Inkjet Technology and Inkjet Printing

1. Inkjet PrintingInkjet Technology FundamentalsRafi BronsteinRafi.Bronstein@HP.comMobile: 054-531-3760

2. Inkjet Technology and Inkjet Printing Rafi Bronstein Rafi.Bronstein@HP.com 2008

3. Course Syllabus • Inkjet technology history and fundamentals • Types on inkjet technologies • History of inkjet printing • Industrial applications • Most successful inkjet printing technologies • Continuous inkjet technologies • Drop-on-Demand inkjet technologies • Thermal inkjet • Piezo inkjet • Novel ink ejection technologies

4. Course Syllabus • Print head fabrication materials and processes • Print head designs and key vendors • Thermal inkjet • Piezo inkjet • Direct ink ejection • Piezo print head design parameters • Frequency, crosstalk, drop placement accuracy …

5. Course Syllabus • Printing inks and their composition • Ink types and properties • Inkjet printing substrates • Paper and coatings • Non-paper media • Basics of radiometry and basic color theory • Radiometry • Color systems and color management

6. Course Syllabus • Ink drying and curing technologies • Drying • Curing • Drop-on-demand ink droplet deflection techniques • Sony • Kodak • Others

7. Course Syllabus • Inkjet printing systems design • The printing industry • Digital printing and inkjet printing

8. Ink Jet Printing Methods Classification

9. Ink Jet Printing History (I) • 1878 – Lord Rayleigh • 1929 – Hansell, USP #1,941,001 Electrostatic Deflection Recorder • 1938 – Genschmer, USP #2,151,683 Spark Type Ink Ejector • 1946 – Hansell, USP #2,512,743 Jet Sprayer Actuated by Piezoelectric • 1958 – Winston, USP #3,060,429 Drop Jetting by Electrostatic Attraction • 1962 – Naiman, USP #3,179,042 Sudden Steam Printer • 1964 – Sweet, USP #3,596,275 Continuous Inkjet Printing • 1966 – Hertz et al. USP #3,416,153 Modulation by Electrostatic Dispersion • 1967 – Sweet et al. USP #3,373,437 Array of Continuous Ink Jets

10. Ink Jet Printing History (II) • 1970 – Kyser et al. USP #3,946,398 Drop-on-Demand Bend Mode Inkjet Apparatus • 1970 – Zoltan, USP #3,683,212 Squeeze Tube Piezoelectric Inkjet • 1972 - Stemme – USP #3,747,120 Bend Mode with Metal Diaphragm • 1979 – Endo et al. GBP #2,007,162 Electrothermal Transducer (Bubble jet) • 1982 – Howkins, USP #4,459,601 Piezoelectric Push Mode • 1982 – Vaught et al. USP #4,490,728 Electrothermal Transducer (Thermal Inkjet) • 1979 - 1985 – Fishbeck, USP #4,032,929 - USP #4,584,590 Shear Mode Transducer • 1989 – Bartky et al. USP #4,879,568 Droplet Deposition Apparatus

11. Ink Jet Printing • Continuous • Drop-On-Demand (DOD) • Piezoelectric • Thermal (Bubble) inkjet • Others

12. Lord Rayleigh – Drop Formation Law (I) d V P λ L • Emerging from an orifice liquid jet breaks-up into droplets. Because of the surface tension: • Droplets have random size • Droplets have random spacing

13. Lord Rayleigh – Drop Formation Law (II) L = K*ln(d/2α0)V(ρd3/σ)0.5 λ = 4.51d; fs = V/4.51d d V P λ L α0 – the initial disturbance ρ - the density of the fluid σ – the surface tension of the fluid L – break-up length fs– the frequency of spontaneous drop formation λ – wave length

14. Drop Formation – Ink Jet Basics • Can the drop size be controlled? • Can the spatial spacing of the drops be controlled? • Can the break-up length be controlled? • What would be the drop selection method?

