インクジェット記録の高画質化と高速化

Acoustic Inkjet Printing (AIP) is suitable for jetting a small drop when compared with other available methods because the drop size depends not on the nozzle area but on the frequency of acoustic beam that enables ejection from free liquid surface.For inkjet printing, drop modulation is the major technology being effective to realize both high image quality and high print speed. In the previous reports regarding AIP, multiple droplets were fired at the same location on paper for gray scale of image.1 This method could enhance image quality at the sacrifice of print speed.Here we propose a method of drop size modulation in AIP to achieve both high image quality and high print speed. It has been proved that the drop size is modulated by a second harmonic on fresnel lens without changing the liquid level and other dimensions. This report also shows that calculations and experiments ascertained drop modulation by the second harmonic.

In order to rival the quality of silver halide photographs, digital printing systems need to satisfy issues of high print quality as well as image stability. Our research and development efforts have focused on thermal dye transfer and ink jet printing systems, with extraordinarily good results in each system.Discussion will focus on the chelate reaction between dye molecules and metal ions in the thermal dye transfer printing system, which has greatly improved the image stability issues, well in excess of original targets.As for ink jet printing, attention was paid to improving the print quality. These efforts led to the world's first production of micro porous printing media with an RC-paper base. The combination of the printing media and dye inks brings the expected print quality together with other features such as quick drying cased by high ink-absorption speed, resistance to water.Work on improving image stability in ink jet systems will also be discussed.

Inkjet printers are the most commonly owned printers because of their low cost, high printing quality, and ease of use. The four major inkjet printer manufacturers are Canon, Epson, Hewlett-Packard, and Lexmark. The inkjet printer business has adopted the “bait and hook” business strategy, offering the basic printer product at a low (possibly below cost) price while charging a higher price for their proprietary ink cartridges. Table 1 shows the pricing of different ink jet printers and ink cartridges from the four major manufacturers. With technology advancement, inkjet printers have improved in quality and reduced in price. As seen in Table 1, the printer (being more technologically complex to make than the ink cartridge) is relatively inexpensive. This is a business tactic used to attract more people to buy the printer. The manufacturers are trying to improve their overall profit margin by charging higher prices than they would have normally done for their proprietary ink cartridges. The setting of printer and cartridge prices must therefore be closely linked and studied, as they affect the overall profitability and survival of the printer company. According to LYRA research (http://www.lyra. com/), the total revenue from inkjet printers and ink cartridges exceeded $45 billion in 2006. I.T. Strategies (http://www.it-strategies.com/) expects the inkjet printer market to grow to $58 billion by 2009. It expects the largest segment of the revenue to come from ink cartridges, with the revenue rising from $20 billion in 2004 to $33 billion in 2009. The printer business is very lucrative, and it is crucial for the survival of a company that produces printers to use a “good and flexible” business decision tool to price the printer and ink cartridges. Allan Table 1 Sample Inkjet Printer and Cartridge Prices

Interactions of ink colourants with chemically modified paper surfaces concerning inkjet print improvement

Environmental-friendly plastics (EFP) are new alternatives of fossil-based plastics. The EFP family mainly constitutes bio-plastics/bio-attributed plastics and post-consumer recycled plastics (PCR). EFP contributes around 10% of total plastics production in global plastic production. Presently EFP are mostly used in grocery bags, bin liners, compostable garbage bags and single-use plastics with single or spot color printing. Multi-color printing can add value or open new horizons for these materials, leading to high-value applications. It can also be used for high-speed printing or flexible packaging applications. Plastics available in this category come from both fossil-based and bio-based sources. Fossil-based bioplastics has almost similar degree of print suitability but materials coming from bio-based sources are yet to be explored for print suitability, especially with high-speed multi-color printing machines. Flexographic printing is known for high-quality and high-speed printing on different substrates, including paper, conventional plastics and fossil-based bio-plastics. The advantage of having a common impression cylinder (CIC) arrangement and the requirement of less pressure during printing makes it suitable for consideration for printing on EFP. Hence, this study, print suitability of EFP using flexography printing, is an attempt to explore the mutual compatibility of these substrates and printing process, which will prove to be a boon in the future for establishing EFP as a strong substitute for replacing conventional plastics.

