In the constant quest for competitive advantage, increased production efficiencies and lower costs are top priorities in all industries. Inkjet printhead manufacturers are no exception, as microfluidic applications extend to inkjet ink and its delivery. OEMs know that microfabrication can dramatically enhance time to market by shrinking cycle time. Microelectronics has been revolutionized by the advances in manufacturing methods used to make high-performance electronic devices in high volumes and at low cost.
Not only is miniaturization more cost effective from a unit-cost standpoint, but it also yields improved product quality because smaller measuring systems have less impact during the manufacturing process, according to researchers at the University of Illinois Nanotechnology Core Facility in Chicago. In addition, design modification is simpler, making product arrays much more manageable, the engineering faculty there has reported.
Such technological advancements are important as inkjet printing expands its scope in the graphics market from wide format into new market spaces (see sidebar), said Bailey Smith, director of business development for Fujifilm Dimatix. “The Fujifilm technology that has helped create the precision standard in the industry is silicon printhead fabrication,” Smith contended. “The ability to create fine, precise, and repeatable features in silicon enables higher nozzle packing density, compact footprint, excellent nozzle uniformity both in position and size, and world-class drop placement accuracy.”
What does this mean to an end user? “While there are many factors to be considered when analyzing image quality, the use of this [silicon] technology means the printer you are working with has printheads that can enable the highest image quality capability,” Smith noted. Silicon fabrication technology is core to the J Press 720, the high-quality, sheetfed inkjet press offering a half-size solution for print runs of just one or thousands. “It uses Fujifilm Dimatix’s SAMBA single-pass piezo drop-on-demand inkjet head technology to achieve an impressive, true 1200x1200 dpi [dots per inch] resolution with a four-level grayscale—a specification unobtainable from any other inkjet press,” he added.
Drop-on-demand (DOD), piezoelectric technology is featured in the core printheads used in industrial printing, other than continuous inkjet coding heads used for product identification and expiration dates, pointed out Marco Boer, VP/analyst at research firm I.T. Strategies. The term is derived from the Greek piezo or piezein, which means to squeeze or press “Thermal printheads are mostly captive to HP and Canon,” Boer added.
Sizing up the market
Piezo inkjet printhead technology is the heart that makes most industrial inkjet printers (non-consumer) possible, cited an I.T. Strategies study from 2012. “Collectively, inkjet printing system integrators purchased in excess of $600 million worth of piezo printheads from Epson, Fujifilm Dimatix, Konica Minolta, Kyocera, TTEC, Ricoh, SIIP, Xaar, and a handful of smaller providers,” the study reported. “Typically, those heads account for between 5 percent and 15 percent of the value of a printing system, which means that a $100,000 wide-format printer is likely to include at least $10,000 worth of piezo printheads. As a percentage, this means the $600 million in piezo inkjet printhead sales generated in excess of $6 billion in value in 2012.”
Piezo inkjet printhead sales stalled during the 2008-09 economic recession, I.T. Strategies also has reported, as inkjet integrators drew down on their inventories rather than order new printheads. “In 2010 the recovery in demand for printheads was even stronger than most had projected, in part premised upon restocking of inventory and new product sell through,” said Boer. “Most piezo printhead manufacturers were running two to three shifts per day to keep up with demand.”
There was concern in 2011 that demand would stall again as inventories had been replenished. However, this did not happen in large part due to a trend towards single-pass inkjet printing systems that can use from 20 to up to 500 or more printheads per system. (Serial-based systems commonly use between four and 12 heads per system.) Many of these models became commercially available this year.
Demand was flat in 2012, in part because the core market for piezo inkjet printheads – wide-format graphics printers -- is reaching maturity in terms of its market demand life cycle and in part because the printheads are becoming more reliable, which translates to fewer replacement parts. Also, the number of nozzles per printhead is increasing dramatically, so fewer printheads are needed per printing system. As a result of higher nozzle density, the weighted average selling price of industrial piezo printheads has doubled to nearly $600 per head.
HP Scitex manufactures its HDR300 printheads in the United States at HP’s Corvallis, OR facility. Large-scale silicon production there provides the benefits of quality control and economies of scale. In March 2012, Kyocera began mass production of commercial print inkjet heads in Japan: its KJ4B-Y for water-based ink and KJ4A-B for UV-curable ink. Both offer “the world's fastest print speeds.” The company initially produced 1,000 units per month (total for both types combined) and has been gradually increasing production volumes.
These printhead unit volumes give some indication of the manufacturing capacity needed, which is important as an indicator of automation capability, I.T. Strategies pointed out. “While the manufacturing of industrial piezo inkjet printheads is becoming more automated, it remains far away from the levels of automation experienced by thermal inkjet printhead manufacturers whose core business relies upon desktop consumer printer demand,” the firm reported. Many of the piezo inkjet printheads sold were hand assembled during a large portion of their manufacturing process. But a migration to the aforementioned next-generation, micro-electromechanical systems (MEMS)-type piezo printheads is encouraging further automation. The trade-off, of course, is a requirement for higher volume demand to justify the upfront capital investment in manufacturing plant, “which can run up to $100 million per facility,” according to I.T. Strategies.
24,000 drops per second
HP Scitex explained the basic concept behind binary inkjet printing, which forms an image from “binary dots,” where a drop of ink is either ejected (or not) at a specific location. Each color of ink has a specific drop volume, and drop volumes are measured in picoliters (pl)—there are one million-million picoliters in a liter. (Drops may also be characterized by their weight in nanograms. For inks with a specific gravity of 1.0, the numerical values are the same.)
