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Inkjet proofing update

Oct 1, 2003 12:00 AM


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If all inkjet engines were identical, you could simply evaluate them based on price and output dimensions. But distinguishing features include inksets, dye/pigment and ink-delivery systems.

Inksets have traditionally been cyan, magenta, yellow and black (CMYK), but many newer printers utilize six-color inksets, featuring light cyan and light magenta in addition to the standard process colors. Light black (gray) is the defining characteristic of most seven-color inksets, which are often described using the acronym CcMmYKk; the lower case letters denotes the lighter color. Including the lighter shades allows the device to extend its tonal range further into the highlight range, for more pleasing pastel colors. (Because yellow is such a difficult color for the human eye to distinguish, no manufacturer supplements its inkset with light yellow.) Roland and MacDermid ColorSpan both offer inksets that include orange and green; the DisplayMaker printers from ColorSpan are even available with 12-color inksets that include red and blue.

Dye vs. pigment remains a hotly debated topic. While dyes have a longer legacy within the proofing marketplace and are typically less expensive, many buyers are intrigued by new pigmented inks. According to Roy Bohnen of color-management consultancy Chromaticity (Grand Rapids, MI), the most attractive attribute of pigment is apparent when analyzing test targets during the color-management profiling process. “Dryback seems to be significantly less of a problem with Epson's new Ultrachrome pigmented inks,” says Bohen. “Test targets measured 10 minutes after output and then again two weeks later exhibited virtually no change in measured values.”

It's all about droplet volume

Delivery systems generally fall into one of three categories: continuous flow, thermal drop-on-demand and piezoelectric drop-on-demand. Nearly 20 years ago, Scitex IRIS proofers introduced the graphic-arts world to continuous-flow imaging, pumping a non-stop stream of ink through a specially shaped nozzle that turned the stream into a series of droplets. These droplets could then be selectively aimed at the substrate or into a waste gutter by use of a charging tunnel. A more recent introduction, the drop-on-demand concept, forces small droplets of ink through a tiny slot in a nozzle plate. Piezoelectric devices physically squeeze the chamber to force release of the ink, while thermal devices heat the chamber until the resulting expansion produces a droplet from the nozzle.

Regardless of how the droplet is produced, it will eventually land on the surface of the proofing paper. How much (or how little) ink can be addressed to each specific location plays a significant role in determining the apparent resolution of the printer. In the past five years, we've seen resolution numbers rise from a mere 300 dpi to 1440 or even 2880 dpi. These numbers, however, don't always yield the expected improvement in image quality — when comparing the specifications for two devices, remember that an increase in the addressability (resolution number) should be accompanied by a corresponding decrease in the droplet volume.

Until recently, anyone purchasing an inkjet printer for graphic-arts use would have looked for a bundled RIP, either on an accompanying computer workstation or embedded within the device itself. If you'll be using the RIP from your existing imagesetter or platesetter to drive your new inkjet printer, you'll save some money with a RIP-free device. Heidelberg, Creo and Agfa all offer color-management services as part of the package when an inkjet printer is attached to one of their workflow systems.

Agfa (Ridgefield Park, NJ)

The Sherpa line of digital proofers has enjoyed a solid reputation for quality and ease of use, highlighted by its compatibility with Agfa's Apogee workflow. The six-color Sherpa 43, Sherpa 62 and Sherpamatic printers all utilize the Mutoh RJ-6100 Plus “Micro Dot” piezoelectric engine, while the more recent Grand Sherpa (in 50-, 64- and 87-inch widths) are four-color devices based on Mutoh's RJ-8000. The newest member of Agfa's inkjet family is the Sherpa 24m contract proofer, a seven-color machine with a 24-inch width. Its small four-picoliter minimum droplet size provides excellent detail at 720 × 720 dpi.

Canon usa (Lake Success, ny)

Canon is expanding its graphic-arts inkjet presence — we've selected four models of special interest to the printing industry (see chart). The newest, Canon's imagePROGRAF W8200, was just introduced at Graph Expo 2003. The six-color W8200 handles cut sheets as well as rolls up to 44 inches wide, and can deliver either dye or pigmented inks at 1200-dpi resolution with an eight-picoliter minimum droplet size. This system also includes a simple software RIP capable of processing PostScript files from hot folder input, but without support for color management.