A thermal ink jet (TIJ) printhead suitable for high speed and high quality printing has been developed. The printhead has been fabricated by dicing the bonded wafer, which consists of a bubble generating heater plate and a Si channel plate. The Si channel plate consists of an ink chamber and an ink inlet formed by KOH etching, and a nozzle formed by ICP RIE. The nozzle formed by ICP RIE has squeezed structures, which contribute to high-energy efficiency of drop ejector and therefore successful ejection of small ink drop. These two wafers are directly bonded by using electrostatic bonding of full-cured polyimide to Si. With these technologies, we have fabricated a 1 long printhead with 832 nozzles having 800 dots per inch (dpi) resolution and a 4 pl. ink drop volume.

The most significant issues in printable electronics fabrication are the printing quality and efficiency delivered by drop-on-demand (DOD) industrial inkjet printhead. Aiming to characterize the nonlinear behaviors of piezoelectric inkjet printhead, the dynamic lumped element model (DLEM) is proposed to cast the original LEM into a time-varying and nonlinear fashion. At the same time , the PSO-based optimization for paramenters is incorporated in DLEM. Due to new characteristics, DLEM can accurately simulate the inkjet-printed nanosilver droplet formation process and effectively predicate optimal combinations of high-frequency driving waveform with high printing quality. From extensive experimental studies, the effectiveness and efficiency of the proposed DLEM is validated.

Performance Improvement of Professional Printing Systems: from theory to practice Markets demand continuously for higher quality, higher speed, and more energy-efficient professional printers. In this thesis, control strategies have been developed to improve the performance of both professional inkjet and laser printers. Drop-on-Demand (DoD) inkjet printing is considered as one of the most promising printing technologies. It offers several advantages including high speed, quiet operation, and compatibility with a variety of printing media. Nowadays, it has been used as low-cost and efficient manufacturing technology in a wide variety of markets. Although the performance requirements, which are imposed by the current applications, are tight, the future performance requirements are expected to be even more challenging. Several requirements are related to the jetted drop properties, namely, drop velocity, drop volume, drop velocity consistency, productivity, and reliability. Meeting the performance requirements is restricted by several operational issues that are associated with the design and operation of inkjet printheads. Major issues that are usually encountered are residual vibrations in and crosstalk among ink channels. This results in a poor printing quality for high-speed printing. Given any arbitrary bitmap, the main objective is to design actuation pulses such that variations in the velocity and volume of the jetted drops are minimized. Several model-based feedfoward control techniques using an existing model are implemented to generate appropriate input pulses for the printhead. Although the implementation of the model-based techniques shows a considerable improvement of the printhead performance compared with the current performance, further improvements are still necessary. We observe that besides the pulse shape the state of the ink surface at the nozzle plate (speed, position) at the start of the pulse influences the drop velocity considerably. This state at firing depends also on previous pixels in the bitmap of the image. Consequently, any pulse design has to guarantee almost the same initial state when firing a drop. Based on these facts, a model-free optimization scheme is developed to minimize the drop velocity variations taking into account the bitmap information. Experimental results show the effectiveness of the optimized pulses. Laser printing systems are highly depending on the appropriate combination of several design factors so as to become functional in a desired working range. The physical printing process involves multiple temperature set points at different places, precise electro-magnetic conditions, transfer of toner through certain pressures and layouts, and many other technical considerations. In the laser printing system there are several challenging issues and unknown disturbances. They originate from different sources, such as the printer itself (unknown phenomena appear, disturbances that are not foreseen, wear, contamination, failures, bugs), the environment of the system (power supply variations, temperature, humidity, vibrations), and the printing media (weight, coating, thermal properties, humidity characteristics, and initial temperature). These issues have a negative effect on the stability and performance of the laser printing system. The objective is to design a control scheme to achieve printing quality requirements and a high productivity. Good printing quality means that the fusing temperature should track a certain reference signal at different operating conditions. Based on the printing system behavior, we propose two different control schemes to cope with the large parameter variations and disturbances, namely, a Model Reference Adaptive Controller (MRAC) and a nonlinear (scheduled) observer-based output feedback control scheme. Both control techniques yield considerable performance improvements compared with the present industrial controller.

