Just like its erstwhile customers – the repro houses of the ’90s were decimated in the 2000s by digital cameras, digital proofing and CTP – Screen has had a choice: adapt or die. And just as its customers are moving en masse into digital print to survive, so Screen has adopted a portfolio of digital presses to suit various applications within the sector. Any aspiring digital developer would be blind not to notice the growing demand for wide-format inkjet, and Screen is certainly not blind.

 　　“We see demand from screen printers who are migrating work to digital, and from conventional litho printers who are wanting to expand their product offering, so there are plenty of people who will be excited by the Jet2500UV,” says Bui Burke, UK sales manager.

　　The Jet2500UV, a hybrid roll-to-roll/UV flatbed, is Screen’s first venture into wide-format, but Burke has no qualms about the different market. “We’re able to build on our existing customer base,” he says. “And Screen also has a strong reputation for colour and workflow that will recommend us even to those printers who haven’t dealt with us before.” That said, Screen has dipped its toe into the wide-format market before, via its parentage of Inca Digital, which it purchased in 2003.

　　Colour is certainly paramount in wide-format digital, and Screen has nailed its to the mast by adopting the latest variable drop-size printhead for the Jet2500UV. Which makes it one of only three wide-format machines currently on the market to use a variable drop-size, and puts it up against stiff competition from Fuji and Océ. Screen’s European product manager Rob Hageman is coy about naming the manufacturer of the printheads, but among other attributes, the droplet size range (6-42pl) would indicate a Xaar, or at least a Xaar-derivative, printhead. It’s too early to tell how long they are likely to last, but Screen’s estimates put the average printhead’s lifespan at around one to two years.

　　Hageman is likewise reluctant to give much detail about the Jet2500UV’s inks, saying only that they have been developed for Screen by a leading manufacturer and have a small particle size, excellent adhesion and – in combination with Screen’s FM screening – a wide colour gamut.

　　As for cost, Screen estimates that a 70% average coverage run would produce about 100m2 of print per litre set of CMYK ink.

　　The Jet2500UV’s base model is a CMYK machine, with the option of LC and LM as a field-upgradeable option to beef up the colourspace. There’s also the option for a white ink, which can either be laid down pre-print to ensure correct colour against a self-colour background, or post-print when printing on to the reverse of a sheet, typically for backlit operation. When in use, the pre-print white has an impact on the overall productivity of the machine, as Hageman explains. “To avoid two-pass printing for pre-print white, we address each nozzle individually – so the machine controller tells half the nozzles in the head to print white, and the rest to print the ordinary colour. Of course, that means the output is slower, by around 40% depending on the resolution, but it does give a perfect registration of the colour with the white.”

　　Outstanding accuracy

　　The architecture of the Jet2500UV has its curing lamps either side of the printhead – it’s the trailing lamp that cures the dot, after it’s been delivered to the substrate. On the printhead’s return journey (like most wide-format printers, this is a bi-directional printer) it’s the other lamp that cures the dot. Both lamps are constantly on when the machine is working, thus avoiding power surges and potential lamp damage from a flicking on-off state.

　　The Jet 2500UV is one of only a handful of wide-format inkjets on the market to use a linear motor with encoder to drive the printhead. What that means, Hageman says, is “quite outstanding accuracy. It has a very short acceleration time and very precise head positioning”. It also means that, while the printhead gantry travels from left to right to left across the substrate width, the Jet2500UV’s belt-drive is able to move the substrate accurately lengthways – this is the case for both flexible and rigid media. A substrate drive belt comprises four vacuum zones that are automatically set by the machine using the substrate size keyed in by the operator at the start of the job – so there’s no masking-off required.

　　Start-up is less hassle than some other wide-format UV machines – it’s simply a matter of switching the Jet2500UV on and giving it about 10 minutes to get up to its 48°C operating temperature (this is important for the ink viscosity). Once the optimum temperature has been reached, Screen advises running an automatic head clean, although as Hageman is keen to stress, “it’s not required”.

　　There are currently no auto-feeds or deliveries for the Jet2500UV (other than the unwind and rewind provided as standard for flexible materials) but Hageman says these will come soon. Screen will almost certainly build on the back of the autoloader expertise developed for its VLF platesetters. In the meantime, the Jet2500UV will show at Drupa with a manual sheeter for flexible substrates, and may by that time also be possessed of its first optional extra: an extended support table for rigid substrates. The current bed supports boards up to 1.25m in length, but this can be extended to 3m with the optional tables.

　　Self-cleaning

　　The Jet2500UV makes provision for blocked nozzles. These can be detected by triggering the machine to print a test pattern – this can either be done independently or in the margin of a currently printing job. Any nozzles found to be blocked can be automatically unblocked – in all but the most severe of cases – by the machine’s self-clean routine. And for nozzles that block while printing, the Jet2500UV has an automatic stitching fall-back, which triggers the surrounding nozzles to fill in for their inactive colleague. There’s a slight performance hit, of course, but “better that than missing lines in the higher-resolution modes especially,” adds Hageman.

　　At the front-end of the Jet2500UV is a Wasatch RIP, based on the SoftRIP TX Gold core engine: this accommodates all the usual wide-format functions including rotation, step-and-repeat, media optimisation, tiling and a degree of colour management. It also delivers both AM screening (with a coarser screen ruling so that screen process printers can simulate the output of their screen presses) and FM screening for close-distance viewing work. More sophisticated colour management can be had by linking the Wasatch RIP into Screen’s Trueflownet workflow – this boosts performance by taking over the interpretation functions, delivering separated 8-bit Tiffs to the RIP, which then has only to convert from 8-bit greyscale data to droplet size.

　　So far, UK printers have greeted the Jet2500UV warmly, and four orders have already been taken. Burke is optimistic about the machine’s future. “In five years’ time, we’ll be one of the main players in this market,” he says. “It’s huge, it will continue to grow, and we have a unique offering of reputation and a superb printer.”

 

[时间：2008-05-23  作者：Karen Charlesworth  来源：互联网|#]