Continuous Inkjet Research Articles

IMG-01 DEVELOPMENT OF NEW NOZZLE FOR CONTINUOUS INKJET PRINTERS(Imaging and Printing Technologies I,Technical Program of Oral Presentations)

IMG-01 DEVELOPMENT OF NEW NOZZLE FOR CONTINUOUS INKJET PRINTERS(Imaging and Printing Technologies I,Technical Program of Oral Presentations)

Study on the equal pressure distributed hydrokinetics of the supplying ink for continuous inkjet printing system

Supplying uniform pressure ink in continuous inkjet printing system is the key factor for forming uniform and constant speed ink droplets, it is related to the final imaging effects, this research has seldom been reported in these years. This paper studied on the hydrokinetics and uniform distributed mechanics of supplying ink pressure for the continuous inkjet printing system based on the theoretical calculation, CFD (Computational Fluid Dynamics) and the advanced testing equipment. According to the analysis of laminar flow characteristics and the other jetting flow dynamics factors of the ink, a new type of equipment for supplying ink was designed in this paper, including the structure of the transition pipe and nozzle. The shape of the equipment is rectangular, where the flow section is gradually tapered. This supplying ink equipment can make the ink droplets distribute under the equal pressure on the cross direction. This study educed the optimally hydrokinetics parameters for the continuous inkjet printing. The experiments showed that this new supplying ink equipment could make the ink droplets distribute under the equal pressure and uniform velocity on the cross direction, so it greatly improved the imaging effects for the continuous inkjet printing system.

Electrostatic deflection of charged droplets with asymmetrical injection: unexpected optimal design

Continuous inkjet printers selectively direct charged droplets to the target medium or into a gutter for recycling by deflecting the stream with an electric field. While this is a well-known and mature technology, it sometimes is useful to revisit the underlying science. We have done this in the similar case of electron beam deflection and results are counterintuitive. Traditionally, to avoid the edge effects at the entrance as much as possible, charged streams have been injected symmetrically into the gap between two oppositely charged conductive plates. However we found that optimal deflection occurs when the stream is injected about 1/3 of the way toward the attracting plate. The stream can be quite wide - about 1/3 of the gap is acceptable. Under these conditions, deflection angles can be much larger than the 10 degrees or so previously considered maximum. For example it is possible to cleanly deflect a charged stream by up to 50 degrees or so. Optimal asymmetrical injection allows the stream to follow equipotentials so that the deflection force is normal to the trajectory and relatively uniform over the entire droplet avoiding break-up. There may be useful design advantages using optimal offset deflection technology in continuous inkjet printing.

Continuous Inkjet Drop Generators Fabricated From Plastic Substrates

Fabrication of a functional continuous inkjet drop generator from plastic substrates by exclusively using micro- electromechanical systems (MEMS) processing steps is reported. Polyimide and poly(ethylene naphthalate) sheets that are laminated to a silicon carrier wafer are investigated as the drop generator substrate, and the MEMS processing methods used and associated challenges are discussed in detail. Successful generation of drops in a 600-nozzles-per-inch array that are as small as 2.4 pL in volume (16.5 mum in diameter) at drop velocities of 15.5 m/s is realized with these devices.

Coupled field analysis of a piezoelectric bimorph disc in a direct write process

This paper investigates the behavior of a piezoelectric (PZT) bimorph disc within a Direct Write Process. A modified Continuous Inkjet Print (CIJ) method is utilized to selectively deposit a variety of conductive nano particulate materials for building functionally gradient materials (FGM). The spatial and temporal complexity of the novel CIJ based microfabrication process necessitates a computational solution to complement its experimental development. Static and modal coupled field finite element analyses were conducted for determining the operating frequency range of the PZT disc within a CIJ print head. The transient behavior of the PZT disc was subsequently analyzed in a conductive ink environment using a fluid–structure interaction (FSI) algorithm. Finally, parametric studies were conducted to generate empirical expression and to determine the relative importance that the density and kinematic viscosity of fluids had on the excitation behavior of the piezoelectric disc.