One of the major digital printing technologies used for production printing is dry-toner electrophotography. The main technical challenge is print quality and many researches have been done to improve it in the recent years. In our study, dry-toner color electrophotography was compared to conventional offset printing. A Xerox iGen3 press and a Heidelberg Speedmaster press were used. The substrates used were different uncoated and coated paper stocks. The GATF 11x17 Four-Color Test Form was printed on the papers by both printing presses. Print quality, such as color gamut, dot gain, print contrast, and trapping, were evaluated and compared. Higher dot gains were found on Speedmaster than on iGen3 except for black color. Higher print contrast values were found for iGen3 than for Speedmaster except for black color. Wider color gamuts were achieved on iGen3 than on Speedmaster, especially on uncoated papers. With high print quality, it is expected that more production printing will be done by dry-toner color electrophotography.

Nowadays, many domestic printing enterprises still rely on artificial visual means to weed out waste, labor-intensive, time-consuming, subjective factors serious influence, the test results not being uniform, especially with the improvement of printing speed, gradually unable to meet the needs of the production. In order to solve the problems in the conventional assay and promote the development of China's printing industry productivity, there is an urgent need to develop the quality of printing online full screen detection system, with the rapid development of modern printing technology, the objective is to test and evaluate. In this paper, machine vision inspection technology, digital image processing technology is used in order to achieve the online testing and feedback of print quality. Dynamic partitioning method is based on standard proofs and proofs of defective segmentation and matching. According to the type of image resolution and the desired accuracy of detecting the type of design image segmentation method, thereby performing the detection and analysis of the color information. Secondary identification defect classification technology is used to change the defect classification, and then display the corresponding defect types. Compared with the traditional printing quality, the high detection print quality inspection speed and precision requirements have been reached, thereby the overall quality of the printed product is improved.

Microvalve jetting, with its advantages of low cost, ease of operation, high printing speed, and ability to process living cells with high viability, has been primarily used for fabricating high-throughput drug-screening models, in vitro cellular structures for fundamental cell biology research, and cell-laden structures for regenerating tissues or organs in the human body after disease or trauma. This article provides an overview of microvalve jetting of biomaterials, including operational parameters. The jetting technologies covered are inkjet printing, microvalve jetting, and laser-assisted jetting. The parameters covered include nozzle size (nozzle inner diameter), pneumatic pressure, valve-opening time, and printing speed of microvalve jetting. Subsequently, the article discusses biomaterials for microvalve jetting in terms of biomaterial definition, required properties for a suitable biomaterial, currently used biomaterials, and cells and cellular structures. Additionally, applications of microvalve jetting in biomedical engineering are presented, which include cellular and RNA analysis, high-throughput drug screening, and tissue engineering.

The influence of wetting and drying during high-speed inkjet (HSI) printing on the time-dependent mechanical behavior of commercial HSI papers was investigated using a custom-built C-Impact tensile tester. In HSI printing the water based ink solvent penetrates into the paper while the colorants adhere onto the surface. We found that water strongly affected paper stiffness and strength already 0.1 s after wetting. Creep compliance and paper strain at a typical HSI printing input tension of 180 N/m are varying strongly during the different process steps of HSI printing. In order to achieve a good color registration and print quality, we thus recommend that the web tension should be dynamically controlled in each process step to prevent straining after wetting or shrinkage during drying.

