The Olivetti Lexikon
ink-jet technology
A carefully regulated flow
of ink drops through a series of nozzles, without any mechanical parts
coming into contact with the paper. This, in very basic terms, is the bubble
ink-jet technology. Although the principle is simple in theory, it took
more than forty years to perfect and then to be applied economically on
an industrial scale.
But now, after four decades
of research, bubble ink-jet technology is reaping enormous rewards, thanks
to its reliability, low production costs, high quality and application
flexibility. The first research dates back to the early 1950s. Over the
years, the laboratories of many major corporations and distinguished universities
undertook projects involving a broad range of scientific disciplines from
fluids mechanics to dye chemistry, which produced a wide variety of technological
solutions.
Many of these techniques
were eventually abandoned as impractical or uneconomic; the few that are
currently in use have survived because they can be produced on an industrial
scale at a reasonable cost, offer good quality and reliability, and provide
a basis for future developments. Today, the technological solution devised
by Olivetti Lexikon - the only European manufacturer capable of developing
and producing all ink-jet components, from inks to printheads - is among
the most valid and promising.
Olivetti Lexikon's ink-jet
architecture
The
Olivetti Lexikon technology uses the top-shooter bubble ink-jet principle.
This solution is based on a printhead whose ink nozzles are arranged on
the surface of a microchip according to a special geometric lay-out designed
to optimise ink delivery.
The number of nozzles may
vary, depending on the model, from a minimum of 50 to several hundred,
to enable simultaneous printing of one or more lines of text. Each nozzle
is fitted with a micro-chamber containing the ink, and a heating element
in tantalum-aluminium protected against thermal and mechanical shocks by
layers of thin film. This assembly, which constitutes the basic actuator,
measures less than the cross-section of a human hair. The heating elements
reach 500 degrees centigrade in just 3 micro-seconds, causing the ink to
boil instantaneously and evaporate at a temperature three times above normal,
in the form of a bubble. The bubble acts as a propeller, creating the pressure
required to expel a microscopic drop of ink, which hits the paper at a
speed of 60 kilometres per hour.

As the ink drop leaves the
printhead it creates a vacuum, which causes the micro-chamber to be refilled
with ink. The entire process can be repeated several thousand times per
second.
The advantages of the
Olivetti Lexikon solution
Olivetti Lexikon's ink-jet
technology permits excellent results in terms of printing quality and speed.
It currently supports resolutions of up to 600 x 600 dpi for graphics and
texts, in black and in colour, and also offers the potential for developments
on a still more sophisticated scale. Contrary
to other solutions available on the market, the planar architecture used
by Olivetti Lexikon means the number of nozzles on the microchip can be
comfortably increased, thus improving speed and/or resolution without incrementing
costs. And in fact, cost-effectiveness is another advantage of bubble ink-jet
printing, since the printhead can be refilled over and over before it needs
to be replaced. Olivetti Lexikon's patented Refill System lets the
user replace just the ink cartridge, without having to change the entire
head.
In addition to printers,
a number of printhead models are used on fax machines, typewriters and
cash registers, extending the advantages of the bubble ink-jet technology
- high quality printing on plain paper, low noise, reliability, easy maintenance
and low costs - to other product groups.
Output capability
Worldwide, few other manufacturers
are able to match Olivetti Lexikon in the development and production of
all the components, from printheads to ink, involved in the implementation
of ink-jet technology.
Production is handled in
its plant at Arnad in the Valle d'Aosta, which turns out 10 million heads
and 15 million refills annually.
The industrial cycle is split
into three stages:
-
production of the print microchip,
using processes typical of semi-conductors;
-
manufacture of non-toxic ink
to chemical formulations researched and experimented by the Olivetti Lexikon
laboratories;
-
final assembly, whereby the
actuator unit is joined to the head containing the electrical connections.
Each of these stages is completed
in clean rooms which, according to the type of processing entailed, are
rated either class 100 or 10,000 - i.e. free of dust or any polluting element
- a characteristic ensuring a quality production process and an end-product
offering maximum reliability. Reliability is, in fact, central to Olivetti
Lexikon's ink-jet technology, and is obtained through the characteristics
of the printing head design, use of the best components and optimised production
processes.
Latest developments: the
"pentachromatic process"
The "Pentacromia" or five-colour
printing process, Olivetti Lexikon's latest technological brainchild in
the ink-jet field, adopts a chromatic selection technique based on five
colours: the classic cyan, magenta and yellow, plus two blacks, graphic
black and covering black.
The use of two types of
black ink, housed in two different printheads, is the solution that enables
this exclusive technology to print colour images offering the maximum precision
and sharpness, plus text with outstanding contrast. One of the blacks,
"graphic black", was specifically developed for use with other colours:
it does not blur, dries rapidly, provides excellent definition, and is
ideal for giving colours extra precision. The second black, "covering black",
is used for texts and to improve the general contrast of the printed document:
this is why it was developed from a special chemical formula that makes
it sharp, intense and deep.
The printheads used for
the Pentacromia process, which is adopted by the new generation of printers,
were designed to ensure sophisticated ink control. They offer an extremely
high resolution of 1200 dpi, suitable for high-tech applications, or a
lower resolution, ideal for high-speed printing while maintaining uniformly
pure colours. The advantages of the Pentacromia process are obvious. Most
notably, the fact that it gives users a no-compromise solution combining
colour brightness with sharp black definition.
Moreover, picture quality
is almost photographic since the incorporation of the four graphic inks
in a single printhead ensures high-precision printing. Finally, the Pentacromia
process also keeps cost per page down, thanks to the Refill System, which
means only the ink cartridge need be replaced. A combination of solutions
that provides two significant cost savings: the printheads only need to
be refilled instead of being replaced, and then only the more frequently
used of the two.
Latest news and forthcoming
developments
Olivetti's research on ink-jet,
spanning over 20 years, continues to this day in order to guarantee the
firm's technological leadership in the products using this technology and
to create new openings for the future.
Attention is currently focused
mainly on one aspect: to make available typographic quality colour - at
present obtained solely with highly specialised equipment - to the public
at large. As a result, research is heading in four directions: enhanced
resolution, creating new printing inks, higher speeds and a further reduction
in costs. A first solution, now available, is sparked off by the next generation
of printing heads: the "intelligent heads" with print microchips that contain
the actuator piloting logic. This enable Olivetti Lexikon to substantially
increase the number of nozzles - while maintaining a compact printing head
- and to create without any trouble a new ink-drop emission system through
the use of drop modulation technology.
Historical notes
Olivetti's innovation skills
and technological knowhow in bubble ink-jet printing are the result of
years of research, which have enabled it to acquire 70 patents in this
field. Olivetti began testing the technology in the 1970s, when it developed
the dry ink-jet, a proprietary solution based on a replaceable printhead
and designed as an alternative to impact technology, which proved very
successful on the typewriter and calculator markets.
This was followed by the
spark ink-jet, a technology based on some of the principles that would
later be used by the bubble ink-jet system: the ink was heated, electrolytically
in this case, to boiling point. The spark ink-jet solution provided good
printing quality both in black and in colour, and excellent reliability,
especially for calculators. Olivetti's researchers then turned their attention
to piezoelectric technology, with a set of micro-pumps configured to form
a printhead.
By 1984, this technology
had achieved a printing quality close to today's level. The bubble ink-jet
technique was finally developed in the mid-80s, capitalising on the expertise
accumulated in all the previous projects. Olivetti Lexikon continues research
into printing technologies today, in order to maintain its current technological
leadership in the field and create new openings for the future. |