Inkjet Printing Inkjet Technology Fundamentals Rafi Bronstein Rafi Inkjet Printing Inkjet Technology Fundamentals Rafi Bronstein Rafi.Bronstein@HP.com Mobile: 054-531-3760

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

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

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 …

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

Course Syllabus Ink drying and curing technologies Drop-on-demand ink droplet deflection techniques Sony Kodak Others

Course Syllabus Inkjet printing systems design The printing industry Digital printing and inkjet printing

Ink Jet Printing Methods Classification

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

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

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

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

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 L λ 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

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?

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

Binary Continuous Ink Jet Deflection Plates Pressure Charge Electrodes Gutter Substrate

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

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

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

Drop Deflection L Electrostatic deflection field 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.

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

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

Key Inkjet Patents (I)

Key Inkjet Patents (II) Zoltan

Piezoelectric Materials Ceramics poling

Piezo effect and Piezoelectric Deformation - + + -

Piezoelectric Materials (I)

Piezo effect and Piezoelectric Deformation - + + -

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

Key Inkjet Patents (III)

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

Drop Ejection Process Drop Ejection Process: Push-on Draw-push

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

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

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

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

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

Key Inkjet Patents (IV) Canon 1977 - 1988

Key Inkjet Patents (V) HP

Key Inkjet Patents (VI) Fishbeck

Key Inkjet Patents (VI) Fishbeck

Key Inkjet Patents (VII)

Key Inkjet Patents (VIII) Bibl MicroFab

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

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

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

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

Effect of Drop Speed Variations

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

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

Drive Signal Form US Pat. No. 5,155,498

Various Drop Formation Wait Periods. Signal of Fig. 2. US Pat. No

Drop Flight Speed with Signal of Fig. 2. US Pat. No. 5,155,498

Another Form of Drive Signal US Pat. No. 5,155,498

Print Head Pressure Changes with Drive Signals of Figs. 6-7. US Pat. No. 5,155,498

Crosstalk Between the Channels

Drop Volume as Function of Ejection frequency US 5,274,400 (HP)

XAAR XJ500/360. VEEjet.

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