Ink Concentration Control System for Continuous Ink Jet Printers

We developed an ink concentration control system for continuous ink jet printers by using a unique inline viscometer. The ink concentration is constantly monitored by measuring the ink viscosity and temperature, and the control system can always accurately maintain the ink concentration by adjusting the ratio of solvent in the ink. The viscometer consists of a plunger moving vertically in a cylinder, a solenoid for raising the plunger by electromagnetic force, and a proximity sensor for detecting the position of the plunger. The viscosity can be calculated automatically from the free-fall time of the plunger from the top to the bottom of the cylinder. The viscometer can measure it rapidly, precisely, and automatically. Also, the reliability of the viscometer can be improved by repeatedly measuring the fall time of the plunger over a short period. Finally, our system can control the ink concentration within ±2% of the initial ink concentration.

Formulation and processing of novel conductive solution inks in continuous inkjet printing of 3-D electric circuits

One of the greatest challenges for the inkjet printing electrical circuits is formulation and processing of conductive inks. In the present investigation, two different formulations of particle-free conductive solutions are introduced that are low in cost, easy to deposit, and possess good electrical properties. A novel aqueous solution consisting of silver nitrate and additives is initially described. This solution demonstrates excellent adherence to glass and polymers and has an electrical resistivity only 2.9 times that of bulk silver after curing. A metallo-organic decomposition (MOD) ink is subsequently introduced. This ink produces a close-packed silver crystal microstructure after low-temperature thermolysis and subsequent high-temperature annealing. The electrical conductance of the final consolidated trace produced with the MOD ink is very close to bulk silver. In addition, the traces produced with the MOD material exhibit excellent wear and fracture resistance. When utilized in a specialized continuous inkjet (CIJ) printing technology system, both particle-free solution inks are able to produce conductive traces in three dimensions. The importance of three-dimensional (3-D) printing of conductive traces is finally discussed in relation to the broad range of applications in the freeform fabrication industry.

A Continuous Ink Jet Device on the Basis of Electrohydrodynamic Mechanism

A new type of ink jet system is proposed on the basis of electrohydrodynamic (EHD) effect. On the application of high DC electric fields to some insulating fluids, a fluid jet with a velocity of about 1 ms−1 is generated from the positive electrode as a bulk flow. By controlling the EHD flow to issue across the free surface, the ink jet device is developed, of which the nozzle unit is simply composed of a needle electrode and capillary. When the fluids are subjected to high electric fields, the ink jet is generated above a critical threshold and the height increases with increasing voltage. The critical voltage strongly depends on the nozzle geometry. The height of ink jet at high voltages increases with decreasing viscosity and conductivity of fluids. The performance of ink jet based on the EHD jet can be improved by a combination of designs of nozzle geometry and material functions.

Ink Concentration Control System for Continuous Ink Jet Printers

Continuous ink jet printers have been widely used for industrial marking such things as bar codes and product dates. An electronically controlled drop to ensure accurate printing positioning carries out the printing. An ink concentration control system has been developed to improve stability of the drop formation and printing quality. The key features are a unique in-line viscometer and an ink concentration control system. The ink concentration is constantly monitored by measuring ink viscosity and temperature, and the ink concentration control system can always maintain the concentration accurately by adjusting the ratio of solvent in the ink. The viscometer consists of a plunger moving vertically in a cylinder, a solenoid to raise the plunger by electromagnetic force and a proximity sensor to detect the position of the plunger. The ink viscosity can be calculated by the fall time of the plunger from the top to the bottom in the cylinder. The viscometer can measure it rapidly (in a few seconds), precisely, and automatically. Also, the reliability of the viscometer can be improved by measuring the fall time of the plunger repeatedly in a short period.

1516 インクジェットプリンターの液滴形成に関する数値解析

The principle of continuous ink jet printer is to run ink droplets into printing paper. It is difficult, however, to form stable ink droplets, and moreover, unstable ink droplets cause disorder of printing performance. The parameters such as shape of nozzle, surface tension and pressure influence the shape of ink droplets. The purposes of this research are both to analyze ink droplet formation and to solve control factor of split process from ink column to ink droplet by using Computational Fluid Dynamics (CFD).

