Is it a Durst Rho 160 or a Rho 205? No, it's a Durst Rho 600 with Quadro technology recently introduced at Europe's premier screen print show, FESPA, in Munich, Germany, May 31 – June 4. The Rho 600-series is the first large-format rigid UV printer with Quadro array printhead technology. Array drop ink delivery for large format is an industry first, and it results in quality that is the closest to traditional or digital photographic prints.
One of the problems common to rigid piezo UV printers is banding due to failure of drop placement. Durst has solved this problem with its exclusive Quadro array system. The arrays produce a better drop breakup to reduce banding and result in near photographic quality. The Rho 600 series produce a variable drop that masses between 40 and 55 picolitres for resolutions up to 600 dpi. The user can select the quality print level, and the printer will adjust the drop size automatically.
According to Durst, its UV ink delivery system "results in a consistent ink droplet that creates extremely smooth, rich, and clean solids, and a very fine text; the Rho 600 can easily print six point reversed text."
In commenting on the Rho 600 design, Chris Howard, Durst's VP of sales & marketing, large-format printing states, "The key from a design standpoint is how we feed the nozzles with ink. Any ink array needs a good system to keep the nozzles from starving for ink and causing nozzle dropouts. Durst's feed system is a straight line and we use an osmotic filter to keep air from getting to the ink feed for the nozzles." Durst's Quadro arrays are the first print arrays made by Durst and utilize nozzle plates from Spectra. Durst also has designed the firing pulse for the arrays.
The color function is the same on all three Rho 600 models; the difference is in the number of Quadro arrays that allow for greater speeds as you move up in the line. The Rho 600, like the Rho 160 and 205, uses the same UV-curing inks and allow the user to print on a wide range of materials such as uncoated and absorbent stock, cardboard, canvas, plastic, wood, aluminum etc. The 600 printers have 12 UV lamp intensity levels in order to adapt the curing properties to different substrates that operate at 40 degrees centigrade (one-half the temperature of other UV curing lamps). The significance of the lower curing temperature is the ability to run a broader variety of substrates through the printer as the heat on the material is lower and the materials do not warp or bend. One example is .015 Styrene.
Arrays, Piezo, Quadro
Do not confuse the Durst Quadro arrays with traditional piezoelectric print heads common to current UV and solvent flatbed printers. UV piezo printers often have failure of drop placement that causes banding. Variable-dot technology is not new, although it is a recent innovation. Durst Quadro arrays can print from 400-600 dpi, utilizing variable ink drop sizes. These dpi settings are user selectable.
The Durst array print technology looks at one pixel at a time and is quite differ ent from other scanning array systems. A linear array combines all pixels into one line to write one line at a time that can result in undesirable dropouts. Linear arrays are stationary when used in copiers. They are used in narrow format printers such as Eastman Kodak's NexPress, but these are toner-based printers. The Agfa Dotrix is the only narrow format single-pass linear printer that uses UV curing inks.
Scanners use an acquiring array. Most digital cameras use area-array sensors with photosites (pixels) arranged in a grid. This allows the sensor to capture the entire image. When printing large format, however, an acquiring array cannot cover 50 or 80 inches across. A scanning area array used by Durst is a different story, because of the larger print area.
Speed Is On Demand
You can refer to the chart below for the speeds associated with the three Rho 600 models. The 600 series is a modular platform that allows the user to combine print quality and output speed. If a user selects the basic model for starters it is upgradeable to the next two faster print models.
There are several differences in the comparison of the Rho 160 and Rho 205 to the Rho 600, the primary difference being speed. The chart below shows that the Rho 600 Rapid can achieve printing speeds up to 1600 ft² per hour, comparable to the Inca Columbia. The Rho family commonality is color and the ability to control curing for a matte or semi-gloss print finish. All Rhos have the option of white ink and clear varnish for spot or full coverage.
The Rho 600 offers some new networking capabilities. The computer runs on the Linux platform, but the Cheetah RIP (common to all Durst printers) is built in so user options remain the same. It is possible to network multiple Durst devices or to RIP with any program and send files over the network to the printer.
At first glance, the Rho 600 looks like a Rho 205; however, the 600 top carriage assembly is wider to accommodate the arrays and extra nozzles. The bed is the same size.
The Rho 600 was beta tested in Europe , but North American image shops will soon have them in production. Several will go to shops in Canada , but the first installations in the U.S. will be at KSK Color Lab, in Solon, Ohio and at Graphic Systems, in Minneapolis .
Hermann Kauls, president of Graphic Systems says, "We looked at samples and liked what we saw… the head configuration and the finer dot pattern." His team chose the Rho 600 Rapid model for speed. They also opted for white ink and varnish. "We are selling off one of our three Rho 160 combination roll and rigid printers to make room for the new 600." Kauls added that Graphic Systems had the number two Rho 160 in the country (Meisel being first). "Durst has good products and good service, and they have helped us grow our business."