Durst, which introduced the Rho 2012 UV flatbed at Fespa 2013, showed off the higher productivity Variodrop version for the first time at the SGIA show. The initial unit had a 12 picolitre drop size and could produce up to 490m2/hr at 1000dpi. With the Variodrop greyscaling technology the drop size changes to 20 picolitres and the printer is said to be up to 25% more productive.
With the inclusion of Variodrop Durst said solid areas are smoother, and that the technology overcomes some of the errors which can occur with greyscale printing alone. In particular, greyscale relies very strongly on accuracy of drop placement and this can be affected by the uniformity of velocity of drops. Any variations of the printheads’ working conditions could lead to a mismatch of different greyscale level drop velocities and the consequence is drop placement inaccuracy.
Variodrop is an adjustable binary mode which uses multipulsing for drop size modulation. It combines two voltage pulses in such a way that the second pulse pumps precise dosage amounts of ink into the droplet before it detaches from the nozzle plate without forming any satellites. Compared to the often uneven droplets formed from a not well tuned greyscale waveform, the double pulse drop shape is perfectly uniform and its placement is always evenly spaced with Variodrop.
Like other Durst inkjet printers, the Rho 1012 is upgradable in the field.