GC 4440- Current Trends - week 1 notes
GC 4440- Current Trends - week 1 notes GC 4440
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This 13 page Class Notes was uploaded by Allie S on Sunday January 17, 2016. The Class Notes belongs to GC 4440 at Clemson University taught by Dr. O'Hara in Fall 2015. Since its upload, it has received 52 views. For similar materials see Current Trends and Deviations in Graphic Communications at Clemson University.
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Date Created: 01/17/16
Inkjet and nanography Ink Jet • The ink jet process is a computer to print technology in which ink is sprayed from nozzles, which means that no image carrier is needed. Primary Technologies • Continuous inkjet • Drop-on-demand inkjet Continuous Inkjet • Only part of the continuously generated flow of small ink drops is directed onto the paper during printing in accordance with the image. • Two types of continuous inkjet: –Binary-Deflection –Multi-Deflection Binary Deflection • The drop has one of two charge states (namely uncharged for conveyance to the paper and charged for deflection in an electrical field) Binary Deflection Continuous Inkjet • Principle of a nozzle system based on Hertz technology, which enables a high frequency stream of drops (of 1 MHz or more) to be created. The pressurized liquid is pressed out of the nozzle. • The high-frequency excitation via a piezo- oscillator results in the constriction of the stream due to fluid dynamics-related effects and the separation of individual drops from the stream. Continuous Inkjet Drop Formation Binary Deflection Continuous Inkjet • The individual drops are electrically charged by an electrode in accordance with the image just before separation from the jet. • The charged drops are deflected in a subsequent electrical field (plate capacitor, deflector) and fed to a collecting device. Binary Deflection Continuous Inkjet Digital Proof System with Continuous Ink Jet Dupont Digital WaterProof Multi-Deflection Inkjet • The drops receive different charges, so that as they pass through the electric field, they are deflected in different directions and are transferred to different positions on the substrate. Multi-Deflection Continuous Ink Jet Multi-Deflection Ink Jet • The height of a line written in this way depends on the distance between the ink jet head and the paper surface. • The writing height increases as the spacing increases, although the resolution will be reduced. • The resolution in the direction of printing is determined by the speed of the substrate and the drop frequency. Multi-Deflection Ink Jet System for Addressing Drop-on-Demand Technologies • With drop-on-demand technologies, a drop is only generated if the print image requires it. Drop-on-Demand Technologies • Thermal inkjet • Piezo inkjet Thermal Inkjet • This is done by heating the liquid ink until it vaporizes, where upon a certain quantity of ink is ejected from the nozzle as a result of the pressure exerted by the vapor bubble, hence the name “bubble jet”. • No moving parts but for the ink itself. Building the bubble • An electrical pulse of 2-microseconds is applied to a resistor that raises its temperature by 100,000,000˚C per second. • This heats ink at its surface to over 300˚C in a superheated vapor explosion • Jet of ink leaves nozzle at 10-15 meters/ second Drop Generation with Thermal Inkjet Thermal Inkjet • The color printers used in desktop- publishing or in an office environment mostly use thermal ink jet systems (HP, Canon, Lexmark). About 75% of inkjet printers employ this technology • In a typical application, a separate inkjet head is used for each color. Printer Speeds • Smaller the droplet, the more it takes to cover substrate • In 2000, limited to 20 million droplets/sec. • By 2005, HP Photosmart 8250 delivers 100 million droplets/sec from 3900 nozzles integrated to single silicon chip • Number of droplets doubles every 18 months. Speed of printers held back by drying time on substrate. Pico Liter • 1 Pico Liter = 10 -1Liter, or 1/100,000,000,000 of a liter • One million droplets to cover a square inch of substrate • Printers can lay down 100 million droplets in a second. Drop-on-Demand Inkjet/ Thermal Inkjet Piezo Inkjet • The drop is generated as a result of a change of volume within the ink chamber due to piezoelectric effects, which leads to the drop of ink being ejected from the nozzle system. • Piezo technologies are used by Epson. Piezo Ink Jet • With piezo ink jet, unlike thermal ink jet, ejection of an ink drop is generated by mechanical displacement in the ink channel, and not by heating and vaporization within the ink jet system. Piezo Ink Jet • The channel walls are deformed, which produces a pumping/suction action in one channel and an ejection action in the adjacent channel. Drop-on-Demand Inkjet/ Piezo Inkjet Piezo Drop-on-Demand Inkjet System for Digital Proofing Large-Format Ink Jet Printing Systems • There are many systems available for printing large format products such as posters and large-scale advertising displays. • Widths of about 135 cm are common, though there are also systems for printing widths of about 5 to 8 m. Innovations • Greyscale printheads – Printhead can eject droplets of varying size • Fixed head inkjet – Print head is the width of the paper – Greatly enhanced print production speeds! Memjet • 8-inch wide print head • 70,400 inkjet nozzles • 60 A4 pages/minute • 51-inch, wide format 6–12 inches/ second • memjet HP T300 • 30-inch web at 400 ft./min • 10 rows of 7 4.25-inch printheads in an overlapping pattern for 29-inch print width • Pre-coating allows wide variety of substrates to be printed • T300 Video Landa Nanography • A unique digital printing platform using nano-sized color pigments • Landa video Nano-Pigments • Improved color strength (high surface area ratio, high transparency) • Water-based inks, jetted onto heated offset blanket • Very thin ink films—dry on blanket, transfer as dry polymer film for sharp dots and no absorption into substrate • Reduced drying costs due to thin film • Thin film preserves the gloss (or lack thereof) of substrate Innovative Interface • 3-meter touch screen • Operator control on either side of press • Screen lifts to allow access to press components • interface High-Speed • 13,000 sheets/hour • 660 ft./min web speed • Bridges gap between current digital and offset litho price points • Strategic Partnerships—manroland, Komori and Heidelberg have licensing agreements with Landa to incorporate digital solutions to their customers Seybold Report Digital Projections • Digital printing will grow to nearly 30% of all print production globally from 2005-2015 • Half of all packaging and label printing to be done digitally. - Frank Romano
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