Waveform and Drop Optimization
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Inkjet printhead waveform optimization process and technique. The importance of Ink and printhead waveform explained and along with tools technique and process. Allows robust inkjet printer systems development.
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Waveform and Drop Optimization
- 1. Tech Talk Waveform and Drop Optimization September 7-8, 2016 Renaissance Schaumburg Convention Center Hotel, Schaumburg (Chicago), Illinois USA
- 2. • Ink and characteristics • Printhead architectures and commonality • Single drop optimization • Measurement Equipment and Drop Visualization • Multi Drop and Gray Scale • Velocity Optimization • Frequency Response What are we talking about?
- 4. Ink and Fluid Carriers Solvent UV Cure H2O Melt Dyes and Pigments Create Colors
- 5. Ink Physical Properties Static – easier to measure Viscosity Surface Tension Contact angle Temperature Density – specific gravity Filtration Time Conductivity Particle Size Dynamic – difficult to measure Viscosity vs. shear rate Dynamic Surface Tension Elasticity Thermal hysteresis (viscosity) Dynamic Characteristics are unique to printhead
- 7. Shared Wall – Shear Mode D15
- 10. Nozzle, Chamber, Actuator • Basic geometries are alike: • Ink manifold to deliver ink • Chamber • Actuator – changes volume of chamber • Nozzle - outputs drop and refills meniscus from chamber • Follow acoustic mode theory and modelling • Pressure waves travel at speed-of-sound • Capillary pumping action
- 11. Chamber Pressure and Settling • Electric field causes piezo to change shape • Piezo quickly changes chamber volume • Creates a pressure wave in the chamber • Usually settles within 100 microseconds Note: Plot is from a computer model Helmholtz Resonance
- 13. 1. Single Drop Pulse Width Optimize 2. Velocity Adjustment – adjust voltage for 5-9 meters per second 3. Plot single drop frequency response – velocity and size 4. Optimize double pulse for two drop 5. Plot 2-drop frequency response 6. Repeat for 3-drop, 4-drop, etc. Waveform Optimization Steps
- 14. Action! • Piezo increases the volume in chamber • The meniscus pulls back from the nozzle & ink flows in from manifold • Pressure wave moves through chamber at the speed-of-sound • Wave crashes into wall of chamber and reverses direction • At the precise time, the piezo collapses creating a second wave, adding to the first • A drop is ejected
- 15. Optimum Pulse Width speed against pulse sustain time in useconds 3 4 5 6 7 8 4 6 8 10 12 14 16
- 16. Adjust for Drop Velocity • Higher Voltage increases Drop Velocity and Size • Optimize velocity between 5-9 meters per second • Good drop formation and no satellites
- 17. Optimization and Print Gap -Printhead 1 -5mm Motion Air currents Larger Gap • Higher Velocity • Larger Drops e = ½ mv2 Smaller Gaps • Lower Velocity • Smaller Drops 5 – 9 meters per second
- 18. Uniform Drop
- 20. Drop Visualization System Meteor Drop Optimization Software Meteor Waveform Editor
- 21. Drop Tuner Waveform Editor Print Head Configuration and Driver Tools
- 25. Satellites are not good
- 26. DROP SIZE(S)
- 27. Drop Size – Multi-Drop – Grayscale -2 • Multi-Drop Technology • Gray Scale
- 28. Chamber Pressure, Settling & multi-Drop • Electric field causes piezo to change shape • Piezo quickly changes chamber volume • Creates a pressure wave in the chamber • Usually settles within 100 microseconds Subsequent drops are ejected when chamber is very active
- 31. Velocity vs Voltage Drop Size vs Voltage
- 33. Frequency versus Drop Size
- 34. NOW DO IT ALL FOR EACH COLOR IN YOUR SYSTEM
- 35. Drive Voltage vs. Velocity
- 36. Drop Volume vs. Drive Voltage
- 37. Drop Velocity vs. Frequency
- 38. Drop Volume vs. Frequency
- 39. • Consistent Drop Placement • Consistent Drop Volume • Improved Color Management • Robust jetting with high operating margins • Longer time between maintenance cycles • Makes the formulator look good Optimizing Jetting & Waveform Achieves That’s what I’m talking about!
- 40. Guttenberg Press ~1439 “Hey, Johannes, You know…this is all going to be digital some day” - Guttenberg Assistant
- 41. Thank You TTP Meteor Ltd. Melbourn, Herts. SG8 6EE. UK Mike Raymond Technical Sales – Business Development ttpmeteor, Philadelphia Office, USA +1 302 514 7775 Mike.Raymond@ttpmeteor.com -
- 42. Sources • http://www.nt.ntnu.no/users/skoge/prost/proceedings/ifac11- proceedings/data/html/papers/1129.pdf • http://seeen.spidergraphics.com/cnf5/doc/Ink%20formulation%20t utorial.pdf • Manipulating drop performance in piezo electric inkjet • Herman Wijshoff, Océ-Technologies B.V., Venlo, the Netherlands • http://www.slideshare.net/MikeRaymond/edit_my_uploads Manipulating drop performance in piezo electric inkjet Herman Wijshoff, Océ-Technologies B.V., Venlo, the Netherlands
Editor's Notes
- An ink needs to be tuned for the target printhead The best operating points need to be chosen, not the fastest You may have a really good ink but you need to thoroughly characterize the ink using a drop watcher
- Ink is central Ink must perform both on the media and in the printhead The characteristics required for media conflict with the characteristics required for jetting quality and reliability Dry quickly on media but not dry in head Flow in printhead but not penetrate media Adhere to media ewith good fastenss but do not harden on printhead
- Many differing types of inks All are either dye based or pigment based All act different in the printhead
- Printhead specificiaons are based on a specific fluid used for manufacturing test. It is just a target. The characteristics of your ink can be quite different. Tuning is required for optimum jetting; empirical methods are employed
- Ink Chamber is is made form the piezo
- All inkjet architecture are common, each has Nozzlw Ink chamber Acturator – change volume of chamber Restriictor – so ink doesn't flow back to manifold Dneser ink has faster speed of sound
- The piezo changes shape when a voltage is applied This changes the volume of the chamber and creates a pressure wave in the fluid Follows a natural settling before returning to rest Curves are generated by modeling. Actual measurements in the chanber are not practical.
- Adjust for optimum single pulse waveform Adjust velocity – below 5 is too slow for good control – above 9 usually create drop breakup Plot frequency response for drop velocity and drop size
- You have to feel the energy and emotion Pretend I’m the set director and you’re the actor
- Change the pulse width and measure drop velocity Perform at a low frequency to avoid settling effects You should see a nice drio formation
- Adjust voltage for DV between 5-9 m/s
- Hardware and software Drive electronics, camera , strobe Drop Optimization software to adust drop rates and patterns Waveform editor Image anaysis
- And now a word form our sponsor Seriouslt, Meteor has htes units in oeration globally Uses the same drive electronics and software as in the printer
- Contrary to popular belief printheads really only have a single drop size. This is called the native drop. Larger drop sizes are created by quickly jetting more drops Complete drop forms before hitting substrate
- The piezo changes shape when a voltage is applied This changes the volume of the chamber and creates a pressure wave in the fluid Follows a natural settling before returning to rest Curves are generated by modeling. Actual measurements in the chanber are not practical.
- The settling waveform affects the subsequest drops
- Now the ink is characteriszed System operating parameters are set for best quality and performance And the output is perfected – Yah, that’s what I’
- ALMOST 500 YEARS FOR THE DIGITAL TRANSFORMATION Just getting started