Scitex Digital Printing and Production Digital Technology

Scitex Digital Printing (SDP), Inc. manufactures high speed digital printers. Recent advancements in technology from SDP have defined a new category of print, Business Color™.Markets and applications of Business Color include Direct Mail, Transactional Documents and Book Printing. Each of these applications have unique opportunities for Business Color printing including high variability of data, elimination of pre-print, and fast job changeover.SDP products such as the Business Color Press with VersaMark® printheads are designed to provide low per page costs at high print volumes of 100% variable documents. SDP has developed modular Business Color printing systems to allow printing businesses to start with monochrome printing and transition their print offerings to include spot and process color. Product modularity also allows press capacity and versatility to increase with increased demand.VersaMark printheads use continuous inkjet technology to print water based inks at 300 x 300 or 300 x 600 dpi. Printheads are 9” wide and can print up to 500 fpm. Paper treatment and coating technologies contribute to improving print quality; a variety of software technologies enable customers to produce documents with Business Color technology.

A study on the drop formation of continuous liquid jet by an electrical method

Acceptable satellite conditions and allowable switching regions of the charging control signal in continuous inkjet printing are studied. The charging control signal can be switched within the phase interval corresponding to the satellite interaction time defined by Pimbley and Lee except for the forbidden region of the satellite droplet in rear-merging satellites, and within the phase interval except for the forbidden region defined by Hertz and Samuelsson in forward-merging and nonsatellites. An electrical method for the investigation of the drop formation using a phase search pulse is presented. It is confirmed that the phases of drop formations and the forbidden regions predicted by the electrical measurement well coincide with the result of optical observation.

Lightfastness Studies of Water-based Inkjet Inks on Coated and Uncoated Papers

Instrumental color (i.e. L*A*B*) and optical density measurements were performed on coated and uncoated papers printed with water based inkjet inks using continuous binary array inkjet equipment. Lightfastness tests were performed in a QUV test chamber with Cool White Fluorescent lamps, Q-Sun Xenon Arc Test Chamber with a Window Glass Filter, and under glass at a Florida outdoor benchmark location (Q-Lab Weathering Research Service). These results were compared with two indoor exposure locations. Rank order was used to show good correlation between the various exposure methods. The results of this study generated data indicating that the lightfastness of water-based inkjet inks can be complex and dictated by the type of coated or uncoated paper used. This study also shows that inks printed on coated substrates are more susceptible to UV degradation than those printed on a bond or uncoated substrate. The development of a light stability test protocol is intended to simulate the conditions of the actual service environment. Meaningful data can be produced to better evaluate the “archivability” or predict durability of inkjet inks and substrates.

Novel Silicon-Based Continuous Inkjet Printhead Employing Asymmetric Heating Deflection Means

In this paper, a novel continuous inkjet technology will be presented. The technology presented uses a pulsed application of asymmetric heat to a pressurized stream of ink emitted from a nozzle both to break up the stream into regularly sized printing drops and to deflect the drops onto a receiver while allowing the non-printing drops to be captured. Depending on the nozzle geometry, fluid properties and applied pressure arrays of small drop volumes (3 picoliters) can be jetted and deflected at high velocity (10 m/s). The printhead, fabricated in silicon, is produced by MEMS processing techniques that are CMOS compatible, allowing for direct integration of circuitry. The basic device geometry and operation will be described including some experimental results.

Continuous Flow High Speed Ink Jet Digital Color Printer

Continuous Flow High Speed Ink Jet Digital Color Printer

Overview of Industrial Digital Printing

There are many different methods by which to apply marks and codes either directly on product packages (primary packaging) or in cartons or cases of that product (secondary packaging). The following is an overview of different types of digital printing technologies used for industrial marking applications. The paper will explain the use of piezo drop-on-demand (DOD) ink jet with both phase change and liquid inks. Other ink containing systems that will be reviewed include continuous ink jet, valve jet, and thermal transfer. In addition, one non-ink containing digital marking method – a laser printing system- will also be discussed. The end user's choice of digital printing technology is determined by the application requirements of the product being marked, including: the size and shape of the mark or code, print speed, adhesion requirements, substrate, environmental requirements, and cost per print. The benefits and disadvantages of each technology will be discussed in relationship to these requirements.

