Ionography
The ionography is a method in digital printing. It is one of the non-impact printing processes.
An electrostatic latent charge image is generated with an ion writing head. A conductive, magnetic toner is deposited on this. The resulting toner image is transferred to paper. The fixation of the pressure is fixed by pressure or flash light.
Pressure unit
The imaging takes place via an ion source, which can be built up as a page-wide array with today's technology. The coloring is done with liquid toners. After the transfer to the paper, the drum surface must be cleaned using mechanical and electrical devices. The cleaning is carried out using a doctor blade system. It is already fixed in the nip when the toner is transferred to the paper by applying heat and pressure via the drum (transfixing). After the print image has been transferred to the paper, the final fixation of the print image takes place via a xenon flash lamp by briefly melting the toner onto the paper using radiant heat.
Imaging system
The central component in ionography is the imaging unit in the form of an ion source. The ions, ie positively or negatively charged atoms or molecules, are formed from the ambient atmosphere and via the material of the ion source via high-voltage signals and transported to the imaging surface. The control of the air humidity in the vicinity of the ion source is of particular importance, since if the humidity is too high, voltage flashovers can occur, which lead to wear and tear and destruction of the ion source and the surface. It is therefore necessary to heat the imaging drum.
Printing unit concepts and printing systems based on ionography
Image carrier in tape design
In iconographic imaging, the charge pattern is applied to a circumferential, dielectrically coated tape. The image is not transferred directly to the paper, but first on an intermediate carrier system. The ink is transferred to the printing substrate after the paper has been preheated as part of a multi-stage fixing process.
Multi-color printing based on ionography
In the case of multi-color printing with NIP technology, which is used for printing with ionography, liquid toners are used in particular. There are printing unit configurations in satellite design or printing is carried out on roll material via an intermediate carrier system on which the color separations are collected. Sometimes the printing is done directly on the substrate without an intermediate carrier. Special features of both systems are the imaging on dielectrically coated tape and the measures to remove the carrier liquid when using liquid toners.
Other printing systems based on ionography
Most common substrates / papers can be printed. A four-color print e.g. B. is generated in that one after the other the color separation is imaged onto the paper using only one ion source and then colored with toner; after the paper web has returned, the illustration is made with the second color separation and subsequent coloring, correspondingly for the third and fourth colors (multipass system). A highly accurate register system for rail transport is required. There is also the variant as a series construction (single pass system), in which a separate ion source is installed in front of each development station.
literature
- Helmut Kipphan: Handbook of the print media . Axel Springer Verlag, Berlin 2000, ISBN 3540669418 .