Since 1977, Canon has described its thermal technology as “bubble jet” — small resistors generate the thermal effect used to drive the ink droplet through the nozzle. MicroFine Droplet Technology is Canon's moniker for the latest version of its bubble-jet engine, featuring a 1.07-inch-wide high-density printhead. Price and performance are both key selling points for thermal inkjet devices; Canon claims its devices require no periodic maintenance or parts replacement.

Creo (Vancouver, BC)

After acquiring Scitex and its IRIS inkjet printer division in April 2000, Creo's engineers updated the classic IRIS continuous-flow inkjet engine. This effort produced the IrisPEN, a modular cartridge that improved performance and eased maintenance as part of Creo's new Multi-Drop Array inkjet-imaging technology. Available in Creo's new Veris proofer, these IrisPENs deliver 1500-dpi resolution with an ultra-small, three-picoliter droplet for highly detailed results. Veris internally tracks recent calibrations and can ascertain if the proper combination of ink, media and ICC profile was used. Known as the “Creo Certified Process,” the Veris can image its stamp of approval directly onto the proof, along with a summary of the proofing parameters used.

Dupont imaging technologies (Wilmington, DE)

The newest inkjet printer from DuPont is the Cromalin b2, which has already been introduced in Europe. The new Chromalin b2 is an industrial piezo drop-on-demand printer, imaging onto a rotary drum by means of a temperature-controlled, curved-plane, piezo-head array.

“This system is not designed to replace our continuous-flow Digital Waterproof IG4,” explains Craig Reed, DuPont's global business manager for inkjet. “Instead, the Chromalin b2 is positioned to deliver the precision of rotary-drum imaging at a midrange price that includes a dual-processor, high-end Dell workstation to host the RIP software.”

Reed also defends the selection of a sheetfed-only rotary drum-architecture for the new printer, despite competition from low-cost, wide-format capstan plotters. “It's not intended for making banners, it's dedicated to digital proofing,” says the exec. “We only sell our printers as a full turnkey package; our guaranteed color performance means we both install and train. When we walk away from an installation, they're already in production.”

Encad Inc., A Kodak Co. (San Diego)

Encad's thermal microburst machines — now offered by Kodak — run the gamut from large to enormous, but the options listed in the accompanying chart (p. 26) focus on those sizes most appropriate for the printing industry. The Encad NovaJet 880 is unusual not only for its 60-inch width and ability to use either dye or pigmented inks, but also for its eight-color inkset. The standard CMYK process set can be expanded with light cyan, light magenta, orange and green, or users can choose a set that offers three shades of cyan and three shades of magenta in addition to yellow and black. For substrates that require extremely heavy ink coverage, Encad's new Double Drop technology allows users to lay down twice the normal volume of ink without a reduction in throughput.

Epson (Long Beach, CA)

Low cost and high performance have been the hallmarks of Epson's popular line of seven-color proofers, including the Stylus Pro 7600, 9600 and 10600. Users must select between Epson's dye-based inks or pigmented Ultrachrome inks — a decision not to be made lightly, since the chosen ink can't be changed after installation.

As an advocate of pressure-driven piezo imaging, Epson touts the consistent delivery of ink droplets as small as four picoliters from its Micro Piezo DX3 printhead. Combining high speed and high resolution, these printers are distributed by Epson as well as resold as a component of several vendors' proofing systems.

Hewlett-Packard (HP) (Palo Alto, CA)

The wide-format Designjet 5500 has won wide acclaim since its 2002 introduction, and now HP has introduced an even more advanced level of technology to the desktop with its new Designjet 120 and Designjet 120nr printers. Handling widths up to 24 inches at resolutions as high as 2400 × 1200 dpi, this newest member of the Designjet family produces a small, four-picoliter droplet size with HP's thermal Color Layering imaging technology. According to Sandy Gramley, HP's Designjet product manager, “We're excited to offer the Designjet 120 as a professional tool for designers, ad agencies and small printshops that are looking for high quality without the high price tag. Our wide-gamut, six-color inkset provides consistent output that's ideal for emulating offset print processes.” Combining 24-inch capability and the convenience of a 100-sheet tray (for cut sheets up to 13 × 19 inches) with an affordable price, these six-color printers seem poised for success.

