form text or pictures.
Main factor
The quality, even the speed, of the printer is therefore largely a factor of the cartridge characteristics. And since they typically come with just around 15 to 30 millilitres of ink, you keep throwing them away every few weeks.
Things are hardly different in the laser printer business. Here too, manufacturers have slowly and deliberately, concentrated all their creative eggs in one basket: the toner cartridge.
Its name belies its role: the cartridge is not just a receptacle to provide the black electrostatically charged powder that adheres to the paper and produces the impression. These days the toner cartridge includes the key element: the photo conductive drum on which the image is transferred by laser action, before it is transferred to the paper.
There is an upside and a downside to this technology evolution: the immediate downside for consumers is that they have to pay again and again for something that in an earlier era seemed like a semi-permanent part of the machine.
The upside, is that this enables printer manufacturers to achieve continuous improvement in the quality that their printers deliver, without requiring the user to upgrade the basic machine. Marshall MacLuhan’s adage still holds: ‘If it works, it’s obsolete’.
So chances are, the printer you bought became capable of better work even before you brought it home. Yesterday, you might have just cursed silently and reconciled to waiting till you could afford to replace the printer. Today, you just buy a new cartridge. A typical monochrome inkjet cartridge has some 300 tiny nozzles, the number could rise to some1200 in a three-colour cartridge. How fine or sharp the image produced looks, depends on the size of the nozzles. Entry level printers have standard sized nozzles that deliver drops sized at just under 5 picolitres. If you want ‘photo quality’ — that is the higher resolution of the dots on the printed page that is required for printing photos — you normally went in for a printer which took a photo cartridge — one whose finer nozzles released just 1.3 picolitres at a time.
Powerful scrutiny
HP engineers have succeeded in combining both sizes of nozzles on the same cartridge. They call it Dual Drop technology. Under a powerful microscope in the inspection department of HP’s Inkjet factory in Singapore I peered at one the dual drop type cartridges. The dual line of the larger nozzles was interspersed with smaller diameter nozzles.
I also examined micrographs of the same photo printed using the normal cartridge and the dual drop cartridge — and the higher resolution of the latter was palpable.
Almost all new generation inkjet cartridges including the popular type 60 series are made to the dual drop design, and the technology allows owners of some of the most affordable entry level printers like the $50 DeskJet 2560, to enjoy the benefits of photo quality printing. The finer nozzles kick in automatically when the printer is set to ‘normal’ or ’best’ quality.
But if all you need is draft quality for text, the job is done using the larger nozzles. The new cartridges also incorporate higher frequencies in the firing circuits, which squirts out the ink at 24 KHz (that is, 24,000 drops per second) versus the earlier 18 KHz (18,000 drops per second).This enables popular consumer photo printers to turn out 6 inch by 4 inch prints in 70 seconds.
Ink chemistry improvements allow customers to use a variety of papers; but when the optimum photo paper is used, accelerated life tests have shown that prints can last 60 plus years without fading, if kept under glass and over 11 years if exposed to the ozone in the air.
Time was, when the toner used in laser printers was produced by pulverization. Today, toner is chemically grown, with a wax core — and resin to which the colour pigment to provide the cyan, magenta, yellow and black colours adheres.
Continuing challenge
The continuing challenge is to achieve uniform size of toner particles, and smaller size. The sharpness of the laser printer image is achieved by fine control of the toner… the rounder the particles, the sharper the image.
Amazingly the recently developed second generation ColorSphere toner from HP, flows — literally — like water; and since they are smaller in size, they pack in closer and as a result, new laser printers have a much smaller footprint.
The toner also melts at lower temperatures and requires 15 per cent less energy to achieve fusing temperature. The end result of these improvements on paper is a wider colour gamut and better gloss.
The paper — the other consumable that forms part of a printer ecosystem — has a small but significant role to play as well. If the paper retains ink on the surface, it makes for good looks — but may dry slowly, leading to inky fingers. If it absorbs some ink, it will dry fast but the image quality may suffer.
Achieving instant drying while retaining the ink on the surface is the challenge for paper technologists and HP claims to have achieved a breakthrough with its ‘ColorLok’ technology which has been transferred to International Paper, the world’s largest paper maker.
The product is said to provide three times faster drying and 40 percent darker blacks , used with both inkjet and laser printers. It may soon reach Indian shops under the brand of local paper vendors, even as Epson and Kodak have partnered to use the technology.
The world printed over 15 trillion pages last year according to Lyra Research; the number is expected to go up to 53 trillion pages by 2010, though the bulk of this will still be printed by analogue rather than digital means.
It is still an awful volume of paper. Technology successes in the consumables arena offer one small consolation: the quality is likely to keep pace with the quantity.
ANAND PARTHASARATHY
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