Article,
Improved Ink Jet In Situ Visualization Strategies
(October 2004)
Abstract
In the last years, printhead, ink and printer manufacturers designed, developed and proposed improved ink jet systems having higher resolutions and smaller droplet sizes. Further optimization of these systems requires more sophisticated print quality tools and in situ visualization tools. As a consequence, print quality and metrology ink jet tools manufacturers have to anticipate and give capabilities to measure these smaller dots and smaller fast moving droplets. Compared to the traditional stroboscopic techniques, nowadays, two alternative ways are used for image capture: photodiode based systems as commercially available from Xennia and pseudo-cinematographic techniques as commercially available from Ardeje.
In this article, the experimental visualization of the dynamics of droplet formation and impact is investigated for various inks and various Drop On Demand (DOD) ink jet printing processes.
The drop ejection devices used are based on printhead modules, electronic boards and hydraulic parts to generate controlled droplets with variations in droplet volumes and velocities.
The visualization methods used are based on high-speed cinematography and proprietary phase controlled ultra-sharp snap shots of the drop formation and impact processes. Different possibilities of high-speed cameras, coupled with lens and optics have been combined with specific illumination sources, to observe droplet behaviour at different steps of the Drop On Demand printing process. Advantages and disadvantages of the different possibilities are discussed in terms of the target applications, being merely related to the actual droplet sizes, and droplet speeds. Both practical and fundamental limitations are discussed for the different in situ visualization strategies.