Hyphen Asia Pacific (distributed in the U.S. by Flashlight Figital [Ypsilanti, MI])

If your workflow requires the creation of two-sided proofs, it's hard to beat the speed of printing both sides simultaneously — a capability reportedly offered exclusively by Hyphen Asia Pacific's Impoproof series. A unique concept in duplex output, these imposition proofers consist of two standard large-format printers bolted together, combined with special software and an optical registration system for accurate front-to-back registration. The Hyphen ImpoProof 1050 × 2, available since 2001, utilizes a pair of HP 1050c wide-format printers and is also available as a single-head model for manual reinsertion.

The newly introduced Hyphen ImpoProof 7200×2 incorporates a pair of Canon 7200 six-color inkjets, providing an output speed of 150 sq. ft. per hour at 600 dpi. According to Mark Chinchen, director, “Our new device is based on the Canon 7200, and that new technology provides faster output, more colors and a higher resolution for the same price as our previous model.”

Kodak Polychrome Graphics (KPG) (Norwalk, CT)

KPG hopes to benefit from the cachet that the “Matchprint” name carries as it expands its digital proofing selection. The Matchprint Inkjet Proofer Models 5542 and 5560 offer six-color thermal-dye imaging on cut sheets or roll stock at widths up to 42 or 60 inches, respectively. The greatest selling point of these devices, however, may be the capabilities of the KPG Color RIP software. According to Robert Pipe, worldwide director for proofing, “Our heritage and knowledge of the desktop proofing market, accumulated over many years, is clearly evident in the new products. KPG provides a complete solution for our customers, including the paper, ink, printer and software, as well as service and support.”

For printers that prefer to process files using their platesetter's RIP, KPG's Matchprint inkjet proofers can be driven by post-RIP, one-bit TIFF files utilizing KPG's OBTi interface.

Macdermid Colorspan (Eden Prairie, MN)

Acquired in 2000 by MacDermid Printing Solutions, ColorSpan's line of DisplayMaker rotary-drum inkjet printers offers a wide range of inkset choices. Accommodating 12 dye or pigmented inks at once, the DisplayMaker X-12 supports multiple shades of cyan, magenta and black as well as orange, green, red and blue. With its 72-inch paper width, this rotary-drum thermal inkjet printer can output an impressive 200 sq. ft. per hour at 1800-dpi resolution. For budget-minded operations, the DisplayMaker Esprit offers similar capabilities in a 62-inch-wide, eight-color configuration.

Roland DGA Corp. (Irvine, CA)

Printing companies that favor Pantone's six-color Hexachrome ink palette can look to Roland's Hi-Fi JET Pro II for their digital-proofing needs. Although it is widely known for being the first inkjet printer to obtain certification from Pantone for Hexachrome reproduction, the Hi-Fi JET is also capable of using the popular light cyan, light magenta six-color inkset. The 74-inch-wide Pro II model, introduced in 2002, uses 360 piezo nozzles per color to generate a sharp five-picoliter droplet and 1440-dpi resolution output. The Hi-Fi JET sports a Fast Ethernet connection to its onboard PostScript RIP, but it can also be accessed directly via the bi-directional parallel interface.

Techsage (distributed in the U.S. by Tekgraf [Greenville, SC])

The SpinJet 1000 System from Techsage was launched at Drupa, then updated to the Spinjet 1000 Plus in 2001. This device, like the newer Spinjet 5500 System, is actually a stock HP printer with additional hardware that allows printed sheets to be automatically turned and reinserted for duplex printing. With the addition of Techsage's SpinFlow software, users may define a variety of imposition styles as well as preview thumbnails of the backed-up sheets. SpinJets can be purchased as complete units, or Tekgraf technicians can modify your existing HP 1000 or HP 5500 onsite.

Conclusion

The ever-improving price/performance ratio of today's inkjet printers has been a tremendous enabling force in the migration to all-digital workflows. Whether you choose continuous-flow, thermal or piezoelectric drop-on-demand, the bountiful cornucopia of sizes, resolutions and inksets should be enough to make any printer give thanks.

You get what you pay for…

Inkjet proofing quality and speed improvements have blurred the lines between consumer, home office and commercial product lines. Small printshops searching for inexpensive digital workflows can find printers in the $700 range capable of creating 13 × 19-inch output of surprisingly high quality — albeit at pokey speeds. Combined with GimpPrint and ESP GhostScript, the free Mac OS X print driver and PostScript RIP combination available online at http://gimp-print.sourceforge.net/, these low-cost desktop inkjets are generating quality digital output.

But, as always, spending more gets you more — heavy-duty construction, bigger ink tanks, larger output sizes and high throughput are all characteristic of the professional models reviewed within this article.