Printer nozzle

Laser Ablation, Fig. 2 KrF laser-drilled ink-jet printer nozzles (30 pm diameter) in polyimide... 

A thermal inlqet ink composition has one or more attractive features, such as short unassisted dry times of printed alphanumeric or graphic images, long decap times, good adhesion to semiporous and nonporous substrates, and safety or material compatibility with one or more components of a thermal inkjet printer (25). The decap time is the time that printer nozzles can be imcovered and idle before they will become ineffective and need to be cleaned. 

When printing in the drop-on-demand mode employing certain inkjet ink compositions on substrates which retain high static electric charges, such as in poly(ethylene) and poly(vinyl chloride) shrink wrap packaging materials, the printer nozzle tends to clog up more frequently than normal (52). 

Namely, poly(ethylene) and poly(vinyl chloride) films tend to hold high static electrical charge. This static charge is generated when the substrates unwind from the spool or are transported via a conveyor system under the printer nozzle. The static charge can be up to 40 kV. This charge tends to distort the ink droplets, causing the droplets to break up more easily and form microsatellites. These microsateUites then accumulate on the printer nozzle. 

Then the ink builds up around the nozzle on the nozzle plate, which leads to poor quality images. Thus, the printer nozzle requires periodic cleaning, which leads to more frequent printer downtime. 

A STUDY OF INTEGRATION OF LIGA AND MEDM TECHNOLOGY ON THE MICRO INJECTION MOLDING OF INK JET PRINTERS NOZZLE PLATES... 

Figure 7.4 is a photograph of a portion of the peptide controls slide printer. A stack of microscope slides, ready for printing, is at the far left. The slides are automatically ejected from the stack, one at a time. The slides are moved on a conveyer to the right, positioning them under the print head. The print head has eight nozzles, out of which microliter-sized droplets are ejected onto an underlying slide. The slide conveyer then places a new slide under the nozzles, and the process repeats. 

The Chemical Inkjet Printer (ChIP), an inkjet printer-like device which is equipped with a piezoelectric reagent-dispensing system, has been developed by Shimadzu Corporation. The ChIP can dispense picoliter volumes of matrix solution onto a tissue section, which has four printing heads and nozzles that have no contact with the tissue section surface. 

In many processes (such as oil recovery, blood flow, underground water), one encounters liquid flow through thin (micrometer diameter), noncircular-shaped tubes, or pores. In the literature, one finds studies that address these latter systems. In another context of liquid drop formation, for example, in an inkjet nozzle, this technique falls under a class of scientifically challenging technology. The inkjet printer demands such quality that this branch of drop-on-demand technology is much in the realm of industrial research. All combustion engines are controlled by oil drop formation and evaporation characteristics. The important role of capillary forces is obvious in such systems. 

Over thousands of years for writing, the ancient people used naturally occurring colloidal fine material from ash (mostly charcoal) dispersed in oil (olive oil). Modem inkjet printers employing color are based on much more sophisticated components. Inkjet printers have a number of nozzles that inject ink droplets on the surface of paper. Simultaneously, different colors are mixed to obtain the desired color shade (more than hundreds of thousands). In a typical printer, there may be 30,000 injections per second, and there may be more than 500 nozzles (each with a size less than a human hair (pm =10 6 m). (The ink has a shelf life of more than a year.) In this process, the surface and colloidal principles most obvious are... 

The ink for inkjet printers is essentially colored water, and the current formulation of ink is about 75% water, plus dye and glue (Kang 1991, Le 1998, Pond 1999). The ink should flow readily from ihe inkwell to the nozzle, and then to the paper, without dripping or clogging. The viscosity of current inkjet ink is from 2 to 8 cP. The droplets formed should be very uniform in size, and should be as small as possible to increase the resolution. When the droplet hits the paper, the droplet should penetrate the fibers without splatter, which would increase the diameter of the dot on the printed text or picture. The surface tension of current ink is around 45 to 50 dynes/cm, which is much lower than water at 70 dynes/cm. It is believed that if the surface tension is raised from 45 to 65 dynes/cm, the spread (or ratio of diameter of spot on paper/diameter of droplet) would decrease from 3.3 to 1.1. Much higher resolutions... 

Conversely, in a piezoelectric inkjet (PIJ) head, the deflection of a membrane drives ink through each nozzle — schematics of the various configurations used in PIJ heads can be found elsewhere. The timescale for PIJ drop ejection is similar to that in a TIJ head (Fig. 1), thus, both are capable of firing 10000 to 30000 drops from a nozzle each second. Typical nozzle diameters d = 10—50 fxm), ink viscosities ( 7 = 1—5 centipoise), ink surface tensions (a = 20—50dyne/cm), and ink densities (p = 0.9—l.lg/ml) are fairly similar for the TIJ and PIJ printers for office and home use. The resulting key fluidic parameters for such print heads are summarized in Table 2. 

Inkjet is a non-contact additive process that delivers metered amounts of a variety of fluids at a precise location in time and space. It requires low viscosity liquid phase inks that must successfully be fired through a nozzle. Inkjet has broad appeal due to its seemingly simple nature. Although all inkjet processes share basic features, the ways in which inkjet technology can be configured are endless. For the most part, drop-on-demand printers have been used in inkjet printing of electronics. ... 

State-of-the-art piezo-based drop-on-demand printers are produced by companies such as Xaar (UK), Konica Minolta (Japan), and Fujifilm Dimatix (US). These print heads have around 180 to 360 nozzles per inch and are designed to print at basic resolutions of up to 360 dpi with drop volumes down to about 40 pi (picoliter). This type of print resolution gives features equivalent to approximately 100 /xm track width on PET or PI substrates. However, Xaar s new generation "gray scale" heads allow variable drop volumes down to around 3 pi to give printed features of around 50 /xm or less. 

The print head of standard, color inkjet printers (Cannon, Hewlett-Packard) is composed of a nozzle, heater, manifold chamber, and restrictor. Once the resistive element is heated (300°C) the fluid... 

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