HP Scitex HDR300 printheads employ an innovative piezo inkjet technology, developed by Hewlett Packard engineers, where each nozzle produces drops at three volume levels—15, 30, and 45 pl—at up to 24,000 drops per second. The printhead is a compact, self-contained module with a robust, industrial design. Pull-out/plug-in servicing offers easy assembly and press maintenance, HP Scitex said. Glass, silicon, and epoxy are the only materials that come into contact with ink for long and reliable service life.
Each printhead has 192 nozzles spaced at 150 nozzles per inch for a 1.28 inch print swath. The 24-kHz design produces high ink flux for high printing productivity: each printhead can eject up to 12 ml of ink per minute. Printheads are calibrated during manufacture for uniform drop velocity and drop volume across the nozzle array, according to HP.
The HDR300 heads feature mechanical, ink, and electrical connections that allow the printhead to be simply plugged into place and secured with two screws. Two locator pins provide better than 10-micron positioning accuracy without adjustment. Ink connections are made through two ports, each sealed with an O-ring, and there are no ink tubes to attach and tighten, HP said. Electrical power and control signals come through a standard 30-pin connector that interfaces to a solid electrical bus bar to ensure reliable, error-free printhead replacement.
For latex inkjet, the HP Latex 3000 Printer features a writing system with more than 70,000 nozzles and advances based on HP 881 Latex Inks, HP Latex Optimizer, and HP 881 Latex Printheads to deliver industrial-scale efficiencies ideal for large print service operations. HP Latex Optimizer delivers consistent image quality and supports high-efficiency curing of HP Latex Inks at lower temperatures and with less energy than previous HP Latex Printing Technologies. Dynamic swath alignment suppresses banding even at the highest levels of productivity, according to HP.
Japanese innovation, too
Kyocera has been mass-producing its 1200- and 600-dpi inkjet printheads. In mid-2012, the Japanese OEM component supplier announced the successful development of the KJ4B-Z Series 1200×1200dpi high-resolution inkjet printhead for water-based ink, achieving “the world’s fastestprint speed of 262 fpm for an inkjet printhead.” Four months later, the firm announced a 300-dpi inkjet head that enables simultaneous two-color printing, effectively halving the number of heads required. At that resolution, it offers the world’s fastest printing speedof nearly 500 feet per minute, the manufacturer said, thanks to its ink flow channel structure design techniques and piezo actuator drive control technology. The printhead achieves simultaneous two-color printing through the firm’s same proprietary ink flow channel structure design along with its high-precision ink discharge control. The new nozzle configuration prevents the mixing of inks at the point of contact with the printed material—a potential problem when printing two colors simultaneously from the same printhead—ensuring that the new head delivers quality printed images.
The 300-dpi head also reduces the number of parts required for wiring, contributing to equipment downsizing. In addition, it has achieved an effective print width of 367 feet, the world's widest for this type of printhead. Reducing the number of printheads used, even when wide-width printing is required, contributes to simpler equipment design and easier assembly, Kyocera explained. During equipment assembly and when parts need replacing, it reduces the burden of a range of adjustments including micron-level head alignment and ink discharge.
Looking into the proverbial crystal ball, what can we expect to see printhead-wise in inkjet’s future? Ink recirculation at the nozzle is one technology that will be more widely used, Fujifilm Dimatix’s Smith believes. Printheads with this feature will allow ink to continuously move past the nozzle plate, providing fresh ink to the active jetting area at all times.
“The advantages of this feature include the ability to reliably jet inks with heavier pigments—white, for example—and the ability to allow longer maintenance intervals with fast-drying inks,” he explained. “This capability can be used to improve the functionality of the inks, allowing broader application spaces. This technology is currently used in the J Press 720, and we expect to see [it] become more commonplace going forward.”
Ceramics, Packaging, and Label Apps, Too
The inkjet encroachment no longer is limited to the traditional graphics market. “There is a lot of new activity in areas like packaging, textiles, ceramics, and 3D printing,” said Jim Hamilton, director of the production group at research firm InfoTrends. As Hamilton’s counterparts at I.T. Strategies explained, “for years the wide-format graphics market dominates in the demand for industrial piezo printheads. Consistently, wide-format graphics accounted for 60 percent to 70 percent of printhead demand. In 2011 a big switch in demand occurred, driven by above market average growth in ceramics and packaging/label applications. Combined, those applications grew 7 percent in consumption of piezo printheads ….”
The second largest application demand is for publishing, according to I.T. Strategies, which consists of inkjet production printers such as the Oce Jetstream and Ricoh InfoPrint 5000 series as well as the console-type Riso inkjet printers. “The Riso product line throws off the curve in this segment as those printers sell in very high-volumes with an average of 24 printheads per printer,” the research firm reported. The next generation of high-print quality sheetfed production printers introduced at drupa 2012 also fall into this category.
Like a soothsayer, I.T. Strategies predicted that the application to watch for rapid growth going forward may be textiles. “It is possible that breakthroughs in single-pass inkjet printhead technology could open up the possibility of using inkjet to create a more efficient and time-compressed apparel design to customer process,” the firm reported. “Some very large European apparel providers have become leaders in inventory efficiency optimization; inkjet printing could be the next step in further improving time-to-market optimization, thereby reducing the rampant discounting that occurs in the fashion world.”