15. Sweet-type Continuous Ink Jet Deflection Plates Pressure Charge Electrodes Gutter Substrate

16. Binary Continuous Ink Jet Deflection Plates Pressure Charge Electrodes Gutter Substrate

17. Is It So Simple? Change in Viscosity with pressure Density Viscosity

18. Drop Charging Methods Plate Charging (Sweet) Tunnel Charging (S. Bahl?) Plate Face Charging (S. Bahl?)

19. Drop Charge Requirements and Limits Drop charge limits: (Rayleigh limit) Q = Sq.Rt.(64π2ε0r3σ); ε – free space permittivity σ – surface tension r – drop radius • Electric field between the • electrodes • Conductive ink • Inductive charging • Charging voltage • Charging electrode shape • Jet break-up parameters

20. Drop Deflection Deflection Plates Pressure L Charge Electrodes Gutter Substrate • Electrostatic deflection field • Aerodynamic drag force • Neighboring drops repulsion Deflection on paper X = (qE/mV2)L(D-(L/2)) Where q, m, and V are charge, mass and drop velocity. L- length of the deflection plate. D – distance from the plate edge to the substrate.

21. Density modulation (W. Lloyd & H. Taub) Substrate Substrate Mask Mask Charge electrode Substrate Charge electrode Nozzle Mask V V Drop dispersion on mask/aperture Charge electrode V

22. Density modulation (H. Hertz) Deflection Plates Pressure Charge Electrodes Gutter Substrate • Variable number of drops per pixel

23. Key Inkjet Patents (I)

24. Key Inkjet Patents (II) Zoltan

25. Piezoelectric Materials Ceramics poling

26. Piezo effect and Piezoelectric Deformation - 0 + + 0 -

27. Piezoelectric Materials (I)

28. Piezo effect and Piezoelectric Deformation 0 - + + 0 -

29. Elements of Piezoelectric Inkjet technology Source: S. Negro and E. Smouse, Hewlett-Packard Inkjet Printing Technology: The State of the Art, 1999

30. Key Inkjet Patents (III)

31. Drop-on-Demand Piezoelectric Inkjet Piezoceramic Membrane Manifold Pressure chamber Inlet Orifice plate Orifice

32. Drop Ejection Process • Drop Ejection Process: • Push-on • Draw-push

33. Forces Acting on Ink Drop VCarriage • Drop charge • Electric field of the substrate • Ejection frequency • Nozzle plate state • … VDrop Windspeed H Drug d daero

34. Elements of Thermal Inkjet (print head structure) Source: S. Negro and E. Smouse, Hewlett-Packard Inkjet Printing Technology: The State of the Art, 1999

35. Elements of Thermal Inkjet (how it works) Source: S. Negro and E. Smouse, Hewlett-Packard Inkjet Printing Technology: The State of the Art, 1999

36. Elements of Thermal Inkjet (drop ejection process) Source: S. Negro and E. Smouse, Hewlett-Packard Inkjet Printing Technology: The State of the Art, 1999

37. Thermal Inkjet Configurations Source: S. Negro and E. Smouse, Hewlett-Packard Inkjet Printing Technology: The State of the Art, 1999

38. Key Inkjet Patents (IV) Canon 1977 - 1988

39. Key Inkjet Patents (V) HP

40. Key Inkjet Patents (VI) Fishbeck

41. Key Inkjet Patents (VI) Fishbeck

42. Key Inkjet Patents (VII)

43. Key Inkjet Patents (VIII) Bibl MicroFab

44. Key Print Head Characteristics • Resolution • Drop ejection frequency • Drop volume • Drop speed • Array pitch • Drop speed uniformity across the array • Operating temperature range • Physical size and weight

45. Print Head Resolution – Print Resolution • Pitch between two neighboring nozzles • Actual resolution • Linear array • Two dimensional array • Electronic resolution • Minimal printable distance between two successive dots

46. Drop Ejection Frequency • Minimal time between two successive drop ejection cycles • System resonance • Fixed frequency • Plurality of ink ejection frequencies • Defines throughput

47. Drop Speed • The speed at which the drop leaves the orifice • Aerodynamic resistance • Multi drop grey scale printing • Ejection force • Ink parameters • Defines printing speed • Drop speed variations

48. Effect of Drop Speed Variations

49. Drop Volume • The volume of the ejected drop (picoliter; nanogram) • Drop volume variation • Drop volume variation as function of ejection frequency • Defines amount of ink on the substrate and accordingly image color gamut

50. Tektronix Print head US Pat. No. 5,155,498