What's New with Inkjet?

By John L. Campo

Have you heard about the new inkjet printer that is capable of printing 500,000 pieces per hour, at 600 dpi, with a printhead-to-product throw distance of a half-inch, can print onto ANY substrate and requires no maintenance? Well, it hasn't quite been developed yet. However, there are some new and exciting developments and improvements going on in the inkjet printing world.

Binary Array Continuous Inkjet (CIJ)

With Binary Array CIJ, ink is pressurized and charged to emit drops; ink continuously circulates through the system (hence continuous inkjet). Binary Array CIJ consists of 256 separate jets, creating a "curtain" of ink, which provides a vertical print window of two inches or more.

The latest generations of binary array inkjet printers have advanced in their linear print speed, start-up efficiency and reduced maintenance requirements. Some print from 100 feet per minute up to 3,100 feet per minute. These printers feature both aqueous and solvent-based inks; the solvent-based printers are able to produce high-speed addressing on glossy stock. Print resolution is typically 170 dpi x 100 dpi to 170 dpi x 240 dpi, so this technology is very capable of
printing the USPS Intelligent Mail Barcode, as well as most other linear and 2D symbologies,
including Datamatrix and QR Code.

The latest generation of binary array inkjet printers offer other improvements, such as a smaller printhead, which requires less space for mounting and significantly less maintenance than older solvent-based binary array printers some up to 70% less which translates to more production time.

Piezo Drop-On-Demand (DOD)

With Piezo DOD, ink is only jetted when required (hence Drop On Demand). Piezo DOD technology utilizes piezo-electric material to generate droplets of ink. Piezo material consists of lead, zirconium and titanium (PZT); when a voltage is applied to the material, it bends or shrinks. That causes a wave pulse to form, which results in an ink droplet being expelled from the printhead. Piezo DOD uses oil-based, solvent-based and UV-curable inks, providing a range of
solutions for various substrates. Piezo DOD also features high resolution printing at
respectable speeds 520 dpi x 316 dpi, for example, and linear print speed up to 950 feet per minute.

Piezo DOD requires minimal maintenance and is quite capable of printing the IMB, as well as all the other major symbologies, including linear and 2D.

Thermal Inkjet (TIJ)

Thermal Inkjet is another form of drop on demand inkjet technology. Tiny resistors create heat, and this heat vaporizes ink to create a bubble. As the bubble expands, some of the ink is pushed out of a nozzle onto the substrate. When the bubble "pops" or collapses, a vacuum is created. This pulls more ink into the printhead from the cartridge. TIJ technology can now be found throughout the mailing and addressing marketplace, providing a cost-effective, low-maintenance,
reliable method for printing targeted marketing and other direct mail pieces. The inks are aqueous, as the TIJ process requires boiling to expel ink. Recent developments have led to inks with more solvent-like characteristics that deliver reduced dry times on glossy substrates. Other recent improvements include faster printing (up to 760 feet per minute) and better printhead-to-substrate throw distance. With its excellent print resolution, TIJ reliably and consistently prints the Intelligent Mail Barcode (IMB).

Which Technology Works in My Application?

Print Resolution Both TIJ and Piezo DOD technology feature many nozzles in a small vertical line/space, providing high fixed print resolution (dpi). With Binary Array CIJ's print mechanics, the nozzles require more spacing between them, so this technology has a lower fixed dpi. Binary array CIJ is able to handle more aggressive solvents (MEK, acetone). More resolution typically means better print quality.

Capital Cost Equipment pricing is determined primarily by the type of printhead technology and the hardware required to make it work (binary array printheads are significantly more expensive to manufacture than TIJ printheads, for instance) and also by the capabilities (speed, substrate, etc.) of the equipment.

Equipment prices typically do not include additional system requirements, such as high end controllers, transports, UV lamps and IR dryers. More print height requires more
hardware, which adds more cost.

Operational Costs Binary Array CIJ tends to have a higher cost per 1,000 addresses due to make-up consumption. However, this cost is marginalized if the system is utilized continuously. With TIJ, because the printhead is part of the ink cartridge, every time a cartridge is replaced, you are "installing" a new printhead, thereby all but eliminating any hardware maintenance requirements.

Print Speed Both TIJ and Piezo DOD technology "buy" print speed with a reduction
in print resolution. The higher the dpi, the slower these technologies print. Binary
Array CIJ is typically not impacted by the speed/resolution conundrum. Some Binary Array CIJ technologies utilize a "double-drop mode," which does impact speed; this is not an improvement in resolution, just an additional ink drop almost on top of the previous drop, to enhance darkness,
improve coverage, etc. All inkjet technologies experience some drop-off in print quality at higher line speeds.

Substrates and Inks Binary array CIJ, using solvent-based inks, is capable of printing on most substrates. Additionally, the solvent inks tend to literally bite into the substrate, providing code permanence. TIJ inks dry on the surface of the substrate and can be wiped away. Both TIJ and Piezo DOD typically require additional hardware for drying/curing. Piezo DOD solvent inks expand the range of substrates somewhat, but for the maximum substrate range, Binary
Array CIJ is the best choice. Binary array provides the widest range of substrate coverage; TIJ provides the least.

Start-Up Time Because Binary Array CIJ uses solvent inks, it requires more time (12-15 minutes) to start up. Once it is up and running, it will operate with minimal
intervention. TIJ technology typically requires five to 10 minutes; simply wipe the heads and begin printing. Piezo DOD technology typically requires 10 to 15 minutes; usually a slight purge and wipe will get the system printing optimally.

Daily Maintenance TIJ technology requires more attention during a normal production day; you typically need to wipe the printhead to clean it of debris every few hours. Also, the more aggressive the ink, the less time the printhead can sit idle. Piezo DOD requires less attention than TIJ, but more than Binary Array CIJ, as dust/debris build-up over a shift will require cleaning. Binary Array CIJ, once up and running, requires little attention until the end of the run/shift.

Printhead-to-Substrate Distance Throw distance is impacted by linear speed; the faster the substrate is moving, the more likely the print will look "shadowy" and fuzzy. Because both TIJ and Piezo DOD are not pressurized, they have less throw distance than Binary Array CIJ.

Intelligent Mail Barcode

IMB implementation has been officially delayed until May 2009; however, that deadline will be here soon. The IMB is a 65-bar, four-state (e.g., four different types of bars in the code) barcode that contains 31 digits of data. The IMB encodes:

The delivery-point address routing code used by the USPS to sort and track mail

Any special services requested by the mailer, such as Address Change Service or Confirm

The class of mail and mailer's ID code (a new feature being introduced with IMB)

The unique identity of the mailpiece

The IMB holds nearly three times the data of POSTNET and can be printed using the same technology. There is one potential caveat it cannot be deciphered by the human eye, which raises quality-control challenges in mail production. However, like its machine-
readable symbol predecessors, there is little doubt that technology will overcome this
caveat, and the IMB will become as ubiquitous on mail as the UPC has become on retail products.

At least until the next new technology comes along. But by then, that inkjet printer that prints 500,000 pieces per hour, at 600 dpi, with a printhead-to-product throw distance of a half inch, that prints onto ANY and EVERY substrate, and requires no maintenance, just might be readily available.

Scott Liniger is a Business Manager for Domino'sCommercial Printing line of industrial inkjet printers. He has been involved with ink jet printing technology for 20 years. Contact: Scott D. Liniger, Domino Amjet, Inc., 1290 Lakeside Drive, Gurnee, IL 60031, www.dominoamjet.com, sliniger@dominoamjet.com.