HP Indigo
Indigo is the name of a range of Hewlett-Packard digital presses .
In 1993, the Israeli inventor and entrepreneur Benny Landa's Indigo company , which was taken over by Hewlett-Packard in 2002, launched the E-Print 1000, the first full-color digital printer with liquid toner (ElectroInk). Due to the high, offset-like print quality, HP itself referred to this technology as Digital Offset Color . In addition to the single-sheet (sheet) printers e-PrintPro +, Turbostream, HP Indigo Press 1000, HP Indigo Press 3050, HP Indigo Press 5000 and HP Indigo Press s2000, the continuous printing systems HP Indigo Press w3200 and w4400 (formerly: Omnius) were also developed .
The three core technologies of HP Indigo Digital Offset Color are:
- ElectroInk (HP Indigos liquid toner)
- Thermal offset
- On-the-fly color switching
Electro ink
HP Indigo's liquid toner contains electrically charged particles, the actual toner, dispersed in a non-conductive liquid (Isopar). As with dry toner , the development of the toner image is controlled by the triboelectric charging of the particles. In contrast to dry toner, the particle size is only 1 to 2 µm. Because of the dust and the lungs, such small parts have to be placed in a carrier liquid. The advantage lies in the possibility of higher resolution and edge sharpness as well as thinner layers of color, similar to offset printing . ElectroInk is offered in the standard process colors ( cyan , magenta , yellow and black ) as well as additional colors.
ElectroInk is introduced into the printing machine as a concentrated paste in cartridges. There it is pumped into the toner tanks and diluted with the carrier liquid (so-called imaging oil), resulting in a consistent mixture of toner particles and carrier liquid.
Thermal offset
As with the offset HP Indigo uses a blanket cylinder on Intermediate Drum (ITM) reared blanket (Blanket) to the developed color separation from the photoconductor drum (Engl. Photo Imaging Plate PIP) to the printing substrate (paper) to be transmitted. The surface of the rubber cylinder is heated to approx. 105–110 ° C, so that the pigment-containing particles of the ElectroInk begin to melt and form a thin, still soft, plasticized layer. Any carrier liquid that may still be present is evaporated. When it comes into contact with the cold paper, the ElectroInk solidifies and remains firmly attached to the paper surface. Due to this process, the paper leaves the printer largely dry and can be processed immediately.
Color switching
With HP Indigo technology, all separations are printed with a single roller. This is possible because the blanket (rubber blanket) transfers a color separation practically completely and no remnants of the previous image remain on the blanket.