Jet of ink

The printer with jet of ink uses liquid ink and authorizes returned colors of quasi photographic quality. The impression is done according to two techniques:

the jet uninterrupted, at the time which drops of ink are continuously ejected print head and are deviated partly towards paper by magnetic reels. The remainder of ink is recovered and recycled for a new cycle of jet.
the jet with the request, at the time which are created and ejected only the drops necessary to the impression.

History

The jet of ink was developed by data processing specialists in the years 1970, in order to propose another exit with the Ordinateurs that the very noisy dot-matrix printer (also called wire-matrix printer). There exist two types of jet of ink. Historically, it is the “continuous jet of ink” then the “drop with the request” which was invented. The jet of ink then made its great strides at the same time as the development of the Informatique general public. Currently, the jet of ink knows a very strong rise, in particular thanks to the Numeric photography, the personalization of printed and the possibility of printing on almost all the supports.

Beginnings of the jet of ink

The jet of ink is a process of impression without contact in which very small drops (about the picolitre) of Encre are projected by tubes. It is in the years 1960 that Dr. Sweet of the Université Stanford showed that by applying a Onde pressure to a tube, ink could separate in uniform drops. Then, by charging ink electrically or not, one can deviate the jet by making it pass in an electrostatic field (it is about the same principle as in a Oscilloscope). One then sees the appearance of the continuous jet of ink ( continuous ink jet or CIJ).

The impression Jet of ink, appeared in the years 1970. Technology was first of all developed by data processing specialists, anxious to find an exit for their Ordinateurs. It is IBM which will patent this technology in the years 1970 and the first Imprimante, IBM 4640 ink-jet leaves in 1976.

Drop one demand

With the same date, professor Hertz of the Lund Institute off Technology in Sweden develops the possibility of printing in levels of gray while varying the number of drops by Pixel. This invention is then patented by Iris Graphics and Stork. It makes it possible to print images of greater quality.

Shortly after develops the jet of ink known as “Goutte with the request” or drop one demand (DOD). There, the drop is generated only if it is desired on the substrate. What avoids the complex device of Déflection.

The pioneers of the DOD are Zoltan, Kyser and Sears. Their invention will be born in 1977 with the Siemens PT-80 and in 1978 with Silonics.

The jet of ink then made its great strides at the same time as the development Informatique.

Currently, the jet of ink knows a very strong rise, in particular thanks to the Numeric photography and the personalization of the printed papers form.

Two technologies: CIJ and DOD

The jet of ink is the only process of impression without contact. It thus makes it possible to print on very varied supports (paper, ceramics, glass, textile, plastics but also cookies or eggs with food inks! …) but also of the supports in relief. It is about a numerical process which does not need printing form (screen for the Sérigraphie, plate for the offset, cylinder engraved for the Héliogravure, Polymère for the Flexographie, plug for the tampography…) what enables him to generate a new image with each printed paper form (like the impression Laser)

The process jet of ink knows several alternatives and has many applications. Two big families however are recognized: the CIJ and the DOD.

The continuous jet

The continuous jet ( Continuous Ink Jet or CIJ) where drops charged or not are generated thus consists of the formation of regular drops in volume and frequency. They charged and are directed according to the reason to generate and can thus be deviated in a receptacle if they are nondesired.

The drops charged are not desired on the support. They are deviated by a electrostatic Champ and are then recovered in a gutter. They réalimentent the print head then. Quality is less than in DOD but rates much higher. One uses it in particular for the marking of the eggs (dates of Péremption…)

There exist two types of Déflection: binary or multiple.

In the binary deflection , the drops is charged or not. The drops charged will be deviated and recovered in a gutter and are recycled. The noncharged ones go directly on the media.

For the multiple deflection , the drops is charged with various stages. What allows a more or less great deflection and thus reached the media at various places.

Technical data (2002):

Viscosity: approximately 1 mPa.s,
energy of surface: 30-40 mN/m,
Volume of the drop: 10 pL,
Speed of ejection: approximately 50 m/s,
Frequency: 1 MHz,
Size of the opening: 10 micrometers.

The drop with the request

The process of drop to the request is developed the most by far. The drop with the request ( Drop One Demand or DOD) is generated with each time it is desired. It is the most current technology in office automation or SOHO ( Small Office - Home Office ) and allows a good quality. It remains however slower.

One can consider four various methods of ejection: piezoelectric, thermics or bubble-jet, valve-jet or jet by valve and the thermofusion.

the piezoelectric process is the most developed and was developed by Epson. The tank of ink is in contact with a piezoelectric crystal which will convert the electric impulses - the wall becomes deformed following an electric excitation - into mechanical force - overpressure due to the crystal causes the ejection of a drop. It is the induced overpressure which allows the expulsion of the droplet.

the thermal process or bubble jet functions on the same principle. By locally heating the Ink with approximately 350°C, one causes a local vaporization of this one and thus an overpressure (a gas takes nearly 24 times more place than a solid, according to the conditions). As previously, a drop is ejected to answer this imbalance. However, this type of ejection poses certain problems, in particular with causes of the thermal stresses which ink must undergo.

the valve jet is currently abandoned because of its bad quality. Its principle resided in electronically ordered microphone-valves which allowed or not the ejection of ink. Its application was primarily industrial, to print big letterss. The advantage was that the fact of having a closed tank makes it possible to use Solvant S volatile and thus a faster drying.

the thermofusion is inspired by the piezoelectric process but here, ink is solid. It must be heated with approximately 150°C in order to be ejector. In contact with the media, ink solidifies and gives then very a good quality of impression. However, ink being in relief, it wears quickly. It is thus necessary to have a flexible good.