Paper for ink jet printing has to obtain optimal printing runnability, printability, and printing quality Therefore, it must have some specific properties that ensure optimal drying time, mechanical stability of a print, and its light and water resistance. The paper surface should enable the printing ink to be dried as fast as possible. The aim of the applied research was to determine how an ink jet color print on paper changes with time immediately after printing, and how long it takes for the color print to stabilize. Color differences ΔE ab were measured that appeared on print after a certain amount of time with regards to values attained immediately after printing. The influence of paper on colorimetric properties and optical density of a print was analyzed by measuring some structural, surface, and sorption properties. The values attained show that the paper surface should enable wetting and ink penetration in paper structure. The biggest changes in colorimetric properties of the print became visible during 1 h after printing; however, color print finally stabilizes only after 96 h. Research results confirmed the importance of paper sorption properties for obtaining high-quality ink jet color prints.

Most formulations of metal inks comprise of a suspension of nanoparticles however, these suffer when printed by the formation of unwanted agglomeration. The exploration and optimisation of particle-free silver-complex ink is causing a strong demand for inkjet printing of these formulations over nanoparticle-based suspension inks. This is due to the enhanced printability and rapid conversion via thermal reduction into a conductive material, which can be utilised in electronics manufacture. We developed a silver-complex ink for ‘smart-clothing’ through inkjet printing. The high-quality printing - characterised by no satellite droplet formation and fast speed - is demonstrated upon polyester fabric by the formation of electrical circuitry using a thermal reduction process. Fabric printing is limited by good metal coverage and adhesion, which we demonstrate and improve on in the work by the application of a low temperature, atmospheric air plasma pre-treatment to the polyester surface, which improves printed silver density and coverage using a plasma device which is easy to operate and economic. Printed silver layer reduction and film crystallinity is characterised from high resolution scanning electron microscopy, and spectroscopy (Ultraviolet-visible and Raman) detailing growth mechanisms for high track feature conductivity, producing a low sheet resistivity of 1.378 ± 0.001 Ω/□ and by the lighting of a 1.9 V, 250 mA Light Emitting Device, highlighting its application for conductive features processing. • Conductive films on PET fabric. • Ink jet printing particle-free silver-complex ink. • Conductive thin Ag films, 1.378 ± 0.001 Ω/□. • Enhancement of printed density and coverage by atmospheric plasma pre-treatment.

Coatings based on hydroxypropylated starch (HPS) provide extraordinary print density with dye-based inkjet inks, but their suitability for pigment-based inks can be limited due to inadequate carrier medium (water) absorption and colorant fixation. In the present work, HPS-based coatings were tailored for both a pigmentbased and a dye-based ink by adding silicate minerals or acid clay (both Lewis and Brönstedt acid sites present in the acid clay). Substrate-ink interaction and colorant distribution were investigated via uncoated gloss and print quality indicators such as print density, ink bleeding tendency and delta gloss after printing with desktop printers. Three-dimensional z-stack CLSM images taken from printed samples revealed substantial differences in ink holdout and penetration characteristics between the studied materials. Pigment-filled HPS coatings showed up to 60% increase in print density compared to uncoated reference substrate and an increase of up to 35% compared to plain HPS coating with dyebased inks. In case of pigment-based ink, the increase was 17% between plain HPS coating and acid-clay-filled HPS coating. In addition, a combination of HPS and silicate mineral decreased ink bleeding substantially, but lower print gloss compared to substrate initial gloss was observed with the majority of experimental coatings. It was found that the pigment type affects substantially the unprinted gloss, which is naturally high in the case of pure HPS coating, but also the observed drastic difference in substrate permeability may explain the differences in print quality. The findings suggest that coating morphology, together with chemical interactions between starch and mineral and coated substrate and ink, has a key role in achieving high gloss and good print quality.