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Renner Johannes

Wissenschaftlicher Adjunkt FH

Hauptkompetenzen

Wissenschaftlicher Adjunkt FH

Büro: MIC_10_157

Haute école d'ingénierie et d'architecture de Fribourg
Boulevard de Pérolles 80, 1700 Fribourg, CH

Master of Science in Engineering (MSE) - Bern University of Applied Sciences

2017

Waveform Optimization for Piezo Drop on Demand Inkjet Print Heads by Meniscus Motion Analysis

Wissenschaftlicher Artikel

Renner Johannes, Bircher Fritz

Advances in Print and Media Technology 44 (Iarigai 2017), 2017 , vol. 44, no 1, pp. 15-20

Link zur Publikation

Zusammenfassung:

Waveform optimization is a key to success for piezo drop on demand printing systems. The industry estab-
lished method for waveform analysis and optimization is a drop watching analysis. With a drop watching sys-
tem, usually a large number of droplets has to be jetted for each configuration of the printing system. As inkjet
is increasingly being used in functional printing, an increasing number of fluids with a certain toxicity, limited
stability or very high material cost are jetted. For such applications, there is a need to reduce the amount of
wasted fluid. The aim of this publication is to explore the potential of estimating jetting properties and opti-
mizing waveforms by meniscus motion analysis with a standard drop watching setup. By analyzing the menis-
cus motion at different pulse amplitudes below the drop emission threshold, the voltage necessary to reach a
certain drop speed could be estimated. An estimation of the frequency - velocity variation can be obtained by
analysis of the meniscus motion in the range of actual jetting frequencies.

2014

A direct printed passive RFID sensor for content aware drug bottles

Wissenschaftlicher Artikel

Renner Johannes, Mazza Marco, Pierluigi Civera, Bircher Fritz

Advances in Print and Media Technology 41 (Iarigai 2014), 2014 , vol. 41, no 1, pp. 85-89

Link zur Publikation

Zusammenfassung:

Lack of compliance with regard to medical prescriptions has become a major cause of treatment failure, a problem
particularly faced in the aging population. In order to aid patients in taking their medication properly, various
products for solid drugs like electronic pill organizers have recently appeared on the market whereas there is a lack of
effective solutions for liquid drugs. In this paper, a novel direct printed RF sensor for drug bottles is presented as a
low-cost solution, which can be used for monitoring liquid medication. The fully-printed, single layer metal sensor has
been realized on the top of a polyethylene bottle, acting as a resonant LC tank, which can be read remotely. Resonant
frequency drifts proportionally to the liquid content, since the distributed capacitance value is affected by the per-
mitivity of the liquid.

The demonstrator presented in this article shows an impressive sensitivity up to 316 kHz/mL, resulting in a cost-
efficient and viable solution to detect content variation in the order of sub - milliliters.

2013

Multi Wavelength Imaging for Drop Watching Systems

Buch

Renner Johannes, Karl-Heinz Selbmann

2013, Chemnitz, Germany : Verlag für Wissenschaft und Bildung, 49 p.

Link zur Publikation

Zusammenfassung:

For measurements of drop speeds and trajectory angles, which are independent of a minimum jetting frequency and unaffected by jitter time on the firing of drops, drop watching systems flash twice with a short flash delay between the flashes during the exposure of one image. The drop speeds and trajectory angles can then be calculated with the displacement of the same drops in the image during the flash delay. By overlaying replicate measurements in one image, the variance of the properties can qualitatively be measured for a print system configuration in an efficient way. The main disadvantages limiting the reliability of such measurements, may be errors in the correlation of overlaid objects, a reduction of the contrast or overlapping artifacts. To enable reliable overlaid measurements or increase the performance and reliability of drop watching systems, a solution with a multi wavelength imaging system is introduced in this paper

2011

Simulation aided design of inkjet systems

Wissenschaftlicher Artikel

Renner Johannes, Philip Marmet, Bircher Fritz, Florian Fässler, Philipp Haslebacher

Advances in Print and Media Technology (Iarigai 2011), 2011 , vol. 38, no 1, pp. 69-78

Link zur Publikation

Zusammenfassung:

This paper presents an approach to simulation aided design of inkjet systems by creating an entirely virtual
printing machine. Simulations are used in every domain of inkjet systems, from the single inkjet valves to the
print machine’s structural dynamics and the simulation of the final printout on substrates. All these simulations
are coupled with different interfaces. Therewith the printing machine with its mechanical structure, drive systems
and control algorithms can be optimized as a whole. The impact of vibrations on the final print result can be
achieved with the simulation of the printout.

A deeper understanding of the whole printing process can be achieved due to the ability to simulate the entire
inkjet system. Furthermore it is possible to solve a specific problem by simulating an individual setting, if
necessary simulations can be coupled. A global approach to simulation with well-defined interfaces and
couplings between the different engineering fields increases the interdisciplinary thinking and exchanging of
knowledge. In this way, simulations are an efficient and powerful tool to develop and optimize the complex inkjet
systems for tomorrow’s needs.

Reproducibility of DoD inkjet print-ing systems

Wissenschaftlicher Artikel

Renner Johannes, Bircher Fritz, Gert Schlegel

Advances in Print and Media Technology (Iarigai 2011), 2011 , vol. 38, no 1, pp. 79-85

Link zur Publikation

Zusammenfassung:

For inkjet printing, the maximal possible accuracy of deposition can be reached with the highest reproducibility
of printing and a correction compensating for systematic jetting faults.

In the this article the reproducibility of jetting of a set of industrial print heads in high throw distance and
high print speed operation is investigated. Based on the results, methods for the correction of reproducible jetting
errors are introduced.

2024

Multi-nozzle inkjet 3D printing with CNC motion

Konferenz ArODES

Johannes Renner, Vincent Nidegger

Proceedings of the Advanced Inkjet Technology Conference, 29-31 January 2024, Fribourg, Switzerland

PEOPLE@HES-SO Verzeichnis der Mitarbeitenden und Kompetenzen

Renner Johannes

Wissenschaftlicher Adjunkt FH

Hauptkompetenzen

Mechatronics

Electronic design

Microfluidics

Inkjet

Inkjet printhead

Matlab

Informatique

Wissenschaftlicher Adjunkt FH

PEOPLE@HES-SO
Verzeichnis der Mitarbeitenden und Kompetenzen