Wide Format Imaging

The Durst Rho 600-series is the first wide-format rigid UV printer with Quadro array printhead technology. Array drop ink delivery for wide-format is an industry first, and 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 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, their 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 VP marketing and CEO of new business development says: "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 the models. The Rho 600, like the Rho 160 and 205, use the same UV-curing inks and allow the user to print on a wide-range of materials, uncoated and absorbent stock, and 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 Celsius (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 different 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 and are a 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.