Performance of Fluids in a Silicon-based Continuous Inkjet Printhead Using Asymmetric Heating

In this paper, we study the performance of a variety of fluids in a new continuous inkjet printhead that employs asymmetrical heating of a jet of fluid to cause it to deflect. The basic design and operation of the printhead is described in a companion paper in this same conference. We focus mainly on the performance of non-aqueous fluids, with some discussion of the performance of water mixed with common humectants.By examining the performance of a variety of fluids, we try to understand the mechanism causing the deflection. We compare our experimental results to the output of a Computational Fluid Dynamics (CFD) model of the device that is solved using finite difference Volume of Fluid (VOF) code. With our choice of fluids, we focus on the role played by the temperature dependence of the fluid viscosity on magnitude of the jet deflection.

Effect of Drop Size on the Print Quality in Continuous Ink Jet Printing

Very little attention has been paid in the literature to the impact of the drop size on the dynamics of spreading and on the final dot quality with different paper grades. In this study, the development of the image properties was observed on a time scale of a few milliseconds and upwards, by using a special high speed imaging environment and continuous ink jet (CIJ) printers, with different nozzle sizes but similar water based ink compositions. The results clearly show that there is a strong paper dependent affiliation between the size of the ink jet drop and the high-speed dynamic phenomenon of dot spreading and drying. With coated paper grades, the interrelation between the drop size and the magnitude of the surface structure was found important, compared with the final shape of the dot. With uncoated papers, the growth of the dot is dependent on the size of the drop. The final intensity of the print was found to be the outcome of the characteristics of the ink and the absorption properties of the paper.

Significance of Paper Properties on Print Quality in Continuous Ink Jet Printing

In this article, we discuss the relationship between a high-speed continuous ink jet system and the printing substrate. Nonabsorbent materials, with different surface topographies were used to evaluate the importance of the droplet impact and spreading without capillary penetration. Commercial papers were also used to evaluate the potential of the existing grades, and to find their essential performance parameters. A laboratory scale testing environment was used for the high-speed imaging of ink jet drops. The impact, spreading, absorption, and drying of the ink droplets on the samples can be observed and analyzed in this testing environment on the time scale of microseconds up to several minutes. The image technical performance of the samples was measured with an image analysis system which was specially designed for the analysis of print quality with non-impact printing techniques.

Development and Characterization of Silicon Micromachined Nozzle Units for Continuous Ink Jet Printers

The design of a silicon micromachined nozzle unit to be used in continuous ink jet printers is suggested and characterized. A truncated pyramid shaped nozzle geometry was obtained by anisotropic etching and p–n junction etch stop processing of <100> silicon wafers. The pyramid shaped nozzle, with the exit on the front side of the silicon die, has a square orifice, which connects to the center of a 10 mm × 0.7 mm × 30 μm (L × W × D) channel situated on the backside of the die. The channel was sealed by an anodically bonded glass lid, which provided in- and outlet via drilled holes. The flow through option, given by the connection of the in- and outlet to each end of the channel, facilitates cleaning at the end of the manufacturing process as well as de-clogging of the nozzle during operation. The stimulation of the jet, to attain constant droplet size and distance between droplets, was achieved with the aid of a piezoelectric element that was glued to the glass lid on the backside of the nozzle unit. The piezoelectric element was positioned adjacent to the orifice of the nozzle to secure a good acoustic coupling to the jet. A jet emerged from a nozzle (10 μm × 10 μm orifice) with a velocity of 50 m/s at a flow rate of 0.22 ml/min when a pressure of 10 bar was used to force the ink through the nozzle unit. The droplet flight stability was characterized by an in-house developed optical measurement system. The results showed that the nozzle unit generated droplets with high droplet flight stability (less than 15° standard deviation in droplet period width measured at 7 mm from the orifice) in a large stimulation frequency region around the desired frequency of 1 MHz.