|This Ph.D. project is a part of the Octopus project, a joint endeavor of industrial and academic partners with the Embedded Systems Institute. The industrial partner is OCE, a world-leading manufacturer of professional printers. The academic partners are Delft University of Technology, Eindhoven University of Technology, Twente University and Radboud University Nijmegen. The Octopus project aims at improving the adaptability of OCE-printers to changing environment conditions, media, customer desiderata and printer dynamics (due to wear, toner contamination, etc.). This project is partly funded by the Dutch Government.
This particular PhD project pertains to the improvement of the printing quality of a Drop-on-
Demand (DoD) inkjet printhead using a system and control approach.
The ability of Inkjet technology to deposit materials with diverse chemical
and physical properties on a substrate has made it an important technology
for both industry and home use. Apart from conventional document printing,
the inkjet technology has been successfully applied in the areas of electronics,
mechanical engineering, and life sciences. It has been used to manufacture
solar panels, PCBs and flat panel displays in the electronics industry. Low
cost metal coating and rapid prototyping are popular applications of inkjet
printers in mechanical engineering. In the medical field, it has been used for
printing DNA structures and making artificial skin, by jetting live cells.
The success of Inkjet technology in all these application is mainly due to its
low operational costs.
Figure: Hot-melt DoD printhead (left) and a cross-sectional of an ink channel (right)
A typical drop-on-demand (DoD) inkjet printhead consists of several ink
channels in parallel. Each channel is provided with a piezo-actuator, which
on application of a standard actuation voltage pulse generates pressure oscillations inside the ink channel. These pressure oscillations push the ink
drop out of the nozzle. The print quality delivered by an inkjet printhead depends on the properties of the jetted drop i.e., the drop velocity, the jetting
direction and the drop volume. To meet the challenging performance requirements posed by new applications, these drop properties have to be tightly
The printing quality delivered by a Drop-on-Demand (DoD) inkjet printhead is limited due to operational issues such as residual oscillations in the ink channel and
the cross-talk between the ink channels. In this project, methods are developed to design the input
actuation waveform for the piezo actuator of the printhead in order to quickly damp the residual oscillations (bringing in this way the ink channel to rest after jetting the ink drop) and to
reduce the effects of the cross talk.
More details on the Octopus project can be found on the web page of the Embedded Systems Institute