Works!
Quality
Advances in
High-speed
Inkjet
By J i m H a m i lt o n
E
48
veryone with a home photo printer has seen that
high-quality color printing is possible using inkjet.
It’s slow, and the ink is expensive, but the ability
to inkjet print beautiful images is nothing new.
What is new today is the ability to translate this into high-
speed use in production facilities. I’ve already written (“The
Impact of Inkjet on Production Print”, Spring 2015) about the
growth production-speed inkjet has had in three key application
areas: transactional documents (like bills and statements), direct
mail, and books.
One common denominator for these applications is the use of
uncoated (or lightly coated) papers and relatively low-color cov-
erage levels. If production inkjet could be fully capable of printing
at high-coverage and high-speed on commodity coated stocks,
then the benefits of inkjet print would expand into other applica-
tions. This would bring digital print benefits such as customization,
personalization, and just-in-time manufacturing into high-volume
segments that to date are primarily printed using traditional meth-
ods such as offset printing.
So it’s important to know that new systems and techniques
that have been introduced recently are beginning to address high
quality and cost-competitive inkjet printing at very high speeds
on coated stocks. These systems, from companies like Canon,
HP, Kodak, Ricoh, and Screen, will begin to tip the balance in
favor of some print applications that have not been economically
feasible so far.
Any method of manufacturing documents is judged by the
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competing factors of quality, productivity, and cost. Let’s look at
this from an inkjet perspective:
Quality | Print resolution and droplet size are important quality
factors for inkjet. Fairly high-speed color inkjet printing systems
existed as far back as 2000, but they were relatively low in res-
olution and the output was not acceptable for many applications.
Today, high-speed inkjet print resolution has soared well beyond
600 dots per inch, and now many devices are capable of 1,200-
to 2,400-dot-per-inch print resolution at very high speed. Per-
haps more important is that the smallest drop size has also been
reduced dramatically. If you run your home inkjet printer in draft
mode, you can easily see the coarse graininess of the resulting
dots. Next-generation high-speed inkjet heads now produce
droplets as small as two or three picoliters. (A picoliter is a tril-
lionth of a liter, and a droplet of this size produces an extremely
small mark on the paper.)
Productivity | Digital print products have sometimes been
belittled because of their slow speed. Inkjet is challenging that
misconception. Inkjet printhead resolution and speed have been
on a steady rise. Today, high-speed inkjet heads can be mounted
on offset presses and run at speeds in the hundreds of feet per
minute. Hitting this speed level was very important in getting pro-
duction sites to acknowledge inkjet’s capability. Full inkjet sys-
tems today can run as fast as 500 or 1,000 feet per minute. At
these productivity levels, they can produce millions of color pages
per month. In fact, the productivity levels are so overwhelming that