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Earlier Dr. John Reczek proudly showed off the pigment ink technology used in the new system. We've reported on this extensively, beginning with the product introduction announcements (http://www.imaging-resource.com/PRINT/KAO/KAO.htm), because it's really the key to the system. Without these inks, there wouldn't be a Kodak inkjet. So we'll summarize here.
They are pigments not dyes, to begin with. But they are unlike other pigments because they are quite small. Kodak drew on pigment grinding patents going back to its X-ray film emulsion technology to develop its miniscule 20 nanometer ink pigments with polymer binders. The X-ray project was an attempt to replace a dye interlayer designed to prevent color contamination that scattered too much light with a pigment layer that would scatter less light and therefore avoid losing sharpness.
The exceptionally small size of the pigments provides two key benefits, John told us. First, because they scatter less light, they provide a larger gamut than normal size pigments. Second, they increase printhead reliability, clogging the nozzles less frequently.
The color gamut issue is a confusing one. Kodak actually claims their pigment set has a larger gamut than dye-based ink sets, not just other pigments. But in our tests back at the bunker, Canon's dyes exceeded the Kodak pigment gamut, as we reported in our 5300 review (http://www.imaging-resource.com/PRINT/K5300/K5300.HTM). We asked John about that.
The Canon print, he pointed out, has the advantage of having been made with a high fidelity ink set. While the Kodak print relied on a set of just three color inks plus black, the Canon had the advantage of a set of eight inks. As a former pressman, I can vouch for that explanation. And in fact, when you compare the output of an HP three-ink print like those from the A626 we reviewed (http://www.imaging-resource.com/PRINT/HPA626/HPA626.HTM) to the Kodak prints, the Kodak has deeper shadows and more contrast. No doubt using a black ink helps Kodak here, too.
The smaller particles also improve gloss performance, John said. In fact, the clear ink in the color cartridge is not a gloss optimizer (as you might find in an Epson inkset). Instead, it's a polymer coating that is designed to seal the ink in the porous papers Kodak uses. Kodak's papers are not the swellable sheets typically used with dye-based inks to encapsulate the dye in a gelatin layer. They are porous sheets that suck in the liquid vehicle that delivers the pigments to the surface of the sheet. The clear coat seals those pigments on the paper and provides instant-dry handling. That slight tackiness you feel when you touch a print fresh from the printer is that coating. It extends over the full width of the image, we noted, regardless of the printed image size.
One of the more interesting stories in the development of Kodak's pigments involves what they early observed as a haze that would form over the image in some places. The effect was the result of subsequent drops of ink physically distorting the drops of ink that had been previously laid down on the sheet. Light was being scattered by the distortion, forming the haze.
Because Kodak developed every ingredient in the ink, it could optimize the formula to defeat this effect rather than merely find some compromise. There were many variables to working this out, John told us, including hue.
That prompted us to ask if the technology was restricted to a three-hue set of inks. Not at all, John answered enthusiastically, without giving any further details.
Anyone who has used an Epson pigment printer knows about clogged printheads. It's revealing that in our inconstant usage over several weeks, neither Kodak clogged.
Cathie Burke referred somewhat shyly to the Kodak printhead as "permanent." Nothing, of course, is permanent. But what Kodak has achieved in the printhead will pass for permanent.
Cathie explained that the Kodak drop ejector is designed so the heater will never be "attacked mechanically." To eject a drop, a heater in the firing chamber is pulsed on, forming a vapor bubble in the ink. As the bubble expands, surface tension pulls the ink into a droplet. After the heater is pulsed off, in many designs, the vapor bubble collapses onto the heater with significant force, and over time will damage the heater. In the Kodak design, the vapor bubble vents to the atmosphere, and the chamber refills with ink. Fire it as many times as you like, the heating element remains untouched.
That wasn't easy to achieve, she pointed out, even though Kodak had printhead technology from earlier projects. She credited the companies superb fluidic, electrical, and Micro Electro Mechanical Systems or MEMS simulation capabilities, which provide the ability to mimic the real world consequences of a design before it escapes the computer. That saves a lot of time, she said.
Early in development, she confided, they witnessed what seemed to be random early failures of some heating elements. Diagnosing the cause of the problem wasn't simple. But Kodak isn't your average home improvement show. It's more like a collaboration of crack CSI investigators with red ink on their gloves. They investigated the problem using microscopic images of cross sections of the printhead. And that revealed the cause of the problem. An otherwise undetectable variation on the surface over which the ink had to travel was the culprit.
Firing the printhead requires electricity and we were amused to learn how Kodak determined the power consumption had to be 35 volts. In some countries, Cathie said, special permits are required to operate equipment at voltages above 40. Keeping it at 35 volts meant it qualified as an appliance worldwide.
The printhead's quick-firing nozzles operate at 24 kHz, whereas the competition runs between six and 12 kHz. That delivers faster prints and consistent laydown.
But it also illustrates how Kodak's control of the entire design -- ejectors, ink, media -- lets them optimize instead of compromise. And from our chat with John and Cathie it was clear that's something they really love to do.
The jury is still out on the 5000 Series. But not on Kodak's inkjet technology. They're winners. And we look forward to perhaps simpler printers that make them available to do what they do best: produce excellent quality prints that last forever for much less money than competing products.
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