Technologies
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

Top Shooter bubble ink-jet principleThe 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.

Top Shooter details - Actuator

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. Printhead Refilling SystemContrary 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.

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