Technical data (2002):

Viscosity: 3 with 50 cPoises (2005),
energy of surface: 30-50 mN/m (2005),
Volume of the drop: 3 with 20 pL with the same tube,
Speed of ejection: approximately 30 m/s,
Frequency: 30 with 40 Khz,
Size of the opening: 100 micrometers (2000) to avoid with the tube stopping itself,
Many tubes per capita of impression: 1000 (to increase speeds).

Types of inks

Dyes dissouts

The most current ink is an ink containing dye dissolves in a solvent (a little like ink with water the pens with feather). It has the advantage of being easy to handle and manage in the tubes of jet of ink, but it is very sensitive to erosion and corrosion by the gases (what reduces the lifespan of the impressions considerably).

Inks with pigments

Nearer to the oil-base paint, inks with pigments comprise bulky solid coloured particles (only a few microns all the same), sometimes packed in a resin sheath, which are simply transported by a transparent fluid and easily évaporable.

In this case, ink has a very good behavior, one long life of life. But, the management of ink is complicated by increased risks of stopping of the channels injector and it occurs sometimes a phenomenon of Bronzing which reveals metal reflections under certain shaving lightings.

conducting Inks

A new market develops in the field of the impression, it consists in depositing various conducting materials, called conducting inks . They are made up of metal particles or conducting polymers.

That makes it possible to print labels RFID ( Radio Frequency IDentification ), intelligent labels which improve the traceability of the products. They are often compared with the code-bars but do not require to be visible to be read. So that they develop, it is however necessary to be able to reduce the production costs and to develop a standardization, because the frequencies change according to the countries.

The printed circuits are currently carried out by Photolithographie ( photo-imaging ) or by Sérigraphie ( screen-printing ). Technology jet of ink can also print printed circuits. Quality is less good than with the traditional processes but the cost is quite lower and less pollution.

Applications

The jet of ink is the only process of impression without contact. That enables him to print on various objects.

Office automation

The most popular application of the jet of ink is office automation ( Small Office - Home Office or SOHO). The Encre used is generally containing water for environmental reasons and of comfort obvious. The process used is the drop with the request ( Drop One Demand or DOD), which makes it possible to have a good quality of image but speeds less than in CIJ.

Épreuvage

Before printing on a press offset or other (photogravure, flexography…), one generally tests the printed paper form on an analogical system of épreuvage (Cromalin®, Matchprint®…) or numerical (gauged copier, jet of ink…). That then makes it possible to have an idea of made final in the condition which the system of épreuvage simulates the fattening caused by the press offset (use of a profile ICC, for the numerical systems, which characterizes the press which will be used for the impression). The épreuvage can be carried out out of jet of ink DOD, which gives very good performances in term of quality.

Large Width

The jet of ink is the only process making it possible to print large Laize S (widths). Currently, the maximum widths are of 5 Mr. the jet of ink large width allows to print large posters for exposures, to hide scaffolding… Moreover, these posters being generally single, it is impossible to print them with the traditional processes. Technology used is generally jet of ink DOD with an ink with drying UV (ultraviolet), which gets more resistance to ink (held with the light, abrasive resistant…)

The jet of ink large width is also interested in the impression of the posters of bus shelter, currently printed in Sérigraphie.

Textile

The textiles are generally printed in Sérigraphie, thermal Sublimation or transfer. The jet of ink also positions on the market.
It with the advantage of being very flexible on the design of the file image and thus makes it possible to be freed from certain technical constraints inherent in the trades of printing works. The jet impression of ink on textile makes it possible to reduce times of production and to increase the reactivity. The quality of the printed image is acceptable on a white textile but still insufficient on a dark or black textile because the low thickness of ink deposited. The technique of the jet of ink obtains its best results where serigraphy encounters difficulties (quadrichromy) and paradoxically fails on the simplest work (your direct - plain color). Its speed is slow for the moment but in progress thanks to the multiplication of the injector channels. The cost of consumable is high (90 with 230 € the liter of ink) and machines specific to the textile too recent to know the real cost of maintenance of it.

Marking

The CIJ is generally used for the marking of the products for its print speed. Into food, ink used is containing alcohol which gives a fast drying. The inks used in canning facilities must also be resistant to the treatments (sterilization with the vapor under pressure to 125°C during 25 min) Marking is also present in the car, electronics, the industry of the cable, the aeronautical engineering…

Personalized impression

As a numerical process, the jet of ink makes it possible to change the design with each printed paper form. It can thus attack the market of the personalized impression. One sees good number in publicities of it but it becomes possible to order wine with a label with its effigy, to have single skis…

See too

Paper
Printing

External bonds

the ink of the ink jet printers of ink - Pigment or dye? Technical comparison

history of the invention of the food printer

Simple: Inkjet printer

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