Inkjet

The English term non-impact printing (NIP) refers to contactless printing processes that do not require a printing plate. The printing ink is therefore transferred to the medium to be printed without contact. In the inkjet printing process, the printing inks are shot from ink nozzles onto the material to be printed. The print image is created by placing tiny image dots, which is why these printers are also referred to as matrix printers.

In black-and-white inkjet printers, there is only one ink nozzle for the black printing ink. In colour printers, four or more ink nozzles are controlled. The basic colours of the CMYK spectrum, cyan, magenta, yellow and key for black printing ink, can be used to mix almost all colours except special colours or spot colours. High-quality colour prints are produced by controlling the colour dots using the printed ink droplets.

There are even a number of German names that, just like the English word inkjet, express how inkjet printers work. In German, the direct translation Tintenstrahldrucker is used, as well as simply Tintendrucker. Less common terms include Tröpfchenstrahl-Drucker or Farbstrahl-Drucker. The English name with a hyphen is also used in German: Ink-Jet-Drucker. Another term from English is bubblejet printer, which is also common in German. In some cases, the different names refer to different technologies on which the printer’s printing process is based.

The first inkjet printer was developed in the USA by the Teletype Corporation in the early 1960s: the Teletype Inktronic. However, it was not used to produce printed materials, but served as an input and output device for mainframe computers. In the 1970s, the technology was further developed first by IBM and later by the companies that are still well known in the inkjet printer industry today: Canon, HP and Epson. These printers were designed for industrial operation. Inkjet printers for end consumers then came onto the market in the mid-1980s.

There are two fundamentally different inkjet printing processes, which are then varied in different ways depending on the manufacturer or application. For the industrial sector, there is the printing process with a continuous ink stream, which is also reflected in the English term continuous inkjet (CIJ). In the CIJ process, an ink stream is modulated by a piezoelectric transducer in such a way that it breaks up into individual droplets. These are electrostatically charged and then deflected sideways by a deflection electrode, allowing them to reach the print medium in a targeted manner. In DOD printers (drop on demand), the ink droplets are already ejected individually from the nozzle. Each manufacturer has its own process for generating and precisely transferring the droplets onto paper or another print medium.

In the piezo printing process, the droplets used for printing are generated by a piezo element, i.e. a semiconductor. When voltage is applied to such an element, it expands and begins to vibrate. This effect presses the printing ink precisely out of the print nozzle. Negative pressure is created in the nozzle, drawing ink from the reservoir. In the inkjet process with piezo elements, this process can be repeated up to a thousand times per second.

• The simple construction of the printers enables low equipment prices, which results in low printing costs
• Fast printing speed
• Many applications are possible on simple printer paper
• High-quality prints can be achieved with special papers or special films
• An inkjet printer does not create a fixed printing plate, which means that varying content can also be printed in quick succession. This makes individualized or dated printouts possible
• Because only ink droplets come into contact with the material to be printed, sensitive, uneven or moving products can also be printed using inkjet printing
• High-quality inkjet printers can reproduce large colour spaces

• The inks used in inkjet printers are not document-proof. They fade in daylight and are often water-soluble
• Expensive special papers are required for high-quality prints
• The inks dry out easily if printing is not carried out often enough, which can result in the costly replacement of the print heads
• The regular cleaning process to prevent drying consumes a lot of ink
• Original ink cartridges from the manufacturers are expensive
• No-name ink cartridges or refilled ink cartridges sometimes cause colour deviations or can lead to clogged print nozzles

Inkjet films are plastic films provided with a special coating on which ink from inkjet printers adheres. Inkjet films from Bleher Folientechnik are made from heat-resistant BOPET carrier film. They are provided on one side with a rough coating that can absorb inkjet inks. This applies both to dye inks and to pigment inks or other water-based inks. The coating of the inkjet film absorbs the ink and thus enables a fast drying time. This also makes batch processing of the films possible. In addition, the coating of the inkjet films ensures bright, vivid colours in the print result.