Digital printing refers to methods of printing from a digital-based image directly to a variety of substrates. Over the last two decades digital printing has evolved rapidly and now encompasses a variety of technologies, including laser toner, electrophotography, inkjet, thermal and others. During this time the quality of digital print has also improved and now is equal to or even possibly better than some of the traditional print processes.
HP Indigo pioneered digital printing, unveiling the world’s first digital printing press in 1993. This innovation eliminated the need for printing plates and significantly reduced setup times compared to more traditional print methods, whilst also opening new possibilities for businesses, brands and customers in commercial printing, labels and packaging, photo products, and publishing.
HP Indigo technology
The HP Indigo digital printing process utilises Liquid Electrophotography (LEP) digital colour printing technology.
The three foundations of HP Indigo of LEP are as follows:
- HP Indigo Electroinks – are special liquid inks that contain electroink particles of 1-2 microns and are used in all HP Indigo presses. The inks are electrically charged to control their placement onto a photoconductive plate. Due to the inks, unique formulation print quality and performance characteristics they are virtually independent of the pigment. This enables HP to provide the largest set of inks available in the digital printing industry and includes spot colours, taggants, invisible inks, etc.
- Thermal Offset transfer – the LEP process employs a thermal offset transfer process. During this process, very thin electroink layers are transferred from a plate to a heated blanket using an electric field. The heated compliant blanket melts the ink resin particles within the electroink, transforming the particles into a smooth tacky film. Upon contact with the ‘cooler’ substrate, the thin electroink tacky layer quickly solidifies and transfers the image with virtually no change in shape or dimensions.
As the substrate is separated from both a heated and wet environment the HP Indigo press is able to print on a wide variety of substrates types, surfaces and thicknesses.
- Direct Contact Transfer – is similar to conventional offset printing whereby ink is transferred mechanically through direct contact all through the process utilising a blanket, unlike inkjet which is jetted through the air.
The benefits of HP Indigo digital print are as follows: high coverage printing with low ink quantities at high speed, wide media/substrate and application versatility, wide colour gamut (up to 97% of the Pantone range), spot Pantone colours, up to seven stations per press, quick set-up, high laser accuracy, straight through processing with no separate personalisation steps required, incorporation of security print and special effects.