Basic Knowledge of inkjet printer

Types of ink

1. DYE BASE INK

Dye is a colorant that is fully dissolved into the carrier fluid, and the resultant ink is a true solution. Once dissolved into the carrier fluid, a well-made dye should never separate or settle out. The analogy of dye ink is that it's like diluting a fruit juice with water, Once stirred, it never separates again - no matter how long you leave it

Characteristic of dye based ink :

• Non water resist

• wide colour gamut

• Poor UV resistance and weakest longevity ratings.

• Take Longer time for dry on paper / other media.

Dye based ink develop become dye sublimation ink

1. The inks are first transferred in a non-sublimated (or inactive) state to standard paper .
2. Then, using a heat transfer press, the printed image is heat transferred (sublimated) to the final substrate.

Sublimations inks generally do not transfer well to darker type materials. Sublimation inks use dye to permeate the material and typically transfer better to lighter colored materials.

 

2. PIGMENT INK

Pigment is a very fine powder of solid colorant particles suspended or dispersed throughout the carrier fluid. The analogy for a pigment ink is that it resembles sandy-colored water in a river or at sea. If you look closely, you can see the particles of sand dispersed throughout the water.

Characteristic of Pigment ink :

Inkjet Printer Technology

Inkjet printer have 3 kinds technology: thermal, piezoelectric and continuous.

1. THERMAL PRINTHEAD

All thermal printheads work according to the same basic principles.
A Heater, or resistor, is located on the floor of an ink channel, near a printhead nozzle.
A short voltage pulse is applied to the rsistor, causing rapid heating of the ink to above the boiling point. This transition from liquid to vapor causes expansion of the ink, forcing a drop out of the printhead nozzle. The drop breaks off, and the bubble collapses back onto the heater, ready for the next drop to be fired. This process is repeatable and reproducible thousands of times per second.

There are two configuration types for thermal ink jet: Roof-shooters and Edgeshooters.

( Pict 1. The Edgeshooter designs )

Issued by Hewlett-Packard and Lexmark, ejects ink directly forward of the resistor. This results in a shorter bubble flight distance, which translates into greater drop repetition capability. In a roofshooter, the ink supply is located beneath the resistor. This enables the ink supply to absorb the excess heat that is generated, there by decreasing the potential for overheating.

( Pict 2. The Edgeshooter designs )

Employed by Canon and Xerox, eject ink to the side of the heater. This longer flight distance has traditionally resulted in less precise drop repetition. Edgeshooters, however, are a more simple design, are more easily manufactured and have remained a popular lower cost alternative. Advances in edgeshooter design have improved performance, and drop repetition equal to a roofshooter is now possible.

Advantage :

• Low cost production, so the price is cheaper than piezoelectric technology
• the heads on most thermal printers are user-replaceable with no costly head repairs

 

2. Piezoelectric printHead

piezoelectric printheads rely on the generation of an electric field and the subsequent deformation of a special ceramic material. This in turn triggers an ink volume change in the pressure chamber, forcing the ink through the nozzle and onto the recording media. Large ink volume displacement is necessary for drop formation, so the physical size of the driver is often much larger than the nozzle, creating a size constraint in the design of the printhead.

The market leader in the use of piezoelectric head technology in desktop printers to date has been Epson.

( Pict 3. Piezzo electric printhead)

advantage :

printhead technology has been the ability to achieve very high resolution (2880 dpi) and “photo” quality printing.

 

3. Continuous inkjet (CIJ)

In addition to drop generation techniques, CIJ must also include drop deflection, and ink collection and recirculation methods to harvest and recycle ink that is not applied to the substrate.

Inks used in CIJ applications must be conductive.

CIJ is popular for industrial type applications such as bar coding, product labeling and box printing

( Pict 4. Continuous inkjet)